1 /*
2 * Copyright (c) 2001, 2020, 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/g1Arguments.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1CardTableEntryClosure.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1DirtyCardQueue.hpp"
42 #include "gc/g1/g1EvacStats.inline.hpp"
43 #include "gc/g1/g1FullCollector.hpp"
44 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
45 #include "gc/g1/g1GCPhaseTimes.hpp"
46 #include "gc/g1/g1HeapSizingPolicy.hpp"
47 #include "gc/g1/g1HeapTransition.hpp"
48 #include "gc/g1/g1HeapVerifier.hpp"
49 #include "gc/g1/g1HotCardCache.hpp"
50 #include "gc/g1/g1MemoryPool.hpp"
51 #include "gc/g1/g1OopClosures.inline.hpp"
52 #include "gc/g1/g1ParallelCleaning.hpp"
53 #include "gc/g1/g1ParScanThreadState.inline.hpp"
54 #include "gc/g1/g1Policy.hpp"
55 #include "gc/g1/g1RedirtyCardsQueue.hpp"
56 #include "gc/g1/g1RegionToSpaceMapper.hpp"
57 #include "gc/g1/g1RemSet.hpp"
58 #include "gc/g1/g1RootClosures.hpp"
59 #include "gc/g1/g1RootProcessor.hpp"
60 #include "gc/g1/g1SATBMarkQueueSet.hpp"
61 #include "gc/g1/g1StringDedup.hpp"
62 #include "gc/g1/g1ThreadLocalData.hpp"
63 #include "gc/g1/g1Trace.hpp"
64 #include "gc/g1/g1YCTypes.hpp"
65 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
66 #include "gc/g1/g1VMOperations.hpp"
67 #include "gc/g1/heapRegion.inline.hpp"
68 #include "gc/g1/heapRegionRemSet.hpp"
69 #include "gc/g1/heapRegionSet.inline.hpp"
70 #include "gc/shared/concurrentGCBreakpoints.hpp"
71 #include "gc/shared/gcBehaviours.hpp"
72 #include "gc/shared/gcHeapSummary.hpp"
73 #include "gc/shared/gcId.hpp"
74 #include "gc/shared/gcLocker.hpp"
75 #include "gc/shared/gcTimer.hpp"
76 #include "gc/shared/gcTraceTime.inline.hpp"
77 #include "gc/shared/generationSpec.hpp"
78 #include "gc/shared/isGCActiveMark.hpp"
79 #include "gc/shared/locationPrinter.inline.hpp"
80 #include "gc/shared/oopStorageParState.hpp"
81 #include "gc/shared/preservedMarks.inline.hpp"
82 #include "gc/shared/suspendibleThreadSet.hpp"
83 #include "gc/shared/referenceProcessor.inline.hpp"
84 #include "gc/shared/taskTerminator.hpp"
85 #include "gc/shared/taskqueue.inline.hpp"
86 #include "gc/shared/weakProcessor.inline.hpp"
87 #include "gc/shared/workerPolicy.hpp"
88 #include "logging/log.hpp"
89 #include "memory/allocation.hpp"
90 #include "memory/iterator.hpp"
91 #include "memory/resourceArea.hpp"
92 #include "memory/universe.hpp"
93 #include "oops/access.inline.hpp"
94 #include "oops/compressedOops.inline.hpp"
95 #include "oops/oop.inline.hpp"
96 #include "runtime/atomic.hpp"
97 #include "runtime/flags/flagSetting.hpp"
98 #include "runtime/handles.inline.hpp"
99 #include "runtime/init.hpp"
100 #include "runtime/orderAccess.hpp"
101 #include "runtime/threadSMR.hpp"
102 #include "runtime/vmThread.hpp"
103 #include "utilities/align.hpp"
104 #include "utilities/bitMap.inline.hpp"
105 #include "utilities/globalDefinitions.hpp"
106 #include "utilities/stack.inline.hpp"
107
108 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
109
110 // INVARIANTS/NOTES
111 //
112 // All allocation activity covered by the G1CollectedHeap interface is
113 // serialized by acquiring the HeapLock. This happens in mem_allocate
114 // and allocate_new_tlab, which are the "entry" points to the
115 // allocation code from the rest of the JVM. (Note that this does not
116 // apply to TLAB allocation, which is not part of this interface: it
117 // is done by clients of this interface.)
118
119 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
120 private:
121 size_t _num_dirtied;
122 G1CollectedHeap* _g1h;
123 G1CardTable* _g1_ct;
124
125 HeapRegion* region_for_card(CardValue* card_ptr) const {
126 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
127 }
128
129 bool will_become_free(HeapRegion* hr) const {
130 // A region will be freed by free_collection_set if the region is in the
131 // collection set and has not had an evacuation failure.
132 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
133 }
134
135 public:
136 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
137 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
138
139 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
140 HeapRegion* hr = region_for_card(card_ptr);
141
142 // Should only dirty cards in regions that won't be freed.
143 if (!will_become_free(hr)) {
144 *card_ptr = G1CardTable::dirty_card_val();
145 _num_dirtied++;
146 }
147 }
148
149 size_t num_dirtied() const { return _num_dirtied; }
150 };
151
152
153 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
154 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
155 }
156
157 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
158 // The from card cache is not the memory that is actually committed. So we cannot
159 // take advantage of the zero_filled parameter.
160 reset_from_card_cache(start_idx, num_regions);
161 }
162
163 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
164 Ticks start = Ticks::now();
165 workers()->run_task(task, workers()->active_workers());
166 return Ticks::now() - start;
167 }
168
169 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
170 MemRegion mr) {
171 return new HeapRegion(hrs_index, bot(), mr);
172 }
173
174 // Private methods.
175
176 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
177 HeapRegionType type,
178 bool do_expand,
179 uint node_index) {
180 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
181 "the only time we use this to allocate a humongous region is "
182 "when we are allocating a single humongous region");
183
184 HeapRegion* res = _hrm->allocate_free_region(type, node_index);
185
186 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
187 // Currently, only attempts to allocate GC alloc regions set
188 // do_expand to true. So, we should only reach here during a
189 // safepoint. If this assumption changes we might have to
190 // reconsider the use of _expand_heap_after_alloc_failure.
191 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
192
193 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
194 word_size * HeapWordSize);
195
196 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
197 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
198 word_size * HeapWordSize);
199 if (expand_single_region(node_index)) {
200 // Given that expand_single_region() succeeded in expanding the heap, and we
201 // always expand the heap by an amount aligned to the heap
202 // region size, the free list should in theory not be empty.
203 // In either case allocate_free_region() will check for NULL.
204 res = _hrm->allocate_free_region(type, node_index);
205 } else {
206 _expand_heap_after_alloc_failure = false;
207 }
208 }
209 return res;
210 }
211
212 HeapWord*
213 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
214 uint num_regions,
215 size_t word_size) {
216 assert(first_hr != NULL, "pre-condition");
217 assert(is_humongous(word_size), "word_size should be humongous");
218 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
219
220 // Index of last region in the series.
221 uint first = first_hr->hrm_index();
222 uint last = first + num_regions - 1;
223
224 // We need to initialize the region(s) we just discovered. This is
225 // a bit tricky given that it can happen concurrently with
226 // refinement threads refining cards on these regions and
227 // potentially wanting to refine the BOT as they are scanning
228 // those cards (this can happen shortly after a cleanup; see CR
229 // 6991377). So we have to set up the region(s) carefully and in
230 // a specific order.
231
232 // The word size sum of all the regions we will allocate.
233 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
234 assert(word_size <= word_size_sum, "sanity");
235
236 // The passed in hr will be the "starts humongous" region. The header
237 // of the new object will be placed at the bottom of this region.
238 HeapWord* new_obj = first_hr->bottom();
239 // This will be the new top of the new object.
240 HeapWord* obj_top = new_obj + word_size;
241
242 // First, we need to zero the header of the space that we will be
243 // allocating. When we update top further down, some refinement
244 // threads might try to scan the region. By zeroing the header we
245 // ensure that any thread that will try to scan the region will
246 // come across the zero klass word and bail out.
247 //
248 // NOTE: It would not have been correct to have used
249 // CollectedHeap::fill_with_object() and make the space look like
250 // an int array. The thread that is doing the allocation will
251 // later update the object header to a potentially different array
252 // type and, for a very short period of time, the klass and length
253 // fields will be inconsistent. This could cause a refinement
254 // thread to calculate the object size incorrectly.
255 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
256
257 // Next, pad out the unused tail of the last region with filler
258 // objects, for improved usage accounting.
259 // How many words we use for filler objects.
260 size_t word_fill_size = word_size_sum - word_size;
261
262 // How many words memory we "waste" which cannot hold a filler object.
263 size_t words_not_fillable = 0;
264
265 if (word_fill_size >= min_fill_size()) {
266 fill_with_objects(obj_top, word_fill_size);
267 } else if (word_fill_size > 0) {
268 // We have space to fill, but we cannot fit an object there.
269 words_not_fillable = word_fill_size;
270 word_fill_size = 0;
271 }
272
273 // We will set up the first region as "starts humongous". This
274 // will also update the BOT covering all the regions to reflect
275 // that there is a single object that starts at the bottom of the
276 // first region.
277 first_hr->set_starts_humongous(obj_top, word_fill_size);
278 _policy->remset_tracker()->update_at_allocate(first_hr);
279 // Then, if there are any, we will set up the "continues
280 // humongous" regions.
281 HeapRegion* hr = NULL;
282 for (uint i = first + 1; i <= last; ++i) {
283 hr = region_at(i);
284 hr->set_continues_humongous(first_hr);
285 _policy->remset_tracker()->update_at_allocate(hr);
286 }
287
288 // Up to this point no concurrent thread would have been able to
289 // do any scanning on any region in this series. All the top
290 // fields still point to bottom, so the intersection between
291 // [bottom,top] and [card_start,card_end] will be empty. Before we
292 // update the top fields, we'll do a storestore to make sure that
293 // no thread sees the update to top before the zeroing of the
294 // object header and the BOT initialization.
295 OrderAccess::storestore();
296
297 // Now, we will update the top fields of the "continues humongous"
298 // regions except the last one.
299 for (uint i = first; i < last; ++i) {
300 hr = region_at(i);
301 hr->set_top(hr->end());
302 }
303
304 hr = region_at(last);
305 // If we cannot fit a filler object, we must set top to the end
306 // of the humongous object, otherwise we cannot iterate the heap
307 // and the BOT will not be complete.
308 hr->set_top(hr->end() - words_not_fillable);
309
310 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
311 "obj_top should be in last region");
312
313 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
314
315 assert(words_not_fillable == 0 ||
316 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
317 "Miscalculation in humongous allocation");
318
319 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
320
321 for (uint i = first; i <= last; ++i) {
322 hr = region_at(i);
323 _humongous_set.add(hr);
324 _hr_printer.alloc(hr);
325 }
326
327 return new_obj;
328 }
329
330 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
331 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
332 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
333 }
334
335 // If could fit into free regions w/o expansion, try.
336 // Otherwise, if can expand, do so.
337 // Otherwise, if using ex regions might help, try with ex given back.
338 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
339 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
340
341 _verifier->verify_region_sets_optional();
342
343 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
344
345 // Policy: First try to allocate a humongous object in the free list.
346 HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions);
347 if (humongous_start == NULL) {
348 // Policy: We could not find enough regions for the humongous object in the
349 // free list. Look through the heap to find a mix of free and uncommitted regions.
350 // If so, expand the heap and allocate the humongous object.
351 humongous_start = _hrm->expand_and_allocate_humongous(obj_regions);
352 if (humongous_start != NULL) {
353 // We managed to find a region by expanding the heap.
354 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
355 word_size * HeapWordSize);
356 policy()->record_new_heap_size(num_regions());
357 } else {
358 // Policy: Potentially trigger a defragmentation GC.
359 }
360 }
361
362 HeapWord* result = NULL;
363 if (humongous_start != NULL) {
364 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
365 assert(result != NULL, "it should always return a valid result");
366
367 // A successful humongous object allocation changes the used space
368 // information of the old generation so we need to recalculate the
369 // sizes and update the jstat counters here.
370 g1mm()->update_sizes();
371 }
372
373 _verifier->verify_region_sets_optional();
374
375 return result;
376 }
377
378 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
379 size_t requested_size,
380 size_t* actual_size) {
381 assert_heap_not_locked_and_not_at_safepoint();
382 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
383
384 return attempt_allocation(min_size, requested_size, actual_size);
385 }
386
387 HeapWord*
388 G1CollectedHeap::mem_allocate(size_t word_size,
389 bool* gc_overhead_limit_was_exceeded) {
390 assert_heap_not_locked_and_not_at_safepoint();
391
392 if (is_humongous(word_size)) {
393 return attempt_allocation_humongous(word_size);
394 }
395 size_t dummy = 0;
396 return attempt_allocation(word_size, word_size, &dummy);
397 }
398
399 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
400 ResourceMark rm; // For retrieving the thread names in log messages.
401
402 // Make sure you read the note in attempt_allocation_humongous().
403
404 assert_heap_not_locked_and_not_at_safepoint();
405 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
406 "be called for humongous allocation requests");
407
408 // We should only get here after the first-level allocation attempt
409 // (attempt_allocation()) failed to allocate.
410
411 // We will loop until a) we manage to successfully perform the
412 // allocation or b) we successfully schedule a collection which
413 // fails to perform the allocation. b) is the only case when we'll
414 // return NULL.
415 HeapWord* result = NULL;
416 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
417 bool should_try_gc;
418 uint gc_count_before;
419
420 {
421 MutexLocker x(Heap_lock);
422 result = _allocator->attempt_allocation_locked(word_size);
423 if (result != NULL) {
424 return result;
425 }
426
427 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
428 // This is different to when only GCLocker::needs_gc() is set: try to avoid
429 // waiting because the GCLocker is active to not wait too long.
430 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
431 // No need for an ergo message here, can_expand_young_list() does this when
432 // it returns true.
433 result = _allocator->attempt_allocation_force(word_size);
434 if (result != NULL) {
435 return result;
436 }
437 }
438 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
439 // the GCLocker initiated GC has been performed and then retry. This includes
440 // the case when the GC Locker is not active but has not been performed.
441 should_try_gc = !GCLocker::needs_gc();
442 // Read the GC count while still holding the Heap_lock.
443 gc_count_before = total_collections();
444 }
445
446 if (should_try_gc) {
447 bool succeeded;
448 result = do_collection_pause(word_size, gc_count_before, &succeeded,
449 GCCause::_g1_inc_collection_pause);
450 if (result != NULL) {
451 assert(succeeded, "only way to get back a non-NULL result");
452 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
453 Thread::current()->name(), p2i(result));
454 return result;
455 }
456
457 if (succeeded) {
458 // We successfully scheduled a collection which failed to allocate. No
459 // point in trying to allocate further. We'll just return NULL.
460 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
461 SIZE_FORMAT " words", Thread::current()->name(), word_size);
462 return NULL;
463 }
464 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
465 Thread::current()->name(), word_size);
466 } else {
467 // Failed to schedule a collection.
468 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
469 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
470 SIZE_FORMAT " words", Thread::current()->name(), word_size);
471 return NULL;
472 }
473 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
474 // The GCLocker is either active or the GCLocker initiated
475 // GC has not yet been performed. Stall until it is and
476 // then retry the allocation.
477 GCLocker::stall_until_clear();
478 gclocker_retry_count += 1;
479 }
480
481 // We can reach here if we were unsuccessful in scheduling a
482 // collection (because another thread beat us to it) or if we were
483 // stalled due to the GC locker. In either can we should retry the
484 // allocation attempt in case another thread successfully
485 // performed a collection and reclaimed enough space. We do the
486 // first attempt (without holding the Heap_lock) here and the
487 // follow-on attempt will be at the start of the next loop
488 // iteration (after taking the Heap_lock).
489 size_t dummy = 0;
490 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
491 if (result != NULL) {
492 return result;
493 }
494
495 // Give a warning if we seem to be looping forever.
496 if ((QueuedAllocationWarningCount > 0) &&
497 (try_count % QueuedAllocationWarningCount == 0)) {
498 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
499 Thread::current()->name(), try_count, word_size);
500 }
501 }
502
503 ShouldNotReachHere();
504 return NULL;
505 }
506
507 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
508 assert_at_safepoint_on_vm_thread();
509 if (_archive_allocator == NULL) {
510 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
511 }
512 }
513
514 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
515 // Allocations in archive regions cannot be of a size that would be considered
516 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
517 // may be different at archive-restore time.
518 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
519 }
520
521 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
522 assert_at_safepoint_on_vm_thread();
523 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
524 if (is_archive_alloc_too_large(word_size)) {
525 return NULL;
526 }
527 return _archive_allocator->archive_mem_allocate(word_size);
528 }
529
530 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
531 size_t end_alignment_in_bytes) {
532 assert_at_safepoint_on_vm_thread();
533 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
534
535 // Call complete_archive to do the real work, filling in the MemRegion
536 // array with the archive regions.
537 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
538 delete _archive_allocator;
539 _archive_allocator = NULL;
540 }
541
542 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
543 assert(ranges != NULL, "MemRegion array NULL");
544 assert(count != 0, "No MemRegions provided");
545 MemRegion reserved = _hrm->reserved();
546 for (size_t i = 0; i < count; i++) {
547 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
548 return false;
549 }
550 }
551 return true;
552 }
553
554 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
555 size_t count,
556 bool open) {
557 assert(!is_init_completed(), "Expect to be called at JVM init time");
558 assert(ranges != NULL, "MemRegion array NULL");
559 assert(count != 0, "No MemRegions provided");
560 MutexLocker x(Heap_lock);
561
562 MemRegion reserved = _hrm->reserved();
563 HeapWord* prev_last_addr = NULL;
564 HeapRegion* prev_last_region = NULL;
565
566 // Temporarily disable pretouching of heap pages. This interface is used
567 // when mmap'ing archived heap data in, so pre-touching is wasted.
568 FlagSetting fs(AlwaysPreTouch, false);
569
570 // Enable archive object checking used by G1MarkSweep. We have to let it know
571 // about each archive range, so that objects in those ranges aren't marked.
572 G1ArchiveAllocator::enable_archive_object_check();
573
574 // For each specified MemRegion range, allocate the corresponding G1
575 // regions and mark them as archive regions. We expect the ranges
576 // in ascending starting address order, without overlap.
577 for (size_t i = 0; i < count; i++) {
578 MemRegion curr_range = ranges[i];
579 HeapWord* start_address = curr_range.start();
580 size_t word_size = curr_range.word_size();
581 HeapWord* last_address = curr_range.last();
582 size_t commits = 0;
583
584 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
585 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
586 p2i(start_address), p2i(last_address));
587 guarantee(start_address > prev_last_addr,
588 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
589 p2i(start_address), p2i(prev_last_addr));
590 prev_last_addr = last_address;
591
592 // Check for ranges that start in the same G1 region in which the previous
593 // range ended, and adjust the start address so we don't try to allocate
594 // the same region again. If the current range is entirely within that
595 // region, skip it, just adjusting the recorded top.
