1 /*
2 * Copyright 2001-2008 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 #include "incls/_precompiled.incl"
26 #include "incls/_g1CollectedHeap.cpp.incl"
27
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".
34
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.)
42
43 // Local to this file.
44
45 // Finds the first HeapRegion.
46 // No longer used, but might be handy someday.
47
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 };
58
59
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 };
82
83
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 };
117
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 };
138
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 };
146
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 }
156
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!");
160
161 hr->set_next_young_region(_head);
162 _head = hr;
163
164 hr->set_young();
165 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
166 ++_length;
167 }
168
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!");
172
173 hr->set_next_young_region(_survivor_head);
174 if (_survivor_head == NULL) {
175 _survivor_tail = hr;
176 }
177 _survivor_head = hr;
178
179 ++_survivor_length;
180 }
181
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");
190
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 }
197
198 if (!ret->is_scan_only()) {
199 return ret;
200 }
201
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" );
205
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;
214
215 // no need to be tagged as scan-only any more
216 ret->set_young();
217
218 ++_scan_only_length;
219 }
220 assert( length() == 0, "list should be empty" );
221 return NULL;
222 }
223
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 }
233
234 void YoungList::empty_list() {
235 assert(check_list_well_formed(), "young list should be well formed");
236
237 empty_list(_head);
238 _head = NULL;
239 _length = 0;
240
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;
246
247 empty_list(_survivor_head);
248 _survivor_head = NULL;
249 _survivor_tail = NULL;
250 _survivor_length = 0;
251
252 _last_sampled_rs_lengths = 0;
253
254 assert(check_list_empty(false), "just making sure...");
255 }
256
257 bool YoungList::check_list_well_formed() {
258 bool ret = true;
259
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);
276
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 }
282
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);
300
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 }
307
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 }
312
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 }
318
319 return ret && scan_only_ret;
320 }
321
322 bool YoungList::check_list_empty(bool ignore_scan_only_list,
323 bool check_sample) {
324 bool ret = true;
325
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 }
342
343 if (ignore_scan_only_list)
344 return ret;
345
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 }
363
364 return ret && scan_only_ret;
365 }
366
367 void
368 YoungList::rs_length_sampling_init() {
369 _sampled_rs_lengths = 0;
370 _curr = _head;
371 }
372
373 bool
374 YoungList::rs_length_sampling_more() {
375 return _curr != NULL;
376 }
377
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 }
388
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.
395
396 guarantee( is_empty(), "young list should be empty" );
397 assert(check_list_well_formed(), "young list should be well formed");
398
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();
408
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 }
417
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;
427
428 _survivor_head = NULL;
429 _survivor_tail = NULL;
430 _survivor_length = 0;
431 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
432
433 assert(check_list_well_formed(), "young list should be well formed");
434 }
435
436 void YoungList::print() {
437 HeapRegion* lists[] = {_head, _scan_only_head, _survivor_head};
438 const char* names[] = {"YOUNG", "SCAN-ONLY", "SURVIVOR"};
439
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 }
460
461 gclog_or_tty->print_cr("");
462 }
463
464 void G1CollectedHeap::stop_conc_gc_threads() {
465 _cg1r->cg1rThread()->stop();
466 _czft->stop();
467 _cmThread->stop();
468 }
469
470
471 void G1CollectedHeap::check_ct_logs_at_safepoint() {
472 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
473 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
474
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();
479
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();
486
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.");
495
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.");
504
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 }
512
513 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
514 }
515
516 // Private class members.
517
518 G1CollectedHeap* G1CollectedHeap::_g1h;
519
520 // Private methods.
521
522 // Finds a HeapRegion that can be used to allocate a given size of block.
523
524
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)");
545
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 }
553
554 return res;
555 }
556
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 }
572
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!");
578
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();
585
586 size_t num_regions =
587 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
588
589 // Special case if < one region???
590
591 // Remember the ft size.
592 size_t x_size = expansion_regions();
593
594 HeapWord* res = NULL;
595 bool eliminated_allocated_from_lists = false;
596
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 }
637
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;
643
644 assert( SafepointSynchronize::is_at_safepoint() ||
645 Heap_lock->owned_by_self(), "pre condition of the call" );
646
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.");
657
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.");
695
696 // Now retry the allocation.
697 if (_cur_alloc_region != NULL) {
698 res = _cur_alloc_region->allocate(word_size);
699 }
700 }
701
702 // NOTE: fails frequently in PRT
703 assert(regions_accounted_for(), "Region leakage!");
704
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 }
711
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 }
720
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" );
725
726 return res;
727 }
728
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;
737
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 }
754
755 // Create the garbage collection operation...
756 VM_G1CollectForAllocation op(word_size,
757 gc_count_before);
758
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 }
766
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 }
775
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 }
788
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 }
794
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 };
814
815
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 };
828
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 };
847
848 class ParRebuildRSTask: public AbstractGangTask {
849 G1CollectedHeap* _g1;
850 public:
851 ParRebuildRSTask(G1CollectedHeap* g1)
852 : AbstractGangTask("ParRebuildRSTask"),
853 _g1(g1)
854 { }
855
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 };
862
863 void G1CollectedHeap::do_collection(bool full, bool clear_all_soft_refs,
864 size_t word_size) {
865 ResourceMark rm;
866
867 if (full && DisableExplicitGC) {
868 gclog_or_tty->print("\n\n\nDisabling Explicit GC\n\n\n");
869 return;
870 }
871
872 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
873 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
874
875 if (GC_locker::is_active()) {
876 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
877 }
878
879 {
880 IsGCActiveMark x;
881
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);
886
887 double start = os::elapsedTime();
888 GCOverheadReporter::recordSTWStart(start);
889 g1_policy()->record_full_collection_start();
890
891 gc_prologue(true);
892 increment_total_collections();
893
894 size_t g1h_prev_used = used();
895 assert(used() == recalculate_used(), "Should be equal");
896
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!");
904
905 COMPILER2_PRESENT(DerivedPointerTable::clear());
906
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();
916
917 // Abandon current iterations of concurrent marking and concurrent
918 // refinement, if any are in progress.
919 concurrent_mark()->abort();
920
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 }
932
933 // Temporarily make reference _discovery_ single threaded (non-MT).
934 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
935
936 // Temporarily make refs discovery atomic
937 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
938
939 // Temporarily clear _is_alive_non_header
940 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
941
942 ref_processor()->enable_discovery();
943 ref_processor()->setup_policy(clear_all_soft_refs);
944
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();
954
955 _summary_bytes_used = recalculate_used();
956
957 ref_processor()->enqueue_discovered_references();
958
959 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
960
961 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
962 HandleMark hm; // Discard invalid handles created during verification
963 gclog_or_tty->print(" VerifyAfterGC:");
964 Universe::verify(false);
965 }
966 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
967
968 reset_gc_time_stamp();
969 // Since everything potentially moved, we will clear all remembered
970 // sets, and clear all cards. Later we will rebuild remebered
971 // sets. We will also reset the GC time stamps of the regions.
972 PostMCRemSetClearClosure rs_clear(mr_bs());
973 heap_region_iterate(&rs_clear);
974
975 // Resize the heap if necessary.
976 resize_if_necessary_after_full_collection(full ? 0 : word_size);
977
978 if (_cg1r->use_cache()) {
979 _cg1r->clear_and_record_card_counts();
980 _cg1r->clear_hot_cache();
981 }
982
983 // Rebuild remembered sets of all regions.
984 if (ParallelGCThreads > 0) {
985 ParRebuildRSTask rebuild_rs_task(this);
986 assert(check_heap_region_claim_values(
987 HeapRegion::InitialClaimValue), "sanity check");
988 set_par_threads(workers()->total_workers());
989 workers()->run_task(&rebuild_rs_task);
990 set_par_threads(0);
991 assert(check_heap_region_claim_values(
992 HeapRegion::RebuildRSClaimValue), "sanity check");
993 reset_heap_region_claim_values();
994 } else {
995 RebuildRSOutOfRegionClosure rebuild_rs(this);
996 heap_region_iterate(&rebuild_rs);
997 }
998
999 if (PrintGC) {
1000 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1001 }
1002
1003 if (true) { // FIXME
1004 // Ask the permanent generation to adjust size for full collections
1005 perm()->compute_new_size();
1006 }
1007
1008 double end = os::elapsedTime();
1009 GCOverheadReporter::recordSTWEnd(end);
1010 g1_policy()->record_full_collection_end();
1011
1012 #ifdef TRACESPINNING
1013 ParallelTaskTerminator::print_termination_counts();
1014 #endif
1015
1016 gc_epilogue(true);
1017
1018 // Abandon concurrent refinement. This must happen last: in the
1019 // dirty-card logging system, some cards may be dirty by weak-ref
1020 // processing, and may be enqueued. But the whole card table is
1021 // dirtied, so this should abandon those logs, and set "do_traversal"
1022 // to true.
1023 concurrent_g1_refine()->set_pya_restart();
1024 assert(!G1DeferredRSUpdate
1025 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1026 assert(regions_accounted_for(), "Region leakage!");
1027 }
1028
1029 if (g1_policy()->in_young_gc_mode()) {
1030 _young_list->reset_sampled_info();
1031 assert( check_young_list_empty(false, false),
1032 "young list should be empty at this point");
1033 }
1034 }
1035
1036 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1037 do_collection(true, clear_all_soft_refs, 0);
1038 }
1039
1040 // This code is mostly copied from TenuredGeneration.
1041 void
1042 G1CollectedHeap::
1043 resize_if_necessary_after_full_collection(size_t word_size) {
1044 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1045
1046 // Include the current allocation, if any, and bytes that will be
1047 // pre-allocated to support collections, as "used".
1048 const size_t used_after_gc = used();
1049 const size_t capacity_after_gc = capacity();
1050 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1051
1052 // We don't have floating point command-line arguments
1053 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100;
1054 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1055 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
1056 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1057
1058 size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage);
1059 size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage);
1060
1061 // Don't shrink less than the initial size.
1062 minimum_desired_capacity =
1063 MAX2(minimum_desired_capacity,
1064 collector_policy()->initial_heap_byte_size());
1065 maximum_desired_capacity =
1066 MAX2(maximum_desired_capacity,
1067 collector_policy()->initial_heap_byte_size());
1068
1069 // We are failing here because minimum_desired_capacity is
1070 assert(used_after_gc <= minimum_desired_capacity, "sanity check");
1071 assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check");
1072
1073 if (PrintGC && Verbose) {
1074 const double free_percentage = ((double)free_after_gc) / capacity();
1075 gclog_or_tty->print_cr("Computing new size after full GC ");
1076 gclog_or_tty->print_cr(" "
1077 " minimum_free_percentage: %6.2f",
1078 minimum_free_percentage);
1079 gclog_or_tty->print_cr(" "
1080 " maximum_free_percentage: %6.2f",
1081 maximum_free_percentage);
1082 gclog_or_tty->print_cr(" "
1083 " capacity: %6.1fK"
1084 " minimum_desired_capacity: %6.1fK"
1085 " maximum_desired_capacity: %6.1fK",
1086 capacity() / (double) K,
1087 minimum_desired_capacity / (double) K,
1088 maximum_desired_capacity / (double) K);
1089 gclog_or_tty->print_cr(" "
1090 " free_after_gc : %6.1fK"
1091 " used_after_gc : %6.1fK",
1092 free_after_gc / (double) K,
1093 used_after_gc / (double) K);
1094 gclog_or_tty->print_cr(" "
1095 " free_percentage: %6.2f",
1096 free_percentage);
1097 }
1098 if (capacity() < minimum_desired_capacity) {
1099 // Don't expand unless it's significant
1100 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1101 expand(expand_bytes);
1102 if (PrintGC && Verbose) {
1103 gclog_or_tty->print_cr(" expanding:"
1104 " minimum_desired_capacity: %6.1fK"
1105 " expand_bytes: %6.1fK",
1106 minimum_desired_capacity / (double) K,
1107 expand_bytes / (double) K);
1108 }
1109
1110 // No expansion, now see if we want to shrink
1111 } else if (capacity() > maximum_desired_capacity) {
1112 // Capacity too large, compute shrinking size
1113 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1114 shrink(shrink_bytes);
1115 if (PrintGC && Verbose) {
1116 gclog_or_tty->print_cr(" "
1117 " shrinking:"
1118 " initSize: %.1fK"
1119 " maximum_desired_capacity: %.1fK",
1120 collector_policy()->initial_heap_byte_size() / (double) K,
1121 maximum_desired_capacity / (double) K);
1122 gclog_or_tty->print_cr(" "
1123 " shrink_bytes: %.1fK",
1124 shrink_bytes / (double) K);
1125 }
1126 }
1127 }
1128
1129
1130 HeapWord*
1131 G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
1132 HeapWord* result = NULL;
1133
1134 // In a G1 heap, we're supposed to keep allocation from failing by
1135 // incremental pauses. Therefore, at least for now, we'll favor
1136 // expansion over collection. (This might change in the future if we can
1137 // do something smarter than full collection to satisfy a failed alloc.)
1138
1139 result = expand_and_allocate(word_size);
1140 if (result != NULL) {
1141 assert(is_in(result), "result not in heap");
1142 return result;
1143 }
1144
1145 // OK, I guess we have to try collection.
1146
1147 do_collection(false, false, word_size);
1148
1149 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1150
1151 if (result != NULL) {
1152 assert(is_in(result), "result not in heap");
1153 return result;
1154 }
1155
1156 // Try collecting soft references.
1157 do_collection(false, true, word_size);
1158 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1159 if (result != NULL) {
1160 assert(is_in(result), "result not in heap");
1161 return result;
1162 }
1163
1164 // What else? We might try synchronous finalization later. If the total
1165 // space available is large enough for the allocation, then a more
1166 // complete compaction phase than we've tried so far might be
1167 // appropriate.
1168 return NULL;
1169 }
1170
1171 // Attempting to expand the heap sufficiently
1172 // to support an allocation of the given "word_size". If
1173 // successful, perform the allocation and return the address of the
1174 // allocated block, or else "NULL".
1175
1176 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1177 size_t expand_bytes = word_size * HeapWordSize;
1178 if (expand_bytes < MinHeapDeltaBytes) {
1179 expand_bytes = MinHeapDeltaBytes;
1180 }
1181 expand(expand_bytes);
1182 assert(regions_accounted_for(), "Region leakage!");
1183 HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
1184 return result;
1185 }
1186
1187 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
1188 size_t pre_used = 0;
1189 size_t cleared_h_regions = 0;
1190 size_t freed_regions = 0;
1191 UncleanRegionList local_list;
1192 free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
1193 freed_regions, &local_list);
1194
1195 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
1196 &local_list);
1197 return pre_used;
1198 }
1199
1200 void
1201 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
1202 size_t& pre_used,
1203 size_t& cleared_h,
1204 size_t& freed_regions,
1205 UncleanRegionList* list,
1206 bool par) {
1207 assert(!hr->continuesHumongous(), "should have filtered these out");
1208 size_t res = 0;
1209 if (!hr->popular() && hr->used() > 0 && hr->garbage_bytes() == hr->used()) {
1210 if (!hr->is_young()) {
1211 if (G1PolicyVerbose > 0)
1212 gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
1213 " during cleanup", hr, hr->used());
1214 free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
1215 }
1216 }
1217 }
1218
1219 // FIXME: both this and shrink could probably be more efficient by
1220 // doing one "VirtualSpace::expand_by" call rather than several.
1221 void G1CollectedHeap::expand(size_t expand_bytes) {
1222 size_t old_mem_size = _g1_storage.committed_size();
1223 // We expand by a minimum of 1K.
1224 expand_bytes = MAX2(expand_bytes, (size_t)K);
1225 size_t aligned_expand_bytes =
1226 ReservedSpace::page_align_size_up(expand_bytes);
1227 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1228 HeapRegion::GrainBytes);
1229 expand_bytes = aligned_expand_bytes;
1230 while (expand_bytes > 0) {
1231 HeapWord* base = (HeapWord*)_g1_storage.high();
1232 // Commit more storage.
1233 bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
1234 if (!successful) {
1235 expand_bytes = 0;
1236 } else {
1237 expand_bytes -= HeapRegion::GrainBytes;
1238 // Expand the committed region.
1239 HeapWord* high = (HeapWord*) _g1_storage.high();
1240 _g1_committed.set_end(high);
1241 // Create a new HeapRegion.
1242 MemRegion mr(base, high);
1243 bool is_zeroed = !_g1_max_committed.contains(base);
1244 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1245
1246 // Now update max_committed if necessary.
1247 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
1248
1249 // Add it to the HeapRegionSeq.
1250 _hrs->insert(hr);
1251 // Set the zero-fill state, according to whether it's already
1252 // zeroed.
1253 {
1254 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
1255 if (is_zeroed) {
1256 hr->set_zero_fill_complete();
1257 put_free_region_on_list_locked(hr);
1258 } else {
1259 hr->set_zero_fill_needed();
1260 put_region_on_unclean_list_locked(hr);
1261 }
1262 }
1263 _free_regions++;
1264 // And we used up an expansion region to create it.
1265 _expansion_regions--;
1266 // Tell the cardtable about it.
1267 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1268 // And the offset table as well.
1269 _bot_shared->resize(_g1_committed.word_size());
1270 }
1271 }
1272 if (Verbose && PrintGC) {
1273 size_t new_mem_size = _g1_storage.committed_size();
1274 gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
1275 old_mem_size/K, aligned_expand_bytes/K,
1276 new_mem_size/K);
1277 }
1278 }
1279
1280 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1281 {
1282 size_t old_mem_size = _g1_storage.committed_size();
1283 size_t aligned_shrink_bytes =
1284 ReservedSpace::page_align_size_down(shrink_bytes);
1285 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1286 HeapRegion::GrainBytes);
1287 size_t num_regions_deleted = 0;
1288 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1289
1290 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1291 if (mr.byte_size() > 0)
1292 _g1_storage.shrink_by(mr.byte_size());
1293 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1294
1295 _g1_committed.set_end(mr.start());
1296 _free_regions -= num_regions_deleted;
1297 _expansion_regions += num_regions_deleted;
1298
1299 // Tell the cardtable about it.
1300 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1301
1302 // And the offset table as well.
1303 _bot_shared->resize(_g1_committed.word_size());
1304
1305 HeapRegionRemSet::shrink_heap(n_regions());
1306
1307 if (Verbose && PrintGC) {
1308 size_t new_mem_size = _g1_storage.committed_size();
1309 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1310 old_mem_size/K, aligned_shrink_bytes/K,
1311 new_mem_size/K);
1312 }
1313 }
1314
1315 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1316 release_gc_alloc_regions(true /* totally */);
1317 tear_down_region_lists(); // We will rebuild them in a moment.
1318 shrink_helper(shrink_bytes);
1319 rebuild_region_lists();
1320 }
1321
1322 // Public methods.
1323
1324 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1325 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1326 #endif // _MSC_VER
1327
1328
1329 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1330 SharedHeap(policy_),
1331 _g1_policy(policy_),
1332 _ref_processor(NULL),
1333 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1334 _bot_shared(NULL),
1335 _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
1336 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1337 _evac_failure_scan_stack(NULL) ,
1338 _mark_in_progress(false),
1339 _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
1340 _cur_alloc_region(NULL),
1341 _refine_cte_cl(NULL),
1342 _free_region_list(NULL), _free_region_list_size(0),
1343 _free_regions(0),
1344 _popular_object_boundary(NULL),
1345 _cur_pop_hr_index(0),
1346 _popular_regions_to_be_evacuated(NULL),
1347 _pop_obj_rc_at_copy(),
1348 _full_collection(false),
1349 _unclean_region_list(),
1350 _unclean_regions_coming(false),
1351 _young_list(new YoungList(this)),
1352 _gc_time_stamp(0),
1353 _surviving_young_words(NULL),
1354 _in_cset_fast_test(NULL),
1355 _in_cset_fast_test_base(NULL) {
1356 _g1h = this; // To catch bugs.
1357 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1358 vm_exit_during_initialization("Failed necessary allocation.");
1359 }
1360 int n_queues = MAX2((int)ParallelGCThreads, 1);
1361 _task_queues = new RefToScanQueueSet(n_queues);
1362
1363 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1364 assert(n_rem_sets > 0, "Invariant.");
1365
1366 HeapRegionRemSetIterator** iter_arr =
1367 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1368 for (int i = 0; i < n_queues; i++) {
1369 iter_arr[i] = new HeapRegionRemSetIterator();
1370 }
1371 _rem_set_iterator = iter_arr;
1372
1373 for (int i = 0; i < n_queues; i++) {
1374 RefToScanQueue* q = new RefToScanQueue();
1375 q->initialize();
1376 _task_queues->register_queue(i, q);
1377 }
1378
1379 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1380 _gc_alloc_regions[ap] = NULL;
1381 _gc_alloc_region_counts[ap] = 0;
1382 _retained_gc_alloc_regions[ap] = NULL;
1383 // by default, we do not retain a GC alloc region for each ap;
1384 // we'll override this, when appropriate, below
1385 _retain_gc_alloc_region[ap] = false;
1386 }
1387
1388 // We will try to remember the last half-full tenured region we
1389 // allocated to at the end of a collection so that we can re-use it
1390 // during the next collection.
1391 _retain_gc_alloc_region[GCAllocForTenured] = true;
1392
1393 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1394 }
1395
1396 jint G1CollectedHeap::initialize() {
1397 os::enable_vtime();
1398
1399 // Necessary to satisfy locking discipline assertions.
1400
1401 MutexLocker x(Heap_lock);
1402
1403 // While there are no constraints in the GC code that HeapWordSize
1404 // be any particular value, there are multiple other areas in the
1405 // system which believe this to be true (e.g. oop->object_size in some
1406 // cases incorrectly returns the size in wordSize units rather than
1407 // HeapWordSize).
