1 /*
2 * Copyright (c) 2001, 2016, 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/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectorPolicy.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1HeapTransition.hpp"
43 #include "gc/g1/g1HeapVerifier.hpp"
44 #include "gc/g1/g1MarkSweep.hpp"
45 #include "gc/g1/g1OopClosures.inline.hpp"
46 #include "gc/g1/g1ParScanThreadState.inline.hpp"
47 #include "gc/g1/g1RegionToSpaceMapper.hpp"
48 #include "gc/g1/g1RemSet.inline.hpp"
49 #include "gc/g1/g1RootClosures.hpp"
50 #include "gc/g1/g1RootProcessor.hpp"
51 #include "gc/g1/g1StringDedup.hpp"
52 #include "gc/g1/g1YCTypes.hpp"
53 #include "gc/g1/heapRegion.inline.hpp"
54 #include "gc/g1/heapRegionRemSet.hpp"
55 #include "gc/g1/heapRegionSet.inline.hpp"
56 #include "gc/g1/suspendibleThreadSet.hpp"
57 #include "gc/g1/vm_operations_g1.hpp"
58 #include "gc/shared/gcHeapSummary.hpp"
59 #include "gc/shared/gcId.hpp"
60 #include "gc/shared/gcLocker.inline.hpp"
61 #include "gc/shared/gcTimer.hpp"
62 #include "gc/shared/gcTrace.hpp"
63 #include "gc/shared/gcTraceTime.inline.hpp"
64 #include "gc/shared/generationSpec.hpp"
65 #include "gc/shared/isGCActiveMark.hpp"
66 #include "gc/shared/referenceProcessor.inline.hpp"
67 #include "gc/shared/taskqueue.inline.hpp"
68 #include "logging/log.hpp"
69 #include "memory/allocation.hpp"
70 #include "memory/iterator.hpp"
71 #include "oops/oop.inline.hpp"
72 #include "runtime/atomic.inline.hpp"
73 #include "runtime/init.hpp"
74 #include "runtime/orderAccess.inline.hpp"
75 #include "runtime/vmThread.hpp"
76 #include "utilities/globalDefinitions.hpp"
77 #include "utilities/stack.inline.hpp"
78
79 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
80
81 // INVARIANTS/NOTES
82 //
83 // All allocation activity covered by the G1CollectedHeap interface is
84 // serialized by acquiring the HeapLock. This happens in mem_allocate
85 // and allocate_new_tlab, which are the "entry" points to the
86 // allocation code from the rest of the JVM. (Note that this does not
87 // apply to TLAB allocation, which is not part of this interface: it
88 // is done by clients of this interface.)
89
90 // Local to this file.
91
92 class RefineCardTableEntryClosure: public CardTableEntryClosure {
93 bool _concurrent;
94 public:
95 RefineCardTableEntryClosure() : _concurrent(true) { }
96
97 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
98 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
99 // This path is executed by the concurrent refine or mutator threads,
100 // concurrently, and so we do not care if card_ptr contains references
101 // that point into the collection set.
102 assert(!oops_into_cset, "should be");
103
104 if (_concurrent && SuspendibleThreadSet::should_yield()) {
105 // Caller will actually yield.
106 return false;
107 }
108 // Otherwise, we finished successfully; return true.
109 return true;
110 }
111
112 void set_concurrent(bool b) { _concurrent = b; }
113 };
114
115
116 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
117 private:
118 size_t _num_dirtied;
119 G1CollectedHeap* _g1h;
120 G1SATBCardTableLoggingModRefBS* _g1_bs;
121
122 HeapRegion* region_for_card(jbyte* card_ptr) const {
123 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
124 }
125
126 bool will_become_free(HeapRegion* hr) const {
127 // A region will be freed by free_collection_set if the region is in the
128 // collection set and has not had an evacuation failure.
129 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
130 }
131
132 public:
133 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
134 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
135
136 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
137 HeapRegion* hr = region_for_card(card_ptr);
138
139 // Should only dirty cards in regions that won't be freed.
140 if (!will_become_free(hr)) {
141 *card_ptr = CardTableModRefBS::dirty_card_val();
142 _num_dirtied++;
143 }
144
145 return true;
146 }
147
148 size_t num_dirtied() const { return _num_dirtied; }
149 };
150
151
152 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
153 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
154 }
155
156 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
157 // The from card cache is not the memory that is actually committed. So we cannot
158 // take advantage of the zero_filled parameter.
159 reset_from_card_cache(start_idx, num_regions);
160 }
161
162 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
163 {
164 // Claim the right to put the region on the dirty cards region list
165 // by installing a self pointer.
166 HeapRegion* next = hr->get_next_dirty_cards_region();
167 if (next == NULL) {
168 HeapRegion* res = (HeapRegion*)
169 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
170 NULL);
171 if (res == NULL) {
172 HeapRegion* head;
173 do {
174 // Put the region to the dirty cards region list.
175 head = _dirty_cards_region_list;
176 next = (HeapRegion*)
177 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
178 if (next == head) {
179 assert(hr->get_next_dirty_cards_region() == hr,
180 "hr->get_next_dirty_cards_region() != hr");
181 if (next == NULL) {
182 // The last region in the list points to itself.
183 hr->set_next_dirty_cards_region(hr);
184 } else {
185 hr->set_next_dirty_cards_region(next);
186 }
187 }
188 } while (next != head);
189 }
190 }
191 }
192
193 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
194 {
195 HeapRegion* head;
196 HeapRegion* hr;
197 do {
198 head = _dirty_cards_region_list;
199 if (head == NULL) {
200 return NULL;
201 }
202 HeapRegion* new_head = head->get_next_dirty_cards_region();
203 if (head == new_head) {
204 // The last region.
205 new_head = NULL;
206 }
207 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
208 head);
209 } while (hr != head);
210 assert(hr != NULL, "invariant");
211 hr->set_next_dirty_cards_region(NULL);
212 return hr;
213 }
214
215 // Returns true if the reference points to an object that
216 // can move in an incremental collection.
217 bool G1CollectedHeap::is_scavengable(const void* p) {
218 HeapRegion* hr = heap_region_containing(p);
219 return !hr->is_pinned();
220 }
221
222 // Private methods.
223
224 HeapRegion*
225 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
226 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
227 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
228 if (!_secondary_free_list.is_empty()) {
229 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
230 "secondary_free_list has %u entries",
231 _secondary_free_list.length());
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 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
241 "allocated " HR_FORMAT " from secondary_free_list",
242 HR_FORMAT_PARAMS(res));
243 return res;
244 }
245
246 // Wait here until we get notified either when (a) there are no
247 // more free regions coming or (b) some regions have been moved on
248 // the secondary_free_list.
249 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
250 }
251
252 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
253 "could not allocate from secondary_free_list");
254 return NULL;
255 }
256
257 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
258 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
259 "the only time we use this to allocate a humongous region is "
260 "when we are allocating a single humongous region");
261
262 HeapRegion* res;
263 if (G1StressConcRegionFreeing) {
264 if (!_secondary_free_list.is_empty()) {
265 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
266 "forced to look at the secondary_free_list");
267 res = new_region_try_secondary_free_list(is_old);
268 if (res != NULL) {
269 return res;
270 }
271 }
272 }
273
274 res = _hrm.allocate_free_region(is_old);
275
276 if (res == NULL) {
277 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
278 "res == NULL, trying the secondary_free_list");
279 res = new_region_try_secondary_free_list(is_old);
280 }
281 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
282 // Currently, only attempts to allocate GC alloc regions set
283 // do_expand to true. So, we should only reach here during a
284 // safepoint. If this assumption changes we might have to
285 // reconsider the use of _expand_heap_after_alloc_failure.
286 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
287
288 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
289 word_size * HeapWordSize);
290
291 if (expand(word_size * HeapWordSize)) {
292 // Given that expand() succeeded in expanding the heap, and we
293 // always expand the heap by an amount aligned to the heap
294 // region size, the free list should in theory not be empty.
295 // In either case allocate_free_region() will check for NULL.
296 res = _hrm.allocate_free_region(is_old);
297 } else {
298 _expand_heap_after_alloc_failure = false;
299 }
300 }
301 return res;
302 }
303
304 HeapWord*
305 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
306 uint num_regions,
307 size_t word_size,
308 AllocationContext_t context) {
309 assert(first != G1_NO_HRM_INDEX, "pre-condition");
310 assert(is_humongous(word_size), "word_size should be humongous");
311 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
312
313 // Index of last region in the series.
314 uint last = first + num_regions - 1;
315
316 // We need to initialize the region(s) we just discovered. This is
317 // a bit tricky given that it can happen concurrently with
318 // refinement threads refining cards on these regions and
319 // potentially wanting to refine the BOT as they are scanning
320 // those cards (this can happen shortly after a cleanup; see CR
321 // 6991377). So we have to set up the region(s) carefully and in
322 // a specific order.
323
324 // The word size sum of all the regions we will allocate.
325 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
326 assert(word_size <= word_size_sum, "sanity");
327
328 // This will be the "starts humongous" region.
329 HeapRegion* first_hr = region_at(first);
330 // The header of the new object will be placed at the bottom of
331 // the first region.
332 HeapWord* new_obj = first_hr->bottom();
333 // This will be the new top of the new object.
334 HeapWord* obj_top = new_obj + word_size;
335
336 // First, we need to zero the header of the space that we will be
337 // allocating. When we update top further down, some refinement
338 // threads might try to scan the region. By zeroing the header we
339 // ensure that any thread that will try to scan the region will
340 // come across the zero klass word and bail out.
341 //
342 // NOTE: It would not have been correct to have used
343 // CollectedHeap::fill_with_object() and make the space look like
344 // an int array. The thread that is doing the allocation will
345 // later update the object header to a potentially different array
346 // type and, for a very short period of time, the klass and length
347 // fields will be inconsistent. This could cause a refinement
348 // thread to calculate the object size incorrectly.
349 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
350
351 // How many words we use for filler objects.
352 size_t word_fill_size = word_size_sum - word_size;
353
354 // How many words memory we "waste" which cannot hold a filler object.
355 size_t words_not_fillable = 0;
356
357 if (word_fill_size >= min_fill_size()) {
358 fill_with_objects(obj_top, word_fill_size);
359 } else if (word_fill_size > 0) {
360 // We have space to fill, but we cannot fit an object there.
361 words_not_fillable = word_fill_size;
362 word_fill_size = 0;
363 }
364
365 // We will set up the first region as "starts humongous". This
366 // will also update the BOT covering all the regions to reflect
367 // that there is a single object that starts at the bottom of the
368 // first region.
369 first_hr->set_starts_humongous(obj_top, word_fill_size);
370 first_hr->set_allocation_context(context);
371 // Then, if there are any, we will set up the "continues
372 // humongous" regions.
373 HeapRegion* hr = NULL;
374 for (uint i = first + 1; i <= last; ++i) {
375 hr = region_at(i);
376 hr->set_continues_humongous(first_hr);
377 hr->set_allocation_context(context);
378 }
379
380 // Up to this point no concurrent thread would have been able to
381 // do any scanning on any region in this series. All the top
382 // fields still point to bottom, so the intersection between
383 // [bottom,top] and [card_start,card_end] will be empty. Before we
384 // update the top fields, we'll do a storestore to make sure that
385 // no thread sees the update to top before the zeroing of the
386 // object header and the BOT initialization.
387 OrderAccess::storestore();
388
389 // Now, we will update the top fields of the "continues humongous"
390 // regions except the last one.
391 for (uint i = first; i < last; ++i) {
392 hr = region_at(i);
393 hr->set_top(hr->end());
394 }
395
396 hr = region_at(last);
397 // If we cannot fit a filler object, we must set top to the end
398 // of the humongous object, otherwise we cannot iterate the heap
399 // and the BOT will not be complete.
400 hr->set_top(hr->end() - words_not_fillable);
401
402 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
403 "obj_top should be in last region");
404
405 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
406
407 assert(words_not_fillable == 0 ||
408 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
409 "Miscalculation in humongous allocation");
410
411 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
412
413 for (uint i = first; i <= last; ++i) {
414 hr = region_at(i);
415 _humongous_set.add(hr);
416 _hr_printer.alloc(hr);
417 }
418
419 return new_obj;
420 }
421
422 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
423 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
424 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
425 }
426
427 // If could fit into free regions w/o expansion, try.
428 // Otherwise, if can expand, do so.
429 // Otherwise, if using ex regions might help, try with ex given back.
430 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
431 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
432
433 _verifier->verify_region_sets_optional();
434
435 uint first = G1_NO_HRM_INDEX;
436 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
437
438 if (obj_regions == 1) {
439 // Only one region to allocate, try to use a fast path by directly allocating
440 // from the free lists. Do not try to expand here, we will potentially do that
441 // later.
442 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
443 if (hr != NULL) {
444 first = hr->hrm_index();
445 }
446 } else {
447 // We can't allocate humongous regions spanning more than one region while
448 // cleanupComplete() is running, since some of the regions we find to be
449 // empty might not yet be added to the free list. It is not straightforward
450 // to know in which list they are on so that we can remove them. We only
451 // need to do this if we need to allocate more than one region to satisfy the
452 // current humongous allocation request. If we are only allocating one region
453 // we use the one-region region allocation code (see above), that already
454 // potentially waits for regions from the secondary free list.
455 wait_while_free_regions_coming();
456 append_secondary_free_list_if_not_empty_with_lock();
457
458 // Policy: Try only empty regions (i.e. already committed first). Maybe we
459 // are lucky enough to find some.
460 first = _hrm.find_contiguous_only_empty(obj_regions);
461 if (first != G1_NO_HRM_INDEX) {
462 _hrm.allocate_free_regions_starting_at(first, obj_regions);
463 }
464 }
465
466 if (first == G1_NO_HRM_INDEX) {
467 // Policy: We could not find enough regions for the humongous object in the
468 // free list. Look through the heap to find a mix of free and uncommitted regions.
469 // If so, try expansion.
470 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
471 if (first != G1_NO_HRM_INDEX) {
472 // We found something. Make sure these regions are committed, i.e. expand
473 // the heap. Alternatively we could do a defragmentation GC.
474 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
475 word_size * HeapWordSize);
476
477
478 _hrm.expand_at(first, obj_regions);
479 g1_policy()->record_new_heap_size(num_regions());
480
481 #ifdef ASSERT
482 for (uint i = first; i < first + obj_regions; ++i) {
483 HeapRegion* hr = region_at(i);
484 assert(hr->is_free(), "sanity");
485 assert(hr->is_empty(), "sanity");
486 assert(is_on_master_free_list(hr), "sanity");
487 }
488 #endif
489 _hrm.allocate_free_regions_starting_at(first, obj_regions);
490 } else {
491 // Policy: Potentially trigger a defragmentation GC.
492 }
493 }
494
495 HeapWord* result = NULL;
496 if (first != G1_NO_HRM_INDEX) {
497 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
498 word_size, context);
499 assert(result != NULL, "it should always return a valid result");
500
501 // A successful humongous object allocation changes the used space
502 // information of the old generation so we need to recalculate the
503 // sizes and update the jstat counters here.
504 g1mm()->update_sizes();
505 }
506
507 _verifier->verify_region_sets_optional();
508
509 return result;
510 }
511
512 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
513 assert_heap_not_locked_and_not_at_safepoint();
514 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
515
516 uint dummy_gc_count_before;
517 uint dummy_gclocker_retry_count = 0;
518 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
519 }
520
521 HeapWord*
522 G1CollectedHeap::mem_allocate(size_t word_size,
523 bool* gc_overhead_limit_was_exceeded) {
524 assert_heap_not_locked_and_not_at_safepoint();
525
526 // Loop until the allocation is satisfied, or unsatisfied after GC.
527 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
528 uint gc_count_before;
529
530 HeapWord* result = NULL;
531 if (!is_humongous(word_size)) {
532 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
533 } else {
534 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
535 }
536 if (result != NULL) {
537 return result;
538 }
539
540 // Create the garbage collection operation...
541 VM_G1CollectForAllocation op(gc_count_before, word_size);
542 op.set_allocation_context(AllocationContext::current());
543
544 // ...and get the VM thread to execute it.
545 VMThread::execute(&op);
546
547 if (op.prologue_succeeded() && op.pause_succeeded()) {
548 // If the operation was successful we'll return the result even
549 // if it is NULL. If the allocation attempt failed immediately
550 // after a Full GC, it's unlikely we'll be able to allocate now.
551 HeapWord* result = op.result();
552 if (result != NULL && !is_humongous(word_size)) {
553 // Allocations that take place on VM operations do not do any
554 // card dirtying and we have to do it here. We only have to do
555 // this for non-humongous allocations, though.
556 dirty_young_block(result, word_size);
557 }
558 return result;
559 } else {
560 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
561 return NULL;
562 }
563 assert(op.result() == NULL,
564 "the result should be NULL if the VM op did not succeed");
565 }
566
567 // Give a warning if we seem to be looping forever.
568 if ((QueuedAllocationWarningCount > 0) &&
569 (try_count % QueuedAllocationWarningCount == 0)) {
570 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
571 }
572 }
573
574 ShouldNotReachHere();
575 return NULL;
576 }
577
578 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
579 AllocationContext_t context,
580 uint* gc_count_before_ret,
581 uint* gclocker_retry_count_ret) {
582 // Make sure you read the note in attempt_allocation_humongous().
583
584 assert_heap_not_locked_and_not_at_safepoint();
585 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
586 "be called for humongous allocation requests");
587
588 // We should only get here after the first-level allocation attempt
589 // (attempt_allocation()) failed to allocate.
590
591 // We will loop until a) we manage to successfully perform the
592 // allocation or b) we successfully schedule a collection which
593 // fails to perform the allocation. b) is the only case when we'll
594 // return NULL.
595 HeapWord* result = NULL;
596 for (int try_count = 1; /* we'll return */; try_count += 1) {
597 bool should_try_gc;
598 uint gc_count_before;
599
600 {
601 MutexLockerEx x(Heap_lock);
602 result = _allocator->attempt_allocation_locked(word_size, context);
603 if (result != NULL) {
604 return result;
605 }
606
607 if (GCLocker::is_active_and_needs_gc()) {
608 if (g1_policy()->can_expand_young_list()) {
609 // No need for an ergo verbose message here,
610 // can_expand_young_list() does this when it returns true.
611 result = _allocator->attempt_allocation_force(word_size, context);
612 if (result != NULL) {
613 return result;
614 }
615 }
616 should_try_gc = false;
617 } else {
618 // The GCLocker may not be active but the GCLocker initiated
619 // GC may not yet have been performed (GCLocker::needs_gc()
620 // returns true). In this case we do not try this GC and
621 // wait until the GCLocker initiated GC is performed, and
622 // then retry the allocation.
623 if (GCLocker::needs_gc()) {
624 should_try_gc = false;
625 } else {
626 // Read the GC count while still holding the Heap_lock.
627 gc_count_before = total_collections();
628 should_try_gc = true;
629 }
630 }
631 }
632
633 if (should_try_gc) {
634 bool succeeded;
635 result = do_collection_pause(word_size, gc_count_before, &succeeded,
636 GCCause::_g1_inc_collection_pause);
637 if (result != NULL) {
638 assert(succeeded, "only way to get back a non-NULL result");
639 return result;
640 }
641
642 if (succeeded) {
643 // If we get here we successfully scheduled a collection which
644 // failed to allocate. No point in trying to allocate
645 // further. We'll just return NULL.
646 MutexLockerEx x(Heap_lock);
647 *gc_count_before_ret = total_collections();
648 return NULL;
649 }
650 } else {
651 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
652 MutexLockerEx x(Heap_lock);
653 *gc_count_before_ret = total_collections();
654 return NULL;
655 }
656 // The GCLocker is either active or the GCLocker initiated
657 // GC has not yet been performed. Stall until it is and
658 // then retry the allocation.
659 GCLocker::stall_until_clear();
660 (*gclocker_retry_count_ret) += 1;
661 }
662
663 // We can reach here if we were unsuccessful in scheduling a
664 // collection (because another thread beat us to it) or if we were
665 // stalled due to the GC locker. In either can we should retry the
666 // allocation attempt in case another thread successfully
667 // performed a collection and reclaimed enough space. We do the
668 // first attempt (without holding the Heap_lock) here and the
669 // follow-on attempt will be at the start of the next loop
670 // iteration (after taking the Heap_lock).
671 result = _allocator->attempt_allocation(word_size, context);
672 if (result != NULL) {
673 return result;
674 }
675
676 // Give a warning if we seem to be looping forever.
677 if ((QueuedAllocationWarningCount > 0) &&
678 (try_count % QueuedAllocationWarningCount == 0)) {
679 warning("G1CollectedHeap::attempt_allocation_slow() "
680 "retries %d times", try_count);
681 }
682 }
683
684 ShouldNotReachHere();
685 return NULL;
686 }
687
688 void G1CollectedHeap::begin_archive_alloc_range() {
689 assert_at_safepoint(true /* should_be_vm_thread */);
690 if (_archive_allocator == NULL) {
691 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
692 }
693 }
694
695 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
696 // Allocations in archive regions cannot be of a size that would be considered
697 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
698 // may be different at archive-restore time.
699 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
700 }
701
702 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
703 assert_at_safepoint(true /* should_be_vm_thread */);
704 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
705 if (is_archive_alloc_too_large(word_size)) {
706 return NULL;
707 }
708 return _archive_allocator->archive_mem_allocate(word_size);
709 }
710
711 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
712 size_t end_alignment_in_bytes) {
713 assert_at_safepoint(true /* should_be_vm_thread */);
714 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
715
716 // Call complete_archive to do the real work, filling in the MemRegion
717 // array with the archive regions.