596 HeapRegion* start_region = _hrm->addr_to_region(start_address);
597 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
598 start_address = start_region->end();
599 if (start_address > last_address) {
600 increase_used(word_size * HeapWordSize);
601 start_region->set_top(last_address + 1);
602 continue;
603 }
604 start_region->set_top(start_address);
605 curr_range = MemRegion(start_address, last_address + 1);
606 start_region = _hrm->addr_to_region(start_address);
607 }
608
609 // Perform the actual region allocation, exiting if it fails.
610 // Then note how much new space we have allocated.
611 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
612 return false;
613 }
614 increase_used(word_size * HeapWordSize);
615 if (commits != 0) {
616 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
617 HeapRegion::GrainWords * HeapWordSize * commits);
618
619 }
620
621 // Mark each G1 region touched by the range as archive, add it to
622 // the old set, and set top.
623 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
624 HeapRegion* last_region = _hrm->addr_to_region(last_address);
625 prev_last_region = last_region;
626
627 while (curr_region != NULL) {
628 assert(curr_region->is_empty() && !curr_region->is_pinned(),
629 "Region already in use (index %u)", curr_region->hrm_index());
630 if (open) {
631 curr_region->set_open_archive();
632 } else {
633 curr_region->set_closed_archive();
634 }
635 _hr_printer.alloc(curr_region);
636 _archive_set.add(curr_region);
637 HeapWord* top;
638 HeapRegion* next_region;
639 if (curr_region != last_region) {
640 top = curr_region->end();
641 next_region = _hrm->next_region_in_heap(curr_region);
642 } else {
643 top = last_address + 1;
644 next_region = NULL;
645 }
646 curr_region->set_top(top);
647 curr_region = next_region;
648 }
649
650 // Notify mark-sweep of the archive
651 G1ArchiveAllocator::set_range_archive(curr_range, open);
652 }
653 return true;
654 }
655
656 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
657 assert(!is_init_completed(), "Expect to be called at JVM init time");
658 assert(ranges != NULL, "MemRegion array NULL");
659 assert(count != 0, "No MemRegions provided");
660 MemRegion reserved = _hrm->reserved();
661 HeapWord *prev_last_addr = NULL;
662 HeapRegion* prev_last_region = NULL;
663
664 // For each MemRegion, create filler objects, if needed, in the G1 regions
665 // that contain the address range. The address range actually within the
666 // MemRegion will not be modified. That is assumed to have been initialized
667 // elsewhere, probably via an mmap of archived heap data.
668 MutexLocker x(Heap_lock);
669 for (size_t i = 0; i < count; i++) {
670 HeapWord* start_address = ranges[i].start();
671 HeapWord* last_address = ranges[i].last();
672
673 assert(reserved.contains(start_address) && reserved.contains(last_address),
674 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
675 p2i(start_address), p2i(last_address));
676 assert(start_address > prev_last_addr,
677 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
678 p2i(start_address), p2i(prev_last_addr));
679
680 HeapRegion* start_region = _hrm->addr_to_region(start_address);
681 HeapRegion* last_region = _hrm->addr_to_region(last_address);
682 HeapWord* bottom_address = start_region->bottom();
683
684 // Check for a range beginning in the same region in which the
685 // previous one ended.
686 if (start_region == prev_last_region) {
687 bottom_address = prev_last_addr + 1;
688 }
689
690 // Verify that the regions were all marked as archive regions by
691 // alloc_archive_regions.
692 HeapRegion* curr_region = start_region;
693 while (curr_region != NULL) {
694 guarantee(curr_region->is_archive(),
695 "Expected archive region at index %u", curr_region->hrm_index());
696 if (curr_region != last_region) {
697 curr_region = _hrm->next_region_in_heap(curr_region);
698 } else {
699 curr_region = NULL;
700 }
701 }
702
703 prev_last_addr = last_address;
704 prev_last_region = last_region;
705
706 // Fill the memory below the allocated range with dummy object(s),
707 // if the region bottom does not match the range start, or if the previous
708 // range ended within the same G1 region, and there is a gap.
709 if (start_address != bottom_address) {
710 size_t fill_size = pointer_delta(start_address, bottom_address);
711 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
712 increase_used(fill_size * HeapWordSize);
713 }
714 }
715 }
716
717 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
718 size_t desired_word_size,
719 size_t* actual_word_size) {
720 assert_heap_not_locked_and_not_at_safepoint();
721 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
722 "be called for humongous allocation requests");
723
724 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
725
726 if (result == NULL) {
727 *actual_word_size = desired_word_size;
728 result = attempt_allocation_slow(desired_word_size);
729 }
730
731 assert_heap_not_locked();
732 if (result != NULL) {
733 assert(*actual_word_size != 0, "Actual size must have been set here");
734 dirty_young_block(result, *actual_word_size);
735 } else {
736 *actual_word_size = 0;
737 }
738
739 return result;
740 }
741
742 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
743 assert(!is_init_completed(), "Expect to be called at JVM init time");
744 assert(ranges != NULL, "MemRegion array NULL");
745 assert(count != 0, "No MemRegions provided");
746 MemRegion reserved = _hrm->reserved();
747 HeapWord* prev_last_addr = NULL;
748 HeapRegion* prev_last_region = NULL;
749 size_t size_used = 0;
750 size_t uncommitted_regions = 0;
751
752 // For each Memregion, free the G1 regions that constitute it, and
753 // notify mark-sweep that the range is no longer to be considered 'archive.'
754 MutexLocker x(Heap_lock);
755 for (size_t i = 0; i < count; i++) {
756 HeapWord* start_address = ranges[i].start();
757 HeapWord* last_address = ranges[i].last();
758
759 assert(reserved.contains(start_address) && reserved.contains(last_address),
760 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
761 p2i(start_address), p2i(last_address));
762 assert(start_address > prev_last_addr,
763 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
764 p2i(start_address), p2i(prev_last_addr));
765 size_used += ranges[i].byte_size();
766 prev_last_addr = last_address;
767
768 HeapRegion* start_region = _hrm->addr_to_region(start_address);
769 HeapRegion* last_region = _hrm->addr_to_region(last_address);
770
771 // Check for ranges that start in the same G1 region in which the previous
772 // range ended, and adjust the start address so we don't try to free
773 // the same region again. If the current range is entirely within that
774 // region, skip it.
775 if (start_region == prev_last_region) {
776 start_address = start_region->end();
777 if (start_address > last_address) {
778 continue;
779 }
780 start_region = _hrm->addr_to_region(start_address);
781 }
782 prev_last_region = last_region;
783
784 // After verifying that each region was marked as an archive region by
785 // alloc_archive_regions, set it free and empty and uncommit it.
786 HeapRegion* curr_region = start_region;
787 while (curr_region != NULL) {
788 guarantee(curr_region->is_archive(),
789 "Expected archive region at index %u", curr_region->hrm_index());
790 uint curr_index = curr_region->hrm_index();
791 _archive_set.remove(curr_region);
792 curr_region->set_free();
793 curr_region->set_top(curr_region->bottom());
794 if (curr_region != last_region) {
795 curr_region = _hrm->next_region_in_heap(curr_region);
796 } else {
797 curr_region = NULL;
798 }
799 _hrm->shrink_at(curr_index, 1);
800 uncommitted_regions++;
801 }
802
803 // Notify mark-sweep that this is no longer an archive range.
804 G1ArchiveAllocator::clear_range_archive(ranges[i]);
805 }
806
807 if (uncommitted_regions != 0) {
808 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
809 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
810 }
811 decrease_used(size_used);
812 }
813
814 oop G1CollectedHeap::materialize_archived_object(oop obj) {
815 assert(obj != NULL, "archived obj is NULL");
816 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
817
818 // Loading an archived object makes it strongly reachable. If it is
819 // loaded during concurrent marking, it must be enqueued to the SATB
820 // queue, shading the previously white object gray.
821 G1BarrierSet::enqueue(obj);
822
823 return obj;
824 }
825
826 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
827 ResourceMark rm; // For retrieving the thread names in log messages.
828
829 // The structure of this method has a lot of similarities to
830 // attempt_allocation_slow(). The reason these two were not merged
831 // into a single one is that such a method would require several "if
832 // allocation is not humongous do this, otherwise do that"
833 // conditional paths which would obscure its flow. In fact, an early
834 // version of this code did use a unified method which was harder to
835 // follow and, as a result, it had subtle bugs that were hard to
836 // track down. So keeping these two methods separate allows each to
837 // be more readable. It will be good to keep these two in sync as
838 // much as possible.
839
840 assert_heap_not_locked_and_not_at_safepoint();
841 assert(is_humongous(word_size), "attempt_allocation_humongous() "
842 "should only be called for humongous allocations");
843
844 // Humongous objects can exhaust the heap quickly, so we should check if we
845 // need to start a marking cycle at each humongous object allocation. We do
846 // the check before we do the actual allocation. The reason for doing it
847 // before the allocation is that we avoid having to keep track of the newly
848 // allocated memory while we do a GC.
849 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
850 word_size)) {
851 collect(GCCause::_g1_humongous_allocation);
852 }
853
854 // We will loop until a) we manage to successfully perform the
855 // allocation or b) we successfully schedule a collection which
856 // fails to perform the allocation. b) is the only case when we'll
857 // return NULL.
858 HeapWord* result = NULL;
859 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
860 bool should_try_gc;
861 uint gc_count_before;
862
863
864 {
865 MutexLocker x(Heap_lock);
866
867 // Given that humongous objects are not allocated in young
868 // regions, we'll first try to do the allocation without doing a
869 // collection hoping that there's enough space in the heap.
870 result = humongous_obj_allocate(word_size);
871 if (result != NULL) {
872 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
873 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
874 return result;
875 }
876
877 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
878 // the GCLocker initiated GC has been performed and then retry. This includes
879 // the case when the GC Locker is not active but has not been performed.
880 should_try_gc = !GCLocker::needs_gc();
881 // Read the GC count while still holding the Heap_lock.
882 gc_count_before = total_collections();
883 }
884
885 if (should_try_gc) {
886 bool succeeded;
887 result = do_collection_pause(word_size, gc_count_before, &succeeded,
888 GCCause::_g1_humongous_allocation);
889 if (result != NULL) {
890 assert(succeeded, "only way to get back a non-NULL result");
891 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
892 Thread::current()->name(), p2i(result));
893 return result;
894 }
895
896 if (succeeded) {
897 // We successfully scheduled a collection which failed to allocate. No
898 // point in trying to allocate further. We'll just return NULL.
899 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
900 SIZE_FORMAT " words", Thread::current()->name(), word_size);
901 return NULL;
902 }
903 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
904 Thread::current()->name(), word_size);
905 } else {
906 // Failed to schedule a collection.
907 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
908 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
909 SIZE_FORMAT " words", Thread::current()->name(), word_size);
910 return NULL;
911 }
912 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
913 // The GCLocker is either active or the GCLocker initiated
914 // GC has not yet been performed. Stall until it is and
915 // then retry the allocation.
916 GCLocker::stall_until_clear();
917 gclocker_retry_count += 1;
918 }
919
920
921 // We can reach here if we were unsuccessful in scheduling a
922 // collection (because another thread beat us to it) or if we were
923 // stalled due to the GC locker. In either can we should retry the
924 // allocation attempt in case another thread successfully
925 // performed a collection and reclaimed enough space.
926 // Humongous object allocation always needs a lock, so we wait for the retry
927 // in the next iteration of the loop, unlike for the regular iteration case.
928 // Give a warning if we seem to be looping forever.
929
930 if ((QueuedAllocationWarningCount > 0) &&
931 (try_count % QueuedAllocationWarningCount == 0)) {
932 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
933 Thread::current()->name(), try_count, word_size);
934 }
935 }
936
937 ShouldNotReachHere();
938 return NULL;
939 }
940
941 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
942 bool expect_null_mutator_alloc_region) {
943 assert_at_safepoint_on_vm_thread();
944 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
945 "the current alloc region was unexpectedly found to be non-NULL");
946
947 if (!is_humongous(word_size)) {
948 return _allocator->attempt_allocation_locked(word_size);
949 } else {
950 HeapWord* result = humongous_obj_allocate(word_size);
951 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
952 collector_state()->set_initiate_conc_mark_if_possible(true);
953 }
954 return result;
955 }
956
957 ShouldNotReachHere();
958 }
959
960 class PostCompactionPrinterClosure: public HeapRegionClosure {
961 private:
962 G1HRPrinter* _hr_printer;
963 public:
964 bool do_heap_region(HeapRegion* hr) {
965 assert(!hr->is_young(), "not expecting to find young regions");
966 _hr_printer->post_compaction(hr);
967 return false;
968 }
969
970 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
971 : _hr_printer(hr_printer) { }
972 };
973
974 void G1CollectedHeap::print_hrm_post_compaction() {
975 if (_hr_printer.is_active()) {
976 PostCompactionPrinterClosure cl(hr_printer());
977 heap_region_iterate(&cl);
978 }
979 }
980
981 void G1CollectedHeap::abort_concurrent_cycle() {
982 // If we start the compaction before the CM threads finish
983 // scanning the root regions we might trip them over as we'll
984 // be moving objects / updating references. So let's wait until
985 // they are done. By telling them to abort, they should complete
986 // early.
987 _cm->root_regions()->abort();
988 _cm->root_regions()->wait_until_scan_finished();
989
990 // Disable discovery and empty the discovered lists
991 // for the CM ref processor.
992 _ref_processor_cm->disable_discovery();
993 _ref_processor_cm->abandon_partial_discovery();
994 _ref_processor_cm->verify_no_references_recorded();
995
996 // Abandon current iterations of concurrent marking and concurrent
997 // refinement, if any are in progress.
998 concurrent_mark()->concurrent_cycle_abort();
999 }
1000
1001 void G1CollectedHeap::prepare_heap_for_full_collection() {
1002 // Make sure we'll choose a new allocation region afterwards.
1003 _allocator->release_mutator_alloc_regions();
1004 _allocator->abandon_gc_alloc_regions();
1005
1006 // We may have added regions to the current incremental collection
1007 // set between the last GC or pause and now. We need to clear the
1008 // incremental collection set and then start rebuilding it afresh
1009 // after this full GC.
1010 abandon_collection_set(collection_set());
1011
1012 tear_down_region_sets(false /* free_list_only */);
1013
1014 hrm()->prepare_for_full_collection_start();
1015 }
1016
1017 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1018 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1019 assert_used_and_recalculate_used_equal(this);
1020 _verifier->verify_region_sets_optional();
1021 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1022 _verifier->check_bitmaps("Full GC Start");
1023 }
1024
1025 void G1CollectedHeap::prepare_heap_for_mutators() {
1026 hrm()->prepare_for_full_collection_end();
1027
1028 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1029 ClassLoaderDataGraph::purge();
1030 MetaspaceUtils::verify_metrics();
1031
1032 // Prepare heap for normal collections.
1033 assert(num_free_regions() == 0, "we should not have added any free regions");
1034 rebuild_region_sets(false /* free_list_only */);
1035 abort_refinement();
1036 resize_heap_if_necessary();
1037
1038 // Rebuild the strong code root lists for each region
1039 rebuild_strong_code_roots();
1040
1041 // Purge code root memory
1042 purge_code_root_memory();
1043
1044 // Start a new incremental collection set for the next pause
1045 start_new_collection_set();
1046
1047 _allocator->init_mutator_alloc_regions();
1048
1049 // Post collection state updates.
1050 MetaspaceGC::compute_new_size();
1051 }
1052
1053 void G1CollectedHeap::abort_refinement() {
1054 if (_hot_card_cache->use_cache()) {
1055 _hot_card_cache->reset_hot_cache();
1056 }
1057
1058 // Discard all remembered set updates and reset refinement statistics.
1059 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1060 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1061 "DCQS should be empty");
1062 concurrent_refine()->get_and_reset_refinement_stats();
1063 }
1064
1065 void G1CollectedHeap::verify_after_full_collection() {
1066 _hrm->verify_optional();
1067 _verifier->verify_region_sets_optional();
1068 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1069 // Clear the previous marking bitmap, if needed for bitmap verification.
1070 // Note we cannot do this when we clear the next marking bitmap in
1071 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1072 // objects marked during a full GC against the previous bitmap.
1073 // But we need to clear it before calling check_bitmaps below since
1074 // the full GC has compacted objects and updated TAMS but not updated
1075 // the prev bitmap.
1076 if (G1VerifyBitmaps) {
1077 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1078 _cm->clear_prev_bitmap(workers());
1079 }
1080 // This call implicitly verifies that the next bitmap is clear after Full GC.
1081 _verifier->check_bitmaps("Full GC End");
1082
1083 // At this point there should be no regions in the
1084 // entire heap tagged as young.
1085 assert(check_young_list_empty(), "young list should be empty at this point");
1086
1087 // Note: since we've just done a full GC, concurrent
1088 // marking is no longer active. Therefore we need not
1089 // re-enable reference discovery for the CM ref processor.
1090 // That will be done at the start of the next marking cycle.
1091 // We also know that the STW processor should no longer
1092 // discover any new references.
1093 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1094 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1095 _ref_processor_stw->verify_no_references_recorded();
1096 _ref_processor_cm->verify_no_references_recorded();
1097 }
1098
1099 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1100 // Post collection logging.
1101 // We should do this after we potentially resize the heap so
1102 // that all the COMMIT / UNCOMMIT events are generated before
1103 // the compaction events.
1104 print_hrm_post_compaction();
1105 heap_transition->print();
1106 print_heap_after_gc();
1107 print_heap_regions();
1108 }
1109
1110 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1111 bool clear_all_soft_refs) {
1112 assert_at_safepoint_on_vm_thread();
1113
1114 if (GCLocker::check_active_before_gc()) {
1115 // Full GC was not completed.
1116 return false;
1117 }
1118
1119 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1120 soft_ref_policy()->should_clear_all_soft_refs();
1121
1122 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1123 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1124
1125 collector.prepare_collection();
1126 collector.collect();
1127 collector.complete_collection();
1128
1129 // Full collection was successfully completed.
1130 return true;
1131 }
1132
1133 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1134 // Currently, there is no facility in the do_full_collection(bool) API to notify
1135 // the caller that the collection did not succeed (e.g., because it was locked
1136 // out by the GC locker). So, right now, we'll ignore the return value.
1137 bool dummy = do_full_collection(true, /* explicit_gc */
1138 clear_all_soft_refs);
1139 }
1140
1141 void G1CollectedHeap::resize_heap_if_necessary() {
1142 assert_at_safepoint_on_vm_thread();
1143
1144 // Capacity, free and used after the GC counted as full regions to
1145 // include the waste in the following calculations.
1146 const size_t capacity_after_gc = capacity();
1147 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1148
1149 // This is enforced in arguments.cpp.
1150 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1151 "otherwise the code below doesn't make sense");
1152
1153 // We don't have floating point command-line arguments
1154 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1155 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1156 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1157 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1158
1159 // We have to be careful here as these two calculations can overflow
1160 // 32-bit size_t's.
1161 double used_after_gc_d = (double) used_after_gc;
1162 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1163 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1164
1165 // Let's make sure that they are both under the max heap size, which
1166 // by default will make them fit into a size_t.
1167 double desired_capacity_upper_bound = (double) MaxHeapSize;
1168 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1169 desired_capacity_upper_bound);
1170 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1171 desired_capacity_upper_bound);
1172
1173 // We can now safely turn them into size_t's.
1174 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1175 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1176
1177 // This assert only makes sense here, before we adjust them
1178 // with respect to the min and max heap size.
