1 /*
2 * Copyright 2001-2007 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 YoungList::YoungList(G1CollectedHeap* g1h)
140 : _g1h(g1h), _head(NULL),
141 _scan_only_head(NULL), _scan_only_tail(NULL), _curr_scan_only(NULL),
142 _length(0), _scan_only_length(0),
143 _last_sampled_rs_lengths(0),
144 _survivor_head(NULL), _survivors_tail(NULL), _survivor_length(0)
145 {
146 guarantee( check_list_empty(false), "just making sure..." );
147 }
148
149 void YoungList::push_region(HeapRegion *hr) {
150 assert(!hr->is_young(), "should not already be young");
151 assert(hr->get_next_young_region() == NULL, "cause it should!");
152
153 hr->set_next_young_region(_head);
154 _head = hr;
155
156 hr->set_young();
157 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
158 ++_length;
159 }
160
161 void YoungList::add_survivor_region(HeapRegion* hr) {
162 assert(!hr->is_survivor(), "should not already be for survived");
163 assert(hr->get_next_young_region() == NULL, "cause it should!");
164
165 hr->set_next_young_region(_survivor_head);
166 if (_survivor_head == NULL) {
167 _survivors_tail = hr;
168 }
169 _survivor_head = hr;
170
171 hr->set_survivor();
172 ++_survivor_length;
173 }
174
175 HeapRegion* YoungList::pop_region() {
176 while (_head != NULL) {
177 assert( length() > 0, "list should not be empty" );
178 HeapRegion* ret = _head;
179 _head = ret->get_next_young_region();
180 ret->set_next_young_region(NULL);
181 --_length;
182 assert(ret->is_young(), "region should be very young");
183
184 // Replace 'Survivor' region type with 'Young'. So the region will
185 // be treated as a young region and will not be 'confused' with
186 // newly created survivor regions.
187 if (ret->is_survivor()) {
188 ret->set_young();
189 }
190
191 if (!ret->is_scan_only()) {
192 return ret;
193 }
194
195 // scan-only, we'll add it to the scan-only list
196 if (_scan_only_tail == NULL) {
197 guarantee( _scan_only_head == NULL, "invariant" );
198
199 _scan_only_head = ret;
200 _curr_scan_only = ret;
201 } else {
202 guarantee( _scan_only_head != NULL, "invariant" );
203 _scan_only_tail->set_next_young_region(ret);
204 }
205 guarantee( ret->get_next_young_region() == NULL, "invariant" );
206 _scan_only_tail = ret;
207
208 // no need to be tagged as scan-only any more
209 ret->set_young();
210
211 ++_scan_only_length;
212 }
213 assert( length() == 0, "list should be empty" );
214 return NULL;
215 }
216
217 void YoungList::empty_list(HeapRegion* list) {
218 while (list != NULL) {
219 HeapRegion* next = list->get_next_young_region();
220 list->set_next_young_region(NULL);
221 list->uninstall_surv_rate_group();
222 list->set_not_young();
223 list = next;
224 }
225 }
226
227 void YoungList::empty_list() {
228 assert(check_list_well_formed(), "young list should be well formed");
229
230 empty_list(_head);
231 _head = NULL;
232 _length = 0;
233
234 empty_list(_scan_only_head);
235 _scan_only_head = NULL;
236 _scan_only_tail = NULL;
237 _scan_only_length = 0;
238 _curr_scan_only = NULL;
239
240 empty_list(_survivor_head);
241 _survivor_head = NULL;
242 _survivors_tail = NULL;
243 _survivor_length = 0;
244
245 _last_sampled_rs_lengths = 0;
246
247 assert(check_list_empty(false), "just making sure...");
248 }
249
250 bool YoungList::check_list_well_formed() {
251 bool ret = true;
252
253 size_t length = 0;
254 HeapRegion* curr = _head;
255 HeapRegion* last = NULL;
256 while (curr != NULL) {
257 if (!curr->is_young() || curr->is_scan_only()) {
258 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
259 "incorrectly tagged (%d, %d)",
260 curr->bottom(), curr->end(),
261 curr->is_young(), curr->is_scan_only());
262 ret = false;
263 }
264 ++length;
265 last = curr;
266 curr = curr->get_next_young_region();
267 }
268 ret = ret && (length == _length);
269
270 if (!ret) {
271 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
272 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
273 length, _length);
274 }
275
276 bool scan_only_ret = true;
277 length = 0;
278 curr = _scan_only_head;
279 last = NULL;
280 while (curr != NULL) {
281 if (!curr->is_young() || curr->is_scan_only()) {
282 gclog_or_tty->print_cr("### SCAN-ONLY REGION "PTR_FORMAT"-"PTR_FORMAT" "
283 "incorrectly tagged (%d, %d)",
284 curr->bottom(), curr->end(),
285 curr->is_young(), curr->is_scan_only());
286 scan_only_ret = false;
287 }
288 ++length;
289 last = curr;
290 curr = curr->get_next_young_region();
291 }
292 scan_only_ret = scan_only_ret && (length == _scan_only_length);
293
294 if ( (last != _scan_only_tail) ||
295 (_scan_only_head == NULL && _scan_only_tail != NULL) ||
296 (_scan_only_head != NULL && _scan_only_tail == NULL) ) {
297 gclog_or_tty->print_cr("## _scan_only_tail is set incorrectly");
298 scan_only_ret = false;
299 }
300
301 if (_curr_scan_only != NULL && _curr_scan_only != _scan_only_head) {
302 gclog_or_tty->print_cr("### _curr_scan_only is set incorrectly");
303 scan_only_ret = false;
304 }
305
306 if (!scan_only_ret) {
307 gclog_or_tty->print_cr("### SCAN-ONLY LIST seems not well formed!");
308 gclog_or_tty->print_cr("### list has %d entries, _scan_only_length is %d",
309 length, _scan_only_length);
310 }
311
312 return ret && scan_only_ret;
313 }
314
315 bool YoungList::check_list_empty(bool ignore_scan_only_list,
316 bool check_sample) {
317 bool ret = true;
318
319 if (_length != 0) {
320 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
321 _length);
322 ret = false;
323 }
324 if (check_sample && _last_sampled_rs_lengths != 0) {
325 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
326 ret = false;
327 }
328 if (_head != NULL) {
329 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
330 ret = false;
331 }
332 if (!ret) {
333 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
334 }
335
336 if (ignore_scan_only_list)
337 return ret;
338
339 bool scan_only_ret = true;
340 if (_scan_only_length != 0) {
341 gclog_or_tty->print_cr("### SCAN-ONLY LIST should have 0 length, not %d",
342 _scan_only_length);
343 scan_only_ret = false;
344 }
345 if (_scan_only_head != NULL) {
346 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL head");
347 scan_only_ret = false;
348 }
349 if (_scan_only_tail != NULL) {
350 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not have a NULL tail");
351 scan_only_ret = false;
352 }
353 if (!scan_only_ret) {
354 gclog_or_tty->print_cr("### SCAN-ONLY LIST does not seem empty");
355 }
356
357 return ret && scan_only_ret;
358 }
359
360 void
361 YoungList::rs_length_sampling_init() {
362 _sampled_rs_lengths = 0;
363 _curr = _head;
364 }
365
366 bool
367 YoungList::rs_length_sampling_more() {
368 return _curr != NULL;
369 }
370
371 void
372 YoungList::rs_length_sampling_next() {
373 assert( _curr != NULL, "invariant" );
374 _sampled_rs_lengths += _curr->rem_set()->occupied();
375 _curr = _curr->get_next_young_region();
376 if (_curr == NULL) {
377 _last_sampled_rs_lengths = _sampled_rs_lengths;
378 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
379 }
380 }
381
382 void
383 YoungList::reset_auxilary_lists() {
384 // We could have just "moved" the scan-only list to the young list.
385 // However, the scan-only list is ordered according to the region
386 // age in descending order, so, by moving one entry at a time, we
387 // ensure that it is recreated in ascending order.
388
389 guarantee( is_empty(), "young list should be empty" );
390 assert(check_list_well_formed(), "young list should be well formed");
391
392 // Add survivor regions to SurvRateGroup.
393 _g1h->g1_policy()->note_start_adding_survivor_regions();
394 for (HeapRegion* curr = _survivor_head;
395 curr != NULL;
396 curr = curr->get_next_young_region()) {
397 _g1h->g1_policy()->set_region_survivors(curr);
398 }
399 _g1h->g1_policy()->note_stop_adding_survivor_regions();
400
401 if (_survivor_head != NULL) {
402 _head = _survivor_head;
403 _length = _survivor_length + _scan_only_length;
404 _survivors_tail->set_next_young_region(_scan_only_head);
405 } else {
406 _head = _scan_only_head;
407 _length = _scan_only_length;
408 }
409
410 for (HeapRegion* curr = _scan_only_head;
411 curr != NULL;
412 curr = curr->get_next_young_region()) {
413 curr->recalculate_age_in_surv_rate_group();
414 }
415 _scan_only_head = NULL;
416 _scan_only_tail = NULL;
417 _scan_only_length = 0;
418 _curr_scan_only = NULL;
419
420 _survivor_head = NULL;
421 _survivors_tail = NULL;
422 _survivor_length = 0;
423 _g1h->g1_policy()->finished_recalculating_age_indexes();
424
425 assert(check_list_well_formed(), "young list should be well formed");
426 }
427
428 void YoungList::print() {
429 HeapRegion* lists[] = {_head, _scan_only_head, _survivor_head};
430 const char* names[] = {"YOUNG", "SCAN-ONLY", "SURVIVOR"};
431
432 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
433 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
434 HeapRegion *curr = lists[list];
435 if (curr == NULL)
436 gclog_or_tty->print_cr(" empty");
437 while (curr != NULL) {
438 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
439 "age: %4d, y: %d, s-o: %d, surv: %d",
440 curr->bottom(), curr->end(),
441 curr->top(),
442 curr->prev_top_at_mark_start(),
443 curr->next_top_at_mark_start(),
444 curr->top_at_conc_mark_count(),
445 curr->age_in_surv_rate_group_cond(),
446 curr->is_young(),
447 curr->is_scan_only(),
448 curr->is_survivor());
449 curr = curr->get_next_young_region();
450 }
451 }
452
453 gclog_or_tty->print_cr("");
454 }
455
456 void G1CollectedHeap::stop_conc_gc_threads() {
457 _cg1r->cg1rThread()->stop();
458 _czft->stop();
459 _cmThread->stop();
460 }
461
462
463 void G1CollectedHeap::check_ct_logs_at_safepoint() {
464 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
465 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
466
467 // Count the dirty cards at the start.
468 CountNonCleanMemRegionClosure count1(this);
469 ct_bs->mod_card_iterate(&count1);
470 int orig_count = count1.n();
471
472 // First clear the logged cards.
473 ClearLoggedCardTableEntryClosure clear;
474 dcqs.set_closure(&clear);
475 dcqs.apply_closure_to_all_completed_buffers();
476 dcqs.iterate_closure_all_threads(false);
477 clear.print_histo();
478
479 // Now ensure that there's no dirty cards.
480 CountNonCleanMemRegionClosure count2(this);
481 ct_bs->mod_card_iterate(&count2);
482 if (count2.n() != 0) {
483 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
484 count2.n(), orig_count);
485 }
486 guarantee(count2.n() == 0, "Card table should be clean.");
487
488 RedirtyLoggedCardTableEntryClosure redirty;
489 JavaThread::dirty_card_queue_set().set_closure(&redirty);
490 dcqs.apply_closure_to_all_completed_buffers();
491 dcqs.iterate_closure_all_threads(false);
492 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
493 clear.calls(), orig_count);
494 guarantee(redirty.calls() == clear.calls(),
495 "Or else mechanism is broken.");
496
497 CountNonCleanMemRegionClosure count3(this);
498 ct_bs->mod_card_iterate(&count3);
499 if (count3.n() != orig_count) {
500 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
501 orig_count, count3.n());
502 guarantee(count3.n() >= orig_count, "Should have restored them all.");
503 }
504
505 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
506 }
507
508 // Private class members.
509
510 G1CollectedHeap* G1CollectedHeap::_g1h;
511
512 // Private methods.
513
514 // Finds a HeapRegion that can be used to allocate a given size of block.
515
516
517 HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size,
518 bool do_expand,
519 bool zero_filled) {
520 ConcurrentZFThread::note_region_alloc();
521 HeapRegion* res = alloc_free_region_from_lists(zero_filled);
522 if (res == NULL && do_expand) {
523 expand(word_size * HeapWordSize);
524 res = alloc_free_region_from_lists(zero_filled);
525 assert(res == NULL ||
526 (!res->isHumongous() &&
527 (!zero_filled ||
528 res->zero_fill_state() == HeapRegion::Allocated)),
529 "Alloc Regions must be zero filled (and non-H)");
530 }
531 if (res != NULL && res->is_empty()) _free_regions--;
532 assert(res == NULL ||
533 (!res->isHumongous() &&
534 (!zero_filled ||
535 res->zero_fill_state() == HeapRegion::Allocated)),
536 "Non-young alloc Regions must be zero filled (and non-H)");
537
538 if (G1TraceRegions) {
539 if (res != NULL) {
540 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
541 "top "PTR_FORMAT,
542 res->hrs_index(), res->bottom(), res->end(), res->top());
543 }
544 }
545
546 return res;
547 }
548
549 HeapRegion* G1CollectedHeap::newAllocRegionWithExpansion(int purpose,
550 size_t word_size,
551 bool zero_filled) {
552 HeapRegion* alloc_region = NULL;
553 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
554 alloc_region = newAllocRegion_work(word_size, true, zero_filled);
555 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
556 _young_list->add_survivor_region(alloc_region);
557 }
558 ++_gc_alloc_region_counts[purpose];
559 } else {
560 g1_policy()->note_alloc_region_limit_reached(purpose);
561 }
562 return alloc_region;
563 }
564
565 // If could fit into free regions w/o expansion, try.
566 // Otherwise, if can expand, do so.
567 // Otherwise, if using ex regions might help, try with ex given back.
568 HeapWord* G1CollectedHeap::humongousObjAllocate(size_t word_size) {
569 assert(regions_accounted_for(), "Region leakage!");
570
571 // We can't allocate H regions while cleanupComplete is running, since
572 // some of the regions we find to be empty might not yet be added to the
573 // unclean list. (If we're already at a safepoint, this call is
574 // unnecessary, not to mention wrong.)
575 if (!SafepointSynchronize::is_at_safepoint())
576 wait_for_cleanup_complete();
577
578 size_t num_regions =
579 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
580
581 // Special case if < one region???
582
583 // Remember the ft size.
584 size_t x_size = expansion_regions();
585
586 HeapWord* res = NULL;
587 bool eliminated_allocated_from_lists = false;
588
589 // Can the allocation potentially fit in the free regions?
590 if (free_regions() >= num_regions) {
591 res = _hrs->obj_allocate(word_size);
592 }
593 if (res == NULL) {
594 // Try expansion.
595 size_t fs = _hrs->free_suffix();
596 if (fs + x_size >= num_regions) {
597 expand((num_regions - fs) * HeapRegion::GrainBytes);
598 res = _hrs->obj_allocate(word_size);
599 assert(res != NULL, "This should have worked.");
600 } else {
601 // Expansion won't help. Are there enough free regions if we get rid
602 // of reservations?
603 size_t avail = free_regions();
604 if (avail >= num_regions) {
605 res = _hrs->obj_allocate(word_size);
606 if (res != NULL) {
607 remove_allocated_regions_from_lists();
608 eliminated_allocated_from_lists = true;
609 }
610 }
611 }
612 }
613 if (res != NULL) {
614 // Increment by the number of regions allocated.
615 // FIXME: Assumes regions all of size GrainBytes.
616 #ifndef PRODUCT
617 mr_bs()->verify_clean_region(MemRegion(res, res + num_regions *
618 HeapRegion::GrainWords));
619 #endif
620 if (!eliminated_allocated_from_lists)
621 remove_allocated_regions_from_lists();
622 _summary_bytes_used += word_size * HeapWordSize;
623 _free_regions -= num_regions;
624 _num_humongous_regions += (int) num_regions;
625 }
626 assert(regions_accounted_for(), "Region Leakage");
627 return res;
628 }
629
630 HeapWord*
631 G1CollectedHeap::attempt_allocation_slow(size_t word_size,
632 bool permit_collection_pause) {
633 HeapWord* res = NULL;
634 HeapRegion* allocated_young_region = NULL;
635
636 assert( SafepointSynchronize::is_at_safepoint() ||
637 Heap_lock->owned_by_self(), "pre condition of the call" );
638
639 if (isHumongous(word_size)) {
640 // Allocation of a humongous object can, in a sense, complete a
641 // partial region, if the previous alloc was also humongous, and
642 // caused the test below to succeed.
643 if (permit_collection_pause)
644 do_collection_pause_if_appropriate(word_size);
645 res = humongousObjAllocate(word_size);
646 assert(_cur_alloc_region == NULL
647 || !_cur_alloc_region->isHumongous(),
648 "Prevent a regression of this bug.");
649
650 } else {
651 // We may have concurrent cleanup working at the time. Wait for it
652 // to complete. In the future we would probably want to make the
653 // concurrent cleanup truly concurrent by decoupling it from the
654 // allocation.
655 if (!SafepointSynchronize::is_at_safepoint())
656 wait_for_cleanup_complete();
657 // If we do a collection pause, this will be reset to a non-NULL
658 // value. If we don't, nulling here ensures that we allocate a new
659 // region below.
660 if (_cur_alloc_region != NULL) {
661 // We're finished with the _cur_alloc_region.
662 _summary_bytes_used += _cur_alloc_region->used();
663 _cur_alloc_region = NULL;
664 }
665 assert(_cur_alloc_region == NULL, "Invariant.");
666 // Completion of a heap region is perhaps a good point at which to do
667 // a collection pause.
668 if (permit_collection_pause)
669 do_collection_pause_if_appropriate(word_size);
670 // Make sure we have an allocation region available.
671 if (_cur_alloc_region == NULL) {
672 if (!SafepointSynchronize::is_at_safepoint())
673 wait_for_cleanup_complete();
674 bool next_is_young = should_set_young_locked();
675 // If the next region is not young, make sure it's zero-filled.
676 _cur_alloc_region = newAllocRegion(word_size, !next_is_young);
677 if (_cur_alloc_region != NULL) {
678 _summary_bytes_used -= _cur_alloc_region->used();
679 if (next_is_young) {
680 set_region_short_lived_locked(_cur_alloc_region);
681 allocated_young_region = _cur_alloc_region;
682 }
683 }
684 }
685 assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
686 "Prevent a regression of this bug.");
687
688 // Now retry the allocation.
689 if (_cur_alloc_region != NULL) {
690 res = _cur_alloc_region->allocate(word_size);
691 }
692 }
693
694 // NOTE: fails frequently in PRT
695 assert(regions_accounted_for(), "Region leakage!");
696
697 if (res != NULL) {
698 if (!SafepointSynchronize::is_at_safepoint()) {
699 assert( permit_collection_pause, "invariant" );
700 assert( Heap_lock->owned_by_self(), "invariant" );
701 Heap_lock->unlock();
702 }
703
704 if (allocated_young_region != NULL) {
705 HeapRegion* hr = allocated_young_region;
706 HeapWord* bottom = hr->bottom();
707 HeapWord* end = hr->end();
708 MemRegion mr(bottom, end);
709 ((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr);
710 }
711 }
712
713 assert( SafepointSynchronize::is_at_safepoint() ||
714 (res == NULL && Heap_lock->owned_by_self()) ||
715 (res != NULL && !Heap_lock->owned_by_self()),
716 "post condition of the call" );
717
718 return res;
719 }
720
721 HeapWord*
722 G1CollectedHeap::mem_allocate(size_t word_size,
723 bool is_noref,
724 bool is_tlab,
725 bool* gc_overhead_limit_was_exceeded) {
726 debug_only(check_for_valid_allocation_state());
727 assert(no_gc_in_progress(), "Allocation during gc not allowed");
728 HeapWord* result = NULL;
729
730 // Loop until the allocation is satisified,
731 // or unsatisfied after GC.
732 for (int try_count = 1; /* return or throw */; try_count += 1) {
733 int gc_count_before;
734 {
735 Heap_lock->lock();
736 result = attempt_allocation(word_size);
737 if (result != NULL) {
738 // attempt_allocation should have unlocked the heap lock
739 assert(is_in(result), "result not in heap");
740 return result;
741 }
742 // Read the gc count while the heap lock is held.
743 gc_count_before = SharedHeap::heap()->total_collections();
744 Heap_lock->unlock();
745 }
746
747 // Create the garbage collection operation...
748 VM_G1CollectForAllocation op(word_size,
749 gc_count_before);
750
751 // ...and get the VM thread to execute it.
752 VMThread::execute(&op);
753 if (op.prologue_succeeded()) {
754 result = op.result();
755 assert(result == NULL || is_in(result), "result not in heap");
756 return result;
757 }
758
759 // Give a warning if we seem to be looping forever.
760 if ((QueuedAllocationWarningCount > 0) &&
761 (try_count % QueuedAllocationWarningCount == 0)) {
762 warning("G1CollectedHeap::mem_allocate_work retries %d times",
763 try_count);
764 }
765 }
766 }
767
768 void G1CollectedHeap::abandon_cur_alloc_region() {
769 if (_cur_alloc_region != NULL) {
770 // We're finished with the _cur_alloc_region.
771 if (_cur_alloc_region->is_empty()) {
772 _free_regions++;
773 free_region(_cur_alloc_region);
774 } else {
775 _summary_bytes_used += _cur_alloc_region->used();
776 }
777 _cur_alloc_region = NULL;
778 }
779 }
780
781 class PostMCRemSetClearClosure: public HeapRegionClosure {
782 ModRefBarrierSet* _mr_bs;
783 public:
784 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
785 bool doHeapRegion(HeapRegion* r) {
786 r->reset_gc_time_stamp();
787 if (r->continuesHumongous())
788 return false;
789 HeapRegionRemSet* hrrs = r->rem_set();
790 if (hrrs != NULL) hrrs->clear();
791 // You might think here that we could clear just the cards
792 // corresponding to the used region. But no: if we leave a dirty card
793 // in a region we might allocate into, then it would prevent that card
794 // from being enqueued, and cause it to be missed.
795 // Re: the performance cost: we shouldn't be doing full GC anyway!
