Thu, 26 Mar 2009 08:51:32 -0700
6822263: G1: JVMTI heap iteration fails
Summary: Make object_iterate() traverse the perm gen
Reviewed-by: apetrusenko, tonyp
1 /*
2 * Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 #include "incls/_precompiled.incl"
26 #include "incls/_g1CollectedHeap.cpp.incl"
28 // turn it on so that the contents of the young list (scan-only /
29 // to-be-collected) are printed at "strategic" points before / during
30 // / after the collection --- this is useful for debugging
31 #define SCAN_ONLY_VERBOSE 0
32 // CURRENT STATUS
33 // This file is under construction. Search for "FIXME".
35 // INVARIANTS/NOTES
36 //
37 // All allocation activity covered by the G1CollectedHeap interface is
38 // serialized by acquiring the HeapLock. This happens in
39 // mem_allocate_work, which all such allocation functions call.
40 // (Note that this does not apply to TLAB allocation, which is not part
41 // of this interface: it is done by clients of this interface.)
43 // Local to this file.
45 class RefineCardTableEntryClosure: public CardTableEntryClosure {
46 SuspendibleThreadSet* _sts;
47 G1RemSet* _g1rs;
48 ConcurrentG1Refine* _cg1r;
49 bool _concurrent;
50 public:
51 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
52 G1RemSet* g1rs,
53 ConcurrentG1Refine* cg1r) :
54 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
55 {}
56 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
57 _g1rs->concurrentRefineOneCard(card_ptr, worker_i);
58 if (_concurrent && _sts->should_yield()) {
59 // Caller will actually yield.
60 return false;
61 }
62 // Otherwise, we finished successfully; return true.
63 return true;
64 }
65 void set_concurrent(bool b) { _concurrent = b; }
66 };
69 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
70 int _calls;
71 G1CollectedHeap* _g1h;
72 CardTableModRefBS* _ctbs;
73 int _histo[256];
74 public:
75 ClearLoggedCardTableEntryClosure() :
76 _calls(0)
77 {
78 _g1h = G1CollectedHeap::heap();
79 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
80 for (int i = 0; i < 256; i++) _histo[i] = 0;
81 }
82 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
83 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
84 _calls++;
85 unsigned char* ujb = (unsigned char*)card_ptr;
86 int ind = (int)(*ujb);
87 _histo[ind]++;
88 *card_ptr = -1;
89 }
90 return true;
91 }
92 int calls() { return _calls; }
93 void print_histo() {
94 gclog_or_tty->print_cr("Card table value histogram:");
95 for (int i = 0; i < 256; i++) {
96 if (_histo[i] != 0) {
97 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
98 }
99 }
100 }
101 };
103 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
104 int _calls;
105 G1CollectedHeap* _g1h;
106 CardTableModRefBS* _ctbs;
107 public:
108 RedirtyLoggedCardTableEntryClosure() :
109 _calls(0)
110 {
111 _g1h = G1CollectedHeap::heap();
112 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
113 }
114 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
115 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
116 _calls++;
117 *card_ptr = 0;
118 }
119 return true;
120 }
121 int calls() { return _calls; }
122 };
124 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
125 public:
126 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
127 *card_ptr = CardTableModRefBS::dirty_card_val();
128 return true;
129 }
130 };
132 YoungList::YoungList(G1CollectedHeap* g1h)
133 : _g1h(g1h), _head(NULL),
134 _scan_only_head(NULL), _scan_only_tail(NULL), _curr_scan_only(NULL),
135 _length(0), _scan_only_length(0),
136 _last_sampled_rs_lengths(0),
137 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
138 {
139 guarantee( check_list_empty(false), "just making sure..." );
140 }
142 void YoungList::push_region(HeapRegion *hr) {
143 assert(!hr->is_young(), "should not already be young");
144 assert(hr->get_next_young_region() == NULL, "cause it should!");
146 hr->set_next_young_region(_head);
147 _head = hr;
149 hr->set_young();
150 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
151 ++_length;
152 }
154 void YoungList::add_survivor_region(HeapRegion* hr) {
155 assert(hr->is_survivor(), "should be flagged as survivor region");
156 assert(hr->get_next_young_region() == NULL, "cause it should!");
158 hr->set_next_young_region(_survivor_head);
159 if (_survivor_head == NULL) {
160 _survivor_tail = hr;
161 }
162 _survivor_head = hr;
164 ++_survivor_length;
165 }
167 HeapRegion* YoungList::pop_region() {
168 while (_head != NULL) {
169 assert( length() > 0, "list should not be empty" );
170 HeapRegion* ret = _head;
171 _head = ret->get_next_young_region();
172 ret->set_next_young_region(NULL);
173 --_length;
174 assert(ret->is_young(), "region should be very young");
176 // Replace 'Survivor' region type with 'Young'. So the region will
177 // be treated as a young region and will not be 'confused' with
178 // newly created survivor regions.
179 if (ret->is_survivor()) {
180 ret->set_young();
181 }
183 if (!ret->is_scan_only()) {
184 return ret;
185 }
187 // scan-only, we'll add it to the scan-only list
188 if (_scan_only_tail == NULL) {
189 guarantee( _scan_only_head == NULL, "invariant" );
191 _scan_only_head = ret;
192 _curr_scan_only = ret;
193 } else {
194 guarantee( _scan_only_head != NULL, "invariant" );
195 _scan_only_tail->set_next_young_region(ret);
196 }
197 guarantee( ret->get_next_young_region() == NULL, "invariant" );
198 _scan_only_tail = ret;
200 // no need to be tagged as scan-only any more
201 ret->set_young();
203 ++_scan_only_length;
204 }
205 assert( length() == 0, "list should be empty" );
206 return NULL;
207 }
209 void YoungList::empty_list(HeapRegion* list) {
210 while (list != NULL) {
211 HeapRegion* next = list->get_next_young_region();
212 list->set_next_young_region(NULL);
213 list->uninstall_surv_rate_group();
214 list->set_not_young();
215 list = next;
216 }
217 }
219 void YoungList::empty_list() {
220 assert(check_list_well_formed(), "young list should be well formed");
222 empty_list(_head);
223 _head = NULL;
224 _length = 0;
226 empty_list(_scan_only_head);
227 _scan_only_head = NULL;
228 _scan_only_tail = NULL;
229 _scan_only_length = 0;
230 _curr_scan_only = NULL;
232 empty_list(_survivor_head);
233 _survivor_head = NULL;
234 _survivor_tail = NULL;
235 _survivor_length = 0;
237 _last_sampled_rs_lengths = 0;
239 assert(check_list_empty(false), "just making sure...");
240 }
242 bool YoungList::check_list_well_formed() {
243 bool ret = true;
245 size_t length = 0;
246 HeapRegion* curr = _head;
247 HeapRegion* last = NULL;
248 while (curr != NULL) {
249 if (!curr->is_young() || curr->is_scan_only()) {
250 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
251 "incorrectly tagged (%d, %d)",
252 curr->bottom(), curr->end(),
253 curr->is_young(), curr->is_scan_only());
254 ret = false;
255 }
256 ++length;
257 last = curr;
258 curr = curr->get_next_young_region();
259 }
260 ret = ret && (length == _length);
262 if (!ret) {
263 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
264 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
265 length, _length);
266 }
268 bool scan_only_ret = true;
269 length = 0;
270 curr = _scan_only_head;
271 last = NULL;
272 while (curr != NULL) {
273 if (!curr->is_young() || curr->is_scan_only()) {
274 gclog_or_tty->print_cr("### SCAN-ONLY REGION "PTR_FORMAT"-"PTR_FORMAT" "
275 "incorrectly tagged (%d, %d)",
276 curr->bottom(), curr->end(),
277 curr->is_young(), curr->is_scan_only());
278 scan_only_ret = false;
279 }
280 ++length;
281 last = curr;
282 curr = curr->get_next_young_region();
283 }
284 scan_only_ret = scan_only_ret && (length == _scan_only_length);
286 if ( (last != _scan_only_tail) ||
287 (_scan_only_head == NULL && _scan_only_tail != NULL) ||
288 (_scan_only_head != NULL && _scan_only_tail == NULL) ) {
289 gclog_or_tty->print_cr("## _scan_only_tail is set incorrectly");
290 scan_only_ret = false;
291 }
293 if (_curr_scan_only != NULL && _curr_scan_only != _scan_only_head) {
294 gclog_or_tty->print_cr("### _curr_scan_only is set incorrectly");
295 scan_only_ret = false;
296 }
298 if (!scan_only_ret) {
299 gclog_or_tty->print_cr("### SCAN-ONLY LIST seems not well formed!");
300 gclog_or_tty->print_cr("### list has %d entries, _scan_only_length is %d",
301 length, _scan_only_length);
302 }
304 return ret && scan_only_ret;
305 }
307 bool YoungList::check_list_empty(bool ignore_scan_only_list,
308 bool check_sample) {
309 bool ret = true;
311 if (_length != 0) {
312 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
313 _length);
314 ret = false;
315 }
316 if (check_sample && _last_sampled_rs_lengths != 0) {
317 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
318 ret = false;
319 }
320 if (_head != NULL) {
321 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
322 ret = false;
323 }
324 if (!ret) {
325 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
326 }
328 if (ignore_scan_only_list)
329 return ret;
331 bool scan_only_ret = true;
332 if (_scan_only_length != 0) {
333 gclog_or_tty->print_cr("### SCAN-ONLY LIST should have 0 length, not %d",
334 _scan_only_length);
335 scan_only_ret = false;
336 }
337 if (_scan_only_head != NULL) {
338 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL head");
339 scan_only_ret = false;
340 }
341 if (_scan_only_tail != NULL) {
342 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL tail");
343 scan_only_ret = false;
344 }
345 if (!scan_only_ret) {
346 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not seem empty");
347 }
349 return ret && scan_only_ret;
350 }
352 void
353 YoungList::rs_length_sampling_init() {
354 _sampled_rs_lengths = 0;
355 _curr = _head;
356 }
358 bool
359 YoungList::rs_length_sampling_more() {
360 return _curr != NULL;
361 }
363 void
364 YoungList::rs_length_sampling_next() {
365 assert( _curr != NULL, "invariant" );
366 _sampled_rs_lengths += _curr->rem_set()->occupied();
367 _curr = _curr->get_next_young_region();
368 if (_curr == NULL) {
369 _last_sampled_rs_lengths = _sampled_rs_lengths;
370 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
371 }
372 }
374 void
375 YoungList::reset_auxilary_lists() {
376 // We could have just "moved" the scan-only list to the young list.
377 // However, the scan-only list is ordered according to the region
378 // age in descending order, so, by moving one entry at a time, we
379 // ensure that it is recreated in ascending order.
381 guarantee( is_empty(), "young list should be empty" );
382 assert(check_list_well_formed(), "young list should be well formed");
384 // Add survivor regions to SurvRateGroup.
385 _g1h->g1_policy()->note_start_adding_survivor_regions();
386 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
387 for (HeapRegion* curr = _survivor_head;
388 curr != NULL;
389 curr = curr->get_next_young_region()) {
390 _g1h->g1_policy()->set_region_survivors(curr);
391 }
392 _g1h->g1_policy()->note_stop_adding_survivor_regions();
394 if (_survivor_head != NULL) {
395 _head = _survivor_head;
396 _length = _survivor_length + _scan_only_length;
397 _survivor_tail->set_next_young_region(_scan_only_head);
398 } else {
399 _head = _scan_only_head;
400 _length = _scan_only_length;
401 }
403 for (HeapRegion* curr = _scan_only_head;
404 curr != NULL;
405 curr = curr->get_next_young_region()) {
406 curr->recalculate_age_in_surv_rate_group();
407 }
408 _scan_only_head = NULL;
409 _scan_only_tail = NULL;
410 _scan_only_length = 0;
411 _curr_scan_only = NULL;
413 _survivor_head = NULL;
414 _survivor_tail = NULL;
415 _survivor_length = 0;
416 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
418 assert(check_list_well_formed(), "young list should be well formed");
419 }
421 void YoungList::print() {
422 HeapRegion* lists[] = {_head, _scan_only_head, _survivor_head};
423 const char* names[] = {"YOUNG", "SCAN-ONLY", "SURVIVOR"};
425 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
426 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
427 HeapRegion *curr = lists[list];
428 if (curr == NULL)
429 gclog_or_tty->print_cr(" empty");
430 while (curr != NULL) {
431 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
432 "age: %4d, y: %d, s-o: %d, surv: %d",
433 curr->bottom(), curr->end(),
434 curr->top(),
435 curr->prev_top_at_mark_start(),
436 curr->next_top_at_mark_start(),
437 curr->top_at_conc_mark_count(),
438 curr->age_in_surv_rate_group_cond(),
439 curr->is_young(),
440 curr->is_scan_only(),
441 curr->is_survivor());
442 curr = curr->get_next_young_region();
443 }
444 }
446 gclog_or_tty->print_cr("");
447 }
449 void G1CollectedHeap::stop_conc_gc_threads() {
450 _cg1r->cg1rThread()->stop();
451 _czft->stop();
452 _cmThread->stop();
453 }
456 void G1CollectedHeap::check_ct_logs_at_safepoint() {
457 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
458 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
460 // Count the dirty cards at the start.
461 CountNonCleanMemRegionClosure count1(this);
462 ct_bs->mod_card_iterate(&count1);
463 int orig_count = count1.n();
465 // First clear the logged cards.
466 ClearLoggedCardTableEntryClosure clear;
467 dcqs.set_closure(&clear);
468 dcqs.apply_closure_to_all_completed_buffers();
469 dcqs.iterate_closure_all_threads(false);
470 clear.print_histo();
472 // Now ensure that there's no dirty cards.
473 CountNonCleanMemRegionClosure count2(this);
474 ct_bs->mod_card_iterate(&count2);
475 if (count2.n() != 0) {
476 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
477 count2.n(), orig_count);
478 }
479 guarantee(count2.n() == 0, "Card table should be clean.");
481 RedirtyLoggedCardTableEntryClosure redirty;
482 JavaThread::dirty_card_queue_set().set_closure(&redirty);
483 dcqs.apply_closure_to_all_completed_buffers();
484 dcqs.iterate_closure_all_threads(false);
485 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
486 clear.calls(), orig_count);
487 guarantee(redirty.calls() == clear.calls(),
488 "Or else mechanism is broken.");
490 CountNonCleanMemRegionClosure count3(this);
491 ct_bs->mod_card_iterate(&count3);
492 if (count3.n() != orig_count) {
493 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
494 orig_count, count3.n());
495 guarantee(count3.n() >= orig_count, "Should have restored them all.");
496 }
498 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
499 }
501 // Private class members.
503 G1CollectedHeap* G1CollectedHeap::_g1h;
505 // Private methods.
507 // Finds a HeapRegion that can be used to allocate a given size of block.
510 HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size,
511 bool do_expand,
512 bool zero_filled) {
513 ConcurrentZFThread::note_region_alloc();
514 HeapRegion* res = alloc_free_region_from_lists(zero_filled);
515 if (res == NULL && do_expand) {
516 expand(word_size * HeapWordSize);
517 res = alloc_free_region_from_lists(zero_filled);
518 assert(res == NULL ||
519 (!res->isHumongous() &&
520 (!zero_filled ||
521 res->zero_fill_state() == HeapRegion::Allocated)),
522 "Alloc Regions must be zero filled (and non-H)");
523 }
524 if (res != NULL && res->is_empty()) _free_regions--;
525 assert(res == NULL ||
526 (!res->isHumongous() &&
527 (!zero_filled ||
528 res->zero_fill_state() == HeapRegion::Allocated)),
529 "Non-young alloc Regions must be zero filled (and non-H)");
531 if (G1TraceRegions) {
532 if (res != NULL) {
533 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
534 "top "PTR_FORMAT,
535 res->hrs_index(), res->bottom(), res->end(), res->top());
536 }
537 }
539 return res;
540 }
542 HeapRegion* G1CollectedHeap::newAllocRegionWithExpansion(int purpose,
543 size_t word_size,
544 bool zero_filled) {
545 HeapRegion* alloc_region = NULL;
546 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
547 alloc_region = newAllocRegion_work(word_size, true, zero_filled);
548 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
549 alloc_region->set_survivor();
550 }
551 ++_gc_alloc_region_counts[purpose];
552 } else {
553 g1_policy()->note_alloc_region_limit_reached(purpose);
554 }
555 return alloc_region;
556 }
558 // If could fit into free regions w/o expansion, try.
559 // Otherwise, if can expand, do so.
560 // Otherwise, if using ex regions might help, try with ex given back.
561 HeapWord* G1CollectedHeap::humongousObjAllocate(size_t word_size) {
562 assert(regions_accounted_for(), "Region leakage!");
564 // We can't allocate H regions while cleanupComplete is running, since
565 // some of the regions we find to be empty might not yet be added to the
566 // unclean list. (If we're already at a safepoint, this call is
567 // unnecessary, not to mention wrong.)
568 if (!SafepointSynchronize::is_at_safepoint())
569 wait_for_cleanup_complete();
571 size_t num_regions =
572 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
574 // Special case if < one region???
576 // Remember the ft size.
577 size_t x_size = expansion_regions();
579 HeapWord* res = NULL;
580 bool eliminated_allocated_from_lists = false;
582 // Can the allocation potentially fit in the free regions?
583 if (free_regions() >= num_regions) {
584 res = _hrs->obj_allocate(word_size);
585 }
586 if (res == NULL) {
587 // Try expansion.
588 size_t fs = _hrs->free_suffix();
589 if (fs + x_size >= num_regions) {
590 expand((num_regions - fs) * HeapRegion::GrainBytes);
591 res = _hrs->obj_allocate(word_size);
592 assert(res != NULL, "This should have worked.");
593 } else {
594 // Expansion won't help. Are there enough free regions if we get rid
595 // of reservations?
596 size_t avail = free_regions();
597 if (avail >= num_regions) {
598 res = _hrs->obj_allocate(word_size);
599 if (res != NULL) {
600 remove_allocated_regions_from_lists();
601 eliminated_allocated_from_lists = true;
602 }
603 }
604 }
605 }
606 if (res != NULL) {
607 // Increment by the number of regions allocated.
608 // FIXME: Assumes regions all of size GrainBytes.
609 #ifndef PRODUCT
610 mr_bs()->verify_clean_region(MemRegion(res, res + num_regions *
611 HeapRegion::GrainWords));
612 #endif
613 if (!eliminated_allocated_from_lists)
614 remove_allocated_regions_from_lists();
615 _summary_bytes_used += word_size * HeapWordSize;
616 _free_regions -= num_regions;
617 _num_humongous_regions += (int) num_regions;
618 }
619 assert(regions_accounted_for(), "Region Leakage");
620 return res;
621 }
623 HeapWord*
624 G1CollectedHeap::attempt_allocation_slow(size_t word_size,
625 bool permit_collection_pause) {
626 HeapWord* res = NULL;
627 HeapRegion* allocated_young_region = NULL;
629 assert( SafepointSynchronize::is_at_safepoint() ||
630 Heap_lock->owned_by_self(), "pre condition of the call" );
632 if (isHumongous(word_size)) {
633 // Allocation of a humongous object can, in a sense, complete a
634 // partial region, if the previous alloc was also humongous, and
635 // caused the test below to succeed.
636 if (permit_collection_pause)
637 do_collection_pause_if_appropriate(word_size);
638 res = humongousObjAllocate(word_size);
639 assert(_cur_alloc_region == NULL
640 || !_cur_alloc_region->isHumongous(),
641 "Prevent a regression of this bug.");
643 } else {
644 // We may have concurrent cleanup working at the time. Wait for it
645 // to complete. In the future we would probably want to make the
646 // concurrent cleanup truly concurrent by decoupling it from the
647 // allocation.
648 if (!SafepointSynchronize::is_at_safepoint())
649 wait_for_cleanup_complete();
650 // If we do a collection pause, this will be reset to a non-NULL
651 // value. If we don't, nulling here ensures that we allocate a new
652 // region below.
653 if (_cur_alloc_region != NULL) {
654 // We're finished with the _cur_alloc_region.
655 _summary_bytes_used += _cur_alloc_region->used();
656 _cur_alloc_region = NULL;
657 }
658 assert(_cur_alloc_region == NULL, "Invariant.");
659 // Completion of a heap region is perhaps a good point at which to do
660 // a collection pause.
661 if (permit_collection_pause)
662 do_collection_pause_if_appropriate(word_size);
663 // Make sure we have an allocation region available.
664 if (_cur_alloc_region == NULL) {
665 if (!SafepointSynchronize::is_at_safepoint())
666 wait_for_cleanup_complete();
667 bool next_is_young = should_set_young_locked();
668 // If the next region is not young, make sure it's zero-filled.
669 _cur_alloc_region = newAllocRegion(word_size, !next_is_young);
670 if (_cur_alloc_region != NULL) {
671 _summary_bytes_used -= _cur_alloc_region->used();
672 if (next_is_young) {
673 set_region_short_lived_locked(_cur_alloc_region);
674 allocated_young_region = _cur_alloc_region;
675 }
676 }
677 }
678 assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
679 "Prevent a regression of this bug.");
681 // Now retry the allocation.
