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/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1MemoryPool.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1SATBMarkQueueSet.hpp"
56 #include "gc/g1/g1StringDedup.hpp"
57 #include "gc/g1/g1ThreadLocalData.hpp"
58 #include "gc/g1/g1YCTypes.hpp"
59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
60 #include "gc/g1/g1VMOperations.hpp"
61 #include "gc/g1/heapRegion.inline.hpp"
62 #include "gc/g1/heapRegionRemSet.hpp"
63 #include "gc/g1/heapRegionSet.inline.hpp"
64 #include "gc/shared/gcBehaviours.hpp"
65 #include "gc/shared/gcHeapSummary.hpp"
66 #include "gc/shared/gcId.hpp"
67 #include "gc/shared/gcLocker.hpp"
68 #include "gc/shared/gcTimer.hpp"
69 #include "gc/shared/gcTrace.hpp"
70 #include "gc/shared/gcTraceTime.inline.hpp"
71 #include "gc/shared/generationSpec.hpp"
72 #include "gc/shared/isGCActiveMark.hpp"
73 #include "gc/shared/oopStorageParState.hpp"
74 #include "gc/shared/parallelCleaning.hpp"
75 #include "gc/shared/preservedMarks.inline.hpp"
76 #include "gc/shared/suspendibleThreadSet.hpp"
77 #include "gc/shared/referenceProcessor.inline.hpp"
78 #include "gc/shared/taskqueue.inline.hpp"
79 #include "gc/shared/weakProcessor.inline.hpp"
80 #include "gc/shared/workerPolicy.hpp"
81 #include "logging/log.hpp"
82 #include "memory/allocation.hpp"
83 #include "memory/iterator.hpp"
84 #include "memory/resourceArea.hpp"
85 #include "oops/access.inline.hpp"
86 #include "oops/compressedOops.inline.hpp"
87 #include "oops/oop.inline.hpp"
88 #include "runtime/atomic.hpp"
89 #include "runtime/flags/flagSetting.hpp"
90 #include "runtime/handles.inline.hpp"
91 #include "runtime/init.hpp"
92 #include "runtime/orderAccess.hpp"
93 #include "runtime/threadSMR.hpp"
94 #include "runtime/vmThread.hpp"
95 #include "utilities/align.hpp"
96 #include "utilities/globalDefinitions.hpp"
97 #include "utilities/stack.inline.hpp"
98
99 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
100
101 // INVARIANTS/NOTES
102 //
103 // All allocation activity covered by the G1CollectedHeap interface is
104 // serialized by acquiring the HeapLock. This happens in mem_allocate
105 // and allocate_new_tlab, which are the "entry" points to the
106 // allocation code from the rest of the JVM. (Note that this does not
107 // apply to TLAB allocation, which is not part of this interface: it
108 // is done by clients of this interface.)
109
110 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
111 private:
112 size_t _num_dirtied;
113 G1CollectedHeap* _g1h;
114 G1CardTable* _g1_ct;
115
116 HeapRegion* region_for_card(jbyte* card_ptr) const {
117 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
118 }
119
120 bool will_become_free(HeapRegion* hr) const {
121 // A region will be freed by free_collection_set if the region is in the
122 // collection set and has not had an evacuation failure.
123 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
124 }
125
126 public:
127 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
128 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
129
130 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
131 HeapRegion* hr = region_for_card(card_ptr);
132
133 // Should only dirty cards in regions that won't be freed.
134 if (!will_become_free(hr)) {
135 *card_ptr = G1CardTable::dirty_card_val();
136 _num_dirtied++;
137 }
138
139 return true;
140 }
141
142 size_t num_dirtied() const { return _num_dirtied; }
143 };
144
145
146 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
147 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
148 }
149
150 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
151 // The from card cache is not the memory that is actually committed. So we cannot
152 // take advantage of the zero_filled parameter.
153 reset_from_card_cache(start_idx, num_regions);
154 }
155
156
157 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
158 MemRegion mr) {
159 return new HeapRegion(hrs_index, bot(), mr);
160 }
161
162 // Private methods.
163
164 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
165 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
166 "the only time we use this to allocate a humongous region is "
167 "when we are allocating a single humongous region");
168
169 HeapRegion* res = _hrm->allocate_free_region(type);
170
171 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
172 // Currently, only attempts to allocate GC alloc regions set
173 // do_expand to true. So, we should only reach here during a
174 // safepoint. If this assumption changes we might have to
175 // reconsider the use of _expand_heap_after_alloc_failure.
176 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
177
178 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
179 word_size * HeapWordSize);
180
181 if (expand(word_size * HeapWordSize)) {
182 // Given that expand() succeeded in expanding the heap, and we
183 // always expand the heap by an amount aligned to the heap
184 // region size, the free list should in theory not be empty.
185 // In either case allocate_free_region() will check for NULL.
186 res = _hrm->allocate_free_region(type);
187 } else {
188 _expand_heap_after_alloc_failure = false;
189 }
190 }
191 return res;
192 }
193
194 HeapWord*
195 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
196 uint num_regions,
197 size_t word_size) {
198 assert(first != G1_NO_HRM_INDEX, "pre-condition");
199 assert(is_humongous(word_size), "word_size should be humongous");
200 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
201
202 // Index of last region in the series.
203 uint last = first + num_regions - 1;
204
205 // We need to initialize the region(s) we just discovered. This is
206 // a bit tricky given that it can happen concurrently with
207 // refinement threads refining cards on these regions and
208 // potentially wanting to refine the BOT as they are scanning
209 // those cards (this can happen shortly after a cleanup; see CR
210 // 6991377). So we have to set up the region(s) carefully and in
211 // a specific order.
212
213 // The word size sum of all the regions we will allocate.
214 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
215 assert(word_size <= word_size_sum, "sanity");
216
217 // This will be the "starts humongous" region.
218 HeapRegion* first_hr = region_at(first);
219 // The header of the new object will be placed at the bottom of
220 // the first region.
221 HeapWord* new_obj = first_hr->bottom();
222 // This will be the new top of the new object.
223 HeapWord* obj_top = new_obj + word_size;
224
225 // First, we need to zero the header of the space that we will be
226 // allocating. When we update top further down, some refinement
227 // threads might try to scan the region. By zeroing the header we
228 // ensure that any thread that will try to scan the region will
229 // come across the zero klass word and bail out.
230 //
231 // NOTE: It would not have been correct to have used
232 // CollectedHeap::fill_with_object() and make the space look like
233 // an int array. The thread that is doing the allocation will
234 // later update the object header to a potentially different array
235 // type and, for a very short period of time, the klass and length
236 // fields will be inconsistent. This could cause a refinement
237 // thread to calculate the object size incorrectly.
238 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
239
240 // Next, pad out the unused tail of the last region with filler
241 // objects, for improved usage accounting.
242 // How many words we use for filler objects.
243 size_t word_fill_size = word_size_sum - word_size;
244
245 // How many words memory we "waste" which cannot hold a filler object.
246 size_t words_not_fillable = 0;
247
248 if (word_fill_size >= min_fill_size()) {
249 fill_with_objects(obj_top, word_fill_size);
250 } else if (word_fill_size > 0) {
251 // We have space to fill, but we cannot fit an object there.
252 words_not_fillable = word_fill_size;
253 word_fill_size = 0;
254 }
255
256 // We will set up the first region as "starts humongous". This
257 // will also update the BOT covering all the regions to reflect
258 // that there is a single object that starts at the bottom of the
259 // first region.
260 first_hr->set_starts_humongous(obj_top, word_fill_size);
261 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
262 // Then, if there are any, we will set up the "continues
263 // humongous" regions.
264 HeapRegion* hr = NULL;
265 for (uint i = first + 1; i <= last; ++i) {
266 hr = region_at(i);
267 hr->set_continues_humongous(first_hr);
268 _g1_policy->remset_tracker()->update_at_allocate(hr);
269 }
270
271 // Up to this point no concurrent thread would have been able to
272 // do any scanning on any region in this series. All the top
273 // fields still point to bottom, so the intersection between
274 // [bottom,top] and [card_start,card_end] will be empty. Before we
275 // update the top fields, we'll do a storestore to make sure that
276 // no thread sees the update to top before the zeroing of the
277 // object header and the BOT initialization.
278 OrderAccess::storestore();
279
280 // Now, we will update the top fields of the "continues humongous"
281 // regions except the last one.
282 for (uint i = first; i < last; ++i) {
283 hr = region_at(i);
284 hr->set_top(hr->end());
285 }
286
287 hr = region_at(last);
288 // If we cannot fit a filler object, we must set top to the end
289 // of the humongous object, otherwise we cannot iterate the heap
290 // and the BOT will not be complete.
291 hr->set_top(hr->end() - words_not_fillable);
292
293 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
294 "obj_top should be in last region");
295
296 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
297
298 assert(words_not_fillable == 0 ||
299 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
300 "Miscalculation in humongous allocation");
301
302 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
303
304 for (uint i = first; i <= last; ++i) {
305 hr = region_at(i);
306 _humongous_set.add(hr);
307 _hr_printer.alloc(hr);
308 }
309
310 return new_obj;
311 }
312
313 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
314 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
315 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
316 }
317
318 // If could fit into free regions w/o expansion, try.
319 // Otherwise, if can expand, do so.
320 // Otherwise, if using ex regions might help, try with ex given back.
321 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
322 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
323
324 _verifier->verify_region_sets_optional();
325
326 uint first = G1_NO_HRM_INDEX;
327 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
328
329 if (obj_regions == 1) {
330 // Only one region to allocate, try to use a fast path by directly allocating
331 // from the free lists. Do not try to expand here, we will potentially do that
332 // later.
333 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
334 if (hr != NULL) {
335 first = hr->hrm_index();
336 }
337 } else {
338 // Policy: Try only empty regions (i.e. already committed first). Maybe we
339 // are lucky enough to find some.
340 first = _hrm->find_contiguous_only_empty(obj_regions);
341 if (first != G1_NO_HRM_INDEX) {
342 _hrm->allocate_free_regions_starting_at(first, obj_regions);
343 }
344 }
345
346 if (first == G1_NO_HRM_INDEX) {
347 // Policy: We could not find enough regions for the humongous object in the
348 // free list. Look through the heap to find a mix of free and uncommitted regions.
349 // If so, try expansion.
350 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
351 if (first != G1_NO_HRM_INDEX) {
352 // We found something. Make sure these regions are committed, i.e. expand
353 // the heap. Alternatively we could do a defragmentation GC.
354 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
355 word_size * HeapWordSize);
356
357 _hrm->expand_at(first, obj_regions, workers());
358 g1_policy()->record_new_heap_size(num_regions());
359
360 #ifdef ASSERT
361 for (uint i = first; i < first + obj_regions; ++i) {
362 HeapRegion* hr = region_at(i);
363 assert(hr->is_free(), "sanity");
364 assert(hr->is_empty(), "sanity");
365 assert(is_on_master_free_list(hr), "sanity");
366 }
367 #endif
368 _hrm->allocate_free_regions_starting_at(first, obj_regions);
369 } else {
370 // Policy: Potentially trigger a defragmentation GC.
371 }
372 }
373
374 HeapWord* result = NULL;
375 if (first != G1_NO_HRM_INDEX) {
376 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
377 assert(result != NULL, "it should always return a valid result");
378
379 // A successful humongous object allocation changes the used space
380 // information of the old generation so we need to recalculate the
381 // sizes and update the jstat counters here.
382 g1mm()->update_sizes();
383 }
384
385 _verifier->verify_region_sets_optional();
386
387 return result;
388 }
389
390 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
391 size_t requested_size,
392 size_t* actual_size) {
393 assert_heap_not_locked_and_not_at_safepoint();
394 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
395
396 return attempt_allocation(min_size, requested_size, actual_size);
397 }
398
399 HeapWord*
400 G1CollectedHeap::mem_allocate(size_t word_size,
401 bool* gc_overhead_limit_was_exceeded) {
402 assert_heap_not_locked_and_not_at_safepoint();
403
404 if (is_humongous(word_size)) {
405 return attempt_allocation_humongous(word_size);
406 }
407 size_t dummy = 0;
408 return attempt_allocation(word_size, word_size, &dummy);
409 }
410
411 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
412 ResourceMark rm; // For retrieving the thread names in log messages.
413
414 // Make sure you read the note in attempt_allocation_humongous().
415
416 assert_heap_not_locked_and_not_at_safepoint();
417 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
418 "be called for humongous allocation requests");
419
420 // We should only get here after the first-level allocation attempt
421 // (attempt_allocation()) failed to allocate.
422
423 // We will loop until a) we manage to successfully perform the
424 // allocation or b) we successfully schedule a collection which
425 // fails to perform the allocation. b) is the only case when we'll
426 // return NULL.
427 HeapWord* result = NULL;
428 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
429 bool should_try_gc;
430 uint gc_count_before;
431
432 {
433 MutexLockerEx x(Heap_lock);
434 result = _allocator->attempt_allocation_locked(word_size);
435 if (result != NULL) {
436 return result;
437 }
438
439 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
440 // This is different to when only GCLocker::needs_gc() is set: try to avoid
441 // waiting because the GCLocker is active to not wait too long.
442 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
443 // No need for an ergo message here, can_expand_young_list() does this when
444 // it returns true.
445 result = _allocator->attempt_allocation_force(word_size);
446 if (result != NULL) {
447 return result;
448 }
449 }
450 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
451 // the GCLocker initiated GC has been performed and then retry. This includes
452 // the case when the GC Locker is not active but has not been performed.
453 should_try_gc = !GCLocker::needs_gc();
454 // Read the GC count while still holding the Heap_lock.
455 gc_count_before = total_collections();
456 }
457
458 if (should_try_gc) {
459 bool succeeded;
460 result = do_collection_pause(word_size, gc_count_before, &succeeded,
461 GCCause::_g1_inc_collection_pause);
462 if (result != NULL) {
463 assert(succeeded, "only way to get back a non-NULL result");
464 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
465 Thread::current()->name(), p2i(result));
466 return result;
467 }
468
469 if (succeeded) {
470 // We successfully scheduled a collection which failed to allocate. No
471 // point in trying to allocate further. We'll just return NULL.
472 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
473 SIZE_FORMAT " words", Thread::current()->name(), word_size);
474 return NULL;
475 }
476 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
477 Thread::current()->name(), word_size);
478 } else {
479 // Failed to schedule a collection.
480 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
481 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
482 SIZE_FORMAT " words", Thread::current()->name(), word_size);
483 return NULL;
484 }
485 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
486 // The GCLocker is either active or the GCLocker initiated
487 // GC has not yet been performed. Stall until it is and
488 // then retry the allocation.
489 GCLocker::stall_until_clear();
490 gclocker_retry_count += 1;
491 }
492
493 // We can reach here if we were unsuccessful in scheduling a
494 // collection (because another thread beat us to it) or if we were
495 // stalled due to the GC locker. In either can we should retry the
496 // allocation attempt in case another thread successfully
497 // performed a collection and reclaimed enough space. We do the
498 // first attempt (without holding the Heap_lock) here and the
499 // follow-on attempt will be at the start of the next loop
500 // iteration (after taking the Heap_lock).
501 size_t dummy = 0;
502 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
503 if (result != NULL) {
504 return result;
505 }
506
507 // Give a warning if we seem to be looping forever.
508 if ((QueuedAllocationWarningCount > 0) &&
509 (try_count % QueuedAllocationWarningCount == 0)) {
510 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
511 Thread::current()->name(), try_count, word_size);
512 }
513 }
514
515 ShouldNotReachHere();
516 return NULL;
517 }
518
519 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
520 assert_at_safepoint_on_vm_thread();
521 if (_archive_allocator == NULL) {
522 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
523 }
524 }
525
526 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
527 // Allocations in archive regions cannot be of a size that would be considered
528 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
529 // may be different at archive-restore time.
530 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
531 }
532
533 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
534 assert_at_safepoint_on_vm_thread();
535 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
536 if (is_archive_alloc_too_large(word_size)) {
537 return NULL;
538 }
539 return _archive_allocator->archive_mem_allocate(word_size);
540 }
541
542 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
543 size_t end_alignment_in_bytes) {
544 assert_at_safepoint_on_vm_thread();
545 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
546
547 // Call complete_archive to do the real work, filling in the MemRegion
548 // array with the archive regions.
549 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
550 delete _archive_allocator;
551 _archive_allocator = NULL;
552 }
553
554 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
555 assert(ranges != NULL, "MemRegion array NULL");
556 assert(count != 0, "No MemRegions provided");
557 MemRegion reserved = _hrm->reserved();
558 for (size_t i = 0; i < count; i++) {
559 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
560 return false;
561 }
562 }
563 return true;
564 }
565
566 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
567 size_t count,
568 bool open) {
569 assert(!is_init_completed(), "Expect to be called at JVM init time");
570 assert(ranges != NULL, "MemRegion array NULL");
571 assert(count != 0, "No MemRegions provided");
572 MutexLockerEx x(Heap_lock);
573
574 MemRegion reserved = _hrm->reserved();
575 HeapWord* prev_last_addr = NULL;
576 HeapRegion* prev_last_region = NULL;
577
578 // Temporarily disable pretouching of heap pages. This interface is used
579 // when mmap'ing archived heap data in, so pre-touching is wasted.
580 FlagSetting fs(AlwaysPreTouch, false);
581
582 // Enable archive object checking used by G1MarkSweep. We have to let it know
583 // about each archive range, so that objects in those ranges aren't marked.
584 G1ArchiveAllocator::enable_archive_object_check();
585
586 // For each specified MemRegion range, allocate the corresponding G1
587 // regions and mark them as archive regions. We expect the ranges
588 // in ascending starting address order, without overlap.