796 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
797 return false;
798 }
799 };
800
801
802 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
803 ModRefBarrierSet* _mr_bs;
804 public:
805 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
806 bool doHeapRegion(HeapRegion* r) {
807 if (r->continuesHumongous()) return false;
808 if (r->used_region().word_size() != 0) {
809 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
810 }
811 return false;
812 }
813 };
814
815 void G1CollectedHeap::do_collection(bool full, bool clear_all_soft_refs,
816 size_t word_size) {
817 ResourceMark rm;
818
819 if (full && DisableExplicitGC) {
820 gclog_or_tty->print("\n\n\nDisabling Explicit GC\n\n\n");
821 return;
822 }
823
824 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
825 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
826
827 if (GC_locker::is_active()) {
828 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
829 }
830
831 {
832 IsGCActiveMark x;
833
834 // Timing
835 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
836 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
837 TraceTime t(full ? "Full GC (System.gc())" : "Full GC", PrintGC, true, gclog_or_tty);
838
839 double start = os::elapsedTime();
840 GCOverheadReporter::recordSTWStart(start);
841 g1_policy()->record_full_collection_start();
842
843 gc_prologue(true);
844 increment_total_collections();
845
846 size_t g1h_prev_used = used();
847 assert(used() == recalculate_used(), "Should be equal");
848
849 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
850 HandleMark hm; // Discard invalid handles created during verification
851 prepare_for_verify();
852 gclog_or_tty->print(" VerifyBeforeGC:");
853 Universe::verify(true);
854 }
855 assert(regions_accounted_for(), "Region leakage!");
856
857 COMPILER2_PRESENT(DerivedPointerTable::clear());
858
859 // We want to discover references, but not process them yet.
860 // This mode is disabled in
861 // instanceRefKlass::process_discovered_references if the
862 // generation does some collection work, or
863 // instanceRefKlass::enqueue_discovered_references if the
864 // generation returns without doing any work.
865 ref_processor()->disable_discovery();
866 ref_processor()->abandon_partial_discovery();
867 ref_processor()->verify_no_references_recorded();
868
869 // Abandon current iterations of concurrent marking and concurrent
870 // refinement, if any are in progress.
871 concurrent_mark()->abort();
872
873 // Make sure we'll choose a new allocation region afterwards.
874 abandon_cur_alloc_region();
875 assert(_cur_alloc_region == NULL, "Invariant.");
876 g1_rem_set()->as_HRInto_G1RemSet()->cleanupHRRS();
877 tear_down_region_lists();
878 set_used_regions_to_need_zero_fill();
879 if (g1_policy()->in_young_gc_mode()) {
880 empty_young_list();
881 g1_policy()->set_full_young_gcs(true);
882 }
883
884 // Temporarily make reference _discovery_ single threaded (non-MT).
885 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
886
887 // Temporarily make refs discovery atomic
888 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
889
890 // Temporarily clear _is_alive_non_header
891 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
892
893 ref_processor()->enable_discovery();
894 ref_processor()->snap_policy(clear_all_soft_refs);
895
896 // Do collection work
897 {
898 HandleMark hm; // Discard invalid handles created during gc
899 G1MarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);
900 }
901 // Because freeing humongous regions may have added some unclean
902 // regions, it is necessary to tear down again before rebuilding.
903 tear_down_region_lists();
904 rebuild_region_lists();
905
906 _summary_bytes_used = recalculate_used();
907
908 ref_processor()->enqueue_discovered_references();
909
910 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
911
912 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
913 HandleMark hm; // Discard invalid handles created during verification
914 gclog_or_tty->print(" VerifyAfterGC:");
915 Universe::verify(false);
916 }
917 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
918
919 reset_gc_time_stamp();
920 // Since everything potentially moved, we will clear all remembered
921 // sets, and clear all cards. Later we will also cards in the used
922 // portion of the heap after the resizing (which could be a shrinking.)
923 // We will also reset the GC time stamps of the regions.
924 PostMCRemSetClearClosure rs_clear(mr_bs());
925 heap_region_iterate(&rs_clear);
926
927 // Resize the heap if necessary.
928 resize_if_necessary_after_full_collection(full ? 0 : word_size);
929
930 // Since everything potentially moved, we will clear all remembered
931 // sets, but also dirty all cards corresponding to used regions.
932 PostMCRemSetInvalidateClosure rs_invalidate(mr_bs());
933 heap_region_iterate(&rs_invalidate);
934 if (_cg1r->use_cache()) {
935 _cg1r->clear_and_record_card_counts();
936 _cg1r->clear_hot_cache();
937 }
938
939 if (PrintGC) {
940 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
941 }
942
943 if (true) { // FIXME
944 // Ask the permanent generation to adjust size for full collections
945 perm()->compute_new_size();
946 }
947
948 double end = os::elapsedTime();
949 GCOverheadReporter::recordSTWEnd(end);
950 g1_policy()->record_full_collection_end();
951
952 gc_epilogue(true);
953
954 // Abandon concurrent refinement. This must happen last: in the
955 // dirty-card logging system, some cards may be dirty by weak-ref
956 // processing, and may be enqueued. But the whole card table is
957 // dirtied, so this should abandon those logs, and set "do_traversal"
958 // to true.
959 concurrent_g1_refine()->set_pya_restart();
960
961 assert(regions_accounted_for(), "Region leakage!");
962 }
963
964 if (g1_policy()->in_young_gc_mode()) {
965 _young_list->reset_sampled_info();
966 assert( check_young_list_empty(false, false),
967 "young list should be empty at this point");
968 }
969 }
970
971 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
972 do_collection(true, clear_all_soft_refs, 0);
973 }
974
975 // This code is mostly copied from TenuredGeneration.
976 void
977 G1CollectedHeap::
978 resize_if_necessary_after_full_collection(size_t word_size) {
979 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
980
981 // Include the current allocation, if any, and bytes that will be
982 // pre-allocated to support collections, as "used".
983 const size_t used_after_gc = used();
984 const size_t capacity_after_gc = capacity();
985 const size_t free_after_gc = capacity_after_gc - used_after_gc;
986
987 // We don't have floating point command-line arguments
988 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100;
989 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
990 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
991 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
992
993 size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage);
994 size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage);
995
996 // Don't shrink less than the initial size.
997 minimum_desired_capacity =
998 MAX2(minimum_desired_capacity,
999 collector_policy()->initial_heap_byte_size());
1000 maximum_desired_capacity =
1001 MAX2(maximum_desired_capacity,
1002 collector_policy()->initial_heap_byte_size());
1003
1004 // We are failing here because minimum_desired_capacity is
1005 assert(used_after_gc <= minimum_desired_capacity, "sanity check");
1006 assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check");
1007
1008 if (PrintGC && Verbose) {
1009 const double free_percentage = ((double)free_after_gc) / capacity();
1010 gclog_or_tty->print_cr("Computing new size after full GC ");
1011 gclog_or_tty->print_cr(" "
1012 " minimum_free_percentage: %6.2f",
1013 minimum_free_percentage);
1014 gclog_or_tty->print_cr(" "
1015 " maximum_free_percentage: %6.2f",
1016 maximum_free_percentage);
1017 gclog_or_tty->print_cr(" "
1018 " capacity: %6.1fK"
1019 " minimum_desired_capacity: %6.1fK"
1020 " maximum_desired_capacity: %6.1fK",
1021 capacity() / (double) K,
1022 minimum_desired_capacity / (double) K,
1023 maximum_desired_capacity / (double) K);
1024 gclog_or_tty->print_cr(" "
1025 " free_after_gc : %6.1fK"
1026 " used_after_gc : %6.1fK",
1027 free_after_gc / (double) K,
1028 used_after_gc / (double) K);
1029 gclog_or_tty->print_cr(" "
1030 " free_percentage: %6.2f",
1031 free_percentage);
1032 }
1033 if (capacity() < minimum_desired_capacity) {
1034 // Don't expand unless it's significant
1035 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1036 expand(expand_bytes);
1037 if (PrintGC && Verbose) {
1038 gclog_or_tty->print_cr(" expanding:"
1039 " minimum_desired_capacity: %6.1fK"
1040 " expand_bytes: %6.1fK",
1041 minimum_desired_capacity / (double) K,
1042 expand_bytes / (double) K);
1043 }
1044
1045 // No expansion, now see if we want to shrink
1046 } else if (capacity() > maximum_desired_capacity) {
1047 // Capacity too large, compute shrinking size
1048 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1049 shrink(shrink_bytes);
1050 if (PrintGC && Verbose) {
1051 gclog_or_tty->print_cr(" "
1052 " shrinking:"
1053 " initSize: %.1fK"
1054 " maximum_desired_capacity: %.1fK",
1055 collector_policy()->initial_heap_byte_size() / (double) K,
1056 maximum_desired_capacity / (double) K);
1057 gclog_or_tty->print_cr(" "
1058 " shrink_bytes: %.1fK",
1059 shrink_bytes / (double) K);
1060 }
1061 }
1062 }
1063
1064
1065 HeapWord*
1066 G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
1067 HeapWord* result = NULL;
1068
1069 // In a G1 heap, we're supposed to keep allocation from failing by
1070 // incremental pauses. Therefore, at least for now, we'll favor
1071 // expansion over collection. (This might change in the future if we can
1072 // do something smarter than full collection to satisfy a failed alloc.)
1073
1074 result = expand_and_allocate(word_size);
1075 if (result != NULL) {
1076 assert(is_in(result), "result not in heap");
1077 return result;
1078 }
1079
1080 // OK, I guess we have to try collection.
1081
1082 do_collection(false, false, word_size);
1083
1084 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1085
1086 if (result != NULL) {
1087 assert(is_in(result), "result not in heap");
1088 return result;
1089 }
1090
1091 // Try collecting soft references.
1092 do_collection(false, true, word_size);
1093 result = attempt_allocation(word_size, /*permit_collection_pause*/false);
1094 if (result != NULL) {
1095 assert(is_in(result), "result not in heap");
1096 return result;
1097 }
1098
1099 // What else? We might try synchronous finalization later. If the total
1100 // space available is large enough for the allocation, then a more
1101 // complete compaction phase than we've tried so far might be
1102 // appropriate.
1103 return NULL;
1104 }
1105
1106 // Attempting to expand the heap sufficiently
1107 // to support an allocation of the given "word_size". If
1108 // successful, perform the allocation and return the address of the
1109 // allocated block, or else "NULL".
1110
1111 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1112 size_t expand_bytes = word_size * HeapWordSize;
1113 if (expand_bytes < MinHeapDeltaBytes) {
1114 expand_bytes = MinHeapDeltaBytes;
1115 }
1116 expand(expand_bytes);
1117 assert(regions_accounted_for(), "Region leakage!");
1118 HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
1119 return result;
1120 }
1121
1122 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
1123 size_t pre_used = 0;
1124 size_t cleared_h_regions = 0;
1125 size_t freed_regions = 0;
1126 UncleanRegionList local_list;
1127 free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
1128 freed_regions, &local_list);
1129
1130 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
1131 &local_list);
1132 return pre_used;
1133 }
1134
1135 void
1136 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
1137 size_t& pre_used,
1138 size_t& cleared_h,
1139 size_t& freed_regions,
1140 UncleanRegionList* list,
1141 bool par) {
1142 assert(!hr->continuesHumongous(), "should have filtered these out");
1143 size_t res = 0;
1144 if (!hr->popular() && hr->used() > 0 && hr->garbage_bytes() == hr->used()) {
1145 if (!hr->is_young()) {
1146 if (G1PolicyVerbose > 0)
1147 gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
1148 " during cleanup", hr, hr->used());
1149 free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
1150 }
1151 }
1152 }
1153
1154 // FIXME: both this and shrink could probably be more efficient by
1155 // doing one "VirtualSpace::expand_by" call rather than several.
1156 void G1CollectedHeap::expand(size_t expand_bytes) {
1157 size_t old_mem_size = _g1_storage.committed_size();
1158 // We expand by a minimum of 1K.
1159 expand_bytes = MAX2(expand_bytes, (size_t)K);
1160 size_t aligned_expand_bytes =
1161 ReservedSpace::page_align_size_up(expand_bytes);
1162 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1163 HeapRegion::GrainBytes);
1164 expand_bytes = aligned_expand_bytes;
1165 while (expand_bytes > 0) {
1166 HeapWord* base = (HeapWord*)_g1_storage.high();
1167 // Commit more storage.
1168 bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
1169 if (!successful) {
1170 expand_bytes = 0;
1171 } else {
1172 expand_bytes -= HeapRegion::GrainBytes;
1173 // Expand the committed region.
1174 HeapWord* high = (HeapWord*) _g1_storage.high();
1175 _g1_committed.set_end(high);
1176 // Create a new HeapRegion.
1177 MemRegion mr(base, high);
1178 bool is_zeroed = !_g1_max_committed.contains(base);
1179 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1180
1181 // Now update max_committed if necessary.
1182 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
1183
1184 // Add it to the HeapRegionSeq.
1185 _hrs->insert(hr);
1186 // Set the zero-fill state, according to whether it's already
1187 // zeroed.
1188 {
1189 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
1190 if (is_zeroed) {
1191 hr->set_zero_fill_complete();
1192 put_free_region_on_list_locked(hr);
1193 } else {
1194 hr->set_zero_fill_needed();
1195 put_region_on_unclean_list_locked(hr);
1196 }
1197 }
1198 _free_regions++;
1199 // And we used up an expansion region to create it.
1200 _expansion_regions--;
1201 // Tell the cardtable about it.
1202 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1203 // And the offset table as well.
1204 _bot_shared->resize(_g1_committed.word_size());
1205 }
1206 }
1207 if (Verbose && PrintGC) {
1208 size_t new_mem_size = _g1_storage.committed_size();
1209 gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
1210 old_mem_size/K, aligned_expand_bytes/K,
1211 new_mem_size/K);
1212 }
1213 }
1214
1215 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1216 {
1217 size_t old_mem_size = _g1_storage.committed_size();
1218 size_t aligned_shrink_bytes =
1219 ReservedSpace::page_align_size_down(shrink_bytes);
1220 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1221 HeapRegion::GrainBytes);
1222 size_t num_regions_deleted = 0;
1223 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1224
1225 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1226 if (mr.byte_size() > 0)
1227 _g1_storage.shrink_by(mr.byte_size());
1228 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1229
1230 _g1_committed.set_end(mr.start());
1231 _free_regions -= num_regions_deleted;
1232 _expansion_regions += num_regions_deleted;
1233
1234 // Tell the cardtable about it.
1235 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1236
1237 // And the offset table as well.
1238 _bot_shared->resize(_g1_committed.word_size());
1239
1240 HeapRegionRemSet::shrink_heap(n_regions());
1241
1242 if (Verbose && PrintGC) {
1243 size_t new_mem_size = _g1_storage.committed_size();
1244 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1245 old_mem_size/K, aligned_shrink_bytes/K,
1246 new_mem_size/K);
1247 }
1248 }
1249
1250 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1251 release_gc_alloc_regions();
1252 tear_down_region_lists(); // We will rebuild them in a moment.
1253 shrink_helper(shrink_bytes);
1254 rebuild_region_lists();
1255 }
1256
1257 // Public methods.
1258
1259 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1260 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1261 #endif // _MSC_VER
1262
1263
1264 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1265 SharedHeap(policy_),
1266 _g1_policy(policy_),
1267 _ref_processor(NULL),
1268 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1269 _bot_shared(NULL),
1270 _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
1271 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1272 _evac_failure_scan_stack(NULL) ,
1273 _mark_in_progress(false),
1274 _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
1275 _cur_alloc_region(NULL),
1276 _refine_cte_cl(NULL),
1277 _free_region_list(NULL), _free_region_list_size(0),
1278 _free_regions(0),
1279 _popular_object_boundary(NULL),
1280 _cur_pop_hr_index(0),
1281 _popular_regions_to_be_evacuated(NULL),
1282 _pop_obj_rc_at_copy(),
1283 _full_collection(false),
1284 _unclean_region_list(),
1285 _unclean_regions_coming(false),
1286 _young_list(new YoungList(this)),
1287 _gc_time_stamp(0),
1288 _surviving_young_words(NULL)
1289 {
1290 _g1h = this; // To catch bugs.
1291 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1292 vm_exit_during_initialization("Failed necessary allocation.");
1293 }
1294 int n_queues = MAX2((int)ParallelGCThreads, 1);
1295 _task_queues = new RefToScanQueueSet(n_queues);
1296
1297 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1298 assert(n_rem_sets > 0, "Invariant.");
1299
1300 HeapRegionRemSetIterator** iter_arr =
1301 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1302 for (int i = 0; i < n_queues; i++) {
1303 iter_arr[i] = new HeapRegionRemSetIterator();
1304 }
1305 _rem_set_iterator = iter_arr;
1306
1307 for (int i = 0; i < n_queues; i++) {
1308 RefToScanQueue* q = new RefToScanQueue();
1309 q->initialize();
1310 _task_queues->register_queue(i, q);
1311 }
1312
1313 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1314 _gc_alloc_regions[ap] = NULL;
1315 _gc_alloc_region_counts[ap] = 0;
1316 }
1317 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1318 }
1319
1320 jint G1CollectedHeap::initialize() {
1321 os::enable_vtime();
1322
1323 // Necessary to satisfy locking discipline assertions.
1324
1325 MutexLocker x(Heap_lock);
1326
1327 // While there are no constraints in the GC code that HeapWordSize
1328 // be any particular value, there are multiple other areas in the
1329 // system which believe this to be true (e.g. oop->object_size in some
1330 // cases incorrectly returns the size in wordSize units rather than
1331 // HeapWordSize).
1332 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1333
1334 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1335 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1336
1337 // Ensure that the sizes are properly aligned.
1338 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1339 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1340
1341 // We allocate this in any case, but only do no work if the command line
1342 // param is off.
1343 _cg1r = new ConcurrentG1Refine();
1344
1345 // Reserve the maximum.
1346 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1347 // Includes the perm-gen.
1348 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1349 HeapRegion::GrainBytes,
1350 false /*ism*/);
1351
1352 if (!heap_rs.is_reserved()) {
1353 vm_exit_during_initialization("Could not reserve enough space for object heap");
1354 return JNI_ENOMEM;
1355 }
1356
1357 // It is important to do this in a way such that concurrent readers can't
1358 // temporarily think somethings in the heap. (I've actually seen this
1359 // happen in asserts: DLD.)
1360 _reserved.set_word_size(0);
1361 _reserved.set_start((HeapWord*)heap_rs.base());
1362 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1363
1364 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1365
1366 _num_humongous_regions = 0;
1367
1368 // Create the gen rem set (and barrier set) for the entire reserved region.
1369 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1370 set_barrier_set(rem_set()->bs());
1371 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1372 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1373 } else {
1374 vm_exit_during_initialization("G1 requires a mod ref bs.");
1375 return JNI_ENOMEM;
1376 }
1377
1378 // Also create a G1 rem set.
1379 if (G1UseHRIntoRS) {
1380 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1381 _g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs());
1382 } else {
1383 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1384 return JNI_ENOMEM;
1385 }
1386 } else {
1387 _g1_rem_set = new StupidG1RemSet(this);
1388 }
1389
1390 // Carve out the G1 part of the heap.
1391
1392 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1393 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1394 g1_rs.size()/HeapWordSize);
1395 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1396
1397 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1398
1399 _g1_storage.initialize(g1_rs, 0);
1400 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1401 _g1_max_committed = _g1_committed;
1402 _hrs = new HeapRegionSeq(_expansion_regions);
1403 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1404 guarantee(_cur_alloc_region == NULL, "from constructor");
1405
1406 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1407 heap_word_size(init_byte_size));
1408
1409 _g1h = this;
1410
1411 // Create the ConcurrentMark data structure and thread.
1412 // (Must do this late, so that "max_regions" is defined.)
1413 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1414 _cmThread = _cm->cmThread();
1415
1416 // ...and the concurrent zero-fill thread, if necessary.
1417 if (G1ConcZeroFill) {
1418 _czft = new ConcurrentZFThread();
1419 }
1420
1421
1422
1423 // Allocate the popular regions; take them off free lists.
1424 size_t pop_byte_size = G1NumPopularRegions * HeapRegion::GrainBytes;
1425 expand(pop_byte_size);
1426 _popular_object_boundary =
1427 _g1_reserved.start() + (G1NumPopularRegions * HeapRegion::GrainWords);
1428 for (int i = 0; i < G1NumPopularRegions; i++) {
1429 HeapRegion* hr = newAllocRegion(HeapRegion::GrainWords);
1430 // assert(hr != NULL && hr->bottom() < _popular_object_boundary,
1431 // "Should be enough, and all should be below boundary.");
1432 hr->set_popular(true);
1433 }
1434 assert(_cur_pop_hr_index == 0, "Start allocating at the first region.");
1435
1436 // Initialize the from_card cache structure of HeapRegionRemSet.
1437 HeapRegionRemSet::init_heap(max_regions());
1438
1439 // Now expand into the rest of the initial heap size.
1440 expand(init_byte_size - pop_byte_size);
1441
1442 // Perform any initialization actions delegated to the policy.
1443 g1_policy()->init();
1444
1445 g1_policy()->note_start_of_mark_thread();
1446
1447 _refine_cte_cl =
1448 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1449 g1_rem_set(),
1450 concurrent_g1_refine());
1451 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1452
1453 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1454 SATB_Q_FL_lock,
1455 0,
1456 Shared_SATB_Q_lock);
1457 if (G1RSBarrierUseQueue) {
1458 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1459 DirtyCardQ_FL_lock,
1460 G1DirtyCardQueueMax,
1461 Shared_DirtyCardQ_lock);
1462 }
1463 // In case we're keeping closure specialization stats, initialize those
1464 // counts and that mechanism.
1465 SpecializationStats::clear();
1466
1467 _gc_alloc_region_list = NULL;
1468
1469 // Do later initialization work for concurrent refinement.
1470 _cg1r->init();
1471
1472 const char* group_names[] = { "CR", "ZF", "CM", "CL" };
1473 GCOverheadReporter::initGCOverheadReporter(4, group_names);
1474
1475 return JNI_OK;
1476 }
1477
1478 void G1CollectedHeap::ref_processing_init() {
1479 SharedHeap::ref_processing_init();
1480 MemRegion mr = reserved_region();
1481 _ref_processor = ReferenceProcessor::create_ref_processor(
1482 mr, // span
1483 false, // Reference discovery is not atomic
1484 // (though it shouldn't matter here.)
1485 true, // mt_discovery
1486 NULL, // is alive closure: need to fill this in for efficiency
1487 ParallelGCThreads,
1488 ParallelRefProcEnabled,
1489 true); // Setting next fields of discovered
1490 // lists requires a barrier.
1491 }
1492
1493 size_t G1CollectedHeap::capacity() const {
1494 return _g1_committed.byte_size();
1495 }
1496
1497 void G1CollectedHeap::iterate_dirty_card_closure(bool concurrent,
1498 int worker_i) {
1499 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1500 int n_completed_buffers = 0;
1501 while (dcqs.apply_closure_to_completed_buffer(worker_i, 0, true)) {
1502 n_completed_buffers++;
1503 }
1504 g1_policy()->record_update_rs_processed_buffers(worker_i,
1505 (double) n_completed_buffers);
1506 dcqs.clear_n_completed_buffers();
1507 // Finish up the queue...
1508 if (worker_i == 0) concurrent_g1_refine()->clean_up_cache(worker_i,
1509 g1_rem_set());
1510 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1511 }
1512
1513
1514 // Computes the sum of the storage used by the various regions.