1408 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1409
1410 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1411 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1412
1413 // Ensure that the sizes are properly aligned.
1414 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1415 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1416
1417 // We allocate this in any case, but only do no work if the command line
1418 // param is off.
1419 _cg1r = new ConcurrentG1Refine();
1420
1421 // Reserve the maximum.
1422 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1423 // Includes the perm-gen.
1424 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1425 HeapRegion::GrainBytes,
1426 false /*ism*/);
1427
1428 if (!heap_rs.is_reserved()) {
1429 vm_exit_during_initialization("Could not reserve enough space for object heap");
1430 return JNI_ENOMEM;
1431 }
1432
1433 // It is important to do this in a way such that concurrent readers can't
1434 // temporarily think somethings in the heap. (I've actually seen this
1435 // happen in asserts: DLD.)
1436 _reserved.set_word_size(0);
1437 _reserved.set_start((HeapWord*)heap_rs.base());
1438 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1439
1440 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1441
1442 _num_humongous_regions = 0;
1443
1444 // Create the gen rem set (and barrier set) for the entire reserved region.
1445 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1446 set_barrier_set(rem_set()->bs());
1447 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1448 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1449 } else {
1450 vm_exit_during_initialization("G1 requires a mod ref bs.");
1451 return JNI_ENOMEM;
1452 }
1453
1454 // Also create a G1 rem set.
1455 if (G1UseHRIntoRS) {
1456 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1457 _g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs());
1458 } else {
1459 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1460 return JNI_ENOMEM;
1461 }
1462 } else {
1463 _g1_rem_set = new StupidG1RemSet(this);
1464 }
1465
1466 // Carve out the G1 part of the heap.
1467
1468 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1469 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1470 g1_rs.size()/HeapWordSize);
1471 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1472
1473 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1474
1475 _g1_storage.initialize(g1_rs, 0);
1476 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1477 _g1_max_committed = _g1_committed;
1478 _hrs = new HeapRegionSeq(_expansion_regions);
1479 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1480 guarantee(_cur_alloc_region == NULL, "from constructor");
1481
1482 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1483 heap_word_size(init_byte_size));
1484
1485 _g1h = this;
1486
1487 // Create the ConcurrentMark data structure and thread.
1488 // (Must do this late, so that "max_regions" is defined.)
1489 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1490 _cmThread = _cm->cmThread();
1491
1492 // ...and the concurrent zero-fill thread, if necessary.
1493 if (G1ConcZeroFill) {
1494 _czft = new ConcurrentZFThread();
1495 }
1496
1497
1498
1499 // Allocate the popular regions; take them off free lists.
1500 size_t pop_byte_size = G1NumPopularRegions * HeapRegion::GrainBytes;
1501 expand(pop_byte_size);
1502 _popular_object_boundary =
1503 _g1_reserved.start() + (G1NumPopularRegions * HeapRegion::GrainWords);
1504 for (int i = 0; i < G1NumPopularRegions; i++) {
1505 HeapRegion* hr = newAllocRegion(HeapRegion::GrainWords);
1506 // assert(hr != NULL && hr->bottom() < _popular_object_boundary,
1507 // "Should be enough, and all should be below boundary.");
1508 hr->set_popular(true);
1509 }
1510 assert(_cur_pop_hr_index == 0, "Start allocating at the first region.");
1511
1512 // Initialize the from_card cache structure of HeapRegionRemSet.
1513 HeapRegionRemSet::init_heap(max_regions());
1514
1515 // Now expand into the rest of the initial heap size.
1516 expand(init_byte_size - pop_byte_size);
1517
1518 // Perform any initialization actions delegated to the policy.
1519 g1_policy()->init();
1520
1521 g1_policy()->note_start_of_mark_thread();
1522
1523 _refine_cte_cl =
1524 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1525 g1_rem_set(),
1526 concurrent_g1_refine());
1527 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1528
1529 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1530 SATB_Q_FL_lock,
1531 0,
1532 Shared_SATB_Q_lock);
1533 if (G1RSBarrierUseQueue) {
1534 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1535 DirtyCardQ_FL_lock,
1536 G1DirtyCardQueueMax,
1537 Shared_DirtyCardQ_lock);
1538 }
1539 if (G1DeferredRSUpdate) {
1540 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1541 DirtyCardQ_FL_lock,
1542 0,
1543 Shared_DirtyCardQ_lock,
1544 &JavaThread::dirty_card_queue_set());
1545 }
1546 // In case we're keeping closure specialization stats, initialize those
1547 // counts and that mechanism.
1548 SpecializationStats::clear();
1549
1550 _gc_alloc_region_list = NULL;
1551
1552 // Do later initialization work for concurrent refinement.
1553 _cg1r->init();
1554
1555 const char* group_names[] = { "CR", "ZF", "CM", "CL" };
1556 GCOverheadReporter::initGCOverheadReporter(4, group_names);
1557
1558 return JNI_OK;
1559 }
1560
1561 void G1CollectedHeap::ref_processing_init() {
1562 SharedHeap::ref_processing_init();
1563 MemRegion mr = reserved_region();
1564 _ref_processor = ReferenceProcessor::create_ref_processor(
1565 mr, // span
1566 false, // Reference discovery is not atomic
1567 // (though it shouldn't matter here.)
1568 true, // mt_discovery
1569 NULL, // is alive closure: need to fill this in for efficiency
1570 ParallelGCThreads,
1571 ParallelRefProcEnabled,
1572 true); // Setting next fields of discovered
1573 // lists requires a barrier.
1574 }
1575
1576 size_t G1CollectedHeap::capacity() const {
1577 return _g1_committed.byte_size();
1578 }
1579
1580 void G1CollectedHeap::iterate_dirty_card_closure(bool concurrent,
1581 int worker_i) {
1582 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1583 int n_completed_buffers = 0;
1584 while (dcqs.apply_closure_to_completed_buffer(worker_i, 0, true)) {
1585 n_completed_buffers++;
1586 }
1587 g1_policy()->record_update_rs_processed_buffers(worker_i,
1588 (double) n_completed_buffers);
1589 dcqs.clear_n_completed_buffers();
1590 // Finish up the queue...
1591 if (worker_i == 0) concurrent_g1_refine()->clean_up_cache(worker_i,
1592 g1_rem_set());
1593 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1594 }
1595
1596
1597 // Computes the sum of the storage used by the various regions.
1598
1599 size_t G1CollectedHeap::used() const {
1600 assert(Heap_lock->owner() != NULL,
1601 "Should be owned on this thread's behalf.");
1602 size_t result = _summary_bytes_used;
1603 if (_cur_alloc_region != NULL)
1604 result += _cur_alloc_region->used();
1605 return result;
1606 }
1607
1608 class SumUsedClosure: public HeapRegionClosure {
1609 size_t _used;
1610 public:
1611 SumUsedClosure() : _used(0) {}
1612 bool doHeapRegion(HeapRegion* r) {
1613 if (!r->continuesHumongous()) {
1614 _used += r->used();
1615 }
1616 return false;
1617 }
1618 size_t result() { return _used; }
1619 };
1620
1621 size_t G1CollectedHeap::recalculate_used() const {
1622 SumUsedClosure blk;
1623 _hrs->iterate(&blk);
1624 return blk.result();
1625 }
1626
1627 #ifndef PRODUCT
1628 class SumUsedRegionsClosure: public HeapRegionClosure {
1629 size_t _num;
1630 public:
1631 // _num is set to 1 to account for the popular region
1632 SumUsedRegionsClosure() : _num(G1NumPopularRegions) {}
1633 bool doHeapRegion(HeapRegion* r) {
1634 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
1635 _num += 1;
1636 }
1637 return false;
1638 }
1639 size_t result() { return _num; }
1640 };
1641
1642 size_t G1CollectedHeap::recalculate_used_regions() const {
1643 SumUsedRegionsClosure blk;
1644 _hrs->iterate(&blk);
1645 return blk.result();
1646 }
1647 #endif // PRODUCT
1648
1649 size_t G1CollectedHeap::unsafe_max_alloc() {
1650 if (_free_regions > 0) return HeapRegion::GrainBytes;
1651 // otherwise, is there space in the current allocation region?
1652
1653 // We need to store the current allocation region in a local variable
1654 // here. The problem is that this method doesn't take any locks and
1655 // there may be other threads which overwrite the current allocation
1656 // region field. attempt_allocation(), for example, sets it to NULL
1657 // and this can happen *after* the NULL check here but before the call
1658 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
1659 // to be a problem in the optimized build, since the two loads of the
1660 // current allocation region field are optimized away.
1661 HeapRegion* car = _cur_alloc_region;
1662
1663 // FIXME: should iterate over all regions?
1664 if (car == NULL) {
1665 return 0;
1666 }
1667 return car->free();
1668 }
1669
1670 void G1CollectedHeap::collect(GCCause::Cause cause) {
1671 // The caller doesn't have the Heap_lock
1672 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
1673 MutexLocker ml(Heap_lock);
1674 collect_locked(cause);
1675 }
1676
1677 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
1678 assert(Thread::current()->is_VM_thread(), "Precondition#1");
1679 assert(Heap_lock->is_locked(), "Precondition#2");
1680 GCCauseSetter gcs(this, cause);
1681 switch (cause) {
1682 case GCCause::_heap_inspection:
1683 case GCCause::_heap_dump: {
1684 HandleMark hm;
1685 do_full_collection(false); // don't clear all soft refs
1686 break;
1687 }
1688 default: // XXX FIX ME
1689 ShouldNotReachHere(); // Unexpected use of this function
1690 }
1691 }
1692
1693
1694 void G1CollectedHeap::collect_locked(GCCause::Cause cause) {
1695 // Don't want to do a GC until cleanup is completed.
1696 wait_for_cleanup_complete();
1697
1698 // Read the GC count while holding the Heap_lock
1699 int gc_count_before = SharedHeap::heap()->total_collections();
1700 {
1701 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
1702 VM_G1CollectFull op(gc_count_before, cause);
1703 VMThread::execute(&op);
1704 }
1705 }
1706
1707 bool G1CollectedHeap::is_in(const void* p) const {
1708 if (_g1_committed.contains(p)) {
1709 HeapRegion* hr = _hrs->addr_to_region(p);
1710 return hr->is_in(p);
1711 } else {
1712 return _perm_gen->as_gen()->is_in(p);
1713 }
1714 }
1715
1716 // Iteration functions.
1717
1718 // Iterates an OopClosure over all ref-containing fields of objects
1719 // within a HeapRegion.
1720
1721 class IterateOopClosureRegionClosure: public HeapRegionClosure {
1722 MemRegion _mr;
1723 OopClosure* _cl;
1724 public:
1725 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
1726 : _mr(mr), _cl(cl) {}
1727 bool doHeapRegion(HeapRegion* r) {
1728 if (! r->continuesHumongous()) {
1729 r->oop_iterate(_cl);
1730 }
1731 return false;
1732 }
1733 };
1734
1735 void G1CollectedHeap::oop_iterate(OopClosure* cl) {
1736 IterateOopClosureRegionClosure blk(_g1_committed, cl);
1737 _hrs->iterate(&blk);
1738 }
1739
1740 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) {
1741 IterateOopClosureRegionClosure blk(mr, cl);
1742 _hrs->iterate(&blk);
1743 }
1744
1745 // Iterates an ObjectClosure over all objects within a HeapRegion.
1746
1747 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1748 ObjectClosure* _cl;
1749 public:
1750 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1751 bool doHeapRegion(HeapRegion* r) {
1752 if (! r->continuesHumongous()) {
1753 r->object_iterate(_cl);
1754 }
1755 return false;
1756 }
1757 };
1758
1759 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
1760 IterateObjectClosureRegionClosure blk(cl);
1761 _hrs->iterate(&blk);
1762 }
1763
1764 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1765 // FIXME: is this right?
1766 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
1767 }
1768
1769 // Calls a SpaceClosure on a HeapRegion.
1770
1771 class SpaceClosureRegionClosure: public HeapRegionClosure {
1772 SpaceClosure* _cl;
1773 public:
1774 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1775 bool doHeapRegion(HeapRegion* r) {
1776 _cl->do_space(r);
1777 return false;
1778 }
1779 };
1780
1781 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
1782 SpaceClosureRegionClosure blk(cl);
1783 _hrs->iterate(&blk);
1784 }
1785
1786 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
1787 _hrs->iterate(cl);
1788 }
1789
1790 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
1791 HeapRegionClosure* cl) {
1792 _hrs->iterate_from(r, cl);
1793 }
1794
1795 void
1796 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
1797 _hrs->iterate_from(idx, cl);
1798 }
1799
1800 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
1801
1802 void
1803 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1804 int worker,
1805 jint claim_value) {
1806 const size_t regions = n_regions();
1807 const size_t worker_num = (ParallelGCThreads > 0 ? ParallelGCThreads : 1);
1808 // try to spread out the starting points of the workers
1809 const size_t start_index = regions / worker_num * (size_t) worker;
1810
1811 // each worker will actually look at all regions
1812 for (size_t count = 0; count < regions; ++count) {
1813 const size_t index = (start_index + count) % regions;
1814 assert(0 <= index && index < regions, "sanity");
1815 HeapRegion* r = region_at(index);
1816 // we'll ignore "continues humongous" regions (we'll process them
1817 // when we come across their corresponding "start humongous"
1818 // region) and regions already claimed
1819 if (r->claim_value() == claim_value || r->continuesHumongous()) {
1820 continue;
1821 }
1822 // OK, try to claim it
1823 if (r->claimHeapRegion(claim_value)) {
1824 // success!
1825 assert(!r->continuesHumongous(), "sanity");
1826 if (r->startsHumongous()) {
1827 // If the region is "starts humongous" we'll iterate over its
1828 // "continues humongous" first; in fact we'll do them
1829 // first. The order is important. In on case, calling the
1830 // closure on the "starts humongous" region might de-allocate
1831 // and clear all its "continues humongous" regions and, as a
1832 // result, we might end up processing them twice. So, we'll do
1833 // them first (notice: most closures will ignore them anyway) and
1834 // then we'll do the "starts humongous" region.
1835 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
1836 HeapRegion* chr = region_at(ch_index);
1837
1838 // if the region has already been claimed or it's not
1839 // "continues humongous" we're done
1840 if (chr->claim_value() == claim_value ||
1841 !chr->continuesHumongous()) {
1842 break;
1843 }
1844
1845 // Noone should have claimed it directly. We can given
1846 // that we claimed its "starts humongous" region.
1847 assert(chr->claim_value() != claim_value, "sanity");
1848 assert(chr->humongous_start_region() == r, "sanity");
1849
1850 if (chr->claimHeapRegion(claim_value)) {
1851 // we should always be able to claim it; noone else should
1852 // be trying to claim this region
1853
1854 bool res2 = cl->doHeapRegion(chr);
1855 assert(!res2, "Should not abort");
1856
1857 // Right now, this holds (i.e., no closure that actually
1858 // does something with "continues humongous" regions
1859 // clears them). We might have to weaken it in the future,
1860 // but let's leave these two asserts here for extra safety.
1861 assert(chr->continuesHumongous(), "should still be the case");
1862 assert(chr->humongous_start_region() == r, "sanity");
1863 } else {
1864 guarantee(false, "we should not reach here");
1865 }
1866 }
1867 }
1868
1869 assert(!r->continuesHumongous(), "sanity");
1870 bool res = cl->doHeapRegion(r);
1871 assert(!res, "Should not abort");
1872 }
1873 }
1874 }
1875
1876 class ResetClaimValuesClosure: public HeapRegionClosure {
1877 public:
1878 bool doHeapRegion(HeapRegion* r) {
1879 r->set_claim_value(HeapRegion::InitialClaimValue);
1880 return false;
1881 }
1882 };
1883
1884 void
1885 G1CollectedHeap::reset_heap_region_claim_values() {
1886 ResetClaimValuesClosure blk;
1887 heap_region_iterate(&blk);
1888 }
1889
1890 #ifdef ASSERT
1891 // This checks whether all regions in the heap have the correct claim
1892 // value. I also piggy-backed on this a check to ensure that the
1893 // humongous_start_region() information on "continues humongous"
1894 // regions is correct.
1895
1896 class CheckClaimValuesClosure : public HeapRegionClosure {
1897 private:
1898 jint _claim_value;
1899 size_t _failures;
1900 HeapRegion* _sh_region;
1901 public:
1902 CheckClaimValuesClosure(jint claim_value) :
1903 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
1904 bool doHeapRegion(HeapRegion* r) {
1905 if (r->claim_value() != _claim_value) {
1906 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1907 "claim value = %d, should be %d",
1908 r->bottom(), r->end(), r->claim_value(),
1909 _claim_value);
1910 ++_failures;
1911 }
1912 if (!r->isHumongous()) {
1913 _sh_region = NULL;
1914 } else if (r->startsHumongous()) {
1915 _sh_region = r;
1916 } else if (r->continuesHumongous()) {
1917 if (r->humongous_start_region() != _sh_region) {
1918 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1919 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
1920 r->bottom(), r->end(),
1921 r->humongous_start_region(),
1922 _sh_region);
1923 ++_failures;
1924 }
1925 }
1926 return false;
1927 }
1928 size_t failures() {
1929 return _failures;
1930 }
1931 };
1932
1933 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
1934 CheckClaimValuesClosure cl(claim_value);
1935 heap_region_iterate(&cl);
1936 return cl.failures() == 0;
1937 }
1938 #endif // ASSERT
1939
1940 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
1941 HeapRegion* r = g1_policy()->collection_set();
1942 while (r != NULL) {
1943 HeapRegion* next = r->next_in_collection_set();
1944 if (cl->doHeapRegion(r)) {
1945 cl->incomplete();
1946 return;
1947 }
1948 r = next;
1949 }
1950 }
1951
1952 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
1953 HeapRegionClosure *cl) {
1954 assert(r->in_collection_set(),
1955 "Start region must be a member of the collection set.");
1956 HeapRegion* cur = r;
1957 while (cur != NULL) {
1958 HeapRegion* next = cur->next_in_collection_set();
1959 if (cl->doHeapRegion(cur) && false) {
1960 cl->incomplete();
1961 return;
1962 }
1963 cur = next;
1964 }
1965 cur = g1_policy()->collection_set();
1966 while (cur != r) {
1967 HeapRegion* next = cur->next_in_collection_set();
1968 if (cl->doHeapRegion(cur) && false) {
1969 cl->incomplete();
1970 return;
1971 }
1972 cur = next;
1973 }
1974 }
1975
1976 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
1977 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
1978 }
1979
1980
1981 Space* G1CollectedHeap::space_containing(const void* addr) const {
1982 Space* res = heap_region_containing(addr);
1983 if (res == NULL)
1984 res = perm_gen()->space_containing(addr);
1985 return res;
1986 }
1987
1988 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
1989 Space* sp = space_containing(addr);
1990 if (sp != NULL) {
1991 return sp->block_start(addr);
1992 }
1993 return NULL;
1994 }
1995
1996 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
1997 Space* sp = space_containing(addr);
1998 assert(sp != NULL, "block_size of address outside of heap");
1999 return sp->block_size(addr);
2000 }
2001
2002 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2003 Space* sp = space_containing(addr);
2004 return sp->block_is_obj(addr);
2005 }
2006
2007 bool G1CollectedHeap::supports_tlab_allocation() const {
2008 return true;
2009 }
2010
2011 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2012 return HeapRegion::GrainBytes;
2013 }
2014
2015 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2016 // Return the remaining space in the cur alloc region, but not less than
2017 // the min TLAB size.
2018 // Also, no more than half the region size, since we can't allow tlabs to
2019 // grow big enough to accomodate humongous objects.
2020
2021 // We need to story it locally, since it might change between when we
2022 // test for NULL and when we use it later.