1179 assert(minimum_desired_capacity <= maximum_desired_capacity,
1180 "minimum_desired_capacity = " SIZE_FORMAT ", "
1181 "maximum_desired_capacity = " SIZE_FORMAT,
1182 minimum_desired_capacity, maximum_desired_capacity);
1183
1184 // Should not be greater than the heap max size. No need to adjust
1185 // it with respect to the heap min size as it's a lower bound (i.e.,
1186 // we'll try to make the capacity larger than it, not smaller).
1187 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1188 // Should not be less than the heap min size. No need to adjust it
1189 // with respect to the heap max size as it's an upper bound (i.e.,
1190 // we'll try to make the capacity smaller than it, not greater).
1191 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1192
1193 if (capacity_after_gc < minimum_desired_capacity) {
1194 // Don't expand unless it's significant
1195 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1196
1197 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1198 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1199 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1200 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1201
1202 expand(expand_bytes, _workers);
1203
1204 // No expansion, now see if we want to shrink
1205 } else if (capacity_after_gc > maximum_desired_capacity) {
1206 // Capacity too large, compute shrinking size
1207 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1208
1209 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1210 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1211 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1212 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1213
1214 shrink(shrink_bytes);
1215 }
1216 }
1217
1218 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1219 bool do_gc,
1220 bool clear_all_soft_refs,
1221 bool expect_null_mutator_alloc_region,
1222 bool* gc_succeeded) {
1223 *gc_succeeded = true;
1224 // Let's attempt the allocation first.
1225 HeapWord* result =
1226 attempt_allocation_at_safepoint(word_size,
1227 expect_null_mutator_alloc_region);
1228 if (result != NULL) {
1229 return result;
1230 }
1231
1232 // In a G1 heap, we're supposed to keep allocation from failing by
1233 // incremental pauses. Therefore, at least for now, we'll favor
1234 // expansion over collection. (This might change in the future if we can
1235 // do something smarter than full collection to satisfy a failed alloc.)
1236 result = expand_and_allocate(word_size);
1237 if (result != NULL) {
1238 return result;
1239 }
1240
1241 if (do_gc) {
1242 // Expansion didn't work, we'll try to do a Full GC.
1243 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1244 clear_all_soft_refs);
1245 }
1246
1247 return NULL;
1248 }
1249
1250 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1251 bool* succeeded) {
1252 assert_at_safepoint_on_vm_thread();
1253
1254 // Attempts to allocate followed by Full GC.
1255 HeapWord* result =
1256 satisfy_failed_allocation_helper(word_size,
1257 true, /* do_gc */
1258 false, /* clear_all_soft_refs */
1259 false, /* expect_null_mutator_alloc_region */
1260 succeeded);
1261
1262 if (result != NULL || !*succeeded) {
1263 return result;
1264 }
1265
1266 // Attempts to allocate followed by Full GC that will collect all soft references.
1267 result = satisfy_failed_allocation_helper(word_size,
1268 true, /* do_gc */
1269 true, /* clear_all_soft_refs */
1270 true, /* expect_null_mutator_alloc_region */
1271 succeeded);
1272
1273 if (result != NULL || !*succeeded) {
1274 return result;
1275 }
1276
1277 // Attempts to allocate, no GC
1278 result = satisfy_failed_allocation_helper(word_size,
1279 false, /* do_gc */
1280 false, /* clear_all_soft_refs */
1281 true, /* expect_null_mutator_alloc_region */
1282 succeeded);
1283
1284 if (result != NULL) {
1285 return result;
1286 }
1287
1288 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1289 "Flag should have been handled and cleared prior to this point");
1290
1291 // What else? We might try synchronous finalization later. If the total
1292 // space available is large enough for the allocation, then a more
1293 // complete compaction phase than we've tried so far might be
1294 // appropriate.
1295 return NULL;
1296 }
1297
1298 // Attempting to expand the heap sufficiently
1299 // to support an allocation of the given "word_size". If
1300 // successful, perform the allocation and return the address of the
1301 // allocated block, or else "NULL".
1302
1303 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1304 assert_at_safepoint_on_vm_thread();
1305
1306 _verifier->verify_region_sets_optional();
1307
1308 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1309 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1310 word_size * HeapWordSize);
1311
1312
1313 if (expand(expand_bytes, _workers)) {
1314 _hrm->verify_optional();
1315 _verifier->verify_region_sets_optional();
1316 return attempt_allocation_at_safepoint(word_size,
1317 false /* expect_null_mutator_alloc_region */);
1318 }
1319 return NULL;
1320 }
1321
1322 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1323 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1324 aligned_expand_bytes = align_up(aligned_expand_bytes,
1325 HeapRegion::GrainBytes);
1326
1327 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1328 expand_bytes, aligned_expand_bytes);
1329
1330 if (is_maximal_no_gc()) {
1331 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1332 return false;
1333 }
1334
1335 double expand_heap_start_time_sec = os::elapsedTime();
1336 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1337 assert(regions_to_expand > 0, "Must expand by at least one region");
1338
1339 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1340 if (expand_time_ms != NULL) {
1341 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1342 }
1343
1344 if (expanded_by > 0) {
1345 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1346 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1347 policy()->record_new_heap_size(num_regions());
1348 } else {
1349 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1350
1351 // The expansion of the virtual storage space was unsuccessful.
1352 // Let's see if it was because we ran out of swap.
1353 if (G1ExitOnExpansionFailure &&
1354 _hrm->available() >= regions_to_expand) {
1355 // We had head room...
1356 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1357 }
1358 }
1359 return regions_to_expand > 0;
1360 }
1361
1362 bool G1CollectedHeap::expand_single_region(uint node_index) {
1363 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1364
1365 if (expanded_by == 0) {
1366 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1367 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1368 return false;
1369 }
1370
1371 policy()->record_new_heap_size(num_regions());
1372 return true;
1373 }
1374
1375 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1376 size_t aligned_shrink_bytes =
1377 ReservedSpace::page_align_size_down(shrink_bytes);
1378 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1379 HeapRegion::GrainBytes);
1380 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1381
1382 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1383 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1384
1385 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",
1386 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1387 if (num_regions_removed > 0) {
1388 policy()->record_new_heap_size(num_regions());
1389 } else {
1390 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1391 }
1392 }
1393
1394 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1395 _verifier->verify_region_sets_optional();
1396
1397 // We should only reach here at the end of a Full GC or during Remark which
1398 // means we should not not be holding to any GC alloc regions. The method
1399 // below will make sure of that and do any remaining clean up.
1400 _allocator->abandon_gc_alloc_regions();
1401
1402 // Instead of tearing down / rebuilding the free lists here, we
1403 // could instead use the remove_all_pending() method on free_list to
1404 // remove only the ones that we need to remove.
1405 tear_down_region_sets(true /* free_list_only */);
1406 shrink_helper(shrink_bytes);
1407 rebuild_region_sets(true /* free_list_only */);
1408
1409 _hrm->verify_optional();
1410 _verifier->verify_region_sets_optional();
1411 }
1412
1413 class OldRegionSetChecker : public HeapRegionSetChecker {
1414 public:
1415 void check_mt_safety() {
1416 // Master Old Set MT safety protocol:
1417 // (a) If we're at a safepoint, operations on the master old set
1418 // should be invoked:
1419 // - by the VM thread (which will serialize them), or
1420 // - by the GC workers while holding the FreeList_lock, if we're
1421 // at a safepoint for an evacuation pause (this lock is taken
1422 // anyway when an GC alloc region is retired so that a new one
1423 // is allocated from the free list), or
1424 // - by the GC workers while holding the OldSets_lock, if we're at a
1425 // safepoint for a cleanup pause.
1426 // (b) If we're not at a safepoint, operations on the master old set
1427 // should be invoked while holding the Heap_lock.
1428
1429 if (SafepointSynchronize::is_at_safepoint()) {
1430 guarantee(Thread::current()->is_VM_thread() ||
1431 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1432 "master old set MT safety protocol at a safepoint");
1433 } else {
1434 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1435 }
1436 }
1437 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1438 const char* get_description() { return "Old Regions"; }
1439 };
1440
1441 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1442 public:
1443 void check_mt_safety() {
1444 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1445 "May only change archive regions during initialization or safepoint.");
1446 }
1447 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1448 const char* get_description() { return "Archive Regions"; }
1449 };
1450
1451 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1452 public:
1453 void check_mt_safety() {
1454 // Humongous Set MT safety protocol:
1455 // (a) If we're at a safepoint, operations on the master humongous
1456 // set should be invoked by either the VM thread (which will
1457 // serialize them) or by the GC workers while holding the
1458 // OldSets_lock.
1459 // (b) If we're not at a safepoint, operations on the master
1460 // humongous set should be invoked while holding the Heap_lock.
1461
1462 if (SafepointSynchronize::is_at_safepoint()) {
1463 guarantee(Thread::current()->is_VM_thread() ||
1464 OldSets_lock->owned_by_self(),
1465 "master humongous set MT safety protocol at a safepoint");
1466 } else {
1467 guarantee(Heap_lock->owned_by_self(),
1468 "master humongous set MT safety protocol outside a safepoint");
1469 }
1470 }
1471 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1472 const char* get_description() { return "Humongous Regions"; }
1473 };
1474
1475 G1CollectedHeap::G1CollectedHeap() :
1476 CollectedHeap(),
1477 _young_gen_sampling_thread(NULL),
1478 _workers(NULL),
1479 _card_table(NULL),
1480 _soft_ref_policy(),
1481 _old_set("Old Region Set", new OldRegionSetChecker()),
1482 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1483 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1484 _bot(NULL),
1485 _listener(),
1486 _numa(G1NUMA::create()),
1487 _hrm(NULL),
1488 _allocator(NULL),
1489 _verifier(NULL),
1490 _summary_bytes_used(0),
1491 _bytes_used_during_gc(0),
1492 _archive_allocator(NULL),
1493 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1494 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1495 _expand_heap_after_alloc_failure(true),
1496 _g1mm(NULL),
1497 _humongous_reclaim_candidates(),
1498 _has_humongous_reclaim_candidates(false),
1499 _hr_printer(),
1500 _collector_state(),
1501 _old_marking_cycles_started(0),
1502 _old_marking_cycles_completed(0),
1503 _eden(),
1504 _survivor(),
1505 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1506 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1507 _policy(G1Policy::create_policy(_gc_timer_stw)),
1508 _heap_sizing_policy(NULL),
1509 _collection_set(this, _policy),
1510 _hot_card_cache(NULL),
1511 _rem_set(NULL),
1512 _cm(NULL),
1513 _cm_thread(NULL),
1514 _cr(NULL),
1515 _task_queues(NULL),
1516 _evacuation_failed(false),
1517 _evacuation_failed_info_array(NULL),
1518 _preserved_marks_set(true /* in_c_heap */),
1519 #ifndef PRODUCT
1520 _evacuation_failure_alot_for_current_gc(false),
1521 _evacuation_failure_alot_gc_number(0),
1522 _evacuation_failure_alot_count(0),
1523 #endif
1524 _ref_processor_stw(NULL),
1525 _is_alive_closure_stw(this),
1526 _is_subject_to_discovery_stw(this),
1527 _ref_processor_cm(NULL),
1528 _is_alive_closure_cm(this),
1529 _is_subject_to_discovery_cm(this),
1530 _region_attr() {
1531
1532 _verifier = new G1HeapVerifier(this);
1533
1534 _allocator = new G1Allocator(this);
1535
1536 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1537
1538 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1539
1540 // Override the default _filler_array_max_size so that no humongous filler
1541 // objects are created.
1542 _filler_array_max_size = _humongous_object_threshold_in_words;
1543
1544 uint n_queues = ParallelGCThreads;
1545 _task_queues = new RefToScanQueueSet(n_queues);
1546
1547 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1548
1549 for (uint i = 0; i < n_queues; i++) {
1550 RefToScanQueue* q = new RefToScanQueue();
1551 q->initialize();
1552 _task_queues->register_queue(i, q);
1553 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1554 }
1555
1556 // Initialize the G1EvacuationFailureALot counters and flags.
1557 NOT_PRODUCT(reset_evacuation_should_fail();)
1558 _gc_tracer_stw->initialize();
1559
1560 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1561 }
1562
1563 static size_t actual_reserved_page_size(ReservedSpace rs) {
1564 size_t page_size = os::vm_page_size();
1565 if (UseLargePages) {
1566 // There are two ways to manage large page memory.
1567 // 1. OS supports committing large page memory.
1568 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1569 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1570 // we reserved memory without large page.
1571 if (os::can_commit_large_page_memory() || rs.special()) {
1572 // An alignment at ReservedSpace comes from preferred page size or
1573 // heap alignment, and if the alignment came from heap alignment, it could be
1574 // larger than large pages size. So need to cap with the large page size.
1575 page_size = MIN2(rs.alignment(), os::large_page_size());
1576 }
1577 }
1578
1579 return page_size;
1580 }
1581
1582 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1583 size_t size,
1584 size_t translation_factor) {
1585 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1586 // Allocate a new reserved space, preferring to use large pages.
1587 ReservedSpace rs(size, preferred_page_size);
1588 size_t page_size = actual_reserved_page_size(rs);
1589 G1RegionToSpaceMapper* result =
1590 G1RegionToSpaceMapper::create_mapper(rs,
1591 size,
1592 page_size,
1593 HeapRegion::GrainBytes,
1594 translation_factor,
1595 mtGC);
1596
1597 os::trace_page_sizes_for_requested_size(description,
1598 size,
1599 preferred_page_size,
1600 page_size,
1601 rs.base(),
1602 rs.size());
1603
1604 return result;
1605 }
1606
1607 jint G1CollectedHeap::initialize_concurrent_refinement() {
1608 jint ecode = JNI_OK;
1609 _cr = G1ConcurrentRefine::create(&ecode);
1610 return ecode;
1611 }
1612
1613 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1614 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1615 if (_young_gen_sampling_thread->osthread() == NULL) {
1616 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1617 return JNI_ENOMEM;
1618 }
1619 return JNI_OK;
1620 }
1621
1622 jint G1CollectedHeap::initialize() {
1623
1624 // Necessary to satisfy locking discipline assertions.
1625
1626 MutexLocker x(Heap_lock);
1627
1628 // While there are no constraints in the GC code that HeapWordSize
1629 // be any particular value, there are multiple other areas in the
1630 // system which believe this to be true (e.g. oop->object_size in some
1631 // cases incorrectly returns the size in wordSize units rather than
1632 // HeapWordSize).
1633 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1634
1635 size_t init_byte_size = InitialHeapSize;
1636 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1637
1638 // Ensure that the sizes are properly aligned.
1639 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1640 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1641 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1642
1643 // Reserve the maximum.
1644
1645 // When compressed oops are enabled, the preferred heap base
1646 // is calculated by subtracting the requested size from the
1647 // 32Gb boundary and using the result as the base address for
1648 // heap reservation. If the requested size is not aligned to
1649 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1650 // into the ReservedHeapSpace constructor) then the actual
1651 // base of the reserved heap may end up differing from the
1652 // address that was requested (i.e. the preferred heap base).
1653 // If this happens then we could end up using a non-optimal
1654 // compressed oops mode.
1655
1656 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1657 HeapAlignment);
1658
1659 initialize_reserved_region(heap_rs);
1660
1661 // Create the barrier set for the entire reserved region.
1662 G1CardTable* ct = new G1CardTable(heap_rs.region());
1663 ct->initialize();
1664 G1BarrierSet* bs = new G1BarrierSet(ct);
1665 bs->initialize();
1666 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1667 BarrierSet::set_barrier_set(bs);
1668 _card_table = ct;
1669
1670 {
1671 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1672 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1673 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1674 }
1675
1676 // Create the hot card cache.
1677 _hot_card_cache = new G1HotCardCache(this);
1678
1679 // Carve out the G1 part of the heap.
1680 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1681 size_t page_size = actual_reserved_page_size(heap_rs);
1682 G1RegionToSpaceMapper* heap_storage =
1683 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1684 g1_rs.size(),
1685 page_size,
1686 HeapRegion::GrainBytes,
1687 1,
1688 mtJavaHeap);
1689 if(heap_storage == NULL) {
1690 vm_shutdown_during_initialization("Could not initialize G1 heap");
1691 return JNI_ERR;
1692 }
1693
1694 os::trace_page_sizes("Heap",
1695 MinHeapSize,
1696 reserved_byte_size,
1697 page_size,
1698 heap_rs.base(),
1699 heap_rs.size());
1700 heap_storage->set_mapping_changed_listener(&_listener);
1701
1702 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1703 G1RegionToSpaceMapper* bot_storage =
1704 create_aux_memory_mapper("Block Offset Table",
1705 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1706 G1BlockOffsetTable::heap_map_factor());
1707
1708 G1RegionToSpaceMapper* cardtable_storage =
1709 create_aux_memory_mapper("Card Table",
1710 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1711 G1CardTable::heap_map_factor());
1712
1713 G1RegionToSpaceMapper* card_counts_storage =
1714 create_aux_memory_mapper("Card Counts Table",
1715 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1716 G1CardCounts::heap_map_factor());
1717
1718 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1719 G1RegionToSpaceMapper* prev_bitmap_storage =
1720 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1721 G1RegionToSpaceMapper* next_bitmap_storage =
1722 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1723
1724 _hrm = HeapRegionManager::create_manager(this);
1725
1726 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1727 _card_table->initialize(cardtable_storage);
1728
1729 // Do later initialization work for concurrent refinement.
1730 _hot_card_cache->initialize(card_counts_storage);
1731
1732 // 6843694 - ensure that the maximum region index can fit
1733 // in the remembered set structures.
1734 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1735 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1736
1737 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1738 // start within the first card.
1739 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1740 // Also create a G1 rem set.
1741 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1742 _rem_set->initialize(max_reserved_capacity(), max_regions());
1743
1744 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1745 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1746 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1747 "too many cards per region");
1748
1749 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1750
1751 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1752
1753 {
1754 HeapWord* start = _hrm->reserved().start();
1755 HeapWord* end = _hrm->reserved().end();
1756 size_t granularity = HeapRegion::GrainBytes;
1757
1758 _region_attr.initialize(start, end, granularity);
1759 _humongous_reclaim_candidates.initialize(start, end, granularity);
1760 }
1761
1762 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1763 true /* are_GC_task_threads */,
1764 false /* are_ConcurrentGC_threads */);
1765 if (_workers == NULL) {
1766 return JNI_ENOMEM;
1767 }
1768 _workers->initialize_workers();
1769
1770 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1771
1772 // Create the G1ConcurrentMark data structure and thread.
1773 // (Must do this late, so that "max_regions" is defined.)
1774 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1775 _cm_thread = _cm->cm_thread();
1776
1777 // Now expand into the initial heap size.
1778 if (!expand(init_byte_size, _workers)) {
1779 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1780 return JNI_ENOMEM;
1781 }
1782
1783 // Perform any initialization actions delegated to the policy.
1784 policy()->init(this, &_collection_set);
1785
1786 jint ecode = initialize_concurrent_refinement();
1787 if (ecode != JNI_OK) {
1788 return ecode;
1789 }
1790
1791 ecode = initialize_young_gen_sampling_thread();
1792 if (ecode != JNI_OK) {
1793 return ecode;
1794 }
1795
1796 {
1797 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1798 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1799 dcqs.set_max_cards(concurrent_refine()->red_zone());
1800 }
1801
1802 // Here we allocate the dummy HeapRegion that is required by the
1803 // G1AllocRegion class.