718 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
719 delete _archive_allocator;
720 _archive_allocator = NULL;
721 }
722
723 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
724 assert(ranges != NULL, "MemRegion array NULL");
725 assert(count != 0, "No MemRegions provided");
726 MemRegion reserved = _hrm.reserved();
727 for (size_t i = 0; i < count; i++) {
728 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
729 return false;
730 }
731 }
732 return true;
733 }
734
735 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
736 assert(!is_init_completed(), "Expect to be called at JVM init time");
737 assert(ranges != NULL, "MemRegion array NULL");
738 assert(count != 0, "No MemRegions provided");
739 MutexLockerEx x(Heap_lock);
740
741 MemRegion reserved = _hrm.reserved();
742 HeapWord* prev_last_addr = NULL;
743 HeapRegion* prev_last_region = NULL;
744
745 // Temporarily disable pretouching of heap pages. This interface is used
746 // when mmap'ing archived heap data in, so pre-touching is wasted.
747 FlagSetting fs(AlwaysPreTouch, false);
748
749 // Enable archive object checking in G1MarkSweep. We have to let it know
750 // about each archive range, so that objects in those ranges aren't marked.
751 G1MarkSweep::enable_archive_object_check();
752
753 // For each specified MemRegion range, allocate the corresponding G1
754 // regions and mark them as archive regions. We expect the ranges in
755 // ascending starting address order, without overlap.
756 for (size_t i = 0; i < count; i++) {
757 MemRegion curr_range = ranges[i];
758 HeapWord* start_address = curr_range.start();
759 size_t word_size = curr_range.word_size();
760 HeapWord* last_address = curr_range.last();
761 size_t commits = 0;
762
763 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
764 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
765 p2i(start_address), p2i(last_address));
766 guarantee(start_address > prev_last_addr,
767 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
768 p2i(start_address), p2i(prev_last_addr));
769 prev_last_addr = last_address;
770
771 // Check for ranges that start in the same G1 region in which the previous
772 // range ended, and adjust the start address so we don't try to allocate
773 // the same region again. If the current range is entirely within that
774 // region, skip it, just adjusting the recorded top.
775 HeapRegion* start_region = _hrm.addr_to_region(start_address);
776 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
777 start_address = start_region->end();
778 if (start_address > last_address) {
779 increase_used(word_size * HeapWordSize);
780 start_region->set_top(last_address + 1);
781 continue;
782 }
783 start_region->set_top(start_address);
784 curr_range = MemRegion(start_address, last_address + 1);
785 start_region = _hrm.addr_to_region(start_address);
786 }
787
788 // Perform the actual region allocation, exiting if it fails.
789 // Then note how much new space we have allocated.
790 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
791 return false;
792 }
793 increase_used(word_size * HeapWordSize);
794 if (commits != 0) {
795 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
796 HeapRegion::GrainWords * HeapWordSize * commits);
797
798 }
799
800 // Mark each G1 region touched by the range as archive, add it to the old set,
801 // and set the allocation context and top.
802 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
803 HeapRegion* last_region = _hrm.addr_to_region(last_address);
804 prev_last_region = last_region;
805
806 while (curr_region != NULL) {
807 assert(curr_region->is_empty() && !curr_region->is_pinned(),
808 "Region already in use (index %u)", curr_region->hrm_index());
809 curr_region->set_allocation_context(AllocationContext::system());
810 curr_region->set_archive();
811 _hr_printer.alloc(curr_region);
812 _old_set.add(curr_region);
813 if (curr_region != last_region) {
814 curr_region->set_top(curr_region->end());
815 curr_region = _hrm.next_region_in_heap(curr_region);
816 } else {
817 curr_region->set_top(last_address + 1);
818 curr_region = NULL;
819 }
820 }
821
822 // Notify mark-sweep of the archive range.
823 G1MarkSweep::set_range_archive(curr_range, true);
824 }
825 return true;
826 }
827
828 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
829 assert(!is_init_completed(), "Expect to be called at JVM init time");
830 assert(ranges != NULL, "MemRegion array NULL");
831 assert(count != 0, "No MemRegions provided");
832 MemRegion reserved = _hrm.reserved();
833 HeapWord *prev_last_addr = NULL;
834 HeapRegion* prev_last_region = NULL;
835
836 // For each MemRegion, create filler objects, if needed, in the G1 regions
837 // that contain the address range. The address range actually within the
838 // MemRegion will not be modified. That is assumed to have been initialized
839 // elsewhere, probably via an mmap of archived heap data.
840 MutexLockerEx x(Heap_lock);
841 for (size_t i = 0; i < count; i++) {
842 HeapWord* start_address = ranges[i].start();
843 HeapWord* last_address = ranges[i].last();
844
845 assert(reserved.contains(start_address) && reserved.contains(last_address),
846 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
847 p2i(start_address), p2i(last_address));
848 assert(start_address > prev_last_addr,
849 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
850 p2i(start_address), p2i(prev_last_addr));
851
852 HeapRegion* start_region = _hrm.addr_to_region(start_address);
853 HeapRegion* last_region = _hrm.addr_to_region(last_address);
854 HeapWord* bottom_address = start_region->bottom();
855
856 // Check for a range beginning in the same region in which the
857 // previous one ended.
858 if (start_region == prev_last_region) {
859 bottom_address = prev_last_addr + 1;
860 }
861
862 // Verify that the regions were all marked as archive regions by
863 // alloc_archive_regions.
864 HeapRegion* curr_region = start_region;
865 while (curr_region != NULL) {
866 guarantee(curr_region->is_archive(),
867 "Expected archive region at index %u", curr_region->hrm_index());
868 if (curr_region != last_region) {
869 curr_region = _hrm.next_region_in_heap(curr_region);
870 } else {
871 curr_region = NULL;
872 }
873 }
874
875 prev_last_addr = last_address;
876 prev_last_region = last_region;
877
878 // Fill the memory below the allocated range with dummy object(s),
879 // if the region bottom does not match the range start, or if the previous
880 // range ended within the same G1 region, and there is a gap.
881 if (start_address != bottom_address) {
882 size_t fill_size = pointer_delta(start_address, bottom_address);
883 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
884 increase_used(fill_size * HeapWordSize);
885 }
886 }
887 }
888
889 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
890 uint* gc_count_before_ret,
891 uint* gclocker_retry_count_ret) {
892 assert_heap_not_locked_and_not_at_safepoint();
893 assert(!is_humongous(word_size), "attempt_allocation() should not "
894 "be called for humongous allocation requests");
895
896 AllocationContext_t context = AllocationContext::current();
897 HeapWord* result = _allocator->attempt_allocation(word_size, context);
898
899 if (result == NULL) {
900 result = attempt_allocation_slow(word_size,
901 context,
902 gc_count_before_ret,
903 gclocker_retry_count_ret);
904 }
905 assert_heap_not_locked();
906 if (result != NULL) {
907 dirty_young_block(result, word_size);
908 }
909 return result;
910 }
911
912 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
913 assert(!is_init_completed(), "Expect to be called at JVM init time");
914 assert(ranges != NULL, "MemRegion array NULL");
915 assert(count != 0, "No MemRegions provided");
916 MemRegion reserved = _hrm.reserved();
917 HeapWord* prev_last_addr = NULL;
918 HeapRegion* prev_last_region = NULL;
919 size_t size_used = 0;
920 size_t uncommitted_regions = 0;
921
922 // For each Memregion, free the G1 regions that constitute it, and
923 // notify mark-sweep that the range is no longer to be considered 'archive.'
924 MutexLockerEx x(Heap_lock);
925 for (size_t i = 0; i < count; i++) {
926 HeapWord* start_address = ranges[i].start();
927 HeapWord* last_address = ranges[i].last();
928
929 assert(reserved.contains(start_address) && reserved.contains(last_address),
930 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
931 p2i(start_address), p2i(last_address));
932 assert(start_address > prev_last_addr,
933 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
934 p2i(start_address), p2i(prev_last_addr));
935 size_used += ranges[i].byte_size();
936 prev_last_addr = last_address;
937
938 HeapRegion* start_region = _hrm.addr_to_region(start_address);
939 HeapRegion* last_region = _hrm.addr_to_region(last_address);
940
941 // Check for ranges that start in the same G1 region in which the previous
942 // range ended, and adjust the start address so we don't try to free
943 // the same region again. If the current range is entirely within that
944 // region, skip it.
945 if (start_region == prev_last_region) {
946 start_address = start_region->end();
947 if (start_address > last_address) {
948 continue;
949 }
950 start_region = _hrm.addr_to_region(start_address);
951 }
952 prev_last_region = last_region;
953
954 // After verifying that each region was marked as an archive region by
955 // alloc_archive_regions, set it free and empty and uncommit it.
956 HeapRegion* curr_region = start_region;
957 while (curr_region != NULL) {
958 guarantee(curr_region->is_archive(),
959 "Expected archive region at index %u", curr_region->hrm_index());
960 uint curr_index = curr_region->hrm_index();
961 _old_set.remove(curr_region);
962 curr_region->set_free();
963 curr_region->set_top(curr_region->bottom());
964 if (curr_region != last_region) {
965 curr_region = _hrm.next_region_in_heap(curr_region);
966 } else {
967 curr_region = NULL;
968 }
969 _hrm.shrink_at(curr_index, 1);
970 uncommitted_regions++;
971 }
972
973 // Notify mark-sweep that this is no longer an archive range.
974 G1MarkSweep::set_range_archive(ranges[i], false);
975 }
976
977 if (uncommitted_regions != 0) {
978 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
979 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
980 }
981 decrease_used(size_used);
982 }
983
984 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
985 uint* gc_count_before_ret,
986 uint* gclocker_retry_count_ret) {
987 // The structure of this method has a lot of similarities to
988 // attempt_allocation_slow(). The reason these two were not merged
989 // into a single one is that such a method would require several "if
990 // allocation is not humongous do this, otherwise do that"
991 // conditional paths which would obscure its flow. In fact, an early
992 // version of this code did use a unified method which was harder to
993 // follow and, as a result, it had subtle bugs that were hard to
994 // track down. So keeping these two methods separate allows each to
995 // be more readable. It will be good to keep these two in sync as
996 // much as possible.
997
998 assert_heap_not_locked_and_not_at_safepoint();
999 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1000 "should only be called for humongous allocations");
1001
1002 // Humongous objects can exhaust the heap quickly, so we should check if we
1003 // need to start a marking cycle at each humongous object allocation. We do
1004 // the check before we do the actual allocation. The reason for doing it
1005 // before the allocation is that we avoid having to keep track of the newly
1006 // allocated memory while we do a GC.
1007 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1008 word_size)) {
1009 collect(GCCause::_g1_humongous_allocation);
1010 }
1011
1012 // We will loop until a) we manage to successfully perform the
1013 // allocation or b) we successfully schedule a collection which
1014 // fails to perform the allocation. b) is the only case when we'll
1015 // return NULL.
1016 HeapWord* result = NULL;
1017 for (int try_count = 1; /* we'll return */; try_count += 1) {
1018 bool should_try_gc;
1019 uint gc_count_before;
1020
1021 {
1022 MutexLockerEx x(Heap_lock);
1023
1024 // Given that humongous objects are not allocated in young
1025 // regions, we'll first try to do the allocation without doing a
1026 // collection hoping that there's enough space in the heap.
1027 result = humongous_obj_allocate(word_size, AllocationContext::current());
1028 if (result != NULL) {
1029 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1030 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1031 return result;
1032 }
1033
1034 if (GCLocker::is_active_and_needs_gc()) {
1035 should_try_gc = false;
1036 } else {
1037 // The GCLocker may not be active but the GCLocker initiated
1038 // GC may not yet have been performed (GCLocker::needs_gc()
1039 // returns true). In this case we do not try this GC and
1040 // wait until the GCLocker initiated GC is performed, and
1041 // then retry the allocation.
1042 if (GCLocker::needs_gc()) {
1043 should_try_gc = false;
1044 } else {
1045 // Read the GC count while still holding the Heap_lock.
1046 gc_count_before = total_collections();
1047 should_try_gc = true;
1048 }
1049 }
1050 }
1051
1052 if (should_try_gc) {
1053 // If we failed to allocate the humongous object, we should try to
1054 // do a collection pause (if we're allowed) in case it reclaims
1055 // enough space for the allocation to succeed after the pause.
1056
1057 bool succeeded;
1058 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1059 GCCause::_g1_humongous_allocation);
1060 if (result != NULL) {
1061 assert(succeeded, "only way to get back a non-NULL result");
1062 return result;
1063 }
1064
1065 if (succeeded) {
1066 // If we get here we successfully scheduled a collection which
1067 // failed to allocate. No point in trying to allocate
1068 // further. We'll just return NULL.
1069 MutexLockerEx x(Heap_lock);
1070 *gc_count_before_ret = total_collections();
1071 return NULL;
1072 }
1073 } else {
1074 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1075 MutexLockerEx x(Heap_lock);
1076 *gc_count_before_ret = total_collections();
1077 return NULL;
1078 }
1079 // The GCLocker is either active or the GCLocker initiated
1080 // GC has not yet been performed. Stall until it is and
1081 // then retry the allocation.
1082 GCLocker::stall_until_clear();
1083 (*gclocker_retry_count_ret) += 1;
1084 }
1085
1086 // We can reach here if we were unsuccessful in scheduling a
1087 // collection (because another thread beat us to it) or if we were
1088 // stalled due to the GC locker. In either can we should retry the
1089 // allocation attempt in case another thread successfully
1090 // performed a collection and reclaimed enough space. Give a
1091 // warning if we seem to be looping forever.
1092
1093 if ((QueuedAllocationWarningCount > 0) &&
1094 (try_count % QueuedAllocationWarningCount == 0)) {
1095 warning("G1CollectedHeap::attempt_allocation_humongous() "
1096 "retries %d times", try_count);
1097 }
1098 }
1099
1100 ShouldNotReachHere();
1101 return NULL;
1102 }
1103
1104 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1105 AllocationContext_t context,
1106 bool expect_null_mutator_alloc_region) {
1107 assert_at_safepoint(true /* should_be_vm_thread */);
1108 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1109 "the current alloc region was unexpectedly found to be non-NULL");
1110
1111 if (!is_humongous(word_size)) {
1112 return _allocator->attempt_allocation_locked(word_size, context);
1113 } else {
1114 HeapWord* result = humongous_obj_allocate(word_size, context);
1115 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1116 collector_state()->set_initiate_conc_mark_if_possible(true);
1117 }
1118 return result;
1119 }
1120
1121 ShouldNotReachHere();
1122 }
1123
1124 class PostMCRemSetClearClosure: public HeapRegionClosure {
1125 G1CollectedHeap* _g1h;
1126 ModRefBarrierSet* _mr_bs;
1127 public:
1128 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1129 _g1h(g1h), _mr_bs(mr_bs) {}
1130
1131 void doHeapRegion(HeapRegion* r) {
1132 HeapRegionRemSet* hrrs = r->rem_set();
1133
1134 _g1h->reset_gc_time_stamps(r);
1135
1136 if (r->is_continues_humongous()) {
1137 // We'll assert that the strong code root list and RSet is empty
1138 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1139 assert(hrrs->occupied() == 0, "RSet should be empty");
1140 } else {
1141 hrrs->clear();
1142 }
1143 // You might think here that we could clear just the cards
1144 // corresponding to the used region. But no: if we leave a dirty card
1145 // in a region we might allocate into, then it would prevent that card
1146 // from being enqueued, and cause it to be missed.
1147 // Re: the performance cost: we shouldn't be doing full GC anyway!
1148 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1149 }
1150 };
1151
1152 void G1CollectedHeap::clear_rsets_post_compaction() {
1153 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1154 heap_region_iterate(&rs_clear);
1155 }
1156
1157 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1158 G1CollectedHeap* _g1h;
1159 UpdateRSOopClosure _cl;
1160 public:
1161 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1162 _cl(g1->g1_rem_set(), worker_i),
1163 _g1h(g1)
1164 { }
1165
1166 void doHeapRegion(HeapRegion* r) {
1167 if (!r->is_continues_humongous()) {
1168 _cl.set_from(r);
1169 r->oop_iterate(&_cl);
1170 }
1171 }
1172 };
1173
1174 class ParRebuildRSTask: public AbstractGangTask {
1175 G1CollectedHeap* _g1;
1176 HeapRegionClaimer _hrclaimer;
1177
1178 public:
1179 ParRebuildRSTask(G1CollectedHeap* g1) :
1180 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1181
1182 void work(uint worker_id) {
1183 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1184 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1185 }
1186 };
1187
1188 class PostCompactionPrinterClosure: public HeapRegionClosure {
1189 private:
1190 G1HRPrinter* _hr_printer;
1191 public:
1192 void doHeapRegion(HeapRegion* hr) {
1193 assert(!hr->is_young(), "not expecting to find young regions");
1194 _hr_printer->post_compaction(hr);
1195 }
1196
1197 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1198 : _hr_printer(hr_printer) { }
1199 };
1200
1201 void G1CollectedHeap::print_hrm_post_compaction() {
1202 if (_hr_printer.is_active()) {
1203 PostCompactionPrinterClosure cl(hr_printer());
1204 heap_region_iterate(&cl);
1205 }
1206
1207 }
1208
1209 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1210 bool clear_all_soft_refs) {
1211 assert_at_safepoint(true /* should_be_vm_thread */);
1212
1213 if (GCLocker::check_active_before_gc()) {
1214 return false;
1215 }
1216
1217 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1218 gc_timer->register_gc_start();
1219
1220 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1221 GCIdMark gc_id_mark;
1222 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1223
1224 SvcGCMarker sgcm(SvcGCMarker::FULL);
1225 ResourceMark rm;
1226
1227 print_heap_before_gc();
1228 trace_heap_before_gc(gc_tracer);
1229
1230 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1231
1232 _verifier->verify_region_sets_optional();
1233
1234 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1235 collector_policy()->should_clear_all_soft_refs();
1236
1237 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1238
1239 {
1240 IsGCActiveMark x;
1241
1242 // Timing
1243 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1244 GCTraceCPUTime tcpu;
1245
1246 {
1247 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1248 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1249 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1250
1251 G1HeapTransition heap_transition(this);
1252 g1_policy()->record_full_collection_start();
1253
1254 // Note: When we have a more flexible GC logging framework that
1255 // allows us to add optional attributes to a GC log record we
1256 // could consider timing and reporting how long we wait in the
1257 // following two methods.
1258 wait_while_free_regions_coming();
1259 // If we start the compaction before the CM threads finish
1260 // scanning the root regions we might trip them over as we'll
1261 // be moving objects / updating references. So let's wait until
1262 // they are done. By telling them to abort, they should complete
1263 // early.
1264 _cm->root_regions()->abort();
1265 _cm->root_regions()->wait_until_scan_finished();
1266 append_secondary_free_list_if_not_empty_with_lock();
1267
1268 gc_prologue(true);
1269 increment_total_collections(true /* full gc */);
1270 increment_old_marking_cycles_started();
1271
1272 assert(used() == recalculate_used(), "Should be equal");
1273
1274 _verifier->verify_before_gc();
1275
1276 _verifier->check_bitmaps("Full GC Start");
1277 pre_full_gc_dump(gc_timer);
1278
1279 #if defined(COMPILER2) || INCLUDE_JVMCI
1280 DerivedPointerTable::clear();
1281 #endif
1282
1283 // Disable discovery and empty the discovered lists
1284 // for the CM ref processor.
1285 ref_processor_cm()->disable_discovery();
1286 ref_processor_cm()->abandon_partial_discovery();
1287 ref_processor_cm()->verify_no_references_recorded();
1288
1289 // Abandon current iterations of concurrent marking and concurrent
1290 // refinement, if any are in progress.
1291 concurrent_mark()->abort();
1292
1293 // Make sure we'll choose a new allocation region afterwards.
1294 _allocator->release_mutator_alloc_region();
1295 _allocator->abandon_gc_alloc_regions();
1296 g1_rem_set()->cleanupHRRS();
1297
1298 // We may have added regions to the current incremental collection
1299 // set between the last GC or pause and now. We need to clear the
1300 // incremental collection set and then start rebuilding it afresh
1301 // after this full GC.
1302 abandon_collection_set(collection_set()->inc_head());
1303 collection_set()->clear_incremental();
1304 collection_set()->stop_incremental_building();
1305
1306 tear_down_region_sets(false /* free_list_only */);
1307 collector_state()->set_gcs_are_young(true);
1308
1309 // See the comments in g1CollectedHeap.hpp and
1310 // G1CollectedHeap::ref_processing_init() about
1311 // how reference processing currently works in G1.
1312
1313 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1314 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1315
1316 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1317 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1318
1319 ref_processor_stw()->enable_discovery();
1320 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1321
1322 // Do collection work
1323 {
1324 HandleMark hm; // Discard invalid handles created during gc
1325 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1326 }
1327
1328 assert(num_free_regions() == 0, "we should not have added any free regions");
1329 rebuild_region_sets(false /* free_list_only */);
1330
1331 // Enqueue any discovered reference objects that have
1332 // not been removed from the discovered lists.
1333 ref_processor_stw()->enqueue_discovered_references();
1334
1335 #if defined(COMPILER2) || INCLUDE_JVMCI
1336 DerivedPointerTable::update_pointers();
1337 #endif
1338
1339 MemoryService::track_memory_usage();
1340
1341 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1342 ref_processor_stw()->verify_no_references_recorded();
1343
1344 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1345 ClassLoaderDataGraph::purge();
1346 MetaspaceAux::verify_metrics();
1347
1348 // Note: since we've just done a full GC, concurrent
1349 // marking is no longer active. Therefore we need not
1350 // re-enable reference discovery for the CM ref processor.
1351 // That will be done at the start of the next marking cycle.
