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