589 for (size_t i = 0; i < count; i++) {
590 MemRegion curr_range = ranges[i];
591 HeapWord* start_address = curr_range.start();
592 size_t word_size = curr_range.word_size();
593 HeapWord* last_address = curr_range.last();
594 size_t commits = 0;
595
596 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
597 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
598 p2i(start_address), p2i(last_address));
599 guarantee(start_address > prev_last_addr,
600 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
601 p2i(start_address), p2i(prev_last_addr));
602 prev_last_addr = last_address;
603
604 // Check for ranges that start in the same G1 region in which the previous
605 // range ended, and adjust the start address so we don't try to allocate
606 // the same region again. If the current range is entirely within that
607 // region, skip it, just adjusting the recorded top.
608 HeapRegion* start_region = _hrm->addr_to_region(start_address);
609 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
610 start_address = start_region->end();
611 if (start_address > last_address) {
612 increase_used(word_size * HeapWordSize);
613 start_region->set_top(last_address + 1);
614 continue;
615 }
616 start_region->set_top(start_address);
617 curr_range = MemRegion(start_address, last_address + 1);
618 start_region = _hrm->addr_to_region(start_address);
619 }
620
621 // Perform the actual region allocation, exiting if it fails.
622 // Then note how much new space we have allocated.
623 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
624 return false;
625 }
626 increase_used(word_size * HeapWordSize);
627 if (commits != 0) {
628 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
629 HeapRegion::GrainWords * HeapWordSize * commits);
630
631 }
632
633 // Mark each G1 region touched by the range as archive, add it to
634 // the old set, and set top.
635 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
636 HeapRegion* last_region = _hrm->addr_to_region(last_address);
637 prev_last_region = last_region;
638
639 while (curr_region != NULL) {
640 assert(curr_region->is_empty() && !curr_region->is_pinned(),
641 "Region already in use (index %u)", curr_region->hrm_index());
642 if (open) {
643 curr_region->set_open_archive();
644 } else {
645 curr_region->set_closed_archive();
646 }
647 _hr_printer.alloc(curr_region);
648 _archive_set.add(curr_region);
649 HeapWord* top;
650 HeapRegion* next_region;
651 if (curr_region != last_region) {
652 top = curr_region->end();
653 next_region = _hrm->next_region_in_heap(curr_region);
654 } else {
655 top = last_address + 1;
656 next_region = NULL;
657 }
658 curr_region->set_top(top);
659 curr_region->set_first_dead(top);
660 curr_region->set_end_of_live(top);
661 curr_region = next_region;
662 }
663
664 // Notify mark-sweep of the archive
665 G1ArchiveAllocator::set_range_archive(curr_range, open);
666 }
667 return true;
668 }
669
670 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
671 assert(!is_init_completed(), "Expect to be called at JVM init time");
672 assert(ranges != NULL, "MemRegion array NULL");
673 assert(count != 0, "No MemRegions provided");
674 MemRegion reserved = _hrm->reserved();
675 HeapWord *prev_last_addr = NULL;
676 HeapRegion* prev_last_region = NULL;
677
678 // For each MemRegion, create filler objects, if needed, in the G1 regions
679 // that contain the address range. The address range actually within the
680 // MemRegion will not be modified. That is assumed to have been initialized
681 // elsewhere, probably via an mmap of archived heap data.
682 MutexLockerEx x(Heap_lock);
683 for (size_t i = 0; i < count; i++) {
684 HeapWord* start_address = ranges[i].start();
685 HeapWord* last_address = ranges[i].last();
686
687 assert(reserved.contains(start_address) && reserved.contains(last_address),
688 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
689 p2i(start_address), p2i(last_address));
690 assert(start_address > prev_last_addr,
691 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
692 p2i(start_address), p2i(prev_last_addr));
693
694 HeapRegion* start_region = _hrm->addr_to_region(start_address);
695 HeapRegion* last_region = _hrm->addr_to_region(last_address);
696 HeapWord* bottom_address = start_region->bottom();
697
698 // Check for a range beginning in the same region in which the
699 // previous one ended.
700 if (start_region == prev_last_region) {
701 bottom_address = prev_last_addr + 1;
702 }
703
704 // Verify that the regions were all marked as archive regions by
705 // alloc_archive_regions.
706 HeapRegion* curr_region = start_region;
707 while (curr_region != NULL) {
708 guarantee(curr_region->is_archive(),
709 "Expected archive region at index %u", curr_region->hrm_index());
710 if (curr_region != last_region) {
711 curr_region = _hrm->next_region_in_heap(curr_region);
712 } else {
713 curr_region = NULL;
714 }
715 }
716
717 prev_last_addr = last_address;
718 prev_last_region = last_region;
719
720 // Fill the memory below the allocated range with dummy object(s),
721 // if the region bottom does not match the range start, or if the previous
722 // range ended within the same G1 region, and there is a gap.
723 if (start_address != bottom_address) {
724 size_t fill_size = pointer_delta(start_address, bottom_address);
725 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
726 increase_used(fill_size * HeapWordSize);
727 }
728 }
729 }
730
731 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
732 size_t desired_word_size,
733 size_t* actual_word_size) {
734 assert_heap_not_locked_and_not_at_safepoint();
735 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
736 "be called for humongous allocation requests");
737
738 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
739
740 if (result == NULL) {
741 *actual_word_size = desired_word_size;
742 result = attempt_allocation_slow(desired_word_size);
743 }
744
745 assert_heap_not_locked();
746 if (result != NULL) {
747 assert(*actual_word_size != 0, "Actual size must have been set here");
748 dirty_young_block(result, *actual_word_size);
749 } else {
750 *actual_word_size = 0;
751 }
752
753 return result;
754 }
755
756 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
757 assert(!is_init_completed(), "Expect to be called at JVM init time");
758 assert(ranges != NULL, "MemRegion array NULL");
759 assert(count != 0, "No MemRegions provided");
760 MemRegion reserved = _hrm->reserved();
761 HeapWord* prev_last_addr = NULL;
762 HeapRegion* prev_last_region = NULL;
763 size_t size_used = 0;
764 size_t uncommitted_regions = 0;
765
766 // For each Memregion, free the G1 regions that constitute it, and
767 // notify mark-sweep that the range is no longer to be considered 'archive.'
768 MutexLockerEx x(Heap_lock);
769 for (size_t i = 0; i < count; i++) {
770 HeapWord* start_address = ranges[i].start();
771 HeapWord* last_address = ranges[i].last();
772
773 assert(reserved.contains(start_address) && reserved.contains(last_address),
774 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
775 p2i(start_address), p2i(last_address));
776 assert(start_address > prev_last_addr,
777 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
778 p2i(start_address), p2i(prev_last_addr));
779 size_used += ranges[i].byte_size();
780 prev_last_addr = last_address;
781
782 HeapRegion* start_region = _hrm->addr_to_region(start_address);
783 HeapRegion* last_region = _hrm->addr_to_region(last_address);
784
785 // Check for ranges that start in the same G1 region in which the previous
786 // range ended, and adjust the start address so we don't try to free
787 // the same region again. If the current range is entirely within that
788 // region, skip it.
789 if (start_region == prev_last_region) {
790 start_address = start_region->end();
791 if (start_address > last_address) {
792 continue;
793 }
794 start_region = _hrm->addr_to_region(start_address);
795 }
796 prev_last_region = last_region;
797
798 // After verifying that each region was marked as an archive region by
799 // alloc_archive_regions, set it free and empty and uncommit it.
800 HeapRegion* curr_region = start_region;
801 while (curr_region != NULL) {
802 guarantee(curr_region->is_archive(),
803 "Expected archive region at index %u", curr_region->hrm_index());
804 uint curr_index = curr_region->hrm_index();
805 _archive_set.remove(curr_region);
806 curr_region->set_free();
807 curr_region->set_top(curr_region->bottom());
808 if (curr_region != last_region) {
809 curr_region = _hrm->next_region_in_heap(curr_region);
810 } else {
811 curr_region = NULL;
812 }
813 _hrm->shrink_at(curr_index, 1);
814 uncommitted_regions++;
815 }
816
817 // Notify mark-sweep that this is no longer an archive range.
818 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
819 }
820
821 if (uncommitted_regions != 0) {
822 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
823 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
824 }
825 decrease_used(size_used);
826 }
827
828 oop G1CollectedHeap::materialize_archived_object(oop obj) {
829 assert(obj != NULL, "archived obj is NULL");
830 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
831
832 // Loading an archived object makes it strongly reachable. If it is
833 // loaded during concurrent marking, it must be enqueued to the SATB
834 // queue, shading the previously white object gray.
835 G1BarrierSet::enqueue(obj);
836
837 return obj;
838 }
839
840 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
841 ResourceMark rm; // For retrieving the thread names in log messages.
842
843 // The structure of this method has a lot of similarities to
844 // attempt_allocation_slow(). The reason these two were not merged
845 // into a single one is that such a method would require several "if
846 // allocation is not humongous do this, otherwise do that"
847 // conditional paths which would obscure its flow. In fact, an early
848 // version of this code did use a unified method which was harder to
849 // follow and, as a result, it had subtle bugs that were hard to
850 // track down. So keeping these two methods separate allows each to
851 // be more readable. It will be good to keep these two in sync as
852 // much as possible.
853
854 assert_heap_not_locked_and_not_at_safepoint();
855 assert(is_humongous(word_size), "attempt_allocation_humongous() "
856 "should only be called for humongous allocations");
857
858 // Humongous objects can exhaust the heap quickly, so we should check if we
859 // need to start a marking cycle at each humongous object allocation. We do
860 // the check before we do the actual allocation. The reason for doing it
861 // before the allocation is that we avoid having to keep track of the newly
862 // allocated memory while we do a GC.
863 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
864 word_size)) {
865 collect(GCCause::_g1_humongous_allocation);
866 }
867
868 // We will loop until a) we manage to successfully perform the
869 // allocation or b) we successfully schedule a collection which
870 // fails to perform the allocation. b) is the only case when we'll
871 // return NULL.
872 HeapWord* result = NULL;
873 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
874 bool should_try_gc;
875 uint gc_count_before;
876
877
878 {
879 MutexLockerEx x(Heap_lock);
880
881 // Given that humongous objects are not allocated in young
882 // regions, we'll first try to do the allocation without doing a
883 // collection hoping that there's enough space in the heap.
884 result = humongous_obj_allocate(word_size);
885 if (result != NULL) {
886 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
887 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
888 return result;
889 }
890
891 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
892 // the GCLocker initiated GC has been performed and then retry. This includes
893 // the case when the GC Locker is not active but has not been performed.
894 should_try_gc = !GCLocker::needs_gc();
895 // Read the GC count while still holding the Heap_lock.
896 gc_count_before = total_collections();
897 }
898
899 if (should_try_gc) {
900 bool succeeded;
901 result = do_collection_pause(word_size, gc_count_before, &succeeded,
902 GCCause::_g1_humongous_allocation);
903 if (result != NULL) {
904 assert(succeeded, "only way to get back a non-NULL result");
905 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
906 Thread::current()->name(), p2i(result));
907 return result;
908 }
909
910 if (succeeded) {
911 // We successfully scheduled a collection which failed to allocate. No
912 // point in trying to allocate further. We'll just return NULL.
913 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
914 SIZE_FORMAT " words", Thread::current()->name(), word_size);
915 return NULL;
916 }
917 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
918 Thread::current()->name(), word_size);
919 } else {
920 // Failed to schedule a collection.
921 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
922 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
923 SIZE_FORMAT " words", Thread::current()->name(), word_size);
924 return NULL;
925 }
926 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
927 // The GCLocker is either active or the GCLocker initiated
928 // GC has not yet been performed. Stall until it is and
929 // then retry the allocation.
930 GCLocker::stall_until_clear();
931 gclocker_retry_count += 1;
932 }
933
934
935 // We can reach here if we were unsuccessful in scheduling a
936 // collection (because another thread beat us to it) or if we were
937 // stalled due to the GC locker. In either can we should retry the
938 // allocation attempt in case another thread successfully
939 // performed a collection and reclaimed enough space.
940 // Humongous object allocation always needs a lock, so we wait for the retry
941 // in the next iteration of the loop, unlike for the regular iteration case.
942 // Give a warning if we seem to be looping forever.
943
944 if ((QueuedAllocationWarningCount > 0) &&
945 (try_count % QueuedAllocationWarningCount == 0)) {
946 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
947 Thread::current()->name(), try_count, word_size);
948 }
949 }
950
951 ShouldNotReachHere();
952 return NULL;
953 }
954
955 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
956 bool expect_null_mutator_alloc_region) {
957 assert_at_safepoint_on_vm_thread();
958 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
959 "the current alloc region was unexpectedly found to be non-NULL");
960
961 if (!is_humongous(word_size)) {
962 return _allocator->attempt_allocation_locked(word_size);
963 } else {
964 HeapWord* result = humongous_obj_allocate(word_size);
965 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
966 collector_state()->set_initiate_conc_mark_if_possible(true);
967 }
968 return result;
969 }
970
971 ShouldNotReachHere();
972 }
973
974 class PostCompactionPrinterClosure: public HeapRegionClosure {
975 private:
976 G1HRPrinter* _hr_printer;
977 public:
978 bool do_heap_region(HeapRegion* hr) {
979 assert(!hr->is_young(), "not expecting to find young regions");
980 _hr_printer->post_compaction(hr);
981 return false;
982 }
983
984 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
985 : _hr_printer(hr_printer) { }
986 };
987
988 void G1CollectedHeap::print_hrm_post_compaction() {
989 if (_hr_printer.is_active()) {
990 PostCompactionPrinterClosure cl(hr_printer());
991 heap_region_iterate(&cl);
992 }
993 }
994
995 void G1CollectedHeap::abort_concurrent_cycle() {
996 // If we start the compaction before the CM threads finish
997 // scanning the root regions we might trip them over as we'll
998 // be moving objects / updating references. So let's wait until
999 // they are done. By telling them to abort, they should complete
1000 // early.
1001 _cm->root_regions()->abort();
1002 _cm->root_regions()->wait_until_scan_finished();
1003
1004 // Disable discovery and empty the discovered lists
1005 // for the CM ref processor.
1006 _ref_processor_cm->disable_discovery();
1007 _ref_processor_cm->abandon_partial_discovery();
1008 _ref_processor_cm->verify_no_references_recorded();
1009
1010 // Abandon current iterations of concurrent marking and concurrent
1011 // refinement, if any are in progress.
1012 concurrent_mark()->concurrent_cycle_abort();
1013 }
1014
1015 void G1CollectedHeap::prepare_heap_for_full_collection() {
1016 // Make sure we'll choose a new allocation region afterwards.
1017 _allocator->release_mutator_alloc_region();
1018 _allocator->abandon_gc_alloc_regions();
1019
1020 // We may have added regions to the current incremental collection
1021 // set between the last GC or pause and now. We need to clear the
1022 // incremental collection set and then start rebuilding it afresh
1023 // after this full GC.
1024 abandon_collection_set(collection_set());
1025
1026 tear_down_region_sets(false /* free_list_only */);
1027
1028 hrm()->prepare_for_full_collection_start();
1029 }
1030
1031 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1032 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1033 assert(used() == recalculate_used(), "Should be equal");
1034 _verifier->verify_region_sets_optional();
1035 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1036 _verifier->check_bitmaps("Full GC Start");
1037 }
1038
1039 void G1CollectedHeap::prepare_heap_for_mutators() {
1040 hrm()->prepare_for_full_collection_end();
1041
1042 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1043 ClassLoaderDataGraph::purge();
1044 MetaspaceUtils::verify_metrics();
1045
1046 // Prepare heap for normal collections.
1047 assert(num_free_regions() == 0, "we should not have added any free regions");
1048 rebuild_region_sets(false /* free_list_only */);
1049 abort_refinement();
1050 resize_heap_if_necessary();
1051
1052 // Rebuild the strong code root lists for each region
1053 rebuild_strong_code_roots();
1054
1055 // Purge code root memory
1056 purge_code_root_memory();
1057
1058 // Start a new incremental collection set for the next pause
1059 start_new_collection_set();
1060
1061 _allocator->init_mutator_alloc_region();
1062
1063 // Post collection state updates.
1064 MetaspaceGC::compute_new_size();
1065 }
1066
1067 void G1CollectedHeap::abort_refinement() {
1068 if (_hot_card_cache->use_cache()) {
1069 _hot_card_cache->reset_hot_cache();
1070 }
1071
1072 // Discard all remembered set updates.
1073 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1074 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1075 }
1076
1077 void G1CollectedHeap::verify_after_full_collection() {
1078 _hrm->verify_optional();
1079 _verifier->verify_region_sets_optional();
1080 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1081 // Clear the previous marking bitmap, if needed for bitmap verification.
1082 // Note we cannot do this when we clear the next marking bitmap in
1083 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1084 // objects marked during a full GC against the previous bitmap.
1085 // But we need to clear it before calling check_bitmaps below since
1086 // the full GC has compacted objects and updated TAMS but not updated
1087 // the prev bitmap.
1088 if (G1VerifyBitmaps) {
1089 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1090 _cm->clear_prev_bitmap(workers());
1091 }
1092 // This call implicitly verifies that the next bitmap is clear after Full GC.
1093 _verifier->check_bitmaps("Full GC End");
1094
1095 // At this point there should be no regions in the
1096 // entire heap tagged as young.
1097 assert(check_young_list_empty(), "young list should be empty at this point");
1098
1099 // Note: since we've just done a full GC, concurrent
1100 // marking is no longer active. Therefore we need not
1101 // re-enable reference discovery for the CM ref processor.
1102 // That will be done at the start of the next marking cycle.
1103 // We also know that the STW processor should no longer
1104 // discover any new references.
1105 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1106 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1107 _ref_processor_stw->verify_no_references_recorded();
1108 _ref_processor_cm->verify_no_references_recorded();
1109 }
1110
1111 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1112 // Post collection logging.
