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 class PostMCRemSetClearClosure: public HeapRegionClosure {
790 ModRefBarrierSet* _mr_bs;
791 public:
792 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
793 bool doHeapRegion(HeapRegion* r) {
794 r->reset_gc_time_stamp();
795 if (r->continuesHumongous())
796 return false;
797 HeapRegionRemSet* hrrs = r->rem_set();
798 if (hrrs != NULL) hrrs->clear();
799 // You might think here that we could clear just the cards
800 // corresponding to the used region. But no: if we leave a dirty card
801 // in a region we might allocate into, then it would prevent that card
802 // from being enqueued, and cause it to be missed.
803 // Re: the performance cost: we shouldn't be doing full GC anyway!
804 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
805 return false;
806 }
807 };
808
809
810 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
811 ModRefBarrierSet* _mr_bs;
812 public:
813 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
814 bool doHeapRegion(HeapRegion* r) {
815 if (r->continuesHumongous()) return false;
816 if (r->used_region().word_size() != 0) {
817 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
818 }
819 return false;
820 }
821 };
822
823 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
824 G1CollectedHeap* _g1h;
825 UpdateRSOopClosure _cl;
826 int _worker_i;
827 public:
828 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
829 _cl(g1->g1_rem_set()->as_HRInto_G1RemSet(), worker_i),
830 _worker_i(worker_i),
831 _g1h(g1)
832 { }
833 bool doHeapRegion(HeapRegion* r) {
834 if (!r->continuesHumongous()) {
835 _cl.set_from(r);
836 r->oop_iterate(&_cl);
837 }
838 return false;
839 }
840 };
841
842 class ParRebuildRSTask: public AbstractGangTask {
843 G1CollectedHeap* _g1;
844 public:
845 ParRebuildRSTask(G1CollectedHeap* g1)
846 : AbstractGangTask("ParRebuildRSTask"),
847 _g1(g1)
848 { }
849
850 void work(int i) {
851 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
852 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
853 HeapRegion::RebuildRSClaimValue);
854 }
855 };
856
857 void G1CollectedHeap::do_collection(bool full, bool clear_all_soft_refs,
858 size_t word_size) {
859 ResourceMark rm;
860
861 if (full && DisableExplicitGC) {
862 gclog_or_tty->print("\n\n\nDisabling Explicit GC\n\n\n");
863 return;
864 }
865
866 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
867 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
868
869 if (GC_locker::is_active()) {
870 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
871 }
872
873 {
874 IsGCActiveMark x;
875
876 // Timing
877 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
878 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
879 TraceTime t(full ? "Full GC (System.gc())" : "Full GC", PrintGC, true, gclog_or_tty);
880
881 double start = os::elapsedTime();
882 GCOverheadReporter::recordSTWStart(start);
883 g1_policy()->record_full_collection_start();
884
885 gc_prologue(true);
886 increment_total_collections();
887
888 size_t g1h_prev_used = used();
889 assert(used() == recalculate_used(), "Should be equal");
890
891 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
892 HandleMark hm; // Discard invalid handles created during verification
893 prepare_for_verify();
894 gclog_or_tty->print(" VerifyBeforeGC:");
895 Universe::verify(true);
896 }
897 assert(regions_accounted_for(), "Region leakage!");
898
899 COMPILER2_PRESENT(DerivedPointerTable::clear());
900
901 // We want to discover references, but not process them yet.
902 // This mode is disabled in
903 // instanceRefKlass::process_discovered_references if the
904 // generation does some collection work, or
905 // instanceRefKlass::enqueue_discovered_references if the
906 // generation returns without doing any work.
907 ref_processor()->disable_discovery();
908 ref_processor()->abandon_partial_discovery();
909 ref_processor()->verify_no_references_recorded();
910
911 // Abandon current iterations of concurrent marking and concurrent
912 // refinement, if any are in progress.
913 concurrent_mark()->abort();
914
915 // Make sure we'll choose a new allocation region afterwards.
916 abandon_cur_alloc_region();
917 assert(_cur_alloc_region == NULL, "Invariant.");
918 g1_rem_set()->as_HRInto_G1RemSet()->cleanupHRRS();
919 tear_down_region_lists();
920 set_used_regions_to_need_zero_fill();
921 if (g1_policy()->in_young_gc_mode()) {
922 empty_young_list();
923 g1_policy()->set_full_young_gcs(true);
924 }
925
926 // Temporarily make reference _discovery_ single threaded (non-MT).
927 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
928
929 // Temporarily make refs discovery atomic
930 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
931
932 // Temporarily clear _is_alive_non_header
933 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
934
935 ref_processor()->enable_discovery();
936 ref_processor()->setup_policy(clear_all_soft_refs);
937
938 // Do collection work
939 {
940 HandleMark hm; // Discard invalid handles created during gc
941 G1MarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);
942 }
943 // Because freeing humongous regions may have added some unclean
944 // regions, it is necessary to tear down again before rebuilding.
945 tear_down_region_lists();
946 rebuild_region_lists();
947
948 _summary_bytes_used = recalculate_used();
949
950 ref_processor()->enqueue_discovered_references();
951
952 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
953
954 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
955 HandleMark hm; // Discard invalid handles created during verification
956 gclog_or_tty->print(" VerifyAfterGC:");
957 prepare_for_verify();
958 Universe::verify(false);
959 }
960 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
961
962 reset_gc_time_stamp();
963 // Since everything potentially moved, we will clear all remembered
964 // sets, and clear all cards. Later we will rebuild remebered
965 // sets. We will also reset the GC time stamps of the regions.
966 PostMCRemSetClearClosure rs_clear(mr_bs());
967 heap_region_iterate(&rs_clear);
968
969 // Resize the heap if necessary.
970 resize_if_necessary_after_full_collection(full ? 0 : word_size);
971
972 if (_cg1r->use_cache()) {
973 _cg1r->clear_and_record_card_counts();
974 _cg1r->clear_hot_cache();
975 }
976
977 // Rebuild remembered sets of all regions.
978 if (ParallelGCThreads > 0) {
979 ParRebuildRSTask rebuild_rs_task(this);
980 assert(check_heap_region_claim_values(
981 HeapRegion::InitialClaimValue), "sanity check");
982 set_par_threads(workers()->total_workers());
983 workers()->run_task(&rebuild_rs_task);
984 set_par_threads(0);
985 assert(check_heap_region_claim_values(
986 HeapRegion::RebuildRSClaimValue), "sanity check");
987 reset_heap_region_claim_values();
988 } else {
989 RebuildRSOutOfRegionClosure rebuild_rs(this);
990 heap_region_iterate(&rebuild_rs);
991 }
992
993 if (PrintGC) {
994 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
995 }
996
997 if (true) { // FIXME
998 // Ask the permanent generation to adjust size for full collections
999 perm()->compute_new_size();
1000 }
1001
1002 double end = os::elapsedTime();
1003 GCOverheadReporter::recordSTWEnd(end);
1004 g1_policy()->record_full_collection_end();
1005
1006 #ifdef TRACESPINNING
1007 ParallelTaskTerminator::print_termination_counts();
1008 #endif
1009
1010 gc_epilogue(true);
1011
1012 // Abandon concurrent refinement. This must happen last: in the
1013 // dirty-card logging system, some cards may be dirty by weak-ref
1014 // processing, and may be enqueued. But the whole card table is
1015 // dirtied, so this should abandon those logs, and set "do_traversal"
1016 // to true.
1017 concurrent_g1_refine()->set_pya_restart();
1018 assert(!G1DeferredRSUpdate
1019 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1020 assert(regions_accounted_for(), "Region leakage!");
1021 }
1022
1023 if (g1_policy()->in_young_gc_mode()) {
1024 _young_list->reset_sampled_info();
1025 assert( check_young_list_empty(false, false),
1026 "young list should be empty at this point");
1027 }
1028 }
1029
1030 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1031 do_collection(true, clear_all_soft_refs, 0);
1032 }
1033
1034 // This code is mostly copied from TenuredGeneration.
1035 void
1036 G1CollectedHeap::
1037 resize_if_necessary_after_full_collection(size_t word_size) {
1038 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1039
1040 // Include the current allocation, if any, and bytes that will be
1041 // pre-allocated to support collections, as "used".
1042 const size_t used_after_gc = used();
1043 const size_t capacity_after_gc = capacity();
1044 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1045
1046 // We don't have floating point command-line arguments
1047 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100;
1048 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1049 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
1050 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1051
1052 size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage);
1053 size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage);
1054
1055 // Don't shrink less than the initial size.
1056 minimum_desired_capacity =
1057 MAX2(minimum_desired_capacity,
1058 collector_policy()->initial_heap_byte_size());
1059 maximum_desired_capacity =
1060 MAX2(maximum_desired_capacity,
1061 collector_policy()->initial_heap_byte_size());
1062
1063 // We are failing here because minimum_desired_capacity is
1064 assert(used_after_gc <= minimum_desired_capacity, "sanity check");
1065 assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check");
1066
1067 if (PrintGC && Verbose) {
1068 const double free_percentage = ((double)free_after_gc) / capacity();
1069 gclog_or_tty->print_cr("Computing new size after full GC ");
1070 gclog_or_tty->print_cr(" "
1071 " minimum_free_percentage: %6.2f",
1072 minimum_free_percentage);
1073 gclog_or_tty->print_cr(" "
1074 " maximum_free_percentage: %6.2f",
1075 maximum_free_percentage);
1076 gclog_or_tty->print_cr(" "
1077 " capacity: %6.1fK"
1078 " minimum_desired_capacity: %6.1fK"
1079 " maximum_desired_capacity: %6.1fK",
1080 capacity() / (double) K,
1081 minimum_desired_capacity / (double) K,
1082 maximum_desired_capacity / (double) K);
1083 gclog_or_tty->print_cr(" "
1084 " free_after_gc : %6.1fK"
1085 " used_after_gc : %6.1fK",
1086 free_after_gc / (double) K,
1087 used_after_gc / (double) K);
1088 gclog_or_tty->print_cr(" "
1089 " free_percentage: %6.2f",
1090 free_percentage);
1091 }
1092 if (capacity() < minimum_desired_capacity) {
1093 // Don't expand unless it's significant
1094 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1095 expand(expand_bytes);
1096 if (PrintGC && Verbose) {
1097 gclog_or_tty->print_cr(" expanding:"
1098 " minimum_desired_capacity: %6.1fK"
1099 " expand_bytes: %6.1fK",
1100 minimum_desired_capacity / (double) K,
1101 expand_bytes / (double) K);
1102 }
1103
1104 // No expansion, now see if we want to shrink
1105 } else if (capacity() > maximum_desired_capacity) {
1106 // Capacity too large, compute shrinking size
1107 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1108 shrink(shrink_bytes);
1109 if (PrintGC && Verbose) {
1110 gclog_or_tty->print_cr(" "
1111 " shrinking:"
1112 " initSize: %.1fK"
1113 " maximum_desired_capacity: %.1fK",
1114 collector_policy()->initial_heap_byte_size() / (double) K,
1115 maximum_desired_capacity / (double) K);
1116 gclog_or_tty->print_cr(" "
1117 " shrink_bytes: %.1fK",
1118 shrink_bytes / (double) K);
1119 }
1120 }
1121 }
1122
1123
1124 HeapWord*
1125 G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
1126 HeapWord* result = NULL;
1127
1128 // In a G1 heap, we're supposed to keep allocation from failing by
1129 // incremental pauses. Therefore, at least for now, we'll favor
1130 // expansion over collection. (This might change in the future if we can
1131 // do something smarter than full collection to satisfy a failed alloc.)
1132
1133 result = expand_and_allocate(word_size);
1134 if (result != NULL) {
1135 assert(is_in(result), "result not in heap");
1136 return result;
1137 }
1138
1139 // OK, I guess we have to try collection.
1140
1141 do_collection(false, false, word_size);
1142
1143 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1144
1145 if (result != NULL) {
1146 assert(is_in(result), "result not in heap");
1147 return result;
1148 }
1149
1150 // Try collecting soft references.
1151 do_collection(false, true, word_size);
1152 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1153 if (result != NULL) {
1154 assert(is_in(result), "result not in heap");
1155 return result;
1156 }
1157
1158 // What else? We might try synchronous finalization later. If the total
1159 // space available is large enough for the allocation, then a more
1160 // complete compaction phase than we've tried so far might be
1161 // appropriate.
1162 return NULL;
1163 }
1164
1165 // Attempting to expand the heap sufficiently
1166 // to support an allocation of the given "word_size". If
1167 // successful, perform the allocation and return the address of the
1168 // allocated block, or else "NULL".
1169
1170 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1171 size_t expand_bytes = word_size * HeapWordSize;
1172 if (expand_bytes < MinHeapDeltaBytes) {
1173 expand_bytes = MinHeapDeltaBytes;
1174 }
1175 expand(expand_bytes);
1176 assert(regions_accounted_for(), "Region leakage!");
1177 HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
1178 return result;
1179 }
1180
1181 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
1182 size_t pre_used = 0;
1183 size_t cleared_h_regions = 0;
1184 size_t freed_regions = 0;
1185 UncleanRegionList local_list;
1186 free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
1187 freed_regions, &local_list);
1188
1189 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
1190 &local_list);
1191 return pre_used;
1192 }
1193
1194 void
1195 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
1196 size_t& pre_used,
1197 size_t& cleared_h,
1198 size_t& freed_regions,
1199 UncleanRegionList* list,
1200 bool par) {
1201 assert(!hr->continuesHumongous(), "should have filtered these out");
1202 size_t res = 0;
1203 if (!hr->popular() && hr->used() > 0 && hr->garbage_bytes() == hr->used()) {
1204 if (!hr->is_young()) {
1205 if (G1PolicyVerbose > 0)
1206 gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
1207 " during cleanup", hr, hr->used());
1208 free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
1209 }
1210 }
1211 }
1212
1213 // FIXME: both this and shrink could probably be more efficient by
1214 // doing one "VirtualSpace::expand_by" call rather than several.
1215 void G1CollectedHeap::expand(size_t expand_bytes) {
1216 size_t old_mem_size = _g1_storage.committed_size();
1217 // We expand by a minimum of 1K.
1218 expand_bytes = MAX2(expand_bytes, (size_t)K);
1219 size_t aligned_expand_bytes =
1220 ReservedSpace::page_align_size_up(expand_bytes);
1221 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1222 HeapRegion::GrainBytes);
1223 expand_bytes = aligned_expand_bytes;
1224 while (expand_bytes > 0) {
1225 HeapWord* base = (HeapWord*)_g1_storage.high();
1226 // Commit more storage.
1227 bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
1228 if (!successful) {
1229 expand_bytes = 0;
1230 } else {
1231 expand_bytes -= HeapRegion::GrainBytes;
1232 // Expand the committed region.
1233 HeapWord* high = (HeapWord*) _g1_storage.high();
1234 _g1_committed.set_end(high);
1235 // Create a new HeapRegion.
1236 MemRegion mr(base, high);
1237 bool is_zeroed = !_g1_max_committed.contains(base);
1238 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1239
1240 // Now update max_committed if necessary.
1241 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
1242
1243 // Add it to the HeapRegionSeq.
1244 _hrs->insert(hr);
1245 // Set the zero-fill state, according to whether it's already
1246 // zeroed.
1247 {
1248 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
1249 if (is_zeroed) {
1250 hr->set_zero_fill_complete();
1251 put_free_region_on_list_locked(hr);
1252 } else {
1253 hr->set_zero_fill_needed();
1254 put_region_on_unclean_list_locked(hr);
1255 }
1256 }
1257 _free_regions++;
1258 // And we used up an expansion region to create it.
1259 _expansion_regions--;
1260 // Tell the cardtable about it.
1261 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1262 // And the offset table as well.
1263 _bot_shared->resize(_g1_committed.word_size());
1264 }
1265 }
1266 if (Verbose && PrintGC) {
1267 size_t new_mem_size = _g1_storage.committed_size();
1268 gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
1269 old_mem_size/K, aligned_expand_bytes/K,
1270 new_mem_size/K);
1271 }
1272 }
1273
1274 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1275 {
1276 size_t old_mem_size = _g1_storage.committed_size();
1277 size_t aligned_shrink_bytes =
1278 ReservedSpace::page_align_size_down(shrink_bytes);
1279 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1280 HeapRegion::GrainBytes);
1281 size_t num_regions_deleted = 0;
1282 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1283
1284 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1285 if (mr.byte_size() > 0)
1286 _g1_storage.shrink_by(mr.byte_size());
1287 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1288
1289 _g1_committed.set_end(mr.start());
1290 _free_regions -= num_regions_deleted;
1291 _expansion_regions += num_regions_deleted;
1292
1293 // Tell the cardtable about it.
1294 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1295
1296 // And the offset table as well.
1297 _bot_shared->resize(_g1_committed.word_size());
1298
1299 HeapRegionRemSet::shrink_heap(n_regions());
1300
1301 if (Verbose && PrintGC) {
1302 size_t new_mem_size = _g1_storage.committed_size();
1303 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1304 old_mem_size/K, aligned_shrink_bytes/K,
1305 new_mem_size/K);
1306 }
1307 }
1308
1309 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1310 release_gc_alloc_regions();
1311 tear_down_region_lists(); // We will rebuild them in a moment.
1312 shrink_helper(shrink_bytes);
1313 rebuild_region_lists();
1314 }
1315
1316 // Public methods.
1317
1318 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1319 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1320 #endif // _MSC_VER
1321
1322
1323 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1324 SharedHeap(policy_),
1325 _g1_policy(policy_),
1326 _ref_processor(NULL),
1327 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1328 _bot_shared(NULL),
1329 _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
1330 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1331 _evac_failure_scan_stack(NULL) ,
1332 _mark_in_progress(false),
1333 _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
1334 _cur_alloc_region(NULL),
1335 _refine_cte_cl(NULL),
1336 _free_region_list(NULL), _free_region_list_size(0),
1337 _free_regions(0),
1338 _popular_object_boundary(NULL),
1339 _cur_pop_hr_index(0),
1340 _popular_regions_to_be_evacuated(NULL),
1341 _pop_obj_rc_at_copy(),
1342 _full_collection(false),
1343 _unclean_region_list(),
1344 _unclean_regions_coming(false),
1345 _young_list(new YoungList(this)),
1346 _gc_time_stamp(0),
1347 _surviving_young_words(NULL),
1348 _in_cset_fast_test(NULL),
1349 _in_cset_fast_test_base(NULL)
1350 {
1351 _g1h = this; // To catch bugs.
1352 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1353 vm_exit_during_initialization("Failed necessary allocation.");
1354 }
1355 int n_queues = MAX2((int)ParallelGCThreads, 1);
1356 _task_queues = new RefToScanQueueSet(n_queues);
1357
1358 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1359 assert(n_rem_sets > 0, "Invariant.");
1360
1361 HeapRegionRemSetIterator** iter_arr =
1362 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1363 for (int i = 0; i < n_queues; i++) {
1364 iter_arr[i] = new HeapRegionRemSetIterator();
1365 }
1366 _rem_set_iterator = iter_arr;
1367
1368 for (int i = 0; i < n_queues; i++) {
1369 RefToScanQueue* q = new RefToScanQueue();
1370 q->initialize();
1371 _task_queues->register_queue(i, q);
1372 }
1373
1374 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1375 _gc_alloc_regions[ap] = NULL;
1376 _gc_alloc_region_counts[ap] = 0;
1377 }
1378 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1379 }
1380
1381 jint G1CollectedHeap::initialize() {
1382 os::enable_vtime();
1383
1384 // Necessary to satisfy locking discipline assertions.
1385
1386 MutexLocker x(Heap_lock);
1387
1388 // While there are no constraints in the GC code that HeapWordSize
1389 // be any particular value, there are multiple other areas in the
1390 // system which believe this to be true (e.g. oop->object_size in some
1391 // cases incorrectly returns the size in wordSize units rather than
1392 // HeapWordSize).
1393 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1394
1395 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1396 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1397
1398 // Ensure that the sizes are properly aligned.
1399 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1400 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1401
1402 // We allocate this in any case, but only do no work if the command line
1403 // param is off.
1404 _cg1r = new ConcurrentG1Refine();
1405
1406 // Reserve the maximum.
1407 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1408 // Includes the perm-gen.
1409 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1410 HeapRegion::GrainBytes,
1411 false /*ism*/);
1412
1413 if (!heap_rs.is_reserved()) {
1414 vm_exit_during_initialization("Could not reserve enough space for object heap");
1415 return JNI_ENOMEM;
1416 }
1417
1418 // It is important to do this in a way such that concurrent readers can't
1419 // temporarily think somethings in the heap. (I've actually seen this
1420 // happen in asserts: DLD.)
1421 _reserved.set_word_size(0);
1422 _reserved.set_start((HeapWord*)heap_rs.base());
1423 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1424
1425 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1426
1427 _num_humongous_regions = 0;
1428
1429 // Create the gen rem set (and barrier set) for the entire reserved region.
1430 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1431 set_barrier_set(rem_set()->bs());
1432 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1433 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1434 } else {
1435 vm_exit_during_initialization("G1 requires a mod ref bs.");
1436 return JNI_ENOMEM;
1437 }
1438
1439 // Also create a G1 rem set.
