Thu, 19 Mar 2009 09:13:24 -0700
Merge
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 // Finds the first HeapRegion.
46 // No longer used, but might be handy someday.
48 class FindFirstRegionClosure: public HeapRegionClosure {
49 HeapRegion* _a_region;
50 public:
51 FindFirstRegionClosure() : _a_region(NULL) {}
52 bool doHeapRegion(HeapRegion* r) {
53 _a_region = r;
54 return true;
55 }
56 HeapRegion* result() { return _a_region; }
57 };
60 class RefineCardTableEntryClosure: public CardTableEntryClosure {
61 SuspendibleThreadSet* _sts;
62 G1RemSet* _g1rs;
63 ConcurrentG1Refine* _cg1r;
64 bool _concurrent;
65 public:
66 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
67 G1RemSet* g1rs,
68 ConcurrentG1Refine* cg1r) :
69 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
70 {}
71 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
72 _g1rs->concurrentRefineOneCard(card_ptr, worker_i);
73 if (_concurrent && _sts->should_yield()) {
74 // Caller will actually yield.
75 return false;
76 }
77 // Otherwise, we finished successfully; return true.
78 return true;
79 }
80 void set_concurrent(bool b) { _concurrent = b; }
81 };
84 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
85 int _calls;
86 G1CollectedHeap* _g1h;
87 CardTableModRefBS* _ctbs;
88 int _histo[256];
89 public:
90 ClearLoggedCardTableEntryClosure() :
91 _calls(0)
92 {
93 _g1h = G1CollectedHeap::heap();
94 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
95 for (int i = 0; i < 256; i++) _histo[i] = 0;
96 }
97 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
98 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
99 _calls++;
100 unsigned char* ujb = (unsigned char*)card_ptr;
101 int ind = (int)(*ujb);
102 _histo[ind]++;
103 *card_ptr = -1;
104 }
105 return true;
106 }
107 int calls() { return _calls; }
108 void print_histo() {
109 gclog_or_tty->print_cr("Card table value histogram:");
110 for (int i = 0; i < 256; i++) {
111 if (_histo[i] != 0) {
112 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
113 }
114 }
115 }
116 };
118 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
119 int _calls;
120 G1CollectedHeap* _g1h;
121 CardTableModRefBS* _ctbs;
122 public:
123 RedirtyLoggedCardTableEntryClosure() :
124 _calls(0)
125 {
126 _g1h = G1CollectedHeap::heap();
127 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
128 }
129 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
130 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
131 _calls++;
132 *card_ptr = 0;
133 }
134 return true;
135 }
136 int calls() { return _calls; }
137 };
139 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
140 public:
141 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
142 *card_ptr = CardTableModRefBS::dirty_card_val();
143 return true;
144 }
145 };
147 YoungList::YoungList(G1CollectedHeap* g1h)
148 : _g1h(g1h), _head(NULL),
149 _scan_only_head(NULL), _scan_only_tail(NULL), _curr_scan_only(NULL),
150 _length(0), _scan_only_length(0),
151 _last_sampled_rs_lengths(0),
152 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
153 {
154 guarantee( check_list_empty(false), "just making sure..." );
155 }
157 void YoungList::push_region(HeapRegion *hr) {
158 assert(!hr->is_young(), "should not already be young");
159 assert(hr->get_next_young_region() == NULL, "cause it should!");
161 hr->set_next_young_region(_head);
162 _head = hr;
164 hr->set_young();
165 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
166 ++_length;
167 }
169 void YoungList::add_survivor_region(HeapRegion* hr) {
170 assert(hr->is_survivor(), "should be flagged as survivor region");
171 assert(hr->get_next_young_region() == NULL, "cause it should!");
173 hr->set_next_young_region(_survivor_head);
174 if (_survivor_head == NULL) {
175 _survivor_tail = hr;
176 }
177 _survivor_head = hr;
179 ++_survivor_length;
180 }
182 HeapRegion* YoungList::pop_region() {
183 while (_head != NULL) {
184 assert( length() > 0, "list should not be empty" );
185 HeapRegion* ret = _head;
186 _head = ret->get_next_young_region();
187 ret->set_next_young_region(NULL);
188 --_length;
189 assert(ret->is_young(), "region should be very young");
191 // Replace 'Survivor' region type with 'Young'. So the region will
192 // be treated as a young region and will not be 'confused' with
193 // newly created survivor regions.
194 if (ret->is_survivor()) {
195 ret->set_young();
196 }
198 if (!ret->is_scan_only()) {
199 return ret;
200 }
202 // scan-only, we'll add it to the scan-only list
203 if (_scan_only_tail == NULL) {
204 guarantee( _scan_only_head == NULL, "invariant" );
206 _scan_only_head = ret;
207 _curr_scan_only = ret;
208 } else {
209 guarantee( _scan_only_head != NULL, "invariant" );
210 _scan_only_tail->set_next_young_region(ret);
211 }
212 guarantee( ret->get_next_young_region() == NULL, "invariant" );
213 _scan_only_tail = ret;
215 // no need to be tagged as scan-only any more
216 ret->set_young();
218 ++_scan_only_length;
219 }
220 assert( length() == 0, "list should be empty" );
221 return NULL;
222 }
224 void YoungList::empty_list(HeapRegion* list) {
225 while (list != NULL) {
226 HeapRegion* next = list->get_next_young_region();
227 list->set_next_young_region(NULL);
228 list->uninstall_surv_rate_group();
229 list->set_not_young();
230 list = next;
231 }
232 }
234 void YoungList::empty_list() {
235 assert(check_list_well_formed(), "young list should be well formed");
237 empty_list(_head);
238 _head = NULL;
239 _length = 0;
241 empty_list(_scan_only_head);
242 _scan_only_head = NULL;
243 _scan_only_tail = NULL;
244 _scan_only_length = 0;
245 _curr_scan_only = NULL;
247 empty_list(_survivor_head);
248 _survivor_head = NULL;
249 _survivor_tail = NULL;
250 _survivor_length = 0;
252 _last_sampled_rs_lengths = 0;
254 assert(check_list_empty(false), "just making sure...");
255 }
257 bool YoungList::check_list_well_formed() {
258 bool ret = true;
260 size_t length = 0;
261 HeapRegion* curr = _head;
262 HeapRegion* last = NULL;
263 while (curr != NULL) {
264 if (!curr->is_young() || curr->is_scan_only()) {
265 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
266 "incorrectly tagged (%d, %d)",
267 curr->bottom(), curr->end(),
268 curr->is_young(), curr->is_scan_only());
269 ret = false;
270 }
271 ++length;
272 last = curr;
273 curr = curr->get_next_young_region();
274 }
275 ret = ret && (length == _length);
277 if (!ret) {
278 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
279 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
280 length, _length);
281 }
283 bool scan_only_ret = true;
284 length = 0;
285 curr = _scan_only_head;
286 last = NULL;
287 while (curr != NULL) {
288 if (!curr->is_young() || curr->is_scan_only()) {
289 gclog_or_tty->print_cr("### SCAN-ONLY REGION "PTR_FORMAT"-"PTR_FORMAT" "
290 "incorrectly tagged (%d, %d)",
291 curr->bottom(), curr->end(),
292 curr->is_young(), curr->is_scan_only());
293 scan_only_ret = false;
294 }
295 ++length;
296 last = curr;
297 curr = curr->get_next_young_region();
298 }
299 scan_only_ret = scan_only_ret && (length == _scan_only_length);
301 if ( (last != _scan_only_tail) ||
302 (_scan_only_head == NULL && _scan_only_tail != NULL) ||
303 (_scan_only_head != NULL && _scan_only_tail == NULL) ) {
304 gclog_or_tty->print_cr("## _scan_only_tail is set incorrectly");
305 scan_only_ret = false;
306 }
308 if (_curr_scan_only != NULL && _curr_scan_only != _scan_only_head) {
309 gclog_or_tty->print_cr("### _curr_scan_only is set incorrectly");
310 scan_only_ret = false;
311 }
313 if (!scan_only_ret) {
314 gclog_or_tty->print_cr("### SCAN-ONLY LIST seems not well formed!");
315 gclog_or_tty->print_cr("### list has %d entries, _scan_only_length is %d",
316 length, _scan_only_length);
317 }
319 return ret && scan_only_ret;
320 }
322 bool YoungList::check_list_empty(bool ignore_scan_only_list,
323 bool check_sample) {
324 bool ret = true;
326 if (_length != 0) {
327 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
328 _length);
329 ret = false;
330 }
331 if (check_sample && _last_sampled_rs_lengths != 0) {
332 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
333 ret = false;
334 }
335 if (_head != NULL) {
336 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
337 ret = false;
338 }
339 if (!ret) {
340 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
341 }
343 if (ignore_scan_only_list)
344 return ret;
346 bool scan_only_ret = true;
347 if (_scan_only_length != 0) {
348 gclog_or_tty->print_cr("### SCAN-ONLY LIST should have 0 length, not %d",
349 _scan_only_length);
350 scan_only_ret = false;
351 }
352 if (_scan_only_head != NULL) {
353 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL head");
354 scan_only_ret = false;
355 }
356 if (_scan_only_tail != NULL) {
357 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL tail");
358 scan_only_ret = false;
359 }
360 if (!scan_only_ret) {
361 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not seem empty");
362 }
364 return ret && scan_only_ret;
365 }
367 void
368 YoungList::rs_length_sampling_init() {
369 _sampled_rs_lengths = 0;
370 _curr = _head;
371 }
373 bool
374 YoungList::rs_length_sampling_more() {
375 return _curr != NULL;
376 }
378 void
379 YoungList::rs_length_sampling_next() {
380 assert( _curr != NULL, "invariant" );
381 _sampled_rs_lengths += _curr->rem_set()->occupied();
382 _curr = _curr->get_next_young_region();
383 if (_curr == NULL) {
384 _last_sampled_rs_lengths = _sampled_rs_lengths;
385 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
386 }
387 }
389 void
390 YoungList::reset_auxilary_lists() {
391 // We could have just "moved" the scan-only list to the young list.
392 // However, the scan-only list is ordered according to the region
393 // age in descending order, so, by moving one entry at a time, we
394 // ensure that it is recreated in ascending order.
396 guarantee( is_empty(), "young list should be empty" );
397 assert(check_list_well_formed(), "young list should be well formed");
399 // Add survivor regions to SurvRateGroup.
400 _g1h->g1_policy()->note_start_adding_survivor_regions();
401 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
402 for (HeapRegion* curr = _survivor_head;
403 curr != NULL;
404 curr = curr->get_next_young_region()) {
405 _g1h->g1_policy()->set_region_survivors(curr);
406 }
407 _g1h->g1_policy()->note_stop_adding_survivor_regions();
409 if (_survivor_head != NULL) {
410 _head = _survivor_head;
411 _length = _survivor_length + _scan_only_length;
412 _survivor_tail->set_next_young_region(_scan_only_head);
413 } else {
414 _head = _scan_only_head;
415 _length = _scan_only_length;
416 }
418 for (HeapRegion* curr = _scan_only_head;
419 curr != NULL;
420 curr = curr->get_next_young_region()) {
421 curr->recalculate_age_in_surv_rate_group();
422 }
423 _scan_only_head = NULL;
424 _scan_only_tail = NULL;
425 _scan_only_length = 0;
426 _curr_scan_only = NULL;
428 _survivor_head = NULL;
429 _survivor_tail = NULL;
430 _survivor_length = 0;
431 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
433 assert(check_list_well_formed(), "young list should be well formed");
434 }
436 void YoungList::print() {
437 HeapRegion* lists[] = {_head, _scan_only_head, _survivor_head};
438 const char* names[] = {"YOUNG", "SCAN-ONLY", "SURVIVOR"};
440 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
441 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
442 HeapRegion *curr = lists[list];
443 if (curr == NULL)
444 gclog_or_tty->print_cr(" empty");
445 while (curr != NULL) {
446 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
447 "age: %4d, y: %d, s-o: %d, surv: %d",
448 curr->bottom(), curr->end(),
449 curr->top(),
450 curr->prev_top_at_mark_start(),
451 curr->next_top_at_mark_start(),
452 curr->top_at_conc_mark_count(),
453 curr->age_in_surv_rate_group_cond(),
454 curr->is_young(),
455 curr->is_scan_only(),
456 curr->is_survivor());
457 curr = curr->get_next_young_region();
458 }
459 }
461 gclog_or_tty->print_cr("");
462 }
464 void G1CollectedHeap::stop_conc_gc_threads() {
465 _cg1r->cg1rThread()->stop();
466 _czft->stop();
467 _cmThread->stop();
468 }
471 void G1CollectedHeap::check_ct_logs_at_safepoint() {
472 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
473 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
475 // Count the dirty cards at the start.
476 CountNonCleanMemRegionClosure count1(this);
477 ct_bs->mod_card_iterate(&count1);
478 int orig_count = count1.n();
480 // First clear the logged cards.
481 ClearLoggedCardTableEntryClosure clear;
482 dcqs.set_closure(&clear);
483 dcqs.apply_closure_to_all_completed_buffers();
484 dcqs.iterate_closure_all_threads(false);
485 clear.print_histo();
487 // Now ensure that there's no dirty cards.
488 CountNonCleanMemRegionClosure count2(this);
489 ct_bs->mod_card_iterate(&count2);
490 if (count2.n() != 0) {
491 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
492 count2.n(), orig_count);
493 }
494 guarantee(count2.n() == 0, "Card table should be clean.");
496 RedirtyLoggedCardTableEntryClosure redirty;
497 JavaThread::dirty_card_queue_set().set_closure(&redirty);
498 dcqs.apply_closure_to_all_completed_buffers();
499 dcqs.iterate_closure_all_threads(false);
500 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
501 clear.calls(), orig_count);
502 guarantee(redirty.calls() == clear.calls(),
503 "Or else mechanism is broken.");
505 CountNonCleanMemRegionClosure count3(this);
506 ct_bs->mod_card_iterate(&count3);
507 if (count3.n() != orig_count) {
508 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
509 orig_count, count3.n());
510 guarantee(count3.n() >= orig_count, "Should have restored them all.");
511 }
513 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
514 }
516 // Private class members.
518 G1CollectedHeap* G1CollectedHeap::_g1h;
520 // Private methods.
522 // Finds a HeapRegion that can be used to allocate a given size of block.
525 HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size,
526 bool do_expand,
527 bool zero_filled) {
528 ConcurrentZFThread::note_region_alloc();
529 HeapRegion* res = alloc_free_region_from_lists(zero_filled);
530 if (res == NULL && do_expand) {
531 expand(word_size * HeapWordSize);
532 res = alloc_free_region_from_lists(zero_filled);
533 assert(res == NULL ||
534 (!res->isHumongous() &&
535 (!zero_filled ||
536 res->zero_fill_state() == HeapRegion::Allocated)),
537 "Alloc Regions must be zero filled (and non-H)");
538 }
539 if (res != NULL && res->is_empty()) _free_regions--;
540 assert(res == NULL ||
541 (!res->isHumongous() &&
542 (!zero_filled ||
543 res->zero_fill_state() == HeapRegion::Allocated)),
544 "Non-young alloc Regions must be zero filled (and non-H)");
546 if (G1TraceRegions) {
547 if (res != NULL) {
548 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
549 "top "PTR_FORMAT,
550 res->hrs_index(), res->bottom(), res->end(), res->top());
551 }
552 }
554 return res;
555 }
557 HeapRegion* G1CollectedHeap::newAllocRegionWithExpansion(int purpose,
558 size_t word_size,
559 bool zero_filled) {
560 HeapRegion* alloc_region = NULL;
561 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
562 alloc_region = newAllocRegion_work(word_size, true, zero_filled);
563 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
564 alloc_region->set_survivor();
565 }
566 ++_gc_alloc_region_counts[purpose];
567 } else {
568 g1_policy()->note_alloc_region_limit_reached(purpose);
569 }
570 return alloc_region;
571 }
573 // If could fit into free regions w/o expansion, try.
574 // Otherwise, if can expand, do so.
575 // Otherwise, if using ex regions might help, try with ex given back.
576 HeapWord* G1CollectedHeap::humongousObjAllocate(size_t word_size) {
577 assert(regions_accounted_for(), "Region leakage!");
579 // We can't allocate H regions while cleanupComplete is running, since
580 // some of the regions we find to be empty might not yet be added to the
581 // unclean list. (If we're already at a safepoint, this call is
582 // unnecessary, not to mention wrong.)
583 if (!SafepointSynchronize::is_at_safepoint())
584 wait_for_cleanup_complete();
586 size_t num_regions =
587 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
589 // Special case if < one region???
591 // Remember the ft size.
592 size_t x_size = expansion_regions();
594 HeapWord* res = NULL;
595 bool eliminated_allocated_from_lists = false;
597 // Can the allocation potentially fit in the free regions?
598 if (free_regions() >= num_regions) {
599 res = _hrs->obj_allocate(word_size);
600 }
601 if (res == NULL) {
602 // Try expansion.
603 size_t fs = _hrs->free_suffix();
604 if (fs + x_size >= num_regions) {
605 expand((num_regions - fs) * HeapRegion::GrainBytes);
606 res = _hrs->obj_allocate(word_size);
607 assert(res != NULL, "This should have worked.");
608 } else {
609 // Expansion won't help. Are there enough free regions if we get rid
610 // of reservations?
611 size_t avail = free_regions();
612 if (avail >= num_regions) {
613 res = _hrs->obj_allocate(word_size);
614 if (res != NULL) {
615 remove_allocated_regions_from_lists();
616 eliminated_allocated_from_lists = true;
617 }
618 }
619 }
620 }
621 if (res != NULL) {
622 // Increment by the number of regions allocated.
623 // FIXME: Assumes regions all of size GrainBytes.
624 #ifndef PRODUCT
625 mr_bs()->verify_clean_region(MemRegion(res, res + num_regions *
626 HeapRegion::GrainWords));
627 #endif
628 if (!eliminated_allocated_from_lists)
629 remove_allocated_regions_from_lists();
630 _summary_bytes_used += word_size * HeapWordSize;
631 _free_regions -= num_regions;
632 _num_humongous_regions += (int) num_regions;
633 }
634 assert(regions_accounted_for(), "Region Leakage");
635 return res;
636 }
638 HeapWord*
639 G1CollectedHeap::attempt_allocation_slow(size_t word_size,
640 bool permit_collection_pause) {
641 HeapWord* res = NULL;
642 HeapRegion* allocated_young_region = NULL;
644 assert( SafepointSynchronize::is_at_safepoint() ||
645 Heap_lock->owned_by_self(), "pre condition of the call" );
647 if (isHumongous(word_size)) {
648 // Allocation of a humongous object can, in a sense, complete a
649 // partial region, if the previous alloc was also humongous, and
650 // caused the test below to succeed.
651 if (permit_collection_pause)
652 do_collection_pause_if_appropriate(word_size);
653 res = humongousObjAllocate(word_size);
654 assert(_cur_alloc_region == NULL
655 || !_cur_alloc_region->isHumongous(),
656 "Prevent a regression of this bug.");
658 } else {
659 // We may have concurrent cleanup working at the time. Wait for it
660 // to complete. In the future we would probably want to make the
661 // concurrent cleanup truly concurrent by decoupling it from the
662 // allocation.
663 if (!SafepointSynchronize::is_at_safepoint())
664 wait_for_cleanup_complete();
665 // If we do a collection pause, this will be reset to a non-NULL
666 // value. If we don't, nulling here ensures that we allocate a new
667 // region below.
668 if (_cur_alloc_region != NULL) {
669 // We're finished with the _cur_alloc_region.
670 _summary_bytes_used += _cur_alloc_region->used();
671 _cur_alloc_region = NULL;
672 }
673 assert(_cur_alloc_region == NULL, "Invariant.");
674 // Completion of a heap region is perhaps a good point at which to do
675 // a collection pause.
676 if (permit_collection_pause)
677 do_collection_pause_if_appropriate(word_size);
678 // Make sure we have an allocation region available.
679 if (_cur_alloc_region == NULL) {
680 if (!SafepointSynchronize::is_at_safepoint())
681 wait_for_cleanup_complete();
682 bool next_is_young = should_set_young_locked();
683 // If the next region is not young, make sure it's zero-filled.
684 _cur_alloc_region = newAllocRegion(word_size, !next_is_young);
685 if (_cur_alloc_region != NULL) {
686 _summary_bytes_used -= _cur_alloc_region->used();
687 if (next_is_young) {
688 set_region_short_lived_locked(_cur_alloc_region);
689 allocated_young_region = _cur_alloc_region;
690 }
691 }
692 }
693 assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
694 "Prevent a regression of this bug.");
696 // Now retry the allocation.
697 if (_cur_alloc_region != NULL) {
698 res = _cur_alloc_region->allocate(word_size);
699 }
700 }
702 // NOTE: fails frequently in PRT
703 assert(regions_accounted_for(), "Region leakage!");
705 if (res != NULL) {
706 if (!SafepointSynchronize::is_at_safepoint()) {
707 assert( permit_collection_pause, "invariant" );
708 assert( Heap_lock->owned_by_self(), "invariant" );
709 Heap_lock->unlock();
710 }
712 if (allocated_young_region != NULL) {
713 HeapRegion* hr = allocated_young_region;
714 HeapWord* bottom = hr->bottom();
715 HeapWord* end = hr->end();
716 MemRegion mr(bottom, end);
717 ((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr);
718 }
719 }
721 assert( SafepointSynchronize::is_at_safepoint() ||
722 (res == NULL && Heap_lock->owned_by_self()) ||
723 (res != NULL && !Heap_lock->owned_by_self()),
724 "post condition of the call" );
726 return res;
727 }
729 HeapWord*
730 G1CollectedHeap::mem_allocate(size_t word_size,
731 bool is_noref,
732 bool is_tlab,
733 bool* gc_overhead_limit_was_exceeded) {
734 debug_only(check_for_valid_allocation_state());
735 assert(no_gc_in_progress(), "Allocation during gc not allowed");
736 HeapWord* result = NULL;
738 // Loop until the allocation is satisified,
739 // or unsatisfied after GC.
740 for (int try_count = 1; /* return or throw */; try_count += 1) {
741 int gc_count_before;
742 {
743 Heap_lock->lock();
744 result = attempt_allocation(word_size);
745 if (result != NULL) {
746 // attempt_allocation should have unlocked the heap lock
747 assert(is_in(result), "result not in heap");
748 return result;
749 }
750 // Read the gc count while the heap lock is held.
751 gc_count_before = SharedHeap::heap()->total_collections();
752 Heap_lock->unlock();
753 }
755 // Create the garbage collection operation...
756 VM_G1CollectForAllocation op(word_size,
757 gc_count_before);
759 // ...and get the VM thread to execute it.
760 VMThread::execute(&op);
761 if (op.prologue_succeeded()) {
762 result = op.result();
763 assert(result == NULL || is_in(result), "result not in heap");
764 return result;
765 }
767 // Give a warning if we seem to be looping forever.
768 if ((QueuedAllocationWarningCount > 0) &&
769 (try_count % QueuedAllocationWarningCount == 0)) {
770 warning("G1CollectedHeap::mem_allocate_work retries %d times",
771 try_count);
772 }
773 }
774 }
776 void G1CollectedHeap::abandon_cur_alloc_region() {
777 if (_cur_alloc_region != NULL) {
778 // We're finished with the _cur_alloc_region.
779 if (_cur_alloc_region->is_empty()) {
780 _free_regions++;
781 free_region(_cur_alloc_region);
782 } else {
783 _summary_bytes_used += _cur_alloc_region->used();
784 }
785 _cur_alloc_region = NULL;
786 }
787 }
789 void G1CollectedHeap::abandon_gc_alloc_regions() {
790 // first, make sure that the GC alloc region list is empty (it should!)