1515
1516 size_t G1CollectedHeap::used() const {
1517 assert(Heap_lock->owner() != NULL,
1518 "Should be owned on this thread's behalf.");
1519 size_t result = _summary_bytes_used;
1520 if (_cur_alloc_region != NULL)
1521 result += _cur_alloc_region->used();
1522 return result;
1523 }
1524
1525 class SumUsedClosure: public HeapRegionClosure {
1526 size_t _used;
1527 public:
1528 SumUsedClosure() : _used(0) {}
1529 bool doHeapRegion(HeapRegion* r) {
1530 if (!r->continuesHumongous()) {
1531 _used += r->used();
1532 }
1533 return false;
1534 }
1535 size_t result() { return _used; }
1536 };
1537
1538 size_t G1CollectedHeap::recalculate_used() const {
1539 SumUsedClosure blk;
1540 _hrs->iterate(&blk);
1541 return blk.result();
1542 }
1543
1544 #ifndef PRODUCT
1545 class SumUsedRegionsClosure: public HeapRegionClosure {
1546 size_t _num;
1547 public:
1548 // _num is set to 1 to account for the popular region
1549 SumUsedRegionsClosure() : _num(G1NumPopularRegions) {}
1550 bool doHeapRegion(HeapRegion* r) {
1551 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
1552 _num += 1;
1553 }
1554 return false;
1555 }
1556 size_t result() { return _num; }
1557 };
1558
1559 size_t G1CollectedHeap::recalculate_used_regions() const {
1560 SumUsedRegionsClosure blk;
1561 _hrs->iterate(&blk);
1562 return blk.result();
1563 }
1564 #endif // PRODUCT
1565
1566 size_t G1CollectedHeap::unsafe_max_alloc() {
1567 if (_free_regions > 0) return HeapRegion::GrainBytes;
1568 // otherwise, is there space in the current allocation region?
1569
1570 // We need to store the current allocation region in a local variable
1571 // here. The problem is that this method doesn't take any locks and
1572 // there may be other threads which overwrite the current allocation
1573 // region field. attempt_allocation(), for example, sets it to NULL
1574 // and this can happen *after* the NULL check here but before the call
1575 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
1576 // to be a problem in the optimized build, since the two loads of the
1577 // current allocation region field are optimized away.
1578 HeapRegion* car = _cur_alloc_region;
1579
1580 // FIXME: should iterate over all regions?
1581 if (car == NULL) {
1582 return 0;
1583 }
1584 return car->free();
1585 }
1586
1587 void G1CollectedHeap::collect(GCCause::Cause cause) {
1588 // The caller doesn't have the Heap_lock
1589 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
1590 MutexLocker ml(Heap_lock);
1591 collect_locked(cause);
1592 }
1593
1594 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
1595 assert(Thread::current()->is_VM_thread(), "Precondition#1");
1596 assert(Heap_lock->is_locked(), "Precondition#2");
1597 GCCauseSetter gcs(this, cause);
1598 switch (cause) {
1599 case GCCause::_heap_inspection:
1600 case GCCause::_heap_dump: {
1601 HandleMark hm;
1602 do_full_collection(false); // don't clear all soft refs
1603 break;
1604 }
1605 default: // XXX FIX ME
1606 ShouldNotReachHere(); // Unexpected use of this function
1607 }
1608 }
1609
1610
1611 void G1CollectedHeap::collect_locked(GCCause::Cause cause) {
1612 // Don't want to do a GC until cleanup is completed.
1613 wait_for_cleanup_complete();
1614
1615 // Read the GC count while holding the Heap_lock
1616 int gc_count_before = SharedHeap::heap()->total_collections();
1617 {
1618 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
1619 VM_G1CollectFull op(gc_count_before, cause);
1620 VMThread::execute(&op);
1621 }
1622 }
1623
1624 bool G1CollectedHeap::is_in(const void* p) const {
1625 if (_g1_committed.contains(p)) {
1626 HeapRegion* hr = _hrs->addr_to_region(p);
1627 return hr->is_in(p);
1628 } else {
1629 return _perm_gen->as_gen()->is_in(p);
1630 }
1631 }
1632
1633 // Iteration functions.
1634
1635 // Iterates an OopClosure over all ref-containing fields of objects
1636 // within a HeapRegion.
1637
1638 class IterateOopClosureRegionClosure: public HeapRegionClosure {
1639 MemRegion _mr;
1640 OopClosure* _cl;
1641 public:
1642 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
1643 : _mr(mr), _cl(cl) {}
1644 bool doHeapRegion(HeapRegion* r) {
1645 if (! r->continuesHumongous()) {
1646 r->oop_iterate(_cl);
1647 }
1648 return false;
1649 }
1650 };
1651
1652 void G1CollectedHeap::oop_iterate(OopClosure* cl) {
1653 IterateOopClosureRegionClosure blk(_g1_committed, cl);
1654 _hrs->iterate(&blk);
1655 }
1656
1657 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) {
1658 IterateOopClosureRegionClosure blk(mr, cl);
1659 _hrs->iterate(&blk);
1660 }
1661
1662 // Iterates an ObjectClosure over all objects within a HeapRegion.
1663
1664 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1665 ObjectClosure* _cl;
1666 public:
1667 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1668 bool doHeapRegion(HeapRegion* r) {
1669 if (! r->continuesHumongous()) {
1670 r->object_iterate(_cl);
1671 }
1672 return false;
1673 }
1674 };
1675
1676 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
1677 IterateObjectClosureRegionClosure blk(cl);
1678 _hrs->iterate(&blk);
1679 }
1680
1681 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
1682 // FIXME: is this right?
1683 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
1684 }
1685
1686 // Calls a SpaceClosure on a HeapRegion.
1687
1688 class SpaceClosureRegionClosure: public HeapRegionClosure {
1689 SpaceClosure* _cl;
1690 public:
1691 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
1692 bool doHeapRegion(HeapRegion* r) {
1693 _cl->do_space(r);
1694 return false;
1695 }
1696 };
1697
1698 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
1699 SpaceClosureRegionClosure blk(cl);
1700 _hrs->iterate(&blk);
1701 }
1702
1703 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
1704 _hrs->iterate(cl);
1705 }
1706
1707 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
1708 HeapRegionClosure* cl) {
1709 _hrs->iterate_from(r, cl);
1710 }
1711
1712 void
1713 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
1714 _hrs->iterate_from(idx, cl);
1715 }
1716
1717 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
1718
1719 void
1720 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1721 int worker,
1722 jint claim_value) {
1723 const size_t regions = n_regions();
1724 const size_t worker_num = (ParallelGCThreads > 0 ? ParallelGCThreads : 1);
1725 // try to spread out the starting points of the workers
1726 const size_t start_index = regions / worker_num * (size_t) worker;
1727
1728 // each worker will actually look at all regions
1729 for (size_t count = 0; count < regions; ++count) {
1730 const size_t index = (start_index + count) % regions;
1731 assert(0 <= index && index < regions, "sanity");
1732 HeapRegion* r = region_at(index);
1733 // we'll ignore "continues humongous" regions (we'll process them
1734 // when we come across their corresponding "start humongous"
1735 // region) and regions already claimed
1736 if (r->claim_value() == claim_value || r->continuesHumongous()) {
1737 continue;
1738 }
1739 // OK, try to claim it
1740 if (r->claimHeapRegion(claim_value)) {
1741 // success!
1742 assert(!r->continuesHumongous(), "sanity");
1743 if (r->startsHumongous()) {
1744 // If the region is "starts humongous" we'll iterate over its
1745 // "continues humongous" first; in fact we'll do them
1746 // first. The order is important. In on case, calling the
1747 // closure on the "starts humongous" region might de-allocate
1748 // and clear all its "continues humongous" regions and, as a
1749 // result, we might end up processing them twice. So, we'll do
1750 // them first (notice: most closures will ignore them anyway) and
1751 // then we'll do the "starts humongous" region.
1752 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
1753 HeapRegion* chr = region_at(ch_index);
1754
1755 // if the region has already been claimed or it's not
1756 // "continues humongous" we're done
1757 if (chr->claim_value() == claim_value ||
1758 !chr->continuesHumongous()) {
1759 break;
1760 }
1761
1762 // Noone should have claimed it directly. We can given
1763 // that we claimed its "starts humongous" region.
1764 assert(chr->claim_value() != claim_value, "sanity");
1765 assert(chr->humongous_start_region() == r, "sanity");
1766
1767 if (chr->claimHeapRegion(claim_value)) {
1768 // we should always be able to claim it; noone else should
1769 // be trying to claim this region
1770
1771 bool res2 = cl->doHeapRegion(chr);
1772 assert(!res2, "Should not abort");
1773
1774 // Right now, this holds (i.e., no closure that actually
1775 // does something with "continues humongous" regions
1776 // clears them). We might have to weaken it in the future,
1777 // but let's leave these two asserts here for extra safety.
1778 assert(chr->continuesHumongous(), "should still be the case");
1779 assert(chr->humongous_start_region() == r, "sanity");
1780 } else {
1781 guarantee(false, "we should not reach here");
1782 }
1783 }
1784 }
1785
1786 assert(!r->continuesHumongous(), "sanity");
1787 bool res = cl->doHeapRegion(r);
1788 assert(!res, "Should not abort");
1789 }
1790 }
1791 }
1792
1793 class ResetClaimValuesClosure: public HeapRegionClosure {
1794 public:
1795 bool doHeapRegion(HeapRegion* r) {
1796 r->set_claim_value(HeapRegion::InitialClaimValue);
1797 return false;
1798 }
1799 };
1800
1801 void
1802 G1CollectedHeap::reset_heap_region_claim_values() {
1803 ResetClaimValuesClosure blk;
1804 heap_region_iterate(&blk);
1805 }
1806
1807 #ifdef ASSERT
1808 // This checks whether all regions in the heap have the correct claim
1809 // value. I also piggy-backed on this a check to ensure that the
1810 // humongous_start_region() information on "continues humongous"
1811 // regions is correct.
1812
1813 class CheckClaimValuesClosure : public HeapRegionClosure {
1814 private:
1815 jint _claim_value;
1816 size_t _failures;
1817 HeapRegion* _sh_region;
1818 public:
1819 CheckClaimValuesClosure(jint claim_value) :
1820 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
1821 bool doHeapRegion(HeapRegion* r) {
1822 if (r->claim_value() != _claim_value) {
1823 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1824 "claim value = %d, should be %d",
1825 r->bottom(), r->end(), r->claim_value(),
1826 _claim_value);
1827 ++_failures;
1828 }
1829 if (!r->isHumongous()) {
1830 _sh_region = NULL;
1831 } else if (r->startsHumongous()) {
1832 _sh_region = r;
1833 } else if (r->continuesHumongous()) {
1834 if (r->humongous_start_region() != _sh_region) {
1835 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
1836 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
1837 r->bottom(), r->end(),
1838 r->humongous_start_region(),
1839 _sh_region);
1840 ++_failures;
1841 }
1842 }
1843 return false;
1844 }
1845 size_t failures() {
1846 return _failures;
1847 }
1848 };
1849
1850 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
1851 CheckClaimValuesClosure cl(claim_value);
1852 heap_region_iterate(&cl);
1853 return cl.failures() == 0;
1854 }
1855 #endif // ASSERT
1856
1857 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
1858 HeapRegion* r = g1_policy()->collection_set();
1859 while (r != NULL) {
1860 HeapRegion* next = r->next_in_collection_set();
1861 if (cl->doHeapRegion(r)) {
1862 cl->incomplete();
1863 return;
1864 }
1865 r = next;
1866 }
1867 }
1868
1869 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
1870 HeapRegionClosure *cl) {
1871 assert(r->in_collection_set(),
1872 "Start region must be a member of the collection set.");
1873 HeapRegion* cur = r;
1874 while (cur != NULL) {
1875 HeapRegion* next = cur->next_in_collection_set();
1876 if (cl->doHeapRegion(cur) && false) {
1877 cl->incomplete();
1878 return;
1879 }
1880 cur = next;
1881 }
1882 cur = g1_policy()->collection_set();
1883 while (cur != r) {
1884 HeapRegion* next = cur->next_in_collection_set();
1885 if (cl->doHeapRegion(cur) && false) {
1886 cl->incomplete();
1887 return;
1888 }
1889 cur = next;
1890 }
1891 }
1892
1893 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
1894 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
1895 }
1896
1897
1898 Space* G1CollectedHeap::space_containing(const void* addr) const {
1899 Space* res = heap_region_containing(addr);
1900 if (res == NULL)
1901 res = perm_gen()->space_containing(addr);
1902 return res;
1903 }
1904
1905 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
1906 Space* sp = space_containing(addr);
1907 if (sp != NULL) {
1908 return sp->block_start(addr);
1909 }
1910 return NULL;
1911 }
1912
1913 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
1914 Space* sp = space_containing(addr);
1915 assert(sp != NULL, "block_size of address outside of heap");
1916 return sp->block_size(addr);
1917 }
1918
1919 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
1920 Space* sp = space_containing(addr);
1921 return sp->block_is_obj(addr);
1922 }
1923
1924 bool G1CollectedHeap::supports_tlab_allocation() const {
1925 return true;
1926 }
1927
1928 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
1929 return HeapRegion::GrainBytes;
1930 }
1931
1932 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
1933 // Return the remaining space in the cur alloc region, but not less than
1934 // the min TLAB size.
1935 // Also, no more than half the region size, since we can't allow tlabs to
1936 // grow big enough to accomodate humongous objects.
1937
1938 // We need to story it locally, since it might change between when we
1939 // test for NULL and when we use it later.
1940 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
1941 if (cur_alloc_space == NULL) {
1942 return HeapRegion::GrainBytes/2;
1943 } else {
1944 return MAX2(MIN2(cur_alloc_space->free(),
1945 (size_t)(HeapRegion::GrainBytes/2)),
1946 (size_t)MinTLABSize);
1947 }
1948 }
1949
1950 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
1951 bool dummy;
1952 return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
1953 }
1954
1955 bool G1CollectedHeap::allocs_are_zero_filled() {
1956 return false;
1957 }
1958
1959 size_t G1CollectedHeap::large_typearray_limit() {
1960 // FIXME
1961 return HeapRegion::GrainBytes/HeapWordSize;
1962 }
1963
1964 size_t G1CollectedHeap::max_capacity() const {
1965 return _g1_committed.byte_size();
1966 }
1967
1968 jlong G1CollectedHeap::millis_since_last_gc() {
1969 // assert(false, "NYI");
1970 return 0;
1971 }
1972
1973
1974 void G1CollectedHeap::prepare_for_verify() {
1975 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
1976 ensure_parsability(false);
1977 }
1978 g1_rem_set()->prepare_for_verify();
1979 }
1980
1981 class VerifyLivenessOopClosure: public OopClosure {
1982 G1CollectedHeap* g1h;
1983 public:
1984 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
1985 g1h = _g1h;
1986 }
1987 void do_oop(narrowOop *p) {
1988 guarantee(false, "NYI");
1989 }
1990 void do_oop(oop *p) {
1991 oop obj = *p;
1992 assert(obj == NULL || !g1h->is_obj_dead(obj),
1993 "Dead object referenced by a not dead object");
1994 }
1995 };
1996
1997 class VerifyObjsInRegionClosure: public ObjectClosure {
1998 G1CollectedHeap* _g1h;
1999 size_t _live_bytes;
2000 HeapRegion *_hr;
2001 public:
2002 VerifyObjsInRegionClosure(HeapRegion *hr) : _live_bytes(0), _hr(hr) {
2003 _g1h = G1CollectedHeap::heap();
2004 }
2005 void do_object(oop o) {
2006 VerifyLivenessOopClosure isLive(_g1h);
2007 assert(o != NULL, "Huh?");
2008 if (!_g1h->is_obj_dead(o)) {
2009 o->oop_iterate(&isLive);
2010 if (!_hr->obj_allocated_since_prev_marking(o))
2011 _live_bytes += (o->size() * HeapWordSize);
2012 }
2013 }
2014 size_t live_bytes() { return _live_bytes; }
2015 };
2016
2017 class PrintObjsInRegionClosure : public ObjectClosure {
2018 HeapRegion *_hr;
2019 G1CollectedHeap *_g1;
2020 public:
2021 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2022 _g1 = G1CollectedHeap::heap();
2023 };
2024
2025 void do_object(oop o) {
2026 if (o != NULL) {
2027 HeapWord *start = (HeapWord *) o;
2028 size_t word_sz = o->size();
2029 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2030 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2031 (void*) o, word_sz,
2032 _g1->isMarkedPrev(o),
2033 _g1->isMarkedNext(o),
2034 _hr->obj_allocated_since_prev_marking(o));
2035 HeapWord *end = start + word_sz;
2036 HeapWord *cur;
2037 int *val;
2038 for (cur = start; cur < end; cur++) {
2039 val = (int *) cur;
2040 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2041 }
2042 }
2043 }
2044 };
2045
2046 class VerifyRegionClosure: public HeapRegionClosure {
2047 public:
2048 bool _allow_dirty;
2049 bool _par;
2050 VerifyRegionClosure(bool allow_dirty, bool par = false)
2051 : _allow_dirty(allow_dirty), _par(par) {}
2052 bool doHeapRegion(HeapRegion* r) {
2053 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2054 "Should be unclaimed at verify points.");
2055 if (r->isHumongous()) {
2056 if (r->startsHumongous()) {
2057 // Verify the single H object.
2058 oop(r->bottom())->verify();
2059 size_t word_sz = oop(r->bottom())->size();
2060 guarantee(r->top() == r->bottom() + word_sz,
2061 "Only one object in a humongous region");
2062 }
2063 } else {
2064 VerifyObjsInRegionClosure not_dead_yet_cl(r);
2065 r->verify(_allow_dirty);
2066 r->object_iterate(¬_dead_yet_cl);
2067 guarantee(r->max_live_bytes() >= not_dead_yet_cl.live_bytes(),
2068 "More live objects than counted in last complete marking.");
2069 }
2070 return false;
2071 }
2072 };
2073
2074 class VerifyRootsClosure: public OopsInGenClosure {
2075 private:
2076 G1CollectedHeap* _g1h;
2077 bool _failures;
2078
2079 public:
2080 VerifyRootsClosure() :
2081 _g1h(G1CollectedHeap::heap()), _failures(false) { }
2082
2083 bool failures() { return _failures; }
2084
2085 void do_oop(narrowOop* p) {
2086 guarantee(false, "NYI");
2087 }
2088
2089 void do_oop(oop* p) {
2090 oop obj = *p;
2091 if (obj != NULL) {
2092 if (_g1h->is_obj_dead(obj)) {
2093 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2094 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2095 obj->print_on(gclog_or_tty);
2096 _failures = true;
2097 }
2098 }
2099 }
2100 };
2101
2102 // This is the task used for parallel heap verification.
2103
2104 class G1ParVerifyTask: public AbstractGangTask {
2105 private:
2106 G1CollectedHeap* _g1h;
2107 bool _allow_dirty;
2108
2109 public:
2110 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty) :
2111 AbstractGangTask("Parallel verify task"),
2112 _g1h(g1h), _allow_dirty(allow_dirty) { }
2113
2114 void work(int worker_i) {
2115 VerifyRegionClosure blk(_allow_dirty, true);
2116 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2117 HeapRegion::ParVerifyClaimValue);
2118 }
2119 };
2120
2121 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2122 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2123 if (!silent) { gclog_or_tty->print("roots "); }
2124 VerifyRootsClosure rootsCl;
2125 process_strong_roots(false,
2126 SharedHeap::SO_AllClasses,
2127 &rootsCl,
2128 &rootsCl);
2129 rem_set()->invalidate(perm_gen()->used_region(), false);
2130 if (!silent) { gclog_or_tty->print("heapRegions "); }
2131 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2132 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2133 "sanity check");
2134
2135 G1ParVerifyTask task(this, allow_dirty);
2136 int n_workers = workers()->total_workers();
2137 set_par_threads(n_workers);
2138 workers()->run_task(&task);
2139 set_par_threads(0);
2140
2141 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2142 "sanity check");
2143
2144 reset_heap_region_claim_values();
2145
2146 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2147 "sanity check");
2148 } else {
2149 VerifyRegionClosure blk(allow_dirty);
2150 _hrs->iterate(&blk);
2151 }
2152 if (!silent) gclog_or_tty->print("remset ");
2153 rem_set()->verify();
2154 guarantee(!rootsCl.failures(), "should not have had failures");
2155 } else {
2156 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2157 }
2158 }
2159
2160 class PrintRegionClosure: public HeapRegionClosure {
2161 outputStream* _st;
2162 public:
2163 PrintRegionClosure(outputStream* st) : _st(st) {}
2164 bool doHeapRegion(HeapRegion* r) {
2165 r->print_on(_st);
2166 return false;
2167 }
2168 };
2169
2170 void G1CollectedHeap::print() const { print_on(gclog_or_tty); }
2171
2172 void G1CollectedHeap::print_on(outputStream* st) const {
2173 PrintRegionClosure blk(st);
2174 _hrs->iterate(&blk);
2175 }
2176
2177 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2178 if (ParallelGCThreads > 0) {
2179 workers()->print_worker_threads();
2180 }
2181 st->print("\"G1 concurrent mark GC Thread\" ");
2182 _cmThread->print();
2183 st->cr();
2184 st->print("\"G1 concurrent refinement GC Thread\" ");
2185 _cg1r->cg1rThread()->print_on(st);
2186 st->cr();
2187 st->print("\"G1 zero-fill GC Thread\" ");
2188 _czft->print_on(st);
2189 st->cr();
2190 }
2191
2192 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2193 if (ParallelGCThreads > 0) {
2194 workers()->threads_do(tc);
2195 }
2196 tc->do_thread(_cmThread);
2197 tc->do_thread(_cg1r->cg1rThread());
2198 tc->do_thread(_czft);
2199 }
2200
2201 void G1CollectedHeap::print_tracing_info() const {
2202 concurrent_g1_refine()->print_final_card_counts();
2203
2204 // We'll overload this to mean "trace GC pause statistics."
2205 if (TraceGen0Time || TraceGen1Time) {
2206 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2207 // to that.