2023 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
2024 if (cur_alloc_space == NULL) {
2025 return HeapRegion::GrainBytes/2;
2026 } else {
2027 return MAX2(MIN2(cur_alloc_space->free(),
2028 (size_t)(HeapRegion::GrainBytes/2)),
2029 (size_t)MinTLABSize);
2030 }
2031 }
2032
2033 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
2034 bool dummy;
2035 return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
2036 }
2037
2038 bool G1CollectedHeap::allocs_are_zero_filled() {
2039 return false;
2040 }
2041
2042 size_t G1CollectedHeap::large_typearray_limit() {
2043 // FIXME
2044 return HeapRegion::GrainBytes/HeapWordSize;
2045 }
2046
2047 size_t G1CollectedHeap::max_capacity() const {
2048 return _g1_committed.byte_size();
2049 }
2050
2051 jlong G1CollectedHeap::millis_since_last_gc() {
2052 // assert(false, "NYI");
2053 return 0;
2054 }
2055
2056
2057 void G1CollectedHeap::prepare_for_verify() {
2058 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2059 ensure_parsability(false);
2060 }
2061 g1_rem_set()->prepare_for_verify();
2062 }
2063
2064 class VerifyLivenessOopClosure: public OopClosure {
2065 G1CollectedHeap* g1h;
2066 public:
2067 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2068 g1h = _g1h;
2069 }
2070 void do_oop(narrowOop *p) {
2071 guarantee(false, "NYI");
2072 }
2073 void do_oop(oop *p) {
2074 oop obj = *p;
2075 assert(obj == NULL || !g1h->is_obj_dead(obj),
2076 "Dead object referenced by a not dead object");
2077 }
2078 };
2079
2080 class VerifyObjsInRegionClosure: public ObjectClosure {
2081 G1CollectedHeap* _g1h;
2082 size_t _live_bytes;
2083 HeapRegion *_hr;
2084 public:
2085 VerifyObjsInRegionClosure(HeapRegion *hr) : _live_bytes(0), _hr(hr) {
2086 _g1h = G1CollectedHeap::heap();
2087 }
2088 void do_object(oop o) {
2089 VerifyLivenessOopClosure isLive(_g1h);
2090 assert(o != NULL, "Huh?");
2091 if (!_g1h->is_obj_dead(o)) {
2092 o->oop_iterate(&isLive);
2093 if (!_hr->obj_allocated_since_prev_marking(o))
2094 _live_bytes += (o->size() * HeapWordSize);
2095 }
2096 }
2097 size_t live_bytes() { return _live_bytes; }
2098 };
2099
2100 class PrintObjsInRegionClosure : public ObjectClosure {
2101 HeapRegion *_hr;
2102 G1CollectedHeap *_g1;
2103 public:
2104 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2105 _g1 = G1CollectedHeap::heap();
2106 };
2107
2108 void do_object(oop o) {
2109 if (o != NULL) {
2110 HeapWord *start = (HeapWord *) o;
2111 size_t word_sz = o->size();
2112 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2113 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2114 (void*) o, word_sz,
2115 _g1->isMarkedPrev(o),
2116 _g1->isMarkedNext(o),
2117 _hr->obj_allocated_since_prev_marking(o));
2118 HeapWord *end = start + word_sz;
2119 HeapWord *cur;
2120 int *val;
2121 for (cur = start; cur < end; cur++) {
2122 val = (int *) cur;
2123 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2124 }
2125 }
2126 }
2127 };
2128
2129 class VerifyRegionClosure: public HeapRegionClosure {
2130 public:
2131 bool _allow_dirty;
2132 bool _par;
2133 VerifyRegionClosure(bool allow_dirty, bool par = false)
2134 : _allow_dirty(allow_dirty), _par(par) {}
2135 bool doHeapRegion(HeapRegion* r) {
2136 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2137 "Should be unclaimed at verify points.");
2138 if (r->isHumongous()) {
2139 if (r->startsHumongous()) {
2140 // Verify the single H object.
2141 oop(r->bottom())->verify();
2142 size_t word_sz = oop(r->bottom())->size();
2143 guarantee(r->top() == r->bottom() + word_sz,
2144 "Only one object in a humongous region");
2145 }
2146 } else {
2147 VerifyObjsInRegionClosure not_dead_yet_cl(r);
2148 r->verify(_allow_dirty);
2149 r->object_iterate(¬_dead_yet_cl);
2150 guarantee(r->max_live_bytes() >= not_dead_yet_cl.live_bytes(),
2151 "More live objects than counted in last complete marking.");
2152 }
2153 return false;
2154 }
2155 };
2156
2157 class VerifyRootsClosure: public OopsInGenClosure {
2158 private:
2159 G1CollectedHeap* _g1h;
2160 bool _failures;
2161
2162 public:
2163 VerifyRootsClosure() :
2164 _g1h(G1CollectedHeap::heap()), _failures(false) { }
2165
2166 bool failures() { return _failures; }
2167
2168 void do_oop(narrowOop* p) {
2169 guarantee(false, "NYI");
2170 }
2171
2172 void do_oop(oop* p) {
2173 oop obj = *p;
2174 if (obj != NULL) {
2175 if (_g1h->is_obj_dead(obj)) {
2176 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2177 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2178 obj->print_on(gclog_or_tty);
2179 _failures = true;
2180 }
2181 }
2182 }
2183 };
2184
2185 // This is the task used for parallel heap verification.
2186
2187 class G1ParVerifyTask: public AbstractGangTask {
2188 private:
2189 G1CollectedHeap* _g1h;
2190 bool _allow_dirty;
2191
2192 public:
2193 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty) :
2194 AbstractGangTask("Parallel verify task"),
2195 _g1h(g1h), _allow_dirty(allow_dirty) { }
2196
2197 void work(int worker_i) {
2198 VerifyRegionClosure blk(_allow_dirty, true);
2199 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2200 HeapRegion::ParVerifyClaimValue);
2201 }
2202 };
2203
2204 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2205 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2206 if (!silent) { gclog_or_tty->print("roots "); }
2207 VerifyRootsClosure rootsCl;
2208 process_strong_roots(false,
2209 SharedHeap::SO_AllClasses,
2210 &rootsCl,
2211 &rootsCl);
2212 rem_set()->invalidate(perm_gen()->used_region(), false);
2213 if (!silent) { gclog_or_tty->print("heapRegions "); }
2214 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2215 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2216 "sanity check");
2217
2218 G1ParVerifyTask task(this, allow_dirty);
2219 int n_workers = workers()->total_workers();
2220 set_par_threads(n_workers);
2221 workers()->run_task(&task);
2222 set_par_threads(0);
2223
2224 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2225 "sanity check");
2226
2227 reset_heap_region_claim_values();
2228
2229 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2230 "sanity check");
2231 } else {
2232 VerifyRegionClosure blk(allow_dirty);
2233 _hrs->iterate(&blk);
2234 }
2235 if (!silent) gclog_or_tty->print("remset ");
2236 rem_set()->verify();
2237 guarantee(!rootsCl.failures(), "should not have had failures");
2238 } else {
2239 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2240 }
2241 }
2242
2243 class PrintRegionClosure: public HeapRegionClosure {
2244 outputStream* _st;
2245 public:
2246 PrintRegionClosure(outputStream* st) : _st(st) {}
2247 bool doHeapRegion(HeapRegion* r) {
2248 r->print_on(_st);
2249 return false;
2250 }
2251 };
2252
2253 void G1CollectedHeap::print() const { print_on(gclog_or_tty); }
2254
2255 void G1CollectedHeap::print_on(outputStream* st) const {
2256 PrintRegionClosure blk(st);
2257 _hrs->iterate(&blk);
2258 }
2259
2260 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2261 if (ParallelGCThreads > 0) {
2262 workers()->print_worker_threads();
2263 }
2264 st->print("\"G1 concurrent mark GC Thread\" ");
2265 _cmThread->print();
2266 st->cr();
2267 st->print("\"G1 concurrent refinement GC Thread\" ");
2268 _cg1r->cg1rThread()->print_on(st);
2269 st->cr();
2270 st->print("\"G1 zero-fill GC Thread\" ");
2271 _czft->print_on(st);
2272 st->cr();
2273 }
2274
2275 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2276 if (ParallelGCThreads > 0) {
2277 workers()->threads_do(tc);
2278 }
2279 tc->do_thread(_cmThread);
2280 tc->do_thread(_cg1r->cg1rThread());
2281 tc->do_thread(_czft);
2282 }
2283
2284 void G1CollectedHeap::print_tracing_info() const {
2285 concurrent_g1_refine()->print_final_card_counts();
2286
2287 // We'll overload this to mean "trace GC pause statistics."
2288 if (TraceGen0Time || TraceGen1Time) {
2289 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2290 // to that.
2291 g1_policy()->print_tracing_info();
2292 }
2293 if (SummarizeG1RSStats) {
2294 g1_rem_set()->print_summary_info();
2295 }
2296 if (SummarizeG1ConcMark) {
2297 concurrent_mark()->print_summary_info();
2298 }
2299 if (SummarizeG1ZFStats) {
2300 ConcurrentZFThread::print_summary_info();
2301 }
2302 if (G1SummarizePopularity) {
2303 print_popularity_summary_info();
2304 }
2305 g1_policy()->print_yg_surv_rate_info();
2306
2307 GCOverheadReporter::printGCOverhead();
2308
2309 SpecializationStats::print();
2310 }
2311
2312
2313 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2314 HeapRegion* hr = heap_region_containing(addr);
2315 if (hr == NULL) {
2316 return 0;
2317 } else {
2318 return 1;
2319 }
2320 }
2321
2322 G1CollectedHeap* G1CollectedHeap::heap() {
2323 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2324 "not a garbage-first heap");
2325 return _g1h;
2326 }
2327
2328 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2329 if (PrintHeapAtGC){
2330 gclog_or_tty->print_cr(" {Heap before GC collections=%d:", total_collections());
2331 Universe::print();
2332 }
2333 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2334 // Call allocation profiler
2335 AllocationProfiler::iterate_since_last_gc();
2336 // Fill TLAB's and such
2337 ensure_parsability(true);
2338 }
2339
2340 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2341 // FIXME: what is this about?
2342 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2343 // is set.
2344 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2345 "derived pointer present"));
2346
2347 if (PrintHeapAtGC){
2348 gclog_or_tty->print_cr(" Heap after GC collections=%d:", total_collections());
2349 Universe::print();
2350 gclog_or_tty->print("} ");
2351 }
2352 }
2353
2354 void G1CollectedHeap::do_collection_pause() {
2355 // Read the GC count while holding the Heap_lock
2356 // we need to do this _before_ wait_for_cleanup_complete(), to
2357 // ensure that we do not give up the heap lock and potentially
2358 // pick up the wrong count
2359 int gc_count_before = SharedHeap::heap()->total_collections();
2360
2361 // Don't want to do a GC pause while cleanup is being completed!
2362 wait_for_cleanup_complete();
2363
2364 g1_policy()->record_stop_world_start();
2365 {
2366 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2367 VM_G1IncCollectionPause op(gc_count_before);
2368 VMThread::execute(&op);
2369 }
2370 }
2371
2372 void
2373 G1CollectedHeap::doConcurrentMark() {
2374 if (G1ConcMark) {
2375 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2376 if (!_cmThread->in_progress()) {
2377 _cmThread->set_started();
2378 CGC_lock->notify();
2379 }
2380 }
2381 }
2382
2383 class VerifyMarkedObjsClosure: public ObjectClosure {
2384 G1CollectedHeap* _g1h;
2385 public:
2386 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2387 void do_object(oop obj) {
2388 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2389 "markandsweep mark should agree with concurrent deadness");
2390 }
2391 };
2392
2393 void
2394 G1CollectedHeap::checkConcurrentMark() {
2395 VerifyMarkedObjsClosure verifycl(this);
2396 // MutexLockerEx x(getMarkBitMapLock(),
2397 // Mutex::_no_safepoint_check_flag);
2398 object_iterate(&verifycl);
2399 }
2400
2401 void G1CollectedHeap::do_sync_mark() {
2402 _cm->checkpointRootsInitial();
2403 _cm->markFromRoots();
2404 _cm->checkpointRootsFinal(false);
2405 }
2406
2407 // <NEW PREDICTION>
2408
2409 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2410 bool young) {
2411 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2412 }
2413
2414 void G1CollectedHeap::check_if_region_is_too_expensive(double
2415 predicted_time_ms) {
2416 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2417 }
2418
2419 size_t G1CollectedHeap::pending_card_num() {
2420 size_t extra_cards = 0;
2421 JavaThread *curr = Threads::first();
2422 while (curr != NULL) {
2423 DirtyCardQueue& dcq = curr->dirty_card_queue();
2424 extra_cards += dcq.size();
2425 curr = curr->next();
2426 }
2427 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2428 size_t buffer_size = dcqs.buffer_size();
2429 size_t buffer_num = dcqs.completed_buffers_num();
2430 return buffer_size * buffer_num + extra_cards;
2431 }
2432
2433 size_t G1CollectedHeap::max_pending_card_num() {
2434 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2435 size_t buffer_size = dcqs.buffer_size();
2436 size_t buffer_num = dcqs.completed_buffers_num();
2437 int thread_num = Threads::number_of_threads();
2438 return (buffer_num + thread_num) * buffer_size;
2439 }
2440
2441 size_t G1CollectedHeap::cards_scanned() {
2442 HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
2443 return g1_rset->cardsScanned();
2444 }
2445
2446 void
2447 G1CollectedHeap::setup_surviving_young_words() {
2448 guarantee( _surviving_young_words == NULL, "pre-condition" );
2449 size_t array_length = g1_policy()->young_cset_length();
2450 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2451 if (_surviving_young_words == NULL) {
2452 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2453 "Not enough space for young surv words summary.");
2454 }
2455 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2456 for (size_t i = 0; i < array_length; ++i) {
2457 guarantee( _surviving_young_words[i] == 0, "invariant" );
2458 }
2459 }
2460
2461 void
2462 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2463 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2464 size_t array_length = g1_policy()->young_cset_length();
2465 for (size_t i = 0; i < array_length; ++i)
2466 _surviving_young_words[i] += surv_young_words[i];
2467 }
2468
2469 void
2470 G1CollectedHeap::cleanup_surviving_young_words() {
2471 guarantee( _surviving_young_words != NULL, "pre-condition" );
2472 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2473 _surviving_young_words = NULL;
2474 }
2475
2476 // </NEW PREDICTION>
2477
2478 void
2479 G1CollectedHeap::do_collection_pause_at_safepoint(HeapRegion* popular_region) {
2480 char verbose_str[128];
2481 sprintf(verbose_str, "GC pause ");
2482 if (popular_region != NULL)
2483 strcat(verbose_str, "(popular)");
2484 else if (g1_policy()->in_young_gc_mode()) {
2485 if (g1_policy()->full_young_gcs())
2486 strcat(verbose_str, "(young)");
2487 else
2488 strcat(verbose_str, "(partial)");
2489 }
2490 bool reset_should_initiate_conc_mark = false;
2491 if (popular_region != NULL && g1_policy()->should_initiate_conc_mark()) {
2492 // we currently do not allow an initial mark phase to be piggy-backed
2493 // on a popular pause
2494 reset_should_initiate_conc_mark = true;
2495 g1_policy()->unset_should_initiate_conc_mark();
2496 }
2497 if (g1_policy()->should_initiate_conc_mark())
2498 strcat(verbose_str, " (initial-mark)");
2499
2500 GCCauseSetter x(this, (popular_region == NULL ?
2501 GCCause::_g1_inc_collection_pause :
2502 GCCause::_g1_pop_region_collection_pause));
2503
2504 // if PrintGCDetails is on, we'll print long statistics information
2505 // in the collector policy code, so let's not print this as the output
2506 // is messy if we do.
2507 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2508 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2509 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2510
2511 ResourceMark rm;
2512 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2513 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2514 guarantee(!is_gc_active(), "collection is not reentrant");
2515 assert(regions_accounted_for(), "Region leakage!");
2516
2517 increment_gc_time_stamp();
2518
2519 if (g1_policy()->in_young_gc_mode()) {
2520 assert(check_young_list_well_formed(),
2521 "young list should be well formed");
2522 }
2523
2524 if (GC_locker::is_active()) {
2525 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2526 }
2527
2528 bool abandoned = false;
2529 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2530 IsGCActiveMark x;
2531
2532 gc_prologue(false);
2533 increment_total_collections();
2534
2535 #if G1_REM_SET_LOGGING
2536 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2537 print();
2538 #endif
2539
2540 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2541 HandleMark hm; // Discard invalid handles created during verification
2542 prepare_for_verify();
2543 gclog_or_tty->print(" VerifyBeforeGC:");
2544 Universe::verify(false);
2545 }
2546
2547 COMPILER2_PRESENT(DerivedPointerTable::clear());
2548
2549 // We want to turn off ref discovery, if necessary, and turn it back on
2550 // on again later if we do.
2551 bool was_enabled = ref_processor()->discovery_enabled();
2552 if (was_enabled) ref_processor()->disable_discovery();
2553
2554 // Forget the current alloc region (we might even choose it to be part
2555 // of the collection set!).
2556 abandon_cur_alloc_region();
2557
2558 // The elapsed time induced by the start time below deliberately elides
2559 // the possible verification above.
2560 double start_time_sec = os::elapsedTime();
2561 GCOverheadReporter::recordSTWStart(start_time_sec);
2562 size_t start_used_bytes = used();
2563 if (!G1ConcMark) {
2564 do_sync_mark();
2565 }
2566
2567 g1_policy()->record_collection_pause_start(start_time_sec,
2568 start_used_bytes);
2569
2570 guarantee(_in_cset_fast_test == NULL, "invariant");
2571 guarantee(_in_cset_fast_test_base == NULL, "invariant");
2572 _in_cset_fast_test_length = max_regions();
2573 _in_cset_fast_test_base =
2574 NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2575 memset(_in_cset_fast_test_base, false,
2576 _in_cset_fast_test_length * sizeof(bool));
2577 // We're biasing _in_cset_fast_test to avoid subtracting the
2578 // beginning of the heap every time we want to index; basically
2579 // it's the same with what we do with the card table.
2580 _in_cset_fast_test = _in_cset_fast_test_base -
2581 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2582
2583 #if SCAN_ONLY_VERBOSE
2584 _young_list->print();
2585 #endif // SCAN_ONLY_VERBOSE
2586
2587 if (g1_policy()->should_initiate_conc_mark()) {
2588 concurrent_mark()->checkpointRootsInitialPre();
2589 }
2590 save_marks();
2591
2592 // We must do this before any possible evacuation that should propagate
2593 // marks, including evacuation of popular objects in a popular pause.
2594 if (mark_in_progress()) {
2595 double start_time_sec = os::elapsedTime();
2596
2597 _cm->drainAllSATBBuffers();
2598 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2599 g1_policy()->record_satb_drain_time(finish_mark_ms);
2600
2601 }
2602 // Record the number of elements currently on the mark stack, so we
2603 // only iterate over these. (Since evacuation may add to the mark
2604 // stack, doing more exposes race conditions.) If no mark is in
2605 // progress, this will be zero.
2606 _cm->set_oops_do_bound();
2607
2608 assert(regions_accounted_for(), "Region leakage.");
2609
2610 bool abandoned = false;
2611
2612 if (mark_in_progress())
2613 concurrent_mark()->newCSet();
2614
2615 // Now choose the CS.
2616 if (popular_region == NULL) {
2617 g1_policy()->choose_collection_set();
2618 } else {
2619 // We may be evacuating a single region (for popularity).
2620 g1_policy()->record_popular_pause_preamble_start();
2621 popularity_pause_preamble(popular_region);
2622 g1_policy()->record_popular_pause_preamble_end();
2623 abandoned = (g1_policy()->collection_set() == NULL);
2624 // Now we allow more regions to be added (we have to collect
2625 // all popular regions).
2626 if (!abandoned) {
2627 g1_policy()->choose_collection_set(popular_region);
2628 }
2629 }
2630 // We may abandon a pause if we find no region that will fit in the MMU
2631 // pause.
2632 abandoned = (g1_policy()->collection_set() == NULL);
2633
2634 // Nothing to do if we were unable to choose a collection set.
2635 if (!abandoned) {
2636 #if G1_REM_SET_LOGGING
2637 gclog_or_tty->print_cr("\nAfter pause, heap:");
2638 print();
2639 #endif
2640
2641 setup_surviving_young_words();
2642
2643 // Set up the gc allocation regions.
2644 get_gc_alloc_regions();
2645
2646 // Actually do the work...
2647 evacuate_collection_set();
2648 free_collection_set(g1_policy()->collection_set());
2649 g1_policy()->clear_collection_set();
2650
2651 FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base);
2652 // this is more for peace of mind; we're nulling them here and
2653 // we're expecting them to be null at the beginning of the next GC
2654 _in_cset_fast_test = NULL;
2655 _in_cset_fast_test_base = NULL;
2656
2657 if (popular_region != NULL) {
2658 // We have to wait until now, because we don't want the region to
2659 // be rescheduled for pop-evac during RS update.
2660 popular_region->set_popular_pending(false);
2661 }
2662
2663 release_gc_alloc_regions(false /* totally */);
2664
2665 cleanup_surviving_young_words();
2666
2667 if (g1_policy()->in_young_gc_mode()) {
2668 _young_list->reset_sampled_info();
2669 assert(check_young_list_empty(true),
2670 "young list should be empty");
2671
2672 #if SCAN_ONLY_VERBOSE
2673 _young_list->print();
2674 #endif // SCAN_ONLY_VERBOSE
2675
2676 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
2677 _young_list->first_survivor_region(),
2678 _young_list->last_survivor_region());
2679 _young_list->reset_auxilary_lists();
2680 }
2681 } else {
2682 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
2683 }
2684
2685 if (evacuation_failed()) {
2686 _summary_bytes_used = recalculate_used();
2687 } else {
2688 // The "used" of the the collection set have already been subtracted
2689 // when they were freed. Add in the bytes evacuated.
2690 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2691 }
2692
2693 if (g1_policy()->in_young_gc_mode() &&
2694 g1_policy()->should_initiate_conc_mark()) {
2695 concurrent_mark()->checkpointRootsInitialPost();
2696 set_marking_started();
2697 doConcurrentMark();
2698 }
2699
2700 #if SCAN_ONLY_VERBOSE
2701 _young_list->print();
2702 #endif // SCAN_ONLY_VERBOSE
2703
2704 double end_time_sec = os::elapsedTime();
2705 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
2706 g1_policy()->record_pause_time_ms(pause_time_ms);
2707 GCOverheadReporter::recordSTWEnd(end_time_sec);
2708 g1_policy()->record_collection_pause_end(popular_region != NULL,
2709 abandoned);
2710
2711 assert(regions_accounted_for(), "Region leakage.");
2712
2713 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
2714 HandleMark hm; // Discard invalid handles created during verification
2715 gclog_or_tty->print(" VerifyAfterGC:");
2716 Universe::verify(false);
2717 }
2718
2719 if (was_enabled) ref_processor()->enable_discovery();
2720
2721 {
2722 size_t expand_bytes = g1_policy()->expansion_amount();
2723 if (expand_bytes > 0) {
2724 size_t bytes_before = capacity();
2725 expand(expand_bytes);
2726 }
2727 }
2728
2729 if (mark_in_progress()) {
2730 concurrent_mark()->update_g1_committed();
2731 }
2732
2733 #ifdef TRACESPINNING
2734 ParallelTaskTerminator::print_termination_counts();
2735 #endif
2736
2737 gc_epilogue(false);
2738 }
2739
2740 assert(verify_region_lists(), "Bad region lists.");
2741
2742 if (reset_should_initiate_conc_mark)
2743 g1_policy()->set_should_initiate_conc_mark();
2744
2745 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
2746 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
2747 print_tracing_info();
2748 vm_exit(-1);
2749 }
2750 }
2751
2752 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
2753 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
2754 // make sure we don't call set_gc_alloc_region() multiple times on
2755 // the same region
2756 assert(r == NULL || !r->is_gc_alloc_region(),
2757 "shouldn't already be a GC alloc region");
2758 HeapWord* original_top = NULL;
2759 if (r != NULL)
2760 original_top = r->top();
2761
2762 // We will want to record the used space in r as being there before gc.