791 assert(_gc_alloc_region_list == NULL, "invariant");
792 release_gc_alloc_regions(true /* totally */);
793 }
795 class PostMCRemSetClearClosure: public HeapRegionClosure {
796 ModRefBarrierSet* _mr_bs;
797 public:
798 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
799 bool doHeapRegion(HeapRegion* r) {
800 r->reset_gc_time_stamp();
801 if (r->continuesHumongous())
802 return false;
803 HeapRegionRemSet* hrrs = r->rem_set();
804 if (hrrs != NULL) hrrs->clear();
805 // You might think here that we could clear just the cards
806 // corresponding to the used region. But no: if we leave a dirty card
807 // in a region we might allocate into, then it would prevent that card
808 // from being enqueued, and cause it to be missed.
809 // Re: the performance cost: we shouldn't be doing full GC anyway!
810 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
811 return false;
812 }
813 };
816 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
817 ModRefBarrierSet* _mr_bs;
818 public:
819 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
820 bool doHeapRegion(HeapRegion* r) {
821 if (r->continuesHumongous()) return false;
822 if (r->used_region().word_size() != 0) {
823 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
824 }
825 return false;
826 }
827 };
829 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
830 G1CollectedHeap* _g1h;
831 UpdateRSOopClosure _cl;
832 int _worker_i;
833 public:
834 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
835 _cl(g1->g1_rem_set()->as_HRInto_G1RemSet(), worker_i),
836 _worker_i(worker_i),
837 _g1h(g1)
838 { }
839 bool doHeapRegion(HeapRegion* r) {
840 if (!r->continuesHumongous()) {
841 _cl.set_from(r);
842 r->oop_iterate(&_cl);
843 }
844 return false;
845 }
846 };
848 class ParRebuildRSTask: public AbstractGangTask {
849 G1CollectedHeap* _g1;
850 public:
851 ParRebuildRSTask(G1CollectedHeap* g1)
852 : AbstractGangTask("ParRebuildRSTask"),
853 _g1(g1)
854 { }
856 void work(int i) {
857 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
858 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
859 HeapRegion::RebuildRSClaimValue);
860 }
861 };
863 void G1CollectedHeap::do_collection(bool full, bool clear_all_soft_refs,
864 size_t word_size) {
865 ResourceMark rm;
867 if (full && DisableExplicitGC) {
868 gclog_or_tty->print("\n\n\nDisabling Explicit GC\n\n\n");
869 return;
870 }
872 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
873 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
875 if (GC_locker::is_active()) {
876 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
877 }
879 {
880 IsGCActiveMark x;
882 // Timing
883 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
884 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
885 TraceTime t(full ? "Full GC (System.gc())" : "Full GC", PrintGC, true, gclog_or_tty);
887 double start = os::elapsedTime();
888 GCOverheadReporter::recordSTWStart(start);
889 g1_policy()->record_full_collection_start();
891 gc_prologue(true);
892 increment_total_collections();
894 size_t g1h_prev_used = used();
895 assert(used() == recalculate_used(), "Should be equal");
897 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
898 HandleMark hm; // Discard invalid handles created during verification
899 prepare_for_verify();
900 gclog_or_tty->print(" VerifyBeforeGC:");
901 Universe::verify(true);
902 }
903 assert(regions_accounted_for(), "Region leakage!");
905 COMPILER2_PRESENT(DerivedPointerTable::clear());
907 // We want to discover references, but not process them yet.
908 // This mode is disabled in
909 // instanceRefKlass::process_discovered_references if the
910 // generation does some collection work, or
911 // instanceRefKlass::enqueue_discovered_references if the
912 // generation returns without doing any work.
913 ref_processor()->disable_discovery();
914 ref_processor()->abandon_partial_discovery();
915 ref_processor()->verify_no_references_recorded();
917 // Abandon current iterations of concurrent marking and concurrent
918 // refinement, if any are in progress.
919 concurrent_mark()->abort();
921 // Make sure we'll choose a new allocation region afterwards.
922 abandon_cur_alloc_region();
923 abandon_gc_alloc_regions();
924 assert(_cur_alloc_region == NULL, "Invariant.");
925 g1_rem_set()->as_HRInto_G1RemSet()->cleanupHRRS();
926 tear_down_region_lists();
927 set_used_regions_to_need_zero_fill();
928 if (g1_policy()->in_young_gc_mode()) {
929 empty_young_list();
930 g1_policy()->set_full_young_gcs(true);
931 }
933 // Temporarily make reference _discovery_ single threaded (non-MT).
934 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
936 // Temporarily make refs discovery atomic
937 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
939 // Temporarily clear _is_alive_non_header
940 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
942 ref_processor()->enable_discovery();
943 ref_processor()->setup_policy(clear_all_soft_refs);
945 // Do collection work
946 {
947 HandleMark hm; // Discard invalid handles created during gc
948 G1MarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);
949 }
950 // Because freeing humongous regions may have added some unclean
951 // regions, it is necessary to tear down again before rebuilding.
952 tear_down_region_lists();
953 rebuild_region_lists();
955 _summary_bytes_used = recalculate_used();
957 ref_processor()->enqueue_discovered_references();
959 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
961 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
962 HandleMark hm; // Discard invalid handles created during verification
963 gclog_or_tty->print(" VerifyAfterGC:");
964 prepare_for_verify();
965 Universe::verify(false);
966 }
967 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
969 reset_gc_time_stamp();
970 // Since everything potentially moved, we will clear all remembered
971 // sets, and clear all cards. Later we will rebuild remebered
972 // sets. We will also reset the GC time stamps of the regions.
973 PostMCRemSetClearClosure rs_clear(mr_bs());
974 heap_region_iterate(&rs_clear);
976 // Resize the heap if necessary.
977 resize_if_necessary_after_full_collection(full ? 0 : word_size);
979 if (_cg1r->use_cache()) {
980 _cg1r->clear_and_record_card_counts();
981 _cg1r->clear_hot_cache();
982 }
984 // Rebuild remembered sets of all regions.
985 if (ParallelGCThreads > 0) {
986 ParRebuildRSTask rebuild_rs_task(this);
987 assert(check_heap_region_claim_values(
988 HeapRegion::InitialClaimValue), "sanity check");
989 set_par_threads(workers()->total_workers());
990 workers()->run_task(&rebuild_rs_task);
991 set_par_threads(0);
992 assert(check_heap_region_claim_values(
993 HeapRegion::RebuildRSClaimValue), "sanity check");
994 reset_heap_region_claim_values();
995 } else {
996 RebuildRSOutOfRegionClosure rebuild_rs(this);
997 heap_region_iterate(&rebuild_rs);
998 }
1000 if (PrintGC) {
1001 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1002 }
1004 if (true) { // FIXME
1005 // Ask the permanent generation to adjust size for full collections
1006 perm()->compute_new_size();
1007 }
1009 double end = os::elapsedTime();
1010 GCOverheadReporter::recordSTWEnd(end);
1011 g1_policy()->record_full_collection_end();
1013 #ifdef TRACESPINNING
1014 ParallelTaskTerminator::print_termination_counts();
1015 #endif
1017 gc_epilogue(true);
1019 // Abandon concurrent refinement. This must happen last: in the
1020 // dirty-card logging system, some cards may be dirty by weak-ref
1021 // processing, and may be enqueued. But the whole card table is
1022 // dirtied, so this should abandon those logs, and set "do_traversal"
1023 // to true.
1024 concurrent_g1_refine()->set_pya_restart();
1025 assert(!G1DeferredRSUpdate
1026 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1027 assert(regions_accounted_for(), "Region leakage!");
1028 }
1030 if (g1_policy()->in_young_gc_mode()) {
1031 _young_list->reset_sampled_info();
1032 assert( check_young_list_empty(false, false),
1033 "young list should be empty at this point");
1034 }
1035 }
1037 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1038 do_collection(true, clear_all_soft_refs, 0);
1039 }
1041 // This code is mostly copied from TenuredGeneration.
1042 void
1043 G1CollectedHeap::
1044 resize_if_necessary_after_full_collection(size_t word_size) {
1045 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1047 // Include the current allocation, if any, and bytes that will be
1048 // pre-allocated to support collections, as "used".
1049 const size_t used_after_gc = used();
1050 const size_t capacity_after_gc = capacity();
1051 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1053 // We don't have floating point command-line arguments
1054 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100;
1055 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1056 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
1057 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1059 size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage);
1060 size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage);
1062 // Don't shrink less than the initial size.
1063 minimum_desired_capacity =
1064 MAX2(minimum_desired_capacity,
1065 collector_policy()->initial_heap_byte_size());
1066 maximum_desired_capacity =
1067 MAX2(maximum_desired_capacity,
1068 collector_policy()->initial_heap_byte_size());
1070 // We are failing here because minimum_desired_capacity is
1071 assert(used_after_gc <= minimum_desired_capacity, "sanity check");
1072 assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check");
1074 if (PrintGC && Verbose) {
1075 const double free_percentage = ((double)free_after_gc) / capacity();
1076 gclog_or_tty->print_cr("Computing new size after full GC ");
1077 gclog_or_tty->print_cr(" "
1078 " minimum_free_percentage: %6.2f",
1079 minimum_free_percentage);
1080 gclog_or_tty->print_cr(" "
1081 " maximum_free_percentage: %6.2f",
1082 maximum_free_percentage);
1083 gclog_or_tty->print_cr(" "
1084 " capacity: %6.1fK"
1085 " minimum_desired_capacity: %6.1fK"
1086 " maximum_desired_capacity: %6.1fK",
1087 capacity() / (double) K,
1088 minimum_desired_capacity / (double) K,
1089 maximum_desired_capacity / (double) K);
1090 gclog_or_tty->print_cr(" "
1091 " free_after_gc : %6.1fK"
1092 " used_after_gc : %6.1fK",
1093 free_after_gc / (double) K,
1094 used_after_gc / (double) K);
1095 gclog_or_tty->print_cr(" "
1096 " free_percentage: %6.2f",
1097 free_percentage);
1098 }
1099 if (capacity() < minimum_desired_capacity) {
1100 // Don't expand unless it's significant
1101 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1102 expand(expand_bytes);
1103 if (PrintGC && Verbose) {
1104 gclog_or_tty->print_cr(" expanding:"
1105 " minimum_desired_capacity: %6.1fK"
1106 " expand_bytes: %6.1fK",
1107 minimum_desired_capacity / (double) K,
1108 expand_bytes / (double) K);
1109 }
1111 // No expansion, now see if we want to shrink
1112 } else if (capacity() > maximum_desired_capacity) {
1113 // Capacity too large, compute shrinking size
1114 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1115 shrink(shrink_bytes);
1116 if (PrintGC && Verbose) {
1117 gclog_or_tty->print_cr(" "
1118 " shrinking:"
1119 " initSize: %.1fK"
1120 " maximum_desired_capacity: %.1fK",
1121 collector_policy()->initial_heap_byte_size() / (double) K,
1122 maximum_desired_capacity / (double) K);
1123 gclog_or_tty->print_cr(" "
1124 " shrink_bytes: %.1fK",
1125 shrink_bytes / (double) K);
1126 }
1127 }
1128 }
1131 HeapWord*
1132 G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
1133 HeapWord* result = NULL;
1135 // In a G1 heap, we're supposed to keep allocation from failing by
1136 // incremental pauses. Therefore, at least for now, we'll favor
1137 // expansion over collection. (This might change in the future if we can
1138 // do something smarter than full collection to satisfy a failed alloc.)
1140 result = expand_and_allocate(word_size);
1141 if (result != NULL) {
1142 assert(is_in(result), "result not in heap");
1143 return result;
1144 }
1146 // OK, I guess we have to try collection.
1148 do_collection(false, false, word_size);
1150 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1152 if (result != NULL) {
1153 assert(is_in(result), "result not in heap");
1154 return result;
1155 }
1157 // Try collecting soft references.
1158 do_collection(false, true, word_size);
1159 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1160 if (result != NULL) {
1161 assert(is_in(result), "result not in heap");
1162 return result;
1163 }
1165 // What else? We might try synchronous finalization later. If the total
1166 // space available is large enough for the allocation, then a more
1167 // complete compaction phase than we've tried so far might be
1168 // appropriate.
1169 return NULL;
1170 }
1172 // Attempting to expand the heap sufficiently
1173 // to support an allocation of the given "word_size". If
1174 // successful, perform the allocation and return the address of the
1175 // allocated block, or else "NULL".
1177 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1178 size_t expand_bytes = word_size * HeapWordSize;
1179 if (expand_bytes < MinHeapDeltaBytes) {
1180 expand_bytes = MinHeapDeltaBytes;
1181 }
1182 expand(expand_bytes);
1183 assert(regions_accounted_for(), "Region leakage!");
1184 HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
1185 return result;
1186 }
1188 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
1189 size_t pre_used = 0;
1190 size_t cleared_h_regions = 0;
1191 size_t freed_regions = 0;
1192 UncleanRegionList local_list;
1193 free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
1194 freed_regions, &local_list);
1196 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
1197 &local_list);
1198 return pre_used;
1199 }
1201 void
1202 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
1203 size_t& pre_used,
1204 size_t& cleared_h,
1205 size_t& freed_regions,
1206 UncleanRegionList* list,
1207 bool par) {
1208 assert(!hr->continuesHumongous(), "should have filtered these out");
1209 size_t res = 0;
1210 if (!hr->popular() && hr->used() > 0 && hr->garbage_bytes() == hr->used()) {
1211 if (!hr->is_young()) {
1212 if (G1PolicyVerbose > 0)
1213 gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
1214 " during cleanup", hr, hr->used());
1215 free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
1216 }
1217 }
1218 }
1220 // FIXME: both this and shrink could probably be more efficient by
1221 // doing one "VirtualSpace::expand_by" call rather than several.
1222 void G1CollectedHeap::expand(size_t expand_bytes) {
1223 size_t old_mem_size = _g1_storage.committed_size();
1224 // We expand by a minimum of 1K.
1225 expand_bytes = MAX2(expand_bytes, (size_t)K);
1226 size_t aligned_expand_bytes =
1227 ReservedSpace::page_align_size_up(expand_bytes);
1228 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1229 HeapRegion::GrainBytes);
1230 expand_bytes = aligned_expand_bytes;
1231 while (expand_bytes > 0) {
1232 HeapWord* base = (HeapWord*)_g1_storage.high();
1233 // Commit more storage.
1234 bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
1235 if (!successful) {
1236 expand_bytes = 0;
1237 } else {
1238 expand_bytes -= HeapRegion::GrainBytes;
1239 // Expand the committed region.
1240 HeapWord* high = (HeapWord*) _g1_storage.high();
1241 _g1_committed.set_end(high);
1242 // Create a new HeapRegion.
1243 MemRegion mr(base, high);
1244 bool is_zeroed = !_g1_max_committed.contains(base);
1245 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1247 // Now update max_committed if necessary.
1248 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
1250 // Add it to the HeapRegionSeq.
1251 _hrs->insert(hr);
1252 // Set the zero-fill state, according to whether it's already
1253 // zeroed.
1254 {
1255 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
1256 if (is_zeroed) {
1257 hr->set_zero_fill_complete();
1258 put_free_region_on_list_locked(hr);
1259 } else {
1260 hr->set_zero_fill_needed();
1261 put_region_on_unclean_list_locked(hr);
1262 }
1263 }
1264 _free_regions++;
1265 // And we used up an expansion region to create it.
1266 _expansion_regions--;
1267 // Tell the cardtable about it.
1268 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1269 // And the offset table as well.
1270 _bot_shared->resize(_g1_committed.word_size());
1271 }
1272 }
1273 if (Verbose && PrintGC) {
1274 size_t new_mem_size = _g1_storage.committed_size();
1275 gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
1276 old_mem_size/K, aligned_expand_bytes/K,
1277 new_mem_size/K);
1278 }
1279 }
1281 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1282 {
1283 size_t old_mem_size = _g1_storage.committed_size();
1284 size_t aligned_shrink_bytes =
1285 ReservedSpace::page_align_size_down(shrink_bytes);
1286 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1287 HeapRegion::GrainBytes);
1288 size_t num_regions_deleted = 0;
1289 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1291 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1292 if (mr.byte_size() > 0)
1293 _g1_storage.shrink_by(mr.byte_size());
1294 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1296 _g1_committed.set_end(mr.start());
1297 _free_regions -= num_regions_deleted;
1298 _expansion_regions += num_regions_deleted;
1300 // Tell the cardtable about it.
1301 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1303 // And the offset table as well.
1304 _bot_shared->resize(_g1_committed.word_size());
1306 HeapRegionRemSet::shrink_heap(n_regions());
1308 if (Verbose && PrintGC) {
1309 size_t new_mem_size = _g1_storage.committed_size();
1310 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1311 old_mem_size/K, aligned_shrink_bytes/K,
1312 new_mem_size/K);
1313 }
1314 }
1316 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1317 release_gc_alloc_regions(true /* totally */);
1318 tear_down_region_lists(); // We will rebuild them in a moment.
1319 shrink_helper(shrink_bytes);
1320 rebuild_region_lists();
1321 }
1323 // Public methods.
1325 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1326 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1327 #endif // _MSC_VER
1330 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1331 SharedHeap(policy_),
1332 _g1_policy(policy_),
1333 _ref_processor(NULL),
1334 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1335 _bot_shared(NULL),
1336 _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
1337 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1338 _evac_failure_scan_stack(NULL) ,
1339 _mark_in_progress(false),
1340 _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
1341 _cur_alloc_region(NULL),
1342 _refine_cte_cl(NULL),
1343 _free_region_list(NULL), _free_region_list_size(0),
1344 _free_regions(0),
1345 _popular_object_boundary(NULL),
1346 _cur_pop_hr_index(0),
1347 _popular_regions_to_be_evacuated(NULL),
1348 _pop_obj_rc_at_copy(),
1349 _full_collection(false),
1350 _unclean_region_list(),
1351 _unclean_regions_coming(false),
1352 _young_list(new YoungList(this)),
1353 _gc_time_stamp(0),
1354 _surviving_young_words(NULL),
1355 _in_cset_fast_test(NULL),
1356 _in_cset_fast_test_base(NULL) {
1357 _g1h = this; // To catch bugs.
1358 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1359 vm_exit_during_initialization("Failed necessary allocation.");
1360 }
1361 int n_queues = MAX2((int)ParallelGCThreads, 1);
1362 _task_queues = new RefToScanQueueSet(n_queues);
1364 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1365 assert(n_rem_sets > 0, "Invariant.");
1367 HeapRegionRemSetIterator** iter_arr =
1368 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1369 for (int i = 0; i < n_queues; i++) {
1370 iter_arr[i] = new HeapRegionRemSetIterator();
1371 }
1372 _rem_set_iterator = iter_arr;
1374 for (int i = 0; i < n_queues; i++) {
1375 RefToScanQueue* q = new RefToScanQueue();
1376 q->initialize();
1377 _task_queues->register_queue(i, q);
1378 }
1380 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1381 _gc_alloc_regions[ap] = NULL;
1382 _gc_alloc_region_counts[ap] = 0;
1383 _retained_gc_alloc_regions[ap] = NULL;
1384 // by default, we do not retain a GC alloc region for each ap;
1385 // we'll override this, when appropriate, below
1386 _retain_gc_alloc_region[ap] = false;
1387 }
1389 // We will try to remember the last half-full tenured region we
1390 // allocated to at the end of a collection so that we can re-use it
1391 // during the next collection.
1392 _retain_gc_alloc_region[GCAllocForTenured] = true;
1394 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1395 }
1397 jint G1CollectedHeap::initialize() {
1398 os::enable_vtime();
1400 // Necessary to satisfy locking discipline assertions.
1402 MutexLocker x(Heap_lock);
1404 // While there are no constraints in the GC code that HeapWordSize
1405 // be any particular value, there are multiple other areas in the
1406 // system which believe this to be true (e.g. oop->object_size in some
1407 // cases incorrectly returns the size in wordSize units rather than
1408 // HeapWordSize).
1409 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1411 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1412 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1414 // Ensure that the sizes are properly aligned.
1415 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1416 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1418 // We allocate this in any case, but only do no work if the command line
1419 // param is off.
1420 _cg1r = new ConcurrentG1Refine();
1422 // Reserve the maximum.
1423 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1424 // Includes the perm-gen.
1426 const size_t total_reserved = max_byte_size + pgs->max_size();
1427 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1429 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1430 HeapRegion::GrainBytes,
1431 false /*ism*/, addr);
1433 if (UseCompressedOops) {
1434 if (addr != NULL && !heap_rs.is_reserved()) {
1435 // Failed to reserve at specified address - the requested memory
1436 // region is taken already, for example, by 'java' launcher.
1437 // Try again to reserver heap higher.
1438 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1439 ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1440 false /*ism*/, addr);
1441 if (addr != NULL && !heap_rs0.is_reserved()) {
1442 // Failed to reserve at specified address again - give up.
1443 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1444 assert(addr == NULL, "");
1445 ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1446 false /*ism*/, addr);
1447 heap_rs = heap_rs1;
1448 } else {
1449 heap_rs = heap_rs0;
1450 }
1451 }
1452 }
1454 if (!heap_rs.is_reserved()) {
1455 vm_exit_during_initialization("Could not reserve enough space for object heap");
1456 return JNI_ENOMEM;
1457 }
1459 // It is important to do this in a way such that concurrent readers can't
1460 // temporarily think somethings in the heap. (I've actually seen this
1461 // happen in asserts: DLD.)
1462 _reserved.set_word_size(0);
1463 _reserved.set_start((HeapWord*)heap_rs.base());
1464 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1466 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1468 _num_humongous_regions = 0;
1470 // Create the gen rem set (and barrier set) for the entire reserved region.
1471 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1472 set_barrier_set(rem_set()->bs());
1473 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1474 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1475 } else {
1476 vm_exit_during_initialization("G1 requires a mod ref bs.");
1477 return JNI_ENOMEM;
1478 }
1480 // Also create a G1 rem set.
1481 if (G1UseHRIntoRS) {
1482 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1483 _g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs());
1484 } else {
1485 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1486 return JNI_ENOMEM;
1487 }
1488 } else {
1489 _g1_rem_set = new StupidG1RemSet(this);
1490 }
1492 // Carve out the G1 part of the heap.
1494 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1495 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1496 g1_rs.size()/HeapWordSize);
1497 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1499 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1501 _g1_storage.initialize(g1_rs, 0);
1502 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1503 _g1_max_committed = _g1_committed;
1504 _hrs = new HeapRegionSeq(_expansion_regions);
1505 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1506 guarantee(_cur_alloc_region == NULL, "from constructor");
1508 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1509 heap_word_size(init_byte_size));
1511 _g1h = this;
1513 // Create the ConcurrentMark data structure and thread.
1514 // (Must do this late, so that "max_regions" is defined.)
1515 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1516 _cmThread = _cm->cmThread();
1518 // ...and the concurrent zero-fill thread, if necessary.
1519 if (G1ConcZeroFill) {
1520 _czft = new ConcurrentZFThread();
1521 }
1525 // Allocate the popular regions; take them off free lists.
1526 size_t pop_byte_size = G1NumPopularRegions * HeapRegion::GrainBytes;
1527 expand(pop_byte_size);
1528 _popular_object_boundary =
1529 _g1_reserved.start() + (G1NumPopularRegions * HeapRegion::GrainWords);
1530 for (int i = 0; i < G1NumPopularRegions; i++) {
1531 HeapRegion* hr = newAllocRegion(HeapRegion::GrainWords);
1532 // assert(hr != NULL && hr->bottom() < _popular_object_boundary,
1533 // "Should be enough, and all should be below boundary.");
1534 hr->set_popular(true);
1535 }
1536 assert(_cur_pop_hr_index == 0, "Start allocating at the first region.");
1538 // Initialize the from_card cache structure of HeapRegionRemSet.
1539 HeapRegionRemSet::init_heap(max_regions());
1541 // Now expand into the rest of the initial heap size.
1542 expand(init_byte_size - pop_byte_size);
1544 // Perform any initialization actions delegated to the policy.
