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/resourceArea.hpp"
93 #include "memory/universe.hpp"
94 #include "oops/access.inline.hpp"
95 #include "oops/compressedOops.inline.hpp"
96 #include "oops/oop.inline.hpp"
97 #include "runtime/atomic.hpp"
98 #include "runtime/handles.inline.hpp"
99 #include "runtime/init.hpp"
100 #include "runtime/orderAccess.hpp"
101 #include "runtime/threadSMR.hpp"
102 #include "runtime/vmThread.hpp"
103 #include "utilities/align.hpp"
104 #include "utilities/autoRestore.hpp"
105 #include "utilities/bitMap.inline.hpp"
106 #include "utilities/globalDefinitions.hpp"
107 #include "utilities/stack.inline.hpp"
108
109 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
110
111 // INVARIANTS/NOTES
112 //
113 // All allocation activity covered by the G1CollectedHeap interface is
114 // serialized by acquiring the HeapLock. This happens in mem_allocate
115 // and allocate_new_tlab, which are the "entry" points to the
116 // allocation code from the rest of the JVM. (Note that this does not
117 // apply to TLAB allocation, which is not part of this interface: it
118 // is done by clients of this interface.)
119
120 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
121 private:
122 size_t _num_dirtied;
123 G1CollectedHeap* _g1h;
124 G1CardTable* _g1_ct;
125
126 HeapRegion* region_for_card(CardValue* card_ptr) const {
127 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
128 }
129
130 bool will_become_free(HeapRegion* hr) const {
131 // A region will be freed by free_collection_set if the region is in the
132 // collection set and has not had an evacuation failure.
133 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
134 }
135
136 public:
137 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
138 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
139
140 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
141 HeapRegion* hr = region_for_card(card_ptr);
142
143 // Should only dirty cards in regions that won't be freed.
144 if (!will_become_free(hr)) {
145 *card_ptr = G1CardTable::dirty_card_val();
146 _num_dirtied++;
147 }
148 }
149
150 size_t num_dirtied() const { return _num_dirtied; }
151 };
152
153
154 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
155 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
156 }
157
158 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
159 // The from card cache is not the memory that is actually committed. So we cannot
160 // take advantage of the zero_filled parameter.
161 reset_from_card_cache(start_idx, num_regions);
162 }
163
164 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
165 Ticks start = Ticks::now();
166 workers()->run_task(task, workers()->active_workers());
167 return Ticks::now() - start;
168 }
169
170 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
171 MemRegion mr) {
172 return new HeapRegion(hrs_index, bot(), mr);
173 }
174
175 // Private methods.
176
177 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
178 HeapRegionType type,
179 bool do_expand,
180 uint node_index) {
181 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
182 "the only time we use this to allocate a humongous region is "
183 "when we are allocating a single humongous region");
184
185 HeapRegion* res = _hrm->allocate_free_region(type, node_index);
186
187 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
188 // Currently, only attempts to allocate GC alloc regions set
189 // do_expand to true. So, we should only reach here during a
190 // safepoint. If this assumption changes we might have to
191 // reconsider the use of _expand_heap_after_alloc_failure.
192 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
193
194 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
195 word_size * HeapWordSize);
196
197 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
198 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
199 word_size * HeapWordSize);
200 if (expand_single_region(node_index)) {
201 // Given that expand_single_region() succeeded in expanding the heap, and we
202 // always expand the heap by an amount aligned to the heap
203 // region size, the free list should in theory not be empty.
204 // In either case allocate_free_region() will check for NULL.
205 res = _hrm->allocate_free_region(type, node_index);
206 } else {
207 _expand_heap_after_alloc_failure = false;
208 }
209 }
210 return res;
211 }
212
213 HeapWord*
214 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
215 uint num_regions,
216 size_t word_size) {
217 assert(first_hr != NULL, "pre-condition");
218 assert(is_humongous(word_size), "word_size should be humongous");
219 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
220
221 // Index of last region in the series.
222 uint first = first_hr->hrm_index();
223 uint last = first + num_regions - 1;
224
225 // We need to initialize the region(s) we just discovered. This is
226 // a bit tricky given that it can happen concurrently with
227 // refinement threads refining cards on these regions and
228 // potentially wanting to refine the BOT as they are scanning
229 // those cards (this can happen shortly after a cleanup; see CR
230 // 6991377). So we have to set up the region(s) carefully and in
231 // a specific order.
232
233 // The word size sum of all the regions we will allocate.
234 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
235 assert(word_size <= word_size_sum, "sanity");
236
237 // The passed in hr will be the "starts humongous" region. The header
238 // of the new object will be placed at the bottom of this region.
239 HeapWord* new_obj = first_hr->bottom();
240 // This will be the new top of the new object.
241 HeapWord* obj_top = new_obj + word_size;
242
243 // First, we need to zero the header of the space that we will be
244 // allocating. When we update top further down, some refinement
245 // threads might try to scan the region. By zeroing the header we
246 // ensure that any thread that will try to scan the region will
247 // come across the zero klass word and bail out.
248 //
249 // NOTE: It would not have been correct to have used
250 // CollectedHeap::fill_with_object() and make the space look like
251 // an int array. The thread that is doing the allocation will
252 // later update the object header to a potentially different array
253 // type and, for a very short period of time, the klass and length
254 // fields will be inconsistent. This could cause a refinement
255 // thread to calculate the object size incorrectly.
256 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
257
258 // Next, pad out the unused tail of the last region with filler
259 // objects, for improved usage accounting.
260 // How many words we use for filler objects.
261 size_t word_fill_size = word_size_sum - word_size;
262
263 // How many words memory we "waste" which cannot hold a filler object.
264 size_t words_not_fillable = 0;
265
266 if (word_fill_size >= min_fill_size()) {
267 fill_with_objects(obj_top, word_fill_size);
268 } else if (word_fill_size > 0) {
269 // We have space to fill, but we cannot fit an object there.
270 words_not_fillable = word_fill_size;
271 word_fill_size = 0;
272 }
273
274 // We will set up the first region as "starts humongous". This
275 // will also update the BOT covering all the regions to reflect
276 // that there is a single object that starts at the bottom of the
277 // first region.
278 first_hr->set_starts_humongous(obj_top, word_fill_size);
279 _policy->remset_tracker()->update_at_allocate(first_hr);
280 // Then, if there are any, we will set up the "continues
281 // humongous" regions.
282 HeapRegion* hr = NULL;
283 for (uint i = first + 1; i <= last; ++i) {
284 hr = region_at(i);
285 hr->set_continues_humongous(first_hr);
286 _policy->remset_tracker()->update_at_allocate(hr);
287 }
288
289 // Up to this point no concurrent thread would have been able to
290 // do any scanning on any region in this series. All the top
291 // fields still point to bottom, so the intersection between
292 // [bottom,top] and [card_start,card_end] will be empty. Before we
293 // update the top fields, we'll do a storestore to make sure that
294 // no thread sees the update to top before the zeroing of the
295 // object header and the BOT initialization.
296 OrderAccess::storestore();
297
298 // Now, we will update the top fields of the "continues humongous"
299 // regions except the last one.
300 for (uint i = first; i < last; ++i) {
301 hr = region_at(i);
302 hr->set_top(hr->end());
303 }
304
305 hr = region_at(last);
306 // If we cannot fit a filler object, we must set top to the end
307 // of the humongous object, otherwise we cannot iterate the heap
308 // and the BOT will not be complete.
309 hr->set_top(hr->end() - words_not_fillable);
310
311 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
312 "obj_top should be in last region");
313
314 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
315
316 assert(words_not_fillable == 0 ||
317 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
318 "Miscalculation in humongous allocation");
319
320 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
321
322 for (uint i = first; i <= last; ++i) {
323 hr = region_at(i);
324 _humongous_set.add(hr);
325 _hr_printer.alloc(hr);
326 }
327
328 return new_obj;
329 }
330
331 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
332 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
333 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
334 }
335
336 // If could fit into free regions w/o expansion, try.
337 // Otherwise, if can expand, do so.
338 // Otherwise, if using ex regions might help, try with ex given back.
339 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
340 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
341
342 _verifier->verify_region_sets_optional();
343
344 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
345
346 // Policy: First try to allocate a humongous object in the free list.
347 HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions);
348 if (humongous_start == NULL) {
349 // Policy: We could not find enough regions for the humongous object in the
350 // free list. Look through the heap to find a mix of free and uncommitted regions.
351 // If so, expand the heap and allocate the humongous object.
352 humongous_start = _hrm->expand_and_allocate_humongous(obj_regions);
353 if (humongous_start != NULL) {
354 // We managed to find a region by expanding the heap.
355 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
356 word_size * HeapWordSize);
357 policy()->record_new_heap_size(num_regions());
358 } else {
359 // Policy: Potentially trigger a defragmentation GC.
360 }
361 }
362
363 HeapWord* result = NULL;
364 if (humongous_start != NULL) {
365 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
366 assert(result != NULL, "it should always return a valid result");
367
368 // A successful humongous object allocation changes the used space
369 // information of the old generation so we need to recalculate the
370 // sizes and update the jstat counters here.
371 g1mm()->update_sizes();
372 }
373
374 _verifier->verify_region_sets_optional();
375
376 return result;
377 }
378
379 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
380 size_t requested_size,
381 size_t* actual_size) {
382 assert_heap_not_locked_and_not_at_safepoint();
383 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
384
385 return attempt_allocation(min_size, requested_size, actual_size);
386 }
387
388 HeapWord*
389 G1CollectedHeap::mem_allocate(size_t word_size,
390 bool* gc_overhead_limit_was_exceeded) {
391 assert_heap_not_locked_and_not_at_safepoint();
392
393 if (is_humongous(word_size)) {
394 return attempt_allocation_humongous(word_size);
395 }
396 size_t dummy = 0;
397 return attempt_allocation(word_size, word_size, &dummy);
398 }
399
400 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
401 ResourceMark rm; // For retrieving the thread names in log messages.
402
403 // Make sure you read the note in attempt_allocation_humongous().
404
405 assert_heap_not_locked_and_not_at_safepoint();
406 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
407 "be called for humongous allocation requests");
408
409 // We should only get here after the first-level allocation attempt
410 // (attempt_allocation()) failed to allocate.
411
412 // We will loop until a) we manage to successfully perform the
413 // allocation or b) we successfully schedule a collection which
414 // fails to perform the allocation. b) is the only case when we'll
415 // return NULL.
416 HeapWord* result = NULL;
417 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
418 bool should_try_gc;
419 uint gc_count_before;
420
421 {
422 MutexLocker x(Heap_lock);
423 result = _allocator->attempt_allocation_locked(word_size);
424 if (result != NULL) {
425 return result;
426 }
427
428 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
429 // This is different to when only GCLocker::needs_gc() is set: try to avoid
430 // waiting because the GCLocker is active to not wait too long.
431 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
432 // No need for an ergo message here, can_expand_young_list() does this when
433 // it returns true.
434 result = _allocator->attempt_allocation_force(word_size);
435 if (result != NULL) {
436 return result;
437 }
438 }
439 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
440 // the GCLocker initiated GC has been performed and then retry. This includes
441 // the case when the GC Locker is not active but has not been performed.
442 should_try_gc = !GCLocker::needs_gc();
443 // Read the GC count while still holding the Heap_lock.
444 gc_count_before = total_collections();
445 }
446
447 if (should_try_gc) {
448 bool succeeded;
449 result = do_collection_pause(word_size, gc_count_before, &succeeded,
450 GCCause::_g1_inc_collection_pause);
451 if (result != NULL) {
452 assert(succeeded, "only way to get back a non-NULL result");
453 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
454 Thread::current()->name(), p2i(result));
455 return result;
456 }
457
458 if (succeeded) {
459 // We successfully scheduled a collection which failed to allocate. No
460 // point in trying to allocate further. We'll just return NULL.
461 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
462 SIZE_FORMAT " words", Thread::current()->name(), word_size);
463 return NULL;
464 }
465 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
466 Thread::current()->name(), word_size);
467 } else {
468 // Failed to schedule a collection.
469 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
470 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
471 SIZE_FORMAT " words", Thread::current()->name(), word_size);
472 return NULL;
473 }
474 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
475 // The GCLocker is either active or the GCLocker initiated
476 // GC has not yet been performed. Stall until it is and
477 // then retry the allocation.
478 GCLocker::stall_until_clear();
479 gclocker_retry_count += 1;
480 }
481
482 // We can reach here if we were unsuccessful in scheduling a
483 // collection (because another thread beat us to it) or if we were
484 // stalled due to the GC locker. In either can we should retry the
485 // allocation attempt in case another thread successfully
486 // performed a collection and reclaimed enough space. We do the
487 // first attempt (without holding the Heap_lock) here and the
488 // follow-on attempt will be at the start of the next loop
489 // iteration (after taking the Heap_lock).
490 size_t dummy = 0;
491 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
492 if (result != NULL) {
493 return result;
494 }
495
496 // Give a warning if we seem to be looping forever.
497 if ((QueuedAllocationWarningCount > 0) &&
498 (try_count % QueuedAllocationWarningCount == 0)) {
499 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
500 Thread::current()->name(), try_count, word_size);
501 }
502 }
503
504 ShouldNotReachHere();
505 return NULL;
506 }
507
508 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
509 assert_at_safepoint_on_vm_thread();
510 if (_archive_allocator == NULL) {
511 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
512 }
513 }
514
515 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
516 // Allocations in archive regions cannot be of a size that would be considered
517 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
518 // may be different at archive-restore time.
519 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
520 }
521
522 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
523 assert_at_safepoint_on_vm_thread();
524 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
525 if (is_archive_alloc_too_large(word_size)) {
526 return NULL;
527 }
528 return _archive_allocator->archive_mem_allocate(word_size);
529 }
530
531 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
532 size_t end_alignment_in_bytes) {
533 assert_at_safepoint_on_vm_thread();
534 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
535
536 // Call complete_archive to do the real work, filling in the MemRegion
537 // array with the archive regions.