1113 // We should do this after we potentially resize the heap so
1114 // that all the COMMIT / UNCOMMIT events are generated before
1115 // the compaction events.
1116 print_hrm_post_compaction();
1117 heap_transition->print();
1118 print_heap_after_gc();
1119 print_heap_regions();
1120 #ifdef TRACESPINNING
1121 ParallelTaskTerminator::print_termination_counts();
1122 #endif
1123 }
1124
1125 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1126 bool clear_all_soft_refs) {
1127 assert_at_safepoint_on_vm_thread();
1128
1129 if (GCLocker::check_active_before_gc()) {
1130 // Full GC was not completed.
1131 return false;
1132 }
1133
1134 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1135 soft_ref_policy()->should_clear_all_soft_refs();
1136
1137 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1138 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1139
1140 collector.prepare_collection();
1141 collector.collect();
1142 collector.complete_collection();
1143
1144 // Full collection was successfully completed.
1145 return true;
1146 }
1147
1148 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1149 // Currently, there is no facility in the do_full_collection(bool) API to notify
1150 // the caller that the collection did not succeed (e.g., because it was locked
1151 // out by the GC locker). So, right now, we'll ignore the return value.
1152 bool dummy = do_full_collection(true, /* explicit_gc */
1153 clear_all_soft_refs);
1154 }
1155
1156 void G1CollectedHeap::resize_heap_if_necessary() {
1157 assert_at_safepoint_on_vm_thread();
1158
1159 // Capacity, free and used after the GC counted as full regions to
1160 // include the waste in the following calculations.
1161 const size_t capacity_after_gc = capacity();
1162 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1163
1164 // This is enforced in arguments.cpp.
1165 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1166 "otherwise the code below doesn't make sense");
1167
1168 // We don't have floating point command-line arguments
1169 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1170 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1171 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1172 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1173
1174 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1175 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1176
1177 // We have to be careful here as these two calculations can overflow
1178 // 32-bit size_t's.
1179 double used_after_gc_d = (double) used_after_gc;
1180 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1181 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1182
1183 // Let's make sure that they are both under the max heap size, which
1184 // by default will make them fit into a size_t.
1185 double desired_capacity_upper_bound = (double) max_heap_size;
1186 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1187 desired_capacity_upper_bound);
1188 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1189 desired_capacity_upper_bound);
1190
1191 // We can now safely turn them into size_t's.
1192 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1193 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1194
1195 // This assert only makes sense here, before we adjust them
1196 // with respect to the min and max heap size.
1197 assert(minimum_desired_capacity <= maximum_desired_capacity,
1198 "minimum_desired_capacity = " SIZE_FORMAT ", "
1199 "maximum_desired_capacity = " SIZE_FORMAT,
1200 minimum_desired_capacity, maximum_desired_capacity);
1201
1202 // Should not be greater than the heap max size. No need to adjust
1203 // it with respect to the heap min size as it's a lower bound (i.e.,
1204 // we'll try to make the capacity larger than it, not smaller).
1205 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1206 // Should not be less than the heap min size. No need to adjust it
1207 // with respect to the heap max size as it's an upper bound (i.e.,
1208 // we'll try to make the capacity smaller than it, not greater).
1209 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1210
1211 if (capacity_after_gc < minimum_desired_capacity) {
1212 // Don't expand unless it's significant
1213 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1214
1215 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1216 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1217 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1218 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1219
1220 expand(expand_bytes, _workers);
1221
1222 // No expansion, now see if we want to shrink
1223 } else if (capacity_after_gc > maximum_desired_capacity) {
1224 // Capacity too large, compute shrinking size
1225 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1226
1227 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1228 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1229 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1230 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1231
1232 shrink(shrink_bytes);
1233 }
1234 }
1235
1236 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1237 bool do_gc,
1238 bool clear_all_soft_refs,
1239 bool expect_null_mutator_alloc_region,
1240 bool* gc_succeeded) {
1241 *gc_succeeded = true;
1242 // Let's attempt the allocation first.
1243 HeapWord* result =
1244 attempt_allocation_at_safepoint(word_size,
1245 expect_null_mutator_alloc_region);
1246 if (result != NULL) {
1247 return result;
1248 }
1249
1250 // In a G1 heap, we're supposed to keep allocation from failing by
1251 // incremental pauses. Therefore, at least for now, we'll favor
1252 // expansion over collection. (This might change in the future if we can
1253 // do something smarter than full collection to satisfy a failed alloc.)
1254 result = expand_and_allocate(word_size);
1255 if (result != NULL) {
1256 return result;
1257 }
1258
1259 if (do_gc) {
1260 // Expansion didn't work, we'll try to do a Full GC.
1261 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1262 clear_all_soft_refs);
1263 }
1264
1265 return NULL;
1266 }
1267
1268 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1269 bool* succeeded) {
1270 assert_at_safepoint_on_vm_thread();
1271
1272 // Attempts to allocate followed by Full GC.
1273 HeapWord* result =
1274 satisfy_failed_allocation_helper(word_size,
1275 true, /* do_gc */
1276 false, /* clear_all_soft_refs */
1277 false, /* expect_null_mutator_alloc_region */
1278 succeeded);
1279
1280 if (result != NULL || !*succeeded) {
1281 return result;
1282 }
1283
1284 // Attempts to allocate followed by Full GC that will collect all soft references.
1285 result = satisfy_failed_allocation_helper(word_size,
1286 true, /* do_gc */
1287 true, /* clear_all_soft_refs */
1288 true, /* expect_null_mutator_alloc_region */
1289 succeeded);
1290
1291 if (result != NULL || !*succeeded) {
1292 return result;
1293 }
1294
1295 // Attempts to allocate, no GC
1296 result = satisfy_failed_allocation_helper(word_size,
1297 false, /* do_gc */
1298 false, /* clear_all_soft_refs */
1299 true, /* expect_null_mutator_alloc_region */
1300 succeeded);
1301
1302 if (result != NULL) {
1303 return result;
1304 }
1305
1306 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1307 "Flag should have been handled and cleared prior to this point");
1308
1309 // What else? We might try synchronous finalization later. If the total
1310 // space available is large enough for the allocation, then a more
1311 // complete compaction phase than we've tried so far might be
1312 // appropriate.
1313 return NULL;
1314 }
1315
1316 // Attempting to expand the heap sufficiently
1317 // to support an allocation of the given "word_size". If
1318 // successful, perform the allocation and return the address of the
1319 // allocated block, or else "NULL".
1320
1321 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1322 assert_at_safepoint_on_vm_thread();
1323
1324 _verifier->verify_region_sets_optional();
1325
1326 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1327 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1328 word_size * HeapWordSize);
1329
1330
1331 if (expand(expand_bytes, _workers)) {
1332 _hrm->verify_optional();
1333 _verifier->verify_region_sets_optional();
1334 return attempt_allocation_at_safepoint(word_size,
1335 false /* expect_null_mutator_alloc_region */);
1336 }
1337 return NULL;
1338 }
1339
1340 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1341 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1342 aligned_expand_bytes = align_up(aligned_expand_bytes,
1343 HeapRegion::GrainBytes);
1344
1345 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1346 expand_bytes, aligned_expand_bytes);
1347
1348 if (is_maximal_no_gc()) {
1349 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1350 return false;
1351 }
1352
1353 double expand_heap_start_time_sec = os::elapsedTime();
1354 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1355 assert(regions_to_expand > 0, "Must expand by at least one region");
1356
1357 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1358 if (expand_time_ms != NULL) {
1359 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1360 }
1361
1362 if (expanded_by > 0) {
1363 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1364 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1365 g1_policy()->record_new_heap_size(num_regions());
1366 } else {
1367 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1368
1369 // The expansion of the virtual storage space was unsuccessful.
1370 // Let's see if it was because we ran out of swap.
1371 if (G1ExitOnExpansionFailure &&
1372 _hrm->available() >= regions_to_expand) {
1373 // We had head room...
1374 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1375 }
1376 }
1377 return regions_to_expand > 0;
1378 }
1379
1380 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1381 size_t aligned_shrink_bytes =
1382 ReservedSpace::page_align_size_down(shrink_bytes);
1383 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1384 HeapRegion::GrainBytes);
1385 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1386
1387 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1388 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1389
1390
1391 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",
1392 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1393 if (num_regions_removed > 0) {
1394 g1_policy()->record_new_heap_size(num_regions());
1395 } else {
1396 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1397 }
1398 }
1399
1400 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1401 _verifier->verify_region_sets_optional();
1402
1403 // We should only reach here at the end of a Full GC or during Remark which
1404 // means we should not not be holding to any GC alloc regions. The method
1405 // below will make sure of that and do any remaining clean up.
1406 _allocator->abandon_gc_alloc_regions();
1407
1408 // Instead of tearing down / rebuilding the free lists here, we
1409 // could instead use the remove_all_pending() method on free_list to
1410 // remove only the ones that we need to remove.
1411 tear_down_region_sets(true /* free_list_only */);
1412 shrink_helper(shrink_bytes);
1413 rebuild_region_sets(true /* free_list_only */);
1414
1415 _hrm->verify_optional();
1416 _verifier->verify_region_sets_optional();
1417 }
1418
1419 class OldRegionSetChecker : public HeapRegionSetChecker {
1420 public:
1421 void check_mt_safety() {
1422 // Master Old Set MT safety protocol:
1423 // (a) If we're at a safepoint, operations on the master old set
1424 // should be invoked:
1425 // - by the VM thread (which will serialize them), or
1426 // - by the GC workers while holding the FreeList_lock, if we're
1427 // at a safepoint for an evacuation pause (this lock is taken
1428 // anyway when an GC alloc region is retired so that a new one
1429 // is allocated from the free list), or
1430 // - by the GC workers while holding the OldSets_lock, if we're at a
1431 // safepoint for a cleanup pause.
1432 // (b) If we're not at a safepoint, operations on the master old set
1433 // should be invoked while holding the Heap_lock.
1434
1435 if (SafepointSynchronize::is_at_safepoint()) {
1436 guarantee(Thread::current()->is_VM_thread() ||
1437 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1438 "master old set MT safety protocol at a safepoint");
1439 } else {
1440 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1441 }
1442 }
1443 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1444 const char* get_description() { return "Old Regions"; }
1445 };
1446
1447 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1448 public:
1449 void check_mt_safety() {
1450 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1451 "May only change archive regions during initialization or safepoint.");
1452 }
1453 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1454 const char* get_description() { return "Archive Regions"; }
1455 };
1456
1457 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1458 public:
1459 void check_mt_safety() {
1460 // Humongous Set MT safety protocol:
1461 // (a) If we're at a safepoint, operations on the master humongous
1462 // set should be invoked by either the VM thread (which will
1463 // serialize them) or by the GC workers while holding the
1464 // OldSets_lock.
1465 // (b) If we're not at a safepoint, operations on the master
1466 // humongous set should be invoked while holding the Heap_lock.
1467
1468 if (SafepointSynchronize::is_at_safepoint()) {
1469 guarantee(Thread::current()->is_VM_thread() ||
1470 OldSets_lock->owned_by_self(),
1471 "master humongous set MT safety protocol at a safepoint");
1472 } else {
1473 guarantee(Heap_lock->owned_by_self(),
1474 "master humongous set MT safety protocol outside a safepoint");
1475 }
1476 }
1477 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1478 const char* get_description() { return "Humongous Regions"; }
1479 };
1480
1481 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1482 CollectedHeap(),
1483 _young_gen_sampling_thread(NULL),
1484 _workers(NULL),
1485 _collector_policy(collector_policy),
1486 _card_table(NULL),
1487 _soft_ref_policy(),
1488 _old_set("Old Region Set", new OldRegionSetChecker()),
1489 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1490 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1491 _bot(NULL),
1492 _listener(),
1493 _hrm(NULL),
1494 _allocator(NULL),
1495 _verifier(NULL),
1496 _summary_bytes_used(0),
1497 _archive_allocator(NULL),
1498 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1499 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1500 _expand_heap_after_alloc_failure(true),
1501 _g1mm(NULL),
1502 _humongous_reclaim_candidates(),
1503 _has_humongous_reclaim_candidates(false),
1504 _hr_printer(),
1505 _collector_state(),
1506 _old_marking_cycles_started(0),
1507 _old_marking_cycles_completed(0),
1508 _eden(),
1509 _survivor(),
1510 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1511 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1512 _g1_policy(G1Policy::create_policy(collector_policy, _gc_timer_stw)),
1513 _heap_sizing_policy(NULL),
1514 _collection_set(this, _g1_policy),
1515 _hot_card_cache(NULL),
1516 _g1_rem_set(NULL),
1517 _dirty_card_queue_set(false),
1518 _cm(NULL),
1519 _cm_thread(NULL),
1520 _cr(NULL),
1521 _task_queues(NULL),
1522 _evacuation_failed(false),
1523 _evacuation_failed_info_array(NULL),
1524 _preserved_marks_set(true /* in_c_heap */),
1525 #ifndef PRODUCT
1526 _evacuation_failure_alot_for_current_gc(false),
1527 _evacuation_failure_alot_gc_number(0),
1528 _evacuation_failure_alot_count(0),
1529 #endif
1530 _ref_processor_stw(NULL),
1531 _is_alive_closure_stw(this),
1532 _is_subject_to_discovery_stw(this),
1533 _ref_processor_cm(NULL),
1534 _is_alive_closure_cm(this),
1535 _is_subject_to_discovery_cm(this),
1536 _in_cset_fast_test() {
1537
1538 _verifier = new G1HeapVerifier(this);
1539
1540 _allocator = new G1Allocator(this);
1541
1542 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1543
1544 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1545
1546 // Override the default _filler_array_max_size so that no humongous filler
1547 // objects are created.
1548 _filler_array_max_size = _humongous_object_threshold_in_words;
1549
1550 uint n_queues = ParallelGCThreads;
1551 _task_queues = new RefToScanQueueSet(n_queues);
1552
1553 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1554
1555 for (uint i = 0; i < n_queues; i++) {
1556 RefToScanQueue* q = new RefToScanQueue();
1557 q->initialize();
1558 _task_queues->register_queue(i, q);
1559 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1560 }
1561
1562 // Initialize the G1EvacuationFailureALot counters and flags.
1563 NOT_PRODUCT(reset_evacuation_should_fail();)
1564
1565 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1566 }
1567
1568 static size_t actual_reserved_page_size(ReservedSpace rs) {
1569 size_t page_size = os::vm_page_size();
1570 if (UseLargePages) {
1571 // There are two ways to manage large page memory.
1572 // 1. OS supports committing large page memory.
1573 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1574 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1575 // we reserved memory without large page.
1576 if (os::can_commit_large_page_memory() || rs.special()) {
1577 page_size = rs.alignment();
1578 }
1579 }
1580
1581 return page_size;
1582 }
1583
1584 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1585 size_t size,
1586 size_t translation_factor) {
1587 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1588 // Allocate a new reserved space, preferring to use large pages.
1589 ReservedSpace rs(size, preferred_page_size);
1590 size_t page_size = actual_reserved_page_size(rs);
1591 G1RegionToSpaceMapper* result =
1592 G1RegionToSpaceMapper::create_mapper(rs,
1593 size,
1594 page_size,
1595 HeapRegion::GrainBytes,
1596 translation_factor,
1597 mtGC);
1598
1599 os::trace_page_sizes_for_requested_size(description,
1600 size,
1601 preferred_page_size,
1602 page_size,
1603 rs.base(),
1604 rs.size());
1605
1606 return result;
1607 }
1608
1609 jint G1CollectedHeap::initialize_concurrent_refinement() {
1610 jint ecode = JNI_OK;
1611 _cr = G1ConcurrentRefine::create(&ecode);
1612 return ecode;
1613 }
1614
1615 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1616 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1617 if (_young_gen_sampling_thread->osthread() == NULL) {
1618 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1619 return JNI_ENOMEM;
1620 }
1621 return JNI_OK;
1622 }
1623
1624 jint G1CollectedHeap::initialize() {
1625 os::enable_vtime();
1626
1627 // Necessary to satisfy locking discipline assertions.
1628
1629 MutexLocker x(Heap_lock);
1630
1631 // While there are no constraints in the GC code that HeapWordSize
1632 // be any particular value, there are multiple other areas in the
1633 // system which believe this to be true (e.g. oop->object_size in some
1634 // cases incorrectly returns the size in wordSize units rather than
1635 // HeapWordSize).
1636 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1637
1638 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1639 size_t max_byte_size = g1_collector_policy()->heap_reserved_size_bytes();
1640 size_t heap_alignment = collector_policy()->heap_alignment();
1641
1642 // Ensure that the sizes are properly aligned.
1643 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1644 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1645 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1646
1647 // Reserve the maximum.
1648
1649 // When compressed oops are enabled, the preferred heap base
1650 // is calculated by subtracting the requested size from the
1651 // 32Gb boundary and using the result as the base address for
1652 // heap reservation. If the requested size is not aligned to
1653 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1654 // into the ReservedHeapSpace constructor) then the actual
1655 // base of the reserved heap may end up differing from the
1656 // address that was requested (i.e. the preferred heap base).
1657 // If this happens then we could end up using a non-optimal
1658 // compressed oops mode.
1659
1660 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1661 heap_alignment);
1662
1663 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1664
1665 // Create the barrier set for the entire reserved region.