1545 g1_policy()->init();
1547 g1_policy()->note_start_of_mark_thread();
1549 _refine_cte_cl =
1550 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1551 g1_rem_set(),
1552 concurrent_g1_refine());
1553 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1555 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1556 SATB_Q_FL_lock,
1557 0,
1558 Shared_SATB_Q_lock);
1559 if (G1RSBarrierUseQueue) {
1560 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1561 DirtyCardQ_FL_lock,
1562 G1DirtyCardQueueMax,
1563 Shared_DirtyCardQ_lock);
1564 }
1565 if (G1DeferredRSUpdate) {
1566 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1567 DirtyCardQ_FL_lock,
1568 0,
1569 Shared_DirtyCardQ_lock,
1570 &JavaThread::dirty_card_queue_set());
1571 }
1572 // In case we're keeping closure specialization stats, initialize those
1573 // counts and that mechanism.
1574 SpecializationStats::clear();
1576 _gc_alloc_region_list = NULL;
1578 // Do later initialization work for concurrent refinement.
1579 _cg1r->init();
1581 const char* group_names[] = { "CR", "ZF", "CM", "CL" };
1582 GCOverheadReporter::initGCOverheadReporter(4, group_names);
1584 return JNI_OK;
1585 }
1587 void G1CollectedHeap::ref_processing_init() {
1588 SharedHeap::ref_processing_init();
1589 MemRegion mr = reserved_region();
1590 _ref_processor = ReferenceProcessor::create_ref_processor(
1591 mr, // span
1592 false, // Reference discovery is not atomic
1593 // (though it shouldn't matter here.)
1594 true, // mt_discovery
1595 NULL, // is alive closure: need to fill this in for efficiency
1596 ParallelGCThreads,
1597 ParallelRefProcEnabled,
1598 true); // Setting next fields of discovered
1599 // lists requires a barrier.
1600 }
1602 size_t G1CollectedHeap::capacity() const {
1603 return _g1_committed.byte_size();
1604 }
1606 void G1CollectedHeap::iterate_dirty_card_closure(bool concurrent,
1607 int worker_i) {
1608 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1609 int n_completed_buffers = 0;
1610 while (dcqs.apply_closure_to_completed_buffer(worker_i, 0, true)) {
1611 n_completed_buffers++;
1612 }
1613 g1_policy()->record_update_rs_processed_buffers(worker_i,
1614 (double) n_completed_buffers);
1615 dcqs.clear_n_completed_buffers();
1616 // Finish up the queue...
1617 if (worker_i == 0) concurrent_g1_refine()->clean_up_cache(worker_i,
1618 g1_rem_set());
1619 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1620 }
1623 // Computes the sum of the storage used by the various regions.
1625 size_t G1CollectedHeap::used() const {
1626 assert(Heap_lock->owner() != NULL,
1627 "Should be owned on this thread's behalf.");
1628 size_t result = _summary_bytes_used;
1629 if (_cur_alloc_region != NULL)
1630 result += _cur_alloc_region->used();
1631 return result;
1632 }
1634 class SumUsedClosure: public HeapRegionClosure {
1635 size_t _used;
1636 public:
1637 SumUsedClosure() : _used(0) {}
1638 bool doHeapRegion(HeapRegion* r) {
1639 if (!r->continuesHumongous()) {
1640 _used += r->used();
1641 }
1642 return false;
1643 }
1644 size_t result() { return _used; }
1645 };
1647 size_t G1CollectedHeap::recalculate_used() const {
1648 SumUsedClosure blk;
1649 _hrs->iterate(&blk);
1650 return blk.result();
1651 }
1653 #ifndef PRODUCT
1654 class SumUsedRegionsClosure: public HeapRegionClosure {
1655 size_t _num;
1656 public:
1657 // _num is set to 1 to account for the popular region
1658 SumUsedRegionsClosure() : _num(G1NumPopularRegions) {}
1659 bool doHeapRegion(HeapRegion* r) {
1660 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
1661 _num += 1;
1662 }
1663 return false;
1664 }
1665 size_t result() { return _num; }
1666 };
1668 size_t G1CollectedHeap::recalculate_used_regions() const {
1669 SumUsedRegionsClosure blk;
1670 _hrs->iterate(&blk);
1671 return blk.result();
1672 }
1673 #endif // PRODUCT
1675 size_t G1CollectedHeap::unsafe_max_alloc() {
1676 if (_free_regions > 0) return HeapRegion::GrainBytes;
1677 // otherwise, is there space in the current allocation region?
1679 // We need to store the current allocation region in a local variable
1680 // here. The problem is that this method doesn't take any locks and
1681 // there may be other threads which overwrite the current allocation
1682 // region field. attempt_allocation(), for example, sets it to NULL
1683 // and this can happen *after* the NULL check here but before the call
1684 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
1685 // to be a problem in the optimized build, since the two loads of the
1686 // current allocation region field are optimized away.
1687 HeapRegion* car = _cur_alloc_region;
1689 // FIXME: should iterate over all regions?
1690 if (car == NULL) {
1691 return 0;
1692 }
1693 return car->free();
1694 }
1696 void G1CollectedHeap::collect(GCCause::Cause cause) {
1697 // The caller doesn't have the Heap_lock
1698 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
1699 MutexLocker ml(Heap_lock);
1700 collect_locked(cause);
1701 }
1703 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
1704 assert(Thread::current()->is_VM_thread(), "Precondition#1");
1705 assert(Heap_lock->is_locked(), "Precondition#2");
1706 GCCauseSetter gcs(this, cause);
1707 switch (cause) {
1708 case GCCause::_heap_inspection:
1709 case GCCause::_heap_dump: {
1710 HandleMark hm;
1711 do_full_collection(false); // don't clear all soft refs
1712 break;
1713 }
1714 default: // XXX FIX ME
1715 ShouldNotReachHere(); // Unexpected use of this function
1716 }
1717 }
1720 void G1CollectedHeap::collect_locked(GCCause::Cause cause) {
1721 // Don't want to do a GC until cleanup is completed.
1722 wait_for_cleanup_complete();
1724 // Read the GC count while holding the Heap_lock
1725 int gc_count_before = SharedHeap::heap()->total_collections();
1726 {
1727 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
1728 VM_G1CollectFull op(gc_count_before, cause);
1729 VMThread::execute(&op);
1730 }
1731 }
1733 bool G1CollectedHeap::is_in(const void* p) const {
1734 if (_g1_committed.contains(p)) {
1735 HeapRegion* hr = _hrs->addr_to_region(p);
1736 return hr->is_in(p);
1737 } else {
1738 return _perm_gen->as_gen()->is_in(p);
1739 }
1740 }
1742 // Iteration functions.
1744 // Iterates an OopClosure over all ref-containing fields of objects
1745 // within a HeapRegion.
1747 class IterateOopClosureRegionClosure: public HeapRegionClosure {
1748 MemRegion _mr;
1749 OopClosure* _cl;
1750 public:
1751 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
1752 : _mr(mr), _cl(cl) {}
1753 bool doHeapRegion(HeapRegion* r) {
1754 if (! r->continuesHumongous()) {
1755 r->oop_iterate(_cl);
1756 }
1757 return false;
1758 }
1759 };
1761 void G1CollectedHeap::oop_iterate(OopClosure* cl) {
1762 IterateOopClosureRegionClosure blk(_g1_committed, cl);
1763 _hrs->iterate(&blk);
1764 }
1766 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) {
1767 IterateOopClosureRegionClosure blk(mr, cl);
1768 _hrs->iterate(&blk);
1769 }
1771 // Iterates an ObjectClosure over all objects within a HeapRegion.
1773 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1774 ObjectClosure* _cl;
1775 public:
1776 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1777 bool doHeapRegion(HeapRegion* r) {
1778 if (! r->continuesHumongous()) {
1779 r->object_iterate(_cl);
1780 }
1781 return false;
1782 }
1783 };
1785 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
1786 IterateObjectClosureRegionClosure blk(cl);
1787 _hrs->iterate(&blk);
1788 }
1790 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1791 // FIXME: is this right?
1792 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
1793 }
1795 // Calls a SpaceClosure on a HeapRegion.
1797 class SpaceClosureRegionClosure: public HeapRegionClosure {
1798 SpaceClosure* _cl;
1799 public:
1800 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1801 bool doHeapRegion(HeapRegion* r) {
1802 _cl->do_space(r);
1803 return false;
1804 }
1805 };
1807 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
1808 SpaceClosureRegionClosure blk(cl);
1809 _hrs->iterate(&blk);
1810 }
1812 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
1813 _hrs->iterate(cl);
1814 }
1816 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
1817 HeapRegionClosure* cl) {
1818 _hrs->iterate_from(r, cl);
1819 }
1821 void
1822 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
1823 _hrs->iterate_from(idx, cl);
1824 }
1826 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
1828 void
1829 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1830 int worker,
1831 jint claim_value) {
1832 const size_t regions = n_regions();
1833 const size_t worker_num = (ParallelGCThreads > 0 ? ParallelGCThreads : 1);
1834 // try to spread out the starting points of the workers
1835 const size_t start_index = regions / worker_num * (size_t) worker;
1837 // each worker will actually look at all regions
1838 for (size_t count = 0; count < regions; ++count) {
1839 const size_t index = (start_index + count) % regions;
1840 assert(0 <= index && index < regions, "sanity");
1841 HeapRegion* r = region_at(index);
1842 // we'll ignore "continues humongous" regions (we'll process them
1843 // when we come across their corresponding "start humongous"
1844 // region) and regions already claimed
1845 if (r->claim_value() == claim_value || r->continuesHumongous()) {
1846 continue;
1847 }
1848 // OK, try to claim it
1849 if (r->claimHeapRegion(claim_value)) {
1850 // success!
1851 assert(!r->continuesHumongous(), "sanity");
1852 if (r->startsHumongous()) {
1853 // If the region is "starts humongous" we'll iterate over its
1854 // "continues humongous" first; in fact we'll do them
1855 // first. The order is important. In on case, calling the
1856 // closure on the "starts humongous" region might de-allocate
1857 // and clear all its "continues humongous" regions and, as a
1858 // result, we might end up processing them twice. So, we'll do
1859 // them first (notice: most closures will ignore them anyway) and
1860 // then we'll do the "starts humongous" region.
1861 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
1862 HeapRegion* chr = region_at(ch_index);
1864 // if the region has already been claimed or it's not
1865 // "continues humongous" we're done
1866 if (chr->claim_value() == claim_value ||
1867 !chr->continuesHumongous()) {
1868 break;
1869 }
1871 // Noone should have claimed it directly. We can given
1872 // that we claimed its "starts humongous" region.
1873 assert(chr->claim_value() != claim_value, "sanity");
1874 assert(chr->humongous_start_region() == r, "sanity");
1876 if (chr->claimHeapRegion(claim_value)) {
1877 // we should always be able to claim it; noone else should
1878 // be trying to claim this region
1880 bool res2 = cl->doHeapRegion(chr);
1881 assert(!res2, "Should not abort");
1883 // Right now, this holds (i.e., no closure that actually
1884 // does something with "continues humongous" regions
1885 // clears them). We might have to weaken it in the future,
1886 // but let's leave these two asserts here for extra safety.
1887 assert(chr->continuesHumongous(), "should still be the case");
1888 assert(chr->humongous_start_region() == r, "sanity");
1889 } else {
1890 guarantee(false, "we should not reach here");
1891 }
1892 }
1893 }
1895 assert(!r->continuesHumongous(), "sanity");
1896 bool res = cl->doHeapRegion(r);
1897 assert(!res, "Should not abort");
1898 }
1899 }
1900 }
1902 class ResetClaimValuesClosure: public HeapRegionClosure {
1903 public:
1904 bool doHeapRegion(HeapRegion* r) {
1905 r->set_claim_value(HeapRegion::InitialClaimValue);
1906 return false;
1907 }
1908 };
1910 void
1911 G1CollectedHeap::reset_heap_region_claim_values() {
1912 ResetClaimValuesClosure blk;
1913 heap_region_iterate(&blk);
1914 }
1916 #ifdef ASSERT
1917 // This checks whether all regions in the heap have the correct claim
1918 // value. I also piggy-backed on this a check to ensure that the
1919 // humongous_start_region() information on "continues humongous"
1920 // regions is correct.
1922 class CheckClaimValuesClosure : public HeapRegionClosure {
1923 private:
1924 jint _claim_value;
1925 size_t _failures;
1926 HeapRegion* _sh_region;
1927 public:
1928 CheckClaimValuesClosure(jint claim_value) :
1929 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
1930 bool doHeapRegion(HeapRegion* r) {
1931 if (r->claim_value() != _claim_value) {
1932 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1933 "claim value = %d, should be %d",
1934 r->bottom(), r->end(), r->claim_value(),
1935 _claim_value);
1936 ++_failures;
1937 }
1938 if (!r->isHumongous()) {
1939 _sh_region = NULL;
1940 } else if (r->startsHumongous()) {
1941 _sh_region = r;
1942 } else if (r->continuesHumongous()) {
1943 if (r->humongous_start_region() != _sh_region) {
1944 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1945 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
1946 r->bottom(), r->end(),
1947 r->humongous_start_region(),
1948 _sh_region);
1949 ++_failures;
1950 }
1951 }
1952 return false;
1953 }
1954 size_t failures() {
1955 return _failures;
1956 }
1957 };
1959 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
1960 CheckClaimValuesClosure cl(claim_value);
1961 heap_region_iterate(&cl);
1962 return cl.failures() == 0;
1963 }
1964 #endif // ASSERT
1966 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
1967 HeapRegion* r = g1_policy()->collection_set();
1968 while (r != NULL) {
1969 HeapRegion* next = r->next_in_collection_set();
1970 if (cl->doHeapRegion(r)) {
1971 cl->incomplete();
1972 return;
1973 }
1974 r = next;
1975 }
1976 }
1978 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
1979 HeapRegionClosure *cl) {
1980 assert(r->in_collection_set(),
1981 "Start region must be a member of the collection set.");
1982 HeapRegion* cur = r;
1983 while (cur != NULL) {
1984 HeapRegion* next = cur->next_in_collection_set();
1985 if (cl->doHeapRegion(cur) && false) {
1986 cl->incomplete();
1987 return;
1988 }
1989 cur = next;
1990 }
1991 cur = g1_policy()->collection_set();
1992 while (cur != r) {
1993 HeapRegion* next = cur->next_in_collection_set();
1994 if (cl->doHeapRegion(cur) && false) {
1995 cl->incomplete();
1996 return;
1997 }
1998 cur = next;
1999 }
2000 }
2002 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2003 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
2004 }
2007 Space* G1CollectedHeap::space_containing(const void* addr) const {
2008 Space* res = heap_region_containing(addr);
2009 if (res == NULL)
2010 res = perm_gen()->space_containing(addr);
2011 return res;
2012 }
2014 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2015 Space* sp = space_containing(addr);
2016 if (sp != NULL) {
2017 return sp->block_start(addr);
2018 }
2019 return NULL;
2020 }
2022 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2023 Space* sp = space_containing(addr);
2024 assert(sp != NULL, "block_size of address outside of heap");
2025 return sp->block_size(addr);
2026 }
2028 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2029 Space* sp = space_containing(addr);
2030 return sp->block_is_obj(addr);
2031 }
2033 bool G1CollectedHeap::supports_tlab_allocation() const {
2034 return true;
2035 }
2037 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2038 return HeapRegion::GrainBytes;
2039 }
2041 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2042 // Return the remaining space in the cur alloc region, but not less than
2043 // the min TLAB size.
2044 // Also, no more than half the region size, since we can't allow tlabs to
2045 // grow big enough to accomodate humongous objects.
2047 // We need to story it locally, since it might change between when we
2048 // test for NULL and when we use it later.
2049 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
2050 if (cur_alloc_space == NULL) {
2051 return HeapRegion::GrainBytes/2;
2052 } else {
2053 return MAX2(MIN2(cur_alloc_space->free(),
2054 (size_t)(HeapRegion::GrainBytes/2)),
2055 (size_t)MinTLABSize);
2056 }
2057 }
2059 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
2060 bool dummy;
2061 return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
2062 }
2064 bool G1CollectedHeap::allocs_are_zero_filled() {
2065 return false;
2066 }
2068 size_t G1CollectedHeap::large_typearray_limit() {
2069 // FIXME
2070 return HeapRegion::GrainBytes/HeapWordSize;
2071 }
2073 size_t G1CollectedHeap::max_capacity() const {
2074 return _g1_committed.byte_size();
2075 }
2077 jlong G1CollectedHeap::millis_since_last_gc() {
2078 // assert(false, "NYI");
2079 return 0;
2080 }
2083 void G1CollectedHeap::prepare_for_verify() {
2084 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2085 ensure_parsability(false);
2086 }
2087 g1_rem_set()->prepare_for_verify();
2088 }
2090 class VerifyLivenessOopClosure: public OopClosure {
2091 G1CollectedHeap* g1h;
2092 public:
2093 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2094 g1h = _g1h;
2095 }
2096 void do_oop(narrowOop *p) {
2097 guarantee(false, "NYI");
2098 }
2099 void do_oop(oop *p) {
2100 oop obj = *p;
2101 assert(obj == NULL || !g1h->is_obj_dead(obj),
2102 "Dead object referenced by a not dead object");
2103 }
2104 };
2106 class VerifyObjsInRegionClosure: public ObjectClosure {
2107 G1CollectedHeap* _g1h;
2108 size_t _live_bytes;
2109 HeapRegion *_hr;
2110 public:
2111 VerifyObjsInRegionClosure(HeapRegion *hr) : _live_bytes(0), _hr(hr) {
2112 _g1h = G1CollectedHeap::heap();
2113 }
2114 void do_object(oop o) {
2115 VerifyLivenessOopClosure isLive(_g1h);
2116 assert(o != NULL, "Huh?");
2117 if (!_g1h->is_obj_dead(o)) {
2118 o->oop_iterate(&isLive);
2119 if (!_hr->obj_allocated_since_prev_marking(o))
2120 _live_bytes += (o->size() * HeapWordSize);
2121 }
2122 }
2123 size_t live_bytes() { return _live_bytes; }
2124 };
2126 class PrintObjsInRegionClosure : public ObjectClosure {
2127 HeapRegion *_hr;
2128 G1CollectedHeap *_g1;
2129 public:
2130 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2131 _g1 = G1CollectedHeap::heap();
2132 };
2134 void do_object(oop o) {
2135 if (o != NULL) {
2136 HeapWord *start = (HeapWord *) o;
2137 size_t word_sz = o->size();
2138 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2139 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2140 (void*) o, word_sz,
2141 _g1->isMarkedPrev(o),
2142 _g1->isMarkedNext(o),
2143 _hr->obj_allocated_since_prev_marking(o));
2144 HeapWord *end = start + word_sz;
2145 HeapWord *cur;
2146 int *val;
2147 for (cur = start; cur < end; cur++) {
2148 val = (int *) cur;
2149 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2150 }
2151 }
2152 }
2153 };
2155 class VerifyRegionClosure: public HeapRegionClosure {
2156 public:
2157 bool _allow_dirty;
2158 bool _par;
2159 VerifyRegionClosure(bool allow_dirty, bool par = false)
2160 : _allow_dirty(allow_dirty), _par(par) {}
2161 bool doHeapRegion(HeapRegion* r) {
2162 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2163 "Should be unclaimed at verify points.");
2164 if (!r->continuesHumongous()) {
2165 VerifyObjsInRegionClosure not_dead_yet_cl(r);
2166 r->verify(_allow_dirty);
2167 r->object_iterate(¬_dead_yet_cl);
2168 guarantee(r->max_live_bytes() >= not_dead_yet_cl.live_bytes(),
2169 "More live objects than counted in last complete marking.");
2170 }
2171 return false;
2172 }
2173 };
2175 class VerifyRootsClosure: public OopsInGenClosure {
2176 private:
2177 G1CollectedHeap* _g1h;
2178 bool _failures;
2180 public:
2181 VerifyRootsClosure() :
2182 _g1h(G1CollectedHeap::heap()), _failures(false) { }
2184 bool failures() { return _failures; }
2186 void do_oop(narrowOop* p) {
2187 guarantee(false, "NYI");
2188 }
2190 void do_oop(oop* p) {
2191 oop obj = *p;
2192 if (obj != NULL) {
2193 if (_g1h->is_obj_dead(obj)) {
2194 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2195 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2196 obj->print_on(gclog_or_tty);
2197 _failures = true;
2198 }
2199 }
2200 }
2201 };
2203 // This is the task used for parallel heap verification.
2205 class G1ParVerifyTask: public AbstractGangTask {
2206 private:
2207 G1CollectedHeap* _g1h;
2208 bool _allow_dirty;
2210 public:
2211 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty) :
2212 AbstractGangTask("Parallel verify task"),
2213 _g1h(g1h), _allow_dirty(allow_dirty) { }
2215 void work(int worker_i) {
2216 HandleMark hm;
2217 VerifyRegionClosure blk(_allow_dirty, true);
2218 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2219 HeapRegion::ParVerifyClaimValue);
2220 }
2221 };
2223 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2224 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2225 if (!silent) { gclog_or_tty->print("roots "); }
2226 VerifyRootsClosure rootsCl;
2227 process_strong_roots(false,
2228 SharedHeap::SO_AllClasses,
2229 &rootsCl,
2230 &rootsCl);
2231 rem_set()->invalidate(perm_gen()->used_region(), false);
2232 if (!silent) { gclog_or_tty->print("heapRegions "); }
2233 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2234 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2235 "sanity check");
2237 G1ParVerifyTask task(this, allow_dirty);
2238 int n_workers = workers()->total_workers();
2239 set_par_threads(n_workers);
2240 workers()->run_task(&task);
2241 set_par_threads(0);
2243 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2244 "sanity check");
2246 reset_heap_region_claim_values();
2248 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2249 "sanity check");
2250 } else {
2251 VerifyRegionClosure blk(allow_dirty);
2252 _hrs->iterate(&blk);
2253 }
2254 if (!silent) gclog_or_tty->print("remset ");
2255 rem_set()->verify();
2256 guarantee(!rootsCl.failures(), "should not have had failures");
2257 } else {
2258 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2259 }
2260 }
2262 class PrintRegionClosure: public HeapRegionClosure {
2263 outputStream* _st;
2264 public:
2265 PrintRegionClosure(outputStream* st) : _st(st) {}
2266 bool doHeapRegion(HeapRegion* r) {
2267 r->print_on(_st);
2268 return false;
2269 }
2270 };
2272 void G1CollectedHeap::print() const { print_on(gclog_or_tty); }
2274 void G1CollectedHeap::print_on(outputStream* st) const {
2275 PrintRegionClosure blk(st);
2276 _hrs->iterate(&blk);
2277 }
2279 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2280 if (ParallelGCThreads > 0) {
2281 workers()->print_worker_threads();
2282 }
2283 st->print("\"G1 concurrent mark GC Thread\" ");
2284 _cmThread->print();
2285 st->cr();
2286 st->print("\"G1 concurrent refinement GC Thread\" ");
2287 _cg1r->cg1rThread()->print_on(st);
2288 st->cr();
2289 st->print("\"G1 zero-fill GC Thread\" ");
2290 _czft->print_on(st);
2291 st->cr();
2292 }
2294 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2295 if (ParallelGCThreads > 0) {
2296 workers()->threads_do(tc);
2297 }
2298 tc->do_thread(_cmThread);
2299 tc->do_thread(_cg1r->cg1rThread());
2300 tc->do_thread(_czft);
2301 }
2303 void G1CollectedHeap::print_tracing_info() const {
2304 concurrent_g1_refine()->print_final_card_counts();
2306 // We'll overload this to mean "trace GC pause statistics."
2307 if (TraceGen0Time || TraceGen1Time) {
2308 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2309 // to that.
