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/g1InitLogger.hpp"
51 #include "gc/g1/g1MemoryPool.hpp"
52 #include "gc/g1/g1OopClosures.inline.hpp"
53 #include "gc/g1/g1ParallelCleaning.hpp"
54 #include "gc/g1/g1ParScanThreadState.inline.hpp"
55 #include "gc/g1/g1Policy.hpp"
56 #include "gc/g1/g1RedirtyCardsQueue.hpp"
57 #include "gc/g1/g1RegionToSpaceMapper.hpp"
58 #include "gc/g1/g1RemSet.hpp"
59 #include "gc/g1/g1RootClosures.hpp"
60 #include "gc/g1/g1RootProcessor.hpp"
61 #include "gc/g1/g1SATBMarkQueueSet.hpp"
62 #include "gc/g1/g1StringDedup.hpp"
63 #include "gc/g1/g1ThreadLocalData.hpp"
64 #include "gc/g1/g1Trace.hpp"
65 #include "gc/g1/g1YCTypes.hpp"
66 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
67 #include "gc/g1/g1VMOperations.hpp"
68 #include "gc/g1/heapRegion.inline.hpp"
69 #include "gc/g1/heapRegionRemSet.hpp"
70 #include "gc/g1/heapRegionSet.inline.hpp"
71 #include "gc/shared/concurrentGCBreakpoints.hpp"
72 #include "gc/shared/gcBehaviours.hpp"
73 #include "gc/shared/gcHeapSummary.hpp"
74 #include "gc/shared/gcId.hpp"
75 #include "gc/shared/gcLocker.hpp"
76 #include "gc/shared/gcTimer.hpp"
77 #include "gc/shared/gcTraceTime.inline.hpp"
78 #include "gc/shared/generationSpec.hpp"
79 #include "gc/shared/isGCActiveMark.hpp"
80 #include "gc/shared/locationPrinter.inline.hpp"
81 #include "gc/shared/oopStorageParState.hpp"
82 #include "gc/shared/preservedMarks.inline.hpp"
83 #include "gc/shared/suspendibleThreadSet.hpp"
84 #include "gc/shared/referenceProcessor.inline.hpp"
85 #include "gc/shared/taskTerminator.hpp"
86 #include "gc/shared/taskqueue.inline.hpp"
87 #include "gc/shared/weakProcessor.inline.hpp"
88 #include "gc/shared/workerPolicy.hpp"
89 #include "logging/log.hpp"
90 #include "memory/allocation.hpp"
91 #include "memory/iterator.hpp"
92 #include "memory/heapInspection.hpp"
93 #include "memory/resourceArea.hpp"
94 #include "memory/universe.hpp"
95 #include "oops/access.inline.hpp"
96 #include "oops/compressedOops.inline.hpp"
97 #include "oops/oop.inline.hpp"
98 #include "runtime/atomic.hpp"
99 #include "runtime/flags/flagSetting.hpp"
100 #include "runtime/handles.inline.hpp"
101 #include "runtime/init.hpp"
102 #include "runtime/orderAccess.hpp"
103 #include "runtime/threadSMR.hpp"
104 #include "runtime/vmThread.hpp"
105 #include "utilities/align.hpp"
106 #include "utilities/bitMap.inline.hpp"
107 #include "utilities/globalDefinitions.hpp"
108 #include "utilities/stack.inline.hpp"
109
110 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
111
112 // INVARIANTS/NOTES
113 //
114 // All allocation activity covered by the G1CollectedHeap interface is
115 // serialized by acquiring the HeapLock. This happens in mem_allocate
116 // and allocate_new_tlab, which are the "entry" points to the
117 // allocation code from the rest of the JVM. (Note that this does not
118 // apply to TLAB allocation, which is not part of this interface: it
119 // is done by clients of this interface.)
120
121 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
122 private:
123 size_t _num_dirtied;
124 G1CollectedHeap* _g1h;
125 G1CardTable* _g1_ct;
126
127 HeapRegion* region_for_card(CardValue* card_ptr) const {
128 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
129 }
130
131 bool will_become_free(HeapRegion* hr) const {
132 // A region will be freed by free_collection_set if the region is in the
133 // collection set and has not had an evacuation failure.
134 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
135 }
136
137 public:
138 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
139 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
140
141 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
142 HeapRegion* hr = region_for_card(card_ptr);
143
144 // Should only dirty cards in regions that won't be freed.
145 if (!will_become_free(hr)) {
146 *card_ptr = G1CardTable::dirty_card_val();
147 _num_dirtied++;
148 }
149 }
150
151 size_t num_dirtied() const { return _num_dirtied; }
152 };
153
154
155 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
156 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
157 }
158
159 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
160 // The from card cache is not the memory that is actually committed. So we cannot
161 // take advantage of the zero_filled parameter.
162 reset_from_card_cache(start_idx, num_regions);
163 }
164
165 void G1CollectedHeap::run_task(AbstractGangTask* task) {
166 workers()->run_task(task, workers()->active_workers());
167 }
168
169 Tickspan G1CollectedHeap::run_task_timed(AbstractGangTask* task) {
170 Ticks start = Ticks::now();
171 run_task(task);
172 return Ticks::now() - start;
173 }
174
175 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
176 MemRegion mr) {
177 return new HeapRegion(hrs_index, bot(), mr);
178 }
179
180 // Private methods.
181
182 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
183 HeapRegionType type,
184 bool do_expand,
185 uint node_index) {
186 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
187 "the only time we use this to allocate a humongous region is "
188 "when we are allocating a single humongous region");
189
190 HeapRegion* res = _hrm->allocate_free_region(type, node_index);
191
192 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
193 // Currently, only attempts to allocate GC alloc regions set
194 // do_expand to true. So, we should only reach here during a
195 // safepoint. If this assumption changes we might have to
196 // reconsider the use of _expand_heap_after_alloc_failure.
197 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
198
199 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
200 word_size * HeapWordSize);
201
202 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
203 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
204 word_size * HeapWordSize);
205 if (expand_single_region(node_index)) {
206 // Given that expand_single_region() succeeded in expanding the heap, and we
207 // always expand the heap by an amount aligned to the heap
208 // region size, the free list should in theory not be empty.
209 // In either case allocate_free_region() will check for NULL.
210 res = _hrm->allocate_free_region(type, node_index);
211 } else {
212 _expand_heap_after_alloc_failure = false;
213 }
214 }
215 return res;
216 }
217
218 HeapWord*
219 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
220 uint num_regions,
221 size_t word_size) {
222 assert(first_hr != NULL, "pre-condition");
223 assert(is_humongous(word_size), "word_size should be humongous");
224 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
225
226 // Index of last region in the series.
227 uint first = first_hr->hrm_index();
228 uint last = first + num_regions - 1;
229
230 // We need to initialize the region(s) we just discovered. This is
231 // a bit tricky given that it can happen concurrently with
232 // refinement threads refining cards on these regions and
233 // potentially wanting to refine the BOT as they are scanning
234 // those cards (this can happen shortly after a cleanup; see CR
235 // 6991377). So we have to set up the region(s) carefully and in
236 // a specific order.
237
238 // The word size sum of all the regions we will allocate.
239 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
240 assert(word_size <= word_size_sum, "sanity");
241
242 // The passed in hr will be the "starts humongous" region. The header
243 // of the new object will be placed at the bottom of this region.
244 HeapWord* new_obj = first_hr->bottom();
245 // This will be the new top of the new object.
246 HeapWord* obj_top = new_obj + word_size;
247
248 // First, we need to zero the header of the space that we will be
249 // allocating. When we update top further down, some refinement
250 // threads might try to scan the region. By zeroing the header we
251 // ensure that any thread that will try to scan the region will
252 // come across the zero klass word and bail out.
253 //
254 // NOTE: It would not have been correct to have used
255 // CollectedHeap::fill_with_object() and make the space look like
256 // an int array. The thread that is doing the allocation will
257 // later update the object header to a potentially different array
258 // type and, for a very short period of time, the klass and length
259 // fields will be inconsistent. This could cause a refinement
260 // thread to calculate the object size incorrectly.
261 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
262
263 // Next, pad out the unused tail of the last region with filler
264 // objects, for improved usage accounting.
265 // How many words we use for filler objects.
266 size_t word_fill_size = word_size_sum - word_size;
267
268 // How many words memory we "waste" which cannot hold a filler object.
269 size_t words_not_fillable = 0;
270
271 if (word_fill_size >= min_fill_size()) {
272 fill_with_objects(obj_top, word_fill_size);
273 } else if (word_fill_size > 0) {
274 // We have space to fill, but we cannot fit an object there.
275 words_not_fillable = word_fill_size;
276 word_fill_size = 0;
277 }
278
279 // We will set up the first region as "starts humongous". This
280 // will also update the BOT covering all the regions to reflect
281 // that there is a single object that starts at the bottom of the
282 // first region.
283 first_hr->set_starts_humongous(obj_top, word_fill_size);
284 _policy->remset_tracker()->update_at_allocate(first_hr);
285 // Then, if there are any, we will set up the "continues
286 // humongous" regions.
287 HeapRegion* hr = NULL;
288 for (uint i = first + 1; i <= last; ++i) {
289 hr = region_at(i);
290 hr->set_continues_humongous(first_hr);
291 _policy->remset_tracker()->update_at_allocate(hr);
292 }
293
294 // Up to this point no concurrent thread would have been able to
295 // do any scanning on any region in this series. All the top
296 // fields still point to bottom, so the intersection between
297 // [bottom,top] and [card_start,card_end] will be empty. Before we
298 // update the top fields, we'll do a storestore to make sure that
299 // no thread sees the update to top before the zeroing of the
300 // object header and the BOT initialization.
301 OrderAccess::storestore();
302
303 // Now, we will update the top fields of the "continues humongous"
304 // regions except the last one.
305 for (uint i = first; i < last; ++i) {
306 hr = region_at(i);
307 hr->set_top(hr->end());
308 }
309
310 hr = region_at(last);
311 // If we cannot fit a filler object, we must set top to the end
312 // of the humongous object, otherwise we cannot iterate the heap
313 // and the BOT will not be complete.
314 hr->set_top(hr->end() - words_not_fillable);
315
316 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
317 "obj_top should be in last region");
318
319 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
320
321 assert(words_not_fillable == 0 ||
322 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
323 "Miscalculation in humongous allocation");
324
325 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
326
327 for (uint i = first; i <= last; ++i) {
328 hr = region_at(i);
329 _humongous_set.add(hr);
330 _hr_printer.alloc(hr);
331 }
332
333 return new_obj;
334 }
335
336 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
337 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
338 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
339 }
340
341 // If could fit into free regions w/o expansion, try.
342 // Otherwise, if can expand, do so.
343 // Otherwise, if using ex regions might help, try with ex given back.
344 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
345 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
346
347 _verifier->verify_region_sets_optional();
348
349 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
350
351 // Policy: First try to allocate a humongous object in the free list.
352 HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions);
353 if (humongous_start == NULL) {
354 // Policy: We could not find enough regions for the humongous object in the
355 // free list. Look through the heap to find a mix of free and uncommitted regions.
356 // If so, expand the heap and allocate the humongous object.
357 humongous_start = _hrm->expand_and_allocate_humongous(obj_regions);
358 if (humongous_start != NULL) {
359 // We managed to find a region by expanding the heap.
360 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
361 word_size * HeapWordSize);
362 policy()->record_new_heap_size(num_regions());
363 } else {
364 // Policy: Potentially trigger a defragmentation GC.
365 }
366 }
367
368 HeapWord* result = NULL;
369 if (humongous_start != NULL) {
370 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
371 assert(result != NULL, "it should always return a valid result");
372
373 // A successful humongous object allocation changes the used space
374 // information of the old generation so we need to recalculate the
375 // sizes and update the jstat counters here.
376 g1mm()->update_sizes();
377 }
378
379 _verifier->verify_region_sets_optional();
380
381 return result;
382 }
383
384 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
385 size_t requested_size,
386 size_t* actual_size) {
387 assert_heap_not_locked_and_not_at_safepoint();
388 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
389
390 return attempt_allocation(min_size, requested_size, actual_size);
391 }
392
393 HeapWord*
394 G1CollectedHeap::mem_allocate(size_t word_size,
395 bool* gc_overhead_limit_was_exceeded) {
396 assert_heap_not_locked_and_not_at_safepoint();
397
398 if (is_humongous(word_size)) {
399 return attempt_allocation_humongous(word_size);
400 }
401 size_t dummy = 0;
402 return attempt_allocation(word_size, word_size, &dummy);
403 }
404
405 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
406 ResourceMark rm; // For retrieving the thread names in log messages.
407
408 // Make sure you read the note in attempt_allocation_humongous().
409
410 assert_heap_not_locked_and_not_at_safepoint();
411 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
412 "be called for humongous allocation requests");
413
414 // We should only get here after the first-level allocation attempt
415 // (attempt_allocation()) failed to allocate.
416
417 // We will loop until a) we manage to successfully perform the
418 // allocation or b) we successfully schedule a collection which
419 // fails to perform the allocation. b) is the only case when we'll
420 // return NULL.
421 HeapWord* result = NULL;
422 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
423 bool should_try_gc;
424 uint gc_count_before;
425
426 {
427 MutexLocker x(Heap_lock);
428 result = _allocator->attempt_allocation_locked(word_size);
429 if (result != NULL) {
430 return result;
431 }
432
433 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
434 // This is different to when only GCLocker::needs_gc() is set: try to avoid
435 // waiting because the GCLocker is active to not wait too long.
436 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
437 // No need for an ergo message here, can_expand_young_list() does this when
438 // it returns true.
439 result = _allocator->attempt_allocation_force(word_size);
440 if (result != NULL) {
441 return result;
442 }
443 }
444 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
445 // the GCLocker initiated GC has been performed and then retry. This includes
446 // the case when the GC Locker is not active but has not been performed.
447 should_try_gc = !GCLocker::needs_gc();
448 // Read the GC count while still holding the Heap_lock.
449 gc_count_before = total_collections();
450 }
451
452 if (should_try_gc) {
453 bool succeeded;
454 result = do_collection_pause(word_size, gc_count_before, &succeeded,
455 GCCause::_g1_inc_collection_pause);
456 if (result != NULL) {
457 assert(succeeded, "only way to get back a non-NULL result");
458 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
459 Thread::current()->name(), p2i(result));
460 return result;
461 }
462
463 if (succeeded) {
464 // We successfully scheduled a collection which failed to allocate. No
465 // point in trying to allocate further. We'll just return NULL.
466 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
467 SIZE_FORMAT " words", Thread::current()->name(), word_size);
468 return NULL;
469 }
470 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
471 Thread::current()->name(), word_size);
472 } else {
473 // Failed to schedule a collection.
474 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
475 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
476 SIZE_FORMAT " words", Thread::current()->name(), word_size);
477 return NULL;
478 }
479 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
480 // The GCLocker is either active or the GCLocker initiated
481 // GC has not yet been performed. Stall until it is and
482 // then retry the allocation.