1440 if (G1UseHRIntoRS) {
1441 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1442 _g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs());
1443 } else {
1444 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1445 return JNI_ENOMEM;
1446 }
1447 } else {
1448 _g1_rem_set = new StupidG1RemSet(this);
1449 }
1450
1451 // Carve out the G1 part of the heap.
1452
1453 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1454 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1455 g1_rs.size()/HeapWordSize);
1456 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1457
1458 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1459
1460 _g1_storage.initialize(g1_rs, 0);
1461 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1462 _g1_max_committed = _g1_committed;
1463 _hrs = new HeapRegionSeq(_expansion_regions);
1464 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1465 guarantee(_cur_alloc_region == NULL, "from constructor");
1466
1467 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1468 heap_word_size(init_byte_size));
1469
1470 _g1h = this;
1471
1472 // Create the ConcurrentMark data structure and thread.
1473 // (Must do this late, so that "max_regions" is defined.)
1474 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1475 _cmThread = _cm->cmThread();
1476
1477 // ...and the concurrent zero-fill thread, if necessary.
1478 if (G1ConcZeroFill) {
1479 _czft = new ConcurrentZFThread();
1480 }
1481
1482
1483
1484 // Allocate the popular regions; take them off free lists.
1485 size_t pop_byte_size = G1NumPopularRegions * HeapRegion::GrainBytes;
1486 expand(pop_byte_size);
1487 _popular_object_boundary =
1488 _g1_reserved.start() + (G1NumPopularRegions * HeapRegion::GrainWords);
1489 for (int i = 0; i < G1NumPopularRegions; i++) {
1490 HeapRegion* hr = newAllocRegion(HeapRegion::GrainWords);
1491 // assert(hr != NULL && hr->bottom() < _popular_object_boundary,
1492 // "Should be enough, and all should be below boundary.");
1493 hr->set_popular(true);
1494 }
1495 assert(_cur_pop_hr_index == 0, "Start allocating at the first region.");
1496
1497 // Initialize the from_card cache structure of HeapRegionRemSet.
1498 HeapRegionRemSet::init_heap(max_regions());
1499
1500 // Now expand into the rest of the initial heap size.
1501 expand(init_byte_size - pop_byte_size);
1502
1503 // Perform any initialization actions delegated to the policy.
1504 g1_policy()->init();
1505
1506 g1_policy()->note_start_of_mark_thread();
1507
1508 _refine_cte_cl =
1509 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1510 g1_rem_set(),
1511 concurrent_g1_refine());
1512 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1513
1514 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1515 SATB_Q_FL_lock,
1516 0,
1517 Shared_SATB_Q_lock);
1518 if (G1RSBarrierUseQueue) {
1519 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1520 DirtyCardQ_FL_lock,
1521 G1DirtyCardQueueMax,
1522 Shared_DirtyCardQ_lock);
1523 }
1524 if (G1DeferredRSUpdate) {
1525 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1526 DirtyCardQ_FL_lock,
1527 0,
1528 Shared_DirtyCardQ_lock,
1529 &JavaThread::dirty_card_queue_set());
1530 }
1531 // In case we're keeping closure specialization stats, initialize those
1532 // counts and that mechanism.
1533 SpecializationStats::clear();
1534
1535 _gc_alloc_region_list = NULL;
1536
1537 // Do later initialization work for concurrent refinement.
1538 _cg1r->init();
1539
1540 const char* group_names[] = { "CR", "ZF", "CM", "CL" };
1541 GCOverheadReporter::initGCOverheadReporter(4, group_names);
1542
1543 return JNI_OK;
1544 }
1545
1546 void G1CollectedHeap::ref_processing_init() {
1547 SharedHeap::ref_processing_init();
1548 MemRegion mr = reserved_region();
1549 _ref_processor = ReferenceProcessor::create_ref_processor(
1550 mr, // span
1551 false, // Reference discovery is not atomic
1552 // (though it shouldn't matter here.)
1553 true, // mt_discovery
1554 NULL, // is alive closure: need to fill this in for efficiency
1555 ParallelGCThreads,
1556 ParallelRefProcEnabled,
1557 true); // Setting next fields of discovered
1558 // lists requires a barrier.
1559 }
1560
1561 size_t G1CollectedHeap::capacity() const {
1562 return _g1_committed.byte_size();
1563 }
1564
1565 void G1CollectedHeap::iterate_dirty_card_closure(bool concurrent,
1566 int worker_i) {
1567 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1568 int n_completed_buffers = 0;
1569 while (dcqs.apply_closure_to_completed_buffer(worker_i, 0, true)) {
1570 n_completed_buffers++;
1571 }
1572 g1_policy()->record_update_rs_processed_buffers(worker_i,
1573 (double) n_completed_buffers);
1574 dcqs.clear_n_completed_buffers();
1575 // Finish up the queue...
1576 if (worker_i == 0) concurrent_g1_refine()->clean_up_cache(worker_i,
1577 g1_rem_set());
1578 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1579 }
1580
1581
1582 // Computes the sum of the storage used by the various regions.
1583
1584 size_t G1CollectedHeap::used() const {
1585 assert(Heap_lock->owner() != NULL,
1586 "Should be owned on this thread's behalf.");
1587 size_t result = _summary_bytes_used;
1588 if (_cur_alloc_region != NULL)
1589 result += _cur_alloc_region->used();
1590 return result;
1591 }
1592
1593 class SumUsedClosure: public HeapRegionClosure {
1594 size_t _used;
1595 public:
1596 SumUsedClosure() : _used(0) {}
1597 bool doHeapRegion(HeapRegion* r) {
1598 if (!r->continuesHumongous()) {
1599 _used += r->used();
1600 }
1601 return false;
1602 }
1603 size_t result() { return _used; }
1604 };
1605
1606 size_t G1CollectedHeap::recalculate_used() const {
1607 SumUsedClosure blk;
1608 _hrs->iterate(&blk);
1609 return blk.result();
1610 }
1611
1612 #ifndef PRODUCT
1613 class SumUsedRegionsClosure: public HeapRegionClosure {
1614 size_t _num;
1615 public:
1616 // _num is set to 1 to account for the popular region
1617 SumUsedRegionsClosure() : _num(G1NumPopularRegions) {}
1618 bool doHeapRegion(HeapRegion* r) {
1619 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
1620 _num += 1;
1621 }
1622 return false;
1623 }
1624 size_t result() { return _num; }
1625 };
1626
1627 size_t G1CollectedHeap::recalculate_used_regions() const {
1628 SumUsedRegionsClosure blk;
1629 _hrs->iterate(&blk);
1630 return blk.result();
1631 }
1632 #endif // PRODUCT
1633
1634 size_t G1CollectedHeap::unsafe_max_alloc() {
1635 if (_free_regions > 0) return HeapRegion::GrainBytes;
1636 // otherwise, is there space in the current allocation region?
1637
1638 // We need to store the current allocation region in a local variable
1639 // here. The problem is that this method doesn't take any locks and
1640 // there may be other threads which overwrite the current allocation
1641 // region field. attempt_allocation(), for example, sets it to NULL
1642 // and this can happen *after* the NULL check here but before the call
1643 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
1644 // to be a problem in the optimized build, since the two loads of the
1645 // current allocation region field are optimized away.
1646 HeapRegion* car = _cur_alloc_region;
1647
1648 // FIXME: should iterate over all regions?
1649 if (car == NULL) {
1650 return 0;
1651 }
1652 return car->free();
1653 }
1654
1655 void G1CollectedHeap::collect(GCCause::Cause cause) {
1656 // The caller doesn't have the Heap_lock
1657 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
1658 MutexLocker ml(Heap_lock);
1659 collect_locked(cause);
1660 }
1661
1662 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
1663 assert(Thread::current()->is_VM_thread(), "Precondition#1");
1664 assert(Heap_lock->is_locked(), "Precondition#2");
1665 GCCauseSetter gcs(this, cause);
1666 switch (cause) {
1667 case GCCause::_heap_inspection:
1668 case GCCause::_heap_dump: {
1669 HandleMark hm;
1670 do_full_collection(false); // don't clear all soft refs
1671 break;
1672 }
1673 default: // XXX FIX ME
1674 ShouldNotReachHere(); // Unexpected use of this function
1675 }
1676 }
1677
1678
1679 void G1CollectedHeap::collect_locked(GCCause::Cause cause) {
1680 // Don't want to do a GC until cleanup is completed.
1681 wait_for_cleanup_complete();
1682
1683 // Read the GC count while holding the Heap_lock
1684 int gc_count_before = SharedHeap::heap()->total_collections();
1685 {
1686 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
1687 VM_G1CollectFull op(gc_count_before, cause);
1688 VMThread::execute(&op);
1689 }
1690 }
1691
1692 bool G1CollectedHeap::is_in(const void* p) const {
1693 if (_g1_committed.contains(p)) {
1694 HeapRegion* hr = _hrs->addr_to_region(p);
1695 return hr->is_in(p);
1696 } else {
1697 return _perm_gen->as_gen()->is_in(p);
1698 }
1699 }
1700
1701 // Iteration functions.
1702
1703 // Iterates an OopClosure over all ref-containing fields of objects
1704 // within a HeapRegion.
1705
1706 class IterateOopClosureRegionClosure: public HeapRegionClosure {
1707 MemRegion _mr;
1708 OopClosure* _cl;
1709 public:
1710 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
1711 : _mr(mr), _cl(cl) {}
1712 bool doHeapRegion(HeapRegion* r) {
1713 if (! r->continuesHumongous()) {
1714 r->oop_iterate(_cl);
1715 }
1716 return false;
1717 }
1718 };
1719
1720 void G1CollectedHeap::oop_iterate(OopClosure* cl) {
1721 IterateOopClosureRegionClosure blk(_g1_committed, cl);
1722 _hrs->iterate(&blk);
1723 }
1724
1725 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) {
1726 IterateOopClosureRegionClosure blk(mr, cl);
1727 _hrs->iterate(&blk);
1728 }
1729
1730 // Iterates an ObjectClosure over all objects within a HeapRegion.
1731
1732 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1733 ObjectClosure* _cl;
1734 public:
1735 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1736 bool doHeapRegion(HeapRegion* r) {
1737 if (! r->continuesHumongous()) {
1738 r->object_iterate(_cl);
1739 }
1740 return false;
1741 }
1742 };
1743
1744 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
1745 IterateObjectClosureRegionClosure blk(cl);
1746 _hrs->iterate(&blk);
1747 }
1748
1749 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1750 // FIXME: is this right?
1751 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
1752 }
1753
1754 // Calls a SpaceClosure on a HeapRegion.
1755
1756 class SpaceClosureRegionClosure: public HeapRegionClosure {
1757 SpaceClosure* _cl;
1758 public:
1759 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1760 bool doHeapRegion(HeapRegion* r) {
1761 _cl->do_space(r);
1762 return false;
1763 }
1764 };
1765
1766 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
1767 SpaceClosureRegionClosure blk(cl);
1768 _hrs->iterate(&blk);
1769 }
1770
1771 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
1772 _hrs->iterate(cl);
1773 }
1774
1775 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
1776 HeapRegionClosure* cl) {
1777 _hrs->iterate_from(r, cl);
1778 }
1779
1780 void
1781 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
1782 _hrs->iterate_from(idx, cl);
1783 }
1784
1785 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
1786
1787 void
1788 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1789 int worker,
1790 jint claim_value) {
1791 const size_t regions = n_regions();
1792 const size_t worker_num = (ParallelGCThreads > 0 ? ParallelGCThreads : 1);
1793 // try to spread out the starting points of the workers
1794 const size_t start_index = regions / worker_num * (size_t) worker;
1795
1796 // each worker will actually look at all regions
1797 for (size_t count = 0; count < regions; ++count) {
1798 const size_t index = (start_index + count) % regions;
1799 assert(0 <= index && index < regions, "sanity");
1800 HeapRegion* r = region_at(index);
1801 // we'll ignore "continues humongous" regions (we'll process them
1802 // when we come across their corresponding "start humongous"
1803 // region) and regions already claimed
1804 if (r->claim_value() == claim_value || r->continuesHumongous()) {
1805 continue;
1806 }
1807 // OK, try to claim it
1808 if (r->claimHeapRegion(claim_value)) {
1809 // success!
1810 assert(!r->continuesHumongous(), "sanity");
1811 if (r->startsHumongous()) {
1812 // If the region is "starts humongous" we'll iterate over its
1813 // "continues humongous" first; in fact we'll do them
1814 // first. The order is important. In on case, calling the
1815 // closure on the "starts humongous" region might de-allocate
1816 // and clear all its "continues humongous" regions and, as a
1817 // result, we might end up processing them twice. So, we'll do
1818 // them first (notice: most closures will ignore them anyway) and
1819 // then we'll do the "starts humongous" region.
1820 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
1821 HeapRegion* chr = region_at(ch_index);
1822
1823 // if the region has already been claimed or it's not
1824 // "continues humongous" we're done
1825 if (chr->claim_value() == claim_value ||
1826 !chr->continuesHumongous()) {
1827 break;
1828 }
1829
1830 // Noone should have claimed it directly. We can given
1831 // that we claimed its "starts humongous" region.
1832 assert(chr->claim_value() != claim_value, "sanity");
1833 assert(chr->humongous_start_region() == r, "sanity");
1834
1835 if (chr->claimHeapRegion(claim_value)) {
1836 // we should always be able to claim it; noone else should
1837 // be trying to claim this region
1838
1839 bool res2 = cl->doHeapRegion(chr);
1840 assert(!res2, "Should not abort");
1841
1842 // Right now, this holds (i.e., no closure that actually
1843 // does something with "continues humongous" regions
1844 // clears them). We might have to weaken it in the future,
1845 // but let's leave these two asserts here for extra safety.
1846 assert(chr->continuesHumongous(), "should still be the case");
1847 assert(chr->humongous_start_region() == r, "sanity");
1848 } else {
1849 guarantee(false, "we should not reach here");
1850 }
1851 }
1852 }
1853
1854 assert(!r->continuesHumongous(), "sanity");
1855 bool res = cl->doHeapRegion(r);
1856 assert(!res, "Should not abort");
1857 }
1858 }
1859 }
1860
1861 class ResetClaimValuesClosure: public HeapRegionClosure {
1862 public:
1863 bool doHeapRegion(HeapRegion* r) {
1864 r->set_claim_value(HeapRegion::InitialClaimValue);
1865 return false;
1866 }
1867 };
1868
1869 void
1870 G1CollectedHeap::reset_heap_region_claim_values() {
1871 ResetClaimValuesClosure blk;
1872 heap_region_iterate(&blk);
1873 }
1874
1875 #ifdef ASSERT
1876 // This checks whether all regions in the heap have the correct claim
1877 // value. I also piggy-backed on this a check to ensure that the
1878 // humongous_start_region() information on "continues humongous"
1879 // regions is correct.
1880
1881 class CheckClaimValuesClosure : public HeapRegionClosure {
1882 private:
1883 jint _claim_value;
1884 size_t _failures;
1885 HeapRegion* _sh_region;
1886 public:
1887 CheckClaimValuesClosure(jint claim_value) :
1888 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
1889 bool doHeapRegion(HeapRegion* r) {
1890 if (r->claim_value() != _claim_value) {
1891 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1892 "claim value = %d, should be %d",
1893 r->bottom(), r->end(), r->claim_value(),
1894 _claim_value);
1895 ++_failures;
1896 }
1897 if (!r->isHumongous()) {
1898 _sh_region = NULL;
1899 } else if (r->startsHumongous()) {
1900 _sh_region = r;
1901 } else if (r->continuesHumongous()) {
1902 if (r->humongous_start_region() != _sh_region) {
1903 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1904 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
1905 r->bottom(), r->end(),
1906 r->humongous_start_region(),
1907 _sh_region);
1908 ++_failures;
1909 }
1910 }
1911 return false;
1912 }
1913 size_t failures() {
1914 return _failures;
1915 }
1916 };
1917
1918 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
1919 CheckClaimValuesClosure cl(claim_value);
1920 heap_region_iterate(&cl);
1921 return cl.failures() == 0;
1922 }
1923 #endif // ASSERT
1924
1925 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
1926 HeapRegion* r = g1_policy()->collection_set();
1927 while (r != NULL) {
1928 HeapRegion* next = r->next_in_collection_set();
1929 if (cl->doHeapRegion(r)) {
1930 cl->incomplete();
1931 return;
1932 }
1933 r = next;
1934 }
1935 }
1936
1937 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
1938 HeapRegionClosure *cl) {
1939 assert(r->in_collection_set(),
1940 "Start region must be a member of the collection set.");
1941 HeapRegion* cur = r;
1942 while (cur != NULL) {
1943 HeapRegion* next = cur->next_in_collection_set();
1944 if (cl->doHeapRegion(cur) && false) {
1945 cl->incomplete();
1946 return;
1947 }
1948 cur = next;
1949 }
1950 cur = g1_policy()->collection_set();
1951 while (cur != r) {
1952 HeapRegion* next = cur->next_in_collection_set();
1953 if (cl->doHeapRegion(cur) && false) {
1954 cl->incomplete();
1955 return;
1956 }
1957 cur = next;
1958 }
1959 }
1960
1961 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
1962 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
1963 }
1964
1965
1966 Space* G1CollectedHeap::space_containing(const void* addr) const {
1967 Space* res = heap_region_containing(addr);
1968 if (res == NULL)
1969 res = perm_gen()->space_containing(addr);
1970 return res;
1971 }
1972
1973 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
1974 Space* sp = space_containing(addr);
1975 if (sp != NULL) {
1976 return sp->block_start(addr);
1977 }
1978 return NULL;
1979 }
1980
1981 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
1982 Space* sp = space_containing(addr);
1983 assert(sp != NULL, "block_size of address outside of heap");
1984 return sp->block_size(addr);
1985 }
1986
1987 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
1988 Space* sp = space_containing(addr);
1989 return sp->block_is_obj(addr);
1990 }
1991
1992 bool G1CollectedHeap::supports_tlab_allocation() const {
1993 return true;
1994 }
1995
1996 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
1997 return HeapRegion::GrainBytes;
1998 }
1999
2000 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2001 // Return the remaining space in the cur alloc region, but not less than
2002 // the min TLAB size.
2003 // Also, no more than half the region size, since we can't allow tlabs to
2004 // grow big enough to accomodate humongous objects.
2005
2006 // We need to story it locally, since it might change between when we
2007 // test for NULL and when we use it later.
2008 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
2009 if (cur_alloc_space == NULL) {
2010 return HeapRegion::GrainBytes/2;
2011 } else {
2012 return MAX2(MIN2(cur_alloc_space->free(),
2013 (size_t)(HeapRegion::GrainBytes/2)),
2014 (size_t)MinTLABSize);
2015 }
2016 }
2017
2018 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
2019 bool dummy;
2020 return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
2021 }
2022
2023 bool G1CollectedHeap::allocs_are_zero_filled() {
2024 return false;
2025 }
2026
2027 size_t G1CollectedHeap::large_typearray_limit() {
2028 // FIXME
2029 return HeapRegion::GrainBytes/HeapWordSize;
2030 }
2031
2032 size_t G1CollectedHeap::max_capacity() const {
2033 return _g1_committed.byte_size();
2034 }
2035
2036 jlong G1CollectedHeap::millis_since_last_gc() {
2037 // assert(false, "NYI");
2038 return 0;
2039 }
2040
2041
2042 void G1CollectedHeap::prepare_for_verify() {
2043 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2044 ensure_parsability(false);
2045 }
2046 g1_rem_set()->prepare_for_verify();
2047 }
2048
2049 class VerifyLivenessOopClosure: public OopClosure {
2050 G1CollectedHeap* g1h;
2051 public:
2052 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2053 g1h = _g1h;
2054 }
2055 void do_oop(narrowOop *p) {
2056 guarantee(false, "NYI");
2057 }
2058 void do_oop(oop *p) {
2059 oop obj = *p;
2060 assert(obj == NULL || !g1h->is_obj_dead(obj),
2061 "Dead object referenced by a not dead object");
2062 }
2063 };
2064
2065 class VerifyObjsInRegionClosure: public ObjectClosure {
2066 G1CollectedHeap* _g1h;
2067 size_t _live_bytes;
2068 HeapRegion *_hr;
2069 public:
2070 VerifyObjsInRegionClosure(HeapRegion *hr) : _live_bytes(0), _hr(hr) {
2071 _g1h = G1CollectedHeap::heap();
2072 }
2073 void do_object(oop o) {
2074 VerifyLivenessOopClosure isLive(_g1h);
2075 assert(o != NULL, "Huh?");
2076 if (!_g1h->is_obj_dead(o)) {
2077 o->oop_iterate(&isLive);
2078 if (!_hr->obj_allocated_since_prev_marking(o))
2079 _live_bytes += (o->size() * HeapWordSize);
2080 }
2081 }
2082 size_t live_bytes() { return _live_bytes; }
2083 };
2084
2085 class PrintObjsInRegionClosure : public ObjectClosure {
2086 HeapRegion *_hr;
2087 G1CollectedHeap *_g1;
2088 public:
2089 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2090 _g1 = G1CollectedHeap::heap();
2091 };
2092
2093 void do_object(oop o) {
2094 if (o != NULL) {
2095 HeapWord *start = (HeapWord *) o;
2096 size_t word_sz = o->size();
2097 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2098 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2099 (void*) o, word_sz,
2100 _g1->isMarkedPrev(o),
2101 _g1->isMarkedNext(o),
2102 _hr->obj_allocated_since_prev_marking(o));
2103 HeapWord *end = start + word_sz;
2104 HeapWord *cur;
2105 int *val;
2106 for (cur = start; cur < end; cur++) {
2107 val = (int *) cur;
2108 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2109 }
2110 }
2111 }
2112 };
2113
2114 class VerifyRegionClosure: public HeapRegionClosure {
2115 public:
2116 bool _allow_dirty;
2117 bool _par;
2118 VerifyRegionClosure(bool allow_dirty, bool par = false)
2119 : _allow_dirty(allow_dirty), _par(par) {}
2120 bool doHeapRegion(HeapRegion* r) {
2121 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2122 "Should be unclaimed at verify points.");
2123 if (!r->isHumongous() || (r->isHumongous() && r->startsHumongous())) {
2124 VerifyObjsInRegionClosure not_dead_yet_cl(r);
2125 r->verify(_allow_dirty);
2126 r->object_iterate(¬_dead_yet_cl);
2127 guarantee(r->max_live_bytes() >= not_dead_yet_cl.live_bytes(),
2128 "More live objects than counted in last complete marking.");
2129 }
2130 return false;
2131 }
2132 };
2133
2134 class VerifyRootsClosure: public OopsInGenClosure {
2135 private:
2136 G1CollectedHeap* _g1h;
2137 bool _failures;
2138
2139 public:
2140 VerifyRootsClosure() :
2141 _g1h(G1CollectedHeap::heap()), _failures(false) { }
2142
2143 bool failures() { return _failures; }
2144
2145 void do_oop(narrowOop* p) {
2146 guarantee(false, "NYI");
2147 }
2148
2149 void do_oop(oop* p) {
2150 oop obj = *p;
2151 if (obj != NULL) {
2152 if (_g1h->is_obj_dead(obj)) {
2153 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2154 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2155 obj->print_on(gclog_or_tty);
2156 _failures = true;
2157 }
2158 }
2159 }
2160 };
2161
2162 // This is the task used for parallel heap verification.
