1 /*
2 * Copyright (c) 2001, 2019, 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/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1BarrierSet.hpp"
33 #include "gc/g1/g1CollectedHeap.inline.hpp"
34 #include "gc/g1/g1CollectionSet.hpp"
35 #include "gc/g1/g1CollectorPolicy.hpp"
36 #include "gc/g1/g1CollectorState.hpp"
37 #include "gc/g1/g1ConcurrentRefine.hpp"
38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
40 #include "gc/g1/g1DirtyCardQueue.hpp"
41 #include "gc/g1/g1EvacStats.inline.hpp"
42 #include "gc/g1/g1FullCollector.hpp"
43 #include "gc/g1/g1GCPhaseTimes.hpp"
44 #include "gc/g1/g1HeapSizingPolicy.hpp"
45 #include "gc/g1/g1HeapTransition.hpp"
46 #include "gc/g1/g1HeapVerifier.hpp"
47 #include "gc/g1/g1HotCardCache.hpp"
48 #include "gc/g1/g1MemoryPool.hpp"
49 #include "gc/g1/g1OopClosures.inline.hpp"
50 #include "gc/g1/g1ParScanThreadState.inline.hpp"
51 #include "gc/g1/g1Policy.hpp"
52 #include "gc/g1/g1RegionToSpaceMapper.hpp"
53 #include "gc/g1/g1RemSet.hpp"
54 #include "gc/g1/g1RootClosures.hpp"
55 #include "gc/g1/g1RootProcessor.hpp"
56 #include "gc/g1/g1SATBMarkQueueSet.hpp"
57 #include "gc/g1/g1StringDedup.hpp"
58 #include "gc/g1/g1ThreadLocalData.hpp"
59 #include "gc/g1/g1YCTypes.hpp"
60 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
61 #include "gc/g1/g1VMOperations.hpp"
62 #include "gc/g1/heapRegion.inline.hpp"
63 #include "gc/g1/heapRegionRemSet.hpp"
64 #include "gc/g1/heapRegionSet.inline.hpp"
65 #include "gc/shared/gcBehaviours.hpp"
66 #include "gc/shared/gcHeapSummary.hpp"
67 #include "gc/shared/gcId.hpp"
68 #include "gc/shared/gcLocker.hpp"
69 #include "gc/shared/gcTimer.hpp"
70 #include "gc/shared/gcTrace.hpp"
71 #include "gc/shared/gcTraceTime.inline.hpp"
72 #include "gc/shared/generationSpec.hpp"
73 #include "gc/shared/isGCActiveMark.hpp"
74 #include "gc/shared/oopStorageParState.hpp"
75 #include "gc/shared/parallelCleaning.hpp"
76 #include "gc/shared/preservedMarks.inline.hpp"
77 #include "gc/shared/suspendibleThreadSet.hpp"
78 #include "gc/shared/referenceProcessor.inline.hpp"
79 #include "gc/shared/taskqueue.inline.hpp"
80 #include "gc/shared/weakProcessor.inline.hpp"
81 #include "gc/shared/workerPolicy.hpp"
82 #include "logging/log.hpp"
83 #include "memory/allocation.hpp"
84 #include "memory/iterator.hpp"
85 #include "memory/resourceArea.hpp"
86 #include "oops/access.inline.hpp"
87 #include "oops/compressedOops.inline.hpp"
88 #include "oops/oop.inline.hpp"
89 #include "runtime/atomic.hpp"
90 #include "runtime/flags/flagSetting.hpp"
91 #include "runtime/handles.inline.hpp"
92 #include "runtime/init.hpp"
93 #include "runtime/orderAccess.hpp"
94 #include "runtime/threadSMR.hpp"
95 #include "runtime/vmThread.hpp"
96 #include "utilities/align.hpp"
97 #include "utilities/globalDefinitions.hpp"
98 #include "utilities/stack.inline.hpp"
99
100 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
101
102 // INVARIANTS/NOTES
103 //
104 // All allocation activity covered by the G1CollectedHeap interface is
105 // serialized by acquiring the HeapLock. This happens in mem_allocate
106 // and allocate_new_tlab, which are the "entry" points to the
107 // allocation code from the rest of the JVM. (Note that this does not
108 // apply to TLAB allocation, which is not part of this interface: it
109 // is done by clients of this interface.)
110
111 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
112 private:
113 size_t _num_dirtied;
114 G1CollectedHeap* _g1h;
115 G1CardTable* _g1_ct;
116
117 HeapRegion* region_for_card(CardValue* card_ptr) const {
118 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
119 }
120
121 bool will_become_free(HeapRegion* hr) const {
122 // A region will be freed by free_collection_set if the region is in the
123 // collection set and has not had an evacuation failure.
124 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
125 }
126
127 public:
128 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
129 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
130
131 bool do_card_ptr(CardValue* card_ptr, uint worker_i) {
132 HeapRegion* hr = region_for_card(card_ptr);
133
134 // Should only dirty cards in regions that won't be freed.
135 if (!will_become_free(hr)) {
136 *card_ptr = G1CardTable::dirty_card_val();
137 _num_dirtied++;
138 }
139
140 return true;
141 }
142
143 size_t num_dirtied() const { return _num_dirtied; }
144 };
145
146
147 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
148 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
149 }
150
151 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
152 // The from card cache is not the memory that is actually committed. So we cannot
153 // take advantage of the zero_filled parameter.
154 reset_from_card_cache(start_idx, num_regions);
155 }
156
157
158 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
159 MemRegion mr) {
160 return new HeapRegion(hrs_index, bot(), mr);
161 }
162
163 // Private methods.
164
165 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
166 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
167 "the only time we use this to allocate a humongous region is "
168 "when we are allocating a single humongous region");
169
170 HeapRegion* res = _hrm->allocate_free_region(type);
171
172 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
173 // Currently, only attempts to allocate GC alloc regions set
174 // do_expand to true. So, we should only reach here during a
175 // safepoint. If this assumption changes we might have to
176 // reconsider the use of _expand_heap_after_alloc_failure.
177 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
178
179 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
180 word_size * HeapWordSize);
181
182 if (expand(word_size * HeapWordSize)) {
183 // Given that expand() succeeded in expanding the heap, and we
184 // always expand the heap by an amount aligned to the heap
185 // region size, the free list should in theory not be empty.
186 // In either case allocate_free_region() will check for NULL.
187 res = _hrm->allocate_free_region(type);
188 } else {
189 _expand_heap_after_alloc_failure = false;
190 }
191 }
192 return res;
193 }
194
195 HeapWord*
196 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
197 uint num_regions,
198 size_t word_size) {
199 assert(first != G1_NO_HRM_INDEX, "pre-condition");
200 assert(is_humongous(word_size), "word_size should be humongous");
201 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
202
203 // Index of last region in the series.
204 uint last = first + num_regions - 1;
205
206 // We need to initialize the region(s) we just discovered. This is
207 // a bit tricky given that it can happen concurrently with
208 // refinement threads refining cards on these regions and
209 // potentially wanting to refine the BOT as they are scanning
210 // those cards (this can happen shortly after a cleanup; see CR
211 // 6991377). So we have to set up the region(s) carefully and in
212 // a specific order.
213
214 // The word size sum of all the regions we will allocate.
215 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
216 assert(word_size <= word_size_sum, "sanity");
217
218 // This will be the "starts humongous" region.
219 HeapRegion* first_hr = region_at(first);
220 // The header of the new object will be placed at the bottom of
221 // the first region.
222 HeapWord* new_obj = first_hr->bottom();
223 // This will be the new top of the new object.
224 HeapWord* obj_top = new_obj + word_size;
225
226 // First, we need to zero the header of the space that we will be
227 // allocating. When we update top further down, some refinement
228 // threads might try to scan the region. By zeroing the header we
229 // ensure that any thread that will try to scan the region will
230 // come across the zero klass word and bail out.
231 //
232 // NOTE: It would not have been correct to have used
233 // CollectedHeap::fill_with_object() and make the space look like
234 // an int array. The thread that is doing the allocation will
235 // later update the object header to a potentially different array
236 // type and, for a very short period of time, the klass and length
237 // fields will be inconsistent. This could cause a refinement
238 // thread to calculate the object size incorrectly.
239 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
240
241 // Next, pad out the unused tail of the last region with filler
242 // objects, for improved usage accounting.
243 // How many words we use for filler objects.
244 size_t word_fill_size = word_size_sum - word_size;
245
246 // How many words memory we "waste" which cannot hold a filler object.
247 size_t words_not_fillable = 0;
248
249 if (word_fill_size >= min_fill_size()) {
250 fill_with_objects(obj_top, word_fill_size);
251 } else if (word_fill_size > 0) {
252 // We have space to fill, but we cannot fit an object there.
253 words_not_fillable = word_fill_size;
254 word_fill_size = 0;
255 }
256
257 // We will set up the first region as "starts humongous". This
258 // will also update the BOT covering all the regions to reflect
259 // that there is a single object that starts at the bottom of the
260 // first region.
261 first_hr->set_starts_humongous(obj_top, word_fill_size);
262 _policy->remset_tracker()->update_at_allocate(first_hr);
263 // Then, if there are any, we will set up the "continues
264 // humongous" regions.
265 HeapRegion* hr = NULL;
266 for (uint i = first + 1; i <= last; ++i) {
267 hr = region_at(i);
268 hr->set_continues_humongous(first_hr);
269 _policy->remset_tracker()->update_at_allocate(hr);
270 }
271
272 // Up to this point no concurrent thread would have been able to
273 // do any scanning on any region in this series. All the top
274 // fields still point to bottom, so the intersection between
275 // [bottom,top] and [card_start,card_end] will be empty. Before we
276 // update the top fields, we'll do a storestore to make sure that
277 // no thread sees the update to top before the zeroing of the
278 // object header and the BOT initialization.
279 OrderAccess::storestore();
280
281 // Now, we will update the top fields of the "continues humongous"
282 // regions except the last one.
283 for (uint i = first; i < last; ++i) {
284 hr = region_at(i);
285 hr->set_top(hr->end());
286 }
287
288 hr = region_at(last);
289 // If we cannot fit a filler object, we must set top to the end
290 // of the humongous object, otherwise we cannot iterate the heap
291 // and the BOT will not be complete.
292 hr->set_top(hr->end() - words_not_fillable);
293
294 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
295 "obj_top should be in last region");
296
297 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
298
299 assert(words_not_fillable == 0 ||
300 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
301 "Miscalculation in humongous allocation");
302
303 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
304
305 for (uint i = first; i <= last; ++i) {
306 hr = region_at(i);
307 _humongous_set.add(hr);
308 _hr_printer.alloc(hr);
309 }
310
311 return new_obj;
312 }
313
314 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
315 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
316 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
317 }
318
319 // If could fit into free regions w/o expansion, try.
320 // Otherwise, if can expand, do so.
321 // Otherwise, if using ex regions might help, try with ex given back.
322 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
323 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
324
325 _verifier->verify_region_sets_optional();
326
327 uint first = G1_NO_HRM_INDEX;
328 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
329
330 if (obj_regions == 1) {
331 // Only one region to allocate, try to use a fast path by directly allocating
332 // from the free lists. Do not try to expand here, we will potentially do that
333 // later.
334 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
335 if (hr != NULL) {
336 first = hr->hrm_index();
337 }
338 } else {
339 // Policy: Try only empty regions (i.e. already committed first). Maybe we
340 // are lucky enough to find some.
341 first = _hrm->find_contiguous_only_empty(obj_regions);
342 if (first != G1_NO_HRM_INDEX) {
343 _hrm->allocate_free_regions_starting_at(first, obj_regions);
344 }
345 }
346
347 if (first == G1_NO_HRM_INDEX) {
348 // Policy: We could not find enough regions for the humongous object in the
349 // free list. Look through the heap to find a mix of free and uncommitted regions.
350 // If so, try expansion.
351 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
352 if (first != G1_NO_HRM_INDEX) {
353 // We found something. Make sure these regions are committed, i.e. expand
354 // the heap. Alternatively we could do a defragmentation GC.
355 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
356 word_size * HeapWordSize);
357
358 _hrm->expand_at(first, obj_regions, workers());
359 policy()->record_new_heap_size(num_regions());
360
361 #ifdef ASSERT
362 for (uint i = first; i < first + obj_regions; ++i) {
363 HeapRegion* hr = region_at(i);
364 assert(hr->is_free(), "sanity");
365 assert(hr->is_empty(), "sanity");
366 assert(is_on_master_free_list(hr), "sanity");
367 }
368 #endif
369 _hrm->allocate_free_regions_starting_at(first, obj_regions);
370 } else {
371 // Policy: Potentially trigger a defragmentation GC.
372 }
373 }
374
375 HeapWord* result = NULL;
376 if (first != G1_NO_HRM_INDEX) {
377 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
378 assert(result != NULL, "it should always return a valid result");
379
380 // A successful humongous object allocation changes the used space
381 // information of the old generation so we need to recalculate the
382 // sizes and update the jstat counters here.
383 g1mm()->update_sizes();
384 }
385
386 _verifier->verify_region_sets_optional();
387
388 return result;
389 }
390
391 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
392 size_t requested_size,
393 size_t* actual_size) {
394 assert_heap_not_locked_and_not_at_safepoint();
395 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
396
397 return attempt_allocation(min_size, requested_size, actual_size);
398 }
399
400 HeapWord*
401 G1CollectedHeap::mem_allocate(size_t word_size,
402 bool* gc_overhead_limit_was_exceeded) {
403 assert_heap_not_locked_and_not_at_safepoint();
404
405 if (is_humongous(word_size)) {
406 return attempt_allocation_humongous(word_size);
407 }
408 size_t dummy = 0;
409 return attempt_allocation(word_size, word_size, &dummy);
410 }
411
412 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
413 ResourceMark rm; // For retrieving the thread names in log messages.
414
415 // Make sure you read the note in attempt_allocation_humongous().
416
417 assert_heap_not_locked_and_not_at_safepoint();
418 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
419 "be called for humongous allocation requests");
420
421 // We should only get here after the first-level allocation attempt
422 // (attempt_allocation()) failed to allocate.
423
424 // We will loop until a) we manage to successfully perform the
425 // allocation or b) we successfully schedule a collection which
426 // fails to perform the allocation. b) is the only case when we'll
427 // return NULL.
428 HeapWord* result = NULL;
429 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
430 bool should_try_gc;
431 uint gc_count_before;
432
433 {
434 MutexLockerEx x(Heap_lock);
435 result = _allocator->attempt_allocation_locked(word_size);
436 if (result != NULL) {
437 return result;
438 }
439
440 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
441 // This is different to when only GCLocker::needs_gc() is set: try to avoid
442 // waiting because the GCLocker is active to not wait too long.
443 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
444 // No need for an ergo message here, can_expand_young_list() does this when
445 // it returns true.
446 result = _allocator->attempt_allocation_force(word_size);
447 if (result != NULL) {
448 return result;
449 }
450 }
451 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
452 // the GCLocker initiated GC has been performed and then retry. This includes
453 // the case when the GC Locker is not active but has not been performed.
454 should_try_gc = !GCLocker::needs_gc();
455 // Read the GC count while still holding the Heap_lock.
456 gc_count_before = total_collections();
457 }
458
459 if (should_try_gc) {
460 bool succeeded;
461 result = do_collection_pause(word_size, gc_count_before, &succeeded,
462 GCCause::_g1_inc_collection_pause);
463 if (result != NULL) {
464 assert(succeeded, "only way to get back a non-NULL result");
465 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
466 Thread::current()->name(), p2i(result));
467 return result;
468 }
469
470 if (succeeded) {
471 // We successfully scheduled a collection which failed to allocate. No
472 // point in trying to allocate further. We'll just return NULL.
473 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
474 SIZE_FORMAT " words", Thread::current()->name(), word_size);
475 return NULL;
476 }
477 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
478 Thread::current()->name(), word_size);
479 } else {
480 // Failed to schedule a collection.
481 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
482 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
483 SIZE_FORMAT " words", Thread::current()->name(), word_size);
484 return NULL;
485 }
486 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
487 // The GCLocker is either active or the GCLocker initiated
488 // GC has not yet been performed. Stall until it is and
489 // then retry the allocation.
490 GCLocker::stall_until_clear();
491 gclocker_retry_count += 1;
492 }
493
494 // We can reach here if we were unsuccessful in scheduling a
495 // collection (because another thread beat us to it) or if we were
496 // stalled due to the GC locker. In either can we should retry the
497 // allocation attempt in case another thread successfully
498 // performed a collection and reclaimed enough space. We do the
499 // first attempt (without holding the Heap_lock) here and the
500 // follow-on attempt will be at the start of the next loop
501 // iteration (after taking the Heap_lock).
502 size_t dummy = 0;
503 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
504 if (result != NULL) {
505 return result;
506 }
507
508 // Give a warning if we seem to be looping forever.
509 if ((QueuedAllocationWarningCount > 0) &&
510 (try_count % QueuedAllocationWarningCount == 0)) {
511 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
512 Thread::current()->name(), try_count, word_size);
513 }
514 }
515
516 ShouldNotReachHere();
517 return NULL;
518 }
519
520 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
521 assert_at_safepoint_on_vm_thread();
522 if (_archive_allocator == NULL) {
523 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
524 }
525 }
526
527 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
528 // Allocations in archive regions cannot be of a size that would be considered
529 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
530 // may be different at archive-restore time.
531 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
532 }
533
534 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
535 assert_at_safepoint_on_vm_thread();
536 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
537 if (is_archive_alloc_too_large(word_size)) {
538 return NULL;
539 }
540 return _archive_allocator->archive_mem_allocate(word_size);
541 }
542
543 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
544 size_t end_alignment_in_bytes) {
545 assert_at_safepoint_on_vm_thread();
546 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
547
548 // Call complete_archive to do the real work, filling in the MemRegion
549 // array with the archive regions.
550 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
551 delete _archive_allocator;
552 _archive_allocator = NULL;
553 }
554
555 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
556 assert(ranges != NULL, "MemRegion array NULL");
557 assert(count != 0, "No MemRegions provided");
558 MemRegion reserved = _hrm->reserved();
559 for (size_t i = 0; i < count; i++) {
560 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
561 return false;
562 }
563 }
564 return true;
565 }
566
567 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
568 size_t count,
569 bool open) {
570 assert(!is_init_completed(), "Expect to be called at JVM init time");
571 assert(ranges != NULL, "MemRegion array NULL");
572 assert(count != 0, "No MemRegions provided");
573 MutexLockerEx x(Heap_lock);
574
575 MemRegion reserved = _hrm->reserved();
576 HeapWord* prev_last_addr = NULL;
577 HeapRegion* prev_last_region = NULL;
578
579 // Temporarily disable pretouching of heap pages. This interface is used
580 // when mmap'ing archived heap data in, so pre-touching is wasted.