1352 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1353 ref_processor_cm()->verify_no_references_recorded();
1354
1355 reset_gc_time_stamp();
1356 // Since everything potentially moved, we will clear all remembered
1357 // sets, and clear all cards. Later we will rebuild remembered
1358 // sets. We will also reset the GC time stamps of the regions.
1359 clear_rsets_post_compaction();
1360 check_gc_time_stamps();
1361
1362 resize_if_necessary_after_full_collection();
1363
1364 // We should do this after we potentially resize the heap so
1365 // that all the COMMIT / UNCOMMIT events are generated before
1366 // the compaction events.
1367 print_hrm_post_compaction();
1368
1369 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1370 if (hot_card_cache->use_cache()) {
1371 hot_card_cache->reset_card_counts();
1372 hot_card_cache->reset_hot_cache();
1373 }
1374
1375 // Rebuild remembered sets of all regions.
1376 uint n_workers =
1377 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1378 workers()->active_workers(),
1379 Threads::number_of_non_daemon_threads());
1380 workers()->set_active_workers(n_workers);
1381
1382 ParRebuildRSTask rebuild_rs_task(this);
1383 workers()->run_task(&rebuild_rs_task);
1384
1385 // Rebuild the strong code root lists for each region
1386 rebuild_strong_code_roots();
1387
1388 if (true) { // FIXME
1389 MetaspaceGC::compute_new_size();
1390 }
1391
1392 #ifdef TRACESPINNING
1393 ParallelTaskTerminator::print_termination_counts();
1394 #endif
1395
1396 // Discard all rset updates
1397 JavaThread::dirty_card_queue_set().abandon_logs();
1398 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1399
1400 // At this point there should be no regions in the
1401 // entire heap tagged as young.
1402 assert(check_young_list_empty(true /* check_heap */),
1403 "young list should be empty at this point");
1404
1405 // Update the number of full collections that have been completed.
1406 increment_old_marking_cycles_completed(false /* concurrent */);
1407
1408 _hrm.verify_optional();
1409 _verifier->verify_region_sets_optional();
1410
1411 _verifier->verify_after_gc();
1412
1413 // Clear the previous marking bitmap, if needed for bitmap verification.
1414 // Note we cannot do this when we clear the next marking bitmap in
1415 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1416 // objects marked during a full GC against the previous bitmap.
1417 // But we need to clear it before calling check_bitmaps below since
1418 // the full GC has compacted objects and updated TAMS but not updated
1419 // the prev bitmap.
1420 if (G1VerifyBitmaps) {
1421 ((G1CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1422 }
1423 _verifier->check_bitmaps("Full GC End");
1424
1425 // Start a new incremental collection set for the next pause
1426 assert(collection_set()->head() == NULL, "must be");
1427 collection_set()->start_incremental_building();
1428
1429 clear_cset_fast_test();
1430
1431 _allocator->init_mutator_alloc_region();
1432
1433 g1_policy()->record_full_collection_end();
1434
1435 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1436 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1437 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1438 // before any GC notifications are raised.
1439 g1mm()->update_sizes();
1440
1441 gc_epilogue(true);
1442
1443 heap_transition.print();
1444
1445 print_heap_after_gc();
1446 trace_heap_after_gc(gc_tracer);
1447
1448 post_full_gc_dump(gc_timer);
1449 }
1450
1451 gc_timer->register_gc_end();
1452 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1453 }
1454
1455 return true;
1456 }
1457
1458 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1459 // Currently, there is no facility in the do_full_collection(bool) API to notify
1460 // the caller that the collection did not succeed (e.g., because it was locked
1461 // out by the GC locker). So, right now, we'll ignore the return value.
1462 bool dummy = do_full_collection(true, /* explicit_gc */
1463 clear_all_soft_refs);
1464 }
1465
1466 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1467 // Include bytes that will be pre-allocated to support collections, as "used".
1468 const size_t used_after_gc = used();
1469 const size_t capacity_after_gc = capacity();
1470 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1471
1472 // This is enforced in arguments.cpp.
1473 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1474 "otherwise the code below doesn't make sense");
1475
1476 // We don't have floating point command-line arguments
1477 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1478 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1479 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1480 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1481
1482 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1483 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1484
1485 // We have to be careful here as these two calculations can overflow
1486 // 32-bit size_t's.
1487 double used_after_gc_d = (double) used_after_gc;
1488 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1489 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1490
1491 // Let's make sure that they are both under the max heap size, which
1492 // by default will make them fit into a size_t.
1493 double desired_capacity_upper_bound = (double) max_heap_size;
1494 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1495 desired_capacity_upper_bound);
1496 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1497 desired_capacity_upper_bound);
1498
1499 // We can now safely turn them into size_t's.
1500 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1501 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1502
1503 // This assert only makes sense here, before we adjust them
1504 // with respect to the min and max heap size.
1505 assert(minimum_desired_capacity <= maximum_desired_capacity,
1506 "minimum_desired_capacity = " SIZE_FORMAT ", "
1507 "maximum_desired_capacity = " SIZE_FORMAT,
1508 minimum_desired_capacity, maximum_desired_capacity);
1509
1510 // Should not be greater than the heap max size. No need to adjust
1511 // it with respect to the heap min size as it's a lower bound (i.e.,
1512 // we'll try to make the capacity larger than it, not smaller).
1513 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1514 // Should not be less than the heap min size. No need to adjust it
1515 // with respect to the heap max size as it's an upper bound (i.e.,
1516 // we'll try to make the capacity smaller than it, not greater).
1517 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1518
1519 if (capacity_after_gc < minimum_desired_capacity) {
1520 // Don't expand unless it's significant
1521 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1522
1523 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1524 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1525 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1526
1527 expand(expand_bytes);
1528
1529 // No expansion, now see if we want to shrink
1530 } else if (capacity_after_gc > maximum_desired_capacity) {
1531 // Capacity too large, compute shrinking size
1532 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1533
1534 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1535 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1536 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1537
1538 shrink(shrink_bytes);
1539 }
1540 }
1541
1542 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1543 AllocationContext_t context,
1544 bool do_gc,
1545 bool clear_all_soft_refs,
1546 bool expect_null_mutator_alloc_region,
1547 bool* gc_succeeded) {
1548 *gc_succeeded = true;
1549 // Let's attempt the allocation first.
1550 HeapWord* result =
1551 attempt_allocation_at_safepoint(word_size,
1552 context,
1553 expect_null_mutator_alloc_region);
1554 if (result != NULL) {
1555 assert(*gc_succeeded, "sanity");
1556 return result;
1557 }
1558
1559 // In a G1 heap, we're supposed to keep allocation from failing by
1560 // incremental pauses. Therefore, at least for now, we'll favor
1561 // expansion over collection. (This might change in the future if we can
1562 // do something smarter than full collection to satisfy a failed alloc.)
1563 result = expand_and_allocate(word_size, context);
1564 if (result != NULL) {
1565 assert(*gc_succeeded, "sanity");
1566 return result;
1567 }
1568
1569 if (do_gc) {
1570 // Expansion didn't work, we'll try to do a Full GC.
1571 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1572 clear_all_soft_refs);
1573 }
1574
1575 return NULL;
1576 }
1577
1578 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1579 AllocationContext_t context,
1580 bool* succeeded) {
1581 assert_at_safepoint(true /* should_be_vm_thread */);
1582
1583 // Attempts to allocate followed by Full GC.
1584 HeapWord* result =
1585 satisfy_failed_allocation_helper(word_size,
1586 context,
1587 true, /* do_gc */
1588 false, /* clear_all_soft_refs */
1589 false, /* expect_null_mutator_alloc_region */
1590 succeeded);
1591
1592 if (result != NULL || !*succeeded) {
1593 return result;
1594 }
1595
1596 // Attempts to allocate followed by Full GC that will collect all soft references.
1597 result = satisfy_failed_allocation_helper(word_size,
1598 context,
1599 true, /* do_gc */
1600 true, /* clear_all_soft_refs */
1601 true, /* expect_null_mutator_alloc_region */
1602 succeeded);
1603
1604 if (result != NULL || !*succeeded) {
1605 return result;
1606 }
1607
1608 // Attempts to allocate, no GC
1609 result = satisfy_failed_allocation_helper(word_size,
1610 context,
1611 false, /* do_gc */
1612 false, /* clear_all_soft_refs */
1613 true, /* expect_null_mutator_alloc_region */
1614 succeeded);
1615
1616 if (result != NULL) {
1617 assert(*succeeded, "sanity");
1618 return result;
1619 }
1620
1621 assert(!collector_policy()->should_clear_all_soft_refs(),
1622 "Flag should have been handled and cleared prior to this point");
1623
1624 // What else? We might try synchronous finalization later. If the total
1625 // space available is large enough for the allocation, then a more
1626 // complete compaction phase than we've tried so far might be
1627 // appropriate.
1628 assert(*succeeded, "sanity");
1629 return NULL;
1630 }
1631
1632 // Attempting to expand the heap sufficiently
1633 // to support an allocation of the given "word_size". If
1634 // successful, perform the allocation and return the address of the
1635 // allocated block, or else "NULL".
1636
1637 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1638 assert_at_safepoint(true /* should_be_vm_thread */);
1639
1640 _verifier->verify_region_sets_optional();
1641
1642 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1643 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1644 word_size * HeapWordSize);
1645
1646
1647 if (expand(expand_bytes)) {
1648 _hrm.verify_optional();
1649 _verifier->verify_region_sets_optional();
1650 return attempt_allocation_at_safepoint(word_size,
1651 context,
1652 false /* expect_null_mutator_alloc_region */);
1653 }
1654 return NULL;
1655 }
1656
1657 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1658 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1659 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1660 HeapRegion::GrainBytes);
1661
1662 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1663 expand_bytes, aligned_expand_bytes);
1664
1665 if (is_maximal_no_gc()) {
1666 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1667 return false;
1668 }
1669
1670 double expand_heap_start_time_sec = os::elapsedTime();
1671 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1672 assert(regions_to_expand > 0, "Must expand by at least one region");
1673
1674 uint expanded_by = _hrm.expand_by(regions_to_expand);
1675 if (expand_time_ms != NULL) {
1676 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1677 }
1678
1679 if (expanded_by > 0) {
1680 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1681 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1682 g1_policy()->record_new_heap_size(num_regions());
1683 } else {
1684 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1685
1686 // The expansion of the virtual storage space was unsuccessful.
1687 // Let's see if it was because we ran out of swap.
1688 if (G1ExitOnExpansionFailure &&
1689 _hrm.available() >= regions_to_expand) {
1690 // We had head room...
1691 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1692 }
1693 }
1694 return regions_to_expand > 0;
1695 }
1696
1697 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1698 size_t aligned_shrink_bytes =
1699 ReservedSpace::page_align_size_down(shrink_bytes);
1700 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1701 HeapRegion::GrainBytes);
1702 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1703
1704 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1705 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1706
1707
1708 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1709 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1710 if (num_regions_removed > 0) {
1711 g1_policy()->record_new_heap_size(num_regions());
1712 } else {
1713 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1714 }
1715 }
1716
1717 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1718 _verifier->verify_region_sets_optional();
1719
1720 // We should only reach here at the end of a Full GC which means we
1721 // should not not be holding to any GC alloc regions. The method
1722 // below will make sure of that and do any remaining clean up.
1723 _allocator->abandon_gc_alloc_regions();
1724
1725 // Instead of tearing down / rebuilding the free lists here, we
1726 // could instead use the remove_all_pending() method on free_list to
1727 // remove only the ones that we need to remove.
1728 tear_down_region_sets(true /* free_list_only */);
1729 shrink_helper(shrink_bytes);
1730 rebuild_region_sets(true /* free_list_only */);
1731
1732 _hrm.verify_optional();
1733 _verifier->verify_region_sets_optional();
1734 }
1735
1736 // Public methods.
1737
1738 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1739 CollectedHeap(),
1740 _g1_policy(policy_),
1741 _collection_set(this),
1742 _dirty_card_queue_set(false),
1743 _is_alive_closure_cm(this),
1744 _is_alive_closure_stw(this),
1745 _ref_processor_cm(NULL),
1746 _ref_processor_stw(NULL),
1747 _bot(NULL),
1748 _cg1r(NULL),
1749 _g1mm(NULL),
1750 _refine_cte_cl(NULL),
1751 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1752 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1753 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1754 _humongous_reclaim_candidates(),
1755 _has_humongous_reclaim_candidates(false),
1756 _archive_allocator(NULL),
1757 _free_regions_coming(false),
1758 _young_list(new YoungList(this)),
1759 _gc_time_stamp(0),
1760 _summary_bytes_used(0),
1761 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1762 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1763 _expand_heap_after_alloc_failure(true),
1764 _old_marking_cycles_started(0),
1765 _old_marking_cycles_completed(0),
1766 _heap_summary_sent(false),
1767 _in_cset_fast_test(),
1768 _dirty_cards_region_list(NULL),
1769 _worker_cset_start_region(NULL),
1770 _worker_cset_start_region_time_stamp(NULL),
1771 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1772 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1773 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1774 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1775
1776 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1777 /* are_GC_task_threads */true,
1778 /* are_ConcurrentGC_threads */false);
1779 _workers->initialize_workers();
1780 _verifier = new G1HeapVerifier(this);
1781
1782 _allocator = G1Allocator::create_allocator(this);
1783 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1784
1785 // Override the default _filler_array_max_size so that no humongous filler
1786 // objects are created.
1787 _filler_array_max_size = _humongous_object_threshold_in_words;
1788
1789 uint n_queues = ParallelGCThreads;
1790 _task_queues = new RefToScanQueueSet(n_queues);
1791
1792 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1793 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1794 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1795
1796 for (uint i = 0; i < n_queues; i++) {
1797 RefToScanQueue* q = new RefToScanQueue();
1798 q->initialize();
1799 _task_queues->register_queue(i, q);
1800 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1801 }
1802 clear_cset_start_regions();
1803
1804 // Initialize the G1EvacuationFailureALot counters and flags.
1805 NOT_PRODUCT(reset_evacuation_should_fail();)
1806
1807 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1808 }
1809
1810 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1811 size_t size,
1812 size_t translation_factor) {
1813 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1814 // Allocate a new reserved space, preferring to use large pages.
1815 ReservedSpace rs(size, preferred_page_size);
1816 G1RegionToSpaceMapper* result =
1817 G1RegionToSpaceMapper::create_mapper(rs,
1818 size,
1819 rs.alignment(),
1820 HeapRegion::GrainBytes,
1821 translation_factor,
1822 mtGC);
1823 if (TracePageSizes) {
1824 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1825 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1826 }
1827 return result;
1828 }
1829
1830 jint G1CollectedHeap::initialize() {
1831 CollectedHeap::pre_initialize();
1832 os::enable_vtime();
1833
1834 // Necessary to satisfy locking discipline assertions.
1835
1836 MutexLocker x(Heap_lock);
1837
1838 // While there are no constraints in the GC code that HeapWordSize
1839 // be any particular value, there are multiple other areas in the
1840 // system which believe this to be true (e.g. oop->object_size in some
1841 // cases incorrectly returns the size in wordSize units rather than
1842 // HeapWordSize).
1843 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1844
1845 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1846 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1847 size_t heap_alignment = collector_policy()->heap_alignment();
1848
1849 // Ensure that the sizes are properly aligned.
1850 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1851 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1852 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1853
1854 _refine_cte_cl = new RefineCardTableEntryClosure();
1855
1856 jint ecode = JNI_OK;
1857 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1858 if (_cg1r == NULL) {
1859 return ecode;
1860 }
1861
1862 // Reserve the maximum.
1863
1864 // When compressed oops are enabled, the preferred heap base
1865 // is calculated by subtracting the requested size from the
1866 // 32Gb boundary and using the result as the base address for
1867 // heap reservation. If the requested size is not aligned to
1868 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1869 // into the ReservedHeapSpace constructor) then the actual
1870 // base of the reserved heap may end up differing from the
1871 // address that was requested (i.e. the preferred heap base).
1872 // If this happens then we could end up using a non-optimal
1873 // compressed oops mode.
1874
1875 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1876 heap_alignment);
1877
1878 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1879
1880 // Create the barrier set for the entire reserved region.
1881 G1SATBCardTableLoggingModRefBS* bs
1882 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1883 bs->initialize();
1884 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1885 set_barrier_set(bs);
1886
1887 // Also create a G1 rem set.
1888 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1889
1890 // Carve out the G1 part of the heap.
1891 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1892 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1893 G1RegionToSpaceMapper* heap_storage =
1894 G1RegionToSpaceMapper::create_mapper(g1_rs,
1895 g1_rs.size(),
1896 page_size,
1897 HeapRegion::GrainBytes,
1898 1,
1899 mtJavaHeap);
1900 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1901 max_byte_size, page_size,
1902 heap_rs.base(),
1903 heap_rs.size());
1904 heap_storage->set_mapping_changed_listener(&_listener);
1905
1906 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1907 G1RegionToSpaceMapper* bot_storage =
1908 create_aux_memory_mapper("Block offset table",
1909 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1910 G1BlockOffsetTable::heap_map_factor());
1911
1912 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1913 G1RegionToSpaceMapper* cardtable_storage =
1914 create_aux_memory_mapper("Card table",
1915 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1916 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1917
1918 G1RegionToSpaceMapper* card_counts_storage =
1919 create_aux_memory_mapper("Card counts table",
1920 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1921 G1CardCounts::heap_map_factor());
1922
1923 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1924 G1RegionToSpaceMapper* prev_bitmap_storage =
1925 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1926 G1RegionToSpaceMapper* next_bitmap_storage =
1927 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1928
1929 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1930 g1_barrier_set()->initialize(cardtable_storage);
1931 // Do later initialization work for concurrent refinement.
1932 _cg1r->init(card_counts_storage);
1933
1934 // 6843694 - ensure that the maximum region index can fit
1935 // in the remembered set structures.
1936 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1937 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1938
1939 G1RemSet::initialize(max_regions());
1940
1941 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1942 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1943 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1944 "too many cards per region");
1945
1946 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1947
1948 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1949
1950 {
1951 HeapWord* start = _hrm.reserved().start();
1952 HeapWord* end = _hrm.reserved().end();
1953 size_t granularity = HeapRegion::GrainBytes;
1954
1955 _in_cset_fast_test.initialize(start, end, granularity);
1956 _humongous_reclaim_candidates.initialize(start, end, granularity);
1957 }
1958
1959 // Create the G1ConcurrentMark data structure and thread.
1960 // (Must do this late, so that "max_regions" is defined.)
1961 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1962 if (_cm == NULL || !_cm->completed_initialization()) {
1963 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1964 return JNI_ENOMEM;
1965 }
1966 _cmThread = _cm->cmThread();
1967
1968 // Now expand into the initial heap size.
1969 if (!expand(init_byte_size)) {
1970 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1971 return JNI_ENOMEM;
1972 }
1973
1974 // Perform any initialization actions delegated to the policy.
1975 g1_policy()->init();
1976
1977 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1978 SATB_Q_FL_lock,
1979 G1SATBProcessCompletedThreshold,
1980 Shared_SATB_Q_lock);
1981
1982 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1983 DirtyCardQ_CBL_mon,
1984 DirtyCardQ_FL_lock,
1985 (int)concurrent_g1_refine()->yellow_zone(),
1986 (int)concurrent_g1_refine()->red_zone(),
1987 Shared_DirtyCardQ_lock,
1988 NULL, // fl_owner
1989 true); // init_free_ids
1990
1991 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1992 DirtyCardQ_CBL_mon,
1993 DirtyCardQ_FL_lock,
1994 -1, // never trigger processing
1995 -1, // no limit on length
1996 Shared_DirtyCardQ_lock,
1997 &JavaThread::dirty_card_queue_set());
1998
1999 // Here we allocate the dummy HeapRegion that is required by the
2000 // G1AllocRegion class.
2001 HeapRegion* dummy_region = _hrm.get_dummy_region();
2002
2003 // We'll re-use the same region whether the alloc region will
2004 // require BOT updates or not and, if it doesn't, then a non-young
2005 // region will complain that it cannot support allocations without
2006 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2007 dummy_region->set_eden();
2008 // Make sure it's full.
2009 dummy_region->set_top(dummy_region->end());
2010 G1AllocRegion::setup(this, dummy_region);
2011
2012 _allocator->init_mutator_alloc_region();
2013
2014 // Do create of the monitoring and management support so that
2015 // values in the heap have been properly initialized.
2016 _g1mm = new G1MonitoringSupport(this);
2017
2018 G1StringDedup::initialize();
2019
2020 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2021 for (uint i = 0; i < ParallelGCThreads; i++) {
2022 new (&_preserved_objs[i]) OopAndMarkOopStack();
2023 }
2024
2025 return JNI_OK;
2026 }
2027
2028 void G1CollectedHeap::stop() {
2029 // Stop all concurrent threads. We do this to make sure these threads
2030 // do not continue to execute and access resources (e.g. logging)
2031 // that are destroyed during shutdown.
2032 _cg1r->stop();
2033 _cmThread->stop();
2034 if (G1StringDedup::is_enabled()) {
2035 G1StringDedup::stop();
2036 }
2037 }
2038
2039 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2040 return HeapRegion::max_region_size();
2041 }
2042
2043 void G1CollectedHeap::post_initialize() {
2044 CollectedHeap::post_initialize();
2045 ref_processing_init();
2046 }
2047
2048 void G1CollectedHeap::ref_processing_init() {
2049 // Reference processing in G1 currently works as follows:
2050 //
2051 // * There are two reference processor instances. One is
2052 // used to record and process discovered references
2053 // during concurrent marking; the other is used to
2054 // record and process references during STW pauses
2055 // (both full and incremental).