538 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
539 delete _archive_allocator;
540 _archive_allocator = NULL;
541 }
542
543 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
544 assert(ranges != NULL, "MemRegion array NULL");
545 assert(count != 0, "No MemRegions provided");
546 MemRegion reserved = _hrm->reserved();
547 for (size_t i = 0; i < count; i++) {
548 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
549 return false;
550 }
551 }
552 return true;
553 }
554
555 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
556 size_t count,
557 bool open) {
558 assert(!is_init_completed(), "Expect to be called at JVM init time");
559 assert(ranges != NULL, "MemRegion array NULL");
560 assert(count != 0, "No MemRegions provided");
561 MutexLocker x(Heap_lock);
562
563 MemRegion reserved = _hrm->reserved();
564 HeapWord* prev_last_addr = NULL;
565 HeapRegion* prev_last_region = NULL;
566
567 // Temporarily disable pretouching of heap pages. This interface is used
568 // when mmap'ing archived heap data in, so pre-touching is wasted.
569 FlagSetting fs(AlwaysPreTouch, false);
570
571 // Enable archive object checking used by G1MarkSweep. We have to let it know
572 // about each archive range, so that objects in those ranges aren't marked.
573 G1ArchiveAllocator::enable_archive_object_check();
574
575 // For each specified MemRegion range, allocate the corresponding G1
576 // regions and mark them as archive regions. We expect the ranges
577 // in ascending starting address order, without overlap.
578 for (size_t i = 0; i < count; i++) {
579 MemRegion curr_range = ranges[i];
580 HeapWord* start_address = curr_range.start();
581 size_t word_size = curr_range.word_size();
582 HeapWord* last_address = curr_range.last();
583 size_t commits = 0;
584
585 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
586 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
587 p2i(start_address), p2i(last_address));
588 guarantee(start_address > prev_last_addr,
589 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
590 p2i(start_address), p2i(prev_last_addr));
591 prev_last_addr = last_address;
592
593 // Check for ranges that start in the same G1 region in which the previous
594 // range ended, and adjust the start address so we don't try to allocate
595 // the same region again. If the current range is entirely within that
596 // region, skip it, just adjusting the recorded top.
597 HeapRegion* start_region = _hrm->addr_to_region(start_address);
598 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
599 start_address = start_region->end();
600 if (start_address > last_address) {
601 increase_used(word_size * HeapWordSize);
602 start_region->set_top(last_address + 1);
603 continue;
604 }
605 start_region->set_top(start_address);
606 curr_range = MemRegion(start_address, last_address + 1);
607 start_region = _hrm->addr_to_region(start_address);
608 }
609
610 // Perform the actual region allocation, exiting if it fails.
611 // Then note how much new space we have allocated.
612 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
613 return false;
614 }
615 increase_used(word_size * HeapWordSize);
616 if (commits != 0) {
617 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
618 HeapRegion::GrainWords * HeapWordSize * commits);
619
620 }
621
622 // Mark each G1 region touched by the range as archive, add it to
623 // the old set, and set top.
624 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
625 HeapRegion* last_region = _hrm->addr_to_region(last_address);
626 prev_last_region = last_region;
627
628 while (curr_region != NULL) {
629 assert(curr_region->is_empty() && !curr_region->is_pinned(),
630 "Region already in use (index %u)", curr_region->hrm_index());
631 if (open) {
632 curr_region->set_open_archive();
633 } else {
634 curr_region->set_closed_archive();
635 }
636 _hr_printer.alloc(curr_region);
637 _archive_set.add(curr_region);
638 HeapWord* top;
639 HeapRegion* next_region;
640 if (curr_region != last_region) {
641 top = curr_region->end();
642 next_region = _hrm->next_region_in_heap(curr_region);
643 } else {
644 top = last_address + 1;
645 next_region = NULL;
646 }
647 curr_region->set_top(top);
648 curr_region = next_region;
649 }
650
651 // Notify mark-sweep of the archive
652 G1ArchiveAllocator::set_range_archive(curr_range, open);
653 }
654 return true;
655 }
656
657 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
658 assert(!is_init_completed(), "Expect to be called at JVM init time");
659 assert(ranges != NULL, "MemRegion array NULL");
660 assert(count != 0, "No MemRegions provided");
661 MemRegion reserved = _hrm->reserved();
662 HeapWord *prev_last_addr = NULL;
663 HeapRegion* prev_last_region = NULL;
664
665 // For each MemRegion, create filler objects, if needed, in the G1 regions
666 // that contain the address range. The address range actually within the
667 // MemRegion will not be modified. That is assumed to have been initialized
668 // elsewhere, probably via an mmap of archived heap data.
669 MutexLocker x(Heap_lock);
670 for (size_t i = 0; i < count; i++) {
671 HeapWord* start_address = ranges[i].start();
672 HeapWord* last_address = ranges[i].last();
673
674 assert(reserved.contains(start_address) && reserved.contains(last_address),
675 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
676 p2i(start_address), p2i(last_address));
677 assert(start_address > prev_last_addr,
678 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
679 p2i(start_address), p2i(prev_last_addr));
680
681 HeapRegion* start_region = _hrm->addr_to_region(start_address);
682 HeapRegion* last_region = _hrm->addr_to_region(last_address);
683 HeapWord* bottom_address = start_region->bottom();
684
685 // Check for a range beginning in the same region in which the
686 // previous one ended.
687 if (start_region == prev_last_region) {
688 bottom_address = prev_last_addr + 1;
689 }
690
691 // Verify that the regions were all marked as archive regions by
692 // alloc_archive_regions.
693 HeapRegion* curr_region = start_region;
694 while (curr_region != NULL) {
695 guarantee(curr_region->is_archive(),
696 "Expected archive region at index %u", curr_region->hrm_index());
697 if (curr_region != last_region) {
698 curr_region = _hrm->next_region_in_heap(curr_region);
699 } else {
700 curr_region = NULL;
701 }
702 }
703
704 prev_last_addr = last_address;
705 prev_last_region = last_region;
706
707 // Fill the memory below the allocated range with dummy object(s),
708 // if the region bottom does not match the range start, or if the previous
709 // range ended within the same G1 region, and there is a gap.
710 if (start_address != bottom_address) {
711 size_t fill_size = pointer_delta(start_address, bottom_address);
712 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
713 increase_used(fill_size * HeapWordSize);
714 }
715 }
716 }
717
718 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
719 size_t desired_word_size,
720 size_t* actual_word_size) {
721 assert_heap_not_locked_and_not_at_safepoint();
722 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
723 "be called for humongous allocation requests");
724
725 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
726
727 if (result == NULL) {
728 *actual_word_size = desired_word_size;
729 result = attempt_allocation_slow(desired_word_size);
730 }
731
732 assert_heap_not_locked();
733 if (result != NULL) {
734 assert(*actual_word_size != 0, "Actual size must have been set here");
735 dirty_young_block(result, *actual_word_size);
736 } else {
737 *actual_word_size = 0;
738 }
739
740 return result;
741 }
742
743 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
744 assert(!is_init_completed(), "Expect to be called at JVM init time");
745 assert(ranges != NULL, "MemRegion array NULL");
746 assert(count != 0, "No MemRegions provided");
747 MemRegion reserved = _hrm->reserved();
748 HeapWord* prev_last_addr = NULL;
749 HeapRegion* prev_last_region = NULL;
750 size_t size_used = 0;
751 size_t uncommitted_regions = 0;
752
753 // For each Memregion, free the G1 regions that constitute it, and
754 // notify mark-sweep that the range is no longer to be considered 'archive.'
755 MutexLocker x(Heap_lock);
756 for (size_t i = 0; i < count; i++) {
757 HeapWord* start_address = ranges[i].start();
758 HeapWord* last_address = ranges[i].last();
759
760 assert(reserved.contains(start_address) && reserved.contains(last_address),
761 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
762 p2i(start_address), p2i(last_address));
763 assert(start_address > prev_last_addr,
764 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
765 p2i(start_address), p2i(prev_last_addr));
766 size_used += ranges[i].byte_size();
767 prev_last_addr = last_address;
768
769 HeapRegion* start_region = _hrm->addr_to_region(start_address);
770 HeapRegion* last_region = _hrm->addr_to_region(last_address);
771
772 // Check for ranges that start in the same G1 region in which the previous
773 // range ended, and adjust the start address so we don't try to free
774 // the same region again. If the current range is entirely within that
775 // region, skip it.
776 if (start_region == prev_last_region) {
777 start_address = start_region->end();
778 if (start_address > last_address) {
779 continue;
780 }
781 start_region = _hrm->addr_to_region(start_address);
782 }
783 prev_last_region = last_region;
784
785 // After verifying that each region was marked as an archive region by
786 // alloc_archive_regions, set it free and empty and uncommit it.
787 HeapRegion* curr_region = start_region;
788 while (curr_region != NULL) {
789 guarantee(curr_region->is_archive(),
790 "Expected archive region at index %u", curr_region->hrm_index());
791 uint curr_index = curr_region->hrm_index();
792 _archive_set.remove(curr_region);
793 curr_region->set_free();
794 curr_region->set_top(curr_region->bottom());
795 if (curr_region != last_region) {
796 curr_region = _hrm->next_region_in_heap(curr_region);
797 } else {
798 curr_region = NULL;
799 }
800 _hrm->shrink_at(curr_index, 1);
801 uncommitted_regions++;
802 }
803
804 // Notify mark-sweep that this is no longer an archive range.
805 G1ArchiveAllocator::clear_range_archive(ranges[i]);
806 }
807
808 if (uncommitted_regions != 0) {
809 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
810 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
811 }
812 decrease_used(size_used);
813 }
814
815 oop G1CollectedHeap::materialize_archived_object(oop obj) {
816 assert(obj != NULL, "archived obj is NULL");
817 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
818
819 // Loading an archived object makes it strongly reachable. If it is
820 // loaded during concurrent marking, it must be enqueued to the SATB
821 // queue, shading the previously white object gray.
822 G1BarrierSet::enqueue(obj);
823
824 return obj;
825 }
826
827 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
828 ResourceMark rm; // For retrieving the thread names in log messages.
829
830 // The structure of this method has a lot of similarities to
831 // attempt_allocation_slow(). The reason these two were not merged
832 // into a single one is that such a method would require several "if
833 // allocation is not humongous do this, otherwise do that"
834 // conditional paths which would obscure its flow. In fact, an early
835 // version of this code did use a unified method which was harder to
836 // follow and, as a result, it had subtle bugs that were hard to
837 // track down. So keeping these two methods separate allows each to
838 // be more readable. It will be good to keep these two in sync as
839 // much as possible.
840
841 assert_heap_not_locked_and_not_at_safepoint();
842 assert(is_humongous(word_size), "attempt_allocation_humongous() "
843 "should only be called for humongous allocations");
844
845 // Humongous objects can exhaust the heap quickly, so we should check if we
846 // need to start a marking cycle at each humongous object allocation. We do
847 // the check before we do the actual allocation. The reason for doing it
848 // before the allocation is that we avoid having to keep track of the newly
849 // allocated memory while we do a GC.
850 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
851 word_size)) {
852 collect(GCCause::_g1_humongous_allocation);
853 }
854
855 // We will loop until a) we manage to successfully perform the
856 // allocation or b) we successfully schedule a collection which
857 // fails to perform the allocation. b) is the only case when we'll
858 // return NULL.
859 HeapWord* result = NULL;
860 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
861 bool should_try_gc;
862 uint gc_count_before;
863
864
865 {
866 MutexLocker x(Heap_lock);
867
868 // Given that humongous objects are not allocated in young
869 // regions, we'll first try to do the allocation without doing a
870 // collection hoping that there's enough space in the heap.
871 result = humongous_obj_allocate(word_size);
872 if (result != NULL) {
873 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
874 policy()->old_gen_alloc_tracker()->
875 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
876 return result;
877 }
878
879 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
880 // the GCLocker initiated GC has been performed and then retry. This includes
881 // the case when the GC Locker is not active but has not been performed.
882 should_try_gc = !GCLocker::needs_gc();
883 // Read the GC count while still holding the Heap_lock.
884 gc_count_before = total_collections();
885 }
886
887 if (should_try_gc) {
888 bool succeeded;
889 result = do_collection_pause(word_size, gc_count_before, &succeeded,
890 GCCause::_g1_humongous_allocation);
891 if (result != NULL) {
892 assert(succeeded, "only way to get back a non-NULL result");
893 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
894 Thread::current()->name(), p2i(result));
895 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
896 policy()->old_gen_alloc_tracker()->
897 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
898 return result;
899 }
900
901 if (succeeded) {
902 // We successfully scheduled a collection which failed to allocate. No
903 // point in trying to allocate further. We'll just return NULL.
904 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
905 SIZE_FORMAT " words", Thread::current()->name(), word_size);
906 return NULL;
907 }
908 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
909 Thread::current()->name(), word_size);
910 } else {
911 // Failed to schedule a collection.
912 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
913 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
914 SIZE_FORMAT " words", Thread::current()->name(), word_size);
915 return NULL;
916 }
917 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
918 // The GCLocker is either active or the GCLocker initiated
919 // GC has not yet been performed. Stall until it is and
920 // then retry the allocation.
921 GCLocker::stall_until_clear();
922 gclocker_retry_count += 1;
923 }
924
925
926 // We can reach here if we were unsuccessful in scheduling a
927 // collection (because another thread beat us to it) or if we were
928 // stalled due to the GC locker. In either can we should retry the
929 // allocation attempt in case another thread successfully
930 // performed a collection and reclaimed enough space.
931 // Humongous object allocation always needs a lock, so we wait for the retry
932 // in the next iteration of the loop, unlike for the regular iteration case.
933 // Give a warning if we seem to be looping forever.
934
935 if ((QueuedAllocationWarningCount > 0) &&
936 (try_count % QueuedAllocationWarningCount == 0)) {
937 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
938 Thread::current()->name(), try_count, word_size);
939 }
940 }
941
942 ShouldNotReachHere();
943 return NULL;
944 }
945
946 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
947 bool expect_null_mutator_alloc_region) {
948 assert_at_safepoint_on_vm_thread();
949 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
950 "the current alloc region was unexpectedly found to be non-NULL");
951
952 if (!is_humongous(word_size)) {
953 return _allocator->attempt_allocation_locked(word_size);
954 } else {
955 HeapWord* result = humongous_obj_allocate(word_size);
956 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
957 collector_state()->set_initiate_conc_mark_if_possible(true);
958 }
959 return result;
960 }
961
962 ShouldNotReachHere();
963 }
964
965 class PostCompactionPrinterClosure: public HeapRegionClosure {
966 private:
967 G1HRPrinter* _hr_printer;
968 public:
969 bool do_heap_region(HeapRegion* hr) {
970 assert(!hr->is_young(), "not expecting to find young regions");
971 _hr_printer->post_compaction(hr);
972 return false;
973 }
974
975 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
976 : _hr_printer(hr_printer) { }
977 };
978
979 void G1CollectedHeap::print_hrm_post_compaction() {
980 if (_hr_printer.is_active()) {
981 PostCompactionPrinterClosure cl(hr_printer());
982 heap_region_iterate(&cl);
983 }
984 }
985
986 void G1CollectedHeap::abort_concurrent_cycle() {
987 // If we start the compaction before the CM threads finish
988 // scanning the root regions we might trip them over as we'll
989 // be moving objects / updating references. So let's wait until
990 // they are done. By telling them to abort, they should complete
991 // early.