581 FlagSetting fs(AlwaysPreTouch, false);
582
583 // Enable archive object checking used by G1MarkSweep. We have to let it know
584 // about each archive range, so that objects in those ranges aren't marked.
585 G1ArchiveAllocator::enable_archive_object_check();
586
587 // For each specified MemRegion range, allocate the corresponding G1
588 // regions and mark them as archive regions. We expect the ranges
589 // in ascending starting address order, without overlap.
590 for (size_t i = 0; i < count; i++) {
591 MemRegion curr_range = ranges[i];
592 HeapWord* start_address = curr_range.start();
593 size_t word_size = curr_range.word_size();
594 HeapWord* last_address = curr_range.last();
595 size_t commits = 0;
596
597 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
598 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
599 p2i(start_address), p2i(last_address));
600 guarantee(start_address > prev_last_addr,
601 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
602 p2i(start_address), p2i(prev_last_addr));
603 prev_last_addr = last_address;
604
605 // Check for ranges that start in the same G1 region in which the previous
606 // range ended, and adjust the start address so we don't try to allocate
607 // the same region again. If the current range is entirely within that
608 // region, skip it, just adjusting the recorded top.
609 HeapRegion* start_region = _hrm->addr_to_region(start_address);
610 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
611 start_address = start_region->end();
612 if (start_address > last_address) {
613 increase_used(word_size * HeapWordSize);
614 start_region->set_top(last_address + 1);
615 continue;
616 }
617 start_region->set_top(start_address);
618 curr_range = MemRegion(start_address, last_address + 1);
619 start_region = _hrm->addr_to_region(start_address);
620 }
621
622 // Perform the actual region allocation, exiting if it fails.
623 // Then note how much new space we have allocated.
624 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
625 return false;
626 }
627 increase_used(word_size * HeapWordSize);
628 if (commits != 0) {
629 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
630 HeapRegion::GrainWords * HeapWordSize * commits);
631
632 }
633
634 // Mark each G1 region touched by the range as archive, add it to
635 // the old set, and set top.
636 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
637 HeapRegion* last_region = _hrm->addr_to_region(last_address);
638 prev_last_region = last_region;
639
640 while (curr_region != NULL) {
641 assert(curr_region->is_empty() && !curr_region->is_pinned(),
642 "Region already in use (index %u)", curr_region->hrm_index());
643 if (open) {
644 curr_region->set_open_archive();
645 } else {
646 curr_region->set_closed_archive();
647 }
648 _hr_printer.alloc(curr_region);
649 _archive_set.add(curr_region);
650 HeapWord* top;
651 HeapRegion* next_region;
652 if (curr_region != last_region) {
653 top = curr_region->end();
654 next_region = _hrm->next_region_in_heap(curr_region);
655 } else {
656 top = last_address + 1;
657 next_region = NULL;
658 }
659 curr_region->set_top(top);
660 curr_region->set_first_dead(top);
661 curr_region->set_end_of_live(top);
662 curr_region = next_region;
663 }
664
665 // Notify mark-sweep of the archive
666 G1ArchiveAllocator::set_range_archive(curr_range, open);
667 }
668 return true;
669 }
670
671 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
672 assert(!is_init_completed(), "Expect to be called at JVM init time");
673 assert(ranges != NULL, "MemRegion array NULL");
674 assert(count != 0, "No MemRegions provided");
675 MemRegion reserved = _hrm->reserved();
676 HeapWord *prev_last_addr = NULL;
677 HeapRegion* prev_last_region = NULL;
678
679 // For each MemRegion, create filler objects, if needed, in the G1 regions
680 // that contain the address range. The address range actually within the
681 // MemRegion will not be modified. That is assumed to have been initialized
682 // elsewhere, probably via an mmap of archived heap data.
683 MutexLockerEx x(Heap_lock);
684 for (size_t i = 0; i < count; i++) {
685 HeapWord* start_address = ranges[i].start();
686 HeapWord* last_address = ranges[i].last();
687
688 assert(reserved.contains(start_address) && reserved.contains(last_address),
689 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
690 p2i(start_address), p2i(last_address));
691 assert(start_address > prev_last_addr,
692 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
693 p2i(start_address), p2i(prev_last_addr));
694
695 HeapRegion* start_region = _hrm->addr_to_region(start_address);
696 HeapRegion* last_region = _hrm->addr_to_region(last_address);
697 HeapWord* bottom_address = start_region->bottom();
698
699 // Check for a range beginning in the same region in which the
700 // previous one ended.
701 if (start_region == prev_last_region) {
702 bottom_address = prev_last_addr + 1;
703 }
704
705 // Verify that the regions were all marked as archive regions by
706 // alloc_archive_regions.
707 HeapRegion* curr_region = start_region;
708 while (curr_region != NULL) {
709 guarantee(curr_region->is_archive(),
710 "Expected archive region at index %u", curr_region->hrm_index());
711 if (curr_region != last_region) {
712 curr_region = _hrm->next_region_in_heap(curr_region);
713 } else {
714 curr_region = NULL;
715 }
716 }
717
718 prev_last_addr = last_address;
719 prev_last_region = last_region;
720
721 // Fill the memory below the allocated range with dummy object(s),
722 // if the region bottom does not match the range start, or if the previous
723 // range ended within the same G1 region, and there is a gap.
724 if (start_address != bottom_address) {
725 size_t fill_size = pointer_delta(start_address, bottom_address);
726 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
727 increase_used(fill_size * HeapWordSize);
728 }
729 }
730 }
731
732 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
733 size_t desired_word_size,
734 size_t* actual_word_size) {
735 assert_heap_not_locked_and_not_at_safepoint();
736 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
737 "be called for humongous allocation requests");
738
739 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
740
741 if (result == NULL) {
742 *actual_word_size = desired_word_size;
743 result = attempt_allocation_slow(desired_word_size);
744 }
745
746 assert_heap_not_locked();
747 if (result != NULL) {
748 assert(*actual_word_size != 0, "Actual size must have been set here");
749 dirty_young_block(result, *actual_word_size);
750 } else {
751 *actual_word_size = 0;
752 }
753
754 return result;
755 }
756
757 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
758 assert(!is_init_completed(), "Expect to be called at JVM init time");
759 assert(ranges != NULL, "MemRegion array NULL");
760 assert(count != 0, "No MemRegions provided");
761 MemRegion reserved = _hrm->reserved();
762 HeapWord* prev_last_addr = NULL;
763 HeapRegion* prev_last_region = NULL;
764 size_t size_used = 0;
765 size_t uncommitted_regions = 0;
766
767 // For each Memregion, free the G1 regions that constitute it, and
768 // notify mark-sweep that the range is no longer to be considered 'archive.'
769 MutexLockerEx x(Heap_lock);
770 for (size_t i = 0; i < count; i++) {
771 HeapWord* start_address = ranges[i].start();
772 HeapWord* last_address = ranges[i].last();
773
774 assert(reserved.contains(start_address) && reserved.contains(last_address),
775 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
776 p2i(start_address), p2i(last_address));
777 assert(start_address > prev_last_addr,
778 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
779 p2i(start_address), p2i(prev_last_addr));
780 size_used += ranges[i].byte_size();
781 prev_last_addr = last_address;
782
783 HeapRegion* start_region = _hrm->addr_to_region(start_address);
784 HeapRegion* last_region = _hrm->addr_to_region(last_address);
785
786 // Check for ranges that start in the same G1 region in which the previous
787 // range ended, and adjust the start address so we don't try to free
788 // the same region again. If the current range is entirely within that
789 // region, skip it.
790 if (start_region == prev_last_region) {
791 start_address = start_region->end();
792 if (start_address > last_address) {
793 continue;
794 }
795 start_region = _hrm->addr_to_region(start_address);
796 }
797 prev_last_region = last_region;
798
799 // After verifying that each region was marked as an archive region by
800 // alloc_archive_regions, set it free and empty and uncommit it.
801 HeapRegion* curr_region = start_region;
802 while (curr_region != NULL) {
803 guarantee(curr_region->is_archive(),
804 "Expected archive region at index %u", curr_region->hrm_index());
805 uint curr_index = curr_region->hrm_index();
806 _archive_set.remove(curr_region);
807 curr_region->set_free();
808 curr_region->set_top(curr_region->bottom());
809 if (curr_region != last_region) {
810 curr_region = _hrm->next_region_in_heap(curr_region);
811 } else {
812 curr_region = NULL;
813 }
814 _hrm->shrink_at(curr_index, 1);
815 uncommitted_regions++;
816 }
817
818 // Notify mark-sweep that this is no longer an archive range.
819 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
820 }
821
822 if (uncommitted_regions != 0) {
823 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
824 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
825 }
826 decrease_used(size_used);
827 }
828
829 oop G1CollectedHeap::materialize_archived_object(oop obj) {
830 assert(obj != NULL, "archived obj is NULL");
831 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
832
833 // Loading an archived object makes it strongly reachable. If it is
834 // loaded during concurrent marking, it must be enqueued to the SATB
835 // queue, shading the previously white object gray.
836 G1BarrierSet::enqueue(obj);
837
838 return obj;
839 }
840
841 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
842 ResourceMark rm; // For retrieving the thread names in log messages.
843
844 // The structure of this method has a lot of similarities to
845 // attempt_allocation_slow(). The reason these two were not merged
846 // into a single one is that such a method would require several "if
847 // allocation is not humongous do this, otherwise do that"
848 // conditional paths which would obscure its flow. In fact, an early
849 // version of this code did use a unified method which was harder to
850 // follow and, as a result, it had subtle bugs that were hard to
851 // track down. So keeping these two methods separate allows each to
852 // be more readable. It will be good to keep these two in sync as
853 // much as possible.
854
855 assert_heap_not_locked_and_not_at_safepoint();
856 assert(is_humongous(word_size), "attempt_allocation_humongous() "
857 "should only be called for humongous allocations");
858
859 // Humongous objects can exhaust the heap quickly, so we should check if we
860 // need to start a marking cycle at each humongous object allocation. We do
861 // the check before we do the actual allocation. The reason for doing it
862 // before the allocation is that we avoid having to keep track of the newly
863 // allocated memory while we do a GC.
864 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
865 word_size)) {
866 collect(GCCause::_g1_humongous_allocation);
867 }
868
869 // We will loop until a) we manage to successfully perform the
870 // allocation or b) we successfully schedule a collection which
871 // fails to perform the allocation. b) is the only case when we'll
872 // return NULL.
873 HeapWord* result = NULL;
874 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
875 bool should_try_gc;
876 uint gc_count_before;
877
878
879 {
880 MutexLockerEx x(Heap_lock);
881
882 // Given that humongous objects are not allocated in young
883 // regions, we'll first try to do the allocation without doing a
884 // collection hoping that there's enough space in the heap.
885 result = humongous_obj_allocate(word_size);
886 if (result != NULL) {
887 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
888 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
889 return result;
890 }
891
892 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
893 // the GCLocker initiated GC has been performed and then retry. This includes
894 // the case when the GC Locker is not active but has not been performed.
895 should_try_gc = !GCLocker::needs_gc();
896 // Read the GC count while still holding the Heap_lock.
897 gc_count_before = total_collections();
898 }
899
900 if (should_try_gc) {
901 bool succeeded;
902 result = do_collection_pause(word_size, gc_count_before, &succeeded,
903 GCCause::_g1_humongous_allocation);
904 if (result != NULL) {
905 assert(succeeded, "only way to get back a non-NULL result");
906 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
907 Thread::current()->name(), p2i(result));
908 return result;
909 }
910
911 if (succeeded) {
912 // We successfully scheduled a collection which failed to allocate. No
913 // point in trying to allocate further. We'll just return NULL.
914 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
915 SIZE_FORMAT " words", Thread::current()->name(), word_size);
916 return NULL;
917 }
918 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
919 Thread::current()->name(), word_size);
920 } else {
921 // Failed to schedule a collection.
922 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
923 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
924 SIZE_FORMAT " words", Thread::current()->name(), word_size);
925 return NULL;
926 }
927 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
928 // The GCLocker is either active or the GCLocker initiated
929 // GC has not yet been performed. Stall until it is and
930 // then retry the allocation.
931 GCLocker::stall_until_clear();
932 gclocker_retry_count += 1;
933 }
934
935
936 // We can reach here if we were unsuccessful in scheduling a
937 // collection (because another thread beat us to it) or if we were
938 // stalled due to the GC locker. In either can we should retry the
939 // allocation attempt in case another thread successfully
940 // performed a collection and reclaimed enough space.
941 // Humongous object allocation always needs a lock, so we wait for the retry
942 // in the next iteration of the loop, unlike for the regular iteration case.
943 // Give a warning if we seem to be looping forever.
944
945 if ((QueuedAllocationWarningCount > 0) &&
946 (try_count % QueuedAllocationWarningCount == 0)) {
947 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
948 Thread::current()->name(), try_count, word_size);
949 }
950 }
951
952 ShouldNotReachHere();
953 return NULL;
954 }
955
956 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
957 bool expect_null_mutator_alloc_region) {
958 assert_at_safepoint_on_vm_thread();
959 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
960 "the current alloc region was unexpectedly found to be non-NULL");
961
962 if (!is_humongous(word_size)) {
963 return _allocator->attempt_allocation_locked(word_size);
964 } else {
965 HeapWord* result = humongous_obj_allocate(word_size);
966 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
967 collector_state()->set_initiate_conc_mark_if_possible(true);
968 }
969 return result;
970 }
971
972 ShouldNotReachHere();
973 }
974
975 class PostCompactionPrinterClosure: public HeapRegionClosure {
976 private:
977 G1HRPrinter* _hr_printer;
978 public:
979 bool do_heap_region(HeapRegion* hr) {
980 assert(!hr->is_young(), "not expecting to find young regions");
981 _hr_printer->post_compaction(hr);
982 return false;
983 }
984
985 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
986 : _hr_printer(hr_printer) { }
987 };
988
989 void G1CollectedHeap::print_hrm_post_compaction() {
990 if (_hr_printer.is_active()) {
991 PostCompactionPrinterClosure cl(hr_printer());
992 heap_region_iterate(&cl);
993 }
994 }
995
996 void G1CollectedHeap::abort_concurrent_cycle() {
997 // If we start the compaction before the CM threads finish
998 // scanning the root regions we might trip them over as we'll
999 // be moving objects / updating references. So let's wait until
1000 // they are done. By telling them to abort, they should complete
1001 // early.
1002 _cm->root_regions()->abort();
1003 _cm->root_regions()->wait_until_scan_finished();
1004
1005 // Disable discovery and empty the discovered lists
1006 // for the CM ref processor.
1007 _ref_processor_cm->disable_discovery();
1008 _ref_processor_cm->abandon_partial_discovery();
1009 _ref_processor_cm->verify_no_references_recorded();
1010
1011 // Abandon current iterations of concurrent marking and concurrent
1012 // refinement, if any are in progress.
1013 concurrent_mark()->concurrent_cycle_abort();
1014 }
1015
1016 void G1CollectedHeap::prepare_heap_for_full_collection() {
1017 // Make sure we'll choose a new allocation region afterwards.
1018 _allocator->release_mutator_alloc_region();
1019 _allocator->abandon_gc_alloc_regions();
1020
1021 // We may have added regions to the current incremental collection
1022 // set between the last GC or pause and now. We need to clear the
1023 // incremental collection set and then start rebuilding it afresh
1024 // after this full GC.
1025 abandon_collection_set(collection_set());
1026
1027 tear_down_region_sets(false /* free_list_only */);
1028
1029 hrm()->prepare_for_full_collection_start();
1030 }
1031
1032 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1033 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1034 assert(used() == recalculate_used(), "Should be equal");
1035 _verifier->verify_region_sets_optional();
1036 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1037 _verifier->check_bitmaps("Full GC Start");
1038 }
1039
1040 void G1CollectedHeap::prepare_heap_for_mutators() {
1041 hrm()->prepare_for_full_collection_end();
1042
1043 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1044 ClassLoaderDataGraph::purge();
1045 MetaspaceUtils::verify_metrics();
1046
1047 // Prepare heap for normal collections.
1048 assert(num_free_regions() == 0, "we should not have added any free regions");
1049 rebuild_region_sets(false /* free_list_only */);
1050 abort_refinement();
1051 resize_heap_if_necessary();
1052
1053 // Rebuild the strong code root lists for each region
1054 rebuild_strong_code_roots();
1055
1056 // Purge code root memory
1057 purge_code_root_memory();
1058
1059 // Start a new incremental collection set for the next pause
1060 start_new_collection_set();
1061
1062 _allocator->init_mutator_alloc_region();
1063
1064 // Post collection state updates.
1065 MetaspaceGC::compute_new_size();
1066 }
1067
1068 void G1CollectedHeap::abort_refinement() {
1069 if (_hot_card_cache->use_cache()) {
1070 _hot_card_cache->reset_hot_cache();
1071 }
1072
1073 // Discard all remembered set updates.
1074 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1075 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1076 }
1077
1078 void G1CollectedHeap::verify_after_full_collection() {
1079 _hrm->verify_optional();
1080 _verifier->verify_region_sets_optional();
1081 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1082 // Clear the previous marking bitmap, if needed for bitmap verification.
1083 // Note we cannot do this when we clear the next marking bitmap in
1084 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1085 // objects marked during a full GC against the previous bitmap.
1086 // But we need to clear it before calling check_bitmaps below since
1087 // the full GC has compacted objects and updated TAMS but not updated
1088 // the prev bitmap.
1089 if (G1VerifyBitmaps) {
1090 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1091 _cm->clear_prev_bitmap(workers());
1092 }
1093 // This call implicitly verifies that the next bitmap is clear after Full GC.
1094 _verifier->check_bitmaps("Full GC End");
1095
1096 // At this point there should be no regions in the
1097 // entire heap tagged as young.
1098 assert(check_young_list_empty(), "young list should be empty at this point");
1099
1100 // Note: since we've just done a full GC, concurrent
1101 // marking is no longer active. Therefore we need not
1102 // re-enable reference discovery for the CM ref processor.
1103 // That will be done at the start of the next marking cycle.
1104 // We also know that the STW processor should no longer
1105 // discover any new references.
1106 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1107 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1108 _ref_processor_stw->verify_no_references_recorded();
1109 _ref_processor_cm->verify_no_references_recorded();
1110 }
1111
1112 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1113 // Post collection logging.
1114 // We should do this after we potentially resize the heap so
1115 // that all the COMMIT / UNCOMMIT events are generated before
1116 // the compaction events.
1117 print_hrm_post_compaction();
1118 heap_transition->print();
1119 print_heap_after_gc();
1120 print_heap_regions();
1121 #ifdef TRACESPINNING
1122 ParallelTaskTerminator::print_termination_counts();
1123 #endif
1124 }
1125
1126 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1127 bool clear_all_soft_refs) {
1128 assert_at_safepoint_on_vm_thread();
1129
1130 if (GCLocker::check_active_before_gc()) {
1131 // Full GC was not completed.