2056 // * Both ref processors need to 'span' the entire heap as
2057 // the regions in the collection set may be dotted around.
2058 //
2059 // * For the concurrent marking ref processor:
2060 // * Reference discovery is enabled at initial marking.
2061 // * Reference discovery is disabled and the discovered
2062 // references processed etc during remarking.
2063 // * Reference discovery is MT (see below).
2064 // * Reference discovery requires a barrier (see below).
2065 // * Reference processing may or may not be MT
2066 // (depending on the value of ParallelRefProcEnabled
2067 // and ParallelGCThreads).
2068 // * A full GC disables reference discovery by the CM
2069 // ref processor and abandons any entries on it's
2070 // discovered lists.
2071 //
2072 // * For the STW processor:
2073 // * Non MT discovery is enabled at the start of a full GC.
2074 // * Processing and enqueueing during a full GC is non-MT.
2075 // * During a full GC, references are processed after marking.
2076 //
2077 // * Discovery (may or may not be MT) is enabled at the start
2078 // of an incremental evacuation pause.
2079 // * References are processed near the end of a STW evacuation pause.
2080 // * For both types of GC:
2081 // * Discovery is atomic - i.e. not concurrent.
2082 // * Reference discovery will not need a barrier.
2083
2084 MemRegion mr = reserved_region();
2085
2086 // Concurrent Mark ref processor
2087 _ref_processor_cm =
2088 new ReferenceProcessor(mr, // span
2089 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2090 // mt processing
2091 ParallelGCThreads,
2092 // degree of mt processing
2093 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2094 // mt discovery
2095 MAX2(ParallelGCThreads, ConcGCThreads),
2096 // degree of mt discovery
2097 false,
2098 // Reference discovery is not atomic
2099 &_is_alive_closure_cm);
2100 // is alive closure
2101 // (for efficiency/performance)
2102
2103 // STW ref processor
2104 _ref_processor_stw =
2105 new ReferenceProcessor(mr, // span
2106 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2107 // mt processing
2108 ParallelGCThreads,
2109 // degree of mt processing
2110 (ParallelGCThreads > 1),
2111 // mt discovery
2112 ParallelGCThreads,
2113 // degree of mt discovery
2114 true,
2115 // Reference discovery is atomic
2116 &_is_alive_closure_stw);
2117 // is alive closure
2118 // (for efficiency/performance)
2119 }
2120
2121 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2122 return g1_policy();
2123 }
2124
2125 size_t G1CollectedHeap::capacity() const {
2126 return _hrm.length() * HeapRegion::GrainBytes;
2127 }
2128
2129 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2130 hr->reset_gc_time_stamp();
2131 }
2132
2133 #ifndef PRODUCT
2134
2135 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2136 private:
2137 unsigned _gc_time_stamp;
2138 bool _failures;
2139
2140 public:
2141 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2142 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2143
2144 virtual void doHeapRegion(HeapRegion* hr) {
2145 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2146 if (_gc_time_stamp != region_gc_time_stamp) {
2147 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2148 region_gc_time_stamp, _gc_time_stamp);
2149 _failures = true;
2150 }
2151 }
2152
2153 bool failures() { return _failures; }
2154 };
2155
2156 void G1CollectedHeap::check_gc_time_stamps() {
2157 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2158 heap_region_iterate(&cl);
2159 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2160 }
2161 #endif // PRODUCT
2162
2163 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2164 _cg1r->hot_card_cache()->drain(cl, worker_i);
2165 }
2166
2167 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2168 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2169 size_t n_completed_buffers = 0;
2170 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2171 n_completed_buffers++;
2172 }
2173 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2174 dcqs.clear_n_completed_buffers();
2175 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2176 }
2177
2178 // Computes the sum of the storage used by the various regions.
2179 size_t G1CollectedHeap::used() const {
2180 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2181 if (_archive_allocator != NULL) {
2182 result += _archive_allocator->used();
2183 }
2184 return result;
2185 }
2186
2187 size_t G1CollectedHeap::used_unlocked() const {
2188 return _summary_bytes_used;
2189 }
2190
2191 class SumUsedClosure: public HeapRegionClosure {
2192 size_t _used;
2193 public:
2194 SumUsedClosure() : _used(0) {}
2195 void doHeapRegion(HeapRegion* r) {
2196 _used += r->used();
2197 }
2198 size_t result() { return _used; }
2199 };
2200
2201 size_t G1CollectedHeap::recalculate_used() const {
2202 double recalculate_used_start = os::elapsedTime();
2203
2204 SumUsedClosure blk;
2205 heap_region_iterate(&blk);
2206
2207 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2208 return blk.result();
2209 }
2210
2211 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2212 switch (cause) {
2213 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2214 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2215 case GCCause::_update_allocation_context_stats_inc: return true;
2216 case GCCause::_wb_conc_mark: return true;
2217 default : return false;
2218 }
2219 }
2220
2221 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2222 switch (cause) {
2223 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2224 case GCCause::_g1_humongous_allocation: return true;
2225 default: return is_user_requested_concurrent_full_gc(cause);
2226 }
2227 }
2228
2229 #ifndef PRODUCT
2230 void G1CollectedHeap::allocate_dummy_regions() {
2231 // Let's fill up most of the region
2232 size_t word_size = HeapRegion::GrainWords - 1024;
2233 // And as a result the region we'll allocate will be humongous.
2234 guarantee(is_humongous(word_size), "sanity");
2235
2236 // _filler_array_max_size is set to humongous object threshold
2237 // but temporarily change it to use CollectedHeap::fill_with_object().
2238 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2239
2240 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2241 // Let's use the existing mechanism for the allocation
2242 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2243 AllocationContext::system());
2244 if (dummy_obj != NULL) {
2245 MemRegion mr(dummy_obj, word_size);
2246 CollectedHeap::fill_with_object(mr);
2247 } else {
2248 // If we can't allocate once, we probably cannot allocate
2249 // again. Let's get out of the loop.
2250 break;
2251 }
2252 }
2253 }
2254 #endif // !PRODUCT
2255
2256 void G1CollectedHeap::increment_old_marking_cycles_started() {
2257 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2258 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2259 "Wrong marking cycle count (started: %d, completed: %d)",
2260 _old_marking_cycles_started, _old_marking_cycles_completed);
2261
2262 _old_marking_cycles_started++;
2263 }
2264
2265 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2266 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2267
2268 // We assume that if concurrent == true, then the caller is a
2269 // concurrent thread that was joined the Suspendible Thread
2270 // Set. If there's ever a cheap way to check this, we should add an
2271 // assert here.
2272
2273 // Given that this method is called at the end of a Full GC or of a
2274 // concurrent cycle, and those can be nested (i.e., a Full GC can
2275 // interrupt a concurrent cycle), the number of full collections
2276 // completed should be either one (in the case where there was no
2277 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2278 // behind the number of full collections started.
2279
2280 // This is the case for the inner caller, i.e. a Full GC.
2281 assert(concurrent ||
2282 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2283 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2284 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2285 "is inconsistent with _old_marking_cycles_completed = %u",
2286 _old_marking_cycles_started, _old_marking_cycles_completed);
2287
2288 // This is the case for the outer caller, i.e. the concurrent cycle.
2289 assert(!concurrent ||
2290 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2291 "for outer caller (concurrent cycle): "
2292 "_old_marking_cycles_started = %u "
2293 "is inconsistent with _old_marking_cycles_completed = %u",
2294 _old_marking_cycles_started, _old_marking_cycles_completed);
2295
2296 _old_marking_cycles_completed += 1;
2297
2298 // We need to clear the "in_progress" flag in the CM thread before
2299 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2300 // is set) so that if a waiter requests another System.gc() it doesn't
2301 // incorrectly see that a marking cycle is still in progress.
2302 if (concurrent) {
2303 _cmThread->set_idle();
2304 }
2305
2306 // This notify_all() will ensure that a thread that called
2307 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2308 // and it's waiting for a full GC to finish will be woken up. It is
2309 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2310 FullGCCount_lock->notify_all();
2311 }
2312
2313 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2314 GCIdMarkAndRestore conc_gc_id_mark;
2315 collector_state()->set_concurrent_cycle_started(true);
2316 _gc_timer_cm->register_gc_start(start_time);
2317
2318 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2319 trace_heap_before_gc(_gc_tracer_cm);
2320 _cmThread->set_gc_id(GCId::current());
2321 }
2322
2323 void G1CollectedHeap::register_concurrent_cycle_end() {
2324 if (collector_state()->concurrent_cycle_started()) {
2325 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2326 if (_cm->has_aborted()) {
2327 _gc_tracer_cm->report_concurrent_mode_failure();
2328
2329 // ConcurrentGCTimer will be ended as well.
2330 _cm->register_concurrent_gc_end_and_stop_timer();
2331 } else {
2332 _gc_timer_cm->register_gc_end();
2333 }
2334
2335 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2336
2337 // Clear state variables to prepare for the next concurrent cycle.
2338 collector_state()->set_concurrent_cycle_started(false);
2339 _heap_summary_sent = false;
2340 }
2341 }
2342
2343 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2344 if (collector_state()->concurrent_cycle_started()) {
2345 // This function can be called when:
2346 // the cleanup pause is run
2347 // the concurrent cycle is aborted before the cleanup pause.
2348 // the concurrent cycle is aborted after the cleanup pause,
2349 // but before the concurrent cycle end has been registered.
2350 // Make sure that we only send the heap information once.
2351 if (!_heap_summary_sent) {
2352 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2353 trace_heap_after_gc(_gc_tracer_cm);
2354 _heap_summary_sent = true;
2355 }
2356 }
2357 }
2358
2359 void G1CollectedHeap::collect(GCCause::Cause cause) {
2360 assert_heap_not_locked();
2361
2362 uint gc_count_before;
2363 uint old_marking_count_before;
2364 uint full_gc_count_before;
2365 bool retry_gc;
2366
2367 do {
2368 retry_gc = false;
2369
2370 {
2371 MutexLocker ml(Heap_lock);
2372
2373 // Read the GC count while holding the Heap_lock
2374 gc_count_before = total_collections();
2375 full_gc_count_before = total_full_collections();
2376 old_marking_count_before = _old_marking_cycles_started;
2377 }
2378
2379 if (should_do_concurrent_full_gc(cause)) {
2380 // Schedule an initial-mark evacuation pause that will start a
2381 // concurrent cycle. We're setting word_size to 0 which means that
2382 // we are not requesting a post-GC allocation.
2383 VM_G1IncCollectionPause op(gc_count_before,
2384 0, /* word_size */
2385 true, /* should_initiate_conc_mark */
2386 g1_policy()->max_pause_time_ms(),
2387 cause);
2388 op.set_allocation_context(AllocationContext::current());
2389
2390 VMThread::execute(&op);
2391 if (!op.pause_succeeded()) {
2392 if (old_marking_count_before == _old_marking_cycles_started) {
2393 retry_gc = op.should_retry_gc();
2394 } else {
2395 // A Full GC happened while we were trying to schedule the
2396 // initial-mark GC. No point in starting a new cycle given
2397 // that the whole heap was collected anyway.
2398 }
2399
2400 if (retry_gc) {
2401 if (GCLocker::is_active_and_needs_gc()) {
2402 GCLocker::stall_until_clear();
2403 }
2404 }
2405 }
2406 } else {
2407 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2408 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2409
2410 // Schedule a standard evacuation pause. We're setting word_size
2411 // to 0 which means that we are not requesting a post-GC allocation.
2412 VM_G1IncCollectionPause op(gc_count_before,
2413 0, /* word_size */
2414 false, /* should_initiate_conc_mark */
2415 g1_policy()->max_pause_time_ms(),
2416 cause);
2417 VMThread::execute(&op);
2418 } else {
2419 // Schedule a Full GC.
2420 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2421 VMThread::execute(&op);
2422 }
2423 }
2424 } while (retry_gc);
2425 }
2426
2427 bool G1CollectedHeap::is_in(const void* p) const {
2428 if (_hrm.reserved().contains(p)) {
2429 // Given that we know that p is in the reserved space,
2430 // heap_region_containing() should successfully
2431 // return the containing region.
2432 HeapRegion* hr = heap_region_containing(p);
2433 return hr->is_in(p);
2434 } else {
2435 return false;
2436 }
2437 }
2438
2439 #ifdef ASSERT
2440 bool G1CollectedHeap::is_in_exact(const void* p) const {
2441 bool contains = reserved_region().contains(p);
2442 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2443 if (contains && available) {
2444 return true;
2445 } else {
2446 return false;
2447 }
2448 }
2449 #endif
2450
2451 bool G1CollectedHeap::obj_in_cs(oop obj) {
2452 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2453 return r != NULL && r->in_collection_set();
2454 }
2455
2456 // Iteration functions.
2457
2458 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2459
2460 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2461 ExtendedOopClosure* _cl;
2462 public:
2463 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2464 void doHeapRegion(HeapRegion* r) {
2465 if (!r->is_continues_humongous()) {
2466 r->oop_iterate(_cl);
2467 }
2468 }
2469 };
2470
2471 // Iterates an ObjectClosure over all objects within a HeapRegion.
2472
2473 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2474 ObjectClosure* _cl;
2475 public:
2476 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2477 void doHeapRegion(HeapRegion* r) {
2478 if (!r->is_continues_humongous()) {
2479 r->object_iterate(_cl);
2480 }
2481 }
2482 };
2483
2484 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2485 IterateObjectClosureRegionClosure blk(cl);
2486 heap_region_iterate(&blk);
2487 }
2488
2489 void G1CollectedHeap::heap_region_iterate(AbortableHeapRegionClosure* cl) const {
2490 _hrm.iterate(cl);
2491 }
2492
2493 void
2494 G1CollectedHeap::heap_region_par_iterate(AbortableHeapRegionClosure* cl,
2495 uint worker_id,
2496 HeapRegionClaimer *hrclaimer,
2497 bool concurrent) const {
2498 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2499 }
2500
2501 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2502 _hrm.iterate(cl);
2503 }
2504
2505 void
2506 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2507 uint worker_id,
2508 HeapRegionClaimer *hrclaimer,
2509 bool concurrent) const {
2510 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2511 }
2512
2513 // Clear the cached CSet starting regions and (more importantly)
2514 // the time stamps. Called when we reset the GC time stamp.
2515 void G1CollectedHeap::clear_cset_start_regions() {
2516 assert(_worker_cset_start_region != NULL, "sanity");
2517 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2518
2519 for (uint i = 0; i < ParallelGCThreads; i++) {
2520 _worker_cset_start_region[i] = NULL;
2521 _worker_cset_start_region_time_stamp[i] = 0;
2522 }
2523 }
2524
2525 // Given the id of a worker, obtain or calculate a suitable
2526 // starting region for iterating over the current collection set.
2527 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2528 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2529
2530 HeapRegion* result = NULL;
2531 unsigned gc_time_stamp = get_gc_time_stamp();
2532
2533 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2534 // Cached starting region for current worker was set
2535 // during the current pause - so it's valid.
2536 // Note: the cached starting heap region may be NULL
2537 // (when the collection set is empty).
2538 result = _worker_cset_start_region[worker_i];
2539 assert(result == NULL || result->in_collection_set(), "sanity");
2540 return result;
2541 }
2542
2543 // The cached entry was not valid so let's calculate
2544 // a suitable starting heap region for this worker.
2545
2546 // We want the parallel threads to start their collection
2547 // set iteration at different collection set regions to
2548 // avoid contention.
2549 // If we have:
2550 // n collection set regions
2551 // p threads
2552 // Then thread t will start at region floor ((t * n) / p)
2553
2554 result = collection_set()->head();
2555 uint cs_size = collection_set()->region_length();
2556 uint active_workers = workers()->active_workers();
2557
2558 uint end_ind = (cs_size * worker_i) / active_workers;
2559 uint start_ind = 0;
2560
2561 if (worker_i > 0 &&
2562 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2563 // Previous workers starting region is valid
2564 // so let's iterate from there
2565 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2566 OrderAccess::loadload();
2567 result = _worker_cset_start_region[worker_i - 1];
2568 }
2569
2570 for (uint i = start_ind; i < end_ind; i++) {
2571 result = result->next_in_collection_set();
2572 }
2573
2574 // Note: the calculated starting heap region may be NULL
2575 // (when the collection set is empty).
2576 assert(result == NULL || result->in_collection_set(), "sanity");
2577 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2578 "should be updated only once per pause");
2579 _worker_cset_start_region[worker_i] = result;
2580 OrderAccess::storestore();
2581 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2582 return result;
2583 }
2584
2585 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2586 HeapRegion* r = collection_set()->head();
2587 while (r != NULL) {
2588 HeapRegion* next = r->next_in_collection_set();
2589 cl->doHeapRegion(r);
2590 r = next;
2591 }
2592 }
2593
2594 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2595 HeapRegionClosure *cl) {
2596 if (r == NULL) {
2597 // The CSet is empty so there's nothing to do.
2598 return;
2599 }
2600
2601 assert(r->in_collection_set(),
2602 "Start region must be a member of the collection set.");
2603 HeapRegion* cur = r;
2604 while (cur != NULL) {
2605 HeapRegion* next = cur->next_in_collection_set();
2606 cl->doHeapRegion(cur);
2607 cur = next;
2608 }
2609 cur = collection_set()->head();
2610 while (cur != r) {
2611 HeapRegion* next = cur->next_in_collection_set();
2612 cl->doHeapRegion(cur);
2613 cur = next;
2614 }
2615 }
2616
2617 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2618 HeapRegion* result = _hrm.next_region_in_heap(from);
2619 while (result != NULL && result->is_pinned()) {
2620 result = _hrm.next_region_in_heap(result);
2621 }
2622 return result;
2623 }
2624
2625 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2626 HeapRegion* hr = heap_region_containing(addr);
2627 return hr->block_start(addr);
2628 }
2629
2630 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2631 HeapRegion* hr = heap_region_containing(addr);
2632 return hr->block_size(addr);
2633 }
2634
2635 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2636 HeapRegion* hr = heap_region_containing(addr);
2637 return hr->block_is_obj(addr);
2638 }
2639
2640 bool G1CollectedHeap::supports_tlab_allocation() const {
2641 return true;
2642 }
2643
2644 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2645 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2646 }
2647
2648 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2649 return young_list()->eden_used_bytes();
2650 }
2651
2652 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2653 // must be equal to the humongous object limit.
2654 size_t G1CollectedHeap::max_tlab_size() const {
2655 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2656 }
2657
2658 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2659 AllocationContext_t context = AllocationContext::current();
2660 return _allocator->unsafe_max_tlab_alloc(context);
2661 }
2662
2663 size_t G1CollectedHeap::max_capacity() const {
2664 return _hrm.reserved().byte_size();
2665 }
2666
2667 jlong G1CollectedHeap::millis_since_last_gc() {
2668 // assert(false, "NYI");
2669 return 0;
2670 }
2671
2672 void G1CollectedHeap::prepare_for_verify() {
2673 _verifier->prepare_for_verify();
2674 }
2675
2676 void G1CollectedHeap::verify(VerifyOption vo) {
2677 _verifier->verify(vo);
2678 }
2679
2680 class PrintRegionClosure: public HeapRegionClosure {
2681 outputStream* _st;
2682 public:
2683 PrintRegionClosure(outputStream* st) : _st(st) {}
2684 void doHeapRegion(HeapRegion* r) {
2685 r->print_on(_st);
2686 }
2687 };
2688
2689 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2690 const HeapRegion* hr,
2691 const VerifyOption vo) const {
2692 switch (vo) {
2693 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2694 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2695 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2696 default: ShouldNotReachHere();
2697 }
2698 return false; // keep some compilers happy
2699 }
2700
2701 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2702 const VerifyOption vo) const {
2703 switch (vo) {
2704 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2705 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2706 case VerifyOption_G1UseMarkWord: {
2707 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2708 return !obj->is_gc_marked() && !hr->is_archive();
2709 }
2710 default: ShouldNotReachHere();
2711 }
2712 return false; // keep some compilers happy
2713 }
2714
2715 void G1CollectedHeap::print_on(outputStream* st) const {
2716 st->print(" %-20s", "garbage-first heap");
2717 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2718 capacity()/K, used_unlocked()/K);
2719 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2720 p2i(_hrm.reserved().start()),
2721 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2722 p2i(_hrm.reserved().end()));
2723 st->cr();
2724 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2725 uint young_regions = _young_list->length();
2726 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2727 (size_t) young_regions * HeapRegion::GrainBytes / K);
2728 uint survivor_regions = g1_policy()->recorded_survivor_regions();
2729 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2730 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2731 st->cr();
2732 MetaspaceAux::print_on(st);
2733 }
2734
2735 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2736 print_on(st);
2737
2738 // Print the per-region information.
2739 st->cr();
2740 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2741 "HS=humongous(starts), HC=humongous(continues), "
2742 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2743 "AC=allocation context, "
2744 "TAMS=top-at-mark-start (previous, next)");
2745 PrintRegionClosure blk(st);
2746 heap_region_iterate(&blk);
2747 }
2748
2749 void G1CollectedHeap::print_on_error(outputStream* st) const {
2750 this->CollectedHeap::print_on_error(st);
2751
2752 if (_cm != NULL) {
2753 st->cr();
2754 _cm->print_on_error(st);
2755 }
2756 }
2757
2758 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2759 workers()->print_worker_threads_on(st);
2760 _cmThread->print_on(st);
2761 st->cr();
2762 _cm->print_worker_threads_on(st);
2763 _cg1r->print_worker_threads_on(st);
2764 if (G1StringDedup::is_enabled()) {
2765 G1StringDedup::print_worker_threads_on(st);
2766 }
2767 }
2768
2769 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2770 workers()->threads_do(tc);
2771 tc->do_thread(_cmThread);
2772 _cg1r->threads_do(tc);
2773 if (G1StringDedup::is_enabled()) {
2774 G1StringDedup::threads_do(tc);
2775 }
2776 }
2777
2778 void G1CollectedHeap::print_tracing_info() const {
2779 g1_rem_set()->print_summary_info();
2780 concurrent_mark()->print_summary_info();
2781 g1_policy()->print_yg_surv_rate_info();
2782 }
2783
2784 #ifndef PRODUCT
2785 // Helpful for debugging RSet issues.