2208 g1_policy()->print_tracing_info();
2209 }
2210 if (SummarizeG1RSStats) {
2211 g1_rem_set()->print_summary_info();
2212 }
2213 if (SummarizeG1ConcMark) {
2214 concurrent_mark()->print_summary_info();
2215 }
2216 if (SummarizeG1ZFStats) {
2217 ConcurrentZFThread::print_summary_info();
2218 }
2219 if (G1SummarizePopularity) {
2220 print_popularity_summary_info();
2221 }
2222 g1_policy()->print_yg_surv_rate_info();
2223
2224 GCOverheadReporter::printGCOverhead();
2225
2226 SpecializationStats::print();
2227 }
2228
2229
2230 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2231 HeapRegion* hr = heap_region_containing(addr);
2232 if (hr == NULL) {
2233 return 0;
2234 } else {
2235 return 1;
2236 }
2237 }
2238
2239 G1CollectedHeap* G1CollectedHeap::heap() {
2240 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
2241 "not a garbage-first heap");
2242 return _g1h;
2243 }
2244
2245 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2246 if (PrintHeapAtGC){
2247 gclog_or_tty->print_cr(" {Heap before GC collections=%d:", total_collections());
2248 Universe::print();
2249 }
2250 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2251 // Call allocation profiler
2252 AllocationProfiler::iterate_since_last_gc();
2253 // Fill TLAB's and such
2254 ensure_parsability(true);
2255 }
2256
2257 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
2258 // FIXME: what is this about?
2259 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2260 // is set.
2261 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
2262 "derived pointer present"));
2263
2264 if (PrintHeapAtGC){
2265 gclog_or_tty->print_cr(" Heap after GC collections=%d:", total_collections());
2266 Universe::print();
2267 gclog_or_tty->print("} ");
2268 }
2269 }
2270
2271 void G1CollectedHeap::do_collection_pause() {
2272 // Read the GC count while holding the Heap_lock
2273 // we need to do this _before_ wait_for_cleanup_complete(), to
2274 // ensure that we do not give up the heap lock and potentially
2275 // pick up the wrong count
2276 int gc_count_before = SharedHeap::heap()->total_collections();
2277
2278 // Don't want to do a GC pause while cleanup is being completed!
2279 wait_for_cleanup_complete();
2280
2281 g1_policy()->record_stop_world_start();
2282 {
2283 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
2284 VM_G1IncCollectionPause op(gc_count_before);
2285 VMThread::execute(&op);
2286 }
2287 }
2288
2289 void
2290 G1CollectedHeap::doConcurrentMark() {
2291 if (G1ConcMark) {
2292 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2293 if (!_cmThread->in_progress()) {
2294 _cmThread->set_started();
2295 CGC_lock->notify();
2296 }
2297 }
2298 }
2299
2300 class VerifyMarkedObjsClosure: public ObjectClosure {
2301 G1CollectedHeap* _g1h;
2302 public:
2303 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
2304 void do_object(oop obj) {
2305 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
2306 "markandsweep mark should agree with concurrent deadness");
2307 }
2308 };
2309
2310 void
2311 G1CollectedHeap::checkConcurrentMark() {
2312 VerifyMarkedObjsClosure verifycl(this);
2313 doConcurrentMark();
2314 // MutexLockerEx x(getMarkBitMapLock(),
2315 // Mutex::_no_safepoint_check_flag);
2316 object_iterate(&verifycl);
2317 }
2318
2319 void G1CollectedHeap::do_sync_mark() {
2320 _cm->checkpointRootsInitial();
2321 _cm->markFromRoots();
2322 _cm->checkpointRootsFinal(false);
2323 }
2324
2325 // <NEW PREDICTION>
2326
2327 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
2328 bool young) {
2329 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
2330 }
2331
2332 void G1CollectedHeap::check_if_region_is_too_expensive(double
2333 predicted_time_ms) {
2334 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
2335 }
2336
2337 size_t G1CollectedHeap::pending_card_num() {
2338 size_t extra_cards = 0;
2339 JavaThread *curr = Threads::first();
2340 while (curr != NULL) {
2341 DirtyCardQueue& dcq = curr->dirty_card_queue();
2342 extra_cards += dcq.size();
2343 curr = curr->next();
2344 }
2345 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2346 size_t buffer_size = dcqs.buffer_size();
2347 size_t buffer_num = dcqs.completed_buffers_num();
2348 return buffer_size * buffer_num + extra_cards;
2349 }
2350
2351 size_t G1CollectedHeap::max_pending_card_num() {
2352 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2353 size_t buffer_size = dcqs.buffer_size();
2354 size_t buffer_num = dcqs.completed_buffers_num();
2355 int thread_num = Threads::number_of_threads();
2356 return (buffer_num + thread_num) * buffer_size;
2357 }
2358
2359 size_t G1CollectedHeap::cards_scanned() {
2360 HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
2361 return g1_rset->cardsScanned();
2362 }
2363
2364 void
2365 G1CollectedHeap::setup_surviving_young_words() {
2366 guarantee( _surviving_young_words == NULL, "pre-condition" );
2367 size_t array_length = g1_policy()->young_cset_length();
2368 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
2369 if (_surviving_young_words == NULL) {
2370 vm_exit_out_of_memory(sizeof(size_t) * array_length,
2371 "Not enough space for young surv words summary.");
2372 }
2373 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
2374 for (size_t i = 0; i < array_length; ++i) {
2375 guarantee( _surviving_young_words[i] == 0, "invariant" );
2376 }
2377 }
2378
2379 void
2380 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
2381 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2382 size_t array_length = g1_policy()->young_cset_length();
2383 for (size_t i = 0; i < array_length; ++i)
2384 _surviving_young_words[i] += surv_young_words[i];
2385 }
2386
2387 void
2388 G1CollectedHeap::cleanup_surviving_young_words() {
2389 guarantee( _surviving_young_words != NULL, "pre-condition" );
2390 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
2391 _surviving_young_words = NULL;
2392 }
2393
2394 // </NEW PREDICTION>
2395
2396 void
2397 G1CollectedHeap::do_collection_pause_at_safepoint(HeapRegion* popular_region) {
2398 char verbose_str[128];
2399 sprintf(verbose_str, "GC pause ");
2400 if (popular_region != NULL)
2401 strcat(verbose_str, "(popular)");
2402 else if (g1_policy()->in_young_gc_mode()) {
2403 if (g1_policy()->full_young_gcs())
2404 strcat(verbose_str, "(young)");
2405 else
2406 strcat(verbose_str, "(partial)");
2407 }
2408 bool reset_should_initiate_conc_mark = false;
2409 if (popular_region != NULL && g1_policy()->should_initiate_conc_mark()) {
2410 // we currently do not allow an initial mark phase to be piggy-backed
2411 // on a popular pause
2412 reset_should_initiate_conc_mark = true;
2413 g1_policy()->unset_should_initiate_conc_mark();
2414 }
2415 if (g1_policy()->should_initiate_conc_mark())
2416 strcat(verbose_str, " (initial-mark)");
2417
2418 GCCauseSetter x(this, (popular_region == NULL ?
2419 GCCause::_g1_inc_collection_pause :
2420 GCCause::_g1_pop_region_collection_pause));
2421
2422 // if PrintGCDetails is on, we'll print long statistics information
2423 // in the collector policy code, so let's not print this as the output
2424 // is messy if we do.
2425 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2426 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2427 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
2428
2429 ResourceMark rm;
2430 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
2431 assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
2432 guarantee(!is_gc_active(), "collection is not reentrant");
2433 assert(regions_accounted_for(), "Region leakage!");
2434
2435 increment_gc_time_stamp();
2436
2437 if (g1_policy()->in_young_gc_mode()) {
2438 assert(check_young_list_well_formed(),
2439 "young list should be well formed");
2440 }
2441
2442 if (GC_locker::is_active()) {
2443 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
2444 }
2445
2446 bool abandoned = false;
2447 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2448 IsGCActiveMark x;
2449
2450 gc_prologue(false);
2451 increment_total_collections();
2452
2453 #if G1_REM_SET_LOGGING
2454 gclog_or_tty->print_cr("\nJust chose CS, heap:");
2455 print();
2456 #endif
2457
2458 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
2459 HandleMark hm; // Discard invalid handles created during verification
2460 prepare_for_verify();
2461 gclog_or_tty->print(" VerifyBeforeGC:");
2462 Universe::verify(false);
2463 }
2464
2465 COMPILER2_PRESENT(DerivedPointerTable::clear());
2466
2467 // We want to turn off ref discovery, if necessary, and turn it back on
2468 // on again later if we do.
2469 bool was_enabled = ref_processor()->discovery_enabled();
2470 if (was_enabled) ref_processor()->disable_discovery();
2471
2472 // Forget the current alloc region (we might even choose it to be part
2473 // of the collection set!).
2474 abandon_cur_alloc_region();
2475
2476 // The elapsed time induced by the start time below deliberately elides
2477 // the possible verification above.
2478 double start_time_sec = os::elapsedTime();
2479 GCOverheadReporter::recordSTWStart(start_time_sec);
2480 size_t start_used_bytes = used();
2481 if (!G1ConcMark) {
2482 do_sync_mark();
2483 }
2484
2485 g1_policy()->record_collection_pause_start(start_time_sec,
2486 start_used_bytes);
2487
2488 #if SCAN_ONLY_VERBOSE
2489 _young_list->print();
2490 #endif // SCAN_ONLY_VERBOSE
2491
2492 if (g1_policy()->should_initiate_conc_mark()) {
2493 concurrent_mark()->checkpointRootsInitialPre();
2494 }
2495 save_marks();
2496
2497 // We must do this before any possible evacuation that should propogate
2498 // marks, including evacuation of popular objects in a popular pause.
2499 if (mark_in_progress()) {
2500 double start_time_sec = os::elapsedTime();
2501
2502 _cm->drainAllSATBBuffers();
2503 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
2504 g1_policy()->record_satb_drain_time(finish_mark_ms);
2505
2506 }
2507 // Record the number of elements currently on the mark stack, so we
2508 // only iterate over these. (Since evacuation may add to the mark
2509 // stack, doing more exposes race conditions.) If no mark is in
2510 // progress, this will be zero.
2511 _cm->set_oops_do_bound();
2512
2513 assert(regions_accounted_for(), "Region leakage.");
2514
2515 bool abandoned = false;
2516
2517 if (mark_in_progress())
2518 concurrent_mark()->newCSet();
2519
2520 // Now choose the CS.
2521 if (popular_region == NULL) {
2522 g1_policy()->choose_collection_set();
2523 } else {
2524 // We may be evacuating a single region (for popularity).
2525 g1_policy()->record_popular_pause_preamble_start();
2526 popularity_pause_preamble(popular_region);
2527 g1_policy()->record_popular_pause_preamble_end();
2528 abandoned = (g1_policy()->collection_set() == NULL);
2529 // Now we allow more regions to be added (we have to collect
2530 // all popular regions).
2531 if (!abandoned) {
2532 g1_policy()->choose_collection_set(popular_region);
2533 }
2534 }
2535 // We may abandon a pause if we find no region that will fit in the MMU
2536 // pause.
2537 abandoned = (g1_policy()->collection_set() == NULL);
2538
2539 // Nothing to do if we were unable to choose a collection set.
2540 if (!abandoned) {
2541 #if G1_REM_SET_LOGGING
2542 gclog_or_tty->print_cr("\nAfter pause, heap:");
2543 print();
2544 #endif
2545
2546 setup_surviving_young_words();
2547
2548 // Set up the gc allocation regions.
2549 get_gc_alloc_regions();
2550
2551 // Actually do the work...
2552 evacuate_collection_set();
2553 free_collection_set(g1_policy()->collection_set());
2554 g1_policy()->clear_collection_set();
2555
2556 if (popular_region != NULL) {
2557 // We have to wait until now, because we don't want the region to
2558 // be rescheduled for pop-evac during RS update.
2559 popular_region->set_popular_pending(false);
2560 }
2561
2562 release_gc_alloc_regions();
2563
2564 cleanup_surviving_young_words();
2565
2566 if (g1_policy()->in_young_gc_mode()) {
2567 _young_list->reset_sampled_info();
2568 assert(check_young_list_empty(true),
2569 "young list should be empty");
2570
2571 #if SCAN_ONLY_VERBOSE
2572 _young_list->print();
2573 #endif // SCAN_ONLY_VERBOSE
2574
2575 _young_list->reset_auxilary_lists();
2576 }
2577 } else {
2578 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
2579 }
2580
2581 if (evacuation_failed()) {
2582 _summary_bytes_used = recalculate_used();
2583 } else {
2584 // The "used" of the the collection set have already been subtracted
2585 // when they were freed. Add in the bytes evacuated.
2586 _summary_bytes_used += g1_policy()->bytes_in_to_space();
2587 }
2588
2589 if (g1_policy()->in_young_gc_mode() &&
2590 g1_policy()->should_initiate_conc_mark()) {
2591 concurrent_mark()->checkpointRootsInitialPost();
2592 set_marking_started();
2593 doConcurrentMark();
2594 }
2595
2596 #if SCAN_ONLY_VERBOSE
2597 _young_list->print();
2598 #endif // SCAN_ONLY_VERBOSE
2599
2600 double end_time_sec = os::elapsedTime();
2601 g1_policy()->record_pause_time((end_time_sec - start_time_sec)*1000.0);
2602 GCOverheadReporter::recordSTWEnd(end_time_sec);
2603 g1_policy()->record_collection_pause_end(popular_region != NULL,
2604 abandoned);
2605
2606 assert(regions_accounted_for(), "Region leakage.");
2607
2608 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
2609 HandleMark hm; // Discard invalid handles created during verification
2610 gclog_or_tty->print(" VerifyAfterGC:");
2611 Universe::verify(false);
2612 }
2613
2614 if (was_enabled) ref_processor()->enable_discovery();
2615
2616 {
2617 size_t expand_bytes = g1_policy()->expansion_amount();
2618 if (expand_bytes > 0) {
2619 size_t bytes_before = capacity();
2620 expand(expand_bytes);
2621 }
2622 }
2623
2624 if (mark_in_progress())
2625 concurrent_mark()->update_g1_committed();
2626
2627 gc_epilogue(false);
2628 }
2629
2630 assert(verify_region_lists(), "Bad region lists.");
2631
2632 if (reset_should_initiate_conc_mark)
2633 g1_policy()->set_should_initiate_conc_mark();
2634
2635 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
2636 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
2637 print_tracing_info();
2638 vm_exit(-1);
2639 }
2640 }
2641
2642 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
2643 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
2644 HeapWord* original_top = NULL;
2645 if (r != NULL)
2646 original_top = r->top();
2647
2648 // We will want to record the used space in r as being there before gc.
2649 // One we install it as a GC alloc region it's eligible for allocation.
2650 // So record it now and use it later.
2651 size_t r_used = 0;
2652 if (r != NULL) {
2653 r_used = r->used();
2654
2655 if (ParallelGCThreads > 0) {
2656 // need to take the lock to guard against two threads calling
2657 // get_gc_alloc_region concurrently (very unlikely but...)
2658 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
2659 r->save_marks();
2660 }
2661 }
2662 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
2663 _gc_alloc_regions[purpose] = r;
2664 if (old_alloc_region != NULL) {
2665 // Replace aliases too.
2666 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2667 if (_gc_alloc_regions[ap] == old_alloc_region) {
2668 _gc_alloc_regions[ap] = r;
2669 }
2670 }
2671 }
2672 if (r != NULL) {
2673 push_gc_alloc_region(r);
2674 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
2675 // We are using a region as a GC alloc region after it has been used
2676 // as a mutator allocation region during the current marking cycle.
2677 // The mutator-allocated objects are currently implicitly marked, but
2678 // when we move hr->next_top_at_mark_start() forward at the the end
2679 // of the GC pause, they won't be. We therefore mark all objects in
2680 // the "gap". We do this object-by-object, since marking densely
2681 // does not currently work right with marking bitmap iteration. This
2682 // means we rely on TLAB filling at the start of pauses, and no
2683 // "resuscitation" of filled TLAB's. If we want to do this, we need
2684 // to fix the marking bitmap iteration.
2685 HeapWord* curhw = r->next_top_at_mark_start();
2686 HeapWord* t = original_top;
2687
2688 while (curhw < t) {
2689 oop cur = (oop)curhw;
2690 // We'll assume parallel for generality. This is rare code.
2691 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
2692 curhw = curhw + cur->size();
2693 }
2694 assert(curhw == t, "Should have parsed correctly.");
2695 }
2696 if (G1PolicyVerbose > 1) {
2697 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
2698 "for survivors:", r->bottom(), original_top, r->end());
2699 r->print();
2700 }
2701 g1_policy()->record_before_bytes(r_used);
2702 }
2703 }
2704
2705 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
2706 assert(Thread::current()->is_VM_thread() ||
2707 par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
2708 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
2709 "Precondition.");
2710 hr->set_is_gc_alloc_region(true);
2711 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
2712 _gc_alloc_region_list = hr;
2713 }
2714
2715 #ifdef G1_DEBUG
2716 class FindGCAllocRegion: public HeapRegionClosure {
2717 public:
2718 bool doHeapRegion(HeapRegion* r) {
2719 if (r->is_gc_alloc_region()) {
2720 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
2721 r->hrs_index(), r->bottom());
2722 }
2723 return false;
2724 }
2725 };
2726 #endif // G1_DEBUG
2727
2728 void G1CollectedHeap::forget_alloc_region_list() {
2729 assert(Thread::current()->is_VM_thread(), "Precondition");
2730 while (_gc_alloc_region_list != NULL) {
2731 HeapRegion* r = _gc_alloc_region_list;
2732 assert(r->is_gc_alloc_region(), "Invariant.");
2733 _gc_alloc_region_list = r->next_gc_alloc_region();
2734 r->set_next_gc_alloc_region(NULL);
2735 r->set_is_gc_alloc_region(false);
2736 if (r->is_empty()) {
2737 ++_free_regions;
2738 }
2739 }
2740 #ifdef G1_DEBUG
2741 FindGCAllocRegion fa;
2742 heap_region_iterate(&fa);
2743 #endif // G1_DEBUG
2744 }
2745
2746
2747 bool G1CollectedHeap::check_gc_alloc_regions() {
2748 // TODO: allocation regions check
2749 return true;
2750 }
2751
2752 void G1CollectedHeap::get_gc_alloc_regions() {
2753 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2754 // Create new GC alloc regions.
2755 HeapRegion* alloc_region = _gc_alloc_regions[ap];
2756 // Clear this alloc region, so that in case it turns out to be
2757 // unacceptable, we end up with no allocation region, rather than a bad
2758 // one.
2759 _gc_alloc_regions[ap] = NULL;
2760 if (alloc_region == NULL || alloc_region->in_collection_set()) {
2761 // Can't re-use old one. Allocate a new one.
2762 alloc_region = newAllocRegionWithExpansion(ap, 0);
2763 }
2764 if (alloc_region != NULL) {
2765 set_gc_alloc_region(ap, alloc_region);
2766 }
2767 }
2768 // Set alternative regions for allocation purposes that have reached
2769 // thier limit.
2770 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2771 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
2772 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
2773 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
2774 }
2775 }
2776 assert(check_gc_alloc_regions(), "alloc regions messed up");
2777 }
2778
2779 void G1CollectedHeap::release_gc_alloc_regions() {
2780 // We keep a separate list of all regions that have been alloc regions in
2781 // the current collection pause. Forget that now.
2782 forget_alloc_region_list();
2783
2784 // The current alloc regions contain objs that have survived
2785 // collection. Make them no longer GC alloc regions.
2786 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2787 HeapRegion* r = _gc_alloc_regions[ap];
2788 if (r != NULL && r->is_empty()) {
2789 {
2790 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
2791 r->set_zero_fill_complete();
2792 put_free_region_on_list_locked(r);
2793 }
2794 }
2795 // set_gc_alloc_region will also NULLify all aliases to the region
2796 set_gc_alloc_region(ap, NULL);
2797 _gc_alloc_region_counts[ap] = 0;
2798 }
2799 }
2800
2801 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
2802 _drain_in_progress = false;
2803 set_evac_failure_closure(cl);
2804 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
2805 }
2806
2807 void G1CollectedHeap::finalize_for_evac_failure() {
2808 assert(_evac_failure_scan_stack != NULL &&
2809 _evac_failure_scan_stack->length() == 0,
2810 "Postcondition");
2811 assert(!_drain_in_progress, "Postcondition");
2812 // Don't have to delete, since the scan stack is a resource object.
2813 _evac_failure_scan_stack = NULL;
2814 }
2815
2816
2817
2818 // *** Sequential G1 Evacuation
2819
2820 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
2821 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
2822 // let the caller handle alloc failure
2823 if (alloc_region == NULL) return NULL;
2824 assert(isHumongous(word_size) || !alloc_region->isHumongous(),
2825 "Either the object is humongous or the region isn't");
2826 HeapWord* block = alloc_region->allocate(word_size);
2827 if (block == NULL) {
2828 block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
2829 }
2830 return block;
2831 }
2832
2833 class G1IsAliveClosure: public BoolObjectClosure {
2834 G1CollectedHeap* _g1;
2835 public:
2836 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
2837 void do_object(oop p) { assert(false, "Do not call."); }
2838 bool do_object_b(oop p) {
2839 // It is reachable if it is outside the collection set, or is inside
2840 // and forwarded.
2841
2842 #ifdef G1_DEBUG
2843 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
2844 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
2845 !_g1->obj_in_cs(p) || p->is_forwarded());
2846 #endif // G1_DEBUG
2847
2848 return !_g1->obj_in_cs(p) || p->is_forwarded();
2849 }
2850 };
2851
2852 class G1KeepAliveClosure: public OopClosure {
2853 G1CollectedHeap* _g1;
2854 public:
2855 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
2856 void do_oop(narrowOop* p) {
2857 guarantee(false, "NYI");
2858 }
2859 void do_oop(oop* p) {
2860 oop obj = *p;
2861 #ifdef G1_DEBUG
2862 if (PrintGC && Verbose) {
2863 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
2864 p, (void*) obj, (void*) *p);
2865 }
2866 #endif // G1_DEBUG
2867
2868 if (_g1->obj_in_cs(obj)) {
2869 assert( obj->is_forwarded(), "invariant" );
2870 *p = obj->forwardee();
2871
2872 #ifdef G1_DEBUG
2873 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
2874 (void*) obj, (void*) *p);
2875 #endif // G1_DEBUG
2876 }
2877 }
2878 };
2879
2880 class RecreateRSetEntriesClosure: public OopClosure {
2881 private:
2882 G1CollectedHeap* _g1;
2883 G1RemSet* _g1_rem_set;
2884 HeapRegion* _from;
2885 public:
2886 RecreateRSetEntriesClosure(G1CollectedHeap* g1, HeapRegion* from) :
2887 _g1(g1), _g1_rem_set(g1->g1_rem_set()), _from(from)
2888 {}
2889
2890 void do_oop(narrowOop* p) {
2891 guarantee(false, "NYI");
2892 }
2893 void do_oop(oop* p) {
2894 assert(_from->is_in_reserved(p), "paranoia");
2895 if (*p != NULL) {
2896 _g1_rem_set->write_ref(_from, p);
2897 }
2898 }
2899 };
2900
2901 class RemoveSelfPointerClosure: public ObjectClosure {
2902 private:
2903 G1CollectedHeap* _g1;
2904 ConcurrentMark* _cm;
2905 HeapRegion* _hr;
2906 size_t _prev_marked_bytes;
2907 size_t _next_marked_bytes;
2908 public:
2909 RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr) :
2910 _g1(g1), _cm(_g1->concurrent_mark()), _hr(hr),
2911 _prev_marked_bytes(0), _next_marked_bytes(0)
2912 {}
2913
2914 size_t prev_marked_bytes() { return _prev_marked_bytes; }
2915 size_t next_marked_bytes() { return _next_marked_bytes; }
2916
2917 // The original idea here was to coalesce evacuated and dead objects.