1132 return false;
1133 }
1134
1135 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1136 soft_ref_policy()->should_clear_all_soft_refs();
1137
1138 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1139 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1140
1141 collector.prepare_collection();
1142 collector.collect();
1143 collector.complete_collection();
1144
1145 // Full collection was successfully completed.
1146 return true;
1147 }
1148
1149 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1150 // Currently, there is no facility in the do_full_collection(bool) API to notify
1151 // the caller that the collection did not succeed (e.g., because it was locked
1152 // out by the GC locker). So, right now, we'll ignore the return value.
1153 bool dummy = do_full_collection(true, /* explicit_gc */
1154 clear_all_soft_refs);
1155 }
1156
1157 void G1CollectedHeap::resize_heap_if_necessary() {
1158 assert_at_safepoint_on_vm_thread();
1159
1160 // Capacity, free and used after the GC counted as full regions to
1161 // include the waste in the following calculations.
1162 const size_t capacity_after_gc = capacity();
1163 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1164
1165 // This is enforced in arguments.cpp.
1166 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1167 "otherwise the code below doesn't make sense");
1168
1169 // We don't have floating point command-line arguments
1170 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1171 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1172 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1173 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1174
1175 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1176 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1177
1178 // We have to be careful here as these two calculations can overflow
1179 // 32-bit size_t's.
1180 double used_after_gc_d = (double) used_after_gc;
1181 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1182 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1183
1184 // Let's make sure that they are both under the max heap size, which
1185 // by default will make them fit into a size_t.
1186 double desired_capacity_upper_bound = (double) max_heap_size;
1187 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1188 desired_capacity_upper_bound);
1189 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1190 desired_capacity_upper_bound);
1191
1192 // We can now safely turn them into size_t's.
1193 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1194 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1195
1196 // This assert only makes sense here, before we adjust them
1197 // with respect to the min and max heap size.
1198 assert(minimum_desired_capacity <= maximum_desired_capacity,
1199 "minimum_desired_capacity = " SIZE_FORMAT ", "
1200 "maximum_desired_capacity = " SIZE_FORMAT,
1201 minimum_desired_capacity, maximum_desired_capacity);
1202
1203 // Should not be greater than the heap max size. No need to adjust
1204 // it with respect to the heap min size as it's a lower bound (i.e.,
1205 // we'll try to make the capacity larger than it, not smaller).
1206 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1207 // Should not be less than the heap min size. No need to adjust it
1208 // with respect to the heap max size as it's an upper bound (i.e.,
1209 // we'll try to make the capacity smaller than it, not greater).
1210 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1211
1212 if (capacity_after_gc < minimum_desired_capacity) {
1213 // Don't expand unless it's significant
1214 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1215
1216 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1217 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1218 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1219 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1220
1221 expand(expand_bytes, _workers);
1222
1223 // No expansion, now see if we want to shrink
1224 } else if (capacity_after_gc > maximum_desired_capacity) {
1225 // Capacity too large, compute shrinking size
1226 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1227
1228 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1229 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1230 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1231 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1232
1233 shrink(shrink_bytes);
1234 }
1235 }
1236
1237 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1238 bool do_gc,
1239 bool clear_all_soft_refs,
1240 bool expect_null_mutator_alloc_region,
1241 bool* gc_succeeded) {
1242 *gc_succeeded = true;
1243 // Let's attempt the allocation first.
1244 HeapWord* result =
1245 attempt_allocation_at_safepoint(word_size,
1246 expect_null_mutator_alloc_region);
1247 if (result != NULL) {
1248 return result;
1249 }
1250
1251 // In a G1 heap, we're supposed to keep allocation from failing by
1252 // incremental pauses. Therefore, at least for now, we'll favor
1253 // expansion over collection. (This might change in the future if we can
1254 // do something smarter than full collection to satisfy a failed alloc.)
1255 result = expand_and_allocate(word_size);
1256 if (result != NULL) {
1257 return result;
1258 }
1259
1260 if (do_gc) {
1261 // Expansion didn't work, we'll try to do a Full GC.
1262 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1263 clear_all_soft_refs);
1264 }
1265
1266 return NULL;
1267 }
1268
1269 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1270 bool* succeeded) {
1271 assert_at_safepoint_on_vm_thread();
1272
1273 // Attempts to allocate followed by Full GC.
1274 HeapWord* result =
1275 satisfy_failed_allocation_helper(word_size,
1276 true, /* do_gc */
1277 false, /* clear_all_soft_refs */
1278 false, /* expect_null_mutator_alloc_region */
1279 succeeded);
1280
1281 if (result != NULL || !*succeeded) {
1282 return result;
1283 }
1284
1285 // Attempts to allocate followed by Full GC that will collect all soft references.
1286 result = satisfy_failed_allocation_helper(word_size,
1287 true, /* do_gc */
1288 true, /* clear_all_soft_refs */
1289 true, /* expect_null_mutator_alloc_region */
1290 succeeded);
1291
1292 if (result != NULL || !*succeeded) {
1293 return result;
1294 }
1295
1296 // Attempts to allocate, no GC
1297 result = satisfy_failed_allocation_helper(word_size,
1298 false, /* do_gc */
1299 false, /* clear_all_soft_refs */
1300 true, /* expect_null_mutator_alloc_region */
1301 succeeded);
1302
1303 if (result != NULL) {
1304 return result;
1305 }
1306
1307 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1308 "Flag should have been handled and cleared prior to this point");
1309
1310 // What else? We might try synchronous finalization later. If the total
1311 // space available is large enough for the allocation, then a more
1312 // complete compaction phase than we've tried so far might be
1313 // appropriate.
1314 return NULL;
1315 }
1316
1317 // Attempting to expand the heap sufficiently
1318 // to support an allocation of the given "word_size". If
1319 // successful, perform the allocation and return the address of the
1320 // allocated block, or else "NULL".
1321
1322 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1323 assert_at_safepoint_on_vm_thread();
1324
1325 _verifier->verify_region_sets_optional();
1326
1327 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1328 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1329 word_size * HeapWordSize);
1330
1331
1332 if (expand(expand_bytes, _workers)) {
1333 _hrm->verify_optional();
1334 _verifier->verify_region_sets_optional();
1335 return attempt_allocation_at_safepoint(word_size,
1336 false /* expect_null_mutator_alloc_region */);
1337 }
1338 return NULL;
1339 }
1340
1341 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1342 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1343 aligned_expand_bytes = align_up(aligned_expand_bytes,
1344 HeapRegion::GrainBytes);
1345
1346 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1347 expand_bytes, aligned_expand_bytes);
1348
1349 if (is_maximal_no_gc()) {
1350 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1351 return false;
1352 }
1353
1354 double expand_heap_start_time_sec = os::elapsedTime();
1355 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1356 assert(regions_to_expand > 0, "Must expand by at least one region");
1357
1358 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1359 if (expand_time_ms != NULL) {
1360 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1361 }
1362
1363 if (expanded_by > 0) {
1364 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1365 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1366 policy()->record_new_heap_size(num_regions());
1367 } else {
1368 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1369
1370 // The expansion of the virtual storage space was unsuccessful.
1371 // Let's see if it was because we ran out of swap.
1372 if (G1ExitOnExpansionFailure &&
1373 _hrm->available() >= regions_to_expand) {
1374 // We had head room...
1375 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1376 }
1377 }
1378 return regions_to_expand > 0;
1379 }
1380
1381 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1382 size_t aligned_shrink_bytes =
1383 ReservedSpace::page_align_size_down(shrink_bytes);
1384 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1385 HeapRegion::GrainBytes);
1386 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1387
1388 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1389 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1390
1391
1392 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",
1393 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1394 if (num_regions_removed > 0) {
1395 policy()->record_new_heap_size(num_regions());
1396 } else {
1397 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1398 }
1399 }
1400
1401 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1402 _verifier->verify_region_sets_optional();
1403
1404 // We should only reach here at the end of a Full GC or during Remark which
1405 // means we should not not be holding to any GC alloc regions. The method
1406 // below will make sure of that and do any remaining clean up.
1407 _allocator->abandon_gc_alloc_regions();
1408
1409 // Instead of tearing down / rebuilding the free lists here, we
1410 // could instead use the remove_all_pending() method on free_list to
1411 // remove only the ones that we need to remove.
1412 tear_down_region_sets(true /* free_list_only */);
1413 shrink_helper(shrink_bytes);
1414 rebuild_region_sets(true /* free_list_only */);
1415
1416 _hrm->verify_optional();
1417 _verifier->verify_region_sets_optional();
1418 }
1419
1420 class OldRegionSetChecker : public HeapRegionSetChecker {
1421 public:
1422 void check_mt_safety() {
1423 // Master Old Set MT safety protocol:
1424 // (a) If we're at a safepoint, operations on the master old set
1425 // should be invoked:
1426 // - by the VM thread (which will serialize them), or
1427 // - by the GC workers while holding the FreeList_lock, if we're
1428 // at a safepoint for an evacuation pause (this lock is taken
1429 // anyway when an GC alloc region is retired so that a new one
1430 // is allocated from the free list), or
1431 // - by the GC workers while holding the OldSets_lock, if we're at a
1432 // safepoint for a cleanup pause.
1433 // (b) If we're not at a safepoint, operations on the master old set
1434 // should be invoked while holding the Heap_lock.
1435
1436 if (SafepointSynchronize::is_at_safepoint()) {
1437 guarantee(Thread::current()->is_VM_thread() ||
1438 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1439 "master old set MT safety protocol at a safepoint");
1440 } else {
1441 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1442 }
1443 }
1444 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1445 const char* get_description() { return "Old Regions"; }
1446 };
1447
1448 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1449 public:
1450 void check_mt_safety() {
1451 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1452 "May only change archive regions during initialization or safepoint.");
1453 }
1454 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1455 const char* get_description() { return "Archive Regions"; }
1456 };
1457
1458 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1459 public:
1460 void check_mt_safety() {
1461 // Humongous Set MT safety protocol:
1462 // (a) If we're at a safepoint, operations on the master humongous
1463 // set should be invoked by either the VM thread (which will
1464 // serialize them) or by the GC workers while holding the
1465 // OldSets_lock.
1466 // (b) If we're not at a safepoint, operations on the master
1467 // humongous set should be invoked while holding the Heap_lock.
1468
1469 if (SafepointSynchronize::is_at_safepoint()) {
1470 guarantee(Thread::current()->is_VM_thread() ||
1471 OldSets_lock->owned_by_self(),
1472 "master humongous set MT safety protocol at a safepoint");
1473 } else {
1474 guarantee(Heap_lock->owned_by_self(),
1475 "master humongous set MT safety protocol outside a safepoint");
1476 }
1477 }
1478 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1479 const char* get_description() { return "Humongous Regions"; }
1480 };
1481
1482 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1483 CollectedHeap(),
1484 _young_gen_sampling_thread(NULL),
1485 _workers(NULL),
1486 _collector_policy(collector_policy),
1487 _card_table(NULL),
1488 _soft_ref_policy(),
1489 _old_set("Old Region Set", new OldRegionSetChecker()),
1490 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1491 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1492 _bot(NULL),
1493 _listener(),
1494 _hrm(NULL),
1495 _allocator(NULL),
1496 _verifier(NULL),
1497 _summary_bytes_used(0),
1498 _archive_allocator(NULL),
1499 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1500 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1501 _expand_heap_after_alloc_failure(true),
1502 _g1mm(NULL),
1503 _humongous_reclaim_candidates(),
1504 _has_humongous_reclaim_candidates(false),
1505 _hr_printer(),
1506 _collector_state(),
1507 _old_marking_cycles_started(0),
1508 _old_marking_cycles_completed(0),
1509 _eden(),
1510 _survivor(),
1511 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1512 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1513 _policy(G1Policy::create_policy(collector_policy, _gc_timer_stw)),
1514 _heap_sizing_policy(NULL),
1515 _collection_set(this, _policy),
1516 _hot_card_cache(NULL),
1517 _rem_set(NULL),
1518 _dirty_card_queue_set(false),
1519 _cm(NULL),
1520 _cm_thread(NULL),
1521 _cr(NULL),
1522 _task_queues(NULL),
1523 _evacuation_failed(false),
1524 _evacuation_failed_info_array(NULL),
1525 _preserved_marks_set(true /* in_c_heap */),
1526 #ifndef PRODUCT
1527 _evacuation_failure_alot_for_current_gc(false),
1528 _evacuation_failure_alot_gc_number(0),
1529 _evacuation_failure_alot_count(0),
1530 #endif
1531 _ref_processor_stw(NULL),
1532 _is_alive_closure_stw(this),
1533 _is_subject_to_discovery_stw(this),
1534 _ref_processor_cm(NULL),
1535 _is_alive_closure_cm(this),
1536 _is_subject_to_discovery_cm(this),
1537 _in_cset_fast_test() {
1538
1539 _verifier = new G1HeapVerifier(this);
1540
1541 _allocator = new G1Allocator(this);
1542
1543 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1544
1545 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1546
1547 // Override the default _filler_array_max_size so that no humongous filler
1548 // objects are created.
1549 _filler_array_max_size = _humongous_object_threshold_in_words;
1550
1551 uint n_queues = ParallelGCThreads;
1552 _task_queues = new RefToScanQueueSet(n_queues);
1553
1554 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1555
1556 for (uint i = 0; i < n_queues; i++) {
1557 RefToScanQueue* q = new RefToScanQueue();
1558 q->initialize();
1559 _task_queues->register_queue(i, q);
1560 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1561 }
1562
1563 // Initialize the G1EvacuationFailureALot counters and flags.
1564 NOT_PRODUCT(reset_evacuation_should_fail();)
1565
1566 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1567 }
1568
1569 static size_t actual_reserved_page_size(ReservedSpace rs) {
1570 size_t page_size = os::vm_page_size();
1571 if (UseLargePages) {
1572 // There are two ways to manage large page memory.
1573 // 1. OS supports committing large page memory.
1574 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1575 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1576 // we reserved memory without large page.
1577 if (os::can_commit_large_page_memory() || rs.special()) {
1578 page_size = rs.alignment();
1579 }
1580 }
1581
1582 return page_size;
1583 }
1584
1585 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1586 size_t size,
1587 size_t translation_factor) {
1588 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1589 // Allocate a new reserved space, preferring to use large pages.
1590 ReservedSpace rs(size, preferred_page_size);
1591 size_t page_size = actual_reserved_page_size(rs);
1592 G1RegionToSpaceMapper* result =
1593 G1RegionToSpaceMapper::create_mapper(rs,
1594 size,
1595 page_size,
1596 HeapRegion::GrainBytes,
1597 translation_factor,
1598 mtGC);
1599
1600 os::trace_page_sizes_for_requested_size(description,
1601 size,
1602 preferred_page_size,
1603 page_size,
1604 rs.base(),
1605 rs.size());
1606
1607 return result;
1608 }
1609
1610 jint G1CollectedHeap::initialize_concurrent_refinement() {
1611 jint ecode = JNI_OK;
1612 _cr = G1ConcurrentRefine::create(&ecode);
1613 return ecode;
1614 }
1615
1616 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1617 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1618 if (_young_gen_sampling_thread->osthread() == NULL) {
1619 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1620 return JNI_ENOMEM;
1621 }
1622 return JNI_OK;
1623 }
1624
1625 jint G1CollectedHeap::initialize() {
1626 os::enable_vtime();
1627
1628 // Necessary to satisfy locking discipline assertions.
1629
1630 MutexLocker x(Heap_lock);
1631
1632 // While there are no constraints in the GC code that HeapWordSize
1633 // be any particular value, there are multiple other areas in the
1634 // system which believe this to be true (e.g. oop->object_size in some
1635 // cases incorrectly returns the size in wordSize units rather than
1636 // HeapWordSize).
1637 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1638
1639 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1640 size_t max_byte_size = _collector_policy->heap_reserved_size_bytes();
1641 size_t heap_alignment = collector_policy()->heap_alignment();
1642
1643 // Ensure that the sizes are properly aligned.
1644 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1645 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1646 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1647
1648 // Reserve the maximum.
1649
1650 // When compressed oops are enabled, the preferred heap base
1651 // is calculated by subtracting the requested size from the
1652 // 32Gb boundary and using the result as the base address for
1653 // heap reservation. If the requested size is not aligned to
1654 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1655 // into the ReservedHeapSpace constructor) then the actual
1656 // base of the reserved heap may end up differing from the
1657 // address that was requested (i.e. the preferred heap base).
1658 // If this happens then we could end up using a non-optimal
1659 // compressed oops mode.
1660
1661 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1662 heap_alignment);
1663
1664 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1665
1666 // Create the barrier set for the entire reserved region.
1667 G1CardTable* ct = new G1CardTable(reserved_region());
1668 ct->initialize();
1669 G1BarrierSet* bs = new G1BarrierSet(ct);
1670 bs->initialize();
1671 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1672 BarrierSet::set_barrier_set(bs);
1673 _card_table = ct;
1674
1675 G1BarrierSet::satb_mark_queue_set().initialize(this,
1676 SATB_Q_CBL_mon,
1677 &bs->satb_mark_queue_buffer_allocator(),
1678 G1SATBProcessCompletedThreshold,
1679 G1SATBBufferEnqueueingThresholdPercent);
1680
1681 // process_completed_buffers_threshold and max_completed_buffers are updated
1682 // later, based on the concurrent refinement object.
1683 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1684 &bs->dirty_card_queue_buffer_allocator(),
1685 Shared_DirtyCardQ_lock,
1686 true); // init_free_ids
1687
1688 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1689 &bs->dirty_card_queue_buffer_allocator(),
1690 Shared_DirtyCardQ_lock);
1691
1692 // Create the hot card cache.
1693 _hot_card_cache = new G1HotCardCache(this);
1694
1695 // Carve out the G1 part of the heap.
1696 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1697 size_t page_size = actual_reserved_page_size(heap_rs);
1698 G1RegionToSpaceMapper* heap_storage =
1699 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1700 g1_rs.size(),
1701 page_size,
1702 HeapRegion::GrainBytes,
1703 1,
1704 mtJavaHeap);
1705 if(heap_storage == NULL) {
1706 vm_shutdown_during_initialization("Could not initialize G1 heap");
1707 return JNI_ERR;
1708 }
1709
1710 os::trace_page_sizes("Heap",
1711 collector_policy()->min_heap_byte_size(),
1712 max_byte_size,
1713 page_size,
1714 heap_rs.base(),
1715 heap_rs.size());
1716 heap_storage->set_mapping_changed_listener(&_listener);
1717
1718 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1719 G1RegionToSpaceMapper* bot_storage =
1720 create_aux_memory_mapper("Block Offset Table",
1721 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1722 G1BlockOffsetTable::heap_map_factor());
1723
1724 G1RegionToSpaceMapper* cardtable_storage =
1725 create_aux_memory_mapper("Card Table",
1726 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1727 G1CardTable::heap_map_factor());
1728
1729 G1RegionToSpaceMapper* card_counts_storage =
1730 create_aux_memory_mapper("Card Counts Table",
1731 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1732 G1CardCounts::heap_map_factor());
1733
1734 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1735 G1RegionToSpaceMapper* prev_bitmap_storage =
1736 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1737 G1RegionToSpaceMapper* next_bitmap_storage =
1738 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1739
1740 _hrm = HeapRegionManager::create_manager(this, _collector_policy);
1741
1742 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1743 _card_table->initialize(cardtable_storage);
1744 // Do later initialization work for concurrent refinement.
