1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectorPolicy.hpp"
38 #include "gc/g1/g1CollectorState.hpp"
39 #include "gc/g1/g1ErgoVerbose.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1Log.hpp"
43 #include "gc/g1/g1MarkSweep.hpp"
44 #include "gc/g1/g1OopClosures.inline.hpp"
45 #include "gc/g1/g1ParScanThreadState.inline.hpp"
46 #include "gc/g1/g1RegionToSpaceMapper.hpp"
47 #include "gc/g1/g1RemSet.inline.hpp"
48 #include "gc/g1/g1RootClosures.hpp"
49 #include "gc/g1/g1RootProcessor.hpp"
50 #include "gc/g1/g1StringDedup.hpp"
51 #include "gc/g1/g1YCTypes.hpp"
52 #include "gc/g1/heapRegion.inline.hpp"
53 #include "gc/g1/heapRegionRemSet.hpp"
54 #include "gc/g1/heapRegionSet.inline.hpp"
55 #include "gc/g1/suspendibleThreadSet.hpp"
56 #include "gc/g1/vm_operations_g1.hpp"
57 #include "gc/shared/gcHeapSummary.hpp"
58 #include "gc/shared/gcId.hpp"
59 #include "gc/shared/gcLocker.inline.hpp"
60 #include "gc/shared/gcTimer.hpp"
61 #include "gc/shared/gcTrace.hpp"
62 #include "gc/shared/gcTraceTime.hpp"
63 #include "gc/shared/generationSpec.hpp"
64 #include "gc/shared/isGCActiveMark.hpp"
65 #include "gc/shared/referenceProcessor.hpp"
66 #include "gc/shared/taskqueue.inline.hpp"
67 #include "memory/allocation.hpp"
68 #include "memory/iterator.hpp"
69 #include "oops/oop.inline.hpp"
70 #include "runtime/atomic.inline.hpp"
71 #include "runtime/init.hpp"
72 #include "runtime/orderAccess.inline.hpp"
73 #include "runtime/vmThread.hpp"
74 #include "utilities/globalDefinitions.hpp"
75 #include "utilities/stack.inline.hpp"
76
77 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
78
79 // INVARIANTS/NOTES
80 //
81 // All allocation activity covered by the G1CollectedHeap interface is
82 // serialized by acquiring the HeapLock. This happens in mem_allocate
83 // and allocate_new_tlab, which are the "entry" points to the
84 // allocation code from the rest of the JVM. (Note that this does not
85 // apply to TLAB allocation, which is not part of this interface: it
86 // is done by clients of this interface.)
87
88 // Local to this file.
89
90 class RefineCardTableEntryClosure: public CardTableEntryClosure {
91 bool _concurrent;
92 public:
93 RefineCardTableEntryClosure() : _concurrent(true) { }
94
95 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
96 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
97 // This path is executed by the concurrent refine or mutator threads,
98 // concurrently, and so we do not care if card_ptr contains references
99 // that point into the collection set.
100 assert(!oops_into_cset, "should be");
101
102 if (_concurrent && SuspendibleThreadSet::should_yield()) {
103 // Caller will actually yield.
104 return false;
105 }
106 // Otherwise, we finished successfully; return true.
107 return true;
108 }
109
110 void set_concurrent(bool b) { _concurrent = b; }
111 };
112
113
114 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
115 private:
116 size_t _num_dirtied;
117 G1CollectedHeap* _g1h;
118 G1SATBCardTableLoggingModRefBS* _g1_bs;
119
120 HeapRegion* region_for_card(jbyte* card_ptr) const {
121 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
122 }
123
124 bool will_become_free(HeapRegion* hr) const {
125 // A region will be freed by free_collection_set if the region is in the
126 // collection set and has not had an evacuation failure.
127 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
128 }
129
130 public:
131 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
132 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
133
134 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
135 HeapRegion* hr = region_for_card(card_ptr);
136
137 // Should only dirty cards in regions that won't be freed.
138 if (!will_become_free(hr)) {
139 *card_ptr = CardTableModRefBS::dirty_card_val();
140 _num_dirtied++;
141 }
142
143 return true;
144 }
145
146 size_t num_dirtied() const { return _num_dirtied; }
147 };
148
149
150 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
151 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
152 }
153
154 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
155 // The from card cache is not the memory that is actually committed. So we cannot
156 // take advantage of the zero_filled parameter.
157 reset_from_card_cache(start_idx, num_regions);
158 }
159
160 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
161 {
162 // Claim the right to put the region on the dirty cards region list
163 // by installing a self pointer.
164 HeapRegion* next = hr->get_next_dirty_cards_region();
165 if (next == NULL) {
166 HeapRegion* res = (HeapRegion*)
167 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
168 NULL);
169 if (res == NULL) {
170 HeapRegion* head;
171 do {
172 // Put the region to the dirty cards region list.
173 head = _dirty_cards_region_list;
174 next = (HeapRegion*)
175 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
176 if (next == head) {
177 assert(hr->get_next_dirty_cards_region() == hr,
178 "hr->get_next_dirty_cards_region() != hr");
179 if (next == NULL) {
180 // The last region in the list points to itself.
181 hr->set_next_dirty_cards_region(hr);
182 } else {
183 hr->set_next_dirty_cards_region(next);
184 }
185 }
186 } while (next != head);
187 }
188 }
189 }
190
191 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
192 {
193 HeapRegion* head;
194 HeapRegion* hr;
195 do {
196 head = _dirty_cards_region_list;
197 if (head == NULL) {
198 return NULL;
199 }
200 HeapRegion* new_head = head->get_next_dirty_cards_region();
201 if (head == new_head) {
202 // The last region.
203 new_head = NULL;
204 }
205 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
206 head);
207 } while (hr != head);
208 assert(hr != NULL, "invariant");
209 hr->set_next_dirty_cards_region(NULL);
210 return hr;
211 }
212
213 // Returns true if the reference points to an object that
214 // can move in an incremental collection.
215 bool G1CollectedHeap::is_scavengable(const void* p) {
216 HeapRegion* hr = heap_region_containing(p);
217 return !hr->is_pinned();
218 }
219
220 // Private methods.
221
222 HeapRegion*
223 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
224 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
225 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
226 if (!_secondary_free_list.is_empty()) {
227 if (G1ConcRegionFreeingVerbose) {
228 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
229 "secondary_free_list has %u entries",
230 _secondary_free_list.length());
231 }
232 // It looks as if there are free regions available on the
233 // secondary_free_list. Let's move them to the free_list and try
234 // again to allocate from it.
235 append_secondary_free_list();
236
237 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
238 "empty we should have moved at least one entry to the free_list");
239 HeapRegion* res = _hrm.allocate_free_region(is_old);
240 if (G1ConcRegionFreeingVerbose) {
241 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
242 "allocated " HR_FORMAT " from secondary_free_list",
243 HR_FORMAT_PARAMS(res));
244 }
245 return res;
246 }
247
248 // Wait here until we get notified either when (a) there are no
249 // more free regions coming or (b) some regions have been moved on
250 // the secondary_free_list.
251 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
252 }
253
254 if (G1ConcRegionFreeingVerbose) {
255 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
256 "could not allocate from secondary_free_list");
257 }
258 return NULL;
259 }
260
261 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
262 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
263 "the only time we use this to allocate a humongous region is "
264 "when we are allocating a single humongous region");
265
266 HeapRegion* res;
267 if (G1StressConcRegionFreeing) {
268 if (!_secondary_free_list.is_empty()) {
269 if (G1ConcRegionFreeingVerbose) {
270 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
271 "forced to look at the secondary_free_list");
272 }
273 res = new_region_try_secondary_free_list(is_old);
274 if (res != NULL) {
275 return res;
276 }
277 }
278 }
279
280 res = _hrm.allocate_free_region(is_old);
281
282 if (res == NULL) {
283 if (G1ConcRegionFreeingVerbose) {
284 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
285 "res == NULL, trying the secondary_free_list");
286 }
287 res = new_region_try_secondary_free_list(is_old);
288 }
289 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
290 // Currently, only attempts to allocate GC alloc regions set
291 // do_expand to true. So, we should only reach here during a
292 // safepoint. If this assumption changes we might have to
293 // reconsider the use of _expand_heap_after_alloc_failure.
294 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
295
296 ergo_verbose1(ErgoHeapSizing,
297 "attempt heap expansion",
298 ergo_format_reason("region allocation request failed")
299 ergo_format_byte("allocation request"),
300 word_size * HeapWordSize);
301 if (expand(word_size * HeapWordSize)) {
302 // Given that expand() succeeded in expanding the heap, and we
303 // always expand the heap by an amount aligned to the heap
304 // region size, the free list should in theory not be empty.
305 // In either case allocate_free_region() will check for NULL.
306 res = _hrm.allocate_free_region(is_old);
307 } else {
308 _expand_heap_after_alloc_failure = false;
309 }
310 }
311 return res;
312 }
313
314 HeapWord*
315 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
316 uint num_regions,
317 size_t word_size,
318 AllocationContext_t context) {
319 assert(first != G1_NO_HRM_INDEX, "pre-condition");
320 assert(is_humongous(word_size), "word_size should be humongous");
321 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
322
323 // Index of last region in the series.
324 uint last = first + num_regions - 1;
325
326 // We need to initialize the region(s) we just discovered. This is
327 // a bit tricky given that it can happen concurrently with
328 // refinement threads refining cards on these regions and
329 // potentially wanting to refine the BOT as they are scanning
330 // those cards (this can happen shortly after a cleanup; see CR
331 // 6991377). So we have to set up the region(s) carefully and in
332 // a specific order.
333
334 // The word size sum of all the regions we will allocate.
335 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
336 assert(word_size <= word_size_sum, "sanity");
337
338 // This will be the "starts humongous" region.
339 HeapRegion* first_hr = region_at(first);
340 // The header of the new object will be placed at the bottom of
341 // the first region.
342 HeapWord* new_obj = first_hr->bottom();
343 // This will be the new top of the new object.
344 HeapWord* obj_top = new_obj + word_size;
345
346 // First, we need to zero the header of the space that we will be
347 // allocating. When we update top further down, some refinement
348 // threads might try to scan the region. By zeroing the header we
349 // ensure that any thread that will try to scan the region will
350 // come across the zero klass word and bail out.
351 //
352 // NOTE: It would not have been correct to have used
353 // CollectedHeap::fill_with_object() and make the space look like
354 // an int array. The thread that is doing the allocation will
355 // later update the object header to a potentially different array
356 // type and, for a very short period of time, the klass and length
357 // fields will be inconsistent. This could cause a refinement
358 // thread to calculate the object size incorrectly.
359 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
360
361 // How many words we use for filler objects.
362 size_t word_fill_size = word_size_sum - word_size;
363
364 // How many words memory we "waste" which cannot hold a filler object.
365 size_t words_not_fillable = 0;
366
367 if (word_fill_size >= min_fill_size()) {
368 fill_with_objects(obj_top, word_fill_size);
369 } else if (word_fill_size > 0) {
370 // We have space to fill, but we cannot fit an object there.
371 words_not_fillable = word_fill_size;
372 word_fill_size = 0;
373 }
374
375 // We will set up the first region as "starts humongous". This
376 // will also update the BOT covering all the regions to reflect
377 // that there is a single object that starts at the bottom of the
378 // first region.
379 first_hr->set_starts_humongous(obj_top, word_fill_size);
380 first_hr->set_allocation_context(context);
381 // Then, if there are any, we will set up the "continues
382 // humongous" regions.
383 HeapRegion* hr = NULL;
384 for (uint i = first + 1; i <= last; ++i) {
385 hr = region_at(i);
386 hr->set_continues_humongous(first_hr);
387 hr->set_allocation_context(context);
388 }
389
390 // Up to this point no concurrent thread would have been able to
391 // do any scanning on any region in this series. All the top
392 // fields still point to bottom, so the intersection between
393 // [bottom,top] and [card_start,card_end] will be empty. Before we
394 // update the top fields, we'll do a storestore to make sure that
395 // no thread sees the update to top before the zeroing of the
396 // object header and the BOT initialization.
397 OrderAccess::storestore();
398
399 // Now, we will update the top fields of the "continues humongous"
400 // regions except the last one.
401 for (uint i = first; i < last; ++i) {
402 hr = region_at(i);
403 hr->set_top(hr->end());
404 }
405
406 hr = region_at(last);
407 // If we cannot fit a filler object, we must set top to the end
408 // of the humongous object, otherwise we cannot iterate the heap
409 // and the BOT will not be complete.
410 hr->set_top(hr->end() - words_not_fillable);
411
412 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
413 "obj_top should be in last region");
414
415 check_bitmaps("Humongous Region Allocation", first_hr);
416
417 assert(words_not_fillable == 0 ||
418 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
419 "Miscalculation in humongous allocation");
420
421 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
422
423 for (uint i = first; i <= last; ++i) {
424 hr = region_at(i);
425 _humongous_set.add(hr);
426 if (i == first) {
427 _hr_printer.alloc(G1HRPrinter::StartsHumongous, hr, hr->top());
428 } else {
429 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->top());
430 }
431 }
432
433 return new_obj;
434 }
435
436 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
437 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
438 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
439 }
440
441 // If could fit into free regions w/o expansion, try.
442 // Otherwise, if can expand, do so.
443 // Otherwise, if using ex regions might help, try with ex given back.
444 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
445 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
446
447 verify_region_sets_optional();
448
449 uint first = G1_NO_HRM_INDEX;
450 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
451
452 if (obj_regions == 1) {
453 // Only one region to allocate, try to use a fast path by directly allocating
454 // from the free lists. Do not try to expand here, we will potentially do that
455 // later.
456 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
457 if (hr != NULL) {
458 first = hr->hrm_index();
459 }
460 } else {
461 // We can't allocate humongous regions spanning more than one region while
462 // cleanupComplete() is running, since some of the regions we find to be
463 // empty might not yet be added to the free list. It is not straightforward
464 // to know in which list they are on so that we can remove them. We only
465 // need to do this if we need to allocate more than one region to satisfy the
466 // current humongous allocation request. If we are only allocating one region
467 // we use the one-region region allocation code (see above), that already
468 // potentially waits for regions from the secondary free list.
469 wait_while_free_regions_coming();
470 append_secondary_free_list_if_not_empty_with_lock();
471
472 // Policy: Try only empty regions (i.e. already committed first). Maybe we
473 // are lucky enough to find some.
474 first = _hrm.find_contiguous_only_empty(obj_regions);
475 if (first != G1_NO_HRM_INDEX) {
476 _hrm.allocate_free_regions_starting_at(first, obj_regions);
477 }
478 }
479
480 if (first == G1_NO_HRM_INDEX) {
481 // Policy: We could not find enough regions for the humongous object in the
482 // free list. Look through the heap to find a mix of free and uncommitted regions.
483 // If so, try expansion.
484 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
485 if (first != G1_NO_HRM_INDEX) {
486 // We found something. Make sure these regions are committed, i.e. expand
487 // the heap. Alternatively we could do a defragmentation GC.
488 ergo_verbose1(ErgoHeapSizing,
489 "attempt heap expansion",
490 ergo_format_reason("humongous allocation request failed")
491 ergo_format_byte("allocation request"),
492 word_size * HeapWordSize);
493
494 _hrm.expand_at(first, obj_regions);
495 g1_policy()->record_new_heap_size(num_regions());
496
497 #ifdef ASSERT
498 for (uint i = first; i < first + obj_regions; ++i) {
499 HeapRegion* hr = region_at(i);
500 assert(hr->is_free(), "sanity");
501 assert(hr->is_empty(), "sanity");
502 assert(is_on_master_free_list(hr), "sanity");
503 }
504 #endif
505 _hrm.allocate_free_regions_starting_at(first, obj_regions);
506 } else {
507 // Policy: Potentially trigger a defragmentation GC.
508 }
509 }
510
511 HeapWord* result = NULL;
512 if (first != G1_NO_HRM_INDEX) {
513 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
514 word_size, context);
515 assert(result != NULL, "it should always return a valid result");
516
517 // A successful humongous object allocation changes the used space
518 // information of the old generation so we need to recalculate the
519 // sizes and update the jstat counters here.
520 g1mm()->update_sizes();
521 }
522
523 verify_region_sets_optional();
524
525 return result;
526 }
527
528 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
529 assert_heap_not_locked_and_not_at_safepoint();
530 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
531
532 uint dummy_gc_count_before;
533 uint dummy_gclocker_retry_count = 0;
534 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
535 }
536
537 HeapWord*
538 G1CollectedHeap::mem_allocate(size_t word_size,
539 bool* gc_overhead_limit_was_exceeded) {
540 assert_heap_not_locked_and_not_at_safepoint();
541
542 // Loop until the allocation is satisfied, or unsatisfied after GC.
543 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
544 uint gc_count_before;
545
546 HeapWord* result = NULL;
547 if (!is_humongous(word_size)) {
548 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
549 } else {
550 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
551 }
552 if (result != NULL) {
553 return result;
554 }
555
556 // Create the garbage collection operation...
557 VM_G1CollectForAllocation op(gc_count_before, word_size);
558 op.set_allocation_context(AllocationContext::current());
559
560 // ...and get the VM thread to execute it.
561 VMThread::execute(&op);
562
563 if (op.prologue_succeeded() && op.pause_succeeded()) {
564 // If the operation was successful we'll return the result even
565 // if it is NULL. If the allocation attempt failed immediately
566 // after a Full GC, it's unlikely we'll be able to allocate now.
567 HeapWord* result = op.result();
568 if (result != NULL && !is_humongous(word_size)) {
569 // Allocations that take place on VM operations do not do any
570 // card dirtying and we have to do it here. We only have to do
571 // this for non-humongous allocations, though.
572 dirty_young_block(result, word_size);
573 }
574 return result;
575 } else {
576 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
577 return NULL;
578 }
579 assert(op.result() == NULL,
580 "the result should be NULL if the VM op did not succeed");
581 }
582
583 // Give a warning if we seem to be looping forever.
584 if ((QueuedAllocationWarningCount > 0) &&
585 (try_count % QueuedAllocationWarningCount == 0)) {
586 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
587 }
588 }
589
590 ShouldNotReachHere();
591 return NULL;
592 }
593
594 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
595 AllocationContext_t context,
596 uint* gc_count_before_ret,
597 uint* gclocker_retry_count_ret) {
598 // Make sure you read the note in attempt_allocation_humongous().
599
600 assert_heap_not_locked_and_not_at_safepoint();
601 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
602 "be called for humongous allocation requests");
603
604 // We should only get here after the first-level allocation attempt
605 // (attempt_allocation()) failed to allocate.
606
607 // We will loop until a) we manage to successfully perform the
608 // allocation or b) we successfully schedule a collection which
609 // fails to perform the allocation. b) is the only case when we'll
610 // return NULL.
611 HeapWord* result = NULL;
612 for (int try_count = 1; /* we'll return */; try_count += 1) {
613 bool should_try_gc;
614 uint gc_count_before;
615
616 {
617 MutexLockerEx x(Heap_lock);
618 result = _allocator->attempt_allocation_locked(word_size, context);
619 if (result != NULL) {
620 return result;
621 }
622
623 if (GC_locker::is_active_and_needs_gc()) {
624 if (g1_policy()->can_expand_young_list()) {
625 // No need for an ergo verbose message here,
626 // can_expand_young_list() does this when it returns true.
627 result = _allocator->attempt_allocation_force(word_size, context);
628 if (result != NULL) {
629 return result;
630 }
631 }
632 should_try_gc = false;
633 } else {
634 // The GCLocker may not be active but the GCLocker initiated
635 // GC may not yet have been performed (GCLocker::needs_gc()
636 // returns true). In this case we do not try this GC and
637 // wait until the GCLocker initiated GC is performed, and
638 // then retry the allocation.
639 if (GC_locker::needs_gc()) {
640 should_try_gc = false;
641 } else {
642 // Read the GC count while still holding the Heap_lock.
643 gc_count_before = total_collections();
644 should_try_gc = true;
645 }
646 }
647 }
648
649 if (should_try_gc) {
650 bool succeeded;
651 result = do_collection_pause(word_size, gc_count_before, &succeeded,
652 GCCause::_g1_inc_collection_pause);
653 if (result != NULL) {
654 assert(succeeded, "only way to get back a non-NULL result");
655 return result;
656 }
657
658 if (succeeded) {
659 // If we get here we successfully scheduled a collection which
660 // failed to allocate. No point in trying to allocate
661 // further. We'll just return NULL.
662 MutexLockerEx x(Heap_lock);
663 *gc_count_before_ret = total_collections();
664 return NULL;
665 }
666 } else {
667 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
668 MutexLockerEx x(Heap_lock);
669 *gc_count_before_ret = total_collections();
670 return NULL;
671 }
672 // The GCLocker is either active or the GCLocker initiated
673 // GC has not yet been performed. Stall until it is and
674 // then retry the allocation.
675 GC_locker::stall_until_clear();
676 (*gclocker_retry_count_ret) += 1;
677 }
678
679 // We can reach here if we were unsuccessful in scheduling a
680 // collection (because another thread beat us to it) or if we were
681 // stalled due to the GC locker. In either can we should retry the
682 // allocation attempt in case another thread successfully
683 // performed a collection and reclaimed enough space. We do the
684 // first attempt (without holding the Heap_lock) here and the
685 // follow-on attempt will be at the start of the next loop
686 // iteration (after taking the Heap_lock).
687 result = _allocator->attempt_allocation(word_size, context);
688 if (result != NULL) {
689 return result;
690 }
691
692 // Give a warning if we seem to be looping forever.
693 if ((QueuedAllocationWarningCount > 0) &&
694 (try_count % QueuedAllocationWarningCount == 0)) {
695 warning("G1CollectedHeap::attempt_allocation_slow() "
696 "retries %d times", try_count);
697 }
698 }
699
700 ShouldNotReachHere();
701 return NULL;
702 }
703
704 void G1CollectedHeap::begin_archive_alloc_range() {
705 assert_at_safepoint(true /* should_be_vm_thread */);
706 if (_archive_allocator == NULL) {
707 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
708 }
709 }
710
711 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
712 // Allocations in archive regions cannot be of a size that would be considered
713 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
714 // may be different at archive-restore time.
715 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
716 }
717
718 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
719 assert_at_safepoint(true /* should_be_vm_thread */);
720 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
721 if (is_archive_alloc_too_large(word_size)) {
722 return NULL;
723 }
724 return _archive_allocator->archive_mem_allocate(word_size);
725 }
726
727 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
728 size_t end_alignment_in_bytes) {
729 assert_at_safepoint(true /* should_be_vm_thread */);
730 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
731
732 // Call complete_archive to do the real work, filling in the MemRegion
733 // array with the archive regions.
734 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
735 delete _archive_allocator;
736 _archive_allocator = NULL;
737 }
738
739 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
740 assert(ranges != NULL, "MemRegion array NULL");
741 assert(count != 0, "No MemRegions provided");
742 MemRegion reserved = _hrm.reserved();
743 for (size_t i = 0; i < count; i++) {
744 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
745 return false;
746 }
747 }
748 return true;
749 }
750
751 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
752 assert(!is_init_completed(), "Expect to be called at JVM init time");
753 assert(ranges != NULL, "MemRegion array NULL");
754 assert(count != 0, "No MemRegions provided");
755 MutexLockerEx x(Heap_lock);
756
757 MemRegion reserved = _hrm.reserved();
758 HeapWord* prev_last_addr = NULL;
759 HeapRegion* prev_last_region = NULL;
760
761 // Temporarily disable pretouching of heap pages. This interface is used
762 // when mmap'ing archived heap data in, so pre-touching is wasted.
763 FlagSetting fs(AlwaysPreTouch, false);
764
765 // Enable archive object checking in G1MarkSweep. We have to let it know
766 // about each archive range, so that objects in those ranges aren't marked.
767 G1MarkSweep::enable_archive_object_check();
768
769 // For each specified MemRegion range, allocate the corresponding G1
770 // regions and mark them as archive regions. We expect the ranges in
771 // ascending starting address order, without overlap.
772 for (size_t i = 0; i < count; i++) {
773 MemRegion curr_range = ranges[i];
774 HeapWord* start_address = curr_range.start();
775 size_t word_size = curr_range.word_size();
776 HeapWord* last_address = curr_range.last();
777 size_t commits = 0;
778
779 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
780 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
781 p2i(start_address), p2i(last_address));
782 guarantee(start_address > prev_last_addr,
783 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
784 p2i(start_address), p2i(prev_last_addr));
785 prev_last_addr = last_address;
786
787 // Check for ranges that start in the same G1 region in which the previous
788 // range ended, and adjust the start address so we don't try to allocate
789 // the same region again. If the current range is entirely within that
790 // region, skip it, just adjusting the recorded top.