682 if (_cur_alloc_region != NULL) {
683 res = _cur_alloc_region->allocate(word_size);
684 }
685 }
687 // NOTE: fails frequently in PRT
688 assert(regions_accounted_for(), "Region leakage!");
690 if (res != NULL) {
691 if (!SafepointSynchronize::is_at_safepoint()) {
692 assert( permit_collection_pause, "invariant" );
693 assert( Heap_lock->owned_by_self(), "invariant" );
694 Heap_lock->unlock();
695 }
697 if (allocated_young_region != NULL) {
698 HeapRegion* hr = allocated_young_region;
699 HeapWord* bottom = hr->bottom();
700 HeapWord* end = hr->end();
701 MemRegion mr(bottom, end);
702 ((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr);
703 }
704 }
706 assert( SafepointSynchronize::is_at_safepoint() ||
707 (res == NULL && Heap_lock->owned_by_self()) ||
708 (res != NULL && !Heap_lock->owned_by_self()),
709 "post condition of the call" );
711 return res;
712 }
714 HeapWord*
715 G1CollectedHeap::mem_allocate(size_t word_size,
716 bool is_noref,
717 bool is_tlab,
718 bool* gc_overhead_limit_was_exceeded) {
719 debug_only(check_for_valid_allocation_state());
720 assert(no_gc_in_progress(), "Allocation during gc not allowed");
721 HeapWord* result = NULL;
723 // Loop until the allocation is satisified,
724 // or unsatisfied after GC.
725 for (int try_count = 1; /* return or throw */; try_count += 1) {
726 int gc_count_before;
727 {
728 Heap_lock->lock();
729 result = attempt_allocation(word_size);
730 if (result != NULL) {
731 // attempt_allocation should have unlocked the heap lock
732 assert(is_in(result), "result not in heap");
733 return result;
734 }
735 // Read the gc count while the heap lock is held.
736 gc_count_before = SharedHeap::heap()->total_collections();
737 Heap_lock->unlock();
738 }
740 // Create the garbage collection operation...
741 VM_G1CollectForAllocation op(word_size,
742 gc_count_before);
744 // ...and get the VM thread to execute it.
745 VMThread::execute(&op);
746 if (op.prologue_succeeded()) {
747 result = op.result();
748 assert(result == NULL || is_in(result), "result not in heap");
749 return result;
750 }
752 // Give a warning if we seem to be looping forever.
753 if ((QueuedAllocationWarningCount > 0) &&
754 (try_count % QueuedAllocationWarningCount == 0)) {
755 warning("G1CollectedHeap::mem_allocate_work retries %d times",
756 try_count);
757 }
758 }
759 }
761 void G1CollectedHeap::abandon_cur_alloc_region() {
762 if (_cur_alloc_region != NULL) {
763 // We're finished with the _cur_alloc_region.
764 if (_cur_alloc_region->is_empty()) {
765 _free_regions++;
766 free_region(_cur_alloc_region);
767 } else {
768 _summary_bytes_used += _cur_alloc_region->used();
769 }
770 _cur_alloc_region = NULL;
771 }
772 }
774 void G1CollectedHeap::abandon_gc_alloc_regions() {
775 // first, make sure that the GC alloc region list is empty (it should!)
776 assert(_gc_alloc_region_list == NULL, "invariant");
777 release_gc_alloc_regions(true /* totally */);
778 }
780 class PostMCRemSetClearClosure: public HeapRegionClosure {
781 ModRefBarrierSet* _mr_bs;
782 public:
783 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
784 bool doHeapRegion(HeapRegion* r) {
785 r->reset_gc_time_stamp();
786 if (r->continuesHumongous())
787 return false;
788 HeapRegionRemSet* hrrs = r->rem_set();
789 if (hrrs != NULL) hrrs->clear();
790 // You might think here that we could clear just the cards
791 // corresponding to the used region. But no: if we leave a dirty card
792 // in a region we might allocate into, then it would prevent that card
793 // from being enqueued, and cause it to be missed.
794 // Re: the performance cost: we shouldn't be doing full GC anyway!
795 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
796 return false;
797 }
798 };
801 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
802 ModRefBarrierSet* _mr_bs;
803 public:
804 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
805 bool doHeapRegion(HeapRegion* r) {
806 if (r->continuesHumongous()) return false;
807 if (r->used_region().word_size() != 0) {
808 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
809 }
810 return false;
811 }
812 };
814 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
815 G1CollectedHeap* _g1h;
816 UpdateRSOopClosure _cl;
817 int _worker_i;
818 public:
819 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
820 _cl(g1->g1_rem_set()->as_HRInto_G1RemSet(), worker_i),
821 _worker_i(worker_i),
822 _g1h(g1)
823 { }
824 bool doHeapRegion(HeapRegion* r) {
825 if (!r->continuesHumongous()) {
826 _cl.set_from(r);
827 r->oop_iterate(&_cl);
828 }
829 return false;
830 }
831 };
833 class ParRebuildRSTask: public AbstractGangTask {
834 G1CollectedHeap* _g1;
835 public:
836 ParRebuildRSTask(G1CollectedHeap* g1)
837 : AbstractGangTask("ParRebuildRSTask"),
838 _g1(g1)
839 { }
841 void work(int i) {
842 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
843 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
844 HeapRegion::RebuildRSClaimValue);
845 }
846 };
848 void G1CollectedHeap::do_collection(bool full, bool clear_all_soft_refs,
849 size_t word_size) {
850 ResourceMark rm;
852 if (full && DisableExplicitGC) {
853 gclog_or_tty->print("\n\n\nDisabling Explicit GC\n\n\n");
854 return;
855 }
857 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
858 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
860 if (GC_locker::is_active()) {
861 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
862 }
864 {
865 IsGCActiveMark x;
867 // Timing
868 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
869 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
870 TraceTime t(full ? "Full GC (System.gc())" : "Full GC", PrintGC, true, gclog_or_tty);
872 double start = os::elapsedTime();
873 GCOverheadReporter::recordSTWStart(start);
874 g1_policy()->record_full_collection_start();
876 gc_prologue(true);
877 increment_total_collections();
879 size_t g1h_prev_used = used();
880 assert(used() == recalculate_used(), "Should be equal");
882 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
883 HandleMark hm; // Discard invalid handles created during verification
884 prepare_for_verify();
885 gclog_or_tty->print(" VerifyBeforeGC:");
886 Universe::verify(true);
887 }
888 assert(regions_accounted_for(), "Region leakage!");
890 COMPILER2_PRESENT(DerivedPointerTable::clear());
892 // We want to discover references, but not process them yet.
893 // This mode is disabled in
894 // instanceRefKlass::process_discovered_references if the
895 // generation does some collection work, or
896 // instanceRefKlass::enqueue_discovered_references if the
897 // generation returns without doing any work.
898 ref_processor()->disable_discovery();
899 ref_processor()->abandon_partial_discovery();
900 ref_processor()->verify_no_references_recorded();
902 // Abandon current iterations of concurrent marking and concurrent
903 // refinement, if any are in progress.
904 concurrent_mark()->abort();
906 // Make sure we'll choose a new allocation region afterwards.
907 abandon_cur_alloc_region();
908 abandon_gc_alloc_regions();
909 assert(_cur_alloc_region == NULL, "Invariant.");
910 g1_rem_set()->as_HRInto_G1RemSet()->cleanupHRRS();
911 tear_down_region_lists();
912 set_used_regions_to_need_zero_fill();
913 if (g1_policy()->in_young_gc_mode()) {
914 empty_young_list();
915 g1_policy()->set_full_young_gcs(true);
916 }
918 // Temporarily make reference _discovery_ single threaded (non-MT).
919 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
921 // Temporarily make refs discovery atomic
922 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
924 // Temporarily clear _is_alive_non_header
925 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
927 ref_processor()->enable_discovery();
928 ref_processor()->setup_policy(clear_all_soft_refs);
930 // Do collection work
931 {
932 HandleMark hm; // Discard invalid handles created during gc
933 G1MarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);
934 }
935 // Because freeing humongous regions may have added some unclean
936 // regions, it is necessary to tear down again before rebuilding.
937 tear_down_region_lists();
938 rebuild_region_lists();
940 _summary_bytes_used = recalculate_used();
942 ref_processor()->enqueue_discovered_references();
944 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
946 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
947 HandleMark hm; // Discard invalid handles created during verification
948 gclog_or_tty->print(" VerifyAfterGC:");
949 prepare_for_verify();
950 Universe::verify(false);
951 }
952 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
954 reset_gc_time_stamp();
955 // Since everything potentially moved, we will clear all remembered
956 // sets, and clear all cards. Later we will rebuild remebered
957 // sets. We will also reset the GC time stamps of the regions.
958 PostMCRemSetClearClosure rs_clear(mr_bs());
959 heap_region_iterate(&rs_clear);
961 // Resize the heap if necessary.
962 resize_if_necessary_after_full_collection(full ? 0 : word_size);
964 if (_cg1r->use_cache()) {
965 _cg1r->clear_and_record_card_counts();
966 _cg1r->clear_hot_cache();
967 }
969 // Rebuild remembered sets of all regions.
970 if (ParallelGCThreads > 0) {
971 ParRebuildRSTask rebuild_rs_task(this);
972 assert(check_heap_region_claim_values(
973 HeapRegion::InitialClaimValue), "sanity check");
974 set_par_threads(workers()->total_workers());
975 workers()->run_task(&rebuild_rs_task);
976 set_par_threads(0);
977 assert(check_heap_region_claim_values(
978 HeapRegion::RebuildRSClaimValue), "sanity check");
979 reset_heap_region_claim_values();
980 } else {
981 RebuildRSOutOfRegionClosure rebuild_rs(this);
982 heap_region_iterate(&rebuild_rs);
983 }
985 if (PrintGC) {
986 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
987 }
989 if (true) { // FIXME
990 // Ask the permanent generation to adjust size for full collections
991 perm()->compute_new_size();
992 }
994 double end = os::elapsedTime();
995 GCOverheadReporter::recordSTWEnd(end);
996 g1_policy()->record_full_collection_end();
998 #ifdef TRACESPINNING
999 ParallelTaskTerminator::print_termination_counts();
1000 #endif
1002 gc_epilogue(true);
1004 // Abandon concurrent refinement. This must happen last: in the
1005 // dirty-card logging system, some cards may be dirty by weak-ref
1006 // processing, and may be enqueued. But the whole card table is
1007 // dirtied, so this should abandon those logs, and set "do_traversal"
1008 // to true.
1009 concurrent_g1_refine()->set_pya_restart();
1010 assert(!G1DeferredRSUpdate
1011 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1012 assert(regions_accounted_for(), "Region leakage!");
1013 }
1015 if (g1_policy()->in_young_gc_mode()) {
1016 _young_list->reset_sampled_info();
1017 assert( check_young_list_empty(false, false),
1018 "young list should be empty at this point");
1019 }
1020 }
1022 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1023 do_collection(true, clear_all_soft_refs, 0);
1024 }
1026 // This code is mostly copied from TenuredGeneration.
1027 void
1028 G1CollectedHeap::
1029 resize_if_necessary_after_full_collection(size_t word_size) {
1030 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1032 // Include the current allocation, if any, and bytes that will be
1033 // pre-allocated to support collections, as "used".
1034 const size_t used_after_gc = used();
1035 const size_t capacity_after_gc = capacity();
1036 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1038 // We don't have floating point command-line arguments
1039 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100;
1040 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1041 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
1042 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1044 size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage);
1045 size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage);
1047 // Don't shrink less than the initial size.
1048 minimum_desired_capacity =
1049 MAX2(minimum_desired_capacity,
1050 collector_policy()->initial_heap_byte_size());
1051 maximum_desired_capacity =
1052 MAX2(maximum_desired_capacity,
1053 collector_policy()->initial_heap_byte_size());
1055 // We are failing here because minimum_desired_capacity is
1056 assert(used_after_gc <= minimum_desired_capacity, "sanity check");
1057 assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check");
1059 if (PrintGC && Verbose) {
1060 const double free_percentage = ((double)free_after_gc) / capacity();
1061 gclog_or_tty->print_cr("Computing new size after full GC ");
1062 gclog_or_tty->print_cr(" "
1063 " minimum_free_percentage: %6.2f",
1064 minimum_free_percentage);
1065 gclog_or_tty->print_cr(" "
1066 " maximum_free_percentage: %6.2f",
1067 maximum_free_percentage);
1068 gclog_or_tty->print_cr(" "
1069 " capacity: %6.1fK"
1070 " minimum_desired_capacity: %6.1fK"
1071 " maximum_desired_capacity: %6.1fK",
1072 capacity() / (double) K,
1073 minimum_desired_capacity / (double) K,
1074 maximum_desired_capacity / (double) K);
1075 gclog_or_tty->print_cr(" "
1076 " free_after_gc : %6.1fK"
1077 " used_after_gc : %6.1fK",
1078 free_after_gc / (double) K,
1079 used_after_gc / (double) K);
1080 gclog_or_tty->print_cr(" "
1081 " free_percentage: %6.2f",
1082 free_percentage);
1083 }
1084 if (capacity() < minimum_desired_capacity) {
1085 // Don't expand unless it's significant
1086 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1087 expand(expand_bytes);
1088 if (PrintGC && Verbose) {
1089 gclog_or_tty->print_cr(" expanding:"
1090 " minimum_desired_capacity: %6.1fK"
1091 " expand_bytes: %6.1fK",
1092 minimum_desired_capacity / (double) K,
1093 expand_bytes / (double) K);
1094 }
1096 // No expansion, now see if we want to shrink
1097 } else if (capacity() > maximum_desired_capacity) {
1098 // Capacity too large, compute shrinking size
1099 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1100 shrink(shrink_bytes);
1101 if (PrintGC && Verbose) {
1102 gclog_or_tty->print_cr(" "
1103 " shrinking:"
1104 " initSize: %.1fK"
1105 " maximum_desired_capacity: %.1fK",
1106 collector_policy()->initial_heap_byte_size() / (double) K,
1107 maximum_desired_capacity / (double) K);
1108 gclog_or_tty->print_cr(" "
1109 " shrink_bytes: %.1fK",
1110 shrink_bytes / (double) K);
1111 }
1112 }
1113 }
1116 HeapWord*
1117 G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
1118 HeapWord* result = NULL;
1120 // In a G1 heap, we're supposed to keep allocation from failing by
1121 // incremental pauses. Therefore, at least for now, we'll favor
1122 // expansion over collection. (This might change in the future if we can
1123 // do something smarter than full collection to satisfy a failed alloc.)
1125 result = expand_and_allocate(word_size);
1126 if (result != NULL) {
1127 assert(is_in(result), "result not in heap");
1128 return result;
1129 }
1131 // OK, I guess we have to try collection.
1133 do_collection(false, false, word_size);
1135 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1137 if (result != NULL) {
1138 assert(is_in(result), "result not in heap");
1139 return result;
1140 }
1142 // Try collecting soft references.
1143 do_collection(false, true, word_size);
1144 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1145 if (result != NULL) {
1146 assert(is_in(result), "result not in heap");
1147 return result;
1148 }
1150 // What else? We might try synchronous finalization later. If the total
1151 // space available is large enough for the allocation, then a more
1152 // complete compaction phase than we've tried so far might be
1153 // appropriate.
1154 return NULL;
1155 }
1157 // Attempting to expand the heap sufficiently
1158 // to support an allocation of the given "word_size". If
1159 // successful, perform the allocation and return the address of the
1160 // allocated block, or else "NULL".
1162 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1163 size_t expand_bytes = word_size * HeapWordSize;
1164 if (expand_bytes < MinHeapDeltaBytes) {
1165 expand_bytes = MinHeapDeltaBytes;
1166 }
1167 expand(expand_bytes);
1168 assert(regions_accounted_for(), "Region leakage!");
1169 HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
1170 return result;
1171 }
1173 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
1174 size_t pre_used = 0;
1175 size_t cleared_h_regions = 0;
1176 size_t freed_regions = 0;
1177 UncleanRegionList local_list;
1178 free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
1179 freed_regions, &local_list);
1181 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
1182 &local_list);
1183 return pre_used;
1184 }
1186 void
1187 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
1188 size_t& pre_used,
1189 size_t& cleared_h,
1190 size_t& freed_regions,
1191 UncleanRegionList* list,
1192 bool par) {
1193 assert(!hr->continuesHumongous(), "should have filtered these out");
1194 size_t res = 0;
1195 if (hr->used() > 0 && hr->garbage_bytes() == hr->used() &&
1196 !hr->is_young()) {
1197 if (G1PolicyVerbose > 0)
1198 gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
1199 " during cleanup", hr, hr->used());
1200 free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
1201 }
1202 }
1204 // FIXME: both this and shrink could probably be more efficient by
1205 // doing one "VirtualSpace::expand_by" call rather than several.
1206 void G1CollectedHeap::expand(size_t expand_bytes) {
1207 size_t old_mem_size = _g1_storage.committed_size();
1208 // We expand by a minimum of 1K.
1209 expand_bytes = MAX2(expand_bytes, (size_t)K);
1210 size_t aligned_expand_bytes =
1211 ReservedSpace::page_align_size_up(expand_bytes);
1212 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1213 HeapRegion::GrainBytes);
1214 expand_bytes = aligned_expand_bytes;
1215 while (expand_bytes > 0) {
1216 HeapWord* base = (HeapWord*)_g1_storage.high();
1217 // Commit more storage.
1218 bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
1219 if (!successful) {
1220 expand_bytes = 0;
1221 } else {
1222 expand_bytes -= HeapRegion::GrainBytes;
1223 // Expand the committed region.
1224 HeapWord* high = (HeapWord*) _g1_storage.high();
1225 _g1_committed.set_end(high);
1226 // Create a new HeapRegion.
1227 MemRegion mr(base, high);
1228 bool is_zeroed = !_g1_max_committed.contains(base);
1229 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1231 // Now update max_committed if necessary.
1232 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
1234 // Add it to the HeapRegionSeq.
1235 _hrs->insert(hr);
1236 // Set the zero-fill state, according to whether it's already
1237 // zeroed.
1238 {
1239 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
1240 if (is_zeroed) {
1241 hr->set_zero_fill_complete();
1242 put_free_region_on_list_locked(hr);
1243 } else {
1244 hr->set_zero_fill_needed();
1245 put_region_on_unclean_list_locked(hr);
1246 }
1247 }
1248 _free_regions++;
1249 // And we used up an expansion region to create it.
1250 _expansion_regions--;
1251 // Tell the cardtable about it.
1252 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1253 // And the offset table as well.
1254 _bot_shared->resize(_g1_committed.word_size());
1255 }
1256 }
1257 if (Verbose && PrintGC) {
1258 size_t new_mem_size = _g1_storage.committed_size();
1259 gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
1260 old_mem_size/K, aligned_expand_bytes/K,
1261 new_mem_size/K);
1262 }
1263 }
1265 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1266 {
1267 size_t old_mem_size = _g1_storage.committed_size();
1268 size_t aligned_shrink_bytes =
1269 ReservedSpace::page_align_size_down(shrink_bytes);
1270 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1271 HeapRegion::GrainBytes);
1272 size_t num_regions_deleted = 0;
1273 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1275 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1276 if (mr.byte_size() > 0)
1277 _g1_storage.shrink_by(mr.byte_size());
1278 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1280 _g1_committed.set_end(mr.start());
1281 _free_regions -= num_regions_deleted;
1282 _expansion_regions += num_regions_deleted;
1284 // Tell the cardtable about it.
1285 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1287 // And the offset table as well.
1288 _bot_shared->resize(_g1_committed.word_size());
1290 HeapRegionRemSet::shrink_heap(n_regions());
1292 if (Verbose && PrintGC) {
1293 size_t new_mem_size = _g1_storage.committed_size();
1294 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1295 old_mem_size/K, aligned_shrink_bytes/K,
1296 new_mem_size/K);
1297 }
1298 }
1300 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1301 release_gc_alloc_regions(true /* totally */);
1302 tear_down_region_lists(); // We will rebuild them in a moment.
1303 shrink_helper(shrink_bytes);
1304 rebuild_region_lists();
1305 }
1307 // Public methods.
1309 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1310 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1311 #endif // _MSC_VER
1314 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1315 SharedHeap(policy_),
1316 _g1_policy(policy_),
1317 _ref_processor(NULL),
1318 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1319 _bot_shared(NULL),
1320 _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
1321 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1322 _evac_failure_scan_stack(NULL) ,
1323 _mark_in_progress(false),
1324 _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
1325 _cur_alloc_region(NULL),
1326 _refine_cte_cl(NULL),
1327 _free_region_list(NULL), _free_region_list_size(0),
1328 _free_regions(0),
1329 _full_collection(false),
1330 _unclean_region_list(),
1331 _unclean_regions_coming(false),
1332 _young_list(new YoungList(this)),
1333 _gc_time_stamp(0),
1334 _surviving_young_words(NULL),
1335 _in_cset_fast_test(NULL),
1336 _in_cset_fast_test_base(NULL) {
1337 _g1h = this; // To catch bugs.
1338 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1339 vm_exit_during_initialization("Failed necessary allocation.");
1340 }
1341 int n_queues = MAX2((int)ParallelGCThreads, 1);
1342 _task_queues = new RefToScanQueueSet(n_queues);
1344 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1345 assert(n_rem_sets > 0, "Invariant.");
1347 HeapRegionRemSetIterator** iter_arr =
1348 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1349 for (int i = 0; i < n_queues; i++) {
1350 iter_arr[i] = new HeapRegionRemSetIterator();
1351 }
1352 _rem_set_iterator = iter_arr;
1354 for (int i = 0; i < n_queues; i++) {
1355 RefToScanQueue* q = new RefToScanQueue();
1356 q->initialize();
1357 _task_queues->register_queue(i, q);
1358 }
1360 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1361 _gc_alloc_regions[ap] = NULL;
1362 _gc_alloc_region_counts[ap] = 0;
1363 _retained_gc_alloc_regions[ap] = NULL;
1364 // by default, we do not retain a GC alloc region for each ap;
1365 // we'll override this, when appropriate, below
1366 _retain_gc_alloc_region[ap] = false;
1367 }
1369 // We will try to remember the last half-full tenured region we
1370 // allocated to at the end of a collection so that we can re-use it
1371 // during the next collection.