1745 _hot_card_cache->initialize(card_counts_storage);
1746
1747 // 6843694 - ensure that the maximum region index can fit
1748 // in the remembered set structures.
1749 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1750 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1751
1752 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1753 // start within the first card.
1754 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1755 // Also create a G1 rem set.
1756 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1757 _rem_set->initialize(max_reserved_capacity(), max_regions());
1758
1759 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1760 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1761 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1762 "too many cards per region");
1763
1764 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1765
1766 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1767
1768 {
1769 HeapWord* start = _hrm->reserved().start();
1770 HeapWord* end = _hrm->reserved().end();
1771 size_t granularity = HeapRegion::GrainBytes;
1772
1773 _in_cset_fast_test.initialize(start, end, granularity);
1774 _humongous_reclaim_candidates.initialize(start, end, granularity);
1775 }
1776
1777 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1778 true /* are_GC_task_threads */,
1779 false /* are_ConcurrentGC_threads */);
1780 if (_workers == NULL) {
1781 return JNI_ENOMEM;
1782 }
1783 _workers->initialize_workers();
1784
1785 // Create the G1ConcurrentMark data structure and thread.
1786 // (Must do this late, so that "max_regions" is defined.)
1787 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1788 if (_cm == NULL || !_cm->completed_initialization()) {
1789 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1790 return JNI_ENOMEM;
1791 }
1792 _cm_thread = _cm->cm_thread();
1793
1794 // Now expand into the initial heap size.
1795 if (!expand(init_byte_size, _workers)) {
1796 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1797 return JNI_ENOMEM;
1798 }
1799
1800 // Perform any initialization actions delegated to the policy.
1801 policy()->init(this, &_collection_set);
1802
1803 jint ecode = initialize_concurrent_refinement();
1804 if (ecode != JNI_OK) {
1805 return ecode;
1806 }
1807
1808 ecode = initialize_young_gen_sampling_thread();
1809 if (ecode != JNI_OK) {
1810 return ecode;
1811 }
1812
1813 {
1814 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1815 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone());
1816 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone());
1817 }
1818
1819 // Here we allocate the dummy HeapRegion that is required by the
1820 // G1AllocRegion class.
1821 HeapRegion* dummy_region = _hrm->get_dummy_region();
1822
1823 // We'll re-use the same region whether the alloc region will
1824 // require BOT updates or not and, if it doesn't, then a non-young
1825 // region will complain that it cannot support allocations without
1826 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1827 dummy_region->set_eden();
1828 // Make sure it's full.
1829 dummy_region->set_top(dummy_region->end());
1830 G1AllocRegion::setup(this, dummy_region);
1831
1832 _allocator->init_mutator_alloc_region();
1833
1834 // Do create of the monitoring and management support so that
1835 // values in the heap have been properly initialized.
1836 _g1mm = new G1MonitoringSupport(this);
1837
1838 G1StringDedup::initialize();
1839
1840 _preserved_marks_set.init(ParallelGCThreads);
1841
1842 _collection_set.initialize(max_regions());
1843
1844 return JNI_OK;
1845 }
1846
1847 void G1CollectedHeap::stop() {
1848 // Stop all concurrent threads. We do this to make sure these threads
1849 // do not continue to execute and access resources (e.g. logging)
1850 // that are destroyed during shutdown.
1851 _cr->stop();
1852 _young_gen_sampling_thread->stop();
1853 _cm_thread->stop();
1854 if (G1StringDedup::is_enabled()) {
1855 G1StringDedup::stop();
1856 }
1857 }
1858
1859 void G1CollectedHeap::safepoint_synchronize_begin() {
1860 SuspendibleThreadSet::synchronize();
1861 }
1862
1863 void G1CollectedHeap::safepoint_synchronize_end() {
1864 SuspendibleThreadSet::desynchronize();
1865 }
1866
1867 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1868 return HeapRegion::max_region_size();
1869 }
1870
1871 void G1CollectedHeap::post_initialize() {
1872 CollectedHeap::post_initialize();
1873 ref_processing_init();
1874 }
1875
1876 void G1CollectedHeap::ref_processing_init() {
1877 // Reference processing in G1 currently works as follows:
1878 //
1879 // * There are two reference processor instances. One is
1880 // used to record and process discovered references
1881 // during concurrent marking; the other is used to
1882 // record and process references during STW pauses
1883 // (both full and incremental).
1884 // * Both ref processors need to 'span' the entire heap as
1885 // the regions in the collection set may be dotted around.
1886 //
1887 // * For the concurrent marking ref processor:
1888 // * Reference discovery is enabled at initial marking.
1889 // * Reference discovery is disabled and the discovered
1890 // references processed etc during remarking.
1891 // * Reference discovery is MT (see below).
1892 // * Reference discovery requires a barrier (see below).
1893 // * Reference processing may or may not be MT
1894 // (depending on the value of ParallelRefProcEnabled
1895 // and ParallelGCThreads).
1896 // * A full GC disables reference discovery by the CM
1897 // ref processor and abandons any entries on it's
1898 // discovered lists.
1899 //
1900 // * For the STW processor:
1901 // * Non MT discovery is enabled at the start of a full GC.
1902 // * Processing and enqueueing during a full GC is non-MT.
1903 // * During a full GC, references are processed after marking.
1904 //
1905 // * Discovery (may or may not be MT) is enabled at the start
1906 // of an incremental evacuation pause.
1907 // * References are processed near the end of a STW evacuation pause.
1908 // * For both types of GC:
1909 // * Discovery is atomic - i.e. not concurrent.
1910 // * Reference discovery will not need a barrier.
1911
1912 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1913
1914 // Concurrent Mark ref processor
1915 _ref_processor_cm =
1916 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1917 mt_processing, // mt processing
1918 ParallelGCThreads, // degree of mt processing
1919 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1920 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1921 false, // Reference discovery is not atomic
1922 &_is_alive_closure_cm, // is alive closure
1923 true); // allow changes to number of processing threads
1924
1925 // STW ref processor
1926 _ref_processor_stw =
1927 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1928 mt_processing, // mt processing
1929 ParallelGCThreads, // degree of mt processing
1930 (ParallelGCThreads > 1), // mt discovery
1931 ParallelGCThreads, // degree of mt discovery
1932 true, // Reference discovery is atomic
1933 &_is_alive_closure_stw, // is alive closure
1934 true); // allow changes to number of processing threads
1935 }
1936
1937 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1938 return _collector_policy;
1939 }
1940
1941 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1942 return &_soft_ref_policy;
1943 }
1944
1945 size_t G1CollectedHeap::capacity() const {
1946 return _hrm->length() * HeapRegion::GrainBytes;
1947 }
1948
1949 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1950 return _hrm->total_free_bytes();
1951 }
1952
1953 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1954 _hot_card_cache->drain(cl, worker_i);
1955 }
1956
1957 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1958 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1959 size_t n_completed_buffers = 0;
1960 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1961 n_completed_buffers++;
1962 }
1963 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!");
1964 phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1965 }
1966
1967 // Computes the sum of the storage used by the various regions.
1968 size_t G1CollectedHeap::used() const {
1969 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1970 if (_archive_allocator != NULL) {
1971 result += _archive_allocator->used();
1972 }
1973 return result;
1974 }
1975
1976 size_t G1CollectedHeap::used_unlocked() const {
1977 return _summary_bytes_used;
1978 }
1979
1980 class SumUsedClosure: public HeapRegionClosure {
1981 size_t _used;
1982 public:
1983 SumUsedClosure() : _used(0) {}
1984 bool do_heap_region(HeapRegion* r) {
1985 _used += r->used();
1986 return false;
1987 }
1988 size_t result() { return _used; }
1989 };
1990
1991 size_t G1CollectedHeap::recalculate_used() const {
1992 SumUsedClosure blk;
1993 heap_region_iterate(&blk);
1994 return blk.result();
1995 }
1996
1997 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1998 switch (cause) {
1999 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2000 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2001 case GCCause::_wb_conc_mark: return true;
2002 default : return false;
2003 }
2004 }
2005
2006 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2007 switch (cause) {
2008 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2009 case GCCause::_g1_humongous_allocation: return true;
2010 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2011 default: return is_user_requested_concurrent_full_gc(cause);
2012 }
2013 }
2014
2015 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2016 if(policy()->force_upgrade_to_full()) {
2017 return true;
2018 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2019 return false;
2020 } else if (has_regions_left_for_allocation()) {
2021 return false;
2022 } else {
2023 return true;
2024 }
2025 }
2026
2027 #ifndef PRODUCT
2028 void G1CollectedHeap::allocate_dummy_regions() {
2029 // Let's fill up most of the region
2030 size_t word_size = HeapRegion::GrainWords - 1024;
2031 // And as a result the region we'll allocate will be humongous.
2032 guarantee(is_humongous(word_size), "sanity");
2033
2034 // _filler_array_max_size is set to humongous object threshold
2035 // but temporarily change it to use CollectedHeap::fill_with_object().
2036 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2037
2038 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2039 // Let's use the existing mechanism for the allocation
2040 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2041 if (dummy_obj != NULL) {
2042 MemRegion mr(dummy_obj, word_size);
2043 CollectedHeap::fill_with_object(mr);
2044 } else {
2045 // If we can't allocate once, we probably cannot allocate
2046 // again. Let's get out of the loop.
2047 break;
2048 }
2049 }
2050 }
2051 #endif // !PRODUCT
2052
2053 void G1CollectedHeap::increment_old_marking_cycles_started() {
2054 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2055 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2056 "Wrong marking cycle count (started: %d, completed: %d)",
2057 _old_marking_cycles_started, _old_marking_cycles_completed);
2058
2059 _old_marking_cycles_started++;
2060 }
2061
2062 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2063 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2064
2065 // We assume that if concurrent == true, then the caller is a
2066 // concurrent thread that was joined the Suspendible Thread
2067 // Set. If there's ever a cheap way to check this, we should add an
2068 // assert here.
2069
2070 // Given that this method is called at the end of a Full GC or of a
2071 // concurrent cycle, and those can be nested (i.e., a Full GC can
2072 // interrupt a concurrent cycle), the number of full collections
2073 // completed should be either one (in the case where there was no
2074 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2075 // behind the number of full collections started.
2076
2077 // This is the case for the inner caller, i.e. a Full GC.
2078 assert(concurrent ||
2079 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2080 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2081 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2082 "is inconsistent with _old_marking_cycles_completed = %u",
2083 _old_marking_cycles_started, _old_marking_cycles_completed);
2084
2085 // This is the case for the outer caller, i.e. the concurrent cycle.
2086 assert(!concurrent ||
2087 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2088 "for outer caller (concurrent cycle): "
2089 "_old_marking_cycles_started = %u "
2090 "is inconsistent with _old_marking_cycles_completed = %u",
2091 _old_marking_cycles_started, _old_marking_cycles_completed);
2092
2093 _old_marking_cycles_completed += 1;
2094
2095 // We need to clear the "in_progress" flag in the CM thread before
2096 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2097 // is set) so that if a waiter requests another System.gc() it doesn't
2098 // incorrectly see that a marking cycle is still in progress.
2099 if (concurrent) {
2100 _cm_thread->set_idle();
2101 }
2102
2103 // This notify_all() will ensure that a thread that called
2104 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2105 // and it's waiting for a full GC to finish will be woken up. It is
2106 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2107 FullGCCount_lock->notify_all();
2108 }
2109
2110 void G1CollectedHeap::collect(GCCause::Cause cause) {
2111 try_collect(cause, true);
2112 }
2113
2114 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2115 assert_heap_not_locked();
2116
2117 bool gc_succeeded;
2118 bool should_retry_gc;
2119
2120 do {
2121 should_retry_gc = false;
2122
2123 uint gc_count_before;
2124 uint old_marking_count_before;
2125 uint full_gc_count_before;
2126
2127 {
2128 MutexLocker ml(Heap_lock);
2129
2130 // Read the GC count while holding the Heap_lock
2131 gc_count_before = total_collections();
2132 full_gc_count_before = total_full_collections();
2133 old_marking_count_before = _old_marking_cycles_started;
2134 }
2135
2136 if (should_do_concurrent_full_gc(cause)) {
2137 // Schedule an initial-mark evacuation pause that will start a
2138 // concurrent cycle. We're setting word_size to 0 which means that
2139 // we are not requesting a post-GC allocation.
2140 VM_G1CollectForAllocation op(0, /* word_size */
2141 gc_count_before,
2142 cause,
2143 true, /* should_initiate_conc_mark */
2144 policy()->max_pause_time_ms());
2145 VMThread::execute(&op);
2146 gc_succeeded = op.gc_succeeded();
2147 if (!gc_succeeded && retry_on_gc_failure) {
2148 if (old_marking_count_before == _old_marking_cycles_started) {
2149 should_retry_gc = op.should_retry_gc();
2150 } else {
2151 // A Full GC happened while we were trying to schedule the
2152 // concurrent cycle. No point in starting a new cycle given
2153 // that the whole heap was collected anyway.
2154 }
2155
2156 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2157 GCLocker::stall_until_clear();
2158 }
2159 }
2160 } else {
2161 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2162 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2163
2164 // Schedule a standard evacuation pause. We're setting word_size
2165 // to 0 which means that we are not requesting a post-GC allocation.
2166 VM_G1CollectForAllocation op(0, /* word_size */
2167 gc_count_before,
2168 cause,
2169 false, /* should_initiate_conc_mark */
2170 policy()->max_pause_time_ms());
2171 VMThread::execute(&op);
2172 gc_succeeded = op.gc_succeeded();
2173 } else {
2174 // Schedule a Full GC.
2175 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2176 VMThread::execute(&op);
2177 gc_succeeded = op.gc_succeeded();
2178 }
2179 }
2180 } while (should_retry_gc);
2181 return gc_succeeded;
2182 }
2183
2184 bool G1CollectedHeap::is_in(const void* p) const {
2185 if (_hrm->reserved().contains(p)) {
2186 // Given that we know that p is in the reserved space,
2187 // heap_region_containing() should successfully
2188 // return the containing region.
2189 HeapRegion* hr = heap_region_containing(p);
2190 return hr->is_in(p);
2191 } else {
2192 return false;
2193 }
2194 }
2195
2196 #ifdef ASSERT
2197 bool G1CollectedHeap::is_in_exact(const void* p) const {
2198 bool contains = reserved_region().contains(p);
2199 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2200 if (contains && available) {
2201 return true;
2202 } else {
2203 return false;
2204 }
2205 }
2206 #endif
2207
2208 // Iteration functions.
2209
2210 // Iterates an ObjectClosure over all objects within a HeapRegion.
2211
2212 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2213 ObjectClosure* _cl;
2214 public:
2215 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2216 bool do_heap_region(HeapRegion* r) {
2217 if (!r->is_continues_humongous()) {
2218 r->object_iterate(_cl);
2219 }
2220 return false;
2221 }
2222 };
2223
2224 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2225 IterateObjectClosureRegionClosure blk(cl);
2226 heap_region_iterate(&blk);
2227 }
2228
2229 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2230 _hrm->iterate(cl);
2231 }
2232
2233 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2234 HeapRegionClaimer *hrclaimer,
2235 uint worker_id) const {
2236 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2237 }
2238
2239 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2240 HeapRegionClaimer *hrclaimer) const {
2241 _hrm->par_iterate(cl, hrclaimer, 0);
2242 }
2243
2244 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2245 _collection_set.iterate(cl);
2246 }
2247
2248 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2249 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2250 }
2251
2252 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2253 HeapRegion* hr = heap_region_containing(addr);
2254 return hr->block_start(addr);
2255 }
2256
2257 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2258 HeapRegion* hr = heap_region_containing(addr);
2259 return hr->block_size(addr);
2260 }
2261
2262 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2263 HeapRegion* hr = heap_region_containing(addr);
2264 return hr->block_is_obj(addr);
2265 }
2266
2267 bool G1CollectedHeap::supports_tlab_allocation() const {
2268 return true;
2269 }
2270
2271 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2272 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2273 }
2274
2275 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2276 return _eden.length() * HeapRegion::GrainBytes;
2277 }
2278
2279 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2280 // must be equal to the humongous object limit.
2281 size_t G1CollectedHeap::max_tlab_size() const {
2282 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2283 }
2284
2285 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2286 return _allocator->unsafe_max_tlab_alloc();
2287 }
2288
2289 size_t G1CollectedHeap::max_capacity() const {
2290 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2291 }
2292
2293 size_t G1CollectedHeap::max_reserved_capacity() const {
2294 return _hrm->max_length() * HeapRegion::GrainBytes;
2295 }
2296
2297 jlong G1CollectedHeap::millis_since_last_gc() {
2298 // See the notes in GenCollectedHeap::millis_since_last_gc()
2299 // for more information about the implementation.