2163
2164 class G1ParVerifyTask: public AbstractGangTask {
2165 private:
2166 G1CollectedHeap* _g1h;
2167 bool _allow_dirty;
2168
2169 public:
2170 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty) :
2171 AbstractGangTask("Parallel verify task"),
2172 _g1h(g1h), _allow_dirty(allow_dirty) { }
2173
2174 void work(int worker_i) {
2175 HandleMark hm;
2176 VerifyRegionClosure blk(_allow_dirty, true);
2177 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2178 HeapRegion::ParVerifyClaimValue);
2179 }
2180 };
2181
2182 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2183 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2184 if (!silent) { gclog_or_tty->print("roots "); }
2185 VerifyRootsClosure rootsCl;
2186 process_strong_roots(false,
2187 SharedHeap::SO_AllClasses,
2188 &rootsCl,
2189 &rootsCl);
2190 rem_set()->invalidate(perm_gen()->used_region(), false);
2191 if (!silent) { gclog_or_tty->print("heapRegions "); }
2192 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2193 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2194 "sanity check");
2195
2196 G1ParVerifyTask task(this, allow_dirty);
2197 int n_workers = workers()->total_workers();
2198 set_par_threads(n_workers);
2199 workers()->run_task(&task);
2200 set_par_threads(0);
2201
2202 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2203 "sanity check");
2204
2205 reset_heap_region_claim_values();
2206
2207 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2208 "sanity check");
2209 } else {
2210 VerifyRegionClosure blk(allow_dirty);
2211 _hrs->iterate(&blk);
2212 }
2213 if (!silent) gclog_or_tty->print("remset ");
2214 rem_set()->verify();
2215 guarantee(!rootsCl.failures(), "should not have had failures");
2216 } else {
2217 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2218 }
2219 }
2220
2221 class PrintRegionClosure: public HeapRegionClosure {
2222 outputStream* _st;
2223 public:
2224 PrintRegionClosure(outputStream* st) : _st(st) {}
2225 bool doHeapRegion(HeapRegion* r) {
2226 r->print_on(_st);
2227 return false;
2228 }
2229 };
2230
2231 void G1CollectedHeap::print() const { print_on(gclog_or_tty); }
2232
2233 void G1CollectedHeap::print_on(outputStream* st) const {
2234 PrintRegionClosure blk(st);
2235 _hrs->iterate(&blk);
2236 }
2237
2238 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2239 if (ParallelGCThreads > 0) {
2240 workers()->print_worker_threads();
2241 }
2242 st->print("\"G1 concurrent mark GC Thread\" ");
2243 _cmThread->print();
2244 st->cr();
2245 st->print("\"G1 concurrent refinement GC Thread\" ");
2246 _cg1r->cg1rThread()->print_on(st);
2247 st->cr();
2248 st->print("\"G1 zero-fill GC Thread\" ");
2249 _czft->print_on(st);
2250 st->cr();
2251 }
2252
2253 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2254 if (ParallelGCThreads > 0) {
2255 workers()->threads_do(tc);
2256 }
2257 tc->do_thread(_cmThread);
2258 tc->do_thread(_cg1r->cg1rThread());
2259 tc->do_thread(_czft);
2260 }
2261
2262 void G1CollectedHeap::print_tracing_info() const {
2263 concurrent_g1_refine()->print_final_card_counts();
2264
2265 // We'll overload this to mean "trace GC pause statistics."
2266 if (TraceGen0Time || TraceGen1Time) {
2267 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2268 // to that.
2269 g1_policy()->print_tracing_info();
2270 }
2271 if (SummarizeG1RSStats) {
2272 g1_rem_set()->print_summary_info();
2273 }
2274 if (SummarizeG1ConcMark) {
2275 concurrent_mark()->print_summary_info();
2276 }
2277 if (SummarizeG1ZFStats) {
2278 ConcurrentZFThread::print_summary_info();
2279 }
2280 if (G1SummarizePopularity) {
2281 print_popularity_summary_info();
2282 }
2283 g1_policy()->print_yg_surv_rate_info();
2284
2285 GCOverheadReporter::printGCOverhead();
2286
2287 SpecializationStats::print();
2288 }
2289
2290
2291 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2292 HeapRegion* hr = heap_region_containing(addr);
2293 if (hr == NULL) {
2294 return 0;
2295 } else {
2296 return 1;
2297 }
2298 }
2299
2300 G1CollectedHeap* G1CollectedHeap::heap() {
2301 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2302 "not a garbage-first heap");
2303 return _g1h;
2304 }
2305
2306 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2307 if (PrintHeapAtGC){
2308 gclog_or_tty->print_cr(" {Heap before GC collections=%d:", total_collections());
2309 Universe::print();
2310 }
2311 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2312 // Call allocation profiler
2313 AllocationProfiler::iterate_since_last_gc();
2314 // Fill TLAB's and such
2315 ensure_parsability(true);
2316 }
2317
2318 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2319 // FIXME: what is this about?
2320 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2321 // is set.
2322 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2323 "derived pointer present"));
2324
2325 if (PrintHeapAtGC){
2326 gclog_or_tty->print_cr(" Heap after GC collections=%d:", total_collections());
2327 Universe::print();
2328 gclog_or_tty->print("} ");
2329 }
2330 }
2331
2332 void G1CollectedHeap::do_collection_pause() {
2333 // Read the GC count while holding the Heap_lock
2334 // we need to do this _before_ wait_for_cleanup_complete(), to
2335 // ensure that we do not give up the heap lock and potentially
2336 // pick up the wrong count
2337 int gc_count_before = SharedHeap::heap()->total_collections();
2338
2339 // Don't want to do a GC pause while cleanup is being completed!
2340 wait_for_cleanup_complete();
2341
2342 g1_policy()->record_stop_world_start();
2343 {
2344 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2345 VM_G1IncCollectionPause op(gc_count_before);
2346 VMThread::execute(&op);
2347 }
2348 }
2349
2350 void
2351 G1CollectedHeap::doConcurrentMark() {
2352 if (G1ConcMark) {
2353 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2354 if (!_cmThread->in_progress()) {
2355 _cmThread->set_started();
2356 CGC_lock->notify();
2357 }
2358 }
2359 }
2360
2361 class VerifyMarkedObjsClosure: public ObjectClosure {
2362 G1CollectedHeap* _g1h;
2363 public:
2364 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2365 void do_object(oop obj) {
2366 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2367 "markandsweep mark should agree with concurrent deadness");
2368 }
2369 };
2370
2371 void
2372 G1CollectedHeap::checkConcurrentMark() {
2373 VerifyMarkedObjsClosure verifycl(this);
2374 // MutexLockerEx x(getMarkBitMapLock(),
2375 // Mutex::_no_safepoint_check_flag);
2376 object_iterate(&verifycl);
2377 }
2378
2379 void G1CollectedHeap::do_sync_mark() {
2380 _cm->checkpointRootsInitial();
2381 _cm->markFromRoots();
2382 _cm->checkpointRootsFinal(false);
2383 }
2384
2385 // <NEW PREDICTION>
2386
2387 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2388 bool young) {
2389 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2390 }
2391
2392 void G1CollectedHeap::check_if_region_is_too_expensive(double
2393 predicted_time_ms) {
2394 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2395 }
2396
2397 size_t G1CollectedHeap::pending_card_num() {
2398 size_t extra_cards = 0;
2399 JavaThread *curr = Threads::first();
2400 while (curr != NULL) {
2401 DirtyCardQueue& dcq = curr->dirty_card_queue();
2402 extra_cards += dcq.size();
2403 curr = curr->next();
2404 }
2405 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2406 size_t buffer_size = dcqs.buffer_size();
2407 size_t buffer_num = dcqs.completed_buffers_num();
2408 return buffer_size * buffer_num + extra_cards;
2409 }
2410
2411 size_t G1CollectedHeap::max_pending_card_num() {
2412 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2413 size_t buffer_size = dcqs.buffer_size();
2414 size_t buffer_num = dcqs.completed_buffers_num();
2415 int thread_num = Threads::number_of_threads();
2416 return (buffer_num + thread_num) * buffer_size;
2417 }
2418
2419 size_t G1CollectedHeap::cards_scanned() {
2420 HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
2421 return g1_rset->cardsScanned();
2422 }
2423
2424 void
2425 G1CollectedHeap::setup_surviving_young_words() {
2426 guarantee( _surviving_young_words == NULL, "pre-condition" );
2427 size_t array_length = g1_policy()->young_cset_length();
2428 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2429 if (_surviving_young_words == NULL) {
2430 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2431 "Not enough space for young surv words summary.");
2432 }
2433 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2434 for (size_t i = 0; i < array_length; ++i) {
2435 guarantee( _surviving_young_words[i] == 0, "invariant" );
2436 }
2437 }
2438
2439 void
2440 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2441 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2442 size_t array_length = g1_policy()->young_cset_length();
2443 for (size_t i = 0; i < array_length; ++i)
2444 _surviving_young_words[i] += surv_young_words[i];
2445 }
2446
2447 void
2448 G1CollectedHeap::cleanup_surviving_young_words() {
2449 guarantee( _surviving_young_words != NULL, "pre-condition" );
2450 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2451 _surviving_young_words = NULL;
2452 }
2453
2454 // </NEW PREDICTION>
2455
2456 void
2457 G1CollectedHeap::do_collection_pause_at_safepoint(HeapRegion* popular_region) {
2458 char verbose_str[128];
2459 sprintf(verbose_str, "GC pause ");
2460 if (popular_region != NULL)
2461 strcat(verbose_str, "(popular)");
2462 else if (g1_policy()->in_young_gc_mode()) {
2463 if (g1_policy()->full_young_gcs())
2464 strcat(verbose_str, "(young)");
2465 else
2466 strcat(verbose_str, "(partial)");
2467 }
2468 bool reset_should_initiate_conc_mark = false;
2469 if (popular_region != NULL && g1_policy()->should_initiate_conc_mark()) {
2470 // we currently do not allow an initial mark phase to be piggy-backed
2471 // on a popular pause
2472 reset_should_initiate_conc_mark = true;
2473 g1_policy()->unset_should_initiate_conc_mark();
2474 }
2475 if (g1_policy()->should_initiate_conc_mark())
2476 strcat(verbose_str, " (initial-mark)");
2477
2478 GCCauseSetter x(this, (popular_region == NULL ?
2479 GCCause::_g1_inc_collection_pause :
2480 GCCause::_g1_pop_region_collection_pause));
2481
2482 // if PrintGCDetails is on, we'll print long statistics information
2483 // in the collector policy code, so let's not print this as the output
2484 // is messy if we do.
2485 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2486 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2487 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2488
2489 ResourceMark rm;
2490 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2491 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2492 guarantee(!is_gc_active(), "collection is not reentrant");
2493 assert(regions_accounted_for(), "Region leakage!");
2494
2495 increment_gc_time_stamp();
2496
2497 if (g1_policy()->in_young_gc_mode()) {
2498 assert(check_young_list_well_formed(),
2499 "young list should be well formed");
2500 }
2501
2502 if (GC_locker::is_active()) {
2503 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2504 }
2505
2506 bool abandoned = false;
2507 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2508 IsGCActiveMark x;
2509
2510 gc_prologue(false);
2511 increment_total_collections();
2512
2513 #if G1_REM_SET_LOGGING
2514 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2515 print();
2516 #endif
2517
2518 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2519 HandleMark hm; // Discard invalid handles created during verification
2520 prepare_for_verify();
2521 gclog_or_tty->print(" VerifyBeforeGC:");
2522 Universe::verify(false);
2523 }
2524
2525 COMPILER2_PRESENT(DerivedPointerTable::clear());
2526
2527 // We want to turn off ref discovery, if necessary, and turn it back on
2528 // on again later if we do.
2529 bool was_enabled = ref_processor()->discovery_enabled();
2530 if (was_enabled) ref_processor()->disable_discovery();
2531
2532 // Forget the current alloc region (we might even choose it to be part
2533 // of the collection set!).
2534 abandon_cur_alloc_region();
2535
2536 // The elapsed time induced by the start time below deliberately elides
2537 // the possible verification above.
2538 double start_time_sec = os::elapsedTime();
2539 GCOverheadReporter::recordSTWStart(start_time_sec);
2540 size_t start_used_bytes = used();
2541 if (!G1ConcMark) {
2542 do_sync_mark();
2543 }
2544
2545 g1_policy()->record_collection_pause_start(start_time_sec,
2546 start_used_bytes);
2547
2548 guarantee(_in_cset_fast_test == NULL, "invariant");
2549 guarantee(_in_cset_fast_test_base == NULL, "invariant");
2550 _in_cset_fast_test_length = max_regions();
2551 _in_cset_fast_test_base =
2552 NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2553 memset(_in_cset_fast_test_base, false,
2554 _in_cset_fast_test_length * sizeof(bool));
2555 // We're biasing _in_cset_fast_test to avoid subtracting the
2556 // beginning of the heap every time we want to index; basically
2557 // it's the same with what we do with the card table.
2558 _in_cset_fast_test = _in_cset_fast_test_base -
2559 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2560
2561 #if SCAN_ONLY_VERBOSE
2562 _young_list->print();
2563 #endif // SCAN_ONLY_VERBOSE
2564
2565 if (g1_policy()->should_initiate_conc_mark()) {
2566 concurrent_mark()->checkpointRootsInitialPre();
2567 }
2568 save_marks();
2569
2570 // We must do this before any possible evacuation that should propagate
2571 // marks, including evacuation of popular objects in a popular pause.
2572 if (mark_in_progress()) {
2573 double start_time_sec = os::elapsedTime();
2574
2575 _cm->drainAllSATBBuffers();
2576 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2577 g1_policy()->record_satb_drain_time(finish_mark_ms);
2578
2579 }
2580 // Record the number of elements currently on the mark stack, so we
2581 // only iterate over these. (Since evacuation may add to the mark
2582 // stack, doing more exposes race conditions.) If no mark is in
2583 // progress, this will be zero.
2584 _cm->set_oops_do_bound();
2585
2586 assert(regions_accounted_for(), "Region leakage.");
2587
2588 bool abandoned = false;
2589
2590 if (mark_in_progress())
2591 concurrent_mark()->newCSet();
2592
2593 // Now choose the CS.
2594 if (popular_region == NULL) {
2595 g1_policy()->choose_collection_set();
2596 } else {
2597 // We may be evacuating a single region (for popularity).
2598 g1_policy()->record_popular_pause_preamble_start();
2599 popularity_pause_preamble(popular_region);
2600 g1_policy()->record_popular_pause_preamble_end();
2601 abandoned = (g1_policy()->collection_set() == NULL);
2602 // Now we allow more regions to be added (we have to collect
2603 // all popular regions).
2604 if (!abandoned) {
2605 g1_policy()->choose_collection_set(popular_region);
2606 }
2607 }
2608 // We may abandon a pause if we find no region that will fit in the MMU
2609 // pause.
2610 abandoned = (g1_policy()->collection_set() == NULL);
2611
2612 // Nothing to do if we were unable to choose a collection set.
2613 if (!abandoned) {
2614 #if G1_REM_SET_LOGGING
2615 gclog_or_tty->print_cr("\nAfter pause, heap:");
2616 print();
2617 #endif
2618
2619 setup_surviving_young_words();
2620
2621 // Set up the gc allocation regions.
2622 get_gc_alloc_regions();
2623
2624 // Actually do the work...
2625 evacuate_collection_set();
2626 free_collection_set(g1_policy()->collection_set());
2627 g1_policy()->clear_collection_set();
2628
2629 FREE_C_HEAP_ARRAY(bool, _in_cset_fast_test_base);
2630 // this is more for peace of mind; we're nulling them here and
2631 // we're expecting them to be null at the beginning of the next GC
2632 _in_cset_fast_test = NULL;
2633 _in_cset_fast_test_base = NULL;
2634
2635 if (popular_region != NULL) {
2636 // We have to wait until now, because we don't want the region to
2637 // be rescheduled for pop-evac during RS update.
2638 popular_region->set_popular_pending(false);
2639 }
2640
2641 release_gc_alloc_regions();
2642
2643 cleanup_surviving_young_words();
2644
2645 if (g1_policy()->in_young_gc_mode()) {
2646 _young_list->reset_sampled_info();
2647 assert(check_young_list_empty(true),
2648 "young list should be empty");
2649
2650 #if SCAN_ONLY_VERBOSE
2651 _young_list->print();
2652 #endif // SCAN_ONLY_VERBOSE
2653
2654 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
2655 _young_list->first_survivor_region(),
2656 _young_list->last_survivor_region());
2657 _young_list->reset_auxilary_lists();
2658 }
2659 } else {
2660 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
2661 }
2662
2663 if (evacuation_failed()) {
2664 _summary_bytes_used = recalculate_used();
2665 } else {
2666 // The "used" of the the collection set have already been subtracted
2667 // when they were freed. Add in the bytes evacuated.
2668 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2669 }
2670
2671 if (g1_policy()->in_young_gc_mode() &&
2672 g1_policy()->should_initiate_conc_mark()) {
2673 concurrent_mark()->checkpointRootsInitialPost();
2674 set_marking_started();
2675 doConcurrentMark();
2676 }
2677
2678 #if SCAN_ONLY_VERBOSE
2679 _young_list->print();
2680 #endif // SCAN_ONLY_VERBOSE
2681
2682 double end_time_sec = os::elapsedTime();
2683 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
2684 g1_policy()->record_pause_time_ms(pause_time_ms);
2685 GCOverheadReporter::recordSTWEnd(end_time_sec);
2686 g1_policy()->record_collection_pause_end(popular_region != NULL,
2687 abandoned);
2688
2689 assert(regions_accounted_for(), "Region leakage.");
2690
2691 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
2692 HandleMark hm; // Discard invalid handles created during verification
2693 gclog_or_tty->print(" VerifyAfterGC:");
2694 prepare_for_verify();
2695 Universe::verify(false);
2696 }
2697
2698 if (was_enabled) ref_processor()->enable_discovery();
2699
2700 {
2701 size_t expand_bytes = g1_policy()->expansion_amount();
2702 if (expand_bytes > 0) {
2703 size_t bytes_before = capacity();
2704 expand(expand_bytes);
2705 }
2706 }
2707
2708 if (mark_in_progress()) {
2709 concurrent_mark()->update_g1_committed();
2710 }
2711
2712 #ifdef TRACESPINNING
2713 ParallelTaskTerminator::print_termination_counts();
2714 #endif
2715
2716 gc_epilogue(false);
2717 }
2718
2719 assert(verify_region_lists(), "Bad region lists.");
2720
2721 if (reset_should_initiate_conc_mark)
2722 g1_policy()->set_should_initiate_conc_mark();
2723
2724 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
2725 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
2726 print_tracing_info();
2727 vm_exit(-1);
2728 }
2729 }
2730
2731 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
2732 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
2733 HeapWord* original_top = NULL;
2734 if (r != NULL)
2735 original_top = r->top();
2736
2737 // We will want to record the used space in r as being there before gc.