2786
2787 class PrintRSetsClosure : public HeapRegionClosure {
2788 private:
2789 const char* _msg;
2790 size_t _occupied_sum;
2791
2792 public:
2793 void doHeapRegion(HeapRegion* r) {
2794 HeapRegionRemSet* hrrs = r->rem_set();
2795 size_t occupied = hrrs->occupied();
2796 _occupied_sum += occupied;
2797
2798 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2799 if (occupied == 0) {
2800 tty->print_cr(" RSet is empty");
2801 } else {
2802 hrrs->print();
2803 }
2804 tty->print_cr("----------");
2805 }
2806
2807 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2808 tty->cr();
2809 tty->print_cr("========================================");
2810 tty->print_cr("%s", msg);
2811 tty->cr();
2812 }
2813
2814 ~PrintRSetsClosure() {
2815 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2816 tty->print_cr("========================================");
2817 tty->cr();
2818 }
2819 };
2820
2821 void G1CollectedHeap::print_cset_rsets() {
2822 PrintRSetsClosure cl("Printing CSet RSets");
2823 collection_set_iterate(&cl);
2824 }
2825
2826 void G1CollectedHeap::print_all_rsets() {
2827 PrintRSetsClosure cl("Printing All RSets");;
2828 heap_region_iterate(&cl);
2829 }
2830 #endif // PRODUCT
2831
2832 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2833 YoungList* young_list = heap()->young_list();
2834
2835 size_t eden_used_bytes = young_list->eden_used_bytes();
2836 size_t survivor_used_bytes = young_list->survivor_used_bytes();
2837
2838 size_t eden_capacity_bytes =
2839 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2840
2841 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2842 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes, num_regions());
2843 }
2844
2845 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2846 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2847 stats->unused(), stats->used(), stats->region_end_waste(),
2848 stats->regions_filled(), stats->direct_allocated(),
2849 stats->failure_used(), stats->failure_waste());
2850 }
2851
2852 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2853 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2854 gc_tracer->report_gc_heap_summary(when, heap_summary);
2855
2856 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2857 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2858 }
2859
2860
2861 G1CollectedHeap* G1CollectedHeap::heap() {
2862 CollectedHeap* heap = Universe::heap();
2863 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2864 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2865 return (G1CollectedHeap*)heap;
2866 }
2867
2868 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2869 // always_do_update_barrier = false;
2870 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2871 // Fill TLAB's and such
2872 accumulate_statistics_all_tlabs();
2873 ensure_parsability(true);
2874
2875 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2876 }
2877
2878 void G1CollectedHeap::gc_epilogue(bool full) {
2879 // we are at the end of the GC. Total collections has already been increased.
2880 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2881
2882 // FIXME: what is this about?
2883 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2884 // is set.
2885 #if defined(COMPILER2) || INCLUDE_JVMCI
2886 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2887 #endif
2888 // always_do_update_barrier = true;
2889
2890 resize_all_tlabs();
2891 allocation_context_stats().update(full);
2892
2893 // We have just completed a GC. Update the soft reference
2894 // policy with the new heap occupancy
2895 Universe::update_heap_info_at_gc();
2896 }
2897
2898 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2899 uint gc_count_before,
2900 bool* succeeded,
2901 GCCause::Cause gc_cause) {
2902 assert_heap_not_locked_and_not_at_safepoint();
2903 VM_G1IncCollectionPause op(gc_count_before,
2904 word_size,
2905 false, /* should_initiate_conc_mark */
2906 g1_policy()->max_pause_time_ms(),
2907 gc_cause);
2908
2909 op.set_allocation_context(AllocationContext::current());
2910 VMThread::execute(&op);
2911
2912 HeapWord* result = op.result();
2913 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2914 assert(result == NULL || ret_succeeded,
2915 "the result should be NULL if the VM did not succeed");
2916 *succeeded = ret_succeeded;
2917
2918 assert_heap_not_locked();
2919 return result;
2920 }
2921
2922 void
2923 G1CollectedHeap::doConcurrentMark() {
2924 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2925 if (!_cmThread->in_progress()) {
2926 _cmThread->set_started();
2927 CGC_lock->notify();
2928 }
2929 }
2930
2931 size_t G1CollectedHeap::pending_card_num() {
2932 size_t extra_cards = 0;
2933 JavaThread *curr = Threads::first();
2934 while (curr != NULL) {
2935 DirtyCardQueue& dcq = curr->dirty_card_queue();
2936 extra_cards += dcq.size();
2937 curr = curr->next();
2938 }
2939 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2940 size_t buffer_size = dcqs.buffer_size();
2941 size_t buffer_num = dcqs.completed_buffers_num();
2942
2943 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2944 // in bytes - not the number of 'entries'. We need to convert
2945 // into a number of cards.
2946 return (buffer_size * buffer_num + extra_cards) / oopSize;
2947 }
2948
2949 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2950 private:
2951 size_t _total_humongous;
2952 size_t _candidate_humongous;
2953
2954 DirtyCardQueue _dcq;
2955
2956 // We don't nominate objects with many remembered set entries, on
2957 // the assumption that such objects are likely still live.
2958 bool is_remset_small(HeapRegion* region) const {
2959 HeapRegionRemSet* const rset = region->rem_set();
2960 return G1EagerReclaimHumongousObjectsWithStaleRefs
2961 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2962 : rset->is_empty();
2963 }
2964
2965 bool is_typeArray_region(HeapRegion* region) const {
2966 return oop(region->bottom())->is_typeArray();
2967 }
2968
2969 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2970 assert(region->is_starts_humongous(), "Must start a humongous object");
2971
2972 // Candidate selection must satisfy the following constraints
2973 // while concurrent marking is in progress:
2974 //
2975 // * In order to maintain SATB invariants, an object must not be
2976 // reclaimed if it was allocated before the start of marking and
2977 // has not had its references scanned. Such an object must have
2978 // its references (including type metadata) scanned to ensure no
2979 // live objects are missed by the marking process. Objects
2980 // allocated after the start of concurrent marking don't need to
2981 // be scanned.
2982 //
2983 // * An object must not be reclaimed if it is on the concurrent
2984 // mark stack. Objects allocated after the start of concurrent
2985 // marking are never pushed on the mark stack.
2986 //
2987 // Nominating only objects allocated after the start of concurrent
2988 // marking is sufficient to meet both constraints. This may miss
2989 // some objects that satisfy the constraints, but the marking data
2990 // structures don't support efficiently performing the needed
2991 // additional tests or scrubbing of the mark stack.
2992 //
2993 // However, we presently only nominate is_typeArray() objects.
2994 // A humongous object containing references induces remembered
2995 // set entries on other regions. In order to reclaim such an
2996 // object, those remembered sets would need to be cleaned up.
2997 //
2998 // We also treat is_typeArray() objects specially, allowing them
2999 // to be reclaimed even if allocated before the start of
3000 // concurrent mark. For this we rely on mark stack insertion to
3001 // exclude is_typeArray() objects, preventing reclaiming an object
3002 // that is in the mark stack. We also rely on the metadata for
3003 // such objects to be built-in and so ensured to be kept live.
3004 // Frequent allocation and drop of large binary blobs is an
3005 // important use case for eager reclaim, and this special handling
3006 // may reduce needed headroom.
3007
3008 return is_typeArray_region(region) && is_remset_small(region);
3009 }
3010
3011 public:
3012 RegisterHumongousWithInCSetFastTestClosure()
3013 : _total_humongous(0),
3014 _candidate_humongous(0),
3015 _dcq(&JavaThread::dirty_card_queue_set()) {
3016 }
3017
3018 virtual void doHeapRegion(HeapRegion* r) {
3019 if (!r->is_starts_humongous()) {
3020 return;
3021 }
3022 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3023
3024 bool is_candidate = humongous_region_is_candidate(g1h, r);
3025 uint rindex = r->hrm_index();
3026 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3027 if (is_candidate) {
3028 _candidate_humongous++;
3029 g1h->register_humongous_region_with_cset(rindex);
3030 // Is_candidate already filters out humongous object with large remembered sets.
3031 // If we have a humongous object with a few remembered sets, we simply flush these
3032 // remembered set entries into the DCQS. That will result in automatic
3033 // re-evaluation of their remembered set entries during the following evacuation
3034 // phase.
3035 if (!r->rem_set()->is_empty()) {
3036 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3037 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3038 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3039 HeapRegionRemSetIterator hrrs(r->rem_set());
3040 size_t card_index;
3041 while (hrrs.has_next(card_index)) {
3042 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3043 // The remembered set might contain references to already freed
3044 // regions. Filter out such entries to avoid failing card table
3045 // verification.
3046 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3047 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3048 *card_ptr = CardTableModRefBS::dirty_card_val();
3049 _dcq.enqueue(card_ptr);
3050 }
3051 }
3052 }
3053 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3054 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3055 hrrs.n_yielded(), r->rem_set()->occupied());
3056 r->rem_set()->clear_locked();
3057 }
3058 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3059 }
3060 _total_humongous++;
3061 }
3062
3063 size_t total_humongous() const { return _total_humongous; }
3064 size_t candidate_humongous() const { return _candidate_humongous; }
3065
3066 void flush_rem_set_entries() { _dcq.flush(); }
3067 };
3068
3069 void G1CollectedHeap::register_humongous_regions_with_cset() {
3070 if (!G1EagerReclaimHumongousObjects) {
3071 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3072 return;
3073 }
3074 double time = os::elapsed_counter();
3075
3076 // Collect reclaim candidate information and register candidates with cset.
3077 RegisterHumongousWithInCSetFastTestClosure cl;
3078 heap_region_iterate(&cl);
3079
3080 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3081 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3082 cl.total_humongous(),
3083 cl.candidate_humongous());
3084 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3085
3086 // Finally flush all remembered set entries to re-check into the global DCQS.
3087 cl.flush_rem_set_entries();
3088 }
3089
3090 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3091 public:
3092 void doHeapRegion(HeapRegion* hr) {
3093 if (!hr->is_archive() && !hr->is_continues_humongous()) {
3094 hr->verify_rem_set();
3095 }
3096 }
3097 };
3098
3099 #ifdef ASSERT
3100 class VerifyCSetClosure: public HeapRegionClosure {
3101 public:
3102 void doHeapRegion(HeapRegion* hr) {
3103 // Here we check that the CSet region's RSet is ready for parallel
3104 // iteration. The fields that we'll verify are only manipulated
3105 // when the region is part of a CSet and is collected. Afterwards,
3106 // we reset these fields when we clear the region's RSet (when the
3107 // region is freed) so they are ready when the region is
3108 // re-allocated. The only exception to this is if there's an
3109 // evacuation failure and instead of freeing the region we leave
3110 // it in the heap. In that case, we reset these fields during
3111 // evacuation failure handling.
3112 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3113
3114 // Here's a good place to add any other checks we'd like to
3115 // perform on CSet regions.
3116 }
3117 };
3118 #endif // ASSERT
3119
3120 uint G1CollectedHeap::num_task_queues() const {
3121 return _task_queues->size();
3122 }
3123
3124 #if TASKQUEUE_STATS
3125 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3126 st->print_raw_cr("GC Task Stats");
3127 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3128 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3129 }
3130
3131 void G1CollectedHeap::print_taskqueue_stats() const {
3132 if (!log_develop_is_enabled(Trace, gc, task, stats)) {
3133 return;
3134 }
3135 LogHandle(gc, task, stats) log;
3136 ResourceMark rm;
3137 outputStream* st = log.trace_stream();
3138
3139 print_taskqueue_stats_hdr(st);
3140
3141 TaskQueueStats totals;
3142 const uint n = num_task_queues();
3143 for (uint i = 0; i < n; ++i) {
3144 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3145 totals += task_queue(i)->stats;
3146 }
3147 st->print_raw("tot "); totals.print(st); st->cr();
3148
3149 DEBUG_ONLY(totals.verify());
3150 }
3151
3152 void G1CollectedHeap::reset_taskqueue_stats() {
3153 const uint n = num_task_queues();
3154 for (uint i = 0; i < n; ++i) {
3155 task_queue(i)->stats.reset();
3156 }
3157 }
3158 #endif // TASKQUEUE_STATS
3159
3160 void G1CollectedHeap::wait_for_root_region_scanning() {
3161 double scan_wait_start = os::elapsedTime();
3162 // We have to wait until the CM threads finish scanning the
3163 // root regions as it's the only way to ensure that all the
3164 // objects on them have been correctly scanned before we start
3165 // moving them during the GC.
3166 bool waited = _cm->root_regions()->wait_until_scan_finished();
3167 double wait_time_ms = 0.0;
3168 if (waited) {
3169 double scan_wait_end = os::elapsedTime();
3170 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3171 }
3172 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3173 }
3174
3175 bool
3176 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3177 assert_at_safepoint(true /* should_be_vm_thread */);
3178 guarantee(!is_gc_active(), "collection is not reentrant");
3179
3180 if (GCLocker::check_active_before_gc()) {
3181 return false;
3182 }
3183
3184 _gc_timer_stw->register_gc_start();
3185
3186 GCIdMark gc_id_mark;
3187 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3188
3189 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3190 ResourceMark rm;
3191
3192 wait_for_root_region_scanning();
3193
3194 print_heap_before_gc();
3195 trace_heap_before_gc(_gc_tracer_stw);
3196
3197 _verifier->verify_region_sets_optional();
3198 _verifier->verify_dirty_young_regions();
3199
3200 // This call will decide whether this pause is an initial-mark
3201 // pause. If it is, during_initial_mark_pause() will return true
3202 // for the duration of this pause.
3203 g1_policy()->decide_on_conc_mark_initiation();
3204
3205 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3206 assert(!collector_state()->during_initial_mark_pause() ||
3207 collector_state()->gcs_are_young(), "sanity");
3208
3209 // We also do not allow mixed GCs during marking.
3210 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3211
3212 // Record whether this pause is an initial mark. When the current
3213 // thread has completed its logging output and it's safe to signal
3214 // the CM thread, the flag's value in the policy has been reset.
3215 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3216
3217 // Inner scope for scope based logging, timers, and stats collection
3218 {
3219 EvacuationInfo evacuation_info;
3220
3221 if (collector_state()->during_initial_mark_pause()) {
3222 // We are about to start a marking cycle, so we increment the
3223 // full collection counter.
3224 increment_old_marking_cycles_started();
3225 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3226 }
3227
3228 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3229
3230 GCTraceCPUTime tcpu;
3231
3232 FormatBuffer<> gc_string("Pause ");
3233 if (collector_state()->during_initial_mark_pause()) {
3234 gc_string.append("Initial Mark");
3235 } else if (collector_state()->gcs_are_young()) {
3236 gc_string.append("Young");
3237 } else {
3238 gc_string.append("Mixed");
3239 }
3240 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3241
3242 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3243 workers()->active_workers(),
3244 Threads::number_of_non_daemon_threads());
3245 workers()->set_active_workers(active_workers);
3246
3247 g1_policy()->note_gc_start(active_workers);
3248
3249 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3250 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3251
3252 // If the secondary_free_list is not empty, append it to the
3253 // free_list. No need to wait for the cleanup operation to finish;
3254 // the region allocation code will check the secondary_free_list
3255 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3256 // set, skip this step so that the region allocation code has to
3257 // get entries from the secondary_free_list.
3258 if (!G1StressConcRegionFreeing) {
3259 append_secondary_free_list_if_not_empty_with_lock();
3260 }
3261
3262 G1HeapTransition heap_transition(this);
3263 size_t heap_used_bytes_before_gc = used();
3264
3265 assert(check_young_list_well_formed(), "young list should be well formed");
3266
3267 // Don't dynamically change the number of GC threads this early. A value of
3268 // 0 is used to indicate serial work. When parallel work is done,
3269 // it will be set.
3270
3271 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3272 IsGCActiveMark x;
3273
3274 gc_prologue(false);
3275 increment_total_collections(false /* full gc */);
3276 increment_gc_time_stamp();
3277
3278 if (VerifyRememberedSets) {
3279 log_info(gc, verify)("[Verifying RemSets before GC]");
3280 VerifyRegionRemSetClosure v_cl;
3281 heap_region_iterate(&v_cl);
3282 }
3283
3284 _verifier->verify_before_gc();
3285
3286 _verifier->check_bitmaps("GC Start");
3287
3288 #if defined(COMPILER2) || INCLUDE_JVMCI
3289 DerivedPointerTable::clear();
3290 #endif
3291
3292 // Please see comment in g1CollectedHeap.hpp and
3293 // G1CollectedHeap::ref_processing_init() to see how
3294 // reference processing currently works in G1.
3295
3296 // Enable discovery in the STW reference processor
3297 if (g1_policy()->should_process_references()) {
3298 ref_processor_stw()->enable_discovery();
3299 } else {
3300 ref_processor_stw()->disable_discovery();
3301 }
3302
3303 {
3304 // We want to temporarily turn off discovery by the
3305 // CM ref processor, if necessary, and turn it back on
3306 // on again later if we do. Using a scoped
3307 // NoRefDiscovery object will do this.
3308 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3309
3310 // Forget the current alloc region (we might even choose it to be part
3311 // of the collection set!).
3312 _allocator->release_mutator_alloc_region();
3313
3314 // This timing is only used by the ergonomics to handle our pause target.
3315 // It is unclear why this should not include the full pause. We will
3316 // investigate this in CR 7178365.
3317 //
3318 // Preserving the old comment here if that helps the investigation:
3319 //
3320 // The elapsed time induced by the start time below deliberately elides
3321 // the possible verification above.
3322 double sample_start_time_sec = os::elapsedTime();
3323
3324 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3325
3326 if (collector_state()->during_initial_mark_pause()) {
3327 concurrent_mark()->checkpointRootsInitialPre();
3328 }
3329
3330 g1_policy()->finalize_collection_set(target_pause_time_ms);
3331
3332 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3333
3334 // Make sure the remembered sets are up to date. This needs to be
3335 // done before register_humongous_regions_with_cset(), because the
3336 // remembered sets are used there to choose eager reclaim candidates.
3337 // If the remembered sets are not up to date we might miss some
3338 // entries that need to be handled.
3339 g1_rem_set()->cleanupHRRS();
3340
3341 register_humongous_regions_with_cset();
3342
3343 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3344
3345 _cm->note_start_of_gc();
3346 // We call this after finalize_cset() to
3347 // ensure that the CSet has been finalized.
3348 _cm->verify_no_cset_oops();
3349
3350 if (_hr_printer.is_active()) {
3351 HeapRegion* hr = collection_set()->head();
3352 while (hr != NULL) {
3353 _hr_printer.cset(hr);
3354 hr = hr->next_in_collection_set();
3355 }
3356 }
3357
3358 #ifdef ASSERT
3359 VerifyCSetClosure cl;
3360 collection_set_iterate(&cl);
3361 #endif // ASSERT
3362
3363 // Initialize the GC alloc regions.
3364 _allocator->init_gc_alloc_regions(evacuation_info);
3365
3366 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3367 pre_evacuate_collection_set();
3368
3369 // Actually do the work...
3370 evacuate_collection_set(evacuation_info, &per_thread_states);
3371
3372 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3373
3374 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3375 free_collection_set(collection_set()->head(), evacuation_info, surviving_young_words);
3376
3377 eagerly_reclaim_humongous_regions();
3378
3379 collection_set()->clear_head();
3380
3381 record_obj_copy_mem_stats();
3382 _survivor_evac_stats.adjust_desired_plab_sz();
3383 _old_evac_stats.adjust_desired_plab_sz();
3384
3385 // Start a new incremental collection set for the next pause.
3386 collection_set()->start_incremental_building();
3387
3388 clear_cset_fast_test();
3389
3390 // Don't check the whole heap at this point as the
3391 // GC alloc regions from this pause have been tagged
3392 // as survivors and moved on to the survivor list.
3393 // Survivor regions will fail the !is_young() check.
3394 assert(check_young_list_empty(false /* check_heap */),
3395 "young list should be empty");
3396
3397 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3398 _young_list->first_survivor_region(),
3399 _young_list->last_survivor_region());
3400
3401 _young_list->reset_auxilary_lists();
3402
3403 if (evacuation_failed()) {
3404 set_used(recalculate_used());
3405 if (_archive_allocator != NULL) {
3406 _archive_allocator->clear_used();
3407 }
3408 for (uint i = 0; i < ParallelGCThreads; i++) {
3409 if (_evacuation_failed_info_array[i].has_failed()) {
3410 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3411 }
3412 }
3413 } else {
3414 // The "used" of the the collection set have already been subtracted
3415 // when they were freed. Add in the bytes evacuated.
3416 increase_used(g1_policy()->bytes_copied_during_gc());
3417 }
3418
3419 if (collector_state()->during_initial_mark_pause()) {
3420 // We have to do this before we notify the CM threads that
3421 // they can start working to make sure that all the
3422 // appropriate initialization is done on the CM object.
3423 concurrent_mark()->checkpointRootsInitialPost();
3424 collector_state()->set_mark_in_progress(true);
3425 // Note that we don't actually trigger the CM thread at
3426 // this point. We do that later when we're sure that
3427 // the current thread has completed its logging output.