1666 G1CardTable* ct = new G1CardTable(reserved_region());
1667 ct->initialize();
1668 G1BarrierSet* bs = new G1BarrierSet(ct);
1669 bs->initialize();
1670 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1671 BarrierSet::set_barrier_set(bs);
1672 _card_table = ct;
1673
1674 G1BarrierSet::satb_mark_queue_set().initialize(this,
1675 SATB_Q_CBL_mon,
1676 &bs->satb_mark_queue_buffer_allocator(),
1677 G1SATBProcessCompletedThreshold,
1678 G1SATBBufferEnqueueingThresholdPercent,
1679 Shared_SATB_Q_lock);
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, g1_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 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1757 _g1_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 g1_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 DirtyCardQueueSet& 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 G1CollectorPolicy* G1CollectedHeap::g1_collector_policy() const {
1942 return _collector_policy;
1943 }
1944
1945 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1946 return &_soft_ref_policy;
1947 }
1948
1949 size_t G1CollectedHeap::capacity() const {
1950 return _hrm->length() * HeapRegion::GrainBytes;
1951 }
1952
1953 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1954 return _hrm->total_free_bytes();
1955 }
1956
1957 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1958 _hot_card_cache->drain(cl, worker_i);
1959 }
1960
1961 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1962 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1963 size_t n_completed_buffers = 0;
1964 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1965 n_completed_buffers++;
1966 }
1967 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!");
1968 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1969 }
1970
1971 // Computes the sum of the storage used by the various regions.
1972 size_t G1CollectedHeap::used() const {
1973 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1974 if (_archive_allocator != NULL) {
1975 result += _archive_allocator->used();
1976 }
1977 return result;
1978 }
1979
1980 size_t G1CollectedHeap::used_unlocked() const {
1981 return _summary_bytes_used;
1982 }
1983
1984 class SumUsedClosure: public HeapRegionClosure {
1985 size_t _used;
1986 public:
1987 SumUsedClosure() : _used(0) {}
1988 bool do_heap_region(HeapRegion* r) {
1989 _used += r->used();
1990 return false;
1991 }
1992 size_t result() { return _used; }
1993 };
1994
1995 size_t G1CollectedHeap::recalculate_used() const {
1996 SumUsedClosure blk;
1997 heap_region_iterate(&blk);
1998 return blk.result();
1999 }
2000
2001 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2002 switch (cause) {
2003 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2004 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2005 case GCCause::_wb_conc_mark: return true;
2006 default : return false;
2007 }
2008 }
2009
2010 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2011 switch (cause) {
2012 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2013 case GCCause::_g1_humongous_allocation: return true;
2014 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2015 default: return is_user_requested_concurrent_full_gc(cause);
2016 }
2017 }
2018
2019 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2020 if(g1_policy()->force_upgrade_to_full()) {
2021 return true;
2022 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2023 return false;
2024 } else if (has_regions_left_for_allocation()) {
2025 return false;
2026 } else {
2027 return true;
2028 }
2029 }
2030
2031 #ifndef PRODUCT
2032 void G1CollectedHeap::allocate_dummy_regions() {
2033 // Let's fill up most of the region
2034 size_t word_size = HeapRegion::GrainWords - 1024;
2035 // And as a result the region we'll allocate will be humongous.
2036 guarantee(is_humongous(word_size), "sanity");
2037
2038 // _filler_array_max_size is set to humongous object threshold
2039 // but temporarily change it to use CollectedHeap::fill_with_object().
2040 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2041
2042 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2043 // Let's use the existing mechanism for the allocation
2044 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2045 if (dummy_obj != NULL) {
2046 MemRegion mr(dummy_obj, word_size);
2047 CollectedHeap::fill_with_object(mr);
2048 } else {
2049 // If we can't allocate once, we probably cannot allocate
2050 // again. Let's get out of the loop.
2051 break;
2052 }
2053 }
2054 }
2055 #endif // !PRODUCT
2056
2057 void G1CollectedHeap::increment_old_marking_cycles_started() {
2058 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2059 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2060 "Wrong marking cycle count (started: %d, completed: %d)",
2061 _old_marking_cycles_started, _old_marking_cycles_completed);
2062
2063 _old_marking_cycles_started++;
2064 }
2065
2066 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2067 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2068
2069 // We assume that if concurrent == true, then the caller is a
2070 // concurrent thread that was joined the Suspendible Thread
2071 // Set. If there's ever a cheap way to check this, we should add an
2072 // assert here.
2073
2074 // Given that this method is called at the end of a Full GC or of a
2075 // concurrent cycle, and those can be nested (i.e., a Full GC can
2076 // interrupt a concurrent cycle), the number of full collections
2077 // completed should be either one (in the case where there was no
2078 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2079 // behind the number of full collections started.
2080
2081 // This is the case for the inner caller, i.e. a Full GC.
2082 assert(concurrent ||
2083 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2084 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2085 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2086 "is inconsistent with _old_marking_cycles_completed = %u",
2087 _old_marking_cycles_started, _old_marking_cycles_completed);
2088
2089 // This is the case for the outer caller, i.e. the concurrent cycle.
2090 assert(!concurrent ||
2091 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2092 "for outer caller (concurrent cycle): "
2093 "_old_marking_cycles_started = %u "
2094 "is inconsistent with _old_marking_cycles_completed = %u",
2095 _old_marking_cycles_started, _old_marking_cycles_completed);
2096
2097 _old_marking_cycles_completed += 1;
2098
2099 // We need to clear the "in_progress" flag in the CM thread before
2100 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2101 // is set) so that if a waiter requests another System.gc() it doesn't
2102 // incorrectly see that a marking cycle is still in progress.
2103 if (concurrent) {
2104 _cm_thread->set_idle();
2105 }
2106
2107 // This notify_all() will ensure that a thread that called
2108 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2109 // and it's waiting for a full GC to finish will be woken up. It is
2110 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2111 FullGCCount_lock->notify_all();
2112 }
2113
2114 void G1CollectedHeap::collect(GCCause::Cause cause) {
2115 assert_heap_not_locked();
2116
2117 uint gc_count_before;
2118 uint old_marking_count_before;
2119 uint full_gc_count_before;
2120 bool retry_gc;
2121
2122 do {
2123 retry_gc = false;
2124
2125 {
2126 MutexLocker ml(Heap_lock);
2127
2128 // Read the GC count while holding the Heap_lock
2129 gc_count_before = total_collections();
2130 full_gc_count_before = total_full_collections();
2131 old_marking_count_before = _old_marking_cycles_started;
2132 }
2133
2134 if (should_do_concurrent_full_gc(cause)) {
2135 // Schedule an initial-mark evacuation pause that will start a
2136 // concurrent cycle. We're setting word_size to 0 which means that
2137 // we are not requesting a post-GC allocation.
2138 VM_G1CollectForAllocation op(0, /* word_size */
2139 gc_count_before,
2140 cause,
2141 true, /* should_initiate_conc_mark */
2142 g1_policy()->max_pause_time_ms());
2143 VMThread::execute(&op);
2144 if (!op.pause_succeeded()) {
2145 if (old_marking_count_before == _old_marking_cycles_started) {
2146 retry_gc = op.should_retry_gc();
2147 } else {
2148 // A Full GC happened while we were trying to schedule the
2149 // initial-mark GC. No point in starting a new cycle given
2150 // that the whole heap was collected anyway.
2151 }
2152
2153 if (retry_gc) {
2154 if (GCLocker::is_active_and_needs_gc()) {
2155 GCLocker::stall_until_clear();
2156 }
2157 }
2158 }
2159 } else {
2160 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2161 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2162
2163 // Schedule a standard evacuation pause. We're setting word_size
2164 // to 0 which means that we are not requesting a post-GC allocation.
2165 VM_G1CollectForAllocation op(0, /* word_size */
2166 gc_count_before,
2167 cause,
2168 false, /* should_initiate_conc_mark */
2169 g1_policy()->max_pause_time_ms());
2170 VMThread::execute(&op);
2171 } else {
2172 // Schedule a Full GC.
2173 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2174 VMThread::execute(&op);
2175 }
2176 }
2177 } while (retry_gc);
2178 }
2179
2180 bool G1CollectedHeap::is_in(const void* p) const {
2181 if (_hrm->reserved().contains(p)) {
2182 // Given that we know that p is in the reserved space,
2183 // heap_region_containing() should successfully
2184 // return the containing region.
2185 HeapRegion* hr = heap_region_containing(p);
2186 return hr->is_in(p);
2187 } else {
2188 return false;
2189 }
2190 }
2191
2192 #ifdef ASSERT
2193 bool G1CollectedHeap::is_in_exact(const void* p) const {
2194 bool contains = reserved_region().contains(p);
2195 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2196 if (contains && available) {
2197 return true;
2198 } else {
2199 return false;
2200 }
2201 }
2202 #endif
2203
2204 // Iteration functions.
2205
2206 // Iterates an ObjectClosure over all objects within a HeapRegion.
2207
2208 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2209 ObjectClosure* _cl;
2210 public:
2211 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2212 bool do_heap_region(HeapRegion* r) {
2213 if (!r->is_continues_humongous()) {
2214 r->object_iterate(_cl);
2215 }
2216 return false;
2217 }
2218 };
2219
2220 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2221 IterateObjectClosureRegionClosure blk(cl);
2222 heap_region_iterate(&blk);
2223 }
2224
2225 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2226 _hrm->iterate(cl);
2227 }
2228
2229 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2230 HeapRegionClaimer *hrclaimer,
2231 uint worker_id) const {
2232 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2233 }
2234
2235 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2236 HeapRegionClaimer *hrclaimer) const {
2237 _hrm->par_iterate(cl, hrclaimer, 0);
2238 }
2239
2240 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2241 _collection_set.iterate(cl);
2242 }
2243
2244 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2245 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2246 }
2247
2248 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2249 HeapRegion* hr = heap_region_containing(addr);
2250 return hr->block_start(addr);
2251 }
2252
2253 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2254 HeapRegion* hr = heap_region_containing(addr);
2255 return hr->block_size(addr);
2256 }
2257
2258 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2259 HeapRegion* hr = heap_region_containing(addr);
2260 return hr->block_is_obj(addr);
2261 }
2262
2263 bool G1CollectedHeap::supports_tlab_allocation() const {
2264 return true;
2265 }
2266
2267 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2268 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2269 }
2270
2271 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2272 return _eden.length() * HeapRegion::GrainBytes;
2273 }
2274
2275 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2276 // must be equal to the humongous object limit.
2277 size_t G1CollectedHeap::max_tlab_size() const {
2278 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2279 }
2280
2281 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2282 return _allocator->unsafe_max_tlab_alloc();
2283 }
2284
2285 size_t G1CollectedHeap::max_capacity() const {
2286 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2287 }
2288
2289 size_t G1CollectedHeap::max_reserved_capacity() const {
2290 return _hrm->max_length() * HeapRegion::GrainBytes;
2291 }
2292
2293 jlong G1CollectedHeap::millis_since_last_gc() {
2294 // See the notes in GenCollectedHeap::millis_since_last_gc()
2295 // for more information about the implementation.
2296 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2297 _g1_policy->collection_pause_end_millis();
2298 if (ret_val < 0) {
2299 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2300 ". returning zero instead.", ret_val);
2301 return 0;
2302 }
2303 return ret_val;
2304 }
2305
2306 void G1CollectedHeap::deduplicate_string(oop str) {
2307 assert(java_lang_String::is_instance(str), "invariant");
2308
2309 if (G1StringDedup::is_enabled()) {
2310 G1StringDedup::deduplicate(str);
2311 }
2312 }
2313
2314 void G1CollectedHeap::prepare_for_verify() {
2315 _verifier->prepare_for_verify();
2316 }
2317
2318 void G1CollectedHeap::verify(VerifyOption vo) {
2319 _verifier->verify(vo);
2320 }
2321
2322 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2323 return true;
2324 }
2325
2326 const char* const* G1CollectedHeap::concurrent_phases() const {
2327 return _cm_thread->concurrent_phases();
2328 }
2329
2330 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2331 return _cm_thread->request_concurrent_phase(phase);
2332 }
2333
2334 class PrintRegionClosure: public HeapRegionClosure {
2335 outputStream* _st;
2336 public:
2337 PrintRegionClosure(outputStream* st) : _st(st) {}
2338 bool do_heap_region(HeapRegion* r) {
2339 r->print_on(_st);
2340 return false;
2341 }
2342 };
2343
2344 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2345 const HeapRegion* hr,
2346 const VerifyOption vo) const {
2347 switch (vo) {
2348 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2349 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2350 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2351 default: ShouldNotReachHere();
2352 }
2353 return false; // keep some compilers happy
2354 }
2355
2356 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2357 const VerifyOption vo) const {
2358 switch (vo) {
2359 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2360 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2361 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2362 default: ShouldNotReachHere();
2363 }
2364 return false; // keep some compilers happy
2365 }
2366
2367 void G1CollectedHeap::print_heap_regions() const {
2368 LogTarget(Trace, gc, heap, region) lt;
2369 if (lt.is_enabled()) {
2370 LogStream ls(lt);
2371 print_regions_on(&ls);
2372 }
2373 }
2374
2375 void G1CollectedHeap::print_on(outputStream* st) const {
2376 st->print(" %-20s", "garbage-first heap");
2377 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2378 capacity()/K, used_unlocked()/K);
2379 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2380 p2i(_hrm->reserved().start()),
2381 p2i(_hrm->reserved().end()));
2382 st->cr();
2383 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2384 uint young_regions = young_regions_count();
2385 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2386 (size_t) young_regions * HeapRegion::GrainBytes / K);
2387 uint survivor_regions = survivor_regions_count();
2388 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2389 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2390 st->cr();
2391 MetaspaceUtils::print_on(st);
2392 }
2393
2394 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2395 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2396 "HS=humongous(starts), HC=humongous(continues), "
2397 "CS=collection set, F=free, A=archive, "
2398 "TAMS=top-at-mark-start (previous, next)");
2399 PrintRegionClosure blk(st);
2400 heap_region_iterate(&blk);
2401 }
2402
2403 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2404 print_on(st);
2405
2406 // Print the per-region information.
2407 print_regions_on(st);
2408 }
2409
2410 void G1CollectedHeap::print_on_error(outputStream* st) const {
2411 this->CollectedHeap::print_on_error(st);
2412
2413 if (_cm != NULL) {
2414 st->cr();
2415 _cm->print_on_error(st);
2416 }
2417 }
2418
2419 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2420 workers()->print_worker_threads_on(st);
2421 _cm_thread->print_on(st);
2422 st->cr();
2423 _cm->print_worker_threads_on(st);
2424 _cr->print_threads_on(st);
2425 _young_gen_sampling_thread->print_on(st);
2426 if (G1StringDedup::is_enabled()) {
2427 G1StringDedup::print_worker_threads_on(st);
2428 }
2429 }
2430
2431 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2432 workers()->threads_do(tc);
2433 tc->do_thread(_cm_thread);
2434 _cm->threads_do(tc);
2435 _cr->threads_do(tc);
2436 tc->do_thread(_young_gen_sampling_thread);
2437 if (G1StringDedup::is_enabled()) {
2438 G1StringDedup::threads_do(tc);
2439 }
2440 }
2441
2442 void G1CollectedHeap::print_tracing_info() const {
2443 g1_rem_set()->print_summary_info();
2444 concurrent_mark()->print_summary_info();
2445 }
2446
2447 #ifndef PRODUCT
2448 // Helpful for debugging RSet issues.
2449
2450 class PrintRSetsClosure : public HeapRegionClosure {
2451 private:
2452 const char* _msg;
2453 size_t _occupied_sum;
2454
2455 public:
2456 bool do_heap_region(HeapRegion* r) {
2457 HeapRegionRemSet* hrrs = r->rem_set();
2458 size_t occupied = hrrs->occupied();
2459 _occupied_sum += occupied;
2460
2461 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2462 if (occupied == 0) {
2463 tty->print_cr(" RSet is empty");
2464 } else {
2465 hrrs->print();
2466 }
2467 tty->print_cr("----------");
2468 return false;
2469 }
2470
2471 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2472 tty->cr();
2473 tty->print_cr("========================================");
2474 tty->print_cr("%s", msg);
2475 tty->cr();
2476 }
2477
2478 ~PrintRSetsClosure() {
2479 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2480 tty->print_cr("========================================");
2481 tty->cr();
2482 }
2483 };
2484
2485 void G1CollectedHeap::print_cset_rsets() {
2486 PrintRSetsClosure cl("Printing CSet RSets");
2487 collection_set_iterate(&cl);
2488 }
2489
2490 void G1CollectedHeap::print_all_rsets() {
2491 PrintRSetsClosure cl("Printing All RSets");;
2492 heap_region_iterate(&cl);
2493 }
2494 #endif // PRODUCT
2495
2496 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2497
2498 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2499 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2500 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2501
2502 size_t eden_capacity_bytes =
2503 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2504
2505 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2506 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2507 eden_capacity_bytes, survivor_used_bytes, num_regions());
2508 }
2509
2510 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2511 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2512 stats->unused(), stats->used(), stats->region_end_waste(),
2513 stats->regions_filled(), stats->direct_allocated(),
2514 stats->failure_used(), stats->failure_waste());
2515 }
2516
2517 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2518 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2519 gc_tracer->report_gc_heap_summary(when, heap_summary);
2520
2521 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2522 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2523 }
2524
2525 G1CollectedHeap* G1CollectedHeap::heap() {
2526 CollectedHeap* heap = Universe::heap();
2527 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2528 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2529 return (G1CollectedHeap*)heap;
2530 }
2531
2532 void G1CollectedHeap::gc_prologue(bool full) {
2533 // always_do_update_barrier = false;
2534 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2535
2536 // This summary needs to be printed before incrementing total collections.
2537 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2538
2539 // Update common counters.
2540 increment_total_collections(full /* full gc */);
2541 if (full) {
2542 increment_old_marking_cycles_started();
2543 }
2544
2545 // Fill TLAB's and such
2546 double start = os::elapsedTime();
2547 ensure_parsability(true);
2548 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2549 }
2550
2551 void G1CollectedHeap::gc_epilogue(bool full) {
2552 // Update common counters.