1372 _retain_gc_alloc_region[GCAllocForTenured] = true;
1374 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1375 }
1377 jint G1CollectedHeap::initialize() {
1378 os::enable_vtime();
1380 // Necessary to satisfy locking discipline assertions.
1382 MutexLocker x(Heap_lock);
1384 // While there are no constraints in the GC code that HeapWordSize
1385 // be any particular value, there are multiple other areas in the
1386 // system which believe this to be true (e.g. oop->object_size in some
1387 // cases incorrectly returns the size in wordSize units rather than
1388 // HeapWordSize).
1389 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1391 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1392 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1394 // Ensure that the sizes are properly aligned.
1395 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1396 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1398 // We allocate this in any case, but only do no work if the command line
1399 // param is off.
1400 _cg1r = new ConcurrentG1Refine();
1402 // Reserve the maximum.
1403 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1404 // Includes the perm-gen.
1406 const size_t total_reserved = max_byte_size + pgs->max_size();
1407 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1409 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1410 HeapRegion::GrainBytes,
1411 false /*ism*/, addr);
1413 if (UseCompressedOops) {
1414 if (addr != NULL && !heap_rs.is_reserved()) {
1415 // Failed to reserve at specified address - the requested memory
1416 // region is taken already, for example, by 'java' launcher.
1417 // Try again to reserver heap higher.
1418 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1419 ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1420 false /*ism*/, addr);
1421 if (addr != NULL && !heap_rs0.is_reserved()) {
1422 // Failed to reserve at specified address again - give up.
1423 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1424 assert(addr == NULL, "");
1425 ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1426 false /*ism*/, addr);
1427 heap_rs = heap_rs1;
1428 } else {
1429 heap_rs = heap_rs0;
1430 }
1431 }
1432 }
1434 if (!heap_rs.is_reserved()) {
1435 vm_exit_during_initialization("Could not reserve enough space for object heap");
1436 return JNI_ENOMEM;
1437 }
1439 // It is important to do this in a way such that concurrent readers can't
1440 // temporarily think somethings in the heap. (I've actually seen this
1441 // happen in asserts: DLD.)
1442 _reserved.set_word_size(0);
1443 _reserved.set_start((HeapWord*)heap_rs.base());
1444 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1446 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1448 _num_humongous_regions = 0;
1450 // Create the gen rem set (and barrier set) for the entire reserved region.
1451 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1452 set_barrier_set(rem_set()->bs());
1453 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1454 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1455 } else {
1456 vm_exit_during_initialization("G1 requires a mod ref bs.");
1457 return JNI_ENOMEM;
1458 }
1460 // Also create a G1 rem set.
1461 if (G1UseHRIntoRS) {
1462 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1463 _g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs());
1464 } else {
1465 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1466 return JNI_ENOMEM;
1467 }
1468 } else {
1469 _g1_rem_set = new StupidG1RemSet(this);
1470 }
1472 // Carve out the G1 part of the heap.
1474 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1475 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1476 g1_rs.size()/HeapWordSize);
1477 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1479 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1481 _g1_storage.initialize(g1_rs, 0);
1482 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1483 _g1_max_committed = _g1_committed;
1484 _hrs = new HeapRegionSeq(_expansion_regions);
1485 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1486 guarantee(_cur_alloc_region == NULL, "from constructor");
1488 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1489 heap_word_size(init_byte_size));
1491 _g1h = this;
1493 // Create the ConcurrentMark data structure and thread.
1494 // (Must do this late, so that "max_regions" is defined.)
1495 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1496 _cmThread = _cm->cmThread();
1498 // ...and the concurrent zero-fill thread, if necessary.
1499 if (G1ConcZeroFill) {
1500 _czft = new ConcurrentZFThread();
1501 }
1503 // Initialize the from_card cache structure of HeapRegionRemSet.
1504 HeapRegionRemSet::init_heap(max_regions());
1506 // Now expand into the initial heap size.
1507 expand(init_byte_size);
1509 // Perform any initialization actions delegated to the policy.
1510 g1_policy()->init();
1512 g1_policy()->note_start_of_mark_thread();
1514 _refine_cte_cl =
1515 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1516 g1_rem_set(),
1517 concurrent_g1_refine());
1518 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1520 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1521 SATB_Q_FL_lock,
1522 0,
1523 Shared_SATB_Q_lock);
1524 if (G1RSBarrierUseQueue) {
1525 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1526 DirtyCardQ_FL_lock,
1527 G1DirtyCardQueueMax,
1528 Shared_DirtyCardQ_lock);
1529 }
1530 if (G1DeferredRSUpdate) {
1531 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1532 DirtyCardQ_FL_lock,
1533 0,
1534 Shared_DirtyCardQ_lock,
1535 &JavaThread::dirty_card_queue_set());
1536 }
1537 // In case we're keeping closure specialization stats, initialize those
1538 // counts and that mechanism.
1539 SpecializationStats::clear();
1541 _gc_alloc_region_list = NULL;
1543 // Do later initialization work for concurrent refinement.
1544 _cg1r->init();
1546 const char* group_names[] = { "CR", "ZF", "CM", "CL" };
1547 GCOverheadReporter::initGCOverheadReporter(4, group_names);
1549 return JNI_OK;
1550 }
1552 void G1CollectedHeap::ref_processing_init() {
1553 SharedHeap::ref_processing_init();
1554 MemRegion mr = reserved_region();
1555 _ref_processor = ReferenceProcessor::create_ref_processor(
1556 mr, // span
1557 false, // Reference discovery is not atomic
1558 // (though it shouldn't matter here.)
1559 true, // mt_discovery
1560 NULL, // is alive closure: need to fill this in for efficiency
1561 ParallelGCThreads,
1562 ParallelRefProcEnabled,
1563 true); // Setting next fields of discovered
1564 // lists requires a barrier.
1565 }
1567 size_t G1CollectedHeap::capacity() const {
1568 return _g1_committed.byte_size();
1569 }
1571 void G1CollectedHeap::iterate_dirty_card_closure(bool concurrent,
1572 int worker_i) {
1573 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1574 int n_completed_buffers = 0;
1575 while (dcqs.apply_closure_to_completed_buffer(worker_i, 0, true)) {
1576 n_completed_buffers++;
1577 }
1578 g1_policy()->record_update_rs_processed_buffers(worker_i,
1579 (double) n_completed_buffers);
1580 dcqs.clear_n_completed_buffers();
1581 // Finish up the queue...
1582 if (worker_i == 0) concurrent_g1_refine()->clean_up_cache(worker_i,
1583 g1_rem_set());
1584 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1585 }
1588 // Computes the sum of the storage used by the various regions.
1590 size_t G1CollectedHeap::used() const {
1591 assert(Heap_lock->owner() != NULL,
1592 "Should be owned on this thread's behalf.");
1593 size_t result = _summary_bytes_used;
1594 if (_cur_alloc_region != NULL)
1595 result += _cur_alloc_region->used();
1596 return result;
1597 }
1599 class SumUsedClosure: public HeapRegionClosure {
1600 size_t _used;
1601 public:
1602 SumUsedClosure() : _used(0) {}
1603 bool doHeapRegion(HeapRegion* r) {
1604 if (!r->continuesHumongous()) {
1605 _used += r->used();
1606 }
1607 return false;
1608 }
1609 size_t result() { return _used; }
1610 };
1612 size_t G1CollectedHeap::recalculate_used() const {
1613 SumUsedClosure blk;
1614 _hrs->iterate(&blk);
1615 return blk.result();
1616 }
1618 #ifndef PRODUCT
1619 class SumUsedRegionsClosure: public HeapRegionClosure {
1620 size_t _num;
1621 public:
1622 SumUsedRegionsClosure() : _num(0) {}
1623 bool doHeapRegion(HeapRegion* r) {
1624 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
1625 _num += 1;
1626 }
1627 return false;
1628 }
1629 size_t result() { return _num; }
1630 };
1632 size_t G1CollectedHeap::recalculate_used_regions() const {
1633 SumUsedRegionsClosure blk;
1634 _hrs->iterate(&blk);
1635 return blk.result();
1636 }
1637 #endif // PRODUCT
1639 size_t G1CollectedHeap::unsafe_max_alloc() {
1640 if (_free_regions > 0) return HeapRegion::GrainBytes;
1641 // otherwise, is there space in the current allocation region?
1643 // We need to store the current allocation region in a local variable
1644 // here. The problem is that this method doesn't take any locks and
1645 // there may be other threads which overwrite the current allocation
1646 // region field. attempt_allocation(), for example, sets it to NULL
1647 // and this can happen *after* the NULL check here but before the call
1648 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
1649 // to be a problem in the optimized build, since the two loads of the
1650 // current allocation region field are optimized away.
1651 HeapRegion* car = _cur_alloc_region;
1653 // FIXME: should iterate over all regions?
1654 if (car == NULL) {
1655 return 0;
1656 }
1657 return car->free();
1658 }
1660 void G1CollectedHeap::collect(GCCause::Cause cause) {
1661 // The caller doesn't have the Heap_lock
1662 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
1663 MutexLocker ml(Heap_lock);
1664 collect_locked(cause);
1665 }
1667 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
1668 assert(Thread::current()->is_VM_thread(), "Precondition#1");
1669 assert(Heap_lock->is_locked(), "Precondition#2");
1670 GCCauseSetter gcs(this, cause);
1671 switch (cause) {
1672 case GCCause::_heap_inspection:
1673 case GCCause::_heap_dump: {
1674 HandleMark hm;
1675 do_full_collection(false); // don't clear all soft refs
1676 break;
1677 }
1678 default: // XXX FIX ME
1679 ShouldNotReachHere(); // Unexpected use of this function
1680 }
1681 }
1684 void G1CollectedHeap::collect_locked(GCCause::Cause cause) {
1685 // Don't want to do a GC until cleanup is completed.
1686 wait_for_cleanup_complete();
1688 // Read the GC count while holding the Heap_lock
1689 int gc_count_before = SharedHeap::heap()->total_collections();
1690 {
1691 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
1692 VM_G1CollectFull op(gc_count_before, cause);
1693 VMThread::execute(&op);
1694 }
1695 }
1697 bool G1CollectedHeap::is_in(const void* p) const {
1698 if (_g1_committed.contains(p)) {
1699 HeapRegion* hr = _hrs->addr_to_region(p);
1700 return hr->is_in(p);
1701 } else {
1702 return _perm_gen->as_gen()->is_in(p);
1703 }
1704 }
1706 // Iteration functions.
1708 // Iterates an OopClosure over all ref-containing fields of objects
1709 // within a HeapRegion.
1711 class IterateOopClosureRegionClosure: public HeapRegionClosure {
1712 MemRegion _mr;
1713 OopClosure* _cl;
1714 public:
1715 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
1716 : _mr(mr), _cl(cl) {}
1717 bool doHeapRegion(HeapRegion* r) {
1718 if (! r->continuesHumongous()) {
1719 r->oop_iterate(_cl);
1720 }
1721 return false;
1722 }
1723 };
1725 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
1726 IterateOopClosureRegionClosure blk(_g1_committed, cl);
1727 _hrs->iterate(&blk);
1728 if (do_perm) {
1729 perm_gen()->oop_iterate(cl);
1730 }
1731 }
1733 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
1734 IterateOopClosureRegionClosure blk(mr, cl);
1735 _hrs->iterate(&blk);
1736 if (do_perm) {
1737 perm_gen()->oop_iterate(cl);
1738 }
1739 }
1741 // Iterates an ObjectClosure over all objects within a HeapRegion.
1743 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1744 ObjectClosure* _cl;
1745 public:
1746 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1747 bool doHeapRegion(HeapRegion* r) {
1748 if (! r->continuesHumongous()) {
1749 r->object_iterate(_cl);
1750 }
1751 return false;
1752 }
1753 };
1755 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
1756 IterateObjectClosureRegionClosure blk(cl);
1757 _hrs->iterate(&blk);
1758 if (do_perm) {
1759 perm_gen()->object_iterate(cl);
1760 }
1761 }
1763 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1764 // FIXME: is this right?
1765 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
1766 }
1768 // Calls a SpaceClosure on a HeapRegion.
1770 class SpaceClosureRegionClosure: public HeapRegionClosure {
1771 SpaceClosure* _cl;
1772 public:
1773 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1774 bool doHeapRegion(HeapRegion* r) {
1775 _cl->do_space(r);
1776 return false;
1777 }
1778 };
1780 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
1781 SpaceClosureRegionClosure blk(cl);
1782 _hrs->iterate(&blk);
1783 }
1785 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
1786 _hrs->iterate(cl);
1787 }
1789 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
1790 HeapRegionClosure* cl) {
1791 _hrs->iterate_from(r, cl);
1792 }
1794 void
1795 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
1796 _hrs->iterate_from(idx, cl);
1797 }
1799 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
1801 void
1802 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1803 int worker,
1804 jint claim_value) {
1805 const size_t regions = n_regions();
1806 const size_t worker_num = (ParallelGCThreads > 0 ? ParallelGCThreads : 1);
1807 // try to spread out the starting points of the workers
1808 const size_t start_index = regions / worker_num * (size_t) worker;
1810 // each worker will actually look at all regions
1811 for (size_t count = 0; count < regions; ++count) {
1812 const size_t index = (start_index + count) % regions;
1813 assert(0 <= index && index < regions, "sanity");
1814 HeapRegion* r = region_at(index);
1815 // we'll ignore "continues humongous" regions (we'll process them
1816 // when we come across their corresponding "start humongous"
1817 // region) and regions already claimed
1818 if (r->claim_value() == claim_value || r->continuesHumongous()) {
1819 continue;
1820 }
1821 // OK, try to claim it
1822 if (r->claimHeapRegion(claim_value)) {
1823 // success!
1824 assert(!r->continuesHumongous(), "sanity");
1825 if (r->startsHumongous()) {
1826 // If the region is "starts humongous" we'll iterate over its
1827 // "continues humongous" first; in fact we'll do them
1828 // first. The order is important. In on case, calling the
1829 // closure on the "starts humongous" region might de-allocate
1830 // and clear all its "continues humongous" regions and, as a
1831 // result, we might end up processing them twice. So, we'll do
1832 // them first (notice: most closures will ignore them anyway) and
1833 // then we'll do the "starts humongous" region.
1834 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
1835 HeapRegion* chr = region_at(ch_index);
1837 // if the region has already been claimed or it's not
1838 // "continues humongous" we're done
1839 if (chr->claim_value() == claim_value ||
1840 !chr->continuesHumongous()) {
1841 break;
1842 }
1844 // Noone should have claimed it directly. We can given
1845 // that we claimed its "starts humongous" region.
1846 assert(chr->claim_value() != claim_value, "sanity");
1847 assert(chr->humongous_start_region() == r, "sanity");
1849 if (chr->claimHeapRegion(claim_value)) {
1850 // we should always be able to claim it; noone else should
1851 // be trying to claim this region
1853 bool res2 = cl->doHeapRegion(chr);
1854 assert(!res2, "Should not abort");
1856 // Right now, this holds (i.e., no closure that actually
1857 // does something with "continues humongous" regions
1858 // clears them). We might have to weaken it in the future,
1859 // but let's leave these two asserts here for extra safety.
1860 assert(chr->continuesHumongous(), "should still be the case");
1861 assert(chr->humongous_start_region() == r, "sanity");
1862 } else {
1863 guarantee(false, "we should not reach here");
1864 }
1865 }
1866 }
1868 assert(!r->continuesHumongous(), "sanity");
1869 bool res = cl->doHeapRegion(r);
1870 assert(!res, "Should not abort");
1871 }
1872 }
1873 }
1875 class ResetClaimValuesClosure: public HeapRegionClosure {
1876 public:
1877 bool doHeapRegion(HeapRegion* r) {
1878 r->set_claim_value(HeapRegion::InitialClaimValue);
1879 return false;
1880 }
1881 };
1883 void
1884 G1CollectedHeap::reset_heap_region_claim_values() {
1885 ResetClaimValuesClosure blk;
1886 heap_region_iterate(&blk);
1887 }
1889 #ifdef ASSERT
1890 // This checks whether all regions in the heap have the correct claim
1891 // value. I also piggy-backed on this a check to ensure that the
1892 // humongous_start_region() information on "continues humongous"
1893 // regions is correct.
1895 class CheckClaimValuesClosure : public HeapRegionClosure {
1896 private:
1897 jint _claim_value;
1898 size_t _failures;
1899 HeapRegion* _sh_region;
1900 public:
1901 CheckClaimValuesClosure(jint claim_value) :
1902 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
1903 bool doHeapRegion(HeapRegion* r) {
1904 if (r->claim_value() != _claim_value) {
1905 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1906 "claim value = %d, should be %d",
1907 r->bottom(), r->end(), r->claim_value(),
1908 _claim_value);
1909 ++_failures;
1910 }
1911 if (!r->isHumongous()) {
1912 _sh_region = NULL;
1913 } else if (r->startsHumongous()) {
1914 _sh_region = r;
1915 } else if (r->continuesHumongous()) {
1916 if (r->humongous_start_region() != _sh_region) {
1917 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1918 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
1919 r->bottom(), r->end(),
1920 r->humongous_start_region(),
1921 _sh_region);
1922 ++_failures;
1923 }
1924 }
1925 return false;
1926 }
1927 size_t failures() {
1928 return _failures;
1929 }
1930 };
1932 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
1933 CheckClaimValuesClosure cl(claim_value);
1934 heap_region_iterate(&cl);
1935 return cl.failures() == 0;
1936 }
1937 #endif // ASSERT
1939 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
1940 HeapRegion* r = g1_policy()->collection_set();
1941 while (r != NULL) {
1942 HeapRegion* next = r->next_in_collection_set();
1943 if (cl->doHeapRegion(r)) {
1944 cl->incomplete();
1945 return;
1946 }
1947 r = next;
1948 }
1949 }
1951 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
1952 HeapRegionClosure *cl) {
1953 assert(r->in_collection_set(),
1954 "Start region must be a member of the collection set.");
1955 HeapRegion* cur = r;
1956 while (cur != NULL) {
1957 HeapRegion* next = cur->next_in_collection_set();
1958 if (cl->doHeapRegion(cur) && false) {
1959 cl->incomplete();
1960 return;
1961 }
1962 cur = next;
1963 }
1964 cur = g1_policy()->collection_set();
1965 while (cur != r) {
1966 HeapRegion* next = cur->next_in_collection_set();
1967 if (cl->doHeapRegion(cur) && false) {
1968 cl->incomplete();
1969 return;
1970 }
1971 cur = next;
1972 }
1973 }
1975 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
1976 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
1977 }
1980 Space* G1CollectedHeap::space_containing(const void* addr) const {
1981 Space* res = heap_region_containing(addr);
1982 if (res == NULL)
1983 res = perm_gen()->space_containing(addr);
1984 return res;
1985 }
1987 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
1988 Space* sp = space_containing(addr);
1989 if (sp != NULL) {
1990 return sp->block_start(addr);
1991 }
1992 return NULL;
1993 }
1995 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
1996 Space* sp = space_containing(addr);
1997 assert(sp != NULL, "block_size of address outside of heap");
1998 return sp->block_size(addr);
1999 }
2001 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2002 Space* sp = space_containing(addr);
2003 return sp->block_is_obj(addr);
2004 }
2006 bool G1CollectedHeap::supports_tlab_allocation() const {
2007 return true;
2008 }
2010 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2011 return HeapRegion::GrainBytes;
2012 }
2014 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2015 // Return the remaining space in the cur alloc region, but not less than
2016 // the min TLAB size.
2017 // Also, no more than half the region size, since we can't allow tlabs to
2018 // grow big enough to accomodate humongous objects.
2020 // We need to story it locally, since it might change between when we
2021 // test for NULL and when we use it later.