1804 HeapRegion* dummy_region = _hrm->get_dummy_region();
1805
1806 // We'll re-use the same region whether the alloc region will
1807 // require BOT updates or not and, if it doesn't, then a non-young
1808 // region will complain that it cannot support allocations without
1809 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1810 dummy_region->set_eden();
1811 // Make sure it's full.
1812 dummy_region->set_top(dummy_region->end());
1813 G1AllocRegion::setup(this, dummy_region);
1814
1815 _allocator->init_mutator_alloc_regions();
1816
1817 // Do create of the monitoring and management support so that
1818 // values in the heap have been properly initialized.
1819 _g1mm = new G1MonitoringSupport(this);
1820
1821 G1StringDedup::initialize();
1822
1823 _preserved_marks_set.init(ParallelGCThreads);
1824
1825 _collection_set.initialize(max_regions());
1826
1827 return JNI_OK;
1828 }
1829
1830 void G1CollectedHeap::stop() {
1831 // Stop all concurrent threads. We do this to make sure these threads
1832 // do not continue to execute and access resources (e.g. logging)
1833 // that are destroyed during shutdown.
1834 _cr->stop();
1835 _young_gen_sampling_thread->stop();
1836 _cm_thread->stop();
1837 if (G1StringDedup::is_enabled()) {
1838 G1StringDedup::stop();
1839 }
1840 }
1841
1842 void G1CollectedHeap::safepoint_synchronize_begin() {
1843 SuspendibleThreadSet::synchronize();
1844 }
1845
1846 void G1CollectedHeap::safepoint_synchronize_end() {
1847 SuspendibleThreadSet::desynchronize();
1848 }
1849
1850 void G1CollectedHeap::post_initialize() {
1851 CollectedHeap::post_initialize();
1852 ref_processing_init();
1853 }
1854
1855 void G1CollectedHeap::ref_processing_init() {
1856 // Reference processing in G1 currently works as follows:
1857 //
1858 // * There are two reference processor instances. One is
1859 // used to record and process discovered references
1860 // during concurrent marking; the other is used to
1861 // record and process references during STW pauses
1862 // (both full and incremental).
1863 // * Both ref processors need to 'span' the entire heap as
1864 // the regions in the collection set may be dotted around.
1865 //
1866 // * For the concurrent marking ref processor:
1867 // * Reference discovery is enabled at initial marking.
1868 // * Reference discovery is disabled and the discovered
1869 // references processed etc during remarking.
1870 // * Reference discovery is MT (see below).
1871 // * Reference discovery requires a barrier (see below).
1872 // * Reference processing may or may not be MT
1873 // (depending on the value of ParallelRefProcEnabled
1874 // and ParallelGCThreads).
1875 // * A full GC disables reference discovery by the CM
1876 // ref processor and abandons any entries on it's
1877 // discovered lists.
1878 //
1879 // * For the STW processor:
1880 // * Non MT discovery is enabled at the start of a full GC.
1881 // * Processing and enqueueing during a full GC is non-MT.
1882 // * During a full GC, references are processed after marking.
1883 //
1884 // * Discovery (may or may not be MT) is enabled at the start
1885 // of an incremental evacuation pause.
1886 // * References are processed near the end of a STW evacuation pause.
1887 // * For both types of GC:
1888 // * Discovery is atomic - i.e. not concurrent.
1889 // * Reference discovery will not need a barrier.
1890
1891 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1892
1893 // Concurrent Mark ref processor
1894 _ref_processor_cm =
1895 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1896 mt_processing, // mt processing
1897 ParallelGCThreads, // degree of mt processing
1898 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1899 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1900 false, // Reference discovery is not atomic
1901 &_is_alive_closure_cm, // is alive closure
1902 true); // allow changes to number of processing threads
1903
1904 // STW ref processor
1905 _ref_processor_stw =
1906 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1907 mt_processing, // mt processing
1908 ParallelGCThreads, // degree of mt processing
1909 (ParallelGCThreads > 1), // mt discovery
1910 ParallelGCThreads, // degree of mt discovery
1911 true, // Reference discovery is atomic
1912 &_is_alive_closure_stw, // is alive closure
1913 true); // allow changes to number of processing threads
1914 }
1915
1916 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1917 return &_soft_ref_policy;
1918 }
1919
1920 size_t G1CollectedHeap::capacity() const {
1921 return _hrm->length() * HeapRegion::GrainBytes;
1922 }
1923
1924 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1925 return _hrm->total_free_bytes();
1926 }
1927
1928 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1929 _hot_card_cache->drain(cl, worker_id);
1930 }
1931
1932 // Computes the sum of the storage used by the various regions.
1933 size_t G1CollectedHeap::used() const {
1934 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1935 if (_archive_allocator != NULL) {
1936 result += _archive_allocator->used();
1937 }
1938 return result;
1939 }
1940
1941 size_t G1CollectedHeap::used_unlocked() const {
1942 return _summary_bytes_used;
1943 }
1944
1945 class SumUsedClosure: public HeapRegionClosure {
1946 size_t _used;
1947 public:
1948 SumUsedClosure() : _used(0) {}
1949 bool do_heap_region(HeapRegion* r) {
1950 _used += r->used();
1951 return false;
1952 }
1953 size_t result() { return _used; }
1954 };
1955
1956 size_t G1CollectedHeap::recalculate_used() const {
1957 SumUsedClosure blk;
1958 heap_region_iterate(&blk);
1959 return blk.result();
1960 }
1961
1962 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1963 switch (cause) {
1964 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1965 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1966 case GCCause::_wb_conc_mark: return true;
1967 default : return false;
1968 }
1969 }
1970
1971 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1972 switch (cause) {
1973 case GCCause::_g1_humongous_allocation: return true;
1974 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1975 case GCCause::_wb_breakpoint: return true;
1976 default: return is_user_requested_concurrent_full_gc(cause);
1977 }
1978 }
1979
1980 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1981 if (policy()->force_upgrade_to_full()) {
1982 return true;
1983 } else if (should_do_concurrent_full_gc(_gc_cause)) {
1984 return false;
1985 } else if (has_regions_left_for_allocation()) {
1986 return false;
1987 } else {
1988 return true;
1989 }
1990 }
1991
1992 #ifndef PRODUCT
1993 void G1CollectedHeap::allocate_dummy_regions() {
1994 // Let's fill up most of the region
1995 size_t word_size = HeapRegion::GrainWords - 1024;
1996 // And as a result the region we'll allocate will be humongous.
1997 guarantee(is_humongous(word_size), "sanity");
1998
1999 // _filler_array_max_size is set to humongous object threshold
2000 // but temporarily change it to use CollectedHeap::fill_with_object().
2001 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2002
2003 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2004 // Let's use the existing mechanism for the allocation
2005 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2006 if (dummy_obj != NULL) {
2007 MemRegion mr(dummy_obj, word_size);
2008 CollectedHeap::fill_with_object(mr);
2009 } else {
2010 // If we can't allocate once, we probably cannot allocate
2011 // again. Let's get out of the loop.
2012 break;
2013 }
2014 }
2015 }
2016 #endif // !PRODUCT
2017
2018 void G1CollectedHeap::increment_old_marking_cycles_started() {
2019 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2020 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2021 "Wrong marking cycle count (started: %d, completed: %d)",
2022 _old_marking_cycles_started, _old_marking_cycles_completed);
2023
2024 _old_marking_cycles_started++;
2025 }
2026
2027 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2028 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2029
2030 // We assume that if concurrent == true, then the caller is a
2031 // concurrent thread that was joined the Suspendible Thread
2032 // Set. If there's ever a cheap way to check this, we should add an
2033 // assert here.
2034
2035 // Given that this method is called at the end of a Full GC or of a
2036 // concurrent cycle, and those can be nested (i.e., a Full GC can
2037 // interrupt a concurrent cycle), the number of full collections
2038 // completed should be either one (in the case where there was no
2039 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2040 // behind the number of full collections started.
2041
2042 // This is the case for the inner caller, i.e. a Full GC.
2043 assert(concurrent ||
2044 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2045 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2046 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2047 "is inconsistent with _old_marking_cycles_completed = %u",
2048 _old_marking_cycles_started, _old_marking_cycles_completed);
2049
2050 // This is the case for the outer caller, i.e. the concurrent cycle.
2051 assert(!concurrent ||
2052 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2053 "for outer caller (concurrent cycle): "
2054 "_old_marking_cycles_started = %u "
2055 "is inconsistent with _old_marking_cycles_completed = %u",
2056 _old_marking_cycles_started, _old_marking_cycles_completed);
2057
2058 _old_marking_cycles_completed += 1;
2059
2060 // We need to clear the "in_progress" flag in the CM thread before
2061 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2062 // is set) so that if a waiter requests another System.gc() it doesn't
2063 // incorrectly see that a marking cycle is still in progress.
2064 if (concurrent) {
2065 _cm_thread->set_idle();
2066 }
2067
2068 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2069 // for a full GC to finish that their wait is over.
2070 ml.notify_all();
2071 }
2072
2073 void G1CollectedHeap::collect(GCCause::Cause cause) {
2074 try_collect(cause);
2075 }
2076
2077 // Return true if (x < y) with allowance for wraparound.
2078 static bool gc_counter_less_than(uint x, uint y) {
2079 return (x - y) > (UINT_MAX/2);
2080 }
2081
2082 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2083 // Macro so msg printing is format-checked.
2084 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2085 do { \
2086 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2087 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2088 ResourceMark rm; /* For thread name. */ \
2089 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2090 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2091 Thread::current()->name(), \
2092 GCCause::to_string(cause)); \
2093 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2094 } \
2095 } while (0)
2096
2097 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2098 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2099
2100 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2101 uint gc_counter,
2102 uint old_marking_started_before) {
2103 assert_heap_not_locked();
2104 assert(should_do_concurrent_full_gc(cause),
2105 "Non-concurrent cause %s", GCCause::to_string(cause));
2106
2107 for (uint i = 1; true; ++i) {
2108 // Try to schedule an initial-mark evacuation pause that will
2109 // start a concurrent cycle.
2110 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2111 VM_G1TryInitiateConcMark op(gc_counter,
2112 cause,
2113 policy()->max_pause_time_ms());
2114 VMThread::execute(&op);
2115
2116 // Request is trivially finished.
2117 if (cause == GCCause::_g1_periodic_collection) {
2118 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2119 return op.gc_succeeded();
2120 }
2121
2122 // If VMOp skipped initiating concurrent marking cycle because
2123 // we're terminating, then we're done.
2124 if (op.terminating()) {
2125 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2126 return false;
2127 }
2128
2129 // Lock to get consistent set of values.
2130 uint old_marking_started_after;
2131 uint old_marking_completed_after;
2132 {
2133 MutexLocker ml(Heap_lock);
2134 // Update gc_counter for retrying VMOp if needed. Captured here to be
2135 // consistent with the values we use below for termination tests. If
2136 // a retry is needed after a possible wait, and another collection
2137 // occurs in the meantime, it will cause our retry to be skipped and
2138 // we'll recheck for termination with updated conditions from that
2139 // more recent collection. That's what we want, rather than having
2140 // our retry possibly perform an unnecessary collection.
2141 gc_counter = total_collections();
2142 old_marking_started_after = _old_marking_cycles_started;
2143 old_marking_completed_after = _old_marking_cycles_completed;
2144 }
2145
2146 if (cause == GCCause::_wb_breakpoint) {
2147 if (op.gc_succeeded()) {
2148 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2149 return true;
2150 }
2151 // When _wb_breakpoint there can't be another cycle or deferred.
2152 assert(!op.cycle_already_in_progress(), "invariant");
2153 assert(!op.whitebox_attached(), "invariant");
2154 // Concurrent cycle attempt might have been cancelled by some other
2155 // collection, so retry. Unlike other cases below, we want to retry
2156 // even if cancelled by a STW full collection, because we really want
2157 // to start a concurrent cycle.
2158 if (old_marking_started_before != old_marking_started_after) {
2159 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2160 old_marking_started_before = old_marking_started_after;
2161 }
2162 } else if (!GCCause::is_user_requested_gc(cause)) {
2163 // For an "automatic" (not user-requested) collection, we just need to
2164 // ensure that progress is made.
2165 //
2166 // Request is finished if any of
2167 // (1) the VMOp successfully performed a GC,
2168 // (2) a concurrent cycle was already in progress,
2169 // (3) whitebox is controlling concurrent cycles,
2170 // (4) a new cycle was started (by this thread or some other), or
2171 // (5) a Full GC was performed.
2172 // Cases (4) and (5) are detected together by a change to
2173 // _old_marking_cycles_started.
2174 //
2175 // Note that (1) does not imply (4). If we're still in the mixed
2176 // phase of an earlier concurrent collection, the request to make the
2177 // collection an initial-mark won't be honored. If we don't check for
2178 // both conditions we'll spin doing back-to-back collections.
2179 if (op.gc_succeeded() ||
2180 op.cycle_already_in_progress() ||
2181 op.whitebox_attached() ||
2182 (old_marking_started_before != old_marking_started_after)) {
2183 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2184 return true;
2185 }
2186 } else { // User-requested GC.
2187 // For a user-requested collection, we want to ensure that a complete
2188 // full collection has been performed before returning, but without
2189 // waiting for more than needed.
2190
2191 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2192 // new cycle was started. That's good, because it's not clear what we
2193 // should do otherwise. Trying again just does back to back GCs.
2194 // Can't wait for someone else to start a cycle. And returning fails
2195 // to meet the goal of ensuring a full collection was performed.
2196 assert(!op.gc_succeeded() ||
2197 (old_marking_started_before != old_marking_started_after),
2198 "invariant: succeeded %s, started before %u, started after %u",
2199 BOOL_TO_STR(op.gc_succeeded()),
2200 old_marking_started_before, old_marking_started_after);
2201
2202 // Request is finished if a full collection (concurrent or stw)
2203 // was started after this request and has completed, e.g.
2204 // started_before < completed_after.
2205 if (gc_counter_less_than(old_marking_started_before,
2206 old_marking_completed_after)) {
2207 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2208 return true;
2209 }
2210
2211 if (old_marking_started_after != old_marking_completed_after) {
2212 // If there is an in-progress cycle (possibly started by us), then
2213 // wait for that cycle to complete, e.g.
2214 // while completed_now < started_after.
2215 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2216 MonitorLocker ml(G1OldGCCount_lock);
2217 while (gc_counter_less_than(_old_marking_cycles_completed,
2218 old_marking_started_after)) {
2219 ml.wait();
2220 }
2221 // Request is finished if the collection we just waited for was
2222 // started after this request.
2223 if (old_marking_started_before != old_marking_started_after) {
2224 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2225 return true;
2226 }
2227 }
2228
2229 // If VMOp was successful then it started a new cycle that the above
2230 // wait &etc should have recognized as finishing this request. This
2231 // differs from a non-user-request, where gc_succeeded does not imply
2232 // a new cycle was started.
2233 assert(!op.gc_succeeded(), "invariant");
2234
2235 if (op.cycle_already_in_progress()) {
2236 // If VMOp failed because a cycle was already in progress, it
2237 // is now complete. But it didn't finish this user-requested
2238 // GC, so try again.
2239 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2240 continue;
2241 } else if (op.whitebox_attached()) {
2242 // If WhiteBox wants control, wait for notification of a state
2243 // change in the controller, then try again. Don't wait for
2244 // release of control, since collections may complete while in
2245 // control. Note: This won't recognize a STW full collection
2246 // while waiting; we can't wait on multiple monitors.
2247 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2248 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2249 if (ConcurrentGCBreakpoints::is_controlled()) {
2250 ml.wait();
2251 }
2252 continue;
2253 }
2254 }
2255
2256 // Collection failed and should be retried.
2257 assert(op.transient_failure(), "invariant");
2258
2259 if (GCLocker::is_active_and_needs_gc()) {
2260 // If GCLocker is active, wait until clear before retrying.
2261 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2262 GCLocker::stall_until_clear();
2263 }
2264
2265 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2266 }
2267 }
2268
2269 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2270 assert_heap_not_locked();
2271
2272 // Lock to get consistent set of values.
2273 uint gc_count_before;
2274 uint full_gc_count_before;
2275 uint old_marking_started_before;
2276 {
2277 MutexLocker ml(Heap_lock);
2278 gc_count_before = total_collections();
2279 full_gc_count_before = total_full_collections();
2280 old_marking_started_before = _old_marking_cycles_started;
2281 }
2282
2283 if (should_do_concurrent_full_gc(cause)) {
2284 return try_collect_concurrently(cause,
2285 gc_count_before,
2286 old_marking_started_before);
2287 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2288 // Indicate failure to be consistent with VMOp failure due to
2289 // another collection slipping in after our gc_count but before
2290 // our request is processed.
2291 return false;
2292 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2293 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2294
2295 // Schedule a standard evacuation pause. We're setting word_size
2296 // to 0 which means that we are not requesting a post-GC allocation.
2297 VM_G1CollectForAllocation op(0, /* word_size */
2298 gc_count_before,
2299 cause,
2300 policy()->max_pause_time_ms());
2301 VMThread::execute(&op);
2302 return op.gc_succeeded();
2303 } else {
2304 // Schedule a Full GC.
2305 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2306 VMThread::execute(&op);
2307 return op.gc_succeeded();
2308 }
2309 }
2310
2311 bool G1CollectedHeap::is_in(const void* p) const {
2312 if (_hrm->reserved().contains(p)) {
2313 // Given that we know that p is in the reserved space,
2314 // heap_region_containing() should successfully
2315 // return the containing region.
2316 HeapRegion* hr = heap_region_containing(p);
2317 return hr->is_in(p);
2318 } else {
2319 return false;
2320 }
2321 }
2322
2323 #ifdef ASSERT
2324 bool G1CollectedHeap::is_in_exact(const void* p) const {
2325 bool contains = reserved_region().contains(p);
2326 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2327 if (contains && available) {
2328 return true;
2329 } else {
2330 return false;
2331 }
2332 }
2333 #endif
2334
2335 // Iteration functions.
2336
2337 // Iterates an ObjectClosure over all objects within a HeapRegion.
2338
2339 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2340 ObjectClosure* _cl;
2341 public:
2342 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2343 bool do_heap_region(HeapRegion* r) {
2344 if (!r->is_continues_humongous()) {
2345 r->object_iterate(_cl);
2346 }
2347 return false;
2348 }
2349 };
2350
2351 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2352 IterateObjectClosureRegionClosure blk(cl);
2353 heap_region_iterate(&blk);
2354 }
2355
2356 void G1CollectedHeap::keep_alive(oop obj) {
2357 G1BarrierSet::enqueue(obj);
2358 }
2359
2360 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2361 _hrm->iterate(cl);
2362 }
2363
2364 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2365 HeapRegionClaimer *hrclaimer,
2366 uint worker_id) const {
2367 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2368 }
2369
2370 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2371 HeapRegionClaimer *hrclaimer) const {
2372 _hrm->par_iterate(cl, hrclaimer, 0);
2373 }
2374
2375 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2376 _collection_set.iterate(cl);
2377 }
2378
2379 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2380 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2381 }
2382
2383 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2384 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2385 }
2386
2387 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2388 HeapRegion* hr = heap_region_containing(addr);
2389 return hr->block_start(addr);
2390 }
2391
2392 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2393 HeapRegion* hr = heap_region_containing(addr);
2394 return hr->block_is_obj(addr);
2395 }
2396
2397 bool G1CollectedHeap::supports_tlab_allocation() const {
2398 return true;
2399 }
2400
2401 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2402 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2403 }
2404
2405 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2406 return _eden.length() * HeapRegion::GrainBytes;
2407 }
2408
2409 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2410 // must be equal to the humongous object limit.