483 GCLocker::stall_until_clear();
484 gclocker_retry_count += 1;
485 }
486
487 // We can reach here if we were unsuccessful in scheduling a
488 // collection (because another thread beat us to it) or if we were
489 // stalled due to the GC locker. In either can we should retry the
490 // allocation attempt in case another thread successfully
491 // performed a collection and reclaimed enough space. We do the
492 // first attempt (without holding the Heap_lock) here and the
493 // follow-on attempt will be at the start of the next loop
494 // iteration (after taking the Heap_lock).
495 size_t dummy = 0;
496 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
497 if (result != NULL) {
498 return result;
499 }
500
501 // Give a warning if we seem to be looping forever.
502 if ((QueuedAllocationWarningCount > 0) &&
503 (try_count % QueuedAllocationWarningCount == 0)) {
504 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
505 Thread::current()->name(), try_count, word_size);
506 }
507 }
508
509 ShouldNotReachHere();
510 return NULL;
511 }
512
513 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
514 assert_at_safepoint_on_vm_thread();
515 if (_archive_allocator == NULL) {
516 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
517 }
518 }
519
520 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
521 // Allocations in archive regions cannot be of a size that would be considered
522 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
523 // may be different at archive-restore time.
524 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
525 }
526
527 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
528 assert_at_safepoint_on_vm_thread();
529 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
530 if (is_archive_alloc_too_large(word_size)) {
531 return NULL;
532 }
533 return _archive_allocator->archive_mem_allocate(word_size);
534 }
535
536 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
537 size_t end_alignment_in_bytes) {
538 assert_at_safepoint_on_vm_thread();
539 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
540
541 // Call complete_archive to do the real work, filling in the MemRegion
542 // array with the archive regions.
543 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
544 delete _archive_allocator;
545 _archive_allocator = NULL;
546 }
547
548 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
549 assert(ranges != NULL, "MemRegion array NULL");
550 assert(count != 0, "No MemRegions provided");
551 MemRegion reserved = _hrm->reserved();
552 for (size_t i = 0; i < count; i++) {
553 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
554 return false;
555 }
556 }
557 return true;
558 }
559
560 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
561 size_t count,
562 bool open) {
563 assert(!is_init_completed(), "Expect to be called at JVM init time");
564 assert(ranges != NULL, "MemRegion array NULL");
565 assert(count != 0, "No MemRegions provided");
566 MutexLocker x(Heap_lock);
567
568 MemRegion reserved = _hrm->reserved();
569 HeapWord* prev_last_addr = NULL;
570 HeapRegion* prev_last_region = NULL;
571
572 // Temporarily disable pretouching of heap pages. This interface is used
573 // when mmap'ing archived heap data in, so pre-touching is wasted.
574 FlagSetting fs(AlwaysPreTouch, false);
575
576 // Enable archive object checking used by G1MarkSweep. We have to let it know
577 // about each archive range, so that objects in those ranges aren't marked.
578 G1ArchiveAllocator::enable_archive_object_check();
579
580 // For each specified MemRegion range, allocate the corresponding G1
581 // regions and mark them as archive regions. We expect the ranges
582 // in ascending starting address order, without overlap.
583 for (size_t i = 0; i < count; i++) {
584 MemRegion curr_range = ranges[i];
585 HeapWord* start_address = curr_range.start();
586 size_t word_size = curr_range.word_size();
587 HeapWord* last_address = curr_range.last();
588 size_t commits = 0;
589
590 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
591 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
592 p2i(start_address), p2i(last_address));
593 guarantee(start_address > prev_last_addr,
594 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
595 p2i(start_address), p2i(prev_last_addr));
596 prev_last_addr = last_address;
597
598 // Check for ranges that start in the same G1 region in which the previous
599 // range ended, and adjust the start address so we don't try to allocate
600 // the same region again. If the current range is entirely within that
601 // region, skip it, just adjusting the recorded top.
602 HeapRegion* start_region = _hrm->addr_to_region(start_address);
603 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
604 start_address = start_region->end();
605 if (start_address > last_address) {
606 increase_used(word_size * HeapWordSize);
607 start_region->set_top(last_address + 1);
608 continue;
609 }
610 start_region->set_top(start_address);
611 curr_range = MemRegion(start_address, last_address + 1);
612 start_region = _hrm->addr_to_region(start_address);
613 }
614
615 // Perform the actual region allocation, exiting if it fails.
616 // Then note how much new space we have allocated.
617 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
618 return false;
619 }
620 increase_used(word_size * HeapWordSize);
621 if (commits != 0) {
622 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
623 HeapRegion::GrainWords * HeapWordSize * commits);
624
625 }
626
627 // Mark each G1 region touched by the range as archive, add it to
628 // the old set, and set top.
629 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
630 HeapRegion* last_region = _hrm->addr_to_region(last_address);
631 prev_last_region = last_region;
632
633 while (curr_region != NULL) {
634 assert(curr_region->is_empty() && !curr_region->is_pinned(),
635 "Region already in use (index %u)", curr_region->hrm_index());
636 if (open) {
637 curr_region->set_open_archive();
638 } else {
639 curr_region->set_closed_archive();
640 }
641 _hr_printer.alloc(curr_region);
642 _archive_set.add(curr_region);
643 HeapWord* top;
644 HeapRegion* next_region;
645 if (curr_region != last_region) {
646 top = curr_region->end();
647 next_region = _hrm->next_region_in_heap(curr_region);
648 } else {
649 top = last_address + 1;
650 next_region = NULL;
651 }
652 curr_region->set_top(top);
653 curr_region = next_region;
654 }
655
656 // Notify mark-sweep of the archive
657 G1ArchiveAllocator::set_range_archive(curr_range, open);
658 }
659 return true;
660 }
661
662 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
663 assert(!is_init_completed(), "Expect to be called at JVM init time");
664 assert(ranges != NULL, "MemRegion array NULL");
665 assert(count != 0, "No MemRegions provided");
666 MemRegion reserved = _hrm->reserved();
667 HeapWord *prev_last_addr = NULL;
668 HeapRegion* prev_last_region = NULL;
669
670 // For each MemRegion, create filler objects, if needed, in the G1 regions
671 // that contain the address range. The address range actually within the
672 // MemRegion will not be modified. That is assumed to have been initialized
673 // elsewhere, probably via an mmap of archived heap data.
674 MutexLocker x(Heap_lock);
675 for (size_t i = 0; i < count; i++) {
676 HeapWord* start_address = ranges[i].start();
677 HeapWord* last_address = ranges[i].last();
678
679 assert(reserved.contains(start_address) && reserved.contains(last_address),
680 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
681 p2i(start_address), p2i(last_address));
682 assert(start_address > prev_last_addr,
683 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
684 p2i(start_address), p2i(prev_last_addr));
685
686 HeapRegion* start_region = _hrm->addr_to_region(start_address);
687 HeapRegion* last_region = _hrm->addr_to_region(last_address);
688 HeapWord* bottom_address = start_region->bottom();
689
690 // Check for a range beginning in the same region in which the
691 // previous one ended.
692 if (start_region == prev_last_region) {
693 bottom_address = prev_last_addr + 1;
694 }
695
696 // Verify that the regions were all marked as archive regions by
697 // alloc_archive_regions.
698 HeapRegion* curr_region = start_region;
699 while (curr_region != NULL) {
700 guarantee(curr_region->is_archive(),
701 "Expected archive region at index %u", curr_region->hrm_index());
702 if (curr_region != last_region) {
703 curr_region = _hrm->next_region_in_heap(curr_region);
704 } else {
705 curr_region = NULL;
706 }
707 }
708
709 prev_last_addr = last_address;
710 prev_last_region = last_region;
711
712 // Fill the memory below the allocated range with dummy object(s),
713 // if the region bottom does not match the range start, or if the previous
714 // range ended within the same G1 region, and there is a gap.
715 if (start_address != bottom_address) {
716 size_t fill_size = pointer_delta(start_address, bottom_address);
717 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
718 increase_used(fill_size * HeapWordSize);
719 }
720 }
721 }
722
723 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
724 size_t desired_word_size,
725 size_t* actual_word_size) {
726 assert_heap_not_locked_and_not_at_safepoint();
727 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
728 "be called for humongous allocation requests");
729
730 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
731
732 if (result == NULL) {
733 *actual_word_size = desired_word_size;
734 result = attempt_allocation_slow(desired_word_size);
735 }
736
737 assert_heap_not_locked();
738 if (result != NULL) {
739 assert(*actual_word_size != 0, "Actual size must have been set here");
740 dirty_young_block(result, *actual_word_size);
741 } else {
742 *actual_word_size = 0;
743 }
744
745 return result;
746 }
747
748 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
749 assert(!is_init_completed(), "Expect to be called at JVM init time");
750 assert(ranges != NULL, "MemRegion array NULL");
751 assert(count != 0, "No MemRegions provided");
752 MemRegion reserved = _hrm->reserved();
753 HeapWord* prev_last_addr = NULL;
754 HeapRegion* prev_last_region = NULL;
755 size_t size_used = 0;
756 size_t uncommitted_regions = 0;
757
758 // For each Memregion, free the G1 regions that constitute it, and
759 // notify mark-sweep that the range is no longer to be considered 'archive.'
760 MutexLocker x(Heap_lock);
761 for (size_t i = 0; i < count; i++) {
762 HeapWord* start_address = ranges[i].start();
763 HeapWord* last_address = ranges[i].last();
764
765 assert(reserved.contains(start_address) && reserved.contains(last_address),
766 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
767 p2i(start_address), p2i(last_address));
768 assert(start_address > prev_last_addr,
769 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
770 p2i(start_address), p2i(prev_last_addr));
771 size_used += ranges[i].byte_size();
772 prev_last_addr = last_address;
773
774 HeapRegion* start_region = _hrm->addr_to_region(start_address);
775 HeapRegion* last_region = _hrm->addr_to_region(last_address);
776
777 // Check for ranges that start in the same G1 region in which the previous
778 // range ended, and adjust the start address so we don't try to free
779 // the same region again. If the current range is entirely within that
780 // region, skip it.
781 if (start_region == prev_last_region) {
782 start_address = start_region->end();
783 if (start_address > last_address) {
784 continue;
785 }
786 start_region = _hrm->addr_to_region(start_address);
787 }
788 prev_last_region = last_region;
789
790 // After verifying that each region was marked as an archive region by
791 // alloc_archive_regions, set it free and empty and uncommit it.
792 HeapRegion* curr_region = start_region;
793 while (curr_region != NULL) {
794 guarantee(curr_region->is_archive(),
795 "Expected archive region at index %u", curr_region->hrm_index());
796 uint curr_index = curr_region->hrm_index();
797 _archive_set.remove(curr_region);
798 curr_region->set_free();
799 curr_region->set_top(curr_region->bottom());
800 if (curr_region != last_region) {
801 curr_region = _hrm->next_region_in_heap(curr_region);
802 } else {
803 curr_region = NULL;
804 }
805 _hrm->shrink_at(curr_index, 1);
806 uncommitted_regions++;
807 }
808
809 // Notify mark-sweep that this is no longer an archive range.
810 G1ArchiveAllocator::clear_range_archive(ranges[i]);
811 }
812
813 if (uncommitted_regions != 0) {
814 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
815 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
816 }
817 decrease_used(size_used);
818 }
819
820 oop G1CollectedHeap::materialize_archived_object(oop obj) {
821 assert(obj != NULL, "archived obj is NULL");
822 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
823
824 // Loading an archived object makes it strongly reachable. If it is
825 // loaded during concurrent marking, it must be enqueued to the SATB
826 // queue, shading the previously white object gray.
827 G1BarrierSet::enqueue(obj);
828
829 return obj;
830 }
831
832 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
833 ResourceMark rm; // For retrieving the thread names in log messages.
834
835 // The structure of this method has a lot of similarities to
836 // attempt_allocation_slow(). The reason these two were not merged
837 // into a single one is that such a method would require several "if
838 // allocation is not humongous do this, otherwise do that"
839 // conditional paths which would obscure its flow. In fact, an early
840 // version of this code did use a unified method which was harder to
841 // follow and, as a result, it had subtle bugs that were hard to
842 // track down. So keeping these two methods separate allows each to
843 // be more readable. It will be good to keep these two in sync as
844 // much as possible.
845
846 assert_heap_not_locked_and_not_at_safepoint();
847 assert(is_humongous(word_size), "attempt_allocation_humongous() "
848 "should only be called for humongous allocations");
849
850 // Humongous objects can exhaust the heap quickly, so we should check if we
851 // need to start a marking cycle at each humongous object allocation. We do
852 // the check before we do the actual allocation. The reason for doing it
853 // before the allocation is that we avoid having to keep track of the newly
854 // allocated memory while we do a GC.
855 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
856 word_size)) {
857 collect(GCCause::_g1_humongous_allocation);
858 }
859
860 // We will loop until a) we manage to successfully perform the
861 // allocation or b) we successfully schedule a collection which
862 // fails to perform the allocation. b) is the only case when we'll
863 // return NULL.
864 HeapWord* result = NULL;
865 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
866 bool should_try_gc;
867 uint gc_count_before;
868
869
870 {
871 MutexLocker x(Heap_lock);
872
873 // Given that humongous objects are not allocated in young
874 // regions, we'll first try to do the allocation without doing a
875 // collection hoping that there's enough space in the heap.
876 result = humongous_obj_allocate(word_size);
877 if (result != NULL) {
878 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
879 policy()->old_gen_alloc_tracker()->
880 add_allocated_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
881 return result;
882 }
883
884 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
885 // the GCLocker initiated GC has been performed and then retry. This includes
886 // the case when the GC Locker is not active but has not been performed.
887 should_try_gc = !GCLocker::needs_gc();
888 // Read the GC count while still holding the Heap_lock.
889 gc_count_before = total_collections();
890 }
891
892 if (should_try_gc) {
893 bool succeeded;
894 result = do_collection_pause(word_size, gc_count_before, &succeeded,
895 GCCause::_g1_humongous_allocation);
896 if (result != NULL) {
897 assert(succeeded, "only way to get back a non-NULL result");
898 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
899 Thread::current()->name(), p2i(result));
900 return result;
901 }
902
903 if (succeeded) {
904 // We successfully scheduled a collection which failed to allocate. No
905 // point in trying to allocate further. We'll just return NULL.
906 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
907 SIZE_FORMAT " words", Thread::current()->name(), word_size);
908 return NULL;
909 }
910 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
911 Thread::current()->name(), word_size);
912 } else {
913 // Failed to schedule a collection.
914 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
915 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
916 SIZE_FORMAT " words", Thread::current()->name(), word_size);
917 return NULL;
918 }
919 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
920 // The GCLocker is either active or the GCLocker initiated
921 // GC has not yet been performed. Stall until it is and
922 // then retry the allocation.
923 GCLocker::stall_until_clear();
924 gclocker_retry_count += 1;
925 }
926
927
928 // We can reach here if we were unsuccessful in scheduling a
929 // collection (because another thread beat us to it) or if we were
930 // stalled due to the GC locker. In either can we should retry the
931 // allocation attempt in case another thread successfully
932 // performed a collection and reclaimed enough space.