2918 // However that caused complications with the block offset table (BOT).
2919 // In particular if there were two TLABs, one of them partially refined.
2920 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
2921 // The BOT entries of the unrefined part of TLAB_2 point to the start
2922 // of TLAB_2. If the last object of the TLAB_1 and the first object
2923 // of TLAB_2 are coalesced, then the cards of the unrefined part
2924 // would point into middle of the filler object.
2925 //
2926 // The current approach is to not coalesce and leave the BOT contents intact.
2927 void do_object(oop obj) {
2928 if (obj->is_forwarded() && obj->forwardee() == obj) {
2929 // The object failed to move.
2930 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
2931 _cm->markPrev(obj);
2932 assert(_cm->isPrevMarked(obj), "Should be marked!");
2933 _prev_marked_bytes += (obj->size() * HeapWordSize);
2934 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
2935 _cm->markAndGrayObjectIfNecessary(obj);
2936 }
2937 obj->set_mark(markOopDesc::prototype());
2938 // While we were processing RSet buffers during the
2939 // collection, we actually didn't scan any cards on the
2940 // collection set, since we didn't want to update remebered
2941 // sets with entries that point into the collection set, given
2942 // that live objects fromthe collection set are about to move
2943 // and such entries will be stale very soon. This change also
2944 // dealt with a reliability issue which involved scanning a
2945 // card in the collection set and coming across an array that
2946 // was being chunked and looking malformed. The problem is
2947 // that, if evacuation fails, we might have remembered set
2948 // entries missing given that we skipped cards on the
2949 // collection set. So, we'll recreate such entries now.
2950 RecreateRSetEntriesClosure cl(_g1, _hr);
2951 obj->oop_iterate(&cl);
2952 assert(_cm->isPrevMarked(obj), "Should be marked!");
2953 } else {
2954 // The object has been either evacuated or is dead. Fill it with a
2955 // dummy object.
2956 MemRegion mr((HeapWord*)obj, obj->size());
2957 SharedHeap::fill_region_with_object(mr);
2958 _cm->clearRangeBothMaps(mr);
2959 }
2960 }
2961 };
2962
2963 void G1CollectedHeap::remove_self_forwarding_pointers() {
2964 HeapRegion* cur = g1_policy()->collection_set();
2965
2966 while (cur != NULL) {
2967 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
2968
2969 if (cur->evacuation_failed()) {
2970 RemoveSelfPointerClosure rspc(_g1h, cur);
2971 assert(cur->in_collection_set(), "bad CS");
2972 cur->object_iterate(&rspc);
2973
2974 // A number of manipulations to make the TAMS be the current top,
2975 // and the marked bytes be the ones observed in the iteration.
2976 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
2977 // The comments below are the postconditions achieved by the
2978 // calls. Note especially the last such condition, which says that
2979 // the count of marked bytes has been properly restored.
2980 cur->note_start_of_marking(false);
2981 // _next_top_at_mark_start == top, _next_marked_bytes == 0
2982 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
2983 // _next_marked_bytes == prev_marked_bytes.
2984 cur->note_end_of_marking();
2985 // _prev_top_at_mark_start == top(),
2986 // _prev_marked_bytes == prev_marked_bytes
2987 }
2988 // If there is no mark in progress, we modified the _next variables
2989 // above needlessly, but harmlessly.
2990 if (_g1h->mark_in_progress()) {
2991 cur->note_start_of_marking(false);
2992 // _next_top_at_mark_start == top, _next_marked_bytes == 0
2993 // _next_marked_bytes == next_marked_bytes.
2994 }
2995
2996 // Now make sure the region has the right index in the sorted array.
2997 g1_policy()->note_change_in_marked_bytes(cur);
2998 }
2999 cur = cur->next_in_collection_set();
3000 }
3001 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3002
3003 // Now restore saved marks, if any.
3004 if (_objs_with_preserved_marks != NULL) {
3005 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3006 assert(_objs_with_preserved_marks->length() ==
3007 _preserved_marks_of_objs->length(), "Both or none.");
3008 guarantee(_objs_with_preserved_marks->length() ==
3009 _preserved_marks_of_objs->length(), "Both or none.");
3010 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3011 oop obj = _objs_with_preserved_marks->at(i);
3012 markOop m = _preserved_marks_of_objs->at(i);
3013 obj->set_mark(m);
3014 }
3015 // Delete the preserved marks growable arrays (allocated on the C heap).
3016 delete _objs_with_preserved_marks;
3017 delete _preserved_marks_of_objs;
3018 _objs_with_preserved_marks = NULL;
3019 _preserved_marks_of_objs = NULL;
3020 }
3021 }
3022
3023 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3024 _evac_failure_scan_stack->push(obj);
3025 }
3026
3027 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3028 assert(_evac_failure_scan_stack != NULL, "precondition");
3029
3030 while (_evac_failure_scan_stack->length() > 0) {
3031 oop obj = _evac_failure_scan_stack->pop();
3032 _evac_failure_closure->set_region(heap_region_containing(obj));
3033 obj->oop_iterate_backwards(_evac_failure_closure);
3034 }
3035 }
3036
3037 void G1CollectedHeap::handle_evacuation_failure(oop old) {
3038 markOop m = old->mark();
3039 // forward to self
3040 assert(!old->is_forwarded(), "precondition");
3041
3042 old->forward_to(old);
3043 handle_evacuation_failure_common(old, m);
3044 }
3045
3046 oop
3047 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
3048 oop old) {
3049 markOop m = old->mark();
3050 oop forward_ptr = old->forward_to_atomic(old);
3051 if (forward_ptr == NULL) {
3052 // Forward-to-self succeeded.
3053 if (_evac_failure_closure != cl) {
3054 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
3055 assert(!_drain_in_progress,
3056 "Should only be true while someone holds the lock.");
3057 // Set the global evac-failure closure to the current thread's.
3058 assert(_evac_failure_closure == NULL, "Or locking has failed.");
3059 set_evac_failure_closure(cl);
3060 // Now do the common part.
3061 handle_evacuation_failure_common(old, m);
3062 // Reset to NULL.
3063 set_evac_failure_closure(NULL);
3064 } else {
3065 // The lock is already held, and this is recursive.
3066 assert(_drain_in_progress, "This should only be the recursive case.");
3067 handle_evacuation_failure_common(old, m);
3068 }
3069 return old;
3070 } else {
3071 // Someone else had a place to copy it.
3072 return forward_ptr;
3073 }
3074 }
3075
3076 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
3077 set_evacuation_failed(true);
3078
3079 preserve_mark_if_necessary(old, m);
3080
3081 HeapRegion* r = heap_region_containing(old);
3082 if (!r->evacuation_failed()) {
3083 r->set_evacuation_failed(true);
3084 if (G1TraceRegions) {
3085 gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
3086 "["PTR_FORMAT","PTR_FORMAT")\n",
3087 r, r->bottom(), r->end());
3088 }
3089 }
3090
3091 push_on_evac_failure_scan_stack(old);
3092
3093 if (!_drain_in_progress) {
3094 // prevent recursion in copy_to_survivor_space()
3095 _drain_in_progress = true;
3096 drain_evac_failure_scan_stack();
3097 _drain_in_progress = false;
3098 }
3099 }
3100
3101 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
3102 if (m != markOopDesc::prototype()) {
3103 if (_objs_with_preserved_marks == NULL) {
3104 assert(_preserved_marks_of_objs == NULL, "Both or none.");
3105 _objs_with_preserved_marks =
3106 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3107 _preserved_marks_of_objs =
3108 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
3109 }
3110 _objs_with_preserved_marks->push(obj);
3111 _preserved_marks_of_objs->push(m);
3112 }
3113 }
3114
3115 // *** Parallel G1 Evacuation
3116
3117 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
3118 size_t word_size) {
3119 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
3120 // let the caller handle alloc failure
3121 if (alloc_region == NULL) return NULL;
3122
3123 HeapWord* block = alloc_region->par_allocate(word_size);
3124 if (block == NULL) {
3125 MutexLockerEx x(par_alloc_during_gc_lock(),
3126 Mutex::_no_safepoint_check_flag);
3127 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
3128 }
3129 return block;
3130 }
3131
3132 HeapWord*
3133 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
3134 HeapRegion* alloc_region,
3135 bool par,
3136 size_t word_size) {
3137 HeapWord* block = NULL;
3138 // In the parallel case, a previous thread to obtain the lock may have
3139 // already assigned a new gc_alloc_region.
3140 if (alloc_region != _gc_alloc_regions[purpose]) {
3141 assert(par, "But should only happen in parallel case.");
3142 alloc_region = _gc_alloc_regions[purpose];
3143 if (alloc_region == NULL) return NULL;
3144 block = alloc_region->par_allocate(word_size);
3145 if (block != NULL) return block;
3146 // Otherwise, continue; this new region is empty, too.
3147 }
3148 assert(alloc_region != NULL, "We better have an allocation region");
3149 // Another thread might have obtained alloc_region for the given
3150 // purpose, and might be attempting to allocate in it, and might
3151 // succeed. Therefore, we can't do the "finalization" stuff on the
3152 // region below until we're sure the last allocation has happened.
3153 // We ensure this by allocating the remaining space with a garbage
3154 // object.
3155 if (par) par_allocate_remaining_space(alloc_region);
3156 // Now we can do the post-GC stuff on the region.
3157 alloc_region->note_end_of_copying();
3158 g1_policy()->record_after_bytes(alloc_region->used());
3159
3160 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
3161 // Cannot allocate more regions for the given purpose.
3162 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
3163 // Is there an alternative?
3164 if (purpose != alt_purpose) {
3165 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
3166 // Has not the alternative region been aliased?
3167 if (alloc_region != alt_region) {
3168 // Try to allocate in the alternative region.
3169 if (par) {
3170 block = alt_region->par_allocate(word_size);
3171 } else {
3172 block = alt_region->allocate(word_size);
3173 }
3174 // Make an alias.
3175 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
3176 }
3177 if (block != NULL) {
3178 return block;
3179 }
3180 // Both the allocation region and the alternative one are full
3181 // and aliased, replace them with a new allocation region.
3182 purpose = alt_purpose;
3183 } else {
3184 set_gc_alloc_region(purpose, NULL);
3185 return NULL;
3186 }
3187 }
3188
3189 // Now allocate a new region for allocation.
3190 alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
3191
3192 // let the caller handle alloc failure
3193 if (alloc_region != NULL) {
3194
3195 assert(check_gc_alloc_regions(), "alloc regions messed up");
3196 assert(alloc_region->saved_mark_at_top(),
3197 "Mark should have been saved already.");
3198 // We used to assert that the region was zero-filled here, but no
3199 // longer.
3200
3201 // This must be done last: once it's installed, other regions may
3202 // allocate in it (without holding the lock.)
3203 set_gc_alloc_region(purpose, alloc_region);
3204
3205 if (par) {
3206 block = alloc_region->par_allocate(word_size);
3207 } else {
3208 block = alloc_region->allocate(word_size);
3209 }
3210 // Caller handles alloc failure.
3211 } else {
3212 // This sets other apis using the same old alloc region to NULL, also.
3213 set_gc_alloc_region(purpose, NULL);
3214 }
3215 return block; // May be NULL.
3216 }
3217
3218 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
3219 HeapWord* block = NULL;
3220 size_t free_words;
3221 do {
3222 free_words = r->free()/HeapWordSize;
3223 // If there's too little space, no one can allocate, so we're done.
3224 if (free_words < (size_t)oopDesc::header_size()) return;
3225 // Otherwise, try to claim it.
3226 block = r->par_allocate(free_words);
3227 } while (block == NULL);
3228 SharedHeap::fill_region_with_object(MemRegion(block, free_words));
3229 }
3230
3231 #define use_local_bitmaps 1
3232 #define verify_local_bitmaps 0
3233
3234 #ifndef PRODUCT
3235
3236 class GCLabBitMap;
3237 class GCLabBitMapClosure: public BitMapClosure {
3238 private:
3239 ConcurrentMark* _cm;
3240 GCLabBitMap* _bitmap;
3241
3242 public:
3243 GCLabBitMapClosure(ConcurrentMark* cm,
3244 GCLabBitMap* bitmap) {
3245 _cm = cm;
3246 _bitmap = bitmap;
3247 }
3248
3249 virtual bool do_bit(size_t offset);
3250 };
3251
3252 #endif // PRODUCT
3253
3254 #define oop_buffer_length 256
3255
3256 class GCLabBitMap: public BitMap {
3257 private:
3258 ConcurrentMark* _cm;
3259
3260 int _shifter;
3261 size_t _bitmap_word_covers_words;
3262
3263 // beginning of the heap
3264 HeapWord* _heap_start;
3265
3266 // this is the actual start of the GCLab
3267 HeapWord* _real_start_word;
3268
3269 // this is the actual end of the GCLab
3270 HeapWord* _real_end_word;
3271
3272 // this is the first word, possibly located before the actual start
3273 // of the GCLab, that corresponds to the first bit of the bitmap
3274 HeapWord* _start_word;
3275
3276 // size of a GCLab in words
3277 size_t _gclab_word_size;
3278
3279 static int shifter() {
3280 return MinObjAlignment - 1;
3281 }
3282
3283 // how many heap words does a single bitmap word corresponds to?
3284 static size_t bitmap_word_covers_words() {
3285 return BitsPerWord << shifter();
3286 }
3287
3288 static size_t gclab_word_size() {
3289 return ParallelGCG1AllocBufferSize / HeapWordSize;
3290 }
3291
3292 static size_t bitmap_size_in_bits() {
3293 size_t bits_in_bitmap = gclab_word_size() >> shifter();
3294 // We are going to ensure that the beginning of a word in this
3295 // bitmap also corresponds to the beginning of a word in the
3296 // global marking bitmap. To handle the case where a GCLab
3297 // starts from the middle of the bitmap, we need to add enough
3298 // space (i.e. up to a bitmap word) to ensure that we have
3299 // enough bits in the bitmap.
3300 return bits_in_bitmap + BitsPerWord - 1;
3301 }
3302 public:
3303 GCLabBitMap(HeapWord* heap_start)
3304 : BitMap(bitmap_size_in_bits()),
3305 _cm(G1CollectedHeap::heap()->concurrent_mark()),
3306 _shifter(shifter()),
3307 _bitmap_word_covers_words(bitmap_word_covers_words()),
3308 _heap_start(heap_start),
3309 _gclab_word_size(gclab_word_size()),
3310 _real_start_word(NULL),
3311 _real_end_word(NULL),
3312 _start_word(NULL)
3313 {
3314 guarantee( size_in_words() >= bitmap_size_in_words(),
3315 "just making sure");
3316 }
3317
3318 inline unsigned heapWordToOffset(HeapWord* addr) {
3319 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
3320 assert(offset < size(), "offset should be within bounds");
3321 return offset;
3322 }
3323
3324 inline HeapWord* offsetToHeapWord(size_t offset) {
3325 HeapWord* addr = _start_word + (offset << _shifter);
3326 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
3327 return addr;
3328 }
3329
3330 bool fields_well_formed() {
3331 bool ret1 = (_real_start_word == NULL) &&
3332 (_real_end_word == NULL) &&
3333 (_start_word == NULL);
3334 if (ret1)
3335 return true;
3336
3337 bool ret2 = _real_start_word >= _start_word &&
3338 _start_word < _real_end_word &&
3339 (_real_start_word + _gclab_word_size) == _real_end_word &&
3340 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
3341 > _real_end_word;
3342 return ret2;
3343 }
3344
3345 inline bool mark(HeapWord* addr) {
3346 guarantee(use_local_bitmaps, "invariant");
3347 assert(fields_well_formed(), "invariant");
3348
3349 if (addr >= _real_start_word && addr < _real_end_word) {
3350 assert(!isMarked(addr), "should not have already been marked");
3351
3352 // first mark it on the bitmap
3353 at_put(heapWordToOffset(addr), true);
3354
3355 return true;
3356 } else {
3357 return false;
3358 }
3359 }
3360
3361 inline bool isMarked(HeapWord* addr) {
3362 guarantee(use_local_bitmaps, "invariant");
3363 assert(fields_well_formed(), "invariant");
3364
3365 return at(heapWordToOffset(addr));
3366 }
3367
3368 void set_buffer(HeapWord* start) {
3369 guarantee(use_local_bitmaps, "invariant");
3370 clear();
3371
3372 assert(start != NULL, "invariant");
3373 _real_start_word = start;
3374 _real_end_word = start + _gclab_word_size;
3375
3376 size_t diff =
3377 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
3378 _start_word = start - diff;
3379
3380 assert(fields_well_formed(), "invariant");
3381 }
3382
3383 #ifndef PRODUCT
3384 void verify() {
3385 // verify that the marks have been propagated
3386 GCLabBitMapClosure cl(_cm, this);
3387 iterate(&cl);
3388 }
3389 #endif // PRODUCT
3390
3391 void retire() {
3392 guarantee(use_local_bitmaps, "invariant");
3393 assert(fields_well_formed(), "invariant");
3394
3395 if (_start_word != NULL) {
3396 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
3397
3398 // this means that the bitmap was set up for the GCLab
3399 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
3400
3401 mark_bitmap->mostly_disjoint_range_union(this,
3402 0, // always start from the start of the bitmap
3403 _start_word,
3404 size_in_words());
3405 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
3406
3407 #ifndef PRODUCT
3408 if (use_local_bitmaps && verify_local_bitmaps)
3409 verify();
3410 #endif // PRODUCT
3411 } else {
3412 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
3413 }
3414 }
3415
3416 static size_t bitmap_size_in_words() {
3417 return (bitmap_size_in_bits() + BitsPerWord - 1) / BitsPerWord;
3418 }
3419 };
3420
3421 #ifndef PRODUCT
3422
3423 bool GCLabBitMapClosure::do_bit(size_t offset) {
3424 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
3425 guarantee(_cm->isMarked(oop(addr)), "it should be!");
3426 return true;
3427 }
3428
3429 #endif // PRODUCT
3430
3431 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
3432 private:
3433 bool _retired;
3434 bool _during_marking;
3435 GCLabBitMap _bitmap;
3436
3437 public:
3438 G1ParGCAllocBuffer() :
3439 ParGCAllocBuffer(ParallelGCG1AllocBufferSize / HeapWordSize),
3440 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
3441 _bitmap(G1CollectedHeap::heap()->reserved_region().start()),
3442 _retired(false)
3443 { }
3444
3445 inline bool mark(HeapWord* addr) {
3446 guarantee(use_local_bitmaps, "invariant");
3447 assert(_during_marking, "invariant");
3448 return _bitmap.mark(addr);
3449 }
3450
3451 inline void set_buf(HeapWord* buf) {
3452 if (use_local_bitmaps && _during_marking)
3453 _bitmap.set_buffer(buf);
3454 ParGCAllocBuffer::set_buf(buf);
3455 _retired = false;
3456 }
3457
3458 inline void retire(bool end_of_gc, bool retain) {
3459 if (_retired)
3460 return;
3461 if (use_local_bitmaps && _during_marking) {
3462 _bitmap.retire();
3463 }
3464 ParGCAllocBuffer::retire(end_of_gc, retain);
3465 _retired = true;
3466 }
3467 };
3468
3469
3470 class G1ParScanThreadState : public StackObj {
3471 protected:
3472 G1CollectedHeap* _g1h;
3473 RefToScanQueue* _refs;
3474
3475 typedef GrowableArray<oop*> OverflowQueue;
3476 OverflowQueue* _overflowed_refs;
3477
3478 G1ParGCAllocBuffer _alloc_buffers[GCAllocPurposeCount];
3479
3480 size_t _alloc_buffer_waste;
3481 size_t _undo_waste;
3482
3483 OopsInHeapRegionClosure* _evac_failure_cl;
3484 G1ParScanHeapEvacClosure* _evac_cl;
3485 G1ParScanPartialArrayClosure* _partial_scan_cl;
3486
3487 int _hash_seed;
3488 int _queue_num;
3489
3490 int _term_attempts;
3491 #if G1_DETAILED_STATS
3492 int _pushes, _pops, _steals, _steal_attempts;
3493 int _overflow_pushes;
3494 #endif
3495
3496 double _start;
3497 double _start_strong_roots;
3498 double _strong_roots_time;
3499 double _start_term;
3500 double _term_time;
3501
3502 // Map from young-age-index (0 == not young, 1 is youngest) to
3503 // surviving words. base is what we get back from the malloc call
3504 size_t* _surviving_young_words_base;
3505 // this points into the array, as we use the first few entries for padding
3506 size_t* _surviving_young_words;
3507
3508 #define PADDING_ELEM_NUM (64 / sizeof(size_t))
3509
3510 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
3511
3512 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
3513
3514 public:
3515 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
3516 : _g1h(g1h),
3517 _refs(g1h->task_queue(queue_num)),
3518 _hash_seed(17), _queue_num(queue_num),
3519 _term_attempts(0),
3520 #if G1_DETAILED_STATS
3521 _pushes(0), _pops(0), _steals(0),
3522 _steal_attempts(0), _overflow_pushes(0),
3523 #endif
3524 _strong_roots_time(0), _term_time(0),
3525 _alloc_buffer_waste(0), _undo_waste(0)
3526 {
3527 // we allocate G1YoungSurvRateNumRegions plus one entries, since
3528 // we "sacrifice" entry 0 to keep track of surviving bytes for
3529 // non-young regions (where the age is -1)
3530 // We also add a few elements at the beginning and at the end in
3531 // an attempt to eliminate cache contention
3532 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
3533 size_t array_length = PADDING_ELEM_NUM +
3534 real_length +
3535 PADDING_ELEM_NUM;
3536 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
3537 if (_surviving_young_words_base == NULL)
3538 vm_exit_out_of_memory(array_length * sizeof(size_t),
3539 "Not enough space for young surv histo.");
3540 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
3541 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
3542
3543 _overflowed_refs = new OverflowQueue(10);
3544
3545 _start = os::elapsedTime();
3546 }
3547
3548 ~G1ParScanThreadState() {
3549 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
3550 }
3551
3552 RefToScanQueue* refs() { return _refs; }
3553 OverflowQueue* overflowed_refs() { return _overflowed_refs; }
3554
3555 inline G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
3556 return &_alloc_buffers[purpose];
3557 }
3558
3559 size_t alloc_buffer_waste() { return _alloc_buffer_waste; }
3560 size_t undo_waste() { return _undo_waste; }
3561
3562 void push_on_queue(oop* ref) {
3563 if (!refs()->push(ref)) {
3564 overflowed_refs()->push(ref);
3565 IF_G1_DETAILED_STATS(note_overflow_push());
3566 } else {
3567 IF_G1_DETAILED_STATS(note_push());
3568 }
3569 }
3570
3571 void pop_from_queue(oop*& ref) {
3572 if (!refs()->pop_local(ref)) {
3573 ref = NULL;
3574 } else {
3575 IF_G1_DETAILED_STATS(note_pop());
3576 }
3577 }
3578
3579 void pop_from_overflow_queue(oop*& ref) {
3580 ref = overflowed_refs()->pop();
3581 }
3582
3583 int refs_to_scan() { return refs()->size(); }
3584 int overflowed_refs_to_scan() { return overflowed_refs()->length(); }
3585
3586 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
3587
3588 HeapWord* obj = NULL;
3589 if (word_sz * 100 <
3590 (size_t)(ParallelGCG1AllocBufferSize / HeapWordSize) *
3591 ParallelGCBufferWastePct) {
3592 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
3593 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
3594 alloc_buf->retire(false, false);
3595
3596 HeapWord* buf =
3597 _g1h->par_allocate_during_gc(purpose, ParallelGCG1AllocBufferSize / HeapWordSize);
3598 if (buf == NULL) return NULL; // Let caller handle allocation failure.