2310 g1_policy()->print_tracing_info();
2311 }
2312 if (SummarizeG1RSStats) {
2313 g1_rem_set()->print_summary_info();
2314 }
2315 if (SummarizeG1ConcMark) {
2316 concurrent_mark()->print_summary_info();
2317 }
2318 if (SummarizeG1ZFStats) {
2319 ConcurrentZFThread::print_summary_info();
2320 }
2321 if (G1SummarizePopularity) {
2322 print_popularity_summary_info();
2323 }
2324 g1_policy()->print_yg_surv_rate_info();
2326 GCOverheadReporter::printGCOverhead();
2328 SpecializationStats::print();
2329 }
2332 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2333 HeapRegion* hr = heap_region_containing(addr);
2334 if (hr == NULL) {
2335 return 0;
2336 } else {
2337 return 1;
2338 }
2339 }
2341 G1CollectedHeap* G1CollectedHeap::heap() {
2342 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2343 "not a garbage-first heap");
2344 return _g1h;
2345 }
2347 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2348 if (PrintHeapAtGC){
2349 gclog_or_tty->print_cr(" {Heap before GC collections=%d:", total_collections());
2350 Universe::print();
2351 }
2352 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2353 // Call allocation profiler
2354 AllocationProfiler::iterate_since_last_gc();
2355 // Fill TLAB's and such
2356 ensure_parsability(true);
2357 }
2359 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2360 // FIXME: what is this about?
2361 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2362 // is set.
2363 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2364 "derived pointer present"));
2366 if (PrintHeapAtGC){
2367 gclog_or_tty->print_cr(" Heap after GC collections=%d:", total_collections());
2368 Universe::print();
2369 gclog_or_tty->print("} ");
2370 }
2371 }
2373 void G1CollectedHeap::do_collection_pause() {
2374 // Read the GC count while holding the Heap_lock
2375 // we need to do this _before_ wait_for_cleanup_complete(), to
2376 // ensure that we do not give up the heap lock and potentially
2377 // pick up the wrong count
2378 int gc_count_before = SharedHeap::heap()->total_collections();
2380 // Don't want to do a GC pause while cleanup is being completed!
2381 wait_for_cleanup_complete();
2383 g1_policy()->record_stop_world_start();
2384 {
2385 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2386 VM_G1IncCollectionPause op(gc_count_before);
2387 VMThread::execute(&op);
2388 }
2389 }
2391 void
2392 G1CollectedHeap::doConcurrentMark() {
2393 if (G1ConcMark) {
2394 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2395 if (!_cmThread->in_progress()) {
2396 _cmThread->set_started();
2397 CGC_lock->notify();
2398 }
2399 }
2400 }
2402 class VerifyMarkedObjsClosure: public ObjectClosure {
2403 G1CollectedHeap* _g1h;
2404 public:
2405 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2406 void do_object(oop obj) {
2407 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2408 "markandsweep mark should agree with concurrent deadness");
2409 }
2410 };
2412 void
2413 G1CollectedHeap::checkConcurrentMark() {
2414 VerifyMarkedObjsClosure verifycl(this);
2415 // MutexLockerEx x(getMarkBitMapLock(),
2416 // Mutex::_no_safepoint_check_flag);
2417 object_iterate(&verifycl);
2418 }
2420 void G1CollectedHeap::do_sync_mark() {
2421 _cm->checkpointRootsInitial();
2422 _cm->markFromRoots();
2423 _cm->checkpointRootsFinal(false);
2424 }
2426 // <NEW PREDICTION>
2428 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2429 bool young) {
2430 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2431 }
2433 void G1CollectedHeap::check_if_region_is_too_expensive(double
2434 predicted_time_ms) {
2435 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2436 }
2438 size_t G1CollectedHeap::pending_card_num() {
2439 size_t extra_cards = 0;
2440 JavaThread *curr = Threads::first();
2441 while (curr != NULL) {
2442 DirtyCardQueue& dcq = curr->dirty_card_queue();
2443 extra_cards += dcq.size();
2444 curr = curr->next();
2445 }
2446 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2447 size_t buffer_size = dcqs.buffer_size();
2448 size_t buffer_num = dcqs.completed_buffers_num();
2449 return buffer_size * buffer_num + extra_cards;
2450 }
2452 size_t G1CollectedHeap::max_pending_card_num() {
2453 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2454 size_t buffer_size = dcqs.buffer_size();
2455 size_t buffer_num = dcqs.completed_buffers_num();
2456 int thread_num = Threads::number_of_threads();
2457 return (buffer_num + thread_num) * buffer_size;
2458 }
2460 size_t G1CollectedHeap::cards_scanned() {
2461 HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
2462 return g1_rset->cardsScanned();
2463 }
2465 void
2466 G1CollectedHeap::setup_surviving_young_words() {
2467 guarantee( _surviving_young_words == NULL, "pre-condition" );
2468 size_t array_length = g1_policy()->young_cset_length();
2469 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2470 if (_surviving_young_words == NULL) {
2471 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2472 "Not enough space for young surv words summary.");
2473 }
2474 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2475 for (size_t i = 0; i < array_length; ++i) {
2476 guarantee( _surviving_young_words[i] == 0, "invariant" );
2477 }
2478 }
2480 void
2481 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2482 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2483 size_t array_length = g1_policy()->young_cset_length();
2484 for (size_t i = 0; i < array_length; ++i)
2485 _surviving_young_words[i] += surv_young_words[i];
2486 }
2488 void
2489 G1CollectedHeap::cleanup_surviving_young_words() {
2490 guarantee( _surviving_young_words != NULL, "pre-condition" );
2491 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2492 _surviving_young_words = NULL;
2493 }
2495 // </NEW PREDICTION>
2497 void
2498 G1CollectedHeap::do_collection_pause_at_safepoint(HeapRegion* popular_region) {
2499 char verbose_str[128];
2500 sprintf(verbose_str, "GC pause ");
2501 if (popular_region != NULL)
2502 strcat(verbose_str, "(popular)");
2503 else if (g1_policy()->in_young_gc_mode()) {
2504 if (g1_policy()->full_young_gcs())
2505 strcat(verbose_str, "(young)");
2506 else
2507 strcat(verbose_str, "(partial)");
2508 }
2509 bool reset_should_initiate_conc_mark = false;
2510 if (popular_region != NULL && g1_policy()->should_initiate_conc_mark()) {
2511 // we currently do not allow an initial mark phase to be piggy-backed
2512 // on a popular pause
2513 reset_should_initiate_conc_mark = true;
2514 g1_policy()->unset_should_initiate_conc_mark();
2515 }
2516 if (g1_policy()->should_initiate_conc_mark())
2517 strcat(verbose_str, " (initial-mark)");
2519 GCCauseSetter x(this, (popular_region == NULL ?
2520 GCCause::_g1_inc_collection_pause :
2521 GCCause::_g1_pop_region_collection_pause));
2523 // if PrintGCDetails is on, we'll print long statistics information
2524 // in the collector policy code, so let's not print this as the output
2525 // is messy if we do.
2526 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2527 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2528 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2530 ResourceMark rm;
2531 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2532 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2533 guarantee(!is_gc_active(), "collection is not reentrant");
2534 assert(regions_accounted_for(), "Region leakage!");
2536 increment_gc_time_stamp();
2538 if (g1_policy()->in_young_gc_mode()) {
2539 assert(check_young_list_well_formed(),
2540 "young list should be well formed");
2541 }
2543 if (GC_locker::is_active()) {
2544 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2545 }
2547 bool abandoned = false;
2548 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2549 IsGCActiveMark x;
2551 gc_prologue(false);
2552 increment_total_collections();
2554 #if G1_REM_SET_LOGGING
2555 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2556 print();
2557 #endif
2559 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2560 HandleMark hm; // Discard invalid handles created during verification
2561 prepare_for_verify();
2562 gclog_or_tty->print(" VerifyBeforeGC:");
2563 Universe::verify(false);
2564 }
2566 COMPILER2_PRESENT(DerivedPointerTable::clear());
2568 // We want to turn off ref discovery, if necessary, and turn it back on
2569 // on again later if we do.
2570 bool was_enabled = ref_processor()->discovery_enabled();
2571 if (was_enabled) ref_processor()->disable_discovery();
2573 // Forget the current alloc region (we might even choose it to be part
2574 // of the collection set!).
2575 abandon_cur_alloc_region();
2577 // The elapsed time induced by the start time below deliberately elides
2578 // the possible verification above.
2579 double start_time_sec = os::elapsedTime();
2580 GCOverheadReporter::recordSTWStart(start_time_sec);
2581 size_t start_used_bytes = used();
2582 if (!G1ConcMark) {
2583 do_sync_mark();
2584 }
2586 g1_policy()->record_collection_pause_start(start_time_sec,
2587 start_used_bytes);
2589 guarantee(_in_cset_fast_test == NULL, "invariant");
2590 guarantee(_in_cset_fast_test_base == NULL, "invariant");
2591 _in_cset_fast_test_length = max_regions();
2592 _in_cset_fast_test_base =
2593 NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2594 memset(_in_cset_fast_test_base, false,
2595 _in_cset_fast_test_length * sizeof(bool));
2596 // We're biasing _in_cset_fast_test to avoid subtracting the
2597 // beginning of the heap every time we want to index; basically
2598 // it's the same with what we do with the card table.
2599 _in_cset_fast_test = _in_cset_fast_test_base -
2600 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2602 #if SCAN_ONLY_VERBOSE
2603 _young_list->print();
2604 #endif // SCAN_ONLY_VERBOSE
2606 if (g1_policy()->should_initiate_conc_mark()) {
2607 concurrent_mark()->checkpointRootsInitialPre();
2608 }
2609 save_marks();
2611 // We must do this before any possible evacuation that should propagate
2612 // marks, including evacuation of popular objects in a popular pause.
2613 if (mark_in_progress()) {
2614 double start_time_sec = os::elapsedTime();
2616 _cm->drainAllSATBBuffers();
2617 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2618 g1_policy()->record_satb_drain_time(finish_mark_ms);
2620 }
2621 // Record the number of elements currently on the mark stack, so we
2622 // only iterate over these. (Since evacuation may add to the mark
2623 // stack, doing more exposes race conditions.) If no mark is in
2624 // progress, this will be zero.
2625 _cm->set_oops_do_bound();
2627 assert(regions_accounted_for(), "Region leakage.");
2629 bool abandoned = false;
2631 if (mark_in_progress())
2632 concurrent_mark()->newCSet();
2634 // Now choose the CS.
2635 if (popular_region == NULL) {
2636 g1_policy()->choose_collection_set();
2637 } else {
2638 // We may be evacuating a single region (for popularity).
2639 g1_policy()->record_popular_pause_preamble_start();
2640 popularity_pause_preamble(popular_region);
2641 g1_policy()->record_popular_pause_preamble_end();
2642 abandoned = (g1_policy()->collection_set() == NULL);
2643 // Now we allow more regions to be added (we have to collect
2644 // all popular regions).
2645 if (!abandoned) {
2646 g1_policy()->choose_collection_set(popular_region);
2647 }
2648 }
2649 // We may abandon a pause if we find no region that will fit in the MMU
2650 // pause.
2651 abandoned = (g1_policy()->collection_set() == NULL);
2653 // Nothing to do if we were unable to choose a collection set.
2654 if (!abandoned) {
2655 #if G1_REM_SET_LOGGING
2656 gclog_or_tty->print_cr("\nAfter pause, heap:");
2657 print();
2658 #endif
2660 setup_surviving_young_words();
2662 // Set up the gc allocation regions.
2663 get_gc_alloc_regions();
2665 // Actually do the work...
2666 evacuate_collection_set();
2667 free_collection_set(g1_policy()->collection_set());
2668 g1_policy()->clear_collection_set();
2670 FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base);
2671 // this is more for peace of mind; we're nulling them here and
2672 // we're expecting them to be null at the beginning of the next GC
2673 _in_cset_fast_test = NULL;
2674 _in_cset_fast_test_base = NULL;
2676 if (popular_region != NULL) {
2677 // We have to wait until now, because we don't want the region to
2678 // be rescheduled for pop-evac during RS update.
2679 popular_region->set_popular_pending(false);
2680 }
2682 release_gc_alloc_regions(false /* totally */);
2684 cleanup_surviving_young_words();
2686 if (g1_policy()->in_young_gc_mode()) {
2687 _young_list->reset_sampled_info();
2688 assert(check_young_list_empty(true),
2689 "young list should be empty");
2691 #if SCAN_ONLY_VERBOSE
2692 _young_list->print();
2693 #endif // SCAN_ONLY_VERBOSE
2695 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
2696 _young_list->first_survivor_region(),
2697 _young_list->last_survivor_region());
2698 _young_list->reset_auxilary_lists();
2699 }
2700 } else {
2701 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
2702 }
2704 if (evacuation_failed()) {
2705 _summary_bytes_used = recalculate_used();
2706 } else {
2707 // The "used" of the the collection set have already been subtracted
2708 // when they were freed. Add in the bytes evacuated.
2709 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2710 }
2712 if (g1_policy()->in_young_gc_mode() &&
2713 g1_policy()->should_initiate_conc_mark()) {
2714 concurrent_mark()->checkpointRootsInitialPost();
2715 set_marking_started();
2716 doConcurrentMark();
2717 }
2719 #if SCAN_ONLY_VERBOSE
2720 _young_list->print();
2721 #endif // SCAN_ONLY_VERBOSE
2723 double end_time_sec = os::elapsedTime();
2724 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
2725 g1_policy()->record_pause_time_ms(pause_time_ms);
2726 GCOverheadReporter::recordSTWEnd(end_time_sec);
2727 g1_policy()->record_collection_pause_end(popular_region != NULL,
2728 abandoned);
2730 assert(regions_accounted_for(), "Region leakage.");
2732 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
2733 HandleMark hm; // Discard invalid handles created during verification
2734 gclog_or_tty->print(" VerifyAfterGC:");
2735 prepare_for_verify();
2736 Universe::verify(false);
2737 }
2739 if (was_enabled) ref_processor()->enable_discovery();
2741 {
2742 size_t expand_bytes = g1_policy()->expansion_amount();
2743 if (expand_bytes > 0) {
2744 size_t bytes_before = capacity();
2745 expand(expand_bytes);
2746 }
2747 }
2749 if (mark_in_progress()) {
2750 concurrent_mark()->update_g1_committed();
2751 }
2753 #ifdef TRACESPINNING
2754 ParallelTaskTerminator::print_termination_counts();
2755 #endif
2757 gc_epilogue(false);
2758 }
2760 assert(verify_region_lists(), "Bad region lists.");
2762 if (reset_should_initiate_conc_mark)
2763 g1_policy()->set_should_initiate_conc_mark();
2765 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
2766 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
2767 print_tracing_info();
2768 vm_exit(-1);
2769 }
2770 }
2772 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
2773 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
2774 // make sure we don't call set_gc_alloc_region() multiple times on
2775 // the same region
2776 assert(r == NULL || !r->is_gc_alloc_region(),
2777 "shouldn't already be a GC alloc region");
2778 HeapWord* original_top = NULL;
2779 if (r != NULL)
2780 original_top = r->top();
2782 // We will want to record the used space in r as being there before gc.
2783 // One we install it as a GC alloc region it's eligible for allocation.
2784 // So record it now and use it later.
2785 size_t r_used = 0;
2786 if (r != NULL) {
2787 r_used = r->used();
2789 if (ParallelGCThreads > 0) {
2790 // need to take the lock to guard against two threads calling
2791 // get_gc_alloc_region concurrently (very unlikely but...)
2792 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2793 r->save_marks();
2794 }
2795 }
2796 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
2797 _gc_alloc_regions[purpose] = r;
2798 if (old_alloc_region != NULL) {
2799 // Replace aliases too.
2800 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2801 if (_gc_alloc_regions[ap] == old_alloc_region) {
2802 _gc_alloc_regions[ap] = r;
2803 }
2804 }
2805 }
2806 if (r != NULL) {
2807 push_gc_alloc_region(r);
2808 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
2809 // We are using a region as a GC alloc region after it has been used
2810 // as a mutator allocation region during the current marking cycle.
2811 // The mutator-allocated objects are currently implicitly marked, but
2812 // when we move hr->next_top_at_mark_start() forward at the the end
2813 // of the GC pause, they won't be. We therefore mark all objects in
2814 // the "gap". We do this object-by-object, since marking densely
2815 // does not currently work right with marking bitmap iteration. This
2816 // means we rely on TLAB filling at the start of pauses, and no
2817 // "resuscitation" of filled TLAB's. If we want to do this, we need
2818 // to fix the marking bitmap iteration.
2819 HeapWord* curhw = r->next_top_at_mark_start();
2820 HeapWord* t = original_top;
2822 while (curhw < t) {
2823 oop cur = (oop)curhw;
2824 // We'll assume parallel for generality. This is rare code.
2825 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
2826 curhw = curhw + cur->size();
2827 }
2828 assert(curhw == t, "Should have parsed correctly.");
2829 }
2830 if (G1PolicyVerbose > 1) {
2831 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
2832 "for survivors:", r->bottom(), original_top, r->end());
2833 r->print();
2834 }
2835 g1_policy()->record_before_bytes(r_used);
2836 }
2837 }
2839 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
2840 assert(Thread::current()->is_VM_thread() ||
2841 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
2842 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
2843 "Precondition.");
2844 hr->set_is_gc_alloc_region(true);
2845 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
2846 _gc_alloc_region_list = hr;
2847 }
2849 #ifdef G1_DEBUG
2850 class FindGCAllocRegion: public HeapRegionClosure {
2851 public:
2852 bool doHeapRegion(HeapRegion* r) {
2853 if (r->is_gc_alloc_region()) {
2854 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
2855 r->hrs_index(), r->bottom());
2856 }
2857 return false;
2858 }
2859 };
2860 #endif // G1_DEBUG
2862 void G1CollectedHeap::forget_alloc_region_list() {
2863 assert(Thread::current()->is_VM_thread(), "Precondition");
2864 while (_gc_alloc_region_list != NULL) {
2865 HeapRegion* r = _gc_alloc_region_list;
2866 assert(r->is_gc_alloc_region(), "Invariant.");
2867 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
2868 // newly allocated data in order to be able to apply deferred updates
2869 // before the GC is done for verification purposes (i.e to allow
2870 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
2871 // collection.
2872 r->ContiguousSpace::set_saved_mark();
2873 _gc_alloc_region_list = r->next_gc_alloc_region();
2874 r->set_next_gc_alloc_region(NULL);
2875 r->set_is_gc_alloc_region(false);
2876 if (r->is_survivor()) {
2877 if (r->is_empty()) {
2878 r->set_not_young();
2879 } else {
2880 _young_list->add_survivor_region(r);
2881 }
2882 }
2883 if (r->is_empty()) {
2884 ++_free_regions;
2885 }
2886 }
2887 #ifdef G1_DEBUG
2888 FindGCAllocRegion fa;
2889 heap_region_iterate(&fa);
2890 #endif // G1_DEBUG
2891 }
2894 bool G1CollectedHeap::check_gc_alloc_regions() {
2895 // TODO: allocation regions check
2896 return true;
2897 }
2899 void G1CollectedHeap::get_gc_alloc_regions() {
2900 // First, let's check that the GC alloc region list is empty (it should)
2901 assert(_gc_alloc_region_list == NULL, "invariant");
2903 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2904 assert(_gc_alloc_regions[ap] == NULL, "invariant");
2906 // Create new GC alloc regions.
2907 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
2908 _retained_gc_alloc_regions[ap] = NULL;
2910 if (alloc_region != NULL) {
2911 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
2913 // let's make sure that the GC alloc region is not tagged as such
2914 // outside a GC operation
2915 assert(!alloc_region->is_gc_alloc_region(), "sanity");
2917 if (alloc_region->in_collection_set() ||
2918 alloc_region->top() == alloc_region->end() ||
2919 alloc_region->top() == alloc_region->bottom()) {
2920 // we will discard the current GC alloc region if it's in the
2921 // collection set (it can happen!), if it's already full (no
2922 // point in using it), or if it's empty (this means that it
2923 // was emptied during a cleanup and it should be on the free
2924 // list now).
2926 alloc_region = NULL;
2927 }
2928 }
2930 if (alloc_region == NULL) {
2931 // we will get a new GC alloc region
2932 alloc_region = newAllocRegionWithExpansion(ap, 0);
2933 }
2935 if (alloc_region != NULL) {
2936 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
2937 set_gc_alloc_region(ap, alloc_region);
2938 }
2940 assert(_gc_alloc_regions[ap] == NULL ||
2941 _gc_alloc_regions[ap]->is_gc_alloc_region(),
2942 "the GC alloc region should be tagged as such");
2943 assert(_gc_alloc_regions[ap] == NULL ||
2944 _gc_alloc_regions[ap] == _gc_alloc_region_list,
2945 "the GC alloc region should be the same as the GC alloc list head");
2946 }
2947 // Set alternative regions for allocation purposes that have reached
2948 // their limit.
2949 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2950 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
2951 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
2952 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
2953 }
2954 }
2955 assert(check_gc_alloc_regions(), "alloc regions messed up");
2956 }
2958 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
2959 // We keep a separate list of all regions that have been alloc regions in
2960 // the current collection pause. Forget that now. This method will
2961 // untag the GC alloc regions and tear down the GC alloc region
2962 // list. It's desirable that no regions are tagged as GC alloc
2963 // outside GCs.
2964 forget_alloc_region_list();
2966 // The current alloc regions contain objs that have survived
2967 // collection. Make them no longer GC alloc regions.
2968 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2969 HeapRegion* r = _gc_alloc_regions[ap];
2970 _retained_gc_alloc_regions[ap] = NULL;
2972 if (r != NULL) {
2973 // we retain nothing on _gc_alloc_regions between GCs
2974 set_gc_alloc_region(ap, NULL);
2975 _gc_alloc_region_counts[ap] = 0;
2977 if (r->is_empty()) {
2978 // we didn't actually allocate anything in it; let's just put
2979 // it on the free list
2980 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
2981 r->set_zero_fill_complete();
2982 put_free_region_on_list_locked(r);
2983 } else if (_retain_gc_alloc_region[ap] && !totally) {
2984 // retain it so that we can use it at the beginning of the next GC
2985 _retained_gc_alloc_regions[ap] = r;
2986 }
2987 }
2988 }
2989 }
2991 #ifndef PRODUCT
2992 // Useful for debugging
2994 void G1CollectedHeap::print_gc_alloc_regions() {
2995 gclog_or_tty->print_cr("GC alloc regions");
2996 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2997 HeapRegion* r = _gc_alloc_regions[ap];
2998 if (r == NULL) {
2999 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
3000 } else {
3001 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
3002 ap, r->bottom(), r->used());
3003 }
3004 }
3005 }
3006 #endif // PRODUCT
3008 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3009 _drain_in_progress = false;
3010 set_evac_failure_closure(cl);
3011 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3012 }
3014 void G1CollectedHeap::finalize_for_evac_failure() {
3015 assert(_evac_failure_scan_stack != NULL &&
3016 _evac_failure_scan_stack->length() == 0,
3017 "Postcondition");
3018 assert(!_drain_in_progress, "Postcondition");
3019 // Don't have to delete, since the scan stack is a resource object.
3020 _evac_failure_scan_stack = NULL;
3021 }
3025 // *** Sequential G1 Evacuation
3027 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
3028 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3029 // let the caller handle alloc failure
3030 if (alloc_region == NULL) return NULL;
3031 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
3032 "Either the object is humongous or the region isn't");
3033 HeapWord* block = alloc_region->allocate(word_size);
3034 if (block == NULL) {
3035 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
3036 }
3037 return block;
3038 }
3040 class G1IsAliveClosure: public BoolObjectClosure {
3041 G1CollectedHeap* _g1;
3042 public:
3043 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3044 void do_object(oop p) { assert(false, "Do not call."); }
3045 bool do_object_b(oop p) {
3046 // It is reachable if it is outside the collection set, or is inside
3047 // and forwarded.