933 // Humongous object allocation always needs a lock, so we wait for the retry
934 // in the next iteration of the loop, unlike for the regular iteration case.
935 // Give a warning if we seem to be looping forever.
936
937 if ((QueuedAllocationWarningCount > 0) &&
938 (try_count % QueuedAllocationWarningCount == 0)) {
939 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
940 Thread::current()->name(), try_count, word_size);
941 }
942 }
943
944 ShouldNotReachHere();
945 return NULL;
946 }
947
948 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
949 bool expect_null_mutator_alloc_region) {
950 assert_at_safepoint_on_vm_thread();
951 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
952 "the current alloc region was unexpectedly found to be non-NULL");
953
954 if (!is_humongous(word_size)) {
955 return _allocator->attempt_allocation_locked(word_size);
956 } else {
957 HeapWord* result = humongous_obj_allocate(word_size);
958 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
959 collector_state()->set_initiate_conc_mark_if_possible(true);
960 }
961 return result;
962 }
963
964 ShouldNotReachHere();
965 }
966
967 class PostCompactionPrinterClosure: public HeapRegionClosure {
968 private:
969 G1HRPrinter* _hr_printer;
970 public:
971 bool do_heap_region(HeapRegion* hr) {
972 assert(!hr->is_young(), "not expecting to find young regions");
973 _hr_printer->post_compaction(hr);
974 return false;
975 }
976
977 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
978 : _hr_printer(hr_printer) { }
979 };
980
981 void G1CollectedHeap::print_hrm_post_compaction() {
982 if (_hr_printer.is_active()) {
983 PostCompactionPrinterClosure cl(hr_printer());
984 heap_region_iterate(&cl);
985 }
986 }
987
988 void G1CollectedHeap::abort_concurrent_cycle() {
989 // If we start the compaction before the CM threads finish
990 // scanning the root regions we might trip them over as we'll
991 // be moving objects / updating references. So let's wait until
992 // they are done. By telling them to abort, they should complete
993 // early.
994 _cm->root_regions()->abort();
995 _cm->root_regions()->wait_until_scan_finished();
996
997 // Disable discovery and empty the discovered lists
998 // for the CM ref processor.
999 _ref_processor_cm->disable_discovery();
1000 _ref_processor_cm->abandon_partial_discovery();
1001 _ref_processor_cm->verify_no_references_recorded();
1002
1003 // Abandon current iterations of concurrent marking and concurrent
1004 // refinement, if any are in progress.
1005 concurrent_mark()->concurrent_cycle_abort();
1006 }
1007
1008 void G1CollectedHeap::prepare_heap_for_full_collection() {
1009 // Make sure we'll choose a new allocation region afterwards.
1010 _allocator->release_mutator_alloc_regions();
1011 _allocator->abandon_gc_alloc_regions();
1012
1013 // We may have added regions to the current incremental collection
1014 // set between the last GC or pause and now. We need to clear the
1015 // incremental collection set and then start rebuilding it afresh
1016 // after this full GC.
1017 abandon_collection_set(collection_set());
1018
1019 tear_down_region_sets(false /* free_list_only */);
1020
1021 hrm()->prepare_for_full_collection_start();
1022 }
1023
1024 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1025 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1026 assert_used_and_recalculate_used_equal(this);
1027 _verifier->verify_region_sets_optional();
1028 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1029 _verifier->check_bitmaps("Full GC Start");
1030 }
1031
1032 void G1CollectedHeap::prepare_heap_for_mutators() {
1033 hrm()->prepare_for_full_collection_end();
1034
1035 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1036 ClassLoaderDataGraph::purge();
1037 MetaspaceUtils::verify_metrics();
1038
1039 // Prepare heap for normal collections.
1040 assert(num_free_regions() == 0, "we should not have added any free regions");
1041 rebuild_region_sets(false /* free_list_only */);
1042 abort_refinement();
1043 resize_heap_if_necessary();
1044
1045 // Rebuild the strong code root lists for each region
1046 rebuild_strong_code_roots();
1047
1048 // Purge code root memory
1049 purge_code_root_memory();
1050
1051 // Start a new incremental collection set for the next pause
1052 start_new_collection_set();
1053
1054 _allocator->init_mutator_alloc_regions();
1055
1056 // Post collection state updates.
1057 MetaspaceGC::compute_new_size();
1058 }
1059
1060 void G1CollectedHeap::abort_refinement() {
1061 if (_hot_card_cache->use_cache()) {
1062 _hot_card_cache->reset_hot_cache();
1063 }
1064
1065 // Discard all remembered set updates and reset refinement statistics.
1066 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1067 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1068 "DCQS should be empty");
1069 concurrent_refine()->get_and_reset_refinement_stats();
1070 }
1071
1072 void G1CollectedHeap::verify_after_full_collection() {
1073 _hrm->verify_optional();
1074 _verifier->verify_region_sets_optional();
1075 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1076 // Clear the previous marking bitmap, if needed for bitmap verification.
1077 // Note we cannot do this when we clear the next marking bitmap in
1078 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1079 // objects marked during a full GC against the previous bitmap.
1080 // But we need to clear it before calling check_bitmaps below since
1081 // the full GC has compacted objects and updated TAMS but not updated
1082 // the prev bitmap.
1083 if (G1VerifyBitmaps) {
1084 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1085 _cm->clear_prev_bitmap(workers());
1086 }
1087 // This call implicitly verifies that the next bitmap is clear after Full GC.
1088 _verifier->check_bitmaps("Full GC End");
1089
1090 // At this point there should be no regions in the
1091 // entire heap tagged as young.
1092 assert(check_young_list_empty(), "young list should be empty at this point");
1093
1094 // Note: since we've just done a full GC, concurrent
1095 // marking is no longer active. Therefore we need not
1096 // re-enable reference discovery for the CM ref processor.
1097 // That will be done at the start of the next marking cycle.
1098 // We also know that the STW processor should no longer
1099 // discover any new references.
1100 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1101 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1102 _ref_processor_stw->verify_no_references_recorded();
1103 _ref_processor_cm->verify_no_references_recorded();
1104 }
1105
1106 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1107 // Post collection logging.
1108 // We should do this after we potentially resize the heap so
1109 // that all the COMMIT / UNCOMMIT events are generated before
1110 // the compaction events.
1111 print_hrm_post_compaction();
1112 heap_transition->print();
1113 print_heap_after_gc();
1114 print_heap_regions();
1115 }
1116
1117 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1118 bool clear_all_soft_refs) {
1119 assert_at_safepoint_on_vm_thread();
1120
1121 if (GCLocker::check_active_before_gc()) {
1122 // Full GC was not completed.
1123 return false;
1124 }
1125
1126 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1127 soft_ref_policy()->should_clear_all_soft_refs();
1128
1129 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1130 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1131
1132 collector.prepare_collection();
1133 collector.collect();
1134 collector.complete_collection();
1135
1136 // Full collection was successfully completed.
1137 return true;
1138 }
1139
1140 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1141 // Currently, there is no facility in the do_full_collection(bool) API to notify
1142 // the caller that the collection did not succeed (e.g., because it was locked
1143 // out by the GC locker). So, right now, we'll ignore the return value.
1144 bool dummy = do_full_collection(true, /* explicit_gc */
1145 clear_all_soft_refs);
1146 }
1147
1148 void G1CollectedHeap::resize_heap_if_necessary() {
1149 assert_at_safepoint_on_vm_thread();
1150
1151 // Capacity, free and used after the GC counted as full regions to
1152 // include the waste in the following calculations.
1153 const size_t capacity_after_gc = capacity();
1154 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1155
1156 // This is enforced in arguments.cpp.
1157 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1158 "otherwise the code below doesn't make sense");
1159
1160 // We don't have floating point command-line arguments
1161 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1162 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1163 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1164 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1165
1166 // We have to be careful here as these two calculations can overflow
1167 // 32-bit size_t's.
1168 double used_after_gc_d = (double) used_after_gc;
1169 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1170 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1171
1172 // Let's make sure that they are both under the max heap size, which
1173 // by default will make them fit into a size_t.
1174 double desired_capacity_upper_bound = (double) MaxHeapSize;
1175 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1176 desired_capacity_upper_bound);
1177 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1178 desired_capacity_upper_bound);
1179
1180 // We can now safely turn them into size_t's.
1181 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1182 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1183
1184 // This assert only makes sense here, before we adjust them
1185 // with respect to the min and max heap size.
1186 assert(minimum_desired_capacity <= maximum_desired_capacity,
1187 "minimum_desired_capacity = " SIZE_FORMAT ", "
1188 "maximum_desired_capacity = " SIZE_FORMAT,
1189 minimum_desired_capacity, maximum_desired_capacity);
1190
1191 // Should not be greater than the heap max size. No need to adjust
1192 // it with respect to the heap min size as it's a lower bound (i.e.,
1193 // we'll try to make the capacity larger than it, not smaller).
1194 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1195 // Should not be less than the heap min size. No need to adjust it
1196 // with respect to the heap max size as it's an upper bound (i.e.,
1197 // we'll try to make the capacity smaller than it, not greater).
1198 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1199
1200 if (capacity_after_gc < minimum_desired_capacity) {
1201 // Don't expand unless it's significant
1202 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1203
1204 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1205 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1206 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1207 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1208
1209 expand(expand_bytes, _workers);
1210
1211 // No expansion, now see if we want to shrink
1212 } else if (capacity_after_gc > maximum_desired_capacity) {
1213 // Capacity too large, compute shrinking size
1214 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1215
1216 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1217 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1218 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1219 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1220
1221 shrink(shrink_bytes);
1222 }
1223 }
1224
1225 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1226 bool do_gc,
1227 bool clear_all_soft_refs,
1228 bool expect_null_mutator_alloc_region,
1229 bool* gc_succeeded) {
1230 *gc_succeeded = true;
1231 // Let's attempt the allocation first.
1232 HeapWord* result =
1233 attempt_allocation_at_safepoint(word_size,
1234 expect_null_mutator_alloc_region);
1235 if (result != NULL) {
1236 return result;
1237 }
1238
1239 // In a G1 heap, we're supposed to keep allocation from failing by
1240 // incremental pauses. Therefore, at least for now, we'll favor
1241 // expansion over collection. (This might change in the future if we can
1242 // do something smarter than full collection to satisfy a failed alloc.)
1243 result = expand_and_allocate(word_size);
1244 if (result != NULL) {
1245 return result;
1246 }
1247
1248 if (do_gc) {
1249 // Expansion didn't work, we'll try to do a Full GC.
1250 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1251 clear_all_soft_refs);
1252 }
1253
1254 return NULL;
1255 }
1256
1257 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1258 bool* succeeded) {
1259 assert_at_safepoint_on_vm_thread();
1260
1261 // Attempts to allocate followed by Full GC.
1262 HeapWord* result =
1263 satisfy_failed_allocation_helper(word_size,
1264 true, /* do_gc */
1265 false, /* clear_all_soft_refs */
1266 false, /* expect_null_mutator_alloc_region */
1267 succeeded);
1268
1269 if (result != NULL || !*succeeded) {
1270 return result;
1271 }
1272
1273 // Attempts to allocate followed by Full GC that will collect all soft references.
1274 result = satisfy_failed_allocation_helper(word_size,
1275 true, /* do_gc */
1276 true, /* clear_all_soft_refs */
1277 true, /* expect_null_mutator_alloc_region */
1278 succeeded);
1279
1280 if (result != NULL || !*succeeded) {
1281 return result;
1282 }
1283
1284 // Attempts to allocate, no GC
1285 result = satisfy_failed_allocation_helper(word_size,
1286 false, /* do_gc */
1287 false, /* clear_all_soft_refs */
1288 true, /* expect_null_mutator_alloc_region */
1289 succeeded);
1290
1291 if (result != NULL) {
1292 return result;
1293 }
1294
1295 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1296 "Flag should have been handled and cleared prior to this point");
1297
1298 // What else? We might try synchronous finalization later. If the total
1299 // space available is large enough for the allocation, then a more
1300 // complete compaction phase than we've tried so far might be
1301 // appropriate.
1302 return NULL;
1303 }
1304
1305 // Attempting to expand the heap sufficiently
1306 // to support an allocation of the given "word_size". If
1307 // successful, perform the allocation and return the address of the
1308 // allocated block, or else "NULL".
1309
1310 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1311 assert_at_safepoint_on_vm_thread();
1312
1313 _verifier->verify_region_sets_optional();
1314
1315 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1316 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1317 word_size * HeapWordSize);
1318
1319
1320 if (expand(expand_bytes, _workers)) {
1321 _hrm->verify_optional();
1322 _verifier->verify_region_sets_optional();
1323 return attempt_allocation_at_safepoint(word_size,
1324 false /* expect_null_mutator_alloc_region */);
1325 }
1326 return NULL;
1327 }
1328
1329 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1330 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1331 aligned_expand_bytes = align_up(aligned_expand_bytes,
1332 HeapRegion::GrainBytes);
1333
1334 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1335 expand_bytes, aligned_expand_bytes);
1336
1337 if (is_maximal_no_gc()) {
1338 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1339 return false;
1340 }
1341
1342 double expand_heap_start_time_sec = os::elapsedTime();
1343 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1344 assert(regions_to_expand > 0, "Must expand by at least one region");
1345
1346 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1347 if (expand_time_ms != NULL) {
1348 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1349 }
1350
1351 if (expanded_by > 0) {
1352 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1353 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1354 policy()->record_new_heap_size(num_regions());
1355 } else {
1356 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1357
1358 // The expansion of the virtual storage space was unsuccessful.
1359 // Let's see if it was because we ran out of swap.
1360 if (G1ExitOnExpansionFailure &&
1361 _hrm->available() >= regions_to_expand) {
1362 // We had head room...
1363 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1364 }
1365 }
1366 return regions_to_expand > 0;
1367 }
1368
1369 bool G1CollectedHeap::expand_single_region(uint node_index) {
1370 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1371
1372 if (expanded_by == 0) {
1373 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1374 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1375 return false;
1376 }
1377
1378 policy()->record_new_heap_size(num_regions());
1379 return true;
1380 }
1381
1382 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1383 size_t aligned_shrink_bytes =
1384 ReservedSpace::page_align_size_down(shrink_bytes);
1385 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1386 HeapRegion::GrainBytes);
1387 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1388
1389 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1390 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1391
1392 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1393 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1394 if (num_regions_removed > 0) {
1395 policy()->record_new_heap_size(num_regions());
1396 } else {
1397 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1398 }
1399 }
1400
1401 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1402 _verifier->verify_region_sets_optional();
1403
1404 // We should only reach here at the end of a Full GC or during Remark which
1405 // means we should not not be holding to any GC alloc regions. The method
1406 // below will make sure of that and do any remaining clean up.