2022 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
2023 if (cur_alloc_space == NULL) {
2024 return HeapRegion::GrainBytes/2;
2025 } else {
2026 return MAX2(MIN2(cur_alloc_space->free(),
2027 (size_t)(HeapRegion::GrainBytes/2)),
2028 (size_t)MinTLABSize);
2029 }
2030 }
2032 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
2033 bool dummy;
2034 return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
2035 }
2037 bool G1CollectedHeap::allocs_are_zero_filled() {
2038 return false;
2039 }
2041 size_t G1CollectedHeap::large_typearray_limit() {
2042 // FIXME
2043 return HeapRegion::GrainBytes/HeapWordSize;
2044 }
2046 size_t G1CollectedHeap::max_capacity() const {
2047 return _g1_committed.byte_size();
2048 }
2050 jlong G1CollectedHeap::millis_since_last_gc() {
2051 // assert(false, "NYI");
2052 return 0;
2053 }
2056 void G1CollectedHeap::prepare_for_verify() {
2057 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2058 ensure_parsability(false);
2059 }
2060 g1_rem_set()->prepare_for_verify();
2061 }
2063 class VerifyLivenessOopClosure: public OopClosure {
2064 G1CollectedHeap* g1h;
2065 public:
2066 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2067 g1h = _g1h;
2068 }
2069 void do_oop(narrowOop *p) {
2070 guarantee(false, "NYI");
2071 }
2072 void do_oop(oop *p) {
2073 oop obj = *p;
2074 assert(obj == NULL || !g1h->is_obj_dead(obj),
2075 "Dead object referenced by a not dead object");
2076 }
2077 };
2079 class VerifyObjsInRegionClosure: public ObjectClosure {
2080 G1CollectedHeap* _g1h;
2081 size_t _live_bytes;
2082 HeapRegion *_hr;
2083 public:
2084 VerifyObjsInRegionClosure(HeapRegion *hr) : _live_bytes(0), _hr(hr) {
2085 _g1h = G1CollectedHeap::heap();
2086 }
2087 void do_object(oop o) {
2088 VerifyLivenessOopClosure isLive(_g1h);
2089 assert(o != NULL, "Huh?");
2090 if (!_g1h->is_obj_dead(o)) {
2091 o->oop_iterate(&isLive);
2092 if (!_hr->obj_allocated_since_prev_marking(o))
2093 _live_bytes += (o->size() * HeapWordSize);
2094 }
2095 }
2096 size_t live_bytes() { return _live_bytes; }
2097 };
2099 class PrintObjsInRegionClosure : public ObjectClosure {
2100 HeapRegion *_hr;
2101 G1CollectedHeap *_g1;
2102 public:
2103 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2104 _g1 = G1CollectedHeap::heap();
2105 };
2107 void do_object(oop o) {
2108 if (o != NULL) {
2109 HeapWord *start = (HeapWord *) o;
2110 size_t word_sz = o->size();
2111 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2112 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2113 (void*) o, word_sz,
2114 _g1->isMarkedPrev(o),
2115 _g1->isMarkedNext(o),
2116 _hr->obj_allocated_since_prev_marking(o));
2117 HeapWord *end = start + word_sz;
2118 HeapWord *cur;
2119 int *val;
2120 for (cur = start; cur < end; cur++) {
2121 val = (int *) cur;
2122 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2123 }
2124 }
2125 }
2126 };
2128 class VerifyRegionClosure: public HeapRegionClosure {
2129 public:
2130 bool _allow_dirty;
2131 bool _par;
2132 VerifyRegionClosure(bool allow_dirty, bool par = false)
2133 : _allow_dirty(allow_dirty), _par(par) {}
2134 bool doHeapRegion(HeapRegion* r) {
2135 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2136 "Should be unclaimed at verify points.");
2137 if (!r->continuesHumongous()) {
2138 VerifyObjsInRegionClosure not_dead_yet_cl(r);
2139 r->verify(_allow_dirty);
2140 r->object_iterate(¬_dead_yet_cl);
2141 guarantee(r->max_live_bytes() >= not_dead_yet_cl.live_bytes(),
2142 "More live objects than counted in last complete marking.");
2143 }
2144 return false;
2145 }
2146 };
2148 class VerifyRootsClosure: public OopsInGenClosure {
2149 private:
2150 G1CollectedHeap* _g1h;
2151 bool _failures;
2153 public:
2154 VerifyRootsClosure() :
2155 _g1h(G1CollectedHeap::heap()), _failures(false) { }
2157 bool failures() { return _failures; }
2159 void do_oop(narrowOop* p) {
2160 guarantee(false, "NYI");
2161 }
2163 void do_oop(oop* p) {
2164 oop obj = *p;
2165 if (obj != NULL) {
2166 if (_g1h->is_obj_dead(obj)) {
2167 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2168 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2169 obj->print_on(gclog_or_tty);
2170 _failures = true;
2171 }
2172 }
2173 }
2174 };
2176 // This is the task used for parallel heap verification.
2178 class G1ParVerifyTask: public AbstractGangTask {
2179 private:
2180 G1CollectedHeap* _g1h;
2181 bool _allow_dirty;
2183 public:
2184 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty) :
2185 AbstractGangTask("Parallel verify task"),
2186 _g1h(g1h), _allow_dirty(allow_dirty) { }
2188 void work(int worker_i) {
2189 HandleMark hm;
2190 VerifyRegionClosure blk(_allow_dirty, true);
2191 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2192 HeapRegion::ParVerifyClaimValue);
2193 }
2194 };
2196 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2197 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2198 if (!silent) { gclog_or_tty->print("roots "); }
2199 VerifyRootsClosure rootsCl;
2200 process_strong_roots(false,
2201 SharedHeap::SO_AllClasses,
2202 &rootsCl,
2203 &rootsCl);
2204 rem_set()->invalidate(perm_gen()->used_region(), false);
2205 if (!silent) { gclog_or_tty->print("heapRegions "); }
2206 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2207 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2208 "sanity check");
2210 G1ParVerifyTask task(this, allow_dirty);
2211 int n_workers = workers()->total_workers();
2212 set_par_threads(n_workers);
2213 workers()->run_task(&task);
2214 set_par_threads(0);
2216 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2217 "sanity check");
2219 reset_heap_region_claim_values();
2221 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2222 "sanity check");
2223 } else {
2224 VerifyRegionClosure blk(allow_dirty);
2225 _hrs->iterate(&blk);
2226 }
2227 if (!silent) gclog_or_tty->print("remset ");
2228 rem_set()->verify();
2229 guarantee(!rootsCl.failures(), "should not have had failures");
2230 } else {
2231 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2232 }
2233 }
2235 class PrintRegionClosure: public HeapRegionClosure {
2236 outputStream* _st;
2237 public:
2238 PrintRegionClosure(outputStream* st) : _st(st) {}
2239 bool doHeapRegion(HeapRegion* r) {
2240 r->print_on(_st);
2241 return false;
2242 }
2243 };
2245 void G1CollectedHeap::print() const { print_on(gclog_or_tty); }
2247 void G1CollectedHeap::print_on(outputStream* st) const {
2248 PrintRegionClosure blk(st);
2249 _hrs->iterate(&blk);
2250 }
2252 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2253 if (ParallelGCThreads > 0) {
2254 workers()->print_worker_threads();
2255 }
2256 st->print("\"G1 concurrent mark GC Thread\" ");
2257 _cmThread->print();
2258 st->cr();
2259 st->print("\"G1 concurrent refinement GC Thread\" ");
2260 _cg1r->cg1rThread()->print_on(st);
2261 st->cr();
2262 st->print("\"G1 zero-fill GC Thread\" ");
2263 _czft->print_on(st);
2264 st->cr();
2265 }
2267 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2268 if (ParallelGCThreads > 0) {
2269 workers()->threads_do(tc);
2270 }
2271 tc->do_thread(_cmThread);
2272 tc->do_thread(_cg1r->cg1rThread());
2273 tc->do_thread(_czft);
2274 }
2276 void G1CollectedHeap::print_tracing_info() const {
2277 concurrent_g1_refine()->print_final_card_counts();
2279 // We'll overload this to mean "trace GC pause statistics."
2280 if (TraceGen0Time || TraceGen1Time) {
2281 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2282 // to that.
2283 g1_policy()->print_tracing_info();
2284 }
2285 if (SummarizeG1RSStats) {
2286 g1_rem_set()->print_summary_info();
2287 }
2288 if (SummarizeG1ConcMark) {
2289 concurrent_mark()->print_summary_info();
2290 }
2291 if (SummarizeG1ZFStats) {
2292 ConcurrentZFThread::print_summary_info();
2293 }
2294 g1_policy()->print_yg_surv_rate_info();
2296 GCOverheadReporter::printGCOverhead();
2298 SpecializationStats::print();
2299 }
2302 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2303 HeapRegion* hr = heap_region_containing(addr);
2304 if (hr == NULL) {
2305 return 0;
2306 } else {
2307 return 1;
2308 }
2309 }
2311 G1CollectedHeap* G1CollectedHeap::heap() {
2312 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2313 "not a garbage-first heap");
2314 return _g1h;
2315 }
2317 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2318 if (PrintHeapAtGC){
2319 gclog_or_tty->print_cr(" {Heap before GC collections=%d:", total_collections());
2320 Universe::print();
2321 }
2322 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2323 // Call allocation profiler
2324 AllocationProfiler::iterate_since_last_gc();
2325 // Fill TLAB's and such
2326 ensure_parsability(true);
2327 }
2329 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2330 // FIXME: what is this about?
2331 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2332 // is set.
2333 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2334 "derived pointer present"));
2336 if (PrintHeapAtGC){
2337 gclog_or_tty->print_cr(" Heap after GC collections=%d:", total_collections());
2338 Universe::print();
2339 gclog_or_tty->print("} ");
2340 }
2341 }
2343 void G1CollectedHeap::do_collection_pause() {
2344 // Read the GC count while holding the Heap_lock
2345 // we need to do this _before_ wait_for_cleanup_complete(), to
2346 // ensure that we do not give up the heap lock and potentially
2347 // pick up the wrong count
2348 int gc_count_before = SharedHeap::heap()->total_collections();
2350 // Don't want to do a GC pause while cleanup is being completed!
2351 wait_for_cleanup_complete();
2353 g1_policy()->record_stop_world_start();
2354 {
2355 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2356 VM_G1IncCollectionPause op(gc_count_before);
2357 VMThread::execute(&op);
2358 }
2359 }
2361 void
2362 G1CollectedHeap::doConcurrentMark() {
2363 if (G1ConcMark) {
2364 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2365 if (!_cmThread->in_progress()) {
2366 _cmThread->set_started();
2367 CGC_lock->notify();
2368 }
2369 }
2370 }
2372 class VerifyMarkedObjsClosure: public ObjectClosure {
2373 G1CollectedHeap* _g1h;
2374 public:
2375 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2376 void do_object(oop obj) {
2377 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2378 "markandsweep mark should agree with concurrent deadness");
2379 }
2380 };
2382 void
2383 G1CollectedHeap::checkConcurrentMark() {
2384 VerifyMarkedObjsClosure verifycl(this);
2385 // MutexLockerEx x(getMarkBitMapLock(),
2386 // Mutex::_no_safepoint_check_flag);
2387 object_iterate(&verifycl, false);
2388 }
2390 void G1CollectedHeap::do_sync_mark() {
2391 _cm->checkpointRootsInitial();
2392 _cm->markFromRoots();
2393 _cm->checkpointRootsFinal(false);
2394 }
2396 // <NEW PREDICTION>
2398 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2399 bool young) {
2400 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2401 }
2403 void G1CollectedHeap::check_if_region_is_too_expensive(double
2404 predicted_time_ms) {
2405 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2406 }
2408 size_t G1CollectedHeap::pending_card_num() {
2409 size_t extra_cards = 0;
2410 JavaThread *curr = Threads::first();
2411 while (curr != NULL) {
2412 DirtyCardQueue& dcq = curr->dirty_card_queue();
2413 extra_cards += dcq.size();
2414 curr = curr->next();
2415 }
2416 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2417 size_t buffer_size = dcqs.buffer_size();
2418 size_t buffer_num = dcqs.completed_buffers_num();
2419 return buffer_size * buffer_num + extra_cards;
2420 }
2422 size_t G1CollectedHeap::max_pending_card_num() {
2423 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2424 size_t buffer_size = dcqs.buffer_size();
2425 size_t buffer_num = dcqs.completed_buffers_num();
2426 int thread_num = Threads::number_of_threads();
2427 return (buffer_num + thread_num) * buffer_size;
2428 }
2430 size_t G1CollectedHeap::cards_scanned() {
2431 HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
2432 return g1_rset->cardsScanned();
2433 }
2435 void
2436 G1CollectedHeap::setup_surviving_young_words() {
2437 guarantee( _surviving_young_words == NULL, "pre-condition" );
2438 size_t array_length = g1_policy()->young_cset_length();
2439 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2440 if (_surviving_young_words == NULL) {
2441 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2442 "Not enough space for young surv words summary.");
2443 }
2444 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2445 for (size_t i = 0; i < array_length; ++i) {
2446 guarantee( _surviving_young_words[i] == 0, "invariant" );
2447 }
2448 }
2450 void
2451 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2452 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2453 size_t array_length = g1_policy()->young_cset_length();
2454 for (size_t i = 0; i < array_length; ++i)
2455 _surviving_young_words[i] += surv_young_words[i];
2456 }
2458 void
2459 G1CollectedHeap::cleanup_surviving_young_words() {
2460 guarantee( _surviving_young_words != NULL, "pre-condition" );
2461 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2462 _surviving_young_words = NULL;
2463 }
2465 // </NEW PREDICTION>
2467 void
2468 G1CollectedHeap::do_collection_pause_at_safepoint() {
2469 char verbose_str[128];
2470 sprintf(verbose_str, "GC pause ");
2471 if (g1_policy()->in_young_gc_mode()) {
2472 if (g1_policy()->full_young_gcs())
2473 strcat(verbose_str, "(young)");
2474 else
2475 strcat(verbose_str, "(partial)");
2476 }
2477 if (g1_policy()->should_initiate_conc_mark())
2478 strcat(verbose_str, " (initial-mark)");
2480 GCCauseSetter x(this, GCCause::_g1_inc_collection_pause);
2482 // if PrintGCDetails is on, we'll print long statistics information
2483 // in the collector policy code, so let's not print this as the output
2484 // is messy if we do.
2485 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2486 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2487 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2489 ResourceMark rm;
2490 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2491 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2492 guarantee(!is_gc_active(), "collection is not reentrant");
2493 assert(regions_accounted_for(), "Region leakage!");
2495 increment_gc_time_stamp();
2497 if (g1_policy()->in_young_gc_mode()) {
2498 assert(check_young_list_well_formed(),
2499 "young list should be well formed");
2500 }
2502 if (GC_locker::is_active()) {
2503 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2504 }
2506 bool abandoned = false;
2507 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2508 IsGCActiveMark x;
2510 gc_prologue(false);
2511 increment_total_collections();
2513 #if G1_REM_SET_LOGGING
2514 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2515 print();
2516 #endif
2518 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2519 HandleMark hm; // Discard invalid handles created during verification
2520 prepare_for_verify();
2521 gclog_or_tty->print(" VerifyBeforeGC:");
2522 Universe::verify(false);
2523 }
2525 COMPILER2_PRESENT(DerivedPointerTable::clear());
2527 // We want to turn off ref discovery, if necessary, and turn it back on
2528 // on again later if we do.
2529 bool was_enabled = ref_processor()->discovery_enabled();
2530 if (was_enabled) ref_processor()->disable_discovery();
2532 // Forget the current alloc region (we might even choose it to be part
2533 // of the collection set!).
2534 abandon_cur_alloc_region();
2536 // The elapsed time induced by the start time below deliberately elides
2537 // the possible verification above.
2538 double start_time_sec = os::elapsedTime();
2539 GCOverheadReporter::recordSTWStart(start_time_sec);
2540 size_t start_used_bytes = used();
2541 if (!G1ConcMark) {
2542 do_sync_mark();
2543 }
2545 g1_policy()->record_collection_pause_start(start_time_sec,
2546 start_used_bytes);
2548 guarantee(_in_cset_fast_test == NULL, "invariant");
2549 guarantee(_in_cset_fast_test_base == NULL, "invariant");
2550 _in_cset_fast_test_length = max_regions();
2551 _in_cset_fast_test_base =
2552 NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2553 memset(_in_cset_fast_test_base, false,
2554 _in_cset_fast_test_length * sizeof(bool));
2555 // We're biasing _in_cset_fast_test to avoid subtracting the
2556 // beginning of the heap every time we want to index; basically
2557 // it's the same with what we do with the card table.
2558 _in_cset_fast_test = _in_cset_fast_test_base -
2559 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2561 #if SCAN_ONLY_VERBOSE
2562 _young_list->print();
2563 #endif // SCAN_ONLY_VERBOSE
2565 if (g1_policy()->should_initiate_conc_mark()) {
2566 concurrent_mark()->checkpointRootsInitialPre();
2567 }
2568 save_marks();
2570 // We must do this before any possible evacuation that should propagate
2571 // marks.
2572 if (mark_in_progress()) {
2573 double start_time_sec = os::elapsedTime();
2575 _cm->drainAllSATBBuffers();
2576 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2577 g1_policy()->record_satb_drain_time(finish_mark_ms);
2579 }
2580 // Record the number of elements currently on the mark stack, so we
2581 // only iterate over these. (Since evacuation may add to the mark
2582 // stack, doing more exposes race conditions.) If no mark is in
2583 // progress, this will be zero.
2584 _cm->set_oops_do_bound();
2586 assert(regions_accounted_for(), "Region leakage.");
2588 if (mark_in_progress())
2589 concurrent_mark()->newCSet();
2591 // Now choose the CS.
2592 g1_policy()->choose_collection_set();
2594 // We may abandon a pause if we find no region that will fit in the MMU
2595 // pause.
2596 bool abandoned = (g1_policy()->collection_set() == NULL);
2598 // Nothing to do if we were unable to choose a collection set.
2599 if (!abandoned) {
2600 #if G1_REM_SET_LOGGING
2601 gclog_or_tty->print_cr("\nAfter pause, heap:");
2602 print();
2603 #endif
2605 setup_surviving_young_words();
2607 // Set up the gc allocation regions.
2608 get_gc_alloc_regions();
2610 // Actually do the work...
2611 evacuate_collection_set();
2612 free_collection_set(g1_policy()->collection_set());
2613 g1_policy()->clear_collection_set();
2615 FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base);
2616 // this is more for peace of mind; we're nulling them here and
2617 // we're expecting them to be null at the beginning of the next GC
2618 _in_cset_fast_test = NULL;
2619 _in_cset_fast_test_base = NULL;
2621 release_gc_alloc_regions(false /* totally */);
2623 cleanup_surviving_young_words();
2625 if (g1_policy()->in_young_gc_mode()) {
2626 _young_list->reset_sampled_info();
2627 assert(check_young_list_empty(true),
2628 "young list should be empty");
2630 #if SCAN_ONLY_VERBOSE
2631 _young_list->print();
2632 #endif // SCAN_ONLY_VERBOSE
2634 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
2635 _young_list->first_survivor_region(),
2636 _young_list->last_survivor_region());
2637 _young_list->reset_auxilary_lists();
2638 }
2639 } else {
2640 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
2641 }
2643 if (evacuation_failed()) {
2644 _summary_bytes_used = recalculate_used();
2645 } else {
2646 // The "used" of the the collection set have already been subtracted
2647 // when they were freed. Add in the bytes evacuated.
2648 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2649 }
2651 if (g1_policy()->in_young_gc_mode() &&
2652 g1_policy()->should_initiate_conc_mark()) {
2653 concurrent_mark()->checkpointRootsInitialPost();
2654 set_marking_started();
2655 doConcurrentMark();
2656 }
2658 #if SCAN_ONLY_VERBOSE
2659 _young_list->print();
2660 #endif // SCAN_ONLY_VERBOSE
2662 double end_time_sec = os::elapsedTime();
2663 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
2664 g1_policy()->record_pause_time_ms(pause_time_ms);
2665 GCOverheadReporter::recordSTWEnd(end_time_sec);
2666 g1_policy()->record_collection_pause_end(abandoned);
2668 assert(regions_accounted_for(), "Region leakage.");
2670 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
2671 HandleMark hm; // Discard invalid handles created during verification
2672 gclog_or_tty->print(" VerifyAfterGC:");
2673 prepare_for_verify();
2674 Universe::verify(false);
2675 }
2677 if (was_enabled) ref_processor()->enable_discovery();
2679 {
2680 size_t expand_bytes = g1_policy()->expansion_amount();
2681 if (expand_bytes > 0) {
2682 size_t bytes_before = capacity();
2683 expand(expand_bytes);
2684 }
2685 }
2687 if (mark_in_progress()) {
2688 concurrent_mark()->update_g1_committed();
2689 }
2691 #ifdef TRACESPINNING
2692 ParallelTaskTerminator::print_termination_counts();
2693 #endif
2695 gc_epilogue(false);
2696 }
2698 assert(verify_region_lists(), "Bad region lists.");
2700 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
2701 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
2702 print_tracing_info();
2703 vm_exit(-1);
2704 }
2705 }
2707 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
2708 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
2709 // make sure we don't call set_gc_alloc_region() multiple times on
2710 // the same region
2711 assert(r == NULL || !r->is_gc_alloc_region(),
2712 "shouldn't already be a GC alloc region");
2713 HeapWord* original_top = NULL;
2714 if (r != NULL)
2715 original_top = r->top();
2717 // We will want to record the used space in r as being there before gc.
2718 // One we install it as a GC alloc region it's eligible for allocation.
2719 // So record it now and use it later.
2720 size_t r_used = 0;
2721 if (r != NULL) {
2722 r_used = r->used();
2724 if (ParallelGCThreads > 0) {
2725 // need to take the lock to guard against two threads calling
2726 // get_gc_alloc_region concurrently (very unlikely but...)
2727 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2728 r->save_marks();
2729 }
2730 }
2731 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
2732 _gc_alloc_regions[purpose] = r;
2733 if (old_alloc_region != NULL) {
2734 // Replace aliases too.
2735 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2736 if (_gc_alloc_regions[ap] == old_alloc_region) {
2737 _gc_alloc_regions[ap] = r;
2738 }
2739 }
2740 }
2741 if (r != NULL) {
2742 push_gc_alloc_region(r);
2743 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
2744 // We are using a region as a GC alloc region after it has been used
2745 // as a mutator allocation region during the current marking cycle.
2746 // The mutator-allocated objects are currently implicitly marked, but
2747 // when we move hr->next_top_at_mark_start() forward at the the end
2748 // of the GC pause, they won't be. We therefore mark all objects in
2749 // the "gap". We do this object-by-object, since marking densely
2750 // does not currently work right with marking bitmap iteration. This
2751 // means we rely on TLAB filling at the start of pauses, and no
2752 // "resuscitation" of filled TLAB's. If we want to do this, we need
2753 // to fix the marking bitmap iteration.
2754 HeapWord* curhw = r->next_top_at_mark_start();
2755 HeapWord* t = original_top;
2757 while (curhw < t) {
2758 oop cur = (oop)curhw;
2759 // We'll assume parallel for generality. This is rare code.