2553 if (full) {
2554 // Update the number of full collections that have been completed.
2555 increment_old_marking_cycles_completed(false /* concurrent */);
2556 }
2557
2558 // We are at the end of the GC. Total collections has already been increased.
2559 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2560
2561 // FIXME: what is this about?
2562 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2563 // is set.
2564 #if COMPILER2_OR_JVMCI
2565 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2566 #endif
2567 // always_do_update_barrier = true;
2568
2569 double start = os::elapsedTime();
2570 resize_all_tlabs();
2571 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2572
2573 MemoryService::track_memory_usage();
2574 // We have just completed a GC. Update the soft reference
2575 // policy with the new heap occupancy
2576 Universe::update_heap_info_at_gc();
2577 }
2578
2579 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2580 uint gc_count_before,
2581 bool* succeeded,
2582 GCCause::Cause gc_cause) {
2583 assert_heap_not_locked_and_not_at_safepoint();
2584 VM_G1CollectForAllocation op(word_size,
2585 gc_count_before,
2586 gc_cause,
2587 false, /* should_initiate_conc_mark */
2588 g1_policy()->max_pause_time_ms());
2589 VMThread::execute(&op);
2590
2591 HeapWord* result = op.result();
2592 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2593 assert(result == NULL || ret_succeeded,
2594 "the result should be NULL if the VM did not succeed");
2595 *succeeded = ret_succeeded;
2596
2597 assert_heap_not_locked();
2598 return result;
2599 }
2600
2601 void G1CollectedHeap::do_concurrent_mark() {
2602 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2603 if (!_cm_thread->in_progress()) {
2604 _cm_thread->set_started();
2605 CGC_lock->notify();
2606 }
2607 }
2608
2609 size_t G1CollectedHeap::pending_card_num() {
2610 size_t extra_cards = 0;
2611 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2612 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2613 extra_cards += dcq.size();
2614 }
2615 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2616 size_t buffer_size = dcqs.buffer_size();
2617 size_t buffer_num = dcqs.completed_buffers_num();
2618
2619 return buffer_size * buffer_num + extra_cards;
2620 }
2621
2622 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2623 // We don't nominate objects with many remembered set entries, on
2624 // the assumption that such objects are likely still live.
2625 HeapRegionRemSet* rem_set = r->rem_set();
2626
2627 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2628 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2629 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2630 }
2631
2632 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2633 private:
2634 size_t _total_humongous;
2635 size_t _candidate_humongous;
2636
2637 DirtyCardQueue _dcq;
2638
2639 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2640 assert(region->is_starts_humongous(), "Must start a humongous object");
2641
2642 oop obj = oop(region->bottom());
2643
2644 // Dead objects cannot be eager reclaim candidates. Due to class
2645 // unloading it is unsafe to query their classes so we return early.
2646 if (g1h->is_obj_dead(obj, region)) {
2647 return false;
2648 }
2649
2650 // If we do not have a complete remembered set for the region, then we can
2651 // not be sure that we have all references to it.
2652 if (!region->rem_set()->is_complete()) {
2653 return false;
2654 }
2655 // Candidate selection must satisfy the following constraints
2656 // while concurrent marking is in progress:
2657 //
2658 // * In order to maintain SATB invariants, an object must not be
2659 // reclaimed if it was allocated before the start of marking and
2660 // has not had its references scanned. Such an object must have
2661 // its references (including type metadata) scanned to ensure no
2662 // live objects are missed by the marking process. Objects
2663 // allocated after the start of concurrent marking don't need to
2664 // be scanned.
2665 //
2666 // * An object must not be reclaimed if it is on the concurrent
2667 // mark stack. Objects allocated after the start of concurrent
2668 // marking are never pushed on the mark stack.
2669 //
2670 // Nominating only objects allocated after the start of concurrent
2671 // marking is sufficient to meet both constraints. This may miss
2672 // some objects that satisfy the constraints, but the marking data
2673 // structures don't support efficiently performing the needed
2674 // additional tests or scrubbing of the mark stack.
2675 //
2676 // However, we presently only nominate is_typeArray() objects.
2677 // A humongous object containing references induces remembered
2678 // set entries on other regions. In order to reclaim such an
2679 // object, those remembered sets would need to be cleaned up.
2680 //
2681 // We also treat is_typeArray() objects specially, allowing them
2682 // to be reclaimed even if allocated before the start of
2683 // concurrent mark. For this we rely on mark stack insertion to
2684 // exclude is_typeArray() objects, preventing reclaiming an object
2685 // that is in the mark stack. We also rely on the metadata for
2686 // such objects to be built-in and so ensured to be kept live.
2687 // Frequent allocation and drop of large binary blobs is an
2688 // important use case for eager reclaim, and this special handling
2689 // may reduce needed headroom.
2690
2691 return obj->is_typeArray() &&
2692 g1h->is_potential_eager_reclaim_candidate(region);
2693 }
2694
2695 public:
2696 RegisterHumongousWithInCSetFastTestClosure()
2697 : _total_humongous(0),
2698 _candidate_humongous(0),
2699 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2700 }
2701
2702 virtual bool do_heap_region(HeapRegion* r) {
2703 if (!r->is_starts_humongous()) {
2704 return false;
2705 }
2706 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2707
2708 bool is_candidate = humongous_region_is_candidate(g1h, r);
2709 uint rindex = r->hrm_index();
2710 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2711 if (is_candidate) {
2712 _candidate_humongous++;
2713 g1h->register_humongous_region_with_cset(rindex);
2714 // Is_candidate already filters out humongous object with large remembered sets.
2715 // If we have a humongous object with a few remembered sets, we simply flush these
2716 // remembered set entries into the DCQS. That will result in automatic
2717 // re-evaluation of their remembered set entries during the following evacuation
2718 // phase.
2719 if (!r->rem_set()->is_empty()) {
2720 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2721 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2722 G1CardTable* ct = g1h->card_table();
2723 HeapRegionRemSetIterator hrrs(r->rem_set());
2724 size_t card_index;
2725 while (hrrs.has_next(card_index)) {
2726 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2727 // The remembered set might contain references to already freed
2728 // regions. Filter out such entries to avoid failing card table
2729 // verification.
2730 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2731 if (*card_ptr != G1CardTable::dirty_card_val()) {
2732 *card_ptr = G1CardTable::dirty_card_val();
2733 _dcq.enqueue(card_ptr);
2734 }
2735 }
2736 }
2737 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2738 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2739 hrrs.n_yielded(), r->rem_set()->occupied());
2740 // We should only clear the card based remembered set here as we will not
2741 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2742 // (and probably never) we do not enter this path if there are other kind of
2743 // remembered sets for this region.
2744 r->rem_set()->clear_locked(true /* only_cardset */);
2745 // Clear_locked() above sets the state to Empty. However we want to continue
2746 // collecting remembered set entries for humongous regions that were not
2747 // reclaimed.
2748 r->rem_set()->set_state_complete();
2749 }
2750 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2751 }
2752 _total_humongous++;
2753
2754 return false;
2755 }
2756
2757 size_t total_humongous() const { return _total_humongous; }
2758 size_t candidate_humongous() const { return _candidate_humongous; }
2759
2760 void flush_rem_set_entries() { _dcq.flush(); }
2761 };
2762
2763 void G1CollectedHeap::register_humongous_regions_with_cset() {
2764 if (!G1EagerReclaimHumongousObjects) {
2765 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2766 return;
2767 }
2768 double time = os::elapsed_counter();
2769
2770 // Collect reclaim candidate information and register candidates with cset.
2771 RegisterHumongousWithInCSetFastTestClosure cl;
2772 heap_region_iterate(&cl);
2773
2774 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2775 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2776 cl.total_humongous(),
2777 cl.candidate_humongous());
2778 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2779
2780 // Finally flush all remembered set entries to re-check into the global DCQS.
2781 cl.flush_rem_set_entries();
2782 }
2783
2784 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2785 public:
2786 bool do_heap_region(HeapRegion* hr) {
2787 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2788 hr->verify_rem_set();
2789 }
2790 return false;
2791 }
2792 };
2793
2794 uint G1CollectedHeap::num_task_queues() const {
2795 return _task_queues->size();
2796 }
2797
2798 #if TASKQUEUE_STATS
2799 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2800 st->print_raw_cr("GC Task Stats");
2801 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2802 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2803 }
2804
2805 void G1CollectedHeap::print_taskqueue_stats() const {
2806 if (!log_is_enabled(Trace, gc, task, stats)) {
2807 return;
2808 }
2809 Log(gc, task, stats) log;
2810 ResourceMark rm;
2811 LogStream ls(log.trace());
2812 outputStream* st = &ls;
2813
2814 print_taskqueue_stats_hdr(st);
2815
2816 TaskQueueStats totals;
2817 const uint n = num_task_queues();
2818 for (uint i = 0; i < n; ++i) {
2819 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2820 totals += task_queue(i)->stats;
2821 }
2822 st->print_raw("tot "); totals.print(st); st->cr();
2823
2824 DEBUG_ONLY(totals.verify());
2825 }
2826
2827 void G1CollectedHeap::reset_taskqueue_stats() {
2828 const uint n = num_task_queues();
2829 for (uint i = 0; i < n; ++i) {
2830 task_queue(i)->stats.reset();
2831 }
2832 }
2833 #endif // TASKQUEUE_STATS
2834
2835 void G1CollectedHeap::wait_for_root_region_scanning() {
2836 double scan_wait_start = os::elapsedTime();
2837 // We have to wait until the CM threads finish scanning the
2838 // root regions as it's the only way to ensure that all the
2839 // objects on them have been correctly scanned before we start
2840 // moving them during the GC.
2841 bool waited = _cm->root_regions()->wait_until_scan_finished();
2842 double wait_time_ms = 0.0;
2843 if (waited) {
2844 double scan_wait_end = os::elapsedTime();
2845 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2846 }
2847 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2848 }
2849
2850 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2851 private:
2852 G1HRPrinter* _hr_printer;
2853 public:
2854 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2855
2856 virtual bool do_heap_region(HeapRegion* r) {
2857 _hr_printer->cset(r);
2858 return false;
2859 }
2860 };
2861
2862 void G1CollectedHeap::start_new_collection_set() {
2863 collection_set()->start_incremental_building();
2864
2865 clear_cset_fast_test();
2866
2867 guarantee(_eden.length() == 0, "eden should have been cleared");
2868 g1_policy()->transfer_survivors_to_cset(survivor());
2869 }
2870
2871 bool
2872 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2873 assert_at_safepoint_on_vm_thread();
2874 guarantee(!is_gc_active(), "collection is not reentrant");
2875
2876 if (GCLocker::check_active_before_gc()) {
2877 return false;
2878 }
2879
2880 _gc_timer_stw->register_gc_start();
2881
2882 GCIdMark gc_id_mark;
2883 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2884
2885 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2886 ResourceMark rm;
2887
2888 g1_policy()->note_gc_start();
2889
2890 wait_for_root_region_scanning();
2891
2892 print_heap_before_gc();
2893 print_heap_regions();
2894 trace_heap_before_gc(_gc_tracer_stw);
2895
2896 _verifier->verify_region_sets_optional();
2897 _verifier->verify_dirty_young_regions();
2898
2899 // We should not be doing initial mark unless the conc mark thread is running
2900 if (!_cm_thread->should_terminate()) {
2901 // This call will decide whether this pause is an initial-mark
2902 // pause. If it is, in_initial_mark_gc() will return true
2903 // for the duration of this pause.
2904 g1_policy()->decide_on_conc_mark_initiation();
2905 }
2906
2907 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2908 assert(!collector_state()->in_initial_mark_gc() ||
2909 collector_state()->in_young_only_phase(), "sanity");
2910
2911 // We also do not allow mixed GCs during marking.
2912 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2913
2914 // Record whether this pause is an initial mark. When the current
2915 // thread has completed its logging output and it's safe to signal
2916 // the CM thread, the flag's value in the policy has been reset.
2917 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2918
2919 // Inner scope for scope based logging, timers, and stats collection
2920 {
2921 G1EvacuationInfo evacuation_info;
2922
2923 if (collector_state()->in_initial_mark_gc()) {
2924 // We are about to start a marking cycle, so we increment the
2925 // full collection counter.
2926 increment_old_marking_cycles_started();
2927 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2928 }
2929
2930 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2931
2932 GCTraceCPUTime tcpu;
2933
2934 G1HeapVerifier::G1VerifyType verify_type;
2935 FormatBuffer<> gc_string("Pause Young ");
2936 if (collector_state()->in_initial_mark_gc()) {
2937 gc_string.append("(Concurrent Start)");
2938 verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2939 } else if (collector_state()->in_young_only_phase()) {
2940 if (collector_state()->in_young_gc_before_mixed()) {
2941 gc_string.append("(Prepare Mixed)");
2942 } else {
2943 gc_string.append("(Normal)");
2944 }
2945 verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2946 } else {
2947 gc_string.append("(Mixed)");
2948 verify_type = G1HeapVerifier::G1VerifyMixed;
2949 }
2950 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2951
2952 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2953 workers()->active_workers(),
2954 Threads::number_of_non_daemon_threads());
2955 active_workers = workers()->update_active_workers(active_workers);
2956 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2957
2958 G1MonitoringScope ms(g1mm(),
2959 false /* full_gc */,
2960 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2961
2962 G1HeapTransition heap_transition(this);
2963 size_t heap_used_bytes_before_gc = used();
2964
2965 // Don't dynamically change the number of GC threads this early. A value of
2966 // 0 is used to indicate serial work. When parallel work is done,
2967 // it will be set.
2968
2969 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2970 IsGCActiveMark x;
2971
2972 gc_prologue(false);
2973
2974 if (VerifyRememberedSets) {
2975 log_info(gc, verify)("[Verifying RemSets before GC]");
2976 VerifyRegionRemSetClosure v_cl;
2977 heap_region_iterate(&v_cl);
2978 }
2979
2980 _verifier->verify_before_gc(verify_type);
2981
2982 _verifier->check_bitmaps("GC Start");
2983
2984 #if COMPILER2_OR_JVMCI
2985 DerivedPointerTable::clear();
2986 #endif
2987
2988 // Please see comment in g1CollectedHeap.hpp and
2989 // G1CollectedHeap::ref_processing_init() to see how
2990 // reference processing currently works in G1.
2991
2992 // Enable discovery in the STW reference processor
2993 _ref_processor_stw->enable_discovery();
2994
2995 {
2996 // We want to temporarily turn off discovery by the
2997 // CM ref processor, if necessary, and turn it back on
2998 // on again later if we do. Using a scoped
2999 // NoRefDiscovery object will do this.
3000 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3001
3002 // Forget the current alloc region (we might even choose it to be part
3003 // of the collection set!).
3004 _allocator->release_mutator_alloc_region();
3005
3006 // This timing is only used by the ergonomics to handle our pause target.
3007 // It is unclear why this should not include the full pause. We will
3008 // investigate this in CR 7178365.
3009 //
3010 // Preserving the old comment here if that helps the investigation:
3011 //
3012 // The elapsed time induced by the start time below deliberately elides
3013 // the possible verification above.
3014 double sample_start_time_sec = os::elapsedTime();
3015
3016 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3017
3018 if (collector_state()->in_initial_mark_gc()) {
3019 concurrent_mark()->pre_initial_mark();
3020 }
3021
3022 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3023
3024 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3025
3026 register_humongous_regions_with_cset();
3027
3028 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3029
3030 // We call this after finalize_cset() to
3031 // ensure that the CSet has been finalized.
3032 _cm->verify_no_cset_oops();
3033
3034 if (_hr_printer.is_active()) {
3035 G1PrintCollectionSetClosure cl(&_hr_printer);
3036 _collection_set.iterate(&cl);
3037 }
3038
3039 // Initialize the GC alloc regions.
3040 _allocator->init_gc_alloc_regions(evacuation_info);
3041
3042 G1ParScanThreadStateSet per_thread_states(this,
3043 workers()->active_workers(),
3044 collection_set()->young_region_length(),
3045 collection_set()->optional_region_length());
3046 pre_evacuate_collection_set();
3047
3048 // Actually do the work...
3049 evacuate_collection_set(&per_thread_states);
3050 evacuate_optional_collection_set(&per_thread_states);
3051
3052 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3053
3054 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3055 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3056
3057 eagerly_reclaim_humongous_regions();
3058
3059 record_obj_copy_mem_stats();
3060 _survivor_evac_stats.adjust_desired_plab_sz();
3061 _old_evac_stats.adjust_desired_plab_sz();
3062
3063 double start = os::elapsedTime();
3064 start_new_collection_set();
3065 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3066
3067 if (evacuation_failed()) {
3068 double recalculate_used_start = os::elapsedTime();
3069 set_used(recalculate_used());
3070 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3071
3072 if (_archive_allocator != NULL) {
3073 _archive_allocator->clear_used();
3074 }
3075 for (uint i = 0; i < ParallelGCThreads; i++) {
3076 if (_evacuation_failed_info_array[i].has_failed()) {
3077 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3078 }
3079 }
3080 } else {
3081 // The "used" of the the collection set have already been subtracted
3082 // when they were freed. Add in the bytes evacuated.
3083 increase_used(g1_policy()->bytes_copied_during_gc());
3084 }
3085
3086 if (collector_state()->in_initial_mark_gc()) {
3087 // We have to do this before we notify the CM threads that
3088 // they can start working to make sure that all the
3089 // appropriate initialization is done on the CM object.
3090 concurrent_mark()->post_initial_mark();
3091 // Note that we don't actually trigger the CM thread at
3092 // this point. We do that later when we're sure that
3093 // the current thread has completed its logging output.