2411 size_t G1CollectedHeap::max_tlab_size() const {
2412 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2413 }
2414
2415 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2416 return _allocator->unsafe_max_tlab_alloc();
2417 }
2418
2419 size_t G1CollectedHeap::max_capacity() const {
2420 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2421 }
2422
2423 size_t G1CollectedHeap::max_reserved_capacity() const {
2424 return _hrm->max_length() * HeapRegion::GrainBytes;
2425 }
2426
2427 jlong G1CollectedHeap::millis_since_last_gc() {
2428 // See the notes in GenCollectedHeap::millis_since_last_gc()
2429 // for more information about the implementation.
2430 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2431 _policy->collection_pause_end_millis();
2432 if (ret_val < 0) {
2433 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2434 ". returning zero instead.", ret_val);
2435 return 0;
2436 }
2437 return ret_val;
2438 }
2439
2440 void G1CollectedHeap::deduplicate_string(oop str) {
2441 assert(java_lang_String::is_instance(str), "invariant");
2442
2443 if (G1StringDedup::is_enabled()) {
2444 G1StringDedup::deduplicate(str);
2445 }
2446 }
2447
2448 void G1CollectedHeap::prepare_for_verify() {
2449 _verifier->prepare_for_verify();
2450 }
2451
2452 void G1CollectedHeap::verify(VerifyOption vo) {
2453 _verifier->verify(vo);
2454 }
2455
2456 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2457 return true;
2458 }
2459
2460 bool G1CollectedHeap::is_heterogeneous_heap() const {
2461 return G1Arguments::is_heterogeneous_heap();
2462 }
2463
2464 class PrintRegionClosure: public HeapRegionClosure {
2465 outputStream* _st;
2466 public:
2467 PrintRegionClosure(outputStream* st) : _st(st) {}
2468 bool do_heap_region(HeapRegion* r) {
2469 r->print_on(_st);
2470 return false;
2471 }
2472 };
2473
2474 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2475 const HeapRegion* hr,
2476 const VerifyOption vo) const {
2477 switch (vo) {
2478 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2479 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2480 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2481 default: ShouldNotReachHere();
2482 }
2483 return false; // keep some compilers happy
2484 }
2485
2486 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2487 const VerifyOption vo) const {
2488 switch (vo) {
2489 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2490 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2491 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2492 default: ShouldNotReachHere();
2493 }
2494 return false; // keep some compilers happy
2495 }
2496
2497 void G1CollectedHeap::print_heap_regions() const {
2498 LogTarget(Trace, gc, heap, region) lt;
2499 if (lt.is_enabled()) {
2500 LogStream ls(lt);
2501 print_regions_on(&ls);
2502 }
2503 }
2504
2505 void G1CollectedHeap::print_on(outputStream* st) const {
2506 st->print(" %-20s", "garbage-first heap");
2507 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2508 capacity()/K, used_unlocked()/K);
2509 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2510 p2i(_hrm->reserved().start()),
2511 p2i(_hrm->reserved().end()));
2512 st->cr();
2513 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2514 uint young_regions = young_regions_count();
2515 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2516 (size_t) young_regions * HeapRegion::GrainBytes / K);
2517 uint survivor_regions = survivor_regions_count();
2518 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2519 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2520 st->cr();
2521 if (_numa->is_enabled()) {
2522 uint num_nodes = _numa->num_active_nodes();
2523 st->print(" remaining free region(s) on each NUMA node: ");
2524 const int* node_ids = _numa->node_ids();
2525 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2526 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2527 }
2528 st->cr();
2529 }
2530 MetaspaceUtils::print_on(st);
2531 }
2532
2533 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2534 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2535 "HS=humongous(starts), HC=humongous(continues), "
2536 "CS=collection set, F=free, "
2537 "OA=open archive, CA=closed archive, "
2538 "TAMS=top-at-mark-start (previous, next)");
2539 PrintRegionClosure blk(st);
2540 heap_region_iterate(&blk);
2541 }
2542
2543 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2544 print_on(st);
2545
2546 // Print the per-region information.
2547 print_regions_on(st);
2548 }
2549
2550 void G1CollectedHeap::print_on_error(outputStream* st) const {
2551 this->CollectedHeap::print_on_error(st);
2552
2553 if (_cm != NULL) {
2554 st->cr();
2555 _cm->print_on_error(st);
2556 }
2557 }
2558
2559 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2560 workers()->print_worker_threads_on(st);
2561 _cm_thread->print_on(st);
2562 st->cr();
2563 _cm->print_worker_threads_on(st);
2564 _cr->print_threads_on(st);
2565 _young_gen_sampling_thread->print_on(st);
2566 if (G1StringDedup::is_enabled()) {
2567 G1StringDedup::print_worker_threads_on(st);
2568 }
2569 }
2570
2571 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2572 workers()->threads_do(tc);
2573 tc->do_thread(_cm_thread);
2574 _cm->threads_do(tc);
2575 _cr->threads_do(tc);
2576 tc->do_thread(_young_gen_sampling_thread);
2577 if (G1StringDedup::is_enabled()) {
2578 G1StringDedup::threads_do(tc);
2579 }
2580 }
2581
2582 void G1CollectedHeap::print_tracing_info() const {
2583 rem_set()->print_summary_info();
2584 concurrent_mark()->print_summary_info();
2585 }
2586
2587 #ifndef PRODUCT
2588 // Helpful for debugging RSet issues.
2589
2590 class PrintRSetsClosure : public HeapRegionClosure {
2591 private:
2592 const char* _msg;
2593 size_t _occupied_sum;
2594
2595 public:
2596 bool do_heap_region(HeapRegion* r) {
2597 HeapRegionRemSet* hrrs = r->rem_set();
2598 size_t occupied = hrrs->occupied();
2599 _occupied_sum += occupied;
2600
2601 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2602 if (occupied == 0) {
2603 tty->print_cr(" RSet is empty");
2604 } else {
2605 hrrs->print();
2606 }
2607 tty->print_cr("----------");
2608 return false;
2609 }
2610
2611 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2612 tty->cr();
2613 tty->print_cr("========================================");
2614 tty->print_cr("%s", msg);
2615 tty->cr();
2616 }
2617
2618 ~PrintRSetsClosure() {
2619 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2620 tty->print_cr("========================================");
2621 tty->cr();
2622 }
2623 };
2624
2625 void G1CollectedHeap::print_cset_rsets() {
2626 PrintRSetsClosure cl("Printing CSet RSets");
2627 collection_set_iterate_all(&cl);
2628 }
2629
2630 void G1CollectedHeap::print_all_rsets() {
2631 PrintRSetsClosure cl("Printing All RSets");;
2632 heap_region_iterate(&cl);
2633 }
2634 #endif // PRODUCT
2635
2636 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2637 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2638 }
2639
2640 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2641
2642 size_t eden_used_bytes = _eden.used_bytes();
2643 size_t survivor_used_bytes = _survivor.used_bytes();
2644 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2645
2646 size_t eden_capacity_bytes =
2647 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2648
2649 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2650 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2651 eden_capacity_bytes, survivor_used_bytes, num_regions());
2652 }
2653
2654 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2655 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2656 stats->unused(), stats->used(), stats->region_end_waste(),
2657 stats->regions_filled(), stats->direct_allocated(),
2658 stats->failure_used(), stats->failure_waste());
2659 }
2660
2661 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2662 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2663 gc_tracer->report_gc_heap_summary(when, heap_summary);
2664
2665 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2666 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2667 }
2668
2669 G1CollectedHeap* G1CollectedHeap::heap() {
2670 CollectedHeap* heap = Universe::heap();
2671 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2672 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2673 return (G1CollectedHeap*)heap;
2674 }
2675
2676 void G1CollectedHeap::gc_prologue(bool full) {
2677 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2678
2679 // This summary needs to be printed before incrementing total collections.
2680 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2681
2682 // Update common counters.
2683 increment_total_collections(full /* full gc */);
2684 if (full || collector_state()->in_initial_mark_gc()) {
2685 increment_old_marking_cycles_started();
2686 }
2687
2688 // Fill TLAB's and such
2689 {
2690 Ticks start = Ticks::now();
2691 ensure_parsability(true);
2692 Tickspan dt = Ticks::now() - start;
2693 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2694 }
2695
2696 if (!full) {
2697 // Flush dirty card queues to qset, so later phases don't need to account
2698 // for partially filled per-thread queues and such. Not needed for full
2699 // collections, which ignore those logs.
2700 Ticks start = Ticks::now();
2701 G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2702 Tickspan dt = Ticks::now() - start;
2703 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2704 }
2705 }
2706
2707 void G1CollectedHeap::gc_epilogue(bool full) {
2708 // Update common counters.
2709 if (full) {
2710 // Update the number of full collections that have been completed.
2711 increment_old_marking_cycles_completed(false /* concurrent */);
2712 }
2713
2714 // We are at the end of the GC. Total collections has already been increased.
2715 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2716
2717 // FIXME: what is this about?
2718 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2719 // is set.
2720 #if COMPILER2_OR_JVMCI
2721 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2722 #endif
2723
2724 double start = os::elapsedTime();
2725 resize_all_tlabs();
2726 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2727
2728 MemoryService::track_memory_usage();
2729 // We have just completed a GC. Update the soft reference
2730 // policy with the new heap occupancy
2731 Universe::update_heap_info_at_gc();
2732
2733 // Print NUMA statistics.
2734 _numa->print_statistics();
2735 }
2736
2737 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2738 LogTarget(Trace, gc, heap, verify) lt;
2739
2740 if (lt.is_enabled()) {
2741 LogStream ls(lt);
2742 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2743 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2744 heap_region_iterate(&cl);
2745 }
2746 }
2747
2748 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2749 uint gc_count_before,
2750 bool* succeeded,
2751 GCCause::Cause gc_cause) {
2752 assert_heap_not_locked_and_not_at_safepoint();
2753 VM_G1CollectForAllocation op(word_size,
2754 gc_count_before,
2755 gc_cause,
2756 policy()->max_pause_time_ms());
2757 VMThread::execute(&op);
2758
2759 HeapWord* result = op.result();
2760 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2761 assert(result == NULL || ret_succeeded,
2762 "the result should be NULL if the VM did not succeed");
2763 *succeeded = ret_succeeded;
2764
2765 assert_heap_not_locked();
2766 return result;
2767 }
2768
2769 void G1CollectedHeap::do_concurrent_mark() {
2770 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2771 if (!_cm_thread->in_progress()) {
2772 _cm_thread->set_started();
2773 CGC_lock->notify();
2774 }
2775 }
2776
2777 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2778 // We don't nominate objects with many remembered set entries, on
2779 // the assumption that such objects are likely still live.
2780 HeapRegionRemSet* rem_set = r->rem_set();
2781
2782 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2783 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2784 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2785 }
2786
2787 #ifndef PRODUCT
2788 void G1CollectedHeap::verify_region_attr_remset_update() {
2789 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2790 public:
2791 virtual bool do_heap_region(HeapRegion* r) {
2792 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2793 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2794 assert(r->rem_set()->is_tracked() == needs_remset_update,
2795 "Region %u remset tracking status (%s) different to region attribute (%s)",
2796 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2797 return false;
2798 }
2799 } cl;
2800 heap_region_iterate(&cl);
2801 }
2802 #endif
2803
2804 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2805 public:
2806 bool do_heap_region(HeapRegion* hr) {
2807 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2808 hr->verify_rem_set();
2809 }
2810 return false;
2811 }
2812 };
2813
2814 uint G1CollectedHeap::num_task_queues() const {
2815 return _task_queues->size();
2816 }
2817
2818 #if TASKQUEUE_STATS
2819 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2820 st->print_raw_cr("GC Task Stats");
2821 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2822 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2823 }
2824
2825 void G1CollectedHeap::print_taskqueue_stats() const {
2826 if (!log_is_enabled(Trace, gc, task, stats)) {
2827 return;
2828 }
2829 Log(gc, task, stats) log;
2830 ResourceMark rm;
2831 LogStream ls(log.trace());
2832 outputStream* st = &ls;
2833
2834 print_taskqueue_stats_hdr(st);
2835
2836 TaskQueueStats totals;
2837 const uint n = num_task_queues();
2838 for (uint i = 0; i < n; ++i) {
2839 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2840 totals += task_queue(i)->stats;
2841 }
2842 st->print_raw("tot "); totals.print(st); st->cr();
2843
2844 DEBUG_ONLY(totals.verify());
2845 }
2846
2847 void G1CollectedHeap::reset_taskqueue_stats() {
2848 const uint n = num_task_queues();
2849 for (uint i = 0; i < n; ++i) {
2850 task_queue(i)->stats.reset();
2851 }
2852 }
2853 #endif // TASKQUEUE_STATS
2854
2855 void G1CollectedHeap::wait_for_root_region_scanning() {
2856 double scan_wait_start = os::elapsedTime();
2857 // We have to wait until the CM threads finish scanning the
2858 // root regions as it's the only way to ensure that all the
2859 // objects on them have been correctly scanned before we start
2860 // moving them during the GC.
2861 bool waited = _cm->root_regions()->wait_until_scan_finished();
2862 double wait_time_ms = 0.0;
2863 if (waited) {
2864 double scan_wait_end = os::elapsedTime();
2865 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2866 }
2867 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2868 }
2869
2870 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2871 private:
2872 G1HRPrinter* _hr_printer;
2873 public:
2874 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2875
2876 virtual bool do_heap_region(HeapRegion* r) {
2877 _hr_printer->cset(r);
2878 return false;
2879 }
2880 };
2881
2882 void G1CollectedHeap::start_new_collection_set() {
2883 double start = os::elapsedTime();
2884
2885 collection_set()->start_incremental_building();
2886
2887 clear_region_attr();
2888
2889 guarantee(_eden.length() == 0, "eden should have been cleared");
2890 policy()->transfer_survivors_to_cset(survivor());
2891
2892 // We redo the verification but now wrt to the new CSet which
2893 // has just got initialized after the previous CSet was freed.
2894 _cm->verify_no_collection_set_oops();
2895
2896 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2897 }
2898
2899 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2900
2901 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2902 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2903 collection_set()->optional_region_length());
2904
2905 _cm->verify_no_collection_set_oops();
2906
2907 if (_hr_printer.is_active()) {
2908 G1PrintCollectionSetClosure cl(&_hr_printer);
2909 _collection_set.iterate(&cl);
2910 _collection_set.iterate_optional(&cl);
2911 }
2912 }
2913
2914 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2915 if (collector_state()->in_initial_mark_gc()) {
2916 return G1HeapVerifier::G1VerifyConcurrentStart;
2917 } else if (collector_state()->in_young_only_phase()) {
2918 return G1HeapVerifier::G1VerifyYoungNormal;
2919 } else {
2920 return G1HeapVerifier::G1VerifyMixed;
2921 }
2922 }
2923
2924 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2925 if (VerifyRememberedSets) {
2926 log_info(gc, verify)("[Verifying RemSets before GC]");
2927 VerifyRegionRemSetClosure v_cl;
2928 heap_region_iterate(&v_cl);
2929 }
2930 _verifier->verify_before_gc(type);
2931 _verifier->check_bitmaps("GC Start");
2932 verify_numa_regions("GC Start");
2933 }
2934
2935 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2936 if (VerifyRememberedSets) {
2937 log_info(gc, verify)("[Verifying RemSets after GC]");
2938 VerifyRegionRemSetClosure v_cl;
2939 heap_region_iterate(&v_cl);
2940 }
2941 _verifier->verify_after_gc(type);
2942 _verifier->check_bitmaps("GC End");
2943 verify_numa_regions("GC End");
2944 }
2945
2946 void G1CollectedHeap::expand_heap_after_young_collection(){
2947 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2948 if (expand_bytes > 0) {
2949 // No need for an ergo logging here,
2950 // expansion_amount() does this when it returns a value > 0.
2951 double expand_ms;
2952 if (!expand(expand_bytes, _workers, &expand_ms)) {
2953 // We failed to expand the heap. Cannot do anything about it.
2954 }
2955 phase_times()->record_expand_heap_time(expand_ms);
2956 }
2957 }
2958
2959 const char* G1CollectedHeap::young_gc_name() const {
2960 if (collector_state()->in_initial_mark_gc()) {
2961 return "Pause Young (Concurrent Start)";
2962 } else if (collector_state()->in_young_only_phase()) {
2963 if (collector_state()->in_young_gc_before_mixed()) {
2964 return "Pause Young (Prepare Mixed)";
2965 } else {
2966 return "Pause Young (Normal)";
2967 }
2968 } else {
2969 return "Pause Young (Mixed)";
2970 }
2971 }
2972
2973 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2974 assert_at_safepoint_on_vm_thread();
2975 guarantee(!is_gc_active(), "collection is not reentrant");
2976
2977 if (GCLocker::check_active_before_gc()) {
2978 return false;
2979 }
2980
2981 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2982 if (should_upgrade_to_full_gc(gc_cause())) {
2983 log_info(gc, ergo)("Attempting maximally compacting collection");
2984 bool result = do_full_collection(false /* explicit gc */,
2985 true /* clear_all_soft_refs */);
2986 // do_full_collection only fails if blocked by GC locker, but
2987 // we've already checked for that above.
2988 assert(result, "invariant");
2989 }
2990 return true;
2991 }
2992
2993 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2994 GCIdMark gc_id_mark;
2995
2996 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2997 ResourceMark rm;
2998
2999 policy()->note_gc_start();
3000
3001 _gc_timer_stw->register_gc_start();
3002 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3003
3004 wait_for_root_region_scanning();
3005
3006 print_heap_before_gc();
3007 print_heap_regions();
3008 trace_heap_before_gc(_gc_tracer_stw);
3009
3010 _verifier->verify_region_sets_optional();
3011 _verifier->verify_dirty_young_regions();
3012
3013 // We should not be doing initial mark unless the conc mark thread is running
3014 if (!_cm_thread->should_terminate()) {
3015 // This call will decide whether this pause is an initial-mark
3016 // pause. If it is, in_initial_mark_gc() will return true
3017 // for the duration of this pause.
3018 policy()->decide_on_conc_mark_initiation();
3019 }
3020
3021 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3022 assert(!collector_state()->in_initial_mark_gc() ||
3023 collector_state()->in_young_only_phase(), "sanity");
3024 // We also do not allow mixed GCs during marking.
3025 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3026
3027 // Record whether this pause is an initial mark. When the current
3028 // thread has completed its logging output and it's safe to signal
3029 // the CM thread, the flag's value in the policy has been reset.