2300 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2301 _policy->collection_pause_end_millis();
2302 if (ret_val < 0) {
2303 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2304 ". returning zero instead.", ret_val);
2305 return 0;
2306 }
2307 return ret_val;
2308 }
2309
2310 void G1CollectedHeap::deduplicate_string(oop str) {
2311 assert(java_lang_String::is_instance(str), "invariant");
2312
2313 if (G1StringDedup::is_enabled()) {
2314 G1StringDedup::deduplicate(str);
2315 }
2316 }
2317
2318 void G1CollectedHeap::prepare_for_verify() {
2319 _verifier->prepare_for_verify();
2320 }
2321
2322 void G1CollectedHeap::verify(VerifyOption vo) {
2323 _verifier->verify(vo);
2324 }
2325
2326 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2327 return true;
2328 }
2329
2330 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2331 return _cm_thread->request_concurrent_phase(phase);
2332 }
2333
2334 bool G1CollectedHeap::is_heterogeneous_heap() const {
2335 return _collector_policy->is_heterogeneous_heap();
2336 }
2337
2338 class PrintRegionClosure: public HeapRegionClosure {
2339 outputStream* _st;
2340 public:
2341 PrintRegionClosure(outputStream* st) : _st(st) {}
2342 bool do_heap_region(HeapRegion* r) {
2343 r->print_on(_st);
2344 return false;
2345 }
2346 };
2347
2348 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2349 const HeapRegion* hr,
2350 const VerifyOption vo) const {
2351 switch (vo) {
2352 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2353 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2354 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2355 default: ShouldNotReachHere();
2356 }
2357 return false; // keep some compilers happy
2358 }
2359
2360 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2361 const VerifyOption vo) const {
2362 switch (vo) {
2363 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2364 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2365 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2366 default: ShouldNotReachHere();
2367 }
2368 return false; // keep some compilers happy
2369 }
2370
2371 void G1CollectedHeap::print_heap_regions() const {
2372 LogTarget(Trace, gc, heap, region) lt;
2373 if (lt.is_enabled()) {
2374 LogStream ls(lt);
2375 print_regions_on(&ls);
2376 }
2377 }
2378
2379 void G1CollectedHeap::print_on(outputStream* st) const {
2380 st->print(" %-20s", "garbage-first heap");
2381 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2382 capacity()/K, used_unlocked()/K);
2383 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2384 p2i(_hrm->reserved().start()),
2385 p2i(_hrm->reserved().end()));
2386 st->cr();
2387 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2388 uint young_regions = young_regions_count();
2389 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2390 (size_t) young_regions * HeapRegion::GrainBytes / K);
2391 uint survivor_regions = survivor_regions_count();
2392 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2393 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2394 st->cr();
2395 MetaspaceUtils::print_on(st);
2396 }
2397
2398 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2399 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2400 "HS=humongous(starts), HC=humongous(continues), "
2401 "CS=collection set, F=free, A=archive, "
2402 "TAMS=top-at-mark-start (previous, next)");
2403 PrintRegionClosure blk(st);
2404 heap_region_iterate(&blk);
2405 }
2406
2407 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2408 print_on(st);
2409
2410 // Print the per-region information.
2411 print_regions_on(st);
2412 }
2413
2414 void G1CollectedHeap::print_on_error(outputStream* st) const {
2415 this->CollectedHeap::print_on_error(st);
2416
2417 if (_cm != NULL) {
2418 st->cr();
2419 _cm->print_on_error(st);
2420 }
2421 }
2422
2423 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2424 workers()->print_worker_threads_on(st);
2425 _cm_thread->print_on(st);
2426 st->cr();
2427 _cm->print_worker_threads_on(st);
2428 _cr->print_threads_on(st);
2429 _young_gen_sampling_thread->print_on(st);
2430 if (G1StringDedup::is_enabled()) {
2431 G1StringDedup::print_worker_threads_on(st);
2432 }
2433 }
2434
2435 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2436 workers()->threads_do(tc);
2437 tc->do_thread(_cm_thread);
2438 _cm->threads_do(tc);
2439 _cr->threads_do(tc);
2440 tc->do_thread(_young_gen_sampling_thread);
2441 if (G1StringDedup::is_enabled()) {
2442 G1StringDedup::threads_do(tc);
2443 }
2444 }
2445
2446 void G1CollectedHeap::print_tracing_info() const {
2447 rem_set()->print_summary_info();
2448 concurrent_mark()->print_summary_info();
2449 }
2450
2451 #ifndef PRODUCT
2452 // Helpful for debugging RSet issues.
2453
2454 class PrintRSetsClosure : public HeapRegionClosure {
2455 private:
2456 const char* _msg;
2457 size_t _occupied_sum;
2458
2459 public:
2460 bool do_heap_region(HeapRegion* r) {
2461 HeapRegionRemSet* hrrs = r->rem_set();
2462 size_t occupied = hrrs->occupied();
2463 _occupied_sum += occupied;
2464
2465 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2466 if (occupied == 0) {
2467 tty->print_cr(" RSet is empty");
2468 } else {
2469 hrrs->print();
2470 }
2471 tty->print_cr("----------");
2472 return false;
2473 }
2474
2475 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2476 tty->cr();
2477 tty->print_cr("========================================");
2478 tty->print_cr("%s", msg);
2479 tty->cr();
2480 }
2481
2482 ~PrintRSetsClosure() {
2483 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2484 tty->print_cr("========================================");
2485 tty->cr();
2486 }
2487 };
2488
2489 void G1CollectedHeap::print_cset_rsets() {
2490 PrintRSetsClosure cl("Printing CSet RSets");
2491 collection_set_iterate(&cl);
2492 }
2493
2494 void G1CollectedHeap::print_all_rsets() {
2495 PrintRSetsClosure cl("Printing All RSets");;
2496 heap_region_iterate(&cl);
2497 }
2498 #endif // PRODUCT
2499
2500 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2501
2502 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2503 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2504 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2505
2506 size_t eden_capacity_bytes =
2507 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2508
2509 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2510 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2511 eden_capacity_bytes, survivor_used_bytes, num_regions());
2512 }
2513
2514 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2515 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2516 stats->unused(), stats->used(), stats->region_end_waste(),
2517 stats->regions_filled(), stats->direct_allocated(),
2518 stats->failure_used(), stats->failure_waste());
2519 }
2520
2521 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2522 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2523 gc_tracer->report_gc_heap_summary(when, heap_summary);
2524
2525 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2526 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2527 }
2528
2529 G1CollectedHeap* G1CollectedHeap::heap() {
2530 CollectedHeap* heap = Universe::heap();
2531 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2532 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2533 return (G1CollectedHeap*)heap;
2534 }
2535
2536 void G1CollectedHeap::gc_prologue(bool full) {
2537 // always_do_update_barrier = false;
2538 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2539
2540 // This summary needs to be printed before incrementing total collections.
2541 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2542
2543 // Update common counters.
2544 increment_total_collections(full /* full gc */);
2545 if (full || collector_state()->in_initial_mark_gc()) {
2546 increment_old_marking_cycles_started();
2547 }
2548
2549 // Fill TLAB's and such
2550 double start = os::elapsedTime();
2551 ensure_parsability(true);
2552 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2553 }
2554
2555 void G1CollectedHeap::gc_epilogue(bool full) {
2556 // Update common counters.
2557 if (full) {
2558 // Update the number of full collections that have been completed.
2559 increment_old_marking_cycles_completed(false /* concurrent */);
2560 }
2561
2562 // We are at the end of the GC. Total collections has already been increased.
2563 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2564
2565 // FIXME: what is this about?
2566 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2567 // is set.
2568 #if COMPILER2_OR_JVMCI
2569 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2570 #endif
2571 // always_do_update_barrier = true;
2572
2573 double start = os::elapsedTime();
2574 resize_all_tlabs();
2575 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2576
2577 MemoryService::track_memory_usage();
2578 // We have just completed a GC. Update the soft reference
2579 // policy with the new heap occupancy
2580 Universe::update_heap_info_at_gc();
2581 }
2582
2583 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2584 uint gc_count_before,
2585 bool* succeeded,
2586 GCCause::Cause gc_cause) {
2587 assert_heap_not_locked_and_not_at_safepoint();
2588 VM_G1CollectForAllocation op(word_size,
2589 gc_count_before,
2590 gc_cause,
2591 false, /* should_initiate_conc_mark */
2592 policy()->max_pause_time_ms());
2593 VMThread::execute(&op);
2594
2595 HeapWord* result = op.result();
2596 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2597 assert(result == NULL || ret_succeeded,
2598 "the result should be NULL if the VM did not succeed");
2599 *succeeded = ret_succeeded;
2600
2601 assert_heap_not_locked();
2602 return result;
2603 }
2604
2605 void G1CollectedHeap::do_concurrent_mark() {
2606 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2607 if (!_cm_thread->in_progress()) {
2608 _cm_thread->set_started();
2609 CGC_lock->notify();
2610 }
2611 }
2612
2613 size_t G1CollectedHeap::pending_card_num() {
2614 struct CountCardsClosure : public ThreadClosure {
2615 size_t _cards;
2616 CountCardsClosure() : _cards(0) {}
2617 virtual void do_thread(Thread* t) {
2618 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2619 }
2620 } count_from_threads;
2621 Threads::threads_do(&count_from_threads);
2622
2623 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2624 size_t buffer_size = dcqs.buffer_size();
2625 size_t buffer_num = dcqs.completed_buffers_num();
2626
2627 return buffer_size * buffer_num + count_from_threads._cards;
2628 }
2629
2630 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2631 // We don't nominate objects with many remembered set entries, on
2632 // the assumption that such objects are likely still live.
2633 HeapRegionRemSet* rem_set = r->rem_set();
2634
2635 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2636 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2637 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2638 }
2639
2640 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2641 private:
2642 size_t _total_humongous;
2643 size_t _candidate_humongous;
2644
2645 G1DirtyCardQueue _dcq;
2646
2647 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2648 assert(region->is_starts_humongous(), "Must start a humongous object");
2649
2650 oop obj = oop(region->bottom());
2651
2652 // Dead objects cannot be eager reclaim candidates. Due to class
2653 // unloading it is unsafe to query their classes so we return early.
2654 if (g1h->is_obj_dead(obj, region)) {
2655 return false;
2656 }
2657
2658 // If we do not have a complete remembered set for the region, then we can
2659 // not be sure that we have all references to it.
2660 if (!region->rem_set()->is_complete()) {
2661 return false;
2662 }
2663 // Candidate selection must satisfy the following constraints
2664 // while concurrent marking is in progress:
2665 //
2666 // * In order to maintain SATB invariants, an object must not be
2667 // reclaimed if it was allocated before the start of marking and
2668 // has not had its references scanned. Such an object must have
2669 // its references (including type metadata) scanned to ensure no
2670 // live objects are missed by the marking process. Objects
2671 // allocated after the start of concurrent marking don't need to
2672 // be scanned.
2673 //
2674 // * An object must not be reclaimed if it is on the concurrent
2675 // mark stack. Objects allocated after the start of concurrent
2676 // marking are never pushed on the mark stack.
2677 //
2678 // Nominating only objects allocated after the start of concurrent
2679 // marking is sufficient to meet both constraints. This may miss
2680 // some objects that satisfy the constraints, but the marking data
2681 // structures don't support efficiently performing the needed
2682 // additional tests or scrubbing of the mark stack.
2683 //
2684 // However, we presently only nominate is_typeArray() objects.
2685 // A humongous object containing references induces remembered
2686 // set entries on other regions. In order to reclaim such an
2687 // object, those remembered sets would need to be cleaned up.
2688 //
2689 // We also treat is_typeArray() objects specially, allowing them
2690 // to be reclaimed even if allocated before the start of
2691 // concurrent mark. For this we rely on mark stack insertion to
2692 // exclude is_typeArray() objects, preventing reclaiming an object
2693 // that is in the mark stack. We also rely on the metadata for
2694 // such objects to be built-in and so ensured to be kept live.
2695 // Frequent allocation and drop of large binary blobs is an
2696 // important use case for eager reclaim, and this special handling
2697 // may reduce needed headroom.
2698
2699 return obj->is_typeArray() &&
2700 g1h->is_potential_eager_reclaim_candidate(region);
2701 }
2702
2703 public:
2704 RegisterHumongousWithInCSetFastTestClosure()
2705 : _total_humongous(0),
2706 _candidate_humongous(0),
2707 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2708 }
2709
2710 virtual bool do_heap_region(HeapRegion* r) {
2711 if (!r->is_starts_humongous()) {
2712 return false;
2713 }
2714 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2715
2716 bool is_candidate = humongous_region_is_candidate(g1h, r);
2717 uint rindex = r->hrm_index();
2718 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2719 if (is_candidate) {
2720 _candidate_humongous++;
2721 g1h->register_humongous_region_with_cset(rindex);
2722 // Is_candidate already filters out humongous object with large remembered sets.
2723 // If we have a humongous object with a few remembered sets, we simply flush these
2724 // remembered set entries into the DCQS. That will result in automatic
2725 // re-evaluation of their remembered set entries during the following evacuation
2726 // phase.
2727 if (!r->rem_set()->is_empty()) {
2728 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2729 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2730 G1CardTable* ct = g1h->card_table();
2731 HeapRegionRemSetIterator hrrs(r->rem_set());
2732 size_t card_index;
2733 while (hrrs.has_next(card_index)) {
2734 CardTable::CardValue* card_ptr = ct->byte_for_index(card_index);
2735 // The remembered set might contain references to already freed
2736 // regions. Filter out such entries to avoid failing card table
2737 // verification.
2738 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2739 if (*card_ptr != G1CardTable::dirty_card_val()) {
2740 *card_ptr = G1CardTable::dirty_card_val();
2741 _dcq.enqueue(card_ptr);
2742 }
2743 }
2744 }
2745 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2746 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2747 hrrs.n_yielded(), r->rem_set()->occupied());
2748 // We should only clear the card based remembered set here as we will not
2749 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2750 // (and probably never) we do not enter this path if there are other kind of
2751 // remembered sets for this region.
2752 r->rem_set()->clear_locked(true /* only_cardset */);
2753 // Clear_locked() above sets the state to Empty. However we want to continue
2754 // collecting remembered set entries for humongous regions that were not
2755 // reclaimed.
2756 r->rem_set()->set_state_complete();
2757 }
2758 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2759 }
2760 _total_humongous++;
2761
2762 return false;
2763 }
2764
2765 size_t total_humongous() const { return _total_humongous; }
2766 size_t candidate_humongous() const { return _candidate_humongous; }
2767
2768 void flush_rem_set_entries() { _dcq.flush(); }
2769 };
2770
2771 void G1CollectedHeap::register_humongous_regions_with_cset() {
2772 if (!G1EagerReclaimHumongousObjects) {
2773 phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2774 return;
2775 }
2776 double time = os::elapsed_counter();
2777
2778 // Collect reclaim candidate information and register candidates with cset.
2779 RegisterHumongousWithInCSetFastTestClosure cl;
2780 heap_region_iterate(&cl);
2781
2782 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2783 phase_times()->record_fast_reclaim_humongous_stats(time,
2784 cl.total_humongous(),
2785 cl.candidate_humongous());
2786 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2787
2788 // Finally flush all remembered set entries to re-check into the global DCQS.
2789 cl.flush_rem_set_entries();
2790 }
2791
2792 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2793 public:
2794 bool do_heap_region(HeapRegion* hr) {
2795 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2796 hr->verify_rem_set();
2797 }
2798 return false;
2799 }
2800 };
2801
2802 uint G1CollectedHeap::num_task_queues() const {
2803 return _task_queues->size();
2804 }
2805
2806 #if TASKQUEUE_STATS
2807 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2808 st->print_raw_cr("GC Task Stats");
2809 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2810 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2811 }
2812
2813 void G1CollectedHeap::print_taskqueue_stats() const {
2814 if (!log_is_enabled(Trace, gc, task, stats)) {
2815 return;
2816 }
2817 Log(gc, task, stats) log;
2818 ResourceMark rm;
2819 LogStream ls(log.trace());
2820 outputStream* st = &ls;
2821
2822 print_taskqueue_stats_hdr(st);
2823
2824 TaskQueueStats totals;
2825 const uint n = num_task_queues();
2826 for (uint i = 0; i < n; ++i) {
2827 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2828 totals += task_queue(i)->stats;
2829 }
2830 st->print_raw("tot "); totals.print(st); st->cr();
2831
2832 DEBUG_ONLY(totals.verify());
2833 }
2834
2835 void G1CollectedHeap::reset_taskqueue_stats() {
2836 const uint n = num_task_queues();
2837 for (uint i = 0; i < n; ++i) {
2838 task_queue(i)->stats.reset();
2839 }
2840 }
2841 #endif // TASKQUEUE_STATS
2842
2843 void G1CollectedHeap::wait_for_root_region_scanning() {
2844 double scan_wait_start = os::elapsedTime();
2845 // We have to wait until the CM threads finish scanning the
2846 // root regions as it's the only way to ensure that all the
2847 // objects on them have been correctly scanned before we start
2848 // moving them during the GC.
2849 bool waited = _cm->root_regions()->wait_until_scan_finished();
2850 double wait_time_ms = 0.0;
2851 if (waited) {
2852 double scan_wait_end = os::elapsedTime();
2853 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2854 }
2855 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2856 }
2857
2858 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2859 private:
2860 G1HRPrinter* _hr_printer;
2861 public:
2862 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2863
2864 virtual bool do_heap_region(HeapRegion* r) {
2865 _hr_printer->cset(r);
2866 return false;
2867 }
2868 };
2869
2870 void G1CollectedHeap::start_new_collection_set() {
2871 double start = os::elapsedTime();
2872
2873 collection_set()->start_incremental_building();
2874
2875 clear_cset_fast_test();
2876
2877 guarantee(_eden.length() == 0, "eden should have been cleared");
2878 policy()->transfer_survivors_to_cset(survivor());
2879
2880 // We redo the verification but now wrt to the new CSet which
2881 // has just got initialized after the previous CSet was freed.
2882 _cm->verify_no_collection_set_oops_in_stacks();
2883
2884 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2885 }
2886
2887 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms){
2888 policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2889 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2890
2891 _cm->verify_no_collection_set_oops_in_stacks();
2892
2893 if (_hr_printer.is_active()) {
2894 G1PrintCollectionSetClosure cl(&_hr_printer);
2895 _collection_set.iterate(&cl);
2896 }
2897 }
2898
2899 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2900 if (collector_state()->in_initial_mark_gc()) {
2901 return G1HeapVerifier::G1VerifyConcurrentStart;
2902 } else if (collector_state()->in_young_only_phase()) {
2903 return G1HeapVerifier::G1VerifyYoungNormal;
2904 } else {
2905 return G1HeapVerifier::G1VerifyMixed;
2906 }
2907 }
2908
2909 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2910 if (VerifyRememberedSets) {
2911 log_info(gc, verify)("[Verifying RemSets before GC]");
2912 VerifyRegionRemSetClosure v_cl;
2913 heap_region_iterate(&v_cl);
2914 }
2915 _verifier->verify_before_gc(type);
2916 _verifier->check_bitmaps("GC Start");
2917 }
2918
2919 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2920 if (VerifyRememberedSets) {
2921 log_info(gc, verify)("[Verifying RemSets after GC]");
2922 VerifyRegionRemSetClosure v_cl;
2923 heap_region_iterate(&v_cl);
2924 }
2925 _verifier->verify_after_gc(type);
2926 _verifier->check_bitmaps("GC End");
2927 }
2928
2929 void G1CollectedHeap::expand_heap_after_young_collection(){
2930 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2931 if (expand_bytes > 0) {
2932 // No need for an ergo logging here,
2933 // expansion_amount() does this when it returns a value > 0.
2934 double expand_ms;
2935 if (!expand(expand_bytes, _workers, &expand_ms)) {
2936 // We failed to expand the heap. Cannot do anything about it.