3599 // Otherwise.
3600 alloc_buf->set_buf(buf);
3601
3602 obj = alloc_buf->allocate(word_sz);
3603 assert(obj != NULL, "buffer was definitely big enough...");
3604 }
3605 else {
3606 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
3607 }
3608 return obj;
3609 }
3610
3611 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
3612 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
3613 if (obj != NULL) return obj;
3614 return allocate_slow(purpose, word_sz);
3615 }
3616
3617 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
3618 if (alloc_buffer(purpose)->contains(obj)) {
3619 guarantee(alloc_buffer(purpose)->contains(obj + word_sz - 1),
3620 "should contain whole object");
3621 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
3622 }
3623 else {
3624 SharedHeap::fill_region_with_object(MemRegion(obj, word_sz));
3625 add_to_undo_waste(word_sz);
3626 }
3627 }
3628
3629 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
3630 _evac_failure_cl = evac_failure_cl;
3631 }
3632 OopsInHeapRegionClosure* evac_failure_closure() {
3633 return _evac_failure_cl;
3634 }
3635
3636 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
3637 _evac_cl = evac_cl;
3638 }
3639
3640 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
3641 _partial_scan_cl = partial_scan_cl;
3642 }
3643
3644 int* hash_seed() { return &_hash_seed; }
3645 int queue_num() { return _queue_num; }
3646
3647 int term_attempts() { return _term_attempts; }
3648 void note_term_attempt() { _term_attempts++; }
3649
3650 #if G1_DETAILED_STATS
3651 int pushes() { return _pushes; }
3652 int pops() { return _pops; }
3653 int steals() { return _steals; }
3654 int steal_attempts() { return _steal_attempts; }
3655 int overflow_pushes() { return _overflow_pushes; }
3656
3657 void note_push() { _pushes++; }
3658 void note_pop() { _pops++; }
3659 void note_steal() { _steals++; }
3660 void note_steal_attempt() { _steal_attempts++; }
3661 void note_overflow_push() { _overflow_pushes++; }
3662 #endif
3663
3664 void start_strong_roots() {
3665 _start_strong_roots = os::elapsedTime();
3666 }
3667 void end_strong_roots() {
3668 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
3669 }
3670 double strong_roots_time() { return _strong_roots_time; }
3671
3672 void start_term_time() {
3673 note_term_attempt();
3674 _start_term = os::elapsedTime();
3675 }
3676 void end_term_time() {
3677 _term_time += (os::elapsedTime() - _start_term);
3678 }
3679 double term_time() { return _term_time; }
3680
3681 double elapsed() {
3682 return os::elapsedTime() - _start;
3683 }
3684
3685 size_t* surviving_young_words() {
3686 // We add on to hide entry 0 which accumulates surviving words for
3687 // age -1 regions (i.e. non-young ones)
3688 return _surviving_young_words;
3689 }
3690
3691 void retire_alloc_buffers() {
3692 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3693 size_t waste = _alloc_buffers[ap].words_remaining();
3694 add_to_alloc_buffer_waste(waste);
3695 _alloc_buffers[ap].retire(true, false);
3696 }
3697 }
3698
3699 void trim_queue() {
3700 while (refs_to_scan() > 0 || overflowed_refs_to_scan() > 0) {
3701 oop *ref_to_scan = NULL;
3702 if (overflowed_refs_to_scan() == 0) {
3703 pop_from_queue(ref_to_scan);
3704 } else {
3705 pop_from_overflow_queue(ref_to_scan);
3706 }
3707 if (ref_to_scan != NULL) {
3708 if ((intptr_t)ref_to_scan & G1_PARTIAL_ARRAY_MASK) {
3709 _partial_scan_cl->do_oop_nv(ref_to_scan);
3710 } else {
3711 // Note: we can use "raw" versions of "region_containing" because
3712 // "obj_to_scan" is definitely in the heap, and is not in a
3713 // humongous region.
3714 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
3715 _evac_cl->set_region(r);
3716 _evac_cl->do_oop_nv(ref_to_scan);
3717 }
3718 }
3719 }
3720 }
3721 };
3722
3723
3724 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
3725 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
3726 _par_scan_state(par_scan_state) { }
3727
3728 // This closure is applied to the fields of the objects that have just been copied.
3729 // Should probably be made inline and moved in g1OopClosures.inline.hpp.
3730 void G1ParScanClosure::do_oop_nv(oop* p) {
3731 oop obj = *p;
3732 if (obj != NULL) {
3733 if (_g1->obj_in_cs(obj)) {
3734 if (obj->is_forwarded()) {
3735 *p = obj->forwardee();
3736 } else {
3737 _par_scan_state->push_on_queue(p);
3738 return;
3739 }
3740 }
3741 _g1_rem->par_write_ref(_from, p, _par_scan_state->queue_num());
3742 }
3743 }
3744
3745 void G1ParCopyHelper::mark_forwardee(oop* p) {
3746 // This is called _after_ do_oop_work has been called, hence after
3747 // the object has been relocated to its new location and *p points
3748 // to its new location.
3749
3750 oop thisOop = *p;
3751 if (thisOop != NULL) {
3752 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(thisOop)),
3753 "shouldn't still be in the CSet if evacuation didn't fail.");
3754 HeapWord* addr = (HeapWord*)thisOop;
3755 if (_g1->is_in_g1_reserved(addr))
3756 _cm->grayRoot(oop(addr));
3757 }
3758 }
3759
3760 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
3761 size_t word_sz = old->size();
3762 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
3763 // +1 to make the -1 indexes valid...
3764 int young_index = from_region->young_index_in_cset()+1;
3765 assert( (from_region->is_young() && young_index > 0) ||
3766 (!from_region->is_young() && young_index == 0), "invariant" );
3767 G1CollectorPolicy* g1p = _g1->g1_policy();
3768 markOop m = old->mark();
3769 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, m->age(),
3770 word_sz);
3771 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
3772 oop obj = oop(obj_ptr);
3773
3774 if (obj_ptr == NULL) {
3775 // This will either forward-to-self, or detect that someone else has
3776 // installed a forwarding pointer.
3777 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
3778 return _g1->handle_evacuation_failure_par(cl, old);
3779 }
3780
3781 oop forward_ptr = old->forward_to_atomic(obj);
3782 if (forward_ptr == NULL) {
3783 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
3784 obj->set_mark(m);
3785 if (g1p->track_object_age(alloc_purpose)) {
3786 obj->incr_age();
3787 }
3788 // preserve "next" mark bit
3789 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
3790 if (!use_local_bitmaps ||
3791 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
3792 // if we couldn't mark it on the local bitmap (this happens when
3793 // the object was not allocated in the GCLab), we have to bite
3794 // the bullet and do the standard parallel mark
3795 _cm->markAndGrayObjectIfNecessary(obj);
3796 }
3797 #if 1
3798 if (_g1->isMarkedNext(old)) {
3799 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
3800 }
3801 #endif
3802 }
3803
3804 size_t* surv_young_words = _par_scan_state->surviving_young_words();
3805 surv_young_words[young_index] += word_sz;
3806
3807 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
3808 arrayOop(old)->set_length(0);
3809 _par_scan_state->push_on_queue((oop*) ((intptr_t)old | G1_PARTIAL_ARRAY_MASK));
3810 } else {
3811 _scanner->set_region(_g1->heap_region_containing(obj));
3812 obj->oop_iterate_backwards(_scanner);
3813 }
3814 } else {
3815 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
3816 obj = forward_ptr;
3817 }
3818 return obj;
3819 }
3820
3821 template<bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee>
3822 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_forwardee>::do_oop_work(oop* p) {
3823 oop obj = *p;
3824 assert(barrier != G1BarrierRS || obj != NULL,
3825 "Precondition: G1BarrierRS implies obj is nonNull");
3826
3827 if (obj != NULL) {
3828 if (_g1->obj_in_cs(obj)) {
3829 #if G1_REM_SET_LOGGING
3830 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" into CS.",
3831 p, (void*) obj);
3832 #endif
3833 if (obj->is_forwarded()) {
3834 *p = obj->forwardee();
3835 } else {
3836 *p = copy_to_survivor_space(obj);
3837 }
3838 // When scanning the RS, we only care about objs in CS.
3839 if (barrier == G1BarrierRS) {
3840 _g1_rem->par_write_ref(_from, p, _par_scan_state->queue_num());
3841 }
3842 }
3843 // When scanning moved objs, must look at all oops.
3844 if (barrier == G1BarrierEvac) {
3845 _g1_rem->par_write_ref(_from, p, _par_scan_state->queue_num());
3846 }
3847
3848 if (do_gen_barrier) {
3849 par_do_barrier(p);
3850 }
3851 }
3852 }
3853
3854 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
3855
3856 template <class T> void G1ParScanPartialArrayClosure::process_array_chunk(
3857 oop obj, int start, int end) {
3858 // process our set of indices (include header in first chunk)
3859 assert(start < end, "invariant");
3860 T* const base = (T*)objArrayOop(obj)->base();
3861 T* const start_addr = base + start;
3862 T* const end_addr = base + end;
3863 MemRegion mr((HeapWord*)start_addr, (HeapWord*)end_addr);
3864 _scanner.set_region(_g1->heap_region_containing(obj));
3865 obj->oop_iterate(&_scanner, mr);
3866 }
3867
3868 void G1ParScanPartialArrayClosure::do_oop_nv(oop* p) {
3869 assert(!UseCompressedOops, "Needs to be fixed to work with compressed oops");
3870 oop old = oop((intptr_t)p & ~G1_PARTIAL_ARRAY_MASK);
3871 assert(old->is_objArray(), "must be obj array");
3872 assert(old->is_forwarded(), "must be forwarded");
3873 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
3874
3875 objArrayOop obj = objArrayOop(old->forwardee());
3876 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
3877 // Process ParGCArrayScanChunk elements now
3878 // and push the remainder back onto queue
3879 int start = arrayOop(old)->length();
3880 int end = obj->length();
3881 int remainder = end - start;
3882 assert(start <= end, "just checking");
3883 if (remainder > 2 * ParGCArrayScanChunk) {
3884 // Test above combines last partial chunk with a full chunk
3885 end = start + ParGCArrayScanChunk;
3886 arrayOop(old)->set_length(end);
3887 // Push remainder.
3888 _par_scan_state->push_on_queue((oop*) ((intptr_t) old | G1_PARTIAL_ARRAY_MASK));
3889 } else {
3890 // Restore length so that the heap remains parsable in
3891 // case of evacuation failure.
3892 arrayOop(old)->set_length(end);
3893 }
3894
3895 // process our set of indices (include header in first chunk)
3896 process_array_chunk<oop>(obj, start, end);
3897 oop* start_addr = start == 0 ? (oop*)obj : obj->obj_at_addr<oop>(start);
3898 oop* end_addr = (oop*)(obj->base()) + end; // obj_at_addr(end) asserts end < length
3899 MemRegion mr((HeapWord*)start_addr, (HeapWord*)end_addr);
3900 _scanner.set_region(_g1->heap_region_containing(obj));
3901 obj->oop_iterate(&_scanner, mr);
3902 }
3903
3904 int G1ScanAndBalanceClosure::_nq = 0;
3905
3906 class G1ParEvacuateFollowersClosure : public VoidClosure {
3907 protected:
3908 G1CollectedHeap* _g1h;
3909 G1ParScanThreadState* _par_scan_state;
3910 RefToScanQueueSet* _queues;
3911 ParallelTaskTerminator* _terminator;
3912
3913 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3914 RefToScanQueueSet* queues() { return _queues; }
3915 ParallelTaskTerminator* terminator() { return _terminator; }
3916
3917 public:
3918 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
3919 G1ParScanThreadState* par_scan_state,
3920 RefToScanQueueSet* queues,
3921 ParallelTaskTerminator* terminator)
3922 : _g1h(g1h), _par_scan_state(par_scan_state),
3923 _queues(queues), _terminator(terminator) {}
3924
3925 void do_void() {
3926 G1ParScanThreadState* pss = par_scan_state();
3927 while (true) {
3928 oop* ref_to_scan;
3929 pss->trim_queue();
3930 IF_G1_DETAILED_STATS(pss->note_steal_attempt());
3931 if (queues()->steal(pss->queue_num(),
3932 pss->hash_seed(),
3933 ref_to_scan)) {
3934 IF_G1_DETAILED_STATS(pss->note_steal());
3935 pss->push_on_queue(ref_to_scan);
3936 continue;
3937 }
3938 pss->start_term_time();
3939 if (terminator()->offer_termination()) break;
3940 pss->end_term_time();
3941 }
3942 pss->end_term_time();
3943 pss->retire_alloc_buffers();
3944 }
3945 };
3946
3947 class G1ParTask : public AbstractGangTask {
3948 protected:
3949 G1CollectedHeap* _g1h;
3950 RefToScanQueueSet *_queues;
3951 ParallelTaskTerminator _terminator;
3952
3953 Mutex _stats_lock;
3954 Mutex* stats_lock() { return &_stats_lock; }
3955
3956 size_t getNCards() {
3957 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
3958 / G1BlockOffsetSharedArray::N_bytes;
3959 }
3960
3961 public:
3962 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
3963 : AbstractGangTask("G1 collection"),
3964 _g1h(g1h),
3965 _queues(task_queues),
3966 _terminator(workers, _queues),
3967 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
3968 {}
3969
3970 RefToScanQueueSet* queues() { return _queues; }
3971
3972 RefToScanQueue *work_queue(int i) {
3973 return queues()->queue(i);
3974 }
3975
3976 void work(int i) {
3977 ResourceMark rm;
3978 HandleMark hm;
3979
3980 G1ParScanThreadState pss(_g1h, i);
3981 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
3982 G1ParScanHeapEvacClosure evac_failure_cl(_g1h, &pss);
3983 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
3984
3985 pss.set_evac_closure(&scan_evac_cl);
3986 pss.set_evac_failure_closure(&evac_failure_cl);
3987 pss.set_partial_scan_closure(&partial_scan_cl);
3988
3989 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
3990 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
3991 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
3992 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
3993 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
3994 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
3995
3996 OopsInHeapRegionClosure *scan_root_cl;
3997 OopsInHeapRegionClosure *scan_perm_cl;
3998 OopsInHeapRegionClosure *scan_so_cl;
3999
4000 if (_g1h->g1_policy()->should_initiate_conc_mark()) {
4001 scan_root_cl = &scan_mark_root_cl;
4002 scan_perm_cl = &scan_mark_perm_cl;
4003 scan_so_cl = &scan_mark_heap_rs_cl;
4004 } else {
4005 scan_root_cl = &only_scan_root_cl;
4006 scan_perm_cl = &only_scan_perm_cl;
4007 scan_so_cl = &only_scan_heap_rs_cl;
4008 }
4009
4010 pss.start_strong_roots();
4011 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4012 SharedHeap::SO_AllClasses,
4013 scan_root_cl,
4014 &only_scan_heap_rs_cl,
4015 scan_so_cl,
4016 scan_perm_cl,
4017 i);
4018 pss.end_strong_roots();
4019 {
4020 double start = os::elapsedTime();
4021 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4022 evac.do_void();
4023 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4024 double term_ms = pss.term_time()*1000.0;
4025 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4026 _g1h->g1_policy()->record_termination_time(i, term_ms);
4027 }
4028 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4029
4030 // Clean up any par-expanded rem sets.
4031 HeapRegionRemSet::par_cleanup();
4032
4033 MutexLocker x(stats_lock());
4034 if (ParallelGCVerbose) {
4035 gclog_or_tty->print("Thread %d complete:\n", i);
4036 #if G1_DETAILED_STATS
4037 gclog_or_tty->print(" Pushes: %7d Pops: %7d Overflows: %7d Steals %7d (in %d attempts)\n",
4038 pss.pushes(),
4039 pss.pops(),
4040 pss.overflow_pushes(),
4041 pss.steals(),
4042 pss.steal_attempts());
4043 #endif
4044 double elapsed = pss.elapsed();
4045 double strong_roots = pss.strong_roots_time();
4046 double term = pss.term_time();
4047 gclog_or_tty->print(" Elapsed: %7.2f ms.\n"
4048 " Strong roots: %7.2f ms (%6.2f%%)\n"
4049 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n",
4050 elapsed * 1000.0,
4051 strong_roots * 1000.0, (strong_roots*100.0/elapsed),
4052 term * 1000.0, (term*100.0/elapsed),
4053 pss.term_attempts());
4054 size_t total_waste = pss.alloc_buffer_waste() + pss.undo_waste();
4055 gclog_or_tty->print(" Waste: %8dK\n"
4056 " Alloc Buffer: %8dK\n"
4057 " Undo: %8dK\n",
4058 (total_waste * HeapWordSize) / K,
4059 (pss.alloc_buffer_waste() * HeapWordSize) / K,
4060 (pss.undo_waste() * HeapWordSize) / K);
4061 }
4062
4063 assert(pss.refs_to_scan() == 0, "Task queue should be empty");
4064 assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
4065 }
4066 };
4067
4068 // *** Common G1 Evacuation Stuff
4069
4070 class G1CountClosure: public OopsInHeapRegionClosure {
4071 public:
4072 int n;
4073 G1CountClosure() : n(0) {}
4074 void do_oop(narrowOop* p) {
4075 guarantee(false, "NYI");
4076 }
4077 void do_oop(oop* p) {
4078 oop obj = *p;
4079 assert(obj != NULL && G1CollectedHeap::heap()->obj_in_cs(obj),
4080 "Rem set closure called on non-rem-set pointer.");
4081 n++;
4082 }
4083 };
4084
4085 static G1CountClosure count_closure;
4086
4087 void
4088 G1CollectedHeap::
4089 g1_process_strong_roots(bool collecting_perm_gen,
4090 SharedHeap::ScanningOption so,
4091 OopClosure* scan_non_heap_roots,
4092 OopsInHeapRegionClosure* scan_rs,
4093 OopsInHeapRegionClosure* scan_so,
4094 OopsInGenClosure* scan_perm,
4095 int worker_i) {
4096 // First scan the strong roots, including the perm gen.
4097 double ext_roots_start = os::elapsedTime();
4098 double closure_app_time_sec = 0.0;
4099
4100 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4101 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4102 buf_scan_perm.set_generation(perm_gen());
4103
4104 process_strong_roots(collecting_perm_gen, so,
4105 &buf_scan_non_heap_roots,
4106 &buf_scan_perm);
4107 // Finish up any enqueued closure apps.
4108 buf_scan_non_heap_roots.done();
4109 buf_scan_perm.done();
4110 double ext_roots_end = os::elapsedTime();
4111 g1_policy()->reset_obj_copy_time(worker_i);
4112 double obj_copy_time_sec =
4113 buf_scan_non_heap_roots.closure_app_seconds() +
4114 buf_scan_perm.closure_app_seconds();
4115 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4116 double ext_root_time_ms =
4117 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4118 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4119
4120 // Scan strong roots in mark stack.
4121 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4122 concurrent_mark()->oops_do(scan_non_heap_roots);
4123 }
4124 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4125 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4126
4127 // XXX What should this be doing in the parallel case?
4128 g1_policy()->record_collection_pause_end_CH_strong_roots();
4129 if (G1VerifyRemSet) {
4130 // :::: FIXME ::::
4131 // The stupid remembered set doesn't know how to filter out dead
4132 // objects, which the smart one does, and so when it is created
4133 // and then compared the number of entries in each differs and
4134 // the verification code fails.
4135 guarantee(false, "verification code is broken, see note");
4136
4137 // Let's make sure that the current rem set agrees with the stupidest
4138 // one possible!
4139 bool refs_enabled = ref_processor()->discovery_enabled();
4140 if (refs_enabled) ref_processor()->disable_discovery();
4141 StupidG1RemSet stupid(this);
4142 count_closure.n = 0;
4143 stupid.oops_into_collection_set_do(&count_closure, worker_i);
4144 int stupid_n = count_closure.n;
4145 count_closure.n = 0;
4146 g1_rem_set()->oops_into_collection_set_do(&count_closure, worker_i);
4147 guarantee(count_closure.n == stupid_n, "Old and new rem sets differ.");
4148 gclog_or_tty->print_cr("\nFound %d pointers in heap RS.", count_closure.n);
4149 if (refs_enabled) ref_processor()->enable_discovery();
4150 }
4151 if (scan_so != NULL) {
4152 scan_scan_only_set(scan_so, worker_i);
4153 }
4154 // Now scan the complement of the collection set.
4155 if (scan_rs != NULL) {
4156 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4157 }
4158 // Finish with the ref_processor roots.