3428 }
3429
3430 allocate_dummy_regions();
3431
3432 _allocator->init_mutator_alloc_region();
3433
3434 {
3435 size_t expand_bytes = g1_policy()->expansion_amount();
3436 if (expand_bytes > 0) {
3437 size_t bytes_before = capacity();
3438 // No need for an ergo logging here,
3439 // expansion_amount() does this when it returns a value > 0.
3440 double expand_ms;
3441 if (!expand(expand_bytes, &expand_ms)) {
3442 // We failed to expand the heap. Cannot do anything about it.
3443 }
3444 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3445 }
3446 }
3447
3448 // We redo the verification but now wrt to the new CSet which
3449 // has just got initialized after the previous CSet was freed.
3450 _cm->verify_no_cset_oops();
3451 _cm->note_end_of_gc();
3452
3453 // This timing is only used by the ergonomics to handle our pause target.
3454 // It is unclear why this should not include the full pause. We will
3455 // investigate this in CR 7178365.
3456 double sample_end_time_sec = os::elapsedTime();
3457 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3458 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3459 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3460
3461 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3462 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3463
3464 MemoryService::track_memory_usage();
3465
3466 // In prepare_for_verify() below we'll need to scan the deferred
3467 // update buffers to bring the RSets up-to-date if
3468 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3469 // the update buffers we'll probably need to scan cards on the
3470 // regions we just allocated to (i.e., the GC alloc
3471 // regions). However, during the last GC we called
3472 // set_saved_mark() on all the GC alloc regions, so card
3473 // scanning might skip the [saved_mark_word()...top()] area of
3474 // those regions (i.e., the area we allocated objects into
3475 // during the last GC). But it shouldn't. Given that
3476 // saved_mark_word() is conditional on whether the GC time stamp
3477 // on the region is current or not, by incrementing the GC time
3478 // stamp here we invalidate all the GC time stamps on all the
3479 // regions and saved_mark_word() will simply return top() for
3480 // all the regions. This is a nicer way of ensuring this rather
3481 // than iterating over the regions and fixing them. In fact, the
3482 // GC time stamp increment here also ensures that
3483 // saved_mark_word() will return top() between pauses, i.e.,
3484 // during concurrent refinement. So we don't need the
3485 // is_gc_active() check to decided which top to use when
3486 // scanning cards (see CR 7039627).
3487 increment_gc_time_stamp();
3488
3489 if (VerifyRememberedSets) {
3490 log_info(gc, verify)("[Verifying RemSets after GC]");
3491 VerifyRegionRemSetClosure v_cl;
3492 heap_region_iterate(&v_cl);
3493 }
3494
3495 _verifier->verify_after_gc();
3496 _verifier->check_bitmaps("GC End");
3497
3498 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3499 ref_processor_stw()->verify_no_references_recorded();
3500
3501 // CM reference discovery will be re-enabled if necessary.
3502 }
3503
3504 #ifdef TRACESPINNING
3505 ParallelTaskTerminator::print_termination_counts();
3506 #endif
3507
3508 gc_epilogue(false);
3509 }
3510
3511 // Print the remainder of the GC log output.
3512 if (evacuation_failed()) {
3513 log_info(gc)("To-space exhausted");
3514 }
3515
3516 g1_policy()->print_phases();
3517 heap_transition.print();
3518
3519 // It is not yet to safe to tell the concurrent mark to
3520 // start as we have some optional output below. We don't want the
3521 // output from the concurrent mark thread interfering with this
3522 // logging output either.
3523
3524 _hrm.verify_optional();
3525 _verifier->verify_region_sets_optional();
3526
3527 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3528 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3529
3530 print_heap_after_gc();
3531 trace_heap_after_gc(_gc_tracer_stw);
3532
3533 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3534 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3535 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3536 // before any GC notifications are raised.
3537 g1mm()->update_sizes();
3538
3539 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3540 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3541 _gc_timer_stw->register_gc_end();
3542 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3543 }
3544 // It should now be safe to tell the concurrent mark thread to start
3545 // without its logging output interfering with the logging output
3546 // that came from the pause.
3547
3548 if (should_start_conc_mark) {
3549 // CAUTION: after the doConcurrentMark() call below,
3550 // the concurrent marking thread(s) could be running
3551 // concurrently with us. Make sure that anything after
3552 // this point does not assume that we are the only GC thread
3553 // running. Note: of course, the actual marking work will
3554 // not start until the safepoint itself is released in
3555 // SuspendibleThreadSet::desynchronize().
3556 doConcurrentMark();
3557 }
3558
3559 return true;
3560 }
3561
3562 void G1CollectedHeap::restore_preserved_marks() {
3563 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3564 workers()->run_task(&rpm_task);
3565 }
3566
3567 void G1CollectedHeap::remove_self_forwarding_pointers() {
3568 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3569 workers()->run_task(&rsfp_task);
3570 }
3571
3572 void G1CollectedHeap::restore_after_evac_failure() {
3573 double remove_self_forwards_start = os::elapsedTime();
3574
3575 remove_self_forwarding_pointers();
3576 restore_preserved_marks();
3577
3578 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3579 }
3580
3581 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3582 if (!_evacuation_failed) {
3583 _evacuation_failed = true;
3584 }
3585
3586 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3587
3588 // We want to call the "for_promotion_failure" version only in the
3589 // case of a promotion failure.
3590 if (m->must_be_preserved_for_promotion_failure(obj)) {
3591 OopAndMarkOop elem(obj, m);
3592 _preserved_objs[worker_id].push(elem);
3593 }
3594 }
3595
3596 bool G1ParEvacuateFollowersClosure::offer_termination() {
3597 G1ParScanThreadState* const pss = par_scan_state();
3598 start_term_time();
3599 const bool res = terminator()->offer_termination();
3600 end_term_time();
3601 return res;
3602 }
3603
3604 void G1ParEvacuateFollowersClosure::do_void() {
3605 G1ParScanThreadState* const pss = par_scan_state();
3606 pss->trim_queue();
3607 do {
3608 pss->steal_and_trim_queue(queues());
3609 } while (!offer_termination());
3610 }
3611
3612 class G1ParTask : public AbstractGangTask {
3613 protected:
3614 G1CollectedHeap* _g1h;
3615 G1ParScanThreadStateSet* _pss;
3616 RefToScanQueueSet* _queues;
3617 G1RootProcessor* _root_processor;
3618 ParallelTaskTerminator _terminator;
3619 uint _n_workers;
3620
3621 public:
3622 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3623 : AbstractGangTask("G1 collection"),
3624 _g1h(g1h),
3625 _pss(per_thread_states),
3626 _queues(task_queues),
3627 _root_processor(root_processor),
3628 _terminator(n_workers, _queues),
3629 _n_workers(n_workers)
3630 {}
3631
3632 void work(uint worker_id) {
3633 if (worker_id >= _n_workers) return; // no work needed this round
3634
3635 double start_sec = os::elapsedTime();
3636 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3637
3638 {
3639 ResourceMark rm;
3640 HandleMark hm;
3641
3642 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3643
3644 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3645 pss->set_ref_processor(rp);
3646
3647 double start_strong_roots_sec = os::elapsedTime();
3648
3649 _root_processor->evacuate_roots(pss->closures(), worker_id);
3650
3651 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3652
3653 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3654 // treating the nmethods visited to act as roots for concurrent marking.
3655 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3656 // objects copied by the current evacuation.
3657 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3658 pss->closures()->weak_codeblobs(),
3659 worker_id);
3660
3661 _pss->add_cards_scanned(worker_id, cards_scanned);
3662
3663 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3664
3665 double term_sec = 0.0;
3666 size_t evac_term_attempts = 0;
3667 {
3668 double start = os::elapsedTime();
3669 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3670 evac.do_void();
3671
3672 evac_term_attempts = evac.term_attempts();
3673 term_sec = evac.term_time();
3674 double elapsed_sec = os::elapsedTime() - start;
3675 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3676 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3677 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3678 }
3679
3680 assert(pss->queue_is_empty(), "should be empty");
3681
3682 if (log_is_enabled(Debug, gc, task, stats)) {
3683 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3684 size_t lab_waste;
3685 size_t lab_undo_waste;
3686 pss->waste(lab_waste, lab_undo_waste);
3687 _g1h->print_termination_stats(worker_id,
3688 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3689 strong_roots_sec * 1000.0, /* strong roots time */
3690 term_sec * 1000.0, /* evac term time */
3691 evac_term_attempts, /* evac term attempts */
3692 lab_waste, /* alloc buffer waste */
3693 lab_undo_waste /* undo waste */
3694 );
3695 }
3696
3697 // Close the inner scope so that the ResourceMark and HandleMark
3698 // destructors are executed here and are included as part of the
3699 // "GC Worker Time".
3700 }
3701 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3702 }
3703 };
3704
3705 void G1CollectedHeap::print_termination_stats_hdr() {
3706 log_debug(gc, task, stats)("GC Termination Stats");
3707 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3708 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3709 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3710 }
3711
3712 void G1CollectedHeap::print_termination_stats(uint worker_id,
3713 double elapsed_ms,
3714 double strong_roots_ms,
3715 double term_ms,
3716 size_t term_attempts,
3717 size_t alloc_buffer_waste,
3718 size_t undo_waste) const {
3719 log_debug(gc, task, stats)
3720 ("%3d %9.2f %9.2f %6.2f "
3721 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3722 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3723 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3724 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3725 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3726 alloc_buffer_waste * HeapWordSize / K,
3727 undo_waste * HeapWordSize / K);
3728 }
3729
3730 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3731 private:
3732 BoolObjectClosure* _is_alive;
3733 int _initial_string_table_size;
3734 int _initial_symbol_table_size;
3735
3736 bool _process_strings;
3737 int _strings_processed;
3738 int _strings_removed;
3739
3740 bool _process_symbols;
3741 int _symbols_processed;
3742 int _symbols_removed;
3743
3744 public:
3745 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3746 AbstractGangTask("String/Symbol Unlinking"),
3747 _is_alive(is_alive),
3748 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3749 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3750
3751 _initial_string_table_size = StringTable::the_table()->table_size();
3752 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3753 if (process_strings) {
3754 StringTable::clear_parallel_claimed_index();
3755 }
3756 if (process_symbols) {
3757 SymbolTable::clear_parallel_claimed_index();
3758 }
3759 }
3760
3761 ~G1StringSymbolTableUnlinkTask() {
3762 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3763 "claim value %d after unlink less than initial string table size %d",
3764 StringTable::parallel_claimed_index(), _initial_string_table_size);
3765 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3766 "claim value %d after unlink less than initial symbol table size %d",
3767 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3768
3769 log_debug(gc, stringdedup)("Cleaned string and symbol table, "
3770 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3771 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3772 strings_processed(), strings_removed(),
3773 symbols_processed(), symbols_removed());
3774 }
3775
3776 void work(uint worker_id) {
3777 int strings_processed = 0;
3778 int strings_removed = 0;
3779 int symbols_processed = 0;
3780 int symbols_removed = 0;
3781 if (_process_strings) {
3782 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3783 Atomic::add(strings_processed, &_strings_processed);
3784 Atomic::add(strings_removed, &_strings_removed);
3785 }
3786 if (_process_symbols) {
3787 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3788 Atomic::add(symbols_processed, &_symbols_processed);
3789 Atomic::add(symbols_removed, &_symbols_removed);
3790 }
3791 }
3792
3793 size_t strings_processed() const { return (size_t)_strings_processed; }
3794 size_t strings_removed() const { return (size_t)_strings_removed; }
3795
3796 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3797 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3798 };
3799
3800 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3801 private:
3802 static Monitor* _lock;
3803
3804 BoolObjectClosure* const _is_alive;
3805 const bool _unloading_occurred;
3806 const uint _num_workers;
3807
3808 // Variables used to claim nmethods.
3809 nmethod* _first_nmethod;
3810 volatile nmethod* _claimed_nmethod;
3811
3812 // The list of nmethods that need to be processed by the second pass.
3813 volatile nmethod* _postponed_list;
3814 volatile uint _num_entered_barrier;
3815
3816 public:
3817 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3818 _is_alive(is_alive),
3819 _unloading_occurred(unloading_occurred),
3820 _num_workers(num_workers),
3821 _first_nmethod(NULL),
3822 _claimed_nmethod(NULL),
3823 _postponed_list(NULL),
3824 _num_entered_barrier(0)
3825 {
3826 nmethod::increase_unloading_clock();
3827 // Get first alive nmethod
3828 NMethodIterator iter = NMethodIterator();
3829 if(iter.next_alive()) {
3830 _first_nmethod = iter.method();
3831 }
3832 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3833 }
3834
3835 ~G1CodeCacheUnloadingTask() {
3836 CodeCache::verify_clean_inline_caches();
3837
3838 CodeCache::set_needs_cache_clean(false);
3839 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3840
3841 CodeCache::verify_icholder_relocations();
3842 }
3843
3844 private:
3845 void add_to_postponed_list(nmethod* nm) {
3846 nmethod* old;
3847 do {
3848 old = (nmethod*)_postponed_list;
3849 nm->set_unloading_next(old);
3850 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3851 }
3852
3853 void clean_nmethod(nmethod* nm) {
3854 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3855
3856 if (postponed) {
3857 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3858 add_to_postponed_list(nm);
3859 }
3860
3861 // Mark that this thread has been cleaned/unloaded.
3862 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3863 nm->set_unloading_clock(nmethod::global_unloading_clock());
3864 }
3865
3866 void clean_nmethod_postponed(nmethod* nm) {
3867 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3868 }
3869
3870 static const int MaxClaimNmethods = 16;
3871
3872 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3873 nmethod* first;
3874 NMethodIterator last;
3875
3876 do {
3877 *num_claimed_nmethods = 0;
3878
3879 first = (nmethod*)_claimed_nmethod;
3880 last = NMethodIterator(first);
3881
3882 if (first != NULL) {
3883
3884 for (int i = 0; i < MaxClaimNmethods; i++) {
3885 if (!last.next_alive()) {
3886 break;
3887 }
3888 claimed_nmethods[i] = last.method();
3889 (*num_claimed_nmethods)++;
3890 }
3891 }
3892
3893 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3894 }
3895
3896 nmethod* claim_postponed_nmethod() {
3897 nmethod* claim;
3898 nmethod* next;
3899
3900 do {
3901 claim = (nmethod*)_postponed_list;
3902 if (claim == NULL) {
3903 return NULL;
3904 }
3905
3906 next = claim->unloading_next();
3907
3908 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3909
3910 return claim;
3911 }
3912
3913 public:
3914 // Mark that we're done with the first pass of nmethod cleaning.
3915 void barrier_mark(uint worker_id) {
3916 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3917 _num_entered_barrier++;
3918 if (_num_entered_barrier == _num_workers) {
3919 ml.notify_all();
3920 }
3921 }
3922
3923 // See if we have to wait for the other workers to
3924 // finish their first-pass nmethod cleaning work.
3925 void barrier_wait(uint worker_id) {
3926 if (_num_entered_barrier < _num_workers) {
3927 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3928 while (_num_entered_barrier < _num_workers) {
3929 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3930 }
3931 }
3932 }
3933
3934 // Cleaning and unloading of nmethods. Some work has to be postponed
3935 // to the second pass, when we know which nmethods survive.
3936 void work_first_pass(uint worker_id) {
3937 // The first nmethods is claimed by the first worker.
3938 if (worker_id == 0 && _first_nmethod != NULL) {
3939 clean_nmethod(_first_nmethod);
3940 _first_nmethod = NULL;
3941 }
3942
3943 int num_claimed_nmethods;
3944 nmethod* claimed_nmethods[MaxClaimNmethods];
3945
3946 while (true) {
3947 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3948
3949 if (num_claimed_nmethods == 0) {
3950 break;
3951 }
3952
3953 for (int i = 0; i < num_claimed_nmethods; i++) {
3954 clean_nmethod(claimed_nmethods[i]);
3955 }
3956 }
3957 }
3958
3959 void work_second_pass(uint worker_id) {
3960 nmethod* nm;
3961 // Take care of postponed nmethods.
3962 while ((nm = claim_postponed_nmethod()) != NULL) {
3963 clean_nmethod_postponed(nm);
3964 }
3965 }
3966 };
3967
3968 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3969
3970 class G1KlassCleaningTask : public StackObj {
3971 BoolObjectClosure* _is_alive;
3972 volatile jint _clean_klass_tree_claimed;
3973 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3974
3975 public:
3976 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3977 _is_alive(is_alive),
3978 _clean_klass_tree_claimed(0),
3979 _klass_iterator() {
3980 }
3981
3982 private:
3983 bool claim_clean_klass_tree_task() {
3984 if (_clean_klass_tree_claimed) {
3985 return false;
3986 }
3987
3988 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3989 }
3990
3991 InstanceKlass* claim_next_klass() {
3992 Klass* klass;
3993 do {
3994 klass =_klass_iterator.next_klass();
3995 } while (klass != NULL && !klass->is_instance_klass());
3996
3997 // this can be null so don't call InstanceKlass::cast
3998 return static_cast<InstanceKlass*>(klass);
3999 }
4000
4001 public:
4002
4003 void clean_klass(InstanceKlass* ik) {
4004 ik->clean_weak_instanceklass_links(_is_alive);
4005 }
4006
4007 void work() {
4008 ResourceMark rm;
4009
4010 // One worker will clean the subklass/sibling klass tree.
4011 if (claim_clean_klass_tree_task()) {
4012 Klass::clean_subklass_tree(_is_alive);
4013 }
4014
4015 // All workers will help cleaning the classes,
4016 InstanceKlass* klass;
4017 while ((klass = claim_next_klass()) != NULL) {
4018 clean_klass(klass);
4019 }
4020 }
4021 };
4022
4023 // To minimize the remark pause times, the tasks below are done in parallel.
4024 class G1ParallelCleaningTask : public AbstractGangTask {
4025 private:
4026 G1StringSymbolTableUnlinkTask _string_symbol_task;
4027 G1CodeCacheUnloadingTask _code_cache_task;
4028 G1KlassCleaningTask _klass_cleaning_task;
4029
4030 public:
4031 // The constructor is run in the VMThread.
4032 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4033 AbstractGangTask("Parallel Cleaning"),
4034 _string_symbol_task(is_alive, process_strings, process_symbols),
4035 _code_cache_task(num_workers, is_alive, unloading_occurred),
4036 _klass_cleaning_task(is_alive) {
4037 }
4038
4039 // The parallel work done by all worker threads.
4040 void work(uint worker_id) {
4041 // Do first pass of code cache cleaning.
4042 _code_cache_task.work_first_pass(worker_id);
4043
4044 // Let the threads mark that the first pass is done.
4045 _code_cache_task.barrier_mark(worker_id);
4046
4047 // Clean the Strings and Symbols.
4048 _string_symbol_task.work(worker_id);
4049
4050 // Wait for all workers to finish the first code cache cleaning pass.
4051 _code_cache_task.barrier_wait(worker_id);
4052
4053 // Do the second code cache cleaning work, which realize on
4054 // the liveness information gathered during the first pass.
4055 _code_cache_task.work_second_pass(worker_id);
4056
4057 // Clean all klasses that were not unloaded.
4058 _klass_cleaning_task.work();
4059 }
4060 };
4061
4062
4063 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4064 bool process_strings,
4065 bool process_symbols,
4066 bool class_unloading_occurred) {
4067 uint n_workers = workers()->active_workers();
4068
4069 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4070 n_workers, class_unloading_occurred);
4071 workers()->run_task(&g1_unlink_task);
4072 }
4073
4074 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4075 bool process_strings, bool process_symbols) {
4076 {
4077 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4078 workers()->run_task(&g1_unlink_task);
4079 }
4080
4081 if (G1StringDedup::is_enabled()) {
4082 G1StringDedup::unlink(is_alive);
4083 }
4084 }
4085
4086 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4087 private:
4088 DirtyCardQueueSet* _queue;
4089 G1CollectedHeap* _g1h;
4090 public:
4091 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4092 _queue(queue), _g1h(g1h) { }
4093
4094 virtual void work(uint worker_id) {
4095 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4096 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4097
4098 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4099 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4100
4101 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4102 }
4103 };
4104
4105 void G1CollectedHeap::redirty_logged_cards() {
4106 double redirty_logged_cards_start = os::elapsedTime();
4107
4108 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4109 dirty_card_queue_set().reset_for_par_iteration();
4110 workers()->run_task(&redirty_task);
4111
4112 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4113 dcq.merge_bufferlists(&dirty_card_queue_set());
4114 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4115
4116 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4117 }
4118
4119 // Weak Reference Processing support
4120
4121 // An always "is_alive" closure that is used to preserve referents.
4122 // If the object is non-null then it's alive. Used in the preservation
4123 // of referent objects that are pointed to by reference objects
4124 // discovered by the CM ref processor.
4125 class G1AlwaysAliveClosure: public BoolObjectClosure {
4126 G1CollectedHeap* _g1;
4127 public:
4128 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4129 bool do_object_b(oop p) {
4130 if (p != NULL) {
4131 return true;
4132 }
4133 return false;
4134 }
4135 };
4136
4137 bool G1STWIsAliveClosure::do_object_b(oop p) {
4138 // An object is reachable if it is outside the collection set,
4139 // or is inside and copied.
