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