791 HeapRegion* start_region = _hrm.addr_to_region(start_address);
792 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
793 start_address = start_region->end();
794 if (start_address > last_address) {
795 increase_used(word_size * HeapWordSize);
796 start_region->set_top(last_address + 1);
797 continue;
798 }
799 start_region->set_top(start_address);
800 curr_range = MemRegion(start_address, last_address + 1);
801 start_region = _hrm.addr_to_region(start_address);
802 }
803
804 // Perform the actual region allocation, exiting if it fails.
805 // Then note how much new space we have allocated.
806 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
807 return false;
808 }
809 increase_used(word_size * HeapWordSize);
810 if (commits != 0) {
811 ergo_verbose1(ErgoHeapSizing,
812 "attempt heap expansion",
813 ergo_format_reason("allocate archive regions")
814 ergo_format_byte("total size"),
815 HeapRegion::GrainWords * HeapWordSize * commits);
816 }
817
818 // Mark each G1 region touched by the range as archive, add it to the old set,
819 // and set the allocation context and top.
820 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
821 HeapRegion* last_region = _hrm.addr_to_region(last_address);
822 prev_last_region = last_region;
823
824 while (curr_region != NULL) {
825 assert(curr_region->is_empty() && !curr_region->is_pinned(),
826 "Region already in use (index %u)", curr_region->hrm_index());
827 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
828 curr_region->set_allocation_context(AllocationContext::system());
829 curr_region->set_archive();
830 _old_set.add(curr_region);
831 if (curr_region != last_region) {
832 curr_region->set_top(curr_region->end());
833 curr_region = _hrm.next_region_in_heap(curr_region);
834 } else {
835 curr_region->set_top(last_address + 1);
836 curr_region = NULL;
837 }
838 }
839
840 // Notify mark-sweep of the archive range.
841 G1MarkSweep::set_range_archive(curr_range, true);
842 }
843 return true;
844 }
845
846 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
847 assert(!is_init_completed(), "Expect to be called at JVM init time");
848 assert(ranges != NULL, "MemRegion array NULL");
849 assert(count != 0, "No MemRegions provided");
850 MemRegion reserved = _hrm.reserved();
851 HeapWord *prev_last_addr = NULL;
852 HeapRegion* prev_last_region = NULL;
853
854 // For each MemRegion, create filler objects, if needed, in the G1 regions
855 // that contain the address range. The address range actually within the
856 // MemRegion will not be modified. That is assumed to have been initialized
857 // elsewhere, probably via an mmap of archived heap data.
858 MutexLockerEx x(Heap_lock);
859 for (size_t i = 0; i < count; i++) {
860 HeapWord* start_address = ranges[i].start();
861 HeapWord* last_address = ranges[i].last();
862
863 assert(reserved.contains(start_address) && reserved.contains(last_address),
864 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
865 p2i(start_address), p2i(last_address));
866 assert(start_address > prev_last_addr,
867 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
868 p2i(start_address), p2i(prev_last_addr));
869
870 HeapRegion* start_region = _hrm.addr_to_region(start_address);
871 HeapRegion* last_region = _hrm.addr_to_region(last_address);
872 HeapWord* bottom_address = start_region->bottom();
873
874 // Check for a range beginning in the same region in which the
875 // previous one ended.
876 if (start_region == prev_last_region) {
877 bottom_address = prev_last_addr + 1;
878 }
879
880 // Verify that the regions were all marked as archive regions by
881 // alloc_archive_regions.
882 HeapRegion* curr_region = start_region;
883 while (curr_region != NULL) {
884 guarantee(curr_region->is_archive(),
885 "Expected archive region at index %u", curr_region->hrm_index());
886 if (curr_region != last_region) {
887 curr_region = _hrm.next_region_in_heap(curr_region);
888 } else {
889 curr_region = NULL;
890 }
891 }
892
893 prev_last_addr = last_address;
894 prev_last_region = last_region;
895
896 // Fill the memory below the allocated range with dummy object(s),
897 // if the region bottom does not match the range start, or if the previous
898 // range ended within the same G1 region, and there is a gap.
899 if (start_address != bottom_address) {
900 size_t fill_size = pointer_delta(start_address, bottom_address);
901 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
902 increase_used(fill_size * HeapWordSize);
903 }
904 }
905 }
906
907 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
908 uint* gc_count_before_ret,
909 uint* gclocker_retry_count_ret) {
910 assert_heap_not_locked_and_not_at_safepoint();
911 assert(!is_humongous(word_size), "attempt_allocation() should not "
912 "be called for humongous allocation requests");
913
914 AllocationContext_t context = AllocationContext::current();
915 HeapWord* result = _allocator->attempt_allocation(word_size, context);
916
917 if (result == NULL) {
918 result = attempt_allocation_slow(word_size,
919 context,
920 gc_count_before_ret,
921 gclocker_retry_count_ret);
922 }
923 assert_heap_not_locked();
924 if (result != NULL) {
925 dirty_young_block(result, word_size);
926 }
927 return result;
928 }
929
930 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
931 assert(!is_init_completed(), "Expect to be called at JVM init time");
932 assert(ranges != NULL, "MemRegion array NULL");
933 assert(count != 0, "No MemRegions provided");
934 MemRegion reserved = _hrm.reserved();
935 HeapWord* prev_last_addr = NULL;
936 HeapRegion* prev_last_region = NULL;
937 size_t size_used = 0;
938 size_t uncommitted_regions = 0;
939
940 // For each Memregion, free the G1 regions that constitute it, and
941 // notify mark-sweep that the range is no longer to be considered 'archive.'
942 MutexLockerEx x(Heap_lock);
943 for (size_t i = 0; i < count; i++) {
944 HeapWord* start_address = ranges[i].start();
945 HeapWord* last_address = ranges[i].last();
946
947 assert(reserved.contains(start_address) && reserved.contains(last_address),
948 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
949 p2i(start_address), p2i(last_address));
950 assert(start_address > prev_last_addr,
951 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
952 p2i(start_address), p2i(prev_last_addr));
953 size_used += ranges[i].byte_size();
954 prev_last_addr = last_address;
955
956 HeapRegion* start_region = _hrm.addr_to_region(start_address);
957 HeapRegion* last_region = _hrm.addr_to_region(last_address);
958
959 // Check for ranges that start in the same G1 region in which the previous
960 // range ended, and adjust the start address so we don't try to free
961 // the same region again. If the current range is entirely within that
962 // region, skip it.
963 if (start_region == prev_last_region) {
964 start_address = start_region->end();
965 if (start_address > last_address) {
966 continue;
967 }
968 start_region = _hrm.addr_to_region(start_address);
969 }
970 prev_last_region = last_region;
971
972 // After verifying that each region was marked as an archive region by
973 // alloc_archive_regions, set it free and empty and uncommit it.
974 HeapRegion* curr_region = start_region;
975 while (curr_region != NULL) {
976 guarantee(curr_region->is_archive(),
977 "Expected archive region at index %u", curr_region->hrm_index());
978 uint curr_index = curr_region->hrm_index();
979 _old_set.remove(curr_region);
980 curr_region->set_free();
981 curr_region->set_top(curr_region->bottom());
982 if (curr_region != last_region) {
983 curr_region = _hrm.next_region_in_heap(curr_region);
984 } else {
985 curr_region = NULL;
986 }
987 _hrm.shrink_at(curr_index, 1);
988 uncommitted_regions++;
989 }
990
991 // Notify mark-sweep that this is no longer an archive range.
992 G1MarkSweep::set_range_archive(ranges[i], false);
993 }
994
995 if (uncommitted_regions != 0) {
996 ergo_verbose1(ErgoHeapSizing,
997 "attempt heap shrinking",
998 ergo_format_reason("uncommitted archive regions")
999 ergo_format_byte("total size"),
1000 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
1001 }
1002 decrease_used(size_used);
1003 }
1004
1005 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1006 uint* gc_count_before_ret,
1007 uint* gclocker_retry_count_ret) {
1008 // The structure of this method has a lot of similarities to
1009 // attempt_allocation_slow(). The reason these two were not merged
1010 // into a single one is that such a method would require several "if
1011 // allocation is not humongous do this, otherwise do that"
1012 // conditional paths which would obscure its flow. In fact, an early
1013 // version of this code did use a unified method which was harder to
1014 // follow and, as a result, it had subtle bugs that were hard to
1015 // track down. So keeping these two methods separate allows each to
1016 // be more readable. It will be good to keep these two in sync as
1017 // much as possible.
1018
1019 assert_heap_not_locked_and_not_at_safepoint();
1020 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1021 "should only be called for humongous allocations");
1022
1023 // Humongous objects can exhaust the heap quickly, so we should check if we
1024 // need to start a marking cycle at each humongous object allocation. We do
1025 // the check before we do the actual allocation. The reason for doing it
1026 // before the allocation is that we avoid having to keep track of the newly
1027 // allocated memory while we do a GC.
1028 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1029 word_size)) {
1030 collect(GCCause::_g1_humongous_allocation);
1031 }
1032
1033 // We will loop until a) we manage to successfully perform the
1034 // allocation or b) we successfully schedule a collection which
1035 // fails to perform the allocation. b) is the only case when we'll
1036 // return NULL.
1037 HeapWord* result = NULL;
1038 for (int try_count = 1; /* we'll return */; try_count += 1) {
1039 bool should_try_gc;
1040 uint gc_count_before;
1041
1042 {
1043 MutexLockerEx x(Heap_lock);
1044
1045 // Given that humongous objects are not allocated in young
1046 // regions, we'll first try to do the allocation without doing a
1047 // collection hoping that there's enough space in the heap.
1048 result = humongous_obj_allocate(word_size, AllocationContext::current());
1049 if (result != NULL) {
1050 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1051 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1052 return result;
1053 }
1054
1055 if (GC_locker::is_active_and_needs_gc()) {
1056 should_try_gc = false;
1057 } else {
1058 // The GCLocker may not be active but the GCLocker initiated
1059 // GC may not yet have been performed (GCLocker::needs_gc()
1060 // returns true). In this case we do not try this GC and
1061 // wait until the GCLocker initiated GC is performed, and
1062 // then retry the allocation.
1063 if (GC_locker::needs_gc()) {
1064 should_try_gc = false;
1065 } else {
1066 // Read the GC count while still holding the Heap_lock.
1067 gc_count_before = total_collections();
1068 should_try_gc = true;
1069 }
1070 }
1071 }
1072
1073 if (should_try_gc) {
1074 // If we failed to allocate the humongous object, we should try to
1075 // do a collection pause (if we're allowed) in case it reclaims
1076 // enough space for the allocation to succeed after the pause.
1077
1078 bool succeeded;
1079 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1080 GCCause::_g1_humongous_allocation);
1081 if (result != NULL) {
1082 assert(succeeded, "only way to get back a non-NULL result");
1083 return result;
1084 }
1085
1086 if (succeeded) {
1087 // If we get here we successfully scheduled a collection which
1088 // failed to allocate. No point in trying to allocate
1089 // further. We'll just return NULL.
1090 MutexLockerEx x(Heap_lock);
1091 *gc_count_before_ret = total_collections();
1092 return NULL;
1093 }
1094 } else {
1095 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1096 MutexLockerEx x(Heap_lock);
1097 *gc_count_before_ret = total_collections();
1098 return NULL;
1099 }
1100 // The GCLocker is either active or the GCLocker initiated
1101 // GC has not yet been performed. Stall until it is and
1102 // then retry the allocation.
1103 GC_locker::stall_until_clear();
1104 (*gclocker_retry_count_ret) += 1;
1105 }
1106
1107 // We can reach here if we were unsuccessful in scheduling a
1108 // collection (because another thread beat us to it) or if we were
1109 // stalled due to the GC locker. In either can we should retry the
1110 // allocation attempt in case another thread successfully
1111 // performed a collection and reclaimed enough space. Give a
1112 // warning if we seem to be looping forever.
1113
1114 if ((QueuedAllocationWarningCount > 0) &&
1115 (try_count % QueuedAllocationWarningCount == 0)) {
1116 warning("G1CollectedHeap::attempt_allocation_humongous() "
1117 "retries %d times", try_count);
1118 }
1119 }
1120
1121 ShouldNotReachHere();
1122 return NULL;
1123 }
1124
1125 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1126 AllocationContext_t context,
1127 bool expect_null_mutator_alloc_region) {
1128 assert_at_safepoint(true /* should_be_vm_thread */);
1129 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1130 "the current alloc region was unexpectedly found to be non-NULL");
1131
1132 if (!is_humongous(word_size)) {
1133 return _allocator->attempt_allocation_locked(word_size, context);
1134 } else {
1135 HeapWord* result = humongous_obj_allocate(word_size, context);
1136 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1137 collector_state()->set_initiate_conc_mark_if_possible(true);
1138 }
1139 return result;
1140 }
1141
1142 ShouldNotReachHere();
1143 }
1144
1145 class PostMCRemSetClearClosure: public HeapRegionClosure {
1146 G1CollectedHeap* _g1h;
1147 ModRefBarrierSet* _mr_bs;
1148 public:
1149 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1150 _g1h(g1h), _mr_bs(mr_bs) {}
1151
1152 bool doHeapRegion(HeapRegion* r) {
1153 HeapRegionRemSet* hrrs = r->rem_set();
1154
1155 _g1h->reset_gc_time_stamps(r);
1156
1157 if (r->is_continues_humongous()) {
1158 // We'll assert that the strong code root list and RSet is empty
1159 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1160 assert(hrrs->occupied() == 0, "RSet should be empty");
1161 } else {
1162 hrrs->clear();
1163 }
1164 // You might think here that we could clear just the cards
1165 // corresponding to the used region. But no: if we leave a dirty card
1166 // in a region we might allocate into, then it would prevent that card
1167 // from being enqueued, and cause it to be missed.
1168 // Re: the performance cost: we shouldn't be doing full GC anyway!
1169 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1170
1171 return false;
1172 }
1173 };
1174
1175 void G1CollectedHeap::clear_rsets_post_compaction() {
1176 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1177 heap_region_iterate(&rs_clear);
1178 }
1179
1180 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1181 G1CollectedHeap* _g1h;
1182 UpdateRSOopClosure _cl;
1183 public:
1184 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1185 _cl(g1->g1_rem_set(), worker_i),
1186 _g1h(g1)
1187 { }
1188
1189 bool doHeapRegion(HeapRegion* r) {
1190 if (!r->is_continues_humongous()) {
1191 _cl.set_from(r);
1192 r->oop_iterate(&_cl);
1193 }
1194 return false;
1195 }
1196 };
1197
1198 class ParRebuildRSTask: public AbstractGangTask {
1199 G1CollectedHeap* _g1;
1200 HeapRegionClaimer _hrclaimer;
1201
1202 public:
1203 ParRebuildRSTask(G1CollectedHeap* g1) :
1204 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1205
1206 void work(uint worker_id) {
1207 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1208 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1209 }
1210 };
1211
1212 class PostCompactionPrinterClosure: public HeapRegionClosure {
1213 private:
1214 G1HRPrinter* _hr_printer;
1215 public:
1216 bool doHeapRegion(HeapRegion* hr) {
1217 assert(!hr->is_young(), "not expecting to find young regions");
1218 if (hr->is_free()) {
1219 // We only generate output for non-empty regions.
1220 } else if (hr->is_starts_humongous()) {
1221 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1222 } else if (hr->is_continues_humongous()) {
1223 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1224 } else if (hr->is_archive()) {
1225 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1226 } else if (hr->is_old()) {
1227 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1228 } else {
1229 ShouldNotReachHere();
1230 }
1231 return false;
1232 }
1233
1234 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1235 : _hr_printer(hr_printer) { }
1236 };
1237
1238 void G1CollectedHeap::print_hrm_post_compaction() {
1239 PostCompactionPrinterClosure cl(hr_printer());
1240 heap_region_iterate(&cl);
1241 }
1242
1243 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1244 bool clear_all_soft_refs) {
1245 assert_at_safepoint(true /* should_be_vm_thread */);
1246
1247 if (GC_locker::check_active_before_gc()) {
1248 return false;
1249 }
1250
1251 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1252 gc_timer->register_gc_start();
1253
1254 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1255 GCIdMark gc_id_mark;
1256 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1257
1258 SvcGCMarker sgcm(SvcGCMarker::FULL);
1259 ResourceMark rm;
1260
1261 G1Log::update_level();
1262 print_heap_before_gc();
1263 trace_heap_before_gc(gc_tracer);
1264
1265 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1266
1267 verify_region_sets_optional();
1268
1269 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1270 collector_policy()->should_clear_all_soft_refs();
1271
1272 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1273
1274 {
1275 IsGCActiveMark x;
1276
1277 // Timing
1278 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1279 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1280
1281 {
1282 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1283 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1284 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1285
1286 g1_policy()->record_full_collection_start();
1287
1288 // Note: When we have a more flexible GC logging framework that
1289 // allows us to add optional attributes to a GC log record we
1290 // could consider timing and reporting how long we wait in the
1291 // following two methods.
1292 wait_while_free_regions_coming();
1293 // If we start the compaction before the CM threads finish
1294 // scanning the root regions we might trip them over as we'll
1295 // be moving objects / updating references. So let's wait until
1296 // they are done. By telling them to abort, they should complete
1297 // early.
1298 _cm->root_regions()->abort();
1299 _cm->root_regions()->wait_until_scan_finished();
1300 append_secondary_free_list_if_not_empty_with_lock();
1301
1302 gc_prologue(true);
1303 increment_total_collections(true /* full gc */);
1304 increment_old_marking_cycles_started();
1305
1306 assert(used() == recalculate_used(), "Should be equal");
1307
1308 verify_before_gc();
1309
1310 check_bitmaps("Full GC Start");
1311 pre_full_gc_dump(gc_timer);
1312
1313 #if defined(COMPILER2) || INCLUDE_JVMCI
1314 DerivedPointerTable::clear();
1315 #endif
1316
1317 // Disable discovery and empty the discovered lists
1318 // for the CM ref processor.
1319 ref_processor_cm()->disable_discovery();
1320 ref_processor_cm()->abandon_partial_discovery();
1321 ref_processor_cm()->verify_no_references_recorded();
1322
1323 // Abandon current iterations of concurrent marking and concurrent
1324 // refinement, if any are in progress. We have to do this before
1325 // wait_until_scan_finished() below.
1326 concurrent_mark()->abort();
1327
1328 // Make sure we'll choose a new allocation region afterwards.
1329 _allocator->release_mutator_alloc_region();
1330 _allocator->abandon_gc_alloc_regions();
1331 g1_rem_set()->cleanupHRRS();
1332
1333 // We should call this after we retire any currently active alloc
1334 // regions so that all the ALLOC / RETIRE events are generated
1335 // before the start GC event.
1336 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1337
1338 // We may have added regions to the current incremental collection
1339 // set between the last GC or pause and now. We need to clear the
1340 // incremental collection set and then start rebuilding it afresh
1341 // after this full GC.
1342 abandon_collection_set(g1_policy()->inc_cset_head());
1343 g1_policy()->clear_incremental_cset();
1344 g1_policy()->stop_incremental_cset_building();
1345
1346 tear_down_region_sets(false /* free_list_only */);
1347 collector_state()->set_gcs_are_young(true);
1348
1349 // See the comments in g1CollectedHeap.hpp and
1350 // G1CollectedHeap::ref_processing_init() about
1351 // how reference processing currently works in G1.
1352
1353 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1354 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1355
1356 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1357 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1358
1359 ref_processor_stw()->enable_discovery();
1360 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1361
1362 // Do collection work
1363 {
1364 HandleMark hm; // Discard invalid handles created during gc
1365 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1366 }
1367
1368 assert(num_free_regions() == 0, "we should not have added any free regions");
1369 rebuild_region_sets(false /* free_list_only */);
1370
1371 // Enqueue any discovered reference objects that have
1372 // not been removed from the discovered lists.
1373 ref_processor_stw()->enqueue_discovered_references();
1374
1375 #if defined(COMPILER2) || INCLUDE_JVMCI
1376 DerivedPointerTable::update_pointers();
1377 #endif
1378
1379 MemoryService::track_memory_usage();
1380
1381 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1382 ref_processor_stw()->verify_no_references_recorded();
1383
1384 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1385 ClassLoaderDataGraph::purge();
1386 MetaspaceAux::verify_metrics();
1387
1388 // Note: since we've just done a full GC, concurrent
1389 // marking is no longer active. Therefore we need not
1390 // re-enable reference discovery for the CM ref processor.
1391 // That will be done at the start of the next marking cycle.
1392 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1393 ref_processor_cm()->verify_no_references_recorded();
1394
1395 reset_gc_time_stamp();
1396 // Since everything potentially moved, we will clear all remembered
1397 // sets, and clear all cards. Later we will rebuild remembered
1398 // sets. We will also reset the GC time stamps of the regions.
1399 clear_rsets_post_compaction();
1400 check_gc_time_stamps();
1401
1402 resize_if_necessary_after_full_collection();
1403
1404 if (_hr_printer.is_active()) {
1405 // We should do this after we potentially resize the heap so
1406 // that all the COMMIT / UNCOMMIT events are generated before
1407 // the end GC event.
1408
1409 print_hrm_post_compaction();
1410 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1411 }
1412
1413 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1414 if (hot_card_cache->use_cache()) {
1415 hot_card_cache->reset_card_counts();
1416 hot_card_cache->reset_hot_cache();
1417 }
1418
1419 // Rebuild remembered sets of all regions.
1420 uint n_workers =
1421 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1422 workers()->active_workers(),
1423 Threads::number_of_non_daemon_threads());
1424 workers()->set_active_workers(n_workers);
1425
1426 ParRebuildRSTask rebuild_rs_task(this);
1427 workers()->run_task(&rebuild_rs_task);
1428
1429 // Rebuild the strong code root lists for each region
1430 rebuild_strong_code_roots();
1431
1432 if (true) { // FIXME
1433 MetaspaceGC::compute_new_size();
1434 }
1435
1436 #ifdef TRACESPINNING
1437 ParallelTaskTerminator::print_termination_counts();
1438 #endif
1439
1440 // Discard all rset updates
1441 JavaThread::dirty_card_queue_set().abandon_logs();
1442 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1443
1444 _young_list->reset_sampled_info();
1445 // At this point there should be no regions in the
1446 // entire heap tagged as young.
1447 assert(check_young_list_empty(true /* check_heap */),
1448 "young list should be empty at this point");
1449
1450 // Update the number of full collections that have been completed.
1451 increment_old_marking_cycles_completed(false /* concurrent */);
1452
1453 _hrm.verify_optional();
1454 verify_region_sets_optional();
1455
1456 verify_after_gc();
1457
1458 // Clear the previous marking bitmap, if needed for bitmap verification.
1459 // Note we cannot do this when we clear the next marking bitmap in
1460 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1461 // objects marked during a full GC against the previous bitmap.
1462 // But we need to clear it before calling check_bitmaps below since
1463 // the full GC has compacted objects and updated TAMS but not updated
1464 // the prev bitmap.
1465 if (G1VerifyBitmaps) {
1466 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1467 }
1468 check_bitmaps("Full GC End");
1469
1470 // Start a new incremental collection set for the next pause
1471 assert(g1_policy()->collection_set() == NULL, "must be");
1472 g1_policy()->start_incremental_cset_building();
1473
1474 clear_cset_fast_test();
1475
1476 _allocator->init_mutator_alloc_region();
1477
1478 g1_policy()->record_full_collection_end();
1479
1480 if (G1Log::fine()) {
1481 g1_policy()->print_heap_transition();
1482 }
1483
1484 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1485 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1486 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1487 // before any GC notifications are raised.
1488 g1mm()->update_sizes();
1489
1490 gc_epilogue(true);
1491 }
1492
1493 if (G1Log::finer()) {
1494 g1_policy()->print_detailed_heap_transition(true /* full */);
1495 }
1496
1497 print_heap_after_gc();
1498 trace_heap_after_gc(gc_tracer);
1499
1500 post_full_gc_dump(gc_timer);
1501
1502 gc_timer->register_gc_end();
1503 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1504 }
1505
1506 return true;
1507 }
1508
1509 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1510 // Currently, there is no facility in the do_full_collection(bool) API to notify
1511 // the caller that the collection did not succeed (e.g., because it was locked
1512 // out by the GC locker). So, right now, we'll ignore the return value.
1513 bool dummy = do_full_collection(true, /* explicit_gc */
1514 clear_all_soft_refs);
1515 }
1516
1517 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1518 // Include bytes that will be pre-allocated to support collections, as "used".
1519 const size_t used_after_gc = used();
1520 const size_t capacity_after_gc = capacity();
1521 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1522
1523 // This is enforced in arguments.cpp.
1524 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1525 "otherwise the code below doesn't make sense");
1526
1527 // We don't have floating point command-line arguments
1528 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1529 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1530 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1531 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1532
1533 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1534 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1535
1536 // We have to be careful here as these two calculations can overflow
1537 // 32-bit size_t's.
1538 double used_after_gc_d = (double) used_after_gc;
1539 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1540 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1541
1542 // Let's make sure that they are both under the max heap size, which
1543 // by default will make them fit into a size_t.