1407 _allocator->abandon_gc_alloc_regions();
1408
1409 // Instead of tearing down / rebuilding the free lists here, we
1410 // could instead use the remove_all_pending() method on free_list to
1411 // remove only the ones that we need to remove.
1412 tear_down_region_sets(true /* free_list_only */);
1413 shrink_helper(shrink_bytes);
1414 rebuild_region_sets(true /* free_list_only */);
1415
1416 _hrm->verify_optional();
1417 _verifier->verify_region_sets_optional();
1418 }
1419
1420 class OldRegionSetChecker : public HeapRegionSetChecker {
1421 public:
1422 void check_mt_safety() {
1423 // Master Old Set MT safety protocol:
1424 // (a) If we're at a safepoint, operations on the master old set
1425 // should be invoked:
1426 // - by the VM thread (which will serialize them), or
1427 // - by the GC workers while holding the FreeList_lock, if we're
1428 // at a safepoint for an evacuation pause (this lock is taken
1429 // anyway when an GC alloc region is retired so that a new one
1430 // is allocated from the free list), or
1431 // - by the GC workers while holding the OldSets_lock, if we're at a
1432 // safepoint for a cleanup pause.
1433 // (b) If we're not at a safepoint, operations on the master old set
1434 // should be invoked while holding the Heap_lock.
1435
1436 if (SafepointSynchronize::is_at_safepoint()) {
1437 guarantee(Thread::current()->is_VM_thread() ||
1438 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1439 "master old set MT safety protocol at a safepoint");
1440 } else {
1441 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1442 }
1443 }
1444 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1445 const char* get_description() { return "Old Regions"; }
1446 };
1447
1448 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1449 public:
1450 void check_mt_safety() {
1451 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1452 "May only change archive regions during initialization or safepoint.");
1453 }
1454 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1455 const char* get_description() { return "Archive Regions"; }
1456 };
1457
1458 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1459 public:
1460 void check_mt_safety() {
1461 // Humongous Set MT safety protocol:
1462 // (a) If we're at a safepoint, operations on the master humongous
1463 // set should be invoked by either the VM thread (which will
1464 // serialize them) or by the GC workers while holding the
1465 // OldSets_lock.
1466 // (b) If we're not at a safepoint, operations on the master
1467 // humongous set should be invoked while holding the Heap_lock.
1468
1469 if (SafepointSynchronize::is_at_safepoint()) {
1470 guarantee(Thread::current()->is_VM_thread() ||
1471 OldSets_lock->owned_by_self(),
1472 "master humongous set MT safety protocol at a safepoint");
1473 } else {
1474 guarantee(Heap_lock->owned_by_self(),
1475 "master humongous set MT safety protocol outside a safepoint");
1476 }
1477 }
1478 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1479 const char* get_description() { return "Humongous Regions"; }
1480 };
1481
1482 G1CollectedHeap::G1CollectedHeap() :
1483 CollectedHeap(),
1484 _young_gen_sampling_thread(NULL),
1485 _workers(NULL),
1486 _card_table(NULL),
1487 _soft_ref_policy(),
1488 _old_set("Old Region Set", new OldRegionSetChecker()),
1489 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1490 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1491 _bot(NULL),
1492 _listener(),
1493 _numa(G1NUMA::create()),
1494 _hrm(NULL),
1495 _allocator(NULL),
1496 _verifier(NULL),
1497 _summary_bytes_used(0),
1498 _bytes_used_during_gc(0),
1499 _archive_allocator(NULL),
1500 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1501 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1502 _expand_heap_after_alloc_failure(true),
1503 _g1mm(NULL),
1504 _humongous_reclaim_candidates(),
1505 _has_humongous_reclaim_candidates(false),
1506 _hr_printer(),
1507 _collector_state(),
1508 _old_marking_cycles_started(0),
1509 _old_marking_cycles_completed(0),
1510 _eden(),
1511 _survivor(),
1512 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1513 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1514 _policy(G1Policy::create_policy(_gc_timer_stw)),
1515 _heap_sizing_policy(NULL),
1516 _collection_set(this, _policy),
1517 _hot_card_cache(NULL),
1518 _rem_set(NULL),
1519 _cm(NULL),
1520 _cm_thread(NULL),
1521 _cr(NULL),
1522 _task_queues(NULL),
1523 _evacuation_failed(false),
1524 _evacuation_failed_info_array(NULL),
1525 _preserved_marks_set(true /* in_c_heap */),
1526 #ifndef PRODUCT
1527 _evacuation_failure_alot_for_current_gc(false),
1528 _evacuation_failure_alot_gc_number(0),
1529 _evacuation_failure_alot_count(0),
1530 #endif
1531 _ref_processor_stw(NULL),
1532 _is_alive_closure_stw(this),
1533 _is_subject_to_discovery_stw(this),
1534 _ref_processor_cm(NULL),
1535 _is_alive_closure_cm(this),
1536 _is_subject_to_discovery_cm(this),
1537 _region_attr() {
1538
1539 _verifier = new G1HeapVerifier(this);
1540
1541 _allocator = new G1Allocator(this);
1542
1543 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1544
1545 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1546
1547 // Override the default _filler_array_max_size so that no humongous filler
1548 // objects are created.
1549 _filler_array_max_size = _humongous_object_threshold_in_words;
1550
1551 uint n_queues = ParallelGCThreads;
1552 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1553
1554 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1555
1556 for (uint i = 0; i < n_queues; i++) {
1557 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1558 q->initialize();
1559 _task_queues->register_queue(i, q);
1560 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1561 }
1562
1563 // Initialize the G1EvacuationFailureALot counters and flags.
1564 NOT_PRODUCT(reset_evacuation_should_fail();)
1565 _gc_tracer_stw->initialize();
1566
1567 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1568 }
1569
1570 static size_t actual_reserved_page_size(ReservedSpace rs) {
1571 size_t page_size = os::vm_page_size();
1572 if (UseLargePages) {
1573 // There are two ways to manage large page memory.
1574 // 1. OS supports committing large page memory.
1575 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1576 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1577 // we reserved memory without large page.
1578 if (os::can_commit_large_page_memory() || rs.special()) {
1579 // An alignment at ReservedSpace comes from preferred page size or
1580 // heap alignment, and if the alignment came from heap alignment, it could be
1581 // larger than large pages size. So need to cap with the large page size.
1582 page_size = MIN2(rs.alignment(), os::large_page_size());
1583 }
1584 }
1585
1586 return page_size;
1587 }
1588
1589 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1590 size_t size,
1591 size_t translation_factor) {
1592 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1593 // Allocate a new reserved space, preferring to use large pages.
1594 ReservedSpace rs(size, preferred_page_size);
1595 size_t page_size = actual_reserved_page_size(rs);
1596 G1RegionToSpaceMapper* result =
1597 G1RegionToSpaceMapper::create_mapper(rs,
1598 size,
1599 page_size,
1600 HeapRegion::GrainBytes,
1601 translation_factor,
1602 mtGC);
1603
1604 os::trace_page_sizes_for_requested_size(description,
1605 size,
1606 preferred_page_size,
1607 page_size,
1608 rs.base(),
1609 rs.size());
1610
1611 return result;
1612 }
1613
1614 jint G1CollectedHeap::initialize_concurrent_refinement() {
1615 jint ecode = JNI_OK;
1616 _cr = G1ConcurrentRefine::create(&ecode);
1617 return ecode;
1618 }
1619
1620 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1621 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1622 if (_young_gen_sampling_thread->osthread() == NULL) {
1623 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1624 return JNI_ENOMEM;
1625 }
1626 return JNI_OK;
1627 }
1628
1629 jint G1CollectedHeap::initialize() {
1630
1631 // Necessary to satisfy locking discipline assertions.
1632
1633 MutexLocker x(Heap_lock);
1634
1635 // While there are no constraints in the GC code that HeapWordSize
1636 // be any particular value, there are multiple other areas in the
1637 // system which believe this to be true (e.g. oop->object_size in some
1638 // cases incorrectly returns the size in wordSize units rather than
1639 // HeapWordSize).
1640 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1641
1642 size_t init_byte_size = InitialHeapSize;
1643 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1644
1645 // Ensure that the sizes are properly aligned.
1646 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1647 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1648 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1649
1650 // Reserve the maximum.
1651
1652 // When compressed oops are enabled, the preferred heap base
1653 // is calculated by subtracting the requested size from the
1654 // 32Gb boundary and using the result as the base address for
1655 // heap reservation. If the requested size is not aligned to
1656 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1657 // into the ReservedHeapSpace constructor) then the actual
1658 // base of the reserved heap may end up differing from the
1659 // address that was requested (i.e. the preferred heap base).
1660 // If this happens then we could end up using a non-optimal
1661 // compressed oops mode.
1662
1663 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1664 HeapAlignment);
1665
1666 initialize_reserved_region(heap_rs);
1667
1668 // Create the barrier set for the entire reserved region.
1669 G1CardTable* ct = new G1CardTable(heap_rs.region());
1670 ct->initialize();
1671 G1BarrierSet* bs = new G1BarrierSet(ct);
1672 bs->initialize();
1673 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1674 BarrierSet::set_barrier_set(bs);
1675 _card_table = ct;
1676
1677 {
1678 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1679 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1680 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1681 }
1682
1683 // Create the hot card cache.
1684 _hot_card_cache = new G1HotCardCache(this);
1685
1686 // Carve out the G1 part of the heap.
1687 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1688 size_t page_size = actual_reserved_page_size(heap_rs);
1689 G1RegionToSpaceMapper* heap_storage =
1690 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1691 g1_rs.size(),
1692 page_size,
1693 HeapRegion::GrainBytes,
1694 1,
1695 mtJavaHeap);
1696 if(heap_storage == NULL) {
1697 vm_shutdown_during_initialization("Could not initialize G1 heap");
1698 return JNI_ERR;
1699 }
1700
1701 os::trace_page_sizes("Heap",
1702 MinHeapSize,
1703 reserved_byte_size,
1704 page_size,
1705 heap_rs.base(),
1706 heap_rs.size());
1707 heap_storage->set_mapping_changed_listener(&_listener);
1708
1709 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1710 G1RegionToSpaceMapper* bot_storage =
1711 create_aux_memory_mapper("Block Offset Table",
1712 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1713 G1BlockOffsetTable::heap_map_factor());
1714
1715 G1RegionToSpaceMapper* cardtable_storage =
1716 create_aux_memory_mapper("Card Table",
1717 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1718 G1CardTable::heap_map_factor());
1719
1720 G1RegionToSpaceMapper* card_counts_storage =
1721 create_aux_memory_mapper("Card Counts Table",
1722 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1723 G1CardCounts::heap_map_factor());
1724
1725 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1726 G1RegionToSpaceMapper* prev_bitmap_storage =
1727 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1728 G1RegionToSpaceMapper* next_bitmap_storage =
1729 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1730
1731 _hrm = HeapRegionManager::create_manager(this);
1732
1733 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1734 _card_table->initialize(cardtable_storage);
1735
1736 // Do later initialization work for concurrent refinement.
1737 _hot_card_cache->initialize(card_counts_storage);
1738
1739 // 6843694 - ensure that the maximum region index can fit
1740 // in the remembered set structures.
1741 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1742 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1743
1744 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1745 // start within the first card.
1746 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1747 // Also create a G1 rem set.
1748 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1749 _rem_set->initialize(max_reserved_capacity(), max_regions());
1750
1751 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1752 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1753 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1754 "too many cards per region");
1755
1756 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1757
1758 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1759
1760 {
1761 HeapWord* start = _hrm->reserved().start();
1762 HeapWord* end = _hrm->reserved().end();
1763 size_t granularity = HeapRegion::GrainBytes;
1764
1765 _region_attr.initialize(start, end, granularity);
1766 _humongous_reclaim_candidates.initialize(start, end, granularity);
1767 }
1768
1769 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1770 true /* are_GC_task_threads */,
1771 false /* are_ConcurrentGC_threads */);
1772 if (_workers == NULL) {
1773 return JNI_ENOMEM;
1774 }
1775 _workers->initialize_workers();
1776
1777 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1778
1779 // Create the G1ConcurrentMark data structure and thread.
1780 // (Must do this late, so that "max_regions" is defined.)
1781 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1782 _cm_thread = _cm->cm_thread();
1783
1784 // Now expand into the initial heap size.
1785 if (!expand(init_byte_size, _workers)) {
1786 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1787 return JNI_ENOMEM;
1788 }
1789
1790 // Perform any initialization actions delegated to the policy.
1791 policy()->init(this, &_collection_set);
1792
1793 jint ecode = initialize_concurrent_refinement();
1794 if (ecode != JNI_OK) {
1795 return ecode;
1796 }
1797
1798 ecode = initialize_young_gen_sampling_thread();
1799 if (ecode != JNI_OK) {
1800 return ecode;
1801 }
1802
1803 {
1804 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1805 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1806 dcqs.set_max_cards(concurrent_refine()->red_zone());
1807 }
1808
1809 // Here we allocate the dummy HeapRegion that is required by the
1810 // G1AllocRegion class.
1811 HeapRegion* dummy_region = _hrm->get_dummy_region();
1812
1813 // We'll re-use the same region whether the alloc region will
1814 // require BOT updates or not and, if it doesn't, then a non-young
1815 // region will complain that it cannot support allocations without
1816 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1817 dummy_region->set_eden();
1818 // Make sure it's full.
1819 dummy_region->set_top(dummy_region->end());
1820 G1AllocRegion::setup(this, dummy_region);
1821
1822 _allocator->init_mutator_alloc_regions();
1823
1824 // Do create of the monitoring and management support so that
1825 // values in the heap have been properly initialized.
1826 _g1mm = new G1MonitoringSupport(this);
1827
1828 G1StringDedup::initialize();
1829
1830 _preserved_marks_set.init(ParallelGCThreads);
1831
1832 _collection_set.initialize(max_regions());
1833
1834 G1InitLogger::print();
1835
1836 return JNI_OK;
1837 }
1838
1839 void G1CollectedHeap::stop() {
1840 // Stop all concurrent threads. We do this to make sure these threads
1841 // do not continue to execute and access resources (e.g. logging)
1842 // that are destroyed during shutdown.
1843 _cr->stop();
1844 _young_gen_sampling_thread->stop();
1845 _cm_thread->stop();
1846 if (G1StringDedup::is_enabled()) {
1847 G1StringDedup::stop();
1848 }
1849 }
1850
1851 void G1CollectedHeap::safepoint_synchronize_begin() {
1852 SuspendibleThreadSet::synchronize();
1853 }
1854
1855 void G1CollectedHeap::safepoint_synchronize_end() {
1856 SuspendibleThreadSet::desynchronize();
1857 }
1858
1859 void G1CollectedHeap::post_initialize() {
1860 CollectedHeap::post_initialize();
1861 ref_processing_init();
1862 }
1863
1864 void G1CollectedHeap::ref_processing_init() {
1865 // Reference processing in G1 currently works as follows:
1866 //
1867 // * There are two reference processor instances. One is
1868 // used to record and process discovered references
1869 // during concurrent marking; the other is used to
1870 // record and process references during STW pauses
1871 // (both full and incremental).