3094 }
3095
3096 allocate_dummy_regions();
3097
3098 _allocator->init_mutator_alloc_region();
3099
3100 {
3101 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3102 if (expand_bytes > 0) {
3103 size_t bytes_before = capacity();
3104 // No need for an ergo logging here,
3105 // expansion_amount() does this when it returns a value > 0.
3106 double expand_ms;
3107 if (!expand(expand_bytes, _workers, &expand_ms)) {
3108 // We failed to expand the heap. Cannot do anything about it.
3109 }
3110 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3111 }
3112 }
3113
3114 // We redo the verification but now wrt to the new CSet which
3115 // has just got initialized after the previous CSet was freed.
3116 _cm->verify_no_cset_oops();
3117
3118 // This timing is only used by the ergonomics to handle our pause target.
3119 // It is unclear why this should not include the full pause. We will
3120 // investigate this in CR 7178365.
3121 double sample_end_time_sec = os::elapsedTime();
3122 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3123 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3124 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3125
3126 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3127 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3128
3129 if (VerifyRememberedSets) {
3130 log_info(gc, verify)("[Verifying RemSets after GC]");
3131 VerifyRegionRemSetClosure v_cl;
3132 heap_region_iterate(&v_cl);
3133 }
3134
3135 _verifier->verify_after_gc(verify_type);
3136 _verifier->check_bitmaps("GC End");
3137
3138 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3139 _ref_processor_stw->verify_no_references_recorded();
3140
3141 // CM reference discovery will be re-enabled if necessary.
3142 }
3143
3144 #ifdef TRACESPINNING
3145 ParallelTaskTerminator::print_termination_counts();
3146 #endif
3147
3148 gc_epilogue(false);
3149 }
3150
3151 // Print the remainder of the GC log output.
3152 if (evacuation_failed()) {
3153 log_info(gc)("To-space exhausted");
3154 }
3155
3156 g1_policy()->print_phases();
3157 heap_transition.print();
3158
3159 // It is not yet to safe to tell the concurrent mark to
3160 // start as we have some optional output below. We don't want the
3161 // output from the concurrent mark thread interfering with this
3162 // logging output either.
3163
3164 _hrm->verify_optional();
3165 _verifier->verify_region_sets_optional();
3166
3167 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3168 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3169
3170 print_heap_after_gc();
3171 print_heap_regions();
3172 trace_heap_after_gc(_gc_tracer_stw);
3173
3174 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3175 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3176 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3177 // before any GC notifications are raised.
3178 g1mm()->update_sizes();
3179
3180 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3181 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3182 _gc_timer_stw->register_gc_end();
3183 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3184 }
3185 // It should now be safe to tell the concurrent mark thread to start
3186 // without its logging output interfering with the logging output
3187 // that came from the pause.
3188
3189 if (should_start_conc_mark) {
3190 // CAUTION: after the doConcurrentMark() call below,
3191 // the concurrent marking thread(s) could be running
3192 // concurrently with us. Make sure that anything after
3193 // this point does not assume that we are the only GC thread
3194 // running. Note: of course, the actual marking work will
3195 // not start until the safepoint itself is released in
3196 // SuspendibleThreadSet::desynchronize().
3197 do_concurrent_mark();
3198 }
3199
3200 return true;
3201 }
3202
3203 void G1CollectedHeap::remove_self_forwarding_pointers() {
3204 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3205 workers()->run_task(&rsfp_task);
3206 }
3207
3208 void G1CollectedHeap::restore_after_evac_failure() {
3209 double remove_self_forwards_start = os::elapsedTime();
3210
3211 remove_self_forwarding_pointers();
3212 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3213 _preserved_marks_set.restore(&task_executor);
3214
3215 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3216 }
3217
3218 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3219 if (!_evacuation_failed) {
3220 _evacuation_failed = true;
3221 }
3222
3223 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3224 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3225 }
3226
3227 bool G1ParEvacuateFollowersClosure::offer_termination() {
3228 EventGCPhaseParallel event;
3229 G1ParScanThreadState* const pss = par_scan_state();
3230 start_term_time();
3231 const bool res = terminator()->offer_termination();
3232 end_term_time();
3233 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3234 return res;
3235 }
3236
3237 void G1ParEvacuateFollowersClosure::do_void() {
3238 EventGCPhaseParallel event;
3239 G1ParScanThreadState* const pss = par_scan_state();
3240 pss->trim_queue();
3241 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3242 do {
3243 EventGCPhaseParallel event;
3244 pss->steal_and_trim_queue(queues());
3245 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3246 } while (!offer_termination());
3247 }
3248
3249 class G1ParTask : public AbstractGangTask {
3250 protected:
3251 G1CollectedHeap* _g1h;
3252 G1ParScanThreadStateSet* _pss;
3253 RefToScanQueueSet* _queues;
3254 G1RootProcessor* _root_processor;
3255 TaskTerminator _terminator;
3256 uint _n_workers;
3257
3258 public:
3259 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3260 : AbstractGangTask("G1 collection"),
3261 _g1h(g1h),
3262 _pss(per_thread_states),
3263 _queues(task_queues),
3264 _root_processor(root_processor),
3265 _terminator(n_workers, _queues),
3266 _n_workers(n_workers)
3267 {}
3268
3269 void work(uint worker_id) {
3270 if (worker_id >= _n_workers) return; // no work needed this round
3271
3272 double start_sec = os::elapsedTime();
3273 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3274
3275 {
3276 ResourceMark rm;
3277 HandleMark hm;
3278
3279 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3280
3281 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3282 pss->set_ref_discoverer(rp);
3283
3284 double start_strong_roots_sec = os::elapsedTime();
3285
3286 _root_processor->evacuate_roots(pss, worker_id);
3287
3288 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3289 // treating the nmethods visited to act as roots for concurrent marking.
3290 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3291 // objects copied by the current evacuation.
3292 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3293
3294 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3295
3296 double term_sec = 0.0;
3297 size_t evac_term_attempts = 0;
3298 {
3299 double start = os::elapsedTime();
3300 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, _terminator.terminator(), G1GCPhaseTimes::ObjCopy);
3301 evac.do_void();
3302
3303 evac_term_attempts = evac.term_attempts();
3304 term_sec = evac.term_time();
3305 double elapsed_sec = os::elapsedTime() - start;
3306
3307 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3308 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3309 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3310 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3311 }
3312
3313 assert(pss->queue_is_empty(), "should be empty");
3314
3315 if (log_is_enabled(Debug, gc, task, stats)) {
3316 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3317 size_t lab_waste;
3318 size_t lab_undo_waste;
3319 pss->waste(lab_waste, lab_undo_waste);
3320 _g1h->print_termination_stats(worker_id,
3321 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3322 strong_roots_sec * 1000.0, /* strong roots time */
3323 term_sec * 1000.0, /* evac term time */
3324 evac_term_attempts, /* evac term attempts */
3325 lab_waste, /* alloc buffer waste */
3326 lab_undo_waste /* undo waste */
3327 );
3328 }
3329
3330 // Close the inner scope so that the ResourceMark and HandleMark
3331 // destructors are executed here and are included as part of the
3332 // "GC Worker Time".
3333 }
3334 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3335 }
3336 };
3337
3338 void G1CollectedHeap::print_termination_stats_hdr() {
3339 log_debug(gc, task, stats)("GC Termination Stats");
3340 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3341 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3342 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3343 }
3344
3345 void G1CollectedHeap::print_termination_stats(uint worker_id,
3346 double elapsed_ms,
3347 double strong_roots_ms,
3348 double term_ms,
3349 size_t term_attempts,
3350 size_t alloc_buffer_waste,
3351 size_t undo_waste) const {
3352 log_debug(gc, task, stats)
3353 ("%3d %9.2f %9.2f %6.2f "
3354 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3355 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3356 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3357 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3358 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3359 alloc_buffer_waste * HeapWordSize / K,
3360 undo_waste * HeapWordSize / K);
3361 }
3362
3363 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3364 bool class_unloading_occurred) {
3365 uint num_workers = workers()->active_workers();
3366 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3367 workers()->run_task(&unlink_task);
3368 }
3369
3370 // Clean string dedup data structures.
3371 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3372 // record the durations of the phases. Hence the almost-copy.
3373 class G1StringDedupCleaningTask : public AbstractGangTask {
3374 BoolObjectClosure* _is_alive;
3375 OopClosure* _keep_alive;
3376 G1GCPhaseTimes* _phase_times;
3377
3378 public:
3379 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3380 OopClosure* keep_alive,
3381 G1GCPhaseTimes* phase_times) :
3382 AbstractGangTask("Partial Cleaning Task"),
3383 _is_alive(is_alive),
3384 _keep_alive(keep_alive),
3385 _phase_times(phase_times)
3386 {
3387 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3388 StringDedup::gc_prologue(true);
3389 }
3390
3391 ~G1StringDedupCleaningTask() {
3392 StringDedup::gc_epilogue();
3393 }
3394
3395 void work(uint worker_id) {
3396 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3397 {
3398 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3399 StringDedupQueue::unlink_or_oops_do(&cl);
3400 }
3401 {
3402 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3403 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3404 }
3405 }
3406 };
3407
3408 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3409 OopClosure* keep_alive,
3410 G1GCPhaseTimes* phase_times) {
3411 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3412 workers()->run_task(&cl);
3413 }
3414
3415 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3416 private:
3417 DirtyCardQueueSet* _queue;
3418 G1CollectedHeap* _g1h;
3419 public:
3420 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3421 _queue(queue), _g1h(g1h) { }
3422
3423 virtual void work(uint worker_id) {
3424 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3425 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3426
3427 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3428 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3429
3430 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3431 }
3432 };
3433
3434 void G1CollectedHeap::redirty_logged_cards() {
3435 double redirty_logged_cards_start = os::elapsedTime();
3436
3437 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3438 dirty_card_queue_set().reset_for_par_iteration();
3439 workers()->run_task(&redirty_task);
3440
3441 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3442 dcq.merge_bufferlists(&dirty_card_queue_set());
3443 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3444
3445 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3446 }
3447
3448 // Weak Reference Processing support
3449
3450 bool G1STWIsAliveClosure::do_object_b(oop p) {
3451 // An object is reachable if it is outside the collection set,
3452 // or is inside and copied.
3453 return !_g1h->is_in_cset(p) || p->is_forwarded();
3454 }
3455
3456 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3457 assert(obj != NULL, "must not be NULL");
3458 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3459 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3460 // may falsely indicate that this is not the case here: however the collection set only
3461 // contains old regions when concurrent mark is not running.
3462 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3463 }
3464
3465 // Non Copying Keep Alive closure
3466 class G1KeepAliveClosure: public OopClosure {
3467 G1CollectedHeap*_g1h;
3468 public:
3469 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3470 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3471 void do_oop(oop* p) {
3472 oop obj = *p;
3473 assert(obj != NULL, "the caller should have filtered out NULL values");
3474
3475 const InCSetState cset_state =_g1h->in_cset_state(obj);
3476 if (!cset_state.is_in_cset_or_humongous()) {
3477 return;
3478 }
3479 if (cset_state.is_in_cset()) {
3480 assert( obj->is_forwarded(), "invariant" );
3481 *p = obj->forwardee();
3482 } else {
3483 assert(!obj->is_forwarded(), "invariant" );
3484 assert(cset_state.is_humongous(),
3485 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3486 _g1h->set_humongous_is_live(obj);
3487 }
3488 }
3489 };
3490
3491 // Copying Keep Alive closure - can be called from both
3492 // serial and parallel code as long as different worker
3493 // threads utilize different G1ParScanThreadState instances
3494 // and different queues.
3495
3496 class G1CopyingKeepAliveClosure: public OopClosure {
3497 G1CollectedHeap* _g1h;
3498 G1ParScanThreadState* _par_scan_state;
3499
3500 public:
3501 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3502 G1ParScanThreadState* pss):
3503 _g1h(g1h),
3504 _par_scan_state(pss)
3505 {}
3506
3507 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3508 virtual void do_oop( oop* p) { do_oop_work(p); }
3509
3510 template <class T> void do_oop_work(T* p) {
3511 oop obj = RawAccess<>::oop_load(p);
3512
3513 if (_g1h->is_in_cset_or_humongous(obj)) {
3514 // If the referent object has been forwarded (either copied
3515 // to a new location or to itself in the event of an
3516 // evacuation failure) then we need to update the reference
3517 // field and, if both reference and referent are in the G1
3518 // heap, update the RSet for the referent.
3519 //
3520 // If the referent has not been forwarded then we have to keep
3521 // it alive by policy. Therefore we have copy the referent.
3522 //
3523 // When the queue is drained (after each phase of reference processing)
3524 // the object and it's followers will be copied, the reference field set
3525 // to point to the new location, and the RSet updated.
3526 _par_scan_state->push_on_queue(p);
3527 }
3528 }
3529 };
3530
3531 // Serial drain queue closure. Called as the 'complete_gc'
3532 // closure for each discovered list in some of the
3533 // reference processing phases.
3534
3535 class G1STWDrainQueueClosure: public VoidClosure {
3536 protected:
3537 G1CollectedHeap* _g1h;
3538 G1ParScanThreadState* _par_scan_state;
3539
3540 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3541
3542 public:
3543 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3544 _g1h(g1h),
3545 _par_scan_state(pss)
3546 { }
3547
3548 void do_void() {
3549 G1ParScanThreadState* const pss = par_scan_state();
3550 pss->trim_queue();
3551 }
3552 };
3553
3554 // Parallel Reference Processing closures
3555
3556 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3557 // processing during G1 evacuation pauses.
3558
3559 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3560 private:
3561 G1CollectedHeap* _g1h;
3562 G1ParScanThreadStateSet* _pss;
3563 RefToScanQueueSet* _queues;
3564 WorkGang* _workers;
3565
3566 public:
3567 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3568 G1ParScanThreadStateSet* per_thread_states,
3569 WorkGang* workers,
3570 RefToScanQueueSet *task_queues) :
3571 _g1h(g1h),
3572 _pss(per_thread_states),
3573 _queues(task_queues),
3574 _workers(workers)
3575 {
3576 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3577 }
3578
3579 // Executes the given task using concurrent marking worker threads.
3580 virtual void execute(ProcessTask& task, uint ergo_workers);
3581 };
3582
3583 // Gang task for possibly parallel reference processing
3584
3585 class G1STWRefProcTaskProxy: public AbstractGangTask {
3586 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3587 ProcessTask& _proc_task;
3588 G1CollectedHeap* _g1h;
3589 G1ParScanThreadStateSet* _pss;
3590 RefToScanQueueSet* _task_queues;
3591 ParallelTaskTerminator* _terminator;
3592
3593 public:
3594 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3595 G1CollectedHeap* g1h,
3596 G1ParScanThreadStateSet* per_thread_states,
3597 RefToScanQueueSet *task_queues,
3598 ParallelTaskTerminator* terminator) :
3599 AbstractGangTask("Process reference objects in parallel"),
3600 _proc_task(proc_task),
3601 _g1h(g1h),
3602 _pss(per_thread_states),
3603 _task_queues(task_queues),
3604 _terminator(terminator)
3605 {}
3606
3607 virtual void work(uint worker_id) {
3608 // The reference processing task executed by a single worker.
3609 ResourceMark rm;
3610 HandleMark hm;
3611
3612 G1STWIsAliveClosure is_alive(_g1h);
3613
3614 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3615 pss->set_ref_discoverer(NULL);
3616
3617 // Keep alive closure.
3618 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3619
3620 // Complete GC closure
3621 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3622
3623 // Call the reference processing task's work routine.
3624 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3625
3626 // Note we cannot assert that the refs array is empty here as not all
3627 // of the processing tasks (specifically phase2 - pp2_work) execute
3628 // the complete_gc closure (which ordinarily would drain the queue) so
3629 // the queue may not be empty.
3630 }
3631 };
3632
3633 // Driver routine for parallel reference processing.
3634 // Creates an instance of the ref processing gang
3635 // task and has the worker threads execute it.
3636 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3637 assert(_workers != NULL, "Need parallel worker threads.");
3638
3639 assert(_workers->active_workers() >= ergo_workers,
3640 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3641 ergo_workers, _workers->active_workers());
3642 TaskTerminator terminator(ergo_workers, _queues);
3643 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3644
3645 _workers->run_task(&proc_task_proxy, ergo_workers);
3646 }
3647
3648 // End of weak reference support closures
3649
3650 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3651 double ref_proc_start = os::elapsedTime();
3652
3653 ReferenceProcessor* rp = _ref_processor_stw;
3654 assert(rp->discovery_enabled(), "should have been enabled");
3655
3656 // Closure to test whether a referent is alive.
3657 G1STWIsAliveClosure is_alive(this);
3658
3659 // Even when parallel reference processing is enabled, the processing
3660 // of JNI refs is serial and performed serially by the current thread
3661 // rather than by a worker. The following PSS will be used for processing
3662 // JNI refs.
3663
3664 // Use only a single queue for this PSS.
3665 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3666 pss->set_ref_discoverer(NULL);
3667 assert(pss->queue_is_empty(), "pre-condition");
3668
3669 // Keep alive closure.
3670 G1CopyingKeepAliveClosure keep_alive(this, pss);
3671
3672 // Serial Complete GC closure
3673 G1STWDrainQueueClosure drain_queue(this, pss);
3674
3675 // Setup the soft refs policy...
3676 rp->setup_policy(false);
3677
3678 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3679
3680 ReferenceProcessorStats stats;
3681 if (!rp->processing_is_mt()) {
3682 // Serial reference processing...