2738 // One we install it as a GC alloc region it's eligible for allocation.
2739 // So record it now and use it later.
2740 size_t r_used = 0;
2741 if (r != NULL) {
2742 r_used = r->used();
2743
2744 if (ParallelGCThreads > 0) {
2745 // need to take the lock to guard against two threads calling
2746 // get_gc_alloc_region concurrently (very unlikely but...)
2747 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2748 r->save_marks();
2749 }
2750 }
2751 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
2752 _gc_alloc_regions[purpose] = r;
2753 if (old_alloc_region != NULL) {
2754 // Replace aliases too.
2755 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2756 if (_gc_alloc_regions[ap] == old_alloc_region) {
2757 _gc_alloc_regions[ap] = r;
2758 }
2759 }
2760 }
2761 if (r != NULL) {
2762 push_gc_alloc_region(r);
2763 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
2764 // We are using a region as a GC alloc region after it has been used
2765 // as a mutator allocation region during the current marking cycle.
2766 // The mutator-allocated objects are currently implicitly marked, but
2767 // when we move hr->next_top_at_mark_start() forward at the the end
2768 // of the GC pause, they won't be. We therefore mark all objects in
2769 // the "gap". We do this object-by-object, since marking densely
2770 // does not currently work right with marking bitmap iteration. This
2771 // means we rely on TLAB filling at the start of pauses, and no
2772 // "resuscitation" of filled TLAB's. If we want to do this, we need
2773 // to fix the marking bitmap iteration.
2774 HeapWord* curhw = r->next_top_at_mark_start();
2775 HeapWord* t = original_top;
2776
2777 while (curhw < t) {
2778 oop cur = (oop)curhw;
2779 // We'll assume parallel for generality. This is rare code.
2780 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
2781 curhw = curhw + cur->size();
2782 }
2783 assert(curhw == t, "Should have parsed correctly.");
2784 }
2785 if (G1PolicyVerbose > 1) {
2786 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
2787 "for survivors:", r->bottom(), original_top, r->end());
2788 r->print();
2789 }
2790 g1_policy()->record_before_bytes(r_used);
2791 }
2792 }
2793
2794 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
2795 assert(Thread::current()->is_VM_thread() ||
2796 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
2797 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
2798 "Precondition.");
2799 hr->set_is_gc_alloc_region(true);
2800 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
2801 _gc_alloc_region_list = hr;
2802 }
2803
2804 #ifdef G1_DEBUG
2805 class FindGCAllocRegion: public HeapRegionClosure {
2806 public:
2807 bool doHeapRegion(HeapRegion* r) {
2808 if (r->is_gc_alloc_region()) {
2809 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
2810 r->hrs_index(), r->bottom());
2811 }
2812 return false;
2813 }
2814 };
2815 #endif // G1_DEBUG
2816
2817 void G1CollectedHeap::forget_alloc_region_list() {
2818 assert(Thread::current()->is_VM_thread(), "Precondition");
2819 while (_gc_alloc_region_list != NULL) {
2820 HeapRegion* r = _gc_alloc_region_list;
2821 assert(r->is_gc_alloc_region(), "Invariant.");
2822 _gc_alloc_region_list = r->next_gc_alloc_region();
2823 r->set_next_gc_alloc_region(NULL);
2824 r->set_is_gc_alloc_region(false);
2825 if (r->is_survivor()) {
2826 if (r->is_empty()) {
2827 r->set_not_young();
2828 } else {
2829 _young_list->add_survivor_region(r);
2830 }
2831 }
2832 if (r->is_empty()) {
2833 ++_free_regions;
2834 }
2835 }
2836 #ifdef G1_DEBUG
2837 FindGCAllocRegion fa;
2838 heap_region_iterate(&fa);
2839 #endif // G1_DEBUG
2840 }
2841
2842
2843 bool G1CollectedHeap::check_gc_alloc_regions() {
2844 // TODO: allocation regions check
2845 return true;
2846 }
2847
2848 void G1CollectedHeap::get_gc_alloc_regions() {
2849 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2850 // Create new GC alloc regions.
2851 HeapRegion* alloc_region = _gc_alloc_regions[ap];
2852 // Clear this alloc region, so that in case it turns out to be
2853 // unacceptable, we end up with no allocation region, rather than a bad
2854 // one.
2855 _gc_alloc_regions[ap] = NULL;
2856 if (alloc_region == NULL || alloc_region->in_collection_set()) {
2857 // Can't re-use old one. Allocate a new one.
2858 alloc_region = newAllocRegionWithExpansion(ap, 0);
2859 }
2860 if (alloc_region != NULL) {
2861 set_gc_alloc_region(ap, alloc_region);
2862 }
2863 }
2864 // Set alternative regions for allocation purposes that have reached
2865 // thier limit.
2866 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2867 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
2868 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
2869 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
2870 }
2871 }
2872 assert(check_gc_alloc_regions(), "alloc regions messed up");
2873 }
2874
2875 void G1CollectedHeap::release_gc_alloc_regions() {
2876 // We keep a separate list of all regions that have been alloc regions in
2877 // the current collection pause. Forget that now.
2878 forget_alloc_region_list();
2879
2880 // The current alloc regions contain objs that have survived
2881 // collection. Make them no longer GC alloc regions.
2882 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2883 HeapRegion* r = _gc_alloc_regions[ap];
2884 if (r != NULL && r->is_empty()) {
2885 {
2886 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
2887 r->set_zero_fill_complete();
2888 put_free_region_on_list_locked(r);
2889 }
2890 }
2891 // set_gc_alloc_region will also NULLify all aliases to the region
2892 set_gc_alloc_region(ap, NULL);
2893 _gc_alloc_region_counts[ap] = 0;
2894 }
2895 }
2896
2897 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
2898 _drain_in_progress = false;
2899 set_evac_failure_closure(cl);
2900 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
2901 }
2902
2903 void G1CollectedHeap::finalize_for_evac_failure() {
2904 assert(_evac_failure_scan_stack != NULL &&
2905 _evac_failure_scan_stack->length() == 0,
2906 "Postcondition");
2907 assert(!_drain_in_progress, "Postcondition");
2908 // Don't have to delete, since the scan stack is a resource object.
2909 _evac_failure_scan_stack = NULL;
2910 }
2911
2912
2913
2914 // *** Sequential G1 Evacuation
2915
2916 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
2917 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
2918 // let the caller handle alloc failure
2919 if (alloc_region == NULL) return NULL;
2920 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
2921 "Either the object is humongous or the region isn't");
2922 HeapWord* block = alloc_region->allocate(word_size);
2923 if (block == NULL) {
2924 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
2925 }
2926 return block;
2927 }
2928
2929 class G1IsAliveClosure: public BoolObjectClosure {
2930 G1CollectedHeap* _g1;
2931 public:
2932 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
2933 void do_object(oop p) { assert(false, "Do not call."); }
2934 bool do_object_b(oop p) {
2935 // It is reachable if it is outside the collection set, or is inside
2936 // and forwarded.
2937
2938 #ifdef G1_DEBUG
2939 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
2940 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
2941 !_g1->obj_in_cs(p) || p->is_forwarded());
2942 #endif // G1_DEBUG
2943
2944 return !_g1->obj_in_cs(p) || p->is_forwarded();
2945 }
2946 };
2947
2948 class G1KeepAliveClosure: public OopClosure {
2949 G1CollectedHeap* _g1;
2950 public:
2951 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
2952 void do_oop(narrowOop* p) {
2953 guarantee(false, "NYI");
2954 }
2955 void do_oop(oop* p) {
2956 oop obj = *p;
2957 #ifdef G1_DEBUG
2958 if (PrintGC && Verbose) {
2959 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
2960 p, (void*) obj, (void*) *p);
2961 }
2962 #endif // G1_DEBUG
2963
2964 if (_g1->obj_in_cs(obj)) {
2965 assert( obj->is_forwarded(), "invariant" );
2966 *p = obj->forwardee();
2967
2968 #ifdef G1_DEBUG
2969 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
2970 (void*) obj, (void*) *p);
2971 #endif // G1_DEBUG
2972 }
2973 }
2974 };
2975
2976 class UpdateRSetImmediate : public OopsInHeapRegionClosure {
2977 private:
2978 G1CollectedHeap* _g1;
2979 G1RemSet* _g1_rem_set;
2980 public:
2981 UpdateRSetImmediate(G1CollectedHeap* g1) :
2982 _g1(g1), _g1_rem_set(g1->g1_rem_set()) {}
2983
2984 void do_oop(narrowOop* p) {
2985 guarantee(false, "NYI");
2986 }
2987 void do_oop(oop* p) {
2988 assert(_from->is_in_reserved(p), "paranoia");
2989 if (*p != NULL && !_from->is_survivor()) {
2990 _g1_rem_set->par_write_ref(_from, p, 0);
2991 }
2992 }
2993 };
2994
2995 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
2996 private:
2997 G1CollectedHeap* _g1;
2998 DirtyCardQueue *_dcq;
2999 CardTableModRefBS* _ct_bs;
3000
3001 public:
3002 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3003 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3004
3005 void do_oop(narrowOop* p) {
3006 guarantee(false, "NYI");
3007 }
3008 void do_oop(oop* p) {
3009 assert(_from->is_in_reserved(p), "paranoia");
3010 if (!_from->is_in_reserved(*p) && !_from->is_survivor()) {
3011 size_t card_index = _ct_bs->index_for(p);
3012 if (_ct_bs->mark_card_deferred(card_index)) {
3013 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3014 }
3015 }
3016 }
3017 };
3018
3019
3020
3021 class RemoveSelfPointerClosure: public ObjectClosure {
3022 private:
3023 G1CollectedHeap* _g1;
3024 ConcurrentMark* _cm;
3025 HeapRegion* _hr;
3026 size_t _prev_marked_bytes;
3027 size_t _next_marked_bytes;
3028 OopsInHeapRegionClosure *_cl;
3029 public:
3030 RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
3031 _g1(g1), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3032 _next_marked_bytes(0), _cl(cl) {}
3033
3034 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3035 size_t next_marked_bytes() { return _next_marked_bytes; }
3036
3037 // The original idea here was to coalesce evacuated and dead objects.
3038 // However that caused complications with the block offset table (BOT).
3039 // In particular if there were two TLABs, one of them partially refined.
3040 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3041 // The BOT entries of the unrefined part of TLAB_2 point to the start
3042 // of TLAB_2. If the last object of the TLAB_1 and the first object
3043 // of TLAB_2 are coalesced, then the cards of the unrefined part
3044 // would point into middle of the filler object.
3045 //
3046 // The current approach is to not coalesce and leave the BOT contents intact.
3047 void do_object(oop obj) {
3048 if (obj->is_forwarded() && obj->forwardee() == obj) {
3049 // The object failed to move.
3050 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3051 _cm->markPrev(obj);
3052 assert(_cm->isPrevMarked(obj), "Should be marked!");
3053 _prev_marked_bytes += (obj->size() * HeapWordSize);
3054 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3055 _cm->markAndGrayObjectIfNecessary(obj);
3056 }
3057 obj->set_mark(markOopDesc::prototype());
3058 // While we were processing RSet buffers during the
3059 // collection, we actually didn't scan any cards on the
3060 // collection set, since we didn't want to update remebered
3061 // sets with entries that point into the collection set, given
3062 // that live objects fromthe collection set are about to move
3063 // and such entries will be stale very soon. This change also
3064 // dealt with a reliability issue which involved scanning a
3065 // card in the collection set and coming across an array that
3066 // was being chunked and looking malformed. The problem is
3067 // that, if evacuation fails, we might have remembered set
3068 // entries missing given that we skipped cards on the
3069 // collection set. So, we'll recreate such entries now.
3070 obj->oop_iterate(_cl);
3071 assert(_cm->isPrevMarked(obj), "Should be marked!");
3072 } else {
3073 // The object has been either evacuated or is dead. Fill it with a
3074 // dummy object.
3075 MemRegion mr((HeapWord*)obj, obj->size());
3076 CollectedHeap::fill_with_object(mr);
3077 _cm->clearRangeBothMaps(mr);
3078 }
3079 }
3080 };
3081
3082 void G1CollectedHeap::remove_self_forwarding_pointers() {
3083 UpdateRSetImmediate immediate_update(_g1h);
3084 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3085 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3086 OopsInHeapRegionClosure *cl;
3087 if (G1DeferredRSUpdate) {
3088 cl = &deferred_update;
3089 } else {
3090 cl = &immediate_update;
3091 }
3092 HeapRegion* cur = g1_policy()->collection_set();
3093 while (cur != NULL) {
3094 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3095
3096 RemoveSelfPointerClosure rspc(_g1h, cl);
3097 if (cur->evacuation_failed()) {
3098 assert(cur->in_collection_set(), "bad CS");
3099 cl->set_region(cur);
3100 cur->object_iterate(&rspc);
3101
3102 // A number of manipulations to make the TAMS be the current top,
3103 // and the marked bytes be the ones observed in the iteration.
3104 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3105 // The comments below are the postconditions achieved by the
3106 // calls. Note especially the last such condition, which says that
3107 // the count of marked bytes has been properly restored.
3108 cur->note_start_of_marking(false);
3109 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3110 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3111 // _next_marked_bytes == prev_marked_bytes.
3112 cur->note_end_of_marking();
3113 // _prev_top_at_mark_start == top(),
3114 // _prev_marked_bytes == prev_marked_bytes
3115 }
3116 // If there is no mark in progress, we modified the _next variables
3117 // above needlessly, but harmlessly.
3118 if (_g1h->mark_in_progress()) {
3119 cur->note_start_of_marking(false);
3120 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3121 // _next_marked_bytes == next_marked_bytes.
3122 }
3123
3124 // Now make sure the region has the right index in the sorted array.
3125 g1_policy()->note_change_in_marked_bytes(cur);
3126 }
3127 cur = cur->next_in_collection_set();
3128 }
3129 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3130
3131 // Now restore saved marks, if any.
3132 if (_objs_with_preserved_marks != NULL) {
3133 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3134 assert(_objs_with_preserved_marks->length() ==
3135 _preserved_marks_of_objs->length(), "Both or none.");
3136 guarantee(_objs_with_preserved_marks->length() ==
3137 _preserved_marks_of_objs->length(), "Both or none.");
3138 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3139 oop obj = _objs_with_preserved_marks->at(i);
3140 markOop m = _preserved_marks_of_objs->at(i);
3141 obj->set_mark(m);
3142 }
3143 // Delete the preserved marks growable arrays (allocated on the C heap).
3144 delete _objs_with_preserved_marks;
3145 delete _preserved_marks_of_objs;
3146 _objs_with_preserved_marks = NULL;
3147 _preserved_marks_of_objs = NULL;
3148 }
3149 }
3150
3151 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3152 _evac_failure_scan_stack->push(obj);
3153 }
3154
3155 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3156 assert(_evac_failure_scan_stack != NULL, "precondition");
3157
3158 while (_evac_failure_scan_stack->length() > 0) {
3159 oop obj = _evac_failure_scan_stack->pop();
3160 _evac_failure_closure->set_region(heap_region_containing(obj));
3161 obj->oop_iterate_backwards(_evac_failure_closure);
3162 }
3163 }
3164
3165 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3166 markOop m = old->mark();
3167 // forward to self
3168 assert(!old->is_forwarded(), "precondition");
3169
3170 old->forward_to(old);
3171 handle_evacuation_failure_common(old, m);
3172 }
3173
3174 oop
3175 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3176 oop old) {
3177 markOop m = old->mark();
3178 oop forward_ptr = old->forward_to_atomic(old);
3179 if (forward_ptr == NULL) {
3180 // Forward-to-self succeeded.
3181 if (_evac_failure_closure != cl) {
3182 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3183 assert(!_drain_in_progress,
3184 "Should only be true while someone holds the lock.");
3185 // Set the global evac-failure closure to the current thread's.
3186 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3187 set_evac_failure_closure(cl);
3188 // Now do the common part.
3189 handle_evacuation_failure_common(old, m);
3190 // Reset to NULL.
3191 set_evac_failure_closure(NULL);
3192 } else {
3193 // The lock is already held, and this is recursive.
3194 assert(_drain_in_progress, "This should only be the recursive case.");
3195 handle_evacuation_failure_common(old, m);
3196 }
3197 return old;
3198 } else {
3199 // Someone else had a place to copy it.
3200 return forward_ptr;
3201 }
3202 }
3203
3204 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3205 set_evacuation_failed(true);
3206
3207 preserve_mark_if_necessary(old, m);
3208
3209 HeapRegion* r = heap_region_containing(old);
3210 if (!r->evacuation_failed()) {
3211 r->set_evacuation_failed(true);
3212 if (G1TraceRegions) {
3213 gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
3214 "["PTR_FORMAT","PTR_FORMAT")\n",
3215 r, r->bottom(), r->end());
3216 }
3217 }
3218
3219 push_on_evac_failure_scan_stack(old);
3220
3221 if (!_drain_in_progress) {
3222 // prevent recursion in copy_to_survivor_space()
3223 _drain_in_progress = true;
3224 drain_evac_failure_scan_stack();
3225 _drain_in_progress = false;
3226 }
3227 }
3228
3229 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3230 if (m != markOopDesc::prototype()) {
3231 if (_objs_with_preserved_marks == NULL) {
3232 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3233 _objs_with_preserved_marks =
3234 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3235 _preserved_marks_of_objs =
3236 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3237 }
3238 _objs_with_preserved_marks->push(obj);
3239 _preserved_marks_of_objs->push(m);
3240 }
3241 }
3242
3243 // *** Parallel G1 Evacuation
3244
3245 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3246 size_t word_size) {
3247 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3248 // let the caller handle alloc failure
3249 if (alloc_region == NULL) return NULL;
3250
3251 HeapWord* block = alloc_region->par_allocate(word_size);
3252 if (block == NULL) {
3253 MutexLockerEx x(par_alloc_during_gc_lock(),
3254 Mutex::_no_safepoint_check_flag);
3255 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3256 }
3257 return block;
3258 }
3259
3260 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
3261 bool par) {
3262 // Another thread might have obtained alloc_region for the given
3263 // purpose, and might be attempting to allocate in it, and might
3264 // succeed. Therefore, we can't do the "finalization" stuff on the
3265 // region below until we're sure the last allocation has happened.
3266 // We ensure this by allocating the remaining space with a garbage
3267 // object.
3268 if (par) par_allocate_remaining_space(alloc_region);
3269 // Now we can do the post-GC stuff on the region.
3270 alloc_region->note_end_of_copying();
3271 g1_policy()->record_after_bytes(alloc_region->used());
3272 }
3273
3274 HeapWord*
3275 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3276 HeapRegion* alloc_region,
3277 bool par,
3278 size_t word_size) {
3279 HeapWord* block = NULL;
3280 // In the parallel case, a previous thread to obtain the lock may have
3281 // already assigned a new gc_alloc_region.
3282 if (alloc_region != _gc_alloc_regions[purpose]) {
3283 assert(par, "But should only happen in parallel case.");
3284 alloc_region = _gc_alloc_regions[purpose];
3285 if (alloc_region == NULL) return NULL;
3286 block = alloc_region->par_allocate(word_size);
3287 if (block != NULL) return block;
3288 // Otherwise, continue; this new region is empty, too.
3289 }
3290 assert(alloc_region != NULL, "We better have an allocation region");
3291 retire_alloc_region(alloc_region, par);
3292
3293 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3294 // Cannot allocate more regions for the given purpose.
3295 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3296 // Is there an alternative?
3297 if (purpose != alt_purpose) {
3298 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3299 // Has not the alternative region been aliased?
3300 if (alloc_region != alt_region && alt_region != NULL) {
3301 // Try to allocate in the alternative region.
3302 if (par) {
3303 block = alt_region->par_allocate(word_size);
3304 } else {
3305 block = alt_region->allocate(word_size);
3306 }
3307 // Make an alias.
3308 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3309 if (block != NULL) {
3310 return block;
3311 }
3312 retire_alloc_region(alt_region, par);
3313 }
3314 // Both the allocation region and the alternative one are full
3315 // and aliased, replace them with a new allocation region.
3316 purpose = alt_purpose;
3317 } else {
3318 set_gc_alloc_region(purpose, NULL);
3319 return NULL;
3320 }
3321 }
3322
3323 // Now allocate a new region for allocation.
3324 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3325
3326 // let the caller handle alloc failure
3327 if (alloc_region != NULL) {
3328
3329 assert(check_gc_alloc_regions(), "alloc regions messed up");
3330 assert(alloc_region->saved_mark_at_top(),
3331 "Mark should have been saved already.");
3332 // We used to assert that the region was zero-filled here, but no
3333 // longer.
3334
3335 // This must be done last: once it's installed, other regions may
3336 // allocate in it (without holding the lock.)
3337 set_gc_alloc_region(purpose, alloc_region);
3338
3339 if (par) {
3340 block = alloc_region->par_allocate(word_size);
3341 } else {
3342 block = alloc_region->allocate(word_size);
3343 }
3344 // Caller handles alloc failure.