3030 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3031 if (should_start_conc_mark) {
3032 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3033 }
3034
3035 // Inner scope for scope based logging, timers, and stats collection
3036 {
3037 G1EvacuationInfo evacuation_info;
3038
3039 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3040
3041 GCTraceCPUTime tcpu;
3042
3043 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3044
3045 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3046 workers()->active_workers(),
3047 Threads::number_of_non_daemon_threads());
3048 active_workers = workers()->update_active_workers(active_workers);
3049 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3050
3051 G1MonitoringScope ms(g1mm(),
3052 false /* full_gc */,
3053 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3054
3055 G1HeapTransition heap_transition(this);
3056
3057 {
3058 IsGCActiveMark x;
3059
3060 gc_prologue(false);
3061
3062 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3063 verify_before_young_collection(verify_type);
3064
3065 {
3066 // The elapsed time induced by the start time below deliberately elides
3067 // the possible verification above.
3068 double sample_start_time_sec = os::elapsedTime();
3069
3070 // Please see comment in g1CollectedHeap.hpp and
3071 // G1CollectedHeap::ref_processing_init() to see how
3072 // reference processing currently works in G1.
3073 _ref_processor_stw->enable_discovery();
3074
3075 // We want to temporarily turn off discovery by the
3076 // CM ref processor, if necessary, and turn it back on
3077 // on again later if we do. Using a scoped
3078 // NoRefDiscovery object will do this.
3079 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3080
3081 policy()->record_collection_pause_start(sample_start_time_sec);
3082
3083 // Forget the current allocation region (we might even choose it to be part
3084 // of the collection set!).
3085 _allocator->release_mutator_alloc_regions();
3086
3087 calculate_collection_set(evacuation_info, target_pause_time_ms);
3088
3089 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3090 G1ParScanThreadStateSet per_thread_states(this,
3091 &rdcqs,
3092 workers()->active_workers(),
3093 collection_set()->young_region_length(),
3094 collection_set()->optional_region_length());
3095 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3096
3097 // Actually do the work...
3098 evacuate_initial_collection_set(&per_thread_states);
3099
3100 if (_collection_set.optional_region_length() != 0) {
3101 evacuate_optional_collection_set(&per_thread_states);
3102 }
3103 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3104
3105 start_new_collection_set();
3106
3107 _survivor_evac_stats.adjust_desired_plab_sz();
3108 _old_evac_stats.adjust_desired_plab_sz();
3109
3110 if (should_start_conc_mark) {
3111 // We have to do this before we notify the CM threads that
3112 // they can start working to make sure that all the
3113 // appropriate initialization is done on the CM object.
3114 concurrent_mark()->post_initial_mark();
3115 // Note that we don't actually trigger the CM thread at
3116 // this point. We do that later when we're sure that
3117 // the current thread has completed its logging output.
3118 }
3119
3120 allocate_dummy_regions();
3121
3122 _allocator->init_mutator_alloc_regions();
3123
3124 expand_heap_after_young_collection();
3125
3126 double sample_end_time_sec = os::elapsedTime();
3127 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3128 policy()->record_collection_pause_end(pause_time_ms);
3129 }
3130
3131 verify_after_young_collection(verify_type);
3132
3133 gc_epilogue(false);
3134 }
3135
3136 // Print the remainder of the GC log output.
3137 if (evacuation_failed()) {
3138 log_info(gc)("To-space exhausted");
3139 }
3140
3141 policy()->print_phases();
3142 heap_transition.print();
3143
3144 _hrm->verify_optional();
3145 _verifier->verify_region_sets_optional();
3146
3147 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3148 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3149
3150 print_heap_after_gc();
3151 print_heap_regions();
3152 trace_heap_after_gc(_gc_tracer_stw);
3153
3154 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3155 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3156 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3157 // before any GC notifications are raised.
3158 g1mm()->update_sizes();
3159
3160 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3161 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3162 _gc_timer_stw->register_gc_end();
3163 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3164 }
3165 // It should now be safe to tell the concurrent mark thread to start
3166 // without its logging output interfering with the logging output
3167 // that came from the pause.
3168
3169 if (should_start_conc_mark) {
3170 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3171 // thread(s) could be running concurrently with us. Make sure that anything
3172 // after this point does not assume that we are the only GC thread running.
3173 // Note: of course, the actual marking work will not start until the safepoint
3174 // itself is released in SuspendibleThreadSet::desynchronize().
3175 do_concurrent_mark();
3176 ConcurrentGCBreakpoints::notify_idle_to_active();
3177 }
3178 }
3179
3180 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3181 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3182 workers()->run_task(&rsfp_task);
3183 }
3184
3185 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3186 double remove_self_forwards_start = os::elapsedTime();
3187
3188 remove_self_forwarding_pointers(rdcqs);
3189 _preserved_marks_set.restore(workers());
3190
3191 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3192 }
3193
3194 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3195 if (!_evacuation_failed) {
3196 _evacuation_failed = true;
3197 }
3198
3199 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3200 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3201 }
3202
3203 bool G1ParEvacuateFollowersClosure::offer_termination() {
3204 EventGCPhaseParallel event;
3205 G1ParScanThreadState* const pss = par_scan_state();
3206 start_term_time();
3207 const bool res = terminator()->offer_termination();
3208 end_term_time();
3209 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3210 return res;
3211 }
3212
3213 void G1ParEvacuateFollowersClosure::do_void() {
3214 EventGCPhaseParallel event;
3215 G1ParScanThreadState* const pss = par_scan_state();
3216 pss->trim_queue();
3217 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3218 do {
3219 EventGCPhaseParallel event;
3220 pss->steal_and_trim_queue(queues());
3221 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3222 } while (!offer_termination());
3223 }
3224
3225 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3226 bool class_unloading_occurred) {
3227 uint num_workers = workers()->active_workers();
3228 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3229 workers()->run_task(&unlink_task);
3230 }
3231
3232 // Clean string dedup data structures.
3233 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3234 // record the durations of the phases. Hence the almost-copy.
3235 class G1StringDedupCleaningTask : public AbstractGangTask {
3236 BoolObjectClosure* _is_alive;
3237 OopClosure* _keep_alive;
3238 G1GCPhaseTimes* _phase_times;
3239
3240 public:
3241 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3242 OopClosure* keep_alive,
3243 G1GCPhaseTimes* phase_times) :
3244 AbstractGangTask("Partial Cleaning Task"),
3245 _is_alive(is_alive),
3246 _keep_alive(keep_alive),
3247 _phase_times(phase_times)
3248 {
3249 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3250 StringDedup::gc_prologue(true);
3251 }
3252
3253 ~G1StringDedupCleaningTask() {
3254 StringDedup::gc_epilogue();
3255 }
3256
3257 void work(uint worker_id) {
3258 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3259 {
3260 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3261 StringDedupQueue::unlink_or_oops_do(&cl);
3262 }
3263 {
3264 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3265 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3266 }
3267 }
3268 };
3269
3270 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3271 OopClosure* keep_alive,
3272 G1GCPhaseTimes* phase_times) {
3273 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3274 workers()->run_task(&cl);
3275 }
3276
3277 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3278 private:
3279 G1RedirtyCardsQueueSet* _qset;
3280 G1CollectedHeap* _g1h;
3281 BufferNode* volatile _nodes;
3282
3283 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3284 size_t buffer_size = _qset->buffer_size();
3285 BufferNode* next = Atomic::load(&_nodes);
3286 while (next != NULL) {
3287 BufferNode* node = next;
3288 next = Atomic::cmpxchg(&_nodes, node, node->next());
3289 if (next == node) {
3290 cl->apply_to_buffer(node, buffer_size, worker_id);
3291 next = node->next();
3292 }
3293 }
3294 }
3295
3296 public:
3297 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3298 AbstractGangTask("Redirty Cards"),
3299 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3300
3301 virtual void work(uint worker_id) {
3302 G1GCPhaseTimes* p = _g1h->phase_times();
3303 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3304
3305 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3306 par_apply(&cl, worker_id);
3307
3308 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3309 }
3310 };
3311
3312 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3313 double redirty_logged_cards_start = os::elapsedTime();
3314
3315 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3316 workers()->run_task(&redirty_task);
3317
3318 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3319 dcq.merge_bufferlists(rdcqs);
3320
3321 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3322 }
3323
3324 // Weak Reference Processing support
3325
3326 bool G1STWIsAliveClosure::do_object_b(oop p) {
3327 // An object is reachable if it is outside the collection set,
3328 // or is inside and copied.
3329 return !_g1h->is_in_cset(p) || p->is_forwarded();
3330 }
3331
3332 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3333 assert(obj != NULL, "must not be NULL");
3334 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3335 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3336 // may falsely indicate that this is not the case here: however the collection set only
3337 // contains old regions when concurrent mark is not running.
3338 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3339 }
3340
3341 // Non Copying Keep Alive closure
3342 class G1KeepAliveClosure: public OopClosure {
3343 G1CollectedHeap*_g1h;
3344 public:
3345 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3346 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3347 void do_oop(oop* p) {
3348 oop obj = *p;
3349 assert(obj != NULL, "the caller should have filtered out NULL values");
3350
3351 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3352 if (!region_attr.is_in_cset_or_humongous()) {
3353 return;
3354 }
3355 if (region_attr.is_in_cset()) {
3356 assert( obj->is_forwarded(), "invariant" );
3357 *p = obj->forwardee();
3358 } else {
3359 assert(!obj->is_forwarded(), "invariant" );
3360 assert(region_attr.is_humongous(),
3361 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3362 _g1h->set_humongous_is_live(obj);
3363 }
3364 }
3365 };
3366
3367 // Copying Keep Alive closure - can be called from both
3368 // serial and parallel code as long as different worker
3369 // threads utilize different G1ParScanThreadState instances
3370 // and different queues.
3371
3372 class G1CopyingKeepAliveClosure: public OopClosure {
3373 G1CollectedHeap* _g1h;
3374 G1ParScanThreadState* _par_scan_state;
3375
3376 public:
3377 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3378 G1ParScanThreadState* pss):
3379 _g1h(g1h),
3380 _par_scan_state(pss)
3381 {}
3382
3383 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3384 virtual void do_oop( oop* p) { do_oop_work(p); }
3385
3386 template <class T> void do_oop_work(T* p) {
3387 oop obj = RawAccess<>::oop_load(p);
3388
3389 if (_g1h->is_in_cset_or_humongous(obj)) {
3390 // If the referent object has been forwarded (either copied
3391 // to a new location or to itself in the event of an
3392 // evacuation failure) then we need to update the reference
3393 // field and, if both reference and referent are in the G1
3394 // heap, update the RSet for the referent.
3395 //
3396 // If the referent has not been forwarded then we have to keep
3397 // it alive by policy. Therefore we have copy the referent.
3398 //
3399 // When the queue is drained (after each phase of reference processing)
3400 // the object and it's followers will be copied, the reference field set
3401 // to point to the new location, and the RSet updated.
3402 _par_scan_state->push_on_queue(p);
3403 }
3404 }
3405 };
3406
3407 // Serial drain queue closure. Called as the 'complete_gc'
3408 // closure for each discovered list in some of the
3409 // reference processing phases.
3410
3411 class G1STWDrainQueueClosure: public VoidClosure {
3412 protected:
3413 G1CollectedHeap* _g1h;
3414 G1ParScanThreadState* _par_scan_state;
3415
3416 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3417
3418 public:
3419 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3420 _g1h(g1h),
3421 _par_scan_state(pss)
3422 { }
3423
3424 void do_void() {
3425 G1ParScanThreadState* const pss = par_scan_state();
3426 pss->trim_queue();
3427 }
3428 };
3429
3430 // Parallel Reference Processing closures
3431
3432 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3433 // processing during G1 evacuation pauses.
3434
3435 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3436 private:
3437 G1CollectedHeap* _g1h;
3438 G1ParScanThreadStateSet* _pss;
3439 RefToScanQueueSet* _queues;
3440 WorkGang* _workers;
3441
3442 public:
3443 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3444 G1ParScanThreadStateSet* per_thread_states,
3445 WorkGang* workers,
3446 RefToScanQueueSet *task_queues) :
3447 _g1h(g1h),
3448 _pss(per_thread_states),
3449 _queues(task_queues),
3450 _workers(workers)
3451 {
3452 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3453 }
3454
3455 // Executes the given task using concurrent marking worker threads.
3456 virtual void execute(ProcessTask& task, uint ergo_workers);
3457 };
3458
3459 // Gang task for possibly parallel reference processing
3460
3461 class G1STWRefProcTaskProxy: public AbstractGangTask {
3462 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3463 ProcessTask& _proc_task;
3464 G1CollectedHeap* _g1h;
3465 G1ParScanThreadStateSet* _pss;
3466 RefToScanQueueSet* _task_queues;
3467 TaskTerminator* _terminator;
3468
3469 public:
3470 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3471 G1CollectedHeap* g1h,
3472 G1ParScanThreadStateSet* per_thread_states,
3473 RefToScanQueueSet *task_queues,
3474 TaskTerminator* terminator) :
3475 AbstractGangTask("Process reference objects in parallel"),
3476 _proc_task(proc_task),
3477 _g1h(g1h),
3478 _pss(per_thread_states),
3479 _task_queues(task_queues),
3480 _terminator(terminator)
3481 {}
3482
3483 virtual void work(uint worker_id) {
3484 // The reference processing task executed by a single worker.
3485 ResourceMark rm;
3486 HandleMark hm;
3487
3488 G1STWIsAliveClosure is_alive(_g1h);
3489
3490 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3491 pss->set_ref_discoverer(NULL);
3492
3493 // Keep alive closure.
3494 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3495
3496 // Complete GC closure
3497 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3498
3499 // Call the reference processing task's work routine.
3500 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3501
3502 // Note we cannot assert that the refs array is empty here as not all
3503 // of the processing tasks (specifically phase2 - pp2_work) execute
3504 // the complete_gc closure (which ordinarily would drain the queue) so
3505 // the queue may not be empty.
3506 }
3507 };
3508
3509 // Driver routine for parallel reference processing.
3510 // Creates an instance of the ref processing gang
3511 // task and has the worker threads execute it.
3512 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3513 assert(_workers != NULL, "Need parallel worker threads.");
3514
3515 assert(_workers->active_workers() >= ergo_workers,
3516 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3517 ergo_workers, _workers->active_workers());
3518 TaskTerminator terminator(ergo_workers, _queues);
3519 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3520
3521 _workers->run_task(&proc_task_proxy, ergo_workers);
3522 }
3523
3524 // End of weak reference support closures
3525
3526 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3527 double ref_proc_start = os::elapsedTime();
3528
3529 ReferenceProcessor* rp = _ref_processor_stw;
3530 assert(rp->discovery_enabled(), "should have been enabled");
3531
3532 // Closure to test whether a referent is alive.
3533 G1STWIsAliveClosure is_alive(this);
3534
3535 // Even when parallel reference processing is enabled, the processing
3536 // of JNI refs is serial and performed serially by the current thread
3537 // rather than by a worker. The following PSS will be used for processing
3538 // JNI refs.
3539
3540 // Use only a single queue for this PSS.
3541 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3542 pss->set_ref_discoverer(NULL);
3543 assert(pss->queue_is_empty(), "pre-condition");
3544
3545 // Keep alive closure.
3546 G1CopyingKeepAliveClosure keep_alive(this, pss);
3547
3548 // Serial Complete GC closure
3549 G1STWDrainQueueClosure drain_queue(this, pss);
3550
3551 // Setup the soft refs policy...
3552 rp->setup_policy(false);
3553
3554 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3555
3556 ReferenceProcessorStats stats;
3557 if (!rp->processing_is_mt()) {
3558 // Serial reference processing...
3559 stats = rp->process_discovered_references(&is_alive,
3560 &keep_alive,
3561 &drain_queue,
3562 NULL,
3563 pt);
3564 } else {
3565 uint no_of_gc_workers = workers()->active_workers();
3566
3567 // Parallel reference processing
3568 assert(no_of_gc_workers <= rp->max_num_queues(),
3569 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3570 no_of_gc_workers, rp->max_num_queues());
3571
3572 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3573 stats = rp->process_discovered_references(&is_alive,
3574 &keep_alive,
3575 &drain_queue,
3576 &par_task_executor,
3577 pt);
3578 }
3579
3580 _gc_tracer_stw->report_gc_reference_stats(stats);
3581
3582 // We have completed copying any necessary live referent objects.
3583 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3584
3585 make_pending_list_reachable();
3586
3587 assert(!rp->discovery_enabled(), "Postcondition");
3588 rp->verify_no_references_recorded();
3589
3590 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3591 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3592 }
3593
3594 void G1CollectedHeap::make_pending_list_reachable() {
3595 if (collector_state()->in_initial_mark_gc()) {
3596 oop pll_head = Universe::reference_pending_list();
3597 if (pll_head != NULL) {
3598 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3599 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3600 }
3601 }
3602 }
3603
3604 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3605 Ticks start = Ticks::now();
3606 per_thread_states->flush();
3607 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3608 }
3609
3610 class G1PrepareEvacuationTask : public AbstractGangTask {
3611 class G1PrepareRegionsClosure : public HeapRegionClosure {
3612 G1CollectedHeap* _g1h;
3613 G1PrepareEvacuationTask* _parent_task;
3614 size_t _worker_humongous_total;
3615 size_t _worker_humongous_candidates;
3616
3617 bool humongous_region_is_candidate(HeapRegion* region) const {
3618 assert(region->is_starts_humongous(), "Must start a humongous object");
3619
3620 oop obj = oop(region->bottom());
3621
3622 // Dead objects cannot be eager reclaim candidates. Due to class
3623 // unloading it is unsafe to query their classes so we return early.
3624 if (_g1h->is_obj_dead(obj, region)) {
3625 return false;
3626 }
3627
3628 // If we do not have a complete remembered set for the region, then we can
3629 // not be sure that we have all references to it.
3630 if (!region->rem_set()->is_complete()) {
3631 return false;
3632 }
3633 // Candidate selection must satisfy the following constraints
3634 // while concurrent marking is in progress:
3635 //
3636 // * In order to maintain SATB invariants, an object must not be
3637 // reclaimed if it was allocated before the start of marking and
3638 // has not had its references scanned. Such an object must have
3639 // its references (including type metadata) scanned to ensure no
3640 // live objects are missed by the marking process. Objects
3641 // allocated after the start of concurrent marking don't need to
3642 // be scanned.
3643 //
3644 // * An object must not be reclaimed if it is on the concurrent
3645 // mark stack. Objects allocated after the start of concurrent
3646 // marking are never pushed on the mark stack.
3647 //
3648 // Nominating only objects allocated after the start of concurrent
3649 // marking is sufficient to meet both constraints. This may miss
3650 // some objects that satisfy the constraints, but the marking data
3651 // structures don't support efficiently performing the needed
3652 // additional tests or scrubbing of the mark stack.
3653 //
3654 // However, we presently only nominate is_typeArray() objects.
3655 // A humongous object containing references induces remembered
3656 // set entries on other regions. In order to reclaim such an
3657 // object, those remembered sets would need to be cleaned up.
3658 //
3659 // We also treat is_typeArray() objects specially, allowing them
3660 // to be reclaimed even if allocated before the start of
3661 // concurrent mark. For this we rely on mark stack insertion to
3662 // exclude is_typeArray() objects, preventing reclaiming an object
3663 // that is in the mark stack. We also rely on the metadata for
3664 // such objects to be built-in and so ensured to be kept live.