3683 stats = rp->process_discovered_references(&is_alive,
3684 &keep_alive,
3685 &drain_queue,
3686 NULL,
3687 pt);
3688 } else {
3689 uint no_of_gc_workers = workers()->active_workers();
3690
3691 // Parallel reference processing
3692 assert(no_of_gc_workers <= rp->max_num_queues(),
3693 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3694 no_of_gc_workers, rp->max_num_queues());
3695
3696 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3697 stats = rp->process_discovered_references(&is_alive,
3698 &keep_alive,
3699 &drain_queue,
3700 &par_task_executor,
3701 pt);
3702 }
3703
3704 _gc_tracer_stw->report_gc_reference_stats(stats);
3705
3706 // We have completed copying any necessary live referent objects.
3707 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3708
3709 make_pending_list_reachable();
3710
3711 rp->verify_no_references_recorded();
3712
3713 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3714 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3715 }
3716
3717 void G1CollectedHeap::make_pending_list_reachable() {
3718 if (collector_state()->in_initial_mark_gc()) {
3719 oop pll_head = Universe::reference_pending_list();
3720 if (pll_head != NULL) {
3721 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3722 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3723 }
3724 }
3725 }
3726
3727 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3728 double merge_pss_time_start = os::elapsedTime();
3729 per_thread_states->flush();
3730 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3731 }
3732
3733 void G1CollectedHeap::pre_evacuate_collection_set() {
3734 _expand_heap_after_alloc_failure = true;
3735 _evacuation_failed = false;
3736
3737 // Disable the hot card cache.
3738 _hot_card_cache->reset_hot_cache_claimed_index();
3739 _hot_card_cache->set_use_cache(false);
3740
3741 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3742 _preserved_marks_set.assert_empty();
3743
3744 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3745
3746 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3747 if (collector_state()->in_initial_mark_gc()) {
3748 double start_clear_claimed_marks = os::elapsedTime();
3749
3750 ClassLoaderDataGraph::clear_claimed_marks();
3751
3752 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3753 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3754 }
3755 }
3756
3757 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3758 // Should G1EvacuationFailureALot be in effect for this GC?
3759 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3760
3761 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3762
3763 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3764
3765 double start_par_time_sec = os::elapsedTime();
3766 double end_par_time_sec;
3767
3768 {
3769 const uint n_workers = workers()->active_workers();
3770 G1RootProcessor root_processor(this, n_workers);
3771 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3772
3773 print_termination_stats_hdr();
3774
3775 workers()->run_task(&g1_par_task);
3776 end_par_time_sec = os::elapsedTime();
3777
3778 // Closing the inner scope will execute the destructor
3779 // for the G1RootProcessor object. We record the current
3780 // elapsed time before closing the scope so that time
3781 // taken for the destructor is NOT included in the
3782 // reported parallel time.
3783 }
3784
3785 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3786 phase_times->record_par_time(par_time_ms);
3787
3788 double code_root_fixup_time_ms =
3789 (os::elapsedTime() - end_par_time_sec) * 1000.0;
3790 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3791 }
3792
3793 class G1EvacuateOptionalRegionTask : public AbstractGangTask {
3794 G1CollectedHeap* _g1h;
3795 G1ParScanThreadStateSet* _per_thread_states;
3796 G1OptionalCSet* _optional;
3797 RefToScanQueueSet* _queues;
3798 ParallelTaskTerminator _terminator;
3799
3800 Tickspan trim_ticks(G1ParScanThreadState* pss) {
3801 Tickspan copy_time = pss->trim_ticks();
3802 pss->reset_trim_ticks();
3803 return copy_time;
3804 }
3805
3806 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3807 G1EvacuationRootClosures* root_cls = pss->closures();
3808 G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss);
3809
3810 size_t scanned = 0;
3811 size_t claimed = 0;
3812 size_t skipped = 0;
3813 size_t used_memory = 0;
3814
3815 Ticks start = Ticks::now();
3816 Tickspan copy_time;
3817
3818 for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) {
3819 HeapRegion* hr = _optional->region_at(i);
3820 G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl);
3821 pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops());
3822 copy_time += trim_ticks(pss);
3823
3824 G1ScanRSForRegionClosure scan_rs_cl(_g1h->g1_rem_set()->scan_state(), &obj_cl, pss, G1GCPhaseTimes::OptScanRS, worker_id);
3825 scan_rs_cl.do_heap_region(hr);
3826 copy_time += trim_ticks(pss);
3827 scanned += scan_rs_cl.cards_scanned();
3828 claimed += scan_rs_cl.cards_claimed();
3829 skipped += scan_rs_cl.cards_skipped();
3830
3831 // Chunk lists for this region is no longer needed.
3832 used_memory += pss->oops_into_optional_region(hr)->used_memory();
3833 }
3834
3835 Tickspan scan_time = (Ticks::now() - start) - copy_time;
3836 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3837 p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds());
3838 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds());
3839
3840 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards);
3841 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards);
3842 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards);
3843 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, used_memory, G1GCPhaseTimes::OptCSetUsedMemory);
3844 }
3845
3846 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3847 Ticks start = Ticks::now();
3848 G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy);
3849 cl.do_void();
3850
3851 Tickspan evac_time = (Ticks::now() - start);
3852 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3853 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds());
3854 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation");
3855 }
3856
3857 public:
3858 G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h,
3859 G1ParScanThreadStateSet* per_thread_states,
3860 G1OptionalCSet* cset,
3861 RefToScanQueueSet* queues,
3862 uint n_workers) :
3863 AbstractGangTask("G1 Evacuation Optional Region Task"),
3864 _g1h(g1h),
3865 _per_thread_states(per_thread_states),
3866 _optional(cset),
3867 _queues(queues),
3868 _terminator(n_workers, _queues) {
3869 }
3870
3871 void work(uint worker_id) {
3872 ResourceMark rm;
3873 HandleMark hm;
3874
3875 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3876 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3877
3878 scan_roots(pss, worker_id);
3879 evacuate_live_objects(pss, worker_id);
3880 }
3881 };
3882
3883 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) {
3884 class G1MarkScope : public MarkScope {};
3885 G1MarkScope code_mark_scope;
3886
3887 G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers());
3888 workers()->run_task(&task);
3889 }
3890
3891 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3892 G1OptionalCSet optional_cset(&_collection_set, per_thread_states);
3893 if (optional_cset.is_empty()) {
3894 return;
3895 }
3896
3897 if (evacuation_failed()) {
3898 return;
3899 }
3900
3901 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3902 const double gc_start_time_ms = phase_times->cur_collection_start_sec() * 1000.0;
3903
3904 double start_time_sec = os::elapsedTime();
3905
3906 do {
3907 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3908 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3909
3910 if (time_left_ms < 0) {
3911 log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms);
3912 break;
3913 }
3914
3915 optional_cset.prepare_evacuation(time_left_ms * _g1_policy->optional_evacuation_fraction());
3916 if (optional_cset.prepare_failed()) {
3917 log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms);
3918 break;
3919 }
3920
3921 evacuate_optional_regions(per_thread_states, &optional_cset);
3922
3923 optional_cset.complete_evacuation();
3924 if (optional_cset.evacuation_failed()) {
3925 break;
3926 }
3927 } while (!optional_cset.is_empty());
3928
3929 phase_times->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0);
3930 }
3931
3932 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3933 // Also cleans the card table from temporary duplicate detection information used
3934 // during UpdateRS/ScanRS.
3935 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3936
3937 // Process any discovered reference objects - we have
3938 // to do this _before_ we retire the GC alloc regions
3939 // as we may have to copy some 'reachable' referent
3940 // objects (and their reachable sub-graphs) that were
3941 // not copied during the pause.
3942 process_discovered_references(per_thread_states);
3943
3944 G1STWIsAliveClosure is_alive(this);
3945 G1KeepAliveClosure keep_alive(this);
3946
3947 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3948 g1_policy()->phase_times()->weak_phase_times());
3949
3950 if (G1StringDedup::is_enabled()) {
3951 double string_dedup_time_ms = os::elapsedTime();
3952
3953 string_dedup_cleaning(&is_alive, &keep_alive, g1_policy()->phase_times());
3954
3955 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3956 g1_policy()->phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3957 }
3958
3959 if (evacuation_failed()) {
3960 restore_after_evac_failure();
3961
3962 // Reset the G1EvacuationFailureALot counters and flags
3963 // Note: the values are reset only when an actual
3964 // evacuation failure occurs.
3965 NOT_PRODUCT(reset_evacuation_should_fail();)
3966 }
3967
3968 _preserved_marks_set.assert_empty();
3969
3970 _allocator->release_gc_alloc_regions(evacuation_info);
3971
3972 merge_per_thread_state_info(per_thread_states);
3973
3974 // Reset and re-enable the hot card cache.
3975 // Note the counts for the cards in the regions in the
3976 // collection set are reset when the collection set is freed.
3977 _hot_card_cache->reset_hot_cache();
3978 _hot_card_cache->set_use_cache(true);
3979
3980 purge_code_root_memory();
3981
3982 redirty_logged_cards();
3983 #if COMPILER2_OR_JVMCI
3984 double start = os::elapsedTime();
3985 DerivedPointerTable::update_pointers();
3986 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3987 #endif
3988 g1_policy()->print_age_table();
3989 }
3990
3991 void G1CollectedHeap::record_obj_copy_mem_stats() {
3992 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3993
3994 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3995 create_g1_evac_summary(&_old_evac_stats));
3996 }
3997
3998 void G1CollectedHeap::free_region(HeapRegion* hr,
3999 FreeRegionList* free_list,
4000 bool skip_remset,
4001 bool skip_hot_card_cache,
4002 bool locked) {
4003 assert(!hr->is_free(), "the region should not be free");
4004 assert(!hr->is_empty(), "the region should not be empty");
4005 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4006 assert(free_list != NULL, "pre-condition");
4007
4008 if (G1VerifyBitmaps) {
4009 MemRegion mr(hr->bottom(), hr->end());
4010 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4011 }
4012
4013 // Clear the card counts for this region.
4014 // Note: we only need to do this if the region is not young
4015 // (since we don't refine cards in young regions).
4016 if (!skip_hot_card_cache && !hr->is_young()) {
4017 _hot_card_cache->reset_card_counts(hr);
4018 }
4019 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4020 _g1_policy->remset_tracker()->update_at_free(hr);
4021 free_list->add_ordered(hr);
4022 }
4023
4024 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4025 FreeRegionList* free_list) {
4026 assert(hr->is_humongous(), "this is only for humongous regions");
4027 assert(free_list != NULL, "pre-condition");
4028 hr->clear_humongous();
4029 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4030 }
4031
4032 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4033 const uint humongous_regions_removed) {
4034 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4035 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4036 _old_set.bulk_remove(old_regions_removed);
4037 _humongous_set.bulk_remove(humongous_regions_removed);
4038 }
4039
4040 }
4041
4042 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4043 assert(list != NULL, "list can't be null");
4044 if (!list->is_empty()) {
4045 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4046 _hrm->insert_list_into_free_list(list);
4047 }
4048 }
4049
4050 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4051 decrease_used(bytes);
4052 }
4053
4054 class G1FreeCollectionSetTask : public AbstractGangTask {
4055 private:
4056
4057 // Closure applied to all regions in the collection set to do work that needs to
4058 // be done serially in a single thread.
4059 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4060 private:
4061 G1EvacuationInfo* _evacuation_info;
4062 const size_t* _surviving_young_words;
4063
4064 // Bytes used in successfully evacuated regions before the evacuation.
4065 size_t _before_used_bytes;
4066 // Bytes used in unsucessfully evacuated regions before the evacuation
4067 size_t _after_used_bytes;
4068
4069 size_t _bytes_allocated_in_old_since_last_gc;
4070
4071 size_t _failure_used_words;
4072 size_t _failure_waste_words;
4073
4074 FreeRegionList _local_free_list;
4075 public:
4076 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4077 HeapRegionClosure(),
4078 _evacuation_info(evacuation_info),
4079 _surviving_young_words(surviving_young_words),
4080 _before_used_bytes(0),
4081 _after_used_bytes(0),
4082 _bytes_allocated_in_old_since_last_gc(0),
4083 _failure_used_words(0),
4084 _failure_waste_words(0),
4085 _local_free_list("Local Region List for CSet Freeing") {
4086 }
4087
4088 virtual bool do_heap_region(HeapRegion* r) {
4089 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4090
4091 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4092 g1h->clear_in_cset(r);
4093
4094 if (r->is_young()) {
4095 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4096 "Young index %d is wrong for region %u of type %s with %u young regions",
4097 r->young_index_in_cset(),
4098 r->hrm_index(),
4099 r->get_type_str(),
4100 g1h->collection_set()->young_region_length());
4101 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4102 r->record_surv_words_in_group(words_survived);
4103 }
4104
4105 if (!r->evacuation_failed()) {
4106 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4107 _before_used_bytes += r->used();
4108 g1h->free_region(r,
4109 &_local_free_list,
4110 true, /* skip_remset */
4111 true, /* skip_hot_card_cache */
4112 true /* locked */);
4113 } else {
4114 r->uninstall_surv_rate_group();
4115 r->set_young_index_in_cset(-1);
4116 r->set_evacuation_failed(false);
4117 // When moving a young gen region to old gen, we "allocate" that whole region
4118 // there. This is in addition to any already evacuated objects. Notify the
4119 // policy about that.
4120 // Old gen regions do not cause an additional allocation: both the objects
4121 // still in the region and the ones already moved are accounted for elsewhere.
4122 if (r->is_young()) {
4123 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4124 }
4125 // The region is now considered to be old.
4126 r->set_old();
4127 // Do some allocation statistics accounting. Regions that failed evacuation
4128 // are always made old, so there is no need to update anything in the young
4129 // gen statistics, but we need to update old gen statistics.
4130 size_t used_words = r->marked_bytes() / HeapWordSize;
4131
4132 _failure_used_words += used_words;
4133 _failure_waste_words += HeapRegion::GrainWords - used_words;
4134
4135 g1h->old_set_add(r);
4136 _after_used_bytes += r->used();
4137 }
4138 return false;
4139 }
4140
4141 void complete_work() {
4142 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4143
4144 _evacuation_info->set_regions_freed(_local_free_list.length());
4145 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4146
4147 g1h->prepend_to_freelist(&_local_free_list);
4148 g1h->decrement_summary_bytes(_before_used_bytes);
4149
4150 G1Policy* policy = g1h->g1_policy();
4151 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4152
4153 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4154 }
4155 };
4156
4157 G1CollectionSet* _collection_set;
4158 G1SerialFreeCollectionSetClosure _cl;
4159 const size_t* _surviving_young_words;
4160
4161 size_t _rs_lengths;
4162
4163 volatile jint _serial_work_claim;
4164
4165 struct WorkItem {
4166 uint region_idx;
4167 bool is_young;
4168 bool evacuation_failed;
4169
4170 WorkItem(HeapRegion* r) {
4171 region_idx = r->hrm_index();
4172 is_young = r->is_young();
4173 evacuation_failed = r->evacuation_failed();
4174 }
4175 };
4176
4177 volatile size_t _parallel_work_claim;
4178 size_t _num_work_items;
4179 WorkItem* _work_items;
4180
4181 void do_serial_work() {
4182 // Need to grab the lock to be allowed to modify the old region list.
4183 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4184 _collection_set->iterate(&_cl);
4185 }
4186
4187 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4188 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4189
4190 HeapRegion* r = g1h->region_at(region_idx);
4191 assert(!g1h->is_on_master_free_list(r), "sanity");
4192
4193 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4194
4195 if (!is_young) {
4196 g1h->_hot_card_cache->reset_card_counts(r);
4197 }
4198
4199 if (!evacuation_failed) {
4200 r->rem_set()->clear_locked();
4201 }
4202 }
4203
4204 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4205 private:
4206 size_t _cur_idx;
4207 WorkItem* _work_items;
4208 public:
4209 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4210
4211 virtual bool do_heap_region(HeapRegion* r) {
4212 _work_items[_cur_idx++] = WorkItem(r);
4213 return false;
4214 }
4215 };
4216
4217 void prepare_work() {
4218 G1PrepareFreeCollectionSetClosure cl(_work_items);
4219 _collection_set->iterate(&cl);
4220 }
4221
4222 void complete_work() {
4223 _cl.complete_work();
4224
4225 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4226 policy->record_max_rs_lengths(_rs_lengths);
4227 policy->cset_regions_freed();
4228 }
4229 public:
4230 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4231 AbstractGangTask("G1 Free Collection Set"),
4232 _collection_set(collection_set),
4233 _cl(evacuation_info, surviving_young_words),
4234 _surviving_young_words(surviving_young_words),
4235 _rs_lengths(0),
4236 _serial_work_claim(0),
4237 _parallel_work_claim(0),
4238 _num_work_items(collection_set->region_length()),
4239 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4240 prepare_work();
4241 }
4242
4243 ~G1FreeCollectionSetTask() {
4244 complete_work();
4245 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4246 }
4247
4248 // Chunk size for work distribution. The chosen value has been determined experimentally
4249 // to be a good tradeoff between overhead and achievable parallelism.
4250 static uint chunk_size() { return 32; }
4251
4252 virtual void work(uint worker_id) {
4253 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4254
4255 // Claim serial work.
4256 if (_serial_work_claim == 0) {
4257 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4258 if (value == 0) {
4259 double serial_time = os::elapsedTime();
4260 do_serial_work();
4261 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4262 }
4263 }
4264
4265 // Start parallel work.