1544 double desired_capacity_upper_bound = (double) max_heap_size;
1545 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1546 desired_capacity_upper_bound);
1547 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1548 desired_capacity_upper_bound);
1549
1550 // We can now safely turn them into size_t's.
1551 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1552 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1553
1554 // This assert only makes sense here, before we adjust them
1555 // with respect to the min and max heap size.
1556 assert(minimum_desired_capacity <= maximum_desired_capacity,
1557 "minimum_desired_capacity = " SIZE_FORMAT ", "
1558 "maximum_desired_capacity = " SIZE_FORMAT,
1559 minimum_desired_capacity, maximum_desired_capacity);
1560
1561 // Should not be greater than the heap max size. No need to adjust
1562 // it with respect to the heap min size as it's a lower bound (i.e.,
1563 // we'll try to make the capacity larger than it, not smaller).
1564 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1565 // Should not be less than the heap min size. No need to adjust it
1566 // with respect to the heap max size as it's an upper bound (i.e.,
1567 // we'll try to make the capacity smaller than it, not greater).
1568 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1569
1570 if (capacity_after_gc < minimum_desired_capacity) {
1571 // Don't expand unless it's significant
1572 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1573 ergo_verbose4(ErgoHeapSizing,
1574 "attempt heap expansion",
1575 ergo_format_reason("capacity lower than "
1576 "min desired capacity after Full GC")
1577 ergo_format_byte("capacity")
1578 ergo_format_byte("occupancy")
1579 ergo_format_byte_perc("min desired capacity"),
1580 capacity_after_gc, used_after_gc,
1581 minimum_desired_capacity, (double) MinHeapFreeRatio);
1582 expand(expand_bytes);
1583
1584 // No expansion, now see if we want to shrink
1585 } else if (capacity_after_gc > maximum_desired_capacity) {
1586 // Capacity too large, compute shrinking size
1587 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1588 ergo_verbose4(ErgoHeapSizing,
1589 "attempt heap shrinking",
1590 ergo_format_reason("capacity higher than "
1591 "max desired capacity after Full GC")
1592 ergo_format_byte("capacity")
1593 ergo_format_byte("occupancy")
1594 ergo_format_byte_perc("max desired capacity"),
1595 capacity_after_gc, used_after_gc,
1596 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1597 shrink(shrink_bytes);
1598 }
1599 }
1600
1601 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1602 AllocationContext_t context,
1603 bool do_gc,
1604 bool clear_all_soft_refs,
1605 bool expect_null_mutator_alloc_region,
1606 bool* gc_succeeded) {
1607 *gc_succeeded = true;
1608 // Let's attempt the allocation first.
1609 HeapWord* result =
1610 attempt_allocation_at_safepoint(word_size,
1611 context,
1612 expect_null_mutator_alloc_region);
1613 if (result != NULL) {
1614 assert(*gc_succeeded, "sanity");
1615 return result;
1616 }
1617
1618 // In a G1 heap, we're supposed to keep allocation from failing by
1619 // incremental pauses. Therefore, at least for now, we'll favor
1620 // expansion over collection. (This might change in the future if we can
1621 // do something smarter than full collection to satisfy a failed alloc.)
1622 result = expand_and_allocate(word_size, context);
1623 if (result != NULL) {
1624 assert(*gc_succeeded, "sanity");
1625 return result;
1626 }
1627
1628 if (do_gc) {
1629 // Expansion didn't work, we'll try to do a Full GC.
1630 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1631 clear_all_soft_refs);
1632 }
1633
1634 return NULL;
1635 }
1636
1637 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1638 AllocationContext_t context,
1639 bool* succeeded) {
1640 assert_at_safepoint(true /* should_be_vm_thread */);
1641
1642 // Attempts to allocate followed by Full GC.
1643 HeapWord* result =
1644 satisfy_failed_allocation_helper(word_size,
1645 context,
1646 true, /* do_gc */
1647 false, /* clear_all_soft_refs */
1648 false, /* expect_null_mutator_alloc_region */
1649 succeeded);
1650
1651 if (result != NULL || !*succeeded) {
1652 return result;
1653 }
1654
1655 // Attempts to allocate followed by Full GC that will collect all soft references.
1656 result = satisfy_failed_allocation_helper(word_size,
1657 context,
1658 true, /* do_gc */
1659 true, /* clear_all_soft_refs */
1660 true, /* expect_null_mutator_alloc_region */
1661 succeeded);
1662
1663 if (result != NULL || !*succeeded) {
1664 return result;
1665 }
1666
1667 // Attempts to allocate, no GC
1668 result = satisfy_failed_allocation_helper(word_size,
1669 context,
1670 false, /* do_gc */
1671 false, /* clear_all_soft_refs */
1672 true, /* expect_null_mutator_alloc_region */
1673 succeeded);
1674
1675 if (result != NULL) {
1676 assert(*succeeded, "sanity");
1677 return result;
1678 }
1679
1680 assert(!collector_policy()->should_clear_all_soft_refs(),
1681 "Flag should have been handled and cleared prior to this point");
1682
1683 // What else? We might try synchronous finalization later. If the total
1684 // space available is large enough for the allocation, then a more
1685 // complete compaction phase than we've tried so far might be
1686 // appropriate.
1687 assert(*succeeded, "sanity");
1688 return NULL;
1689 }
1690
1691 // Attempting to expand the heap sufficiently
1692 // to support an allocation of the given "word_size". If
1693 // successful, perform the allocation and return the address of the
1694 // allocated block, or else "NULL".
1695
1696 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1697 assert_at_safepoint(true /* should_be_vm_thread */);
1698
1699 verify_region_sets_optional();
1700
1701 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1702 ergo_verbose1(ErgoHeapSizing,
1703 "attempt heap expansion",
1704 ergo_format_reason("allocation request failed")
1705 ergo_format_byte("allocation request"),
1706 word_size * HeapWordSize);
1707 if (expand(expand_bytes)) {
1708 _hrm.verify_optional();
1709 verify_region_sets_optional();
1710 return attempt_allocation_at_safepoint(word_size,
1711 context,
1712 false /* expect_null_mutator_alloc_region */);
1713 }
1714 return NULL;
1715 }
1716
1717 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1718 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1719 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1720 HeapRegion::GrainBytes);
1721 ergo_verbose2(ErgoHeapSizing,
1722 "expand the heap",
1723 ergo_format_byte("requested expansion amount")
1724 ergo_format_byte("attempted expansion amount"),
1725 expand_bytes, aligned_expand_bytes);
1726
1727 if (is_maximal_no_gc()) {
1728 ergo_verbose0(ErgoHeapSizing,
1729 "did not expand the heap",
1730 ergo_format_reason("heap already fully expanded"));
1731 return false;
1732 }
1733
1734 double expand_heap_start_time_sec = os::elapsedTime();
1735 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1736 assert(regions_to_expand > 0, "Must expand by at least one region");
1737
1738 uint expanded_by = _hrm.expand_by(regions_to_expand);
1739 if (expand_time_ms != NULL) {
1740 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1741 }
1742
1743 if (expanded_by > 0) {
1744 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1745 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1746 g1_policy()->record_new_heap_size(num_regions());
1747 } else {
1748 ergo_verbose0(ErgoHeapSizing,
1749 "did not expand the heap",
1750 ergo_format_reason("heap expansion operation failed"));
1751 // The expansion of the virtual storage space was unsuccessful.
1752 // Let's see if it was because we ran out of swap.
1753 if (G1ExitOnExpansionFailure &&
1754 _hrm.available() >= regions_to_expand) {
1755 // We had head room...
1756 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1757 }
1758 }
1759 return regions_to_expand > 0;
1760 }
1761
1762 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1763 size_t aligned_shrink_bytes =
1764 ReservedSpace::page_align_size_down(shrink_bytes);
1765 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1766 HeapRegion::GrainBytes);
1767 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1768
1769 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1770 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1771
1772 ergo_verbose3(ErgoHeapSizing,
1773 "shrink the heap",
1774 ergo_format_byte("requested shrinking amount")
1775 ergo_format_byte("aligned shrinking amount")
1776 ergo_format_byte("attempted shrinking amount"),
1777 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1778 if (num_regions_removed > 0) {
1779 g1_policy()->record_new_heap_size(num_regions());
1780 } else {
1781 ergo_verbose0(ErgoHeapSizing,
1782 "did not shrink the heap",
1783 ergo_format_reason("heap shrinking operation failed"));
1784 }
1785 }
1786
1787 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1788 verify_region_sets_optional();
1789
1790 // We should only reach here at the end of a Full GC which means we
1791 // should not not be holding to any GC alloc regions. The method
1792 // below will make sure of that and do any remaining clean up.
1793 _allocator->abandon_gc_alloc_regions();
1794
1795 // Instead of tearing down / rebuilding the free lists here, we
1796 // could instead use the remove_all_pending() method on free_list to
1797 // remove only the ones that we need to remove.
1798 tear_down_region_sets(true /* free_list_only */);
1799 shrink_helper(shrink_bytes);
1800 rebuild_region_sets(true /* free_list_only */);
1801
1802 _hrm.verify_optional();
1803 verify_region_sets_optional();
1804 }
1805
1806 // Public methods.
1807
1808 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1809 CollectedHeap(),
1810 _g1_policy(policy_),
1811 _dirty_card_queue_set(false),
1812 _is_alive_closure_cm(this),
1813 _is_alive_closure_stw(this),
1814 _ref_processor_cm(NULL),
1815 _ref_processor_stw(NULL),
1816 _bot_shared(NULL),
1817 _cg1r(NULL),
1818 _g1mm(NULL),
1819 _refine_cte_cl(NULL),
1820 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1821 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1822 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1823 _humongous_reclaim_candidates(),
1824 _has_humongous_reclaim_candidates(false),
1825 _archive_allocator(NULL),
1826 _free_regions_coming(false),
1827 _young_list(new YoungList(this)),
1828 _gc_time_stamp(0),
1829 _summary_bytes_used(0),
1830 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1831 _old_evac_stats(OldPLABSize, PLABWeight),
1832 _expand_heap_after_alloc_failure(true),
1833 _old_marking_cycles_started(0),
1834 _old_marking_cycles_completed(0),
1835 _heap_summary_sent(false),
1836 _in_cset_fast_test(),
1837 _dirty_cards_region_list(NULL),
1838 _worker_cset_start_region(NULL),
1839 _worker_cset_start_region_time_stamp(NULL),
1840 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1841 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1842 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1843 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1844
1845 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1846 /* are_GC_task_threads */true,
1847 /* are_ConcurrentGC_threads */false);
1848 _workers->initialize_workers();
1849
1850 _allocator = G1Allocator::create_allocator(this);
1851 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1852
1853 // Override the default _filler_array_max_size so that no humongous filler
1854 // objects are created.
1855 _filler_array_max_size = _humongous_object_threshold_in_words;
1856
1857 uint n_queues = ParallelGCThreads;
1858 _task_queues = new RefToScanQueueSet(n_queues);
1859
1860 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1861 assert(n_rem_sets > 0, "Invariant.");
1862
1863 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1864 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1865 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1866
1867 for (uint i = 0; i < n_queues; i++) {
1868 RefToScanQueue* q = new RefToScanQueue();
1869 q->initialize();
1870 _task_queues->register_queue(i, q);
1871 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1872 }
1873 clear_cset_start_regions();
1874
1875 // Initialize the G1EvacuationFailureALot counters and flags.
1876 NOT_PRODUCT(reset_evacuation_should_fail();)
1877
1878 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1879 }
1880
1881 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1882 size_t size,
1883 size_t translation_factor) {
1884 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1885 // Allocate a new reserved space, preferring to use large pages.
1886 ReservedSpace rs(size, preferred_page_size);
1887 G1RegionToSpaceMapper* result =
1888 G1RegionToSpaceMapper::create_mapper(rs,
1889 size,
1890 rs.alignment(),
1891 HeapRegion::GrainBytes,
1892 translation_factor,
1893 mtGC);
1894 if (TracePageSizes) {
1895 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1896 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1897 }
1898 return result;
1899 }
1900
1901 jint G1CollectedHeap::initialize() {
1902 CollectedHeap::pre_initialize();
1903 os::enable_vtime();
1904
1905 G1Log::init();
1906
1907 // Necessary to satisfy locking discipline assertions.
1908
1909 MutexLocker x(Heap_lock);
1910
1911 // We have to initialize the printer before committing the heap, as
1912 // it will be used then.
1913 _hr_printer.set_active(G1PrintHeapRegions);
1914
1915 // While there are no constraints in the GC code that HeapWordSize
1916 // be any particular value, there are multiple other areas in the
1917 // system which believe this to be true (e.g. oop->object_size in some
1918 // cases incorrectly returns the size in wordSize units rather than
1919 // HeapWordSize).
1920 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1921
1922 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1923 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1924 size_t heap_alignment = collector_policy()->heap_alignment();
1925
1926 // Ensure that the sizes are properly aligned.
1927 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1928 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1929 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1930
1931 _refine_cte_cl = new RefineCardTableEntryClosure();
1932
1933 jint ecode = JNI_OK;
1934 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1935 if (_cg1r == NULL) {
1936 return ecode;
1937 }
1938
1939 // Reserve the maximum.
1940
1941 // When compressed oops are enabled, the preferred heap base
1942 // is calculated by subtracting the requested size from the
1943 // 32Gb boundary and using the result as the base address for
1944 // heap reservation. If the requested size is not aligned to
1945 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1946 // into the ReservedHeapSpace constructor) then the actual
1947 // base of the reserved heap may end up differing from the
1948 // address that was requested (i.e. the preferred heap base).
1949 // If this happens then we could end up using a non-optimal
1950 // compressed oops mode.
1951
1952 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1953 heap_alignment);
1954
1955 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1956
1957 // Create the barrier set for the entire reserved region.
1958 G1SATBCardTableLoggingModRefBS* bs
1959 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1960 bs->initialize();
1961 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1962 set_barrier_set(bs);
1963
1964 // Also create a G1 rem set.
1965 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1966
1967 // Carve out the G1 part of the heap.
1968
1969 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1970 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1971 G1RegionToSpaceMapper* heap_storage =
1972 G1RegionToSpaceMapper::create_mapper(g1_rs,
1973 g1_rs.size(),
1974 page_size,
1975 HeapRegion::GrainBytes,
1976 1,
1977 mtJavaHeap);
1978 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1979 max_byte_size, page_size,
1980 heap_rs.base(),
1981 heap_rs.size());
1982 heap_storage->set_mapping_changed_listener(&_listener);
1983
1984 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1985 G1RegionToSpaceMapper* bot_storage =
1986 create_aux_memory_mapper("Block offset table",
1987 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1988 G1BlockOffsetSharedArray::heap_map_factor());
1989
1990 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1991 G1RegionToSpaceMapper* cardtable_storage =
1992 create_aux_memory_mapper("Card table",
1993 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1994 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1995
1996 G1RegionToSpaceMapper* card_counts_storage =
1997 create_aux_memory_mapper("Card counts table",
1998 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1999 G1CardCounts::heap_map_factor());
2000
2001 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2002 G1RegionToSpaceMapper* prev_bitmap_storage =
2003 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2004 G1RegionToSpaceMapper* next_bitmap_storage =
2005 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2006
2007 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2008 g1_barrier_set()->initialize(cardtable_storage);
2009 // Do later initialization work for concurrent refinement.
2010 _cg1r->init(card_counts_storage);
2011
2012 // 6843694 - ensure that the maximum region index can fit
2013 // in the remembered set structures.
2014 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2015 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2016
2017 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2018 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2019 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2020 "too many cards per region");
2021
2022 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2023
2024 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2025
2026 {
2027 HeapWord* start = _hrm.reserved().start();
2028 HeapWord* end = _hrm.reserved().end();
2029 size_t granularity = HeapRegion::GrainBytes;
2030
2031 _in_cset_fast_test.initialize(start, end, granularity);
2032 _humongous_reclaim_candidates.initialize(start, end, granularity);
2033 }
2034
2035 // Create the ConcurrentMark data structure and thread.
2036 // (Must do this late, so that "max_regions" is defined.)
2037 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2038 if (_cm == NULL || !_cm->completed_initialization()) {
2039 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2040 return JNI_ENOMEM;
2041 }
2042 _cmThread = _cm->cmThread();
2043
2044 // Initialize the from_card cache structure of HeapRegionRemSet.
2045 HeapRegionRemSet::init_heap(max_regions());
2046
2047 // Now expand into the initial heap size.
2048 if (!expand(init_byte_size)) {
2049 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2050 return JNI_ENOMEM;
2051 }
2052
2053 // Perform any initialization actions delegated to the policy.
2054 g1_policy()->init();
2055
2056 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2057 SATB_Q_FL_lock,
2058 G1SATBProcessCompletedThreshold,
2059 Shared_SATB_Q_lock);
2060
2061 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2062 DirtyCardQ_CBL_mon,
2063 DirtyCardQ_FL_lock,
2064 concurrent_g1_refine()->yellow_zone(),
2065 concurrent_g1_refine()->red_zone(),
2066 Shared_DirtyCardQ_lock);
2067
2068 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2069 DirtyCardQ_CBL_mon,
2070 DirtyCardQ_FL_lock,
2071 -1, // never trigger processing
2072 -1, // no limit on length
2073 Shared_DirtyCardQ_lock,
2074 &JavaThread::dirty_card_queue_set());
2075
2076 // Here we allocate the dummy HeapRegion that is required by the
2077 // G1AllocRegion class.
2078 HeapRegion* dummy_region = _hrm.get_dummy_region();
2079
2080 // We'll re-use the same region whether the alloc region will
2081 // require BOT updates or not and, if it doesn't, then a non-young
2082 // region will complain that it cannot support allocations without
2083 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2084 dummy_region->set_eden();
2085 // Make sure it's full.
2086 dummy_region->set_top(dummy_region->end());
2087 G1AllocRegion::setup(this, dummy_region);
2088
2089 _allocator->init_mutator_alloc_region();
2090
2091 // Do create of the monitoring and management support so that
2092 // values in the heap have been properly initialized.
2093 _g1mm = new G1MonitoringSupport(this);
2094
2095 G1StringDedup::initialize();
2096
2097 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2098 for (uint i = 0; i < ParallelGCThreads; i++) {
2099 new (&_preserved_objs[i]) OopAndMarkOopStack();
2100 }
2101
2102 return JNI_OK;
2103 }
2104
2105 void G1CollectedHeap::stop() {
2106 // Stop all concurrent threads. We do this to make sure these threads
2107 // do not continue to execute and access resources (e.g. gclog_or_tty)
2108 // that are destroyed during shutdown.
2109 _cg1r->stop();
2110 _cmThread->stop();
2111 if (G1StringDedup::is_enabled()) {
2112 G1StringDedup::stop();
2113 }
2114 }
2115
2116 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2117 return HeapRegion::max_region_size();
2118 }
2119
2120 void G1CollectedHeap::post_initialize() {
2121 CollectedHeap::post_initialize();
2122 ref_processing_init();
2123 }
2124
2125 void G1CollectedHeap::ref_processing_init() {
2126 // Reference processing in G1 currently works as follows:
2127 //
2128 // * There are two reference processor instances. One is
2129 // used to record and process discovered references
2130 // during concurrent marking; the other is used to
2131 // record and process references during STW pauses
2132 // (both full and incremental).
2133 // * Both ref processors need to 'span' the entire heap as
2134 // the regions in the collection set may be dotted around.
2135 //
2136 // * For the concurrent marking ref processor:
2137 // * Reference discovery is enabled at initial marking.
2138 // * Reference discovery is disabled and the discovered
2139 // references processed etc during remarking.
2140 // * Reference discovery is MT (see below).
2141 // * Reference discovery requires a barrier (see below).
2142 // * Reference processing may or may not be MT
2143 // (depending on the value of ParallelRefProcEnabled
2144 // and ParallelGCThreads).
2145 // * A full GC disables reference discovery by the CM
2146 // ref processor and abandons any entries on it's
2147 // discovered lists.
2148 //
2149 // * For the STW processor:
2150 // * Non MT discovery is enabled at the start of a full GC.
2151 // * Processing and enqueueing during a full GC is non-MT.
2152 // * During a full GC, references are processed after marking.
2153 //
2154 // * Discovery (may or may not be MT) is enabled at the start
2155 // of an incremental evacuation pause.
2156 // * References are processed near the end of a STW evacuation pause.
2157 // * For both types of GC:
2158 // * Discovery is atomic - i.e. not concurrent.
2159 // * Reference discovery will not need a barrier.
2160
2161 MemRegion mr = reserved_region();
2162
2163 // Concurrent Mark ref processor
2164 _ref_processor_cm =
2165 new ReferenceProcessor(mr, // span
2166 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2167 // mt processing
2168 ParallelGCThreads,
2169 // degree of mt processing
2170 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2171 // mt discovery
2172 MAX2(ParallelGCThreads, ConcGCThreads),
2173 // degree of mt discovery
2174 false,
2175 // Reference discovery is not atomic
2176 &_is_alive_closure_cm);
2177 // is alive closure
2178 // (for efficiency/performance)
2179
2180 // STW ref processor
2181 _ref_processor_stw =
2182 new ReferenceProcessor(mr, // span
2183 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2184 // mt processing
2185 ParallelGCThreads,
2186 // degree of mt processing
2187 (ParallelGCThreads > 1),
2188 // mt discovery
2189 ParallelGCThreads,
2190 // degree of mt discovery
2191 true,
2192 // Reference discovery is atomic
2193 &_is_alive_closure_stw);
2194 // is alive closure
2195 // (for efficiency/performance)
2196 }
2197
2198 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2199 return g1_policy();
2200 }
2201
2202 size_t G1CollectedHeap::capacity() const {
2203 return _hrm.length() * HeapRegion::GrainBytes;
2204 }
2205
2206 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2207 hr->reset_gc_time_stamp();
2208 }
2209
2210 #ifndef PRODUCT
2211
2212 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2213 private:
2214 unsigned _gc_time_stamp;
2215 bool _failures;
2216
2217 public:
2218 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2219 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2220
2221 virtual bool doHeapRegion(HeapRegion* hr) {
2222 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2223 if (_gc_time_stamp != region_gc_time_stamp) {
2224 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2225 "expected %d", HR_FORMAT_PARAMS(hr),
2226 region_gc_time_stamp, _gc_time_stamp);
2227 _failures = true;
2228 }
2229 return false;
2230 }
2231
2232 bool failures() { return _failures; }
2233 };
2234
2235 void G1CollectedHeap::check_gc_time_stamps() {
2236 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2237 heap_region_iterate(&cl);
2238 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2239 }
2240 #endif // PRODUCT
2241
2242 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2243 _cg1r->hot_card_cache()->drain(cl, worker_i);
2244 }
2245
2246 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2247 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2248 size_t n_completed_buffers = 0;
2249 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2250 n_completed_buffers++;
2251 }
2252 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2253 dcqs.clear_n_completed_buffers();
2254 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2255 }
2256
2257 // Computes the sum of the storage used by the various regions.
2258 size_t G1CollectedHeap::used() const {
2259 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2260 if (_archive_allocator != NULL) {
2261 result += _archive_allocator->used();
2262 }
2263 return result;
2264 }
2265
2266 size_t G1CollectedHeap::used_unlocked() const {
2267 return _summary_bytes_used;
2268 }
2269
2270 class SumUsedClosure: public HeapRegionClosure {
2271 size_t _used;
2272 public:
2273 SumUsedClosure() : _used(0) {}
2274 bool doHeapRegion(HeapRegion* r) {
2275 _used += r->used();
2276 return false;
2277 }
2278 size_t result() { return _used; }
2279 };
2280
2281 size_t G1CollectedHeap::recalculate_used() const {
2282 double recalculate_used_start = os::elapsedTime();
2283
2284 SumUsedClosure blk;
2285 heap_region_iterate(&blk);
2286
2287 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2288 return blk.result();
2289 }
2290
2291 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2292 switch (cause) {
2293 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2294 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2295 case GCCause::_update_allocation_context_stats_inc: return true;
2296 case GCCause::_wb_conc_mark: return true;
2297 default : return false;
2298 }
2299 }
2300
2301 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2302 switch (cause) {
2303 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2304 case GCCause::_g1_humongous_allocation: return true;
2305 default: return is_user_requested_concurrent_full_gc(cause);
2306 }
2307 }
2308
2309 #ifndef PRODUCT
2310 void G1CollectedHeap::allocate_dummy_regions() {
2311 // Let's fill up most of the region
2312 size_t word_size = HeapRegion::GrainWords - 1024;
2313 // And as a result the region we'll allocate will be humongous.
2314 guarantee(is_humongous(word_size), "sanity");
2315
2316 // _filler_array_max_size is set to humongous object threshold
2317 // but temporarily change it to use CollectedHeap::fill_with_object().
2318 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2319
2320 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2321 // Let's use the existing mechanism for the allocation
2322 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2323 AllocationContext::system());
2324 if (dummy_obj != NULL) {
2325 MemRegion mr(dummy_obj, word_size);
2326 CollectedHeap::fill_with_object(mr);
2327 } else {
2328 // If we can't allocate once, we probably cannot allocate
2329 // again. Let's get out of the loop.