992 _cm->root_regions()->abort();
993 _cm->root_regions()->wait_until_scan_finished();
994
995 // Disable discovery and empty the discovered lists
996 // for the CM ref processor.
997 _ref_processor_cm->disable_discovery();
998 _ref_processor_cm->abandon_partial_discovery();
999 _ref_processor_cm->verify_no_references_recorded();
1000
1001 // Abandon current iterations of concurrent marking and concurrent
1002 // refinement, if any are in progress.
1003 concurrent_mark()->concurrent_cycle_abort();
1004 }
1005
1006 void G1CollectedHeap::prepare_heap_for_full_collection() {
1007 // Make sure we'll choose a new allocation region afterwards.
1008 _allocator->release_mutator_alloc_regions();
1009 _allocator->abandon_gc_alloc_regions();
1010
1011 // We may have added regions to the current incremental collection
1012 // set between the last GC or pause and now. We need to clear the
1013 // incremental collection set and then start rebuilding it afresh
1014 // after this full GC.
1015 abandon_collection_set(collection_set());
1016
1017 tear_down_region_sets(false /* free_list_only */);
1018
1019 hrm()->prepare_for_full_collection_start();
1020 }
1021
1022 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1023 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1024 assert_used_and_recalculate_used_equal(this);
1025 _verifier->verify_region_sets_optional();
1026 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1027 _verifier->check_bitmaps("Full GC Start");
1028 }
1029
1030 void G1CollectedHeap::prepare_heap_for_mutators() {
1031 hrm()->prepare_for_full_collection_end();
1032
1033 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1034 ClassLoaderDataGraph::purge();
1035 MetaspaceUtils::verify_metrics();
1036
1037 // Prepare heap for normal collections.
1038 assert(num_free_regions() == 0, "we should not have added any free regions");
1039 rebuild_region_sets(false /* free_list_only */);
1040 abort_refinement();
1041 resize_heap_if_necessary();
1042
1043 // Rebuild the strong code root lists for each region
1044 rebuild_strong_code_roots();
1045
1046 // Purge code root memory
1047 purge_code_root_memory();
1048
1049 // Start a new incremental collection set for the next pause
1050 start_new_collection_set();
1051
1052 _allocator->init_mutator_alloc_regions();
1053
1054 // Post collection state updates.
1055 MetaspaceGC::compute_new_size();
1056 }
1057
1058 void G1CollectedHeap::abort_refinement() {
1059 if (_hot_card_cache->use_cache()) {
1060 _hot_card_cache->reset_hot_cache();
1061 }
1062
1063 // Discard all remembered set updates and reset refinement statistics.
1064 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1065 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1066 "DCQS should be empty");
1067 concurrent_refine()->get_and_reset_refinement_stats();
1068 }
1069
1070 void G1CollectedHeap::verify_after_full_collection() {
1071 _hrm->verify_optional();
1072 _verifier->verify_region_sets_optional();
1073 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1074 // Clear the previous marking bitmap, if needed for bitmap verification.
1075 // Note we cannot do this when we clear the next marking bitmap in
1076 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1077 // objects marked during a full GC against the previous bitmap.
1078 // But we need to clear it before calling check_bitmaps below since
1079 // the full GC has compacted objects and updated TAMS but not updated
1080 // the prev bitmap.
1081 if (G1VerifyBitmaps) {
1082 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1083 _cm->clear_prev_bitmap(workers());
1084 }
1085 // This call implicitly verifies that the next bitmap is clear after Full GC.
1086 _verifier->check_bitmaps("Full GC End");
1087
1088 // At this point there should be no regions in the
1089 // entire heap tagged as young.
1090 assert(check_young_list_empty(), "young list should be empty at this point");
1091
1092 // Note: since we've just done a full GC, concurrent
1093 // marking is no longer active. Therefore we need not
1094 // re-enable reference discovery for the CM ref processor.
1095 // That will be done at the start of the next marking cycle.
1096 // We also know that the STW processor should no longer
1097 // discover any new references.
1098 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1099 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1100 _ref_processor_stw->verify_no_references_recorded();
1101 _ref_processor_cm->verify_no_references_recorded();
1102 }
1103
1104 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1105 // Post collection logging.
1106 // We should do this after we potentially resize the heap so
1107 // that all the COMMIT / UNCOMMIT events are generated before
1108 // the compaction events.
1109 print_hrm_post_compaction();
1110 heap_transition->print();
1111 print_heap_after_gc();
1112 print_heap_regions();
1113 }
1114
1115 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1116 bool clear_all_soft_refs) {
1117 assert_at_safepoint_on_vm_thread();
1118
1119 if (GCLocker::check_active_before_gc()) {
1120 // Full GC was not completed.
1121 return false;
1122 }
1123
1124 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1125 soft_ref_policy()->should_clear_all_soft_refs();
1126
1127 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1128 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1129
1130 collector.prepare_collection();
1131 collector.collect();
1132 collector.complete_collection();
1133
1134 // Full collection was successfully completed.
1135 return true;
1136 }
1137
1138 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1139 // Currently, there is no facility in the do_full_collection(bool) API to notify
1140 // the caller that the collection did not succeed (e.g., because it was locked
1141 // out by the GC locker). So, right now, we'll ignore the return value.
1142 bool dummy = do_full_collection(true, /* explicit_gc */
1143 clear_all_soft_refs);
1144 }
1145
1146 void G1CollectedHeap::resize_heap_if_necessary() {
1147 assert_at_safepoint_on_vm_thread();
1148
1149 bool should_expand;
1150 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1151
1152 if (resize_amount == 0) {
1153 return;
1154 } else if (should_expand) {
1155 expand(resize_amount, _workers);
1156 } else {
1157 shrink(resize_amount);
1158 }
1159 }
1160
1161 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1162 bool do_gc,
1163 bool clear_all_soft_refs,
1164 bool expect_null_mutator_alloc_region,
1165 bool* gc_succeeded) {
1166 *gc_succeeded = true;
1167 // Let's attempt the allocation first.
1168 HeapWord* result =
1169 attempt_allocation_at_safepoint(word_size,
1170 expect_null_mutator_alloc_region);
1171 if (result != NULL) {
1172 return result;
1173 }
1174
1175 // In a G1 heap, we're supposed to keep allocation from failing by
1176 // incremental pauses. Therefore, at least for now, we'll favor
1177 // expansion over collection. (This might change in the future if we can
1178 // do something smarter than full collection to satisfy a failed alloc.)
1179 result = expand_and_allocate(word_size);
1180 if (result != NULL) {
1181 return result;
1182 }
1183
1184 if (do_gc) {
1185 // Expansion didn't work, we'll try to do a Full GC.
1186 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1187 clear_all_soft_refs);
1188 }
1189
1190 return NULL;
1191 }
1192
1193 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1194 bool* succeeded) {
1195 assert_at_safepoint_on_vm_thread();
1196
1197 // Attempts to allocate followed by Full GC.
1198 HeapWord* result =
1199 satisfy_failed_allocation_helper(word_size,
1200 true, /* do_gc */
1201 false, /* clear_all_soft_refs */
1202 false, /* expect_null_mutator_alloc_region */
1203 succeeded);
1204
1205 if (result != NULL || !*succeeded) {
1206 return result;
1207 }
1208
1209 // Attempts to allocate followed by Full GC that will collect all soft references.
1210 result = satisfy_failed_allocation_helper(word_size,
1211 true, /* do_gc */
1212 true, /* clear_all_soft_refs */
1213 true, /* expect_null_mutator_alloc_region */
1214 succeeded);
1215
1216 if (result != NULL || !*succeeded) {
1217 return result;
1218 }
1219
1220 // Attempts to allocate, no GC
1221 result = satisfy_failed_allocation_helper(word_size,
1222 false, /* do_gc */
1223 false, /* clear_all_soft_refs */
1224 true, /* expect_null_mutator_alloc_region */
1225 succeeded);
1226
1227 if (result != NULL) {
1228 return result;
1229 }
1230
1231 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1232 "Flag should have been handled and cleared prior to this point");
1233
1234 // What else? We might try synchronous finalization later. If the total
1235 // space available is large enough for the allocation, then a more
1236 // complete compaction phase than we've tried so far might be
1237 // appropriate.
1238 return NULL;
1239 }
1240
1241 // Attempting to expand the heap sufficiently
1242 // to support an allocation of the given "word_size". If
1243 // successful, perform the allocation and return the address of the
1244 // allocated block, or else "NULL".
1245
1246 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1247 assert_at_safepoint_on_vm_thread();
1248
1249 _verifier->verify_region_sets_optional();
1250
1251 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1252 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1253 word_size * HeapWordSize);
1254
1255
1256 if (expand(expand_bytes, _workers)) {
1257 _hrm->verify_optional();
1258 _verifier->verify_region_sets_optional();
1259 return attempt_allocation_at_safepoint(word_size,
1260 false /* expect_null_mutator_alloc_region */);
1261 }
1262 return NULL;
1263 }
1264
1265 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1266 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1267 aligned_expand_bytes = align_up(aligned_expand_bytes,
1268 HeapRegion::GrainBytes);
1269
1270 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1271 expand_bytes, aligned_expand_bytes);
1272
1273 if (is_maximal_no_gc()) {
1274 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1275 return false;
1276 }
1277
1278 double expand_heap_start_time_sec = os::elapsedTime();
1279 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1280 assert(regions_to_expand > 0, "Must expand by at least one region");
1281
1282 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1283 if (expand_time_ms != NULL) {
1284 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1285 }
1286
1287 if (expanded_by > 0) {
1288 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1289 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1290 policy()->record_new_heap_size(num_regions());
1291 } else {
1292 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1293
1294 // The expansion of the virtual storage space was unsuccessful.
1295 // Let's see if it was because we ran out of swap.
1296 if (G1ExitOnExpansionFailure &&
1297 _hrm->available() >= regions_to_expand) {
1298 // We had head room...
1299 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1300 }
1301 }
1302 return regions_to_expand > 0;
1303 }
1304
1305 bool G1CollectedHeap::expand_single_region(uint node_index) {
1306 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1307
1308 if (expanded_by == 0) {
1309 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1310 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1311 return false;
1312 }
1313
1314 policy()->record_new_heap_size(num_regions());
1315 return true;
1316 }
1317
1318 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1319 size_t aligned_shrink_bytes =
1320 ReservedSpace::page_align_size_down(shrink_bytes);
1321 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1322 HeapRegion::GrainBytes);
1323 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1324
1325 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1326 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1327
1328 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",
1329 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1330 if (num_regions_removed > 0) {
1331 policy()->record_new_heap_size(num_regions());
1332 } else {
1333 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1334 }
1335 }
1336
1337 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1338 _verifier->verify_region_sets_optional();
1339
1340 // We should only reach here at the end of a Full GC or during Remark which
1341 // means we should not not be holding to any GC alloc regions. The method
1342 // below will make sure of that and do any remaining clean up.
1343 _allocator->abandon_gc_alloc_regions();
1344
1345 // Instead of tearing down / rebuilding the free lists here, we
1346 // could instead use the remove_all_pending() method on free_list to
1347 // remove only the ones that we need to remove.
1348 tear_down_region_sets(true /* free_list_only */);
1349 shrink_helper(shrink_bytes);
1350 rebuild_region_sets(true /* free_list_only */);
1351
1352 _hrm->verify_optional();
1353 _verifier->verify_region_sets_optional();
1354 }
1355
1356 class OldRegionSetChecker : public HeapRegionSetChecker {
1357 public:
1358 void check_mt_safety() {
1359 // Master Old Set MT safety protocol:
1360 // (a) If we're at a safepoint, operations on the master old set
1361 // should be invoked:
1362 // - by the VM thread (which will serialize them), or
1363 // - by the GC workers while holding the FreeList_lock, if we're
1364 // at a safepoint for an evacuation pause (this lock is taken
1365 // anyway when an GC alloc region is retired so that a new one
1366 // is allocated from the free list), or
1367 // - by the GC workers while holding the OldSets_lock, if we're at a
1368 // safepoint for a cleanup pause.
1369 // (b) If we're not at a safepoint, operations on the master old set
1370 // should be invoked while holding the Heap_lock.
1371
1372 if (SafepointSynchronize::is_at_safepoint()) {
1373 guarantee(Thread::current()->is_VM_thread() ||
1374 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1375 "master old set MT safety protocol at a safepoint");
1376 } else {
1377 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1378 }
1379 }
1380 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1381 const char* get_description() { return "Old Regions"; }
1382 };
1383
1384 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1385 public:
1386 void check_mt_safety() {
1387 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1388 "May only change archive regions during initialization or safepoint.");
1389 }
1390 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1391 const char* get_description() { return "Archive Regions"; }
1392 };
1393
1394 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1395 public:
1396 void check_mt_safety() {
1397 // Humongous Set MT safety protocol:
1398 // (a) If we're at a safepoint, operations on the master humongous
1399 // set should be invoked by either the VM thread (which will
1400 // serialize them) or by the GC workers while holding the
1401 // OldSets_lock.
1402 // (b) If we're not at a safepoint, operations on the master
1403 // humongous set should be invoked while holding the Heap_lock.