3345 } else {
3346 // This sets other apis using the same old alloc region to NULL, also.
3347 set_gc_alloc_region(purpose, NULL);
3348 }
3349 return block; // May be NULL.
3350 }
3351
3352 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3353 HeapWord* block = NULL;
3354 size_t free_words;
3355 do {
3356 free_words = r->free()/HeapWordSize;
3357 // If there's too little space, no one can allocate, so we're done.
3358 if (free_words < (size_t)oopDesc::header_size()) return;
3359 // Otherwise, try to claim it.
3360 block = r->par_allocate(free_words);
3361 } while (block == NULL);
3362 fill_with_object(block, free_words);
3363 }
3364
3365 #define use_local_bitmaps 1
3366 #define verify_local_bitmaps 0
3367
3368 #ifndef PRODUCT
3369
3370 class GCLabBitMap;
3371 class GCLabBitMapClosure: public BitMapClosure {
3372 private:
3373 ConcurrentMark* _cm;
3374 GCLabBitMap* _bitmap;
3375
3376 public:
3377 GCLabBitMapClosure(ConcurrentMark* cm,
3378 GCLabBitMap* bitmap) {
3379 _cm = cm;
3380 _bitmap = bitmap;
3381 }
3382
3383 virtual bool do_bit(size_t offset);
3384 };
3385
3386 #endif // PRODUCT
3387
3388 #define oop_buffer_length 256
3389
3390 class GCLabBitMap: public BitMap {
3391 private:
3392 ConcurrentMark* _cm;
3393
3394 int _shifter;
3395 size_t _bitmap_word_covers_words;
3396
3397 // beginning of the heap
3398 HeapWord* _heap_start;
3399
3400 // this is the actual start of the GCLab
3401 HeapWord* _real_start_word;
3402
3403 // this is the actual end of the GCLab
3404 HeapWord* _real_end_word;
3405
3406 // this is the first word, possibly located before the actual start
3407 // of the GCLab, that corresponds to the first bit of the bitmap
3408 HeapWord* _start_word;
3409
3410 // size of a GCLab in words
3411 size_t _gclab_word_size;
3412
3413 static int shifter() {
3414 return MinObjAlignment - 1;
3415 }
3416
3417 // how many heap words does a single bitmap word corresponds to?
3418 static size_t bitmap_word_covers_words() {
3419 return BitsPerWord << shifter();
3420 }
3421
3422 static size_t gclab_word_size() {
3423 return ParallelGCG1AllocBufferSize / HeapWordSize;
3424 }
3425
3426 static size_t bitmap_size_in_bits() {
3427 size_t bits_in_bitmap = gclab_word_size() >> shifter();
3428 // We are going to ensure that the beginning of a word in this
3429 // bitmap also corresponds to the beginning of a word in the
3430 // global marking bitmap. To handle the case where a GCLab
3431 // starts from the middle of the bitmap, we need to add enough
3432 // space (i.e. up to a bitmap word) to ensure that we have
3433 // enough bits in the bitmap.
3434 return bits_in_bitmap + BitsPerWord - 1;
3435 }
3436 public:
3437 GCLabBitMap(HeapWord* heap_start)
3438 : BitMap(bitmap_size_in_bits()),
3439 _cm(G1CollectedHeap::heap()->concurrent_mark()),
3440 _shifter(shifter()),
3441 _bitmap_word_covers_words(bitmap_word_covers_words()),
3442 _heap_start(heap_start),
3443 _gclab_word_size(gclab_word_size()),
3444 _real_start_word(NULL),
3445 _real_end_word(NULL),
3446 _start_word(NULL)
3447 {
3448 guarantee( size_in_words() >= bitmap_size_in_words(),
3449 "just making sure");
3450 }
3451
3452 inline unsigned heapWordToOffset(HeapWord* addr) {
3453 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
3454 assert(offset < size(), "offset should be within bounds");
3455 return offset;
3456 }
3457
3458 inline HeapWord* offsetToHeapWord(size_t offset) {
3459 HeapWord* addr = _start_word + (offset << _shifter);
3460 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
3461 return addr;
3462 }
3463
3464 bool fields_well_formed() {
3465 bool ret1 = (_real_start_word == NULL) &&
3466 (_real_end_word == NULL) &&
3467 (_start_word == NULL);
3468 if (ret1)
3469 return true;
3470
3471 bool ret2 = _real_start_word >= _start_word &&
3472 _start_word < _real_end_word &&
3473 (_real_start_word + _gclab_word_size) == _real_end_word &&
3474 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
3475 > _real_end_word;
3476 return ret2;
3477 }
3478
3479 inline bool mark(HeapWord* addr) {
3480 guarantee(use_local_bitmaps, "invariant");
3481 assert(fields_well_formed(), "invariant");
3482
3483 if (addr >= _real_start_word && addr < _real_end_word) {
3484 assert(!isMarked(addr), "should not have already been marked");
3485
3486 // first mark it on the bitmap
3487 at_put(heapWordToOffset(addr), true);
3488
3489 return true;
3490 } else {
3491 return false;
3492 }
3493 }
3494
3495 inline bool isMarked(HeapWord* addr) {
3496 guarantee(use_local_bitmaps, "invariant");
3497 assert(fields_well_formed(), "invariant");
3498
3499 return at(heapWordToOffset(addr));
3500 }
3501
3502 void set_buffer(HeapWord* start) {
3503 guarantee(use_local_bitmaps, "invariant");
3504 clear();
3505
3506 assert(start != NULL, "invariant");
3507 _real_start_word = start;
3508 _real_end_word = start + _gclab_word_size;
3509
3510 size_t diff =
3511 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
3512 _start_word = start - diff;
3513
3514 assert(fields_well_formed(), "invariant");
3515 }
3516
3517 #ifndef PRODUCT
3518 void verify() {
3519 // verify that the marks have been propagated
3520 GCLabBitMapClosure cl(_cm, this);
3521 iterate(&cl);
3522 }
3523 #endif // PRODUCT
3524
3525 void retire() {
3526 guarantee(use_local_bitmaps, "invariant");
3527 assert(fields_well_formed(), "invariant");
3528
3529 if (_start_word != NULL) {
3530 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
3531
3532 // this means that the bitmap was set up for the GCLab
3533 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
3534
3535 mark_bitmap->mostly_disjoint_range_union(this,
3536 0, // always start from the start of the bitmap
3537 _start_word,
3538 size_in_words());
3539 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
3540
3541 #ifndef PRODUCT
3542 if (use_local_bitmaps && verify_local_bitmaps)
3543 verify();
3544 #endif // PRODUCT
3545 } else {
3546 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
3547 }
3548 }
3549
3550 static size_t bitmap_size_in_words() {
3551 return (bitmap_size_in_bits() + BitsPerWord - 1) / BitsPerWord;
3552 }
3553 };
3554
3555 #ifndef PRODUCT
3556
3557 bool GCLabBitMapClosure::do_bit(size_t offset) {
3558 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3559 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3560 return true;
3561 }
3562
3563 #endif // PRODUCT
3564
3565 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
3566 private:
3567 bool _retired;
3568 bool _during_marking;
3569 GCLabBitMap _bitmap;
3570
3571 public:
3572 G1ParGCAllocBuffer() :
3573 ParGCAllocBuffer(ParallelGCG1AllocBufferSize / HeapWordSize),
3574 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
3575 _bitmap(G1CollectedHeap::heap()->reserved_region().start()),
3576 _retired(false)
3577 { }
3578
3579 inline bool mark(HeapWord* addr) {
3580 guarantee(use_local_bitmaps, "invariant");
3581 assert(_during_marking, "invariant");
3582 return _bitmap.mark(addr);
3583 }
3584
3585 inline void set_buf(HeapWord* buf) {
3586 if (use_local_bitmaps && _during_marking)
3587 _bitmap.set_buffer(buf);
3588 ParGCAllocBuffer::set_buf(buf);
3589 _retired = false;
3590 }
3591
3592 inline void retire(bool end_of_gc, bool retain) {
3593 if (_retired)
3594 return;
3595 if (use_local_bitmaps && _during_marking) {
3596 _bitmap.retire();
3597 }
3598 ParGCAllocBuffer::retire(end_of_gc, retain);
3599 _retired = true;
3600 }
3601 };
3602
3603
3604 class G1ParScanThreadState : public StackObj {
3605 protected:
3606 G1CollectedHeap* _g1h;
3607 RefToScanQueue* _refs;
3608 DirtyCardQueue _dcq;
3609 CardTableModRefBS* _ct_bs;
3610 G1RemSet* _g1_rem;
3611
3612 typedef GrowableArray<oop*> OverflowQueue;
3613 OverflowQueue* _overflowed_refs;
3614
3615 G1ParGCAllocBuffer _alloc_buffers[GCAllocPurposeCount];
3616 ageTable _age_table;
3617
3618 size_t _alloc_buffer_waste;
3619 size_t _undo_waste;
3620
3621 OopsInHeapRegionClosure* _evac_failure_cl;
3622 G1ParScanHeapEvacClosure* _evac_cl;
3623 G1ParScanPartialArrayClosure* _partial_scan_cl;
3624
3625 int _hash_seed;
3626 int _queue_num;
3627
3628 int _term_attempts;
3629 #if G1_DETAILED_STATS
3630 int _pushes, _pops, _steals, _steal_attempts;
3631 int _overflow_pushes;
3632 #endif
3633
3634 double _start;
3635 double _start_strong_roots;
3636 double _strong_roots_time;
3637 double _start_term;
3638 double _term_time;
3639
3640 // Map from young-age-index (0 == not young, 1 is youngest) to
3641 // surviving words. base is what we get back from the malloc call
3642 size_t* _surviving_young_words_base;
3643 // this points into the array, as we use the first few entries for padding
3644 size_t* _surviving_young_words;
3645
3646 #define PADDING_ELEM_NUM (64 / sizeof(size_t))
3647
3648 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
3649
3650 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
3651
3652 DirtyCardQueue& dirty_card_queue() { return _dcq; }
3653 CardTableModRefBS* ctbs() { return _ct_bs; }
3654
3655 void immediate_rs_update(HeapRegion* from, oop* p, int tid) {
3656 if (!from->is_survivor()) {
3657 _g1_rem->par_write_ref(from, p, tid);
3658 }
3659 }
3660
3661 void deferred_rs_update(HeapRegion* from, oop* p, int tid) {
3662 // If the new value of the field points to the same region or
3663 // is the to-space, we don't need to include it in the Rset updates.
3664 if (!from->is_in_reserved(*p) && !from->is_survivor()) {
3665 size_t card_index = ctbs()->index_for(p);
3666 // If the card hasn't been added to the buffer, do it.
3667 if (ctbs()->mark_card_deferred(card_index)) {
3668 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
3669 }
3670 }
3671 }
3672
3673 public:
3674 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3675 : _g1h(g1h),
3676 _refs(g1h->task_queue(queue_num)),
3677 _dcq(&g1h->dirty_card_queue_set()),
3678 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
3679 _g1_rem(g1h->g1_rem_set()),
3680 _hash_seed(17), _queue_num(queue_num),
3681 _term_attempts(0),
3682 _age_table(false),
3683 #if G1_DETAILED_STATS
3684 _pushes(0), _pops(0), _steals(0),
3685 _steal_attempts(0), _overflow_pushes(0),
3686 #endif
3687 _strong_roots_time(0), _term_time(0),
3688 _alloc_buffer_waste(0), _undo_waste(0)
3689 {
3690 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3691 // we "sacrifice" entry 0 to keep track of surviving bytes for
3692 // non-young regions (where the age is -1)
3693 // We also add a few elements at the beginning and at the end in
3694 // an attempt to eliminate cache contention
3695 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3696 size_t array_length = PADDING_ELEM_NUM +
3697 real_length +
3698 PADDING_ELEM_NUM;
3699 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3700 if (_surviving_young_words_base == NULL)
3701 vm_exit_out_of_memory(array_length * sizeof(size_t),
3702 "Not enough space for young surv histo.");
3703 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3704 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3705
3706 _overflowed_refs = new OverflowQueue(10);
3707
3708 _start = os::elapsedTime();
3709 }
3710
3711 ~G1ParScanThreadState() {
3712 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
3713 }
3714
3715 RefToScanQueue* refs() { return _refs; }
3716 OverflowQueue* overflowed_refs() { return _overflowed_refs; }
3717 ageTable* age_table() { return &_age_table; }
3718
3719 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
3720 return &_alloc_buffers[purpose];
3721 }
3722
3723 size_t alloc_buffer_waste() { return _alloc_buffer_waste; }
3724 size_t undo_waste() { return _undo_waste; }
3725
3726 void push_on_queue(oop* ref) {
3727 assert(ref != NULL, "invariant");
3728 assert(has_partial_array_mask(ref) || _g1h->obj_in_cs(*ref), "invariant");
3729
3730 if (!refs()->push(ref)) {
3731 overflowed_refs()->push(ref);
3732 IF_G1_DETAILED_STATS(note_overflow_push());
3733 } else {
3734 IF_G1_DETAILED_STATS(note_push());
3735 }
3736 }
3737
3738 void pop_from_queue(oop*& ref) {
3739 if (!refs()->pop_local(ref)) {
3740 ref = NULL;
3741 } else {
3742 assert(ref != NULL, "invariant");
3743 assert(has_partial_array_mask(ref) || _g1h->obj_in_cs(*ref),
3744 "invariant");
3745
3746 IF_G1_DETAILED_STATS(note_pop());
3747 }
3748 }
3749
3750 void pop_from_overflow_queue(oop*& ref) {
3751 ref = overflowed_refs()->pop();
3752 }
3753
3754 int refs_to_scan() { return refs()->size(); }
3755 int overflowed_refs_to_scan() { return overflowed_refs()->length(); }
3756
3757 void update_rs(HeapRegion* from, oop* p, int tid) {
3758 if (G1DeferredRSUpdate) {
3759 deferred_rs_update(from, p, tid);
3760 } else {
3761 immediate_rs_update(from, p, tid);
3762 }
3763 }
3764
3765 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
3766
3767 HeapWord* obj = NULL;
3768 if (word_sz * 100 <
3769 (size_t)(ParallelGCG1AllocBufferSize / HeapWordSize) *
3770 ParallelGCBufferWastePct) {
3771 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
3772 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
3773 alloc_buf->retire(false, false);
3774
3775 HeapWord* buf =
3776 _g1h->par_allocate_during_gc(purpose, ParallelGCG1AllocBufferSize / HeapWordSize);
3777 if (buf == NULL) return NULL; // Let caller handle allocation failure.
3778 // Otherwise.
3779 alloc_buf->set_buf(buf);
3780
3781 obj = alloc_buf->allocate(word_sz);
3782 assert(obj != NULL, "buffer was definitely big enough...");
3783 } else {
3784 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
3785 }
3786 return obj;
3787 }
3788
3789 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
3790 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
3791 if (obj != NULL) return obj;
3792 return allocate_slow(purpose, word_sz);
3793 }
3794
3795 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
3796 if (alloc_buffer(purpose)->contains(obj)) {
3797 guarantee(alloc_buffer(purpose)->contains(obj + word_sz - 1),
3798 "should contain whole object");
3799 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
3800 } else {
3801 CollectedHeap::fill_with_object(obj, word_sz);
3802 add_to_undo_waste(word_sz);
3803 }
3804 }
3805
3806 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
3807 _evac_failure_cl = evac_failure_cl;
3808 }
3809 OopsInHeapRegionClosure* evac_failure_closure() {
3810 return _evac_failure_cl;
3811 }
3812
3813 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
3814 _evac_cl = evac_cl;
3815 }
3816
3817 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
3818 _partial_scan_cl = partial_scan_cl;
3819 }
3820
3821 int* hash_seed() { return &_hash_seed; }
3822 int queue_num() { return _queue_num; }
3823
3824 int term_attempts() { return _term_attempts; }
3825 void note_term_attempt() { _term_attempts++; }
3826
3827 #if G1_DETAILED_STATS
3828 int pushes() { return _pushes; }
3829 int pops() { return _pops; }
3830 int steals() { return _steals; }
3831 int steal_attempts() { return _steal_attempts; }
3832 int overflow_pushes() { return _overflow_pushes; }
3833
3834 void note_push() { _pushes++; }
3835 void note_pop() { _pops++; }
3836 void note_steal() { _steals++; }
3837 void note_steal_attempt() { _steal_attempts++; }
3838 void note_overflow_push() { _overflow_pushes++; }
3839 #endif
3840
3841 void start_strong_roots() {
3842 _start_strong_roots = os::elapsedTime();
3843 }
3844 void end_strong_roots() {
3845 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
3846 }
3847 double strong_roots_time() { return _strong_roots_time; }
3848
3849 void start_term_time() {
3850 note_term_attempt();
3851 _start_term = os::elapsedTime();
3852 }
3853 void end_term_time() {
3854 _term_time += (os::elapsedTime() - _start_term);
3855 }
3856 double term_time() { return _term_time; }
3857
3858 double elapsed() {
3859 return os::elapsedTime() - _start;
3860 }
3861
3862 size_t* surviving_young_words() {
3863 // We add on to hide entry 0 which accumulates surviving words for
3864 // age -1 regions (i.e. non-young ones)
3865 return _surviving_young_words;
3866 }
3867
3868 void retire_alloc_buffers() {
3869 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3870 size_t waste = _alloc_buffers[ap].words_remaining();
3871 add_to_alloc_buffer_waste(waste);
3872 _alloc_buffers[ap].retire(true, false);
3873 }
3874 }
3875
3876 private:
3877 void deal_with_reference(oop* ref_to_scan) {
3878 if (has_partial_array_mask(ref_to_scan)) {
3879 _partial_scan_cl->do_oop_nv(ref_to_scan);
3880 } else {
3881 // Note: we can use "raw" versions of "region_containing" because
3882 // "obj_to_scan" is definitely in the heap, and is not in a
3883 // humongous region.
3884 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
3885 _evac_cl->set_region(r);
3886 _evac_cl->do_oop_nv(ref_to_scan);
3887 }
3888 }
3889
3890 public:
3891 void trim_queue() {
3892 // I've replicated the loop twice, first to drain the overflow
3893 // queue, second to drain the task queue. This is better than
3894 // having a single loop, which checks both conditions and, inside
3895 // it, either pops the overflow queue or the task queue, as each
3896 // loop is tighter. Also, the decision to drain the overflow queue
3897 // first is not arbitrary, as the overflow queue is not visible
3898 // to the other workers, whereas the task queue is. So, we want to
3899 // drain the "invisible" entries first, while allowing the other
3900 // workers to potentially steal the "visible" entries.
3901
3902 while (refs_to_scan() > 0 || overflowed_refs_to_scan() > 0) {
3903 while (overflowed_refs_to_scan() > 0) {
3904 oop *ref_to_scan = NULL;
3905 pop_from_overflow_queue(ref_to_scan);
3906 assert(ref_to_scan != NULL, "invariant");
3907 // We shouldn't have pushed it on the queue if it was not
3908 // pointing into the CSet.
3909 assert(ref_to_scan != NULL, "sanity");
3910 assert(has_partial_array_mask(ref_to_scan) ||
3911 _g1h->obj_in_cs(*ref_to_scan), "sanity");
3912
3913 deal_with_reference(ref_to_scan);
3914 }
3915
3916 while (refs_to_scan() > 0) {
3917 oop *ref_to_scan = NULL;
3918 pop_from_queue(ref_to_scan);
3919
3920 if (ref_to_scan != NULL) {
3921 // We shouldn't have pushed it on the queue if it was not
3922 // pointing into the CSet.
3923 assert(has_partial_array_mask(ref_to_scan) ||
3924 _g1h->obj_in_cs(*ref_to_scan), "sanity");
3925
3926 deal_with_reference(ref_to_scan);
3927 }
3928 }
3929 }
3930 }
3931 };
3932
3933 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
3934 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
3935 _par_scan_state(par_scan_state) { }
3936
3937 // This closure is applied to the fields of the objects that have just been copied.
3938 // Should probably be made inline and moved in g1OopClosures.inline.hpp.
3939 void G1ParScanClosure::do_oop_nv(oop* p) {
3940 oop obj = *p;
3941
3942 if (obj != NULL) {
3943 if (_g1->in_cset_fast_test(obj)) {
3944 // We're not going to even bother checking whether the object is
3945 // already forwarded or not, as this usually causes an immediate
3946 // stall. We'll try to prefetch the object (for write, given that
3947 // we might need to install the forwarding reference) and we'll
3948 // get back to it when pop it from the queue
3949 Prefetch::write(obj->mark_addr(), 0);
3950 Prefetch::read(obj->mark_addr(), (HeapWordSize*2));
3951
3952 // slightly paranoid test; I'm trying to catch potential
3953 // problems before we go into push_on_queue to know where the
3954 // problem is coming from
3955 assert(obj == *p, "the value of *p should not have changed");
3956 _par_scan_state->push_on_queue(p);
3957 } else {
3958 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
3959 }
3960 }
3961 }
3962
3963 void G1ParCopyHelper::mark_forwardee(oop* p) {
3964 // This is called _after_ do_oop_work has been called, hence after
3965 // the object has been relocated to its new location and *p points
3966 // to its new location.