2763 // One we install it as a GC alloc region it's eligible for allocation.
2764 // So record it now and use it later.
2765 size_t r_used = 0;
2766 if (r != NULL) {
2767 r_used = r->used();
2768
2769 if (ParallelGCThreads > 0) {
2770 // need to take the lock to guard against two threads calling
2771 // get_gc_alloc_region concurrently (very unlikely but...)
2772 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2773 r->save_marks();
2774 }
2775 }
2776 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
2777 _gc_alloc_regions[purpose] = r;
2778 if (old_alloc_region != NULL) {
2779 // Replace aliases too.
2780 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2781 if (_gc_alloc_regions[ap] == old_alloc_region) {
2782 _gc_alloc_regions[ap] = r;
2783 }
2784 }
2785 }
2786 if (r != NULL) {
2787 push_gc_alloc_region(r);
2788 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
2789 // We are using a region as a GC alloc region after it has been used
2790 // as a mutator allocation region during the current marking cycle.
2791 // The mutator-allocated objects are currently implicitly marked, but
2792 // when we move hr->next_top_at_mark_start() forward at the the end
2793 // of the GC pause, they won't be. We therefore mark all objects in
2794 // the "gap". We do this object-by-object, since marking densely
2795 // does not currently work right with marking bitmap iteration. This
2796 // means we rely on TLAB filling at the start of pauses, and no
2797 // "resuscitation" of filled TLAB's. If we want to do this, we need
2798 // to fix the marking bitmap iteration.
2799 HeapWord* curhw = r->next_top_at_mark_start();
2800 HeapWord* t = original_top;
2801
2802 while (curhw < t) {
2803 oop cur = (oop)curhw;
2804 // We'll assume parallel for generality. This is rare code.
2805 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
2806 curhw = curhw + cur->size();
2807 }
2808 assert(curhw == t, "Should have parsed correctly.");
2809 }
2810 if (G1PolicyVerbose > 1) {
2811 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
2812 "for survivors:", r->bottom(), original_top, r->end());
2813 r->print();
2814 }
2815 g1_policy()->record_before_bytes(r_used);
2816 }
2817 }
2818
2819 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
2820 assert(Thread::current()->is_VM_thread() ||
2821 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
2822 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
2823 "Precondition.");
2824 hr->set_is_gc_alloc_region(true);
2825 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
2826 _gc_alloc_region_list = hr;
2827 }
2828
2829 #ifdef G1_DEBUG
2830 class FindGCAllocRegion: public HeapRegionClosure {
2831 public:
2832 bool doHeapRegion(HeapRegion* r) {
2833 if (r->is_gc_alloc_region()) {
2834 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
2835 r->hrs_index(), r->bottom());
2836 }
2837 return false;
2838 }
2839 };
2840 #endif // G1_DEBUG
2841
2842 void G1CollectedHeap::forget_alloc_region_list() {
2843 assert(Thread::current()->is_VM_thread(), "Precondition");
2844 while (_gc_alloc_region_list != NULL) {
2845 HeapRegion* r = _gc_alloc_region_list;
2846 assert(r->is_gc_alloc_region(), "Invariant.");
2847 _gc_alloc_region_list = r->next_gc_alloc_region();
2848 r->set_next_gc_alloc_region(NULL);
2849 r->set_is_gc_alloc_region(false);
2850 if (r->is_survivor()) {
2851 if (r->is_empty()) {
2852 r->set_not_young();
2853 } else {
2854 _young_list->add_survivor_region(r);
2855 }
2856 }
2857 if (r->is_empty()) {
2858 ++_free_regions;
2859 }
2860 }
2861 #ifdef G1_DEBUG
2862 FindGCAllocRegion fa;
2863 heap_region_iterate(&fa);
2864 #endif // G1_DEBUG
2865 }
2866
2867
2868 bool G1CollectedHeap::check_gc_alloc_regions() {
2869 // TODO: allocation regions check
2870 return true;
2871 }
2872
2873 void G1CollectedHeap::get_gc_alloc_regions() {
2874 // First, let's check that the GC alloc region list is empty (it should)
2875 assert(_gc_alloc_region_list == NULL, "invariant");
2876
2877 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2878 assert(_gc_alloc_regions[ap] == NULL, "invariant");
2879
2880 // Create new GC alloc regions.
2881 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
2882 _retained_gc_alloc_regions[ap] = NULL;
2883
2884 if (alloc_region != NULL) {
2885 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
2886
2887 // let's make sure that the GC alloc region is not tagged as such
2888 // outside a GC operation
2889 assert(!alloc_region->is_gc_alloc_region(), "sanity");
2890
2891 if (alloc_region->in_collection_set() ||
2892 alloc_region->top() == alloc_region->end() ||
2893 alloc_region->top() == alloc_region->bottom()) {
2894 // we will discard the current GC alloc region if it's in the
2895 // collection set (it can happen!), if it's already full (no
2896 // point in using it), or if it's empty (this means that it
2897 // was emptied during a cleanup and it should be on the free
2898 // list now).
2899
2900 alloc_region = NULL;
2901 }
2902 }
2903
2904 if (alloc_region == NULL) {
2905 // we will get a new GC alloc region
2906 alloc_region = newAllocRegionWithExpansion(ap, 0);
2907 }
2908
2909 if (alloc_region != NULL) {
2910 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
2911 set_gc_alloc_region(ap, alloc_region);
2912 }
2913
2914 assert(_gc_alloc_regions[ap] == NULL ||
2915 _gc_alloc_regions[ap]->is_gc_alloc_region(),
2916 "the GC alloc region should be tagged as such");
2917 assert(_gc_alloc_regions[ap] == NULL ||
2918 _gc_alloc_regions[ap] == _gc_alloc_region_list,
2919 "the GC alloc region should be the same as the GC alloc list head");
2920 }
2921 // Set alternative regions for allocation purposes that have reached
2922 // their limit.
2923 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2924 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
2925 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
2926 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
2927 }
2928 }
2929 assert(check_gc_alloc_regions(), "alloc regions messed up");
2930 }
2931
2932 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
2933 // We keep a separate list of all regions that have been alloc regions in
2934 // the current collection pause. Forget that now. This method will
2935 // untag the GC alloc regions and tear down the GC alloc region
2936 // list. It's desirable that no regions are tagged as GC alloc
2937 // outside GCs.
2938 forget_alloc_region_list();
2939
2940 // The current alloc regions contain objs that have survived
2941 // collection. Make them no longer GC alloc regions.
2942 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2943 HeapRegion* r = _gc_alloc_regions[ap];
2944 _retained_gc_alloc_regions[ap] = NULL;
2945
2946 if (r != NULL) {
2947 // we retain nothing on _gc_alloc_regions between GCs
2948 set_gc_alloc_region(ap, NULL);
2949 _gc_alloc_region_counts[ap] = 0;
2950
2951 if (r->is_empty()) {
2952 // we didn't actually allocate anything in it; let's just put
2953 // it on the free list
2954 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
2955 r->set_zero_fill_complete();
2956 put_free_region_on_list_locked(r);
2957 } else if (_retain_gc_alloc_region[ap] && !totally) {
2958 // retain it so that we can use it at the beginning of the next GC
2959 _retained_gc_alloc_regions[ap] = r;
2960 }
2961 }
2962 }
2963 }
2964
2965 #ifndef PRODUCT
2966 // Useful for debugging
2967
2968 void G1CollectedHeap::print_gc_alloc_regions() {
2969 gclog_or_tty->print_cr("GC alloc regions");
2970 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2971 HeapRegion* r = _gc_alloc_regions[ap];
2972 if (r == NULL) {
2973 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
2974 } else {
2975 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
2976 ap, r->bottom(), r->used());
2977 }
2978 }
2979 }
2980 #endif // PRODUCT
2981
2982 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
2983 _drain_in_progress = false;
2984 set_evac_failure_closure(cl);
2985 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
2986 }
2987
2988 void G1CollectedHeap::finalize_for_evac_failure() {
2989 assert(_evac_failure_scan_stack != NULL &&
2990 _evac_failure_scan_stack->length() == 0,
2991 "Postcondition");
2992 assert(!_drain_in_progress, "Postcondition");
2993 // Don't have to delete, since the scan stack is a resource object.
2994 _evac_failure_scan_stack = NULL;
2995 }
2996
2997
2998
2999 // *** Sequential G1 Evacuation
3000
3001 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
3002 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3003 // let the caller handle alloc failure
3004 if (alloc_region == NULL) return NULL;
3005 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
3006 "Either the object is humongous or the region isn't");
3007 HeapWord* block = alloc_region->allocate(word_size);
3008 if (block == NULL) {
3009 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
3010 }
3011 return block;
3012 }
3013
3014 class G1IsAliveClosure: public BoolObjectClosure {
3015 G1CollectedHeap* _g1;
3016 public:
3017 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3018 void do_object(oop p) { assert(false, "Do not call."); }
3019 bool do_object_b(oop p) {
3020 // It is reachable if it is outside the collection set, or is inside
3021 // and forwarded.
3022
3023 #ifdef G1_DEBUG
3024 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3025 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3026 !_g1->obj_in_cs(p) || p->is_forwarded());
3027 #endif // G1_DEBUG
3028
3029 return !_g1->obj_in_cs(p) || p->is_forwarded();
3030 }
3031 };
3032
3033 class G1KeepAliveClosure: public OopClosure {
3034 G1CollectedHeap* _g1;
3035 public:
3036 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3037 void do_oop(narrowOop* p) {
3038 guarantee(false, "NYI");
3039 }
3040 void do_oop(oop* p) {
3041 oop obj = *p;
3042 #ifdef G1_DEBUG
3043 if (PrintGC && Verbose) {
3044 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3045 p, (void*) obj, (void*) *p);
3046 }
3047 #endif // G1_DEBUG
3048
3049 if (_g1->obj_in_cs(obj)) {
3050 assert( obj->is_forwarded(), "invariant" );
3051 *p = obj->forwardee();
3052
3053 #ifdef G1_DEBUG
3054 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3055 (void*) obj, (void*) *p);
3056 #endif // G1_DEBUG
3057 }
3058 }
3059 };
3060
3061 class UpdateRSetImmediate : public OopsInHeapRegionClosure {
3062 private:
3063 G1CollectedHeap* _g1;
3064 G1RemSet* _g1_rem_set;
3065 public:
3066 UpdateRSetImmediate(G1CollectedHeap* g1) :
3067 _g1(g1), _g1_rem_set(g1->g1_rem_set()) {}
3068
3069 void do_oop(narrowOop* p) {
3070 guarantee(false, "NYI");
3071 }
3072 void do_oop(oop* p) {
3073 assert(_from->is_in_reserved(p), "paranoia");
3074 if (*p != NULL && !_from->is_survivor()) {
3075 _g1_rem_set->par_write_ref(_from, p, 0);
3076 }
3077 }
3078 };
3079
3080 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3081 private:
3082 G1CollectedHeap* _g1;
3083 DirtyCardQueue *_dcq;
3084 CardTableModRefBS* _ct_bs;
3085
3086 public:
3087 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3088 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3089
3090 void do_oop(narrowOop* p) {
3091 guarantee(false, "NYI");
3092 }
3093 void do_oop(oop* p) {
3094 assert(_from->is_in_reserved(p), "paranoia");
3095 if (!_from->is_in_reserved(*p) && !_from->is_survivor()) {
3096 size_t card_index = _ct_bs->index_for(p);
3097 if (_ct_bs->mark_card_deferred(card_index)) {
3098 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3099 }
3100 }
3101 }
3102 };
3103
3104
3105
3106 class RemoveSelfPointerClosure: public ObjectClosure {
3107 private:
3108 G1CollectedHeap* _g1;
3109 ConcurrentMark* _cm;
3110 HeapRegion* _hr;
3111 size_t _prev_marked_bytes;
3112 size_t _next_marked_bytes;
3113 OopsInHeapRegionClosure *_cl;
3114 public:
3115 RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
3116 _g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3117 _next_marked_bytes(0), _cl(cl) {}
3118
3119 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3120 size_t next_marked_bytes() { return _next_marked_bytes; }
3121
3122 // The original idea here was to coalesce evacuated and dead objects.
3123 // However that caused complications with the block offset table (BOT).
3124 // In particular if there were two TLABs, one of them partially refined.
3125 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3126 // The BOT entries of the unrefined part of TLAB_2 point to the start
3127 // of TLAB_2. If the last object of the TLAB_1 and the first object
3128 // of TLAB_2 are coalesced, then the cards of the unrefined part
3129 // would point into middle of the filler object.
3130 //
3131 // The current approach is to not coalesce and leave the BOT contents intact.
3132 void do_object(oop obj) {
3133 if (obj->is_forwarded() && obj->forwardee() == obj) {
3134 // The object failed to move.
3135 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3136 _cm->markPrev(obj);
3137 assert(_cm->isPrevMarked(obj), "Should be marked!");
3138 _prev_marked_bytes += (obj->size() * HeapWordSize);
3139 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3140 _cm->markAndGrayObjectIfNecessary(obj);
3141 }
3142 obj->set_mark(markOopDesc::prototype());
3143 // While we were processing RSet buffers during the
3144 // collection, we actually didn't scan any cards on the
3145 // collection set, since we didn't want to update remebered
3146 // sets with entries that point into the collection set, given
3147 // that live objects fromthe collection set are about to move
3148 // and such entries will be stale very soon. This change also
3149 // dealt with a reliability issue which involved scanning a
3150 // card in the collection set and coming across an array that
3151 // was being chunked and looking malformed. The problem is
3152 // that, if evacuation fails, we might have remembered set
3153 // entries missing given that we skipped cards on the
3154 // collection set. So, we'll recreate such entries now.
3155 obj->oop_iterate(_cl);
3156 assert(_cm->isPrevMarked(obj), "Should be marked!");
3157 } else {
3158 // The object has been either evacuated or is dead. Fill it with a
3159 // dummy object.
3160 MemRegion mr((HeapWord*)obj, obj->size());
3161 CollectedHeap::fill_with_object(mr);
3162 _cm->clearRangeBothMaps(mr);
3163 }
3164 }
3165 };
3166
3167 void G1CollectedHeap::remove_self_forwarding_pointers() {
3168 UpdateRSetImmediate immediate_update(_g1h);
3169 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3170 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3171 OopsInHeapRegionClosure *cl;
3172 if (G1DeferredRSUpdate) {
3173 cl = &deferred_update;
3174 } else {
3175 cl = &immediate_update;
3176 }
3177 HeapRegion* cur = g1_policy()->collection_set();
3178 while (cur != NULL) {
3179 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3180
3181 RemoveSelfPointerClosure rspc(_g1h, cl);
3182 if (cur->evacuation_failed()) {
3183 assert(cur->in_collection_set(), "bad CS");
3184 cl->set_region(cur);
3185 cur->object_iterate(&rspc);
3186
3187 // A number of manipulations to make the TAMS be the current top,
3188 // and the marked bytes be the ones observed in the iteration.
3189 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3190 // The comments below are the postconditions achieved by the
3191 // calls. Note especially the last such condition, which says that
3192 // the count of marked bytes has been properly restored.
3193 cur->note_start_of_marking(false);
3194 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3195 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3196 // _next_marked_bytes == prev_marked_bytes.
3197 cur->note_end_of_marking();
3198 // _prev_top_at_mark_start == top(),
3199 // _prev_marked_bytes == prev_marked_bytes
3200 }
3201 // If there is no mark in progress, we modified the _next variables
3202 // above needlessly, but harmlessly.
3203 if (_g1h->mark_in_progress()) {
3204 cur->note_start_of_marking(false);
3205 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3206 // _next_marked_bytes == next_marked_bytes.
3207 }
3208
3209 // Now make sure the region has the right index in the sorted array.
3210 g1_policy()->note_change_in_marked_bytes(cur);
3211 }
3212 cur = cur->next_in_collection_set();
3213 }
3214 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3215
3216 // Now restore saved marks, if any.
3217 if (_objs_with_preserved_marks != NULL) {
3218 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3219 assert(_objs_with_preserved_marks->length() ==
3220 _preserved_marks_of_objs->length(), "Both or none.");
3221 guarantee(_objs_with_preserved_marks->length() ==
3222 _preserved_marks_of_objs->length(), "Both or none.");
3223 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3224 oop obj = _objs_with_preserved_marks->at(i);
3225 markOop m = _preserved_marks_of_objs->at(i);
3226 obj->set_mark(m);
3227 }
3228 // Delete the preserved marks growable arrays (allocated on the C heap).
3229 delete _objs_with_preserved_marks;
3230 delete _preserved_marks_of_objs;
3231 _objs_with_preserved_marks = NULL;
3232 _preserved_marks_of_objs = NULL;
3233 }
3234 }
3235
3236 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3237 _evac_failure_scan_stack->push(obj);
3238 }
3239
3240 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3241 assert(_evac_failure_scan_stack != NULL, "precondition");
3242
3243 while (_evac_failure_scan_stack->length() > 0) {
3244 oop obj = _evac_failure_scan_stack->pop();
3245 _evac_failure_closure->set_region(heap_region_containing(obj));
3246 obj->oop_iterate_backwards(_evac_failure_closure);
3247 }
3248 }
3249
3250 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3251 markOop m = old->mark();
3252 // forward to self
3253 assert(!old->is_forwarded(), "precondition");
3254
3255 old->forward_to(old);
3256 handle_evacuation_failure_common(old, m);
3257 }
3258
3259 oop
3260 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3261 oop old) {
3262 markOop m = old->mark();
3263 oop forward_ptr = old->forward_to_atomic(old);
3264 if (forward_ptr == NULL) {
3265 // Forward-to-self succeeded.
3266 if (_evac_failure_closure != cl) {
3267 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3268 assert(!_drain_in_progress,
3269 "Should only be true while someone holds the lock.");
3270 // Set the global evac-failure closure to the current thread's.
3271 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3272 set_evac_failure_closure(cl);
3273 // Now do the common part.
3274 handle_evacuation_failure_common(old, m);
3275 // Reset to NULL.
3276 set_evac_failure_closure(NULL);
3277 } else {
3278 // The lock is already held, and this is recursive.
3279 assert(_drain_in_progress, "This should only be the recursive case.");
3280 handle_evacuation_failure_common(old, m);
3281 }
3282 return old;
3283 } else {
3284 // Someone else had a place to copy it.
3285 return forward_ptr;
3286 }
3287 }
3288
3289 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3290 set_evacuation_failed(true);
3291
3292 preserve_mark_if_necessary(old, m);
3293
3294 HeapRegion* r = heap_region_containing(old);
3295 if (!r->evacuation_failed()) {
3296 r->set_evacuation_failed(true);
3297 if (G1TraceRegions) {
3298 gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
3299 "["PTR_FORMAT","PTR_FORMAT")\n",
3300 r, r->bottom(), r->end());
3301 }
3302 }
3303
3304 push_on_evac_failure_scan_stack(old);
3305
3306 if (!_drain_in_progress) {
3307 // prevent recursion in copy_to_survivor_space()
3308 _drain_in_progress = true;
3309 drain_evac_failure_scan_stack();
3310 _drain_in_progress = false;
3311 }
3312 }
3313
3314 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3315 if (m != markOopDesc::prototype()) {
3316 if (_objs_with_preserved_marks == NULL) {
3317 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3318 _objs_with_preserved_marks =
3319 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3320 _preserved_marks_of_objs =
3321 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3322 }
3323 _objs_with_preserved_marks->push(obj);
3324 _preserved_marks_of_objs->push(m);
3325 }
3326 }
3327
3328 // *** Parallel G1 Evacuation
3329
3330 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3331 size_t word_size) {
3332 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3333 // let the caller handle alloc failure
3334 if (alloc_region == NULL) return NULL;
3335
3336 HeapWord* block = alloc_region->par_allocate(word_size);
3337 if (block == NULL) {
3338 MutexLockerEx x(par_alloc_during_gc_lock(),
3339 Mutex::_no_safepoint_check_flag);
3340 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3341 }
3342 return block;
3343 }
3344
3345 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
3346 bool par) {
3347 // Another thread might have obtained alloc_region for the given
3348 // purpose, and might be attempting to allocate in it, and might
3349 // succeed. Therefore, we can't do the "finalization" stuff on the
3350 // region below until we're sure the last allocation has happened.
3351 // We ensure this by allocating the remaining space with a garbage
3352 // object.
3353 if (par) par_allocate_remaining_space(alloc_region);
3354 // Now we can do the post-GC stuff on the region.
3355 alloc_region->note_end_of_copying();
3356 g1_policy()->record_after_bytes(alloc_region->used());
3357 }
3358
3359 HeapWord*
3360 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3361 HeapRegion* alloc_region,
3362 bool par,
3363 size_t word_size) {
3364 HeapWord* block = NULL;
3365 // In the parallel case, a previous thread to obtain the lock may have
3366 // already assigned a new gc_alloc_region.