2760 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
2761 curhw = curhw + cur->size();
2762 }
2763 assert(curhw == t, "Should have parsed correctly.");
2764 }
2765 if (G1PolicyVerbose > 1) {
2766 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
2767 "for survivors:", r->bottom(), original_top, r->end());
2768 r->print();
2769 }
2770 g1_policy()->record_before_bytes(r_used);
2771 }
2772 }
2774 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
2775 assert(Thread::current()->is_VM_thread() ||
2776 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
2777 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
2778 "Precondition.");
2779 hr->set_is_gc_alloc_region(true);
2780 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
2781 _gc_alloc_region_list = hr;
2782 }
2784 #ifdef G1_DEBUG
2785 class FindGCAllocRegion: public HeapRegionClosure {
2786 public:
2787 bool doHeapRegion(HeapRegion* r) {
2788 if (r->is_gc_alloc_region()) {
2789 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
2790 r->hrs_index(), r->bottom());
2791 }
2792 return false;
2793 }
2794 };
2795 #endif // G1_DEBUG
2797 void G1CollectedHeap::forget_alloc_region_list() {
2798 assert(Thread::current()->is_VM_thread(), "Precondition");
2799 while (_gc_alloc_region_list != NULL) {
2800 HeapRegion* r = _gc_alloc_region_list;
2801 assert(r->is_gc_alloc_region(), "Invariant.");
2802 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
2803 // newly allocated data in order to be able to apply deferred updates
2804 // before the GC is done for verification purposes (i.e to allow
2805 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
2806 // collection.
2807 r->ContiguousSpace::set_saved_mark();
2808 _gc_alloc_region_list = r->next_gc_alloc_region();
2809 r->set_next_gc_alloc_region(NULL);
2810 r->set_is_gc_alloc_region(false);
2811 if (r->is_survivor()) {
2812 if (r->is_empty()) {
2813 r->set_not_young();
2814 } else {
2815 _young_list->add_survivor_region(r);
2816 }
2817 }
2818 if (r->is_empty()) {
2819 ++_free_regions;
2820 }
2821 }
2822 #ifdef G1_DEBUG
2823 FindGCAllocRegion fa;
2824 heap_region_iterate(&fa);
2825 #endif // G1_DEBUG
2826 }
2829 bool G1CollectedHeap::check_gc_alloc_regions() {
2830 // TODO: allocation regions check
2831 return true;
2832 }
2834 void G1CollectedHeap::get_gc_alloc_regions() {
2835 // First, let's check that the GC alloc region list is empty (it should)
2836 assert(_gc_alloc_region_list == NULL, "invariant");
2838 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2839 assert(_gc_alloc_regions[ap] == NULL, "invariant");
2841 // Create new GC alloc regions.
2842 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
2843 _retained_gc_alloc_regions[ap] = NULL;
2845 if (alloc_region != NULL) {
2846 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
2848 // let's make sure that the GC alloc region is not tagged as such
2849 // outside a GC operation
2850 assert(!alloc_region->is_gc_alloc_region(), "sanity");
2852 if (alloc_region->in_collection_set() ||
2853 alloc_region->top() == alloc_region->end() ||
2854 alloc_region->top() == alloc_region->bottom()) {
2855 // we will discard the current GC alloc region if it's in the
2856 // collection set (it can happen!), if it's already full (no
2857 // point in using it), or if it's empty (this means that it
2858 // was emptied during a cleanup and it should be on the free
2859 // list now).
2861 alloc_region = NULL;
2862 }
2863 }
2865 if (alloc_region == NULL) {
2866 // we will get a new GC alloc region
2867 alloc_region = newAllocRegionWithExpansion(ap, 0);
2868 }
2870 if (alloc_region != NULL) {
2871 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
2872 set_gc_alloc_region(ap, alloc_region);
2873 }
2875 assert(_gc_alloc_regions[ap] == NULL ||
2876 _gc_alloc_regions[ap]->is_gc_alloc_region(),
2877 "the GC alloc region should be tagged as such");
2878 assert(_gc_alloc_regions[ap] == NULL ||
2879 _gc_alloc_regions[ap] == _gc_alloc_region_list,
2880 "the GC alloc region should be the same as the GC alloc list head");
2881 }
2882 // Set alternative regions for allocation purposes that have reached
2883 // their limit.
2884 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2885 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
2886 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
2887 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
2888 }
2889 }
2890 assert(check_gc_alloc_regions(), "alloc regions messed up");
2891 }
2893 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
2894 // We keep a separate list of all regions that have been alloc regions in
2895 // the current collection pause. Forget that now. This method will
2896 // untag the GC alloc regions and tear down the GC alloc region
2897 // list. It's desirable that no regions are tagged as GC alloc
2898 // outside GCs.
2899 forget_alloc_region_list();
2901 // The current alloc regions contain objs that have survived
2902 // collection. Make them no longer GC alloc regions.
2903 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2904 HeapRegion* r = _gc_alloc_regions[ap];
2905 _retained_gc_alloc_regions[ap] = NULL;
2907 if (r != NULL) {
2908 // we retain nothing on _gc_alloc_regions between GCs
2909 set_gc_alloc_region(ap, NULL);
2910 _gc_alloc_region_counts[ap] = 0;
2912 if (r->is_empty()) {
2913 // we didn't actually allocate anything in it; let's just put
2914 // it on the free list
2915 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
2916 r->set_zero_fill_complete();
2917 put_free_region_on_list_locked(r);
2918 } else if (_retain_gc_alloc_region[ap] && !totally) {
2919 // retain it so that we can use it at the beginning of the next GC
2920 _retained_gc_alloc_regions[ap] = r;
2921 }
2922 }
2923 }
2924 }
2926 #ifndef PRODUCT
2927 // Useful for debugging
2929 void G1CollectedHeap::print_gc_alloc_regions() {
2930 gclog_or_tty->print_cr("GC alloc regions");
2931 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2932 HeapRegion* r = _gc_alloc_regions[ap];
2933 if (r == NULL) {
2934 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
2935 } else {
2936 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
2937 ap, r->bottom(), r->used());
2938 }
2939 }
2940 }
2941 #endif // PRODUCT
2943 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
2944 _drain_in_progress = false;
2945 set_evac_failure_closure(cl);
2946 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
2947 }
2949 void G1CollectedHeap::finalize_for_evac_failure() {
2950 assert(_evac_failure_scan_stack != NULL &&
2951 _evac_failure_scan_stack->length() == 0,
2952 "Postcondition");
2953 assert(!_drain_in_progress, "Postcondition");
2954 // Don't have to delete, since the scan stack is a resource object.
2955 _evac_failure_scan_stack = NULL;
2956 }
2960 // *** Sequential G1 Evacuation
2962 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
2963 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
2964 // let the caller handle alloc failure
2965 if (alloc_region == NULL) return NULL;
2966 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
2967 "Either the object is humongous or the region isn't");
2968 HeapWord* block = alloc_region->allocate(word_size);
2969 if (block == NULL) {
2970 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
2971 }
2972 return block;
2973 }
2975 class G1IsAliveClosure: public BoolObjectClosure {
2976 G1CollectedHeap* _g1;
2977 public:
2978 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
2979 void do_object(oop p) { assert(false, "Do not call."); }
2980 bool do_object_b(oop p) {
2981 // It is reachable if it is outside the collection set, or is inside
2982 // and forwarded.
2984 #ifdef G1_DEBUG
2985 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
2986 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
2987 !_g1->obj_in_cs(p) || p->is_forwarded());
2988 #endif // G1_DEBUG
2990 return !_g1->obj_in_cs(p) || p->is_forwarded();
2991 }
2992 };
2994 class G1KeepAliveClosure: public OopClosure {
2995 G1CollectedHeap* _g1;
2996 public:
2997 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
2998 void do_oop(narrowOop* p) {
2999 guarantee(false, "NYI");
3000 }
3001 void do_oop(oop* p) {
3002 oop obj = *p;
3003 #ifdef G1_DEBUG
3004 if (PrintGC && Verbose) {
3005 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3006 p, (void*) obj, (void*) *p);
3007 }
3008 #endif // G1_DEBUG
3010 if (_g1->obj_in_cs(obj)) {
3011 assert( obj->is_forwarded(), "invariant" );
3012 *p = obj->forwardee();
3014 #ifdef G1_DEBUG
3015 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3016 (void*) obj, (void*) *p);
3017 #endif // G1_DEBUG
3018 }
3019 }
3020 };
3022 class UpdateRSetImmediate : public OopsInHeapRegionClosure {
3023 private:
3024 G1CollectedHeap* _g1;
3025 G1RemSet* _g1_rem_set;
3026 public:
3027 UpdateRSetImmediate(G1CollectedHeap* g1) :
3028 _g1(g1), _g1_rem_set(g1->g1_rem_set()) {}
3030 void do_oop(narrowOop* p) {
3031 guarantee(false, "NYI");
3032 }
3033 void do_oop(oop* p) {
3034 assert(_from->is_in_reserved(p), "paranoia");
3035 if (*p != NULL && !_from->is_survivor()) {
3036 _g1_rem_set->par_write_ref(_from, p, 0);
3037 }
3038 }
3039 };
3041 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3042 private:
3043 G1CollectedHeap* _g1;
3044 DirtyCardQueue *_dcq;
3045 CardTableModRefBS* _ct_bs;
3047 public:
3048 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3049 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3051 void do_oop(narrowOop* p) {
3052 guarantee(false, "NYI");
3053 }
3054 void do_oop(oop* p) {
3055 assert(_from->is_in_reserved(p), "paranoia");
3056 if (!_from->is_in_reserved(*p) && !_from->is_survivor()) {
3057 size_t card_index = _ct_bs->index_for(p);
3058 if (_ct_bs->mark_card_deferred(card_index)) {
3059 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3060 }
3061 }
3062 }
3063 };
3067 class RemoveSelfPointerClosure: public ObjectClosure {
3068 private:
3069 G1CollectedHeap* _g1;
3070 ConcurrentMark* _cm;
3071 HeapRegion* _hr;
3072 size_t _prev_marked_bytes;
3073 size_t _next_marked_bytes;
3074 OopsInHeapRegionClosure *_cl;
3075 public:
3076 RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
3077 _g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3078 _next_marked_bytes(0), _cl(cl) {}
3080 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3081 size_t next_marked_bytes() { return _next_marked_bytes; }
3083 // The original idea here was to coalesce evacuated and dead objects.
3084 // However that caused complications with the block offset table (BOT).
3085 // In particular if there were two TLABs, one of them partially refined.
3086 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3087 // The BOT entries of the unrefined part of TLAB_2 point to the start
3088 // of TLAB_2. If the last object of the TLAB_1 and the first object
3089 // of TLAB_2 are coalesced, then the cards of the unrefined part
3090 // would point into middle of the filler object.
3091 //
3092 // The current approach is to not coalesce and leave the BOT contents intact.
3093 void do_object(oop obj) {
3094 if (obj->is_forwarded() && obj->forwardee() == obj) {
3095 // The object failed to move.
3096 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3097 _cm->markPrev(obj);
3098 assert(_cm->isPrevMarked(obj), "Should be marked!");
3099 _prev_marked_bytes += (obj->size() * HeapWordSize);
3100 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3101 _cm->markAndGrayObjectIfNecessary(obj);
3102 }
3103 obj->set_mark(markOopDesc::prototype());
3104 // While we were processing RSet buffers during the
3105 // collection, we actually didn't scan any cards on the
3106 // collection set, since we didn't want to update remebered
3107 // sets with entries that point into the collection set, given
3108 // that live objects fromthe collection set are about to move
3109 // and such entries will be stale very soon. This change also
3110 // dealt with a reliability issue which involved scanning a
3111 // card in the collection set and coming across an array that
3112 // was being chunked and looking malformed. The problem is
3113 // that, if evacuation fails, we might have remembered set
3114 // entries missing given that we skipped cards on the
3115 // collection set. So, we'll recreate such entries now.
3116 obj->oop_iterate(_cl);
3117 assert(_cm->isPrevMarked(obj), "Should be marked!");
3118 } else {
3119 // The object has been either evacuated or is dead. Fill it with a
3120 // dummy object.
3121 MemRegion mr((HeapWord*)obj, obj->size());
3122 CollectedHeap::fill_with_object(mr);
3123 _cm->clearRangeBothMaps(mr);
3124 }
3125 }
3126 };
3128 void G1CollectedHeap::remove_self_forwarding_pointers() {
3129 UpdateRSetImmediate immediate_update(_g1h);
3130 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3131 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3132 OopsInHeapRegionClosure *cl;
3133 if (G1DeferredRSUpdate) {
3134 cl = &deferred_update;
3135 } else {
3136 cl = &immediate_update;
3137 }
3138 HeapRegion* cur = g1_policy()->collection_set();
3139 while (cur != NULL) {
3140 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3142 RemoveSelfPointerClosure rspc(_g1h, cl);
3143 if (cur->evacuation_failed()) {
3144 assert(cur->in_collection_set(), "bad CS");
3145 cl->set_region(cur);
3146 cur->object_iterate(&rspc);
3148 // A number of manipulations to make the TAMS be the current top,
3149 // and the marked bytes be the ones observed in the iteration.
3150 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3151 // The comments below are the postconditions achieved by the
3152 // calls. Note especially the last such condition, which says that
3153 // the count of marked bytes has been properly restored.
3154 cur->note_start_of_marking(false);
3155 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3156 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3157 // _next_marked_bytes == prev_marked_bytes.
3158 cur->note_end_of_marking();
3159 // _prev_top_at_mark_start == top(),
3160 // _prev_marked_bytes == prev_marked_bytes
3161 }
3162 // If there is no mark in progress, we modified the _next variables
3163 // above needlessly, but harmlessly.
3164 if (_g1h->mark_in_progress()) {
3165 cur->note_start_of_marking(false);
3166 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3167 // _next_marked_bytes == next_marked_bytes.
3168 }
3170 // Now make sure the region has the right index in the sorted array.
3171 g1_policy()->note_change_in_marked_bytes(cur);
3172 }
3173 cur = cur->next_in_collection_set();
3174 }
3175 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3177 // Now restore saved marks, if any.
3178 if (_objs_with_preserved_marks != NULL) {
3179 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3180 assert(_objs_with_preserved_marks->length() ==
3181 _preserved_marks_of_objs->length(), "Both or none.");
3182 guarantee(_objs_with_preserved_marks->length() ==
3183 _preserved_marks_of_objs->length(), "Both or none.");
3184 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3185 oop obj = _objs_with_preserved_marks->at(i);
3186 markOop m = _preserved_marks_of_objs->at(i);
3187 obj->set_mark(m);
3188 }
3189 // Delete the preserved marks growable arrays (allocated on the C heap).
3190 delete _objs_with_preserved_marks;
3191 delete _preserved_marks_of_objs;
3192 _objs_with_preserved_marks = NULL;
3193 _preserved_marks_of_objs = NULL;
3194 }
3195 }
3197 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3198 _evac_failure_scan_stack->push(obj);
3199 }
3201 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3202 assert(_evac_failure_scan_stack != NULL, "precondition");
3204 while (_evac_failure_scan_stack->length() > 0) {
3205 oop obj = _evac_failure_scan_stack->pop();
3206 _evac_failure_closure->set_region(heap_region_containing(obj));
3207 obj->oop_iterate_backwards(_evac_failure_closure);
3208 }
3209 }
3211 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3212 markOop m = old->mark();
3213 // forward to self
3214 assert(!old->is_forwarded(), "precondition");
3216 old->forward_to(old);
3217 handle_evacuation_failure_common(old, m);
3218 }
3220 oop
3221 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3222 oop old) {
3223 markOop m = old->mark();
3224 oop forward_ptr = old->forward_to_atomic(old);
3225 if (forward_ptr == NULL) {
3226 // Forward-to-self succeeded.
3227 if (_evac_failure_closure != cl) {
3228 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3229 assert(!_drain_in_progress,
3230 "Should only be true while someone holds the lock.");
3231 // Set the global evac-failure closure to the current thread's.
3232 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3233 set_evac_failure_closure(cl);
3234 // Now do the common part.
3235 handle_evacuation_failure_common(old, m);
3236 // Reset to NULL.
3237 set_evac_failure_closure(NULL);
3238 } else {
3239 // The lock is already held, and this is recursive.
3240 assert(_drain_in_progress, "This should only be the recursive case.");
3241 handle_evacuation_failure_common(old, m);
3242 }
3243 return old;
3244 } else {
3245 // Someone else had a place to copy it.
3246 return forward_ptr;
3247 }
3248 }
3250 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3251 set_evacuation_failed(true);
3253 preserve_mark_if_necessary(old, m);
3255 HeapRegion* r = heap_region_containing(old);
3256 if (!r->evacuation_failed()) {
3257 r->set_evacuation_failed(true);
3258 if (G1TraceRegions) {
3259 gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
3260 "["PTR_FORMAT","PTR_FORMAT")\n",
3261 r, r->bottom(), r->end());
3262 }
3263 }
3265 push_on_evac_failure_scan_stack(old);
3267 if (!_drain_in_progress) {
3268 // prevent recursion in copy_to_survivor_space()
3269 _drain_in_progress = true;
3270 drain_evac_failure_scan_stack();
3271 _drain_in_progress = false;
3272 }
3273 }
3275 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3276 if (m != markOopDesc::prototype()) {
3277 if (_objs_with_preserved_marks == NULL) {
3278 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3279 _objs_with_preserved_marks =
3280 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3281 _preserved_marks_of_objs =
3282 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3283 }
3284 _objs_with_preserved_marks->push(obj);
3285 _preserved_marks_of_objs->push(m);
3286 }
3287 }
3289 // *** Parallel G1 Evacuation
3291 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3292 size_t word_size) {
3293 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3294 // let the caller handle alloc failure
3295 if (alloc_region == NULL) return NULL;
3297 HeapWord* block = alloc_region->par_allocate(word_size);
3298 if (block == NULL) {
3299 MutexLockerEx x(par_alloc_during_gc_lock(),
3300 Mutex::_no_safepoint_check_flag);
3301 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3302 }
3303 return block;
3304 }
3306 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
3307 bool par) {
3308 // Another thread might have obtained alloc_region for the given
3309 // purpose, and might be attempting to allocate in it, and might
3310 // succeed. Therefore, we can't do the "finalization" stuff on the
3311 // region below until we're sure the last allocation has happened.
3312 // We ensure this by allocating the remaining space with a garbage
3313 // object.
3314 if (par) par_allocate_remaining_space(alloc_region);
3315 // Now we can do the post-GC stuff on the region.
3316 alloc_region->note_end_of_copying();
3317 g1_policy()->record_after_bytes(alloc_region->used());
3318 }
3320 HeapWord*
3321 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3322 HeapRegion* alloc_region,
3323 bool par,
3324 size_t word_size) {
3325 HeapWord* block = NULL;
3326 // In the parallel case, a previous thread to obtain the lock may have
3327 // already assigned a new gc_alloc_region.
3328 if (alloc_region != _gc_alloc_regions[purpose]) {
3329 assert(par, "But should only happen in parallel case.");
3330 alloc_region = _gc_alloc_regions[purpose];
3331 if (alloc_region == NULL) return NULL;
3332 block = alloc_region->par_allocate(word_size);
3333 if (block != NULL) return block;
3334 // Otherwise, continue; this new region is empty, too.
3335 }
3336 assert(alloc_region != NULL, "We better have an allocation region");
3337 retire_alloc_region(alloc_region, par);
3339 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3340 // Cannot allocate more regions for the given purpose.
3341 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3342 // Is there an alternative?
3343 if (purpose != alt_purpose) {
3344 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3345 // Has not the alternative region been aliased?
3346 if (alloc_region != alt_region && alt_region != NULL) {
3347 // Try to allocate in the alternative region.
3348 if (par) {
3349 block = alt_region->par_allocate(word_size);
3350 } else {
3351 block = alt_region->allocate(word_size);
3352 }
3353 // Make an alias.
3354 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3355 if (block != NULL) {
3356 return block;
3357 }
3358 retire_alloc_region(alt_region, par);
3359 }
3360 // Both the allocation region and the alternative one are full
3361 // and aliased, replace them with a new allocation region.
3362 purpose = alt_purpose;
3363 } else {
3364 set_gc_alloc_region(purpose, NULL);
3365 return NULL;
3366 }
3367 }
3369 // Now allocate a new region for allocation.
3370 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3372 // let the caller handle alloc failure
3373 if (alloc_region != NULL) {
3375 assert(check_gc_alloc_regions(), "alloc regions messed up");
3376 assert(alloc_region->saved_mark_at_top(),
3377 "Mark should have been saved already.");
3378 // We used to assert that the region was zero-filled here, but no
3379 // longer.
3381 // This must be done last: once it's installed, other regions may
3382 // allocate in it (without holding the lock.)
3383 set_gc_alloc_region(purpose, alloc_region);
3385 if (par) {
3386 block = alloc_region->par_allocate(word_size);
3387 } else {
3388 block = alloc_region->allocate(word_size);
3389 }
3390 // Caller handles alloc failure.
3391 } else {
3392 // This sets other apis using the same old alloc region to NULL, also.
3393 set_gc_alloc_region(purpose, NULL);
3394 }
3395 return block; // May be NULL.
3396 }
3398 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3399 HeapWord* block = NULL;
3400 size_t free_words;
3401 do {
3402 free_words = r->free()/HeapWordSize;
3403 // If there's too little space, no one can allocate, so we're done.
3404 if (free_words < (size_t)oopDesc::header_size()) return;
3405 // Otherwise, try to claim it.