2937 }
2938 phase_times()->record_expand_heap_time(expand_ms);
2939 }
2940 }
2941
2942 const char* G1CollectedHeap::young_gc_name() const {
2943 if (collector_state()->in_initial_mark_gc()) {
2944 return "Pause Young (Concurrent Start)";
2945 } else if (collector_state()->in_young_only_phase()) {
2946 if (collector_state()->in_young_gc_before_mixed()) {
2947 return "Pause Young (Prepare Mixed)";
2948 } else {
2949 return "Pause Young (Normal)";
2950 }
2951 } else {
2952 return "Pause Young (Mixed)";
2953 }
2954 }
2955
2956 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2957 assert_at_safepoint_on_vm_thread();
2958 guarantee(!is_gc_active(), "collection is not reentrant");
2959
2960 if (GCLocker::check_active_before_gc()) {
2961 return false;
2962 }
2963
2964 GCIdMark gc_id_mark;
2965
2966 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2967 ResourceMark rm;
2968
2969 policy()->note_gc_start();
2970
2971 _gc_timer_stw->register_gc_start();
2972 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2973
2974 wait_for_root_region_scanning();
2975
2976 print_heap_before_gc();
2977 print_heap_regions();
2978 trace_heap_before_gc(_gc_tracer_stw);
2979
2980 _verifier->verify_region_sets_optional();
2981 _verifier->verify_dirty_young_regions();
2982
2983 // We should not be doing initial mark unless the conc mark thread is running
2984 if (!_cm_thread->should_terminate()) {
2985 // This call will decide whether this pause is an initial-mark
2986 // pause. If it is, in_initial_mark_gc() will return true
2987 // for the duration of this pause.
2988 policy()->decide_on_conc_mark_initiation();
2989 }
2990
2991 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2992 assert(!collector_state()->in_initial_mark_gc() ||
2993 collector_state()->in_young_only_phase(), "sanity");
2994 // We also do not allow mixed GCs during marking.
2995 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2996
2997 // Record whether this pause is an initial mark. When the current
2998 // thread has completed its logging output and it's safe to signal
2999 // the CM thread, the flag's value in the policy has been reset.
3000 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3001 if (should_start_conc_mark) {
3002 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3003 }
3004
3005 // Inner scope for scope based logging, timers, and stats collection
3006 {
3007 G1EvacuationInfo evacuation_info;
3008
3009 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3010
3011 GCTraceCPUTime tcpu;
3012
3013 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3014
3015 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3016 workers()->active_workers(),
3017 Threads::number_of_non_daemon_threads());
3018 active_workers = workers()->update_active_workers(active_workers);
3019 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3020
3021 G1MonitoringScope ms(g1mm(),
3022 false /* full_gc */,
3023 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3024
3025 G1HeapTransition heap_transition(this);
3026 size_t heap_used_bytes_before_gc = used();
3027
3028 {
3029 IsGCActiveMark x;
3030
3031 gc_prologue(false);
3032
3033 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3034 verify_before_young_collection(verify_type);
3035
3036 {
3037 // The elapsed time induced by the start time below deliberately elides
3038 // the possible verification above.
3039 double sample_start_time_sec = os::elapsedTime();
3040
3041 // Please see comment in g1CollectedHeap.hpp and
3042 // G1CollectedHeap::ref_processing_init() to see how
3043 // reference processing currently works in G1.
3044 _ref_processor_stw->enable_discovery();
3045
3046 // We want to temporarily turn off discovery by the
3047 // CM ref processor, if necessary, and turn it back on
3048 // on again later if we do. Using a scoped
3049 // NoRefDiscovery object will do this.
3050 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3051
3052 policy()->record_collection_pause_start(sample_start_time_sec);
3053
3054 // Forget the current allocation region (we might even choose it to be part
3055 // of the collection set!).
3056 _allocator->release_mutator_alloc_region();
3057
3058 calculate_collection_set(evacuation_info, target_pause_time_ms);
3059
3060 G1ParScanThreadStateSet per_thread_states(this,
3061 workers()->active_workers(),
3062 collection_set()->young_region_length(),
3063 collection_set()->optional_region_length());
3064 pre_evacuate_collection_set(evacuation_info);
3065
3066 // Actually do the work...
3067 evacuate_collection_set(&per_thread_states);
3068 evacuate_optional_collection_set(&per_thread_states);
3069
3070 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3071
3072 start_new_collection_set();
3073
3074 _survivor_evac_stats.adjust_desired_plab_sz();
3075 _old_evac_stats.adjust_desired_plab_sz();
3076
3077 if (should_start_conc_mark) {
3078 // We have to do this before we notify the CM threads that
3079 // they can start working to make sure that all the
3080 // appropriate initialization is done on the CM object.
3081 concurrent_mark()->post_initial_mark();
3082 // Note that we don't actually trigger the CM thread at
3083 // this point. We do that later when we're sure that
3084 // the current thread has completed its logging output.
3085 }
3086
3087 allocate_dummy_regions();
3088
3089 _allocator->init_mutator_alloc_region();
3090
3091 expand_heap_after_young_collection();
3092
3093 double sample_end_time_sec = os::elapsedTime();
3094 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3095 size_t total_cards_scanned = phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3096 policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3097 }
3098
3099 verify_after_young_collection(verify_type);
3100
3101 #ifdef TRACESPINNING
3102 ParallelTaskTerminator::print_termination_counts();
3103 #endif
3104
3105 gc_epilogue(false);
3106 }
3107
3108 // Print the remainder of the GC log output.
3109 if (evacuation_failed()) {
3110 log_info(gc)("To-space exhausted");
3111 }
3112
3113 policy()->print_phases();
3114 heap_transition.print();
3115
3116 _hrm->verify_optional();
3117 _verifier->verify_region_sets_optional();
3118
3119 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3120 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3121
3122 print_heap_after_gc();
3123 print_heap_regions();
3124 trace_heap_after_gc(_gc_tracer_stw);
3125
3126 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3127 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3128 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3129 // before any GC notifications are raised.
3130 g1mm()->update_sizes();
3131
3132 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3133 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3134 _gc_timer_stw->register_gc_end();
3135 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3136 }
3137 // It should now be safe to tell the concurrent mark thread to start
3138 // without its logging output interfering with the logging output
3139 // that came from the pause.
3140
3141 if (should_start_conc_mark) {
3142 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3143 // thread(s) could be running concurrently with us. Make sure that anything
3144 // after this point does not assume that we are the only GC thread running.
3145 // Note: of course, the actual marking work will not start until the safepoint
3146 // itself is released in SuspendibleThreadSet::desynchronize().
3147 do_concurrent_mark();
3148 }
3149
3150 return true;
3151 }
3152
3153 void G1CollectedHeap::remove_self_forwarding_pointers() {
3154 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3155 workers()->run_task(&rsfp_task);
3156 }
3157
3158 void G1CollectedHeap::restore_after_evac_failure() {
3159 double remove_self_forwards_start = os::elapsedTime();
3160
3161 remove_self_forwarding_pointers();
3162 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3163 _preserved_marks_set.restore(&task_executor);
3164
3165 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3166 }
3167
3168 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3169 if (!_evacuation_failed) {
3170 _evacuation_failed = true;
3171 }
3172
3173 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3174 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3175 }
3176
3177 bool G1ParEvacuateFollowersClosure::offer_termination() {
3178 EventGCPhaseParallel event;
3179 G1ParScanThreadState* const pss = par_scan_state();
3180 start_term_time();
3181 const bool res = terminator()->offer_termination();
3182 end_term_time();
3183 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3184 return res;
3185 }
3186
3187 void G1ParEvacuateFollowersClosure::do_void() {
3188 EventGCPhaseParallel event;
3189 G1ParScanThreadState* const pss = par_scan_state();
3190 pss->trim_queue();
3191 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3192 do {
3193 EventGCPhaseParallel event;
3194 pss->steal_and_trim_queue(queues());
3195 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3196 } while (!offer_termination());
3197 }
3198
3199 class G1ParTask : public AbstractGangTask {
3200 protected:
3201 G1CollectedHeap* _g1h;
3202 G1ParScanThreadStateSet* _pss;
3203 RefToScanQueueSet* _queues;
3204 G1RootProcessor* _root_processor;
3205 TaskTerminator _terminator;
3206 uint _n_workers;
3207
3208 public:
3209 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3210 : AbstractGangTask("G1 collection"),
3211 _g1h(g1h),
3212 _pss(per_thread_states),
3213 _queues(task_queues),
3214 _root_processor(root_processor),
3215 _terminator(n_workers, _queues),
3216 _n_workers(n_workers)
3217 {}
3218
3219 void work(uint worker_id) {
3220 if (worker_id >= _n_workers) return; // no work needed this round
3221
3222 double start_sec = os::elapsedTime();
3223 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3224
3225 {
3226 ResourceMark rm;
3227 HandleMark hm;
3228
3229 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3230
3231 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3232 pss->set_ref_discoverer(rp);
3233
3234 double start_strong_roots_sec = os::elapsedTime();
3235
3236 _root_processor->evacuate_roots(pss, worker_id);
3237
3238 _g1h->rem_set()->oops_into_collection_set_do(pss, worker_id);
3239
3240 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3241
3242 double term_sec = 0.0;
3243 size_t evac_term_attempts = 0;
3244 {
3245 double start = os::elapsedTime();
3246 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, _terminator.terminator(), G1GCPhaseTimes::ObjCopy);
3247 evac.do_void();
3248
3249 evac_term_attempts = evac.term_attempts();
3250 term_sec = evac.term_time();
3251 double elapsed_sec = os::elapsedTime() - start;
3252
3253 G1GCPhaseTimes* p = _g1h->phase_times();
3254 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3255
3256 p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy,
3257 worker_id,
3258 pss->lab_waste_words() * HeapWordSize,
3259 G1GCPhaseTimes::ObjCopyLABWaste);
3260 p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy,
3261 worker_id,
3262 pss->lab_undo_waste_words() * HeapWordSize,
3263 G1GCPhaseTimes::ObjCopyLABUndoWaste);
3264
3265 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3266 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3267 }
3268
3269 assert(pss->queue_is_empty(), "should be empty");
3270
3271 // Close the inner scope so that the ResourceMark and HandleMark
3272 // destructors are executed here and are included as part of the
3273 // "GC Worker Time".
3274 }
3275 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3276 }
3277 };
3278
3279 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3280 bool class_unloading_occurred) {
3281 uint num_workers = workers()->active_workers();
3282 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3283 workers()->run_task(&unlink_task);
3284 }
3285
3286 // Clean string dedup data structures.
3287 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3288 // record the durations of the phases. Hence the almost-copy.
3289 class G1StringDedupCleaningTask : public AbstractGangTask {
3290 BoolObjectClosure* _is_alive;
3291 OopClosure* _keep_alive;
3292 G1GCPhaseTimes* _phase_times;
3293
3294 public:
3295 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3296 OopClosure* keep_alive,
3297 G1GCPhaseTimes* phase_times) :
3298 AbstractGangTask("Partial Cleaning Task"),
3299 _is_alive(is_alive),
3300 _keep_alive(keep_alive),
3301 _phase_times(phase_times)
3302 {
3303 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3304 StringDedup::gc_prologue(true);
3305 }
3306
3307 ~G1StringDedupCleaningTask() {
3308 StringDedup::gc_epilogue();
3309 }
3310
3311 void work(uint worker_id) {
3312 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3313 {
3314 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3315 StringDedupQueue::unlink_or_oops_do(&cl);
3316 }
3317 {
3318 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3319 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3320 }
3321 }
3322 };
3323
3324 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3325 OopClosure* keep_alive,
3326 G1GCPhaseTimes* phase_times) {
3327 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3328 workers()->run_task(&cl);
3329 }
3330
3331 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3332 private:
3333 G1DirtyCardQueueSet* _queue;
3334 G1CollectedHeap* _g1h;
3335 public:
3336 G1RedirtyLoggedCardsTask(G1DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3337 _queue(queue), _g1h(g1h) { }
3338
3339 virtual void work(uint worker_id) {
3340 G1GCPhaseTimes* p = _g1h->phase_times();
3341 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3342
3343 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3344 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3345
3346 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3347 }
3348 };
3349
3350 void G1CollectedHeap::redirty_logged_cards() {
3351 double redirty_logged_cards_start = os::elapsedTime();
3352
3353 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3354 dirty_card_queue_set().reset_for_par_iteration();
3355 workers()->run_task(&redirty_task);
3356
3357 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3358 dcq.merge_bufferlists(&dirty_card_queue_set());
3359 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3360
3361 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3362 }
3363
3364 // Weak Reference Processing support
3365
3366 bool G1STWIsAliveClosure::do_object_b(oop p) {
3367 // An object is reachable if it is outside the collection set,
3368 // or is inside and copied.
3369 return !_g1h->is_in_cset(p) || p->is_forwarded();
3370 }
3371
3372 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3373 assert(obj != NULL, "must not be NULL");
3374 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3375 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3376 // may falsely indicate that this is not the case here: however the collection set only
3377 // contains old regions when concurrent mark is not running.
3378 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3379 }
3380
3381 // Non Copying Keep Alive closure
3382 class G1KeepAliveClosure: public OopClosure {
3383 G1CollectedHeap*_g1h;
3384 public:
3385 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3386 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3387 void do_oop(oop* p) {
3388 oop obj = *p;
3389 assert(obj != NULL, "the caller should have filtered out NULL values");
3390
3391 const InCSetState cset_state =_g1h->in_cset_state(obj);
3392 if (!cset_state.is_in_cset_or_humongous()) {
3393 return;
3394 }
3395 if (cset_state.is_in_cset()) {
3396 assert( obj->is_forwarded(), "invariant" );
3397 *p = obj->forwardee();
3398 } else {
3399 assert(!obj->is_forwarded(), "invariant" );
3400 assert(cset_state.is_humongous(),
3401 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3402 _g1h->set_humongous_is_live(obj);
3403 }
3404 }
3405 };
3406
3407 // Copying Keep Alive closure - can be called from both
3408 // serial and parallel code as long as different worker
3409 // threads utilize different G1ParScanThreadState instances
3410 // and different queues.
3411
3412 class G1CopyingKeepAliveClosure: public OopClosure {
3413 G1CollectedHeap* _g1h;
3414 G1ParScanThreadState* _par_scan_state;
3415
3416 public:
3417 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3418 G1ParScanThreadState* pss):
3419 _g1h(g1h),
3420 _par_scan_state(pss)
3421 {}
3422
3423 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3424 virtual void do_oop( oop* p) { do_oop_work(p); }
3425
3426 template <class T> void do_oop_work(T* p) {
3427 oop obj = RawAccess<>::oop_load(p);
3428
3429 if (_g1h->is_in_cset_or_humongous(obj)) {
3430 // If the referent object has been forwarded (either copied
3431 // to a new location or to itself in the event of an
3432 // evacuation failure) then we need to update the reference
3433 // field and, if both reference and referent are in the G1
3434 // heap, update the RSet for the referent.
3435 //
3436 // If the referent has not been forwarded then we have to keep
3437 // it alive by policy. Therefore we have copy the referent.
3438 //
3439 // When the queue is drained (after each phase of reference processing)
3440 // the object and it's followers will be copied, the reference field set
3441 // to point to the new location, and the RSet updated.
3442 _par_scan_state->push_on_queue(p);
3443 }
3444 }
3445 };
3446
3447 // Serial drain queue closure. Called as the 'complete_gc'
3448 // closure for each discovered list in some of the
3449 // reference processing phases.
3450
3451 class G1STWDrainQueueClosure: public VoidClosure {
3452 protected:
3453 G1CollectedHeap* _g1h;
3454 G1ParScanThreadState* _par_scan_state;
3455
3456 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3457
3458 public:
3459 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3460 _g1h(g1h),
3461 _par_scan_state(pss)
3462 { }
3463
3464 void do_void() {
3465 G1ParScanThreadState* const pss = par_scan_state();
3466 pss->trim_queue();
3467 }
3468 };
3469
3470 // Parallel Reference Processing closures
3471
3472 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3473 // processing during G1 evacuation pauses.
3474
3475 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3476 private:
3477 G1CollectedHeap* _g1h;
3478 G1ParScanThreadStateSet* _pss;
3479 RefToScanQueueSet* _queues;
3480 WorkGang* _workers;
3481
3482 public:
3483 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3484 G1ParScanThreadStateSet* per_thread_states,
3485 WorkGang* workers,
3486 RefToScanQueueSet *task_queues) :
3487 _g1h(g1h),
3488 _pss(per_thread_states),
3489 _queues(task_queues),
3490 _workers(workers)
3491 {
3492 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3493 }
3494
3495 // Executes the given task using concurrent marking worker threads.
3496 virtual void execute(ProcessTask& task, uint ergo_workers);
3497 };
3498
3499 // Gang task for possibly parallel reference processing
3500
3501 class G1STWRefProcTaskProxy: public AbstractGangTask {
3502 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3503 ProcessTask& _proc_task;
3504 G1CollectedHeap* _g1h;
3505 G1ParScanThreadStateSet* _pss;
3506 RefToScanQueueSet* _task_queues;
3507 ParallelTaskTerminator* _terminator;
3508
3509 public:
3510 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3511 G1CollectedHeap* g1h,
3512 G1ParScanThreadStateSet* per_thread_states,
3513 RefToScanQueueSet *task_queues,
3514 ParallelTaskTerminator* terminator) :
3515 AbstractGangTask("Process reference objects in parallel"),
3516 _proc_task(proc_task),
3517 _g1h(g1h),
3518 _pss(per_thread_states),
3519 _task_queues(task_queues),
3520 _terminator(terminator)
3521 {}
3522
3523 virtual void work(uint worker_id) {
3524 // The reference processing task executed by a single worker.
3525 ResourceMark rm;
3526 HandleMark hm;
3527
3528 G1STWIsAliveClosure is_alive(_g1h);
3529
3530 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3531 pss->set_ref_discoverer(NULL);
3532
3533 // Keep alive closure.
3534 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3535
3536 // Complete GC closure
3537 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3538
3539 // Call the reference processing task's work routine.
3540 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3541
3542 // Note we cannot assert that the refs array is empty here as not all
3543 // of the processing tasks (specifically phase2 - pp2_work) execute
3544 // the complete_gc closure (which ordinarily would drain the queue) so
3545 // the queue may not be empty.
3546 }
3547 };
3548
3549 // Driver routine for parallel reference processing.
3550 // Creates an instance of the ref processing gang
3551 // task and has the worker threads execute it.
3552 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3553 assert(_workers != NULL, "Need parallel worker threads.");
3554
3555 assert(_workers->active_workers() >= ergo_workers,
3556 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3557 ergo_workers, _workers->active_workers());
3558 TaskTerminator terminator(ergo_workers, _queues);
3559 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3560
3561 _workers->run_task(&proc_task_proxy, ergo_workers);
3562 }
3563
3564 // End of weak reference support closures
3565
3566 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3567 double ref_proc_start = os::elapsedTime();
3568
3569 ReferenceProcessor* rp = _ref_processor_stw;
3570 assert(rp->discovery_enabled(), "should have been enabled");
3571
3572 // Closure to test whether a referent is alive.