1872 // * Both ref processors need to 'span' the entire heap as
1873 // the regions in the collection set may be dotted around.
1874 //
1875 // * For the concurrent marking ref processor:
1876 // * Reference discovery is enabled at initial marking.
1877 // * Reference discovery is disabled and the discovered
1878 // references processed etc during remarking.
1879 // * Reference discovery is MT (see below).
1880 // * Reference discovery requires a barrier (see below).
1881 // * Reference processing may or may not be MT
1882 // (depending on the value of ParallelRefProcEnabled
1883 // and ParallelGCThreads).
1884 // * A full GC disables reference discovery by the CM
1885 // ref processor and abandons any entries on it's
1886 // discovered lists.
1887 //
1888 // * For the STW processor:
1889 // * Non MT discovery is enabled at the start of a full GC.
1890 // * Processing and enqueueing during a full GC is non-MT.
1891 // * During a full GC, references are processed after marking.
1892 //
1893 // * Discovery (may or may not be MT) is enabled at the start
1894 // of an incremental evacuation pause.
1895 // * References are processed near the end of a STW evacuation pause.
1896 // * For both types of GC:
1897 // * Discovery is atomic - i.e. not concurrent.
1898 // * Reference discovery will not need a barrier.
1899
1900 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1901
1902 // Concurrent Mark ref processor
1903 _ref_processor_cm =
1904 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1905 mt_processing, // mt processing
1906 ParallelGCThreads, // degree of mt processing
1907 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1908 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1909 false, // Reference discovery is not atomic
1910 &_is_alive_closure_cm, // is alive closure
1911 true); // allow changes to number of processing threads
1912
1913 // STW ref processor
1914 _ref_processor_stw =
1915 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1916 mt_processing, // mt processing
1917 ParallelGCThreads, // degree of mt processing
1918 (ParallelGCThreads > 1), // mt discovery
1919 ParallelGCThreads, // degree of mt discovery
1920 true, // Reference discovery is atomic
1921 &_is_alive_closure_stw, // is alive closure
1922 true); // allow changes to number of processing threads
1923 }
1924
1925 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1926 return &_soft_ref_policy;
1927 }
1928
1929 size_t G1CollectedHeap::capacity() const {
1930 return _hrm->length() * HeapRegion::GrainBytes;
1931 }
1932
1933 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1934 return _hrm->total_free_bytes();
1935 }
1936
1937 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1938 _hot_card_cache->drain(cl, worker_id);
1939 }
1940
1941 // Computes the sum of the storage used by the various regions.
1942 size_t G1CollectedHeap::used() const {
1943 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1944 if (_archive_allocator != NULL) {
1945 result += _archive_allocator->used();
1946 }
1947 return result;
1948 }
1949
1950 size_t G1CollectedHeap::used_unlocked() const {
1951 return _summary_bytes_used;
1952 }
1953
1954 class SumUsedClosure: public HeapRegionClosure {
1955 size_t _used;
1956 public:
1957 SumUsedClosure() : _used(0) {}
1958 bool do_heap_region(HeapRegion* r) {
1959 _used += r->used();
1960 return false;
1961 }
1962 size_t result() { return _used; }
1963 };
1964
1965 size_t G1CollectedHeap::recalculate_used() const {
1966 SumUsedClosure blk;
1967 heap_region_iterate(&blk);
1968 return blk.result();
1969 }
1970
1971 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1972 switch (cause) {
1973 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1974 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1975 case GCCause::_wb_conc_mark: return true;
1976 default : return false;
1977 }
1978 }
1979
1980 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1981 switch (cause) {
1982 case GCCause::_g1_humongous_allocation: return true;
1983 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1984 case GCCause::_wb_breakpoint: return true;
1985 default: return is_user_requested_concurrent_full_gc(cause);
1986 }
1987 }
1988
1989 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1990 if (policy()->force_upgrade_to_full()) {
1991 return true;
1992 } else if (should_do_concurrent_full_gc(_gc_cause)) {
1993 return false;
1994 } else if (has_regions_left_for_allocation()) {
1995 return false;
1996 } else {
1997 return true;
1998 }
1999 }
2000
2001 #ifndef PRODUCT
2002 void G1CollectedHeap::allocate_dummy_regions() {
2003 // Let's fill up most of the region
2004 size_t word_size = HeapRegion::GrainWords - 1024;
2005 // And as a result the region we'll allocate will be humongous.
2006 guarantee(is_humongous(word_size), "sanity");
2007
2008 // _filler_array_max_size is set to humongous object threshold
2009 // but temporarily change it to use CollectedHeap::fill_with_object().
2010 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2011
2012 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2013 // Let's use the existing mechanism for the allocation
2014 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2015 if (dummy_obj != NULL) {
2016 MemRegion mr(dummy_obj, word_size);
2017 CollectedHeap::fill_with_object(mr);
2018 } else {
2019 // If we can't allocate once, we probably cannot allocate
2020 // again. Let's get out of the loop.
2021 break;
2022 }
2023 }
2024 }
2025 #endif // !PRODUCT
2026
2027 void G1CollectedHeap::increment_old_marking_cycles_started() {
2028 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2029 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2030 "Wrong marking cycle count (started: %d, completed: %d)",
2031 _old_marking_cycles_started, _old_marking_cycles_completed);
2032
2033 _old_marking_cycles_started++;
2034 }
2035
2036 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2037 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2038
2039 // We assume that if concurrent == true, then the caller is a
2040 // concurrent thread that was joined the Suspendible Thread
2041 // Set. If there's ever a cheap way to check this, we should add an
2042 // assert here.
2043
2044 // Given that this method is called at the end of a Full GC or of a
2045 // concurrent cycle, and those can be nested (i.e., a Full GC can
2046 // interrupt a concurrent cycle), the number of full collections
2047 // completed should be either one (in the case where there was no
2048 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2049 // behind the number of full collections started.
2050
2051 // This is the case for the inner caller, i.e. a Full GC.
2052 assert(concurrent ||
2053 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2054 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2055 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2056 "is inconsistent with _old_marking_cycles_completed = %u",
2057 _old_marking_cycles_started, _old_marking_cycles_completed);
2058
2059 // This is the case for the outer caller, i.e. the concurrent cycle.
2060 assert(!concurrent ||
2061 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2062 "for outer caller (concurrent cycle): "
2063 "_old_marking_cycles_started = %u "
2064 "is inconsistent with _old_marking_cycles_completed = %u",
2065 _old_marking_cycles_started, _old_marking_cycles_completed);
2066
2067 _old_marking_cycles_completed += 1;
2068
2069 // We need to clear the "in_progress" flag in the CM thread before
2070 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2071 // is set) so that if a waiter requests another System.gc() it doesn't
2072 // incorrectly see that a marking cycle is still in progress.
2073 if (concurrent) {
2074 _cm_thread->set_idle();
2075 }
2076
2077 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2078 // for a full GC to finish that their wait is over.
2079 ml.notify_all();
2080 }
2081
2082 void G1CollectedHeap::collect(GCCause::Cause cause) {
2083 try_collect(cause);
2084 }
2085
2086 // Return true if (x < y) with allowance for wraparound.
2087 static bool gc_counter_less_than(uint x, uint y) {
2088 return (x - y) > (UINT_MAX/2);
2089 }
2090
2091 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2092 // Macro so msg printing is format-checked.
2093 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2094 do { \
2095 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2096 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2097 ResourceMark rm; /* For thread name. */ \
2098 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2099 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2100 Thread::current()->name(), \
2101 GCCause::to_string(cause)); \
2102 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2103 } \
2104 } while (0)
2105
2106 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2107 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2108
2109 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2110 uint gc_counter,
2111 uint old_marking_started_before) {
2112 assert_heap_not_locked();
2113 assert(should_do_concurrent_full_gc(cause),
2114 "Non-concurrent cause %s", GCCause::to_string(cause));
2115
2116 for (uint i = 1; true; ++i) {
2117 // Try to schedule an initial-mark evacuation pause that will
2118 // start a concurrent cycle.
2119 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2120 VM_G1TryInitiateConcMark op(gc_counter,
2121 cause,
2122 policy()->max_pause_time_ms());
2123 VMThread::execute(&op);
2124
2125 // Request is trivially finished.
2126 if (cause == GCCause::_g1_periodic_collection) {
2127 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2128 return op.gc_succeeded();
2129 }
2130
2131 // If VMOp skipped initiating concurrent marking cycle because
2132 // we're terminating, then we're done.
2133 if (op.terminating()) {
2134 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2135 return false;
2136 }
2137
2138 // Lock to get consistent set of values.
2139 uint old_marking_started_after;
2140 uint old_marking_completed_after;
2141 {
2142 MutexLocker ml(Heap_lock);
2143 // Update gc_counter for retrying VMOp if needed. Captured here to be
2144 // consistent with the values we use below for termination tests. If
2145 // a retry is needed after a possible wait, and another collection
2146 // occurs in the meantime, it will cause our retry to be skipped and
2147 // we'll recheck for termination with updated conditions from that
2148 // more recent collection. That's what we want, rather than having
2149 // our retry possibly perform an unnecessary collection.
2150 gc_counter = total_collections();
2151 old_marking_started_after = _old_marking_cycles_started;
2152 old_marking_completed_after = _old_marking_cycles_completed;
2153 }
2154
2155 if (cause == GCCause::_wb_breakpoint) {
2156 if (op.gc_succeeded()) {
2157 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2158 return true;
2159 }
2160 // When _wb_breakpoint there can't be another cycle or deferred.
2161 assert(!op.cycle_already_in_progress(), "invariant");
2162 assert(!op.whitebox_attached(), "invariant");
2163 // Concurrent cycle attempt might have been cancelled by some other
2164 // collection, so retry. Unlike other cases below, we want to retry
2165 // even if cancelled by a STW full collection, because we really want
2166 // to start a concurrent cycle.
2167 if (old_marking_started_before != old_marking_started_after) {
2168 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2169 old_marking_started_before = old_marking_started_after;
2170 }
2171 } else if (!GCCause::is_user_requested_gc(cause)) {
2172 // For an "automatic" (not user-requested) collection, we just need to
2173 // ensure that progress is made.
2174 //
2175 // Request is finished if any of
2176 // (1) the VMOp successfully performed a GC,
2177 // (2) a concurrent cycle was already in progress,
2178 // (3) whitebox is controlling concurrent cycles,
2179 // (4) a new cycle was started (by this thread or some other), or
2180 // (5) a Full GC was performed.
2181 // Cases (4) and (5) are detected together by a change to
2182 // _old_marking_cycles_started.
2183 //
2184 // Note that (1) does not imply (4). If we're still in the mixed
2185 // phase of an earlier concurrent collection, the request to make the
2186 // collection an initial-mark won't be honored. If we don't check for
2187 // both conditions we'll spin doing back-to-back collections.
2188 if (op.gc_succeeded() ||
2189 op.cycle_already_in_progress() ||
2190 op.whitebox_attached() ||
2191 (old_marking_started_before != old_marking_started_after)) {
2192 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2193 return true;
2194 }
2195 } else { // User-requested GC.
2196 // For a user-requested collection, we want to ensure that a complete
2197 // full collection has been performed before returning, but without
2198 // waiting for more than needed.
2199
2200 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2201 // new cycle was started. That's good, because it's not clear what we
2202 // should do otherwise. Trying again just does back to back GCs.
2203 // Can't wait for someone else to start a cycle. And returning fails
2204 // to meet the goal of ensuring a full collection was performed.
2205 assert(!op.gc_succeeded() ||
2206 (old_marking_started_before != old_marking_started_after),
2207 "invariant: succeeded %s, started before %u, started after %u",
2208 BOOL_TO_STR(op.gc_succeeded()),
2209 old_marking_started_before, old_marking_started_after);
2210
2211 // Request is finished if a full collection (concurrent or stw)
2212 // was started after this request and has completed, e.g.
2213 // started_before < completed_after.
2214 if (gc_counter_less_than(old_marking_started_before,
2215 old_marking_completed_after)) {
2216 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2217 return true;
2218 }
2219
2220 if (old_marking_started_after != old_marking_completed_after) {
2221 // If there is an in-progress cycle (possibly started by us), then
2222 // wait for that cycle to complete, e.g.
2223 // while completed_now < started_after.
2224 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2225 MonitorLocker ml(G1OldGCCount_lock);
2226 while (gc_counter_less_than(_old_marking_cycles_completed,
2227 old_marking_started_after)) {
2228 ml.wait();
2229 }
2230 // Request is finished if the collection we just waited for was
2231 // started after this request.
2232 if (old_marking_started_before != old_marking_started_after) {
2233 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2234 return true;
2235 }
2236 }
2237
2238 // If VMOp was successful then it started a new cycle that the above
2239 // wait &etc should have recognized as finishing this request. This
2240 // differs from a non-user-request, where gc_succeeded does not imply
2241 // a new cycle was started.
2242 assert(!op.gc_succeeded(), "invariant");
2243
2244 if (op.cycle_already_in_progress()) {
2245 // If VMOp failed because a cycle was already in progress, it
2246 // is now complete. But it didn't finish this user-requested
2247 // GC, so try again.
2248 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2249 continue;
2250 } else if (op.whitebox_attached()) {
2251 // If WhiteBox wants control, wait for notification of a state
2252 // change in the controller, then try again. Don't wait for
2253 // release of control, since collections may complete while in
2254 // control. Note: This won't recognize a STW full collection
2255 // while waiting; we can't wait on multiple monitors.
2256 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2257 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2258 if (ConcurrentGCBreakpoints::is_controlled()) {
2259 ml.wait();
2260 }
2261 continue;
2262 }
2263 }
2264
2265 // Collection failed and should be retried.
2266 assert(op.transient_failure(), "invariant");
2267
2268 if (GCLocker::is_active_and_needs_gc()) {
2269 // If GCLocker is active, wait until clear before retrying.
2270 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2271 GCLocker::stall_until_clear();
2272 }
2273
2274 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2275 }
2276 }
2277
2278 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2279 assert_heap_not_locked();
2280
2281 // Lock to get consistent set of values.
2282 uint gc_count_before;
2283 uint full_gc_count_before;
2284 uint old_marking_started_before;
2285 {
2286 MutexLocker ml(Heap_lock);
2287 gc_count_before = total_collections();
2288 full_gc_count_before = total_full_collections();
2289 old_marking_started_before = _old_marking_cycles_started;
2290 }
2291
2292 if (should_do_concurrent_full_gc(cause)) {
2293 return try_collect_concurrently(cause,
2294 gc_count_before,
2295 old_marking_started_before);
2296 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2297 // Indicate failure to be consistent with VMOp failure due to
2298 // another collection slipping in after our gc_count but before
2299 // our request is processed.
2300 return false;
2301 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2302 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2303
2304 // Schedule a standard evacuation pause. We're setting word_size
2305 // to 0 which means that we are not requesting a post-GC allocation.