1404
1405 if (SafepointSynchronize::is_at_safepoint()) {
1406 guarantee(Thread::current()->is_VM_thread() ||
1407 OldSets_lock->owned_by_self(),
1408 "master humongous set MT safety protocol at a safepoint");
1409 } else {
1410 guarantee(Heap_lock->owned_by_self(),
1411 "master humongous set MT safety protocol outside a safepoint");
1412 }
1413 }
1414 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1415 const char* get_description() { return "Humongous Regions"; }
1416 };
1417
1418 G1CollectedHeap::G1CollectedHeap() :
1419 CollectedHeap(),
1420 _young_gen_sampling_thread(NULL),
1421 _workers(NULL),
1422 _card_table(NULL),
1423 _collection_pause_end(Ticks::now()),
1424 _soft_ref_policy(),
1425 _old_set("Old Region Set", new OldRegionSetChecker()),
1426 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1427 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1428 _bot(NULL),
1429 _listener(),
1430 _numa(G1NUMA::create()),
1431 _hrm(NULL),
1432 _allocator(NULL),
1433 _verifier(NULL),
1434 _summary_bytes_used(0),
1435 _bytes_used_during_gc(0),
1436 _archive_allocator(NULL),
1437 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1438 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1439 _expand_heap_after_alloc_failure(true),
1440 _g1mm(NULL),
1441 _humongous_reclaim_candidates(),
1442 _has_humongous_reclaim_candidates(false),
1443 _hr_printer(),
1444 _collector_state(),
1445 _old_marking_cycles_started(0),
1446 _old_marking_cycles_completed(0),
1447 _eden(),
1448 _survivor(),
1449 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1450 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1451 _policy(G1Policy::create_policy(_gc_timer_stw)),
1452 _heap_sizing_policy(NULL),
1453 _collection_set(this, _policy),
1454 _hot_card_cache(NULL),
1455 _rem_set(NULL),
1456 _cm(NULL),
1457 _cm_thread(NULL),
1458 _cr(NULL),
1459 _task_queues(NULL),
1460 _evacuation_failed(false),
1461 _evacuation_failed_info_array(NULL),
1462 _preserved_marks_set(true /* in_c_heap */),
1463 #ifndef PRODUCT
1464 _evacuation_failure_alot_for_current_gc(false),
1465 _evacuation_failure_alot_gc_number(0),
1466 _evacuation_failure_alot_count(0),
1467 #endif
1468 _ref_processor_stw(NULL),
1469 _is_alive_closure_stw(this),
1470 _is_subject_to_discovery_stw(this),
1471 _ref_processor_cm(NULL),
1472 _is_alive_closure_cm(this),
1473 _is_subject_to_discovery_cm(this),
1474 _region_attr() {
1475
1476 _verifier = new G1HeapVerifier(this);
1477
1478 _allocator = new G1Allocator(this);
1479
1480 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1481
1482 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1483
1484 // Override the default _filler_array_max_size so that no humongous filler
1485 // objects are created.
1486 _filler_array_max_size = _humongous_object_threshold_in_words;
1487
1488 uint n_queues = ParallelGCThreads;
1489 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1490
1491 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1492
1493 for (uint i = 0; i < n_queues; i++) {
1494 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1495 q->initialize();
1496 _task_queues->register_queue(i, q);
1497 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1498 }
1499
1500 // Initialize the G1EvacuationFailureALot counters and flags.
1501 NOT_PRODUCT(reset_evacuation_should_fail();)
1502 _gc_tracer_stw->initialize();
1503
1504 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1505 }
1506
1507 static size_t actual_reserved_page_size(ReservedSpace rs) {
1508 size_t page_size = os::vm_page_size();
1509 if (UseLargePages) {
1510 // There are two ways to manage large page memory.
1511 // 1. OS supports committing large page memory.
1512 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1513 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1514 // we reserved memory without large page.
1515 if (os::can_commit_large_page_memory() || rs.special()) {
1516 // An alignment at ReservedSpace comes from preferred page size or
1517 // heap alignment, and if the alignment came from heap alignment, it could be
1518 // larger than large pages size. So need to cap with the large page size.
1519 page_size = MIN2(rs.alignment(), os::large_page_size());
1520 }
1521 }
1522
1523 return page_size;
1524 }
1525
1526 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1527 size_t size,
1528 size_t translation_factor) {
1529 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1530 // Allocate a new reserved space, preferring to use large pages.
1531 ReservedSpace rs(size, preferred_page_size);
1532 size_t page_size = actual_reserved_page_size(rs);
1533 G1RegionToSpaceMapper* result =
1534 G1RegionToSpaceMapper::create_mapper(rs,
1535 size,
1536 page_size,
1537 HeapRegion::GrainBytes,
1538 translation_factor,
1539 mtGC);
1540
1541 os::trace_page_sizes_for_requested_size(description,
1542 size,
1543 preferred_page_size,
1544 page_size,
1545 rs.base(),
1546 rs.size());
1547
1548 return result;
1549 }
1550
1551 jint G1CollectedHeap::initialize_concurrent_refinement() {
1552 jint ecode = JNI_OK;
1553 _cr = G1ConcurrentRefine::create(&ecode);
1554 return ecode;
1555 }
1556
1557 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1558 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1559 if (_young_gen_sampling_thread->osthread() == NULL) {
1560 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1561 return JNI_ENOMEM;
1562 }
1563 return JNI_OK;
1564 }
1565
1566 jint G1CollectedHeap::initialize() {
1567
1568 // Necessary to satisfy locking discipline assertions.
1569
1570 MutexLocker x(Heap_lock);
1571
1572 // While there are no constraints in the GC code that HeapWordSize
1573 // be any particular value, there are multiple other areas in the
1574 // system which believe this to be true (e.g. oop->object_size in some
1575 // cases incorrectly returns the size in wordSize units rather than
1576 // HeapWordSize).
1577 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1578
1579 size_t init_byte_size = InitialHeapSize;
1580 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1581
1582 // Ensure that the sizes are properly aligned.
1583 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1584 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1585 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1586
1587 // Reserve the maximum.
1588
1589 // When compressed oops are enabled, the preferred heap base
1590 // is calculated by subtracting the requested size from the
1591 // 32Gb boundary and using the result as the base address for
1592 // heap reservation. If the requested size is not aligned to
1593 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1594 // into the ReservedHeapSpace constructor) then the actual
1595 // base of the reserved heap may end up differing from the
1596 // address that was requested (i.e. the preferred heap base).
1597 // If this happens then we could end up using a non-optimal
1598 // compressed oops mode.
1599
1600 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1601 HeapAlignment);
1602
1603 initialize_reserved_region(heap_rs);
1604
1605 // Create the barrier set for the entire reserved region.
1606 G1CardTable* ct = new G1CardTable(heap_rs.region());
1607 ct->initialize();
1608 G1BarrierSet* bs = new G1BarrierSet(ct);
1609 bs->initialize();
1610 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1611 BarrierSet::set_barrier_set(bs);
1612 _card_table = ct;
1613
1614 {
1615 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1616 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1617 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1618 }
1619
1620 // Create the hot card cache.
1621 _hot_card_cache = new G1HotCardCache(this);
1622
1623 // Carve out the G1 part of the heap.
1624 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1625 size_t page_size = actual_reserved_page_size(heap_rs);
1626 G1RegionToSpaceMapper* heap_storage =
1627 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1628 g1_rs.size(),
1629 page_size,
1630 HeapRegion::GrainBytes,
1631 1,
1632 mtJavaHeap);
1633 if(heap_storage == NULL) {
1634 vm_shutdown_during_initialization("Could not initialize G1 heap");
1635 return JNI_ERR;
1636 }
1637
1638 os::trace_page_sizes("Heap",
1639 MinHeapSize,
1640 reserved_byte_size,
1641 page_size,
1642 heap_rs.base(),
1643 heap_rs.size());
1644 heap_storage->set_mapping_changed_listener(&_listener);
1645
1646 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1647 G1RegionToSpaceMapper* bot_storage =
1648 create_aux_memory_mapper("Block Offset Table",
1649 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1650 G1BlockOffsetTable::heap_map_factor());
1651
1652 G1RegionToSpaceMapper* cardtable_storage =
1653 create_aux_memory_mapper("Card Table",
1654 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1655 G1CardTable::heap_map_factor());
1656
1657 G1RegionToSpaceMapper* card_counts_storage =
1658 create_aux_memory_mapper("Card Counts Table",
1659 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1660 G1CardCounts::heap_map_factor());
1661
1662 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1663 G1RegionToSpaceMapper* prev_bitmap_storage =
1664 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1665 G1RegionToSpaceMapper* next_bitmap_storage =
1666 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1667
1668 _hrm = HeapRegionManager::create_manager(this);
1669
1670 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1671 _card_table->initialize(cardtable_storage);
1672
1673 // Do later initialization work for concurrent refinement.
1674 _hot_card_cache->initialize(card_counts_storage);
1675
1676 // 6843694 - ensure that the maximum region index can fit
1677 // in the remembered set structures.
1678 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1679 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1680
1681 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1682 // start within the first card.
1683 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1684 // Also create a G1 rem set.
1685 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1686 _rem_set->initialize(max_reserved_capacity(), max_regions());
1687
1688 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1689 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1690 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1691 "too many cards per region");
1692
1693 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1694
1695 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1696
1697 {
1698 HeapWord* start = _hrm->reserved().start();
1699 HeapWord* end = _hrm->reserved().end();
1700 size_t granularity = HeapRegion::GrainBytes;
1701
1702 _region_attr.initialize(start, end, granularity);
1703 _humongous_reclaim_candidates.initialize(start, end, granularity);
1704 }
1705
1706 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1707 true /* are_GC_task_threads */,
1708 false /* are_ConcurrentGC_threads */);
1709 if (_workers == NULL) {
1710 return JNI_ENOMEM;
1711 }
1712 _workers->initialize_workers();
1713
1714 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1715
1716 // Create the G1ConcurrentMark data structure and thread.
1717 // (Must do this late, so that "max_regions" is defined.)
1718 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1719 _cm_thread = _cm->cm_thread();
1720
1721 // Now expand into the initial heap size.
1722 if (!expand(init_byte_size, _workers)) {
1723 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1724 return JNI_ENOMEM;
1725 }
1726
1727 // Perform any initialization actions delegated to the policy.
1728 policy()->init(this, &_collection_set);
1729
1730 jint ecode = initialize_concurrent_refinement();
1731 if (ecode != JNI_OK) {
1732 return ecode;
1733 }
1734
1735 ecode = initialize_young_gen_sampling_thread();
1736 if (ecode != JNI_OK) {
1737 return ecode;
1738 }
1739
1740 {
1741 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1742 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1743 dcqs.set_max_cards(concurrent_refine()->red_zone());
1744 }
1745
1746 // Here we allocate the dummy HeapRegion that is required by the
1747 // G1AllocRegion class.
1748 HeapRegion* dummy_region = _hrm->get_dummy_region();
1749
1750 // We'll re-use the same region whether the alloc region will
1751 // require BOT updates or not and, if it doesn't, then a non-young
1752 // region will complain that it cannot support allocations without
1753 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1754 dummy_region->set_eden();
1755 // Make sure it's full.
1756 dummy_region->set_top(dummy_region->end());
1757 G1AllocRegion::setup(this, dummy_region);
1758
1759 _allocator->init_mutator_alloc_regions();
1760
1761 // Do create of the monitoring and management support so that
1762 // values in the heap have been properly initialized.
1763 _g1mm = new G1MonitoringSupport(this);
1764
1765 G1StringDedup::initialize();
1766
1767 _preserved_marks_set.init(ParallelGCThreads);
1768
1769 _collection_set.initialize(max_regions());
1770
1771 G1InitLogger::print();
1772
1773 return JNI_OK;
1774 }
1775
1776 void G1CollectedHeap::stop() {
1777 // Stop all concurrent threads. We do this to make sure these threads
1778 // do not continue to execute and access resources (e.g. logging)
1779 // that are destroyed during shutdown.
1780 _cr->stop();
1781 _young_gen_sampling_thread->stop();
1782 _cm_thread->stop();
1783 if (G1StringDedup::is_enabled()) {
1784 G1StringDedup::stop();
1785 }
1786 }
1787
1788 void G1CollectedHeap::safepoint_synchronize_begin() {
1789 SuspendibleThreadSet::synchronize();
1790 }
1791
1792 void G1CollectedHeap::safepoint_synchronize_end() {
1793 SuspendibleThreadSet::desynchronize();
1794 }
1795
1796 void G1CollectedHeap::post_initialize() {
1797 CollectedHeap::post_initialize();
1798 ref_processing_init();
1799 }
1800
1801 void G1CollectedHeap::ref_processing_init() {
1802 // Reference processing in G1 currently works as follows:
1803 //
1804 // * There are two reference processor instances. One is
1805 // used to record and process discovered references
1806 // during concurrent marking; the other is used to
1807 // record and process references during STW pauses
1808 // (both full and incremental).
1809 // * Both ref processors need to 'span' the entire heap as
1810 // the regions in the collection set may be dotted around.
1811 //
1812 // * For the concurrent marking ref processor:
1813 // * Reference discovery is enabled at concurrent start.
1814 // * Reference discovery is disabled and the discovered
1815 // references processed etc during remarking.
1816 // * Reference discovery is MT (see below).
1817 // * Reference discovery requires a barrier (see below).
1818 // * Reference processing may or may not be MT
1819 // (depending on the value of ParallelRefProcEnabled
1820 // and ParallelGCThreads).
1821 // * A full GC disables reference discovery by the CM
1822 // ref processor and abandons any entries on it's
1823 // discovered lists.
1824 //
1825 // * For the STW processor:
1826 // * Non MT discovery is enabled at the start of a full GC.
1827 // * Processing and enqueueing during a full GC is non-MT.
1828 // * During a full GC, references are processed after marking.
1829 //
1830 // * Discovery (may or may not be MT) is enabled at the start
1831 // of an incremental evacuation pause.
1832 // * References are processed near the end of a STW evacuation pause.
1833 // * For both types of GC:
1834 // * Discovery is atomic - i.e. not concurrent.
1835 // * Reference discovery will not need a barrier.
1836
1837 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1838
1839 // Concurrent Mark ref processor
1840 _ref_processor_cm =
1841 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1842 mt_processing, // mt processing
1843 ParallelGCThreads, // degree of mt processing
1844 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1845 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1846 false, // Reference discovery is not atomic
1847 &_is_alive_closure_cm, // is alive closure
1848 true); // allow changes to number of processing threads
1849
1850 // STW ref processor
1851 _ref_processor_stw =
1852 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1853 mt_processing, // mt processing
1854 ParallelGCThreads, // degree of mt processing
1855 (ParallelGCThreads > 1), // mt discovery
1856 ParallelGCThreads, // degree of mt discovery
1857 true, // Reference discovery is atomic
1858 &_is_alive_closure_stw, // is alive closure
1859 true); // allow changes to number of processing threads
1860 }
1861
1862 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1863 return &_soft_ref_policy;
1864 }
1865
1866 size_t G1CollectedHeap::capacity() const {
1867 return _hrm->length() * HeapRegion::GrainBytes;
1868 }
1869
1870 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1871 return _hrm->total_free_bytes();
1872 }
1873
1874 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1875 _hot_card_cache->drain(cl, worker_id);
1876 }
1877
1878 // Computes the sum of the storage used by the various regions.