3049 #ifdef G1_DEBUG
3050 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3051 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3052 !_g1->obj_in_cs(p) || p->is_forwarded());
3053 #endif // G1_DEBUG
3055 return !_g1->obj_in_cs(p) || p->is_forwarded();
3056 }
3057 };
3059 class G1KeepAliveClosure: public OopClosure {
3060 G1CollectedHeap* _g1;
3061 public:
3062 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3063 void do_oop(narrowOop* p) {
3064 guarantee(false, "NYI");
3065 }
3066 void do_oop(oop* p) {
3067 oop obj = *p;
3068 #ifdef G1_DEBUG
3069 if (PrintGC && Verbose) {
3070 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3071 p, (void*) obj, (void*) *p);
3072 }
3073 #endif // G1_DEBUG
3075 if (_g1->obj_in_cs(obj)) {
3076 assert( obj->is_forwarded(), "invariant" );
3077 *p = obj->forwardee();
3079 #ifdef G1_DEBUG
3080 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3081 (void*) obj, (void*) *p);
3082 #endif // G1_DEBUG
3083 }
3084 }
3085 };
3087 class UpdateRSetImmediate : public OopsInHeapRegionClosure {
3088 private:
3089 G1CollectedHeap* _g1;
3090 G1RemSet* _g1_rem_set;
3091 public:
3092 UpdateRSetImmediate(G1CollectedHeap* g1) :
3093 _g1(g1), _g1_rem_set(g1->g1_rem_set()) {}
3095 void do_oop(narrowOop* p) {
3096 guarantee(false, "NYI");
3097 }
3098 void do_oop(oop* p) {
3099 assert(_from->is_in_reserved(p), "paranoia");
3100 if (*p != NULL && !_from->is_survivor()) {
3101 _g1_rem_set->par_write_ref(_from, p, 0);
3102 }
3103 }
3104 };
3106 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3107 private:
3108 G1CollectedHeap* _g1;
3109 DirtyCardQueue *_dcq;
3110 CardTableModRefBS* _ct_bs;
3112 public:
3113 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3114 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3116 void do_oop(narrowOop* p) {
3117 guarantee(false, "NYI");
3118 }
3119 void do_oop(oop* p) {
3120 assert(_from->is_in_reserved(p), "paranoia");
3121 if (!_from->is_in_reserved(*p) && !_from->is_survivor()) {
3122 size_t card_index = _ct_bs->index_for(p);
3123 if (_ct_bs->mark_card_deferred(card_index)) {
3124 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3125 }
3126 }
3127 }
3128 };
3132 class RemoveSelfPointerClosure: public ObjectClosure {
3133 private:
3134 G1CollectedHeap* _g1;
3135 ConcurrentMark* _cm;
3136 HeapRegion* _hr;
3137 size_t _prev_marked_bytes;
3138 size_t _next_marked_bytes;
3139 OopsInHeapRegionClosure *_cl;
3140 public:
3141 RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
3142 _g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3143 _next_marked_bytes(0), _cl(cl) {}
3145 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3146 size_t next_marked_bytes() { return _next_marked_bytes; }
3148 // The original idea here was to coalesce evacuated and dead objects.
3149 // However that caused complications with the block offset table (BOT).
3150 // In particular if there were two TLABs, one of them partially refined.
3151 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3152 // The BOT entries of the unrefined part of TLAB_2 point to the start
3153 // of TLAB_2. If the last object of the TLAB_1 and the first object
3154 // of TLAB_2 are coalesced, then the cards of the unrefined part
3155 // would point into middle of the filler object.
3156 //
3157 // The current approach is to not coalesce and leave the BOT contents intact.
3158 void do_object(oop obj) {
3159 if (obj->is_forwarded() && obj->forwardee() == obj) {
3160 // The object failed to move.
3161 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3162 _cm->markPrev(obj);
3163 assert(_cm->isPrevMarked(obj), "Should be marked!");
3164 _prev_marked_bytes += (obj->size() * HeapWordSize);
3165 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3166 _cm->markAndGrayObjectIfNecessary(obj);
3167 }
3168 obj->set_mark(markOopDesc::prototype());
3169 // While we were processing RSet buffers during the
3170 // collection, we actually didn't scan any cards on the
3171 // collection set, since we didn't want to update remebered
3172 // sets with entries that point into the collection set, given
3173 // that live objects fromthe collection set are about to move
3174 // and such entries will be stale very soon. This change also
3175 // dealt with a reliability issue which involved scanning a
3176 // card in the collection set and coming across an array that
3177 // was being chunked and looking malformed. The problem is
3178 // that, if evacuation fails, we might have remembered set
3179 // entries missing given that we skipped cards on the
3180 // collection set. So, we'll recreate such entries now.
3181 obj->oop_iterate(_cl);
3182 assert(_cm->isPrevMarked(obj), "Should be marked!");
3183 } else {
3184 // The object has been either evacuated or is dead. Fill it with a
3185 // dummy object.
3186 MemRegion mr((HeapWord*)obj, obj->size());
3187 CollectedHeap::fill_with_object(mr);
3188 _cm->clearRangeBothMaps(mr);
3189 }
3190 }
3191 };
3193 void G1CollectedHeap::remove_self_forwarding_pointers() {
3194 UpdateRSetImmediate immediate_update(_g1h);
3195 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3196 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3197 OopsInHeapRegionClosure *cl;
3198 if (G1DeferredRSUpdate) {
3199 cl = &deferred_update;
3200 } else {
3201 cl = &immediate_update;
3202 }
3203 HeapRegion* cur = g1_policy()->collection_set();
3204 while (cur != NULL) {
3205 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3207 RemoveSelfPointerClosure rspc(_g1h, cl);
3208 if (cur->evacuation_failed()) {
3209 assert(cur->in_collection_set(), "bad CS");
3210 cl->set_region(cur);
3211 cur->object_iterate(&rspc);
3213 // A number of manipulations to make the TAMS be the current top,
3214 // and the marked bytes be the ones observed in the iteration.
3215 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3216 // The comments below are the postconditions achieved by the
3217 // calls. Note especially the last such condition, which says that
3218 // the count of marked bytes has been properly restored.
3219 cur->note_start_of_marking(false);
3220 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3221 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3222 // _next_marked_bytes == prev_marked_bytes.
3223 cur->note_end_of_marking();
3224 // _prev_top_at_mark_start == top(),
3225 // _prev_marked_bytes == prev_marked_bytes
3226 }
3227 // If there is no mark in progress, we modified the _next variables
3228 // above needlessly, but harmlessly.
3229 if (_g1h->mark_in_progress()) {
3230 cur->note_start_of_marking(false);
3231 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3232 // _next_marked_bytes == next_marked_bytes.
3233 }
3235 // Now make sure the region has the right index in the sorted array.
3236 g1_policy()->note_change_in_marked_bytes(cur);
3237 }
3238 cur = cur->next_in_collection_set();
3239 }
3240 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3242 // Now restore saved marks, if any.
3243 if (_objs_with_preserved_marks != NULL) {
3244 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3245 assert(_objs_with_preserved_marks->length() ==
3246 _preserved_marks_of_objs->length(), "Both or none.");
3247 guarantee(_objs_with_preserved_marks->length() ==
3248 _preserved_marks_of_objs->length(), "Both or none.");
3249 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3250 oop obj = _objs_with_preserved_marks->at(i);
3251 markOop m = _preserved_marks_of_objs->at(i);
3252 obj->set_mark(m);
3253 }
3254 // Delete the preserved marks growable arrays (allocated on the C heap).
3255 delete _objs_with_preserved_marks;
3256 delete _preserved_marks_of_objs;
3257 _objs_with_preserved_marks = NULL;
3258 _preserved_marks_of_objs = NULL;
3259 }
3260 }
3262 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3263 _evac_failure_scan_stack->push(obj);
3264 }
3266 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3267 assert(_evac_failure_scan_stack != NULL, "precondition");
3269 while (_evac_failure_scan_stack->length() > 0) {
3270 oop obj = _evac_failure_scan_stack->pop();
3271 _evac_failure_closure->set_region(heap_region_containing(obj));
3272 obj->oop_iterate_backwards(_evac_failure_closure);
3273 }
3274 }
3276 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3277 markOop m = old->mark();
3278 // forward to self
3279 assert(!old->is_forwarded(), "precondition");
3281 old->forward_to(old);
3282 handle_evacuation_failure_common(old, m);
3283 }
3285 oop
3286 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3287 oop old) {
3288 markOop m = old->mark();
3289 oop forward_ptr = old->forward_to_atomic(old);
3290 if (forward_ptr == NULL) {
3291 // Forward-to-self succeeded.
3292 if (_evac_failure_closure != cl) {
3293 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3294 assert(!_drain_in_progress,
3295 "Should only be true while someone holds the lock.");
3296 // Set the global evac-failure closure to the current thread's.
3297 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3298 set_evac_failure_closure(cl);
3299 // Now do the common part.
3300 handle_evacuation_failure_common(old, m);
3301 // Reset to NULL.
3302 set_evac_failure_closure(NULL);
3303 } else {
3304 // The lock is already held, and this is recursive.
3305 assert(_drain_in_progress, "This should only be the recursive case.");
3306 handle_evacuation_failure_common(old, m);
3307 }
3308 return old;
3309 } else {
3310 // Someone else had a place to copy it.
3311 return forward_ptr;
3312 }
3313 }
3315 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3316 set_evacuation_failed(true);
3318 preserve_mark_if_necessary(old, m);
3320 HeapRegion* r = heap_region_containing(old);
3321 if (!r->evacuation_failed()) {
3322 r->set_evacuation_failed(true);
3323 if (G1TraceRegions) {
3324 gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
3325 "["PTR_FORMAT","PTR_FORMAT")\n",
3326 r, r->bottom(), r->end());
3327 }
3328 }
3330 push_on_evac_failure_scan_stack(old);
3332 if (!_drain_in_progress) {
3333 // prevent recursion in copy_to_survivor_space()
3334 _drain_in_progress = true;
3335 drain_evac_failure_scan_stack();
3336 _drain_in_progress = false;
3337 }
3338 }
3340 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3341 if (m != markOopDesc::prototype()) {
3342 if (_objs_with_preserved_marks == NULL) {
3343 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3344 _objs_with_preserved_marks =
3345 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3346 _preserved_marks_of_objs =
3347 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3348 }
3349 _objs_with_preserved_marks->push(obj);
3350 _preserved_marks_of_objs->push(m);
3351 }
3352 }
3354 // *** Parallel G1 Evacuation
3356 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3357 size_t word_size) {
3358 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3359 // let the caller handle alloc failure
3360 if (alloc_region == NULL) return NULL;
3362 HeapWord* block = alloc_region->par_allocate(word_size);
3363 if (block == NULL) {
3364 MutexLockerEx x(par_alloc_during_gc_lock(),
3365 Mutex::_no_safepoint_check_flag);
3366 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3367 }
3368 return block;
3369 }
3371 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
3372 bool par) {
3373 // Another thread might have obtained alloc_region for the given
3374 // purpose, and might be attempting to allocate in it, and might
3375 // succeed. Therefore, we can't do the "finalization" stuff on the
3376 // region below until we're sure the last allocation has happened.
3377 // We ensure this by allocating the remaining space with a garbage
3378 // object.
3379 if (par) par_allocate_remaining_space(alloc_region);
3380 // Now we can do the post-GC stuff on the region.
3381 alloc_region->note_end_of_copying();
3382 g1_policy()->record_after_bytes(alloc_region->used());
3383 }
3385 HeapWord*
3386 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3387 HeapRegion* alloc_region,
3388 bool par,
3389 size_t word_size) {
3390 HeapWord* block = NULL;
3391 // In the parallel case, a previous thread to obtain the lock may have
3392 // already assigned a new gc_alloc_region.
3393 if (alloc_region != _gc_alloc_regions[purpose]) {
3394 assert(par, "But should only happen in parallel case.");
3395 alloc_region = _gc_alloc_regions[purpose];
3396 if (alloc_region == NULL) return NULL;
3397 block = alloc_region->par_allocate(word_size);
3398 if (block != NULL) return block;
3399 // Otherwise, continue; this new region is empty, too.
3400 }
3401 assert(alloc_region != NULL, "We better have an allocation region");
3402 retire_alloc_region(alloc_region, par);
3404 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3405 // Cannot allocate more regions for the given purpose.
3406 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3407 // Is there an alternative?
3408 if (purpose != alt_purpose) {
3409 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3410 // Has not the alternative region been aliased?
3411 if (alloc_region != alt_region && alt_region != NULL) {
3412 // Try to allocate in the alternative region.
3413 if (par) {
3414 block = alt_region->par_allocate(word_size);
3415 } else {
3416 block = alt_region->allocate(word_size);
3417 }
3418 // Make an alias.
3419 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3420 if (block != NULL) {
3421 return block;
3422 }
3423 retire_alloc_region(alt_region, par);
3424 }
3425 // Both the allocation region and the alternative one are full
3426 // and aliased, replace them with a new allocation region.
3427 purpose = alt_purpose;
3428 } else {
3429 set_gc_alloc_region(purpose, NULL);
3430 return NULL;
3431 }
3432 }
3434 // Now allocate a new region for allocation.
3435 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3437 // let the caller handle alloc failure
3438 if (alloc_region != NULL) {
3440 assert(check_gc_alloc_regions(), "alloc regions messed up");
3441 assert(alloc_region->saved_mark_at_top(),
3442 "Mark should have been saved already.");
3443 // We used to assert that the region was zero-filled here, but no
3444 // longer.
3446 // This must be done last: once it's installed, other regions may
3447 // allocate in it (without holding the lock.)
3448 set_gc_alloc_region(purpose, alloc_region);
3450 if (par) {
3451 block = alloc_region->par_allocate(word_size);
3452 } else {
3453 block = alloc_region->allocate(word_size);
3454 }
3455 // Caller handles alloc failure.
3456 } else {
3457 // This sets other apis using the same old alloc region to NULL, also.
3458 set_gc_alloc_region(purpose, NULL);
3459 }
3460 return block; // May be NULL.
3461 }
3463 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3464 HeapWord* block = NULL;
3465 size_t free_words;
3466 do {
3467 free_words = r->free()/HeapWordSize;
3468 // If there's too little space, no one can allocate, so we're done.
3469 if (free_words < (size_t)oopDesc::header_size()) return;
3470 // Otherwise, try to claim it.
3471 block = r->par_allocate(free_words);
3472 } while (block == NULL);
3473 fill_with_object(block, free_words);
3474 }
3476 #define use_local_bitmaps 1
3477 #define verify_local_bitmaps 0
3479 #ifndef PRODUCT
3481 class GCLabBitMap;
3482 class GCLabBitMapClosure: public BitMapClosure {
3483 private:
3484 ConcurrentMark* _cm;
3485 GCLabBitMap* _bitmap;
3487 public:
3488 GCLabBitMapClosure(ConcurrentMark* cm,
3489 GCLabBitMap* bitmap) {
3490 _cm = cm;
3491 _bitmap = bitmap;
3492 }
3494 virtual bool do_bit(size_t offset);
3495 };
3497 #endif // PRODUCT
3499 #define oop_buffer_length 256
3501 class GCLabBitMap: public BitMap {
3502 private:
3503 ConcurrentMark* _cm;
3505 int _shifter;
3506 size_t _bitmap_word_covers_words;
3508 // beginning of the heap
3509 HeapWord* _heap_start;
3511 // this is the actual start of the GCLab
3512 HeapWord* _real_start_word;
3514 // this is the actual end of the GCLab
3515 HeapWord* _real_end_word;
3517 // this is the first word, possibly located before the actual start
3518 // of the GCLab, that corresponds to the first bit of the bitmap
3519 HeapWord* _start_word;
3521 // size of a GCLab in words
3522 size_t _gclab_word_size;
3524 static int shifter() {
3525 return MinObjAlignment - 1;
3526 }
3528 // how many heap words does a single bitmap word corresponds to?
3529 static size_t bitmap_word_covers_words() {
3530 return BitsPerWord << shifter();
3531 }
3533 static size_t gclab_word_size() {
3534 return ParallelGCG1AllocBufferSize / HeapWordSize;
3535 }
3537 static size_t bitmap_size_in_bits() {
3538 size_t bits_in_bitmap = gclab_word_size() >> shifter();
3539 // We are going to ensure that the beginning of a word in this
3540 // bitmap also corresponds to the beginning of a word in the
3541 // global marking bitmap. To handle the case where a GCLab
3542 // starts from the middle of the bitmap, we need to add enough
3543 // space (i.e. up to a bitmap word) to ensure that we have
3544 // enough bits in the bitmap.
3545 return bits_in_bitmap + BitsPerWord - 1;
3546 }
3547 public:
3548 GCLabBitMap(HeapWord* heap_start)
3549 : BitMap(bitmap_size_in_bits()),
3550 _cm(G1CollectedHeap::heap()->concurrent_mark()),
3551 _shifter(shifter()),
3552 _bitmap_word_covers_words(bitmap_word_covers_words()),
3553 _heap_start(heap_start),
3554 _gclab_word_size(gclab_word_size()),
3555 _real_start_word(NULL),
3556 _real_end_word(NULL),
3557 _start_word(NULL)
3558 {
3559 guarantee( size_in_words() >= bitmap_size_in_words(),
3560 "just making sure");
3561 }
3563 inline unsigned heapWordToOffset(HeapWord* addr) {
3564 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
3565 assert(offset < size(), "offset should be within bounds");
3566 return offset;
3567 }
3569 inline HeapWord* offsetToHeapWord(size_t offset) {
3570 HeapWord* addr = _start_word + (offset << _shifter);
3571 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
3572 return addr;
3573 }
3575 bool fields_well_formed() {
3576 bool ret1 = (_real_start_word == NULL) &&
3577 (_real_end_word == NULL) &&
3578 (_start_word == NULL);
3579 if (ret1)
3580 return true;
3582 bool ret2 = _real_start_word >= _start_word &&
3583 _start_word < _real_end_word &&
3584 (_real_start_word + _gclab_word_size) == _real_end_word &&
3585 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
3586 > _real_end_word;
3587 return ret2;
3588 }
3590 inline bool mark(HeapWord* addr) {
3591 guarantee(use_local_bitmaps, "invariant");
3592 assert(fields_well_formed(), "invariant");
3594 if (addr >= _real_start_word && addr < _real_end_word) {
3595 assert(!isMarked(addr), "should not have already been marked");
3597 // first mark it on the bitmap
3598 at_put(heapWordToOffset(addr), true);
3600 return true;
3601 } else {
3602 return false;
3603 }
3604 }
3606 inline bool isMarked(HeapWord* addr) {
3607 guarantee(use_local_bitmaps, "invariant");
3608 assert(fields_well_formed(), "invariant");
3610 return at(heapWordToOffset(addr));
3611 }
3613 void set_buffer(HeapWord* start) {
3614 guarantee(use_local_bitmaps, "invariant");
3615 clear();
3617 assert(start != NULL, "invariant");
3618 _real_start_word = start;
3619 _real_end_word = start + _gclab_word_size;
3621 size_t diff =
3622 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
3623 _start_word = start - diff;
3625 assert(fields_well_formed(), "invariant");
3626 }
3628 #ifndef PRODUCT
3629 void verify() {
3630 // verify that the marks have been propagated
3631 GCLabBitMapClosure cl(_cm, this);
3632 iterate(&cl);
3633 }
3634 #endif // PRODUCT
3636 void retire() {
3637 guarantee(use_local_bitmaps, "invariant");
3638 assert(fields_well_formed(), "invariant");
3640 if (_start_word != NULL) {
3641 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
3643 // this means that the bitmap was set up for the GCLab
3644 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
3646 mark_bitmap->mostly_disjoint_range_union(this,
3647 0, // always start from the start of the bitmap
3648 _start_word,
3649 size_in_words());
3650 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
3652 #ifndef PRODUCT
3653 if (use_local_bitmaps && verify_local_bitmaps)
3654 verify();
3655 #endif // PRODUCT
3656 } else {
3657 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
3658 }
3659 }
3661 static size_t bitmap_size_in_words() {
3662 return (bitmap_size_in_bits() + BitsPerWord - 1) / BitsPerWord;
3663 }
3664 };
3666 #ifndef PRODUCT
3668 bool GCLabBitMapClosure::do_bit(size_t offset) {
3669 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3670 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3671 return true;
3672 }
3674 #endif // PRODUCT
3676 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
3677 private:
3678 bool _retired;
3679 bool _during_marking;
3680 GCLabBitMap _bitmap;
3682 public:
3683 G1ParGCAllocBuffer() :
3684 ParGCAllocBuffer(ParallelGCG1AllocBufferSize / HeapWordSize),
3685 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
3686 _bitmap(G1CollectedHeap::heap()->reserved_region().start()),
3687 _retired(false)
3688 { }
3690 inline bool mark(HeapWord* addr) {
3691 guarantee(use_local_bitmaps, "invariant");
3692 assert(_during_marking, "invariant");
3693 return _bitmap.mark(addr);
3694 }
3696 inline void set_buf(HeapWord* buf) {
3697 if (use_local_bitmaps && _during_marking)
3698 _bitmap.set_buffer(buf);
3699 ParGCAllocBuffer::set_buf(buf);
3700 _retired = false;
3701 }
3703 inline void retire(bool end_of_gc, bool retain) {
3704 if (_retired)
3705 return;
3706 if (use_local_bitmaps && _during_marking) {
3707 _bitmap.retire();
3708 }
3709 ParGCAllocBuffer::retire(end_of_gc, retain);
3710 _retired = true;
3711 }
3712 };
3715 class G1ParScanThreadState : public StackObj {
3716 protected:
3717 G1CollectedHeap* _g1h;
3718 RefToScanQueue* _refs;
3719 DirtyCardQueue _dcq;
3720 CardTableModRefBS* _ct_bs;
3721 G1RemSet* _g1_rem;
3723 typedef GrowableArray<oop*> OverflowQueue;
3724 OverflowQueue* _overflowed_refs;
3726 G1ParGCAllocBuffer _alloc_buffers[GCAllocPurposeCount];
3727 ageTable _age_table;
3729 size_t _alloc_buffer_waste;
3730 size_t _undo_waste;
3732 OopsInHeapRegionClosure* _evac_failure_cl;
3733 G1ParScanHeapEvacClosure* _evac_cl;
3734 G1ParScanPartialArrayClosure* _partial_scan_cl;
3736 int _hash_seed;
3737 int _queue_num;
3739 int _term_attempts;
3740 #if G1_DETAILED_STATS
3741 int _pushes, _pops, _steals, _steal_attempts;
3742 int _overflow_pushes;
3743 #endif
3745 double _start;
3746 double _start_strong_roots;
3747 double _strong_roots_time;
3748 double _start_term;
3749 double _term_time;
3751 // Map from young-age-index (0 == not young, 1 is youngest) to
3752 // surviving words. base is what we get back from the malloc call
3753 size_t* _surviving_young_words_base;
3754 // this points into the array, as we use the first few entries for padding
3755 size_t* _surviving_young_words;
3757 #define PADDING_ELEM_NUM (64 / sizeof(size_t))
3759 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
3761 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
3763 DirtyCardQueue& dirty_card_queue() { return _dcq; }
3764 CardTableModRefBS* ctbs() { return _ct_bs; }
3766 void immediate_rs_update(HeapRegion* from, oop* p, int tid) {
3767 if (!from->is_survivor()) {
3768 _g1_rem->par_write_ref(from, p, tid);
3769 }
3770 }
3772 void deferred_rs_update(HeapRegion* from, oop* p, int tid) {
3773 // If the new value of the field points to the same region or
3774 // is the to-space, we don't need to include it in the Rset updates.
3775 if (!from->is_in_reserved(*p) && !from->is_survivor()) {
3776 size_t card_index = ctbs()->index_for(p);
3777 // If the card hasn't been added to the buffer, do it.