2306 VM_G1CollectForAllocation op(0, /* word_size */
2307 gc_count_before,
2308 cause,
2309 policy()->max_pause_time_ms());
2310 VMThread::execute(&op);
2311 return op.gc_succeeded();
2312 } else {
2313 // Schedule a Full GC.
2314 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2315 VMThread::execute(&op);
2316 return op.gc_succeeded();
2317 }
2318 }
2319
2320 bool G1CollectedHeap::is_in(const void* p) const {
2321 if (_hrm->reserved().contains(p)) {
2322 // Given that we know that p is in the reserved space,
2323 // heap_region_containing() should successfully
2324 // return the containing region.
2325 HeapRegion* hr = heap_region_containing(p);
2326 return hr->is_in(p);
2327 } else {
2328 return false;
2329 }
2330 }
2331
2332 #ifdef ASSERT
2333 bool G1CollectedHeap::is_in_exact(const void* p) const {
2334 bool contains = reserved_region().contains(p);
2335 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2336 if (contains && available) {
2337 return true;
2338 } else {
2339 return false;
2340 }
2341 }
2342 #endif
2343
2344 // Iteration functions.
2345
2346 // Iterates an ObjectClosure over all objects within a HeapRegion.
2347
2348 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2349 ObjectClosure* _cl;
2350 public:
2351 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2352 bool do_heap_region(HeapRegion* r) {
2353 if (!r->is_continues_humongous()) {
2354 r->object_iterate(_cl);
2355 }
2356 return false;
2357 }
2358 };
2359
2360 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2361 IterateObjectClosureRegionClosure blk(cl);
2362 heap_region_iterate(&blk);
2363 }
2364
2365 void G1CollectedHeap::keep_alive(oop obj) {
2366 G1BarrierSet::enqueue(obj);
2367 }
2368
2369 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2370 _hrm->iterate(cl);
2371 }
2372
2373 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2374 HeapRegionClaimer *hrclaimer,
2375 uint worker_id) const {
2376 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2377 }
2378
2379 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2380 HeapRegionClaimer *hrclaimer) const {
2381 _hrm->par_iterate(cl, hrclaimer, 0);
2382 }
2383
2384 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2385 _collection_set.iterate(cl);
2386 }
2387
2388 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2389 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2390 }
2391
2392 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2393 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2394 }
2395
2396 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2397 HeapRegion* hr = heap_region_containing(addr);
2398 return hr->block_start(addr);
2399 }
2400
2401 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2402 HeapRegion* hr = heap_region_containing(addr);
2403 return hr->block_is_obj(addr);
2404 }
2405
2406 bool G1CollectedHeap::supports_tlab_allocation() const {
2407 return true;
2408 }
2409
2410 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2411 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2412 }
2413
2414 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2415 return _eden.length() * HeapRegion::GrainBytes;
2416 }
2417
2418 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2419 // must be equal to the humongous object limit.
2420 size_t G1CollectedHeap::max_tlab_size() const {
2421 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2422 }
2423
2424 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2425 return _allocator->unsafe_max_tlab_alloc();
2426 }
2427
2428 size_t G1CollectedHeap::max_capacity() const {
2429 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2430 }
2431
2432 size_t G1CollectedHeap::max_reserved_capacity() const {
2433 return _hrm->max_length() * HeapRegion::GrainBytes;
2434 }
2435
2436 jlong G1CollectedHeap::millis_since_last_gc() {
2437 // See the notes in GenCollectedHeap::millis_since_last_gc()
2438 // for more information about the implementation.
2439 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2440 _policy->collection_pause_end_millis();
2441 if (ret_val < 0) {
2442 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2443 ". returning zero instead.", ret_val);
2444 return 0;
2445 }
2446 return ret_val;
2447 }
2448
2449 void G1CollectedHeap::deduplicate_string(oop str) {
2450 assert(java_lang_String::is_instance(str), "invariant");
2451
2452 if (G1StringDedup::is_enabled()) {
2453 G1StringDedup::deduplicate(str);
2454 }
2455 }
2456
2457 void G1CollectedHeap::prepare_for_verify() {
2458 _verifier->prepare_for_verify();
2459 }
2460
2461 void G1CollectedHeap::verify(VerifyOption vo) {
2462 _verifier->verify(vo);
2463 }
2464
2465 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2466 return true;
2467 }
2468
2469 bool G1CollectedHeap::is_heterogeneous_heap() const {
2470 return G1Arguments::is_heterogeneous_heap();
2471 }
2472
2473 class PrintRegionClosure: public HeapRegionClosure {
2474 outputStream* _st;
2475 public:
2476 PrintRegionClosure(outputStream* st) : _st(st) {}
2477 bool do_heap_region(HeapRegion* r) {
2478 r->print_on(_st);
2479 return false;
2480 }
2481 };
2482
2483 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2484 const HeapRegion* hr,
2485 const VerifyOption vo) const {
2486 switch (vo) {
2487 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2488 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2489 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2490 default: ShouldNotReachHere();
2491 }
2492 return false; // keep some compilers happy
2493 }
2494
2495 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2496 const VerifyOption vo) const {
2497 switch (vo) {
2498 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2499 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2500 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2501 default: ShouldNotReachHere();
2502 }
2503 return false; // keep some compilers happy
2504 }
2505
2506 void G1CollectedHeap::print_heap_regions() const {
2507 LogTarget(Trace, gc, heap, region) lt;
2508 if (lt.is_enabled()) {
2509 LogStream ls(lt);
2510 print_regions_on(&ls);
2511 }
2512 }
2513
2514 void G1CollectedHeap::print_on(outputStream* st) const {
2515 st->print(" %-20s", "garbage-first heap");
2516 if (_hrm != NULL) {
2517 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2518 capacity()/K, used_unlocked()/K);
2519 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2520 p2i(_hrm->reserved().start()),
2521 p2i(_hrm->reserved().end()));
2522 }
2523 st->cr();
2524 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2525 uint young_regions = young_regions_count();
2526 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2527 (size_t) young_regions * HeapRegion::GrainBytes / K);
2528 uint survivor_regions = survivor_regions_count();
2529 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2530 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2531 st->cr();
2532 if (_numa->is_enabled()) {
2533 uint num_nodes = _numa->num_active_nodes();
2534 st->print(" remaining free region(s) on each NUMA node: ");
2535 const int* node_ids = _numa->node_ids();
2536 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2537 uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0);
2538 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2539 }
2540 st->cr();
2541 }
2542 MetaspaceUtils::print_on(st);
2543 }
2544
2545 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2546 if (_hrm == NULL) {
2547 return;
2548 }
2549
2550 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2551 "HS=humongous(starts), HC=humongous(continues), "
2552 "CS=collection set, F=free, "
2553 "OA=open archive, CA=closed archive, "
2554 "TAMS=top-at-mark-start (previous, next)");
2555 PrintRegionClosure blk(st);
2556 heap_region_iterate(&blk);
2557 }
2558
2559 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2560 print_on(st);
2561
2562 // Print the per-region information.
2563 if (_hrm != NULL) {
2564 st->cr();
2565 print_regions_on(st);
2566 }
2567 }
2568
2569 void G1CollectedHeap::print_on_error(outputStream* st) const {
2570 this->CollectedHeap::print_on_error(st);
2571
2572 if (_cm != NULL) {
2573 st->cr();
2574 _cm->print_on_error(st);
2575 }
2576 }
2577
2578 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2579 workers()->threads_do(tc);
2580 tc->do_thread(_cm_thread);
2581 _cm->threads_do(tc);
2582 _cr->threads_do(tc);
2583 tc->do_thread(_young_gen_sampling_thread);
2584 if (G1StringDedup::is_enabled()) {
2585 G1StringDedup::threads_do(tc);
2586 }
2587 }
2588
2589 void G1CollectedHeap::print_tracing_info() const {
2590 rem_set()->print_summary_info();
2591 concurrent_mark()->print_summary_info();
2592 }
2593
2594 #ifndef PRODUCT
2595 // Helpful for debugging RSet issues.
2596
2597 class PrintRSetsClosure : public HeapRegionClosure {
2598 private:
2599 const char* _msg;
2600 size_t _occupied_sum;
2601
2602 public:
2603 bool do_heap_region(HeapRegion* r) {
2604 HeapRegionRemSet* hrrs = r->rem_set();
2605 size_t occupied = hrrs->occupied();
2606 _occupied_sum += occupied;
2607
2608 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2609 if (occupied == 0) {
2610 tty->print_cr(" RSet is empty");
2611 } else {
2612 hrrs->print();
2613 }
2614 tty->print_cr("----------");
2615 return false;
2616 }
2617
2618 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2619 tty->cr();
2620 tty->print_cr("========================================");
2621 tty->print_cr("%s", msg);
2622 tty->cr();
2623 }
2624
2625 ~PrintRSetsClosure() {
2626 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2627 tty->print_cr("========================================");
2628 tty->cr();
2629 }
2630 };
2631
2632 void G1CollectedHeap::print_cset_rsets() {
2633 PrintRSetsClosure cl("Printing CSet RSets");
2634 collection_set_iterate_all(&cl);
2635 }
2636
2637 void G1CollectedHeap::print_all_rsets() {
2638 PrintRSetsClosure cl("Printing All RSets");;
2639 heap_region_iterate(&cl);
2640 }
2641 #endif // PRODUCT
2642
2643 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2644 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2645 }
2646
2647 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2648
2649 size_t eden_used_bytes = _eden.used_bytes();
2650 size_t survivor_used_bytes = _survivor.used_bytes();
2651 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2652
2653 size_t eden_capacity_bytes =
2654 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2655
2656 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2657 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2658 eden_capacity_bytes, survivor_used_bytes, num_regions());
2659 }
2660
2661 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2662 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2663 stats->unused(), stats->used(), stats->region_end_waste(),
2664 stats->regions_filled(), stats->direct_allocated(),
2665 stats->failure_used(), stats->failure_waste());
2666 }
2667
2668 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2669 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2670 gc_tracer->report_gc_heap_summary(when, heap_summary);
2671
2672 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2673 gc_tracer->report_metaspace_summary(when, metaspace_summary);
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(ScannerTask(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 G1ScannerTasksQueueSet* _queues;
3440 WorkGang* _workers;
3441
3442 public:
3443 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3444 G1ParScanThreadStateSet* per_thread_states,
3445 WorkGang* workers,
3446 G1ScannerTasksQueueSet *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 G1ScannerTasksQueueSet* _task_queues;
3467 TaskTerminator* _terminator;
3468
3469 public:
3470 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3471 G1CollectedHeap* g1h,
3472 G1ParScanThreadStateSet* per_thread_states,
3473 G1ScannerTasksQueueSet *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_timed(&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 G1ScannerTasksQueueSet* _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,
3843 G1ParScanThreadStateSet* per_thread_states,
3844 G1ScannerTasksQueueSet* task_queues,
3845 uint num_workers) :
3846 AbstractGangTask(name),
3847 _g1h(G1CollectedHeap::heap()),
3848 _per_thread_states(per_thread_states),
3849 _task_queues(task_queues),
3850 _terminator(num_workers, _task_queues),
3851 _num_workers(num_workers)
3852 { }
3853
3854 void work(uint worker_id) {
3855 start_work(worker_id);
3856
3857 {
3858 ResourceMark rm;
3859 HandleMark hm;
3860
3861 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3862 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3863
3864 scan_roots(pss, worker_id);
3865 evacuate_live_objects(pss, worker_id);
3866 }
3867
3868 end_work(worker_id);
3869 }
3870 };
3871
3872 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3873 G1RootProcessor* _root_processor;
3874
3875 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3876 _root_processor->evacuate_roots(pss, worker_id);
3877 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3878 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3879 }
3880
3881 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3882 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3883 }
3884
3885 void start_work(uint worker_id) {
3886 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3887 }
3888
3889 void end_work(uint worker_id) {
3890 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3891 }
3892
3893 public:
3894 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3895 G1ParScanThreadStateSet* per_thread_states,
3896 G1ScannerTasksQueueSet* task_queues,
3897 G1RootProcessor* root_processor,
3898 uint num_workers) :
3899 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3900 _root_processor(root_processor)
3901 { }
3902 };
3903
3904 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3905 G1GCPhaseTimes* p = phase_times();
3906
3907 {
3908 Ticks start = Ticks::now();
3909 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3910 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3911 }
3912
3913 Tickspan task_time;
3914 const uint num_workers = workers()->active_workers();
3915
3916 Ticks start_processing = Ticks::now();
3917 {
3918 G1RootProcessor root_processor(this, num_workers);
3919 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3920 task_time = run_task_timed(&g1_par_task);
3921 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3922 // To extract its code root fixup time we measure total time of this scope and
3923 // subtract from the time the WorkGang task took.
3924 }
3925 Tickspan total_processing = Ticks::now() - start_processing;
3926
3927 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3928 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3929 }
3930
3931 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3932
3933 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3934 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3935 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3936 }
3937
3938 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3939 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3940 }
3941
3942 public:
3943 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3944 G1ScannerTasksQueueSet* queues,
3945 uint num_workers) :
3946 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3947 }
3948 };
3949
3950 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3951 class G1MarkScope : public MarkScope { };
3952
3953 Tickspan task_time;
3954
3955 Ticks start_processing = Ticks::now();
3956 {
3957 G1MarkScope code_mark_scope;
3958 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3959 task_time = run_task_timed(&task);
3960 // See comment in evacuate_collection_set() for the reason of the scope.
3961 }
3962 Tickspan total_processing = Ticks::now() - start_processing;
3963
3964 G1GCPhaseTimes* p = phase_times();
3965 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3966 }
3967
3968 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3969 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3970
3971 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3972
3973 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3974 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3975
3976 if (time_left_ms < 0 ||
3977 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3978 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3979 _collection_set.optional_region_length(), time_left_ms);
3980 break;
3981 }
3982
3983 {
3984 Ticks start = Ticks::now();
3985 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3986 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3987 }
3988
3989 {
3990 Ticks start = Ticks::now();
3991 evacuate_next_optional_regions(per_thread_states);
3992 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3993 }
3994 }
3995
3996 _collection_set.abandon_optional_collection_set(per_thread_states);
3997 }
3998
3999 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
4000 G1RedirtyCardsQueueSet* rdcqs,
4001 G1ParScanThreadStateSet* per_thread_states) {
4002 G1GCPhaseTimes* p = phase_times();
4003
4004 rem_set()->cleanup_after_scan_heap_roots();
4005
4006 // Process any discovered reference objects - we have
4007 // to do this _before_ we retire the GC alloc regions
4008 // as we may have to copy some 'reachable' referent
4009 // objects (and their reachable sub-graphs) that were
4010 // not copied during the pause.