1879 size_t G1CollectedHeap::used() const {
1880 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1881 if (_archive_allocator != NULL) {
1882 result += _archive_allocator->used();
1883 }
1884 return result;
1885 }
1886
1887 size_t G1CollectedHeap::used_unlocked() const {
1888 return _summary_bytes_used;
1889 }
1890
1891 class SumUsedClosure: public HeapRegionClosure {
1892 size_t _used;
1893 public:
1894 SumUsedClosure() : _used(0) {}
1895 bool do_heap_region(HeapRegion* r) {
1896 _used += r->used();
1897 return false;
1898 }
1899 size_t result() { return _used; }
1900 };
1901
1902 size_t G1CollectedHeap::recalculate_used() const {
1903 SumUsedClosure blk;
1904 heap_region_iterate(&blk);
1905 return blk.result();
1906 }
1907
1908 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1909 switch (cause) {
1910 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1911 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1912 case GCCause::_wb_conc_mark: return true;
1913 default : return false;
1914 }
1915 }
1916
1917 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1918 switch (cause) {
1919 case GCCause::_g1_humongous_allocation: return true;
1920 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1921 case GCCause::_wb_breakpoint: return true;
1922 default: return is_user_requested_concurrent_full_gc(cause);
1923 }
1924 }
1925
1926 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1927 if (policy()->force_upgrade_to_full()) {
1928 return true;
1929 } else if (should_do_concurrent_full_gc(_gc_cause)) {
1930 return false;
1931 } else if (has_regions_left_for_allocation()) {
1932 return false;
1933 } else {
1934 return true;
1935 }
1936 }
1937
1938 #ifndef PRODUCT
1939 void G1CollectedHeap::allocate_dummy_regions() {
1940 // Let's fill up most of the region
1941 size_t word_size = HeapRegion::GrainWords - 1024;
1942 // And as a result the region we'll allocate will be humongous.
1943 guarantee(is_humongous(word_size), "sanity");
1944
1945 // _filler_array_max_size is set to humongous object threshold
1946 // but temporarily change it to use CollectedHeap::fill_with_object().
1947 AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size);
1948
1949 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1950 // Let's use the existing mechanism for the allocation
1951 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1952 if (dummy_obj != NULL) {
1953 MemRegion mr(dummy_obj, word_size);
1954 CollectedHeap::fill_with_object(mr);
1955 } else {
1956 // If we can't allocate once, we probably cannot allocate
1957 // again. Let's get out of the loop.
1958 break;
1959 }
1960 }
1961 }
1962 #endif // !PRODUCT
1963
1964 void G1CollectedHeap::increment_old_marking_cycles_started() {
1965 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1966 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1967 "Wrong marking cycle count (started: %d, completed: %d)",
1968 _old_marking_cycles_started, _old_marking_cycles_completed);
1969
1970 _old_marking_cycles_started++;
1971 }
1972
1973 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1974 bool whole_heap_examined) {
1975 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1976
1977 // We assume that if concurrent == true, then the caller is a
1978 // concurrent thread that was joined the Suspendible Thread
1979 // Set. If there's ever a cheap way to check this, we should add an
1980 // assert here.
1981
1982 // Given that this method is called at the end of a Full GC or of a
1983 // concurrent cycle, and those can be nested (i.e., a Full GC can
1984 // interrupt a concurrent cycle), the number of full collections
1985 // completed should be either one (in the case where there was no
1986 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1987 // behind the number of full collections started.
1988
1989 // This is the case for the inner caller, i.e. a Full GC.
1990 assert(concurrent ||
1991 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1992 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1993 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1994 "is inconsistent with _old_marking_cycles_completed = %u",
1995 _old_marking_cycles_started, _old_marking_cycles_completed);
1996
1997 // This is the case for the outer caller, i.e. the concurrent cycle.
1998 assert(!concurrent ||
1999 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2000 "for outer caller (concurrent cycle): "
2001 "_old_marking_cycles_started = %u "
2002 "is inconsistent with _old_marking_cycles_completed = %u",
2003 _old_marking_cycles_started, _old_marking_cycles_completed);
2004
2005 _old_marking_cycles_completed += 1;
2006 if (whole_heap_examined) {
2007 // Signal that we have completed a visit to all live objects.
2008 record_whole_heap_examined_timestamp();
2009 }
2010
2011 // We need to clear the "in_progress" flag in the CM thread before
2012 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2013 // is set) so that if a waiter requests another System.gc() it doesn't
2014 // incorrectly see that a marking cycle is still in progress.
2015 if (concurrent) {
2016 _cm_thread->set_idle();
2017 }
2018
2019 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2020 // for a full GC to finish that their wait is over.
2021 ml.notify_all();
2022 }
2023
2024 void G1CollectedHeap::collect(GCCause::Cause cause) {
2025 try_collect(cause);
2026 }
2027
2028 // Return true if (x < y) with allowance for wraparound.
2029 static bool gc_counter_less_than(uint x, uint y) {
2030 return (x - y) > (UINT_MAX/2);
2031 }
2032
2033 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2034 // Macro so msg printing is format-checked.
2035 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2036 do { \
2037 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2038 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2039 ResourceMark rm; /* For thread name. */ \
2040 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2041 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2042 Thread::current()->name(), \
2043 GCCause::to_string(cause)); \
2044 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2045 } \
2046 } while (0)
2047
2048 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2049 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2050
2051 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2052 uint gc_counter,
2053 uint old_marking_started_before) {
2054 assert_heap_not_locked();
2055 assert(should_do_concurrent_full_gc(cause),
2056 "Non-concurrent cause %s", GCCause::to_string(cause));
2057
2058 for (uint i = 1; true; ++i) {
2059 // Try to schedule concurrent start evacuation pause that will
2060 // start a concurrent cycle.
2061 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2062 VM_G1TryInitiateConcMark op(gc_counter,
2063 cause,
2064 policy()->max_pause_time_ms());
2065 VMThread::execute(&op);
2066
2067 // Request is trivially finished.
2068 if (cause == GCCause::_g1_periodic_collection) {
2069 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2070 return op.gc_succeeded();
2071 }
2072
2073 // If VMOp skipped initiating concurrent marking cycle because
2074 // we're terminating, then we're done.
2075 if (op.terminating()) {
2076 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2077 return false;
2078 }
2079
2080 // Lock to get consistent set of values.
2081 uint old_marking_started_after;
2082 uint old_marking_completed_after;
2083 {
2084 MutexLocker ml(Heap_lock);
2085 // Update gc_counter for retrying VMOp if needed. Captured here to be
2086 // consistent with the values we use below for termination tests. If
2087 // a retry is needed after a possible wait, and another collection
2088 // occurs in the meantime, it will cause our retry to be skipped and
2089 // we'll recheck for termination with updated conditions from that
2090 // more recent collection. That's what we want, rather than having
2091 // our retry possibly perform an unnecessary collection.
2092 gc_counter = total_collections();
2093 old_marking_started_after = _old_marking_cycles_started;
2094 old_marking_completed_after = _old_marking_cycles_completed;
2095 }
2096
2097 if (cause == GCCause::_wb_breakpoint) {
2098 if (op.gc_succeeded()) {
2099 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2100 return true;
2101 }
2102 // When _wb_breakpoint there can't be another cycle or deferred.
2103 assert(!op.cycle_already_in_progress(), "invariant");
2104 assert(!op.whitebox_attached(), "invariant");
2105 // Concurrent cycle attempt might have been cancelled by some other
2106 // collection, so retry. Unlike other cases below, we want to retry
2107 // even if cancelled by a STW full collection, because we really want
2108 // to start a concurrent cycle.
2109 if (old_marking_started_before != old_marking_started_after) {
2110 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2111 old_marking_started_before = old_marking_started_after;
2112 }
2113 } else if (!GCCause::is_user_requested_gc(cause)) {
2114 // For an "automatic" (not user-requested) collection, we just need to
2115 // ensure that progress is made.
2116 //
2117 // Request is finished if any of
2118 // (1) the VMOp successfully performed a GC,
2119 // (2) a concurrent cycle was already in progress,
2120 // (3) whitebox is controlling concurrent cycles,
2121 // (4) a new cycle was started (by this thread or some other), or
2122 // (5) a Full GC was performed.
2123 // Cases (4) and (5) are detected together by a change to
2124 // _old_marking_cycles_started.
2125 //
2126 // Note that (1) does not imply (4). If we're still in the mixed
2127 // phase of an earlier concurrent collection, the request to make the
2128 // collection a concurrent start won't be honored. If we don't check for
2129 // both conditions we'll spin doing back-to-back collections.
2130 if (op.gc_succeeded() ||
2131 op.cycle_already_in_progress() ||
2132 op.whitebox_attached() ||
2133 (old_marking_started_before != old_marking_started_after)) {
2134 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2135 return true;
2136 }
2137 } else { // User-requested GC.
2138 // For a user-requested collection, we want to ensure that a complete
2139 // full collection has been performed before returning, but without
2140 // waiting for more than needed.
2141
2142 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2143 // new cycle was started. That's good, because it's not clear what we
2144 // should do otherwise. Trying again just does back to back GCs.
2145 // Can't wait for someone else to start a cycle. And returning fails
2146 // to meet the goal of ensuring a full collection was performed.
2147 assert(!op.gc_succeeded() ||
2148 (old_marking_started_before != old_marking_started_after),
2149 "invariant: succeeded %s, started before %u, started after %u",
2150 BOOL_TO_STR(op.gc_succeeded()),
2151 old_marking_started_before, old_marking_started_after);
2152
2153 // Request is finished if a full collection (concurrent or stw)
2154 // was started after this request and has completed, e.g.
2155 // started_before < completed_after.
2156 if (gc_counter_less_than(old_marking_started_before,
2157 old_marking_completed_after)) {
2158 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2159 return true;
2160 }
2161
2162 if (old_marking_started_after != old_marking_completed_after) {
2163 // If there is an in-progress cycle (possibly started by us), then
2164 // wait for that cycle to complete, e.g.
2165 // while completed_now < started_after.
2166 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2167 MonitorLocker ml(G1OldGCCount_lock);
2168 while (gc_counter_less_than(_old_marking_cycles_completed,
2169 old_marking_started_after)) {
2170 ml.wait();
2171 }
2172 // Request is finished if the collection we just waited for was
2173 // started after this request.
2174 if (old_marking_started_before != old_marking_started_after) {
2175 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2176 return true;
2177 }
2178 }
2179
2180 // If VMOp was successful then it started a new cycle that the above
2181 // wait &etc should have recognized as finishing this request. This
2182 // differs from a non-user-request, where gc_succeeded does not imply
2183 // a new cycle was started.
2184 assert(!op.gc_succeeded(), "invariant");
2185
2186 if (op.cycle_already_in_progress()) {
2187 // If VMOp failed because a cycle was already in progress, it
2188 // is now complete. But it didn't finish this user-requested
2189 // GC, so try again.
2190 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2191 continue;
2192 } else if (op.whitebox_attached()) {
2193 // If WhiteBox wants control, wait for notification of a state
2194 // change in the controller, then try again. Don't wait for
2195 // release of control, since collections may complete while in
2196 // control. Note: This won't recognize a STW full collection
2197 // while waiting; we can't wait on multiple monitors.
2198 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2199 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2200 if (ConcurrentGCBreakpoints::is_controlled()) {
2201 ml.wait();
2202 }
2203 continue;
2204 }
2205 }
2206
2207 // Collection failed and should be retried.
2208 assert(op.transient_failure(), "invariant");
2209
2210 if (GCLocker::is_active_and_needs_gc()) {
2211 // If GCLocker is active, wait until clear before retrying.
2212 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2213 GCLocker::stall_until_clear();
2214 }
2215
2216 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2217 }
2218 }
2219
2220 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2221 assert_heap_not_locked();
2222
2223 // Lock to get consistent set of values.
2224 uint gc_count_before;
2225 uint full_gc_count_before;
2226 uint old_marking_started_before;
2227 {
2228 MutexLocker ml(Heap_lock);
2229 gc_count_before = total_collections();
2230 full_gc_count_before = total_full_collections();
2231 old_marking_started_before = _old_marking_cycles_started;
2232 }
2233
2234 if (should_do_concurrent_full_gc(cause)) {
2235 return try_collect_concurrently(cause,
2236 gc_count_before,
2237 old_marking_started_before);
2238 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2239 // Indicate failure to be consistent with VMOp failure due to
2240 // another collection slipping in after our gc_count but before
2241 // our request is processed.
2242 return false;
2243 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2244 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2245
2246 // Schedule a standard evacuation pause. We're setting word_size
2247 // to 0 which means that we are not requesting a post-GC allocation.
2248 VM_G1CollectForAllocation op(0, /* word_size */
2249 gc_count_before,
2250 cause,
2251 policy()->max_pause_time_ms());
2252 VMThread::execute(&op);
2253 return op.gc_succeeded();
2254 } else {
2255 // Schedule a Full GC.
2256 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2257 VMThread::execute(&op);
2258 return op.gc_succeeded();
2259 }
2260 }
2261
2262 bool G1CollectedHeap::is_in(const void* p) const {
2263 if (_hrm->reserved().contains(p)) {
2264 // Given that we know that p is in the reserved space,
2265 // heap_region_containing() should successfully
2266 // return the containing region.
2267 HeapRegion* hr = heap_region_containing(p);
2268 return hr->is_in(p);
2269 } else {
2270 return false;
2271 }
2272 }
2273
2274 #ifdef ASSERT
2275 bool G1CollectedHeap::is_in_exact(const void* p) const {
2276 bool contains = reserved_region().contains(p);
2277 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2278 if (contains && available) {
2279 return true;
2280 } else {
2281 return false;
2282 }
2283 }
2284 #endif
2285
2286 // Iteration functions.
2287
2288 // Iterates an ObjectClosure over all objects within a HeapRegion.