4140 return !_g1->is_in_cset(p) || p->is_forwarded();
4141 }
4142
4143 // Non Copying Keep Alive closure
4144 class G1KeepAliveClosure: public OopClosure {
4145 G1CollectedHeap* _g1;
4146 public:
4147 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4148 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4149 void do_oop(oop* p) {
4150 oop obj = *p;
4151 assert(obj != NULL, "the caller should have filtered out NULL values");
4152
4153 const InCSetState cset_state = _g1->in_cset_state(obj);
4154 if (!cset_state.is_in_cset_or_humongous()) {
4155 return;
4156 }
4157 if (cset_state.is_in_cset()) {
4158 assert( obj->is_forwarded(), "invariant" );
4159 *p = obj->forwardee();
4160 } else {
4161 assert(!obj->is_forwarded(), "invariant" );
4162 assert(cset_state.is_humongous(),
4163 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4164 _g1->set_humongous_is_live(obj);
4165 }
4166 }
4167 };
4168
4169 // Copying Keep Alive closure - can be called from both
4170 // serial and parallel code as long as different worker
4171 // threads utilize different G1ParScanThreadState instances
4172 // and different queues.
4173
4174 class G1CopyingKeepAliveClosure: public OopClosure {
4175 G1CollectedHeap* _g1h;
4176 OopClosure* _copy_non_heap_obj_cl;
4177 G1ParScanThreadState* _par_scan_state;
4178
4179 public:
4180 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4181 OopClosure* non_heap_obj_cl,
4182 G1ParScanThreadState* pss):
4183 _g1h(g1h),
4184 _copy_non_heap_obj_cl(non_heap_obj_cl),
4185 _par_scan_state(pss)
4186 {}
4187
4188 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4189 virtual void do_oop( oop* p) { do_oop_work(p); }
4190
4191 template <class T> void do_oop_work(T* p) {
4192 oop obj = oopDesc::load_decode_heap_oop(p);
4193
4194 if (_g1h->is_in_cset_or_humongous(obj)) {
4195 // If the referent object has been forwarded (either copied
4196 // to a new location or to itself in the event of an
4197 // evacuation failure) then we need to update the reference
4198 // field and, if both reference and referent are in the G1
4199 // heap, update the RSet for the referent.
4200 //
4201 // If the referent has not been forwarded then we have to keep
4202 // it alive by policy. Therefore we have copy the referent.
4203 //
4204 // If the reference field is in the G1 heap then we can push
4205 // on the PSS queue. When the queue is drained (after each
4206 // phase of reference processing) the object and it's followers
4207 // will be copied, the reference field set to point to the
4208 // new location, and the RSet updated. Otherwise we need to
4209 // use the the non-heap or metadata closures directly to copy
4210 // the referent object and update the pointer, while avoiding
4211 // updating the RSet.
4212
4213 if (_g1h->is_in_g1_reserved(p)) {
4214 _par_scan_state->push_on_queue(p);
4215 } else {
4216 assert(!Metaspace::contains((const void*)p),
4217 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4218 _copy_non_heap_obj_cl->do_oop(p);
4219 }
4220 }
4221 }
4222 };
4223
4224 // Serial drain queue closure. Called as the 'complete_gc'
4225 // closure for each discovered list in some of the
4226 // reference processing phases.
4227
4228 class G1STWDrainQueueClosure: public VoidClosure {
4229 protected:
4230 G1CollectedHeap* _g1h;
4231 G1ParScanThreadState* _par_scan_state;
4232
4233 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4234
4235 public:
4236 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4237 _g1h(g1h),
4238 _par_scan_state(pss)
4239 { }
4240
4241 void do_void() {
4242 G1ParScanThreadState* const pss = par_scan_state();
4243 pss->trim_queue();
4244 }
4245 };
4246
4247 // Parallel Reference Processing closures
4248
4249 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4250 // processing during G1 evacuation pauses.
4251
4252 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4253 private:
4254 G1CollectedHeap* _g1h;
4255 G1ParScanThreadStateSet* _pss;
4256 RefToScanQueueSet* _queues;
4257 WorkGang* _workers;
4258 uint _active_workers;
4259
4260 public:
4261 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4262 G1ParScanThreadStateSet* per_thread_states,
4263 WorkGang* workers,
4264 RefToScanQueueSet *task_queues,
4265 uint n_workers) :
4266 _g1h(g1h),
4267 _pss(per_thread_states),
4268 _queues(task_queues),
4269 _workers(workers),
4270 _active_workers(n_workers)
4271 {
4272 assert(n_workers > 0, "shouldn't call this otherwise");
4273 }
4274
4275 // Executes the given task using concurrent marking worker threads.
4276 virtual void execute(ProcessTask& task);
4277 virtual void execute(EnqueueTask& task);
4278 };
4279
4280 // Gang task for possibly parallel reference processing
4281
4282 class G1STWRefProcTaskProxy: public AbstractGangTask {
4283 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4284 ProcessTask& _proc_task;
4285 G1CollectedHeap* _g1h;
4286 G1ParScanThreadStateSet* _pss;
4287 RefToScanQueueSet* _task_queues;
4288 ParallelTaskTerminator* _terminator;
4289
4290 public:
4291 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4292 G1CollectedHeap* g1h,
4293 G1ParScanThreadStateSet* per_thread_states,
4294 RefToScanQueueSet *task_queues,
4295 ParallelTaskTerminator* terminator) :
4296 AbstractGangTask("Process reference objects in parallel"),
4297 _proc_task(proc_task),
4298 _g1h(g1h),
4299 _pss(per_thread_states),
4300 _task_queues(task_queues),
4301 _terminator(terminator)
4302 {}
4303
4304 virtual void work(uint worker_id) {
4305 // The reference processing task executed by a single worker.
4306 ResourceMark rm;
4307 HandleMark hm;
4308
4309 G1STWIsAliveClosure is_alive(_g1h);
4310
4311 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4312 pss->set_ref_processor(NULL);
4313
4314 // Keep alive closure.
4315 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4316
4317 // Complete GC closure
4318 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4319
4320 // Call the reference processing task's work routine.
4321 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4322
4323 // Note we cannot assert that the refs array is empty here as not all
4324 // of the processing tasks (specifically phase2 - pp2_work) execute
4325 // the complete_gc closure (which ordinarily would drain the queue) so
4326 // the queue may not be empty.
4327 }
4328 };
4329
4330 // Driver routine for parallel reference processing.
4331 // Creates an instance of the ref processing gang
4332 // task and has the worker threads execute it.
4333 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4334 assert(_workers != NULL, "Need parallel worker threads.");
4335
4336 ParallelTaskTerminator terminator(_active_workers, _queues);
4337 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4338
4339 _workers->run_task(&proc_task_proxy);
4340 }
4341
4342 // Gang task for parallel reference enqueueing.
4343
4344 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4345 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4346 EnqueueTask& _enq_task;
4347
4348 public:
4349 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4350 AbstractGangTask("Enqueue reference objects in parallel"),
4351 _enq_task(enq_task)
4352 { }
4353
4354 virtual void work(uint worker_id) {
4355 _enq_task.work(worker_id);
4356 }
4357 };
4358
4359 // Driver routine for parallel reference enqueueing.
4360 // Creates an instance of the ref enqueueing gang
4361 // task and has the worker threads execute it.
4362
4363 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4364 assert(_workers != NULL, "Need parallel worker threads.");
4365
4366 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4367
4368 _workers->run_task(&enq_task_proxy);
4369 }
4370
4371 // End of weak reference support closures
4372
4373 // Abstract task used to preserve (i.e. copy) any referent objects
4374 // that are in the collection set and are pointed to by reference
4375 // objects discovered by the CM ref processor.
4376
4377 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4378 protected:
4379 G1CollectedHeap* _g1h;
4380 G1ParScanThreadStateSet* _pss;
4381 RefToScanQueueSet* _queues;
4382 ParallelTaskTerminator _terminator;
4383 uint _n_workers;
4384
4385 public:
4386 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4387 AbstractGangTask("ParPreserveCMReferents"),
4388 _g1h(g1h),
4389 _pss(per_thread_states),
4390 _queues(task_queues),
4391 _terminator(workers, _queues),
4392 _n_workers(workers)
4393 { }
4394
4395 void work(uint worker_id) {
4396 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4397
4398 ResourceMark rm;
4399 HandleMark hm;
4400
4401 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4402 pss->set_ref_processor(NULL);
4403 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4404
4405 // Is alive closure
4406 G1AlwaysAliveClosure always_alive(_g1h);
4407
4408 // Copying keep alive closure. Applied to referent objects that need
4409 // to be copied.
4410 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4411
4412 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4413
4414 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4415 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4416
4417 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4418 // So this must be true - but assert just in case someone decides to
4419 // change the worker ids.
4420 assert(worker_id < limit, "sanity");
4421 assert(!rp->discovery_is_atomic(), "check this code");
4422
4423 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4424 for (uint idx = worker_id; idx < limit; idx += stride) {
4425 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4426
4427 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4428 while (iter.has_next()) {
4429 // Since discovery is not atomic for the CM ref processor, we
4430 // can see some null referent objects.
4431 iter.load_ptrs(DEBUG_ONLY(true));
4432 oop ref = iter.obj();
4433
4434 // This will filter nulls.
4435 if (iter.is_referent_alive()) {
4436 iter.make_referent_alive();
4437 }
4438 iter.move_to_next();
4439 }
4440 }
4441
4442 // Drain the queue - which may cause stealing
4443 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4444 drain_queue.do_void();
4445 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4446 assert(pss->queue_is_empty(), "should be");
4447 }
4448 };
4449
4450 void G1CollectedHeap::process_weak_jni_handles() {
4451 double ref_proc_start = os::elapsedTime();
4452
4453 G1STWIsAliveClosure is_alive(this);
4454 G1KeepAliveClosure keep_alive(this);
4455 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4456
4457 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4458 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4459 }
4460
4461 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4462 double preserve_cm_referents_start = os::elapsedTime();
4463 // Any reference objects, in the collection set, that were 'discovered'
4464 // by the CM ref processor should have already been copied (either by
4465 // applying the external root copy closure to the discovered lists, or
4466 // by following an RSet entry).
4467 //
4468 // But some of the referents, that are in the collection set, that these
4469 // reference objects point to may not have been copied: the STW ref
4470 // processor would have seen that the reference object had already
4471 // been 'discovered' and would have skipped discovering the reference,
4472 // but would not have treated the reference object as a regular oop.
4473 // As a result the copy closure would not have been applied to the
4474 // referent object.
4475 //
4476 // We need to explicitly copy these referent objects - the references
4477 // will be processed at the end of remarking.
4478 //
4479 // We also need to do this copying before we process the reference
4480 // objects discovered by the STW ref processor in case one of these
4481 // referents points to another object which is also referenced by an
4482 // object discovered by the STW ref processor.
4483
4484 uint no_of_gc_workers = workers()->active_workers();
4485
4486 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4487 per_thread_states,
4488 no_of_gc_workers,
4489 _task_queues);
4490 workers()->run_task(&keep_cm_referents);
4491
4492 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms((os::elapsedTime() - preserve_cm_referents_start) * 1000.0);
4493 }
4494
4495 // Weak Reference processing during an evacuation pause (part 1).
4496 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4497 double ref_proc_start = os::elapsedTime();
4498
4499 ReferenceProcessor* rp = _ref_processor_stw;
4500 assert(rp->discovery_enabled(), "should have been enabled");
4501
4502 // Closure to test whether a referent is alive.
4503 G1STWIsAliveClosure is_alive(this);
4504
4505 // Even when parallel reference processing is enabled, the processing
4506 // of JNI refs is serial and performed serially by the current thread
4507 // rather than by a worker. The following PSS will be used for processing
4508 // JNI refs.
4509
4510 // Use only a single queue for this PSS.
4511 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4512 pss->set_ref_processor(NULL);
4513 assert(pss->queue_is_empty(), "pre-condition");
4514
4515 // Keep alive closure.
4516 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4517
4518 // Serial Complete GC closure
4519 G1STWDrainQueueClosure drain_queue(this, pss);
4520
4521 // Setup the soft refs policy...
4522 rp->setup_policy(false);
4523
4524 ReferenceProcessorStats stats;
4525 if (!rp->processing_is_mt()) {
4526 // Serial reference processing...
4527 stats = rp->process_discovered_references(&is_alive,
4528 &keep_alive,
4529 &drain_queue,
4530 NULL,
4531 _gc_timer_stw);
4532 } else {
4533 uint no_of_gc_workers = workers()->active_workers();
4534
4535 // Parallel reference processing
4536 assert(rp->num_q() == no_of_gc_workers, "sanity");
4537 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4538
4539 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4540 stats = rp->process_discovered_references(&is_alive,
4541 &keep_alive,
4542 &drain_queue,
4543 &par_task_executor,
4544 _gc_timer_stw);
4545 }
4546
4547 _gc_tracer_stw->report_gc_reference_stats(stats);
4548
4549 // We have completed copying any necessary live referent objects.
4550 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4551
4552 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4553 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4554 }
4555
4556 // Weak Reference processing during an evacuation pause (part 2).
4557 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4558 double ref_enq_start = os::elapsedTime();
4559
4560 ReferenceProcessor* rp = _ref_processor_stw;
4561 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4562
4563 // Now enqueue any remaining on the discovered lists on to
4564 // the pending list.
4565 if (!rp->processing_is_mt()) {
4566 // Serial reference processing...
4567 rp->enqueue_discovered_references();
4568 } else {
4569 // Parallel reference enqueueing
4570
4571 uint n_workers = workers()->active_workers();
4572
4573 assert(rp->num_q() == n_workers, "sanity");
4574 assert(n_workers <= rp->max_num_q(), "sanity");
4575
4576 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4577 rp->enqueue_discovered_references(&par_task_executor);
4578 }
4579
4580 rp->verify_no_references_recorded();
4581 assert(!rp->discovery_enabled(), "should have been disabled");
4582
4583 // FIXME
4584 // CM's reference processing also cleans up the string and symbol tables.
4585 // Should we do that here also? We could, but it is a serial operation
4586 // and could significantly increase the pause time.
4587
4588 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4589 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4590 }
4591
4592 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4593 double merge_pss_time_start = os::elapsedTime();
4594 per_thread_states->flush();
4595 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4596 }
4597
4598 void G1CollectedHeap::pre_evacuate_collection_set() {
4599 _expand_heap_after_alloc_failure = true;
4600 _evacuation_failed = false;
4601
4602 // Disable the hot card cache.
4603 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4604 hot_card_cache->reset_hot_cache_claimed_index();
4605 hot_card_cache->set_use_cache(false);
4606
4607 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4608 }
4609
4610 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4611 // Should G1EvacuationFailureALot be in effect for this GC?
4612 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4613
4614 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4615 double start_par_time_sec = os::elapsedTime();
4616 double end_par_time_sec;
4617
4618 {
4619 const uint n_workers = workers()->active_workers();
4620 G1RootProcessor root_processor(this, n_workers);
4621 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4622 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4623 if (collector_state()->during_initial_mark_pause()) {
4624 ClassLoaderDataGraph::clear_claimed_marks();
4625 }
4626
4627 print_termination_stats_hdr();
4628
4629 workers()->run_task(&g1_par_task);
4630 end_par_time_sec = os::elapsedTime();
4631
4632 // Closing the inner scope will execute the destructor
4633 // for the G1RootProcessor object. We record the current
4634 // elapsed time before closing the scope so that time
4635 // taken for the destructor is NOT included in the
4636 // reported parallel time.
4637 }
4638
4639 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4640
4641 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4642 phase_times->record_par_time(par_time_ms);
4643
4644 double code_root_fixup_time_ms =
4645 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4646 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4647 }
4648
4649 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4650 // Process any discovered reference objects - we have
4651 // to do this _before_ we retire the GC alloc regions
4652 // as we may have to copy some 'reachable' referent
4653 // objects (and their reachable sub-graphs) that were
4654 // not copied during the pause.
4655 if (g1_policy()->should_process_references()) {
4656 preserve_cm_referents(per_thread_states);
4657 process_discovered_references(per_thread_states);
4658 } else {
4659 ref_processor_stw()->verify_no_references_recorded();
4660 process_weak_jni_handles();
4661 }
4662
4663 if (G1StringDedup::is_enabled()) {
4664 double fixup_start = os::elapsedTime();
4665
4666 G1STWIsAliveClosure is_alive(this);
4667 G1KeepAliveClosure keep_alive(this);
4668 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4669
4670 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4671 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4672 }
4673
4674 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4675
4676 if (evacuation_failed()) {
4677 restore_after_evac_failure();
4678
4679 // Reset the G1EvacuationFailureALot counters and flags
4680 // Note: the values are reset only when an actual
4681 // evacuation failure occurs.
4682 NOT_PRODUCT(reset_evacuation_should_fail();)
4683 }
4684
4685 // Enqueue any remaining references remaining on the STW
4686 // reference processor's discovered lists. We need to do
4687 // this after the card table is cleaned (and verified) as
4688 // the act of enqueueing entries on to the pending list
4689 // will log these updates (and dirty their associated
4690 // cards). We need these updates logged to update any
4691 // RSets.
4692 if (g1_policy()->should_process_references()) {
4693 enqueue_discovered_references(per_thread_states);
4694 } else {
4695 g1_policy()->phase_times()->record_ref_enq_time(0);
4696 }
4697
4698 _allocator->release_gc_alloc_regions(evacuation_info);
4699
4700 merge_per_thread_state_info(per_thread_states);
4701
4702 // Reset and re-enable the hot card cache.
4703 // Note the counts for the cards in the regions in the
4704 // collection set are reset when the collection set is freed.
4705 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4706 hot_card_cache->reset_hot_cache();
4707 hot_card_cache->set_use_cache(true);
4708
4709 purge_code_root_memory();
4710
4711 redirty_logged_cards();
4712 #if defined(COMPILER2) || INCLUDE_JVMCI
4713 DerivedPointerTable::update_pointers();
4714 #endif
4715 }
4716
4717 void G1CollectedHeap::record_obj_copy_mem_stats() {
4718 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4719
4720 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4721 create_g1_evac_summary(&_old_evac_stats));
4722 }
4723
4724 void G1CollectedHeap::free_region(HeapRegion* hr,
4725 FreeRegionList* free_list,
4726 bool par,
4727 bool locked) {
4728 assert(!hr->is_free(), "the region should not be free");
4729 assert(!hr->is_empty(), "the region should not be empty");
4730 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4731 assert(free_list != NULL, "pre-condition");
4732
4733 if (G1VerifyBitmaps) {
4734 MemRegion mr(hr->bottom(), hr->end());
4735 concurrent_mark()->clearRangePrevBitmap(mr);
4736 }
4737
4738 // Clear the card counts for this region.
4739 // Note: we only need to do this if the region is not young
4740 // (since we don't refine cards in young regions).
4741 if (!hr->is_young()) {
4742 _cg1r->hot_card_cache()->reset_card_counts(hr);
4743 }
4744 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4745 free_list->add_ordered(hr);
4746 }
4747
4748 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4749 FreeRegionList* free_list,
4750 bool par) {
4751 assert(hr->is_humongous(), "this is only for humongous regions");
4752 assert(free_list != NULL, "pre-condition");
4753 hr->clear_humongous();
4754 free_region(hr, free_list, par);
4755 }
4756
4757 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4758 const uint humongous_regions_removed) {
4759 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4760 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4761 _old_set.bulk_remove(old_regions_removed);
4762 _humongous_set.bulk_remove(humongous_regions_removed);
4763 }
4764
4765 }
4766
4767 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4768 assert(list != NULL, "list can't be null");
4769 if (!list->is_empty()) {
4770 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4771 _hrm.insert_list_into_free_list(list);
4772 }
4773 }
4774
4775 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4776 decrease_used(bytes);
4777 }
4778
4779 class G1ParCleanupCTTask : public AbstractGangTask {
4780 G1SATBCardTableModRefBS* _ct_bs;
4781 G1CollectedHeap* _g1h;
4782 HeapRegion* volatile _su_head;
4783 public:
4784 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4785 G1CollectedHeap* g1h) :
4786 AbstractGangTask("G1 Par Cleanup CT Task"),
4787 _ct_bs(ct_bs), _g1h(g1h) { }
4788
4789 void work(uint worker_id) {
4790 HeapRegion* r;
4791 while (r = _g1h->pop_dirty_cards_region()) {
4792 clear_cards(r);
4793 }
4794 }
4795
4796 void clear_cards(HeapRegion* r) {
4797 // Cards of the survivors should have already been dirtied.
4798 if (!r->is_survivor()) {
4799 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4800 }
4801 }
4802 };
4803
4804 class G1ParScrubRemSetTask: public AbstractGangTask {
4805 protected:
4806 G1RemSet* _g1rs;
4807 BitMap* _region_bm;
4808 BitMap* _card_bm;
4809 HeapRegionClaimer _hrclaimer;
4810
4811 public:
4812 G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) :
4813 AbstractGangTask("G1 ScrubRS"),
4814 _g1rs(g1_rs),
4815 _region_bm(region_bm),
4816 _card_bm(card_bm),
4817 _hrclaimer(num_workers) {
4818 }
4819
4820 void work(uint worker_id) {
4821 _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
4822 }
4823 };
4824
4825 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) {
4826 uint num_workers = workers()->active_workers();
4827 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers);
4828 workers()->run_task(&g1_par_scrub_rs_task);
4829 }
4830
4831 void G1CollectedHeap::cleanUpCardTable() {
4832 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4833 double start = os::elapsedTime();
4834
4835 {
4836 // Iterate over the dirty cards region list.