4159 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4160 ref_processor()->oops_do(scan_non_heap_roots);
4161 }
4162 g1_policy()->record_collection_pause_end_G1_strong_roots();
4163 _process_strong_tasks->all_tasks_completed();
4164 }
4165
4166 void
4167 G1CollectedHeap::scan_scan_only_region(HeapRegion* r,
4168 OopsInHeapRegionClosure* oc,
4169 int worker_i) {
4170 HeapWord* startAddr = r->bottom();
4171 HeapWord* endAddr = r->used_region().end();
4172
4173 oc->set_region(r);
4174
4175 HeapWord* p = r->bottom();
4176 HeapWord* t = r->top();
4177 guarantee( p == r->next_top_at_mark_start(), "invariant" );
4178 while (p < t) {
4179 oop obj = oop(p);
4180 p += obj->oop_iterate(oc);
4181 }
4182 }
4183
4184 void
4185 G1CollectedHeap::scan_scan_only_set(OopsInHeapRegionClosure* oc,
4186 int worker_i) {
4187 double start = os::elapsedTime();
4188
4189 BufferingOopsInHeapRegionClosure boc(oc);
4190
4191 FilterInHeapRegionAndIntoCSClosure scan_only(this, &boc);
4192 FilterAndMarkInHeapRegionAndIntoCSClosure scan_and_mark(this, &boc, concurrent_mark());
4193
4194 OopsInHeapRegionClosure *foc;
4195 if (g1_policy()->should_initiate_conc_mark())
4196 foc = &scan_and_mark;
4197 else
4198 foc = &scan_only;
4199
4200 HeapRegion* hr;
4201 int n = 0;
4202 while ((hr = _young_list->par_get_next_scan_only_region()) != NULL) {
4203 scan_scan_only_region(hr, foc, worker_i);
4204 ++n;
4205 }
4206 boc.done();
4207
4208 double closure_app_s = boc.closure_app_seconds();
4209 g1_policy()->record_obj_copy_time(worker_i, closure_app_s * 1000.0);
4210 double ms = (os::elapsedTime() - start - closure_app_s)*1000.0;
4211 g1_policy()->record_scan_only_time(worker_i, ms, n);
4212 }
4213
4214 void
4215 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4216 OopClosure* non_root_closure) {
4217 SharedHeap::process_weak_roots(root_closure, non_root_closure);
4218 }
4219
4220
4221 class SaveMarksClosure: public HeapRegionClosure {
4222 public:
4223 bool doHeapRegion(HeapRegion* r) {
4224 r->save_marks();
4225 return false;
4226 }
4227 };
4228
4229 void G1CollectedHeap::save_marks() {
4230 if (ParallelGCThreads == 0) {
4231 SaveMarksClosure sm;
4232 heap_region_iterate(&sm);
4233 }
4234 // We do this even in the parallel case
4235 perm_gen()->save_marks();
4236 }
4237
4238 void G1CollectedHeap::evacuate_collection_set() {
4239 set_evacuation_failed(false);
4240
4241 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4242 concurrent_g1_refine()->set_use_cache(false);
4243 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4244
4245 set_par_threads(n_workers);
4246 G1ParTask g1_par_task(this, n_workers, _task_queues);
4247
4248 init_for_evac_failure(NULL);
4249
4250 change_strong_roots_parity(); // In preparation for parallel strong roots.
4251 rem_set()->prepare_for_younger_refs_iterate(true);
4252 double start_par = os::elapsedTime();
4253
4254 if (ParallelGCThreads > 0) {
4255 // The individual threads will set their evac-failure closures.
4256 workers()->run_task(&g1_par_task);
4257 } else {
4258 g1_par_task.work(0);
4259 }
4260
4261 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4262 g1_policy()->record_par_time(par_time);
4263 set_par_threads(0);
4264 // Is this the right thing to do here? We don't save marks
4265 // on individual heap regions when we allocate from
4266 // them in parallel, so this seems like the correct place for this.
4267 all_alloc_regions_note_end_of_copying();
4268 {
4269 G1IsAliveClosure is_alive(this);
4270 G1KeepAliveClosure keep_alive(this);
4271 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4272 }
4273
4274 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4275 concurrent_g1_refine()->set_use_cache(true);
4276
4277 finalize_for_evac_failure();
4278
4279 // Must do this before removing self-forwarding pointers, which clears
4280 // the per-region evac-failure flags.
4281 concurrent_mark()->complete_marking_in_collection_set();
4282
4283 if (evacuation_failed()) {
4284 remove_self_forwarding_pointers();
4285
4286 if (PrintGCDetails) {
4287 gclog_or_tty->print(" (evacuation failed)");
4288 } else if (PrintGC) {
4289 gclog_or_tty->print("--");
4290 }
4291 }
4292
4293 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4294 }
4295
4296 void G1CollectedHeap::free_region(HeapRegion* hr) {
4297 size_t pre_used = 0;
4298 size_t cleared_h_regions = 0;
4299 size_t freed_regions = 0;
4300 UncleanRegionList local_list;
4301
4302 HeapWord* start = hr->bottom();
4303 HeapWord* end = hr->prev_top_at_mark_start();
4304 size_t used_bytes = hr->used();
4305 size_t live_bytes = hr->max_live_bytes();
4306 if (used_bytes > 0) {
4307 guarantee( live_bytes <= used_bytes, "invariant" );
4308 } else {
4309 guarantee( live_bytes == 0, "invariant" );
4310 }
4311
4312 size_t garbage_bytes = used_bytes - live_bytes;
4313 if (garbage_bytes > 0)
4314 g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
4315
4316 free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
4317 &local_list);
4318 finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
4319 &local_list);
4320 }
4321
4322 void
4323 G1CollectedHeap::free_region_work(HeapRegion* hr,
4324 size_t& pre_used,
4325 size_t& cleared_h_regions,
4326 size_t& freed_regions,
4327 UncleanRegionList* list,
4328 bool par) {
4329 assert(!hr->popular(), "should not free popular regions");
4330 pre_used += hr->used();
4331 if (hr->isHumongous()) {
4332 assert(hr->startsHumongous(),
4333 "Only the start of a humongous region should be freed.");
4334 int ind = _hrs->find(hr);
4335 assert(ind != -1, "Should have an index.");
4336 // Clear the start region.
4337 hr->hr_clear(par, true /*clear_space*/);
4338 list->insert_before_head(hr);
4339 cleared_h_regions++;
4340 freed_regions++;
4341 // Clear any continued regions.
4342 ind++;
4343 while ((size_t)ind < n_regions()) {
4344 HeapRegion* hrc = _hrs->at(ind);
4345 if (!hrc->continuesHumongous()) break;
4346 // Otherwise, does continue the H region.
4347 assert(hrc->humongous_start_region() == hr, "Huh?");
4348 hrc->hr_clear(par, true /*clear_space*/);
4349 cleared_h_regions++;
4350 freed_regions++;
4351 list->insert_before_head(hrc);
4352 ind++;
4353 }
4354 } else {
4355 hr->hr_clear(par, true /*clear_space*/);
4356 list->insert_before_head(hr);
4357 freed_regions++;
4358 // If we're using clear2, this should not be enabled.
4359 // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
4360 }
4361 }
4362
4363 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
4364 size_t cleared_h_regions,
4365 size_t freed_regions,
4366 UncleanRegionList* list) {
4367 if (list != NULL && list->sz() > 0) {
4368 prepend_region_list_on_unclean_list(list);
4369 }
4370 // Acquire a lock, if we're parallel, to update possibly-shared
4371 // variables.
4372 Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
4373 {
4374 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4375 _summary_bytes_used -= pre_used;
4376 _num_humongous_regions -= (int) cleared_h_regions;
4377 _free_regions += freed_regions;
4378 }
4379 }
4380
4381
4382 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4383 while (list != NULL) {
4384 guarantee( list->is_young(), "invariant" );
4385
4386 HeapWord* bottom = list->bottom();
4387 HeapWord* end = list->end();
4388 MemRegion mr(bottom, end);
4389 ct_bs->dirty(mr);
4390
4391 list = list->get_next_young_region();
4392 }
4393 }
4394
4395 void G1CollectedHeap::cleanUpCardTable() {
4396 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
4397 double start = os::elapsedTime();
4398
4399 ct_bs->clear(_g1_committed);
4400
4401 // now, redirty the cards of the scan-only and survivor regions
4402 // (it seemed faster to do it this way, instead of iterating over
4403 // all regions and then clearing / dirtying as approprite)
4404 dirtyCardsForYoungRegions(ct_bs, _young_list->first_scan_only_region());
4405 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
4406
4407 double elapsed = os::elapsedTime() - start;
4408 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
4409 }
4410
4411
4412 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
4413 // First do any popular regions.
4414 HeapRegion* hr;
4415 while ((hr = popular_region_to_evac()) != NULL) {
4416 evac_popular_region(hr);
4417 }
4418 // Now do heuristic pauses.
4419 if (g1_policy()->should_do_collection_pause(word_size)) {
4420 do_collection_pause();
4421 }
4422 }
4423
4424 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
4425 double young_time_ms = 0.0;
4426 double non_young_time_ms = 0.0;
4427
4428 G1CollectorPolicy* policy = g1_policy();
4429
4430 double start_sec = os::elapsedTime();
4431 bool non_young = true;
4432
4433 HeapRegion* cur = cs_head;
4434 int age_bound = -1;
4435 size_t rs_lengths = 0;
4436
4437 while (cur != NULL) {
4438 if (non_young) {
4439 if (cur->is_young()) {
4440 double end_sec = os::elapsedTime();
4441 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4442 non_young_time_ms += elapsed_ms;
4443
4444 start_sec = os::elapsedTime();
4445 non_young = false;
4446 }
4447 } else {
4448 if (!cur->is_on_free_list()) {
4449 double end_sec = os::elapsedTime();
4450 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4451 young_time_ms += elapsed_ms;
4452
4453 start_sec = os::elapsedTime();
4454 non_young = true;
4455 }
4456 }
4457
4458 rs_lengths += cur->rem_set()->occupied();
4459
4460 HeapRegion* next = cur->next_in_collection_set();
4461 assert(cur->in_collection_set(), "bad CS");
4462 cur->set_next_in_collection_set(NULL);
4463 cur->set_in_collection_set(false);
4464
4465 if (cur->is_young()) {
4466 int index = cur->young_index_in_cset();
4467 guarantee( index != -1, "invariant" );
4468 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
4469 size_t words_survived = _surviving_young_words[index];
4470 cur->record_surv_words_in_group(words_survived);
4471 } else {
4472 int index = cur->young_index_in_cset();
4473 guarantee( index == -1, "invariant" );
4474 }
4475
4476 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4477 (!cur->is_young() && cur->young_index_in_cset() == -1),
4478 "invariant" );
4479
4480 if (!cur->evacuation_failed()) {
4481 // And the region is empty.
4482 assert(!cur->is_empty(),
4483 "Should not have empty regions in a CS.");
4484 free_region(cur);
4485 } else {
4486 guarantee( !cur->is_scan_only(), "should not be scan only" );
4487 cur->uninstall_surv_rate_group();
4488 if (cur->is_young())
4489 cur->set_young_index_in_cset(-1);
4490 cur->set_not_young();
4491 cur->set_evacuation_failed(false);
4492 }
4493 cur = next;
4494 }
4495
4496 policy->record_max_rs_lengths(rs_lengths);
4497 policy->cset_regions_freed();
4498
4499 double end_sec = os::elapsedTime();
4500 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4501 if (non_young)
4502 non_young_time_ms += elapsed_ms;
4503 else
4504 young_time_ms += elapsed_ms;
4505
4506 policy->record_young_free_cset_time_ms(young_time_ms);
4507 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
4508 }
4509
4510 HeapRegion*
4511 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
4512 assert(ZF_mon->owned_by_self(), "Precondition");
4513 HeapRegion* res = pop_unclean_region_list_locked();
4514 if (res != NULL) {
4515 assert(!res->continuesHumongous() &&
4516 res->zero_fill_state() != HeapRegion::Allocated,
4517 "Only free regions on unclean list.");
4518 if (zero_filled) {
4519 res->ensure_zero_filled_locked();
4520 res->set_zero_fill_allocated();
4521 }
4522 }
4523 return res;
4524 }
4525
4526 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
4527 MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
4528 return alloc_region_from_unclean_list_locked(zero_filled);
4529 }
4530
4531 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
4532 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4533 put_region_on_unclean_list_locked(r);
4534 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4535 }
4536
4537 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
4538 MutexLockerEx x(Cleanup_mon);
4539 set_unclean_regions_coming_locked(b);
4540 }
4541
4542 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
4543 assert(Cleanup_mon->owned_by_self(), "Precondition");
4544 _unclean_regions_coming = b;
4545 // Wake up mutator threads that might be waiting for completeCleanup to
4546 // finish.
4547 if (!b) Cleanup_mon->notify_all();
4548 }
4549
4550 void G1CollectedHeap::wait_for_cleanup_complete() {
4551 MutexLockerEx x(Cleanup_mon);
4552 wait_for_cleanup_complete_locked();
4553 }
4554
4555 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
4556 assert(Cleanup_mon->owned_by_self(), "precondition");
4557 while (_unclean_regions_coming) {
4558 Cleanup_mon->wait();
4559 }
4560 }
4561
4562 void
4563 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
4564 assert(ZF_mon->owned_by_self(), "precondition.");
4565 _unclean_region_list.insert_before_head(r);
4566 }
4567
4568 void
4569 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
4570 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4571 prepend_region_list_on_unclean_list_locked(list);
4572 if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
4573 }
4574
4575 void
4576 G1CollectedHeap::
4577 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
4578 assert(ZF_mon->owned_by_self(), "precondition.");
4579 _unclean_region_list.prepend_list(list);
4580 }
4581
4582 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
4583 assert(ZF_mon->owned_by_self(), "precondition.");
4584 HeapRegion* res = _unclean_region_list.pop();
4585 if (res != NULL) {
4586 // Inform ZF thread that there's a new unclean head.
4587 if (_unclean_region_list.hd() != NULL && should_zf())
4588 ZF_mon->notify_all();
4589 }
4590 return res;
4591 }
4592
4593 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
4594 assert(ZF_mon->owned_by_self(), "precondition.");
4595 return _unclean_region_list.hd();
4596 }
4597
4598
4599 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
4600 assert(ZF_mon->owned_by_self(), "Precondition");
4601 HeapRegion* r = peek_unclean_region_list_locked();
4602 if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
4603 // Result of below must be equal to "r", since we hold the lock.
4604 (void)pop_unclean_region_list_locked();
4605 put_free_region_on_list_locked(r);
4606 return true;
4607 } else {
4608 return false;
4609 }
4610 }
4611
4612 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
4613 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4614 return move_cleaned_region_to_free_list_locked();
4615 }
4616
4617
4618 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
4619 assert(ZF_mon->owned_by_self(), "precondition.");
4620 assert(_free_region_list_size == free_region_list_length(), "Inv");
4621 assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
4622 "Regions on free list must be zero filled");
4623 assert(!r->isHumongous(), "Must not be humongous.");
4624 assert(r->is_empty(), "Better be empty");
4625 assert(!r->is_on_free_list(),
4626 "Better not already be on free list");
4627 assert(!r->is_on_unclean_list(),
4628 "Better not already be on unclean list");
4629 r->set_on_free_list(true);
4630 r->set_next_on_free_list(_free_region_list);
4631 _free_region_list = r;
4632 _free_region_list_size++;
4633 assert(_free_region_list_size == free_region_list_length(), "Inv");
4634 }
4635
4636 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
4637 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4638 put_free_region_on_list_locked(r);
4639 }
4640
4641 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
4642 assert(ZF_mon->owned_by_self(), "precondition.");
4643 assert(_free_region_list_size == free_region_list_length(), "Inv");
4644 HeapRegion* res = _free_region_list;
4645 if (res != NULL) {
4646 _free_region_list = res->next_from_free_list();
4647 _free_region_list_size--;
4648 res->set_on_free_list(false);
4649 res->set_next_on_free_list(NULL);
4650 assert(_free_region_list_size == free_region_list_length(), "Inv");
4651 }
4652 return res;
4653 }
4654
4655
4656 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
4657 // By self, or on behalf of self.
4658 assert(Heap_lock->is_locked(), "Precondition");
4659 HeapRegion* res = NULL;
4660 bool first = true;
4661 while (res == NULL) {
4662 if (zero_filled || !first) {
4663 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4664 res = pop_free_region_list_locked();
4665 if (res != NULL) {
4666 assert(!res->zero_fill_is_allocated(),
4667 "No allocated regions on free list.");
4668 res->set_zero_fill_allocated();
4669 } else if (!first) {
4670 break; // We tried both, time to return NULL.
4671 }
4672 }
4673
4674 if (res == NULL) {
4675 res = alloc_region_from_unclean_list(zero_filled);
4676 }
4677 assert(res == NULL ||
4678 !zero_filled ||
4679 res->zero_fill_is_allocated(),
4680 "We must have allocated the region we're returning");
4681 first = false;
4682 }
4683 return res;
4684 }
4685
4686 void G1CollectedHeap::remove_allocated_regions_from_lists() {
4687 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4688 {
4689 HeapRegion* prev = NULL;
4690 HeapRegion* cur = _unclean_region_list.hd();
4691 while (cur != NULL) {
4692 HeapRegion* next = cur->next_from_unclean_list();
4693 if (cur->zero_fill_is_allocated()) {
4694 // Remove from the list.
4695 if (prev == NULL) {
4696 (void)_unclean_region_list.pop();
4697 } else {
4698 _unclean_region_list.delete_after(prev);
4699 }
4700 cur->set_on_unclean_list(false);
4701 cur->set_next_on_unclean_list(NULL);
4702 } else {
4703 prev = cur;
4704 }
4705 cur = next;
4706 }
4707 assert(_unclean_region_list.sz() == unclean_region_list_length(),
4708 "Inv");
4709 }
4710
4711 {
4712 HeapRegion* prev = NULL;
4713 HeapRegion* cur = _free_region_list;
4714 while (cur != NULL) {
4715 HeapRegion* next = cur->next_from_free_list();
4716 if (cur->zero_fill_is_allocated()) {
4717 // Remove from the list.
4718 if (prev == NULL) {
4719 _free_region_list = cur->next_from_free_list();
4720 } else {
4721 prev->set_next_on_free_list(cur->next_from_free_list());
4722 }
4723 cur->set_on_free_list(false);
4724 cur->set_next_on_free_list(NULL);
4725 _free_region_list_size--;
4726 } else {
4727 prev = cur;
4728 }
4729 cur = next;
4730 }
4731 assert(_free_region_list_size == free_region_list_length(), "Inv");
4732 }
4733 }
4734
4735 bool G1CollectedHeap::verify_region_lists() {
4736 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4737 return verify_region_lists_locked();
4738 }
4739
4740 bool G1CollectedHeap::verify_region_lists_locked() {
4741 HeapRegion* unclean = _unclean_region_list.hd();
4742 while (unclean != NULL) {
4743 guarantee(unclean->is_on_unclean_list(), "Well, it is!");
4744 guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
4745 guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
4746 "Everything else is possible.");
4747 unclean = unclean->next_from_unclean_list();
4748 }
4749 guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
4750
4751 HeapRegion* free_r = _free_region_list;
4752 while (free_r != NULL) {
4753 assert(free_r->is_on_free_list(), "Well, it is!");
4754 assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
4755 switch (free_r->zero_fill_state()) {
4756 case HeapRegion::NotZeroFilled:
4757 case HeapRegion::ZeroFilling:
4758 guarantee(false, "Should not be on free list.");
4759 break;
4760 default:
4761 // Everything else is possible.
4762 break;
4763 }
4764 free_r = free_r->next_from_free_list();
4765 }
4766 guarantee(_free_region_list_size == free_region_list_length(), "Inv");
4767 // If we didn't do an assertion...
4768 return true;
4769 }
4770
4771 size_t G1CollectedHeap::free_region_list_length() {
4772 assert(ZF_mon->owned_by_self(), "precondition.");
4773 size_t len = 0;
4774 HeapRegion* cur = _free_region_list;
4775 while (cur != NULL) {
4776 len++;
4777 cur = cur->next_from_free_list();
4778 }
4779 return len;
4780 }
4781
4782 size_t G1CollectedHeap::unclean_region_list_length() {
4783 assert(ZF_mon->owned_by_self(), "precondition.");
4784 return _unclean_region_list.length();
4785 }
4786
4787 size_t G1CollectedHeap::n_regions() {
4788 return _hrs->length();
4789 }
4790
4791 size_t G1CollectedHeap::max_regions() {
4792 return
4793 (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
4794 HeapRegion::GrainBytes;
4795 }
4796
4797 size_t G1CollectedHeap::free_regions() {
4798 /* Possibly-expensive assert.
4799 assert(_free_regions == count_free_regions(),
4800 "_free_regions is off.");
4801 */
4802 return _free_regions;
4803 }
4804
4805 bool G1CollectedHeap::should_zf() {
4806 return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
4807 }
4808
4809 class RegionCounter: public HeapRegionClosure {
4810 size_t _n;
4811 public:
4812 RegionCounter() : _n(0) {}
4813 bool doHeapRegion(HeapRegion* r) {
4814 if (r->is_empty() && !r->popular()) {
4815 assert(!r->isHumongous(), "H regions should not be empty.");
4816 _n++;
4817 }
4818 return false;
4819 }
4820 int res() { return (int) _n; }
4821 };
4822
4823 size_t G1CollectedHeap::count_free_regions() {
4824 RegionCounter rc;
4825 heap_region_iterate(&rc);
4826 size_t n = rc.res();
4827 if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
4828 n--;
4829 return n;
4830 }
4831
4832 size_t G1CollectedHeap::count_free_regions_list() {
4833 size_t n = 0;
4834 size_t o = 0;
4835 ZF_mon->lock_without_safepoint_check();
4836 HeapRegion* cur = _free_region_list;
4837 while (cur != NULL) {
4838 cur = cur->next_from_free_list();
4839 n++;
4840 }
4841 size_t m = unclean_region_list_length();
4842 ZF_mon->unlock();
4843 return n + m;
4844 }
4845
4846 bool G1CollectedHeap::should_set_young_locked() {
4847 assert(heap_lock_held_for_gc(),
4848 "the heap lock should already be held by or for this thread");
4849 return (g1_policy()->in_young_gc_mode() &&
4850 g1_policy()->should_add_next_region_to_young_list());
4851 }
4852
4853 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4854 assert(heap_lock_held_for_gc(),
4855 "the heap lock should already be held by or for this thread");
4856 _young_list->push_region(hr);
4857 g1_policy()->set_region_short_lived(hr);
4858 }
4859
4860 class NoYoungRegionsClosure: public HeapRegionClosure {
4861 private:
4862 bool _success;
4863 public:
4864 NoYoungRegionsClosure() : _success(true) { }
4865 bool doHeapRegion(HeapRegion* r) {
4866 if (r->is_young()) {
4867 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
4868 r->bottom(), r->end());
4869 _success = false;
4870 }
4871 return false;
4872 }
4873 bool success() { return _success; }
4874 };
4875
4876 bool G1CollectedHeap::check_young_list_empty(bool ignore_scan_only_list,
4877 bool check_sample) {
4878 bool ret = true;
4879
4880 ret = _young_list->check_list_empty(ignore_scan_only_list, check_sample);
4881 if (!ignore_scan_only_list) {
4882 NoYoungRegionsClosure closure;
4883 heap_region_iterate(&closure);
4884 ret = ret && closure.success();
4885 }
4886
4887 return ret;
4888 }
4889
4890 void G1CollectedHeap::empty_young_list() {
4891 assert(heap_lock_held_for_gc(),
4892 "the heap lock should already be held by or for this thread");
4893 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
4894
4895 _young_list->empty_list();
4896 }
4897
4898 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
4899 bool no_allocs = true;
4900 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
4901 HeapRegion* r = _gc_alloc_regions[ap];
4902 no_allocs = r == NULL || r->saved_mark_at_top();
4903 }
4904 return no_allocs;
4905 }
4906
4907 void G1CollectedHeap::all_alloc_regions_note_end_of_copying() {
4908 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
4909 HeapRegion* r = _gc_alloc_regions[ap];
4910 if (r != NULL) {
4911 // Check for aliases.