3406 block = r->par_allocate(free_words);
3407 } while (block == NULL);
3408 fill_with_object(block, free_words);
3409 }
3411 #define use_local_bitmaps 1
3412 #define verify_local_bitmaps 0
3414 #ifndef PRODUCT
3416 class GCLabBitMap;
3417 class GCLabBitMapClosure: public BitMapClosure {
3418 private:
3419 ConcurrentMark* _cm;
3420 GCLabBitMap* _bitmap;
3422 public:
3423 GCLabBitMapClosure(ConcurrentMark* cm,
3424 GCLabBitMap* bitmap) {
3425 _cm = cm;
3426 _bitmap = bitmap;
3427 }
3429 virtual bool do_bit(size_t offset);
3430 };
3432 #endif // PRODUCT
3434 #define oop_buffer_length 256
3436 class GCLabBitMap: public BitMap {
3437 private:
3438 ConcurrentMark* _cm;
3440 int _shifter;
3441 size_t _bitmap_word_covers_words;
3443 // beginning of the heap
3444 HeapWord* _heap_start;
3446 // this is the actual start of the GCLab
3447 HeapWord* _real_start_word;
3449 // this is the actual end of the GCLab
3450 HeapWord* _real_end_word;
3452 // this is the first word, possibly located before the actual start
3453 // of the GCLab, that corresponds to the first bit of the bitmap
3454 HeapWord* _start_word;
3456 // size of a GCLab in words
3457 size_t _gclab_word_size;
3459 static int shifter() {
3460 return MinObjAlignment - 1;
3461 }
3463 // how many heap words does a single bitmap word corresponds to?
3464 static size_t bitmap_word_covers_words() {
3465 return BitsPerWord << shifter();
3466 }
3468 static size_t gclab_word_size() {
3469 return ParallelGCG1AllocBufferSize / HeapWordSize;
3470 }
3472 static size_t bitmap_size_in_bits() {
3473 size_t bits_in_bitmap = gclab_word_size() >> shifter();
3474 // We are going to ensure that the beginning of a word in this
3475 // bitmap also corresponds to the beginning of a word in the
3476 // global marking bitmap. To handle the case where a GCLab
3477 // starts from the middle of the bitmap, we need to add enough
3478 // space (i.e. up to a bitmap word) to ensure that we have
3479 // enough bits in the bitmap.
3480 return bits_in_bitmap + BitsPerWord - 1;
3481 }
3482 public:
3483 GCLabBitMap(HeapWord* heap_start)
3484 : BitMap(bitmap_size_in_bits()),
3485 _cm(G1CollectedHeap::heap()->concurrent_mark()),
3486 _shifter(shifter()),
3487 _bitmap_word_covers_words(bitmap_word_covers_words()),
3488 _heap_start(heap_start),
3489 _gclab_word_size(gclab_word_size()),
3490 _real_start_word(NULL),
3491 _real_end_word(NULL),
3492 _start_word(NULL)
3493 {
3494 guarantee( size_in_words() >= bitmap_size_in_words(),
3495 "just making sure");
3496 }
3498 inline unsigned heapWordToOffset(HeapWord* addr) {
3499 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
3500 assert(offset < size(), "offset should be within bounds");
3501 return offset;
3502 }
3504 inline HeapWord* offsetToHeapWord(size_t offset) {
3505 HeapWord* addr = _start_word + (offset << _shifter);
3506 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
3507 return addr;
3508 }
3510 bool fields_well_formed() {
3511 bool ret1 = (_real_start_word == NULL) &&
3512 (_real_end_word == NULL) &&
3513 (_start_word == NULL);
3514 if (ret1)
3515 return true;
3517 bool ret2 = _real_start_word >= _start_word &&
3518 _start_word < _real_end_word &&
3519 (_real_start_word + _gclab_word_size) == _real_end_word &&
3520 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
3521 > _real_end_word;
3522 return ret2;
3523 }
3525 inline bool mark(HeapWord* addr) {
3526 guarantee(use_local_bitmaps, "invariant");
3527 assert(fields_well_formed(), "invariant");
3529 if (addr >= _real_start_word && addr < _real_end_word) {
3530 assert(!isMarked(addr), "should not have already been marked");
3532 // first mark it on the bitmap
3533 at_put(heapWordToOffset(addr), true);
3535 return true;
3536 } else {
3537 return false;
3538 }
3539 }
3541 inline bool isMarked(HeapWord* addr) {
3542 guarantee(use_local_bitmaps, "invariant");
3543 assert(fields_well_formed(), "invariant");
3545 return at(heapWordToOffset(addr));
3546 }
3548 void set_buffer(HeapWord* start) {
3549 guarantee(use_local_bitmaps, "invariant");
3550 clear();
3552 assert(start != NULL, "invariant");
3553 _real_start_word = start;
3554 _real_end_word = start + _gclab_word_size;
3556 size_t diff =
3557 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
3558 _start_word = start - diff;
3560 assert(fields_well_formed(), "invariant");
3561 }
3563 #ifndef PRODUCT
3564 void verify() {
3565 // verify that the marks have been propagated
3566 GCLabBitMapClosure cl(_cm, this);
3567 iterate(&cl);
3568 }
3569 #endif // PRODUCT
3571 void retire() {
3572 guarantee(use_local_bitmaps, "invariant");
3573 assert(fields_well_formed(), "invariant");
3575 if (_start_word != NULL) {
3576 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
3578 // this means that the bitmap was set up for the GCLab
3579 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
3581 mark_bitmap->mostly_disjoint_range_union(this,
3582 0, // always start from the start of the bitmap
3583 _start_word,
3584 size_in_words());
3585 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
3587 #ifndef PRODUCT
3588 if (use_local_bitmaps && verify_local_bitmaps)
3589 verify();
3590 #endif // PRODUCT
3591 } else {
3592 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
3593 }
3594 }
3596 static size_t bitmap_size_in_words() {
3597 return (bitmap_size_in_bits() + BitsPerWord - 1) / BitsPerWord;
3598 }
3599 };
3601 #ifndef PRODUCT
3603 bool GCLabBitMapClosure::do_bit(size_t offset) {
3604 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3605 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3606 return true;
3607 }
3609 #endif // PRODUCT
3611 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
3612 private:
3613 bool _retired;
3614 bool _during_marking;
3615 GCLabBitMap _bitmap;
3617 public:
3618 G1ParGCAllocBuffer() :
3619 ParGCAllocBuffer(ParallelGCG1AllocBufferSize / HeapWordSize),
3620 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
3621 _bitmap(G1CollectedHeap::heap()->reserved_region().start()),
3622 _retired(false)
3623 { }
3625 inline bool mark(HeapWord* addr) {
3626 guarantee(use_local_bitmaps, "invariant");
3627 assert(_during_marking, "invariant");
3628 return _bitmap.mark(addr);
3629 }
3631 inline void set_buf(HeapWord* buf) {
3632 if (use_local_bitmaps && _during_marking)
3633 _bitmap.set_buffer(buf);
3634 ParGCAllocBuffer::set_buf(buf);
3635 _retired = false;
3636 }
3638 inline void retire(bool end_of_gc, bool retain) {
3639 if (_retired)
3640 return;
3641 if (use_local_bitmaps && _during_marking) {
3642 _bitmap.retire();
3643 }
3644 ParGCAllocBuffer::retire(end_of_gc, retain);
3645 _retired = true;
3646 }
3647 };
3650 class G1ParScanThreadState : public StackObj {
3651 protected:
3652 G1CollectedHeap* _g1h;
3653 RefToScanQueue* _refs;
3654 DirtyCardQueue _dcq;
3655 CardTableModRefBS* _ct_bs;
3656 G1RemSet* _g1_rem;
3658 typedef GrowableArray<oop*> OverflowQueue;
3659 OverflowQueue* _overflowed_refs;
3661 G1ParGCAllocBuffer _alloc_buffers[GCAllocPurposeCount];
3662 ageTable _age_table;
3664 size_t _alloc_buffer_waste;
3665 size_t _undo_waste;
3667 OopsInHeapRegionClosure* _evac_failure_cl;
3668 G1ParScanHeapEvacClosure* _evac_cl;
3669 G1ParScanPartialArrayClosure* _partial_scan_cl;
3671 int _hash_seed;
3672 int _queue_num;
3674 int _term_attempts;
3675 #if G1_DETAILED_STATS
3676 int _pushes, _pops, _steals, _steal_attempts;
3677 int _overflow_pushes;
3678 #endif
3680 double _start;
3681 double _start_strong_roots;
3682 double _strong_roots_time;
3683 double _start_term;
3684 double _term_time;
3686 // Map from young-age-index (0 == not young, 1 is youngest) to
3687 // surviving words. base is what we get back from the malloc call
3688 size_t* _surviving_young_words_base;
3689 // this points into the array, as we use the first few entries for padding
3690 size_t* _surviving_young_words;
3692 #define PADDING_ELEM_NUM (64 / sizeof(size_t))
3694 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
3696 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
3698 DirtyCardQueue& dirty_card_queue() { return _dcq; }
3699 CardTableModRefBS* ctbs() { return _ct_bs; }
3701 void immediate_rs_update(HeapRegion* from, oop* p, int tid) {
3702 if (!from->is_survivor()) {
3703 _g1_rem->par_write_ref(from, p, tid);
3704 }
3705 }
3707 void deferred_rs_update(HeapRegion* from, oop* p, int tid) {
3708 // If the new value of the field points to the same region or
3709 // is the to-space, we don't need to include it in the Rset updates.
3710 if (!from->is_in_reserved(*p) && !from->is_survivor()) {
3711 size_t card_index = ctbs()->index_for(p);
3712 // If the card hasn't been added to the buffer, do it.
3713 if (ctbs()->mark_card_deferred(card_index)) {
3714 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
3715 }
3716 }
3717 }
3719 public:
3720 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3721 : _g1h(g1h),
3722 _refs(g1h->task_queue(queue_num)),
3723 _dcq(&g1h->dirty_card_queue_set()),
3724 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
3725 _g1_rem(g1h->g1_rem_set()),
3726 _hash_seed(17), _queue_num(queue_num),
3727 _term_attempts(0),
3728 _age_table(false),
3729 #if G1_DETAILED_STATS
3730 _pushes(0), _pops(0), _steals(0),
3731 _steal_attempts(0), _overflow_pushes(0),
3732 #endif
3733 _strong_roots_time(0), _term_time(0),
3734 _alloc_buffer_waste(0), _undo_waste(0)
3735 {
3736 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3737 // we "sacrifice" entry 0 to keep track of surviving bytes for
3738 // non-young regions (where the age is -1)
3739 // We also add a few elements at the beginning and at the end in
3740 // an attempt to eliminate cache contention
3741 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3742 size_t array_length = PADDING_ELEM_NUM +
3743 real_length +
3744 PADDING_ELEM_NUM;
3745 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3746 if (_surviving_young_words_base == NULL)
3747 vm_exit_out_of_memory(array_length * sizeof(size_t),
3748 "Not enough space for young surv histo.");
3749 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3750 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3752 _overflowed_refs = new OverflowQueue(10);
3754 _start = os::elapsedTime();
3755 }
3757 ~G1ParScanThreadState() {
3758 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
3759 }
3761 RefToScanQueue* refs() { return _refs; }
3762 OverflowQueue* overflowed_refs() { return _overflowed_refs; }
3763 ageTable* age_table() { return &_age_table; }
3765 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
3766 return &_alloc_buffers[purpose];
3767 }
3769 size_t alloc_buffer_waste() { return _alloc_buffer_waste; }
3770 size_t undo_waste() { return _undo_waste; }
3772 void push_on_queue(oop* ref) {
3773 assert(ref != NULL, "invariant");
3774 assert(has_partial_array_mask(ref) || _g1h->obj_in_cs(*ref), "invariant");
3776 if (!refs()->push(ref)) {
3777 overflowed_refs()->push(ref);
3778 IF_G1_DETAILED_STATS(note_overflow_push());
3779 } else {
3780 IF_G1_DETAILED_STATS(note_push());
3781 }
3782 }
3784 void pop_from_queue(oop*& ref) {
3785 if (!refs()->pop_local(ref)) {
3786 ref = NULL;
3787 } else {
3788 assert(ref != NULL, "invariant");
3789 assert(has_partial_array_mask(ref) || _g1h->obj_in_cs(*ref),
3790 "invariant");
3792 IF_G1_DETAILED_STATS(note_pop());
3793 }
3794 }
3796 void pop_from_overflow_queue(oop*& ref) {
3797 ref = overflowed_refs()->pop();
3798 }
3800 int refs_to_scan() { return refs()->size(); }
3801 int overflowed_refs_to_scan() { return overflowed_refs()->length(); }
3803 void update_rs(HeapRegion* from, oop* p, int tid) {
3804 if (G1DeferredRSUpdate) {
3805 deferred_rs_update(from, p, tid);
3806 } else {
3807 immediate_rs_update(from, p, tid);
3808 }
3809 }
3811 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
3813 HeapWord* obj = NULL;
3814 if (word_sz * 100 <
3815 (size_t)(ParallelGCG1AllocBufferSize / HeapWordSize) *
3816 ParallelGCBufferWastePct) {
3817 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
3818 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
3819 alloc_buf->retire(false, false);
3821 HeapWord* buf =
3822 _g1h->par_allocate_during_gc(purpose, ParallelGCG1AllocBufferSize / HeapWordSize);
3823 if (buf == NULL) return NULL; // Let caller handle allocation failure.
3824 // Otherwise.
3825 alloc_buf->set_buf(buf);
3827 obj = alloc_buf->allocate(word_sz);
3828 assert(obj != NULL, "buffer was definitely big enough...");
3829 } else {
3830 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
3831 }
3832 return obj;
3833 }
3835 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
3836 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
3837 if (obj != NULL) return obj;
3838 return allocate_slow(purpose, word_sz);
3839 }
3841 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
3842 if (alloc_buffer(purpose)->contains(obj)) {
3843 guarantee(alloc_buffer(purpose)->contains(obj + word_sz - 1),
3844 "should contain whole object");
3845 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
3846 } else {
3847 CollectedHeap::fill_with_object(obj, word_sz);
3848 add_to_undo_waste(word_sz);
3849 }
3850 }
3852 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
3853 _evac_failure_cl = evac_failure_cl;
3854 }
3855 OopsInHeapRegionClosure* evac_failure_closure() {
3856 return _evac_failure_cl;
3857 }
3859 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
3860 _evac_cl = evac_cl;
3861 }
3863 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
3864 _partial_scan_cl = partial_scan_cl;
3865 }
3867 int* hash_seed() { return &_hash_seed; }
3868 int queue_num() { return _queue_num; }
3870 int term_attempts() { return _term_attempts; }
3871 void note_term_attempt() { _term_attempts++; }
3873 #if G1_DETAILED_STATS
3874 int pushes() { return _pushes; }
3875 int pops() { return _pops; }
3876 int steals() { return _steals; }
3877 int steal_attempts() { return _steal_attempts; }
3878 int overflow_pushes() { return _overflow_pushes; }
3880 void note_push() { _pushes++; }
3881 void note_pop() { _pops++; }
3882 void note_steal() { _steals++; }
3883 void note_steal_attempt() { _steal_attempts++; }
3884 void note_overflow_push() { _overflow_pushes++; }
3885 #endif
3887 void start_strong_roots() {
3888 _start_strong_roots = os::elapsedTime();
3889 }
3890 void end_strong_roots() {
3891 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
3892 }
3893 double strong_roots_time() { return _strong_roots_time; }
3895 void start_term_time() {
3896 note_term_attempt();
3897 _start_term = os::elapsedTime();
3898 }
3899 void end_term_time() {
3900 _term_time += (os::elapsedTime() - _start_term);
3901 }
3902 double term_time() { return _term_time; }
3904 double elapsed() {
3905 return os::elapsedTime() - _start;
3906 }
3908 size_t* surviving_young_words() {
3909 // We add on to hide entry 0 which accumulates surviving words for
3910 // age -1 regions (i.e. non-young ones)
3911 return _surviving_young_words;
3912 }
3914 void retire_alloc_buffers() {
3915 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3916 size_t waste = _alloc_buffers[ap].words_remaining();
3917 add_to_alloc_buffer_waste(waste);
3918 _alloc_buffers[ap].retire(true, false);
3919 }
3920 }
3922 private:
3923 void deal_with_reference(oop* ref_to_scan) {
3924 if (has_partial_array_mask(ref_to_scan)) {
3925 _partial_scan_cl->do_oop_nv(ref_to_scan);
3926 } else {
3927 // Note: we can use "raw" versions of "region_containing" because
3928 // "obj_to_scan" is definitely in the heap, and is not in a
3929 // humongous region.
3930 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
3931 _evac_cl->set_region(r);
3932 _evac_cl->do_oop_nv(ref_to_scan);
3933 }
3934 }
3936 public:
3937 void trim_queue() {
3938 // I've replicated the loop twice, first to drain the overflow
3939 // queue, second to drain the task queue. This is better than
3940 // having a single loop, which checks both conditions and, inside
3941 // it, either pops the overflow queue or the task queue, as each
3942 // loop is tighter. Also, the decision to drain the overflow queue
3943 // first is not arbitrary, as the overflow queue is not visible
3944 // to the other workers, whereas the task queue is. So, we want to
3945 // drain the "invisible" entries first, while allowing the other
3946 // workers to potentially steal the "visible" entries.
3948 while (refs_to_scan() > 0 || overflowed_refs_to_scan() > 0) {
3949 while (overflowed_refs_to_scan() > 0) {
3950 oop *ref_to_scan = NULL;
3951 pop_from_overflow_queue(ref_to_scan);
3952 assert(ref_to_scan != NULL, "invariant");
3953 // We shouldn't have pushed it on the queue if it was not
3954 // pointing into the CSet.
3955 assert(ref_to_scan != NULL, "sanity");
3956 assert(has_partial_array_mask(ref_to_scan) ||
3957 _g1h->obj_in_cs(*ref_to_scan), "sanity");
3959 deal_with_reference(ref_to_scan);
3960 }
3962 while (refs_to_scan() > 0) {
3963 oop *ref_to_scan = NULL;
3964 pop_from_queue(ref_to_scan);
3966 if (ref_to_scan != NULL) {
3967 // We shouldn't have pushed it on the queue if it was not
3968 // pointing into the CSet.
3969 assert(has_partial_array_mask(ref_to_scan) ||
3970 _g1h->obj_in_cs(*ref_to_scan), "sanity");
3972 deal_with_reference(ref_to_scan);
3973 }
3974 }
3975 }
3976 }
3977 };
3979 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
3980 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
3981 _par_scan_state(par_scan_state) { }
3983 // This closure is applied to the fields of the objects that have just been copied.
3984 // Should probably be made inline and moved in g1OopClosures.inline.hpp.
3985 void G1ParScanClosure::do_oop_nv(oop* p) {
3986 oop obj = *p;
3988 if (obj != NULL) {
3989 if (_g1->in_cset_fast_test(obj)) {
3990 // We're not going to even bother checking whether the object is
3991 // already forwarded or not, as this usually causes an immediate
3992 // stall. We'll try to prefetch the object (for write, given that
3993 // we might need to install the forwarding reference) and we'll
3994 // get back to it when pop it from the queue
3995 Prefetch::write(obj->mark_addr(), 0);
3996 Prefetch::read(obj->mark_addr(), (HeapWordSize*2));
3998 // slightly paranoid test; I'm trying to catch potential
3999 // problems before we go into push_on_queue to know where the
4000 // problem is coming from
4001 assert(obj == *p, "the value of *p should not have changed");
4002 _par_scan_state->push_on_queue(p);
4003 } else {
4004 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4005 }
4006 }
4007 }
4009 void G1ParCopyHelper::mark_forwardee(oop* p) {
4010 // This is called _after_ do_oop_work has been called, hence after
4011 // the object has been relocated to its new location and *p points
4012 // to its new location.
4014 oop thisOop = *p;
4015 if (thisOop != NULL) {
4016 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(thisOop)),
4017 "shouldn't still be in the CSet if evacuation didn't fail.");
4018 HeapWord* addr = (HeapWord*)thisOop;
4019 if (_g1->is_in_g1_reserved(addr))
4020 _cm->grayRoot(oop(addr));
4021 }
4022 }
4024 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
4025 size_t word_sz = old->size();
4026 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4027 // +1 to make the -1 indexes valid...
4028 int young_index = from_region->young_index_in_cset()+1;
4029 assert( (from_region->is_young() && young_index > 0) ||
4030 (!from_region->is_young() && young_index == 0), "invariant" );
4031 G1CollectorPolicy* g1p = _g1->g1_policy();
4032 markOop m = old->mark();
4033 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4034 : m->age();
4035 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4036 word_sz);
4037 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4038 oop obj = oop(obj_ptr);
4040 if (obj_ptr == NULL) {
4041 // This will either forward-to-self, or detect that someone else has
4042 // installed a forwarding pointer.
4043 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4044 return _g1->handle_evacuation_failure_par(cl, old);
4045 }
4047 // We're going to allocate linearly, so might as well prefetch ahead.
4048 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4050 oop forward_ptr = old->forward_to_atomic(obj);
4051 if (forward_ptr == NULL) {
4052 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4053 if (g1p->track_object_age(alloc_purpose)) {
4054 // We could simply do obj->incr_age(). However, this causes a
4055 // performance issue. obj->incr_age() will first check whether
4056 // the object has a displaced mark by checking its mark word;
4057 // getting the mark word from the new location of the object
4058 // stalls. So, given that we already have the mark word and we
4059 // are about to install it anyway, it's better to increase the
4060 // age on the mark word, when the object does not have a
4061 // displaced mark word. We're not expecting many objects to have
4062 // a displaced marked word, so that case is not optimized
4063 // further (it could be...) and we simply call obj->incr_age().