3573 G1STWIsAliveClosure is_alive(this);
3574
3575 // Even when parallel reference processing is enabled, the processing
3576 // of JNI refs is serial and performed serially by the current thread
3577 // rather than by a worker. The following PSS will be used for processing
3578 // JNI refs.
3579
3580 // Use only a single queue for this PSS.
3581 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3582 pss->set_ref_discoverer(NULL);
3583 assert(pss->queue_is_empty(), "pre-condition");
3584
3585 // Keep alive closure.
3586 G1CopyingKeepAliveClosure keep_alive(this, pss);
3587
3588 // Serial Complete GC closure
3589 G1STWDrainQueueClosure drain_queue(this, pss);
3590
3591 // Setup the soft refs policy...
3592 rp->setup_policy(false);
3593
3594 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3595
3596 ReferenceProcessorStats stats;
3597 if (!rp->processing_is_mt()) {
3598 // Serial reference processing...
3599 stats = rp->process_discovered_references(&is_alive,
3600 &keep_alive,
3601 &drain_queue,
3602 NULL,
3603 pt);
3604 } else {
3605 uint no_of_gc_workers = workers()->active_workers();
3606
3607 // Parallel reference processing
3608 assert(no_of_gc_workers <= rp->max_num_queues(),
3609 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3610 no_of_gc_workers, rp->max_num_queues());
3611
3612 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3613 stats = rp->process_discovered_references(&is_alive,
3614 &keep_alive,
3615 &drain_queue,
3616 &par_task_executor,
3617 pt);
3618 }
3619
3620 _gc_tracer_stw->report_gc_reference_stats(stats);
3621
3622 // We have completed copying any necessary live referent objects.
3623 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3624
3625 make_pending_list_reachable();
3626
3627 assert(!rp->discovery_enabled(), "Postcondition");
3628 rp->verify_no_references_recorded();
3629
3630 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3631 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3632 }
3633
3634 void G1CollectedHeap::make_pending_list_reachable() {
3635 if (collector_state()->in_initial_mark_gc()) {
3636 oop pll_head = Universe::reference_pending_list();
3637 if (pll_head != NULL) {
3638 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3639 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3640 }
3641 }
3642 }
3643
3644 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3645 double merge_pss_time_start = os::elapsedTime();
3646 per_thread_states->flush();
3647 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3648 }
3649
3650 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info) {
3651 _expand_heap_after_alloc_failure = true;
3652 _evacuation_failed = false;
3653
3654 // Disable the hot card cache.
3655 _hot_card_cache->reset_hot_cache_claimed_index();
3656 _hot_card_cache->set_use_cache(false);
3657
3658 // Initialize the GC alloc regions.
3659 _allocator->init_gc_alloc_regions(evacuation_info);
3660
3661 register_humongous_regions_with_cset();
3662 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3663
3664 rem_set()->prepare_for_oops_into_collection_set_do();
3665 _preserved_marks_set.assert_empty();
3666
3667 #if COMPILER2_OR_JVMCI
3668 DerivedPointerTable::clear();
3669 #endif
3670
3671 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3672 if (collector_state()->in_initial_mark_gc()) {
3673 concurrent_mark()->pre_initial_mark();
3674
3675 double start_clear_claimed_marks = os::elapsedTime();
3676
3677 ClassLoaderDataGraph::clear_claimed_marks();
3678
3679 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3680 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3681 }
3682 }
3683
3684 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3685 // Should G1EvacuationFailureALot be in effect for this GC?
3686 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3687
3688 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3689
3690 double start_par_time_sec = os::elapsedTime();
3691 double end_par_time_sec;
3692
3693 {
3694 const uint n_workers = workers()->active_workers();
3695 G1RootProcessor root_processor(this, n_workers);
3696 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3697
3698 workers()->run_task(&g1_par_task);
3699 end_par_time_sec = os::elapsedTime();
3700
3701 // Closing the inner scope will execute the destructor
3702 // for the G1RootProcessor object. We record the current
3703 // elapsed time before closing the scope so that time
3704 // taken for the destructor is NOT included in the
3705 // reported parallel time.
3706 }
3707
3708 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3709 phase_times()->record_par_time(par_time_ms);
3710
3711 double code_root_fixup_time_ms =
3712 (os::elapsedTime() - end_par_time_sec) * 1000.0;
3713 phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
3714 }
3715
3716 class G1EvacuateOptionalRegionTask : public AbstractGangTask {
3717 G1CollectedHeap* _g1h;
3718 G1ParScanThreadStateSet* _per_thread_states;
3719 G1OptionalCSet* _optional;
3720 RefToScanQueueSet* _queues;
3721 ParallelTaskTerminator _terminator;
3722
3723 Tickspan trim_ticks(G1ParScanThreadState* pss) {
3724 Tickspan copy_time = pss->trim_ticks();
3725 pss->reset_trim_ticks();
3726 return copy_time;
3727 }
3728
3729 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3730 G1EvacuationRootClosures* root_cls = pss->closures();
3731 G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss);
3732
3733 size_t scanned = 0;
3734 size_t claimed = 0;
3735 size_t skipped = 0;
3736 size_t used_memory = 0;
3737
3738 Ticks start = Ticks::now();
3739 Tickspan copy_time;
3740
3741 for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) {
3742 HeapRegion* hr = _optional->region_at(i);
3743 G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl);
3744 pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops());
3745 copy_time += trim_ticks(pss);
3746
3747 G1ScanRSForRegionClosure scan_rs_cl(_g1h->rem_set()->scan_state(), &obj_cl, pss, G1GCPhaseTimes::OptScanRS, worker_id);
3748 scan_rs_cl.do_heap_region(hr);
3749 copy_time += trim_ticks(pss);
3750 scanned += scan_rs_cl.cards_scanned();
3751 claimed += scan_rs_cl.cards_claimed();
3752 skipped += scan_rs_cl.cards_skipped();
3753
3754 // Chunk lists for this region is no longer needed.
3755 used_memory += pss->oops_into_optional_region(hr)->used_memory();
3756 }
3757
3758 Tickspan scan_time = (Ticks::now() - start) - copy_time;
3759 G1GCPhaseTimes* p = _g1h->phase_times();
3760 p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds());
3761 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds());
3762
3763 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards);
3764 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards);
3765 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards);
3766 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, used_memory, G1GCPhaseTimes::OptCSetUsedMemory);
3767 }
3768
3769 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3770 Ticks start = Ticks::now();
3771 G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy);
3772 cl.do_void();
3773
3774 Tickspan evac_time = (Ticks::now() - start);
3775 G1GCPhaseTimes* p = _g1h->phase_times();
3776 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds());
3777 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation");
3778 }
3779
3780 public:
3781 G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h,
3782 G1ParScanThreadStateSet* per_thread_states,
3783 G1OptionalCSet* cset,
3784 RefToScanQueueSet* queues,
3785 uint n_workers) :
3786 AbstractGangTask("G1 Evacuation Optional Region Task"),
3787 _g1h(g1h),
3788 _per_thread_states(per_thread_states),
3789 _optional(cset),
3790 _queues(queues),
3791 _terminator(n_workers, _queues) {
3792 }
3793
3794 void work(uint worker_id) {
3795 ResourceMark rm;
3796 HandleMark hm;
3797
3798 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3799 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3800
3801 scan_roots(pss, worker_id);
3802 evacuate_live_objects(pss, worker_id);
3803 }
3804 };
3805
3806 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) {
3807 class G1MarkScope : public MarkScope {};
3808 G1MarkScope code_mark_scope;
3809
3810 G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers());
3811 workers()->run_task(&task);
3812 }
3813
3814 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3815 G1OptionalCSet optional_cset(&_collection_set, per_thread_states);
3816 if (optional_cset.is_empty()) {
3817 return;
3818 }
3819
3820 if (evacuation_failed()) {
3821 return;
3822 }
3823
3824 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3825
3826 double start_time_sec = os::elapsedTime();
3827
3828 do {
3829 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3830 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3831
3832 if (time_left_ms < 0) {
3833 log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms);
3834 break;
3835 }
3836
3837 optional_cset.prepare_evacuation(time_left_ms * _policy->optional_evacuation_fraction());
3838 if (optional_cset.prepare_failed()) {
3839 log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms);
3840 break;
3841 }
3842
3843 evacuate_optional_regions(per_thread_states, &optional_cset);
3844
3845 optional_cset.complete_evacuation();
3846 if (optional_cset.evacuation_failed()) {
3847 break;
3848 }
3849 } while (!optional_cset.is_empty());
3850
3851 phase_times()->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0);
3852 }
3853
3854 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3855 // Also cleans the card table from temporary duplicate detection information used
3856 // during UpdateRS/ScanRS.
3857 rem_set()->cleanup_after_oops_into_collection_set_do();
3858
3859 // Process any discovered reference objects - we have
3860 // to do this _before_ we retire the GC alloc regions
3861 // as we may have to copy some 'reachable' referent
3862 // objects (and their reachable sub-graphs) that were
3863 // not copied during the pause.
3864 process_discovered_references(per_thread_states);
3865
3866 G1STWIsAliveClosure is_alive(this);
3867 G1KeepAliveClosure keep_alive(this);
3868
3869 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3870 phase_times()->weak_phase_times());
3871
3872 if (G1StringDedup::is_enabled()) {
3873 double string_dedup_time_ms = os::elapsedTime();
3874
3875 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3876
3877 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3878 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3879 }
3880
3881 _allocator->release_gc_alloc_regions(evacuation_info);
3882
3883 if (evacuation_failed()) {
3884 restore_after_evac_failure();
3885
3886 // Reset the G1EvacuationFailureALot counters and flags
3887 NOT_PRODUCT(reset_evacuation_should_fail();)
3888
3889 double recalculate_used_start = os::elapsedTime();
3890 set_used(recalculate_used());
3891 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3892
3893 if (_archive_allocator != NULL) {
3894 _archive_allocator->clear_used();
3895 }
3896 for (uint i = 0; i < ParallelGCThreads; i++) {
3897 if (_evacuation_failed_info_array[i].has_failed()) {
3898 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3899 }
3900 }
3901 } else {
3902 // The "used" of the the collection set have already been subtracted
3903 // when they were freed. Add in the bytes evacuated.
3904 increase_used(policy()->bytes_copied_during_gc());
3905 }
3906
3907 _preserved_marks_set.assert_empty();
3908
3909 merge_per_thread_state_info(per_thread_states);
3910
3911 // Reset and re-enable the hot card cache.
3912 // Note the counts for the cards in the regions in the
3913 // collection set are reset when the collection set is freed.
3914 _hot_card_cache->reset_hot_cache();
3915 _hot_card_cache->set_use_cache(true);
3916
3917 purge_code_root_memory();
3918
3919 redirty_logged_cards();
3920
3921 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3922
3923 eagerly_reclaim_humongous_regions();
3924
3925 record_obj_copy_mem_stats();
3926
3927 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3928 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3929
3930 #if COMPILER2_OR_JVMCI
3931 double start = os::elapsedTime();
3932 DerivedPointerTable::update_pointers();
3933 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3934 #endif
3935 policy()->print_age_table();
3936 }
3937
3938 void G1CollectedHeap::record_obj_copy_mem_stats() {
3939 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3940
3941 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3942 create_g1_evac_summary(&_old_evac_stats));
3943 }
3944
3945 void G1CollectedHeap::free_region(HeapRegion* hr,
3946 FreeRegionList* free_list,
3947 bool skip_remset,
3948 bool skip_hot_card_cache,
3949 bool locked) {
3950 assert(!hr->is_free(), "the region should not be free");
3951 assert(!hr->is_empty(), "the region should not be empty");
3952 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3953 assert(free_list != NULL, "pre-condition");
3954
3955 if (G1VerifyBitmaps) {
3956 MemRegion mr(hr->bottom(), hr->end());
3957 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3958 }
3959
3960 // Clear the card counts for this region.
3961 // Note: we only need to do this if the region is not young
3962 // (since we don't refine cards in young regions).
3963 if (!skip_hot_card_cache && !hr->is_young()) {
3964 _hot_card_cache->reset_card_counts(hr);
3965 }
3966 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3967 _policy->remset_tracker()->update_at_free(hr);
3968 free_list->add_ordered(hr);
3969 }
3970
3971 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3972 FreeRegionList* free_list) {
3973 assert(hr->is_humongous(), "this is only for humongous regions");
3974 assert(free_list != NULL, "pre-condition");
3975 hr->clear_humongous();
3976 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3977 }
3978
3979 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3980 const uint humongous_regions_removed) {
3981 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3982 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3983 _old_set.bulk_remove(old_regions_removed);
3984 _humongous_set.bulk_remove(humongous_regions_removed);
3985 }
3986
3987 }
3988
3989 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3990 assert(list != NULL, "list can't be null");
3991 if (!list->is_empty()) {
3992 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3993 _hrm->insert_list_into_free_list(list);
3994 }
3995 }
3996
3997 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3998 decrease_used(bytes);
3999 }
4000
4001 class G1FreeCollectionSetTask : public AbstractGangTask {
4002 private:
4003
4004 // Closure applied to all regions in the collection set to do work that needs to
4005 // be done serially in a single thread.
4006 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4007 private:
4008 G1EvacuationInfo* _evacuation_info;
4009 const size_t* _surviving_young_words;
4010
4011 // Bytes used in successfully evacuated regions before the evacuation.
4012 size_t _before_used_bytes;
4013 // Bytes used in unsucessfully evacuated regions before the evacuation
4014 size_t _after_used_bytes;
4015
4016 size_t _bytes_allocated_in_old_since_last_gc;
4017
4018 size_t _failure_used_words;
4019 size_t _failure_waste_words;
4020
4021 FreeRegionList _local_free_list;
4022 public:
4023 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4024 HeapRegionClosure(),
4025 _evacuation_info(evacuation_info),
4026 _surviving_young_words(surviving_young_words),
4027 _before_used_bytes(0),
4028 _after_used_bytes(0),
4029 _bytes_allocated_in_old_since_last_gc(0),
4030 _failure_used_words(0),
4031 _failure_waste_words(0),
4032 _local_free_list("Local Region List for CSet Freeing") {
4033 }
4034
4035 virtual bool do_heap_region(HeapRegion* r) {
4036 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4037
4038 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4039 g1h->clear_in_cset(r);
4040
4041 if (r->is_young()) {
4042 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4043 "Young index %d is wrong for region %u of type %s with %u young regions",
4044 r->young_index_in_cset(),
4045 r->hrm_index(),
4046 r->get_type_str(),
4047 g1h->collection_set()->young_region_length());
4048 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4049 r->record_surv_words_in_group(words_survived);
4050 }
4051
4052 if (!r->evacuation_failed()) {
4053 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4054 _before_used_bytes += r->used();
4055 g1h->free_region(r,
4056 &_local_free_list,
4057 true, /* skip_remset */
4058 true, /* skip_hot_card_cache */
4059 true /* locked */);
4060 } else {
4061 r->uninstall_surv_rate_group();
4062 r->set_young_index_in_cset(-1);
4063 r->set_evacuation_failed(false);
4064 // When moving a young gen region to old gen, we "allocate" that whole region
4065 // there. This is in addition to any already evacuated objects. Notify the
4066 // policy about that.
4067 // Old gen regions do not cause an additional allocation: both the objects
4068 // still in the region and the ones already moved are accounted for elsewhere.
4069 if (r->is_young()) {
4070 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4071 }
4072 // The region is now considered to be old.
4073 r->set_old();
4074 // Do some allocation statistics accounting. Regions that failed evacuation
4075 // are always made old, so there is no need to update anything in the young
4076 // gen statistics, but we need to update old gen statistics.
4077 size_t used_words = r->marked_bytes() / HeapWordSize;
4078
4079 _failure_used_words += used_words;
4080 _failure_waste_words += HeapRegion::GrainWords - used_words;
4081
4082 g1h->old_set_add(r);
4083 _after_used_bytes += r->used();
4084 }
4085 return false;
4086 }
4087
4088 void complete_work() {
4089 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4090
4091 _evacuation_info->set_regions_freed(_local_free_list.length());
4092 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4093
4094 g1h->prepend_to_freelist(&_local_free_list);
4095 g1h->decrement_summary_bytes(_before_used_bytes);
4096
4097 G1Policy* policy = g1h->policy();
4098 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4099
4100 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4101 }
4102 };
4103
4104 G1CollectionSet* _collection_set;
4105 G1SerialFreeCollectionSetClosure _cl;
4106 const size_t* _surviving_young_words;
4107
4108 size_t _rs_lengths;
4109
4110 volatile jint _serial_work_claim;
4111
4112 struct WorkItem {
4113 uint region_idx;
4114 bool is_young;
4115 bool evacuation_failed;
4116
4117 WorkItem(HeapRegion* r) {
4118 region_idx = r->hrm_index();
4119 is_young = r->is_young();
4120 evacuation_failed = r->evacuation_failed();
4121 }
4122 };
4123
4124 volatile size_t _parallel_work_claim;
4125 size_t _num_work_items;
4126 WorkItem* _work_items;
4127
4128 void do_serial_work() {
4129 // Need to grab the lock to be allowed to modify the old region list.
4130 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4131 _collection_set->iterate(&_cl);
4132 }
4133
4134 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4135 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4136
4137 HeapRegion* r = g1h->region_at(region_idx);
4138 assert(!g1h->is_on_master_free_list(r), "sanity");
4139
4140 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4141
4142 if (!is_young) {
4143 g1h->_hot_card_cache->reset_card_counts(r);
4144 }
4145
4146 if (!evacuation_failed) {
4147 r->rem_set()->clear_locked();
4148 }
4149 }
4150
4151 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4152 private:
4153 size_t _cur_idx;
4154 WorkItem* _work_items;
4155 public:
4156 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4157
4158 virtual bool do_heap_region(HeapRegion* r) {
4159 _work_items[_cur_idx++] = WorkItem(r);
4160 return false;
4161 }
4162 };
4163
4164 void prepare_work() {
4165 G1PrepareFreeCollectionSetClosure cl(_work_items);
4166 _collection_set->iterate(&cl);
4167 }
4168
4169 void complete_work() {
4170 _cl.complete_work();
4171
4172 G1Policy* policy = G1CollectedHeap::heap()->policy();
4173 policy->record_max_rs_lengths(_rs_lengths);
4174 policy->cset_regions_freed();
4175 }
4176 public:
4177 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4178 AbstractGangTask("G1 Free Collection Set"),
4179 _collection_set(collection_set),
4180 _cl(evacuation_info, surviving_young_words),
4181 _surviving_young_words(surviving_young_words),
4182 _rs_lengths(0),
4183 _serial_work_claim(0),
4184 _parallel_work_claim(0),
4185 _num_work_items(collection_set->region_length()),
4186 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4187 prepare_work();
4188 }
4189
4190 ~G1FreeCollectionSetTask() {
4191 complete_work();
4192 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4193 }
4194
4195 // Chunk size for work distribution. The chosen value has been determined experimentally
4196 // to be a good tradeoff between overhead and achievable parallelism.