4266 double young_time = 0.0;
4267 bool has_young_time = false;
4268 double non_young_time = 0.0;
4269 bool has_non_young_time = false;
4270
4271 while (true) {
4272 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4273 size_t cur = end - chunk_size();
4274
4275 if (cur >= _num_work_items) {
4276 break;
4277 }
4278
4279 EventGCPhaseParallel event;
4280 double start_time = os::elapsedTime();
4281
4282 end = MIN2(end, _num_work_items);
4283
4284 for (; cur < end; cur++) {
4285 bool is_young = _work_items[cur].is_young;
4286
4287 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4288
4289 double end_time = os::elapsedTime();
4290 double time_taken = end_time - start_time;
4291 if (is_young) {
4292 young_time += time_taken;
4293 has_young_time = true;
4294 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4295 } else {
4296 non_young_time += time_taken;
4297 has_non_young_time = true;
4298 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4299 }
4300 start_time = end_time;
4301 }
4302 }
4303
4304 if (has_young_time) {
4305 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4306 }
4307 if (has_non_young_time) {
4308 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4309 }
4310 }
4311 };
4312
4313 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4314 _eden.clear();
4315
4316 double free_cset_start_time = os::elapsedTime();
4317
4318 {
4319 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4320 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4321
4322 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4323
4324 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4325 cl.name(),
4326 num_workers,
4327 _collection_set.region_length());
4328 workers()->run_task(&cl, num_workers);
4329 }
4330 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4331
4332 collection_set->clear();
4333 }
4334
4335 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4336 private:
4337 FreeRegionList* _free_region_list;
4338 HeapRegionSet* _proxy_set;
4339 uint _humongous_objects_reclaimed;
4340 uint _humongous_regions_reclaimed;
4341 size_t _freed_bytes;
4342 public:
4343
4344 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4345 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4346 }
4347
4348 virtual bool do_heap_region(HeapRegion* r) {
4349 if (!r->is_starts_humongous()) {
4350 return false;
4351 }
4352
4353 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4354
4355 oop obj = (oop)r->bottom();
4356 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4357
4358 // The following checks whether the humongous object is live are sufficient.
4359 // The main additional check (in addition to having a reference from the roots
4360 // or the young gen) is whether the humongous object has a remembered set entry.
4361 //
4362 // A humongous object cannot be live if there is no remembered set for it
4363 // because:
4364 // - there can be no references from within humongous starts regions referencing
4365 // the object because we never allocate other objects into them.
4366 // (I.e. there are no intra-region references that may be missed by the
4367 // remembered set)
4368 // - as soon there is a remembered set entry to the humongous starts region
4369 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4370 // until the end of a concurrent mark.
4371 //
4372 // It is not required to check whether the object has been found dead by marking
4373 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4374 // all objects allocated during that time are considered live.
4375 // SATB marking is even more conservative than the remembered set.
4376 // So if at this point in the collection there is no remembered set entry,
4377 // nobody has a reference to it.
4378 // At the start of collection we flush all refinement logs, and remembered sets
4379 // are completely up-to-date wrt to references to the humongous object.
4380 //
4381 // Other implementation considerations:
4382 // - never consider object arrays at this time because they would pose
4383 // considerable effort for cleaning up the the remembered sets. This is
4384 // required because stale remembered sets might reference locations that
4385 // are currently allocated into.
4386 uint region_idx = r->hrm_index();
4387 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4388 !r->rem_set()->is_empty()) {
4389 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",
4390 region_idx,
4391 (size_t)obj->size() * HeapWordSize,
4392 p2i(r->bottom()),
4393 r->rem_set()->occupied(),
4394 r->rem_set()->strong_code_roots_list_length(),
4395 next_bitmap->is_marked(r->bottom()),
4396 g1h->is_humongous_reclaim_candidate(region_idx),
4397 obj->is_typeArray()
4398 );
4399 return false;
4400 }
4401
4402 guarantee(obj->is_typeArray(),
4403 "Only eagerly reclaiming type arrays is supported, but the object "
4404 PTR_FORMAT " is not.", p2i(r->bottom()));
4405
4406 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",
4407 region_idx,
4408 (size_t)obj->size() * HeapWordSize,
4409 p2i(r->bottom()),
4410 r->rem_set()->occupied(),
4411 r->rem_set()->strong_code_roots_list_length(),
4412 next_bitmap->is_marked(r->bottom()),
4413 g1h->is_humongous_reclaim_candidate(region_idx),
4414 obj->is_typeArray()
4415 );
4416
4417 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4418 cm->humongous_object_eagerly_reclaimed(r);
4419 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4420 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4421 region_idx,
4422 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4423 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4424 _humongous_objects_reclaimed++;
4425 do {
4426 HeapRegion* next = g1h->next_region_in_humongous(r);
4427 _freed_bytes += r->used();
4428 r->set_containing_set(NULL);
4429 _humongous_regions_reclaimed++;
4430 g1h->free_humongous_region(r, _free_region_list);
4431 r = next;
4432 } while (r != NULL);
4433
4434 return false;
4435 }
4436
4437 uint humongous_objects_reclaimed() {
4438 return _humongous_objects_reclaimed;
4439 }
4440
4441 uint humongous_regions_reclaimed() {
4442 return _humongous_regions_reclaimed;
4443 }
4444
4445 size_t bytes_freed() const {
4446 return _freed_bytes;
4447 }
4448 };
4449
4450 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4451 assert_at_safepoint_on_vm_thread();
4452
4453 if (!G1EagerReclaimHumongousObjects ||
4454 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4455 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4456 return;
4457 }
4458
4459 double start_time = os::elapsedTime();
4460
4461 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4462
4463 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4464 heap_region_iterate(&cl);
4465
4466 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4467
4468 G1HRPrinter* hrp = hr_printer();
4469 if (hrp->is_active()) {
4470 FreeRegionListIterator iter(&local_cleanup_list);
4471 while (iter.more_available()) {
4472 HeapRegion* hr = iter.get_next();
4473 hrp->cleanup(hr);
4474 }
4475 }
4476
4477 prepend_to_freelist(&local_cleanup_list);
4478 decrement_summary_bytes(cl.bytes_freed());
4479
4480 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4481 cl.humongous_objects_reclaimed());
4482 }
4483
4484 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4485 public:
4486 virtual bool do_heap_region(HeapRegion* r) {
4487 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4488 G1CollectedHeap::heap()->clear_in_cset(r);
4489 r->set_young_index_in_cset(-1);
4490 return false;
4491 }
4492 };
4493
4494 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4495 G1AbandonCollectionSetClosure cl;
4496 collection_set->iterate(&cl);
4497
4498 collection_set->clear();
4499 collection_set->stop_incremental_building();
4500 }
4501
4502 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4503 return _allocator->is_retained_old_region(hr);
4504 }
4505
4506 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4507 _eden.add(hr);
4508 _g1_policy->set_region_eden(hr);
4509 }
4510
4511 #ifdef ASSERT
4512
4513 class NoYoungRegionsClosure: public HeapRegionClosure {
4514 private:
4515 bool _success;
4516 public:
4517 NoYoungRegionsClosure() : _success(true) { }
4518 bool do_heap_region(HeapRegion* r) {
4519 if (r->is_young()) {
4520 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4521 p2i(r->bottom()), p2i(r->end()));
4522 _success = false;
4523 }
4524 return false;
4525 }
4526 bool success() { return _success; }
4527 };
4528
4529 bool G1CollectedHeap::check_young_list_empty() {
4530 bool ret = (young_regions_count() == 0);
4531
4532 NoYoungRegionsClosure closure;
4533 heap_region_iterate(&closure);
4534 ret = ret && closure.success();
4535
4536 return ret;
4537 }
4538
4539 #endif // ASSERT
4540
4541 class TearDownRegionSetsClosure : public HeapRegionClosure {
4542 HeapRegionSet *_old_set;
4543
4544 public:
4545 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4546
4547 bool do_heap_region(HeapRegion* r) {
4548 if (r->is_old()) {
4549 _old_set->remove(r);
4550 } else if(r->is_young()) {
4551 r->uninstall_surv_rate_group();
4552 } else {
4553 // We ignore free regions, we'll empty the free list afterwards.
4554 // We ignore humongous and archive regions, we're not tearing down these
4555 // sets.
4556 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4557 "it cannot be another type");
4558 }
4559 return false;
4560 }
4561
4562 ~TearDownRegionSetsClosure() {
4563 assert(_old_set->is_empty(), "post-condition");
4564 }
4565 };
4566
4567 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4568 assert_at_safepoint_on_vm_thread();
4569
4570 if (!free_list_only) {
4571 TearDownRegionSetsClosure cl(&_old_set);
4572 heap_region_iterate(&cl);
4573
4574 // Note that emptying the _young_list is postponed and instead done as
4575 // the first step when rebuilding the regions sets again. The reason for
4576 // this is that during a full GC string deduplication needs to know if
4577 // a collected region was young or old when the full GC was initiated.
4578 }
4579 _hrm->remove_all_free_regions();
4580 }
4581
4582 void G1CollectedHeap::increase_used(size_t bytes) {
4583 _summary_bytes_used += bytes;
4584 }
4585
4586 void G1CollectedHeap::decrease_used(size_t bytes) {
4587 assert(_summary_bytes_used >= bytes,
4588 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4589 _summary_bytes_used, bytes);
4590 _summary_bytes_used -= bytes;
4591 }
4592
4593 void G1CollectedHeap::set_used(size_t bytes) {
4594 _summary_bytes_used = bytes;
4595 }
4596
4597 class RebuildRegionSetsClosure : public HeapRegionClosure {
4598 private:
4599 bool _free_list_only;
4600
4601 HeapRegionSet* _old_set;
4602 HeapRegionManager* _hrm;
4603
4604 size_t _total_used;
4605
4606 public:
4607 RebuildRegionSetsClosure(bool free_list_only,
4608 HeapRegionSet* old_set,
4609 HeapRegionManager* hrm) :
4610 _free_list_only(free_list_only),
4611 _old_set(old_set), _hrm(hrm), _total_used(0) {
4612 assert(_hrm->num_free_regions() == 0, "pre-condition");
4613 if (!free_list_only) {
4614 assert(_old_set->is_empty(), "pre-condition");
4615 }
4616 }
4617
4618 bool do_heap_region(HeapRegion* r) {
4619 if (r->is_empty()) {
4620 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4621 // Add free regions to the free list
4622 r->set_free();
4623 _hrm->insert_into_free_list(r);
4624 } else if (!_free_list_only) {
4625 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4626
4627 if (r->is_archive() || r->is_humongous()) {
4628 // We ignore archive and humongous regions. We left these sets unchanged.
4629 } else {
4630 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4631 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4632 r->move_to_old();
4633 _old_set->add(r);
4634 }
4635 _total_used += r->used();
4636 }
4637
4638 return false;
4639 }
4640
4641 size_t total_used() {
4642 return _total_used;
4643 }
4644 };
4645
4646 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4647 assert_at_safepoint_on_vm_thread();
4648
4649 if (!free_list_only) {
4650 _eden.clear();
4651 _survivor.clear();
4652 }
4653
4654 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4655 heap_region_iterate(&cl);
4656
4657 if (!free_list_only) {
4658 set_used(cl.total_used());
4659 if (_archive_allocator != NULL) {
4660 _archive_allocator->clear_used();
4661 }
4662 }
4663 assert(used() == recalculate_used(),
4664 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4665 used(), recalculate_used());
4666 }
4667
4668 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4669 HeapRegion* hr = heap_region_containing(p);
4670 return hr->is_in(p);
4671 }
4672
4673 // Methods for the mutator alloc region
4674
4675 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4676 bool force) {
4677 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4678 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4679 if (force || should_allocate) {
4680 HeapRegion* new_alloc_region = new_region(word_size,
4681 HeapRegionType::Eden,
4682 false /* do_expand */);
4683 if (new_alloc_region != NULL) {
4684 set_region_short_lived_locked(new_alloc_region);
4685 _hr_printer.alloc(new_alloc_region, !should_allocate);
4686 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4687 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4688 return new_alloc_region;
4689 }
4690 }
4691 return NULL;
4692 }
4693
4694 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4695 size_t allocated_bytes) {
4696 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4697 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4698
4699 collection_set()->add_eden_region(alloc_region);
4700 increase_used(allocated_bytes);
4701 _hr_printer.retire(alloc_region);
4702 // We update the eden sizes here, when the region is retired,
4703 // instead of when it's allocated, since this is the point that its
4704 // used space has been recorded in _summary_bytes_used.
4705 g1mm()->update_eden_size();
4706 }
4707
4708 // Methods for the GC alloc regions
4709
4710 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4711 if (dest.is_old()) {
4712 return true;
4713 } else {
4714 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4715 }
4716 }
4717
4718 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4719 assert(FreeList_lock->owned_by_self(), "pre-condition");
4720
4721 if (!has_more_regions(dest)) {
4722 return NULL;
4723 }
4724
4725 HeapRegionType type;
4726 if (dest.is_young()) {
4727 type = HeapRegionType::Survivor;
4728 } else {
4729 type = HeapRegionType::Old;
4730 }
4731
4732 HeapRegion* new_alloc_region = new_region(word_size,
4733 type,
4734 true /* do_expand */);
4735
4736 if (new_alloc_region != NULL) {
4737 if (type.is_survivor()) {
4738 new_alloc_region->set_survivor();
4739 _survivor.add(new_alloc_region);
4740 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4741 } else {
4742 new_alloc_region->set_old();
4743 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4744 }
4745 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4746 _hr_printer.alloc(new_alloc_region);
4747 return new_alloc_region;
4748 }
4749 return NULL;
4750 }
4751
4752 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4753 size_t allocated_bytes,
4754 InCSetState dest) {
4755 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4756 if (dest.is_old()) {
4757 old_set_add(alloc_region);
4758 }
4759
4760 bool const during_im = collector_state()->in_initial_mark_gc();
4761 if (during_im && allocated_bytes > 0) {
4762 _cm->root_regions()->add(alloc_region);
4763 }
4764 _hr_printer.retire(alloc_region);
4765 }
4766
4767 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4768 bool expanded = false;
4769 uint index = _hrm->find_highest_free(&expanded);
4770
4771 if (index != G1_NO_HRM_INDEX) {
4772 if (expanded) {
4773 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4774 HeapRegion::GrainWords * HeapWordSize);
4775 }
4776 _hrm->allocate_free_regions_starting_at(index, 1);
4777 return region_at(index);
4778 }
4779 return NULL;
4780 }
4781
4782 // Optimized nmethod scanning
4783
4784 class RegisterNMethodOopClosure: public OopClosure {
4785 G1CollectedHeap* _g1h;
4786 nmethod* _nm;
4787
4788 template <class T> void do_oop_work(T* p) {
4789 T heap_oop = RawAccess<>::oop_load(p);
4790 if (!CompressedOops::is_null(heap_oop)) {
4791 oop obj = CompressedOops::decode_not_null(heap_oop);
4792 HeapRegion* hr = _g1h->heap_region_containing(obj);
4793 assert(!hr->is_continues_humongous(),
4794 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4795 " starting at " HR_FORMAT,
4796 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4797
4798 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4799 hr->add_strong_code_root_locked(_nm);
4800 }
4801 }
4802
4803 public:
4804 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4805 _g1h(g1h), _nm(nm) {}
4806
4807 void do_oop(oop* p) { do_oop_work(p); }
4808 void do_oop(narrowOop* p) { do_oop_work(p); }
4809 };
4810
4811 class UnregisterNMethodOopClosure: public OopClosure {
4812 G1CollectedHeap* _g1h;
4813 nmethod* _nm;
4814
4815 template <class T> void do_oop_work(T* p) {
4816 T heap_oop = RawAccess<>::oop_load(p);
4817 if (!CompressedOops::is_null(heap_oop)) {
4818 oop obj = CompressedOops::decode_not_null(heap_oop);
4819 HeapRegion* hr = _g1h->heap_region_containing(obj);
4820 assert(!hr->is_continues_humongous(),
4821 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4822 " starting at " HR_FORMAT,
4823 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4824
4825 hr->remove_strong_code_root(_nm);
4826 }
4827 }
4828
4829 public:
4830 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4831 _g1h(g1h), _nm(nm) {}
4832
4833 void do_oop(oop* p) { do_oop_work(p); }
4834 void do_oop(narrowOop* p) { do_oop_work(p); }
4835 };
4836
4837 // Returns true if the reference points to an object that
4838 // can move in an incremental collection.
4839 bool G1CollectedHeap::is_scavengable(oop obj) {
4840 HeapRegion* hr = heap_region_containing(obj);
4841 return !hr->is_pinned();
4842 }
4843
4844 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4845 guarantee(nm != NULL, "sanity");
4846 RegisterNMethodOopClosure reg_cl(this, nm);
4847 nm->oops_do(®_cl);
4848 }
4849
4850 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4851 guarantee(nm != NULL, "sanity");
4852 UnregisterNMethodOopClosure reg_cl(this, nm);
4853 nm->oops_do(®_cl, true);
4854 }
4855
4856 void G1CollectedHeap::purge_code_root_memory() {
4857 double purge_start = os::elapsedTime();
4858 G1CodeRootSet::purge();
4859 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4860 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4861 }
4862
4863 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4864 G1CollectedHeap* _g1h;
4865
4866 public:
4867 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4868 _g1h(g1h) {}
4869
4870 void do_code_blob(CodeBlob* cb) {
4871 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4872 if (nm == NULL) {
4873 return;
4874 }
4875
4876 if (ScavengeRootsInCode) {
4877 _g1h->register_nmethod(nm);
4878 }
4879 }
4880 };
4881
4882 void G1CollectedHeap::rebuild_strong_code_roots() {
4883 RebuildStrongCodeRootClosure blob_cl(this);
4884 CodeCache::blobs_do(&blob_cl);
4885 }
4886
4887 void G1CollectedHeap::initialize_serviceability() {
4888 _g1mm->initialize_serviceability();
4889 }
4890
4891 MemoryUsage G1CollectedHeap::memory_usage() {
4892 return _g1mm->memory_usage();
4893 }
4894
4895 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4896 return _g1mm->memory_managers();
4897 }
4898
4899 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4900 return _g1mm->memory_pools();
4901 }