3367 if (alloc_region != _gc_alloc_regions[purpose]) {
3368 assert(par, "But should only happen in parallel case.");
3369 alloc_region = _gc_alloc_regions[purpose];
3370 if (alloc_region == NULL) return NULL;
3371 block = alloc_region->par_allocate(word_size);
3372 if (block != NULL) return block;
3373 // Otherwise, continue; this new region is empty, too.
3374 }
3375 assert(alloc_region != NULL, "We better have an allocation region");
3376 retire_alloc_region(alloc_region, par);
3377
3378 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3379 // Cannot allocate more regions for the given purpose.
3380 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3381 // Is there an alternative?
3382 if (purpose != alt_purpose) {
3383 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3384 // Has not the alternative region been aliased?
3385 if (alloc_region != alt_region && alt_region != NULL) {
3386 // Try to allocate in the alternative region.
3387 if (par) {
3388 block = alt_region->par_allocate(word_size);
3389 } else {
3390 block = alt_region->allocate(word_size);
3391 }
3392 // Make an alias.
3393 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3394 if (block != NULL) {
3395 return block;
3396 }
3397 retire_alloc_region(alt_region, par);
3398 }
3399 // Both the allocation region and the alternative one are full
3400 // and aliased, replace them with a new allocation region.
3401 purpose = alt_purpose;
3402 } else {
3403 set_gc_alloc_region(purpose, NULL);
3404 return NULL;
3405 }
3406 }
3407
3408 // Now allocate a new region for allocation.
3409 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3410
3411 // let the caller handle alloc failure
3412 if (alloc_region != NULL) {
3413
3414 assert(check_gc_alloc_regions(), "alloc regions messed up");
3415 assert(alloc_region->saved_mark_at_top(),
3416 "Mark should have been saved already.");
3417 // We used to assert that the region was zero-filled here, but no
3418 // longer.
3419
3420 // This must be done last: once it's installed, other regions may
3421 // allocate in it (without holding the lock.)
3422 set_gc_alloc_region(purpose, alloc_region);
3423
3424 if (par) {
3425 block = alloc_region->par_allocate(word_size);
3426 } else {
3427 block = alloc_region->allocate(word_size);
3428 }
3429 // Caller handles alloc failure.
3430 } else {
3431 // This sets other apis using the same old alloc region to NULL, also.
3432 set_gc_alloc_region(purpose, NULL);
3433 }
3434 return block; // May be NULL.
3435 }
3436
3437 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3438 HeapWord* block = NULL;
3439 size_t free_words;
3440 do {
3441 free_words = r->free()/HeapWordSize;
3442 // If there's too little space, no one can allocate, so we're done.
3443 if (free_words < (size_t)oopDesc::header_size()) return;
3444 // Otherwise, try to claim it.
3445 block = r->par_allocate(free_words);
3446 } while (block == NULL);
3447 fill_with_object(block, free_words);
3448 }
3449
3450 #define use_local_bitmaps 1
3451 #define verify_local_bitmaps 0
3452
3453 #ifndef PRODUCT
3454
3455 class GCLabBitMap;
3456 class GCLabBitMapClosure: public BitMapClosure {
3457 private:
3458 ConcurrentMark* _cm;
3459 GCLabBitMap* _bitmap;
3460
3461 public:
3462 GCLabBitMapClosure(ConcurrentMark* cm,
3463 GCLabBitMap* bitmap) {
3464 _cm = cm;
3465 _bitmap = bitmap;
3466 }
3467
3468 virtual bool do_bit(size_t offset);
3469 };
3470
3471 #endif // PRODUCT
3472
3473 #define oop_buffer_length 256
3474
3475 class GCLabBitMap: public BitMap {
3476 private:
3477 ConcurrentMark* _cm;
3478
3479 int _shifter;
3480 size_t _bitmap_word_covers_words;
3481
3482 // beginning of the heap
3483 HeapWord* _heap_start;
3484
3485 // this is the actual start of the GCLab
3486 HeapWord* _real_start_word;
3487
3488 // this is the actual end of the GCLab
3489 HeapWord* _real_end_word;
3490
3491 // this is the first word, possibly located before the actual start
3492 // of the GCLab, that corresponds to the first bit of the bitmap
3493 HeapWord* _start_word;
3494
3495 // size of a GCLab in words
3496 size_t _gclab_word_size;
3497
3498 static int shifter() {
3499 return MinObjAlignment - 1;
3500 }
3501
3502 // how many heap words does a single bitmap word corresponds to?
3503 static size_t bitmap_word_covers_words() {
3504 return BitsPerWord << shifter();
3505 }
3506
3507 static size_t gclab_word_size() {
3508 return ParallelGCG1AllocBufferSize / HeapWordSize;
3509 }
3510
3511 static size_t bitmap_size_in_bits() {
3512 size_t bits_in_bitmap = gclab_word_size() >> shifter();
3513 // We are going to ensure that the beginning of a word in this
3514 // bitmap also corresponds to the beginning of a word in the
3515 // global marking bitmap. To handle the case where a GCLab
3516 // starts from the middle of the bitmap, we need to add enough
3517 // space (i.e. up to a bitmap word) to ensure that we have
3518 // enough bits in the bitmap.
3519 return bits_in_bitmap + BitsPerWord - 1;
3520 }
3521 public:
3522 GCLabBitMap(HeapWord* heap_start)
3523 : BitMap(bitmap_size_in_bits()),
3524 _cm(G1CollectedHeap::heap()->concurrent_mark()),
3525 _shifter(shifter()),
3526 _bitmap_word_covers_words(bitmap_word_covers_words()),
3527 _heap_start(heap_start),
3528 _gclab_word_size(gclab_word_size()),
3529 _real_start_word(NULL),
3530 _real_end_word(NULL),
3531 _start_word(NULL)
3532 {
3533 guarantee( size_in_words() >= bitmap_size_in_words(),
3534 "just making sure");
3535 }
3536
3537 inline unsigned heapWordToOffset(HeapWord* addr) {
3538 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
3539 assert(offset < size(), "offset should be within bounds");
3540 return offset;
3541 }
3542
3543 inline HeapWord* offsetToHeapWord(size_t offset) {
3544 HeapWord* addr = _start_word + (offset << _shifter);
3545 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
3546 return addr;
3547 }
3548
3549 bool fields_well_formed() {
3550 bool ret1 = (_real_start_word == NULL) &&
3551 (_real_end_word == NULL) &&
3552 (_start_word == NULL);
3553 if (ret1)
3554 return true;
3555
3556 bool ret2 = _real_start_word >= _start_word &&
3557 _start_word < _real_end_word &&
3558 (_real_start_word + _gclab_word_size) == _real_end_word &&
3559 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
3560 > _real_end_word;
3561 return ret2;
3562 }
3563
3564 inline bool mark(HeapWord* addr) {
3565 guarantee(use_local_bitmaps, "invariant");
3566 assert(fields_well_formed(), "invariant");
3567
3568 if (addr >= _real_start_word && addr < _real_end_word) {
3569 assert(!isMarked(addr), "should not have already been marked");
3570
3571 // first mark it on the bitmap
3572 at_put(heapWordToOffset(addr), true);
3573
3574 return true;
3575 } else {
3576 return false;
3577 }
3578 }
3579
3580 inline bool isMarked(HeapWord* addr) {
3581 guarantee(use_local_bitmaps, "invariant");
3582 assert(fields_well_formed(), "invariant");
3583
3584 return at(heapWordToOffset(addr));
3585 }
3586
3587 void set_buffer(HeapWord* start) {
3588 guarantee(use_local_bitmaps, "invariant");
3589 clear();
3590
3591 assert(start != NULL, "invariant");
3592 _real_start_word = start;
3593 _real_end_word = start + _gclab_word_size;
3594
3595 size_t diff =
3596 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
3597 _start_word = start - diff;
3598
3599 assert(fields_well_formed(), "invariant");
3600 }
3601
3602 #ifndef PRODUCT
3603 void verify() {
3604 // verify that the marks have been propagated
3605 GCLabBitMapClosure cl(_cm, this);
3606 iterate(&cl);
3607 }
3608 #endif // PRODUCT
3609
3610 void retire() {
3611 guarantee(use_local_bitmaps, "invariant");
3612 assert(fields_well_formed(), "invariant");
3613
3614 if (_start_word != NULL) {
3615 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
3616
3617 // this means that the bitmap was set up for the GCLab
3618 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
3619
3620 mark_bitmap->mostly_disjoint_range_union(this,
3621 0, // always start from the start of the bitmap
3622 _start_word,
3623 size_in_words());
3624 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
3625
3626 #ifndef PRODUCT
3627 if (use_local_bitmaps && verify_local_bitmaps)
3628 verify();
3629 #endif // PRODUCT
3630 } else {
3631 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
3632 }
3633 }
3634
3635 static size_t bitmap_size_in_words() {
3636 return (bitmap_size_in_bits() + BitsPerWord - 1) / BitsPerWord;
3637 }
3638 };
3639
3640 #ifndef PRODUCT
3641
3642 bool GCLabBitMapClosure::do_bit(size_t offset) {
3643 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3644 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3645 return true;
3646 }
3647
3648 #endif // PRODUCT
3649
3650 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
3651 private:
3652 bool _retired;
3653 bool _during_marking;
3654 GCLabBitMap _bitmap;
3655
3656 public:
3657 G1ParGCAllocBuffer() :
3658 ParGCAllocBuffer(ParallelGCG1AllocBufferSize / HeapWordSize),
3659 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
3660 _bitmap(G1CollectedHeap::heap()->reserved_region().start()),
3661 _retired(false)
3662 { }
3663
3664 inline bool mark(HeapWord* addr) {
3665 guarantee(use_local_bitmaps, "invariant");
3666 assert(_during_marking, "invariant");
3667 return _bitmap.mark(addr);
3668 }
3669
3670 inline void set_buf(HeapWord* buf) {
3671 if (use_local_bitmaps && _during_marking)
3672 _bitmap.set_buffer(buf);
3673 ParGCAllocBuffer::set_buf(buf);
3674 _retired = false;
3675 }
3676
3677 inline void retire(bool end_of_gc, bool retain) {
3678 if (_retired)
3679 return;
3680 if (use_local_bitmaps && _during_marking) {
3681 _bitmap.retire();
3682 }
3683 ParGCAllocBuffer::retire(end_of_gc, retain);
3684 _retired = true;
3685 }
3686 };
3687
3688
3689 class G1ParScanThreadState : public StackObj {
3690 protected:
3691 G1CollectedHeap* _g1h;
3692 RefToScanQueue* _refs;
3693 DirtyCardQueue _dcq;
3694 CardTableModRefBS* _ct_bs;
3695 G1RemSet* _g1_rem;
3696
3697 typedef GrowableArray<oop*> OverflowQueue;
3698 OverflowQueue* _overflowed_refs;
3699
3700 G1ParGCAllocBuffer _alloc_buffers[GCAllocPurposeCount];
3701 ageTable _age_table;
3702
3703 size_t _alloc_buffer_waste;
3704 size_t _undo_waste;
3705
3706 OopsInHeapRegionClosure* _evac_failure_cl;
3707 G1ParScanHeapEvacClosure* _evac_cl;
3708 G1ParScanPartialArrayClosure* _partial_scan_cl;
3709
3710 int _hash_seed;
3711 int _queue_num;
3712
3713 int _term_attempts;
3714 #if G1_DETAILED_STATS
3715 int _pushes, _pops, _steals, _steal_attempts;
3716 int _overflow_pushes;
3717 #endif
3718
3719 double _start;
3720 double _start_strong_roots;
3721 double _strong_roots_time;
3722 double _start_term;
3723 double _term_time;
3724
3725 // Map from young-age-index (0 == not young, 1 is youngest) to
3726 // surviving words. base is what we get back from the malloc call
3727 size_t* _surviving_young_words_base;
3728 // this points into the array, as we use the first few entries for padding
3729 size_t* _surviving_young_words;
3730
3731 #define PADDING_ELEM_NUM (64 / sizeof(size_t))
3732
3733 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
3734
3735 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
3736
3737 DirtyCardQueue& dirty_card_queue() { return _dcq; }
3738 CardTableModRefBS* ctbs() { return _ct_bs; }
3739
3740 void immediate_rs_update(HeapRegion* from, oop* p, int tid) {
3741 _g1_rem->par_write_ref(from, p, tid);
3742 }
3743
3744 void deferred_rs_update(HeapRegion* from, oop* p, int tid) {
3745 // If the new value of the field points to the same region or
3746 // is the to-space, we don't need to include it in the Rset updates.
3747 if (!from->is_in_reserved(*p) && !from->is_survivor()) {
3748 size_t card_index = ctbs()->index_for(p);
3749 // If the card hasn't been added to the buffer, do it.
3750 if (ctbs()->mark_card_deferred(card_index)) {
3751 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
3752 }
3753 }
3754 }
3755
3756 public:
3757 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3758 : _g1h(g1h),
3759 _refs(g1h->task_queue(queue_num)),
3760 _dcq(&g1h->dirty_card_queue_set()),
3761 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
3762 _g1_rem(g1h->g1_rem_set()),
3763 _hash_seed(17), _queue_num(queue_num),
3764 _term_attempts(0),
3765 _age_table(false),
3766 #if G1_DETAILED_STATS
3767 _pushes(0), _pops(0), _steals(0),
3768 _steal_attempts(0), _overflow_pushes(0),
3769 #endif
3770 _strong_roots_time(0), _term_time(0),
3771 _alloc_buffer_waste(0), _undo_waste(0)
3772 {
3773 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3774 // we "sacrifice" entry 0 to keep track of surviving bytes for
3775 // non-young regions (where the age is -1)
3776 // We also add a few elements at the beginning and at the end in
3777 // an attempt to eliminate cache contention
3778 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3779 size_t array_length = PADDING_ELEM_NUM +
3780 real_length +
3781 PADDING_ELEM_NUM;
3782 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3783 if (_surviving_young_words_base == NULL)
3784 vm_exit_out_of_memory(array_length * sizeof(size_t),
3785 "Not enough space for young surv histo.");
3786 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3787 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3788
3789 _overflowed_refs = new OverflowQueue(10);
3790
3791 _start = os::elapsedTime();
3792 }
3793
3794 ~G1ParScanThreadState() {
3795 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
3796 }
3797
3798 RefToScanQueue* refs() { return _refs; }
3799 OverflowQueue* overflowed_refs() { return _overflowed_refs; }
3800 ageTable* age_table() { return &_age_table; }
3801
3802 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
3803 return &_alloc_buffers[purpose];
3804 }
3805
3806 size_t alloc_buffer_waste() { return _alloc_buffer_waste; }
3807 size_t undo_waste() { return _undo_waste; }
3808
3809 void push_on_queue(oop* ref) {
3810 assert(ref != NULL, "invariant");
3811 assert(has_partial_array_mask(ref) || _g1h->obj_in_cs(*ref), "invariant");
3812
3813 if (!refs()->push(ref)) {
3814 overflowed_refs()->push(ref);
3815 IF_G1_DETAILED_STATS(note_overflow_push());
3816 } else {
3817 IF_G1_DETAILED_STATS(note_push());
3818 }
3819 }
3820
3821 void pop_from_queue(oop*& ref) {
3822 if (!refs()->pop_local(ref)) {
3823 ref = NULL;
3824 } else {
3825 assert(ref != NULL, "invariant");
3826 assert(has_partial_array_mask(ref) || _g1h->obj_in_cs(*ref),
3827 "invariant");
3828
3829 IF_G1_DETAILED_STATS(note_pop());
3830 }
3831 }
3832
3833 void pop_from_overflow_queue(oop*& ref) {
3834 ref = overflowed_refs()->pop();
3835 }
3836
3837 int refs_to_scan() { return refs()->size(); }
3838 int overflowed_refs_to_scan() { return overflowed_refs()->length(); }
3839
3840 void update_rs(HeapRegion* from, oop* p, int tid) {
3841 if (G1DeferredRSUpdate) {
3842 deferred_rs_update(from, p, tid);
3843 } else {
3844 immediate_rs_update(from, p, tid);
3845 }
3846 }
3847
3848 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
3849
3850 HeapWord* obj = NULL;
3851 if (word_sz * 100 <
3852 (size_t)(ParallelGCG1AllocBufferSize / HeapWordSize) *
3853 ParallelGCBufferWastePct) {
3854 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
3855 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
3856 alloc_buf->retire(false, false);
3857
3858 HeapWord* buf =
3859 _g1h->par_allocate_during_gc(purpose, ParallelGCG1AllocBufferSize / HeapWordSize);
3860 if (buf == NULL) return NULL; // Let caller handle allocation failure.
3861 // Otherwise.
3862 alloc_buf->set_buf(buf);
3863
3864 obj = alloc_buf->allocate(word_sz);
3865 assert(obj != NULL, "buffer was definitely big enough...");
3866 } else {
3867 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
3868 }
3869 return obj;
3870 }
3871
3872 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
3873 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
3874 if (obj != NULL) return obj;
3875 return allocate_slow(purpose, word_sz);
3876 }
3877
3878 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
3879 if (alloc_buffer(purpose)->contains(obj)) {
3880 guarantee(alloc_buffer(purpose)->contains(obj + word_sz - 1),
3881 "should contain whole object");
3882 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
3883 } else {
3884 CollectedHeap::fill_with_object(obj, word_sz);
3885 add_to_undo_waste(word_sz);
3886 }
3887 }
3888
3889 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
3890 _evac_failure_cl = evac_failure_cl;
3891 }
3892 OopsInHeapRegionClosure* evac_failure_closure() {
3893 return _evac_failure_cl;
3894 }
3895
3896 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
3897 _evac_cl = evac_cl;
3898 }
3899
3900 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
3901 _partial_scan_cl = partial_scan_cl;
3902 }
3903
3904 int* hash_seed() { return &_hash_seed; }
3905 int queue_num() { return _queue_num; }
3906
3907 int term_attempts() { return _term_attempts; }
3908 void note_term_attempt() { _term_attempts++; }
3909
3910 #if G1_DETAILED_STATS
3911 int pushes() { return _pushes; }
3912 int pops() { return _pops; }
3913 int steals() { return _steals; }
3914 int steal_attempts() { return _steal_attempts; }
3915 int overflow_pushes() { return _overflow_pushes; }
3916
3917 void note_push() { _pushes++; }
3918 void note_pop() { _pops++; }
3919 void note_steal() { _steals++; }
3920 void note_steal_attempt() { _steal_attempts++; }
3921 void note_overflow_push() { _overflow_pushes++; }
3922 #endif
3923
3924 void start_strong_roots() {
3925 _start_strong_roots = os::elapsedTime();
3926 }
3927 void end_strong_roots() {
3928 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
3929 }
3930 double strong_roots_time() { return _strong_roots_time; }
3931
3932 void start_term_time() {
3933 note_term_attempt();
3934 _start_term = os::elapsedTime();
3935 }
3936 void end_term_time() {
3937 _term_time += (os::elapsedTime() - _start_term);
3938 }
3939 double term_time() { return _term_time; }
3940
3941 double elapsed() {
3942 return os::elapsedTime() - _start;
3943 }
3944
3945 size_t* surviving_young_words() {
3946 // We add on to hide entry 0 which accumulates surviving words for
3947 // age -1 regions (i.e. non-young ones)
3948 return _surviving_young_words;
3949 }
3950
3951 void retire_alloc_buffers() {
3952 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3953 size_t waste = _alloc_buffers[ap].words_remaining();
3954 add_to_alloc_buffer_waste(waste);
3955 _alloc_buffers[ap].retire(true, false);
3956 }
3957 }
3958
3959 private:
3960 void deal_with_reference(oop* ref_to_scan) {
3961 if (has_partial_array_mask(ref_to_scan)) {
3962 _partial_scan_cl->do_oop_nv(ref_to_scan);
3963 } else {
3964 // Note: we can use "raw" versions of "region_containing" because
3965 // "obj_to_scan" is definitely in the heap, and is not in a
3966 // humongous region.
3967 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
3968 _evac_cl->set_region(r);
3969 _evac_cl->do_oop_nv(ref_to_scan);
3970 }
3971 }
3972
3973 public:
3974 void trim_queue() {
3975 // I've replicated the loop twice, first to drain the overflow
3976 // queue, second to drain the task queue. This is better than
3977 // having a single loop, which checks both conditions and, inside
3978 // it, either pops the overflow queue or the task queue, as each
3979 // loop is tighter. Also, the decision to drain the overflow queue
3980 // first is not arbitrary, as the overflow queue is not visible
3981 // to the other workers, whereas the task queue is. So, we want to
3982 // drain the "invisible" entries first, while allowing the other
3983 // workers to potentially steal the "visible" entries.
3984
3985 while (refs_to_scan() > 0 || overflowed_refs_to_scan() > 0) {
3986 while (overflowed_refs_to_scan() > 0) {
3987 oop *ref_to_scan = NULL;
3988 pop_from_overflow_queue(ref_to_scan);
3989 assert(ref_to_scan != NULL, "invariant");
3990 // We shouldn't have pushed it on the queue if it was not
3991 // pointing into the CSet.
3992 assert(ref_to_scan != NULL, "sanity");
3993 assert(has_partial_array_mask(ref_to_scan) ||
3994 _g1h->obj_in_cs(*ref_to_scan), "sanity");
3995
3996 deal_with_reference(ref_to_scan);
3997 }
3998
3999 while (refs_to_scan() > 0) {
4000 oop *ref_to_scan = NULL;
4001 pop_from_queue(ref_to_scan);
4002
4003 if (ref_to_scan != NULL) {
4004 // We shouldn't have pushed it on the queue if it was not
4005 // pointing into the CSet.