3778 if (ctbs()->mark_card_deferred(card_index)) {
3779 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
3780 }
3781 }
3782 }
3784 public:
3785 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3786 : _g1h(g1h),
3787 _refs(g1h->task_queue(queue_num)),
3788 _dcq(&g1h->dirty_card_queue_set()),
3789 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
3790 _g1_rem(g1h->g1_rem_set()),
3791 _hash_seed(17), _queue_num(queue_num),
3792 _term_attempts(0),
3793 _age_table(false),
3794 #if G1_DETAILED_STATS
3795 _pushes(0), _pops(0), _steals(0),
3796 _steal_attempts(0), _overflow_pushes(0),
3797 #endif
3798 _strong_roots_time(0), _term_time(0),
3799 _alloc_buffer_waste(0), _undo_waste(0)
3800 {
3801 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3802 // we "sacrifice" entry 0 to keep track of surviving bytes for
3803 // non-young regions (where the age is -1)
3804 // We also add a few elements at the beginning and at the end in
3805 // an attempt to eliminate cache contention
3806 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3807 size_t array_length = PADDING_ELEM_NUM +
3808 real_length +
3809 PADDING_ELEM_NUM;
3810 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3811 if (_surviving_young_words_base == NULL)
3812 vm_exit_out_of_memory(array_length * sizeof(size_t),
3813 "Not enough space for young surv histo.");
3814 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3815 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3817 _overflowed_refs = new OverflowQueue(10);
3819 _start = os::elapsedTime();
3820 }
3822 ~G1ParScanThreadState() {
3823 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
3824 }
3826 RefToScanQueue* refs() { return _refs; }
3827 OverflowQueue* overflowed_refs() { return _overflowed_refs; }
3828 ageTable* age_table() { return &_age_table; }
3830 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
3831 return &_alloc_buffers[purpose];
3832 }
3834 size_t alloc_buffer_waste() { return _alloc_buffer_waste; }
3835 size_t undo_waste() { return _undo_waste; }
3837 void push_on_queue(oop* ref) {
3838 assert(ref != NULL, "invariant");
3839 assert(has_partial_array_mask(ref) || _g1h->obj_in_cs(*ref), "invariant");
3841 if (!refs()->push(ref)) {
3842 overflowed_refs()->push(ref);
3843 IF_G1_DETAILED_STATS(note_overflow_push());
3844 } else {
3845 IF_G1_DETAILED_STATS(note_push());
3846 }
3847 }
3849 void pop_from_queue(oop*& ref) {
3850 if (!refs()->pop_local(ref)) {
3851 ref = NULL;
3852 } else {
3853 assert(ref != NULL, "invariant");
3854 assert(has_partial_array_mask(ref) || _g1h->obj_in_cs(*ref),
3855 "invariant");
3857 IF_G1_DETAILED_STATS(note_pop());
3858 }
3859 }
3861 void pop_from_overflow_queue(oop*& ref) {
3862 ref = overflowed_refs()->pop();
3863 }
3865 int refs_to_scan() { return refs()->size(); }
3866 int overflowed_refs_to_scan() { return overflowed_refs()->length(); }
3868 void update_rs(HeapRegion* from, oop* p, int tid) {
3869 if (G1DeferredRSUpdate) {
3870 deferred_rs_update(from, p, tid);
3871 } else {
3872 immediate_rs_update(from, p, tid);
3873 }
3874 }
3876 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
3878 HeapWord* obj = NULL;
3879 if (word_sz * 100 <
3880 (size_t)(ParallelGCG1AllocBufferSize / HeapWordSize) *
3881 ParallelGCBufferWastePct) {
3882 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
3883 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
3884 alloc_buf->retire(false, false);
3886 HeapWord* buf =
3887 _g1h->par_allocate_during_gc(purpose, ParallelGCG1AllocBufferSize / HeapWordSize);
3888 if (buf == NULL) return NULL; // Let caller handle allocation failure.
3889 // Otherwise.
3890 alloc_buf->set_buf(buf);
3892 obj = alloc_buf->allocate(word_sz);
3893 assert(obj != NULL, "buffer was definitely big enough...");
3894 } else {
3895 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
3896 }
3897 return obj;
3898 }
3900 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
3901 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
3902 if (obj != NULL) return obj;
3903 return allocate_slow(purpose, word_sz);
3904 }
3906 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
3907 if (alloc_buffer(purpose)->contains(obj)) {
3908 guarantee(alloc_buffer(purpose)->contains(obj + word_sz - 1),
3909 "should contain whole object");
3910 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
3911 } else {
3912 CollectedHeap::fill_with_object(obj, word_sz);
3913 add_to_undo_waste(word_sz);
3914 }
3915 }
3917 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
3918 _evac_failure_cl = evac_failure_cl;
3919 }
3920 OopsInHeapRegionClosure* evac_failure_closure() {
3921 return _evac_failure_cl;
3922 }
3924 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
3925 _evac_cl = evac_cl;
3926 }
3928 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
3929 _partial_scan_cl = partial_scan_cl;
3930 }
3932 int* hash_seed() { return &_hash_seed; }
3933 int queue_num() { return _queue_num; }
3935 int term_attempts() { return _term_attempts; }
3936 void note_term_attempt() { _term_attempts++; }
3938 #if G1_DETAILED_STATS
3939 int pushes() { return _pushes; }
3940 int pops() { return _pops; }
3941 int steals() { return _steals; }
3942 int steal_attempts() { return _steal_attempts; }
3943 int overflow_pushes() { return _overflow_pushes; }
3945 void note_push() { _pushes++; }
3946 void note_pop() { _pops++; }
3947 void note_steal() { _steals++; }
3948 void note_steal_attempt() { _steal_attempts++; }
3949 void note_overflow_push() { _overflow_pushes++; }
3950 #endif
3952 void start_strong_roots() {
3953 _start_strong_roots = os::elapsedTime();
3954 }
3955 void end_strong_roots() {
3956 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
3957 }
3958 double strong_roots_time() { return _strong_roots_time; }
3960 void start_term_time() {
3961 note_term_attempt();
3962 _start_term = os::elapsedTime();
3963 }
3964 void end_term_time() {
3965 _term_time += (os::elapsedTime() - _start_term);
3966 }
3967 double term_time() { return _term_time; }
3969 double elapsed() {
3970 return os::elapsedTime() - _start;
3971 }
3973 size_t* surviving_young_words() {
3974 // We add on to hide entry 0 which accumulates surviving words for
3975 // age -1 regions (i.e. non-young ones)
3976 return _surviving_young_words;
3977 }
3979 void retire_alloc_buffers() {
3980 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3981 size_t waste = _alloc_buffers[ap].words_remaining();
3982 add_to_alloc_buffer_waste(waste);
3983 _alloc_buffers[ap].retire(true, false);
3984 }
3985 }
3987 private:
3988 void deal_with_reference(oop* ref_to_scan) {
3989 if (has_partial_array_mask(ref_to_scan)) {
3990 _partial_scan_cl->do_oop_nv(ref_to_scan);
3991 } else {
3992 // Note: we can use "raw" versions of "region_containing" because
3993 // "obj_to_scan" is definitely in the heap, and is not in a
3994 // humongous region.
3995 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
3996 _evac_cl->set_region(r);
3997 _evac_cl->do_oop_nv(ref_to_scan);
3998 }
3999 }
4001 public:
4002 void trim_queue() {
4003 // I've replicated the loop twice, first to drain the overflow
4004 // queue, second to drain the task queue. This is better than
4005 // having a single loop, which checks both conditions and, inside
4006 // it, either pops the overflow queue or the task queue, as each
4007 // loop is tighter. Also, the decision to drain the overflow queue
4008 // first is not arbitrary, as the overflow queue is not visible
4009 // to the other workers, whereas the task queue is. So, we want to
4010 // drain the "invisible" entries first, while allowing the other
4011 // workers to potentially steal the "visible" entries.
4013 while (refs_to_scan() > 0 || overflowed_refs_to_scan() > 0) {
4014 while (overflowed_refs_to_scan() > 0) {
4015 oop *ref_to_scan = NULL;
4016 pop_from_overflow_queue(ref_to_scan);
4017 assert(ref_to_scan != NULL, "invariant");
4018 // We shouldn't have pushed it on the queue if it was not
4019 // pointing into the CSet.
4020 assert(ref_to_scan != NULL, "sanity");
4021 assert(has_partial_array_mask(ref_to_scan) ||
4022 _g1h->obj_in_cs(*ref_to_scan), "sanity");
4024 deal_with_reference(ref_to_scan);
4025 }
4027 while (refs_to_scan() > 0) {
4028 oop *ref_to_scan = NULL;
4029 pop_from_queue(ref_to_scan);
4031 if (ref_to_scan != NULL) {
4032 // We shouldn't have pushed it on the queue if it was not
4033 // pointing into the CSet.
4034 assert(has_partial_array_mask(ref_to_scan) ||
4035 _g1h->obj_in_cs(*ref_to_scan), "sanity");
4037 deal_with_reference(ref_to_scan);
4038 }
4039 }
4040 }
4041 }
4042 };
4044 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4045 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4046 _par_scan_state(par_scan_state) { }
4048 // This closure is applied to the fields of the objects that have just been copied.
4049 // Should probably be made inline and moved in g1OopClosures.inline.hpp.
4050 void G1ParScanClosure::do_oop_nv(oop* p) {
4051 oop obj = *p;
4053 if (obj != NULL) {
4054 if (_g1->in_cset_fast_test(obj)) {
4055 // We're not going to even bother checking whether the object is
4056 // already forwarded or not, as this usually causes an immediate
4057 // stall. We'll try to prefetch the object (for write, given that
4058 // we might need to install the forwarding reference) and we'll
4059 // get back to it when pop it from the queue
4060 Prefetch::write(obj->mark_addr(), 0);
4061 Prefetch::read(obj->mark_addr(), (HeapWordSize*2));
4063 // slightly paranoid test; I'm trying to catch potential
4064 // problems before we go into push_on_queue to know where the
4065 // problem is coming from
4066 assert(obj == *p, "the value of *p should not have changed");
4067 _par_scan_state->push_on_queue(p);
4068 } else {
4069 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4070 }
4071 }
4072 }
4074 void G1ParCopyHelper::mark_forwardee(oop* p) {
4075 // This is called _after_ do_oop_work has been called, hence after
4076 // the object has been relocated to its new location and *p points
4077 // to its new location.
4079 oop thisOop = *p;
4080 if (thisOop != NULL) {
4081 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(thisOop)),
4082 "shouldn't still be in the CSet if evacuation didn't fail.");
4083 HeapWord* addr = (HeapWord*)thisOop;
4084 if (_g1->is_in_g1_reserved(addr))
4085 _cm->grayRoot(oop(addr));
4086 }
4087 }
4089 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
4090 size_t word_sz = old->size();
4091 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4092 // +1 to make the -1 indexes valid...
4093 int young_index = from_region->young_index_in_cset()+1;
4094 assert( (from_region->is_young() && young_index > 0) ||
4095 (!from_region->is_young() && young_index == 0), "invariant" );
4096 G1CollectorPolicy* g1p = _g1->g1_policy();
4097 markOop m = old->mark();
4098 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4099 : m->age();
4100 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4101 word_sz);
4102 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4103 oop obj = oop(obj_ptr);
4105 if (obj_ptr == NULL) {
4106 // This will either forward-to-self, or detect that someone else has
4107 // installed a forwarding pointer.
4108 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4109 return _g1->handle_evacuation_failure_par(cl, old);
4110 }
4112 // We're going to allocate linearly, so might as well prefetch ahead.
4113 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4115 oop forward_ptr = old->forward_to_atomic(obj);
4116 if (forward_ptr == NULL) {
4117 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4118 if (g1p->track_object_age(alloc_purpose)) {
4119 // We could simply do obj->incr_age(). However, this causes a
4120 // performance issue. obj->incr_age() will first check whether
4121 // the object has a displaced mark by checking its mark word;
4122 // getting the mark word from the new location of the object
4123 // stalls. So, given that we already have the mark word and we
4124 // are about to install it anyway, it's better to increase the
4125 // age on the mark word, when the object does not have a
4126 // displaced mark word. We're not expecting many objects to have
4127 // a displaced marked word, so that case is not optimized
4128 // further (it could be...) and we simply call obj->incr_age().
4130 if (m->has_displaced_mark_helper()) {
4131 // in this case, we have to install the mark word first,
4132 // otherwise obj looks to be forwarded (the old mark word,
4133 // which contains the forward pointer, was copied)
4134 obj->set_mark(m);
4135 obj->incr_age();
4136 } else {
4137 m = m->incr_age();
4138 obj->set_mark(m);
4139 }
4140 _par_scan_state->age_table()->add(obj, word_sz);
4141 } else {
4142 obj->set_mark(m);
4143 }
4145 // preserve "next" mark bit
4146 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
4147 if (!use_local_bitmaps ||
4148 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4149 // if we couldn't mark it on the local bitmap (this happens when
4150 // the object was not allocated in the GCLab), we have to bite
4151 // the bullet and do the standard parallel mark
4152 _cm->markAndGrayObjectIfNecessary(obj);
4153 }
4154 #if 1
4155 if (_g1->isMarkedNext(old)) {
4156 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4157 }
4158 #endif
4159 }
4161 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4162 surv_young_words[young_index] += word_sz;
4164 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4165 arrayOop(old)->set_length(0);
4166 _par_scan_state->push_on_queue(set_partial_array_mask(old));
4167 } else {
4168 // No point in using the slower heap_region_containing() method,
4169 // given that we know obj is in the heap.
4170 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4171 obj->oop_iterate_backwards(_scanner);
4172 }
4173 } else {
4174 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4175 obj = forward_ptr;
4176 }
4177 return obj;
4178 }
4180 template<bool do_gen_barrier, G1Barrier barrier,
4181 bool do_mark_forwardee, bool skip_cset_test>
4182 void G1ParCopyClosure<do_gen_barrier, barrier,
4183 do_mark_forwardee, skip_cset_test>::do_oop_work(oop* p) {
4184 oop obj = *p;
4185 assert(barrier != G1BarrierRS || obj != NULL,
4186 "Precondition: G1BarrierRS implies obj is nonNull");
4188 // The only time we skip the cset test is when we're scanning
4189 // references popped from the queue. And we only push on the queue
4190 // references that we know point into the cset, so no point in
4191 // checking again. But we'll leave an assert here for peace of mind.
4192 assert(!skip_cset_test || _g1->obj_in_cs(obj), "invariant");
4194 // here the null check is implicit in the cset_fast_test() test
4195 if (skip_cset_test || _g1->in_cset_fast_test(obj)) {
4196 #if G1_REM_SET_LOGGING
4197 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
4198 "into CS.", p, (void*) obj);
4199 #endif
4200 if (obj->is_forwarded()) {
4201 *p = obj->forwardee();
4202 } else {
4203 *p = copy_to_survivor_space(obj);
4204 }
4205 // When scanning the RS, we only care about objs in CS.
4206 if (barrier == G1BarrierRS) {
4207 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4208 }
4209 }
4211 // When scanning moved objs, must look at all oops.
4212 if (barrier == G1BarrierEvac && obj != NULL) {
4213 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4214 }
4216 if (do_gen_barrier && obj != NULL) {
4217 par_do_barrier(p);
4218 }
4219 }
4221 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(oop* p);
4223 template<class T> void G1ParScanPartialArrayClosure::process_array_chunk(
4224 oop obj, int start, int end) {
4225 // process our set of indices (include header in first chunk)
4226 assert(start < end, "invariant");
4227 T* const base = (T*)objArrayOop(obj)->base();
4228 T* const start_addr = (start == 0) ? (T*) obj : base + start;
4229 T* const end_addr = base + end;
4230 MemRegion mr((HeapWord*)start_addr, (HeapWord*)end_addr);
4231 _scanner.set_region(_g1->heap_region_containing(obj));
4232 obj->oop_iterate(&_scanner, mr);
4233 }
4235 void G1ParScanPartialArrayClosure::do_oop_nv(oop* p) {
4236 assert(!UseCompressedOops, "Needs to be fixed to work with compressed oops");
4237 assert(has_partial_array_mask(p), "invariant");
4238 oop old = clear_partial_array_mask(p);
4239 assert(old->is_objArray(), "must be obj array");
4240 assert(old->is_forwarded(), "must be forwarded");
4241 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4243 objArrayOop obj = objArrayOop(old->forwardee());
4244 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4245 // Process ParGCArrayScanChunk elements now
4246 // and push the remainder back onto queue
4247 int start = arrayOop(old)->length();
4248 int end = obj->length();
4249 int remainder = end - start;
4250 assert(start <= end, "just checking");
4251 if (remainder > 2 * ParGCArrayScanChunk) {
4252 // Test above combines last partial chunk with a full chunk
4253 end = start + ParGCArrayScanChunk;
4254 arrayOop(old)->set_length(end);
4255 // Push remainder.
4256 _par_scan_state->push_on_queue(set_partial_array_mask(old));
4257 } else {
4258 // Restore length so that the heap remains parsable in
4259 // case of evacuation failure.
4260 arrayOop(old)->set_length(end);
4261 }
4263 // process our set of indices (include header in first chunk)
4264 process_array_chunk<oop>(obj, start, end);
4265 }
4267 int G1ScanAndBalanceClosure::_nq = 0;
4269 class G1ParEvacuateFollowersClosure : public VoidClosure {
4270 protected:
4271 G1CollectedHeap* _g1h;
4272 G1ParScanThreadState* _par_scan_state;
4273 RefToScanQueueSet* _queues;
4274 ParallelTaskTerminator* _terminator;
4276 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4277 RefToScanQueueSet* queues() { return _queues; }
4278 ParallelTaskTerminator* terminator() { return _terminator; }
4280 public:
4281 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4282 G1ParScanThreadState* par_scan_state,
4283 RefToScanQueueSet* queues,
4284 ParallelTaskTerminator* terminator)
4285 : _g1h(g1h), _par_scan_state(par_scan_state),
4286 _queues(queues), _terminator(terminator) {}
4288 void do_void() {
4289 G1ParScanThreadState* pss = par_scan_state();
4290 while (true) {
4291 oop* ref_to_scan;
4292 pss->trim_queue();
4293 IF_G1_DETAILED_STATS(pss->note_steal_attempt());
4294 if (queues()->steal(pss->queue_num(),
4295 pss->hash_seed(),
4296 ref_to_scan)) {
4297 IF_G1_DETAILED_STATS(pss->note_steal());
4299 // slightly paranoid tests; I'm trying to catch potential
4300 // problems before we go into push_on_queue to know where the
4301 // problem is coming from
4302 assert(ref_to_scan != NULL, "invariant");
4303 assert(has_partial_array_mask(ref_to_scan) ||
4304 _g1h->obj_in_cs(*ref_to_scan), "invariant");
4305 pss->push_on_queue(ref_to_scan);
4306 continue;
4307 }
4308 pss->start_term_time();
4309 if (terminator()->offer_termination()) break;
4310 pss->end_term_time();
4311 }
4312 pss->end_term_time();
4313 pss->retire_alloc_buffers();
4314 }
4315 };
4317 class G1ParTask : public AbstractGangTask {
4318 protected:
4319 G1CollectedHeap* _g1h;
4320 RefToScanQueueSet *_queues;
4321 ParallelTaskTerminator _terminator;
4323 Mutex _stats_lock;
4324 Mutex* stats_lock() { return &_stats_lock; }
4326 size_t getNCards() {
4327 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4328 / G1BlockOffsetSharedArray::N_bytes;
4329 }
4331 public:
4332 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4333 : AbstractGangTask("G1 collection"),
4334 _g1h(g1h),
4335 _queues(task_queues),
4336 _terminator(workers, _queues),
4337 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4338 {}
4340 RefToScanQueueSet* queues() { return _queues; }
4342 RefToScanQueue *work_queue(int i) {
4343 return queues()->queue(i);
4344 }
4346 void work(int i) {
4347 ResourceMark rm;
4348 HandleMark hm;
4350 G1ParScanThreadState pss(_g1h, i);
4351 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4352 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4353 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4355 pss.set_evac_closure(&scan_evac_cl);
4356 pss.set_evac_failure_closure(&evac_failure_cl);
4357 pss.set_partial_scan_closure(&partial_scan_cl);
4359 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4360 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4361 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4363 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4364 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4365 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4367 OopsInHeapRegionClosure *scan_root_cl;
4368 OopsInHeapRegionClosure *scan_perm_cl;
4369 OopsInHeapRegionClosure *scan_so_cl;
4371 if (_g1h->g1_policy()->should_initiate_conc_mark()) {
4372 scan_root_cl = &scan_mark_root_cl;
4373 scan_perm_cl = &scan_mark_perm_cl;
4374 scan_so_cl = &scan_mark_heap_rs_cl;
4375 } else {
4376 scan_root_cl = &only_scan_root_cl;
4377 scan_perm_cl = &only_scan_perm_cl;
4378 scan_so_cl = &only_scan_heap_rs_cl;
4379 }
4381 pss.start_strong_roots();
4382 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4383 SharedHeap::SO_AllClasses,
4384 scan_root_cl,
4385 &only_scan_heap_rs_cl,
4386 scan_so_cl,
4387 scan_perm_cl,
4388 i);
4389 pss.end_strong_roots();
4390 {
4391 double start = os::elapsedTime();
4392 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4393 evac.do_void();
4394 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4395 double term_ms = pss.term_time()*1000.0;
4396 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4397 _g1h->g1_policy()->record_termination_time(i, term_ms);
4398 }
4399 if (G1UseSurvivorSpace) {
4400 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4401 }
4402 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4404 // Clean up any par-expanded rem sets.
4405 HeapRegionRemSet::par_cleanup();
4407 MutexLocker x(stats_lock());
4408 if (ParallelGCVerbose) {
4409 gclog_or_tty->print("Thread %d complete:\n", i);
4410 #if G1_DETAILED_STATS
4411 gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n",
4412 pss.pushes(),
4413 pss.pops(),
4414 pss.overflow_pushes(),
4415 pss.steals(),
4416 pss.steal_attempts());
4417 #endif
4418 double elapsed = pss.elapsed();
4419 double strong_roots = pss.strong_roots_time();
4420 double term = pss.term_time();
4421 gclog_or_tty->print(" Elapsed: %7.2f ms.\n"
4422 " Strong roots: %7.2f ms (%6.2f%%)\n"
4423 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n",
4424 elapsed * 1000.0,
4425 strong_roots * 1000.0, (strong_roots*100.0/elapsed),
4426 term * 1000.0, (term*100.0/elapsed),
4427 pss.term_attempts());
4428 size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste();
4429 gclog_or_tty->print(" Waste: %8dK\n"
4430 " Alloc Buffer: %8dK\n"
4431 " Undo: %8dK\n",
4432 (total_waste * HeapWordSize) / K,
4433 (pss.alloc_buffer_waste() * HeapWordSize) / K,
4434 (pss.undo_waste() * HeapWordSize) / K);
4435 }
4437 assert(pss.refs_to_scan() == 0, "Task queue should be empty");
4438 assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
4439 }
4440 };
4442 // *** Common G1 Evacuation Stuff
4444 class G1CountClosure: public OopsInHeapRegionClosure {
4445 public:
4446 int n;
4447 G1CountClosure() : n(0) {}
4448 void do_oop(narrowOop* p) {
4449 guarantee(false, "NYI");
4450 }
4451 void do_oop(oop* p) {
4452 oop obj = *p;
4453 assert(obj != NULL && G1CollectedHeap::heap()->obj_in_cs(obj),
4454 "Rem set closure called on non-rem-set pointer.");
4455 n++;
4456 }
4457 };
4459 static G1CountClosure count_closure;
4461 void
4462 G1CollectedHeap::
4463 g1_process_strong_roots(bool collecting_perm_gen,
4464 SharedHeap::ScanningOption so,
4465 OopClosure* scan_non_heap_roots,
4466 OopsInHeapRegionClosure* scan_rs,
4467 OopsInHeapRegionClosure* scan_so,
4468 OopsInGenClosure* scan_perm,
4469 int worker_i) {
4470 // First scan the strong roots, including the perm gen.