4837 G1ParCleanupCTTask cleanup_task(ct_bs, this);
4838
4839 workers()->run_task(&cleanup_task);
4840 #ifndef PRODUCT
4841 _verifier->verify_card_table_cleanup();
4842 #endif
4843 }
4844
4845 double elapsed = os::elapsedTime() - start;
4846 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4847 }
4848
4849 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4850 size_t pre_used = 0;
4851 FreeRegionList local_free_list("Local List for CSet Freeing");
4852
4853 double young_time_ms = 0.0;
4854 double non_young_time_ms = 0.0;
4855
4856 // Since the collection set is a superset of the the young list,
4857 // all we need to do to clear the young list is clear its
4858 // head and length, and unlink any young regions in the code below
4859 _young_list->clear();
4860
4861 G1CollectorPolicy* policy = g1_policy();
4862
4863 double start_sec = os::elapsedTime();
4864 bool non_young = true;
4865
4866 HeapRegion* cur = cs_head;
4867 int age_bound = -1;
4868 size_t rs_lengths = 0;
4869
4870 while (cur != NULL) {
4871 assert(!is_on_master_free_list(cur), "sanity");
4872 if (non_young) {
4873 if (cur->is_young()) {
4874 double end_sec = os::elapsedTime();
4875 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4876 non_young_time_ms += elapsed_ms;
4877
4878 start_sec = os::elapsedTime();
4879 non_young = false;
4880 }
4881 } else {
4882 if (!cur->is_young()) {
4883 double end_sec = os::elapsedTime();
4884 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4885 young_time_ms += elapsed_ms;
4886
4887 start_sec = os::elapsedTime();
4888 non_young = true;
4889 }
4890 }
4891
4892 rs_lengths += cur->rem_set()->occupied_locked();
4893
4894 HeapRegion* next = cur->next_in_collection_set();
4895 assert(cur->in_collection_set(), "bad CS");
4896 cur->set_next_in_collection_set(NULL);
4897 clear_in_cset(cur);
4898
4899 if (cur->is_young()) {
4900 int index = cur->young_index_in_cset();
4901 assert(index != -1, "invariant");
4902 assert((uint) index < collection_set()->young_region_length(), "invariant");
4903 size_t words_survived = surviving_young_words[index];
4904 cur->record_surv_words_in_group(words_survived);
4905
4906 // At this point the we have 'popped' cur from the collection set
4907 // (linked via next_in_collection_set()) but it is still in the
4908 // young list (linked via next_young_region()). Clear the
4909 // _next_young_region field.
4910 cur->set_next_young_region(NULL);
4911 } else {
4912 int index = cur->young_index_in_cset();
4913 assert(index == -1, "invariant");
4914 }
4915
4916 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4917 (!cur->is_young() && cur->young_index_in_cset() == -1),
4918 "invariant" );
4919
4920 if (!cur->evacuation_failed()) {
4921 MemRegion used_mr = cur->used_region();
4922
4923 // And the region is empty.
4924 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4925 pre_used += cur->used();
4926 free_region(cur, &local_free_list, false /* par */, true /* locked */);
4927 } else {
4928 cur->uninstall_surv_rate_group();
4929 if (cur->is_young()) {
4930 cur->set_young_index_in_cset(-1);
4931 }
4932 cur->set_evacuation_failed(false);
4933 // When moving a young gen region to old gen, we "allocate" that whole region
4934 // there. This is in addition to any already evacuated objects. Notify the
4935 // policy about that.
4936 // Old gen regions do not cause an additional allocation: both the objects
4937 // still in the region and the ones already moved are accounted for elsewhere.
4938 if (cur->is_young()) {
4939 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4940 }
4941 // The region is now considered to be old.
4942 cur->set_old();
4943 // Do some allocation statistics accounting. Regions that failed evacuation
4944 // are always made old, so there is no need to update anything in the young
4945 // gen statistics, but we need to update old gen statistics.
4946 size_t used_words = cur->marked_bytes() / HeapWordSize;
4947 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4948 _old_set.add(cur);
4949 evacuation_info.increment_collectionset_used_after(cur->used());
4950 }
4951 cur = next;
4952 }
4953
4954 evacuation_info.set_regions_freed(local_free_list.length());
4955 policy->record_max_rs_lengths(rs_lengths);
4956 policy->cset_regions_freed();
4957
4958 double end_sec = os::elapsedTime();
4959 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4960
4961 if (non_young) {
4962 non_young_time_ms += elapsed_ms;
4963 } else {
4964 young_time_ms += elapsed_ms;
4965 }
4966
4967 prepend_to_freelist(&local_free_list);
4968 decrement_summary_bytes(pre_used);
4969 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4970 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4971 }
4972
4973 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4974 private:
4975 FreeRegionList* _free_region_list;
4976 HeapRegionSet* _proxy_set;
4977 uint _humongous_regions_removed;
4978 size_t _freed_bytes;
4979 public:
4980
4981 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4982 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4983 }
4984
4985 virtual void doHeapRegion(HeapRegion* r) {
4986 if (!r->is_starts_humongous()) {
4987 return;
4988 }
4989
4990 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4991
4992 oop obj = (oop)r->bottom();
4993 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4994
4995 // The following checks whether the humongous object is live are sufficient.
4996 // The main additional check (in addition to having a reference from the roots
4997 // or the young gen) is whether the humongous object has a remembered set entry.
4998 //
4999 // A humongous object cannot be live if there is no remembered set for it
5000 // because:
5001 // - there can be no references from within humongous starts regions referencing
5002 // the object because we never allocate other objects into them.
5003 // (I.e. there are no intra-region references that may be missed by the
5004 // remembered set)
5005 // - as soon there is a remembered set entry to the humongous starts region
5006 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5007 // until the end of a concurrent mark.
5008 //
5009 // It is not required to check whether the object has been found dead by marking
5010 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5011 // all objects allocated during that time are considered live.
5012 // SATB marking is even more conservative than the remembered set.
5013 // So if at this point in the collection there is no remembered set entry,
5014 // nobody has a reference to it.
5015 // At the start of collection we flush all refinement logs, and remembered sets
5016 // are completely up-to-date wrt to references to the humongous object.
5017 //
5018 // Other implementation considerations:
5019 // - never consider object arrays at this time because they would pose
5020 // considerable effort for cleaning up the the remembered sets. This is
5021 // required because stale remembered sets might reference locations that
5022 // are currently allocated into.
5023 uint region_idx = r->hrm_index();
5024 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5025 !r->rem_set()->is_empty()) {
5026 log_debug(gc, humongous)("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",
5027 region_idx,
5028 (size_t)obj->size() * HeapWordSize,
5029 p2i(r->bottom()),
5030 r->rem_set()->occupied(),
5031 r->rem_set()->strong_code_roots_list_length(),
5032 next_bitmap->isMarked(r->bottom()),
5033 g1h->is_humongous_reclaim_candidate(region_idx),
5034 obj->is_typeArray()
5035 );
5036 return;
5037 }
5038
5039 guarantee(obj->is_typeArray(),
5040 "Only eagerly reclaiming type arrays is supported, but the object "
5041 PTR_FORMAT " is not.", p2i(r->bottom()));
5042
5043 log_debug(gc, humongous)("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",
5044 region_idx,
5045 (size_t)obj->size() * HeapWordSize,
5046 p2i(r->bottom()),
5047 r->rem_set()->occupied(),
5048 r->rem_set()->strong_code_roots_list_length(),
5049 next_bitmap->isMarked(r->bottom()),
5050 g1h->is_humongous_reclaim_candidate(region_idx),
5051 obj->is_typeArray()
5052 );
5053
5054 // Need to clear mark bit of the humongous object if already set.
5055 if (next_bitmap->isMarked(r->bottom())) {
5056 next_bitmap->clear(r->bottom());
5057 }
5058 do {
5059 HeapRegion* next = g1h->next_region_in_humongous(r);
5060 _freed_bytes += r->used();
5061 r->set_containing_set(NULL);
5062 _humongous_regions_removed++;
5063 g1h->free_humongous_region(r, _free_region_list, false);
5064 r = next;
5065 } while (r != NULL);
5066 }
5067
5068 uint humongous_free_count() {
5069 return _humongous_regions_removed;
5070 }
5071
5072 size_t bytes_freed() const {
5073 return _freed_bytes;
5074 }
5075 };
5076
5077 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5078 assert_at_safepoint(true);
5079
5080 if (!G1EagerReclaimHumongousObjects ||
5081 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5082 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5083 return;
5084 }
5085
5086 double start_time = os::elapsedTime();
5087
5088 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5089
5090 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5091 heap_region_iterate(&cl);
5092
5093 remove_from_old_sets(0, cl.humongous_free_count());
5094
5095 G1HRPrinter* hrp = hr_printer();
5096 if (hrp->is_active()) {
5097 FreeRegionListIterator iter(&local_cleanup_list);
5098 while (iter.more_available()) {
5099 HeapRegion* hr = iter.get_next();
5100 hrp->cleanup(hr);
5101 }
5102 }
5103
5104 prepend_to_freelist(&local_cleanup_list);
5105 decrement_summary_bytes(cl.bytes_freed());
5106
5107 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5108 cl.humongous_free_count());
5109 }
5110
5111 // This routine is similar to the above but does not record
5112 // any policy statistics or update free lists; we are abandoning
5113 // the current incremental collection set in preparation of a
5114 // full collection. After the full GC we will start to build up
5115 // the incremental collection set again.
5116 // This is only called when we're doing a full collection
5117 // and is immediately followed by the tearing down of the young list.
5118
5119 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5120 HeapRegion* cur = cs_head;
5121
5122 while (cur != NULL) {
5123 HeapRegion* next = cur->next_in_collection_set();
5124 assert(cur->in_collection_set(), "bad CS");
5125 cur->set_next_in_collection_set(NULL);
5126 clear_in_cset(cur);
5127 cur->set_young_index_in_cset(-1);
5128 cur = next;
5129 }
5130 }
5131
5132 void G1CollectedHeap::set_free_regions_coming() {
5133 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5134
5135 assert(!free_regions_coming(), "pre-condition");
5136 _free_regions_coming = true;
5137 }
5138
5139 void G1CollectedHeap::reset_free_regions_coming() {
5140 assert(free_regions_coming(), "pre-condition");
5141
5142 {
5143 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5144 _free_regions_coming = false;
5145 SecondaryFreeList_lock->notify_all();
5146 }
5147
5148 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5149 }
5150
5151 void G1CollectedHeap::wait_while_free_regions_coming() {
5152 // Most of the time we won't have to wait, so let's do a quick test
5153 // first before we take the lock.
5154 if (!free_regions_coming()) {
5155 return;
5156 }
5157
5158 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5159
5160 {
5161 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5162 while (free_regions_coming()) {
5163 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5164 }
5165 }
5166
5167 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5168 }
5169
5170 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5171 return _allocator->is_retained_old_region(hr);
5172 }
5173
5174 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5175 _young_list->push_region(hr);
5176 }
5177
5178 class NoYoungRegionsClosure: public HeapRegionClosure {
5179 private:
5180 bool _success;
5181 public:
5182 NoYoungRegionsClosure() : _success(true) { }
5183 void doHeapRegion(HeapRegion* r) {
5184 if (r->is_young()) {
5185 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5186 p2i(r->bottom()), p2i(r->end()));
5187 _success = false;
5188 }
5189 }
5190 bool success() { return _success; }
5191 };
5192
5193 bool G1CollectedHeap::check_young_list_empty(bool check_heap) {
5194 bool ret = _young_list->check_list_empty();
5195
5196 if (check_heap) {
5197 NoYoungRegionsClosure closure;
5198 heap_region_iterate(&closure);
5199 ret = ret && closure.success();
5200 }
5201
5202 return ret;
5203 }
5204
5205 class TearDownRegionSetsClosure : public HeapRegionClosure {
5206 private:
5207 HeapRegionSet *_old_set;
5208
5209 public:
5210 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5211
5212 void doHeapRegion(HeapRegion* r) {
5213 if (r->is_old()) {
5214 _old_set->remove(r);
5215 } else {
5216 // We ignore free regions, we'll empty the free list afterwards.
5217 // We ignore young regions, we'll empty the young list afterwards.
5218 // We ignore humongous regions, we're not tearing down the
5219 // humongous regions set.
5220 assert(r->is_free() || r->is_young() || r->is_humongous(),
5221 "it cannot be another type");
5222 }
5223 }
5224
5225 ~TearDownRegionSetsClosure() {
5226 assert(_old_set->is_empty(), "post-condition");
5227 }
5228 };
5229
5230 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5231 assert_at_safepoint(true /* should_be_vm_thread */);
5232
5233 if (!free_list_only) {
5234 TearDownRegionSetsClosure cl(&_old_set);
5235 heap_region_iterate(&cl);
5236
5237 // Note that emptying the _young_list is postponed and instead done as
5238 // the first step when rebuilding the regions sets again. The reason for
5239 // this is that during a full GC string deduplication needs to know if
5240 // a collected region was young or old when the full GC was initiated.
5241 }
5242 _hrm.remove_all_free_regions();
5243 }
5244
5245 void G1CollectedHeap::increase_used(size_t bytes) {
5246 _summary_bytes_used += bytes;
5247 }
5248
5249 void G1CollectedHeap::decrease_used(size_t bytes) {
5250 assert(_summary_bytes_used >= bytes,
5251 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5252 _summary_bytes_used, bytes);
5253 _summary_bytes_used -= bytes;
5254 }
5255
5256 void G1CollectedHeap::set_used(size_t bytes) {
5257 _summary_bytes_used = bytes;
5258 }
5259
5260 class RebuildRegionSetsClosure : public HeapRegionClosure {
5261 private:
5262 bool _free_list_only;
5263 HeapRegionSet* _old_set;
5264 HeapRegionManager* _hrm;
5265 size_t _total_used;
5266
5267 public:
5268 RebuildRegionSetsClosure(bool free_list_only,
5269 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5270 _free_list_only(free_list_only),
5271 _old_set(old_set), _hrm(hrm), _total_used(0) {
5272 assert(_hrm->num_free_regions() == 0, "pre-condition");
5273 if (!free_list_only) {
5274 assert(_old_set->is_empty(), "pre-condition");
5275 }
5276 }
5277
5278 void doHeapRegion(HeapRegion* r) {
5279 if (r->is_empty()) {
5280 // Add free regions to the free list
5281 r->set_free();
5282 r->set_allocation_context(AllocationContext::system());
5283 _hrm->insert_into_free_list(r);
5284 } else if (!_free_list_only) {
5285 assert(!r->is_young(), "we should not come across young regions");
5286
5287 if (r->is_humongous()) {
5288 // We ignore humongous regions. We left the humongous set unchanged.
5289 } else {
5290 // Objects that were compacted would have ended up on regions
5291 // that were previously old or free. Archive regions (which are
5292 // old) will not have been touched.
5293 assert(r->is_free() || r->is_old(), "invariant");
5294 // We now consider them old, so register as such. Leave
5295 // archive regions set that way, however, while still adding
5296 // them to the old set.
5297 if (!r->is_archive()) {
5298 r->set_old();
5299 }
5300 _old_set->add(r);
5301 }
5302 _total_used += r->used();
5303 }
5304 }
5305
5306 size_t total_used() {
5307 return _total_used;
5308 }
5309 };
5310
5311 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5312 assert_at_safepoint(true /* should_be_vm_thread */);
5313
5314 if (!free_list_only) {
5315 _young_list->empty_list();
5316 }
5317
5318 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5319 heap_region_iterate(&cl);
5320
5321 if (!free_list_only) {
5322 set_used(cl.total_used());
5323 if (_archive_allocator != NULL) {
5324 _archive_allocator->clear_used();
5325 }
5326 }
5327 assert(used_unlocked() == recalculate_used(),
5328 "inconsistent used_unlocked(), "
5329 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5330 used_unlocked(), recalculate_used());
5331 }
5332
5333 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5334 _refine_cte_cl->set_concurrent(concurrent);
5335 }
5336
5337 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5338 HeapRegion* hr = heap_region_containing(p);
5339 return hr->is_in(p);
5340 }
5341
5342 // Methods for the mutator alloc region
5343
5344 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5345 bool force) {
5346 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5347 assert(!force || g1_policy()->can_expand_young_list(),
5348 "if force is true we should be able to expand the young list");
5349 bool young_list_full = g1_policy()->is_young_list_full();
5350 if (force || !young_list_full) {
5351 HeapRegion* new_alloc_region = new_region(word_size,
5352 false /* is_old */,
5353 false /* do_expand */);
5354 if (new_alloc_region != NULL) {
5355 set_region_short_lived_locked(new_alloc_region);
5356 _hr_printer.alloc(new_alloc_region, young_list_full);
5357 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5358 return new_alloc_region;
5359 }
5360 }
5361 return NULL;
5362 }
5363
5364 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5365 size_t allocated_bytes) {
5366 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5367 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5368
5369 collection_set()->add_eden_region(alloc_region);
5370 increase_used(allocated_bytes);
5371 _hr_printer.retire(alloc_region);
5372 // We update the eden sizes here, when the region is retired,
5373 // instead of when it's allocated, since this is the point that its
5374 // used space has been recored in _summary_bytes_used.
5375 g1mm()->update_eden_size();
5376 }
5377
5378 // Methods for the GC alloc regions
5379
5380 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5381 uint count,
5382 InCSetState dest) {
5383 assert(FreeList_lock->owned_by_self(), "pre-condition");
5384
5385 if (count < g1_policy()->max_regions(dest)) {
5386 const bool is_survivor = (dest.is_young());
5387 HeapRegion* new_alloc_region = new_region(word_size,
5388 !is_survivor,
5389 true /* do_expand */);
5390 if (new_alloc_region != NULL) {
5391 // We really only need to do this for old regions given that we
5392 // should never scan survivors. But it doesn't hurt to do it
5393 // for survivors too.
5394 new_alloc_region->record_timestamp();
5395 if (is_survivor) {
5396 new_alloc_region->set_survivor();
5397 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5398 } else {
5399 new_alloc_region->set_old();
5400 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5401 }
5402 _hr_printer.alloc(new_alloc_region);
5403 bool during_im = collector_state()->during_initial_mark_pause();
5404 new_alloc_region->note_start_of_copying(during_im);
5405 return new_alloc_region;
5406 }
5407 }
5408 return NULL;
5409 }
5410
5411 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5412 size_t allocated_bytes,
5413 InCSetState dest) {
5414 bool during_im = collector_state()->during_initial_mark_pause();
5415 alloc_region->note_end_of_copying(during_im);
5416 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5417 if (dest.is_young()) {
5418 young_list()->add_survivor_region(alloc_region);
5419 } else {
5420 _old_set.add(alloc_region);
5421 }
5422 _hr_printer.retire(alloc_region);
5423 }
5424
5425 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5426 bool expanded = false;
5427 uint index = _hrm.find_highest_free(&expanded);
5428
5429 if (index != G1_NO_HRM_INDEX) {
5430 if (expanded) {
5431 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5432 HeapRegion::GrainWords * HeapWordSize);
5433 }
5434 _hrm.allocate_free_regions_starting_at(index, 1);
5435 return region_at(index);
5436 }
5437 return NULL;
5438 }
5439
5440 // Optimized nmethod scanning
5441
5442 class RegisterNMethodOopClosure: public OopClosure {
5443 G1CollectedHeap* _g1h;
5444 nmethod* _nm;
5445
5446 template <class T> void do_oop_work(T* p) {
5447 T heap_oop = oopDesc::load_heap_oop(p);
5448 if (!oopDesc::is_null(heap_oop)) {
5449 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5450 HeapRegion* hr = _g1h->heap_region_containing(obj);
5451 assert(!hr->is_continues_humongous(),
5452 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5453 " starting at " HR_FORMAT,
5454 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5455
5456 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5457 hr->add_strong_code_root_locked(_nm);
5458 }
5459 }
5460
5461 public:
5462 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5463 _g1h(g1h), _nm(nm) {}
5464
5465 void do_oop(oop* p) { do_oop_work(p); }
5466 void do_oop(narrowOop* p) { do_oop_work(p); }
5467 };
5468
5469 class UnregisterNMethodOopClosure: public OopClosure {
5470 G1CollectedHeap* _g1h;
5471 nmethod* _nm;
5472
5473 template <class T> void do_oop_work(T* p) {
5474 T heap_oop = oopDesc::load_heap_oop(p);
5475 if (!oopDesc::is_null(heap_oop)) {
5476 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5477 HeapRegion* hr = _g1h->heap_region_containing(obj);
5478 assert(!hr->is_continues_humongous(),
5479 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5480 " starting at " HR_FORMAT,
5481 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5482
5483 hr->remove_strong_code_root(_nm);
5484 }
5485 }
5486
5487 public:
5488 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5489 _g1h(g1h), _nm(nm) {}
5490
5491 void do_oop(oop* p) { do_oop_work(p); }
5492 void do_oop(narrowOop* p) { do_oop_work(p); }
5493 };
5494
5495 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5496 CollectedHeap::register_nmethod(nm);
5497
5498 guarantee(nm != NULL, "sanity");
5499 RegisterNMethodOopClosure reg_cl(this, nm);
5500 nm->oops_do(®_cl);
5501 }
5502
5503 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5504 CollectedHeap::unregister_nmethod(nm);
5505
5506 guarantee(nm != NULL, "sanity");
5507 UnregisterNMethodOopClosure reg_cl(this, nm);
5508 nm->oops_do(®_cl, true);
5509 }
5510
5511 void G1CollectedHeap::purge_code_root_memory() {
5512 double purge_start = os::elapsedTime();
5513 G1CodeRootSet::purge();
5514 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5515 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5516 }
5517
5518 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5519 G1CollectedHeap* _g1h;
5520
5521 public:
5522 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5523 _g1h(g1h) {}
5524
5525 void do_code_blob(CodeBlob* cb) {
5526 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5527 if (nm == NULL) {
5528 return;
5529 }
5530
5531 if (ScavengeRootsInCode) {
5532 _g1h->register_nmethod(nm);
5533 }
5534 }
5535 };
5536
5537 void G1CollectedHeap::rebuild_strong_code_roots() {
5538 RebuildStrongCodeRootClosure blob_cl(this);
5539 CodeCache::blobs_do(&blob_cl);
5540 }