4011 process_discovered_references(per_thread_states);
4012
4013 G1STWIsAliveClosure is_alive(this);
4014 G1KeepAliveClosure keep_alive(this);
4015
4016 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4017
4018 if (G1StringDedup::is_enabled()) {
4019 double string_dedup_time_ms = os::elapsedTime();
4020
4021 string_dedup_cleaning(&is_alive, &keep_alive, p);
4022
4023 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4024 p->record_string_deduplication_time(string_cleanup_time_ms);
4025 }
4026
4027 _allocator->release_gc_alloc_regions(evacuation_info);
4028
4029 if (evacuation_failed()) {
4030 restore_after_evac_failure(rdcqs);
4031
4032 // Reset the G1EvacuationFailureALot counters and flags
4033 NOT_PRODUCT(reset_evacuation_should_fail();)
4034
4035 double recalculate_used_start = os::elapsedTime();
4036 set_used(recalculate_used());
4037 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4038
4039 if (_archive_allocator != NULL) {
4040 _archive_allocator->clear_used();
4041 }
4042 for (uint i = 0; i < ParallelGCThreads; i++) {
4043 if (_evacuation_failed_info_array[i].has_failed()) {
4044 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4045 }
4046 }
4047 } else {
4048 // The "used" of the the collection set have already been subtracted
4049 // when they were freed. Add in the bytes used.
4050 increase_used(_bytes_used_during_gc);
4051 }
4052
4053 _preserved_marks_set.assert_empty();
4054
4055 merge_per_thread_state_info(per_thread_states);
4056
4057 // Reset and re-enable the hot card cache.
4058 // Note the counts for the cards in the regions in the
4059 // collection set are reset when the collection set is freed.
4060 _hot_card_cache->reset_hot_cache();
4061 _hot_card_cache->set_use_cache(true);
4062
4063 purge_code_root_memory();
4064
4065 redirty_logged_cards(rdcqs);
4066
4067 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4068
4069 eagerly_reclaim_humongous_regions();
4070
4071 record_obj_copy_mem_stats();
4072
4073 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4074 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4075
4076 #if COMPILER2_OR_JVMCI
4077 double start = os::elapsedTime();
4078 DerivedPointerTable::update_pointers();
4079 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4080 #endif
4081 policy()->print_age_table();
4082 }
4083
4084 void G1CollectedHeap::record_obj_copy_mem_stats() {
4085 policy()->old_gen_alloc_tracker()->
4086 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4087
4088 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4089 create_g1_evac_summary(&_old_evac_stats));
4090 }
4091
4092 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4093 assert(!hr->is_free(), "the region should not be free");
4094 assert(!hr->is_empty(), "the region should not be empty");
4095 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4096
4097 if (G1VerifyBitmaps) {
4098 MemRegion mr(hr->bottom(), hr->end());
4099 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4100 }
4101
4102 // Clear the card counts for this region.
4103 // Note: we only need to do this if the region is not young
4104 // (since we don't refine cards in young regions).
4105 if (!hr->is_young()) {
4106 _hot_card_cache->reset_card_counts(hr);
4107 }
4108
4109 // Reset region metadata to allow reuse.
4110 hr->hr_clear(true /* clear_space */);
4111 _policy->remset_tracker()->update_at_free(hr);
4112
4113 if (free_list != NULL) {
4114 free_list->add_ordered(hr);
4115 }
4116 }
4117
4118 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4119 FreeRegionList* free_list) {
4120 assert(hr->is_humongous(), "this is only for humongous regions");
4121 assert(free_list != NULL, "pre-condition");
4122 hr->clear_humongous();
4123 free_region(hr, free_list);
4124 }
4125
4126 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4127 const uint humongous_regions_removed) {
4128 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4129 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4130 _old_set.bulk_remove(old_regions_removed);
4131 _humongous_set.bulk_remove(humongous_regions_removed);
4132 }
4133
4134 }
4135
4136 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4137 assert(list != NULL, "list can't be null");
4138 if (!list->is_empty()) {
4139 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4140 _hrm->insert_list_into_free_list(list);
4141 }
4142 }
4143
4144 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4145 decrease_used(bytes);
4146 }
4147
4148 class G1FreeCollectionSetTask : public AbstractGangTask {
4149 // Helper class to keep statistics for the collection set freeing
4150 class FreeCSetStats {
4151 size_t _before_used_bytes; // Usage in regions successfully evacutate
4152 size_t _after_used_bytes; // Usage in regions failing evacuation
4153 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4154 size_t _failure_used_words; // Live size in failed regions
4155 size_t _failure_waste_words; // Wasted size in failed regions
4156 size_t _rs_length; // Remembered set size
4157 uint _regions_freed; // Number of regions freed
4158 public:
4159 FreeCSetStats() :
4160 _before_used_bytes(0),
4161 _after_used_bytes(0),
4162 _bytes_allocated_in_old_since_last_gc(0),
4163 _failure_used_words(0),
4164 _failure_waste_words(0),
4165 _rs_length(0),
4166 _regions_freed(0) { }
4167
4168 void merge_stats(FreeCSetStats* other) {
4169 assert(other != NULL, "invariant");
4170 _before_used_bytes += other->_before_used_bytes;
4171 _after_used_bytes += other->_after_used_bytes;
4172 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4173 _failure_used_words += other->_failure_used_words;
4174 _failure_waste_words += other->_failure_waste_words;
4175 _rs_length += other->_rs_length;
4176 _regions_freed += other->_regions_freed;
4177 }
4178
4179 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4180 evacuation_info->set_regions_freed(_regions_freed);
4181 evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4182
4183 g1h->decrement_summary_bytes(_before_used_bytes);
4184 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4185
4186 G1Policy *policy = g1h->policy();
4187 policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4188 policy->record_rs_length(_rs_length);
4189 policy->cset_regions_freed();
4190 }
4191
4192 void account_failed_region(HeapRegion* r) {
4193 size_t used_words = r->marked_bytes() / HeapWordSize;
4194 _failure_used_words += used_words;
4195 _failure_waste_words += HeapRegion::GrainWords - used_words;
4196 _after_used_bytes += r->used();
4197
4198 // When moving a young gen region to old gen, we "allocate" that whole
4199 // region there. This is in addition to any already evacuated objects.
4200 // Notify the policy about that. Old gen regions do not cause an
4201 // additional allocation: both the objects still in the region and the
4202 // ones already moved are accounted for elsewhere.
4203 if (r->is_young()) {
4204 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4205 }
4206 }
4207
4208 void account_evacuated_region(HeapRegion* r) {
4209 _before_used_bytes += r->used();
4210 _regions_freed += 1;
4211 }
4212
4213 void account_rs_length(HeapRegion* r) {
4214 _rs_length += r->rem_set()->occupied();
4215 }
4216 };
4217
4218 // Closure applied to all regions in the collection set.
4219 class FreeCSetClosure : public HeapRegionClosure {
4220 // Helper to send JFR events for regions.
4221 class JFREventForRegion {
4222 EventGCPhaseParallel _event;
4223 public:
4224 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4225 _event.set_gcId(GCId::current());
4226 _event.set_gcWorkerId(worker_id);
4227 if (region->is_young()) {
4228 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4229 } else {
4230 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4231 }
4232 }
4233
4234 ~JFREventForRegion() {
4235 _event.commit();
4236 }
4237 };
4238
4239 // Helper to do timing for region work.
4240 class TimerForRegion {
4241 Tickspan& _time;
4242 Ticks _start_time;
4243 public:
4244 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4245 ~TimerForRegion() {
4246 _time += Ticks::now() - _start_time;
4247 }
4248 };
4249
4250 // FreeCSetClosure members
4251 G1CollectedHeap* _g1h;
4252 const size_t* _surviving_young_words;
4253 uint _worker_id;
4254 Tickspan _young_time;
4255 Tickspan _non_young_time;
4256 FreeCSetStats* _stats;
4257
4258 void assert_in_cset(HeapRegion* r) {
4259 assert(r->young_index_in_cset() != 0 &&
4260 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4261 "Young index %u is wrong for region %u of type %s with %u young regions",
4262 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4263 }
4264
4265 void handle_evacuated_region(HeapRegion* r) {
4266 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4267 stats()->account_evacuated_region(r);
4268
4269 // Free the region and and its remembered set.
4270 _g1h->free_region(r, NULL);
4271 }
4272
4273 void handle_failed_region(HeapRegion* r) {
4274 // Do some allocation statistics accounting. Regions that failed evacuation
4275 // are always made old, so there is no need to update anything in the young
4276 // gen statistics, but we need to update old gen statistics.
4277 stats()->account_failed_region(r);
4278
4279 // Update the region state due to the failed evacuation.
4280 r->handle_evacuation_failure();
4281
4282 // Add region to old set, need to hold lock.
4283 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4284 _g1h->old_set_add(r);
4285 }
4286
4287 Tickspan& timer_for_region(HeapRegion* r) {
4288 return r->is_young() ? _young_time : _non_young_time;
4289 }
4290
4291 FreeCSetStats* stats() {
4292 return _stats;
4293 }
4294 public:
4295 FreeCSetClosure(const size_t* surviving_young_words,
4296 uint worker_id,
4297 FreeCSetStats* stats) :
4298 HeapRegionClosure(),
4299 _g1h(G1CollectedHeap::heap()),
4300 _surviving_young_words(surviving_young_words),
4301 _worker_id(worker_id),
4302 _young_time(),
4303 _non_young_time(),
4304 _stats(stats) { }
4305
4306 virtual bool do_heap_region(HeapRegion* r) {
4307 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4308 JFREventForRegion event(r, _worker_id);
4309 TimerForRegion timer(timer_for_region(r));
4310
4311 _g1h->clear_region_attr(r);
4312 stats()->account_rs_length(r);
4313
4314 if (r->is_young()) {
4315 assert_in_cset(r);
4316 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4317 }
4318
4319 if (r->evacuation_failed()) {
4320 handle_failed_region(r);
4321 } else {
4322 handle_evacuated_region(r);
4323 }
4324 assert(!_g1h->is_on_master_free_list(r), "sanity");
4325
4326 return false;
4327 }
4328
4329 void report_timing(Tickspan parallel_time) {
4330 G1GCPhaseTimes* pt = _g1h->phase_times();
4331 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4332 if (_young_time.value() > 0) {
4333 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4334 }
4335 if (_non_young_time.value() > 0) {
4336 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4337 }
4338 }
4339 };
4340
4341 // G1FreeCollectionSetTask members
4342 G1CollectedHeap* _g1h;
4343 G1EvacuationInfo* _evacuation_info;
4344 FreeCSetStats* _worker_stats;
4345 HeapRegionClaimer _claimer;
4346 const size_t* _surviving_young_words;
4347 uint _active_workers;
4348
4349 FreeCSetStats* worker_stats(uint worker) {
4350 return &_worker_stats[worker];
4351 }
4352
4353 void report_statistics() {
4354 // Merge the accounting
4355 FreeCSetStats total_stats;
4356 for (uint worker = 0; worker < _active_workers; worker++) {
4357 total_stats.merge_stats(worker_stats(worker));
4358 }
4359 total_stats.report(_g1h, _evacuation_info);
4360 }
4361
4362 public:
4363 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4364 AbstractGangTask("G1 Free Collection Set"),
4365 _g1h(G1CollectedHeap::heap()),
4366 _evacuation_info(evacuation_info),
4367 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4368 _claimer(active_workers),
4369 _surviving_young_words(surviving_young_words),
4370 _active_workers(active_workers) {
4371 for (uint worker = 0; worker < active_workers; worker++) {
4372 ::new (&_worker_stats[worker]) FreeCSetStats();
4373 }
4374 }
4375
4376 ~G1FreeCollectionSetTask() {
4377 Ticks serial_time = Ticks::now();
4378 report_statistics();
4379 for (uint worker = 0; worker < _active_workers; worker++) {
4380 _worker_stats[worker].~FreeCSetStats();
4381 }
4382 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4383 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4384 }
4385
4386 virtual void work(uint worker_id) {
4387 EventGCPhaseParallel event;
4388 Ticks start = Ticks::now();
4389 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4390 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4391
4392 // Report the total parallel time along with some more detailed metrics.
4393 cl.report_timing(Ticks::now() - start);
4394 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4395 }
4396 };
4397
4398 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4399 _eden.clear();
4400
4401 // The free collections set is split up in two tasks, the first
4402 // frees the collection set and records what regions are free,
4403 // and the second one rebuilds the free list. This proved to be
4404 // more efficient than adding a sorted list to another.
4405
4406 Ticks free_cset_start_time = Ticks::now();
4407 {
4408 uint const num_cs_regions = _collection_set.region_length();
4409 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4410 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4411
4412 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4413 cl.name(), num_workers, num_cs_regions, num_regions());
4414 workers()->run_task(&cl, num_workers);
4415 }
4416
4417 Ticks free_cset_end_time = Ticks::now();
4418 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4419
4420 // Now rebuild the free region list.
4421 hrm()->rebuild_free_list(workers());
4422 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4423
4424 collection_set->clear();
4425 }
4426
4427 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4428 private:
4429 FreeRegionList* _free_region_list;
4430 HeapRegionSet* _proxy_set;
4431 uint _humongous_objects_reclaimed;
4432 uint _humongous_regions_reclaimed;
4433 size_t _freed_bytes;
4434 public:
4435
4436 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4437 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4438 }
4439
4440 virtual bool do_heap_region(HeapRegion* r) {
4441 if (!r->is_starts_humongous()) {
4442 return false;
4443 }
4444
4445 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4446
4447 oop obj = (oop)r->bottom();
4448 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4449
4450 // The following checks whether the humongous object is live are sufficient.
4451 // The main additional check (in addition to having a reference from the roots
4452 // or the young gen) is whether the humongous object has a remembered set entry.
4453 //
4454 // A humongous object cannot be live if there is no remembered set for it
4455 // because:
4456 // - there can be no references from within humongous starts regions referencing
4457 // the object because we never allocate other objects into them.
4458 // (I.e. there are no intra-region references that may be missed by the
4459 // remembered set)
4460 // - as soon there is a remembered set entry to the humongous starts region
4461 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4462 // until the end of a concurrent mark.
4463 //
4464 // It is not required to check whether the object has been found dead by marking
4465 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4466 // all objects allocated during that time are considered live.
4467 // SATB marking is even more conservative than the remembered set.
4468 // So if at this point in the collection there is no remembered set entry,
4469 // nobody has a reference to it.
4470 // At the start of collection we flush all refinement logs, and remembered sets
4471 // are completely up-to-date wrt to references to the humongous object.
4472 //
4473 // Other implementation considerations:
4474 // - never consider object arrays at this time because they would pose
4475 // considerable effort for cleaning up the the remembered sets. This is
4476 // required because stale remembered sets might reference locations that
4477 // are currently allocated into.