4471 double ext_roots_start = os::elapsedTime();
4472 double closure_app_time_sec = 0.0;
4474 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4475 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4476 buf_scan_perm.set_generation(perm_gen());
4478 process_strong_roots(collecting_perm_gen, so,
4479 &buf_scan_non_heap_roots,
4480 &buf_scan_perm);
4481 // Finish up any enqueued closure apps.
4482 buf_scan_non_heap_roots.done();
4483 buf_scan_perm.done();
4484 double ext_roots_end = os::elapsedTime();
4485 g1_policy()->reset_obj_copy_time(worker_i);
4486 double obj_copy_time_sec =
4487 buf_scan_non_heap_roots.closure_app_seconds() +
4488 buf_scan_perm.closure_app_seconds();
4489 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4490 double ext_root_time_ms =
4491 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4492 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4494 // Scan strong roots in mark stack.
4495 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4496 concurrent_mark()->oops_do(scan_non_heap_roots);
4497 }
4498 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4499 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4501 // XXX What should this be doing in the parallel case?
4502 g1_policy()->record_collection_pause_end_CH_strong_roots();
4503 if (G1VerifyRemSet) {
4504 // :::: FIXME ::::
4505 // The stupid remembered set doesn't know how to filter out dead
4506 // objects, which the smart one does, and so when it is created
4507 // and then compared the number of entries in each differs and
4508 // the verification code fails.
4509 guarantee(false, "verification code is broken, see note");
4511 // Let's make sure that the current rem set agrees with the stupidest
4512 // one possible!
4513 bool refs_enabled = ref_processor()->discovery_enabled();
4514 if (refs_enabled) ref_processor()->disable_discovery();
4515 StupidG1RemSet stupid(this);
4516 count_closure.n = 0;
4517 stupid.oops_into_collection_set_do(&count_closure, worker_i);
4518 int stupid_n = count_closure.n;
4519 count_closure.n = 0;
4520 g1_rem_set()->oops_into_collection_set_do(&count_closure, worker_i);
4521 guarantee(count_closure.n == stupid_n, "Old and new rem sets differ.");
4522 gclog_or_tty->print_cr("\nFound %d pointers in heap RS.", count_closure.n);
4523 if (refs_enabled) ref_processor()->enable_discovery();
4524 }
4525 if (scan_so != NULL) {
4526 scan_scan_only_set(scan_so, worker_i);
4527 }
4528 // Now scan the complement of the collection set.
4529 if (scan_rs != NULL) {
4530 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4531 }
4532 // Finish with the ref_processor roots.
4533 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4534 ref_processor()->oops_do(scan_non_heap_roots);
4535 }
4536 g1_policy()->record_collection_pause_end_G1_strong_roots();
4537 _process_strong_tasks->all_tasks_completed();
4538 }
4540 void
4541 G1CollectedHeap::scan_scan_only_region(HeapRegion* r,
4542 OopsInHeapRegionClosure* oc,
4543 int worker_i) {
4544 HeapWord* startAddr = r->bottom();
4545 HeapWord* endAddr = r->used_region().end();
4547 oc->set_region(r);
4549 HeapWord* p = r->bottom();
4550 HeapWord* t = r->top();
4551 guarantee( p == r->next_top_at_mark_start(), "invariant" );
4552 while (p < t) {
4553 oop obj = oop(p);
4554 p += obj->oop_iterate(oc);
4555 }
4556 }
4558 void
4559 G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc,
4560 int worker_i) {
4561 double start = os::elapsedTime();
4563 BufferingOopsInHeapRegionClosure boc(oc);
4565 FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc);
4566 FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark());
4568 OopsInHeapRegionClosure *foc;
4569 if (g1_policy()->should_initiate_conc_mark())
4570 foc = &scan_and_mark;
4571 else
4572 foc = &scan_only;
4574 HeapRegion* hr;
4575 int n = 0;
4576 while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) {
4577 scan_scan_only_region(hr, foc, worker_i);
4578 ++n;
4579 }
4580 boc.done();
4582 double closure_app_s = boc.closure_app_seconds();
4583 g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0);
4584 double ms = (os::elapsedTime() - start - closure_app_s)*1000.0;
4585 g1_policy()->record_scan_only_time(worker_i, ms, n);
4586 }
4588 void
4589 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4590 OopClosure* non_root_closure) {
4591 SharedHeap::process_weak_roots(root_closure, non_root_closure);
4592 }
4595 class SaveMarksClosure: public HeapRegionClosure {
4596 public:
4597 bool doHeapRegion(HeapRegion* r) {
4598 r->save_marks();
4599 return false;
4600 }
4601 };
4603 void G1CollectedHeap::save_marks() {
4604 if (ParallelGCThreads == 0) {
4605 SaveMarksClosure sm;
4606 heap_region_iterate(&sm);
4607 }
4608 // We do this even in the parallel case
4609 perm_gen()->save_marks();
4610 }
4612 void G1CollectedHeap::evacuate_collection_set() {
4613 set_evacuation_failed(false);
4615 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4616 concurrent_g1_refine()->set_use_cache(false);
4617 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4618 set_par_threads(n_workers);
4619 G1ParTask g1_par_task(this, n_workers, _task_queues);
4621 init_for_evac_failure(NULL);
4623 change_strong_roots_parity(); // In preparation for parallel strong roots.
4624 rem_set()->prepare_for_younger_refs_iterate(true);
4626 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4627 double start_par = os::elapsedTime();
4628 if (ParallelGCThreads > 0) {
4629 // The individual threads will set their evac-failure closures.
4630 workers()->run_task(&g1_par_task);
4631 } else {
4632 g1_par_task.work(0);
4633 }
4635 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4636 g1_policy()->record_par_time(par_time);
4637 set_par_threads(0);
4638 // Is this the right thing to do here? We don't save marks
4639 // on individual heap regions when we allocate from
4640 // them in parallel, so this seems like the correct place for this.
4641 retire_all_alloc_regions();
4642 {
4643 G1IsAliveClosure is_alive(this);
4644 G1KeepAliveClosure keep_alive(this);
4645 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4646 }
4647 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4649 concurrent_g1_refine()->set_use_cache(true);
4651 finalize_for_evac_failure();
4653 // Must do this before removing self-forwarding pointers, which clears
4654 // the per-region evac-failure flags.
4655 concurrent_mark()->complete_marking_in_collection_set();
4657 if (evacuation_failed()) {
4658 remove_self_forwarding_pointers();
4659 if (PrintGCDetails) {
4660 gclog_or_tty->print(" (evacuation failed)");
4661 } else if (PrintGC) {
4662 gclog_or_tty->print("--");
4663 }
4664 }
4666 if (G1DeferredRSUpdate) {
4667 RedirtyLoggedCardTableEntryFastClosure redirty;
4668 dirty_card_queue_set().set_closure(&redirty);
4669 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4670 JavaThread::dirty_card_queue_set().merge_bufferlists(&dirty_card_queue_set());
4671 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4672 }
4674 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4675 }
4677 void G1CollectedHeap::free_region(HeapRegion* hr) {
4678 size_t pre_used = 0;
4679 size_t cleared_h_regions = 0;
4680 size_t freed_regions = 0;
4681 UncleanRegionList local_list;
4683 HeapWord* start = hr->bottom();
4684 HeapWord* end = hr->prev_top_at_mark_start();
4685 size_t used_bytes = hr->used();
4686 size_t live_bytes = hr->max_live_bytes();
4687 if (used_bytes > 0) {
4688 guarantee( live_bytes <= used_bytes, "invariant" );
4689 } else {
4690 guarantee( live_bytes == 0, "invariant" );
4691 }
4693 size_t garbage_bytes = used_bytes - live_bytes;
4694 if (garbage_bytes > 0)
4695 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4697 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4698 &local_list);
4699 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4700 &local_list);
4701 }
4703 void
4704 G1CollectedHeap::free_region_work(HeapRegion* hr,
4705 size_t& pre_used,
4706 size_t& cleared_h_regions,
4707 size_t& freed_regions,
4708 UncleanRegionList* list,
4709 bool par) {
4710 assert(!hr->popular(), "should not free popular regions");
4711 pre_used += hr->used();
4712 if (hr->isHumongous()) {
4713 assert(hr->startsHumongous(),
4714 "Only the start of a humongous region should be freed.");
4715 int ind = _hrs->find(hr);
4716 assert(ind != -1, "Should have an index.");
4717 // Clear the start region.
4718 hr->hr_clear(par, true /*clear_space*/);
4719 list->insert_before_head(hr);
4720 cleared_h_regions++;
4721 freed_regions++;
4722 // Clear any continued regions.
4723 ind++;
4724 while ((size_t)ind < n_regions()) {
4725 HeapRegion* hrc = _hrs->at(ind);
4726 if (!hrc->continuesHumongous()) break;
4727 // Otherwise, does continue the H region.
4728 assert(hrc->humongous_start_region() == hr, "Huh?");
4729 hrc->hr_clear(par, true /*clear_space*/);
4730 cleared_h_regions++;
4731 freed_regions++;
4732 list->insert_before_head(hrc);
4733 ind++;
4734 }
4735 } else {
4736 hr->hr_clear(par, true /*clear_space*/);
4737 list->insert_before_head(hr);
4738 freed_regions++;
4739 // If we're using clear2, this should not be enabled.
4740 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4741 }
4742 }
4744 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4745 size_t cleared_h_regions,
4746 size_t freed_regions,
4747 UncleanRegionList* list) {
4748 if (list != NULL && list->sz() > 0) {
4749 prepend_region_list_on_unclean_list(list);
4750 }
4751 // Acquire a lock, if we're parallel, to update possibly-shared
4752 // variables.
4753 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4754 {
4755 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4756 _summary_bytes_used -= pre_used;
4757 _num_humongous_regions -= (int) cleared_h_regions;
4758 _free_regions += freed_regions;
4759 }
4760 }
4763 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4764 while (list != NULL) {
4765 guarantee( list->is_young(), "invariant" );
4767 HeapWord* bottom = list->bottom();
4768 HeapWord* end = list->end();
4769 MemRegion mr(bottom, end);
4770 ct_bs->dirty(mr);
4772 list = list->get_next_young_region();
4773 }
4774 }
4776 void G1CollectedHeap::cleanUpCardTable() {
4777 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4778 double start = os::elapsedTime();
4780 ct_bs->clear(_g1_committed);
4782 // now, redirty the cards of the scan-only and survivor regions
4783 // (it seemed faster to do it this way, instead of iterating over
4784 // all regions and then clearing / dirtying as approprite)
4785 dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region());
4786 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4788 double elapsed = os::elapsedTime() - start;
4789 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4790 }
4793 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4794 // First do any popular regions.
4795 HeapRegion* hr;
4796 while ((hr = popular_region_to_evac()) != NULL) {
4797 evac_popular_region(hr);
4798 }
4799 // Now do heuristic pauses.
4800 if (g1_policy()->should_do_collection_pause(word_size)) {
4801 do_collection_pause();
4802 }
4803 }
4805 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4806 double young_time_ms = 0.0;
4807 double non_young_time_ms = 0.0;
4809 G1CollectorPolicy* policy = g1_policy();
4811 double start_sec = os::elapsedTime();
4812 bool non_young = true;
4814 HeapRegion* cur = cs_head;
4815 int age_bound = -1;
4816 size_t rs_lengths = 0;
4818 while (cur != NULL) {
4819 if (non_young) {
4820 if (cur->is_young()) {
4821 double end_sec = os::elapsedTime();
4822 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4823 non_young_time_ms += elapsed_ms;
4825 start_sec = os::elapsedTime();
4826 non_young = false;
4827 }
4828 } else {
4829 if (!cur->is_on_free_list()) {
4830 double end_sec = os::elapsedTime();
4831 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4832 young_time_ms += elapsed_ms;
4834 start_sec = os::elapsedTime();
4835 non_young = true;
4836 }
4837 }
4839 rs_lengths += cur->rem_set()->occupied();
4841 HeapRegion* next = cur->next_in_collection_set();
4842 assert(cur->in_collection_set(), "bad CS");
4843 cur->set_next_in_collection_set(NULL);
4844 cur->set_in_collection_set(false);
4846 if (cur->is_young()) {
4847 int index = cur->young_index_in_cset();
4848 guarantee( index != -1, "invariant" );
4849 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4850 size_t words_survived = _surviving_young_words[index];
4851 cur->record_surv_words_in_group(words_survived);
4852 } else {
4853 int index = cur->young_index_in_cset();
4854 guarantee( index == -1, "invariant" );
4855 }
4857 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4858 (!cur->is_young() && cur->young_index_in_cset() == -1),
4859 "invariant" );
4861 if (!cur->evacuation_failed()) {
4862 // And the region is empty.
4863 assert(!cur->is_empty(),
4864 "Should not have empty regions in a CS.");
4865 free_region(cur);
4866 } else {
4867 guarantee( !cur->is_scan_only(), "should not be scan only" );
4868 cur->uninstall_surv_rate_group();
4869 if (cur->is_young())
4870 cur->set_young_index_in_cset(-1);
4871 cur->set_not_young();
4872 cur->set_evacuation_failed(false);
4873 }
4874 cur = next;
4875 }
4877 policy->record_max_rs_lengths(rs_lengths);
4878 policy->cset_regions_freed();
4880 double end_sec = os::elapsedTime();
4881 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4882 if (non_young)
4883 non_young_time_ms += elapsed_ms;
4884 else
4885 young_time_ms += elapsed_ms;
4887 policy->record_young_free_cset_time_ms(young_time_ms);
4888 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4889 }
4891 HeapRegion*
4892 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4893 assert(ZF_mon->owned_by_self(), "Precondition");
4894 HeapRegion* res = pop_unclean_region_list_locked();
4895 if (res != NULL) {
4896 assert(!res->continuesHumongous() &&
4897 res->zero_fill_state() != HeapRegion::Allocated,
4898 "Only free regions on unclean list.");
4899 if (zero_filled) {
4900 res->ensure_zero_filled_locked();
4901 res->set_zero_fill_allocated();
4902 }
4903 }
4904 return res;
4905 }
4907 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4908 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4909 return alloc_region_from_unclean_list_locked(zero_filled);
4910 }
4912 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4913 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4914 put_region_on_unclean_list_locked(r);
4915 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4916 }
4918 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4919 MutexLockerEx x(Cleanup_mon);
4920 set_unclean_regions_coming_locked(b);
4921 }
4923 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4924 assert(Cleanup_mon->owned_by_self(), "Precondition");
4925 _unclean_regions_coming = b;
4926 // Wake up mutator threads that might be waiting for completeCleanup to
4927 // finish.
4928 if (!b) Cleanup_mon->notify_all();
4929 }
4931 void G1CollectedHeap::wait_for_cleanup_complete() {
4932 MutexLockerEx x(Cleanup_mon);
4933 wait_for_cleanup_complete_locked();
4934 }
4936 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4937 assert(Cleanup_mon->owned_by_self(), "precondition");
4938 while (_unclean_regions_coming) {
4939 Cleanup_mon->wait();
4940 }
4941 }
4943 void
4944 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4945 assert(ZF_mon->owned_by_self(), "precondition.");
4946 _unclean_region_list.insert_before_head(r);
4947 }
4949 void
4950 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4951 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4952 prepend_region_list_on_unclean_list_locked(list);
4953 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4954 }
4956 void
4957 G1CollectedHeap::
4958 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4959 assert(ZF_mon->owned_by_self(), "precondition.");
4960 _unclean_region_list.prepend_list(list);
4961 }
4963 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4964 assert(ZF_mon->owned_by_self(), "precondition.");
4965 HeapRegion* res = _unclean_region_list.pop();
4966 if (res != NULL) {
4967 // Inform ZF thread that there's a new unclean head.
4968 if (_unclean_region_list.hd() != NULL && should_zf())
4969 ZF_mon->notify_all();
4970 }
4971 return res;
4972 }
4974 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4975 assert(ZF_mon->owned_by_self(), "precondition.");
4976 return _unclean_region_list.hd();
4977 }
4980 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4981 assert(ZF_mon->owned_by_self(), "Precondition");
4982 HeapRegion* r = peek_unclean_region_list_locked();
4983 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4984 // Result of below must be equal to "r", since we hold the lock.
4985 (void)pop_unclean_region_list_locked();
4986 put_free_region_on_list_locked(r);
4987 return true;
4988 } else {
4989 return false;
4990 }
4991 }
4993 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4994 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4995 return move_cleaned_region_to_free_list_locked();
4996 }
4999 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
5000 assert(ZF_mon->owned_by_self(), "precondition.");
5001 assert(_free_region_list_size == free_region_list_length(), "Inv");
5002 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
5003 "Regions on free list must be zero filled");
5004 assert(!r->isHumongous(), "Must not be humongous.");
5005 assert(r->is_empty(), "Better be empty");
5006 assert(!r->is_on_free_list(),
5007 "Better not already be on free list");
5008 assert(!r->is_on_unclean_list(),
5009 "Better not already be on unclean list");
5010 r->set_on_free_list(true);
5011 r->set_next_on_free_list(_free_region_list);
5012 _free_region_list = r;
5013 _free_region_list_size++;
5014 assert(_free_region_list_size == free_region_list_length(), "Inv");
5015 }
5017 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
5018 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5019 put_free_region_on_list_locked(r);
5020 }
5022 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
5023 assert(ZF_mon->owned_by_self(), "precondition.");
5024 assert(_free_region_list_size == free_region_list_length(), "Inv");
5025 HeapRegion* res = _free_region_list;
5026 if (res != NULL) {
5027 _free_region_list = res->next_from_free_list();
5028 _free_region_list_size--;
5029 res->set_on_free_list(false);
5030 res->set_next_on_free_list(NULL);
5031 assert(_free_region_list_size == free_region_list_length(), "Inv");
5032 }
5033 return res;
5034 }
5037 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
5038 // By self, or on behalf of self.
5039 assert(Heap_lock->is_locked(), "Precondition");
5040 HeapRegion* res = NULL;
5041 bool first = true;
5042 while (res == NULL) {
5043 if (zero_filled || !first) {
5044 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5045 res = pop_free_region_list_locked();
5046 if (res != NULL) {
5047 assert(!res->zero_fill_is_allocated(),
5048 "No allocated regions on free list.");
5049 res->set_zero_fill_allocated();
5050 } else if (!first) {
5051 break; // We tried both, time to return NULL.
5052 }
5053 }
5055 if (res == NULL) {
5056 res = alloc_region_from_unclean_list(zero_filled);
5057 }
5058 assert(res == NULL ||
5059 !zero_filled ||
5060 res->zero_fill_is_allocated(),
5061 "We must have allocated the region we're returning");
5062 first = false;
5063 }
5064 return res;
5065 }
5067 void G1CollectedHeap::remove_allocated_regions_from_lists() {
5068 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5069 {
5070 HeapRegion* prev = NULL;
5071 HeapRegion* cur = _unclean_region_list.hd();
5072 while (cur != NULL) {
5073 HeapRegion* next = cur->next_from_unclean_list();
5074 if (cur->zero_fill_is_allocated()) {
5075 // Remove from the list.
5076 if (prev == NULL) {
5077 (void)_unclean_region_list.pop();
5078 } else {
5079 _unclean_region_list.delete_after(prev);
5080 }
5081 cur->set_on_unclean_list(false);
5082 cur->set_next_on_unclean_list(NULL);
5083 } else {
5084 prev = cur;
5085 }
5086 cur = next;
5087 }
5088 assert(_unclean_region_list.sz() == unclean_region_list_length(),
5089 "Inv");
5090 }
5092 {
5093 HeapRegion* prev = NULL;
5094 HeapRegion* cur = _free_region_list;
5095 while (cur != NULL) {
5096 HeapRegion* next = cur->next_from_free_list();
5097 if (cur->zero_fill_is_allocated()) {
5098 // Remove from the list.
5099 if (prev == NULL) {
5100 _free_region_list = cur->next_from_free_list();
5101 } else {
5102 prev->set_next_on_free_list(cur->next_from_free_list());
5103 }
5104 cur->set_on_free_list(false);
5105 cur->set_next_on_free_list(NULL);
5106 _free_region_list_size--;
5107 } else {
5108 prev = cur;
5109 }
5110 cur = next;
5111 }
5112 assert(_free_region_list_size == free_region_list_length(), "Inv");
5113 }
5114 }
5116 bool G1CollectedHeap::verify_region_lists() {
5117 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5118 return verify_region_lists_locked();
5119 }
5121 bool G1CollectedHeap::verify_region_lists_locked() {
5122 HeapRegion* unclean = _unclean_region_list.hd();
5123 while (unclean != NULL) {
5124 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
5125 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
5126 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
5127 "Everything else is possible.");
5128 unclean = unclean->next_from_unclean_list();
5129 }
5130 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
5132 HeapRegion* free_r = _free_region_list;
5133 while (free_r != NULL) {
5134 assert(free_r->is_on_free_list(), "Well, it is!");
5135 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
5136 switch (free_r->zero_fill_state()) {
5137 case HeapRegion::NotZeroFilled:
5138 case HeapRegion::ZeroFilling:
5139 guarantee(false, "Should not be on free list.");
5140 break;
5141 default:
5142 // Everything else is possible.
5143 break;
5144 }
5145 free_r = free_r->next_from_free_list();
5146 }
5147 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
5148 // If we didn't do an assertion...
5149 return true;
5150 }
5152 size_t G1CollectedHeap::free_region_list_length() {
5153 assert(ZF_mon->owned_by_self(), "precondition.");
5154 size_t len = 0;
5155 HeapRegion* cur = _free_region_list;
5156 while (cur != NULL) {
5157 len++;
5158 cur = cur->next_from_free_list();
5159 }
5160 return len;
5161 }
5163 size_t G1CollectedHeap::unclean_region_list_length() {
5164 assert(ZF_mon->owned_by_self(), "precondition.");
5165 return _unclean_region_list.length();
5166 }
5168 size_t G1CollectedHeap::n_regions() {
5169 return _hrs->length();
5170 }
5172 size_t G1CollectedHeap::max_regions() {
5173 return
5174 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
5175 HeapRegion::GrainBytes;
5176 }
5178 size_t G1CollectedHeap::free_regions() {
5179 /* Possibly-expensive assert.