3665 // Frequent allocation and drop of large binary blobs is an
3666 // important use case for eager reclaim, and this special handling
3667 // may reduce needed headroom.
3668
3669 return obj->is_typeArray() &&
3670 _g1h->is_potential_eager_reclaim_candidate(region);
3671 }
3672
3673 public:
3674 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3675 _g1h(g1h),
3676 _parent_task(parent_task),
3677 _worker_humongous_total(0),
3678 _worker_humongous_candidates(0) { }
3679
3680 ~G1PrepareRegionsClosure() {
3681 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3682 _parent_task->add_humongous_total(_worker_humongous_total);
3683 }
3684
3685 virtual bool do_heap_region(HeapRegion* hr) {
3686 // First prepare the region for scanning
3687 _g1h->rem_set()->prepare_region_for_scan(hr);
3688
3689 // Now check if region is a humongous candidate
3690 if (!hr->is_starts_humongous()) {
3691 _g1h->register_region_with_region_attr(hr);
3692 return false;
3693 }
3694
3695 uint index = hr->hrm_index();
3696 if (humongous_region_is_candidate(hr)) {
3697 _g1h->set_humongous_reclaim_candidate(index, true);
3698 _g1h->register_humongous_region_with_region_attr(index);
3699 _worker_humongous_candidates++;
3700 // We will later handle the remembered sets of these regions.
3701 } else {
3702 _g1h->set_humongous_reclaim_candidate(index, false);
3703 _g1h->register_region_with_region_attr(hr);
3704 }
3705 _worker_humongous_total++;
3706
3707 return false;
3708 }
3709 };
3710
3711 G1CollectedHeap* _g1h;
3712 HeapRegionClaimer _claimer;
3713 volatile size_t _humongous_total;
3714 volatile size_t _humongous_candidates;
3715 public:
3716 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3717 AbstractGangTask("Prepare Evacuation"),
3718 _g1h(g1h),
3719 _claimer(_g1h->workers()->active_workers()),
3720 _humongous_total(0),
3721 _humongous_candidates(0) { }
3722
3723 ~G1PrepareEvacuationTask() {
3724 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3725 }
3726
3727 void work(uint worker_id) {
3728 G1PrepareRegionsClosure cl(_g1h, this);
3729 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3730 }
3731
3732 void add_humongous_candidates(size_t candidates) {
3733 Atomic::add(&_humongous_candidates, candidates);
3734 }
3735
3736 void add_humongous_total(size_t total) {
3737 Atomic::add(&_humongous_total, total);
3738 }
3739
3740 size_t humongous_candidates() {
3741 return _humongous_candidates;
3742 }
3743
3744 size_t humongous_total() {
3745 return _humongous_total;
3746 }
3747 };
3748
3749 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3750 _bytes_used_during_gc = 0;
3751
3752 _expand_heap_after_alloc_failure = true;
3753 _evacuation_failed = false;
3754
3755 // Disable the hot card cache.
3756 _hot_card_cache->reset_hot_cache_claimed_index();
3757 _hot_card_cache->set_use_cache(false);
3758
3759 // Initialize the GC alloc regions.
3760 _allocator->init_gc_alloc_regions(evacuation_info);
3761
3762 {
3763 Ticks start = Ticks::now();
3764 rem_set()->prepare_for_scan_heap_roots();
3765 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3766 }
3767
3768 {
3769 G1PrepareEvacuationTask g1_prep_task(this);
3770 Tickspan task_time = run_task(&g1_prep_task);
3771
3772 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3773 g1_prep_task.humongous_total(),
3774 g1_prep_task.humongous_candidates());
3775 }
3776
3777 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3778 _preserved_marks_set.assert_empty();
3779
3780 #if COMPILER2_OR_JVMCI
3781 DerivedPointerTable::clear();
3782 #endif
3783
3784 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3785 if (collector_state()->in_initial_mark_gc()) {
3786 concurrent_mark()->pre_initial_mark();
3787
3788 double start_clear_claimed_marks = os::elapsedTime();
3789
3790 ClassLoaderDataGraph::clear_claimed_marks();
3791
3792 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3793 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3794 }
3795
3796 // Should G1EvacuationFailureALot be in effect for this GC?
3797 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3798 }
3799
3800 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3801 protected:
3802 G1CollectedHeap* _g1h;
3803 G1ParScanThreadStateSet* _per_thread_states;
3804 RefToScanQueueSet* _task_queues;
3805 TaskTerminator _terminator;
3806 uint _num_workers;
3807
3808 void evacuate_live_objects(G1ParScanThreadState* pss,
3809 uint worker_id,
3810 G1GCPhaseTimes::GCParPhases objcopy_phase,
3811 G1GCPhaseTimes::GCParPhases termination_phase) {
3812 G1GCPhaseTimes* p = _g1h->phase_times();
3813
3814 Ticks start = Ticks::now();
3815 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3816 cl.do_void();
3817
3818 assert(pss->queue_is_empty(), "should be empty");
3819
3820 Tickspan evac_time = (Ticks::now() - start);
3821 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3822
3823 if (termination_phase == G1GCPhaseTimes::Termination) {
3824 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3825 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3826 } else {
3827 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3828 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3829 }
3830 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3831 }
3832
3833 virtual void start_work(uint worker_id) { }
3834
3835 virtual void end_work(uint worker_id) { }
3836
3837 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3838
3839 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3840
3841 public:
3842 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3843 AbstractGangTask(name),
3844 _g1h(G1CollectedHeap::heap()),
3845 _per_thread_states(per_thread_states),
3846 _task_queues(task_queues),
3847 _terminator(num_workers, _task_queues),
3848 _num_workers(num_workers)
3849 { }
3850
3851 void work(uint worker_id) {
3852 start_work(worker_id);
3853
3854 {
3855 ResourceMark rm;
3856 HandleMark hm;
3857
3858 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3859 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3860
3861 scan_roots(pss, worker_id);
3862 evacuate_live_objects(pss, worker_id);
3863 }
3864
3865 end_work(worker_id);
3866 }
3867 };
3868
3869 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3870 G1RootProcessor* _root_processor;
3871
3872 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3873 _root_processor->evacuate_roots(pss, worker_id);
3874 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3875 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3876 }
3877
3878 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3879 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3880 }
3881
3882 void start_work(uint worker_id) {
3883 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3884 }
3885
3886 void end_work(uint worker_id) {
3887 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3888 }
3889
3890 public:
3891 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3892 G1ParScanThreadStateSet* per_thread_states,
3893 RefToScanQueueSet* task_queues,
3894 G1RootProcessor* root_processor,
3895 uint num_workers) :
3896 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3897 _root_processor(root_processor)
3898 { }
3899 };
3900
3901 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3902 G1GCPhaseTimes* p = phase_times();
3903
3904 {
3905 Ticks start = Ticks::now();
3906 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3907 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3908 }
3909
3910 Tickspan task_time;
3911 const uint num_workers = workers()->active_workers();
3912
3913 Ticks start_processing = Ticks::now();
3914 {
3915 G1RootProcessor root_processor(this, num_workers);
3916 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3917 task_time = run_task(&g1_par_task);
3918 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3919 // To extract its code root fixup time we measure total time of this scope and
3920 // subtract from the time the WorkGang task took.
3921 }
3922 Tickspan total_processing = Ticks::now() - start_processing;
3923
3924 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3925 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3926 }
3927
3928 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3929
3930 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3931 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3932 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3933 }
3934
3935 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3936 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3937 }
3938
3939 public:
3940 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3941 RefToScanQueueSet* queues,
3942 uint num_workers) :
3943 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3944 }
3945 };
3946
3947 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3948 class G1MarkScope : public MarkScope { };
3949
3950 Tickspan task_time;
3951
3952 Ticks start_processing = Ticks::now();
3953 {
3954 G1MarkScope code_mark_scope;
3955 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3956 task_time = run_task(&task);
3957 // See comment in evacuate_collection_set() for the reason of the scope.
3958 }
3959 Tickspan total_processing = Ticks::now() - start_processing;
3960
3961 G1GCPhaseTimes* p = phase_times();
3962 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3963 }
3964
3965 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3966 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3967
3968 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3969
3970 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3971 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3972
3973 if (time_left_ms < 0 ||
3974 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3975 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3976 _collection_set.optional_region_length(), time_left_ms);
3977 break;
3978 }
3979
3980 {
3981 Ticks start = Ticks::now();
3982 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3983 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3984 }
3985
3986 {
3987 Ticks start = Ticks::now();
3988 evacuate_next_optional_regions(per_thread_states);
3989 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3990 }
3991 }
3992
3993 _collection_set.abandon_optional_collection_set(per_thread_states);
3994 }
3995
3996 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3997 G1RedirtyCardsQueueSet* rdcqs,
3998 G1ParScanThreadStateSet* per_thread_states) {
3999 G1GCPhaseTimes* p = phase_times();
4000
4001 rem_set()->cleanup_after_scan_heap_roots();
4002
4003 // Process any discovered reference objects - we have
4004 // to do this _before_ we retire the GC alloc regions
4005 // as we may have to copy some 'reachable' referent
4006 // objects (and their reachable sub-graphs) that were
4007 // not copied during the pause.
4008 process_discovered_references(per_thread_states);
4009
4010 G1STWIsAliveClosure is_alive(this);
4011 G1KeepAliveClosure keep_alive(this);
4012
4013 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4014
4015 if (G1StringDedup::is_enabled()) {
4016 double string_dedup_time_ms = os::elapsedTime();
4017
4018 string_dedup_cleaning(&is_alive, &keep_alive, p);
4019
4020 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4021 p->record_string_deduplication_time(string_cleanup_time_ms);
4022 }
4023
4024 _allocator->release_gc_alloc_regions(evacuation_info);
4025
4026 if (evacuation_failed()) {
4027 restore_after_evac_failure(rdcqs);
4028
4029 // Reset the G1EvacuationFailureALot counters and flags
4030 NOT_PRODUCT(reset_evacuation_should_fail();)
4031
4032 double recalculate_used_start = os::elapsedTime();
4033 set_used(recalculate_used());
4034 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4035
4036 if (_archive_allocator != NULL) {
4037 _archive_allocator->clear_used();
4038 }
4039 for (uint i = 0; i < ParallelGCThreads; i++) {
4040 if (_evacuation_failed_info_array[i].has_failed()) {
4041 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4042 }
4043 }
4044 } else {
4045 // The "used" of the the collection set have already been subtracted
4046 // when they were freed. Add in the bytes used.
4047 increase_used(_bytes_used_during_gc);
4048 }
4049
4050 _preserved_marks_set.assert_empty();
4051
4052 merge_per_thread_state_info(per_thread_states);
4053
4054 // Reset and re-enable the hot card cache.
4055 // Note the counts for the cards in the regions in the
4056 // collection set are reset when the collection set is freed.
4057 _hot_card_cache->reset_hot_cache();
4058 _hot_card_cache->set_use_cache(true);
4059
4060 purge_code_root_memory();
4061
4062 redirty_logged_cards(rdcqs);
4063
4064 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4065
4066 eagerly_reclaim_humongous_regions();
4067
4068 record_obj_copy_mem_stats();
4069
4070 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4071 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4072
4073 #if COMPILER2_OR_JVMCI
4074 double start = os::elapsedTime();
4075 DerivedPointerTable::update_pointers();
4076 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4077 #endif
4078 policy()->print_age_table();
4079 }
4080
4081 void G1CollectedHeap::record_obj_copy_mem_stats() {
4082 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4083
4084 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4085 create_g1_evac_summary(&_old_evac_stats));
4086 }
4087
4088 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4089 assert(!hr->is_free(), "the region should not be free");
4090 assert(!hr->is_empty(), "the region should not be empty");
4091 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4092
4093 if (G1VerifyBitmaps) {
4094 MemRegion mr(hr->bottom(), hr->end());
4095 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4096 }
4097
4098 // Clear the card counts for this region.
4099 // Note: we only need to do this if the region is not young
4100 // (since we don't refine cards in young regions).
4101 if (!hr->is_young()) {
4102 _hot_card_cache->reset_card_counts(hr);
4103 }
4104
4105 // Reset region metadata to allow reuse.
4106 hr->hr_clear(true /* clear_space */);
4107 _policy->remset_tracker()->update_at_free(hr);
4108
4109 if (free_list != NULL) {
4110 free_list->add_ordered(hr);
4111 }
4112 }
4113
4114 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4115 FreeRegionList* free_list) {
4116 assert(hr->is_humongous(), "this is only for humongous regions");
4117 assert(free_list != NULL, "pre-condition");
4118 hr->clear_humongous();
4119 free_region(hr, free_list);
4120 }
4121
4122 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4123 const uint humongous_regions_removed) {
4124 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4125 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4126 _old_set.bulk_remove(old_regions_removed);
4127 _humongous_set.bulk_remove(humongous_regions_removed);
4128 }
4129
4130 }
4131
4132 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4133 assert(list != NULL, "list can't be null");
4134 if (!list->is_empty()) {
4135 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4136 _hrm->insert_list_into_free_list(list);
4137 }
4138 }
4139
4140 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4141 decrease_used(bytes);
4142 }
4143
4144 class G1FreeCollectionSetTask : public AbstractGangTask {
4145 // Helper class to keep statistics for the collection set freeing
4146 class FreeCSetStats {
4147 size_t _before_used_bytes; // Usage in regions successfully evacutate
4148 size_t _after_used_bytes; // Usage in regions failing evacuation
4149 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4150 size_t _failure_used_words; // Live size in failed regions
4151 size_t _failure_waste_words; // Wasted size in failed regions
4152 size_t _rs_length; // Remembered set size
4153 uint _regions_freed; // Number of regions freed
4154 public:
4155 FreeCSetStats() :
4156 _before_used_bytes(0),
4157 _after_used_bytes(0),
4158 _bytes_allocated_in_old_since_last_gc(0),
4159 _failure_used_words(0),
4160 _failure_waste_words(0),
4161 _rs_length(0),
4162 _regions_freed(0) { }
4163
4164 void merge_stats(FreeCSetStats* other) {
4165 assert(other != NULL, "invariant");
4166 _before_used_bytes += other->_before_used_bytes;
4167 _after_used_bytes += other->_after_used_bytes;
4168 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4169 _failure_used_words += other->_failure_used_words;
4170 _failure_waste_words += other->_failure_waste_words;
4171 _rs_length += other->_rs_length;
4172 _regions_freed += other->_regions_freed;
4173 }
4174
4175 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4176 evacuation_info->set_regions_freed(_regions_freed);
4177 evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4178
4179 g1h->decrement_summary_bytes(_before_used_bytes);
4180 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4181
4182 G1Policy *policy = g1h->policy();
4183 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4184 policy->record_rs_length(_rs_length);
4185 policy->cset_regions_freed();
4186 }
4187
4188 void account_failed_region(HeapRegion* r) {
4189 size_t used_words = r->marked_bytes() / HeapWordSize;
4190 _failure_used_words += used_words;
4191 _failure_waste_words += HeapRegion::GrainWords - used_words;
4192 _after_used_bytes += r->used();
4193
4194 // When moving a young gen region to old gen, we "allocate" that whole
4195 // region there. This is in addition to any already evacuated objects.
4196 // Notify the policy about that. Old gen regions do not cause an
4197 // additional allocation: both the objects still in the region and the
4198 // ones already moved are accounted for elsewhere.
4199 if (r->is_young()) {
4200 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4201 }
4202 }
4203
4204 void account_evacuated_region(HeapRegion* r) {
4205 _before_used_bytes += r->used();
4206 _regions_freed += 1;
4207 }
4208
4209 void account_rs_length(HeapRegion* r) {
4210 _rs_length += r->rem_set()->occupied();
4211 }
4212 };
4213
4214 // Closure applied to all regions in the collection set.
4215 class FreeCSetClosure : public HeapRegionClosure {
4216 // Helper to send JFR events for regions.
4217 class JFREventForRegion {
4218 EventGCPhaseParallel _event;
4219 public:
4220 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4221 _event.set_gcId(GCId::current());
4222 _event.set_gcWorkerId(worker_id);
4223 if (region->is_young()) {
4224 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4225 } else {
4226 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4227 }
4228 }
4229
4230 ~JFREventForRegion() {
4231 _event.commit();
4232 }
4233 };
4234
4235 // Helper to do timing for region work.
4236 class TimerForRegion {
4237 Tickspan& _time;
4238 Ticks _start_time;
4239 public:
4240 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4241 ~TimerForRegion() {
4242 _time += Ticks::now() - _start_time;
4243 }
4244 };
4245
4246 // FreeCSetClosure members
4247 G1CollectedHeap* _g1h;
4248 const size_t* _surviving_young_words;
4249 uint _worker_id;
4250 Tickspan _young_time;
4251 Tickspan _non_young_time;
4252 FreeCSetStats* _stats;
4253
4254 void assert_in_cset(HeapRegion* r) {
4255 assert(r->young_index_in_cset() != 0 &&
4256 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4257 "Young index %u is wrong for region %u of type %s with %u young regions",
4258 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4259 }
4260
4261 void handle_evacuated_region(HeapRegion* r) {
4262 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4263 stats()->account_evacuated_region(r);
4264
4265 // Free the region and and its remembered set.
4266 _g1h->free_region(r, NULL);
4267 }
4268
4269 void handle_failed_region(HeapRegion* r) {
4270 // Do some allocation statistics accounting. Regions that failed evacuation
4271 // are always made old, so there is no need to update anything in the young
4272 // gen statistics, but we need to update old gen statistics.
4273 stats()->account_failed_region(r);
4274
4275 // Update the region state due to the failed evacuation.
4276 r->handle_evacuation_failure();
4277
4278 // Add region to old set, need to hold lock.