4478 uint region_idx = r->hrm_index();
4479 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4480 !r->rem_set()->is_empty()) {
4481 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",
4482 region_idx,
4483 (size_t)obj->size() * HeapWordSize,
4484 p2i(r->bottom()),
4485 r->rem_set()->occupied(),
4486 r->rem_set()->strong_code_roots_list_length(),
4487 next_bitmap->is_marked(r->bottom()),
4488 g1h->is_humongous_reclaim_candidate(region_idx),
4489 obj->is_typeArray()
4490 );
4491 return false;
4492 }
4493
4494 guarantee(obj->is_typeArray(),
4495 "Only eagerly reclaiming type arrays is supported, but the object "
4496 PTR_FORMAT " is not.", p2i(r->bottom()));
4497
4498 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",
4499 region_idx,
4500 (size_t)obj->size() * HeapWordSize,
4501 p2i(r->bottom()),
4502 r->rem_set()->occupied(),
4503 r->rem_set()->strong_code_roots_list_length(),
4504 next_bitmap->is_marked(r->bottom()),
4505 g1h->is_humongous_reclaim_candidate(region_idx),
4506 obj->is_typeArray()
4507 );
4508
4509 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4510 cm->humongous_object_eagerly_reclaimed(r);
4511 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4512 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4513 region_idx,
4514 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4515 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4516 _humongous_objects_reclaimed++;
4517 do {
4518 HeapRegion* next = g1h->next_region_in_humongous(r);
4519 _freed_bytes += r->used();
4520 r->set_containing_set(NULL);
4521 _humongous_regions_reclaimed++;
4522 g1h->free_humongous_region(r, _free_region_list);
4523 r = next;
4524 } while (r != NULL);
4525
4526 return false;
4527 }
4528
4529 uint humongous_objects_reclaimed() {
4530 return _humongous_objects_reclaimed;
4531 }
4532
4533 uint humongous_regions_reclaimed() {
4534 return _humongous_regions_reclaimed;
4535 }
4536
4537 size_t bytes_freed() const {
4538 return _freed_bytes;
4539 }
4540 };
4541
4542 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4543 assert_at_safepoint_on_vm_thread();
4544
4545 if (!G1EagerReclaimHumongousObjects ||
4546 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4547 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4548 return;
4549 }
4550
4551 double start_time = os::elapsedTime();
4552
4553 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4554
4555 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4556 heap_region_iterate(&cl);
4557
4558 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4559
4560 G1HRPrinter* hrp = hr_printer();
4561 if (hrp->is_active()) {
4562 FreeRegionListIterator iter(&local_cleanup_list);
4563 while (iter.more_available()) {
4564 HeapRegion* hr = iter.get_next();
4565 hrp->cleanup(hr);
4566 }
4567 }
4568
4569 prepend_to_freelist(&local_cleanup_list);
4570 decrement_summary_bytes(cl.bytes_freed());
4571
4572 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4573 cl.humongous_objects_reclaimed());
4574 }
4575
4576 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4577 public:
4578 virtual bool do_heap_region(HeapRegion* r) {
4579 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4580 G1CollectedHeap::heap()->clear_region_attr(r);
4581 r->clear_young_index_in_cset();
4582 return false;
4583 }
4584 };
4585
4586 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4587 G1AbandonCollectionSetClosure cl;
4588 collection_set_iterate_all(&cl);
4589
4590 collection_set->clear();
4591 collection_set->stop_incremental_building();
4592 }
4593
4594 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4595 return _allocator->is_retained_old_region(hr);
4596 }
4597
4598 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4599 _eden.add(hr);
4600 _policy->set_region_eden(hr);
4601 }
4602
4603 #ifdef ASSERT
4604
4605 class NoYoungRegionsClosure: public HeapRegionClosure {
4606 private:
4607 bool _success;
4608 public:
4609 NoYoungRegionsClosure() : _success(true) { }
4610 bool do_heap_region(HeapRegion* r) {
4611 if (r->is_young()) {
4612 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4613 p2i(r->bottom()), p2i(r->end()));
4614 _success = false;
4615 }
4616 return false;
4617 }
4618 bool success() { return _success; }
4619 };
4620
4621 bool G1CollectedHeap::check_young_list_empty() {
4622 bool ret = (young_regions_count() == 0);
4623
4624 NoYoungRegionsClosure closure;
4625 heap_region_iterate(&closure);
4626 ret = ret && closure.success();
4627
4628 return ret;
4629 }
4630
4631 #endif // ASSERT
4632
4633 class TearDownRegionSetsClosure : public HeapRegionClosure {
4634 HeapRegionSet *_old_set;
4635
4636 public:
4637 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4638
4639 bool do_heap_region(HeapRegion* r) {
4640 if (r->is_old()) {
4641 _old_set->remove(r);
4642 } else if(r->is_young()) {
4643 r->uninstall_surv_rate_group();
4644 } else {
4645 // We ignore free regions, we'll empty the free list afterwards.
4646 // We ignore humongous and archive regions, we're not tearing down these
4647 // sets.
4648 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4649 "it cannot be another type");
4650 }
4651 return false;
4652 }
4653
4654 ~TearDownRegionSetsClosure() {
4655 assert(_old_set->is_empty(), "post-condition");
4656 }
4657 };
4658
4659 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4660 assert_at_safepoint_on_vm_thread();
4661
4662 if (!free_list_only) {
4663 TearDownRegionSetsClosure cl(&_old_set);
4664 heap_region_iterate(&cl);
4665
4666 // Note that emptying the _young_list is postponed and instead done as
4667 // the first step when rebuilding the regions sets again. The reason for
4668 // this is that during a full GC string deduplication needs to know if
4669 // a collected region was young or old when the full GC was initiated.
4670 }
4671 _hrm->remove_all_free_regions();
4672 }
4673
4674 void G1CollectedHeap::increase_used(size_t bytes) {
4675 _summary_bytes_used += bytes;
4676 }
4677
4678 void G1CollectedHeap::decrease_used(size_t bytes) {
4679 assert(_summary_bytes_used >= bytes,
4680 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4681 _summary_bytes_used, bytes);
4682 _summary_bytes_used -= bytes;
4683 }
4684
4685 void G1CollectedHeap::set_used(size_t bytes) {
4686 _summary_bytes_used = bytes;
4687 }
4688
4689 class RebuildRegionSetsClosure : public HeapRegionClosure {
4690 private:
4691 bool _free_list_only;
4692
4693 HeapRegionSet* _old_set;
4694 HeapRegionManager* _hrm;
4695
4696 size_t _total_used;
4697
4698 public:
4699 RebuildRegionSetsClosure(bool free_list_only,
4700 HeapRegionSet* old_set,
4701 HeapRegionManager* hrm) :
4702 _free_list_only(free_list_only),
4703 _old_set(old_set), _hrm(hrm), _total_used(0) {
4704 assert(_hrm->num_free_regions() == 0, "pre-condition");
4705 if (!free_list_only) {
4706 assert(_old_set->is_empty(), "pre-condition");
4707 }
4708 }
4709
4710 bool do_heap_region(HeapRegion* r) {
4711 if (r->is_empty()) {
4712 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4713 // Add free regions to the free list
4714 r->set_free();
4715 _hrm->insert_into_free_list(r);
4716 } else if (!_free_list_only) {
4717 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4718
4719 if (r->is_archive() || r->is_humongous()) {
4720 // We ignore archive and humongous regions. We left these sets unchanged.
4721 } else {
4722 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4723 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4724 r->move_to_old();
4725 _old_set->add(r);
4726 }
4727 _total_used += r->used();
4728 }
4729
4730 return false;
4731 }
4732
4733 size_t total_used() {
4734 return _total_used;
4735 }
4736 };
4737
4738 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4739 assert_at_safepoint_on_vm_thread();
4740
4741 if (!free_list_only) {
4742 _eden.clear();
4743 _survivor.clear();
4744 }
4745
4746 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4747 heap_region_iterate(&cl);
4748
4749 if (!free_list_only) {
4750 set_used(cl.total_used());
4751 if (_archive_allocator != NULL) {
4752 _archive_allocator->clear_used();
4753 }
4754 }
4755 assert_used_and_recalculate_used_equal(this);
4756 }
4757
4758 // Methods for the mutator alloc region
4759
4760 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4761 bool force,
4762 uint node_index) {
4763 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4764 bool should_allocate = policy()->should_allocate_mutator_region();
4765 if (force || should_allocate) {
4766 HeapRegion* new_alloc_region = new_region(word_size,
4767 HeapRegionType::Eden,
4768 false /* do_expand */,
4769 node_index);
4770 if (new_alloc_region != NULL) {
4771 set_region_short_lived_locked(new_alloc_region);
4772 _hr_printer.alloc(new_alloc_region, !should_allocate);
4773 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4774 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4775 return new_alloc_region;
4776 }
4777 }
4778 return NULL;
4779 }
4780
4781 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4782 size_t allocated_bytes) {
4783 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4784 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4785
4786 collection_set()->add_eden_region(alloc_region);
4787 increase_used(allocated_bytes);
4788 _eden.add_used_bytes(allocated_bytes);
4789 _hr_printer.retire(alloc_region);
4790
4791 // We update the eden sizes here, when the region is retired,
4792 // instead of when it's allocated, since this is the point that its
4793 // used space has been recorded in _summary_bytes_used.
4794 g1mm()->update_eden_size();
4795 }
4796
4797 // Methods for the GC alloc regions
4798
4799 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4800 if (dest.is_old()) {
4801 return true;
4802 } else {
4803 return survivor_regions_count() < policy()->max_survivor_regions();
4804 }
4805 }
4806
4807 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4808 assert(FreeList_lock->owned_by_self(), "pre-condition");
4809
4810 if (!has_more_regions(dest)) {
4811 return NULL;
4812 }
4813
4814 HeapRegionType type;
4815 if (dest.is_young()) {
4816 type = HeapRegionType::Survivor;
4817 } else {
4818 type = HeapRegionType::Old;
4819 }
4820
4821 HeapRegion* new_alloc_region = new_region(word_size,
4822 type,
4823 true /* do_expand */,
4824 node_index);
4825
4826 if (new_alloc_region != NULL) {
4827 if (type.is_survivor()) {
4828 new_alloc_region->set_survivor();
4829 _survivor.add(new_alloc_region);
4830 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4831 } else {
4832 new_alloc_region->set_old();
4833 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4834 }
4835 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4836 register_region_with_region_attr(new_alloc_region);
4837 _hr_printer.alloc(new_alloc_region);
4838 return new_alloc_region;
4839 }
4840 return NULL;
4841 }
4842
4843 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4844 size_t allocated_bytes,
4845 G1HeapRegionAttr dest) {
4846 _bytes_used_during_gc += allocated_bytes;
4847 if (dest.is_old()) {
4848 old_set_add(alloc_region);
4849 } else {
4850 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4851 _survivor.add_used_bytes(allocated_bytes);
4852 }
4853
4854 bool const during_im = collector_state()->in_initial_mark_gc();
4855 if (during_im && allocated_bytes > 0) {
4856 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4857 }
4858 _hr_printer.retire(alloc_region);
4859 }
4860
4861 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4862 bool expanded = false;
4863 uint index = _hrm->find_highest_free(&expanded);
4864
4865 if (index != G1_NO_HRM_INDEX) {
4866 if (expanded) {
4867 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4868 HeapRegion::GrainWords * HeapWordSize);
4869 }
4870 return _hrm->allocate_free_regions_starting_at(index, 1);
4871 }
4872 return NULL;
4873 }
4874
4875 // Optimized nmethod scanning
4876
4877 class RegisterNMethodOopClosure: public OopClosure {
4878 G1CollectedHeap* _g1h;
4879 nmethod* _nm;
4880
4881 template <class T> void do_oop_work(T* p) {
4882 T heap_oop = RawAccess<>::oop_load(p);
4883 if (!CompressedOops::is_null(heap_oop)) {
4884 oop obj = CompressedOops::decode_not_null(heap_oop);
4885 HeapRegion* hr = _g1h->heap_region_containing(obj);
4886 assert(!hr->is_continues_humongous(),
4887 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4888 " starting at " HR_FORMAT,
4889 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4890
4891 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4892 hr->add_strong_code_root_locked(_nm);
4893 }
4894 }
4895
4896 public:
4897 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4898 _g1h(g1h), _nm(nm) {}
4899
4900 void do_oop(oop* p) { do_oop_work(p); }
4901 void do_oop(narrowOop* p) { do_oop_work(p); }
4902 };
4903
4904 class UnregisterNMethodOopClosure: public OopClosure {
4905 G1CollectedHeap* _g1h;
4906 nmethod* _nm;
4907
4908 template <class T> void do_oop_work(T* p) {
4909 T heap_oop = RawAccess<>::oop_load(p);
4910 if (!CompressedOops::is_null(heap_oop)) {
4911 oop obj = CompressedOops::decode_not_null(heap_oop);
4912 HeapRegion* hr = _g1h->heap_region_containing(obj);
4913 assert(!hr->is_continues_humongous(),
4914 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4915 " starting at " HR_FORMAT,
4916 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4917
4918 hr->remove_strong_code_root(_nm);
4919 }
4920 }
4921
4922 public:
4923 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4924 _g1h(g1h), _nm(nm) {}
4925
4926 void do_oop(oop* p) { do_oop_work(p); }
4927 void do_oop(narrowOop* p) { do_oop_work(p); }
4928 };
4929
4930 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4931 guarantee(nm != NULL, "sanity");
4932 RegisterNMethodOopClosure reg_cl(this, nm);
4933 nm->oops_do(®_cl);
4934 }
4935
4936 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4937 guarantee(nm != NULL, "sanity");
4938 UnregisterNMethodOopClosure reg_cl(this, nm);
4939 nm->oops_do(®_cl, true);
4940 }
4941
4942 void G1CollectedHeap::purge_code_root_memory() {
4943 double purge_start = os::elapsedTime();
4944 G1CodeRootSet::purge();
4945 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4946 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4947 }
4948
4949 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4950 G1CollectedHeap* _g1h;
4951
4952 public:
4953 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4954 _g1h(g1h) {}
4955
4956 void do_code_blob(CodeBlob* cb) {
4957 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4958 if (nm == NULL) {
4959 return;
4960 }
4961
4962 _g1h->register_nmethod(nm);
4963 }
4964 };
4965
4966 void G1CollectedHeap::rebuild_strong_code_roots() {
4967 RebuildStrongCodeRootClosure blob_cl(this);
4968 CodeCache::blobs_do(&blob_cl);
4969 }
4970
4971 void G1CollectedHeap::initialize_serviceability() {
4972 _g1mm->initialize_serviceability();
4973 }
4974
4975 MemoryUsage G1CollectedHeap::memory_usage() {
4976 return _g1mm->memory_usage();
4977 }
4978
4979 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4980 return _g1mm->memory_managers();
4981 }
4982
4983 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4984 return _g1mm->memory_pools();
4985 }
4986
4987 class G1ParallelObjectIterator : public ParallelObjectIterator {
4988 private:
4989 G1CollectedHeap* _heap;
4990 HeapRegionClaimer _claimer;
4991
4992 public:
4993 G1ParallelObjectIterator(uint thread_num) :
4994 _heap(G1CollectedHeap::heap()),
4995 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
4996
4997 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
4998 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
4999 }
5000 };
5001
5002 ParallelObjectIterator* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
5003 return new G1ParallelObjectIterator(thread_num);
5004 }
5005
5006 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
5007 IterateObjectClosureRegionClosure blk(cl);
5008 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
5009 }