4006 assert(has_partial_array_mask(ref_to_scan) ||
4007 _g1h->obj_in_cs(*ref_to_scan), "sanity");
4008
4009 deal_with_reference(ref_to_scan);
4010 }
4011 }
4012 }
4013 }
4014 };
4015
4016 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4017 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4018 _par_scan_state(par_scan_state) { }
4019
4020 // This closure is applied to the fields of the objects that have just been copied.
4021 // Should probably be made inline and moved in g1OopClosures.inline.hpp.
4022 void G1ParScanClosure::do_oop_nv(oop* p) {
4023 oop obj = *p;
4024
4025 if (obj != NULL) {
4026 if (_g1->in_cset_fast_test(obj)) {
4027 // We're not going to even bother checking whether the object is
4028 // already forwarded or not, as this usually causes an immediate
4029 // stall. We'll try to prefetch the object (for write, given that
4030 // we might need to install the forwarding reference) and we'll
4031 // get back to it when pop it from the queue
4032 Prefetch::write(obj->mark_addr(), 0);
4033 Prefetch::read(obj->mark_addr(), (HeapWordSize*2));
4034
4035 // slightly paranoid test; I'm trying to catch potential
4036 // problems before we go into push_on_queue to know where the
4037 // problem is coming from
4038 assert(obj == *p, "the value of *p should not have changed");
4039 _par_scan_state->push_on_queue(p);
4040 } else {
4041 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4042 }
4043 }
4044 }
4045
4046 void G1ParCopyHelper::mark_forwardee(oop* p) {
4047 // This is called _after_ do_oop_work has been called, hence after
4048 // the object has been relocated to its new location and *p points
4049 // to its new location.
4050
4051 oop thisOop = *p;
4052 if (thisOop != NULL) {
4053 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(thisOop)),
4054 "shouldn't still be in the CSet if evacuation didn't fail.");
4055 HeapWord* addr = (HeapWord*)thisOop;
4056 if (_g1->is_in_g1_reserved(addr))
4057 _cm->grayRoot(oop(addr));
4058 }
4059 }
4060
4061 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
4062 size_t word_sz = old->size();
4063 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4064 // +1 to make the -1 indexes valid...
4065 int young_index = from_region->young_index_in_cset()+1;
4066 assert( (from_region->is_young() && young_index > 0) ||
4067 (!from_region->is_young() && young_index == 0), "invariant" );
4068 G1CollectorPolicy* g1p = _g1->g1_policy();
4069 markOop m = old->mark();
4070 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4071 : m->age();
4072 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4073 word_sz);
4074 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4075 oop obj = oop(obj_ptr);
4076
4077 if (obj_ptr == NULL) {
4078 // This will either forward-to-self, or detect that someone else has
4079 // installed a forwarding pointer.
4080 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4081 return _g1->handle_evacuation_failure_par(cl, old);
4082 }
4083
4084 // We're going to allocate linearly, so might as well prefetch ahead.
4085 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4086
4087 oop forward_ptr = old->forward_to_atomic(obj);
4088 if (forward_ptr == NULL) {
4089 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4090 if (g1p->track_object_age(alloc_purpose)) {
4091 // We could simply do obj->incr_age(). However, this causes a
4092 // performance issue. obj->incr_age() will first check whether
4093 // the object has a displaced mark by checking its mark word;
4094 // getting the mark word from the new location of the object
4095 // stalls. So, given that we already have the mark word and we
4096 // are about to install it anyway, it's better to increase the
4097 // age on the mark word, when the object does not have a
4098 // displaced mark word. We're not expecting many objects to have
4099 // a displaced marked word, so that case is not optimized
4100 // further (it could be...) and we simply call obj->incr_age().
4101
4102 if (m->has_displaced_mark_helper()) {
4103 // in this case, we have to install the mark word first,
4104 // otherwise obj looks to be forwarded (the old mark word,
4105 // which contains the forward pointer, was copied)
4106 obj->set_mark(m);
4107 obj->incr_age();
4108 } else {
4109 m = m->incr_age();
4110 obj->set_mark(m);
4111 }
4112 _par_scan_state->age_table()->add(obj, word_sz);
4113 } else {
4114 obj->set_mark(m);
4115 }
4116
4117 // preserve "next" mark bit
4118 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
4119 if (!use_local_bitmaps ||
4120 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4121 // if we couldn't mark it on the local bitmap (this happens when
4122 // the object was not allocated in the GCLab), we have to bite
4123 // the bullet and do the standard parallel mark
4124 _cm->markAndGrayObjectIfNecessary(obj);
4125 }
4126 #if 1
4127 if (_g1->isMarkedNext(old)) {
4128 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4129 }
4130 #endif
4131 }
4132
4133 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4134 surv_young_words[young_index] += word_sz;
4135
4136 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4137 arrayOop(old)->set_length(0);
4138 _par_scan_state->push_on_queue(set_partial_array_mask(old));
4139 } else {
4140 // No point in using the slower heap_region_containing() method,
4141 // given that we know obj is in the heap.
4142 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4143 obj->oop_iterate_backwards(_scanner);
4144 }
4145 } else {
4146 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4147 obj = forward_ptr;
4148 }
4149 return obj;
4150 }
4151
4152 template<bool do_gen_barrier, G1Barrier barrier,
4153 bool do_mark_forwardee, bool skip_cset_test>
4154 void G1ParCopyClosure<do_gen_barrier, barrier,
4155 do_mark_forwardee, skip_cset_test>::do_oop_work(oop* p) {
4156 oop obj = *p;
4157 assert(barrier != G1BarrierRS || obj != NULL,
4158 "Precondition: G1BarrierRS implies obj is nonNull");
4159
4160 // The only time we skip the cset test is when we're scanning
4161 // references popped from the queue. And we only push on the queue
4162 // references that we know point into the cset, so no point in
4163 // checking again. But we'll leave an assert here for peace of mind.
4164 assert(!skip_cset_test || _g1->obj_in_cs(obj), "invariant");
4165
4166 // here the null check is implicit in the cset_fast_test() test
4167 if (skip_cset_test || _g1->in_cset_fast_test(obj)) {
4168 #if G1_REM_SET_LOGGING
4169 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
4170 "into CS.", p, (void*) obj);
4171 #endif
4172 if (obj->is_forwarded()) {
4173 *p = obj->forwardee();
4174 } else {
4175 *p = copy_to_survivor_space(obj);
4176 }
4177 // When scanning the RS, we only care about objs in CS.
4178 if (barrier == G1BarrierRS) {
4179 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4180 }
4181 }
4182
4183 // When scanning moved objs, must look at all oops.
4184 if (barrier == G1BarrierEvac && obj != NULL) {
4185 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4186 }
4187
4188 if (do_gen_barrier && obj != NULL) {
4189 par_do_barrier(p);
4190 }
4191 }
4192
4193 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(oop* p);
4194
4195 template<class T> void G1ParScanPartialArrayClosure::process_array_chunk(
4196 oop obj, int start, int end) {
4197 // process our set of indices (include header in first chunk)
4198 assert(start < end, "invariant");
4199 T* const base = (T*)objArrayOop(obj)->base();
4200 T* const start_addr = (start == 0) ? (T*) obj : base + start;
4201 T* const end_addr = base + end;
4202 MemRegion mr((HeapWord*)start_addr, (HeapWord*)end_addr);
4203 _scanner.set_region(_g1->heap_region_containing(obj));
4204 obj->oop_iterate(&_scanner, mr);
4205 }
4206
4207 void G1ParScanPartialArrayClosure::do_oop_nv(oop* p) {
4208 assert(!UseCompressedOops, "Needs to be fixed to work with compressed oops");
4209 assert(has_partial_array_mask(p), "invariant");
4210 oop old = clear_partial_array_mask(p);
4211 assert(old->is_objArray(), "must be obj array");
4212 assert(old->is_forwarded(), "must be forwarded");
4213 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4214
4215 objArrayOop obj = objArrayOop(old->forwardee());
4216 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4217 // Process ParGCArrayScanChunk elements now
4218 // and push the remainder back onto queue
4219 int start = arrayOop(old)->length();
4220 int end = obj->length();
4221 int remainder = end - start;
4222 assert(start <= end, "just checking");
4223 if (remainder > 2 * ParGCArrayScanChunk) {
4224 // Test above combines last partial chunk with a full chunk
4225 end = start + ParGCArrayScanChunk;
4226 arrayOop(old)->set_length(end);
4227 // Push remainder.
4228 _par_scan_state->push_on_queue(set_partial_array_mask(old));
4229 } else {
4230 // Restore length so that the heap remains parsable in
4231 // case of evacuation failure.
4232 arrayOop(old)->set_length(end);
4233 }
4234
4235 // process our set of indices (include header in first chunk)
4236 process_array_chunk<oop>(obj, start, end);
4237 }
4238
4239 int G1ScanAndBalanceClosure::_nq = 0;
4240
4241 class G1ParEvacuateFollowersClosure : public VoidClosure {
4242 protected:
4243 G1CollectedHeap* _g1h;
4244 G1ParScanThreadState* _par_scan_state;
4245 RefToScanQueueSet* _queues;
4246 ParallelTaskTerminator* _terminator;
4247
4248 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4249 RefToScanQueueSet* queues() { return _queues; }
4250 ParallelTaskTerminator* terminator() { return _terminator; }
4251
4252 public:
4253 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4254 G1ParScanThreadState* par_scan_state,
4255 RefToScanQueueSet* queues,
4256 ParallelTaskTerminator* terminator)
4257 : _g1h(g1h), _par_scan_state(par_scan_state),
4258 _queues(queues), _terminator(terminator) {}
4259
4260 void do_void() {
4261 G1ParScanThreadState* pss = par_scan_state();
4262 while (true) {
4263 oop* ref_to_scan;
4264 pss->trim_queue();
4265 IF_G1_DETAILED_STATS(pss->note_steal_attempt());
4266 if (queues()->steal(pss->queue_num(),
4267 pss->hash_seed(),
4268 ref_to_scan)) {
4269 IF_G1_DETAILED_STATS(pss->note_steal());
4270
4271 // slightly paranoid tests; I'm trying to catch potential
4272 // problems before we go into push_on_queue to know where the
4273 // problem is coming from
4274 assert(ref_to_scan != NULL, "invariant");
4275 assert(has_partial_array_mask(ref_to_scan) ||
4276 _g1h->obj_in_cs(*ref_to_scan), "invariant");
4277 pss->push_on_queue(ref_to_scan);
4278 continue;
4279 }
4280 pss->start_term_time();
4281 if (terminator()->offer_termination()) break;
4282 pss->end_term_time();
4283 }
4284 pss->end_term_time();
4285 pss->retire_alloc_buffers();
4286 }
4287 };
4288
4289 class G1ParTask : public AbstractGangTask {
4290 protected:
4291 G1CollectedHeap* _g1h;
4292 RefToScanQueueSet *_queues;
4293 ParallelTaskTerminator _terminator;
4294
4295 Mutex _stats_lock;
4296 Mutex* stats_lock() { return &_stats_lock; }
4297
4298 size_t getNCards() {
4299 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4300 / G1BlockOffsetSharedArray::N_bytes;
4301 }
4302
4303 public:
4304 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4305 : AbstractGangTask("G1 collection"),
4306 _g1h(g1h),
4307 _queues(task_queues),
4308 _terminator(workers, _queues),
4309 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4310 {}
4311
4312 RefToScanQueueSet* queues() { return _queues; }
4313
4314 RefToScanQueue *work_queue(int i) {
4315 return queues()->queue(i);
4316 }
4317
4318 void work(int i) {
4319 ResourceMark rm;
4320 HandleMark hm;
4321
4322 G1ParScanThreadState pss(_g1h, i);
4323 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4324 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4325 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4326
4327 pss.set_evac_closure(&scan_evac_cl);
4328 pss.set_evac_failure_closure(&evac_failure_cl);
4329 pss.set_partial_scan_closure(&partial_scan_cl);
4330
4331 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4332 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4333 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4334
4335 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4336 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4337 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4338
4339 OopsInHeapRegionClosure *scan_root_cl;
4340 OopsInHeapRegionClosure *scan_perm_cl;
4341 OopsInHeapRegionClosure *scan_so_cl;
4342
4343 if (_g1h->g1_policy()->should_initiate_conc_mark()) {
4344 scan_root_cl = &scan_mark_root_cl;
4345 scan_perm_cl = &scan_mark_perm_cl;
4346 scan_so_cl = &scan_mark_heap_rs_cl;
4347 } else {
4348 scan_root_cl = &only_scan_root_cl;
4349 scan_perm_cl = &only_scan_perm_cl;
4350 scan_so_cl = &only_scan_heap_rs_cl;
4351 }
4352
4353 pss.start_strong_roots();
4354 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4355 SharedHeap::SO_AllClasses,
4356 scan_root_cl,
4357 &only_scan_heap_rs_cl,
4358 scan_so_cl,
4359 scan_perm_cl,
4360 i);
4361 pss.end_strong_roots();
4362 {
4363 double start = os::elapsedTime();
4364 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4365 evac.do_void();
4366 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4367 double term_ms = pss.term_time()*1000.0;
4368 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4369 _g1h->g1_policy()->record_termination_time(i, term_ms);
4370 }
4371 if (G1UseSurvivorSpace) {
4372 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4373 }
4374 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4375
4376 // Clean up any par-expanded rem sets.
4377 HeapRegionRemSet::par_cleanup();
4378
4379 MutexLocker x(stats_lock());
4380 if (ParallelGCVerbose) {
4381 gclog_or_tty->print("Thread %d complete:\n", i);
4382 #if G1_DETAILED_STATS
4383 gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n",
4384 pss.pushes(),
4385 pss.pops(),
4386 pss.overflow_pushes(),
4387 pss.steals(),
4388 pss.steal_attempts());
4389 #endif
4390 double elapsed = pss.elapsed();
4391 double strong_roots = pss.strong_roots_time();
4392 double term = pss.term_time();
4393 gclog_or_tty->print(" Elapsed: %7.2f ms.\n"
4394 " Strong roots: %7.2f ms (%6.2f%%)\n"
4395 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n",
4396 elapsed * 1000.0,
4397 strong_roots * 1000.0, (strong_roots*100.0/elapsed),
4398 term * 1000.0, (term*100.0/elapsed),
4399 pss.term_attempts());
4400 size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste();
4401 gclog_or_tty->print(" Waste: %8dK\n"
4402 " Alloc Buffer: %8dK\n"
4403 " Undo: %8dK\n",
4404 (total_waste * HeapWordSize) / K,
4405 (pss.alloc_buffer_waste() * HeapWordSize) / K,
4406 (pss.undo_waste() * HeapWordSize) / K);
4407 }
4408
4409 assert(pss.refs_to_scan() == 0, "Task queue should be empty");
4410 assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
4411 }
4412 };
4413
4414 // *** Common G1 Evacuation Stuff
4415
4416 class G1CountClosure: public OopsInHeapRegionClosure {
4417 public:
4418 int n;
4419 G1CountClosure() : n(0) {}
4420 void do_oop(narrowOop* p) {
4421 guarantee(false, "NYI");
4422 }
4423 void do_oop(oop* p) {
4424 oop obj = *p;
4425 assert(obj != NULL && G1CollectedHeap::heap()->obj_in_cs(obj),
4426 "Rem set closure called on non-rem-set pointer.");
4427 n++;
4428 }
4429 };
4430
4431 static G1CountClosure count_closure;
4432
4433 void
4434 G1CollectedHeap::
4435 g1_process_strong_roots(bool collecting_perm_gen,
4436 SharedHeap::ScanningOption so,
4437 OopClosure* scan_non_heap_roots,
4438 OopsInHeapRegionClosure* scan_rs,
4439 OopsInHeapRegionClosure* scan_so,
4440 OopsInGenClosure* scan_perm,
4441 int worker_i) {
4442 // First scan the strong roots, including the perm gen.
4443 double ext_roots_start = os::elapsedTime();
4444 double closure_app_time_sec = 0.0;
4445
4446 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4447 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4448 buf_scan_perm.set_generation(perm_gen());
4449
4450 process_strong_roots(collecting_perm_gen, so,
4451 &buf_scan_non_heap_roots,
4452 &buf_scan_perm);
4453 // Finish up any enqueued closure apps.
4454 buf_scan_non_heap_roots.done();
4455 buf_scan_perm.done();
4456 double ext_roots_end = os::elapsedTime();
4457 g1_policy()->reset_obj_copy_time(worker_i);
4458 double obj_copy_time_sec =
4459 buf_scan_non_heap_roots.closure_app_seconds() +
4460 buf_scan_perm.closure_app_seconds();
4461 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4462 double ext_root_time_ms =
4463 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4464 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4465
4466 // Scan strong roots in mark stack.
4467 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4468 concurrent_mark()->oops_do(scan_non_heap_roots);
4469 }
4470 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4471 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4472
4473 // XXX What should this be doing in the parallel case?
4474 g1_policy()->record_collection_pause_end_CH_strong_roots();
4475 if (G1VerifyRemSet) {
4476 // :::: FIXME ::::
4477 // The stupid remembered set doesn't know how to filter out dead
4478 // objects, which the smart one does, and so when it is created
4479 // and then compared the number of entries in each differs and
4480 // the verification code fails.
4481 guarantee(false, "verification code is broken, see note");
4482
4483 // Let's make sure that the current rem set agrees with the stupidest
4484 // one possible!
4485 bool refs_enabled = ref_processor()->discovery_enabled();
4486 if (refs_enabled) ref_processor()->disable_discovery();
4487 StupidG1RemSet stupid(this);
4488 count_closure.n = 0;
4489 stupid.oops_into_collection_set_do(&count_closure, worker_i);
4490 int stupid_n = count_closure.n;
4491 count_closure.n = 0;
4492 g1_rem_set()->oops_into_collection_set_do(&count_closure, worker_i);
4493 guarantee(count_closure.n == stupid_n, "Old and new rem sets differ.");
4494 gclog_or_tty->print_cr("\nFound %d pointers in heap RS.", count_closure.n);
4495 if (refs_enabled) ref_processor()->enable_discovery();
4496 }
4497 if (scan_so != NULL) {
4498 scan_scan_only_set(scan_so, worker_i);
4499 }
4500 // Now scan the complement of the collection set.
4501 if (scan_rs != NULL) {
4502 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4503 }
4504 // Finish with the ref_processor roots.
4505 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4506 ref_processor()->oops_do(scan_non_heap_roots);
4507 }
4508 g1_policy()->record_collection_pause_end_G1_strong_roots();
4509 _process_strong_tasks->all_tasks_completed();
4510 }
4511
4512 void
4513 G1CollectedHeap::scan_scan_only_region(HeapRegion* r,
4514 OopsInHeapRegionClosure* oc,
4515 int worker_i) {
4516 HeapWord* startAddr = r->bottom();
4517 HeapWord* endAddr = r->used_region().end();
4518
4519 oc->set_region(r);
4520
4521 HeapWord* p = r->bottom();
4522 HeapWord* t = r->top();
4523 guarantee( p == r->next_top_at_mark_start(), "invariant" );
4524 while (p < t) {
4525 oop obj = oop(p);
4526 p += obj->oop_iterate(oc);
4527 }
4528 }
4529
4530 void
4531 G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc,
4532 int worker_i) {
4533 double start = os::elapsedTime();
4534
4535 BufferingOopsInHeapRegionClosure boc(oc);
4536
4537 FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc);
4538 FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark());
4539
4540 OopsInHeapRegionClosure *foc;
4541 if (g1_policy()->should_initiate_conc_mark())
4542 foc = &scan_and_mark;
4543 else
4544 foc = &scan_only;
4545
4546 HeapRegion* hr;
4547 int n = 0;
4548 while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) {
4549 scan_scan_only_region(hr, foc, worker_i);
4550 ++n;
4551 }
4552 boc.done();
4553
4554 double closure_app_s = boc.closure_app_seconds();
4555 g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0);
4556 double ms = (os::elapsedTime() - start - closure_app_s)*1000.0;
4557 g1_policy()->record_scan_only_time(worker_i, ms, n);
4558 }
4559
4560 void
4561 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4562 OopClosure* non_root_closure) {
4563 SharedHeap::process_weak_roots(root_closure, non_root_closure);
4564 }
4565
4566
4567 class SaveMarksClosure: public HeapRegionClosure {
4568 public:
4569 bool doHeapRegion(HeapRegion* r) {
4570 r->save_marks();
4571 return false;
4572 }
4573 };
4574
4575 void G1CollectedHeap::save_marks() {
4576 if (ParallelGCThreads == 0) {
4577 SaveMarksClosure sm;
4578 heap_region_iterate(&sm);
4579 }
4580 // We do this even in the parallel case
4581 perm_gen()->save_marks();
4582 }
4583
4584 void G1CollectedHeap::evacuate_collection_set() {
4585 set_evacuation_failed(false);
4586
4587 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4588 concurrent_g1_refine()->set_use_cache(false);
4589 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4590 set_par_threads(n_workers);
4591 G1ParTask g1_par_task(this, n_workers, _task_queues);
4592
4593 init_for_evac_failure(NULL);
4594
4595 change_strong_roots_parity(); // In preparation for parallel strong roots.
4596 rem_set()->prepare_for_younger_refs_iterate(true);
4597
4598 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4599 double start_par = os::elapsedTime();
4600 if (ParallelGCThreads > 0) {
4601 // The individual threads will set their evac-failure closures.