4279 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4280 _g1h->old_set_add(r);
4281 }
4282
4283 Tickspan& timer_for_region(HeapRegion* r) {
4284 return r->is_young() ? _young_time : _non_young_time;
4285 }
4286
4287 FreeCSetStats* stats() {
4288 return _stats;
4289 }
4290 public:
4291 FreeCSetClosure(const size_t* surviving_young_words,
4292 uint worker_id,
4293 FreeCSetStats* stats) :
4294 HeapRegionClosure(),
4295 _g1h(G1CollectedHeap::heap()),
4296 _surviving_young_words(surviving_young_words),
4297 _worker_id(worker_id),
4298 _young_time(),
4299 _non_young_time(),
4300 _stats(stats) { }
4301
4302 virtual bool do_heap_region(HeapRegion* r) {
4303 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4304 JFREventForRegion event(r, _worker_id);
4305 TimerForRegion timer(timer_for_region(r));
4306
4307 _g1h->clear_region_attr(r);
4308 stats()->account_rs_length(r);
4309
4310 if (r->is_young()) {
4311 assert_in_cset(r);
4312 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4313 }
4314
4315 if (r->evacuation_failed()) {
4316 handle_failed_region(r);
4317 } else {
4318 handle_evacuated_region(r);
4319 }
4320 assert(!_g1h->is_on_master_free_list(r), "sanity");
4321
4322 return false;
4323 }
4324
4325 void report_timing(Tickspan parallel_time) {
4326 G1GCPhaseTimes* pt = _g1h->phase_times();
4327 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4328 if (_young_time.value() > 0) {
4329 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4330 }
4331 if (_non_young_time.value() > 0) {
4332 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4333 }
4334 }
4335 };
4336
4337 // G1FreeCollectionSetTask members
4338 G1CollectedHeap* _g1h;
4339 G1EvacuationInfo* _evacuation_info;
4340 FreeCSetStats* _worker_stats;
4341 HeapRegionClaimer _claimer;
4342 const size_t* _surviving_young_words;
4343 uint _active_workers;
4344
4345 FreeCSetStats* worker_stats(uint worker) {
4346 return &_worker_stats[worker];
4347 }
4348
4349 void report_statistics() {
4350 // Merge the accounting
4351 FreeCSetStats total_stats;
4352 for (uint worker = 0; worker < _active_workers; worker++) {
4353 total_stats.merge_stats(worker_stats(worker));
4354 }
4355 total_stats.report(_g1h, _evacuation_info);
4356 }
4357
4358 public:
4359 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4360 AbstractGangTask("G1 Free Collection Set"),
4361 _g1h(G1CollectedHeap::heap()),
4362 _evacuation_info(evacuation_info),
4363 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4364 _claimer(active_workers),
4365 _surviving_young_words(surviving_young_words),
4366 _active_workers(active_workers) {
4367 for (uint worker = 0; worker < active_workers; worker++) {
4368 ::new (&_worker_stats[worker]) FreeCSetStats();
4369 }
4370 }
4371
4372 ~G1FreeCollectionSetTask() {
4373 Ticks serial_time = Ticks::now();
4374 report_statistics();
4375 for (uint worker = 0; worker < _active_workers; worker++) {
4376 _worker_stats[worker].~FreeCSetStats();
4377 }
4378 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4379 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4380 }
4381
4382 virtual void work(uint worker_id) {
4383 EventGCPhaseParallel event;
4384 Ticks start = Ticks::now();
4385 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4386 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4387
4388 // Report the total parallel time along with some more detailed metrics.
4389 cl.report_timing(Ticks::now() - start);
4390 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4391 }
4392 };
4393
4394 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4395 _eden.clear();
4396
4397 // The free collections set is split up in two tasks, the first
4398 // frees the collection set and records what regions are free,
4399 // and the second one rebuilds the free list. This proved to be
4400 // more efficient than adding a sorted list to another.
4401
4402 Ticks free_cset_start_time = Ticks::now();
4403 {
4404 uint const num_cs_regions = _collection_set.region_length();
4405 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4406 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4407
4408 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4409 cl.name(), num_workers, num_cs_regions, num_regions());
4410 workers()->run_task(&cl, num_workers);
4411 }
4412
4413 Ticks free_cset_end_time = Ticks::now();
4414 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4415
4416 // Now rebuild the free region list.
4417 hrm()->rebuild_free_list(workers());
4418 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4419
4420 collection_set->clear();
4421 }
4422
4423 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4424 private:
4425 FreeRegionList* _free_region_list;
4426 HeapRegionSet* _proxy_set;
4427 uint _humongous_objects_reclaimed;
4428 uint _humongous_regions_reclaimed;
4429 size_t _freed_bytes;
4430 public:
4431
4432 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4433 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4434 }
4435
4436 virtual bool do_heap_region(HeapRegion* r) {
4437 if (!r->is_starts_humongous()) {
4438 return false;
4439 }
4440
4441 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4442
4443 oop obj = (oop)r->bottom();
4444 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4445
4446 // The following checks whether the humongous object is live are sufficient.
4447 // The main additional check (in addition to having a reference from the roots
4448 // or the young gen) is whether the humongous object has a remembered set entry.
4449 //
4450 // A humongous object cannot be live if there is no remembered set for it
4451 // because:
4452 // - there can be no references from within humongous starts regions referencing
4453 // the object because we never allocate other objects into them.
4454 // (I.e. there are no intra-region references that may be missed by the
4455 // remembered set)
4456 // - as soon there is a remembered set entry to the humongous starts region
4457 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4458 // until the end of a concurrent mark.
4459 //
4460 // It is not required to check whether the object has been found dead by marking
4461 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4462 // all objects allocated during that time are considered live.
4463 // SATB marking is even more conservative than the remembered set.
4464 // So if at this point in the collection there is no remembered set entry,
4465 // nobody has a reference to it.
4466 // At the start of collection we flush all refinement logs, and remembered sets
4467 // are completely up-to-date wrt to references to the humongous object.
4468 //
4469 // Other implementation considerations:
4470 // - never consider object arrays at this time because they would pose
4471 // considerable effort for cleaning up the the remembered sets. This is
4472 // required because stale remembered sets might reference locations that
4473 // are currently allocated into.
4474 uint region_idx = r->hrm_index();
4475 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4476 !r->rem_set()->is_empty()) {
4477 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",
4478 region_idx,
4479 (size_t)obj->size() * HeapWordSize,
4480 p2i(r->bottom()),
4481 r->rem_set()->occupied(),
4482 r->rem_set()->strong_code_roots_list_length(),
4483 next_bitmap->is_marked(r->bottom()),
4484 g1h->is_humongous_reclaim_candidate(region_idx),
4485 obj->is_typeArray()
4486 );
4487 return false;
4488 }
4489
4490 guarantee(obj->is_typeArray(),
4491 "Only eagerly reclaiming type arrays is supported, but the object "
4492 PTR_FORMAT " is not.", p2i(r->bottom()));
4493
4494 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",
4495 region_idx,
4496 (size_t)obj->size() * HeapWordSize,
4497 p2i(r->bottom()),
4498 r->rem_set()->occupied(),
4499 r->rem_set()->strong_code_roots_list_length(),
4500 next_bitmap->is_marked(r->bottom()),
4501 g1h->is_humongous_reclaim_candidate(region_idx),
4502 obj->is_typeArray()
4503 );
4504
4505 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4506 cm->humongous_object_eagerly_reclaimed(r);
4507 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4508 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4509 region_idx,
4510 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4511 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4512 _humongous_objects_reclaimed++;
4513 do {
4514 HeapRegion* next = g1h->next_region_in_humongous(r);
4515 _freed_bytes += r->used();
4516 r->set_containing_set(NULL);
4517 _humongous_regions_reclaimed++;
4518 g1h->free_humongous_region(r, _free_region_list);
4519 r = next;
4520 } while (r != NULL);
4521
4522 return false;
4523 }
4524
4525 uint humongous_objects_reclaimed() {
4526 return _humongous_objects_reclaimed;
4527 }
4528
4529 uint humongous_regions_reclaimed() {
4530 return _humongous_regions_reclaimed;
4531 }
4532
4533 size_t bytes_freed() const {
4534 return _freed_bytes;
4535 }
4536 };
4537
4538 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4539 assert_at_safepoint_on_vm_thread();
4540
4541 if (!G1EagerReclaimHumongousObjects ||
4542 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4543 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4544 return;
4545 }
4546
4547 double start_time = os::elapsedTime();
4548
4549 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4550
4551 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4552 heap_region_iterate(&cl);
4553
4554 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4555
4556 G1HRPrinter* hrp = hr_printer();
4557 if (hrp->is_active()) {
4558 FreeRegionListIterator iter(&local_cleanup_list);
4559 while (iter.more_available()) {
4560 HeapRegion* hr = iter.get_next();
4561 hrp->cleanup(hr);
4562 }
4563 }
4564
4565 prepend_to_freelist(&local_cleanup_list);
4566 decrement_summary_bytes(cl.bytes_freed());
4567
4568 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4569 cl.humongous_objects_reclaimed());
4570 }
4571
4572 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4573 public:
4574 virtual bool do_heap_region(HeapRegion* r) {
4575 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4576 G1CollectedHeap::heap()->clear_region_attr(r);
4577 r->clear_young_index_in_cset();
4578 return false;
4579 }
4580 };
4581
4582 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4583 G1AbandonCollectionSetClosure cl;
4584 collection_set_iterate_all(&cl);
4585
4586 collection_set->clear();
4587 collection_set->stop_incremental_building();
4588 }
4589
4590 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4591 return _allocator->is_retained_old_region(hr);
4592 }
4593
4594 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4595 _eden.add(hr);
4596 _policy->set_region_eden(hr);
4597 }
4598
4599 #ifdef ASSERT
4600
4601 class NoYoungRegionsClosure: public HeapRegionClosure {
4602 private:
4603 bool _success;
4604 public:
4605 NoYoungRegionsClosure() : _success(true) { }
4606 bool do_heap_region(HeapRegion* r) {
4607 if (r->is_young()) {
4608 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4609 p2i(r->bottom()), p2i(r->end()));
4610 _success = false;
4611 }
4612 return false;
4613 }
4614 bool success() { return _success; }
4615 };
4616
4617 bool G1CollectedHeap::check_young_list_empty() {
4618 bool ret = (young_regions_count() == 0);
4619
4620 NoYoungRegionsClosure closure;
4621 heap_region_iterate(&closure);
4622 ret = ret && closure.success();
4623
4624 return ret;
4625 }
4626
4627 #endif // ASSERT
4628
4629 class TearDownRegionSetsClosure : public HeapRegionClosure {
4630 HeapRegionSet *_old_set;
4631
4632 public:
4633 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4634
4635 bool do_heap_region(HeapRegion* r) {
4636 if (r->is_old()) {
4637 _old_set->remove(r);
4638 } else if(r->is_young()) {
4639 r->uninstall_surv_rate_group();
4640 } else {
4641 // We ignore free regions, we'll empty the free list afterwards.
4642 // We ignore humongous and archive regions, we're not tearing down these
4643 // sets.
4644 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4645 "it cannot be another type");
4646 }
4647 return false;
4648 }
4649
4650 ~TearDownRegionSetsClosure() {
4651 assert(_old_set->is_empty(), "post-condition");
4652 }
4653 };
4654
4655 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4656 assert_at_safepoint_on_vm_thread();
4657
4658 if (!free_list_only) {
4659 TearDownRegionSetsClosure cl(&_old_set);
4660 heap_region_iterate(&cl);
4661
4662 // Note that emptying the _young_list is postponed and instead done as
4663 // the first step when rebuilding the regions sets again. The reason for
4664 // this is that during a full GC string deduplication needs to know if
4665 // a collected region was young or old when the full GC was initiated.
4666 }
4667 _hrm->remove_all_free_regions();
4668 }
4669
4670 void G1CollectedHeap::increase_used(size_t bytes) {
4671 _summary_bytes_used += bytes;
4672 }
4673
4674 void G1CollectedHeap::decrease_used(size_t bytes) {
4675 assert(_summary_bytes_used >= bytes,
4676 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4677 _summary_bytes_used, bytes);
4678 _summary_bytes_used -= bytes;
4679 }
4680
4681 void G1CollectedHeap::set_used(size_t bytes) {
4682 _summary_bytes_used = bytes;
4683 }
4684
4685 class RebuildRegionSetsClosure : public HeapRegionClosure {
4686 private:
4687 bool _free_list_only;
4688
4689 HeapRegionSet* _old_set;
4690 HeapRegionManager* _hrm;
4691
4692 size_t _total_used;
4693
4694 public:
4695 RebuildRegionSetsClosure(bool free_list_only,
4696 HeapRegionSet* old_set,
4697 HeapRegionManager* hrm) :
4698 _free_list_only(free_list_only),
4699 _old_set(old_set), _hrm(hrm), _total_used(0) {
4700 assert(_hrm->num_free_regions() == 0, "pre-condition");
4701 if (!free_list_only) {
4702 assert(_old_set->is_empty(), "pre-condition");
4703 }
4704 }
4705
4706 bool do_heap_region(HeapRegion* r) {
4707 if (r->is_empty()) {
4708 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4709 // Add free regions to the free list
4710 r->set_free();
4711 _hrm->insert_into_free_list(r);
4712 } else if (!_free_list_only) {
4713 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4714
4715 if (r->is_archive() || r->is_humongous()) {
4716 // We ignore archive and humongous regions. We left these sets unchanged.
4717 } else {
4718 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4719 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4720 r->move_to_old();
4721 _old_set->add(r);
4722 }
4723 _total_used += r->used();
4724 }
4725
4726 return false;
4727 }
4728
4729 size_t total_used() {
4730 return _total_used;
4731 }
4732 };
4733
4734 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4735 assert_at_safepoint_on_vm_thread();
4736
4737 if (!free_list_only) {
4738 _eden.clear();
4739 _survivor.clear();
4740 }
4741
4742 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4743 heap_region_iterate(&cl);
4744
4745 if (!free_list_only) {
4746 set_used(cl.total_used());
4747 if (_archive_allocator != NULL) {
4748 _archive_allocator->clear_used();
4749 }
4750 }
4751 assert_used_and_recalculate_used_equal(this);
4752 }
4753
4754 // Methods for the mutator alloc region
4755
4756 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4757 bool force,
4758 uint node_index) {
4759 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4760 bool should_allocate = policy()->should_allocate_mutator_region();
4761 if (force || should_allocate) {
4762 HeapRegion* new_alloc_region = new_region(word_size,
4763 HeapRegionType::Eden,
4764 false /* do_expand */,
4765 node_index);
4766 if (new_alloc_region != NULL) {
4767 set_region_short_lived_locked(new_alloc_region);
4768 _hr_printer.alloc(new_alloc_region, !should_allocate);
4769 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4770 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4771 return new_alloc_region;
4772 }
4773 }
4774 return NULL;
4775 }
4776
4777 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4778 size_t allocated_bytes) {
4779 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4780 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4781
4782 collection_set()->add_eden_region(alloc_region);
4783 increase_used(allocated_bytes);
4784 _eden.add_used_bytes(allocated_bytes);
4785 _hr_printer.retire(alloc_region);
4786
4787 // We update the eden sizes here, when the region is retired,
4788 // instead of when it's allocated, since this is the point that its
4789 // used space has been recorded in _summary_bytes_used.
4790 g1mm()->update_eden_size();
4791 }
4792
4793 // Methods for the GC alloc regions
4794
4795 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4796 if (dest.is_old()) {
4797 return true;
4798 } else {
4799 return survivor_regions_count() < policy()->max_survivor_regions();
4800 }
4801 }
4802
4803 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4804 assert(FreeList_lock->owned_by_self(), "pre-condition");
4805
4806 if (!has_more_regions(dest)) {
4807 return NULL;
4808 }
4809
4810 HeapRegionType type;
4811 if (dest.is_young()) {
4812 type = HeapRegionType::Survivor;
4813 } else {
4814 type = HeapRegionType::Old;
4815 }
4816
4817 HeapRegion* new_alloc_region = new_region(word_size,
4818 type,
4819 true /* do_expand */,
4820 node_index);
4821
4822 if (new_alloc_region != NULL) {
4823 if (type.is_survivor()) {
4824 new_alloc_region->set_survivor();
4825 _survivor.add(new_alloc_region);
4826 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4827 } else {
4828 new_alloc_region->set_old();
4829 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4830 }
4831 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4832 register_region_with_region_attr(new_alloc_region);
4833 _hr_printer.alloc(new_alloc_region);
4834 return new_alloc_region;
4835 }
4836 return NULL;
4837 }
4838
4839 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4840 size_t allocated_bytes,
4841 G1HeapRegionAttr dest) {
4842 _bytes_used_during_gc += allocated_bytes;
4843 if (dest.is_old()) {
4844 old_set_add(alloc_region);
4845 } else {
4846 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4847 _survivor.add_used_bytes(allocated_bytes);
4848 }
4849
4850 bool const during_im = collector_state()->in_initial_mark_gc();
4851 if (during_im && allocated_bytes > 0) {
4852 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4853 }
4854 _hr_printer.retire(alloc_region);
4855 }
4856
4857 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4858 bool expanded = false;
4859 uint index = _hrm->find_highest_free(&expanded);
4860
4861 if (index != G1_NO_HRM_INDEX) {
4862 if (expanded) {
4863 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4864 HeapRegion::GrainWords * HeapWordSize);
4865 }
4866 return _hrm->allocate_free_regions_starting_at(index, 1);
4867 }
4868 return NULL;
4869 }
4870
4871 // Optimized nmethod scanning
4872
4873 class RegisterNMethodOopClosure: public OopClosure {
4874 G1CollectedHeap* _g1h;
4875 nmethod* _nm;
4876
4877 template <class T> void do_oop_work(T* p) {
4878 T heap_oop = RawAccess<>::oop_load(p);
4879 if (!CompressedOops::is_null(heap_oop)) {
4880 oop obj = CompressedOops::decode_not_null(heap_oop);
4881 HeapRegion* hr = _g1h->heap_region_containing(obj);
4882 assert(!hr->is_continues_humongous(),
4883 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4884 " starting at " HR_FORMAT,
4885 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4886
4887 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4888 hr->add_strong_code_root_locked(_nm);
4889 }
4890 }
4891
4892 public:
4893 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4894 _g1h(g1h), _nm(nm) {}
4895
4896 void do_oop(oop* p) { do_oop_work(p); }
4897 void do_oop(narrowOop* p) { do_oop_work(p); }
4898 };
4899
4900 class UnregisterNMethodOopClosure: public OopClosure {
4901 G1CollectedHeap* _g1h;
4902 nmethod* _nm;
4903
4904 template <class T> void do_oop_work(T* p) {
4905 T heap_oop = RawAccess<>::oop_load(p);
4906 if (!CompressedOops::is_null(heap_oop)) {
4907 oop obj = CompressedOops::decode_not_null(heap_oop);
4908 HeapRegion* hr = _g1h->heap_region_containing(obj);
4909 assert(!hr->is_continues_humongous(),
4910 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4911 " starting at " HR_FORMAT,
4912 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4913
4914 hr->remove_strong_code_root(_nm);
4915 }
4916 }
4917
4918 public:
4919 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4920 _g1h(g1h), _nm(nm) {}
4921
4922 void do_oop(oop* p) { do_oop_work(p); }
4923 void do_oop(narrowOop* p) { do_oop_work(p); }
4924 };
4925
4926 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4927 guarantee(nm != NULL, "sanity");
4928 RegisterNMethodOopClosure reg_cl(this, nm);
4929 nm->oops_do(®_cl);
4930 }
4931
4932 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4933 guarantee(nm != NULL, "sanity");
4934 UnregisterNMethodOopClosure reg_cl(this, nm);
4935 nm->oops_do(®_cl, true);
4936 }
4937
4938 void G1CollectedHeap::purge_code_root_memory() {
4939 double purge_start = os::elapsedTime();
4940 G1CodeRootSet::purge();
4941 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4942 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4943 }
4944
4945 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4946 G1CollectedHeap* _g1h;
4947
4948 public:
4949 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4950 _g1h(g1h) {}
4951
4952 void do_code_blob(CodeBlob* cb) {
4953 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4954 if (nm == NULL) {
4955 return;
4956 }
4957
4958 _g1h->register_nmethod(nm);
4959 }
4960 };
4961
4962 void G1CollectedHeap::rebuild_strong_code_roots() {
4963 RebuildStrongCodeRootClosure blob_cl(this);
4964 CodeCache::blobs_do(&blob_cl);
4965 }
4966
4967 void G1CollectedHeap::initialize_serviceability() {
4968 _g1mm->initialize_serviceability();
4969 }
4970
4971 MemoryUsage G1CollectedHeap::memory_usage() {
4972 return _g1mm->memory_usage();
4973 }
4974
4975 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4976 return _g1mm->memory_managers();
4977 }
4978
4979 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4980 return _g1mm->memory_pools();
4981 }