2330 break;
2331 }
2332 }
2333 }
2334 #endif // !PRODUCT
2335
2336 void G1CollectedHeap::increment_old_marking_cycles_started() {
2337 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2338 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2339 "Wrong marking cycle count (started: %d, completed: %d)",
2340 _old_marking_cycles_started, _old_marking_cycles_completed);
2341
2342 _old_marking_cycles_started++;
2343 }
2344
2345 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2346 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2347
2348 // We assume that if concurrent == true, then the caller is a
2349 // concurrent thread that was joined the Suspendible Thread
2350 // Set. If there's ever a cheap way to check this, we should add an
2351 // assert here.
2352
2353 // Given that this method is called at the end of a Full GC or of a
2354 // concurrent cycle, and those can be nested (i.e., a Full GC can
2355 // interrupt a concurrent cycle), the number of full collections
2356 // completed should be either one (in the case where there was no
2357 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2358 // behind the number of full collections started.
2359
2360 // This is the case for the inner caller, i.e. a Full GC.
2361 assert(concurrent ||
2362 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2363 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2364 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2365 "is inconsistent with _old_marking_cycles_completed = %u",
2366 _old_marking_cycles_started, _old_marking_cycles_completed);
2367
2368 // This is the case for the outer caller, i.e. the concurrent cycle.
2369 assert(!concurrent ||
2370 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2371 "for outer caller (concurrent cycle): "
2372 "_old_marking_cycles_started = %u "
2373 "is inconsistent with _old_marking_cycles_completed = %u",
2374 _old_marking_cycles_started, _old_marking_cycles_completed);
2375
2376 _old_marking_cycles_completed += 1;
2377
2378 // We need to clear the "in_progress" flag in the CM thread before
2379 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2380 // is set) so that if a waiter requests another System.gc() it doesn't
2381 // incorrectly see that a marking cycle is still in progress.
2382 if (concurrent) {
2383 _cmThread->set_idle();
2384 }
2385
2386 // This notify_all() will ensure that a thread that called
2387 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2388 // and it's waiting for a full GC to finish will be woken up. It is
2389 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2390 FullGCCount_lock->notify_all();
2391 }
2392
2393 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2394 GCIdMarkAndRestore conc_gc_id_mark;
2395 collector_state()->set_concurrent_cycle_started(true);
2396 _gc_timer_cm->register_gc_start(start_time);
2397
2398 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2399 trace_heap_before_gc(_gc_tracer_cm);
2400 _cmThread->set_gc_id(GCId::current());
2401 }
2402
2403 void G1CollectedHeap::register_concurrent_cycle_end() {
2404 if (collector_state()->concurrent_cycle_started()) {
2405 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2406 if (_cm->has_aborted()) {
2407 _gc_tracer_cm->report_concurrent_mode_failure();
2408 }
2409
2410 _gc_timer_cm->register_gc_end();
2411 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2412
2413 // Clear state variables to prepare for the next concurrent cycle.
2414 collector_state()->set_concurrent_cycle_started(false);
2415 _heap_summary_sent = false;
2416 }
2417 }
2418
2419 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2420 if (collector_state()->concurrent_cycle_started()) {
2421 // This function can be called when:
2422 // the cleanup pause is run
2423 // the concurrent cycle is aborted before the cleanup pause.
2424 // the concurrent cycle is aborted after the cleanup pause,
2425 // but before the concurrent cycle end has been registered.
2426 // Make sure that we only send the heap information once.
2427 if (!_heap_summary_sent) {
2428 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2429 trace_heap_after_gc(_gc_tracer_cm);
2430 _heap_summary_sent = true;
2431 }
2432 }
2433 }
2434
2435 void G1CollectedHeap::collect(GCCause::Cause cause) {
2436 assert_heap_not_locked();
2437
2438 uint gc_count_before;
2439 uint old_marking_count_before;
2440 uint full_gc_count_before;
2441 bool retry_gc;
2442
2443 do {
2444 retry_gc = false;
2445
2446 {
2447 MutexLocker ml(Heap_lock);
2448
2449 // Read the GC count while holding the Heap_lock
2450 gc_count_before = total_collections();
2451 full_gc_count_before = total_full_collections();
2452 old_marking_count_before = _old_marking_cycles_started;
2453 }
2454
2455 if (should_do_concurrent_full_gc(cause)) {
2456 // Schedule an initial-mark evacuation pause that will start a
2457 // concurrent cycle. We're setting word_size to 0 which means that
2458 // we are not requesting a post-GC allocation.
2459 VM_G1IncCollectionPause op(gc_count_before,
2460 0, /* word_size */
2461 true, /* should_initiate_conc_mark */
2462 g1_policy()->max_pause_time_ms(),
2463 cause);
2464 op.set_allocation_context(AllocationContext::current());
2465
2466 VMThread::execute(&op);
2467 if (!op.pause_succeeded()) {
2468 if (old_marking_count_before == _old_marking_cycles_started) {
2469 retry_gc = op.should_retry_gc();
2470 } else {
2471 // A Full GC happened while we were trying to schedule the
2472 // initial-mark GC. No point in starting a new cycle given
2473 // that the whole heap was collected anyway.
2474 }
2475
2476 if (retry_gc) {
2477 if (GC_locker::is_active_and_needs_gc()) {
2478 GC_locker::stall_until_clear();
2479 }
2480 }
2481 }
2482 } else {
2483 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2484 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2485
2486 // Schedule a standard evacuation pause. We're setting word_size
2487 // to 0 which means that we are not requesting a post-GC allocation.
2488 VM_G1IncCollectionPause op(gc_count_before,
2489 0, /* word_size */
2490 false, /* should_initiate_conc_mark */
2491 g1_policy()->max_pause_time_ms(),
2492 cause);
2493 VMThread::execute(&op);
2494 } else {
2495 // Schedule a Full GC.
2496 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2497 VMThread::execute(&op);
2498 }
2499 }
2500 } while (retry_gc);
2501 }
2502
2503 bool G1CollectedHeap::is_in(const void* p) const {
2504 if (_hrm.reserved().contains(p)) {
2505 // Given that we know that p is in the reserved space,
2506 // heap_region_containing() should successfully
2507 // return the containing region.
2508 HeapRegion* hr = heap_region_containing(p);
2509 return hr->is_in(p);
2510 } else {
2511 return false;
2512 }
2513 }
2514
2515 #ifdef ASSERT
2516 bool G1CollectedHeap::is_in_exact(const void* p) const {
2517 bool contains = reserved_region().contains(p);
2518 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2519 if (contains && available) {
2520 return true;
2521 } else {
2522 return false;
2523 }
2524 }
2525 #endif
2526
2527 bool G1CollectedHeap::obj_in_cs(oop obj) {
2528 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2529 return r != NULL && r->in_collection_set();
2530 }
2531
2532 // Iteration functions.
2533
2534 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2535
2536 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2537 ExtendedOopClosure* _cl;
2538 public:
2539 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2540 bool doHeapRegion(HeapRegion* r) {
2541 if (!r->is_continues_humongous()) {
2542 r->oop_iterate(_cl);
2543 }
2544 return false;
2545 }
2546 };
2547
2548 // Iterates an ObjectClosure over all objects within a HeapRegion.
2549
2550 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2551 ObjectClosure* _cl;
2552 public:
2553 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2554 bool doHeapRegion(HeapRegion* r) {
2555 if (!r->is_continues_humongous()) {
2556 r->object_iterate(_cl);
2557 }
2558 return false;
2559 }
2560 };
2561
2562 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2563 IterateObjectClosureRegionClosure blk(cl);
2564 heap_region_iterate(&blk);
2565 }
2566
2567 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2568 _hrm.iterate(cl);
2569 }
2570
2571 void
2572 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2573 uint worker_id,
2574 HeapRegionClaimer *hrclaimer,
2575 bool concurrent) const {
2576 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2577 }
2578
2579 // Clear the cached CSet starting regions and (more importantly)
2580 // the time stamps. Called when we reset the GC time stamp.
2581 void G1CollectedHeap::clear_cset_start_regions() {
2582 assert(_worker_cset_start_region != NULL, "sanity");
2583 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2584
2585 for (uint i = 0; i < ParallelGCThreads; i++) {
2586 _worker_cset_start_region[i] = NULL;
2587 _worker_cset_start_region_time_stamp[i] = 0;
2588 }
2589 }
2590
2591 // Given the id of a worker, obtain or calculate a suitable
2592 // starting region for iterating over the current collection set.
2593 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2594 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2595
2596 HeapRegion* result = NULL;
2597 unsigned gc_time_stamp = get_gc_time_stamp();
2598
2599 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2600 // Cached starting region for current worker was set
2601 // during the current pause - so it's valid.
2602 // Note: the cached starting heap region may be NULL
2603 // (when the collection set is empty).
2604 result = _worker_cset_start_region[worker_i];
2605 assert(result == NULL || result->in_collection_set(), "sanity");
2606 return result;
2607 }
2608
2609 // The cached entry was not valid so let's calculate
2610 // a suitable starting heap region for this worker.
2611
2612 // We want the parallel threads to start their collection
2613 // set iteration at different collection set regions to
2614 // avoid contention.
2615 // If we have:
2616 // n collection set regions
2617 // p threads
2618 // Then thread t will start at region floor ((t * n) / p)
2619
2620 result = g1_policy()->collection_set();
2621 uint cs_size = g1_policy()->cset_region_length();
2622 uint active_workers = workers()->active_workers();
2623
2624 uint end_ind = (cs_size * worker_i) / active_workers;
2625 uint start_ind = 0;
2626
2627 if (worker_i > 0 &&
2628 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2629 // Previous workers starting region is valid
2630 // so let's iterate from there
2631 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2632 result = _worker_cset_start_region[worker_i - 1];
2633 }
2634
2635 for (uint i = start_ind; i < end_ind; i++) {
2636 result = result->next_in_collection_set();
2637 }
2638
2639 // Note: the calculated starting heap region may be NULL
2640 // (when the collection set is empty).
2641 assert(result == NULL || result->in_collection_set(), "sanity");
2642 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2643 "should be updated only once per pause");
2644 _worker_cset_start_region[worker_i] = result;
2645 OrderAccess::storestore();
2646 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2647 return result;
2648 }
2649
2650 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2651 HeapRegion* r = g1_policy()->collection_set();
2652 while (r != NULL) {
2653 HeapRegion* next = r->next_in_collection_set();
2654 if (cl->doHeapRegion(r)) {
2655 cl->incomplete();
2656 return;
2657 }
2658 r = next;
2659 }
2660 }
2661
2662 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2663 HeapRegionClosure *cl) {
2664 if (r == NULL) {
2665 // The CSet is empty so there's nothing to do.
2666 return;
2667 }
2668
2669 assert(r->in_collection_set(),
2670 "Start region must be a member of the collection set.");
2671 HeapRegion* cur = r;
2672 while (cur != NULL) {
2673 HeapRegion* next = cur->next_in_collection_set();
2674 if (cl->doHeapRegion(cur) && false) {
2675 cl->incomplete();
2676 return;
2677 }
2678 cur = next;
2679 }
2680 cur = g1_policy()->collection_set();
2681 while (cur != r) {
2682 HeapRegion* next = cur->next_in_collection_set();
2683 if (cl->doHeapRegion(cur) && false) {
2684 cl->incomplete();
2685 return;
2686 }
2687 cur = next;
2688 }
2689 }
2690
2691 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2692 HeapRegion* result = _hrm.next_region_in_heap(from);
2693 while (result != NULL && result->is_pinned()) {
2694 result = _hrm.next_region_in_heap(result);
2695 }
2696 return result;
2697 }
2698
2699 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2700 HeapRegion* hr = heap_region_containing(addr);
2701 return hr->block_start(addr);
2702 }
2703
2704 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2705 HeapRegion* hr = heap_region_containing(addr);
2706 return hr->block_size(addr);
2707 }
2708
2709 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2710 HeapRegion* hr = heap_region_containing(addr);
2711 return hr->block_is_obj(addr);
2712 }
2713
2714 bool G1CollectedHeap::supports_tlab_allocation() const {
2715 return true;
2716 }
2717
2718 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2719 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2720 }
2721
2722 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2723 return young_list()->eden_used_bytes();
2724 }
2725
2726 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2727 // must be equal to the humongous object limit.
2728 size_t G1CollectedHeap::max_tlab_size() const {
2729 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2730 }
2731
2732 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2733 AllocationContext_t context = AllocationContext::current();
2734 return _allocator->unsafe_max_tlab_alloc(context);
2735 }
2736
2737 size_t G1CollectedHeap::max_capacity() const {
2738 return _hrm.reserved().byte_size();
2739 }
2740
2741 jlong G1CollectedHeap::millis_since_last_gc() {
2742 // assert(false, "NYI");
2743 return 0;
2744 }
2745
2746 void G1CollectedHeap::prepare_for_verify() {
2747 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2748 ensure_parsability(false);
2749 }
2750 g1_rem_set()->prepare_for_verify();
2751 }
2752
2753 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2754 VerifyOption vo) {
2755 switch (vo) {
2756 case VerifyOption_G1UsePrevMarking:
2757 return hr->obj_allocated_since_prev_marking(obj);
2758 case VerifyOption_G1UseNextMarking:
2759 return hr->obj_allocated_since_next_marking(obj);
2760 case VerifyOption_G1UseMarkWord:
2761 return false;
2762 default:
2763 ShouldNotReachHere();
2764 }
2765 return false; // keep some compilers happy
2766 }
2767
2768 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2769 switch (vo) {
2770 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2771 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2772 case VerifyOption_G1UseMarkWord: return NULL;
2773 default: ShouldNotReachHere();
2774 }
2775 return NULL; // keep some compilers happy
2776 }
2777
2778 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2779 switch (vo) {
2780 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2781 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2782 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2783 default: ShouldNotReachHere();
2784 }
2785 return false; // keep some compilers happy
2786 }
2787
2788 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2789 switch (vo) {
2790 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2791 case VerifyOption_G1UseNextMarking: return "NTAMS";
2792 case VerifyOption_G1UseMarkWord: return "NONE";
2793 default: ShouldNotReachHere();
2794 }
2795 return NULL; // keep some compilers happy
2796 }
2797
2798 class VerifyRootsClosure: public OopClosure {
2799 private:
2800 G1CollectedHeap* _g1h;
2801 VerifyOption _vo;
2802 bool _failures;
2803 public:
2804 // _vo == UsePrevMarking -> use "prev" marking information,
2805 // _vo == UseNextMarking -> use "next" marking information,
2806 // _vo == UseMarkWord -> use mark word from object header.
2807 VerifyRootsClosure(VerifyOption vo) :
2808 _g1h(G1CollectedHeap::heap()),
2809 _vo(vo),
2810 _failures(false) { }
2811
2812 bool failures() { return _failures; }
2813
2814 template <class T> void do_oop_nv(T* p) {
2815 T heap_oop = oopDesc::load_heap_oop(p);
2816 if (!oopDesc::is_null(heap_oop)) {
2817 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2818 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2819 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2820 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2821 if (_vo == VerifyOption_G1UseMarkWord) {
2822 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2823 }
2824 obj->print_on(gclog_or_tty);
2825 _failures = true;
2826 }
2827 }
2828 }
2829
2830 void do_oop(oop* p) { do_oop_nv(p); }
2831 void do_oop(narrowOop* p) { do_oop_nv(p); }
2832 };
2833
2834 class G1VerifyCodeRootOopClosure: public OopClosure {
2835 G1CollectedHeap* _g1h;
2836 OopClosure* _root_cl;
2837 nmethod* _nm;
2838 VerifyOption _vo;
2839 bool _failures;
2840
2841 template <class T> void do_oop_work(T* p) {
2842 // First verify that this root is live
2843 _root_cl->do_oop(p);
2844
2845 if (!G1VerifyHeapRegionCodeRoots) {
2846 // We're not verifying the code roots attached to heap region.
2847 return;
2848 }
2849
2850 // Don't check the code roots during marking verification in a full GC
2851 if (_vo == VerifyOption_G1UseMarkWord) {
2852 return;
2853 }
2854
2855 // Now verify that the current nmethod (which contains p) is
2856 // in the code root list of the heap region containing the
2857 // object referenced by p.
2858
2859 T heap_oop = oopDesc::load_heap_oop(p);
2860 if (!oopDesc::is_null(heap_oop)) {
2861 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2862
2863 // Now fetch the region containing the object
2864 HeapRegion* hr = _g1h->heap_region_containing(obj);
2865 HeapRegionRemSet* hrrs = hr->rem_set();
2866 // Verify that the strong code root list for this region
2867 // contains the nmethod
2868 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2869 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2870 "from nmethod " PTR_FORMAT " not in strong "
2871 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2872 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2873 _failures = true;
2874 }
2875 }
2876 }
2877
2878 public:
2879 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2880 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2881
2882 void do_oop(oop* p) { do_oop_work(p); }
2883 void do_oop(narrowOop* p) { do_oop_work(p); }
2884
2885 void set_nmethod(nmethod* nm) { _nm = nm; }
2886 bool failures() { return _failures; }
2887 };
2888
2889 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2890 G1VerifyCodeRootOopClosure* _oop_cl;
2891
2892 public:
2893 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2894 _oop_cl(oop_cl) {}
2895
2896 void do_code_blob(CodeBlob* cb) {
2897 nmethod* nm = cb->as_nmethod_or_null();
2898 if (nm != NULL) {
2899 _oop_cl->set_nmethod(nm);
2900 nm->oops_do(_oop_cl);
2901 }
2902 }
2903 };
2904
2905 class YoungRefCounterClosure : public OopClosure {
2906 G1CollectedHeap* _g1h;
2907 int _count;
2908 public:
2909 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2910 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2911 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2912
2913 int count() { return _count; }
2914 void reset_count() { _count = 0; };
2915 };
2916
2917 class VerifyKlassClosure: public KlassClosure {
2918 YoungRefCounterClosure _young_ref_counter_closure;
2919 OopClosure *_oop_closure;
2920 public:
2921 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2922 void do_klass(Klass* k) {
2923 k->oops_do(_oop_closure);
2924
2925 _young_ref_counter_closure.reset_count();
2926 k->oops_do(&_young_ref_counter_closure);
2927 if (_young_ref_counter_closure.count() > 0) {
2928 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2929 }
2930 }
2931 };
2932
2933 class VerifyLivenessOopClosure: public OopClosure {
2934 G1CollectedHeap* _g1h;
2935 VerifyOption _vo;
2936 public:
2937 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2938 _g1h(g1h), _vo(vo)
2939 { }
2940 void do_oop(narrowOop *p) { do_oop_work(p); }
2941 void do_oop( oop *p) { do_oop_work(p); }
2942
2943 template <class T> void do_oop_work(T *p) {
2944 oop obj = oopDesc::load_decode_heap_oop(p);
2945 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2946 "Dead object referenced by a not dead object");
2947 }
2948 };
2949
2950 class VerifyObjsInRegionClosure: public ObjectClosure {
2951 private:
2952 G1CollectedHeap* _g1h;
2953 size_t _live_bytes;
2954 HeapRegion *_hr;
2955 VerifyOption _vo;
2956 public:
2957 // _vo == UsePrevMarking -> use "prev" marking information,
2958 // _vo == UseNextMarking -> use "next" marking information,
2959 // _vo == UseMarkWord -> use mark word from object header.
2960 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2961 : _live_bytes(0), _hr(hr), _vo(vo) {
2962 _g1h = G1CollectedHeap::heap();
2963 }
2964 void do_object(oop o) {
2965 VerifyLivenessOopClosure isLive(_g1h, _vo);
2966 assert(o != NULL, "Huh?");
2967 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2968 // If the object is alive according to the mark word,
2969 // then verify that the marking information agrees.
2970 // Note we can't verify the contra-positive of the
2971 // above: if the object is dead (according to the mark
2972 // word), it may not be marked, or may have been marked
2973 // but has since became dead, or may have been allocated
2974 // since the last marking.
2975 if (_vo == VerifyOption_G1UseMarkWord) {
2976 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2977 }
2978
2979 o->oop_iterate_no_header(&isLive);
2980 if (!_hr->obj_allocated_since_prev_marking(o)) {
2981 size_t obj_size = o->size(); // Make sure we don't overflow
2982 _live_bytes += (obj_size * HeapWordSize);
2983 }
2984 }
2985 }
2986 size_t live_bytes() { return _live_bytes; }
2987 };
2988
2989 class VerifyArchiveOopClosure: public OopClosure {
2990 public:
2991 VerifyArchiveOopClosure(HeapRegion *hr) { }
2992 void do_oop(narrowOop *p) { do_oop_work(p); }
2993 void do_oop( oop *p) { do_oop_work(p); }
2994
2995 template <class T> void do_oop_work(T *p) {
2996 oop obj = oopDesc::load_decode_heap_oop(p);
2997 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2998 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2999 p2i(p), p2i(obj));
3000 }
3001 };
3002
3003 class VerifyArchiveRegionClosure: public ObjectClosure {
3004 public:
3005 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3006 // Verify that all object pointers are to archive regions.
3007 void do_object(oop o) {
3008 VerifyArchiveOopClosure checkOop(NULL);
3009 assert(o != NULL, "Should not be here for NULL oops");
3010 o->oop_iterate_no_header(&checkOop);
3011 }
3012 };
3013
3014 class VerifyRegionClosure: public HeapRegionClosure {
3015 private:
3016 bool _par;
3017 VerifyOption _vo;
3018 bool _failures;
3019 public:
3020 // _vo == UsePrevMarking -> use "prev" marking information,
3021 // _vo == UseNextMarking -> use "next" marking information,
3022 // _vo == UseMarkWord -> use mark word from object header.
3023 VerifyRegionClosure(bool par, VerifyOption vo)
3024 : _par(par),
3025 _vo(vo),
3026 _failures(false) {}
3027
3028 bool failures() {
3029 return _failures;
3030 }
3031
3032 bool doHeapRegion(HeapRegion* r) {
3033 // For archive regions, verify there are no heap pointers to
3034 // non-pinned regions. For all others, verify liveness info.
3035 if (r->is_archive()) {
3036 VerifyArchiveRegionClosure verify_oop_pointers(r);
3037 r->object_iterate(&verify_oop_pointers);
3038 return true;
3039 }
3040 if (!r->is_continues_humongous()) {
3041 bool failures = false;
3042 r->verify(_vo, &failures);
3043 if (failures) {
3044 _failures = true;
3045 } else if (!r->is_starts_humongous()) {
3046 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3047 r->object_iterate(¬_dead_yet_cl);
3048 if (_vo != VerifyOption_G1UseNextMarking) {
3049 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3050 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3051 "max_live_bytes " SIZE_FORMAT " "
3052 "< calculated " SIZE_FORMAT,
3053 p2i(r->bottom()), p2i(r->end()),
3054 r->max_live_bytes(),
3055 not_dead_yet_cl.live_bytes());
3056 _failures = true;
3057 }
3058 } else {
3059 // When vo == UseNextMarking we cannot currently do a sanity
3060 // check on the live bytes as the calculation has not been
3061 // finalized yet.
3062 }
3063 }
3064 }
3065 return false; // stop the region iteration if we hit a failure
3066 }
3067 };
3068
3069 // This is the task used for parallel verification of the heap regions
3070
3071 class G1ParVerifyTask: public AbstractGangTask {
3072 private:
3073 G1CollectedHeap* _g1h;
3074 VerifyOption _vo;
3075 bool _failures;
3076 HeapRegionClaimer _hrclaimer;
3077
3078 public:
3079 // _vo == UsePrevMarking -> use "prev" marking information,
3080 // _vo == UseNextMarking -> use "next" marking information,
3081 // _vo == UseMarkWord -> use mark word from object header.
3082 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3083 AbstractGangTask("Parallel verify task"),
3084 _g1h(g1h),
3085 _vo(vo),
3086 _failures(false),
3087 _hrclaimer(g1h->workers()->active_workers()) {}
3088
3089 bool failures() {
3090 return _failures;
3091 }
3092
3093 void work(uint worker_id) {
3094 HandleMark hm;
3095 VerifyRegionClosure blk(true, _vo);
3096 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3097 if (blk.failures()) {
3098 _failures = true;
3099 }
3100 }
3101 };
3102
3103 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3104 if (SafepointSynchronize::is_at_safepoint()) {
3105 assert(Thread::current()->is_VM_thread(),
3106 "Expected to be executed serially by the VM thread at this point");
3107
3108 if (!silent) { gclog_or_tty->print("Roots "); }
3109 VerifyRootsClosure rootsCl(vo);
3110 VerifyKlassClosure klassCl(this, &rootsCl);
3111 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3112
3113 // We apply the relevant closures to all the oops in the
3114 // system dictionary, class loader data graph, the string table
3115 // and the nmethods in the code cache.