4602 workers()->run_task(&g1_par_task);
4603 } else {
4604 g1_par_task.work(0);
4605 }
4606
4607 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4608 g1_policy()->record_par_time(par_time);
4609 set_par_threads(0);
4610 // Is this the right thing to do here? We don't save marks
4611 // on individual heap regions when we allocate from
4612 // them in parallel, so this seems like the correct place for this.
4613 retire_all_alloc_regions();
4614 {
4615 G1IsAliveClosure is_alive(this);
4616 G1KeepAliveClosure keep_alive(this);
4617 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4618 }
4619 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4620
4621 concurrent_g1_refine()->set_use_cache(true);
4622
4623 finalize_for_evac_failure();
4624
4625 // Must do this before removing self-forwarding pointers, which clears
4626 // the per-region evac-failure flags.
4627 concurrent_mark()->complete_marking_in_collection_set();
4628
4629 if (evacuation_failed()) {
4630 remove_self_forwarding_pointers();
4631 if (PrintGCDetails) {
4632 gclog_or_tty->print(" (evacuation failed)");
4633 } else if (PrintGC) {
4634 gclog_or_tty->print("--");
4635 }
4636 }
4637
4638 if (G1DeferredRSUpdate) {
4639 RedirtyLoggedCardTableEntryFastClosure redirty;
4640 dirty_card_queue_set().set_closure(&redirty);
4641 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4642 JavaThread::dirty_card_queue_set().merge_bufferlists(&dirty_card_queue_set());
4643 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4644 }
4645
4646 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4647 }
4648
4649 void G1CollectedHeap::free_region(HeapRegion* hr) {
4650 size_t pre_used = 0;
4651 size_t cleared_h_regions = 0;
4652 size_t freed_regions = 0;
4653 UncleanRegionList local_list;
4654
4655 HeapWord* start = hr->bottom();
4656 HeapWord* end = hr->prev_top_at_mark_start();
4657 size_t used_bytes = hr->used();
4658 size_t live_bytes = hr->max_live_bytes();
4659 if (used_bytes > 0) {
4660 guarantee( live_bytes <= used_bytes, "invariant" );
4661 } else {
4662 guarantee( live_bytes == 0, "invariant" );
4663 }
4664
4665 size_t garbage_bytes = used_bytes - live_bytes;
4666 if (garbage_bytes > 0)
4667 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4668
4669 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4670 &local_list);
4671 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4672 &local_list);
4673 }
4674
4675 void
4676 G1CollectedHeap::free_region_work(HeapRegion* hr,
4677 size_t& pre_used,
4678 size_t& cleared_h_regions,
4679 size_t& freed_regions,
4680 UncleanRegionList* list,
4681 bool par) {
4682 assert(!hr->popular(), "should not free popular regions");
4683 pre_used += hr->used();
4684 if (hr->isHumongous()) {
4685 assert(hr->startsHumongous(),
4686 "Only the start of a humongous region should be freed.");
4687 int ind = _hrs->find(hr);
4688 assert(ind != -1, "Should have an index.");
4689 // Clear the start region.
4690 hr->hr_clear(par, true /*clear_space*/);
4691 list->insert_before_head(hr);
4692 cleared_h_regions++;
4693 freed_regions++;
4694 // Clear any continued regions.
4695 ind++;
4696 while ((size_t)ind < n_regions()) {
4697 HeapRegion* hrc = _hrs->at(ind);
4698 if (!hrc->continuesHumongous()) break;
4699 // Otherwise, does continue the H region.
4700 assert(hrc->humongous_start_region() == hr, "Huh?");
4701 hrc->hr_clear(par, true /*clear_space*/);
4702 cleared_h_regions++;
4703 freed_regions++;
4704 list->insert_before_head(hrc);
4705 ind++;
4706 }
4707 } else {
4708 hr->hr_clear(par, true /*clear_space*/);
4709 list->insert_before_head(hr);
4710 freed_regions++;
4711 // If we're using clear2, this should not be enabled.
4712 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4713 }
4714 }
4715
4716 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4717 size_t cleared_h_regions,
4718 size_t freed_regions,
4719 UncleanRegionList* list) {
4720 if (list != NULL && list->sz() > 0) {
4721 prepend_region_list_on_unclean_list(list);
4722 }
4723 // Acquire a lock, if we're parallel, to update possibly-shared
4724 // variables.
4725 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4726 {
4727 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4728 _summary_bytes_used -= pre_used;
4729 _num_humongous_regions -= (int) cleared_h_regions;
4730 _free_regions += freed_regions;
4731 }
4732 }
4733
4734
4735 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4736 while (list != NULL) {
4737 guarantee( list->is_young(), "invariant" );
4738
4739 HeapWord* bottom = list->bottom();
4740 HeapWord* end = list->end();
4741 MemRegion mr(bottom, end);
4742 ct_bs->dirty(mr);
4743
4744 list = list->get_next_young_region();
4745 }
4746 }
4747
4748 void G1CollectedHeap::cleanUpCardTable() {
4749 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4750 double start = os::elapsedTime();
4751
4752 ct_bs->clear(_g1_committed);
4753
4754 // now, redirty the cards of the scan-only and survivor regions
4755 // (it seemed faster to do it this way, instead of iterating over
4756 // all regions and then clearing / dirtying as approprite)
4757 dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region());
4758 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4759
4760 double elapsed = os::elapsedTime() - start;
4761 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4762 }
4763
4764
4765 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4766 // First do any popular regions.
4767 HeapRegion* hr;
4768 while ((hr = popular_region_to_evac()) != NULL) {
4769 evac_popular_region(hr);
4770 }
4771 // Now do heuristic pauses.
4772 if (g1_policy()->should_do_collection_pause(word_size)) {
4773 do_collection_pause();
4774 }
4775 }
4776
4777 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4778 double young_time_ms = 0.0;
4779 double non_young_time_ms = 0.0;
4780
4781 G1CollectorPolicy* policy = g1_policy();
4782
4783 double start_sec = os::elapsedTime();
4784 bool non_young = true;
4785
4786 HeapRegion* cur = cs_head;
4787 int age_bound = -1;
4788 size_t rs_lengths = 0;
4789
4790 while (cur != NULL) {
4791 if (non_young) {
4792 if (cur->is_young()) {
4793 double end_sec = os::elapsedTime();
4794 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4795 non_young_time_ms += elapsed_ms;
4796
4797 start_sec = os::elapsedTime();
4798 non_young = false;
4799 }
4800 } else {
4801 if (!cur->is_on_free_list()) {
4802 double end_sec = os::elapsedTime();
4803 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4804 young_time_ms += elapsed_ms;
4805
4806 start_sec = os::elapsedTime();
4807 non_young = true;
4808 }
4809 }
4810
4811 rs_lengths += cur->rem_set()->occupied();
4812
4813 HeapRegion* next = cur->next_in_collection_set();
4814 assert(cur->in_collection_set(), "bad CS");
4815 cur->set_next_in_collection_set(NULL);
4816 cur->set_in_collection_set(false);
4817
4818 if (cur->is_young()) {
4819 int index = cur->young_index_in_cset();
4820 guarantee( index != -1, "invariant" );
4821 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4822 size_t words_survived = _surviving_young_words[index];
4823 cur->record_surv_words_in_group(words_survived);
4824 } else {
4825 int index = cur->young_index_in_cset();
4826 guarantee( index == -1, "invariant" );
4827 }
4828
4829 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4830 (!cur->is_young() && cur->young_index_in_cset() == -1),
4831 "invariant" );
4832
4833 if (!cur->evacuation_failed()) {
4834 // And the region is empty.
4835 assert(!cur->is_empty(),
4836 "Should not have empty regions in a CS.");
4837 free_region(cur);
4838 } else {
4839 guarantee( !cur->is_scan_only(), "should not be scan only" );
4840 cur->uninstall_surv_rate_group();
4841 if (cur->is_young())
4842 cur->set_young_index_in_cset(-1);
4843 cur->set_not_young();
4844 cur->set_evacuation_failed(false);
4845 }
4846 cur = next;
4847 }
4848
4849 policy->record_max_rs_lengths(rs_lengths);
4850 policy->cset_regions_freed();
4851
4852 double end_sec = os::elapsedTime();
4853 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4854 if (non_young)
4855 non_young_time_ms += elapsed_ms;
4856 else
4857 young_time_ms += elapsed_ms;
4858
4859 policy->record_young_free_cset_time_ms(young_time_ms);
4860 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4861 }
4862
4863 HeapRegion*
4864 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4865 assert(ZF_mon->owned_by_self(), "Precondition");
4866 HeapRegion* res = pop_unclean_region_list_locked();
4867 if (res != NULL) {
4868 assert(!res->continuesHumongous() &&
4869 res->zero_fill_state() != HeapRegion::Allocated,
4870 "Only free regions on unclean list.");
4871 if (zero_filled) {
4872 res->ensure_zero_filled_locked();
4873 res->set_zero_fill_allocated();
4874 }
4875 }
4876 return res;
4877 }
4878
4879 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4880 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4881 return alloc_region_from_unclean_list_locked(zero_filled);
4882 }
4883
4884 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4885 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4886 put_region_on_unclean_list_locked(r);
4887 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4888 }
4889
4890 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4891 MutexLockerEx x(Cleanup_mon);
4892 set_unclean_regions_coming_locked(b);
4893 }
4894
4895 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4896 assert(Cleanup_mon->owned_by_self(), "Precondition");
4897 _unclean_regions_coming = b;
4898 // Wake up mutator threads that might be waiting for completeCleanup to
4899 // finish.
4900 if (!b) Cleanup_mon->notify_all();
4901 }
4902
4903 void G1CollectedHeap::wait_for_cleanup_complete() {
4904 MutexLockerEx x(Cleanup_mon);
4905 wait_for_cleanup_complete_locked();
4906 }
4907
4908 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4909 assert(Cleanup_mon->owned_by_self(), "precondition");
4910 while (_unclean_regions_coming) {
4911 Cleanup_mon->wait();
4912 }
4913 }
4914
4915 void
4916 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4917 assert(ZF_mon->owned_by_self(), "precondition.");
4918 _unclean_region_list.insert_before_head(r);
4919 }
4920
4921 void
4922 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4923 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4924 prepend_region_list_on_unclean_list_locked(list);
4925 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4926 }
4927
4928 void
4929 G1CollectedHeap::
4930 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4931 assert(ZF_mon->owned_by_self(), "precondition.");
4932 _unclean_region_list.prepend_list(list);
4933 }
4934
4935 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4936 assert(ZF_mon->owned_by_self(), "precondition.");
4937 HeapRegion* res = _unclean_region_list.pop();
4938 if (res != NULL) {
4939 // Inform ZF thread that there's a new unclean head.
4940 if (_unclean_region_list.hd() != NULL && should_zf())
4941 ZF_mon->notify_all();
4942 }
4943 return res;
4944 }
4945
4946 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4947 assert(ZF_mon->owned_by_self(), "precondition.");
4948 return _unclean_region_list.hd();
4949 }
4950
4951
4952 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4953 assert(ZF_mon->owned_by_self(), "Precondition");
4954 HeapRegion* r = peek_unclean_region_list_locked();
4955 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4956 // Result of below must be equal to "r", since we hold the lock.
4957 (void)pop_unclean_region_list_locked();
4958 put_free_region_on_list_locked(r);
4959 return true;
4960 } else {
4961 return false;
4962 }
4963 }
4964
4965 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4966 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4967 return move_cleaned_region_to_free_list_locked();
4968 }
4969
4970
4971 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
4972 assert(ZF_mon->owned_by_self(), "precondition.");
4973 assert(_free_region_list_size == free_region_list_length(), "Inv");
4974 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
4975 "Regions on free list must be zero filled");
4976 assert(!r->isHumongous(), "Must not be humongous.");
4977 assert(r->is_empty(), "Better be empty");
4978 assert(!r->is_on_free_list(),
4979 "Better not already be on free list");
4980 assert(!r->is_on_unclean_list(),
4981 "Better not already be on unclean list");
4982 r->set_on_free_list(true);
4983 r->set_next_on_free_list(_free_region_list);
4984 _free_region_list = r;
4985 _free_region_list_size++;
4986 assert(_free_region_list_size == free_region_list_length(), "Inv");
4987 }
4988
4989 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
4990 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4991 put_free_region_on_list_locked(r);
4992 }
4993
4994 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
4995 assert(ZF_mon->owned_by_self(), "precondition.");
4996 assert(_free_region_list_size == free_region_list_length(), "Inv");
4997 HeapRegion* res = _free_region_list;
4998 if (res != NULL) {
4999 _free_region_list = res->next_from_free_list();
5000 _free_region_list_size--;
5001 res->set_on_free_list(false);
5002 res->set_next_on_free_list(NULL);
5003 assert(_free_region_list_size == free_region_list_length(), "Inv");
5004 }
5005 return res;
5006 }
5007
5008
5009 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
5010 // By self, or on behalf of self.
5011 assert(Heap_lock->is_locked(), "Precondition");
5012 HeapRegion* res = NULL;
5013 bool first = true;
5014 while (res == NULL) {
5015 if (zero_filled || !first) {
5016 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5017 res = pop_free_region_list_locked();
5018 if (res != NULL) {
5019 assert(!res->zero_fill_is_allocated(),
5020 "No allocated regions on free list.");
5021 res->set_zero_fill_allocated();
5022 } else if (!first) {
5023 break; // We tried both, time to return NULL.
5024 }
5025 }
5026
5027 if (res == NULL) {
5028 res = alloc_region_from_unclean_list(zero_filled);
5029 }
5030 assert(res == NULL ||
5031 !zero_filled ||
5032 res->zero_fill_is_allocated(),
5033 "We must have allocated the region we're returning");
5034 first = false;
5035 }
5036 return res;
5037 }
5038
5039 void G1CollectedHeap::remove_allocated_regions_from_lists() {
5040 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5041 {
5042 HeapRegion* prev = NULL;
5043 HeapRegion* cur = _unclean_region_list.hd();
5044 while (cur != NULL) {
5045 HeapRegion* next = cur->next_from_unclean_list();
5046 if (cur->zero_fill_is_allocated()) {
5047 // Remove from the list.
5048 if (prev == NULL) {
5049 (void)_unclean_region_list.pop();
5050 } else {
5051 _unclean_region_list.delete_after(prev);
5052 }
5053 cur->set_on_unclean_list(false);
5054 cur->set_next_on_unclean_list(NULL);
5055 } else {
5056 prev = cur;
5057 }
5058 cur = next;
5059 }
5060 assert(_unclean_region_list.sz() == unclean_region_list_length(),
5061 "Inv");
5062 }
5063
5064 {
5065 HeapRegion* prev = NULL;
5066 HeapRegion* cur = _free_region_list;
5067 while (cur != NULL) {
5068 HeapRegion* next = cur->next_from_free_list();
5069 if (cur->zero_fill_is_allocated()) {
5070 // Remove from the list.
5071 if (prev == NULL) {
5072 _free_region_list = cur->next_from_free_list();
5073 } else {
5074 prev->set_next_on_free_list(cur->next_from_free_list());
5075 }
5076 cur->set_on_free_list(false);
5077 cur->set_next_on_free_list(NULL);
5078 _free_region_list_size--;
5079 } else {
5080 prev = cur;
5081 }
5082 cur = next;
5083 }
5084 assert(_free_region_list_size == free_region_list_length(), "Inv");
5085 }
5086 }
5087
5088 bool G1CollectedHeap::verify_region_lists() {
5089 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5090 return verify_region_lists_locked();
5091 }
5092
5093 bool G1CollectedHeap::verify_region_lists_locked() {
5094 HeapRegion* unclean = _unclean_region_list.hd();
5095 while (unclean != NULL) {
5096 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
5097 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
5098 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
5099 "Everything else is possible.");
5100 unclean = unclean->next_from_unclean_list();
5101 }
5102 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
5103
5104 HeapRegion* free_r = _free_region_list;
5105 while (free_r != NULL) {
5106 assert(free_r->is_on_free_list(), "Well, it is!");
5107 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
5108 switch (free_r->zero_fill_state()) {
5109 case HeapRegion::NotZeroFilled:
5110 case HeapRegion::ZeroFilling:
5111 guarantee(false, "Should not be on free list.");
5112 break;
5113 default:
5114 // Everything else is possible.
5115 break;
5116 }
5117 free_r = free_r->next_from_free_list();
5118 }
5119 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
5120 // If we didn't do an assertion...
5121 return true;
5122 }
5123
5124 size_t G1CollectedHeap::free_region_list_length() {
5125 assert(ZF_mon->owned_by_self(), "precondition.");
5126 size_t len = 0;
5127 HeapRegion* cur = _free_region_list;
5128 while (cur != NULL) {
5129 len++;
5130 cur = cur->next_from_free_list();
5131 }
5132 return len;
5133 }
5134
5135 size_t G1CollectedHeap::unclean_region_list_length() {
5136 assert(ZF_mon->owned_by_self(), "precondition.");
5137 return _unclean_region_list.length();
5138 }
5139
5140 size_t G1CollectedHeap::n_regions() {
5141 return _hrs->length();
5142 }
5143
5144 size_t G1CollectedHeap::max_regions() {
5145 return
5146 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
5147 HeapRegion::GrainBytes;
5148 }
5149
5150 size_t G1CollectedHeap::free_regions() {
5151 /* Possibly-expensive assert.
5152 assert(_free_regions == count_free_regions(),
5153 "_free_regions is off.");
5154 */
5155 return _free_regions;
5156 }
5157
5158 bool G1CollectedHeap::should_zf() {
5159 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
5160 }
5161
5162 class RegionCounter: public HeapRegionClosure {
5163 size_t _n;
5164 public:
5165 RegionCounter() : _n(0) {}
5166 bool doHeapRegion(HeapRegion* r) {
5167 if (r->is_empty() && !r->popular()) {
5168 assert(!r->isHumongous(), "H regions should not be empty.");
5169 _n++;
5170 }
5171 return false;
5172 }
5173 int res() { return (int) _n; }
5174 };
5175
5176 size_t G1CollectedHeap::count_free_regions() {
5177 RegionCounter rc;
5178 heap_region_iterate(&rc);
5179 size_t n = rc.res();
5180 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
5181 n--;
5182 return n;
5183 }
5184
5185 size_t G1CollectedHeap::count_free_regions_list() {
5186 size_t n = 0;
5187 size_t o = 0;
5188 ZF_mon->lock_without_safepoint_check();
5189 HeapRegion* cur = _free_region_list;
5190 while (cur != NULL) {
5191 cur = cur->next_from_free_list();
5192 n++;
5193 }
5194 size_t m = unclean_region_list_length();
5195 ZF_mon->unlock();
5196 return n + m;
5197 }
5198
5199 bool G1CollectedHeap::should_set_young_locked() {
5200 assert(heap_lock_held_for_gc(),
5201 "the heap lock should already be held by or for this thread");
5202 return (g1_policy()->in_young_gc_mode() &&
5203 g1_policy()->should_add_next_region_to_young_list());
5204 }
5205
5206 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5207 assert(heap_lock_held_for_gc(),
5208 "the heap lock should already be held by or for this thread");
5209 _young_list->push_region(hr);
5210 g1_policy()->set_region_short_lived(hr);
5211 }
5212
5213 class NoYoungRegionsClosure: public HeapRegionClosure {
5214 private:
5215 bool _success;
5216 public:
5217 NoYoungRegionsClosure() : _success(true) { }
5218 bool doHeapRegion(HeapRegion* r) {
5219 if (r->is_young()) {
5220 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5221 r->bottom(), r->end());
5222 _success = false;
5223 }
5224 return false;
5225 }
5226 bool success() { return _success; }
5227 };
5228
5229 bool G1CollectedHeap::check_young_list_empty(bool ignore_scan_only_list,
5230 bool check_sample) {
5231 bool ret = true;
5232
5233 ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample);
5234 if (!ignore_scan_only_list) {
5235 NoYoungRegionsClosure closure;
5236 heap_region_iterate(&closure);
5237 ret = ret && closure.success();
5238 }
5239
5240 return ret;
5241 }
5242
5243 void G1CollectedHeap::empty_young_list() {
5244 assert(heap_lock_held_for_gc(),
5245 "the heap lock should already be held by or for this thread");
5246 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
5247
5248 _young_list->empty_list();
5249 }
5250
5251 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
5252 bool no_allocs = true;
5253 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
5254 HeapRegion* r = _gc_alloc_regions[ap];
5255 no_allocs = r == NULL || r->saved_mark_at_top();
5256 }
5257 return no_allocs;
5258 }
5259
5260 void G1CollectedHeap::retire_all_alloc_regions() {
5261 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
5262 HeapRegion* r = _gc_alloc_regions[ap];
5263 if (r != NULL) {
5264 // Check for aliases.
5265 bool has_processed_alias = false;
5266 for (int i = 0; i < ap; ++i) {
5267 if (_gc_alloc_regions[i] == r) {
5268 has_processed_alias = true;
5269 break;
5270 }
5271 }
5272 if (!has_processed_alias) {
5273 retire_alloc_region(r, false /* par */);
5274 }
5275 }
5276 }
5277 }
5278
5279
5280 // Done at the start of full GC.
5281 void G1CollectedHeap::tear_down_region_lists() {
5282 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5283 while (pop_unclean_region_list_locked() != NULL) ;
5284 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
5285 "Postconditions of loop.")