2289
2290 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2291 ObjectClosure* _cl;
2292 public:
2293 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2294 bool do_heap_region(HeapRegion* r) {
2295 if (!r->is_continues_humongous()) {
2296 r->object_iterate(_cl);
2297 }
2298 return false;
2299 }
2300 };
2301
2302 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2303 IterateObjectClosureRegionClosure blk(cl);
2304 heap_region_iterate(&blk);
2305 }
2306
2307 void G1CollectedHeap::keep_alive(oop obj) {
2308 G1BarrierSet::enqueue(obj);
2309 }
2310
2311 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2312 _hrm->iterate(cl);
2313 }
2314
2315 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2316 HeapRegionClaimer *hrclaimer,
2317 uint worker_id) const {
2318 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2319 }
2320
2321 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2322 HeapRegionClaimer *hrclaimer) const {
2323 _hrm->par_iterate(cl, hrclaimer, 0);
2324 }
2325
2326 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2327 _collection_set.iterate(cl);
2328 }
2329
2330 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2331 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2332 }
2333
2334 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2335 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2336 }
2337
2338 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2339 HeapRegion* hr = heap_region_containing(addr);
2340 return hr->block_start(addr);
2341 }
2342
2343 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2344 HeapRegion* hr = heap_region_containing(addr);
2345 return hr->block_is_obj(addr);
2346 }
2347
2348 bool G1CollectedHeap::supports_tlab_allocation() const {
2349 return true;
2350 }
2351
2352 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2353 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2354 }
2355
2356 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2357 return _eden.length() * HeapRegion::GrainBytes;
2358 }
2359
2360 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2361 // must be equal to the humongous object limit.
2362 size_t G1CollectedHeap::max_tlab_size() const {
2363 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2364 }
2365
2366 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2367 return _allocator->unsafe_max_tlab_alloc();
2368 }
2369
2370 size_t G1CollectedHeap::max_capacity() const {
2371 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2372 }
2373
2374 size_t G1CollectedHeap::max_reserved_capacity() const {
2375 return _hrm->max_length() * HeapRegion::GrainBytes;
2376 }
2377
2378 void G1CollectedHeap::deduplicate_string(oop str) {
2379 assert(java_lang_String::is_instance(str), "invariant");
2380
2381 if (G1StringDedup::is_enabled()) {
2382 G1StringDedup::deduplicate(str);
2383 }
2384 }
2385
2386 void G1CollectedHeap::prepare_for_verify() {
2387 _verifier->prepare_for_verify();
2388 }
2389
2390 void G1CollectedHeap::verify(VerifyOption vo) {
2391 _verifier->verify(vo);
2392 }
2393
2394 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2395 return true;
2396 }
2397
2398 bool G1CollectedHeap::is_heterogeneous_heap() const {
2399 return G1Arguments::is_heterogeneous_heap();
2400 }
2401
2402 class PrintRegionClosure: public HeapRegionClosure {
2403 outputStream* _st;
2404 public:
2405 PrintRegionClosure(outputStream* st) : _st(st) {}
2406 bool do_heap_region(HeapRegion* r) {
2407 r->print_on(_st);
2408 return false;
2409 }
2410 };
2411
2412 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2413 const HeapRegion* hr,
2414 const VerifyOption vo) const {
2415 switch (vo) {
2416 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2417 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2418 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2419 default: ShouldNotReachHere();
2420 }
2421 return false; // keep some compilers happy
2422 }
2423
2424 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2425 const VerifyOption vo) const {
2426 switch (vo) {
2427 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2428 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2429 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2430 default: ShouldNotReachHere();
2431 }
2432 return false; // keep some compilers happy
2433 }
2434
2435 void G1CollectedHeap::print_heap_regions() const {
2436 LogTarget(Trace, gc, heap, region) lt;
2437 if (lt.is_enabled()) {
2438 LogStream ls(lt);
2439 print_regions_on(&ls);
2440 }
2441 }
2442
2443 void G1CollectedHeap::print_on(outputStream* st) const {
2444 st->print(" %-20s", "garbage-first heap");
2445 if (_hrm != NULL) {
2446 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2447 capacity()/K, used_unlocked()/K);
2448 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2449 p2i(_hrm->reserved().start()),
2450 p2i(_hrm->reserved().end()));
2451 }
2452 st->cr();
2453 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2454 uint young_regions = young_regions_count();
2455 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2456 (size_t) young_regions * HeapRegion::GrainBytes / K);
2457 uint survivor_regions = survivor_regions_count();
2458 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2459 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2460 st->cr();
2461 if (_numa->is_enabled()) {
2462 uint num_nodes = _numa->num_active_nodes();
2463 st->print(" remaining free region(s) on each NUMA node: ");
2464 const int* node_ids = _numa->node_ids();
2465 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2466 uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0);
2467 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2468 }
2469 st->cr();
2470 }
2471 MetaspaceUtils::print_on(st);
2472 }
2473
2474 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2475 if (_hrm == NULL) {
2476 return;
2477 }
2478
2479 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2480 "HS=humongous(starts), HC=humongous(continues), "
2481 "CS=collection set, F=free, "
2482 "OA=open archive, CA=closed archive, "
2483 "TAMS=top-at-mark-start (previous, next)");
2484 PrintRegionClosure blk(st);
2485 heap_region_iterate(&blk);
2486 }
2487
2488 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2489 print_on(st);
2490
2491 // Print the per-region information.
2492 if (_hrm != NULL) {
2493 st->cr();
2494 print_regions_on(st);
2495 }
2496 }
2497
2498 void G1CollectedHeap::print_on_error(outputStream* st) const {
2499 this->CollectedHeap::print_on_error(st);
2500
2501 if (_cm != NULL) {
2502 st->cr();
2503 _cm->print_on_error(st);
2504 }
2505 }
2506
2507 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2508 workers()->threads_do(tc);
2509 tc->do_thread(_cm_thread);
2510 _cm->threads_do(tc);
2511 _cr->threads_do(tc);
2512 tc->do_thread(_young_gen_sampling_thread);
2513 if (G1StringDedup::is_enabled()) {
2514 G1StringDedup::threads_do(tc);
2515 }
2516 }
2517
2518 void G1CollectedHeap::print_tracing_info() const {
2519 rem_set()->print_summary_info();
2520 concurrent_mark()->print_summary_info();
2521 }
2522
2523 #ifndef PRODUCT
2524 // Helpful for debugging RSet issues.
2525
2526 class PrintRSetsClosure : public HeapRegionClosure {
2527 private:
2528 const char* _msg;
2529 size_t _occupied_sum;
2530
2531 public:
2532 bool do_heap_region(HeapRegion* r) {
2533 HeapRegionRemSet* hrrs = r->rem_set();
2534 size_t occupied = hrrs->occupied();
2535 _occupied_sum += occupied;
2536
2537 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2538 if (occupied == 0) {
2539 tty->print_cr(" RSet is empty");
2540 } else {
2541 hrrs->print();
2542 }
2543 tty->print_cr("----------");
2544 return false;
2545 }
2546
2547 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2548 tty->cr();
2549 tty->print_cr("========================================");
2550 tty->print_cr("%s", msg);
2551 tty->cr();
2552 }
2553
2554 ~PrintRSetsClosure() {
2555 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2556 tty->print_cr("========================================");
2557 tty->cr();
2558 }
2559 };
2560
2561 void G1CollectedHeap::print_cset_rsets() {
2562 PrintRSetsClosure cl("Printing CSet RSets");
2563 collection_set_iterate_all(&cl);
2564 }
2565
2566 void G1CollectedHeap::print_all_rsets() {
2567 PrintRSetsClosure cl("Printing All RSets");;
2568 heap_region_iterate(&cl);
2569 }
2570 #endif // PRODUCT
2571
2572 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2573 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2574 }
2575
2576 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2577
2578 size_t eden_used_bytes = _eden.used_bytes();
2579 size_t survivor_used_bytes = _survivor.used_bytes();
2580 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2581
2582 size_t eden_capacity_bytes =
2583 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2584
2585 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2586 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2587 eden_capacity_bytes, survivor_used_bytes, num_regions());
2588 }
2589
2590 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2591 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2592 stats->unused(), stats->used(), stats->region_end_waste(),
2593 stats->regions_filled(), stats->direct_allocated(),
2594 stats->failure_used(), stats->failure_waste());
2595 }
2596
2597 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2598 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2599 gc_tracer->report_gc_heap_summary(when, heap_summary);
2600
2601 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2602 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2603 }
2604
2605 void G1CollectedHeap::gc_prologue(bool full) {
2606 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2607
2608 // This summary needs to be printed before incrementing total collections.
2609 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2610
2611 // Update common counters.
2612 increment_total_collections(full /* full gc */);
2613 if (full || collector_state()->in_concurrent_start_gc()) {
2614 increment_old_marking_cycles_started();
2615 }
2616
2617 // Fill TLAB's and such
2618 {
2619 Ticks start = Ticks::now();
2620 ensure_parsability(true);
2621 Tickspan dt = Ticks::now() - start;
2622 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2623 }
2624
2625 if (!full) {
2626 // Flush dirty card queues to qset, so later phases don't need to account
2627 // for partially filled per-thread queues and such. Not needed for full
2628 // collections, which ignore those logs.
2629 Ticks start = Ticks::now();
2630 G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2631 Tickspan dt = Ticks::now() - start;
2632 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2633 }
2634 }
2635
2636 void G1CollectedHeap::gc_epilogue(bool full) {
2637 // Update common counters.
2638 if (full) {
2639 // Update the number of full collections that have been completed.
2640 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2641 }
2642
2643 // We are at the end of the GC. Total collections has already been increased.
2644 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2645
2646 // FIXME: what is this about?
2647 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2648 // is set.
2649 #if COMPILER2_OR_JVMCI
2650 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2651 #endif
2652
2653 double start = os::elapsedTime();
2654 resize_all_tlabs();
2655 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2656
2657 MemoryService::track_memory_usage();
2658 // We have just completed a GC. Update the soft reference
2659 // policy with the new heap occupancy
2660 Universe::update_heap_info_at_gc();
2661
2662 // Print NUMA statistics.
2663 _numa->print_statistics();
2664
2665 _collection_pause_end = Ticks::now();
2666 }
2667
2668 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2669 LogTarget(Trace, gc, heap, verify) lt;
2670
2671 if (lt.is_enabled()) {
2672 LogStream ls(lt);
2673 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2674 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2675 heap_region_iterate(&cl);
2676 }
2677 }
2678
2679 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2680 uint gc_count_before,
2681 bool* succeeded,
2682 GCCause::Cause gc_cause) {
2683 assert_heap_not_locked_and_not_at_safepoint();
2684 VM_G1CollectForAllocation op(word_size,
2685 gc_count_before,
2686 gc_cause,
2687 policy()->max_pause_time_ms());
2688 VMThread::execute(&op);
2689
2690 HeapWord* result = op.result();
2691 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2692 assert(result == NULL || ret_succeeded,
2693 "the result should be NULL if the VM did not succeed");
2694 *succeeded = ret_succeeded;
2695
2696 assert_heap_not_locked();
2697 return result;
2698 }
2699
2700 void G1CollectedHeap::do_concurrent_mark() {
2701 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2702 if (!_cm_thread->in_progress()) {
2703 _cm_thread->set_started();
2704 CGC_lock->notify();
2705 }
2706 }
2707
2708 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2709 // We don't nominate objects with many remembered set entries, on
2710 // the assumption that such objects are likely still live.
2711 HeapRegionRemSet* rem_set = r->rem_set();
2712
2713 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2714 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2715 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2716 }
2717
2718 #ifndef PRODUCT
2719 void G1CollectedHeap::verify_region_attr_remset_update() {
2720 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2721 public:
2722 virtual bool do_heap_region(HeapRegion* r) {
2723 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2724 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2725 assert(r->rem_set()->is_tracked() == needs_remset_update,
2726 "Region %u remset tracking status (%s) different to region attribute (%s)",
2727 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2728 return false;
2729 }
2730 } cl;
2731 heap_region_iterate(&cl);
2732 }
2733 #endif
2734
2735 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2736 public:
2737 bool do_heap_region(HeapRegion* hr) {
2738 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2739 hr->verify_rem_set();
2740 }
2741 return false;
2742 }
2743 };
2744
2745 uint G1CollectedHeap::num_task_queues() const {
2746 return _task_queues->size();
2747 }
2748
2749 #if TASKQUEUE_STATS
2750 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2751 st->print_raw_cr("GC Task Stats");
2752 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2753 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2754 }
2755
2756 void G1CollectedHeap::print_taskqueue_stats() const {
2757 if (!log_is_enabled(Trace, gc, task, stats)) {
2758 return;
2759 }
2760 Log(gc, task, stats) log;
2761 ResourceMark rm;
2762 LogStream ls(log.trace());
2763 outputStream* st = &ls;
2764
2765 print_taskqueue_stats_hdr(st);
2766
2767 TaskQueueStats totals;
2768 const uint n = num_task_queues();
2769 for (uint i = 0; i < n; ++i) {
2770 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2771 totals += task_queue(i)->stats;
2772 }
2773 st->print_raw("tot "); totals.print(st); st->cr();
2774
2775 DEBUG_ONLY(totals.verify());
2776 }
2777
2778 void G1CollectedHeap::reset_taskqueue_stats() {
2779 const uint n = num_task_queues();
2780 for (uint i = 0; i < n; ++i) {
2781 task_queue(i)->stats.reset();
2782 }
2783 }
2784 #endif // TASKQUEUE_STATS
2785
2786 void G1CollectedHeap::wait_for_root_region_scanning() {
2787 double scan_wait_start = os::elapsedTime();
2788 // We have to wait until the CM threads finish scanning the
2789 // root regions as it's the only way to ensure that all the
2790 // objects on them have been correctly scanned before we start
2791 // moving them during the GC.
2792 bool waited = _cm->root_regions()->wait_until_scan_finished();
2793 double wait_time_ms = 0.0;
2794 if (waited) {
2795 double scan_wait_end = os::elapsedTime();
2796 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2797 }
2798 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2799 }
2800
2801 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2802 private:
2803 G1HRPrinter* _hr_printer;
2804 public:
2805 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2806
2807 virtual bool do_heap_region(HeapRegion* r) {
2808 _hr_printer->cset(r);
2809 return false;
2810 }
2811 };
2812
2813 void G1CollectedHeap::start_new_collection_set() {
2814 double start = os::elapsedTime();
2815
2816 collection_set()->start_incremental_building();
2817
2818 clear_region_attr();
2819
2820 guarantee(_eden.length() == 0, "eden should have been cleared");
2821 policy()->transfer_survivors_to_cset(survivor());
2822
2823 // We redo the verification but now wrt to the new CSet which
2824 // has just got initialized after the previous CSet was freed.