3967
3968 oop thisOop = *p;
3969 if (thisOop != NULL) {
3970 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(thisOop)),
3971 "shouldn't still be in the CSet if evacuation didn't fail.");
3972 HeapWord* addr = (HeapWord*)thisOop;
3973 if (_g1->is_in_g1_reserved(addr))
3974 _cm->grayRoot(oop(addr));
3975 }
3976 }
3977
3978 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
3979 size_t word_sz = old->size();
3980 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
3981 // +1 to make the -1 indexes valid...
3982 int young_index = from_region->young_index_in_cset()+1;
3983 assert( (from_region->is_young() && young_index > 0) ||
3984 (!from_region->is_young() && young_index == 0), "invariant" );
3985 G1CollectorPolicy* g1p = _g1->g1_policy();
3986 markOop m = old->mark();
3987 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
3988 : m->age();
3989 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
3990 word_sz);
3991 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
3992 oop obj = oop(obj_ptr);
3993
3994 if (obj_ptr == NULL) {
3995 // This will either forward-to-self, or detect that someone else has
3996 // installed a forwarding pointer.
3997 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
3998 return _g1->handle_evacuation_failure_par(cl, old);
3999 }
4000
4001 // We're going to allocate linearly, so might as well prefetch ahead.
4002 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4003
4004 oop forward_ptr = old->forward_to_atomic(obj);
4005 if (forward_ptr == NULL) {
4006 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4007 if (g1p->track_object_age(alloc_purpose)) {
4008 // We could simply do obj->incr_age(). However, this causes a
4009 // performance issue. obj->incr_age() will first check whether
4010 // the object has a displaced mark by checking its mark word;
4011 // getting the mark word from the new location of the object
4012 // stalls. So, given that we already have the mark word and we
4013 // are about to install it anyway, it's better to increase the
4014 // age on the mark word, when the object does not have a
4015 // displaced mark word. We're not expecting many objects to have
4016 // a displaced marked word, so that case is not optimized
4017 // further (it could be...) and we simply call obj->incr_age().
4018
4019 if (m->has_displaced_mark_helper()) {
4020 // in this case, we have to install the mark word first,
4021 // otherwise obj looks to be forwarded (the old mark word,
4022 // which contains the forward pointer, was copied)
4023 obj->set_mark(m);
4024 obj->incr_age();
4025 } else {
4026 m = m->incr_age();
4027 obj->set_mark(m);
4028 }
4029 _par_scan_state->age_table()->add(obj, word_sz);
4030 } else {
4031 obj->set_mark(m);
4032 }
4033
4034 // preserve "next" mark bit
4035 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
4036 if (!use_local_bitmaps ||
4037 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4038 // if we couldn't mark it on the local bitmap (this happens when
4039 // the object was not allocated in the GCLab), we have to bite
4040 // the bullet and do the standard parallel mark
4041 _cm->markAndGrayObjectIfNecessary(obj);
4042 }
4043 #if 1
4044 if (_g1->isMarkedNext(old)) {
4045 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4046 }
4047 #endif
4048 }
4049
4050 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4051 surv_young_words[young_index] += word_sz;
4052
4053 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4054 arrayOop(old)->set_length(0);
4055 _par_scan_state->push_on_queue(set_partial_array_mask(old));
4056 } else {
4057 // No point in using the slower heap_region_containing() method,
4058 // given that we know obj is in the heap.
4059 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4060 obj->oop_iterate_backwards(_scanner);
4061 }
4062 } else {
4063 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4064 obj = forward_ptr;
4065 }
4066 return obj;
4067 }
4068
4069 template<bool do_gen_barrier, G1Barrier barrier,
4070 bool do_mark_forwardee, bool skip_cset_test>
4071 void G1ParCopyClosure<do_gen_barrier, barrier,
4072 do_mark_forwardee, skip_cset_test>::do_oop_work(oop* p) {
4073 oop obj = *p;
4074 assert(barrier != G1BarrierRS || obj != NULL,
4075 "Precondition: G1BarrierRS implies obj is nonNull");
4076
4077 // The only time we skip the cset test is when we're scanning
4078 // references popped from the queue. And we only push on the queue
4079 // references that we know point into the cset, so no point in
4080 // checking again. But we'll leave an assert here for peace of mind.
4081 assert(!skip_cset_test || _g1->obj_in_cs(obj), "invariant");
4082
4083 // here the null check is implicit in the cset_fast_test() test
4084 if (skip_cset_test || _g1->in_cset_fast_test(obj)) {
4085 #if G1_REM_SET_LOGGING
4086 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
4087 "into CS.", p, (void*) obj);
4088 #endif
4089 if (obj->is_forwarded()) {
4090 *p = obj->forwardee();
4091 } else {
4092 *p = copy_to_survivor_space(obj);
4093 }
4094 // When scanning the RS, we only care about objs in CS.
4095 if (barrier == G1BarrierRS) {
4096 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4097 }
4098 }
4099
4100 // When scanning moved objs, must look at all oops.
4101 if (barrier == G1BarrierEvac && obj != NULL) {
4102 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4103 }
4104
4105 if (do_gen_barrier && obj != NULL) {
4106 par_do_barrier(p);
4107 }
4108 }
4109
4110 template void G1ParCopyClosure<false, G1BarrierEvac, false, true>::do_oop_work(oop* p);
4111
4112 template<class T> void G1ParScanPartialArrayClosure::process_array_chunk(
4113 oop obj, int start, int end) {
4114 // process our set of indices (include header in first chunk)
4115 assert(start < end, "invariant");
4116 T* const base = (T*)objArrayOop(obj)->base();
4117 T* const start_addr = (start == 0) ? (T*) obj : base + start;
4118 T* const end_addr = base + end;
4119 MemRegion mr((HeapWord*)start_addr, (HeapWord*)end_addr);
4120 _scanner.set_region(_g1->heap_region_containing(obj));
4121 obj->oop_iterate(&_scanner, mr);
4122 }
4123
4124 void G1ParScanPartialArrayClosure::do_oop_nv(oop* p) {
4125 assert(!UseCompressedOops, "Needs to be fixed to work with compressed oops");
4126 assert(has_partial_array_mask(p), "invariant");
4127 oop old = clear_partial_array_mask(p);
4128 assert(old->is_objArray(), "must be obj array");
4129 assert(old->is_forwarded(), "must be forwarded");
4130 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4131
4132 objArrayOop obj = objArrayOop(old->forwardee());
4133 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4134 // Process ParGCArrayScanChunk elements now
4135 // and push the remainder back onto queue
4136 int start = arrayOop(old)->length();
4137 int end = obj->length();
4138 int remainder = end - start;
4139 assert(start <= end, "just checking");
4140 if (remainder > 2 * ParGCArrayScanChunk) {
4141 // Test above combines last partial chunk with a full chunk
4142 end = start + ParGCArrayScanChunk;
4143 arrayOop(old)->set_length(end);
4144 // Push remainder.
4145 _par_scan_state->push_on_queue(set_partial_array_mask(old));
4146 } else {
4147 // Restore length so that the heap remains parsable in
4148 // case of evacuation failure.
4149 arrayOop(old)->set_length(end);
4150 }
4151
4152 // process our set of indices (include header in first chunk)
4153 process_array_chunk<oop>(obj, start, end);
4154 }
4155
4156 int G1ScanAndBalanceClosure::_nq = 0;
4157
4158 class G1ParEvacuateFollowersClosure : public VoidClosure {
4159 protected:
4160 G1CollectedHeap* _g1h;
4161 G1ParScanThreadState* _par_scan_state;
4162 RefToScanQueueSet* _queues;
4163 ParallelTaskTerminator* _terminator;
4164
4165 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4166 RefToScanQueueSet* queues() { return _queues; }
4167 ParallelTaskTerminator* terminator() { return _terminator; }
4168
4169 public:
4170 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4171 G1ParScanThreadState* par_scan_state,
4172 RefToScanQueueSet* queues,
4173 ParallelTaskTerminator* terminator)
4174 : _g1h(g1h), _par_scan_state(par_scan_state),
4175 _queues(queues), _terminator(terminator) {}
4176
4177 void do_void() {
4178 G1ParScanThreadState* pss = par_scan_state();
4179 while (true) {
4180 oop* ref_to_scan;
4181 pss->trim_queue();
4182 IF_G1_DETAILED_STATS(pss->note_steal_attempt());
4183 if (queues()->steal(pss->queue_num(),
4184 pss->hash_seed(),
4185 ref_to_scan)) {
4186 IF_G1_DETAILED_STATS(pss->note_steal());
4187
4188 // slightly paranoid tests; I'm trying to catch potential
4189 // problems before we go into push_on_queue to know where the
4190 // problem is coming from
4191 assert(ref_to_scan != NULL, "invariant");
4192 assert(has_partial_array_mask(ref_to_scan) ||
4193 _g1h->obj_in_cs(*ref_to_scan), "invariant");
4194 pss->push_on_queue(ref_to_scan);
4195 continue;
4196 }
4197 pss->start_term_time();
4198 if (terminator()->offer_termination()) break;
4199 pss->end_term_time();
4200 }
4201 pss->end_term_time();
4202 pss->retire_alloc_buffers();
4203 }
4204 };
4205
4206 class G1ParTask : public AbstractGangTask {
4207 protected:
4208 G1CollectedHeap* _g1h;
4209 RefToScanQueueSet *_queues;
4210 ParallelTaskTerminator _terminator;
4211
4212 Mutex _stats_lock;
4213 Mutex* stats_lock() { return &_stats_lock; }
4214
4215 size_t getNCards() {
4216 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4217 / G1BlockOffsetSharedArray::N_bytes;
4218 }
4219
4220 public:
4221 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4222 : AbstractGangTask("G1 collection"),
4223 _g1h(g1h),
4224 _queues(task_queues),
4225 _terminator(workers, _queues),
4226 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4227 {}
4228
4229 RefToScanQueueSet* queues() { return _queues; }
4230
4231 RefToScanQueue *work_queue(int i) {
4232 return queues()->queue(i);
4233 }
4234
4235 void work(int i) {
4236 ResourceMark rm;
4237 HandleMark hm;
4238
4239 G1ParScanThreadState pss(_g1h, i);
4240 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4241 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4242 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4243
4244 pss.set_evac_closure(&scan_evac_cl);
4245 pss.set_evac_failure_closure(&evac_failure_cl);
4246 pss.set_partial_scan_closure(&partial_scan_cl);
4247
4248 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4249 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4250 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4251
4252 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4253 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4254 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4255
4256 OopsInHeapRegionClosure *scan_root_cl;
4257 OopsInHeapRegionClosure *scan_perm_cl;
4258 OopsInHeapRegionClosure *scan_so_cl;
4259
4260 if (_g1h->g1_policy()->should_initiate_conc_mark()) {
4261 scan_root_cl = &scan_mark_root_cl;
4262 scan_perm_cl = &scan_mark_perm_cl;
4263 scan_so_cl = &scan_mark_heap_rs_cl;
4264 } else {
4265 scan_root_cl = &only_scan_root_cl;
4266 scan_perm_cl = &only_scan_perm_cl;
4267 scan_so_cl = &only_scan_heap_rs_cl;
4268 }
4269
4270 pss.start_strong_roots();
4271 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4272 SharedHeap::SO_AllClasses,
4273 scan_root_cl,
4274 &only_scan_heap_rs_cl,
4275 scan_so_cl,
4276 scan_perm_cl,
4277 i);
4278 pss.end_strong_roots();
4279 {
4280 double start = os::elapsedTime();
4281 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4282 evac.do_void();
4283 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4284 double term_ms = pss.term_time()*1000.0;
4285 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4286 _g1h->g1_policy()->record_termination_time(i, term_ms);
4287 }
4288 if (G1UseSurvivorSpace) {
4289 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4290 }
4291 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4292
4293 // Clean up any par-expanded rem sets.
4294 HeapRegionRemSet::par_cleanup();
4295
4296 MutexLocker x(stats_lock());
4297 if (ParallelGCVerbose) {
4298 gclog_or_tty->print("Thread %d complete:\n", i);
4299 #if G1_DETAILED_STATS
4300 gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n",
4301 pss.pushes(),
4302 pss.pops(),
4303 pss.overflow_pushes(),
4304 pss.steals(),
4305 pss.steal_attempts());
4306 #endif
4307 double elapsed = pss.elapsed();
4308 double strong_roots = pss.strong_roots_time();
4309 double term = pss.term_time();
4310 gclog_or_tty->print(" Elapsed: %7.2f ms.\n"
4311 " Strong roots: %7.2f ms (%6.2f%%)\n"
4312 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n",
4313 elapsed * 1000.0,
4314 strong_roots * 1000.0, (strong_roots*100.0/elapsed),
4315 term * 1000.0, (term*100.0/elapsed),
4316 pss.term_attempts());
4317 size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste();
4318 gclog_or_tty->print(" Waste: %8dK\n"
4319 " Alloc Buffer: %8dK\n"
4320 " Undo: %8dK\n",
4321 (total_waste * HeapWordSize) / K,
4322 (pss.alloc_buffer_waste() * HeapWordSize) / K,
4323 (pss.undo_waste() * HeapWordSize) / K);
4324 }
4325
4326 assert(pss.refs_to_scan() == 0, "Task queue should be empty");
4327 assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
4328 }
4329 };
4330
4331 // *** Common G1 Evacuation Stuff
4332
4333 class G1CountClosure: public OopsInHeapRegionClosure {
4334 public:
4335 int n;
4336 G1CountClosure() : n(0) {}
4337 void do_oop(narrowOop* p) {
4338 guarantee(false, "NYI");
4339 }
4340 void do_oop(oop* p) {
4341 oop obj = *p;
4342 assert(obj != NULL && G1CollectedHeap::heap()->obj_in_cs(obj),
4343 "Rem set closure called on non-rem-set pointer.");
4344 n++;
4345 }
4346 };
4347
4348 static G1CountClosure count_closure;
4349
4350 void
4351 G1CollectedHeap::
4352 g1_process_strong_roots(bool collecting_perm_gen,
4353 SharedHeap::ScanningOption so,
4354 OopClosure* scan_non_heap_roots,
4355 OopsInHeapRegionClosure* scan_rs,
4356 OopsInHeapRegionClosure* scan_so,
4357 OopsInGenClosure* scan_perm,
4358 int worker_i) {
4359 // First scan the strong roots, including the perm gen.
4360 double ext_roots_start = os::elapsedTime();
4361 double closure_app_time_sec = 0.0;
4362
4363 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4364 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4365 buf_scan_perm.set_generation(perm_gen());
4366
4367 process_strong_roots(collecting_perm_gen, so,
4368 &buf_scan_non_heap_roots,
4369 &buf_scan_perm);
4370 // Finish up any enqueued closure apps.
4371 buf_scan_non_heap_roots.done();
4372 buf_scan_perm.done();
4373 double ext_roots_end = os::elapsedTime();
4374 g1_policy()->reset_obj_copy_time(worker_i);
4375 double obj_copy_time_sec =
4376 buf_scan_non_heap_roots.closure_app_seconds() +
4377 buf_scan_perm.closure_app_seconds();
4378 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4379 double ext_root_time_ms =
4380 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4381 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4382
4383 // Scan strong roots in mark stack.
4384 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4385 concurrent_mark()->oops_do(scan_non_heap_roots);
4386 }
4387 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4388 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4389
4390 // XXX What should this be doing in the parallel case?
4391 g1_policy()->record_collection_pause_end_CH_strong_roots();
4392 if (G1VerifyRemSet) {
4393 // :::: FIXME ::::
4394 // The stupid remembered set doesn't know how to filter out dead
4395 // objects, which the smart one does, and so when it is created
4396 // and then compared the number of entries in each differs and
4397 // the verification code fails.
4398 guarantee(false, "verification code is broken, see note");
4399
4400 // Let's make sure that the current rem set agrees with the stupidest
4401 // one possible!
4402 bool refs_enabled = ref_processor()->discovery_enabled();
4403 if (refs_enabled) ref_processor()->disable_discovery();
4404 StupidG1RemSet stupid(this);
4405 count_closure.n = 0;
4406 stupid.oops_into_collection_set_do(&count_closure, worker_i);
4407 int stupid_n = count_closure.n;
4408 count_closure.n = 0;
4409 g1_rem_set()->oops_into_collection_set_do(&count_closure, worker_i);
4410 guarantee(count_closure.n == stupid_n, "Old and new rem sets differ.");
4411 gclog_or_tty->print_cr("\nFound %d pointers in heap RS.", count_closure.n);
4412 if (refs_enabled) ref_processor()->enable_discovery();
4413 }
4414 if (scan_so != NULL) {
4415 scan_scan_only_set(scan_so, worker_i);
4416 }
4417 // Now scan the complement of the collection set.
4418 if (scan_rs != NULL) {
4419 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4420 }
4421 // Finish with the ref_processor roots.
4422 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4423 ref_processor()->oops_do(scan_non_heap_roots);
4424 }
4425 g1_policy()->record_collection_pause_end_G1_strong_roots();
4426 _process_strong_tasks->all_tasks_completed();
4427 }
4428
4429 void
4430 G1CollectedHeap::scan_scan_only_region(HeapRegion* r,
4431 OopsInHeapRegionClosure* oc,
4432 int worker_i) {
4433 HeapWord* startAddr = r->bottom();
4434 HeapWord* endAddr = r->used_region().end();
4435
4436 oc->set_region(r);
4437
4438 HeapWord* p = r->bottom();
4439 HeapWord* t = r->top();
4440 guarantee( p == r->next_top_at_mark_start(), "invariant" );
4441 while (p < t) {
4442 oop obj = oop(p);
4443 p += obj->oop_iterate(oc);
4444 }
4445 }
4446
4447 void
4448 G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc,
4449 int worker_i) {
4450 double start = os::elapsedTime();
4451
4452 BufferingOopsInHeapRegionClosure boc(oc);
4453
4454 FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc);
4455 FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark());
4456
4457 OopsInHeapRegionClosure *foc;
4458 if (g1_policy()->should_initiate_conc_mark())
4459 foc = &scan_and_mark;
4460 else
4461 foc = &scan_only;
4462
4463 HeapRegion* hr;
4464 int n = 0;
4465 while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) {
4466 scan_scan_only_region(hr, foc, worker_i);
4467 ++n;
4468 }
4469 boc.done();
4470
4471 double closure_app_s = boc.closure_app_seconds();
4472 g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0);
4473 double ms = (os::elapsedTime() - start - closure_app_s)*1000.0;
4474 g1_policy()->record_scan_only_time(worker_i, ms, n);
4475 }
4476
4477 void
4478 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4479 OopClosure* non_root_closure) {
4480 SharedHeap::process_weak_roots(root_closure, non_root_closure);
4481 }
4482
4483
4484 class SaveMarksClosure: public HeapRegionClosure {
4485 public:
4486 bool doHeapRegion(HeapRegion* r) {
4487 r->save_marks();
4488 return false;
4489 }
4490 };
4491
4492 void G1CollectedHeap::save_marks() {
4493 if (ParallelGCThreads == 0) {
4494 SaveMarksClosure sm;
4495 heap_region_iterate(&sm);
4496 }
4497 // We do this even in the parallel case
4498 perm_gen()->save_marks();
4499 }
4500
4501 void G1CollectedHeap::evacuate_collection_set() {
4502 set_evacuation_failed(false);
4503
4504 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4505 concurrent_g1_refine()->set_use_cache(false);
4506 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4507 set_par_threads(n_workers);
4508 G1ParTask g1_par_task(this, n_workers, _task_queues);
4509
4510 init_for_evac_failure(NULL);
4511
4512 change_strong_roots_parity(); // In preparation for parallel strong roots.
4513 rem_set()->prepare_for_younger_refs_iterate(true);
4514
4515 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4516 double start_par = os::elapsedTime();
4517 if (ParallelGCThreads > 0) {
4518 // The individual threads will set their evac-failure closures.
4519 workers()->run_task(&g1_par_task);
4520 } else {
4521 g1_par_task.work(0);
4522 }
4523
4524 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4525 g1_policy()->record_par_time(par_time);
4526 set_par_threads(0);
4527 // Is this the right thing to do here? We don't save marks
4528 // on individual heap regions when we allocate from
4529 // them in parallel, so this seems like the correct place for this.
4530 retire_all_alloc_regions();
4531 {
4532 G1IsAliveClosure is_alive(this);
4533 G1KeepAliveClosure keep_alive(this);
4534 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4535 }
4536 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4537
4538 concurrent_g1_refine()->set_use_cache(true);
4539
4540 finalize_for_evac_failure();
4541
4542 // Must do this before removing self-forwarding pointers, which clears
4543 // the per-region evac-failure flags.