3116 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3117 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3118
3119 {
3120 G1RootProcessor root_processor(this, 1);
3121 root_processor.process_all_roots(&rootsCl,
3122 &cldCl,
3123 &blobsCl);
3124 }
3125
3126 bool failures = rootsCl.failures() || codeRootsCl.failures();
3127
3128 if (vo != VerifyOption_G1UseMarkWord) {
3129 // If we're verifying during a full GC then the region sets
3130 // will have been torn down at the start of the GC. Therefore
3131 // verifying the region sets will fail. So we only verify
3132 // the region sets when not in a full GC.
3133 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3134 verify_region_sets();
3135 }
3136
3137 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3138 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3139
3140 G1ParVerifyTask task(this, vo);
3141 workers()->run_task(&task);
3142 if (task.failures()) {
3143 failures = true;
3144 }
3145
3146 } else {
3147 VerifyRegionClosure blk(false, vo);
3148 heap_region_iterate(&blk);
3149 if (blk.failures()) {
3150 failures = true;
3151 }
3152 }
3153
3154 if (G1StringDedup::is_enabled()) {
3155 if (!silent) gclog_or_tty->print("StrDedup ");
3156 G1StringDedup::verify();
3157 }
3158
3159 if (failures) {
3160 gclog_or_tty->print_cr("Heap:");
3161 // It helps to have the per-region information in the output to
3162 // help us track down what went wrong. This is why we call
3163 // print_extended_on() instead of print_on().
3164 print_extended_on(gclog_or_tty);
3165 gclog_or_tty->cr();
3166 gclog_or_tty->flush();
3167 }
3168 guarantee(!failures, "there should not have been any failures");
3169 } else {
3170 if (!silent) {
3171 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3172 if (G1StringDedup::is_enabled()) {
3173 gclog_or_tty->print(", StrDedup");
3174 }
3175 gclog_or_tty->print(") ");
3176 }
3177 }
3178 }
3179
3180 void G1CollectedHeap::verify(bool silent) {
3181 verify(silent, VerifyOption_G1UsePrevMarking);
3182 }
3183
3184 double G1CollectedHeap::verify(bool guard, const char* msg) {
3185 double verify_time_ms = 0.0;
3186
3187 if (guard && total_collections() >= VerifyGCStartAt) {
3188 double verify_start = os::elapsedTime();
3189 HandleMark hm; // Discard invalid handles created during verification
3190 prepare_for_verify();
3191 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3192 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3193 }
3194
3195 return verify_time_ms;
3196 }
3197
3198 void G1CollectedHeap::verify_before_gc() {
3199 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3200 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3201 }
3202
3203 void G1CollectedHeap::verify_after_gc() {
3204 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3205 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3206 }
3207
3208 class PrintRegionClosure: public HeapRegionClosure {
3209 outputStream* _st;
3210 public:
3211 PrintRegionClosure(outputStream* st) : _st(st) {}
3212 bool doHeapRegion(HeapRegion* r) {
3213 r->print_on(_st);
3214 return false;
3215 }
3216 };
3217
3218 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3219 const HeapRegion* hr,
3220 const VerifyOption vo) const {
3221 switch (vo) {
3222 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3223 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3224 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3225 default: ShouldNotReachHere();
3226 }
3227 return false; // keep some compilers happy
3228 }
3229
3230 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3231 const VerifyOption vo) const {
3232 switch (vo) {
3233 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3234 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3235 case VerifyOption_G1UseMarkWord: {
3236 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3237 return !obj->is_gc_marked() && !hr->is_archive();
3238 }
3239 default: ShouldNotReachHere();
3240 }
3241 return false; // keep some compilers happy
3242 }
3243
3244 void G1CollectedHeap::print_on(outputStream* st) const {
3245 st->print(" %-20s", "garbage-first heap");
3246 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3247 capacity()/K, used_unlocked()/K);
3248 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3249 p2i(_hrm.reserved().start()),
3250 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3251 p2i(_hrm.reserved().end()));
3252 st->cr();
3253 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3254 uint young_regions = _young_list->length();
3255 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3256 (size_t) young_regions * HeapRegion::GrainBytes / K);
3257 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3258 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3259 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3260 st->cr();
3261 MetaspaceAux::print_on(st);
3262 }
3263
3264 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3265 print_on(st);
3266
3267 // Print the per-region information.
3268 st->cr();
3269 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
3270 "HS=humongous(starts), HC=humongous(continues), "
3271 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3272 "AC=allocation context, "
3273 "TAMS=top-at-mark-start (previous, next)");
3274 PrintRegionClosure blk(st);
3275 heap_region_iterate(&blk);
3276 }
3277
3278 void G1CollectedHeap::print_on_error(outputStream* st) const {
3279 this->CollectedHeap::print_on_error(st);
3280
3281 if (_cm != NULL) {
3282 st->cr();
3283 _cm->print_on_error(st);
3284 }
3285 }
3286
3287 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3288 workers()->print_worker_threads_on(st);
3289 _cmThread->print_on(st);
3290 st->cr();
3291 _cm->print_worker_threads_on(st);
3292 _cg1r->print_worker_threads_on(st);
3293 if (G1StringDedup::is_enabled()) {
3294 G1StringDedup::print_worker_threads_on(st);
3295 }
3296 }
3297
3298 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3299 workers()->threads_do(tc);
3300 tc->do_thread(_cmThread);
3301 _cg1r->threads_do(tc);
3302 if (G1StringDedup::is_enabled()) {
3303 G1StringDedup::threads_do(tc);
3304 }
3305 }
3306
3307 void G1CollectedHeap::print_tracing_info() const {
3308 // We'll overload this to mean "trace GC pause statistics."
3309 if (TraceYoungGenTime || TraceOldGenTime) {
3310 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3311 // to that.
3312 g1_policy()->print_tracing_info();
3313 }
3314 if (G1SummarizeRSetStats) {
3315 g1_rem_set()->print_summary_info();
3316 }
3317 if (G1SummarizeConcMark) {
3318 concurrent_mark()->print_summary_info();
3319 }
3320 g1_policy()->print_yg_surv_rate_info();
3321 }
3322
3323 #ifndef PRODUCT
3324 // Helpful for debugging RSet issues.
3325
3326 class PrintRSetsClosure : public HeapRegionClosure {
3327 private:
3328 const char* _msg;
3329 size_t _occupied_sum;
3330
3331 public:
3332 bool doHeapRegion(HeapRegion* r) {
3333 HeapRegionRemSet* hrrs = r->rem_set();
3334 size_t occupied = hrrs->occupied();
3335 _occupied_sum += occupied;
3336
3337 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3338 HR_FORMAT_PARAMS(r));
3339 if (occupied == 0) {
3340 gclog_or_tty->print_cr(" RSet is empty");
3341 } else {
3342 hrrs->print();
3343 }
3344 gclog_or_tty->print_cr("----------");
3345 return false;
3346 }
3347
3348 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3349 gclog_or_tty->cr();
3350 gclog_or_tty->print_cr("========================================");
3351 gclog_or_tty->print_cr("%s", msg);
3352 gclog_or_tty->cr();
3353 }
3354
3355 ~PrintRSetsClosure() {
3356 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3357 gclog_or_tty->print_cr("========================================");
3358 gclog_or_tty->cr();
3359 }
3360 };
3361
3362 void G1CollectedHeap::print_cset_rsets() {
3363 PrintRSetsClosure cl("Printing CSet RSets");
3364 collection_set_iterate(&cl);
3365 }
3366
3367 void G1CollectedHeap::print_all_rsets() {
3368 PrintRSetsClosure cl("Printing All RSets");;
3369 heap_region_iterate(&cl);
3370 }
3371 #endif // PRODUCT
3372
3373 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3374 YoungList* young_list = heap()->young_list();
3375
3376 size_t eden_used_bytes = young_list->eden_used_bytes();
3377 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3378
3379 size_t eden_capacity_bytes =
3380 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3381
3382 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3383 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3384 }
3385
3386 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3387 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3388 stats->unused(), stats->used(), stats->region_end_waste(),
3389 stats->regions_filled(), stats->direct_allocated(),
3390 stats->failure_used(), stats->failure_waste());
3391 }
3392
3393 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3394 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3395 gc_tracer->report_gc_heap_summary(when, heap_summary);
3396
3397 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3398 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3399 }
3400
3401
3402 G1CollectedHeap* G1CollectedHeap::heap() {
3403 CollectedHeap* heap = Universe::heap();
3404 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3405 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3406 return (G1CollectedHeap*)heap;
3407 }
3408
3409 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3410 // always_do_update_barrier = false;
3411 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3412 // Fill TLAB's and such
3413 accumulate_statistics_all_tlabs();
3414 ensure_parsability(true);
3415
3416 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3417 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3418 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3419 }
3420 }
3421
3422 void G1CollectedHeap::gc_epilogue(bool full) {
3423
3424 if (G1SummarizeRSetStats &&
3425 (G1SummarizeRSetStatsPeriod > 0) &&
3426 // we are at the end of the GC. Total collections has already been increased.
3427 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3428 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3429 }
3430
3431 // FIXME: what is this about?
3432 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3433 // is set.
3434 #if defined(COMPILER2) || INCLUDE_JVMCI
3435 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3436 #endif
3437 // always_do_update_barrier = true;
3438
3439 resize_all_tlabs();
3440 allocation_context_stats().update(full);
3441
3442 // We have just completed a GC. Update the soft reference
3443 // policy with the new heap occupancy
3444 Universe::update_heap_info_at_gc();
3445 }
3446
3447 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3448 uint gc_count_before,
3449 bool* succeeded,
3450 GCCause::Cause gc_cause) {
3451 assert_heap_not_locked_and_not_at_safepoint();
3452 g1_policy()->record_stop_world_start();
3453 VM_G1IncCollectionPause op(gc_count_before,
3454 word_size,
3455 false, /* should_initiate_conc_mark */
3456 g1_policy()->max_pause_time_ms(),
3457 gc_cause);
3458
3459 op.set_allocation_context(AllocationContext::current());
3460 VMThread::execute(&op);
3461
3462 HeapWord* result = op.result();
3463 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3464 assert(result == NULL || ret_succeeded,
3465 "the result should be NULL if the VM did not succeed");
3466 *succeeded = ret_succeeded;
3467
3468 assert_heap_not_locked();
3469 return result;
3470 }
3471
3472 void
3473 G1CollectedHeap::doConcurrentMark() {
3474 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3475 if (!_cmThread->in_progress()) {
3476 _cmThread->set_started();
3477 CGC_lock->notify();
3478 }
3479 }
3480
3481 size_t G1CollectedHeap::pending_card_num() {
3482 size_t extra_cards = 0;
3483 JavaThread *curr = Threads::first();
3484 while (curr != NULL) {
3485 DirtyCardQueue& dcq = curr->dirty_card_queue();
3486 extra_cards += dcq.size();
3487 curr = curr->next();
3488 }
3489 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3490 size_t buffer_size = dcqs.buffer_size();
3491 size_t buffer_num = dcqs.completed_buffers_num();
3492
3493 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3494 // in bytes - not the number of 'entries'. We need to convert
3495 // into a number of cards.
3496 return (buffer_size * buffer_num + extra_cards) / oopSize;
3497 }
3498
3499 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3500 private:
3501 size_t _total_humongous;
3502 size_t _candidate_humongous;
3503
3504 DirtyCardQueue _dcq;
3505
3506 // We don't nominate objects with many remembered set entries, on
3507 // the assumption that such objects are likely still live.
3508 bool is_remset_small(HeapRegion* region) const {
3509 HeapRegionRemSet* const rset = region->rem_set();
3510 return G1EagerReclaimHumongousObjectsWithStaleRefs
3511 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3512 : rset->is_empty();
3513 }
3514
3515 bool is_typeArray_region(HeapRegion* region) const {
3516 return oop(region->bottom())->is_typeArray();
3517 }
3518
3519 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3520 assert(region->is_starts_humongous(), "Must start a humongous object");
3521
3522 // Candidate selection must satisfy the following constraints
3523 // while concurrent marking is in progress:
3524 //
3525 // * In order to maintain SATB invariants, an object must not be
3526 // reclaimed if it was allocated before the start of marking and
3527 // has not had its references scanned. Such an object must have
3528 // its references (including type metadata) scanned to ensure no
3529 // live objects are missed by the marking process. Objects
3530 // allocated after the start of concurrent marking don't need to
3531 // be scanned.
3532 //
3533 // * An object must not be reclaimed if it is on the concurrent
3534 // mark stack. Objects allocated after the start of concurrent
3535 // marking are never pushed on the mark stack.
3536 //
3537 // Nominating only objects allocated after the start of concurrent
3538 // marking is sufficient to meet both constraints. This may miss
3539 // some objects that satisfy the constraints, but the marking data
3540 // structures don't support efficiently performing the needed
3541 // additional tests or scrubbing of the mark stack.
3542 //
3543 // However, we presently only nominate is_typeArray() objects.
3544 // A humongous object containing references induces remembered
3545 // set entries on other regions. In order to reclaim such an
3546 // object, those remembered sets would need to be cleaned up.
3547 //
3548 // We also treat is_typeArray() objects specially, allowing them
3549 // to be reclaimed even if allocated before the start of
3550 // concurrent mark. For this we rely on mark stack insertion to
3551 // exclude is_typeArray() objects, preventing reclaiming an object
3552 // that is in the mark stack. We also rely on the metadata for
3553 // such objects to be built-in and so ensured to be kept live.
3554 // Frequent allocation and drop of large binary blobs is an
3555 // important use case for eager reclaim, and this special handling
3556 // may reduce needed headroom.
3557
3558 return is_typeArray_region(region) && is_remset_small(region);
3559 }
3560
3561 public:
3562 RegisterHumongousWithInCSetFastTestClosure()
3563 : _total_humongous(0),
3564 _candidate_humongous(0),
3565 _dcq(&JavaThread::dirty_card_queue_set()) {
3566 }
3567
3568 virtual bool doHeapRegion(HeapRegion* r) {
3569 if (!r->is_starts_humongous()) {
3570 return false;
3571 }
3572 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3573
3574 bool is_candidate = humongous_region_is_candidate(g1h, r);
3575 uint rindex = r->hrm_index();
3576 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3577 if (is_candidate) {
3578 _candidate_humongous++;
3579 g1h->register_humongous_region_with_cset(rindex);
3580 // Is_candidate already filters out humongous object with large remembered sets.
3581 // If we have a humongous object with a few remembered sets, we simply flush these
3582 // remembered set entries into the DCQS. That will result in automatic
3583 // re-evaluation of their remembered set entries during the following evacuation
3584 // phase.
3585 if (!r->rem_set()->is_empty()) {
3586 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3587 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3588 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3589 HeapRegionRemSetIterator hrrs(r->rem_set());
3590 size_t card_index;
3591 while (hrrs.has_next(card_index)) {
3592 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3593 // The remembered set might contain references to already freed
3594 // regions. Filter out such entries to avoid failing card table
3595 // verification.
3596 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3597 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3598 *card_ptr = CardTableModRefBS::dirty_card_val();
3599 _dcq.enqueue(card_ptr);
3600 }
3601 }
3602 }
3603 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3604 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3605 hrrs.n_yielded(), r->rem_set()->occupied());
3606 r->rem_set()->clear_locked();
3607 }
3608 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3609 }
3610 _total_humongous++;
3611
3612 return false;
3613 }
3614
3615 size_t total_humongous() const { return _total_humongous; }
3616 size_t candidate_humongous() const { return _candidate_humongous; }
3617
3618 void flush_rem_set_entries() { _dcq.flush(); }
3619 };
3620
3621 void G1CollectedHeap::register_humongous_regions_with_cset() {
3622 if (!G1EagerReclaimHumongousObjects) {
3623 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3624 return;
3625 }
3626 double time = os::elapsed_counter();
3627
3628 // Collect reclaim candidate information and register candidates with cset.
3629 RegisterHumongousWithInCSetFastTestClosure cl;
3630 heap_region_iterate(&cl);
3631
3632 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3633 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3634 cl.total_humongous(),
3635 cl.candidate_humongous());
3636 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3637
3638 // Finally flush all remembered set entries to re-check into the global DCQS.
3639 cl.flush_rem_set_entries();
3640 }
3641
3642 #ifdef ASSERT
3643 class VerifyCSetClosure: public HeapRegionClosure {
3644 public:
3645 bool doHeapRegion(HeapRegion* hr) {
3646 // Here we check that the CSet region's RSet is ready for parallel
3647 // iteration. The fields that we'll verify are only manipulated
3648 // when the region is part of a CSet and is collected. Afterwards,
3649 // we reset these fields when we clear the region's RSet (when the
3650 // region is freed) so they are ready when the region is
3651 // re-allocated. The only exception to this is if there's an
3652 // evacuation failure and instead of freeing the region we leave
3653 // it in the heap. In that case, we reset these fields during
3654 // evacuation failure handling.
3655 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3656
3657 // Here's a good place to add any other checks we'd like to
3658 // perform on CSet regions.
3659 return false;
3660 }
3661 };
3662 #endif // ASSERT
3663
3664 uint G1CollectedHeap::num_task_queues() const {
3665 return _task_queues->size();
3666 }
3667
3668 #if TASKQUEUE_STATS
3669 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3670 st->print_raw_cr("GC Task Stats");
3671 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3672 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3673 }
3674
3675 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3676 print_taskqueue_stats_hdr(st);
3677
3678 TaskQueueStats totals;
3679 const uint n = num_task_queues();
3680 for (uint i = 0; i < n; ++i) {
3681 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3682 totals += task_queue(i)->stats;
3683 }
3684 st->print_raw("tot "); totals.print(st); st->cr();
3685
3686 DEBUG_ONLY(totals.verify());
3687 }
3688
3689 void G1CollectedHeap::reset_taskqueue_stats() {
3690 const uint n = num_task_queues();
3691 for (uint i = 0; i < n; ++i) {
3692 task_queue(i)->stats.reset();
3693 }
3694 }
3695 #endif // TASKQUEUE_STATS
3696
3697 void G1CollectedHeap::log_gc_header() {
3698 if (!G1Log::fine()) {
3699 return;
3700 }
3701
3702 gclog_or_tty->gclog_stamp();
3703
3704 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3705 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3706 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3707
3708 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3709 }
3710
3711 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3712 if (!G1Log::fine()) {
3713 return;
3714 }
3715
3716 if (G1Log::finer()) {
3717 if (evacuation_failed()) {
3718 gclog_or_tty->print(" (to-space exhausted)");
3719 }
3720 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3721 g1_policy()->print_phases(pause_time_sec);
3722 g1_policy()->print_detailed_heap_transition();
3723 } else {
3724 if (evacuation_failed()) {
3725 gclog_or_tty->print("--");
3726 }
3727 g1_policy()->print_heap_transition();
3728 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3729 }
3730 gclog_or_tty->flush();
3731 }
3732
3733 void G1CollectedHeap::wait_for_root_region_scanning() {
3734 double scan_wait_start = os::elapsedTime();
3735 // We have to wait until the CM threads finish scanning the
3736 // root regions as it's the only way to ensure that all the
3737 // objects on them have been correctly scanned before we start
3738 // moving them during the GC.
3739 bool waited = _cm->root_regions()->wait_until_scan_finished();
3740 double wait_time_ms = 0.0;
3741 if (waited) {
3742 double scan_wait_end = os::elapsedTime();
3743 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3744 }
3745 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3746 }
3747
3748 bool
3749 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3750 assert_at_safepoint(true /* should_be_vm_thread */);
3751 guarantee(!is_gc_active(), "collection is not reentrant");
3752
3753 if (GC_locker::check_active_before_gc()) {
3754 return false;
3755 }
3756
3757 _gc_timer_stw->register_gc_start();
3758
3759 GCIdMark gc_id_mark;
3760 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3761
3762 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3763 ResourceMark rm;
3764
3765 wait_for_root_region_scanning();
3766
3767 G1Log::update_level();
3768 print_heap_before_gc();
3769 trace_heap_before_gc(_gc_tracer_stw);
3770
3771 verify_region_sets_optional();
3772 verify_dirty_young_regions();
3773
3774 // This call will decide whether this pause is an initial-mark
3775 // pause. If it is, during_initial_mark_pause() will return true
3776 // for the duration of this pause.
3777 g1_policy()->decide_on_conc_mark_initiation();
3778
3779 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3780 assert(!collector_state()->during_initial_mark_pause() ||
3781 collector_state()->gcs_are_young(), "sanity");
3782
3783 // We also do not allow mixed GCs during marking.
3784 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3785
3786 // Record whether this pause is an initial mark. When the current
3787 // thread has completed its logging output and it's safe to signal
3788 // the CM thread, the flag's value in the policy has been reset.
3789 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3790
3791 // Inner scope for scope based logging, timers, and stats collection
3792 {
3793 EvacuationInfo evacuation_info;
3794
3795 if (collector_state()->during_initial_mark_pause()) {
3796 // We are about to start a marking cycle, so we increment the
3797 // full collection counter.
3798 increment_old_marking_cycles_started();
3799 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3800 }
3801
3802 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3803
3804 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3805
3806 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3807 workers()->active_workers(),
3808 Threads::number_of_non_daemon_threads());
3809 workers()->set_active_workers(active_workers);
3810
3811 double pause_start_sec = os::elapsedTime();
3812 g1_policy()->note_gc_start(active_workers);
3813 log_gc_header();
3814
3815 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3816 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3817
3818 // If the secondary_free_list is not empty, append it to the
3819 // free_list. No need to wait for the cleanup operation to finish;
3820 // the region allocation code will check the secondary_free_list
3821 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3822 // set, skip this step so that the region allocation code has to
3823 // get entries from the secondary_free_list.
3824 if (!G1StressConcRegionFreeing) {
3825 append_secondary_free_list_if_not_empty_with_lock();
3826 }
3827
3828 assert(check_young_list_well_formed(), "young list should be well formed");
3829
3830 // Don't dynamically change the number of GC threads this early. A value of
3831 // 0 is used to indicate serial work. When parallel work is done,
3832 // it will be set.
3833
3834 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3835 IsGCActiveMark x;
3836
3837 gc_prologue(false);
3838 increment_total_collections(false /* full gc */);
3839 increment_gc_time_stamp();
3840
3841 verify_before_gc();
3842
3843 check_bitmaps("GC Start");
3844
3845 #if defined(COMPILER2) || INCLUDE_JVMCI
3846 DerivedPointerTable::clear();
3847 #endif
3848
3849 // Please see comment in g1CollectedHeap.hpp and
3850 // G1CollectedHeap::ref_processing_init() to see how
3851 // reference processing currently works in G1.
3852
3853 // Enable discovery in the STW reference processor
3854 if (g1_policy()->should_process_references()) {
3855 ref_processor_stw()->enable_discovery();
3856 } else {
3857 ref_processor_stw()->disable_discovery();
3858 }
3859
3860 {
3861 // We want to temporarily turn off discovery by the
3862 // CM ref processor, if necessary, and turn it back on
3863 // on again later if we do. Using a scoped
3864 // NoRefDiscovery object will do this.
3865 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3866
3867 // Forget the current alloc region (we might even choose it to be part
3868 // of the collection set!).
3869 _allocator->release_mutator_alloc_region();
3870
3871 // We should call this after we retire the mutator alloc
3872 // region(s) so that all the ALLOC / RETIRE events are generated
3873 // before the start GC event.
3874 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3875
3876 // This timing is only used by the ergonomics to handle our pause target.
3877 // It is unclear why this should not include the full pause. We will
3878 // investigate this in CR 7178365.
3879 //
3880 // Preserving the old comment here if that helps the investigation:
3881 //
3882 // The elapsed time induced by the start time below deliberately elides
3883 // the possible verification above.
3884 double sample_start_time_sec = os::elapsedTime();
3885
3886 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3887
3888 if (collector_state()->during_initial_mark_pause()) {
3889 concurrent_mark()->checkpointRootsInitialPre();
3890 }
3891
3892 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3893 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3894
3895 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3896
3897 // Make sure the remembered sets are up to date. This needs to be
3898 // done before register_humongous_regions_with_cset(), because the
3899 // remembered sets are used there to choose eager reclaim candidates.
3900 // If the remembered sets are not up to date we might miss some
3901 // entries that need to be handled.
3902 g1_rem_set()->cleanupHRRS();
3903
3904 register_humongous_regions_with_cset();
3905
3906 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3907
3908 _cm->note_start_of_gc();
3909 // We call this after finalize_cset() to
3910 // ensure that the CSet has been finalized.
3911 _cm->verify_no_cset_oops();
3912
3913 if (_hr_printer.is_active()) {
3914 HeapRegion* hr = g1_policy()->collection_set();
3915 while (hr != NULL) {
3916 _hr_printer.cset(hr);
3917 hr = hr->next_in_collection_set();
3918 }
3919 }
3920
3921 #ifdef ASSERT
3922 VerifyCSetClosure cl;
3923 collection_set_iterate(&cl);
3924 #endif // ASSERT
3925
3926 // Initialize the GC alloc regions.
3927 _allocator->init_gc_alloc_regions(evacuation_info);
3928
3929 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3930 pre_evacuate_collection_set();
3931
3932 // Actually do the work...