2825 _cm->verify_no_collection_set_oops();
2826
2827 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2828 }
2829
2830 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2831
2832 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2833 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2834 collection_set()->optional_region_length());
2835
2836 _cm->verify_no_collection_set_oops();
2837
2838 if (_hr_printer.is_active()) {
2839 G1PrintCollectionSetClosure cl(&_hr_printer);
2840 _collection_set.iterate(&cl);
2841 _collection_set.iterate_optional(&cl);
2842 }
2843 }
2844
2845 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2846 if (collector_state()->in_concurrent_start_gc()) {
2847 return G1HeapVerifier::G1VerifyConcurrentStart;
2848 } else if (collector_state()->in_young_only_phase()) {
2849 return G1HeapVerifier::G1VerifyYoungNormal;
2850 } else {
2851 return G1HeapVerifier::G1VerifyMixed;
2852 }
2853 }
2854
2855 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2856 if (VerifyRememberedSets) {
2857 log_info(gc, verify)("[Verifying RemSets before GC]");
2858 VerifyRegionRemSetClosure v_cl;
2859 heap_region_iterate(&v_cl);
2860 }
2861 _verifier->verify_before_gc(type);
2862 _verifier->check_bitmaps("GC Start");
2863 verify_numa_regions("GC Start");
2864 }
2865
2866 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2867 if (VerifyRememberedSets) {
2868 log_info(gc, verify)("[Verifying RemSets after GC]");
2869 VerifyRegionRemSetClosure v_cl;
2870 heap_region_iterate(&v_cl);
2871 }
2872 _verifier->verify_after_gc(type);
2873 _verifier->check_bitmaps("GC End");
2874 verify_numa_regions("GC End");
2875 }
2876
2877 void G1CollectedHeap::expand_heap_after_young_collection(){
2878 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2879 if (expand_bytes > 0) {
2880 // No need for an ergo logging here,
2881 // expansion_amount() does this when it returns a value > 0.
2882 double expand_ms;
2883 if (!expand(expand_bytes, _workers, &expand_ms)) {
2884 // We failed to expand the heap. Cannot do anything about it.
2885 }
2886 phase_times()->record_expand_heap_time(expand_ms);
2887 }
2888 }
2889
2890 const char* G1CollectedHeap::young_gc_name() const {
2891 if (collector_state()->in_concurrent_start_gc()) {
2892 return "Pause Young (Concurrent Start)";
2893 } else if (collector_state()->in_young_only_phase()) {
2894 if (collector_state()->in_young_gc_before_mixed()) {
2895 return "Pause Young (Prepare Mixed)";
2896 } else {
2897 return "Pause Young (Normal)";
2898 }
2899 } else {
2900 return "Pause Young (Mixed)";
2901 }
2902 }
2903
2904 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2905 assert_at_safepoint_on_vm_thread();
2906 guarantee(!is_gc_active(), "collection is not reentrant");
2907
2908 if (GCLocker::check_active_before_gc()) {
2909 return false;
2910 }
2911
2912 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2913 if (should_upgrade_to_full_gc(gc_cause())) {
2914 log_info(gc, ergo)("Attempting maximally compacting collection");
2915 bool result = do_full_collection(false /* explicit gc */,
2916 true /* clear_all_soft_refs */);
2917 // do_full_collection only fails if blocked by GC locker, but
2918 // we've already checked for that above.
2919 assert(result, "invariant");
2920 }
2921 return true;
2922 }
2923
2924 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2925 GCIdMark gc_id_mark;
2926
2927 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2928 ResourceMark rm;
2929
2930 policy()->note_gc_start();
2931
2932 _gc_timer_stw->register_gc_start();
2933 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2934
2935 wait_for_root_region_scanning();
2936
2937 print_heap_before_gc();
2938 print_heap_regions();
2939 trace_heap_before_gc(_gc_tracer_stw);
2940
2941 _verifier->verify_region_sets_optional();
2942 _verifier->verify_dirty_young_regions();
2943
2944 // We should not be doing concurrent start unless the concurrent mark thread is running
2945 if (!_cm_thread->should_terminate()) {
2946 // This call will decide whether this pause is a concurrent start
2947 // pause. If it is, in_concurrent_start_gc() will return true
2948 // for the duration of this pause.
2949 policy()->decide_on_conc_mark_initiation();
2950 }
2951
2952 // We do not allow concurrent start to be piggy-backed on a mixed GC.
2953 assert(!collector_state()->in_concurrent_start_gc() ||
2954 collector_state()->in_young_only_phase(), "sanity");
2955 // We also do not allow mixed GCs during marking.
2956 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2957
2958 // Record whether this pause is a concurrent start. When the current
2959 // thread has completed its logging output and it's safe to signal
2960 // the CM thread, the flag's value in the policy has been reset.
2961 bool should_start_conc_mark = collector_state()->in_concurrent_start_gc();
2962 if (should_start_conc_mark) {
2963 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2964 }
2965
2966 // Inner scope for scope based logging, timers, and stats collection
2967 {
2968 G1EvacuationInfo evacuation_info;
2969
2970 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2971
2972 GCTraceCPUTime tcpu;
2973
2974 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
2975
2976 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2977 workers()->active_workers(),
2978 Threads::number_of_non_daemon_threads());
2979 active_workers = workers()->update_active_workers(active_workers);
2980 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2981
2982 G1MonitoringScope ms(g1mm(),
2983 false /* full_gc */,
2984 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2985
2986 G1HeapTransition heap_transition(this);
2987
2988 {
2989 IsGCActiveMark x;
2990
2991 gc_prologue(false);
2992
2993 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
2994 verify_before_young_collection(verify_type);
2995
2996 {
2997 // The elapsed time induced by the start time below deliberately elides
2998 // the possible verification above.
2999 double sample_start_time_sec = os::elapsedTime();
3000
3001 // Please see comment in g1CollectedHeap.hpp and
3002 // G1CollectedHeap::ref_processing_init() to see how
3003 // reference processing currently works in G1.
3004 _ref_processor_stw->enable_discovery();
3005
3006 // We want to temporarily turn off discovery by the
3007 // CM ref processor, if necessary, and turn it back on
3008 // on again later if we do. Using a scoped
3009 // NoRefDiscovery object will do this.
3010 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3011
3012 policy()->record_collection_pause_start(sample_start_time_sec);
3013
3014 // Forget the current allocation region (we might even choose it to be part
3015 // of the collection set!).
3016 _allocator->release_mutator_alloc_regions();
3017
3018 calculate_collection_set(evacuation_info, target_pause_time_ms);
3019
3020 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3021 G1ParScanThreadStateSet per_thread_states(this,
3022 &rdcqs,
3023 workers()->active_workers(),
3024 collection_set()->young_region_length(),
3025 collection_set()->optional_region_length());
3026 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3027
3028 // Actually do the work...
3029 evacuate_initial_collection_set(&per_thread_states);
3030
3031 if (_collection_set.optional_region_length() != 0) {
3032 evacuate_optional_collection_set(&per_thread_states);
3033 }
3034 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3035
3036 start_new_collection_set();
3037
3038 _survivor_evac_stats.adjust_desired_plab_sz();
3039 _old_evac_stats.adjust_desired_plab_sz();
3040
3041 if (should_start_conc_mark) {
3042 // We have to do this before we notify the CM threads that
3043 // they can start working to make sure that all the
3044 // appropriate initialization is done on the CM object.
3045 concurrent_mark()->post_concurrent_start();
3046 // Note that we don't actually trigger the CM thread at
3047 // this point. We do that later when we're sure that
3048 // the current thread has completed its logging output.
3049 }
3050
3051 allocate_dummy_regions();
3052
3053 _allocator->init_mutator_alloc_regions();
3054
3055 expand_heap_after_young_collection();
3056
3057 double sample_end_time_sec = os::elapsedTime();
3058 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3059 policy()->record_collection_pause_end(pause_time_ms);
3060 }
3061
3062 verify_after_young_collection(verify_type);
3063
3064 gc_epilogue(false);
3065 }
3066
3067 // Print the remainder of the GC log output.
3068 if (evacuation_failed()) {
3069 log_info(gc)("To-space exhausted");
3070 }
3071
3072 policy()->print_phases();
3073 heap_transition.print();
3074
3075 _hrm->verify_optional();
3076 _verifier->verify_region_sets_optional();
3077
3078 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3079 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3080
3081 print_heap_after_gc();
3082 print_heap_regions();
3083 trace_heap_after_gc(_gc_tracer_stw);
3084
3085 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3086 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3087 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3088 // before any GC notifications are raised.
3089 g1mm()->update_sizes();
3090
3091 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3092 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3093 _gc_timer_stw->register_gc_end();
3094 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3095 }
3096 // It should now be safe to tell the concurrent mark thread to start
3097 // without its logging output interfering with the logging output
3098 // that came from the pause.
3099
3100 if (should_start_conc_mark) {
3101 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3102 // thread(s) could be running concurrently with us. Make sure that anything
3103 // after this point does not assume that we are the only GC thread running.
3104 // Note: of course, the actual marking work will not start until the safepoint
3105 // itself is released in SuspendibleThreadSet::desynchronize().
3106 do_concurrent_mark();
3107 ConcurrentGCBreakpoints::notify_idle_to_active();
3108 }
3109 }
3110
3111 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3112 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3113 workers()->run_task(&rsfp_task);
3114 }
3115
3116 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3117 double remove_self_forwards_start = os::elapsedTime();
3118
3119 remove_self_forwarding_pointers(rdcqs);
3120 _preserved_marks_set.restore(workers());
3121
3122 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3123 }
3124
3125 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3126 if (!_evacuation_failed) {
3127 _evacuation_failed = true;
3128 }
3129
3130 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3131 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3132 }
3133
3134 bool G1ParEvacuateFollowersClosure::offer_termination() {
3135 EventGCPhaseParallel event;
3136 G1ParScanThreadState* const pss = par_scan_state();
3137 start_term_time();
3138 const bool res = terminator()->offer_termination();
3139 end_term_time();
3140 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3141 return res;
3142 }
3143
3144 void G1ParEvacuateFollowersClosure::do_void() {
3145 EventGCPhaseParallel event;
3146 G1ParScanThreadState* const pss = par_scan_state();
3147 pss->trim_queue();
3148 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3149 do {
3150 EventGCPhaseParallel event;
3151 pss->steal_and_trim_queue(queues());
3152 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3153 } while (!offer_termination());
3154 }
3155
3156 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3157 bool class_unloading_occurred) {
3158 uint num_workers = workers()->active_workers();
3159 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3160 workers()->run_task(&unlink_task);
3161 }
3162
3163 // Clean string dedup data structures.
3164 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3165 // record the durations of the phases. Hence the almost-copy.
3166 class G1StringDedupCleaningTask : public AbstractGangTask {
3167 BoolObjectClosure* _is_alive;
3168 OopClosure* _keep_alive;
3169 G1GCPhaseTimes* _phase_times;
3170
3171 public:
3172 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3173 OopClosure* keep_alive,
3174 G1GCPhaseTimes* phase_times) :
3175 AbstractGangTask("Partial Cleaning Task"),
3176 _is_alive(is_alive),
3177 _keep_alive(keep_alive),
3178 _phase_times(phase_times)
3179 {
3180 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3181 StringDedup::gc_prologue(true);
3182 }
3183
3184 ~G1StringDedupCleaningTask() {
3185 StringDedup::gc_epilogue();
3186 }
3187
3188 void work(uint worker_id) {
3189 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3190 {
3191 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3192 StringDedupQueue::unlink_or_oops_do(&cl);
3193 }
3194 {
3195 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3196 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3197 }
3198 }
3199 };
3200
3201 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3202 OopClosure* keep_alive,
3203 G1GCPhaseTimes* phase_times) {
3204 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3205 workers()->run_task(&cl);
3206 }
3207
3208 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3209 private:
3210 G1RedirtyCardsQueueSet* _qset;
3211 G1CollectedHeap* _g1h;
3212 BufferNode* volatile _nodes;
3213
3214 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3215 size_t buffer_size = _qset->buffer_size();
3216 BufferNode* next = Atomic::load(&_nodes);
3217 while (next != NULL) {
3218 BufferNode* node = next;
3219 next = Atomic::cmpxchg(&_nodes, node, node->next());
3220 if (next == node) {
3221 cl->apply_to_buffer(node, buffer_size, worker_id);
3222 next = node->next();
3223 }
3224 }
3225 }
3226
3227 public:
3228 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3229 AbstractGangTask("Redirty Cards"),
3230 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3231
3232 virtual void work(uint worker_id) {
3233 G1GCPhaseTimes* p = _g1h->phase_times();
3234 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3235
3236 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3237 par_apply(&cl, worker_id);
3238
3239 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3240 }
3241 };
3242
3243 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3244 double redirty_logged_cards_start = os::elapsedTime();
3245
3246 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3247 workers()->run_task(&redirty_task);
3248
3249 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3250 dcq.merge_bufferlists(rdcqs);
3251
3252 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3253 }
3254
3255 // Weak Reference Processing support
3256
3257 bool G1STWIsAliveClosure::do_object_b(oop p) {
3258 // An object is reachable if it is outside the collection set,
3259 // or is inside and copied.
3260 return !_g1h->is_in_cset(p) || p->is_forwarded();
3261 }
3262
3263 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3264 assert(obj != NULL, "must not be NULL");
3265 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3266 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3267 // may falsely indicate that this is not the case here: however the collection set only
3268 // contains old regions when concurrent mark is not running.