4544 concurrent_mark()->complete_marking_in_collection_set();
4545
4546 if (evacuation_failed()) {
4547 remove_self_forwarding_pointers();
4548 if (PrintGCDetails) {
4549 gclog_or_tty->print(" (evacuation failed)");
4550 } else if (PrintGC) {
4551 gclog_or_tty->print("--");
4552 }
4553 }
4554
4555 if (G1DeferredRSUpdate) {
4556 RedirtyLoggedCardTableEntryFastClosure redirty;
4557 dirty_card_queue_set().set_closure(&redirty);
4558 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4559 JavaThread::dirty_card_queue_set().merge_bufferlists(&dirty_card_queue_set());
4560 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4561 }
4562
4563 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4564 }
4565
4566 void G1CollectedHeap::free_region(HeapRegion* hr) {
4567 size_t pre_used = 0;
4568 size_t cleared_h_regions = 0;
4569 size_t freed_regions = 0;
4570 UncleanRegionList local_list;
4571
4572 HeapWord* start = hr->bottom();
4573 HeapWord* end = hr->prev_top_at_mark_start();
4574 size_t used_bytes = hr->used();
4575 size_t live_bytes = hr->max_live_bytes();
4576 if (used_bytes > 0) {
4577 guarantee( live_bytes <= used_bytes, "invariant" );
4578 } else {
4579 guarantee( live_bytes == 0, "invariant" );
4580 }
4581
4582 size_t garbage_bytes = used_bytes - live_bytes;
4583 if (garbage_bytes > 0)
4584 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4585
4586 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4587 &local_list);
4588 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4589 &local_list);
4590 }
4591
4592 void
4593 G1CollectedHeap::free_region_work(HeapRegion* hr,
4594 size_t& pre_used,
4595 size_t& cleared_h_regions,
4596 size_t& freed_regions,
4597 UncleanRegionList* list,
4598 bool par) {
4599 assert(!hr->popular(), "should not free popular regions");
4600 pre_used += hr->used();
4601 if (hr->isHumongous()) {
4602 assert(hr->startsHumongous(),
4603 "Only the start of a humongous region should be freed.");
4604 int ind = _hrs->find(hr);
4605 assert(ind != -1, "Should have an index.");
4606 // Clear the start region.
4607 hr->hr_clear(par, true /*clear_space*/);
4608 list->insert_before_head(hr);
4609 cleared_h_regions++;
4610 freed_regions++;
4611 // Clear any continued regions.
4612 ind++;
4613 while ((size_t)ind < n_regions()) {
4614 HeapRegion* hrc = _hrs->at(ind);
4615 if (!hrc->continuesHumongous()) break;
4616 // Otherwise, does continue the H region.
4617 assert(hrc->humongous_start_region() == hr, "Huh?");
4618 hrc->hr_clear(par, true /*clear_space*/);
4619 cleared_h_regions++;
4620 freed_regions++;
4621 list->insert_before_head(hrc);
4622 ind++;
4623 }
4624 } else {
4625 hr->hr_clear(par, true /*clear_space*/);
4626 list->insert_before_head(hr);
4627 freed_regions++;
4628 // If we're using clear2, this should not be enabled.
4629 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4630 }
4631 }
4632
4633 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4634 size_t cleared_h_regions,
4635 size_t freed_regions,
4636 UncleanRegionList* list) {
4637 if (list != NULL && list->sz() > 0) {
4638 prepend_region_list_on_unclean_list(list);
4639 }
4640 // Acquire a lock, if we're parallel, to update possibly-shared
4641 // variables.
4642 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4643 {
4644 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4645 _summary_bytes_used -= pre_used;
4646 _num_humongous_regions -= (int) cleared_h_regions;
4647 _free_regions += freed_regions;
4648 }
4649 }
4650
4651
4652 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4653 while (list != NULL) {
4654 guarantee( list->is_young(), "invariant" );
4655
4656 HeapWord* bottom = list->bottom();
4657 HeapWord* end = list->end();
4658 MemRegion mr(bottom, end);
4659 ct_bs->dirty(mr);
4660
4661 list = list->get_next_young_region();
4662 }
4663 }
4664
4665 void G1CollectedHeap::cleanUpCardTable() {
4666 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4667 double start = os::elapsedTime();
4668
4669 ct_bs->clear(_g1_committed);
4670
4671 // now, redirty the cards of the scan-only and survivor regions
4672 // (it seemed faster to do it this way, instead of iterating over
4673 // all regions and then clearing / dirtying as approprite)
4674 dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region());
4675 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4676
4677 double elapsed = os::elapsedTime() - start;
4678 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4679 }
4680
4681
4682 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4683 // First do any popular regions.
4684 HeapRegion* hr;
4685 while ((hr = popular_region_to_evac()) != NULL) {
4686 evac_popular_region(hr);
4687 }
4688 // Now do heuristic pauses.
4689 if (g1_policy()->should_do_collection_pause(word_size)) {
4690 do_collection_pause();
4691 }
4692 }
4693
4694 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4695 double young_time_ms = 0.0;
4696 double non_young_time_ms = 0.0;
4697
4698 G1CollectorPolicy* policy = g1_policy();
4699
4700 double start_sec = os::elapsedTime();
4701 bool non_young = true;
4702
4703 HeapRegion* cur = cs_head;
4704 int age_bound = -1;
4705 size_t rs_lengths = 0;
4706
4707 while (cur != NULL) {
4708 if (non_young) {
4709 if (cur->is_young()) {
4710 double end_sec = os::elapsedTime();
4711 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4712 non_young_time_ms += elapsed_ms;
4713
4714 start_sec = os::elapsedTime();
4715 non_young = false;
4716 }
4717 } else {
4718 if (!cur->is_on_free_list()) {
4719 double end_sec = os::elapsedTime();
4720 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4721 young_time_ms += elapsed_ms;
4722
4723 start_sec = os::elapsedTime();
4724 non_young = true;
4725 }
4726 }
4727
4728 rs_lengths += cur->rem_set()->occupied();
4729
4730 HeapRegion* next = cur->next_in_collection_set();
4731 assert(cur->in_collection_set(), "bad CS");
4732 cur->set_next_in_collection_set(NULL);
4733 cur->set_in_collection_set(false);
4734
4735 if (cur->is_young()) {
4736 int index = cur->young_index_in_cset();
4737 guarantee( index != -1, "invariant" );
4738 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4739 size_t words_survived = _surviving_young_words[index];
4740 cur->record_surv_words_in_group(words_survived);
4741 } else {
4742 int index = cur->young_index_in_cset();
4743 guarantee( index == -1, "invariant" );
4744 }
4745
4746 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4747 (!cur->is_young() && cur->young_index_in_cset() == -1),
4748 "invariant" );
4749
4750 if (!cur->evacuation_failed()) {
4751 // And the region is empty.
4752 assert(!cur->is_empty(),
4753 "Should not have empty regions in a CS.");
4754 free_region(cur);
4755 } else {
4756 guarantee( !cur->is_scan_only(), "should not be scan only" );
4757 cur->uninstall_surv_rate_group();
4758 if (cur->is_young())
4759 cur->set_young_index_in_cset(-1);
4760 cur->set_not_young();
4761 cur->set_evacuation_failed(false);
4762 }
4763 cur = next;
4764 }
4765
4766 policy->record_max_rs_lengths(rs_lengths);
4767 policy->cset_regions_freed();
4768
4769 double end_sec = os::elapsedTime();
4770 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4771 if (non_young)
4772 non_young_time_ms += elapsed_ms;
4773 else
4774 young_time_ms += elapsed_ms;
4775
4776 policy->record_young_free_cset_time_ms(young_time_ms);
4777 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4778 }
4779
4780 HeapRegion*
4781 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4782 assert(ZF_mon->owned_by_self(), "Precondition");
4783 HeapRegion* res = pop_unclean_region_list_locked();
4784 if (res != NULL) {
4785 assert(!res->continuesHumongous() &&
4786 res->zero_fill_state() != HeapRegion::Allocated,
4787 "Only free regions on unclean list.");
4788 if (zero_filled) {
4789 res->ensure_zero_filled_locked();
4790 res->set_zero_fill_allocated();
4791 }
4792 }
4793 return res;
4794 }
4795
4796 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4797 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4798 return alloc_region_from_unclean_list_locked(zero_filled);
4799 }
4800
4801 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4802 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4803 put_region_on_unclean_list_locked(r);
4804 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4805 }
4806
4807 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4808 MutexLockerEx x(Cleanup_mon);
4809 set_unclean_regions_coming_locked(b);
4810 }
4811
4812 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4813 assert(Cleanup_mon->owned_by_self(), "Precondition");
4814 _unclean_regions_coming = b;
4815 // Wake up mutator threads that might be waiting for completeCleanup to
4816 // finish.
4817 if (!b) Cleanup_mon->notify_all();
4818 }
4819
4820 void G1CollectedHeap::wait_for_cleanup_complete() {
4821 MutexLockerEx x(Cleanup_mon);
4822 wait_for_cleanup_complete_locked();
4823 }
4824
4825 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4826 assert(Cleanup_mon->owned_by_self(), "precondition");
4827 while (_unclean_regions_coming) {
4828 Cleanup_mon->wait();
4829 }
4830 }
4831
4832 void
4833 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4834 assert(ZF_mon->owned_by_self(), "precondition.");
4835 _unclean_region_list.insert_before_head(r);
4836 }
4837
4838 void
4839 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4840 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4841 prepend_region_list_on_unclean_list_locked(list);
4842 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4843 }
4844
4845 void
4846 G1CollectedHeap::
4847 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4848 assert(ZF_mon->owned_by_self(), "precondition.");
4849 _unclean_region_list.prepend_list(list);
4850 }
4851
4852 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4853 assert(ZF_mon->owned_by_self(), "precondition.");
4854 HeapRegion* res = _unclean_region_list.pop();
4855 if (res != NULL) {
4856 // Inform ZF thread that there's a new unclean head.
4857 if (_unclean_region_list.hd() != NULL && should_zf())
4858 ZF_mon->notify_all();
4859 }
4860 return res;
4861 }
4862
4863 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4864 assert(ZF_mon->owned_by_self(), "precondition.");
4865 return _unclean_region_list.hd();
4866 }
4867
4868
4869 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4870 assert(ZF_mon->owned_by_self(), "Precondition");
4871 HeapRegion* r = peek_unclean_region_list_locked();
4872 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4873 // Result of below must be equal to "r", since we hold the lock.
4874 (void)pop_unclean_region_list_locked();
4875 put_free_region_on_list_locked(r);
4876 return true;
4877 } else {
4878 return false;
4879 }
4880 }
4881
4882 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4883 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4884 return move_cleaned_region_to_free_list_locked();
4885 }
4886
4887
4888 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
4889 assert(ZF_mon->owned_by_self(), "precondition.");
4890 assert(_free_region_list_size == free_region_list_length(), "Inv");
4891 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
4892 "Regions on free list must be zero filled");
4893 assert(!r->isHumongous(), "Must not be humongous.");
4894 assert(r->is_empty(), "Better be empty");
4895 assert(!r->is_on_free_list(),
4896 "Better not already be on free list");
4897 assert(!r->is_on_unclean_list(),
4898 "Better not already be on unclean list");
4899 r->set_on_free_list(true);
4900 r->set_next_on_free_list(_free_region_list);
4901 _free_region_list = r;
4902 _free_region_list_size++;
4903 assert(_free_region_list_size == free_region_list_length(), "Inv");
4904 }
4905
4906 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
4907 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4908 put_free_region_on_list_locked(r);
4909 }
4910
4911 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
4912 assert(ZF_mon->owned_by_self(), "precondition.");
4913 assert(_free_region_list_size == free_region_list_length(), "Inv");
4914 HeapRegion* res = _free_region_list;
4915 if (res != NULL) {
4916 _free_region_list = res->next_from_free_list();
4917 _free_region_list_size--;
4918 res->set_on_free_list(false);
4919 res->set_next_on_free_list(NULL);
4920 assert(_free_region_list_size == free_region_list_length(), "Inv");
4921 }
4922 return res;
4923 }
4924
4925
4926 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
4927 // By self, or on behalf of self.
4928 assert(Heap_lock->is_locked(), "Precondition");
4929 HeapRegion* res = NULL;
4930 bool first = true;
4931 while (res == NULL) {
4932 if (zero_filled || !first) {
4933 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4934 res = pop_free_region_list_locked();
4935 if (res != NULL) {
4936 assert(!res->zero_fill_is_allocated(),
4937 "No allocated regions on free list.");
4938 res->set_zero_fill_allocated();
4939 } else if (!first) {
4940 break; // We tried both, time to return NULL.
4941 }
4942 }
4943
4944 if (res == NULL) {
4945 res = alloc_region_from_unclean_list(zero_filled);
4946 }
4947 assert(res == NULL ||
4948 !zero_filled ||
4949 res->zero_fill_is_allocated(),
4950 "We must have allocated the region we're returning");
4951 first = false;
4952 }
4953 return res;
4954 }
4955
4956 void G1CollectedHeap::remove_allocated_regions_from_lists() {
4957 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4958 {
4959 HeapRegion* prev = NULL;
4960 HeapRegion* cur = _unclean_region_list.hd();
4961 while (cur != NULL) {
4962 HeapRegion* next = cur->next_from_unclean_list();
4963 if (cur->zero_fill_is_allocated()) {
4964 // Remove from the list.
4965 if (prev == NULL) {
4966 (void)_unclean_region_list.pop();
4967 } else {
4968 _unclean_region_list.delete_after(prev);
4969 }
4970 cur->set_on_unclean_list(false);
4971 cur->set_next_on_unclean_list(NULL);
4972 } else {
4973 prev = cur;
4974 }
4975 cur = next;
4976 }
4977 assert(_unclean_region_list.sz() == unclean_region_list_length(),
4978 "Inv");
4979 }
4980
4981 {
4982 HeapRegion* prev = NULL;
4983 HeapRegion* cur = _free_region_list;
4984 while (cur != NULL) {
4985 HeapRegion* next = cur->next_from_free_list();
4986 if (cur->zero_fill_is_allocated()) {
4987 // Remove from the list.
4988 if (prev == NULL) {
4989 _free_region_list = cur->next_from_free_list();
4990 } else {
4991 prev->set_next_on_free_list(cur->next_from_free_list());
4992 }
4993 cur->set_on_free_list(false);
4994 cur->set_next_on_free_list(NULL);
4995 _free_region_list_size--;
4996 } else {
4997 prev = cur;
4998 }
4999 cur = next;
5000 }
5001 assert(_free_region_list_size == free_region_list_length(), "Inv");
5002 }
5003 }
5004
5005 bool G1CollectedHeap::verify_region_lists() {
5006 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5007 return verify_region_lists_locked();
5008 }
5009
5010 bool G1CollectedHeap::verify_region_lists_locked() {
5011 HeapRegion* unclean = _unclean_region_list.hd();
5012 while (unclean != NULL) {
5013 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
5014 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
5015 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
5016 "Everything else is possible.");
5017 unclean = unclean->next_from_unclean_list();
5018 }
5019 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
5020
5021 HeapRegion* free_r = _free_region_list;
5022 while (free_r != NULL) {
5023 assert(free_r->is_on_free_list(), "Well, it is!");
5024 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
5025 switch (free_r->zero_fill_state()) {
5026 case HeapRegion::NotZeroFilled:
5027 case HeapRegion::ZeroFilling:
5028 guarantee(false, "Should not be on free list.");
5029 break;
5030 default:
5031 // Everything else is possible.
5032 break;
5033 }
5034 free_r = free_r->next_from_free_list();
5035 }
5036 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
5037 // If we didn't do an assertion...
5038 return true;
5039 }
5040
5041 size_t G1CollectedHeap::free_region_list_length() {
5042 assert(ZF_mon->owned_by_self(), "precondition.");
5043 size_t len = 0;
5044 HeapRegion* cur = _free_region_list;
5045 while (cur != NULL) {
5046 len++;
5047 cur = cur->next_from_free_list();
5048 }
5049 return len;
5050 }
5051
5052 size_t G1CollectedHeap::unclean_region_list_length() {
5053 assert(ZF_mon->owned_by_self(), "precondition.");
5054 return _unclean_region_list.length();
5055 }
5056
5057 size_t G1CollectedHeap::n_regions() {
5058 return _hrs->length();
5059 }
5060
5061 size_t G1CollectedHeap::max_regions() {
5062 return
5063 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
5064 HeapRegion::GrainBytes;
5065 }
5066
5067 size_t G1CollectedHeap::free_regions() {
5068 /* Possibly-expensive assert.
5069 assert(_free_regions == count_free_regions(),
5070 "_free_regions is off.");
5071 */
5072 return _free_regions;
5073 }
5074
5075 bool G1CollectedHeap::should_zf() {
5076 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
5077 }
5078
5079 class RegionCounter: public HeapRegionClosure {
5080 size_t _n;
5081 public:
5082 RegionCounter() : _n(0) {}
5083 bool doHeapRegion(HeapRegion* r) {
5084 if (r->is_empty() && !r->popular()) {
5085 assert(!r->isHumongous(), "H regions should not be empty.");
5086 _n++;
5087 }
5088 return false;
5089 }
5090 int res() { return (int) _n; }
5091 };
5092
5093 size_t G1CollectedHeap::count_free_regions() {
5094 RegionCounter rc;
5095 heap_region_iterate(&rc);
5096 size_t n = rc.res();
5097 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
5098 n--;
5099 return n;
5100 }
5101
5102 size_t G1CollectedHeap::count_free_regions_list() {
5103 size_t n = 0;
5104 size_t o = 0;
5105 ZF_mon->lock_without_safepoint_check();
5106 HeapRegion* cur = _free_region_list;
5107 while (cur != NULL) {
5108 cur = cur->next_from_free_list();
5109 n++;
5110 }
5111 size_t m = unclean_region_list_length();
5112 ZF_mon->unlock();
5113 return n + m;
5114 }
5115
5116 bool G1CollectedHeap::should_set_young_locked() {
5117 assert(heap_lock_held_for_gc(),
5118 "the heap lock should already be held by or for this thread");
5119 return (g1_policy()->in_young_gc_mode() &&
5120 g1_policy()->should_add_next_region_to_young_list());
5121 }
5122
5123 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5124 assert(heap_lock_held_for_gc(),
5125 "the heap lock should already be held by or for this thread");
5126 _young_list->push_region(hr);
5127 g1_policy()->set_region_short_lived(hr);
5128 }
5129
5130 class NoYoungRegionsClosure: public HeapRegionClosure {
5131 private:
5132 bool _success;
5133 public:
5134 NoYoungRegionsClosure() : _success(true) { }
5135 bool doHeapRegion(HeapRegion* r) {
5136 if (r->is_young()) {
5137 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5138 r->bottom(), r->end());
5139 _success = false;
5140 }
5141 return false;
5142 }
5143 bool success() { return _success; }
5144 };
5145
5146 bool G1CollectedHeap::check_young_list_empty(bool ignore_scan_only_list,
5147 bool check_sample) {
5148 bool ret = true;
5149
5150 ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample);
5151 if (!ignore_scan_only_list) {
5152 NoYoungRegionsClosure closure;
5153 heap_region_iterate(&closure);
5154 ret = ret && closure.success();
5155 }
5156
5157 return ret;
5158 }
5159
5160 void G1CollectedHeap::empty_young_list() {
5161 assert(heap_lock_held_for_gc(),
5162 "the heap lock should already be held by or for this thread");
5163 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
5164
5165 _young_list->empty_list();
5166 }
5167
5168 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
5169 bool no_allocs = true;
5170 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
5171 HeapRegion* r = _gc_alloc_regions[ap];
5172 no_allocs = r == NULL || r->saved_mark_at_top();
5173 }
5174 return no_allocs;
5175 }
5176
5177 void G1CollectedHeap::retire_all_alloc_regions() {
5178 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
5179 HeapRegion* r = _gc_alloc_regions[ap];
5180 if (r != NULL) {
5181 // Check for aliases.
5182 bool has_processed_alias = false;
5183 for (int i = 0; i < ap; ++i) {
5184 if (_gc_alloc_regions[i] == r) {
5185 has_processed_alias = true;
5186 break;
5187 }
5188 }
5189 if (!has_processed_alias) {
5190 retire_alloc_region(r, false /* par */);
5191 }
5192 }
5193 }
5194 }
5195
5196
5197 // Done at the start of full GC.
5198 void G1CollectedHeap::tear_down_region_lists() {
5199 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5200 while (pop_unclean_region_list_locked() != NULL) ;
5201 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
5202 "Postconditions of loop.")
5203 while (pop_free_region_list_locked() != NULL) ;
5204 assert(_free_region_list == NULL, "Postcondition of loop.");
5205 if (_free_region_list_size != 0) {
5206 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
5207 print();
5208 }
5209 assert(_free_region_list_size == 0, "Postconditions of loop.");
5210 }
5211
5212
5213 class RegionResetter: public HeapRegionClosure {
5214 G1CollectedHeap* _g1;
5215 int _n;
5216 public:
5217 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5218 bool doHeapRegion(HeapRegion* r) {
5219 if (r->continuesHumongous()) return false;
5220 if (r->top() > r->bottom()) {
5221 if (r->top() < r->end()) {
5222 Copy::fill_to_words(r->top(),
5223 pointer_delta(r->end(), r->top()));
5224 }
5225 r->set_zero_fill_allocated();
5226 } else {
5227 assert(r->is_empty(), "tautology");
5228 if (r->popular()) {
5229 if (r->zero_fill_state() != HeapRegion::Allocated) {
5230 r->ensure_zero_filled_locked();
5231 r->set_zero_fill_allocated();
5232 }
5233 } else {
5234 _n++;
5235 switch (r->zero_fill_state()) {
5236 case HeapRegion::NotZeroFilled:
5237 case HeapRegion::ZeroFilling:
5238 _g1->put_region_on_unclean_list_locked(r);
5239 break;
5240 case HeapRegion::Allocated:
5241 r->set_zero_fill_complete();
5242 // no break; go on to put on free list.