5180 assert(_free_regions == count_free_regions(),
5181 "_free_regions is off.");
5182 */
5183 return _free_regions;
5184 }
5186 bool G1CollectedHeap::should_zf() {
5187 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
5188 }
5190 class RegionCounter: public HeapRegionClosure {
5191 size_t _n;
5192 public:
5193 RegionCounter() : _n(0) {}
5194 bool doHeapRegion(HeapRegion* r) {
5195 if (r->is_empty() && !r->popular()) {
5196 assert(!r->isHumongous(), "H regions should not be empty.");
5197 _n++;
5198 }
5199 return false;
5200 }
5201 int res() { return (int) _n; }
5202 };
5204 size_t G1CollectedHeap::count_free_regions() {
5205 RegionCounter rc;
5206 heap_region_iterate(&rc);
5207 size_t n = rc.res();
5208 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
5209 n--;
5210 return n;
5211 }
5213 size_t G1CollectedHeap::count_free_regions_list() {
5214 size_t n = 0;
5215 size_t o = 0;
5216 ZF_mon->lock_without_safepoint_check();
5217 HeapRegion* cur = _free_region_list;
5218 while (cur != NULL) {
5219 cur = cur->next_from_free_list();
5220 n++;
5221 }
5222 size_t m = unclean_region_list_length();
5223 ZF_mon->unlock();
5224 return n + m;
5225 }
5227 bool G1CollectedHeap::should_set_young_locked() {
5228 assert(heap_lock_held_for_gc(),
5229 "the heap lock should already be held by or for this thread");
5230 return (g1_policy()->in_young_gc_mode() &&
5231 g1_policy()->should_add_next_region_to_young_list());
5232 }
5234 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5235 assert(heap_lock_held_for_gc(),
5236 "the heap lock should already be held by or for this thread");
5237 _young_list->push_region(hr);
5238 g1_policy()->set_region_short_lived(hr);
5239 }
5241 class NoYoungRegionsClosure: public HeapRegionClosure {
5242 private:
5243 bool _success;
5244 public:
5245 NoYoungRegionsClosure() : _success(true) { }
5246 bool doHeapRegion(HeapRegion* r) {
5247 if (r->is_young()) {
5248 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5249 r->bottom(), r->end());
5250 _success = false;
5251 }
5252 return false;
5253 }
5254 bool success() { return _success; }
5255 };
5257 bool G1CollectedHeap::check_young_list_empty(bool ignore_scan_only_list,
5258 bool check_sample) {
5259 bool ret = true;
5261 ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample);
5262 if (!ignore_scan_only_list) {
5263 NoYoungRegionsClosure closure;
5264 heap_region_iterate(&closure);
5265 ret = ret && closure.success();
5266 }
5268 return ret;
5269 }
5271 void G1CollectedHeap::empty_young_list() {
5272 assert(heap_lock_held_for_gc(),
5273 "the heap lock should already be held by or for this thread");
5274 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
5276 _young_list->empty_list();
5277 }
5279 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
5280 bool no_allocs = true;
5281 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
5282 HeapRegion* r = _gc_alloc_regions[ap];
5283 no_allocs = r == NULL || r->saved_mark_at_top();
5284 }
5285 return no_allocs;
5286 }
5288 void G1CollectedHeap::retire_all_alloc_regions() {
5289 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
5290 HeapRegion* r = _gc_alloc_regions[ap];
5291 if (r != NULL) {
5292 // Check for aliases.
5293 bool has_processed_alias = false;
5294 for (int i = 0; i < ap; ++i) {
5295 if (_gc_alloc_regions[i] == r) {
5296 has_processed_alias = true;
5297 break;
5298 }
5299 }
5300 if (!has_processed_alias) {
5301 retire_alloc_region(r, false /* par */);
5302 }
5303 }
5304 }
5305 }
5308 // Done at the start of full GC.
5309 void G1CollectedHeap::tear_down_region_lists() {
5310 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5311 while (pop_unclean_region_list_locked() != NULL) ;
5312 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
5313 "Postconditions of loop.")
5314 while (pop_free_region_list_locked() != NULL) ;
5315 assert(_free_region_list == NULL, "Postcondition of loop.");
5316 if (_free_region_list_size != 0) {
5317 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
5318 print();
5319 }
5320 assert(_free_region_list_size == 0, "Postconditions of loop.");
5321 }
5324 class RegionResetter: public HeapRegionClosure {
5325 G1CollectedHeap* _g1;
5326 int _n;
5327 public:
5328 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5329 bool doHeapRegion(HeapRegion* r) {
5330 if (r->continuesHumongous()) return false;
5331 if (r->top() > r->bottom()) {
5332 if (r->top() < r->end()) {
5333 Copy::fill_to_words(r->top(),
5334 pointer_delta(r->end(), r->top()));
5335 }
5336 r->set_zero_fill_allocated();
5337 } else {
5338 assert(r->is_empty(), "tautology");
5339 if (r->popular()) {
5340 if (r->zero_fill_state() != HeapRegion::Allocated) {
5341 r->ensure_zero_filled_locked();
5342 r->set_zero_fill_allocated();
5343 }
5344 } else {
5345 _n++;
5346 switch (r->zero_fill_state()) {
5347 case HeapRegion::NotZeroFilled:
5348 case HeapRegion::ZeroFilling:
5349 _g1->put_region_on_unclean_list_locked(r);
5350 break;
5351 case HeapRegion::Allocated:
5352 r->set_zero_fill_complete();
5353 // no break; go on to put on free list.
5354 case HeapRegion::ZeroFilled:
5355 _g1->put_free_region_on_list_locked(r);
5356 break;
5357 }
5358 }
5359 }
5360 return false;
5361 }
5363 int getFreeRegionCount() {return _n;}
5364 };
5366 // Done at the end of full GC.
5367 void G1CollectedHeap::rebuild_region_lists() {
5368 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5369 // This needs to go at the end of the full GC.
5370 RegionResetter rs;
5371 heap_region_iterate(&rs);
5372 _free_regions = rs.getFreeRegionCount();
5373 // Tell the ZF thread it may have work to do.
5374 if (should_zf()) ZF_mon->notify_all();
5375 }
5377 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
5378 G1CollectedHeap* _g1;
5379 int _n;
5380 public:
5381 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5382 bool doHeapRegion(HeapRegion* r) {
5383 if (r->continuesHumongous()) return false;
5384 if (r->top() > r->bottom()) {
5385 // There are assertions in "set_zero_fill_needed()" below that
5386 // require top() == bottom(), so this is technically illegal.
5387 // We'll skirt the law here, by making that true temporarily.
5388 DEBUG_ONLY(HeapWord* save_top = r->top();
5389 r->set_top(r->bottom()));
5390 r->set_zero_fill_needed();
5391 DEBUG_ONLY(r->set_top(save_top));
5392 }
5393 return false;
5394 }
5395 };
5397 // Done at the start of full GC.
5398 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
5399 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5400 // This needs to go at the end of the full GC.
5401 UsedRegionsNeedZeroFillSetter rs;
5402 heap_region_iterate(&rs);
5403 }
5405 class CountObjClosure: public ObjectClosure {
5406 size_t _n;
5407 public:
5408 CountObjClosure() : _n(0) {}
5409 void do_object(oop obj) { _n++; }
5410 size_t n() { return _n; }
5411 };
5413 size_t G1CollectedHeap::pop_object_used_objs() {
5414 size_t sum_objs = 0;
5415 for (int i = 0; i < G1NumPopularRegions; i++) {
5416 CountObjClosure cl;
5417 _hrs->at(i)->object_iterate(&cl);
5418 sum_objs += cl.n();
5419 }
5420 return sum_objs;
5421 }
5423 size_t G1CollectedHeap::pop_object_used_bytes() {
5424 size_t sum_bytes = 0;
5425 for (int i = 0; i < G1NumPopularRegions; i++) {
5426 sum_bytes += _hrs->at(i)->used();
5427 }
5428 return sum_bytes;
5429 }
5432 static int nq = 0;
5434 HeapWord* G1CollectedHeap::allocate_popular_object(size_t word_size) {
5435 while (_cur_pop_hr_index < G1NumPopularRegions) {
5436 HeapRegion* cur_pop_region = _hrs->at(_cur_pop_hr_index);
5437 HeapWord* res = cur_pop_region->allocate(word_size);
5438 if (res != NULL) {
5439 // We account for popular objs directly in the used summary:
5440 _summary_bytes_used += (word_size * HeapWordSize);
5441 return res;
5442 }
5443 // Otherwise, try the next region (first making sure that we remember
5444 // the last "top" value as the "next_top_at_mark_start", so that
5445 // objects made popular during markings aren't automatically considered
5446 // live).
5447 cur_pop_region->note_end_of_copying();
5448 // Otherwise, try the next region.
5449 _cur_pop_hr_index++;
5450 }
5451 // XXX: For now !!!
5452 vm_exit_out_of_memory(word_size,
5453 "Not enough pop obj space (To Be Fixed)");
5454 return NULL;
5455 }
5457 class HeapRegionList: public CHeapObj {
5458 public:
5459 HeapRegion* hr;
5460 HeapRegionList* next;
5461 };
5463 void G1CollectedHeap::schedule_popular_region_evac(HeapRegion* r) {
5464 // This might happen during parallel GC, so protect by this lock.
5465 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
5466 // We don't schedule regions whose evacuations are already pending, or
5467 // are already being evacuated.
5468 if (!r->popular_pending() && !r->in_collection_set()) {
5469 r->set_popular_pending(true);
5470 if (G1TracePopularity) {
5471 gclog_or_tty->print_cr("Scheduling region "PTR_FORMAT" "
5472 "["PTR_FORMAT", "PTR_FORMAT") for pop-object evacuation.",
5473 r, r->bottom(), r->end());
5474 }
5475 HeapRegionList* hrl = new HeapRegionList;
5476 hrl->hr = r;
5477 hrl->next = _popular_regions_to_be_evacuated;
5478 _popular_regions_to_be_evacuated = hrl;
5479 }
5480 }
5482 HeapRegion* G1CollectedHeap::popular_region_to_evac() {
5483 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
5484 HeapRegion* res = NULL;
5485 while (_popular_regions_to_be_evacuated != NULL && res == NULL) {
5486 HeapRegionList* hrl = _popular_regions_to_be_evacuated;
5487 _popular_regions_to_be_evacuated = hrl->next;
5488 res = hrl->hr;
5489 // The G1RSPopLimit may have increased, so recheck here...
5490 if (res->rem_set()->occupied() < (size_t) G1RSPopLimit) {
5491 // Hah: don't need to schedule.
5492 if (G1TracePopularity) {
5493 gclog_or_tty->print_cr("Unscheduling region "PTR_FORMAT" "
5494 "["PTR_FORMAT", "PTR_FORMAT") "
5495 "for pop-object evacuation (size %d < limit %d)",
5496 res, res->bottom(), res->end(),
5497 res->rem_set()->occupied(), G1RSPopLimit);
5498 }
5499 res->set_popular_pending(false);
5500 res = NULL;
5501 }
5502 // We do not reset res->popular() here; if we did so, it would allow
5503 // the region to be "rescheduled" for popularity evacuation. Instead,
5504 // this is done in the collection pause, with the world stopped.
5505 // So the invariant is that the regions in the list have the popularity
5506 // boolean set, but having the boolean set does not imply membership
5507 // on the list (though there can at most one such pop-pending region
5508 // not on the list at any time).
5509 delete hrl;
5510 }
5511 return res;
5512 }
5514 void G1CollectedHeap::evac_popular_region(HeapRegion* hr) {
5515 while (true) {
5516 // Don't want to do a GC pause while cleanup is being completed!
5517 wait_for_cleanup_complete();
5519 // Read the GC count while holding the Heap_lock
5520 int gc_count_before = SharedHeap::heap()->total_collections();
5521 g1_policy()->record_stop_world_start();
5523 {
5524 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
5525 VM_G1PopRegionCollectionPause op(gc_count_before, hr);
5526 VMThread::execute(&op);
5528 // If the prolog succeeded, we didn't do a GC for this.
5529 if (op.prologue_succeeded()) break;
5530 }
5531 // Otherwise we didn't. We should recheck the size, though, since
5532 // the limit may have increased...
5533 if (hr->rem_set()->occupied() < (size_t) G1RSPopLimit) {
5534 hr->set_popular_pending(false);
5535 break;
5536 }
5537 }
5538 }
5540 void G1CollectedHeap::atomic_inc_obj_rc(oop obj) {
5541 Atomic::inc(obj_rc_addr(obj));
5542 }
5544 class CountRCClosure: public OopsInHeapRegionClosure {
5545 G1CollectedHeap* _g1h;
5546 bool _parallel;
5547 public:
5548 CountRCClosure(G1CollectedHeap* g1h) :
5549 _g1h(g1h), _parallel(ParallelGCThreads > 0)
5550 {}
5551 void do_oop(narrowOop* p) {
5552 guarantee(false, "NYI");
5553 }
5554 void do_oop(oop* p) {
5555 oop obj = *p;
5556 assert(obj != NULL, "Precondition.");
5557 if (_parallel) {
5558 // We go sticky at the limit to avoid excess contention.
5559 // If we want to track the actual RC's further, we'll need to keep a
5560 // per-thread hash table or something for the popular objects.
5561 if (_g1h->obj_rc(obj) < G1ObjPopLimit) {
5562 _g1h->atomic_inc_obj_rc(obj);
5563 }
5564 } else {
5565 _g1h->inc_obj_rc(obj);
5566 }
5567 }
5568 };
5570 class EvacPopObjClosure: public ObjectClosure {
5571 G1CollectedHeap* _g1h;
5572 size_t _pop_objs;
5573 size_t _max_rc;
5574 public:
5575 EvacPopObjClosure(G1CollectedHeap* g1h) :
5576 _g1h(g1h), _pop_objs(0), _max_rc(0) {}
5578 void do_object(oop obj) {
5579 size_t rc = _g1h->obj_rc(obj);
5580 _max_rc = MAX2(rc, _max_rc);
5581 if (rc >= (size_t) G1ObjPopLimit) {
5582 _g1h->_pop_obj_rc_at_copy.add((double)rc);
5583 size_t word_sz = obj->size();
5584 HeapWord* new_pop_loc = _g1h->allocate_popular_object(word_sz);
5585 oop new_pop_obj = (oop)new_pop_loc;
5586 Copy::aligned_disjoint_words((HeapWord*)obj, new_pop_loc, word_sz);
5587 obj->forward_to(new_pop_obj);
5588 G1ScanAndBalanceClosure scan_and_balance(_g1h);
5589 new_pop_obj->oop_iterate_backwards(&scan_and_balance);
5590 // preserve "next" mark bit if marking is in progress.
5591 if (_g1h->mark_in_progress() && !_g1h->is_obj_ill(obj)) {
5592 _g1h->concurrent_mark()->markAndGrayObjectIfNecessary(new_pop_obj);
5593 }
5595 if (G1TracePopularity) {
5596 gclog_or_tty->print_cr("Found obj " PTR_FORMAT " of word size " SIZE_FORMAT
5597 " pop (%d), move to " PTR_FORMAT,
5598 (void*) obj, word_sz,
5599 _g1h->obj_rc(obj), (void*) new_pop_obj);
5600 }
5601 _pop_objs++;
5602 }
5603 }
5604 size_t pop_objs() { return _pop_objs; }
5605 size_t max_rc() { return _max_rc; }
5606 };
5608 class G1ParCountRCTask : public AbstractGangTask {
5609 G1CollectedHeap* _g1h;
5610 BitMap _bm;
5612 size_t getNCards() {
5613 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
5614 / G1BlockOffsetSharedArray::N_bytes;
5615 }
5616 CountRCClosure _count_rc_closure;
5617 public:
5618 G1ParCountRCTask(G1CollectedHeap* g1h) :
5619 AbstractGangTask("G1 Par RC Count task"),
5620 _g1h(g1h), _bm(getNCards()), _count_rc_closure(g1h)
5621 {}
5623 void work(int i) {
5624 ResourceMark rm;
5625 HandleMark hm;
5626 _g1h->g1_rem_set()->oops_into_collection_set_do(&_count_rc_closure, i);
5627 }
5628 };
5630 void G1CollectedHeap::popularity_pause_preamble(HeapRegion* popular_region) {
5631 // We're evacuating a single region (for popularity).
5632 if (G1TracePopularity) {
5633 gclog_or_tty->print_cr("Doing pop region pause for ["PTR_FORMAT", "PTR_FORMAT")",
5634 popular_region->bottom(), popular_region->end());
5635 }
5636 g1_policy()->set_single_region_collection_set(popular_region);
5637 size_t max_rc;
5638 if (!compute_reference_counts_and_evac_popular(popular_region,
5639 &max_rc)) {
5640 // We didn't evacuate any popular objects.
5641 // We increase the RS popularity limit, to prevent this from
5642 // happening in the future.
5643 if (G1RSPopLimit < (1 << 30)) {
5644 G1RSPopLimit *= 2;
5645 }
5646 // For now, interesting enough for a message:
5647 #if 1
5648 gclog_or_tty->print_cr("In pop region pause for ["PTR_FORMAT", "PTR_FORMAT"), "
5649 "failed to find a pop object (max = %d).",
5650 popular_region->bottom(), popular_region->end(),
5651 max_rc);
5652 gclog_or_tty->print_cr("Increased G1RSPopLimit to %d.", G1RSPopLimit);
5653 #endif // 0
5654 // Also, we reset the collection set to NULL, to make the rest of
5655 // the collection do nothing.
5656 assert(popular_region->next_in_collection_set() == NULL,
5657 "should be single-region.");
5658 popular_region->set_in_collection_set(false);
5659 popular_region->set_popular_pending(false);
5660 g1_policy()->clear_collection_set();
5661 }
5662 }
5664 bool G1CollectedHeap::
5665 compute_reference_counts_and_evac_popular(HeapRegion* popular_region,
5666 size_t* max_rc) {
5667 HeapWord* rc_region_bot;
5668 HeapWord* rc_region_end;
5670 // Set up the reference count region.
5671 HeapRegion* rc_region = newAllocRegion(HeapRegion::GrainWords);
5672 if (rc_region != NULL) {
5673 rc_region_bot = rc_region->bottom();
5674 rc_region_end = rc_region->end();
5675 } else {
5676 rc_region_bot = NEW_C_HEAP_ARRAY(HeapWord, HeapRegion::GrainWords);
5677 if (rc_region_bot == NULL) {
5678 vm_exit_out_of_memory(HeapRegion::GrainWords,
5679 "No space for RC region.");
5680 }
5681 rc_region_end = rc_region_bot + HeapRegion::GrainWords;
5682 }
5684 if (G1TracePopularity)
5685 gclog_or_tty->print_cr("RC region is ["PTR_FORMAT", "PTR_FORMAT")",
5686 rc_region_bot, rc_region_end);
5687 if (rc_region_bot > popular_region->bottom()) {
5688 _rc_region_above = true;
5689 _rc_region_diff =
5690 pointer_delta(rc_region_bot, popular_region->bottom(), 1);
5691 } else {
5692 assert(rc_region_bot < popular_region->bottom(), "Can't be equal.");
5693 _rc_region_above = false;
5694 _rc_region_diff =
5695 pointer_delta(popular_region->bottom(), rc_region_bot, 1);
5696 }
5697 g1_policy()->record_pop_compute_rc_start();
5698 // Count external references.
5699 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5700 if (ParallelGCThreads > 0) {
5702 set_par_threads(workers()->total_workers());
5703 G1ParCountRCTask par_count_rc_task(this);
5704 workers()->run_task(&par_count_rc_task);
5705 set_par_threads(0);
5707 } else {
5708 CountRCClosure count_rc_closure(this);
5709 g1_rem_set()->oops_into_collection_set_do(&count_rc_closure, 0);
5710 }
5711 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5712 g1_policy()->record_pop_compute_rc_end();
5714 // Now evacuate popular objects.
5715 g1_policy()->record_pop_evac_start();
5716 EvacPopObjClosure evac_pop_obj_cl(this);
5717 popular_region->object_iterate(&evac_pop_obj_cl);
5718 *max_rc = evac_pop_obj_cl.max_rc();
5720 // Make sure the last "top" value of the current popular region is copied
5721 // as the "next_top_at_mark_start", so that objects made popular during
5722 // markings aren't automatically considered live.
5723 HeapRegion* cur_pop_region = _hrs->at(_cur_pop_hr_index);
5724 cur_pop_region->note_end_of_copying();
5726 if (rc_region != NULL) {
5727 free_region(rc_region);
5728 } else {
5729 FREE_C_HEAP_ARRAY(HeapWord, rc_region_bot);
5730 }
5731 g1_policy()->record_pop_evac_end();
5733 return evac_pop_obj_cl.pop_objs() > 0;
5734 }
5736 class CountPopObjInfoClosure: public HeapRegionClosure {
5737 size_t _objs;
5738 size_t _bytes;
5740 class CountObjClosure: public ObjectClosure {
5741 int _n;
5742 public:
5743 CountObjClosure() : _n(0) {}
5744 void do_object(oop obj) { _n++; }
5745 size_t n() { return _n; }
5746 };
5748 public:
5749 CountPopObjInfoClosure() : _objs(0), _bytes(0) {}
5750 bool doHeapRegion(HeapRegion* r) {
5751 _bytes += r->used();
5752 CountObjClosure blk;
5753 r->object_iterate(&blk);
5754 _objs += blk.n();
5755 return false;
5756 }
5757 size_t objs() { return _objs; }
5758 size_t bytes() { return _bytes; }
5759 };
5762 void G1CollectedHeap::print_popularity_summary_info() const {
5763 CountPopObjInfoClosure blk;
5764 for (int i = 0; i <= _cur_pop_hr_index; i++) {
5765 blk.doHeapRegion(_hrs->at(i));
5766 }
5767 gclog_or_tty->print_cr("\nPopular objects: %d objs, %d bytes.",
5768 blk.objs(), blk.bytes());
5769 gclog_or_tty->print_cr(" RC at copy = [avg = %5.2f, max = %5.2f, sd = %5.2f].",
5770 _pop_obj_rc_at_copy.avg(),
5771 _pop_obj_rc_at_copy.maximum(),
5772 _pop_obj_rc_at_copy.sd());
5773 }
5775 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5776 _refine_cte_cl->set_concurrent(concurrent);
5777 }
5779 #ifndef PRODUCT
5781 class PrintHeapRegionClosure: public HeapRegionClosure {
5782 public:
5783 bool doHeapRegion(HeapRegion *r) {
5784 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
5785 if (r != NULL) {
5786 if (r->is_on_free_list())
5787 gclog_or_tty->print("Free ");
5788 if (r->is_young())
5789 gclog_or_tty->print("Young ");
5790 if (r->isHumongous())
5791 gclog_or_tty->print("Is Humongous ");
5792 r->print();
5793 }
5794 return false;
5795 }
5796 };
5798 class SortHeapRegionClosure : public HeapRegionClosure {
5799 size_t young_regions,free_regions, unclean_regions;
5800 size_t hum_regions, count;
5801 size_t unaccounted, cur_unclean, cur_alloc;
5802 size_t total_free;
5803 HeapRegion* cur;
5804 public:
5805 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5806 free_regions(0), unclean_regions(0),
5807 hum_regions(0),
5808 count(0), unaccounted(0),
5809 cur_alloc(0), total_free(0)
5810 {}
5811 bool doHeapRegion(HeapRegion *r) {
5812 count++;
5813 if (r->is_on_free_list()) free_regions++;
5814 else if (r->is_on_unclean_list()) unclean_regions++;
5815 else if (r->isHumongous()) hum_regions++;
5816 else if (r->is_young()) young_regions++;
5817 else if (r == cur) cur_alloc++;
5818 else unaccounted++;
5819 return false;
5820 }
5821 void print() {
5822 total_free = free_regions + unclean_regions;
5823 gclog_or_tty->print("%d regions\n", count);
5824 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5825 total_free, free_regions, unclean_regions);
5826 gclog_or_tty->print("%d humongous %d young\n",
5827 hum_regions, young_regions);
5828 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5829 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5830 }
5831 };
5833 void G1CollectedHeap::print_region_counts() {
5834 SortHeapRegionClosure sc(_cur_alloc_region);
5835 PrintHeapRegionClosure cl;
5836 heap_region_iterate(&cl);
5837 heap_region_iterate(&sc);
5838 sc.print();
5839 print_region_accounting_info();
5840 };
5842 bool G1CollectedHeap::regions_accounted_for() {
5843 // TODO: regions accounting for young/survivor/tenured
5844 return true;
5845 }
5847 bool G1CollectedHeap::print_region_accounting_info() {
5848 gclog_or_tty->print_cr("P regions: %d.", G1NumPopularRegions);
5849 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5850 free_regions(),
5851 count_free_regions(), count_free_regions_list(),
5852 _free_region_list_size, _unclean_region_list.sz());
5853 gclog_or_tty->print_cr("cur_alloc: %d.",
5854 (_cur_alloc_region == NULL ? 0 : 1));
5855 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5857 // TODO: check regions accounting for young/survivor/tenured
5858 return true;
5859 }
5861 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5862 HeapRegion* hr = heap_region_containing(p);
5863 if (hr == NULL) {
5864 return is_in_permanent(p);
5865 } else {
5866 return hr->is_in(p);
5867 }
5868 }
5869 #endif // PRODUCT
5871 void G1CollectedHeap::g1_unimplemented() {
5872 // Unimplemented();
5873 }
5876 // Local Variables: ***
5877 // c-indentation-style: gnu ***
5878 // End: ***