4197 static uint chunk_size() { return 32; }
4198
4199 virtual void work(uint worker_id) {
4200 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4201
4202 // Claim serial work.
4203 if (_serial_work_claim == 0) {
4204 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4205 if (value == 0) {
4206 double serial_time = os::elapsedTime();
4207 do_serial_work();
4208 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4209 }
4210 }
4211
4212 // Start parallel work.
4213 double young_time = 0.0;
4214 bool has_young_time = false;
4215 double non_young_time = 0.0;
4216 bool has_non_young_time = false;
4217
4218 while (true) {
4219 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4220 size_t cur = end - chunk_size();
4221
4222 if (cur >= _num_work_items) {
4223 break;
4224 }
4225
4226 EventGCPhaseParallel event;
4227 double start_time = os::elapsedTime();
4228
4229 end = MIN2(end, _num_work_items);
4230
4231 for (; cur < end; cur++) {
4232 bool is_young = _work_items[cur].is_young;
4233
4234 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4235
4236 double end_time = os::elapsedTime();
4237 double time_taken = end_time - start_time;
4238 if (is_young) {
4239 young_time += time_taken;
4240 has_young_time = true;
4241 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4242 } else {
4243 non_young_time += time_taken;
4244 has_non_young_time = true;
4245 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4246 }
4247 start_time = end_time;
4248 }
4249 }
4250
4251 if (has_young_time) {
4252 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4253 }
4254 if (has_non_young_time) {
4255 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4256 }
4257 }
4258 };
4259
4260 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4261 _eden.clear();
4262
4263 double free_cset_start_time = os::elapsedTime();
4264
4265 {
4266 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4267 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4268
4269 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4270
4271 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4272 cl.name(),
4273 num_workers,
4274 _collection_set.region_length());
4275 workers()->run_task(&cl, num_workers);
4276 }
4277 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4278
4279 collection_set->clear();
4280 }
4281
4282 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4283 private:
4284 FreeRegionList* _free_region_list;
4285 HeapRegionSet* _proxy_set;
4286 uint _humongous_objects_reclaimed;
4287 uint _humongous_regions_reclaimed;
4288 size_t _freed_bytes;
4289 public:
4290
4291 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4292 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4293 }
4294
4295 virtual bool do_heap_region(HeapRegion* r) {
4296 if (!r->is_starts_humongous()) {
4297 return false;
4298 }
4299
4300 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4301
4302 oop obj = (oop)r->bottom();
4303 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4304
4305 // The following checks whether the humongous object is live are sufficient.
4306 // The main additional check (in addition to having a reference from the roots
4307 // or the young gen) is whether the humongous object has a remembered set entry.
4308 //
4309 // A humongous object cannot be live if there is no remembered set for it
4310 // because:
4311 // - there can be no references from within humongous starts regions referencing
4312 // the object because we never allocate other objects into them.
4313 // (I.e. there are no intra-region references that may be missed by the
4314 // remembered set)
4315 // - as soon there is a remembered set entry to the humongous starts region
4316 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4317 // until the end of a concurrent mark.
4318 //
4319 // It is not required to check whether the object has been found dead by marking
4320 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4321 // all objects allocated during that time are considered live.
4322 // SATB marking is even more conservative than the remembered set.
4323 // So if at this point in the collection there is no remembered set entry,
4324 // nobody has a reference to it.
4325 // At the start of collection we flush all refinement logs, and remembered sets
4326 // are completely up-to-date wrt to references to the humongous object.
4327 //
4328 // Other implementation considerations:
4329 // - never consider object arrays at this time because they would pose
4330 // considerable effort for cleaning up the the remembered sets. This is
4331 // required because stale remembered sets might reference locations that
4332 // are currently allocated into.
4333 uint region_idx = r->hrm_index();
4334 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4335 !r->rem_set()->is_empty()) {
4336 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",
4337 region_idx,
4338 (size_t)obj->size() * HeapWordSize,
4339 p2i(r->bottom()),
4340 r->rem_set()->occupied(),
4341 r->rem_set()->strong_code_roots_list_length(),
4342 next_bitmap->is_marked(r->bottom()),
4343 g1h->is_humongous_reclaim_candidate(region_idx),
4344 obj->is_typeArray()
4345 );
4346 return false;
4347 }
4348
4349 guarantee(obj->is_typeArray(),
4350 "Only eagerly reclaiming type arrays is supported, but the object "
4351 PTR_FORMAT " is not.", p2i(r->bottom()));
4352
4353 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",
4354 region_idx,
4355 (size_t)obj->size() * HeapWordSize,
4356 p2i(r->bottom()),
4357 r->rem_set()->occupied(),
4358 r->rem_set()->strong_code_roots_list_length(),
4359 next_bitmap->is_marked(r->bottom()),
4360 g1h->is_humongous_reclaim_candidate(region_idx),
4361 obj->is_typeArray()
4362 );
4363
4364 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4365 cm->humongous_object_eagerly_reclaimed(r);
4366 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4367 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4368 region_idx,
4369 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4370 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4371 _humongous_objects_reclaimed++;
4372 do {
4373 HeapRegion* next = g1h->next_region_in_humongous(r);
4374 _freed_bytes += r->used();
4375 r->set_containing_set(NULL);
4376 _humongous_regions_reclaimed++;
4377 g1h->free_humongous_region(r, _free_region_list);
4378 r = next;
4379 } while (r != NULL);
4380
4381 return false;
4382 }
4383
4384 uint humongous_objects_reclaimed() {
4385 return _humongous_objects_reclaimed;
4386 }
4387
4388 uint humongous_regions_reclaimed() {
4389 return _humongous_regions_reclaimed;
4390 }
4391
4392 size_t bytes_freed() const {
4393 return _freed_bytes;
4394 }
4395 };
4396
4397 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4398 assert_at_safepoint_on_vm_thread();
4399
4400 if (!G1EagerReclaimHumongousObjects ||
4401 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4402 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4403 return;
4404 }
4405
4406 double start_time = os::elapsedTime();
4407
4408 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4409
4410 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4411 heap_region_iterate(&cl);
4412
4413 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4414
4415 G1HRPrinter* hrp = hr_printer();
4416 if (hrp->is_active()) {
4417 FreeRegionListIterator iter(&local_cleanup_list);
4418 while (iter.more_available()) {
4419 HeapRegion* hr = iter.get_next();
4420 hrp->cleanup(hr);
4421 }
4422 }
4423
4424 prepend_to_freelist(&local_cleanup_list);
4425 decrement_summary_bytes(cl.bytes_freed());
4426
4427 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4428 cl.humongous_objects_reclaimed());
4429 }
4430
4431 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4432 public:
4433 virtual bool do_heap_region(HeapRegion* r) {
4434 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4435 G1CollectedHeap::heap()->clear_in_cset(r);
4436 r->set_young_index_in_cset(-1);
4437 return false;
4438 }
4439 };
4440
4441 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4442 G1AbandonCollectionSetClosure cl;
4443 collection_set->iterate(&cl);
4444
4445 collection_set->clear();
4446 collection_set->stop_incremental_building();
4447 }
4448
4449 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4450 return _allocator->is_retained_old_region(hr);
4451 }
4452
4453 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4454 _eden.add(hr);
4455 _policy->set_region_eden(hr);
4456 }
4457
4458 #ifdef ASSERT
4459
4460 class NoYoungRegionsClosure: public HeapRegionClosure {
4461 private:
4462 bool _success;
4463 public:
4464 NoYoungRegionsClosure() : _success(true) { }
4465 bool do_heap_region(HeapRegion* r) {
4466 if (r->is_young()) {
4467 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4468 p2i(r->bottom()), p2i(r->end()));
4469 _success = false;
4470 }
4471 return false;
4472 }
4473 bool success() { return _success; }
4474 };
4475
4476 bool G1CollectedHeap::check_young_list_empty() {
4477 bool ret = (young_regions_count() == 0);
4478
4479 NoYoungRegionsClosure closure;
4480 heap_region_iterate(&closure);
4481 ret = ret && closure.success();
4482
4483 return ret;
4484 }
4485
4486 #endif // ASSERT
4487
4488 class TearDownRegionSetsClosure : public HeapRegionClosure {
4489 HeapRegionSet *_old_set;
4490
4491 public:
4492 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4493
4494 bool do_heap_region(HeapRegion* r) {
4495 if (r->is_old()) {
4496 _old_set->remove(r);
4497 } else if(r->is_young()) {
4498 r->uninstall_surv_rate_group();
4499 } else {
4500 // We ignore free regions, we'll empty the free list afterwards.
4501 // We ignore humongous and archive regions, we're not tearing down these
4502 // sets.
4503 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4504 "it cannot be another type");
4505 }
4506 return false;
4507 }
4508
4509 ~TearDownRegionSetsClosure() {
4510 assert(_old_set->is_empty(), "post-condition");
4511 }
4512 };
4513
4514 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4515 assert_at_safepoint_on_vm_thread();
4516
4517 if (!free_list_only) {
4518 TearDownRegionSetsClosure cl(&_old_set);
4519 heap_region_iterate(&cl);
4520
4521 // Note that emptying the _young_list is postponed and instead done as
4522 // the first step when rebuilding the regions sets again. The reason for
4523 // this is that during a full GC string deduplication needs to know if
4524 // a collected region was young or old when the full GC was initiated.
4525 }
4526 _hrm->remove_all_free_regions();
4527 }
4528
4529 void G1CollectedHeap::increase_used(size_t bytes) {
4530 _summary_bytes_used += bytes;
4531 }
4532
4533 void G1CollectedHeap::decrease_used(size_t bytes) {
4534 assert(_summary_bytes_used >= bytes,
4535 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4536 _summary_bytes_used, bytes);
4537 _summary_bytes_used -= bytes;
4538 }
4539
4540 void G1CollectedHeap::set_used(size_t bytes) {
4541 _summary_bytes_used = bytes;
4542 }
4543
4544 class RebuildRegionSetsClosure : public HeapRegionClosure {
4545 private:
4546 bool _free_list_only;
4547
4548 HeapRegionSet* _old_set;
4549 HeapRegionManager* _hrm;
4550
4551 size_t _total_used;
4552
4553 public:
4554 RebuildRegionSetsClosure(bool free_list_only,
4555 HeapRegionSet* old_set,
4556 HeapRegionManager* hrm) :
4557 _free_list_only(free_list_only),
4558 _old_set(old_set), _hrm(hrm), _total_used(0) {
4559 assert(_hrm->num_free_regions() == 0, "pre-condition");
4560 if (!free_list_only) {
4561 assert(_old_set->is_empty(), "pre-condition");
4562 }
4563 }
4564
4565 bool do_heap_region(HeapRegion* r) {
4566 if (r->is_empty()) {
4567 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4568 // Add free regions to the free list
4569 r->set_free();
4570 _hrm->insert_into_free_list(r);
4571 } else if (!_free_list_only) {
4572 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4573
4574 if (r->is_archive() || r->is_humongous()) {
4575 // We ignore archive and humongous regions. We left these sets unchanged.
4576 } else {
4577 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4578 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4579 r->move_to_old();
4580 _old_set->add(r);
4581 }
4582 _total_used += r->used();
4583 }
4584
4585 return false;
4586 }
4587
4588 size_t total_used() {
4589 return _total_used;
4590 }
4591 };
4592
4593 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4594 assert_at_safepoint_on_vm_thread();
4595
4596 if (!free_list_only) {
4597 _eden.clear();
4598 _survivor.clear();
4599 }
4600
4601 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4602 heap_region_iterate(&cl);
4603
4604 if (!free_list_only) {
4605 set_used(cl.total_used());
4606 if (_archive_allocator != NULL) {
4607 _archive_allocator->clear_used();
4608 }
4609 }
4610 assert(used() == recalculate_used(),
4611 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4612 used(), recalculate_used());
4613 }
4614
4615 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4616 HeapRegion* hr = heap_region_containing(p);
4617 return hr->is_in(p);
4618 }
4619
4620 // Methods for the mutator alloc region
4621
4622 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4623 bool force) {
4624 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4625 bool should_allocate = policy()->should_allocate_mutator_region();
4626 if (force || should_allocate) {
4627 HeapRegion* new_alloc_region = new_region(word_size,
4628 HeapRegionType::Eden,
4629 false /* do_expand */);
4630 if (new_alloc_region != NULL) {
4631 set_region_short_lived_locked(new_alloc_region);
4632 _hr_printer.alloc(new_alloc_region, !should_allocate);
4633 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4634 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4635 return new_alloc_region;
4636 }
4637 }
4638 return NULL;
4639 }
4640
4641 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4642 size_t allocated_bytes) {
4643 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4644 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4645
4646 collection_set()->add_eden_region(alloc_region);
4647 increase_used(allocated_bytes);
4648 _hr_printer.retire(alloc_region);
4649 // We update the eden sizes here, when the region is retired,
4650 // instead of when it's allocated, since this is the point that its
4651 // used space has been recorded in _summary_bytes_used.
4652 g1mm()->update_eden_size();
4653 }
4654
4655 // Methods for the GC alloc regions
4656
4657 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4658 if (dest.is_old()) {
4659 return true;
4660 } else {
4661 return survivor_regions_count() < policy()->max_survivor_regions();
4662 }
4663 }
4664
4665 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4666 assert(FreeList_lock->owned_by_self(), "pre-condition");
4667
4668 if (!has_more_regions(dest)) {
4669 return NULL;
4670 }
4671
4672 HeapRegionType type;
4673 if (dest.is_young()) {
4674 type = HeapRegionType::Survivor;
4675 } else {
4676 type = HeapRegionType::Old;
4677 }
4678
4679 HeapRegion* new_alloc_region = new_region(word_size,
4680 type,
4681 true /* do_expand */);
4682
4683 if (new_alloc_region != NULL) {
4684 if (type.is_survivor()) {
4685 new_alloc_region->set_survivor();
4686 _survivor.add(new_alloc_region);
4687 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4688 } else {
4689 new_alloc_region->set_old();
4690 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4691 }
4692 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4693 _hr_printer.alloc(new_alloc_region);
4694 return new_alloc_region;
4695 }
4696 return NULL;
4697 }
4698
4699 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4700 size_t allocated_bytes,
4701 InCSetState dest) {
4702 policy()->record_bytes_copied_during_gc(allocated_bytes);
4703 if (dest.is_old()) {
4704 old_set_add(alloc_region);
4705 }
4706
4707 bool const during_im = collector_state()->in_initial_mark_gc();
4708 if (during_im && allocated_bytes > 0) {
4709 _cm->root_regions()->add(alloc_region);
4710 }
4711 _hr_printer.retire(alloc_region);
4712 }
4713
4714 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4715 bool expanded = false;
4716 uint index = _hrm->find_highest_free(&expanded);
4717
4718 if (index != G1_NO_HRM_INDEX) {
4719 if (expanded) {
4720 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4721 HeapRegion::GrainWords * HeapWordSize);
4722 }
4723 _hrm->allocate_free_regions_starting_at(index, 1);
4724 return region_at(index);
4725 }
4726 return NULL;
4727 }
4728
4729 // Optimized nmethod scanning
4730
4731 class RegisterNMethodOopClosure: public OopClosure {
4732 G1CollectedHeap* _g1h;
4733 nmethod* _nm;
4734
4735 template <class T> void do_oop_work(T* p) {
4736 T heap_oop = RawAccess<>::oop_load(p);
4737 if (!CompressedOops::is_null(heap_oop)) {
4738 oop obj = CompressedOops::decode_not_null(heap_oop);
4739 HeapRegion* hr = _g1h->heap_region_containing(obj);
4740 assert(!hr->is_continues_humongous(),
4741 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4742 " starting at " HR_FORMAT,
4743 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4744
4745 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4746 hr->add_strong_code_root_locked(_nm);
4747 }
4748 }
4749
4750 public:
4751 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4752 _g1h(g1h), _nm(nm) {}
4753
4754 void do_oop(oop* p) { do_oop_work(p); }
4755 void do_oop(narrowOop* p) { do_oop_work(p); }
4756 };
4757
4758 class UnregisterNMethodOopClosure: public OopClosure {
4759 G1CollectedHeap* _g1h;
4760 nmethod* _nm;
4761
4762 template <class T> void do_oop_work(T* p) {
4763 T heap_oop = RawAccess<>::oop_load(p);
4764 if (!CompressedOops::is_null(heap_oop)) {
4765 oop obj = CompressedOops::decode_not_null(heap_oop);
4766 HeapRegion* hr = _g1h->heap_region_containing(obj);
4767 assert(!hr->is_continues_humongous(),
4768 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4769 " starting at " HR_FORMAT,
4770 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4771
4772 hr->remove_strong_code_root(_nm);
4773 }
4774 }
4775
4776 public:
4777 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4778 _g1h(g1h), _nm(nm) {}
4779
4780 void do_oop(oop* p) { do_oop_work(p); }
4781 void do_oop(narrowOop* p) { do_oop_work(p); }
4782 };
4783
4784 // Returns true if the reference points to an object that
4785 // can move in an incremental collection.
4786 bool G1CollectedHeap::is_scavengable(oop obj) {
4787 HeapRegion* hr = heap_region_containing(obj);
4788 return !hr->is_pinned();
4789 }
4790
4791 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4792 guarantee(nm != NULL, "sanity");
4793 RegisterNMethodOopClosure reg_cl(this, nm);
4794 nm->oops_do(®_cl);
4795 }
4796
4797 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4798 guarantee(nm != NULL, "sanity");
4799 UnregisterNMethodOopClosure reg_cl(this, nm);
4800 nm->oops_do(®_cl, true);
4801 }
4802
4803 void G1CollectedHeap::purge_code_root_memory() {
4804 double purge_start = os::elapsedTime();
4805 G1CodeRootSet::purge();
4806 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4807 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4808 }
4809
4810 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4811 G1CollectedHeap* _g1h;
4812
4813 public:
4814 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4815 _g1h(g1h) {}
4816
4817 void do_code_blob(CodeBlob* cb) {
4818 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4819 if (nm == NULL) {
4820 return;
4821 }
4822
4823 if (ScavengeRootsInCode) {
4824 _g1h->register_nmethod(nm);
4825 }
4826 }
4827 };
4828
4829 void G1CollectedHeap::rebuild_strong_code_roots() {
4830 RebuildStrongCodeRootClosure blob_cl(this);
4831 CodeCache::blobs_do(&blob_cl);
4832 }
4833
4834 void G1CollectedHeap::initialize_serviceability() {
4835 _g1mm->initialize_serviceability();
4836 }
4837
4838 MemoryUsage G1CollectedHeap::memory_usage() {
4839 return _g1mm->memory_usage();
4840 }
4841
4842 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4843 return _g1mm->memory_managers();
4844 }
4845
4846 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4847 return _g1mm->memory_pools();
4848 }