5243 case HeapRegion::ZeroFilled:
5244 _g1->put_free_region_on_list_locked(r);
5245 break;
5246 }
5247 }
5248 }
5249 return false;
5250 }
5251
5252 int getFreeRegionCount() {return _n;}
5253 };
5254
5255 // Done at the end of full GC.
5256 void G1CollectedHeap::rebuild_region_lists() {
5257 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5258 // This needs to go at the end of the full GC.
5259 RegionResetter rs;
5260 heap_region_iterate(&rs);
5261 _free_regions = rs.getFreeRegionCount();
5262 // Tell the ZF thread it may have work to do.
5263 if (should_zf()) ZF_mon->notify_all();
5264 }
5265
5266 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
5267 G1CollectedHeap* _g1;
5268 int _n;
5269 public:
5270 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5271 bool doHeapRegion(HeapRegion* r) {
5272 if (r->continuesHumongous()) return false;
5273 if (r->top() > r->bottom()) {
5274 // There are assertions in "set_zero_fill_needed()" below that
5275 // require top() == bottom(), so this is technically illegal.
5276 // We'll skirt the law here, by making that true temporarily.
5277 DEBUG_ONLY(HeapWord* save_top = r->top();
5278 r->set_top(r->bottom()));
5279 r->set_zero_fill_needed();
5280 DEBUG_ONLY(r->set_top(save_top));
5281 }
5282 return false;
5283 }
5284 };
5285
5286 // Done at the start of full GC.
5287 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
5288 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5289 // This needs to go at the end of the full GC.
5290 UsedRegionsNeedZeroFillSetter rs;
5291 heap_region_iterate(&rs);
5292 }
5293
5294 class CountObjClosure: public ObjectClosure {
5295 size_t _n;
5296 public:
5297 CountObjClosure() : _n(0) {}
5298 void do_object(oop obj) { _n++; }
5299 size_t n() { return _n; }
5300 };
5301
5302 size_t G1CollectedHeap::pop_object_used_objs() {
5303 size_t sum_objs = 0;
5304 for (int i = 0; i < G1NumPopularRegions; i++) {
5305 CountObjClosure cl;
5306 _hrs->at(i)->object_iterate(&cl);
5307 sum_objs += cl.n();
5308 }
5309 return sum_objs;
5310 }
5311
5312 size_t G1CollectedHeap::pop_object_used_bytes() {
5313 size_t sum_bytes = 0;
5314 for (int i = 0; i < G1NumPopularRegions; i++) {
5315 sum_bytes += _hrs->at(i)->used();
5316 }
5317 return sum_bytes;
5318 }
5319
5320
5321 static int nq = 0;
5322
5323 HeapWord* G1CollectedHeap::allocate_popular_object(size_t word_size) {
5324 while (_cur_pop_hr_index < G1NumPopularRegions) {
5325 HeapRegion* cur_pop_region = _hrs->at(_cur_pop_hr_index);
5326 HeapWord* res = cur_pop_region->allocate(word_size);
5327 if (res != NULL) {
5328 // We account for popular objs directly in the used summary:
5329 _summary_bytes_used += (word_size * HeapWordSize);
5330 return res;
5331 }
5332 // Otherwise, try the next region (first making sure that we remember
5333 // the last "top" value as the "next_top_at_mark_start", so that
5334 // objects made popular during markings aren't automatically considered
5335 // live).
5336 cur_pop_region->note_end_of_copying();
5337 // Otherwise, try the next region.
5338 _cur_pop_hr_index++;
5339 }
5340 // XXX: For now !!!
5341 vm_exit_out_of_memory(word_size,
5342 "Not enough pop obj space (To Be Fixed)");
5343 return NULL;
5344 }
5345
5346 class HeapRegionList: public CHeapObj {
5347 public:
5348 HeapRegion* hr;
5349 HeapRegionList* next;
5350 };
5351
5352 void G1CollectedHeap::schedule_popular_region_evac(HeapRegion* r) {
5353 // This might happen during parallel GC, so protect by this lock.
5354 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
5355 // We don't schedule regions whose evacuations are already pending, or
5356 // are already being evacuated.
5357 if (!r->popular_pending() && !r->in_collection_set()) {
5358 r->set_popular_pending(true);
5359 if (G1TracePopularity) {
5360 gclog_or_tty->print_cr("Scheduling region "PTR_FORMAT" "
5361 "["PTR_FORMAT", "PTR_FORMAT") for pop-object evacuation.",
5362 r, r->bottom(), r->end());
5363 }
5364 HeapRegionList* hrl = new HeapRegionList;
5365 hrl->hr = r;
5366 hrl->next = _popular_regions_to_be_evacuated;
5367 _popular_regions_to_be_evacuated = hrl;
5368 }
5369 }
5370
5371 HeapRegion* G1CollectedHeap::popular_region_to_evac() {
5372 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
5373 HeapRegion* res = NULL;
5374 while (_popular_regions_to_be_evacuated != NULL && res == NULL) {
5375 HeapRegionList* hrl = _popular_regions_to_be_evacuated;
5376 _popular_regions_to_be_evacuated = hrl->next;
5377 res = hrl->hr;
5378 // The G1RSPopLimit may have increased, so recheck here...
5379 if (res->rem_set()->occupied() < (size_t) G1RSPopLimit) {
5380 // Hah: don't need to schedule.
5381 if (G1TracePopularity) {
5382 gclog_or_tty->print_cr("Unscheduling region "PTR_FORMAT" "
5383 "["PTR_FORMAT", "PTR_FORMAT") "
5384 "for pop-object evacuation (size %d < limit %d)",
5385 res, res->bottom(), res->end(),
5386 res->rem_set()->occupied(), G1RSPopLimit);
5387 }
5388 res->set_popular_pending(false);
5389 res = NULL;
5390 }
5391 // We do not reset res->popular() here; if we did so, it would allow
5392 // the region to be "rescheduled" for popularity evacuation. Instead,
5393 // this is done in the collection pause, with the world stopped.
5394 // So the invariant is that the regions in the list have the popularity
5395 // boolean set, but having the boolean set does not imply membership
5396 // on the list (though there can at most one such pop-pending region
5397 // not on the list at any time).
5398 delete hrl;
5399 }
5400 return res;
5401 }
5402
5403 void G1CollectedHeap::evac_popular_region(HeapRegion* hr) {
5404 while (true) {
5405 // Don't want to do a GC pause while cleanup is being completed!
5406 wait_for_cleanup_complete();
5407
5408 // Read the GC count while holding the Heap_lock
5409 int gc_count_before = SharedHeap::heap()->total_collections();
5410 g1_policy()->record_stop_world_start();
5411
5412 {
5413 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
5414 VM_G1PopRegionCollectionPause op(gc_count_before, hr);
5415 VMThread::execute(&op);
5416
5417 // If the prolog succeeded, we didn't do a GC for this.
5418 if (op.prologue_succeeded()) break;
5419 }
5420 // Otherwise we didn't. We should recheck the size, though, since
5421 // the limit may have increased...
5422 if (hr->rem_set()->occupied() < (size_t) G1RSPopLimit) {
5423 hr->set_popular_pending(false);
5424 break;
5425 }
5426 }
5427 }
5428
5429 void G1CollectedHeap::atomic_inc_obj_rc(oop obj) {
5430 Atomic::inc(obj_rc_addr(obj));
5431 }
5432
5433 class CountRCClosure: public OopsInHeapRegionClosure {
5434 G1CollectedHeap* _g1h;
5435 bool _parallel;
5436 public:
5437 CountRCClosure(G1CollectedHeap* g1h) :
5438 _g1h(g1h), _parallel(ParallelGCThreads > 0)
5439 {}
5440 void do_oop(narrowOop* p) {
5441 guarantee(false, "NYI");
5442 }
5443 void do_oop(oop* p) {
5444 oop obj = *p;
5445 assert(obj != NULL, "Precondition.");
5446 if (_parallel) {
5447 // We go sticky at the limit to avoid excess contention.
5448 // If we want to track the actual RC's further, we'll need to keep a
5449 // per-thread hash table or something for the popular objects.
5450 if (_g1h->obj_rc(obj) < G1ObjPopLimit) {
5451 _g1h->atomic_inc_obj_rc(obj);
5452 }
5453 } else {
5454 _g1h->inc_obj_rc(obj);
5455 }
5456 }
5457 };
5458
5459 class EvacPopObjClosure: public ObjectClosure {
5460 G1CollectedHeap* _g1h;
5461 size_t _pop_objs;
5462 size_t _max_rc;
5463 public:
5464 EvacPopObjClosure(G1CollectedHeap* g1h) :
5465 _g1h(g1h), _pop_objs(0), _max_rc(0) {}
5466
5467 void do_object(oop obj) {
5468 size_t rc = _g1h->obj_rc(obj);
5469 _max_rc = MAX2(rc, _max_rc);
5470 if (rc >= (size_t) G1ObjPopLimit) {
5471 _g1h->_pop_obj_rc_at_copy.add((double)rc);
5472 size_t word_sz = obj->size();
5473 HeapWord* new_pop_loc = _g1h->allocate_popular_object(word_sz);
5474 oop new_pop_obj = (oop)new_pop_loc;
5475 Copy::aligned_disjoint_words((HeapWord*)obj, new_pop_loc, word_sz);
5476 obj->forward_to(new_pop_obj);
5477 G1ScanAndBalanceClosure scan_and_balance(_g1h);
5478 new_pop_obj->oop_iterate_backwards(&scan_and_balance);
5479 // preserve "next" mark bit if marking is in progress.
5480 if (_g1h->mark_in_progress() && !_g1h->is_obj_ill(obj)) {
5481 _g1h->concurrent_mark()->markAndGrayObjectIfNecessary(new_pop_obj);
5482 }
5483
5484 if (G1TracePopularity) {
5485 gclog_or_tty->print_cr("Found obj " PTR_FORMAT " of word size " SIZE_FORMAT
5486 " pop (%d), move to " PTR_FORMAT,
5487 (void*) obj, word_sz,
5488 _g1h->obj_rc(obj), (void*) new_pop_obj);
5489 }
5490 _pop_objs++;
5491 }
5492 }
5493 size_t pop_objs() { return _pop_objs; }
5494 size_t max_rc() { return _max_rc; }
5495 };
5496
5497 class G1ParCountRCTask : public AbstractGangTask {
5498 G1CollectedHeap* _g1h;
5499 BitMap _bm;
5500
5501 size_t getNCards() {
5502 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
5503 / G1BlockOffsetSharedArray::N_bytes;
5504 }
5505 CountRCClosure _count_rc_closure;
5506 public:
5507 G1ParCountRCTask(G1CollectedHeap* g1h) :
5508 AbstractGangTask("G1 Par RC Count task"),
5509 _g1h(g1h), _bm(getNCards()), _count_rc_closure(g1h)
5510 {}
5511
5512 void work(int i) {
5513 ResourceMark rm;
5514 HandleMark hm;
5515 _g1h->g1_rem_set()->oops_into_collection_set_do(&_count_rc_closure, i);
5516 }
5517 };
5518
5519 void G1CollectedHeap::popularity_pause_preamble(HeapRegion* popular_region) {
5520 // We're evacuating a single region (for popularity).
5521 if (G1TracePopularity) {
5522 gclog_or_tty->print_cr("Doing pop region pause for ["PTR_FORMAT", "PTR_FORMAT")",
5523 popular_region->bottom(), popular_region->end());
5524 }
5525 g1_policy()->set_single_region_collection_set(popular_region);
5526 size_t max_rc;
5527 if (!compute_reference_counts_and_evac_popular(popular_region,
5528 &max_rc)) {
5529 // We didn't evacuate any popular objects.
5530 // We increase the RS popularity limit, to prevent this from
5531 // happening in the future.
5532 if (G1RSPopLimit < (1 << 30)) {
5533 G1RSPopLimit *= 2;
5534 }
5535 // For now, interesting enough for a message:
5536 #if 1
5537 gclog_or_tty->print_cr("In pop region pause for ["PTR_FORMAT", "PTR_FORMAT"), "
5538 "failed to find a pop object (max = %d).",
5539 popular_region->bottom(), popular_region->end(),
5540 max_rc);
5541 gclog_or_tty->print_cr("Increased G1RSPopLimit to %d.", G1RSPopLimit);
5542 #endif // 0
5543 // Also, we reset the collection set to NULL, to make the rest of
5544 // the collection do nothing.
5545 assert(popular_region->next_in_collection_set() == NULL,
5546 "should be single-region.");
5547 popular_region->set_in_collection_set(false);
5548 popular_region->set_popular_pending(false);
5549 g1_policy()->clear_collection_set();
5550 }
5551 }
5552
5553 bool G1CollectedHeap::
5554 compute_reference_counts_and_evac_popular(HeapRegion* popular_region,
5555 size_t* max_rc) {
5556 HeapWord* rc_region_bot;
5557 HeapWord* rc_region_end;
5558
5559 // Set up the reference count region.
5560 HeapRegion* rc_region = newAllocRegion(HeapRegion::GrainWords);
5561 if (rc_region != NULL) {
5562 rc_region_bot = rc_region->bottom();
5563 rc_region_end = rc_region->end();
5564 } else {
5565 rc_region_bot = NEW_C_HEAP_ARRAY(HeapWord, HeapRegion::GrainWords);
5566 if (rc_region_bot == NULL) {
5567 vm_exit_out_of_memory(HeapRegion::GrainWords,
5568 "No space for RC region.");
5569 }
5570 rc_region_end = rc_region_bot + HeapRegion::GrainWords;
5571 }
5572
5573 if (G1TracePopularity)
5574 gclog_or_tty->print_cr("RC region is ["PTR_FORMAT", "PTR_FORMAT")",
5575 rc_region_bot, rc_region_end);
5576 if (rc_region_bot > popular_region->bottom()) {
5577 _rc_region_above = true;
5578 _rc_region_diff =
5579 pointer_delta(rc_region_bot, popular_region->bottom(), 1);
5580 } else {
5581 assert(rc_region_bot < popular_region->bottom(), "Can't be equal.");
5582 _rc_region_above = false;
5583 _rc_region_diff =
5584 pointer_delta(popular_region->bottom(), rc_region_bot, 1);
5585 }
5586 g1_policy()->record_pop_compute_rc_start();
5587 // Count external references.
5588 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5589 if (ParallelGCThreads > 0) {
5590
5591 set_par_threads(workers()->total_workers());
5592 G1ParCountRCTask par_count_rc_task(this);
5593 workers()->run_task(&par_count_rc_task);
5594 set_par_threads(0);
5595
5596 } else {
5597 CountRCClosure count_rc_closure(this);
5598 g1_rem_set()->oops_into_collection_set_do(&count_rc_closure, 0);
5599 }
5600 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5601 g1_policy()->record_pop_compute_rc_end();
5602
5603 // Now evacuate popular objects.
5604 g1_policy()->record_pop_evac_start();
5605 EvacPopObjClosure evac_pop_obj_cl(this);
5606 popular_region->object_iterate(&evac_pop_obj_cl);
5607 *max_rc = evac_pop_obj_cl.max_rc();
5608
5609 // Make sure the last "top" value of the current popular region is copied
5610 // as the "next_top_at_mark_start", so that objects made popular during
5611 // markings aren't automatically considered live.
5612 HeapRegion* cur_pop_region = _hrs->at(_cur_pop_hr_index);
5613 cur_pop_region->note_end_of_copying();
5614
5615 if (rc_region != NULL) {
5616 free_region(rc_region);
5617 } else {
5618 FREE_C_HEAP_ARRAY(HeapWord, rc_region_bot);
5619 }
5620 g1_policy()->record_pop_evac_end();
5621
5622 return evac_pop_obj_cl.pop_objs() > 0;
5623 }
5624
5625 class CountPopObjInfoClosure: public HeapRegionClosure {
5626 size_t _objs;
5627 size_t _bytes;
5628
5629 class CountObjClosure: public ObjectClosure {
5630 int _n;
5631 public:
5632 CountObjClosure() : _n(0) {}
5633 void do_object(oop obj) { _n++; }
5634 size_t n() { return _n; }
5635 };
5636
5637 public:
5638 CountPopObjInfoClosure() : _objs(0), _bytes(0) {}
5639 bool doHeapRegion(HeapRegion* r) {
5640 _bytes += r->used();
5641 CountObjClosure blk;
5642 r->object_iterate(&blk);
5643 _objs += blk.n();
5644 return false;
5645 }
5646 size_t objs() { return _objs; }
5647 size_t bytes() { return _bytes; }
5648 };
5649
5650
5651 void G1CollectedHeap::print_popularity_summary_info() const {
5652 CountPopObjInfoClosure blk;
5653 for (int i = 0; i <= _cur_pop_hr_index; i++) {
5654 blk.doHeapRegion(_hrs->at(i));
5655 }
5656 gclog_or_tty->print_cr("\nPopular objects: %d objs, %d bytes.",
5657 blk.objs(), blk.bytes());
5658 gclog_or_tty->print_cr(" RC at copy = [avg = %5.2f, max = %5.2f, sd = %5.2f].",
5659 _pop_obj_rc_at_copy.avg(),
5660 _pop_obj_rc_at_copy.maximum(),
5661 _pop_obj_rc_at_copy.sd());
5662 }
5663
5664 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5665 _refine_cte_cl->set_concurrent(concurrent);
5666 }
5667
5668 #ifndef PRODUCT
5669
5670 class PrintHeapRegionClosure: public HeapRegionClosure {
5671 public:
5672 bool doHeapRegion(HeapRegion *r) {
5673 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
5674 if (r != NULL) {
5675 if (r->is_on_free_list())
5676 gclog_or_tty->print("Free ");
5677 if (r->is_young())
5678 gclog_or_tty->print("Young ");
5679 if (r->isHumongous())
5680 gclog_or_tty->print("Is Humongous ");
5681 r->print();
5682 }
5683 return false;
5684 }
5685 };
5686
5687 class SortHeapRegionClosure : public HeapRegionClosure {
5688 size_t young_regions,free_regions, unclean_regions;
5689 size_t hum_regions, count;
5690 size_t unaccounted, cur_unclean, cur_alloc;
5691 size_t total_free;
5692 HeapRegion* cur;
5693 public:
5694 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5695 free_regions(0), unclean_regions(0),
5696 hum_regions(0),
5697 count(0), unaccounted(0),
5698 cur_alloc(0), total_free(0)
5699 {}
5700 bool doHeapRegion(HeapRegion *r) {
5701 count++;
5702 if (r->is_on_free_list()) free_regions++;
5703 else if (r->is_on_unclean_list()) unclean_regions++;
5704 else if (r->isHumongous()) hum_regions++;
5705 else if (r->is_young()) young_regions++;
5706 else if (r == cur) cur_alloc++;
5707 else unaccounted++;
5708 return false;
5709 }
5710 void print() {
5711 total_free = free_regions + unclean_regions;
5712 gclog_or_tty->print("%d regions\n", count);
5713 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5714 total_free, free_regions, unclean_regions);
5715 gclog_or_tty->print("%d humongous %d young\n",
5716 hum_regions, young_regions);
5717 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5718 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5719 }
5720 };
5721
5722 void G1CollectedHeap::print_region_counts() {
5723 SortHeapRegionClosure sc(_cur_alloc_region);
5724 PrintHeapRegionClosure cl;
5725 heap_region_iterate(&cl);
5726 heap_region_iterate(&sc);
5727 sc.print();
5728 print_region_accounting_info();
5729 };
5730
5731 bool G1CollectedHeap::regions_accounted_for() {
5732 // TODO: regions accounting for young/survivor/tenured
5733 return true;
5734 }
5735
5736 bool G1CollectedHeap::print_region_accounting_info() {
5737 gclog_or_tty->print_cr("P regions: %d.", G1NumPopularRegions);
5738 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5739 free_regions(),
5740 count_free_regions(), count_free_regions_list(),
5741 _free_region_list_size, _unclean_region_list.sz());
5742 gclog_or_tty->print_cr("cur_alloc: %d.",
5743 (_cur_alloc_region == NULL ? 0 : 1));
5744 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5745
5746 // TODO: check regions accounting for young/survivor/tenured
5747 return true;
5748 }
5749
5750 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5751 HeapRegion* hr = heap_region_containing(p);
5752 if (hr == NULL) {
5753 return is_in_permanent(p);
5754 } else {
5755 return hr->is_in(p);
5756 }
5757 }
5758 #endif // PRODUCT
5759
5760 void G1CollectedHeap::g1_unimplemented() {
5761 // Unimplemented();
5762 }
5763
5764
5765 // Local Variables: ***
5766 // c-indentation-style: gnu ***
5767 // End: ***