4065 if (m->has_displaced_mark_helper()) {
4066 // in this case, we have to install the mark word first,
4067 // otherwise obj looks to be forwarded (the old mark word,
4068 // which contains the forward pointer, was copied)
4069 obj->set_mark(m);
4070 obj->incr_age();
4071 } else {
4072 m = m->incr_age();
4073 obj->set_mark(m);
4074 }
4075 _par_scan_state->age_table()->add(obj, word_sz);
4076 } else {
4077 obj->set_mark(m);
4078 }
4080 // preserve "next" mark bit
4081 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
4082 if (!use_local_bitmaps ||
4083 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4084 // if we couldn't mark it on the local bitmap (this happens when
4085 // the object was not allocated in the GCLab), we have to bite
4086 // the bullet and do the standard parallel mark
4087 _cm->markAndGrayObjectIfNecessary(obj);
4088 }
4089 #if 1
4090 if (_g1->isMarkedNext(old)) {
4091 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4092 }
4093 #endif
4094 }
4096 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4097 surv_young_words[young_index] += word_sz;
4099 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4100 arrayOop(old)->set_length(0);
4101 _par_scan_state->push_on_queue(set_partial_array_mask(old));
4102 } else {
4103 // No point in using the slower heap_region_containing() method,
4104 // given that we know obj is in the heap.
4105 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4106 obj->oop_iterate_backwards(_scanner);
4107 }
4108 } else {
4109 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4110 obj = forward_ptr;
4111 }
4112 return obj;
4113 }
4115 template<bool do_gen_barrier, G1Barrier barrier,
4116 bool do_mark_forwardee, bool skip_cset_test>
4117 void G1ParCopyClosure<do_gen_barrier, barrier,
4118 do_mark_forwardee, skip_cset_test>::do_oop_work(oop* p) {
4119 oop obj = *p;
4120 assert(barrier != G1BarrierRS || obj != NULL,
4121 "Precondition: G1BarrierRS implies obj is nonNull");
4123 // The only time we skip the cset test is when we're scanning
4124 // references popped from the queue. And we only push on the queue
4125 // references that we know point into the cset, so no point in
4126 // checking again. But we'll leave an assert here for peace of mind.
4127 assert(!skip_cset_test || _g1->obj_in_cs(obj), "invariant");
4129 // here the null check is implicit in the cset_fast_test() test
4130 if (skip_cset_test || _g1->in_cset_fast_test(obj)) {
4131 #if G1_REM_SET_LOGGING
4132 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
4133 "into CS.", p, (void*) obj);
4134 #endif
4135 if (obj->is_forwarded()) {
4136 *p = obj->forwardee();
4137 } else {
4138 *p = copy_to_survivor_space(obj);
4139 }
4140 // When scanning the RS, we only care about objs in CS.
4141 if (barrier == G1BarrierRS) {
4142 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4143 }
4144 }
4146 // When scanning moved objs, must look at all oops.
4147 if (barrier == G1BarrierEvac && obj != NULL) {
4148 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4149 }
4151 if (do_gen_barrier && obj != NULL) {
4152 par_do_barrier(p);
4153 }
4154 }
4156 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(oop* p);
4158 template<class T> void G1ParScanPartialArrayClosure::process_array_chunk(
4159 oop obj, int start, int end) {
4160 // process our set of indices (include header in first chunk)
4161 assert(start < end, "invariant");
4162 T* const base = (T*)objArrayOop(obj)->base();
4163 T* const start_addr = (start == 0) ? (T*) obj : base + start;
4164 T* const end_addr = base + end;
4165 MemRegion mr((HeapWord*)start_addr, (HeapWord*)end_addr);
4166 _scanner.set_region(_g1->heap_region_containing(obj));
4167 obj->oop_iterate(&_scanner, mr);
4168 }
4170 void G1ParScanPartialArrayClosure::do_oop_nv(oop* p) {
4171 assert(!UseCompressedOops, "Needs to be fixed to work with compressed oops");
4172 assert(has_partial_array_mask(p), "invariant");
4173 oop old = clear_partial_array_mask(p);
4174 assert(old->is_objArray(), "must be obj array");
4175 assert(old->is_forwarded(), "must be forwarded");
4176 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4178 objArrayOop obj = objArrayOop(old->forwardee());
4179 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4180 // Process ParGCArrayScanChunk elements now
4181 // and push the remainder back onto queue
4182 int start = arrayOop(old)->length();
4183 int end = obj->length();
4184 int remainder = end - start;
4185 assert(start <= end, "just checking");
4186 if (remainder > 2 * ParGCArrayScanChunk) {
4187 // Test above combines last partial chunk with a full chunk
4188 end = start + ParGCArrayScanChunk;
4189 arrayOop(old)->set_length(end);
4190 // Push remainder.
4191 _par_scan_state->push_on_queue(set_partial_array_mask(old));
4192 } else {
4193 // Restore length so that the heap remains parsable in
4194 // case of evacuation failure.
4195 arrayOop(old)->set_length(end);
4196 }
4198 // process our set of indices (include header in first chunk)
4199 process_array_chunk<oop>(obj, start, end);
4200 }
4202 int G1ScanAndBalanceClosure::_nq = 0;
4204 class G1ParEvacuateFollowersClosure : public VoidClosure {
4205 protected:
4206 G1CollectedHeap* _g1h;
4207 G1ParScanThreadState* _par_scan_state;
4208 RefToScanQueueSet* _queues;
4209 ParallelTaskTerminator* _terminator;
4211 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4212 RefToScanQueueSet* queues() { return _queues; }
4213 ParallelTaskTerminator* terminator() { return _terminator; }
4215 public:
4216 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4217 G1ParScanThreadState* par_scan_state,
4218 RefToScanQueueSet* queues,
4219 ParallelTaskTerminator* terminator)
4220 : _g1h(g1h), _par_scan_state(par_scan_state),
4221 _queues(queues), _terminator(terminator) {}
4223 void do_void() {
4224 G1ParScanThreadState* pss = par_scan_state();
4225 while (true) {
4226 oop* ref_to_scan;
4227 pss->trim_queue();
4228 IF_G1_DETAILED_STATS(pss->note_steal_attempt());
4229 if (queues()->steal(pss->queue_num(),
4230 pss->hash_seed(),
4231 ref_to_scan)) {
4232 IF_G1_DETAILED_STATS(pss->note_steal());
4234 // slightly paranoid tests; I'm trying to catch potential
4235 // problems before we go into push_on_queue to know where the
4236 // problem is coming from
4237 assert(ref_to_scan != NULL, "invariant");
4238 assert(has_partial_array_mask(ref_to_scan) ||
4239 _g1h->obj_in_cs(*ref_to_scan), "invariant");
4240 pss->push_on_queue(ref_to_scan);
4241 continue;
4242 }
4243 pss->start_term_time();
4244 if (terminator()->offer_termination()) break;
4245 pss->end_term_time();
4246 }
4247 pss->end_term_time();
4248 pss->retire_alloc_buffers();
4249 }
4250 };
4252 class G1ParTask : public AbstractGangTask {
4253 protected:
4254 G1CollectedHeap* _g1h;
4255 RefToScanQueueSet *_queues;
4256 ParallelTaskTerminator _terminator;
4258 Mutex _stats_lock;
4259 Mutex* stats_lock() { return &_stats_lock; }
4261 size_t getNCards() {
4262 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4263 / G1BlockOffsetSharedArray::N_bytes;
4264 }
4266 public:
4267 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4268 : AbstractGangTask("G1 collection"),
4269 _g1h(g1h),
4270 _queues(task_queues),
4271 _terminator(workers, _queues),
4272 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4273 {}
4275 RefToScanQueueSet* queues() { return _queues; }
4277 RefToScanQueue *work_queue(int i) {
4278 return queues()->queue(i);
4279 }
4281 void work(int i) {
4282 ResourceMark rm;
4283 HandleMark hm;
4285 G1ParScanThreadState pss(_g1h, i);
4286 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4287 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4288 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4290 pss.set_evac_closure(&scan_evac_cl);
4291 pss.set_evac_failure_closure(&evac_failure_cl);
4292 pss.set_partial_scan_closure(&partial_scan_cl);
4294 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4295 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4296 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4298 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4299 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4300 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4302 OopsInHeapRegionClosure *scan_root_cl;
4303 OopsInHeapRegionClosure *scan_perm_cl;
4304 OopsInHeapRegionClosure *scan_so_cl;
4306 if (_g1h->g1_policy()->should_initiate_conc_mark()) {
4307 scan_root_cl = &scan_mark_root_cl;
4308 scan_perm_cl = &scan_mark_perm_cl;
4309 scan_so_cl = &scan_mark_heap_rs_cl;
4310 } else {
4311 scan_root_cl = &only_scan_root_cl;
4312 scan_perm_cl = &only_scan_perm_cl;
4313 scan_so_cl = &only_scan_heap_rs_cl;
4314 }
4316 pss.start_strong_roots();
4317 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4318 SharedHeap::SO_AllClasses,
4319 scan_root_cl,
4320 &only_scan_heap_rs_cl,
4321 scan_so_cl,
4322 scan_perm_cl,
4323 i);
4324 pss.end_strong_roots();
4325 {
4326 double start = os::elapsedTime();
4327 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4328 evac.do_void();
4329 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4330 double term_ms = pss.term_time()*1000.0;
4331 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4332 _g1h->g1_policy()->record_termination_time(i, term_ms);
4333 }
4334 if (G1UseSurvivorSpace) {
4335 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4336 }
4337 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4339 // Clean up any par-expanded rem sets.
4340 HeapRegionRemSet::par_cleanup();
4342 MutexLocker x(stats_lock());
4343 if (ParallelGCVerbose) {
4344 gclog_or_tty->print("Thread %d complete:\n", i);
4345 #if G1_DETAILED_STATS
4346 gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n",
4347 pss.pushes(),
4348 pss.pops(),
4349 pss.overflow_pushes(),
4350 pss.steals(),
4351 pss.steal_attempts());
4352 #endif
4353 double elapsed = pss.elapsed();
4354 double strong_roots = pss.strong_roots_time();
4355 double term = pss.term_time();
4356 gclog_or_tty->print(" Elapsed: %7.2f ms.\n"
4357 " Strong roots: %7.2f ms (%6.2f%%)\n"
4358 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n",
4359 elapsed * 1000.0,
4360 strong_roots * 1000.0, (strong_roots*100.0/elapsed),
4361 term * 1000.0, (term*100.0/elapsed),
4362 pss.term_attempts());
4363 size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste();
4364 gclog_or_tty->print(" Waste: %8dK\n"
4365 " Alloc Buffer: %8dK\n"
4366 " Undo: %8dK\n",
4367 (total_waste * HeapWordSize) / K,
4368 (pss.alloc_buffer_waste() * HeapWordSize) / K,
4369 (pss.undo_waste() * HeapWordSize) / K);
4370 }
4372 assert(pss.refs_to_scan() == 0, "Task queue should be empty");
4373 assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
4374 }
4375 };
4377 // *** Common G1 Evacuation Stuff
4379 class G1CountClosure: public OopsInHeapRegionClosure {
4380 public:
4381 int n;
4382 G1CountClosure() : n(0) {}
4383 void do_oop(narrowOop* p) {
4384 guarantee(false, "NYI");
4385 }
4386 void do_oop(oop* p) {
4387 oop obj = *p;
4388 assert(obj != NULL && G1CollectedHeap::heap()->obj_in_cs(obj),
4389 "Rem set closure called on non-rem-set pointer.");
4390 n++;
4391 }
4392 };
4394 static G1CountClosure count_closure;
4396 void
4397 G1CollectedHeap::
4398 g1_process_strong_roots(bool collecting_perm_gen,
4399 SharedHeap::ScanningOption so,
4400 OopClosure* scan_non_heap_roots,
4401 OopsInHeapRegionClosure* scan_rs,
4402 OopsInHeapRegionClosure* scan_so,
4403 OopsInGenClosure* scan_perm,
4404 int worker_i) {
4405 // First scan the strong roots, including the perm gen.
4406 double ext_roots_start = os::elapsedTime();
4407 double closure_app_time_sec = 0.0;
4409 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4410 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4411 buf_scan_perm.set_generation(perm_gen());
4413 process_strong_roots(collecting_perm_gen, so,
4414 &buf_scan_non_heap_roots,
4415 &buf_scan_perm);
4416 // Finish up any enqueued closure apps.
4417 buf_scan_non_heap_roots.done();
4418 buf_scan_perm.done();
4419 double ext_roots_end = os::elapsedTime();
4420 g1_policy()->reset_obj_copy_time(worker_i);
4421 double obj_copy_time_sec =
4422 buf_scan_non_heap_roots.closure_app_seconds() +
4423 buf_scan_perm.closure_app_seconds();
4424 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4425 double ext_root_time_ms =
4426 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4427 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4429 // Scan strong roots in mark stack.
4430 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4431 concurrent_mark()->oops_do(scan_non_heap_roots);
4432 }
4433 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4434 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4436 // XXX What should this be doing in the parallel case?
4437 g1_policy()->record_collection_pause_end_CH_strong_roots();
4438 if (G1VerifyRemSet) {
4439 // :::: FIXME ::::
4440 // The stupid remembered set doesn't know how to filter out dead
4441 // objects, which the smart one does, and so when it is created
4442 // and then compared the number of entries in each differs and
4443 // the verification code fails.
4444 guarantee(false, "verification code is broken, see note");
4446 // Let's make sure that the current rem set agrees with the stupidest
4447 // one possible!
4448 bool refs_enabled = ref_processor()->discovery_enabled();
4449 if (refs_enabled) ref_processor()->disable_discovery();
4450 StupidG1RemSet stupid(this);
4451 count_closure.n = 0;
4452 stupid.oops_into_collection_set_do(&count_closure, worker_i);
4453 int stupid_n = count_closure.n;
4454 count_closure.n = 0;
4455 g1_rem_set()->oops_into_collection_set_do(&count_closure, worker_i);
4456 guarantee(count_closure.n == stupid_n, "Old and new rem sets differ.");
4457 gclog_or_tty->print_cr("\nFound %d pointers in heap RS.", count_closure.n);
4458 if (refs_enabled) ref_processor()->enable_discovery();
4459 }
4460 if (scan_so != NULL) {
4461 scan_scan_only_set(scan_so, worker_i);
4462 }
4463 // Now scan the complement of the collection set.
4464 if (scan_rs != NULL) {
4465 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4466 }
4467 // Finish with the ref_processor roots.
4468 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4469 ref_processor()->oops_do(scan_non_heap_roots);
4470 }
4471 g1_policy()->record_collection_pause_end_G1_strong_roots();
4472 _process_strong_tasks->all_tasks_completed();
4473 }
4475 void
4476 G1CollectedHeap::scan_scan_only_region(HeapRegion* r,
4477 OopsInHeapRegionClosure* oc,
4478 int worker_i) {
4479 HeapWord* startAddr = r->bottom();
4480 HeapWord* endAddr = r->used_region().end();
4482 oc->set_region(r);
4484 HeapWord* p = r->bottom();
4485 HeapWord* t = r->top();
4486 guarantee( p == r->next_top_at_mark_start(), "invariant" );
4487 while (p < t) {
4488 oop obj = oop(p);
4489 p += obj->oop_iterate(oc);
4490 }
4491 }
4493 void
4494 G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc,
4495 int worker_i) {
4496 double start = os::elapsedTime();
4498 BufferingOopsInHeapRegionClosure boc(oc);
4500 FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc);
4501 FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark());
4503 OopsInHeapRegionClosure *foc;
4504 if (g1_policy()->should_initiate_conc_mark())
4505 foc = &scan_and_mark;
4506 else
4507 foc = &scan_only;
4509 HeapRegion* hr;
4510 int n = 0;
4511 while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) {
4512 scan_scan_only_region(hr, foc, worker_i);
4513 ++n;
4514 }
4515 boc.done();
4517 double closure_app_s = boc.closure_app_seconds();
4518 g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0);
4519 double ms = (os::elapsedTime() - start - closure_app_s)*1000.0;
4520 g1_policy()->record_scan_only_time(worker_i, ms, n);
4521 }
4523 void
4524 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4525 OopClosure* non_root_closure) {
4526 SharedHeap::process_weak_roots(root_closure, non_root_closure);
4527 }
4530 class SaveMarksClosure: public HeapRegionClosure {
4531 public:
4532 bool doHeapRegion(HeapRegion* r) {
4533 r->save_marks();
4534 return false;
4535 }
4536 };
4538 void G1CollectedHeap::save_marks() {
4539 if (ParallelGCThreads == 0) {
4540 SaveMarksClosure sm;
4541 heap_region_iterate(&sm);
4542 }
4543 // We do this even in the parallel case
4544 perm_gen()->save_marks();
4545 }
4547 void G1CollectedHeap::evacuate_collection_set() {
4548 set_evacuation_failed(false);
4550 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4551 concurrent_g1_refine()->set_use_cache(false);
4552 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4553 set_par_threads(n_workers);
4554 G1ParTask g1_par_task(this, n_workers, _task_queues);
4556 init_for_evac_failure(NULL);
4558 change_strong_roots_parity(); // In preparation for parallel strong roots.
4559 rem_set()->prepare_for_younger_refs_iterate(true);
4561 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4562 double start_par = os::elapsedTime();
4563 if (ParallelGCThreads > 0) {
4564 // The individual threads will set their evac-failure closures.
4565 workers()->run_task(&g1_par_task);
4566 } else {
4567 g1_par_task.work(0);
4568 }
4570 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4571 g1_policy()->record_par_time(par_time);
4572 set_par_threads(0);
4573 // Is this the right thing to do here? We don't save marks
4574 // on individual heap regions when we allocate from
4575 // them in parallel, so this seems like the correct place for this.
4576 retire_all_alloc_regions();
4577 {
4578 G1IsAliveClosure is_alive(this);
4579 G1KeepAliveClosure keep_alive(this);
4580 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4581 }
4582 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4584 concurrent_g1_refine()->set_use_cache(true);
4586 finalize_for_evac_failure();
4588 // Must do this before removing self-forwarding pointers, which clears
4589 // the per-region evac-failure flags.
4590 concurrent_mark()->complete_marking_in_collection_set();
4592 if (evacuation_failed()) {
4593 remove_self_forwarding_pointers();
4594 if (PrintGCDetails) {
4595 gclog_or_tty->print(" (evacuation failed)");
4596 } else if (PrintGC) {
4597 gclog_or_tty->print("--");
4598 }
4599 }
4601 if (G1DeferredRSUpdate) {
4602 RedirtyLoggedCardTableEntryFastClosure redirty;
4603 dirty_card_queue_set().set_closure(&redirty);
4604 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4605 JavaThread::dirty_card_queue_set().merge_bufferlists(&dirty_card_queue_set());
4606 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4607 }
4609 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4610 }
4612 void G1CollectedHeap::free_region(HeapRegion* hr) {
4613 size_t pre_used = 0;
4614 size_t cleared_h_regions = 0;
4615 size_t freed_regions = 0;
4616 UncleanRegionList local_list;
4618 HeapWord* start = hr->bottom();
4619 HeapWord* end = hr->prev_top_at_mark_start();
4620 size_t used_bytes = hr->used();
4621 size_t live_bytes = hr->max_live_bytes();
4622 if (used_bytes > 0) {
4623 guarantee( live_bytes <= used_bytes, "invariant" );
4624 } else {
4625 guarantee( live_bytes == 0, "invariant" );
4626 }
4628 size_t garbage_bytes = used_bytes - live_bytes;
4629 if (garbage_bytes > 0)
4630 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4632 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4633 &local_list);
4634 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4635 &local_list);
4636 }
4638 void
4639 G1CollectedHeap::free_region_work(HeapRegion* hr,
4640 size_t& pre_used,
4641 size_t& cleared_h_regions,
4642 size_t& freed_regions,
4643 UncleanRegionList* list,
4644 bool par) {
4645 pre_used += hr->used();
4646 if (hr->isHumongous()) {
4647 assert(hr->startsHumongous(),
4648 "Only the start of a humongous region should be freed.");
4649 int ind = _hrs->find(hr);
4650 assert(ind != -1, "Should have an index.");
4651 // Clear the start region.
4652 hr->hr_clear(par, true /*clear_space*/);
4653 list->insert_before_head(hr);
4654 cleared_h_regions++;
4655 freed_regions++;
4656 // Clear any continued regions.
4657 ind++;
4658 while ((size_t)ind < n_regions()) {
4659 HeapRegion* hrc = _hrs->at(ind);
4660 if (!hrc->continuesHumongous()) break;
4661 // Otherwise, does continue the H region.
4662 assert(hrc->humongous_start_region() == hr, "Huh?");
4663 hrc->hr_clear(par, true /*clear_space*/);
4664 cleared_h_regions++;
4665 freed_regions++;
4666 list->insert_before_head(hrc);
4667 ind++;
4668 }
4669 } else {
4670 hr->hr_clear(par, true /*clear_space*/);
4671 list->insert_before_head(hr);
4672 freed_regions++;
4673 // If we're using clear2, this should not be enabled.
4674 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4675 }
4676 }
4678 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4679 size_t cleared_h_regions,
4680 size_t freed_regions,
4681 UncleanRegionList* list) {
4682 if (list != NULL && list->sz() > 0) {
4683 prepend_region_list_on_unclean_list(list);
4684 }
4685 // Acquire a lock, if we're parallel, to update possibly-shared
4686 // variables.