4912 bool has_processed_alias = false;
4913 for (int i = 0; i < ap; ++i) {
4914 if (_gc_alloc_regions[i] == r) {
4915 has_processed_alias = true;
4916 break;
4917 }
4918 }
4919 if (!has_processed_alias) {
4920 r->note_end_of_copying();
4921 g1_policy()->record_after_bytes(r->used());
4922 }
4923 }
4924 }
4925 }
4926
4927
4928 // Done at the start of full GC.
4929 void G1CollectedHeap::tear_down_region_lists() {
4930 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4931 while (pop_unclean_region_list_locked() != NULL) ;
4932 assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
4933 "Postconditions of loop.")
4934 while (pop_free_region_list_locked() != NULL) ;
4935 assert(_free_region_list == NULL, "Postcondition of loop.");
4936 if (_free_region_list_size != 0) {
4937 gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
4938 print();
4939 }
4940 assert(_free_region_list_size == 0, "Postconditions of loop.");
4941 }
4942
4943
4944 class RegionResetter: public HeapRegionClosure {
4945 G1CollectedHeap* _g1;
4946 int _n;
4947 public:
4948 RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
4949 bool doHeapRegion(HeapRegion* r) {
4950 if (r->continuesHumongous()) return false;
4951 if (r->top() > r->bottom()) {
4952 if (r->top() < r->end()) {
4953 Copy::fill_to_words(r->top(),
4954 pointer_delta(r->end(), r->top()));
4955 }
4956 r->set_zero_fill_allocated();
4957 } else {
4958 assert(r->is_empty(), "tautology");
4959 if (r->popular()) {
4960 if (r->zero_fill_state() != HeapRegion::Allocated) {
4961 r->ensure_zero_filled_locked();
4962 r->set_zero_fill_allocated();
4963 }
4964 } else {
4965 _n++;
4966 switch (r->zero_fill_state()) {
4967 case HeapRegion::NotZeroFilled:
4968 case HeapRegion::ZeroFilling:
4969 _g1->put_region_on_unclean_list_locked(r);
4970 break;
4971 case HeapRegion::Allocated:
4972 r->set_zero_fill_complete();
4973 // no break; go on to put on free list.
4974 case HeapRegion::ZeroFilled:
4975 _g1->put_free_region_on_list_locked(r);
4976 break;
4977 }
4978 }
4979 }
4980 return false;
4981 }
4982
4983 int getFreeRegionCount() {return _n;}
4984 };
4985
4986 // Done at the end of full GC.
4987 void G1CollectedHeap::rebuild_region_lists() {
4988 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
4989 // This needs to go at the end of the full GC.
4990 RegionResetter rs;
4991 heap_region_iterate(&rs);
4992 _free_regions = rs.getFreeRegionCount();
4993 // Tell the ZF thread it may have work to do.
4994 if (should_zf()) ZF_mon->notify_all();
4995 }
4996
4997 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
4998 G1CollectedHeap* _g1;
4999 int _n;
5000 public:
5001 UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
5002 bool doHeapRegion(HeapRegion* r) {
5003 if (r->continuesHumongous()) return false;
5004 if (r->top() > r->bottom()) {
5005 // There are assertions in "set_zero_fill_needed()" below that
5006 // require top() == bottom(), so this is technically illegal.
5007 // We'll skirt the law here, by making that true temporarily.
5008 DEBUG_ONLY(HeapWord* save_top = r->top();
5009 r->set_top(r->bottom()));
5010 r->set_zero_fill_needed();
5011 DEBUG_ONLY(r->set_top(save_top));
5012 }
5013 return false;
5014 }
5015 };
5016
5017 // Done at the start of full GC.
5018 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
5019 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
5020 // This needs to go at the end of the full GC.
5021 UsedRegionsNeedZeroFillSetter rs;
5022 heap_region_iterate(&rs);
5023 }
5024
5025 class CountObjClosure: public ObjectClosure {
5026 size_t _n;
5027 public:
5028 CountObjClosure() : _n(0) {}
5029 void do_object(oop obj) { _n++; }
5030 size_t n() { return _n; }
5031 };
5032
5033 size_t G1CollectedHeap::pop_object_used_objs() {
5034 size_t sum_objs = 0;
5035 for (int i = 0; i < G1NumPopularRegions; i++) {
5036 CountObjClosure cl;
5037 _hrs->at(i)->object_iterate(&cl);
5038 sum_objs += cl.n();
5039 }
5040 return sum_objs;
5041 }
5042
5043 size_t G1CollectedHeap::pop_object_used_bytes() {
5044 size_t sum_bytes = 0;
5045 for (int i = 0; i < G1NumPopularRegions; i++) {
5046 sum_bytes += _hrs->at(i)->used();
5047 }
5048 return sum_bytes;
5049 }
5050
5051
5052 static int nq = 0;
5053
5054 HeapWord* G1CollectedHeap::allocate_popular_object(size_t word_size) {
5055 while (_cur_pop_hr_index < G1NumPopularRegions) {
5056 HeapRegion* cur_pop_region = _hrs->at(_cur_pop_hr_index);
5057 HeapWord* res = cur_pop_region->allocate(word_size);
5058 if (res != NULL) {
5059 // We account for popular objs directly in the used summary:
5060 _summary_bytes_used += (word_size * HeapWordSize);
5061 return res;
5062 }
5063 // Otherwise, try the next region (first making sure that we remember
5064 // the last "top" value as the "next_top_at_mark_start", so that
5065 // objects made popular during markings aren't automatically considered
5066 // live).
5067 cur_pop_region->note_end_of_copying();
5068 // Otherwise, try the next region.
5069 _cur_pop_hr_index++;
5070 }
5071 // XXX: For now !!!
5072 vm_exit_out_of_memory(word_size,
5073 "Not enough pop obj space (To Be Fixed)");
5074 return NULL;
5075 }
5076
5077 class HeapRegionList: public CHeapObj {
5078 public:
5079 HeapRegion* hr;
5080 HeapRegionList* next;
5081 };
5082
5083 void G1CollectedHeap::schedule_popular_region_evac(HeapRegion* r) {
5084 // This might happen during parallel GC, so protect by this lock.
5085 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
5086 // We don't schedule regions whose evacuations are already pending, or
5087 // are already being evacuated.
5088 if (!r->popular_pending() && !r->in_collection_set()) {
5089 r->set_popular_pending(true);
5090 if (G1TracePopularity) {
5091 gclog_or_tty->print_cr("Scheduling region "PTR_FORMAT" "
5092 "["PTR_FORMAT", "PTR_FORMAT") for pop-object evacuation.",
5093 r, r->bottom(), r->end());
5094 }
5095 HeapRegionList* hrl = new HeapRegionList;
5096 hrl->hr = r;
5097 hrl->next = _popular_regions_to_be_evacuated;
5098 _popular_regions_to_be_evacuated = hrl;
5099 }
5100 }
5101
5102 HeapRegion* G1CollectedHeap::popular_region_to_evac() {
5103 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
5104 HeapRegion* res = NULL;
5105 while (_popular_regions_to_be_evacuated != NULL && res == NULL) {
5106 HeapRegionList* hrl = _popular_regions_to_be_evacuated;
5107 _popular_regions_to_be_evacuated = hrl->next;
5108 res = hrl->hr;
5109 // The G1RSPopLimit may have increased, so recheck here...
5110 if (res->rem_set()->occupied() < (size_t) G1RSPopLimit) {
5111 // Hah: don't need to schedule.
5112 if (G1TracePopularity) {
5113 gclog_or_tty->print_cr("Unscheduling region "PTR_FORMAT" "
5114 "["PTR_FORMAT", "PTR_FORMAT") "
5115 "for pop-object evacuation (size %d < limit %d)",
5116 res, res->bottom(), res->end(),
5117 res->rem_set()->occupied(), G1RSPopLimit);
5118 }
5119 res->set_popular_pending(false);
5120 res = NULL;
5121 }
5122 // We do not reset res->popular() here; if we did so, it would allow
5123 // the region to be "rescheduled" for popularity evacuation. Instead,
5124 // this is done in the collection pause, with the world stopped.
5125 // So the invariant is that the regions in the list have the popularity
5126 // boolean set, but having the boolean set does not imply membership
5127 // on the list (though there can at most one such pop-pending region
5128 // not on the list at any time).
5129 delete hrl;
5130 }
5131 return res;
5132 }
5133
5134 void G1CollectedHeap::evac_popular_region(HeapRegion* hr) {
5135 while (true) {
5136 // Don't want to do a GC pause while cleanup is being completed!
5137 wait_for_cleanup_complete();
5138
5139 // Read the GC count while holding the Heap_lock
5140 int gc_count_before = SharedHeap::heap()->total_collections();
5141 g1_policy()->record_stop_world_start();
5142
5143 {
5144 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
5145 VM_G1PopRegionCollectionPause op(gc_count_before, hr);
5146 VMThread::execute(&op);
5147
5148 // If the prolog succeeded, we didn't do a GC for this.
5149 if (op.prologue_succeeded()) break;
5150 }
5151 // Otherwise we didn't. We should recheck the size, though, since
5152 // the limit may have increased...
5153 if (hr->rem_set()->occupied() < (size_t) G1RSPopLimit) {
5154 hr->set_popular_pending(false);
5155 break;
5156 }
5157 }
5158 }
5159
5160 void G1CollectedHeap::atomic_inc_obj_rc(oop obj) {
5161 Atomic::inc(obj_rc_addr(obj));
5162 }
5163
5164 class CountRCClosure: public OopsInHeapRegionClosure {
5165 G1CollectedHeap* _g1h;
5166 bool _parallel;
5167 public:
5168 CountRCClosure(G1CollectedHeap* g1h) :
5169 _g1h(g1h), _parallel(ParallelGCThreads > 0)
5170 {}
5171 void do_oop(narrowOop* p) {
5172 guarantee(false, "NYI");
5173 }
5174 void do_oop(oop* p) {
5175 oop obj = *p;
5176 assert(obj != NULL, "Precondition.");
5177 if (_parallel) {
5178 // We go sticky at the limit to avoid excess contention.
5179 // If we want to track the actual RC's further, we'll need to keep a
5180 // per-thread hash table or something for the popular objects.
5181 if (_g1h->obj_rc(obj) < G1ObjPopLimit) {
5182 _g1h->atomic_inc_obj_rc(obj);
5183 }
5184 } else {
5185 _g1h->inc_obj_rc(obj);
5186 }
5187 }
5188 };
5189
5190 class EvacPopObjClosure: public ObjectClosure {
5191 G1CollectedHeap* _g1h;
5192 size_t _pop_objs;
5193 size_t _max_rc;
5194 public:
5195 EvacPopObjClosure(G1CollectedHeap* g1h) :
5196 _g1h(g1h), _pop_objs(0), _max_rc(0) {}
5197
5198 void do_object(oop obj) {
5199 size_t rc = _g1h->obj_rc(obj);
5200 _max_rc = MAX2(rc, _max_rc);
5201 if (rc >= (size_t) G1ObjPopLimit) {
5202 _g1h->_pop_obj_rc_at_copy.add((double)rc);
5203 size_t word_sz = obj->size();
5204 HeapWord* new_pop_loc = _g1h->allocate_popular_object(word_sz);
5205 oop new_pop_obj = (oop)new_pop_loc;
5206 Copy::aligned_disjoint_words((HeapWord*)obj, new_pop_loc, word_sz);
5207 obj->forward_to(new_pop_obj);
5208 G1ScanAndBalanceClosure scan_and_balance(_g1h);
5209 new_pop_obj->oop_iterate_backwards(&scan_and_balance);
5210 // preserve "next" mark bit if marking is in progress.
5211 if (_g1h->mark_in_progress() && !_g1h->is_obj_ill(obj)) {
5212 _g1h->concurrent_mark()->markAndGrayObjectIfNecessary(new_pop_obj);
5213 }
5214
5215 if (G1TracePopularity) {
5216 gclog_or_tty->print_cr("Found obj " PTR_FORMAT " of word size " SIZE_FORMAT
5217 " pop (%d), move to " PTR_FORMAT,
5218 (void*) obj, word_sz,
5219 _g1h->obj_rc(obj), (void*) new_pop_obj);
5220 }
5221 _pop_objs++;
5222 }
5223 }
5224 size_t pop_objs() { return _pop_objs; }
5225 size_t max_rc() { return _max_rc; }
5226 };
5227
5228 class G1ParCountRCTask : public AbstractGangTask {
5229 G1CollectedHeap* _g1h;
5230 BitMap _bm;
5231
5232 size_t getNCards() {
5233 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
5234 / G1BlockOffsetSharedArray::N_bytes;
5235 }
5236 CountRCClosure _count_rc_closure;
5237 public:
5238 G1ParCountRCTask(G1CollectedHeap* g1h) :
5239 AbstractGangTask("G1 Par RC Count task"),
5240 _g1h(g1h), _bm(getNCards()), _count_rc_closure(g1h)
5241 {}
5242
5243 void work(int i) {
5244 ResourceMark rm;
5245 HandleMark hm;
5246 _g1h->g1_rem_set()->oops_into_collection_set_do(&_count_rc_closure, i);
5247 }
5248 };
5249
5250 void G1CollectedHeap::popularity_pause_preamble(HeapRegion* popular_region) {
5251 // We're evacuating a single region (for popularity).
5252 if (G1TracePopularity) {
5253 gclog_or_tty->print_cr("Doing pop region pause for ["PTR_FORMAT", "PTR_FORMAT")",
5254 popular_region->bottom(), popular_region->end());
5255 }
5256 g1_policy()->set_single_region_collection_set(popular_region);
5257 size_t max_rc;
5258 if (!compute_reference_counts_and_evac_popular(popular_region,
5259 &max_rc)) {
5260 // We didn't evacuate any popular objects.
5261 // We increase the RS popularity limit, to prevent this from
5262 // happening in the future.
5263 if (G1RSPopLimit < (1 << 30)) {
5264 G1RSPopLimit *= 2;
5265 }
5266 // For now, interesting enough for a message:
5267 #if 1
5268 gclog_or_tty->print_cr("In pop region pause for ["PTR_FORMAT", "PTR_FORMAT"), "
5269 "failed to find a pop object (max = %d).",
5270 popular_region->bottom(), popular_region->end(),
5271 max_rc);
5272 gclog_or_tty->print_cr("Increased G1RSPopLimit to %d.", G1RSPopLimit);
5273 #endif // 0
5274 // Also, we reset the collection set to NULL, to make the rest of
5275 // the collection do nothing.
5276 assert(popular_region->next_in_collection_set() == NULL,
5277 "should be single-region.");
5278 popular_region->set_in_collection_set(false);
5279 popular_region->set_popular_pending(false);
5280 g1_policy()->clear_collection_set();
5281 }
5282 }
5283
5284 bool G1CollectedHeap::
5285 compute_reference_counts_and_evac_popular(HeapRegion* popular_region,
5286 size_t* max_rc) {
5287 HeapWord* rc_region_bot;
5288 HeapWord* rc_region_end;
5289
5290 // Set up the reference count region.
5291 HeapRegion* rc_region = newAllocRegion(HeapRegion::GrainWords);
5292 if (rc_region != NULL) {
5293 rc_region_bot = rc_region->bottom();
5294 rc_region_end = rc_region->end();
5295 } else {
5296 rc_region_bot = NEW_C_HEAP_ARRAY(HeapWord, HeapRegion::GrainWords);
5297 if (rc_region_bot == NULL) {
5298 vm_exit_out_of_memory(HeapRegion::GrainWords,
5299 "No space for RC region.");
5300 }
5301 rc_region_end = rc_region_bot + HeapRegion::GrainWords;
5302 }
5303
5304 if (G1TracePopularity)
5305 gclog_or_tty->print_cr("RC region is ["PTR_FORMAT", "PTR_FORMAT")",
5306 rc_region_bot, rc_region_end);
5307 if (rc_region_bot > popular_region->bottom()) {
5308 _rc_region_above = true;
5309 _rc_region_diff =
5310 pointer_delta(rc_region_bot, popular_region->bottom(), 1);
5311 } else {
5312 assert(rc_region_bot < popular_region->bottom(), "Can't be equal.");
5313 _rc_region_above = false;
5314 _rc_region_diff =
5315 pointer_delta(popular_region->bottom(), rc_region_bot, 1);
5316 }
5317 g1_policy()->record_pop_compute_rc_start();
5318 // Count external references.
5319 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5320 if (ParallelGCThreads > 0) {
5321
5322 set_par_threads(workers()->total_workers());
5323 G1ParCountRCTask par_count_rc_task(this);
5324 workers()->run_task(&par_count_rc_task);
5325 set_par_threads(0);
5326
5327 } else {
5328 CountRCClosure count_rc_closure(this);
5329 g1_rem_set()->oops_into_collection_set_do(&count_rc_closure, 0);
5330 }
5331 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5332 g1_policy()->record_pop_compute_rc_end();
5333
5334 // Now evacuate popular objects.
5335 g1_policy()->record_pop_evac_start();
5336 EvacPopObjClosure evac_pop_obj_cl(this);
5337 popular_region->object_iterate(&evac_pop_obj_cl);
5338 *max_rc = evac_pop_obj_cl.max_rc();
5339
5340 // Make sure the last "top" value of the current popular region is copied
5341 // as the "next_top_at_mark_start", so that objects made popular during
5342 // markings aren't automatically considered live.
5343 HeapRegion* cur_pop_region = _hrs->at(_cur_pop_hr_index);
5344 cur_pop_region->note_end_of_copying();
5345
5346 if (rc_region != NULL) {
5347 free_region(rc_region);
5348 } else {
5349 FREE_C_HEAP_ARRAY(HeapWord, rc_region_bot);
5350 }
5351 g1_policy()->record_pop_evac_end();
5352
5353 return evac_pop_obj_cl.pop_objs() > 0;
5354 }
5355
5356 class CountPopObjInfoClosure: public HeapRegionClosure {
5357 size_t _objs;
5358 size_t _bytes;
5359
5360 class CountObjClosure: public ObjectClosure {
5361 int _n;
5362 public:
5363 CountObjClosure() : _n(0) {}
5364 void do_object(oop obj) { _n++; }
5365 size_t n() { return _n; }
5366 };
5367
5368 public:
5369 CountPopObjInfoClosure() : _objs(0), _bytes(0) {}
5370 bool doHeapRegion(HeapRegion* r) {
5371 _bytes += r->used();
5372 CountObjClosure blk;
5373 r->object_iterate(&blk);
5374 _objs += blk.n();
5375 return false;
5376 }
5377 size_t objs() { return _objs; }
5378 size_t bytes() { return _bytes; }
5379 };
5380
5381
5382 void G1CollectedHeap::print_popularity_summary_info() const {
5383 CountPopObjInfoClosure blk;
5384 for (int i = 0; i <= _cur_pop_hr_index; i++) {
5385 blk.doHeapRegion(_hrs->at(i));
5386 }
5387 gclog_or_tty->print_cr("\nPopular objects: %d objs, %d bytes.",
5388 blk.objs(), blk.bytes());
5389 gclog_or_tty->print_cr(" RC at copy = [avg = %5.2f, max = %5.2f, sd = %5.2f].",
5390 _pop_obj_rc_at_copy.avg(),
5391 _pop_obj_rc_at_copy.maximum(),
5392 _pop_obj_rc_at_copy.sd());
5393 }
5394
5395 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5396 _refine_cte_cl->set_concurrent(concurrent);
5397 }
5398
5399 #ifndef PRODUCT
5400
5401 class PrintHeapRegionClosure: public HeapRegionClosure {
5402 public:
5403 bool doHeapRegion(HeapRegion *r) {
5404 gclog_or_tty->print("Region: "PTR_FORMAT":", r);
5405 if (r != NULL) {
5406 if (r->is_on_free_list())
5407 gclog_or_tty->print("Free ");
5408 if (r->is_young())
5409 gclog_or_tty->print("Young ");
5410 if (r->isHumongous())
5411 gclog_or_tty->print("Is Humongous ");
5412 r->print();
5413 }
5414 return false;
5415 }
5416 };
5417
5418 class SortHeapRegionClosure : public HeapRegionClosure {
5419 size_t young_regions,free_regions, unclean_regions;
5420 size_t hum_regions, count;
5421 size_t unaccounted, cur_unclean, cur_alloc;
5422 size_t total_free;
5423 HeapRegion* cur;
5424 public:
5425 SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
5426 free_regions(0), unclean_regions(0),
5427 hum_regions(0),
5428 count(0), unaccounted(0),
5429 cur_alloc(0), total_free(0)
5430 {}
5431 bool doHeapRegion(HeapRegion *r) {
5432 count++;
5433 if (r->is_on_free_list()) free_regions++;
5434 else if (r->is_on_unclean_list()) unclean_regions++;
5435 else if (r->isHumongous()) hum_regions++;
5436 else if (r->is_young()) young_regions++;
5437 else if (r == cur) cur_alloc++;
5438 else unaccounted++;
5439 return false;
5440 }
5441 void print() {
5442 total_free = free_regions + unclean_regions;
5443 gclog_or_tty->print("%d regions\n", count);
5444 gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
5445 total_free, free_regions, unclean_regions);
5446 gclog_or_tty->print("%d humongous %d young\n",
5447 hum_regions, young_regions);
5448 gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
5449 gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
5450 }
5451 };
5452
5453 void G1CollectedHeap::print_region_counts() {
5454 SortHeapRegionClosure sc(_cur_alloc_region);
5455 PrintHeapRegionClosure cl;
5456 heap_region_iterate(&cl);
5457 heap_region_iterate(&sc);
5458 sc.print();
5459 print_region_accounting_info();
5460 };
5461
5462 bool G1CollectedHeap::regions_accounted_for() {
5463 // TODO: regions accounting for young/survivor/tenured
5464 return true;
5465 }
5466
5467 bool G1CollectedHeap::print_region_accounting_info() {
5468 gclog_or_tty->print_cr("P regions: %d.", G1NumPopularRegions);
5469 gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
5470 free_regions(),
5471 count_free_regions(), count_free_regions_list(),
5472 _free_region_list_size, _unclean_region_list.sz());
5473 gclog_or_tty->print_cr("cur_alloc: %d.",
5474 (_cur_alloc_region == NULL ? 0 : 1));
5475 gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
5476
5477 // TODO: check regions accounting for young/survivor/tenured
5478 return true;
5479 }
5480
5481 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5482 HeapRegion* hr = heap_region_containing(p);
5483 if (hr == NULL) {
5484 return is_in_permanent(p);
5485 } else {
5486 return hr->is_in(p);
5487 }
5488 }
5489 #endif // PRODUCT
5490
5491 void G1CollectedHeap::g1_unimplemented() {
5492 // Unimplemented();
5493 }
5494
5495
5496 // Local Variables: ***
5497 // c-indentation-style: gnu ***
5498 // End: ***