3933 evacuate_collection_set(evacuation_info, &per_thread_states);
3934
3935 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3936
3937 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3938 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3939
3940 eagerly_reclaim_humongous_regions();
3941
3942 g1_policy()->clear_collection_set();
3943
3944 // Start a new incremental collection set for the next pause.
3945 g1_policy()->start_incremental_cset_building();
3946
3947 clear_cset_fast_test();
3948
3949 _young_list->reset_sampled_info();
3950
3951 // Don't check the whole heap at this point as the
3952 // GC alloc regions from this pause have been tagged
3953 // as survivors and moved on to the survivor list.
3954 // Survivor regions will fail the !is_young() check.
3955 assert(check_young_list_empty(false /* check_heap */),
3956 "young list should be empty");
3957
3958 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3959 _young_list->first_survivor_region(),
3960 _young_list->last_survivor_region());
3961
3962 _young_list->reset_auxilary_lists();
3963
3964 if (evacuation_failed()) {
3965 set_used(recalculate_used());
3966 if (_archive_allocator != NULL) {
3967 _archive_allocator->clear_used();
3968 }
3969 for (uint i = 0; i < ParallelGCThreads; i++) {
3970 if (_evacuation_failed_info_array[i].has_failed()) {
3971 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3972 }
3973 }
3974 } else {
3975 // The "used" of the the collection set have already been subtracted
3976 // when they were freed. Add in the bytes evacuated.
3977 increase_used(g1_policy()->bytes_copied_during_gc());
3978 }
3979
3980 if (collector_state()->during_initial_mark_pause()) {
3981 // We have to do this before we notify the CM threads that
3982 // they can start working to make sure that all the
3983 // appropriate initialization is done on the CM object.
3984 concurrent_mark()->checkpointRootsInitialPost();
3985 collector_state()->set_mark_in_progress(true);
3986 // Note that we don't actually trigger the CM thread at
3987 // this point. We do that later when we're sure that
3988 // the current thread has completed its logging output.
3989 }
3990
3991 allocate_dummy_regions();
3992
3993 _allocator->init_mutator_alloc_region();
3994
3995 {
3996 size_t expand_bytes = g1_policy()->expansion_amount();
3997 if (expand_bytes > 0) {
3998 size_t bytes_before = capacity();
3999 // No need for an ergo verbose message here,
4000 // expansion_amount() does this when it returns a value > 0.
4001 double expand_ms;
4002 if (!expand(expand_bytes, &expand_ms)) {
4003 // We failed to expand the heap. Cannot do anything about it.
4004 }
4005 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
4006 }
4007 }
4008
4009 // We redo the verification but now wrt to the new CSet which
4010 // has just got initialized after the previous CSet was freed.
4011 _cm->verify_no_cset_oops();
4012 _cm->note_end_of_gc();
4013
4014 // This timing is only used by the ergonomics to handle our pause target.
4015 // It is unclear why this should not include the full pause. We will
4016 // investigate this in CR 7178365.
4017 double sample_end_time_sec = os::elapsedTime();
4018 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4019 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
4020 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
4021
4022 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4023 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4024
4025 MemoryService::track_memory_usage();
4026
4027 // In prepare_for_verify() below we'll need to scan the deferred
4028 // update buffers to bring the RSets up-to-date if
4029 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4030 // the update buffers we'll probably need to scan cards on the
4031 // regions we just allocated to (i.e., the GC alloc
4032 // regions). However, during the last GC we called
4033 // set_saved_mark() on all the GC alloc regions, so card
4034 // scanning might skip the [saved_mark_word()...top()] area of
4035 // those regions (i.e., the area we allocated objects into
4036 // during the last GC). But it shouldn't. Given that
4037 // saved_mark_word() is conditional on whether the GC time stamp
4038 // on the region is current or not, by incrementing the GC time
4039 // stamp here we invalidate all the GC time stamps on all the
4040 // regions and saved_mark_word() will simply return top() for
4041 // all the regions. This is a nicer way of ensuring this rather
4042 // than iterating over the regions and fixing them. In fact, the
4043 // GC time stamp increment here also ensures that
4044 // saved_mark_word() will return top() between pauses, i.e.,
4045 // during concurrent refinement. So we don't need the
4046 // is_gc_active() check to decided which top to use when
4047 // scanning cards (see CR 7039627).
4048 increment_gc_time_stamp();
4049
4050 verify_after_gc();
4051 check_bitmaps("GC End");
4052
4053 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4054 ref_processor_stw()->verify_no_references_recorded();
4055
4056 // CM reference discovery will be re-enabled if necessary.
4057 }
4058
4059 // We should do this after we potentially expand the heap so
4060 // that all the COMMIT events are generated before the end GC
4061 // event, and after we retire the GC alloc regions so that all
4062 // RETIRE events are generated before the end GC event.
4063 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4064
4065 #ifdef TRACESPINNING
4066 ParallelTaskTerminator::print_termination_counts();
4067 #endif
4068
4069 gc_epilogue(false);
4070 }
4071
4072 // Print the remainder of the GC log output.
4073 log_gc_footer(os::elapsedTime() - pause_start_sec);
4074
4075 // It is not yet to safe to tell the concurrent mark to
4076 // start as we have some optional output below. We don't want the
4077 // output from the concurrent mark thread interfering with this
4078 // logging output either.
4079
4080 _hrm.verify_optional();
4081 verify_region_sets_optional();
4082
4083 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4084 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4085
4086 print_heap_after_gc();
4087 trace_heap_after_gc(_gc_tracer_stw);
4088
4089 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4090 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4091 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4092 // before any GC notifications are raised.
4093 g1mm()->update_sizes();
4094
4095 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4096 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4097 _gc_timer_stw->register_gc_end();
4098 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4099 }
4100 // It should now be safe to tell the concurrent mark thread to start
4101 // without its logging output interfering with the logging output
4102 // that came from the pause.
4103
4104 if (should_start_conc_mark) {
4105 // CAUTION: after the doConcurrentMark() call below,
4106 // the concurrent marking thread(s) could be running
4107 // concurrently with us. Make sure that anything after
4108 // this point does not assume that we are the only GC thread
4109 // running. Note: of course, the actual marking work will
4110 // not start until the safepoint itself is released in
4111 // SuspendibleThreadSet::desynchronize().
4112 doConcurrentMark();
4113 }
4114
4115 return true;
4116 }
4117
4118 void G1CollectedHeap::restore_preserved_marks() {
4119 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
4120 workers()->run_task(&rpm_task);
4121 }
4122
4123 void G1CollectedHeap::remove_self_forwarding_pointers() {
4124 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4125 workers()->run_task(&rsfp_task);
4126 }
4127
4128 void G1CollectedHeap::restore_after_evac_failure() {
4129 double remove_self_forwards_start = os::elapsedTime();
4130
4131 remove_self_forwarding_pointers();
4132 restore_preserved_marks();
4133
4134 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4135 }
4136
4137 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4138 if (!_evacuation_failed) {
4139 _evacuation_failed = true;
4140 }
4141
4142 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4143
4144 // We want to call the "for_promotion_failure" version only in the
4145 // case of a promotion failure.
4146 if (m->must_be_preserved_for_promotion_failure(obj)) {
4147 OopAndMarkOop elem(obj, m);
4148 _preserved_objs[worker_id].push(elem);
4149 }
4150 }
4151
4152 bool G1ParEvacuateFollowersClosure::offer_termination() {
4153 G1ParScanThreadState* const pss = par_scan_state();
4154 start_term_time();
4155 const bool res = terminator()->offer_termination();
4156 end_term_time();
4157 return res;
4158 }
4159
4160 void G1ParEvacuateFollowersClosure::do_void() {
4161 G1ParScanThreadState* const pss = par_scan_state();
4162 pss->trim_queue();
4163 do {
4164 pss->steal_and_trim_queue(queues());
4165 } while (!offer_termination());
4166 }
4167
4168 class G1ParTask : public AbstractGangTask {
4169 protected:
4170 G1CollectedHeap* _g1h;
4171 G1ParScanThreadStateSet* _pss;
4172 RefToScanQueueSet* _queues;
4173 G1RootProcessor* _root_processor;
4174 ParallelTaskTerminator _terminator;
4175 uint _n_workers;
4176
4177 public:
4178 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4179 : AbstractGangTask("G1 collection"),
4180 _g1h(g1h),
4181 _pss(per_thread_states),
4182 _queues(task_queues),
4183 _root_processor(root_processor),
4184 _terminator(n_workers, _queues),
4185 _n_workers(n_workers)
4186 {}
4187
4188 void work(uint worker_id) {
4189 if (worker_id >= _n_workers) return; // no work needed this round
4190
4191 double start_sec = os::elapsedTime();
4192 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4193
4194 {
4195 ResourceMark rm;
4196 HandleMark hm;
4197
4198 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4199
4200 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4201 pss->set_ref_processor(rp);
4202
4203 double start_strong_roots_sec = os::elapsedTime();
4204
4205 _root_processor->evacuate_roots(pss->closures(), worker_id);
4206
4207 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4208
4209 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4210 // treating the nmethods visited to act as roots for concurrent marking.
4211 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4212 // objects copied by the current evacuation.
4213 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4214 pss->closures()->weak_codeblobs(),
4215 worker_id);
4216
4217 _pss->add_cards_scanned(worker_id, cards_scanned);
4218
4219 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4220
4221 double term_sec = 0.0;
4222 size_t evac_term_attempts = 0;
4223 {
4224 double start = os::elapsedTime();
4225 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4226 evac.do_void();
4227
4228 evac_term_attempts = evac.term_attempts();
4229 term_sec = evac.term_time();
4230 double elapsed_sec = os::elapsedTime() - start;
4231 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4232 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4233 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4234 }
4235
4236 assert(pss->queue_is_empty(), "should be empty");
4237
4238 if (PrintTerminationStats) {
4239 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4240 size_t lab_waste;
4241 size_t lab_undo_waste;
4242 pss->waste(lab_waste, lab_undo_waste);
4243 _g1h->print_termination_stats(gclog_or_tty,
4244 worker_id,
4245 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4246 strong_roots_sec * 1000.0, /* strong roots time */
4247 term_sec * 1000.0, /* evac term time */
4248 evac_term_attempts, /* evac term attempts */
4249 lab_waste, /* alloc buffer waste */
4250 lab_undo_waste /* undo waste */
4251 );
4252 }
4253
4254 // Close the inner scope so that the ResourceMark and HandleMark
4255 // destructors are executed here and are included as part of the
4256 // "GC Worker Time".
4257 }
4258 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4259 }
4260 };
4261
4262 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4263 st->print_raw_cr("GC Termination Stats");
4264 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4265 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4266 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4267 }
4268
4269 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4270 uint worker_id,
4271 double elapsed_ms,
4272 double strong_roots_ms,
4273 double term_ms,
4274 size_t term_attempts,
4275 size_t alloc_buffer_waste,
4276 size_t undo_waste) const {
4277 st->print_cr("%3d %9.2f %9.2f %6.2f "
4278 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4279 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4280 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4281 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4282 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4283 alloc_buffer_waste * HeapWordSize / K,
4284 undo_waste * HeapWordSize / K);
4285 }
4286
4287 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4288 private:
4289 BoolObjectClosure* _is_alive;
4290 int _initial_string_table_size;
4291 int _initial_symbol_table_size;
4292
4293 bool _process_strings;
4294 int _strings_processed;
4295 int _strings_removed;
4296
4297 bool _process_symbols;
4298 int _symbols_processed;
4299 int _symbols_removed;
4300
4301 public:
4302 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4303 AbstractGangTask("String/Symbol Unlinking"),
4304 _is_alive(is_alive),
4305 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4306 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4307
4308 _initial_string_table_size = StringTable::the_table()->table_size();
4309 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4310 if (process_strings) {
4311 StringTable::clear_parallel_claimed_index();
4312 }
4313 if (process_symbols) {
4314 SymbolTable::clear_parallel_claimed_index();
4315 }
4316 }
4317
4318 ~G1StringSymbolTableUnlinkTask() {
4319 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4320 "claim value %d after unlink less than initial string table size %d",
4321 StringTable::parallel_claimed_index(), _initial_string_table_size);
4322 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4323 "claim value %d after unlink less than initial symbol table size %d",
4324 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4325
4326 if (G1TraceStringSymbolTableScrubbing) {
4327 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4328 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4329 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4330 strings_processed(), strings_removed(),
4331 symbols_processed(), symbols_removed());
4332 }
4333 }
4334
4335 void work(uint worker_id) {
4336 int strings_processed = 0;
4337 int strings_removed = 0;
4338 int symbols_processed = 0;
4339 int symbols_removed = 0;
4340 if (_process_strings) {
4341 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4342 Atomic::add(strings_processed, &_strings_processed);
4343 Atomic::add(strings_removed, &_strings_removed);
4344 }
4345 if (_process_symbols) {
4346 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4347 Atomic::add(symbols_processed, &_symbols_processed);
4348 Atomic::add(symbols_removed, &_symbols_removed);
4349 }
4350 }
4351
4352 size_t strings_processed() const { return (size_t)_strings_processed; }
4353 size_t strings_removed() const { return (size_t)_strings_removed; }
4354
4355 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4356 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4357 };
4358
4359 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4360 private:
4361 static Monitor* _lock;
4362
4363 BoolObjectClosure* const _is_alive;
4364 const bool _unloading_occurred;
4365 const uint _num_workers;
4366
4367 // Variables used to claim nmethods.
4368 nmethod* _first_nmethod;
4369 volatile nmethod* _claimed_nmethod;
4370
4371 // The list of nmethods that need to be processed by the second pass.
4372 volatile nmethod* _postponed_list;
4373 volatile uint _num_entered_barrier;
4374
4375 public:
4376 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4377 _is_alive(is_alive),
4378 _unloading_occurred(unloading_occurred),
4379 _num_workers(num_workers),
4380 _first_nmethod(NULL),
4381 _claimed_nmethod(NULL),
4382 _postponed_list(NULL),
4383 _num_entered_barrier(0)
4384 {
4385 nmethod::increase_unloading_clock();
4386 // Get first alive nmethod
4387 NMethodIterator iter = NMethodIterator();
4388 if(iter.next_alive()) {
4389 _first_nmethod = iter.method();
4390 }
4391 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4392 }
4393
4394 ~G1CodeCacheUnloadingTask() {
4395 CodeCache::verify_clean_inline_caches();
4396
4397 CodeCache::set_needs_cache_clean(false);
4398 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4399
4400 CodeCache::verify_icholder_relocations();
4401 }
4402
4403 private:
4404 void add_to_postponed_list(nmethod* nm) {
4405 nmethod* old;
4406 do {
4407 old = (nmethod*)_postponed_list;
4408 nm->set_unloading_next(old);
4409 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4410 }
4411
4412 void clean_nmethod(nmethod* nm) {
4413 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4414
4415 if (postponed) {
4416 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4417 add_to_postponed_list(nm);
4418 }
4419
4420 // Mark that this thread has been cleaned/unloaded.
4421 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4422 nm->set_unloading_clock(nmethod::global_unloading_clock());
4423 }
4424
4425 void clean_nmethod_postponed(nmethod* nm) {
4426 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4427 }
4428
4429 static const int MaxClaimNmethods = 16;
4430
4431 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4432 nmethod* first;
4433 NMethodIterator last;
4434
4435 do {
4436 *num_claimed_nmethods = 0;
4437
4438 first = (nmethod*)_claimed_nmethod;
4439 last = NMethodIterator(first);
4440
4441 if (first != NULL) {
4442
4443 for (int i = 0; i < MaxClaimNmethods; i++) {
4444 if (!last.next_alive()) {
4445 break;
4446 }
4447 claimed_nmethods[i] = last.method();
4448 (*num_claimed_nmethods)++;
4449 }
4450 }
4451
4452 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4453 }
4454
4455 nmethod* claim_postponed_nmethod() {
4456 nmethod* claim;
4457 nmethod* next;
4458
4459 do {
4460 claim = (nmethod*)_postponed_list;
4461 if (claim == NULL) {
4462 return NULL;
4463 }
4464
4465 next = claim->unloading_next();
4466
4467 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4468
4469 return claim;
4470 }
4471
4472 public:
4473 // Mark that we're done with the first pass of nmethod cleaning.
4474 void barrier_mark(uint worker_id) {
4475 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4476 _num_entered_barrier++;
4477 if (_num_entered_barrier == _num_workers) {
4478 ml.notify_all();
4479 }
4480 }
4481
4482 // See if we have to wait for the other workers to
4483 // finish their first-pass nmethod cleaning work.
4484 void barrier_wait(uint worker_id) {
4485 if (_num_entered_barrier < _num_workers) {
4486 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4487 while (_num_entered_barrier < _num_workers) {
4488 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4489 }
4490 }
4491 }
4492
4493 // Cleaning and unloading of nmethods. Some work has to be postponed
4494 // to the second pass, when we know which nmethods survive.
4495 void work_first_pass(uint worker_id) {
4496 // The first nmethods is claimed by the first worker.
4497 if (worker_id == 0 && _first_nmethod != NULL) {
4498 clean_nmethod(_first_nmethod);
4499 _first_nmethod = NULL;
4500 }
4501
4502 int num_claimed_nmethods;
4503 nmethod* claimed_nmethods[MaxClaimNmethods];
4504
4505 while (true) {
4506 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4507
4508 if (num_claimed_nmethods == 0) {
4509 break;
4510 }
4511
4512 for (int i = 0; i < num_claimed_nmethods; i++) {
4513 clean_nmethod(claimed_nmethods[i]);
4514 }
4515 }
4516 }
4517
4518 void work_second_pass(uint worker_id) {
4519 nmethod* nm;
4520 // Take care of postponed nmethods.
4521 while ((nm = claim_postponed_nmethod()) != NULL) {
4522 clean_nmethod_postponed(nm);
4523 }
4524 }
4525 };
4526
4527 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4528
4529 class G1KlassCleaningTask : public StackObj {
4530 BoolObjectClosure* _is_alive;
4531 volatile jint _clean_klass_tree_claimed;
4532 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4533
4534 public:
4535 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4536 _is_alive(is_alive),
4537 _clean_klass_tree_claimed(0),
4538 _klass_iterator() {
4539 }
4540
4541 private:
4542 bool claim_clean_klass_tree_task() {
4543 if (_clean_klass_tree_claimed) {
4544 return false;
4545 }
4546
4547 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4548 }
4549
4550 InstanceKlass* claim_next_klass() {
4551 Klass* klass;
4552 do {
4553 klass =_klass_iterator.next_klass();
4554 } while (klass != NULL && !klass->is_instance_klass());
4555
4556 // this can be null so don't call InstanceKlass::cast
4557 return static_cast<InstanceKlass*>(klass);
4558 }
4559
4560 public:
4561
4562 void clean_klass(InstanceKlass* ik) {
4563 ik->clean_weak_instanceklass_links(_is_alive);
4564 }
4565
4566 void work() {
4567 ResourceMark rm;
4568
4569 // One worker will clean the subklass/sibling klass tree.
4570 if (claim_clean_klass_tree_task()) {
4571 Klass::clean_subklass_tree(_is_alive);
4572 }
4573
4574 // All workers will help cleaning the classes,
4575 InstanceKlass* klass;
4576 while ((klass = claim_next_klass()) != NULL) {
4577 clean_klass(klass);
4578 }
4579 }
4580 };
4581
4582 // To minimize the remark pause times, the tasks below are done in parallel.
4583 class G1ParallelCleaningTask : public AbstractGangTask {
4584 private:
4585 G1StringSymbolTableUnlinkTask _string_symbol_task;
4586 G1CodeCacheUnloadingTask _code_cache_task;
4587 G1KlassCleaningTask _klass_cleaning_task;
4588
4589 public:
4590 // The constructor is run in the VMThread.
4591 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4592 AbstractGangTask("Parallel Cleaning"),
4593 _string_symbol_task(is_alive, process_strings, process_symbols),
4594 _code_cache_task(num_workers, is_alive, unloading_occurred),
4595 _klass_cleaning_task(is_alive) {
4596 }
4597
4598 // The parallel work done by all worker threads.
4599 void work(uint worker_id) {
4600 // Do first pass of code cache cleaning.
4601 _code_cache_task.work_first_pass(worker_id);
4602
4603 // Let the threads mark that the first pass is done.
4604 _code_cache_task.barrier_mark(worker_id);
4605
4606 // Clean the Strings and Symbols.
4607 _string_symbol_task.work(worker_id);
4608
4609 // Wait for all workers to finish the first code cache cleaning pass.
4610 _code_cache_task.barrier_wait(worker_id);
4611
4612 // Do the second code cache cleaning work, which realize on
4613 // the liveness information gathered during the first pass.
4614 _code_cache_task.work_second_pass(worker_id);
4615
4616 // Clean all klasses that were not unloaded.
4617 _klass_cleaning_task.work();
4618 }
4619 };
4620
4621
4622 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4623 bool process_strings,
4624 bool process_symbols,
4625 bool class_unloading_occurred) {
4626 uint n_workers = workers()->active_workers();
4627
4628 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4629 n_workers, class_unloading_occurred);
4630 workers()->run_task(&g1_unlink_task);
4631 }
4632
4633 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4634 bool process_strings, bool process_symbols) {
4635 {
4636 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4637 workers()->run_task(&g1_unlink_task);
4638 }
4639
4640 if (G1StringDedup::is_enabled()) {
4641 G1StringDedup::unlink(is_alive);
4642 }
4643 }
4644
4645 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4646 private:
4647 DirtyCardQueueSet* _queue;
4648 G1CollectedHeap* _g1h;
4649 public:
4650 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4651 _queue(queue), _g1h(g1h) { }
4652
4653 virtual void work(uint worker_id) {
4654 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4655 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4656
4657 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4658 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4659
4660 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4661 }
4662 };
4663
4664 void G1CollectedHeap::redirty_logged_cards() {
4665 double redirty_logged_cards_start = os::elapsedTime();
4666
4667 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4668 dirty_card_queue_set().reset_for_par_iteration();
4669 workers()->run_task(&redirty_task);
4670
4671 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4672 dcq.merge_bufferlists(&dirty_card_queue_set());
4673 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4674
4675 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4676 }
4677
4678 // Weak Reference Processing support
4679
4680 // An always "is_alive" closure that is used to preserve referents.
4681 // If the object is non-null then it's alive. Used in the preservation
4682 // of referent objects that are pointed to by reference objects
4683 // discovered by the CM ref processor.
4684 class G1AlwaysAliveClosure: public BoolObjectClosure {
4685 G1CollectedHeap* _g1;
4686 public:
4687 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4688 bool do_object_b(oop p) {
4689 if (p != NULL) {
4690 return true;
4691 }
4692 return false;
4693 }
4694 };
4695
4696 bool G1STWIsAliveClosure::do_object_b(oop p) {
4697 // An object is reachable if it is outside the collection set,
4698 // or is inside and copied.
4699 return !_g1->is_in_cset(p) || p->is_forwarded();
4700 }
4701
4702 // Non Copying Keep Alive closure
4703 class G1KeepAliveClosure: public OopClosure {
4704 G1CollectedHeap* _g1;
4705 public:
4706 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4707 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4708 void do_oop(oop* p) {
4709 oop obj = *p;
4710 assert(obj != NULL, "the caller should have filtered out NULL values");
4711
4712 const InCSetState cset_state = _g1->in_cset_state(obj);
4713 if (!cset_state.is_in_cset_or_humongous()) {
4714 return;
4715 }
4716 if (cset_state.is_in_cset()) {
4717 assert( obj->is_forwarded(), "invariant" );
4718 *p = obj->forwardee();
4719 } else {
4720 assert(!obj->is_forwarded(), "invariant" );
4721 assert(cset_state.is_humongous(),
4722 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4723 _g1->set_humongous_is_live(obj);
4724 }
4725 }
4726 };
4727
4728 // Copying Keep Alive closure - can be called from both
4729 // serial and parallel code as long as different worker
4730 // threads utilize different G1ParScanThreadState instances
4731 // and different queues.
4732
4733 class G1CopyingKeepAliveClosure: public OopClosure {
4734 G1CollectedHeap* _g1h;
4735 OopClosure* _copy_non_heap_obj_cl;
4736 G1ParScanThreadState* _par_scan_state;
4737
4738 public:
4739 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4740 OopClosure* non_heap_obj_cl,
4741 G1ParScanThreadState* pss):
4742 _g1h(g1h),
4743 _copy_non_heap_obj_cl(non_heap_obj_cl),
4744 _par_scan_state(pss)
4745 {}
4746
4747 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4748 virtual void do_oop( oop* p) { do_oop_work(p); }
4749
4750 template <class T> void do_oop_work(T* p) {
4751 oop obj = oopDesc::load_decode_heap_oop(p);
4752
4753 if (_g1h->is_in_cset_or_humongous(obj)) {
4754 // If the referent object has been forwarded (either copied
4755 // to a new location or to itself in the event of an
4756 // evacuation failure) then we need to update the reference
4757 // field and, if both reference and referent are in the G1
4758 // heap, update the RSet for the referent.