4687 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4688 {
4689 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4690 _summary_bytes_used -= pre_used;
4691 _num_humongous_regions -= (int) cleared_h_regions;
4692 _free_regions += freed_regions;
4693 }
4694 }
4697 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4698 while (list != NULL) {
4699 guarantee( list->is_young(), "invariant" );
4701 HeapWord* bottom = list->bottom();
4702 HeapWord* end = list->end();
4703 MemRegion mr(bottom, end);
4704 ct_bs->dirty(mr);
4706 list = list->get_next_young_region();
4707 }
4708 }
4710 void G1CollectedHeap::cleanUpCardTable() {
4711 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4712 double start = os::elapsedTime();
4714 ct_bs->clear(_g1_committed);
4716 // now, redirty the cards of the scan-only and survivor regions
4717 // (it seemed faster to do it this way, instead of iterating over
4718 // all regions and then clearing / dirtying as approprite)
4719 dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region());
4720 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4722 double elapsed = os::elapsedTime() - start;
4723 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4724 }
4727 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4728 if (g1_policy()->should_do_collection_pause(word_size)) {
4729 do_collection_pause();
4730 }
4731 }
4733 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4734 double young_time_ms = 0.0;
4735 double non_young_time_ms = 0.0;
4737 G1CollectorPolicy* policy = g1_policy();
4739 double start_sec = os::elapsedTime();
4740 bool non_young = true;
4742 HeapRegion* cur = cs_head;
4743 int age_bound = -1;
4744 size_t rs_lengths = 0;
4746 while (cur != NULL) {
4747 if (non_young) {
4748 if (cur->is_young()) {
4749 double end_sec = os::elapsedTime();
4750 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4751 non_young_time_ms += elapsed_ms;
4753 start_sec = os::elapsedTime();
4754 non_young = false;
4755 }
4756 } else {
4757 if (!cur->is_on_free_list()) {
4758 double end_sec = os::elapsedTime();
4759 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4760 young_time_ms += elapsed_ms;
4762 start_sec = os::elapsedTime();
4763 non_young = true;
4764 }
4765 }
4767 rs_lengths += cur->rem_set()->occupied();
4769 HeapRegion* next = cur->next_in_collection_set();
4770 assert(cur->in_collection_set(), "bad CS");
4771 cur->set_next_in_collection_set(NULL);
4772 cur->set_in_collection_set(false);
4774 if (cur->is_young()) {
4775 int index = cur->young_index_in_cset();
4776 guarantee( index != -1, "invariant" );
4777 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4778 size_t words_survived = _surviving_young_words[index];
4779 cur->record_surv_words_in_group(words_survived);
4780 } else {
4781 int index = cur->young_index_in_cset();
4782 guarantee( index == -1, "invariant" );
4783 }
4785 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4786 (!cur->is_young() && cur->young_index_in_cset() == -1),
4787 "invariant" );
4789 if (!cur->evacuation_failed()) {
4790 // And the region is empty.
4791 assert(!cur->is_empty(),
4792 "Should not have empty regions in a CS.");
4793 free_region(cur);
4794 } else {
4795 guarantee( !cur->is_scan_only(), "should not be scan only" );
4796 cur->uninstall_surv_rate_group();
4797 if (cur->is_young())
4798 cur->set_young_index_in_cset(-1);
4799 cur->set_not_young();
4800 cur->set_evacuation_failed(false);
4801 }
4802 cur = next;
4803 }
4805 policy->record_max_rs_lengths(rs_lengths);
4806 policy->cset_regions_freed();
4808 double end_sec = os::elapsedTime();
4809 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4810 if (non_young)
4811 non_young_time_ms += elapsed_ms;
4812 else
4813 young_time_ms += elapsed_ms;
4815 policy->record_young_free_cset_time_ms(young_time_ms);
4816 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4817 }
4819 HeapRegion*
4820 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4821 assert(ZF_mon->owned_by_self(), "Precondition");
4822 HeapRegion* res = pop_unclean_region_list_locked();
4823 if (res != NULL) {
4824 assert(!res->continuesHumongous() &&
4825 res->zero_fill_state() != HeapRegion::Allocated,
4826 "Only free regions on unclean list.");
4827 if (zero_filled) {
4828 res->ensure_zero_filled_locked();
4829 res->set_zero_fill_allocated();
4830 }
4831 }
4832 return res;
4833 }
4835 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4836 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4837 return alloc_region_from_unclean_list_locked(zero_filled);
4838 }
4840 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4841 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4842 put_region_on_unclean_list_locked(r);
4843 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4844 }
4846 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4847 MutexLockerEx x(Cleanup_mon);
4848 set_unclean_regions_coming_locked(b);
4849 }
4851 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4852 assert(Cleanup_mon->owned_by_self(), "Precondition");
4853 _unclean_regions_coming = b;
4854 // Wake up mutator threads that might be waiting for completeCleanup to
4855 // finish.
4856 if (!b) Cleanup_mon->notify_all();
4857 }
4859 void G1CollectedHeap::wait_for_cleanup_complete() {
4860 MutexLockerEx x(Cleanup_mon);
4861 wait_for_cleanup_complete_locked();
4862 }
4864 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4865 assert(Cleanup_mon->owned_by_self(), "precondition");
4866 while (_unclean_regions_coming) {
4867 Cleanup_mon->wait();
4868 }
4869 }
4871 void
4872 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4873 assert(ZF_mon->owned_by_self(), "precondition.");
4874 _unclean_region_list.insert_before_head(r);
4875 }
4877 void
4878 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4879 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4880 prepend_region_list_on_unclean_list_locked(list);
4881 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4882 }
4884 void
4885 G1CollectedHeap::
4886 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4887 assert(ZF_mon->owned_by_self(), "precondition.");
4888 _unclean_region_list.prepend_list(list);
4889 }
4891 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4892 assert(ZF_mon->owned_by_self(), "precondition.");
4893 HeapRegion* res = _unclean_region_list.pop();
4894 if (res != NULL) {
4895 // Inform ZF thread that there's a new unclean head.
4896 if (_unclean_region_list.hd() != NULL && should_zf())
4897 ZF_mon->notify_all();
4898 }
4899 return res;
4900 }
4902 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4903 assert(ZF_mon->owned_by_self(), "precondition.");
4904 return _unclean_region_list.hd();
4905 }
4908 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4909 assert(ZF_mon->owned_by_self(), "Precondition");
4910 HeapRegion* r = peek_unclean_region_list_locked();
4911 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4912 // Result of below must be equal to "r", since we hold the lock.
4913 (void)pop_unclean_region_list_locked();
4914 put_free_region_on_list_locked(r);
4915 return true;
4916 } else {
4917 return false;
4918 }
4919 }
4921 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4922 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4923 return move_cleaned_region_to_free_list_locked();
4924 }
4927 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
4928 assert(ZF_mon->owned_by_self(), "precondition.");
4929 assert(_free_region_list_size == free_region_list_length(), "Inv");
4930 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
4931 "Regions on free list must be zero filled");
4932 assert(!r->isHumongous(), "Must not be humongous.");
4933 assert(r->is_empty(), "Better be empty");
4934 assert(!r->is_on_free_list(),
4935 "Better not already be on free list");
4936 assert(!r->is_on_unclean_list(),
4937 "Better not already be on unclean list");
4938 r->set_on_free_list(true);
4939 r->set_next_on_free_list(_free_region_list);
4940 _free_region_list = r;
4941 _free_region_list_size++;
4942 assert(_free_region_list_size == free_region_list_length(), "Inv");
4943 }
4945 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
4946 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4947 put_free_region_on_list_locked(r);
4948 }
4950 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
4951 assert(ZF_mon->owned_by_self(), "precondition.");
4952 assert(_free_region_list_size == free_region_list_length(), "Inv");
4953 HeapRegion* res = _free_region_list;
4954 if (res != NULL) {
4955 _free_region_list = res->next_from_free_list();
4956 _free_region_list_size--;
4957 res->set_on_free_list(false);
4958 res->set_next_on_free_list(NULL);
4959 assert(_free_region_list_size == free_region_list_length(), "Inv");
4960 }
4961 return res;
4962 }
4965 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
4966 // By self, or on behalf of self.
4967 assert(Heap_lock->is_locked(), "Precondition");
4968 HeapRegion* res = NULL;
4969 bool first = true;
4970 while (res == NULL) {
4971 if (zero_filled || !first) {
4972 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4973 res = pop_free_region_list_locked();
4974 if (res != NULL) {
4975 assert(!res->zero_fill_is_allocated(),
4976 "No allocated regions on free list.");
4977 res->set_zero_fill_allocated();
4978 } else if (!first) {
4979 break; // We tried both, time to return NULL.
4980 }
4981 }
4983 if (res == NULL) {
4984 res = alloc_region_from_unclean_list(zero_filled);
4985 }
4986 assert(res == NULL ||
4987 !zero_filled ||
4988 res->zero_fill_is_allocated(),
4989 "We must have allocated the region we're returning");
4990 first = false;
4991 }
4992 return res;
4993 }
4995 void G1CollectedHeap::remove_allocated_regions_from_lists() {
4996 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4997 {
4998 HeapRegion* prev = NULL;
4999 HeapRegion* cur = _unclean_region_list.hd();
5000 while (cur != NULL) {
5001 HeapRegion* next = cur->next_from_unclean_list();
5002 if (cur->zero_fill_is_allocated()) {
5003 // Remove from the list.
5004 if (prev == NULL) {
5005 (void)_unclean_region_list.pop();
5006 } else {
5007 _unclean_region_list.delete_after(prev);
5008 }
5009 cur->set_on_unclean_list(false);
5010 cur->set_next_on_unclean_list(NULL);
5011 } else {
5012 prev = cur;
5013 }
5014 cur = next;
5015 }
5016 assert(_unclean_region_list.sz() == unclean_region_list_length(),
5017 "Inv");
5018 }
5020 {
5021 HeapRegion* prev = NULL;
5022 HeapRegion* cur = _free_region_list;
5023 while (cur != NULL) {
5024 HeapRegion* next = cur->next_from_free_list();
5025 if (cur->zero_fill_is_allocated()) {
5026 // Remove from the list.
5027 if (prev == NULL) {
5028 _free_region_list = cur->next_from_free_list();
5029 } else {
5030 prev->set_next_on_free_list(cur->next_from_free_list());
5031 }
5032 cur->set_on_free_list(false);
5033 cur->set_next_on_free_list(NULL);
5034 _free_region_list_size--;
5035 } else {
5036 prev = cur;
5037 }
5038 cur = next;
5039 }
5040 assert(_free_region_list_size == free_region_list_length(), "Inv");
5041 }
5042 }
5044 bool G1CollectedHeap::verify_region_lists() {
5045 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5046 return verify_region_lists_locked();
5047 }
5049 bool G1CollectedHeap::verify_region_lists_locked() {
5050 HeapRegion* unclean = _unclean_region_list.hd();
5051 while (unclean != NULL) {
5052 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
5053 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
5054 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
5055 "Everything else is possible.");
5056 unclean = unclean->next_from_unclean_list();
5057 }
5058 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
5060 HeapRegion* free_r = _free_region_list;
5061 while (free_r != NULL) {
5062 assert(free_r->is_on_free_list(), "Well, it is!");
5063 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
5064 switch (free_r->zero_fill_state()) {
5065 case HeapRegion::NotZeroFilled:
5066 case HeapRegion::ZeroFilling:
5067 guarantee(false, "Should not be on free list.");
5068 break;
5069 default:
5070 // Everything else is possible.
5071 break;
5072 }
5073 free_r = free_r->next_from_free_list();
5074 }
5075 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
5076 // If we didn't do an assertion...
5077 return true;
5078 }
5080 size_t G1CollectedHeap::free_region_list_length() {
5081 assert(ZF_mon->owned_by_self(), "precondition.");
5082 size_t len = 0;
5083 HeapRegion* cur = _free_region_list;
5084 while (cur != NULL) {
5085 len++;
5086 cur = cur->next_from_free_list();
5087 }
5088 return len;
5089 }
5091 size_t G1CollectedHeap::unclean_region_list_length() {
5092 assert(ZF_mon->owned_by_self(), "precondition.");
5093 return _unclean_region_list.length();
5094 }
5096 size_t G1CollectedHeap::n_regions() {
5097 return _hrs->length();
5098 }
5100 size_t G1CollectedHeap::max_regions() {
5101 return
5102 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
5103 HeapRegion::GrainBytes;
5104 }
5106 size_t G1CollectedHeap::free_regions() {
5107 /* Possibly-expensive assert.
5108 assert(_free_regions == count_free_regions(),
5109 "_free_regions is off.");
5110 */
5111 return _free_regions;
5112 }
5114 bool G1CollectedHeap::should_zf() {
5115 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
5116 }
5118 class RegionCounter: public HeapRegionClosure {
5119 size_t _n;
5120 public:
5121 RegionCounter() : _n(0) {}
5122 bool doHeapRegion(HeapRegion* r) {
5123 if (r->is_empty()) {
5124 assert(!r->isHumongous(), "H regions should not be empty.");
5125 _n++;
5126 }
5127 return false;
5128 }
5129 int res() { return (int) _n; }
5130 };
5132 size_t G1CollectedHeap::count_free_regions() {
5133 RegionCounter rc;
5134 heap_region_iterate(&rc);
5135 size_t n = rc.res();
5136 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
5137 n--;
5138 return n;
5139 }
5141 size_t G1CollectedHeap::count_free_regions_list() {
5142 size_t n = 0;
5143 size_t o = 0;
5144 ZF_mon->lock_without_safepoint_check();
5145 HeapRegion* cur = _free_region_list;
5146 while (cur != NULL) {
5147 cur = cur->next_from_free_list();
5148 n++;
5149 }
5150 size_t m = unclean_region_list_length();
5151 ZF_mon->unlock();
5152 return n + m;
5153 }
5155 bool G1CollectedHeap::should_set_young_locked() {
5156 assert(heap_lock_held_for_gc(),
5157 "the heap lock should already be held by or for this thread");
5158 return (g1_policy()->in_young_gc_mode() &&
5159 g1_policy()->should_add_next_region_to_young_list());
5160 }
5162 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5163 assert(heap_lock_held_for_gc(),
5164 "the heap lock should already be held by or for this thread");
5165 _young_list->push_region(hr);
5166 g1_policy()->set_region_short_lived(hr);
5167 }
5169 class NoYoungRegionsClosure: public HeapRegionClosure {
5170 private:
5171 bool _success;
5172 public:
5173 NoYoungRegionsClosure() : _success(true) { }
5174 bool doHeapRegion(HeapRegion* r) {
5175 if (r->is_young()) {
5176 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5177 r->bottom(), r->end());
5178 _success = false;
5179 }
5180 return false;
5181 }
5182 bool success() { return _success; }
5183 };
5185 bool G1CollectedHeap::check_young_list_empty(bool ignore_scan_only_list,
5186 bool check_sample) {
5187 bool ret = true;
5189 ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample);
5190 if (!ignore_scan_only_list) {
5191 NoYoungRegionsClosure closure;
5192 heap_region_iterate(&closure);
5193 ret = ret && closure.success();
5194 }
5196 return ret;
5197 }
5199 void G1CollectedHeap::empty_young_list() {
5200 assert(heap_lock_held_for_gc(),
5201 "the heap lock should already be held by or for this thread");
5202 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
5204 _young_list->empty_list();
5205 }
5207 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
5208 bool no_allocs = true;
5209 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
5210 HeapRegion* r = _gc_alloc_regions[ap];
5211 no_allocs = r == NULL || r->saved_mark_at_top();
5212 }
5213 return no_allocs;
5214 }
5216 void G1CollectedHeap::retire_all_alloc_regions() {
5217 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
5218 HeapRegion* r = _gc_alloc_regions[ap];
5219 if (r != NULL) {
5220 // Check for aliases.
5221 bool has_processed_alias = false;
5222 for (int i = 0; i < ap; ++i) {
5223 if (_gc_alloc_regions[i] == r) {
5224 has_processed_alias = true;
5225 break;
5226 }
5227 }
5228 if (!has_processed_alias) {
5229 retire_alloc_region(r, false /* par */);
5230 }
5231 }
5232 }
5233 }
5236 // Done at the start of full GC.
5237 void G1CollectedHeap::tear_down_region_lists() {
5238 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5239 while (pop_unclean_region_list_locked() != NULL) ;
5240 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
5241 "Postconditions of loop.")
5242 while (pop_free_region_list_locked() != NULL) ;
5243 assert(_free_region_list == NULL, "Postcondition of loop.");
5244 if (_free_region_list_size != 0) {
5245 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
5246 print();
5247 }
5248 assert(_free_region_list_size == 0, "Postconditions of loop.");
5249 }
5252 class RegionResetter: public HeapRegionClosure {
5253 G1CollectedHeap* _g1;
5254 int _n;
5255 public:
5256 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5257 bool doHeapRegion(HeapRegion* r) {
5258 if (r->continuesHumongous()) return false;
5259 if (r->top() > r->bottom()) {
5260 if (r->top() < r->end()) {
5261 Copy::fill_to_words(r->top(),
5262 pointer_delta(r->end(), r->top()));
5263 }
5264 r->set_zero_fill_allocated();
5265 } else {
5266 assert(r->is_empty(), "tautology");
5267 _n++;
5268 switch (r->zero_fill_state()) {
5269 case HeapRegion::NotZeroFilled:
5270 case HeapRegion::ZeroFilling:
5271 _g1->put_region_on_unclean_list_locked(r);
5272 break;
5273 case HeapRegion::Allocated:
5274 r->set_zero_fill_complete();
5275 // no break; go on to put on free list.
5276 case HeapRegion::ZeroFilled:
5277 _g1->put_free_region_on_list_locked(r);
5278 break;
5279 }
5280 }
5281 return false;
5282 }
5284 int getFreeRegionCount() {return _n;}
5285 };
5287 // Done at the end of full GC.
5288 void G1CollectedHeap::rebuild_region_lists() {
5289 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5290 // This needs to go at the end of the full GC.
5291 RegionResetter rs;
5292 heap_region_iterate(&rs);
5293 _free_regions = rs.getFreeRegionCount();
5294 // Tell the ZF thread it may have work to do.
5295 if (should_zf()) ZF_mon->notify_all();
5296 }
5298 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
5299 G1CollectedHeap* _g1;
5300 int _n;
5301 public:
5302 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5303 bool doHeapRegion(HeapRegion* r) {
5304 if (r->continuesHumongous()) return false;
5305 if (r->top() > r->bottom()) {
5306 // There are assertions in "set_zero_fill_needed()" below that
5307 // require top() == bottom(), so this is technically illegal.
5308 // We'll skirt the law here, by making that true temporarily.
5309 DEBUG_ONLY(HeapWord* save_top = r->top();
5310 r->set_top(r->bottom()));
5311 r->set_zero_fill_needed();
5312 DEBUG_ONLY(r->set_top(save_top));
5313 }
5314 return false;
5315 }
5316 };
5318 // Done at the start of full GC.
5319 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
5320 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5321 // This needs to go at the end of the full GC.
5322 UsedRegionsNeedZeroFillSetter rs;
5323 heap_region_iterate(&rs);
5324 }
5326 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5327 _refine_cte_cl->set_concurrent(concurrent);
5328 }
5330 #ifndef PRODUCT
5332 class PrintHeapRegionClosure: public HeapRegionClosure {
5333 public:
5334 bool doHeapRegion(HeapRegion *r) {
5335 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
5336 if (r != NULL) {
5337 if (r->is_on_free_list())
5338 gclog_or_tty->print("Free ");
5339 if (r->is_young())
5340 gclog_or_tty->print("Young ");
5341 if (r->isHumongous())
5342 gclog_or_tty->print("Is Humongous ");
5343 r->print();
5344 }
5345 return false;
5346 }
5347 };
5349 class SortHeapRegionClosure : public HeapRegionClosure {
5350 size_t young_regions,free_regions, unclean_regions;
5351 size_t hum_regions, count;
5352 size_t unaccounted, cur_unclean, cur_alloc;
5353 size_t total_free;
5354 HeapRegion* cur;
5355 public:
5356 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5357 free_regions(0), unclean_regions(0),
5358 hum_regions(0),
5359 count(0), unaccounted(0),
5360 cur_alloc(0), total_free(0)
5361 {}
5362 bool doHeapRegion(HeapRegion *r) {
5363 count++;
5364 if (r->is_on_free_list()) free_regions++;
5365 else if (r->is_on_unclean_list()) unclean_regions++;
5366 else if (r->isHumongous()) hum_regions++;
5367 else if (r->is_young()) young_regions++;
5368 else if (r == cur) cur_alloc++;
5369 else unaccounted++;
5370 return false;
5371 }
5372 void print() {
5373 total_free = free_regions + unclean_regions;
5374 gclog_or_tty->print("%d regions\n", count);
5375 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5376 total_free, free_regions, unclean_regions);
5377 gclog_or_tty->print("%d humongous %d young\n",
5378 hum_regions, young_regions);
5379 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5380 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5381 }
5382 };
5384 void G1CollectedHeap::print_region_counts() {
5385 SortHeapRegionClosure sc(_cur_alloc_region);
5386 PrintHeapRegionClosure cl;
5387 heap_region_iterate(&cl);
5388 heap_region_iterate(&sc);
5389 sc.print();
5390 print_region_accounting_info();
5391 };
5393 bool G1CollectedHeap::regions_accounted_for() {
5394 // TODO: regions accounting for young/survivor/tenured
5395 return true;
5396 }
5398 bool G1CollectedHeap::print_region_accounting_info() {
5399 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5400 free_regions(),
5401 count_free_regions(), count_free_regions_list(),
5402 _free_region_list_size, _unclean_region_list.sz());
5403 gclog_or_tty->print_cr("cur_alloc: %d.",
5404 (_cur_alloc_region == NULL ? 0 : 1));
5405 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5407 // TODO: check regions accounting for young/survivor/tenured
5408 return true;
5409 }
5411 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5412 HeapRegion* hr = heap_region_containing(p);
5413 if (hr == NULL) {
5414 return is_in_permanent(p);
5415 } else {
5416 return hr->is_in(p);
5417 }
5418 }
5419 #endif // PRODUCT
5421 void G1CollectedHeap::g1_unimplemented() {
5422 // Unimplemented();
5423 }
5426 // Local Variables: ***
5427 // c-indentation-style: gnu ***
5428 // End: ***