5286 while (pop_free_region_list_locked() != NULL) ;
5287 assert(_free_region_list == NULL, "Postcondition of loop.");
5288 if (_free_region_list_size != 0) {
5289 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
5290 print();
5291 }
5292 assert(_free_region_list_size == 0, "Postconditions of loop.");
5293 }
5294
5295
5296 class RegionResetter: public HeapRegionClosure {
5297 G1CollectedHeap* _g1;
5298 int _n;
5299 public:
5300 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5301 bool doHeapRegion(HeapRegion* r) {
5302 if (r->continuesHumongous()) return false;
5303 if (r->top() > r->bottom()) {
5304 if (r->top() < r->end()) {
5305 Copy::fill_to_words(r->top(),
5306 pointer_delta(r->end(), r->top()));
5307 }
5308 r->set_zero_fill_allocated();
5309 } else {
5310 assert(r->is_empty(), "tautology");
5311 if (r->popular()) {
5312 if (r->zero_fill_state() != HeapRegion::Allocated) {
5313 r->ensure_zero_filled_locked();
5314 r->set_zero_fill_allocated();
5315 }
5316 } else {
5317 _n++;
5318 switch (r->zero_fill_state()) {
5319 case HeapRegion::NotZeroFilled:
5320 case HeapRegion::ZeroFilling:
5321 _g1->put_region_on_unclean_list_locked(r);
5322 break;
5323 case HeapRegion::Allocated:
5324 r->set_zero_fill_complete();
5325 // no break; go on to put on free list.
5326 case HeapRegion::ZeroFilled:
5327 _g1->put_free_region_on_list_locked(r);
5328 break;
5329 }
5330 }
5331 }
5332 return false;
5333 }
5334
5335 int getFreeRegionCount() {return _n;}
5336 };
5337
5338 // Done at the end of full GC.
5339 void G1CollectedHeap::rebuild_region_lists() {
5340 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5341 // This needs to go at the end of the full GC.
5342 RegionResetter rs;
5343 heap_region_iterate(&rs);
5344 _free_regions = rs.getFreeRegionCount();
5345 // Tell the ZF thread it may have work to do.
5346 if (should_zf()) ZF_mon->notify_all();
5347 }
5348
5349 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
5350 G1CollectedHeap* _g1;
5351 int _n;
5352 public:
5353 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5354 bool doHeapRegion(HeapRegion* r) {
5355 if (r->continuesHumongous()) return false;
5356 if (r->top() > r->bottom()) {
5357 // There are assertions in "set_zero_fill_needed()" below that
5358 // require top() == bottom(), so this is technically illegal.
5359 // We'll skirt the law here, by making that true temporarily.
5360 DEBUG_ONLY(HeapWord* save_top = r->top();
5361 r->set_top(r->bottom()));
5362 r->set_zero_fill_needed();
5363 DEBUG_ONLY(r->set_top(save_top));
5364 }
5365 return false;
5366 }
5367 };
5368
5369 // Done at the start of full GC.
5370 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
5371 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5372 // This needs to go at the end of the full GC.
5373 UsedRegionsNeedZeroFillSetter rs;
5374 heap_region_iterate(&rs);
5375 }
5376
5377 class CountObjClosure: public ObjectClosure {
5378 size_t _n;
5379 public:
5380 CountObjClosure() : _n(0) {}
5381 void do_object(oop obj) { _n++; }
5382 size_t n() { return _n; }
5383 };
5384
5385 size_t G1CollectedHeap::pop_object_used_objs() {
5386 size_t sum_objs = 0;
5387 for (int i = 0; i < G1NumPopularRegions; i++) {
5388 CountObjClosure cl;
5389 _hrs->at(i)->object_iterate(&cl);
5390 sum_objs += cl.n();
5391 }
5392 return sum_objs;
5393 }
5394
5395 size_t G1CollectedHeap::pop_object_used_bytes() {
5396 size_t sum_bytes = 0;
5397 for (int i = 0; i < G1NumPopularRegions; i++) {
5398 sum_bytes += _hrs->at(i)->used();
5399 }
5400 return sum_bytes;
5401 }
5402
5403
5404 static int nq = 0;
5405
5406 HeapWord* G1CollectedHeap::allocate_popular_object(size_t word_size) {
5407 while (_cur_pop_hr_index < G1NumPopularRegions) {
5408 HeapRegion* cur_pop_region = _hrs->at(_cur_pop_hr_index);
5409 HeapWord* res = cur_pop_region->allocate(word_size);
5410 if (res != NULL) {
5411 // We account for popular objs directly in the used summary:
5412 _summary_bytes_used += (word_size * HeapWordSize);
5413 return res;
5414 }
5415 // Otherwise, try the next region (first making sure that we remember
5416 // the last "top" value as the "next_top_at_mark_start", so that
5417 // objects made popular during markings aren't automatically considered
5418 // live).
5419 cur_pop_region->note_end_of_copying();
5420 // Otherwise, try the next region.
5421 _cur_pop_hr_index++;
5422 }
5423 // XXX: For now !!!
5424 vm_exit_out_of_memory(word_size,
5425 "Not enough pop obj space (To Be Fixed)");
5426 return NULL;
5427 }
5428
5429 class HeapRegionList: public CHeapObj {
5430 public:
5431 HeapRegion* hr;
5432 HeapRegionList* next;
5433 };
5434
5435 void G1CollectedHeap::schedule_popular_region_evac(HeapRegion* r) {
5436 // This might happen during parallel GC, so protect by this lock.
5437 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
5438 // We don't schedule regions whose evacuations are already pending, or
5439 // are already being evacuated.
5440 if (!r->popular_pending() && !r->in_collection_set()) {
5441 r->set_popular_pending(true);
5442 if (G1TracePopularity) {
5443 gclog_or_tty->print_cr("Scheduling region "PTR_FORMAT" "
5444 "["PTR_FORMAT", "PTR_FORMAT") for pop-object evacuation.",
5445 r, r->bottom(), r->end());
5446 }
5447 HeapRegionList* hrl = new HeapRegionList;
5448 hrl->hr = r;
5449 hrl->next = _popular_regions_to_be_evacuated;
5450 _popular_regions_to_be_evacuated = hrl;
5451 }
5452 }
5453
5454 HeapRegion* G1CollectedHeap::popular_region_to_evac() {
5455 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
5456 HeapRegion* res = NULL;
5457 while (_popular_regions_to_be_evacuated != NULL && res == NULL) {
5458 HeapRegionList* hrl = _popular_regions_to_be_evacuated;
5459 _popular_regions_to_be_evacuated = hrl->next;
5460 res = hrl->hr;
5461 // The G1RSPopLimit may have increased, so recheck here...
5462 if (res->rem_set()->occupied() < (size_t) G1RSPopLimit) {
5463 // Hah: don't need to schedule.
5464 if (G1TracePopularity) {
5465 gclog_or_tty->print_cr("Unscheduling region "PTR_FORMAT" "
5466 "["PTR_FORMAT", "PTR_FORMAT") "
5467 "for pop-object evacuation (size %d < limit %d)",
5468 res, res->bottom(), res->end(),
5469 res->rem_set()->occupied(), G1RSPopLimit);
5470 }
5471 res->set_popular_pending(false);
5472 res = NULL;
5473 }
5474 // We do not reset res->popular() here; if we did so, it would allow
5475 // the region to be "rescheduled" for popularity evacuation. Instead,
5476 // this is done in the collection pause, with the world stopped.
5477 // So the invariant is that the regions in the list have the popularity
5478 // boolean set, but having the boolean set does not imply membership
5479 // on the list (though there can at most one such pop-pending region
5480 // not on the list at any time).
5481 delete hrl;
5482 }
5483 return res;
5484 }
5485
5486 void G1CollectedHeap::evac_popular_region(HeapRegion* hr) {
5487 while (true) {
5488 // Don't want to do a GC pause while cleanup is being completed!
5489 wait_for_cleanup_complete();
5490
5491 // Read the GC count while holding the Heap_lock
5492 int gc_count_before = SharedHeap::heap()->total_collections();
5493 g1_policy()->record_stop_world_start();
5494
5495 {
5496 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
5497 VM_G1PopRegionCollectionPause op(gc_count_before, hr);
5498 VMThread::execute(&op);
5499
5500 // If the prolog succeeded, we didn't do a GC for this.
5501 if (op.prologue_succeeded()) break;
5502 }
5503 // Otherwise we didn't. We should recheck the size, though, since
5504 // the limit may have increased...
5505 if (hr->rem_set()->occupied() < (size_t) G1RSPopLimit) {
5506 hr->set_popular_pending(false);
5507 break;
5508 }
5509 }
5510 }
5511
5512 void G1CollectedHeap::atomic_inc_obj_rc(oop obj) {
5513 Atomic::inc(obj_rc_addr(obj));
5514 }
5515
5516 class CountRCClosure: public OopsInHeapRegionClosure {
5517 G1CollectedHeap* _g1h;
5518 bool _parallel;
5519 public:
5520 CountRCClosure(G1CollectedHeap* g1h) :
5521 _g1h(g1h), _parallel(ParallelGCThreads > 0)
5522 {}
5523 void do_oop(narrowOop* p) {
5524 guarantee(false, "NYI");
5525 }
5526 void do_oop(oop* p) {
5527 oop obj = *p;
5528 assert(obj != NULL, "Precondition.");
5529 if (_parallel) {
5530 // We go sticky at the limit to avoid excess contention.
5531 // If we want to track the actual RC's further, we'll need to keep a
5532 // per-thread hash table or something for the popular objects.
5533 if (_g1h->obj_rc(obj) < G1ObjPopLimit) {
5534 _g1h->atomic_inc_obj_rc(obj);
5535 }
5536 } else {
5537 _g1h->inc_obj_rc(obj);
5538 }
5539 }
5540 };
5541
5542 class EvacPopObjClosure: public ObjectClosure {
5543 G1CollectedHeap* _g1h;
5544 size_t _pop_objs;
5545 size_t _max_rc;
5546 public:
5547 EvacPopObjClosure(G1CollectedHeap* g1h) :
5548 _g1h(g1h), _pop_objs(0), _max_rc(0) {}
5549
5550 void do_object(oop obj) {
5551 size_t rc = _g1h->obj_rc(obj);
5552 _max_rc = MAX2(rc, _max_rc);
5553 if (rc >= (size_t) G1ObjPopLimit) {
5554 _g1h->_pop_obj_rc_at_copy.add((double)rc);
5555 size_t word_sz = obj->size();
5556 HeapWord* new_pop_loc = _g1h->allocate_popular_object(word_sz);
5557 oop new_pop_obj = (oop)new_pop_loc;
5558 Copy::aligned_disjoint_words((HeapWord*)obj, new_pop_loc, word_sz);
5559 obj->forward_to(new_pop_obj);
5560 G1ScanAndBalanceClosure scan_and_balance(_g1h);
5561 new_pop_obj->oop_iterate_backwards(&scan_and_balance);
5562 // preserve "next" mark bit if marking is in progress.
5563 if (_g1h->mark_in_progress() && !_g1h->is_obj_ill(obj)) {
5564 _g1h->concurrent_mark()->markAndGrayObjectIfNecessary(new_pop_obj);
5565 }
5566
5567 if (G1TracePopularity) {
5568 gclog_or_tty->print_cr("Found obj " PTR_FORMAT " of word size " SIZE_FORMAT
5569 " pop (%d), move to " PTR_FORMAT,
5570 (void*) obj, word_sz,
5571 _g1h->obj_rc(obj), (void*) new_pop_obj);
5572 }
5573 _pop_objs++;
5574 }
5575 }
5576 size_t pop_objs() { return _pop_objs; }
5577 size_t max_rc() { return _max_rc; }
5578 };
5579
5580 class G1ParCountRCTask : public AbstractGangTask {
5581 G1CollectedHeap* _g1h;
5582 BitMap _bm;
5583
5584 size_t getNCards() {
5585 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
5586 / G1BlockOffsetSharedArray::N_bytes;
5587 }
5588 CountRCClosure _count_rc_closure;
5589 public:
5590 G1ParCountRCTask(G1CollectedHeap* g1h) :
5591 AbstractGangTask("G1 Par RC Count task"),
5592 _g1h(g1h), _bm(getNCards()), _count_rc_closure(g1h)
5593 {}
5594
5595 void work(int i) {
5596 ResourceMark rm;
5597 HandleMark hm;
5598 _g1h->g1_rem_set()->oops_into_collection_set_do(&_count_rc_closure, i);
5599 }
5600 };
5601
5602 void G1CollectedHeap::popularity_pause_preamble(HeapRegion* popular_region) {
5603 // We're evacuating a single region (for popularity).
5604 if (G1TracePopularity) {
5605 gclog_or_tty->print_cr("Doing pop region pause for ["PTR_FORMAT", "PTR_FORMAT")",
5606 popular_region->bottom(), popular_region->end());
5607 }
5608 g1_policy()->set_single_region_collection_set(popular_region);
5609 size_t max_rc;
5610 if (!compute_reference_counts_and_evac_popular(popular_region,
5611 &max_rc)) {
5612 // We didn't evacuate any popular objects.
5613 // We increase the RS popularity limit, to prevent this from
5614 // happening in the future.
5615 if (G1RSPopLimit < (1 << 30)) {
5616 G1RSPopLimit *= 2;
5617 }
5618 // For now, interesting enough for a message:
5619 #if 1
5620 gclog_or_tty->print_cr("In pop region pause for ["PTR_FORMAT", "PTR_FORMAT"), "
5621 "failed to find a pop object (max = %d).",
5622 popular_region->bottom(), popular_region->end(),
5623 max_rc);
5624 gclog_or_tty->print_cr("Increased G1RSPopLimit to %d.", G1RSPopLimit);
5625 #endif // 0
5626 // Also, we reset the collection set to NULL, to make the rest of
5627 // the collection do nothing.
5628 assert(popular_region->next_in_collection_set() == NULL,
5629 "should be single-region.");
5630 popular_region->set_in_collection_set(false);
5631 popular_region->set_popular_pending(false);
5632 g1_policy()->clear_collection_set();
5633 }
5634 }
5635
5636 bool G1CollectedHeap::
5637 compute_reference_counts_and_evac_popular(HeapRegion* popular_region,
5638 size_t* max_rc) {
5639 HeapWord* rc_region_bot;
5640 HeapWord* rc_region_end;
5641
5642 // Set up the reference count region.
5643 HeapRegion* rc_region = newAllocRegion(HeapRegion::GrainWords);
5644 if (rc_region != NULL) {
5645 rc_region_bot = rc_region->bottom();
5646 rc_region_end = rc_region->end();
5647 } else {
5648 rc_region_bot = NEW_C_HEAP_ARRAY(HeapWord, HeapRegion::GrainWords);
5649 if (rc_region_bot == NULL) {
5650 vm_exit_out_of_memory(HeapRegion::GrainWords,
5651 "No space for RC region.");
5652 }
5653 rc_region_end = rc_region_bot + HeapRegion::GrainWords;
5654 }
5655
5656 if (G1TracePopularity)
5657 gclog_or_tty->print_cr("RC region is ["PTR_FORMAT", "PTR_FORMAT")",
5658 rc_region_bot, rc_region_end);
5659 if (rc_region_bot > popular_region->bottom()) {
5660 _rc_region_above = true;
5661 _rc_region_diff =
5662 pointer_delta(rc_region_bot, popular_region->bottom(), 1);
5663 } else {
5664 assert(rc_region_bot < popular_region->bottom(), "Can't be equal.");
5665 _rc_region_above = false;
5666 _rc_region_diff =
5667 pointer_delta(popular_region->bottom(), rc_region_bot, 1);
5668 }
5669 g1_policy()->record_pop_compute_rc_start();
5670 // Count external references.
5671 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5672 if (ParallelGCThreads > 0) {
5673
5674 set_par_threads(workers()->total_workers());
5675 G1ParCountRCTask par_count_rc_task(this);
5676 workers()->run_task(&par_count_rc_task);
5677 set_par_threads(0);
5678
5679 } else {
5680 CountRCClosure count_rc_closure(this);
5681 g1_rem_set()->oops_into_collection_set_do(&count_rc_closure, 0);
5682 }
5683 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5684 g1_policy()->record_pop_compute_rc_end();
5685
5686 // Now evacuate popular objects.
5687 g1_policy()->record_pop_evac_start();
5688 EvacPopObjClosure evac_pop_obj_cl(this);
5689 popular_region->object_iterate(&evac_pop_obj_cl);
5690 *max_rc = evac_pop_obj_cl.max_rc();
5691
5692 // Make sure the last "top" value of the current popular region is copied
5693 // as the "next_top_at_mark_start", so that objects made popular during
5694 // markings aren't automatically considered live.
5695 HeapRegion* cur_pop_region = _hrs->at(_cur_pop_hr_index);
5696 cur_pop_region->note_end_of_copying();
5697
5698 if (rc_region != NULL) {
5699 free_region(rc_region);
5700 } else {
5701 FREE_C_HEAP_ARRAY(HeapWord, rc_region_bot);
5702 }
5703 g1_policy()->record_pop_evac_end();
5704
5705 return evac_pop_obj_cl.pop_objs() > 0;
5706 }
5707
5708 class CountPopObjInfoClosure: public HeapRegionClosure {
5709 size_t _objs;
5710 size_t _bytes;
5711
5712 class CountObjClosure: public ObjectClosure {
5713 int _n;
5714 public:
5715 CountObjClosure() : _n(0) {}
5716 void do_object(oop obj) { _n++; }
5717 size_t n() { return _n; }
5718 };
5719
5720 public:
5721 CountPopObjInfoClosure() : _objs(0), _bytes(0) {}
5722 bool doHeapRegion(HeapRegion* r) {
5723 _bytes += r->used();
5724 CountObjClosure blk;
5725 r->object_iterate(&blk);
5726 _objs += blk.n();
5727 return false;
5728 }
5729 size_t objs() { return _objs; }
5730 size_t bytes() { return _bytes; }
5731 };
5732
5733
5734 void G1CollectedHeap::print_popularity_summary_info() const {
5735 CountPopObjInfoClosure blk;
5736 for (int i = 0; i <= _cur_pop_hr_index; i++) {
5737 blk.doHeapRegion(_hrs->at(i));
5738 }
5739 gclog_or_tty->print_cr("\nPopular objects: %d objs, %d bytes.",
5740 blk.objs(), blk.bytes());
5741 gclog_or_tty->print_cr(" RC at copy = [avg = %5.2f, max = %5.2f, sd = %5.2f].",
5742 _pop_obj_rc_at_copy.avg(),
5743 _pop_obj_rc_at_copy.maximum(),
5744 _pop_obj_rc_at_copy.sd());
5745 }
5746
5747 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5748 _refine_cte_cl->set_concurrent(concurrent);
5749 }
5750
5751 #ifndef PRODUCT
5752
5753 class PrintHeapRegionClosure: public HeapRegionClosure {
5754 public:
5755 bool doHeapRegion(HeapRegion *r) {
5756 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
5757 if (r != NULL) {
5758 if (r->is_on_free_list())
5759 gclog_or_tty->print("Free ");
5760 if (r->is_young())
5761 gclog_or_tty->print("Young ");
5762 if (r->isHumongous())
5763 gclog_or_tty->print("Is Humongous ");
5764 r->print();
5765 }
5766 return false;
5767 }
5768 };
5769
5770 class SortHeapRegionClosure : public HeapRegionClosure {
5771 size_t young_regions,free_regions, unclean_regions;
5772 size_t hum_regions, count;
5773 size_t unaccounted, cur_unclean, cur_alloc;
5774 size_t total_free;
5775 HeapRegion* cur;
5776 public:
5777 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5778 free_regions(0), unclean_regions(0),
5779 hum_regions(0),
5780 count(0), unaccounted(0),
5781 cur_alloc(0), total_free(0)
5782 {}
5783 bool doHeapRegion(HeapRegion *r) {
5784 count++;
5785 if (r->is_on_free_list()) free_regions++;
5786 else if (r->is_on_unclean_list()) unclean_regions++;
5787 else if (r->isHumongous()) hum_regions++;
5788 else if (r->is_young()) young_regions++;
5789 else if (r == cur) cur_alloc++;
5790 else unaccounted++;
5791 return false;
5792 }
5793 void print() {
5794 total_free = free_regions + unclean_regions;
5795 gclog_or_tty->print("%d regions\n", count);
5796 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5797 total_free, free_regions, unclean_regions);
5798 gclog_or_tty->print("%d humongous %d young\n",
5799 hum_regions, young_regions);
5800 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5801 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5802 }
5803 };
5804
5805 void G1CollectedHeap::print_region_counts() {
5806 SortHeapRegionClosure sc(_cur_alloc_region);
5807 PrintHeapRegionClosure cl;
5808 heap_region_iterate(&cl);
5809 heap_region_iterate(&sc);
5810 sc.print();
5811 print_region_accounting_info();
5812 };
5813
5814 bool G1CollectedHeap::regions_accounted_for() {
5815 // TODO: regions accounting for young/survivor/tenured
5816 return true;
5817 }
5818
5819 bool G1CollectedHeap::print_region_accounting_info() {
5820 gclog_or_tty->print_cr("P regions: %d.", G1NumPopularRegions);
5821 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5822 free_regions(),
5823 count_free_regions(), count_free_regions_list(),
5824 _free_region_list_size, _unclean_region_list.sz());
5825 gclog_or_tty->print_cr("cur_alloc: %d.",
5826 (_cur_alloc_region == NULL ? 0 : 1));
5827 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5828
5829 // TODO: check regions accounting for young/survivor/tenured
5830 return true;
5831 }
5832
5833 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5834 HeapRegion* hr = heap_region_containing(p);
5835 if (hr == NULL) {
5836 return is_in_permanent(p);
5837 } else {
5838 return hr->is_in(p);
5839 }
5840 }
5841 #endif // PRODUCT
5842
5843 void G1CollectedHeap::g1_unimplemented() {
5844 // Unimplemented();
5845 }
5846
5847
5848 // Local Variables: ***
5849 // c-indentation-style: gnu ***
5850 // End: ***