4759 //
4760 // If the referent has not been forwarded then we have to keep
4761 // it alive by policy. Therefore we have copy the referent.
4762 //
4763 // If the reference field is in the G1 heap then we can push
4764 // on the PSS queue. When the queue is drained (after each
4765 // phase of reference processing) the object and it's followers
4766 // will be copied, the reference field set to point to the
4767 // new location, and the RSet updated. Otherwise we need to
4768 // use the the non-heap or metadata closures directly to copy
4769 // the referent object and update the pointer, while avoiding
4770 // updating the RSet.
4771
4772 if (_g1h->is_in_g1_reserved(p)) {
4773 _par_scan_state->push_on_queue(p);
4774 } else {
4775 assert(!Metaspace::contains((const void*)p),
4776 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4777 _copy_non_heap_obj_cl->do_oop(p);
4778 }
4779 }
4780 }
4781 };
4782
4783 // Serial drain queue closure. Called as the 'complete_gc'
4784 // closure for each discovered list in some of the
4785 // reference processing phases.
4786
4787 class G1STWDrainQueueClosure: public VoidClosure {
4788 protected:
4789 G1CollectedHeap* _g1h;
4790 G1ParScanThreadState* _par_scan_state;
4791
4792 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4793
4794 public:
4795 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4796 _g1h(g1h),
4797 _par_scan_state(pss)
4798 { }
4799
4800 void do_void() {
4801 G1ParScanThreadState* const pss = par_scan_state();
4802 pss->trim_queue();
4803 }
4804 };
4805
4806 // Parallel Reference Processing closures
4807
4808 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4809 // processing during G1 evacuation pauses.
4810
4811 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4812 private:
4813 G1CollectedHeap* _g1h;
4814 G1ParScanThreadStateSet* _pss;
4815 RefToScanQueueSet* _queues;
4816 WorkGang* _workers;
4817 uint _active_workers;
4818
4819 public:
4820 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4821 G1ParScanThreadStateSet* per_thread_states,
4822 WorkGang* workers,
4823 RefToScanQueueSet *task_queues,
4824 uint n_workers) :
4825 _g1h(g1h),
4826 _pss(per_thread_states),
4827 _queues(task_queues),
4828 _workers(workers),
4829 _active_workers(n_workers)
4830 {
4831 assert(n_workers > 0, "shouldn't call this otherwise");
4832 }
4833
4834 // Executes the given task using concurrent marking worker threads.
4835 virtual void execute(ProcessTask& task);
4836 virtual void execute(EnqueueTask& task);
4837 };
4838
4839 // Gang task for possibly parallel reference processing
4840
4841 class G1STWRefProcTaskProxy: public AbstractGangTask {
4842 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4843 ProcessTask& _proc_task;
4844 G1CollectedHeap* _g1h;
4845 G1ParScanThreadStateSet* _pss;
4846 RefToScanQueueSet* _task_queues;
4847 ParallelTaskTerminator* _terminator;
4848
4849 public:
4850 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4851 G1CollectedHeap* g1h,
4852 G1ParScanThreadStateSet* per_thread_states,
4853 RefToScanQueueSet *task_queues,
4854 ParallelTaskTerminator* terminator) :
4855 AbstractGangTask("Process reference objects in parallel"),
4856 _proc_task(proc_task),
4857 _g1h(g1h),
4858 _pss(per_thread_states),
4859 _task_queues(task_queues),
4860 _terminator(terminator)
4861 {}
4862
4863 virtual void work(uint worker_id) {
4864 // The reference processing task executed by a single worker.
4865 ResourceMark rm;
4866 HandleMark hm;
4867
4868 G1STWIsAliveClosure is_alive(_g1h);
4869
4870 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4871 pss->set_ref_processor(NULL);
4872
4873 // Keep alive closure.
4874 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4875
4876 // Complete GC closure
4877 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4878
4879 // Call the reference processing task's work routine.
4880 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4881
4882 // Note we cannot assert that the refs array is empty here as not all
4883 // of the processing tasks (specifically phase2 - pp2_work) execute
4884 // the complete_gc closure (which ordinarily would drain the queue) so
4885 // the queue may not be empty.
4886 }
4887 };
4888
4889 // Driver routine for parallel reference processing.
4890 // Creates an instance of the ref processing gang
4891 // task and has the worker threads execute it.
4892 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4893 assert(_workers != NULL, "Need parallel worker threads.");
4894
4895 ParallelTaskTerminator terminator(_active_workers, _queues);
4896 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4897
4898 _workers->run_task(&proc_task_proxy);
4899 }
4900
4901 // Gang task for parallel reference enqueueing.
4902
4903 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4904 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4905 EnqueueTask& _enq_task;
4906
4907 public:
4908 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4909 AbstractGangTask("Enqueue reference objects in parallel"),
4910 _enq_task(enq_task)
4911 { }
4912
4913 virtual void work(uint worker_id) {
4914 _enq_task.work(worker_id);
4915 }
4916 };
4917
4918 // Driver routine for parallel reference enqueueing.
4919 // Creates an instance of the ref enqueueing gang
4920 // task and has the worker threads execute it.
4921
4922 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4923 assert(_workers != NULL, "Need parallel worker threads.");
4924
4925 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4926
4927 _workers->run_task(&enq_task_proxy);
4928 }
4929
4930 // End of weak reference support closures
4931
4932 // Abstract task used to preserve (i.e. copy) any referent objects
4933 // that are in the collection set and are pointed to by reference
4934 // objects discovered by the CM ref processor.
4935
4936 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4937 protected:
4938 G1CollectedHeap* _g1h;
4939 G1ParScanThreadStateSet* _pss;
4940 RefToScanQueueSet* _queues;
4941 ParallelTaskTerminator _terminator;
4942 uint _n_workers;
4943
4944 public:
4945 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4946 AbstractGangTask("ParPreserveCMReferents"),
4947 _g1h(g1h),
4948 _pss(per_thread_states),
4949 _queues(task_queues),
4950 _terminator(workers, _queues),
4951 _n_workers(workers)
4952 { }
4953
4954 void work(uint worker_id) {
4955 ResourceMark rm;
4956 HandleMark hm;
4957
4958 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4959 pss->set_ref_processor(NULL);
4960 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4961
4962 // Is alive closure
4963 G1AlwaysAliveClosure always_alive(_g1h);
4964
4965 // Copying keep alive closure. Applied to referent objects that need
4966 // to be copied.
4967 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4968
4969 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4970
4971 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4972 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4973
4974 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4975 // So this must be true - but assert just in case someone decides to
4976 // change the worker ids.
4977 assert(worker_id < limit, "sanity");
4978 assert(!rp->discovery_is_atomic(), "check this code");
4979
4980 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4981 for (uint idx = worker_id; idx < limit; idx += stride) {
4982 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4983
4984 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4985 while (iter.has_next()) {
4986 // Since discovery is not atomic for the CM ref processor, we
4987 // can see some null referent objects.
4988 iter.load_ptrs(DEBUG_ONLY(true));
4989 oop ref = iter.obj();
4990
4991 // This will filter nulls.
4992 if (iter.is_referent_alive()) {
4993 iter.make_referent_alive();
4994 }
4995 iter.move_to_next();
4996 }
4997 }
4998
4999 // Drain the queue - which may cause stealing
5000 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5001 drain_queue.do_void();
5002 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5003 assert(pss->queue_is_empty(), "should be");
5004 }
5005 };
5006
5007 void G1CollectedHeap::process_weak_jni_handles() {
5008 double ref_proc_start = os::elapsedTime();
5009
5010 G1STWIsAliveClosure is_alive(this);
5011 G1KeepAliveClosure keep_alive(this);
5012 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5013
5014 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5015 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5016 }
5017
5018 // Weak Reference processing during an evacuation pause (part 1).
5019 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5020 double ref_proc_start = os::elapsedTime();
5021
5022 ReferenceProcessor* rp = _ref_processor_stw;
5023 assert(rp->discovery_enabled(), "should have been enabled");
5024
5025 // Any reference objects, in the collection set, that were 'discovered'
5026 // by the CM ref processor should have already been copied (either by
5027 // applying the external root copy closure to the discovered lists, or
5028 // by following an RSet entry).
5029 //
5030 // But some of the referents, that are in the collection set, that these
5031 // reference objects point to may not have been copied: the STW ref
5032 // processor would have seen that the reference object had already
5033 // been 'discovered' and would have skipped discovering the reference,
5034 // but would not have treated the reference object as a regular oop.
5035 // As a result the copy closure would not have been applied to the
5036 // referent object.
5037 //
5038 // We need to explicitly copy these referent objects - the references
5039 // will be processed at the end of remarking.
5040 //
5041 // We also need to do this copying before we process the reference
5042 // objects discovered by the STW ref processor in case one of these
5043 // referents points to another object which is also referenced by an
5044 // object discovered by the STW ref processor.
5045
5046 uint no_of_gc_workers = workers()->active_workers();
5047
5048 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5049 per_thread_states,
5050 no_of_gc_workers,
5051 _task_queues);
5052
5053 workers()->run_task(&keep_cm_referents);
5054
5055 // Closure to test whether a referent is alive.
5056 G1STWIsAliveClosure is_alive(this);
5057
5058 // Even when parallel reference processing is enabled, the processing
5059 // of JNI refs is serial and performed serially by the current thread
5060 // rather than by a worker. The following PSS will be used for processing
5061 // JNI refs.
5062
5063 // Use only a single queue for this PSS.
5064 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5065 pss->set_ref_processor(NULL);
5066 assert(pss->queue_is_empty(), "pre-condition");
5067
5068 // Keep alive closure.
5069 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5070
5071 // Serial Complete GC closure
5072 G1STWDrainQueueClosure drain_queue(this, pss);
5073
5074 // Setup the soft refs policy...
5075 rp->setup_policy(false);
5076
5077 ReferenceProcessorStats stats;
5078 if (!rp->processing_is_mt()) {
5079 // Serial reference processing...
5080 stats = rp->process_discovered_references(&is_alive,
5081 &keep_alive,
5082 &drain_queue,
5083 NULL,
5084 _gc_timer_stw);
5085 } else {
5086 // Parallel reference processing
5087 assert(rp->num_q() == no_of_gc_workers, "sanity");
5088 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5089
5090 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5091 stats = rp->process_discovered_references(&is_alive,
5092 &keep_alive,
5093 &drain_queue,
5094 &par_task_executor,
5095 _gc_timer_stw);
5096 }
5097
5098 _gc_tracer_stw->report_gc_reference_stats(stats);
5099
5100 // We have completed copying any necessary live referent objects.
5101 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5102
5103 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5104 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5105 }
5106
5107 // Weak Reference processing during an evacuation pause (part 2).
5108 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5109 double ref_enq_start = os::elapsedTime();
5110
5111 ReferenceProcessor* rp = _ref_processor_stw;
5112 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5113
5114 // Now enqueue any remaining on the discovered lists on to
5115 // the pending list.
5116 if (!rp->processing_is_mt()) {
5117 // Serial reference processing...
5118 rp->enqueue_discovered_references();
5119 } else {
5120 // Parallel reference enqueueing
5121
5122 uint n_workers = workers()->active_workers();
5123
5124 assert(rp->num_q() == n_workers, "sanity");
5125 assert(n_workers <= rp->max_num_q(), "sanity");
5126
5127 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5128 rp->enqueue_discovered_references(&par_task_executor);
5129 }
5130
5131 rp->verify_no_references_recorded();
5132 assert(!rp->discovery_enabled(), "should have been disabled");
5133
5134 // FIXME
5135 // CM's reference processing also cleans up the string and symbol tables.
5136 // Should we do that here also? We could, but it is a serial operation
5137 // and could significantly increase the pause time.
5138
5139 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5140 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5141 }
5142
5143 void G1CollectedHeap::pre_evacuate_collection_set() {
5144 _expand_heap_after_alloc_failure = true;
5145 _evacuation_failed = false;
5146
5147 // Disable the hot card cache.
5148 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5149 hot_card_cache->reset_hot_cache_claimed_index();
5150 hot_card_cache->set_use_cache(false);
5151
5152 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5153 }
5154
5155 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5156 // Should G1EvacuationFailureALot be in effect for this GC?
5157 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5158
5159 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5160 double start_par_time_sec = os::elapsedTime();
5161 double end_par_time_sec;
5162
5163 {
5164 const uint n_workers = workers()->active_workers();
5165 G1RootProcessor root_processor(this, n_workers);
5166 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5167 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5168 if (collector_state()->during_initial_mark_pause()) {
5169 ClassLoaderDataGraph::clear_claimed_marks();
5170 }
5171
5172 // The individual threads will set their evac-failure closures.
5173 if (PrintTerminationStats) {
5174 print_termination_stats_hdr(gclog_or_tty);
5175 }
5176
5177 workers()->run_task(&g1_par_task);
5178 end_par_time_sec = os::elapsedTime();
5179
5180 // Closing the inner scope will execute the destructor
5181 // for the G1RootProcessor object. We record the current
5182 // elapsed time before closing the scope so that time
5183 // taken for the destructor is NOT included in the
5184 // reported parallel time.
5185 }
5186
5187 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5188
5189 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5190 phase_times->record_par_time(par_time_ms);
5191
5192 double code_root_fixup_time_ms =
5193 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5194 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5195 }
5196
5197 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5198 // Process any discovered reference objects - we have
5199 // to do this _before_ we retire the GC alloc regions
5200 // as we may have to copy some 'reachable' referent
5201 // objects (and their reachable sub-graphs) that were
5202 // not copied during the pause.
5203 if (g1_policy()->should_process_references()) {
5204 process_discovered_references(per_thread_states);
5205 } else {
5206 ref_processor_stw()->verify_no_references_recorded();
5207 process_weak_jni_handles();
5208 }
5209
5210 if (G1StringDedup::is_enabled()) {
5211 double fixup_start = os::elapsedTime();
5212
5213 G1STWIsAliveClosure is_alive(this);
5214 G1KeepAliveClosure keep_alive(this);
5215 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
5216
5217 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5218 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
5219 }
5220
5221 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5222
5223 if (evacuation_failed()) {
5224 restore_after_evac_failure();
5225
5226 // Reset the G1EvacuationFailureALot counters and flags
5227 // Note: the values are reset only when an actual
5228 // evacuation failure occurs.
5229 NOT_PRODUCT(reset_evacuation_should_fail();)
5230 }
5231
5232 // Enqueue any remaining references remaining on the STW
5233 // reference processor's discovered lists. We need to do
5234 // this after the card table is cleaned (and verified) as
5235 // the act of enqueueing entries on to the pending list
5236 // will log these updates (and dirty their associated
5237 // cards). We need these updates logged to update any
5238 // RSets.
5239 if (g1_policy()->should_process_references()) {
5240 enqueue_discovered_references(per_thread_states);
5241 } else {
5242 g1_policy()->phase_times()->record_ref_enq_time(0);
5243 }
5244
5245 _allocator->release_gc_alloc_regions(evacuation_info);
5246
5247 per_thread_states->flush();
5248
5249 record_obj_copy_mem_stats();
5250
5251 _survivor_evac_stats.adjust_desired_plab_sz();
5252 _old_evac_stats.adjust_desired_plab_sz();
5253
5254 // Reset and re-enable the hot card cache.
5255 // Note the counts for the cards in the regions in the
5256 // collection set are reset when the collection set is freed.
5257 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5258 hot_card_cache->reset_hot_cache();
5259 hot_card_cache->set_use_cache(true);
5260
5261 purge_code_root_memory();
5262
5263 redirty_logged_cards();
5264 #if defined(COMPILER2) || INCLUDE_JVMCI
5265 DerivedPointerTable::update_pointers();
5266 #endif
5267 }
5268
5269 void G1CollectedHeap::record_obj_copy_mem_stats() {
5270 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
5271
5272 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5273 create_g1_evac_summary(&_old_evac_stats));
5274 }
5275
5276 void G1CollectedHeap::free_region(HeapRegion* hr,
5277 FreeRegionList* free_list,
5278 bool par,
5279 bool locked) {
5280 assert(!hr->is_free(), "the region should not be free");
5281 assert(!hr->is_empty(), "the region should not be empty");
5282 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5283 assert(free_list != NULL, "pre-condition");
5284
5285 if (G1VerifyBitmaps) {
5286 MemRegion mr(hr->bottom(), hr->end());
5287 concurrent_mark()->clearRangePrevBitmap(mr);
5288 }
5289
5290 // Clear the card counts for this region.
5291 // Note: we only need to do this if the region is not young
5292 // (since we don't refine cards in young regions).
5293 if (!hr->is_young()) {
5294 _cg1r->hot_card_cache()->reset_card_counts(hr);
5295 }
5296 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5297 free_list->add_ordered(hr);
5298 }
5299
5300 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5301 FreeRegionList* free_list,
5302 bool par) {
5303 assert(hr->is_humongous(), "this is only for humongous regions");
5304 assert(free_list != NULL, "pre-condition");
5305 hr->clear_humongous();
5306 free_region(hr, free_list, par);
5307 }
5308
5309 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
5310 const uint humongous_regions_removed) {
5311 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
5312 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5313 _old_set.bulk_remove(old_regions_removed);
5314 _humongous_set.bulk_remove(humongous_regions_removed);
5315 }
5316
5317 }
5318
5319 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5320 assert(list != NULL, "list can't be null");
5321 if (!list->is_empty()) {
5322 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5323 _hrm.insert_list_into_free_list(list);
5324 }
5325 }
5326
5327 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5328 decrease_used(bytes);
5329 }
5330
5331 class G1ParCleanupCTTask : public AbstractGangTask {
5332 G1SATBCardTableModRefBS* _ct_bs;
5333 G1CollectedHeap* _g1h;
5334 HeapRegion* volatile _su_head;
5335 public:
5336 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5337 G1CollectedHeap* g1h) :
5338 AbstractGangTask("G1 Par Cleanup CT Task"),
5339 _ct_bs(ct_bs), _g1h(g1h) { }
5340
5341 void work(uint worker_id) {
5342 HeapRegion* r;
5343 while (r = _g1h->pop_dirty_cards_region()) {
5344 clear_cards(r);
5345 }
5346 }
5347
5348 void clear_cards(HeapRegion* r) {
5349 // Cards of the survivors should have already been dirtied.
5350 if (!r->is_survivor()) {
5351 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5352 }
5353 }
5354 };
5355
5356 #ifndef PRODUCT
5357 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5358 G1CollectedHeap* _g1h;
5359 G1SATBCardTableModRefBS* _ct_bs;
5360 public:
5361 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5362 : _g1h(g1h), _ct_bs(ct_bs) { }
5363 virtual bool doHeapRegion(HeapRegion* r) {
5364 if (r->is_survivor()) {
5365 _g1h->verify_dirty_region(r);
5366 } else {
5367 _g1h->verify_not_dirty_region(r);
5368 }
5369 return false;
5370 }
5371 };
5372
5373 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5374 // All of the region should be clean.
5375 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5376 MemRegion mr(hr->bottom(), hr->end());
5377 ct_bs->verify_not_dirty_region(mr);
5378 }
5379
5380 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5381 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5382 // dirty allocated blocks as they allocate them. The thread that
5383 // retires each region and replaces it with a new one will do a
5384 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5385 // not dirty that area (one less thing to have to do while holding
5386 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5387 // is dirty.
5388 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5389 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5390 if (hr->is_young()) {
5391 ct_bs->verify_g1_young_region(mr);
5392 } else {
5393 ct_bs->verify_dirty_region(mr);
5394 }
5395 }
5396
5397 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5398 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5399 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5400 verify_dirty_region(hr);
5401 }
5402 }
5403
5404 void G1CollectedHeap::verify_dirty_young_regions() {
5405 verify_dirty_young_list(_young_list->first_region());
5406 }
5407
5408 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5409 HeapWord* tams, HeapWord* end) {
5410 guarantee(tams <= end,
5411 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5412 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5413 if (result < end) {
5414 gclog_or_tty->cr();
5415 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5416 bitmap_name, p2i(result));
5417 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5418 bitmap_name, p2i(tams), p2i(end));
5419 return false;
5420 }
5421 return true;
5422 }
5423
5424 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5425 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5426 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5427
5428 HeapWord* bottom = hr->bottom();
5429 HeapWord* ptams = hr->prev_top_at_mark_start();
5430 HeapWord* ntams = hr->next_top_at_mark_start();
5431 HeapWord* end = hr->end();
5432
5433 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5434
5435 bool res_n = true;
5436 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5437 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5438 // if we happen to be in that state.
5439 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5440 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5441 }
5442 if (!res_p || !res_n) {
5443 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5444 HR_FORMAT_PARAMS(hr));
5445 gclog_or_tty->print_cr("#### Caller: %s", caller);
5446 return false;
5447 }
5448 return true;
5449 }
5450
5451 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5452 if (!G1VerifyBitmaps) return;
5453
5454 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5455 }
5456
5457 class G1VerifyBitmapClosure : public HeapRegionClosure {
5458 private:
5459 const char* _caller;
5460 G1CollectedHeap* _g1h;
5461 bool _failures;
5462
5463 public:
5464 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5465 _caller(caller), _g1h(g1h), _failures(false) { }
5466
5467 bool failures() { return _failures; }
5468
5469 virtual bool doHeapRegion(HeapRegion* hr) {
5470 bool result = _g1h->verify_bitmaps(_caller, hr);
5471 if (!result) {
5472 _failures = true;
5473 }
5474 return false;
5475 }
5476 };
5477
5478 void G1CollectedHeap::check_bitmaps(const char* caller) {
5479 if (!G1VerifyBitmaps) return;
5480
5481 G1VerifyBitmapClosure cl(caller, this);
5482 heap_region_iterate(&cl);
5483 guarantee(!cl.failures(), "bitmap verification");
5484 }
5485
5486 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5487 private:
5488 bool _failures;
5489 public:
5490 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5491
5492 virtual bool doHeapRegion(HeapRegion* hr) {
5493 uint i = hr->hrm_index();
5494 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5495 if (hr->is_humongous()) {
5496 if (hr->in_collection_set()) {
5497 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5498 _failures = true;
5499 return true;
5500 }
5501 if (cset_state.is_in_cset()) {
5502 gclog_or_tty->print_cr("\n## inconsistent cset state " CSETSTATE_FORMAT " for humongous region %u", cset_state.value(), i);
5503 _failures = true;
5504 return true;
5505 }
5506 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5507 gclog_or_tty->print_cr("\n## inconsistent cset state " CSETSTATE_FORMAT " for continues humongous region %u", cset_state.value(), i);
5508 _failures = true;
5509 return true;
5510 }
5511 } else {
5512 if (cset_state.is_humongous()) {
5513 gclog_or_tty->print_cr("\n## inconsistent cset state " CSETSTATE_FORMAT " for non-humongous region %u", cset_state.value(), i);
5514 _failures = true;
5515 return true;
5516 }
5517 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5518 gclog_or_tty->print_cr("\n## in CSet %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5519 hr->in_collection_set(), cset_state.value(), i);
5520 _failures = true;
5521 return true;
5522 }
5523 if (cset_state.is_in_cset()) {
5524 if (hr->is_young() != (cset_state.is_young())) {
5525 gclog_or_tty->print_cr("\n## is_young %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5526 hr->is_young(), cset_state.value(), i);
5527 _failures = true;
5528 return true;
5529 }
5530 if (hr->is_old() != (cset_state.is_old())) {
5531 gclog_or_tty->print_cr("\n## is_old %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5532 hr->is_old(), cset_state.value(), i);
5533 _failures = true;
5534 return true;
5535 }
5536 }
5537 }
5538 return false;
5539 }
5540
5541 bool failures() const { return _failures; }
5542 };
5543
5544 bool G1CollectedHeap::check_cset_fast_test() {
5545 G1CheckCSetFastTableClosure cl;
5546 _hrm.iterate(&cl);
5547 return !cl.failures();
5548 }
5549 #endif // PRODUCT
5550
5551 void G1CollectedHeap::cleanUpCardTable() {
5552 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5553 double start = os::elapsedTime();
5554
5555 {
5556 // Iterate over the dirty cards region list.
5557 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5558
5559 workers()->run_task(&cleanup_task);
5560 #ifndef PRODUCT
5561 if (G1VerifyCTCleanup || VerifyAfterGC) {
5562 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5563 heap_region_iterate(&cleanup_verifier);
5564 }
5565 #endif
5566 }
5567
5568 double elapsed = os::elapsedTime() - start;
5569 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5570 }
5571
5572 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5573 size_t pre_used = 0;
5574 FreeRegionList local_free_list("Local List for CSet Freeing");
5575
5576 double young_time_ms = 0.0;
5577 double non_young_time_ms = 0.0;
5578
5579 // Since the collection set is a superset of the the young list,
5580 // all we need to do to clear the young list is clear its
5581 // head and length, and unlink any young regions in the code below
5582 _young_list->clear();
5583
5584 G1CollectorPolicy* policy = g1_policy();
5585
5586 double start_sec = os::elapsedTime();
5587 bool non_young = true;
5588
5589 HeapRegion* cur = cs_head;
5590 int age_bound = -1;
5591 size_t rs_lengths = 0;
5592
5593 while (cur != NULL) {
5594 assert(!is_on_master_free_list(cur), "sanity");
5595 if (non_young) {
5596 if (cur->is_young()) {
5597 double end_sec = os::elapsedTime();
5598 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5599 non_young_time_ms += elapsed_ms;
5600
5601 start_sec = os::elapsedTime();
5602 non_young = false;
5603 }
5604 } else {
5605 if (!cur->is_young()) {
5606 double end_sec = os::elapsedTime();
5607 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5608 young_time_ms += elapsed_ms;
5609
5610 start_sec = os::elapsedTime();
5611 non_young = true;
5612 }
5613 }
5614
5615 rs_lengths += cur->rem_set()->occupied_locked();
5616
5617 HeapRegion* next = cur->next_in_collection_set();
5618 assert(cur->in_collection_set(), "bad CS");
5619 cur->set_next_in_collection_set(NULL);
5620 clear_in_cset(cur);
5621
5622 if (cur->is_young()) {
5623 int index = cur->young_index_in_cset();
5624 assert(index != -1, "invariant");
5625 assert((uint) index < policy->young_cset_region_length(), "invariant");
5626 size_t words_survived = surviving_young_words[index];
5627 cur->record_surv_words_in_group(words_survived);
5628
5629 // At this point the we have 'popped' cur from the collection set
5630 // (linked via next_in_collection_set()) but it is still in the
5631 // young list (linked via next_young_region()). Clear the
5632 // _next_young_region field.
5633 cur->set_next_young_region(NULL);
5634 } else {
5635 int index = cur->young_index_in_cset();
5636 assert(index == -1, "invariant");
5637 }
5638
5639 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5640 (!cur->is_young() && cur->young_index_in_cset() == -1),
5641 "invariant" );
5642
5643 if (!cur->evacuation_failed()) {
5644 MemRegion used_mr = cur->used_region();
5645
5646 // And the region is empty.
5647 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5648 pre_used += cur->used();
5649 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5650 } else {
5651 cur->uninstall_surv_rate_group();
5652 if (cur->is_young()) {
5653 cur->set_young_index_in_cset(-1);
5654 }
5655 cur->set_evacuation_failed(false);
5656 // When moving a young gen region to old gen, we "allocate" that whole region
5657 // there. This is in addition to any already evacuated objects. Notify the
5658 // policy about that.
5659 // Old gen regions do not cause an additional allocation: both the objects
5660 // still in the region and the ones already moved are accounted for elsewhere.
5661 if (cur->is_young()) {
5662 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
5663 }
5664 // The region is now considered to be old.
5665 cur->set_old();
5666 // Do some allocation statistics accounting. Regions that failed evacuation
5667 // are always made old, so there is no need to update anything in the young
5668 // gen statistics, but we need to update old gen statistics.
5669 size_t used_words = cur->marked_bytes() / HeapWordSize;
5670 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5671 _old_set.add(cur);
5672 evacuation_info.increment_collectionset_used_after(cur->used());
5673 }
5674 cur = next;
5675 }
5676
5677 evacuation_info.set_regions_freed(local_free_list.length());
5678 policy->record_max_rs_lengths(rs_lengths);
5679 policy->cset_regions_freed();
5680
5681 double end_sec = os::elapsedTime();
5682 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5683
5684 if (non_young) {
5685 non_young_time_ms += elapsed_ms;
5686 } else {
5687 young_time_ms += elapsed_ms;
5688 }
5689
5690 prepend_to_freelist(&local_free_list);
5691 decrement_summary_bytes(pre_used);
5692 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5693 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5694 }
5695
5696 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5697 private:
5698 FreeRegionList* _free_region_list;
5699 HeapRegionSet* _proxy_set;
5700 uint _humongous_regions_removed;
5701 size_t _freed_bytes;
5702 public:
5703
5704 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5705 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
5706 }
5707
5708 virtual bool doHeapRegion(HeapRegion* r) {
5709 if (!r->is_starts_humongous()) {
5710 return false;
5711 }
5712
5713 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5714
5715 oop obj = (oop)r->bottom();
5716 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5717
5718 // The following checks whether the humongous object is live are sufficient.
5719 // The main additional check (in addition to having a reference from the roots
5720 // or the young gen) is whether the humongous object has a remembered set entry.
5721 //
5722 // A humongous object cannot be live if there is no remembered set for it
5723 // because:
5724 // - there can be no references from within humongous starts regions referencing
5725 // the object because we never allocate other objects into them.
5726 // (I.e. there are no intra-region references that may be missed by the
5727 // remembered set)
5728 // - as soon there is a remembered set entry to the humongous starts region
5729 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5730 // until the end of a concurrent mark.
5731 //
5732 // It is not required to check whether the object has been found dead by marking
5733 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5734 // all objects allocated during that time are considered live.
5735 // SATB marking is even more conservative than the remembered set.
5736 // So if at this point in the collection there is no remembered set entry,
5737 // nobody has a reference to it.
5738 // At the start of collection we flush all refinement logs, and remembered sets
5739 // are completely up-to-date wrt to references to the humongous object.
5740 //
5741 // Other implementation considerations:
5742 // - never consider object arrays at this time because they would pose
5743 // considerable effort for cleaning up the the remembered sets. This is
5744 // required because stale remembered sets might reference locations that
5745 // are currently allocated into.
5746 uint region_idx = r->hrm_index();
5747 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5748 !r->rem_set()->is_empty()) {
5749
5750 if (G1TraceEagerReclaimHumongousObjects) {
5751 gclog_or_tty->print_cr("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5752 region_idx,
5753 (size_t)obj->size() * HeapWordSize,
5754 p2i(r->bottom()),
5755 r->rem_set()->occupied(),
5756 r->rem_set()->strong_code_roots_list_length(),
5757 next_bitmap->isMarked(r->bottom()),
5758 g1h->is_humongous_reclaim_candidate(region_idx),
5759 obj->is_typeArray()
5760 );
5761 }
5762
5763 return false;
5764 }
5765
5766 guarantee(obj->is_typeArray(),
5767 "Only eagerly reclaiming type arrays is supported, but the object "
5768 PTR_FORMAT " is not.", p2i(r->bottom()));
5769
5770 if (G1TraceEagerReclaimHumongousObjects) {
5771 gclog_or_tty->print_cr("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5772 region_idx,
5773 (size_t)obj->size() * HeapWordSize,
5774 p2i(r->bottom()),
5775 r->rem_set()->occupied(),
5776 r->rem_set()->strong_code_roots_list_length(),
5777 next_bitmap->isMarked(r->bottom()),
5778 g1h->is_humongous_reclaim_candidate(region_idx),
5779 obj->is_typeArray()
5780 );
5781 }
5782 // Need to clear mark bit of the humongous object if already set.
5783 if (next_bitmap->isMarked(r->bottom())) {
5784 next_bitmap->clear(r->bottom());
5785 }
5786 do {
5787 HeapRegion* next = g1h->next_region_in_humongous(r);
5788 _freed_bytes += r->used();
5789 r->set_containing_set(NULL);
5790 _humongous_regions_removed++;
5791 g1h->free_humongous_region(r, _free_region_list, false);
5792 r = next;
5793 } while (r != NULL);
5794
5795 return false;
5796 }
5797
5798 uint humongous_free_count() {
5799 return _humongous_regions_removed;
5800 }
5801
5802 size_t bytes_freed() const {
5803 return _freed_bytes;
5804 }
5805 };
5806
5807 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5808 assert_at_safepoint(true);
5809
5810 if (!G1EagerReclaimHumongousObjects ||
5811 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5812 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5813 return;
5814 }
5815
5816 double start_time = os::elapsedTime();
5817
5818 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5819
5820 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5821 heap_region_iterate(&cl);
5822
5823 remove_from_old_sets(0, cl.humongous_free_count());
5824
5825 G1HRPrinter* hrp = hr_printer();
5826 if (hrp->is_active()) {
5827 FreeRegionListIterator iter(&local_cleanup_list);
5828 while (iter.more_available()) {
5829 HeapRegion* hr = iter.get_next();
5830 hrp->cleanup(hr);
5831 }
5832 }
5833
5834 prepend_to_freelist(&local_cleanup_list);
5835 decrement_summary_bytes(cl.bytes_freed());
5836
5837 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5838 cl.humongous_free_count());
5839 }
5840
5841 // This routine is similar to the above but does not record
5842 // any policy statistics or update free lists; we are abandoning
5843 // the current incremental collection set in preparation of a
5844 // full collection. After the full GC we will start to build up
5845 // the incremental collection set again.
5846 // This is only called when we're doing a full collection
5847 // and is immediately followed by the tearing down of the young list.
5848
5849 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5850 HeapRegion* cur = cs_head;
5851
5852 while (cur != NULL) {
5853 HeapRegion* next = cur->next_in_collection_set();
5854 assert(cur->in_collection_set(), "bad CS");
5855 cur->set_next_in_collection_set(NULL);
5856 clear_in_cset(cur);
5857 cur->set_young_index_in_cset(-1);
5858 cur = next;
5859 }
5860 }
5861
5862 void G1CollectedHeap::set_free_regions_coming() {
5863 if (G1ConcRegionFreeingVerbose) {
5864 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5865 "setting free regions coming");
5866 }
5867
5868 assert(!free_regions_coming(), "pre-condition");
5869 _free_regions_coming = true;
5870 }
5871
5872 void G1CollectedHeap::reset_free_regions_coming() {
5873 assert(free_regions_coming(), "pre-condition");
5874
5875 {
5876 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5877 _free_regions_coming = false;
5878 SecondaryFreeList_lock->notify_all();
5879 }
5880
5881 if (G1ConcRegionFreeingVerbose) {
5882 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5883 "reset free regions coming");
5884 }
5885 }
5886
5887 void G1CollectedHeap::wait_while_free_regions_coming() {
5888 // Most of the time we won't have to wait, so let's do a quick test
5889 // first before we take the lock.
5890 if (!free_regions_coming()) {
5891 return;
5892 }
5893
5894 if (G1ConcRegionFreeingVerbose) {
5895 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5896 "waiting for free regions");
5897 }
5898
5899 {
5900 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5901 while (free_regions_coming()) {
5902 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5903 }
5904 }
5905
5906 if (G1ConcRegionFreeingVerbose) {
5907 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5908 "done waiting for free regions");
5909 }
5910 }
5911
5912 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5913 return _allocator->is_retained_old_region(hr);
5914 }
5915
5916 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5917 _young_list->push_region(hr);
5918 }
5919
5920 class NoYoungRegionsClosure: public HeapRegionClosure {
5921 private:
5922 bool _success;
5923 public:
5924 NoYoungRegionsClosure() : _success(true) { }
5925 bool doHeapRegion(HeapRegion* r) {
5926 if (r->is_young()) {
5927 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5928 p2i(r->bottom()), p2i(r->end()));
5929 _success = false;
5930 }
5931 return false;
5932 }
5933 bool success() { return _success; }
5934 };
5935
5936 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5937 bool ret = _young_list->check_list_empty(check_sample);
5938
5939 if (check_heap) {
5940 NoYoungRegionsClosure closure;
5941 heap_region_iterate(&closure);
5942 ret = ret && closure.success();
5943 }
5944
5945 return ret;
5946 }
5947
5948 class TearDownRegionSetsClosure : public HeapRegionClosure {
5949 private:
5950 HeapRegionSet *_old_set;
5951
5952 public:
5953 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5954
5955 bool doHeapRegion(HeapRegion* r) {
5956 if (r->is_old()) {
5957 _old_set->remove(r);
5958 } else {
5959 // We ignore free regions, we'll empty the free list afterwards.
5960 // We ignore young regions, we'll empty the young list afterwards.
5961 // We ignore humongous regions, we're not tearing down the
5962 // humongous regions set.
5963 assert(r->is_free() || r->is_young() || r->is_humongous(),
5964 "it cannot be another type");
5965 }
5966 return false;
5967 }
5968
5969 ~TearDownRegionSetsClosure() {
5970 assert(_old_set->is_empty(), "post-condition");
5971 }
5972 };
5973
5974 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5975 assert_at_safepoint(true /* should_be_vm_thread */);
5976
5977 if (!free_list_only) {
5978 TearDownRegionSetsClosure cl(&_old_set);
5979 heap_region_iterate(&cl);
5980
5981 // Note that emptying the _young_list is postponed and instead done as
5982 // the first step when rebuilding the regions sets again. The reason for
5983 // this is that during a full GC string deduplication needs to know if
5984 // a collected region was young or old when the full GC was initiated.
5985 }
5986 _hrm.remove_all_free_regions();
5987 }
5988
5989 void G1CollectedHeap::increase_used(size_t bytes) {
5990 _summary_bytes_used += bytes;
5991 }
5992
5993 void G1CollectedHeap::decrease_used(size_t bytes) {
5994 assert(_summary_bytes_used >= bytes,
5995 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5996 _summary_bytes_used, bytes);
5997 _summary_bytes_used -= bytes;
5998 }
5999
6000 void G1CollectedHeap::set_used(size_t bytes) {
6001 _summary_bytes_used = bytes;
6002 }
6003
6004 class RebuildRegionSetsClosure : public HeapRegionClosure {
6005 private:
6006 bool _free_list_only;
6007 HeapRegionSet* _old_set;
6008 HeapRegionManager* _hrm;
6009 size_t _total_used;
6010
6011 public:
6012 RebuildRegionSetsClosure(bool free_list_only,
6013 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6014 _free_list_only(free_list_only),
6015 _old_set(old_set), _hrm(hrm), _total_used(0) {
6016 assert(_hrm->num_free_regions() == 0, "pre-condition");
6017 if (!free_list_only) {
6018 assert(_old_set->is_empty(), "pre-condition");
6019 }
6020 }
6021
6022 bool doHeapRegion(HeapRegion* r) {
6023 if (r->is_empty()) {
6024 // Add free regions to the free list
6025 r->set_free();
6026 r->set_allocation_context(AllocationContext::system());
6027 _hrm->insert_into_free_list(r);
6028 } else if (!_free_list_only) {
6029 assert(!r->is_young(), "we should not come across young regions");
6030
6031 if (r->is_humongous()) {
6032 // We ignore humongous regions. We left the humongous set unchanged.
6033 } else {
6034 // Objects that were compacted would have ended up on regions
6035 // that were previously old or free. Archive regions (which are
6036 // old) will not have been touched.
6037 assert(r->is_free() || r->is_old(), "invariant");
6038 // We now consider them old, so register as such. Leave
6039 // archive regions set that way, however, while still adding
6040 // them to the old set.
6041 if (!r->is_archive()) {
6042 r->set_old();
6043 }
6044 _old_set->add(r);
6045 }
6046 _total_used += r->used();
6047 }
6048
6049 return false;
6050 }
6051
6052 size_t total_used() {
6053 return _total_used;
6054 }
6055 };
6056
6057 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6058 assert_at_safepoint(true /* should_be_vm_thread */);
6059
6060 if (!free_list_only) {
6061 _young_list->empty_list();
6062 }
6063
6064 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6065 heap_region_iterate(&cl);
6066
6067 if (!free_list_only) {
6068 set_used(cl.total_used());
6069 if (_archive_allocator != NULL) {
6070 _archive_allocator->clear_used();
6071 }
6072 }
6073 assert(used_unlocked() == recalculate_used(),
6074 "inconsistent used_unlocked(), "
6075 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6076 used_unlocked(), recalculate_used());
6077 }
6078
6079 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6080 _refine_cte_cl->set_concurrent(concurrent);
6081 }
6082
6083 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6084 HeapRegion* hr = heap_region_containing(p);
6085 return hr->is_in(p);
6086 }
6087
6088 // Methods for the mutator alloc region
6089
6090 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6091 bool force) {
6092 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6093 assert(!force || g1_policy()->can_expand_young_list(),
6094 "if force is true we should be able to expand the young list");
6095 bool young_list_full = g1_policy()->is_young_list_full();
6096 if (force || !young_list_full) {
6097 HeapRegion* new_alloc_region = new_region(word_size,
6098 false /* is_old */,
6099 false /* do_expand */);
6100 if (new_alloc_region != NULL) {
6101 set_region_short_lived_locked(new_alloc_region);
6102 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6103 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6104 return new_alloc_region;
6105 }
6106 }
6107 return NULL;
6108 }
6109
6110 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6111 size_t allocated_bytes) {
6112 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6113 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6114
6115 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6116 increase_used(allocated_bytes);
6117 _hr_printer.retire(alloc_region);
6118 // We update the eden sizes here, when the region is retired,
6119 // instead of when it's allocated, since this is the point that its
6120 // used space has been recored in _summary_bytes_used.
6121 g1mm()->update_eden_size();
6122 }
6123
6124 // Methods for the GC alloc regions
6125
6126 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6127 uint count,
6128 InCSetState dest) {
6129 assert(FreeList_lock->owned_by_self(), "pre-condition");
6130
6131 if (count < g1_policy()->max_regions(dest)) {
6132 const bool is_survivor = (dest.is_young());
6133 HeapRegion* new_alloc_region = new_region(word_size,
6134 !is_survivor,
6135 true /* do_expand */);
6136 if (new_alloc_region != NULL) {
6137 // We really only need to do this for old regions given that we
6138 // should never scan survivors. But it doesn't hurt to do it
6139 // for survivors too.
6140 new_alloc_region->record_timestamp();
6141 if (is_survivor) {
6142 new_alloc_region->set_survivor();
6143 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6144 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6145 } else {
6146 new_alloc_region->set_old();
6147 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6148 check_bitmaps("Old Region Allocation", new_alloc_region);
6149 }
6150 bool during_im = collector_state()->during_initial_mark_pause();
6151 new_alloc_region->note_start_of_copying(during_im);
6152 return new_alloc_region;
6153 }
6154 }
6155 return NULL;
6156 }
6157
6158 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6159 size_t allocated_bytes,
6160 InCSetState dest) {
6161 bool during_im = collector_state()->during_initial_mark_pause();
6162 alloc_region->note_end_of_copying(during_im);
6163 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6164 if (dest.is_young()) {
6165 young_list()->add_survivor_region(alloc_region);
6166 } else {
6167 _old_set.add(alloc_region);
6168 }
6169 _hr_printer.retire(alloc_region);
6170 }
6171
6172 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6173 bool expanded = false;
6174 uint index = _hrm.find_highest_free(&expanded);
6175
6176 if (index != G1_NO_HRM_INDEX) {
6177 if (expanded) {
6178 ergo_verbose1(ErgoHeapSizing,
6179 "attempt heap expansion",
6180 ergo_format_reason("requested address range outside heap bounds")
6181 ergo_format_byte("region size"),
6182 HeapRegion::GrainWords * HeapWordSize);
6183 }
6184 _hrm.allocate_free_regions_starting_at(index, 1);
6185 return region_at(index);
6186 }
6187 return NULL;
6188 }
6189
6190 // Heap region set verification
6191
6192 class VerifyRegionListsClosure : public HeapRegionClosure {
6193 private:
6194 HeapRegionSet* _old_set;
6195 HeapRegionSet* _humongous_set;
6196 HeapRegionManager* _hrm;
6197
6198 public:
6199 uint _old_count;
6200 uint _humongous_count;
6201 uint _free_count;
6202
6203 VerifyRegionListsClosure(HeapRegionSet* old_set,
6204 HeapRegionSet* humongous_set,
6205 HeapRegionManager* hrm) :
6206 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6207 _old_count(), _humongous_count(), _free_count(){ }
6208
6209 bool doHeapRegion(HeapRegion* hr) {
6210 if (hr->is_young()) {
6211 // TODO
6212 } else if (hr->is_humongous()) {
6213 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6214 _humongous_count++;
6215 } else if (hr->is_empty()) {
6216 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6217 _free_count++;
6218 } else if (hr->is_old()) {
6219 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6220 _old_count++;
6221 } else {
6222 // There are no other valid region types. Check for one invalid
6223 // one we can identify: pinned without old or humongous set.
6224 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6225 ShouldNotReachHere();
6226 }
6227 return false;
6228 }
6229
6230 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6231 guarantee(old_set->length() == _old_count, "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count);
6232 guarantee(humongous_set->length() == _humongous_count, "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count);
6233 guarantee(free_list->num_free_regions() == _free_count, "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count);
6234 }
6235 };
6236
6237 void G1CollectedHeap::verify_region_sets() {
6238 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6239
6240 // First, check the explicit lists.
6241 _hrm.verify();
6242 {
6243 // Given that a concurrent operation might be adding regions to
6244 // the secondary free list we have to take the lock before
6245 // verifying it.
6246 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6247 _secondary_free_list.verify_list();
6248 }
6249
6250 // If a concurrent region freeing operation is in progress it will
6251 // be difficult to correctly attributed any free regions we come
6252 // across to the correct free list given that they might belong to
6253 // one of several (free_list, secondary_free_list, any local lists,
6254 // etc.). So, if that's the case we will skip the rest of the
6255 // verification operation. Alternatively, waiting for the concurrent
6256 // operation to complete will have a non-trivial effect on the GC's
6257 // operation (no concurrent operation will last longer than the
6258 // interval between two calls to verification) and it might hide
6259 // any issues that we would like to catch during testing.
6260 if (free_regions_coming()) {
6261 return;
6262 }
6263
6264 // Make sure we append the secondary_free_list on the free_list so
6265 // that all free regions we will come across can be safely
6266 // attributed to the free_list.
6267 append_secondary_free_list_if_not_empty_with_lock();
6268
6269 // Finally, make sure that the region accounting in the lists is
6270 // consistent with what we see in the heap.
6271
6272 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6273 heap_region_iterate(&cl);
6274 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6275 }
6276
6277 // Optimized nmethod scanning
6278
6279 class RegisterNMethodOopClosure: public OopClosure {
6280 G1CollectedHeap* _g1h;
6281 nmethod* _nm;
6282
6283 template <class T> void do_oop_work(T* p) {
6284 T heap_oop = oopDesc::load_heap_oop(p);
6285 if (!oopDesc::is_null(heap_oop)) {
6286 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6287 HeapRegion* hr = _g1h->heap_region_containing(obj);
6288 assert(!hr->is_continues_humongous(),
6289 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6290 " starting at " HR_FORMAT,
6291 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6292
6293 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6294 hr->add_strong_code_root_locked(_nm);
6295 }
6296 }
6297
6298 public:
6299 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6300 _g1h(g1h), _nm(nm) {}
6301
6302 void do_oop(oop* p) { do_oop_work(p); }
6303 void do_oop(narrowOop* p) { do_oop_work(p); }
6304 };
6305
6306 class UnregisterNMethodOopClosure: public OopClosure {
6307 G1CollectedHeap* _g1h;
6308 nmethod* _nm;
6309
6310 template <class T> void do_oop_work(T* p) {
6311 T heap_oop = oopDesc::load_heap_oop(p);
6312 if (!oopDesc::is_null(heap_oop)) {
6313 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6314 HeapRegion* hr = _g1h->heap_region_containing(obj);
6315 assert(!hr->is_continues_humongous(),
6316 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6317 " starting at " HR_FORMAT,
6318 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6319
6320 hr->remove_strong_code_root(_nm);
6321 }
6322 }
6323
6324 public:
6325 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6326 _g1h(g1h), _nm(nm) {}
6327
6328 void do_oop(oop* p) { do_oop_work(p); }
6329 void do_oop(narrowOop* p) { do_oop_work(p); }
6330 };
6331
6332 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6333 CollectedHeap::register_nmethod(nm);
6334
6335 guarantee(nm != NULL, "sanity");
6336 RegisterNMethodOopClosure reg_cl(this, nm);
6337 nm->oops_do(®_cl);
6338 }
6339
6340 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6341 CollectedHeap::unregister_nmethod(nm);
6342
6343 guarantee(nm != NULL, "sanity");
6344 UnregisterNMethodOopClosure reg_cl(this, nm);
6345 nm->oops_do(®_cl, true);
6346 }
6347
6348 void G1CollectedHeap::purge_code_root_memory() {
6349 double purge_start = os::elapsedTime();
6350 G1CodeRootSet::purge();
6351 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6352 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6353 }
6354
6355 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6356 G1CollectedHeap* _g1h;
6357
6358 public:
6359 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6360 _g1h(g1h) {}
6361
6362 void do_code_blob(CodeBlob* cb) {
6363 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6364 if (nm == NULL) {
6365 return;
6366 }
6367
6368 if (ScavengeRootsInCode) {
6369 _g1h->register_nmethod(nm);
6370 }
6371 }
6372 };
6373
6374 void G1CollectedHeap::rebuild_strong_code_roots() {
6375 RebuildStrongCodeRootClosure blob_cl(this);
6376 CodeCache::blobs_do(&blob_cl);
6377 }