3269 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3270 }
3271
3272 // Non Copying Keep Alive closure
3273 class G1KeepAliveClosure: public OopClosure {
3274 G1CollectedHeap*_g1h;
3275 public:
3276 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3277 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3278 void do_oop(oop* p) {
3279 oop obj = *p;
3280 assert(obj != NULL, "the caller should have filtered out NULL values");
3281
3282 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3283 if (!region_attr.is_in_cset_or_humongous()) {
3284 return;
3285 }
3286 if (region_attr.is_in_cset()) {
3287 assert( obj->is_forwarded(), "invariant" );
3288 *p = obj->forwardee();
3289 } else {
3290 assert(!obj->is_forwarded(), "invariant" );
3291 assert(region_attr.is_humongous(),
3292 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3293 _g1h->set_humongous_is_live(obj);
3294 }
3295 }
3296 };
3297
3298 // Copying Keep Alive closure - can be called from both
3299 // serial and parallel code as long as different worker
3300 // threads utilize different G1ParScanThreadState instances
3301 // and different queues.
3302
3303 class G1CopyingKeepAliveClosure: public OopClosure {
3304 G1CollectedHeap* _g1h;
3305 G1ParScanThreadState* _par_scan_state;
3306
3307 public:
3308 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3309 G1ParScanThreadState* pss):
3310 _g1h(g1h),
3311 _par_scan_state(pss)
3312 {}
3313
3314 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3315 virtual void do_oop( oop* p) { do_oop_work(p); }
3316
3317 template <class T> void do_oop_work(T* p) {
3318 oop obj = RawAccess<>::oop_load(p);
3319
3320 if (_g1h->is_in_cset_or_humongous(obj)) {
3321 // If the referent object has been forwarded (either copied
3322 // to a new location or to itself in the event of an
3323 // evacuation failure) then we need to update the reference
3324 // field and, if both reference and referent are in the G1
3325 // heap, update the RSet for the referent.
3326 //
3327 // If the referent has not been forwarded then we have to keep
3328 // it alive by policy. Therefore we have copy the referent.
3329 //
3330 // When the queue is drained (after each phase of reference processing)
3331 // the object and it's followers will be copied, the reference field set
3332 // to point to the new location, and the RSet updated.
3333 _par_scan_state->push_on_queue(ScannerTask(p));
3334 }
3335 }
3336 };
3337
3338 // Serial drain queue closure. Called as the 'complete_gc'
3339 // closure for each discovered list in some of the
3340 // reference processing phases.
3341
3342 class G1STWDrainQueueClosure: public VoidClosure {
3343 protected:
3344 G1CollectedHeap* _g1h;
3345 G1ParScanThreadState* _par_scan_state;
3346
3347 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3348
3349 public:
3350 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3351 _g1h(g1h),
3352 _par_scan_state(pss)
3353 { }
3354
3355 void do_void() {
3356 G1ParScanThreadState* const pss = par_scan_state();
3357 pss->trim_queue();
3358 }
3359 };
3360
3361 // Parallel Reference Processing closures
3362
3363 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3364 // processing during G1 evacuation pauses.
3365
3366 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3367 private:
3368 G1CollectedHeap* _g1h;
3369 G1ParScanThreadStateSet* _pss;
3370 G1ScannerTasksQueueSet* _queues;
3371 WorkGang* _workers;
3372
3373 public:
3374 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3375 G1ParScanThreadStateSet* per_thread_states,
3376 WorkGang* workers,
3377 G1ScannerTasksQueueSet *task_queues) :
3378 _g1h(g1h),
3379 _pss(per_thread_states),
3380 _queues(task_queues),
3381 _workers(workers)
3382 {
3383 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3384 }
3385
3386 // Executes the given task using concurrent marking worker threads.
3387 virtual void execute(ProcessTask& task, uint ergo_workers);
3388 };
3389
3390 // Gang task for possibly parallel reference processing
3391
3392 class G1STWRefProcTaskProxy: public AbstractGangTask {
3393 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3394 ProcessTask& _proc_task;
3395 G1CollectedHeap* _g1h;
3396 G1ParScanThreadStateSet* _pss;
3397 G1ScannerTasksQueueSet* _task_queues;
3398 TaskTerminator* _terminator;
3399
3400 public:
3401 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3402 G1CollectedHeap* g1h,
3403 G1ParScanThreadStateSet* per_thread_states,
3404 G1ScannerTasksQueueSet *task_queues,
3405 TaskTerminator* terminator) :
3406 AbstractGangTask("Process reference objects in parallel"),
3407 _proc_task(proc_task),
3408 _g1h(g1h),
3409 _pss(per_thread_states),
3410 _task_queues(task_queues),
3411 _terminator(terminator)
3412 {}
3413
3414 virtual void work(uint worker_id) {
3415 // The reference processing task executed by a single worker.
3416 ResourceMark rm;
3417
3418 G1STWIsAliveClosure is_alive(_g1h);
3419
3420 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3421 pss->set_ref_discoverer(NULL);
3422
3423 // Keep alive closure.
3424 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3425
3426 // Complete GC closure
3427 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3428
3429 // Call the reference processing task's work routine.
3430 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3431
3432 // Note we cannot assert that the refs array is empty here as not all
3433 // of the processing tasks (specifically phase2 - pp2_work) execute
3434 // the complete_gc closure (which ordinarily would drain the queue) so
3435 // the queue may not be empty.
3436 }
3437 };
3438
3439 // Driver routine for parallel reference processing.
3440 // Creates an instance of the ref processing gang
3441 // task and has the worker threads execute it.
3442 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3443 assert(_workers != NULL, "Need parallel worker threads.");
3444
3445 assert(_workers->active_workers() >= ergo_workers,
3446 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3447 ergo_workers, _workers->active_workers());
3448 TaskTerminator terminator(ergo_workers, _queues);
3449 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3450
3451 _workers->run_task(&proc_task_proxy, ergo_workers);
3452 }
3453
3454 // End of weak reference support closures
3455
3456 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3457 double ref_proc_start = os::elapsedTime();
3458
3459 ReferenceProcessor* rp = _ref_processor_stw;
3460 assert(rp->discovery_enabled(), "should have been enabled");
3461
3462 // Closure to test whether a referent is alive.
3463 G1STWIsAliveClosure is_alive(this);
3464
3465 // Even when parallel reference processing is enabled, the processing
3466 // of JNI refs is serial and performed serially by the current thread
3467 // rather than by a worker. The following PSS will be used for processing
3468 // JNI refs.
3469
3470 // Use only a single queue for this PSS.
3471 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3472 pss->set_ref_discoverer(NULL);
3473 assert(pss->queue_is_empty(), "pre-condition");
3474
3475 // Keep alive closure.
3476 G1CopyingKeepAliveClosure keep_alive(this, pss);
3477
3478 // Serial Complete GC closure
3479 G1STWDrainQueueClosure drain_queue(this, pss);
3480
3481 // Setup the soft refs policy...
3482 rp->setup_policy(false);
3483
3484 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3485
3486 ReferenceProcessorStats stats;
3487 if (!rp->processing_is_mt()) {
3488 // Serial reference processing...
3489 stats = rp->process_discovered_references(&is_alive,
3490 &keep_alive,
3491 &drain_queue,
3492 NULL,
3493 pt);
3494 } else {
3495 uint no_of_gc_workers = workers()->active_workers();
3496
3497 // Parallel reference processing
3498 assert(no_of_gc_workers <= rp->max_num_queues(),
3499 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3500 no_of_gc_workers, rp->max_num_queues());
3501
3502 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3503 stats = rp->process_discovered_references(&is_alive,
3504 &keep_alive,
3505 &drain_queue,
3506 &par_task_executor,
3507 pt);
3508 }
3509
3510 _gc_tracer_stw->report_gc_reference_stats(stats);
3511
3512 // We have completed copying any necessary live referent objects.
3513 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3514
3515 make_pending_list_reachable();
3516
3517 assert(!rp->discovery_enabled(), "Postcondition");
3518 rp->verify_no_references_recorded();
3519
3520 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3521 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3522 }
3523
3524 void G1CollectedHeap::make_pending_list_reachable() {
3525 if (collector_state()->in_concurrent_start_gc()) {
3526 oop pll_head = Universe::reference_pending_list();
3527 if (pll_head != NULL) {
3528 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3529 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3530 }
3531 }
3532 }
3533
3534 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3535 Ticks start = Ticks::now();
3536 per_thread_states->flush();
3537 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3538 }
3539
3540 class G1PrepareEvacuationTask : public AbstractGangTask {
3541 class G1PrepareRegionsClosure : public HeapRegionClosure {
3542 G1CollectedHeap* _g1h;
3543 G1PrepareEvacuationTask* _parent_task;
3544 size_t _worker_humongous_total;
3545 size_t _worker_humongous_candidates;
3546
3547 bool humongous_region_is_candidate(HeapRegion* region) const {
3548 assert(region->is_starts_humongous(), "Must start a humongous object");
3549
3550 oop obj = oop(region->bottom());
3551
3552 // Dead objects cannot be eager reclaim candidates. Due to class
3553 // unloading it is unsafe to query their classes so we return early.
3554 if (_g1h->is_obj_dead(obj, region)) {
3555 return false;
3556 }
3557
3558 // If we do not have a complete remembered set for the region, then we can
3559 // not be sure that we have all references to it.
3560 if (!region->rem_set()->is_complete()) {
3561 return false;
3562 }
3563 // Candidate selection must satisfy the following constraints
3564 // while concurrent marking is in progress:
3565 //
3566 // * In order to maintain SATB invariants, an object must not be
3567 // reclaimed if it was allocated before the start of marking and
3568 // has not had its references scanned. Such an object must have
3569 // its references (including type metadata) scanned to ensure no
3570 // live objects are missed by the marking process. Objects
3571 // allocated after the start of concurrent marking don't need to
3572 // be scanned.
3573 //
3574 // * An object must not be reclaimed if it is on the concurrent
3575 // mark stack. Objects allocated after the start of concurrent
3576 // marking are never pushed on the mark stack.
3577 //
3578 // Nominating only objects allocated after the start of concurrent
3579 // marking is sufficient to meet both constraints. This may miss
3580 // some objects that satisfy the constraints, but the marking data
3581 // structures don't support efficiently performing the needed
3582 // additional tests or scrubbing of the mark stack.
3583 //
3584 // However, we presently only nominate is_typeArray() objects.
3585 // A humongous object containing references induces remembered
3586 // set entries on other regions. In order to reclaim such an
3587 // object, those remembered sets would need to be cleaned up.
3588 //
3589 // We also treat is_typeArray() objects specially, allowing them
3590 // to be reclaimed even if allocated before the start of
3591 // concurrent mark. For this we rely on mark stack insertion to
3592 // exclude is_typeArray() objects, preventing reclaiming an object
3593 // that is in the mark stack. We also rely on the metadata for
3594 // such objects to be built-in and so ensured to be kept live.
3595 // Frequent allocation and drop of large binary blobs is an
3596 // important use case for eager reclaim, and this special handling
3597 // may reduce needed headroom.
3598
3599 return obj->is_typeArray() &&
3600 _g1h->is_potential_eager_reclaim_candidate(region);
3601 }
3602
3603 public:
3604 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3605 _g1h(g1h),
3606 _parent_task(parent_task),
3607 _worker_humongous_total(0),
3608 _worker_humongous_candidates(0) { }
3609
3610 ~G1PrepareRegionsClosure() {
3611 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3612 _parent_task->add_humongous_total(_worker_humongous_total);
3613 }
3614
3615 virtual bool do_heap_region(HeapRegion* hr) {
3616 // First prepare the region for scanning
3617 _g1h->rem_set()->prepare_region_for_scan(hr);
3618
3619 // Now check if region is a humongous candidate
3620 if (!hr->is_starts_humongous()) {
3621 _g1h->register_region_with_region_attr(hr);
3622 return false;
3623 }
3624
3625 uint index = hr->hrm_index();
3626 if (humongous_region_is_candidate(hr)) {
3627 _g1h->set_humongous_reclaim_candidate(index, true);
3628 _g1h->register_humongous_region_with_region_attr(index);
3629 _worker_humongous_candidates++;
3630 // We will later handle the remembered sets of these regions.
3631 } else {
3632 _g1h->set_humongous_reclaim_candidate(index, false);
3633 _g1h->register_region_with_region_attr(hr);
3634 }
3635 _worker_humongous_total++;
3636
3637 return false;
3638 }
3639 };
3640
3641 G1CollectedHeap* _g1h;
3642 HeapRegionClaimer _claimer;
3643 volatile size_t _humongous_total;
3644 volatile size_t _humongous_candidates;
3645 public:
3646 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3647 AbstractGangTask("Prepare Evacuation"),
3648 _g1h(g1h),
3649 _claimer(_g1h->workers()->active_workers()),
3650 _humongous_total(0),
3651 _humongous_candidates(0) { }
3652
3653 ~G1PrepareEvacuationTask() {
3654 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3655 }
3656
3657 void work(uint worker_id) {
3658 G1PrepareRegionsClosure cl(_g1h, this);
3659 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3660 }
3661
3662 void add_humongous_candidates(size_t candidates) {
3663 Atomic::add(&_humongous_candidates, candidates);
3664 }
3665
3666 void add_humongous_total(size_t total) {
3667 Atomic::add(&_humongous_total, total);
3668 }
3669
3670 size_t humongous_candidates() {
3671 return _humongous_candidates;
3672 }
3673
3674 size_t humongous_total() {
3675 return _humongous_total;
3676 }
3677 };
3678
3679 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3680 _bytes_used_during_gc = 0;
3681
3682 _expand_heap_after_alloc_failure = true;
3683 _evacuation_failed = false;
3684
3685 // Disable the hot card cache.
3686 _hot_card_cache->reset_hot_cache_claimed_index();
3687 _hot_card_cache->set_use_cache(false);
3688
3689 // Initialize the GC alloc regions.
3690 _allocator->init_gc_alloc_regions(evacuation_info);
3691
3692 {
3693 Ticks start = Ticks::now();
3694 rem_set()->prepare_for_scan_heap_roots();
3695 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3696 }
3697
3698 {
3699 G1PrepareEvacuationTask g1_prep_task(this);
3700 Tickspan task_time = run_task(&g1_prep_task);
3701
3702 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3703 g1_prep_task.humongous_total(),
3704 g1_prep_task.humongous_candidates());
3705 }
3706
3707 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3708 _preserved_marks_set.assert_empty();
3709
3710 #if COMPILER2_OR_JVMCI
3711 DerivedPointerTable::clear();
3712 #endif
3713
3714 // Concurrent start needs claim bits to keep track of the marked-through CLDs.
3715 if (collector_state()->in_concurrent_start_gc()) {
3716 concurrent_mark()->pre_concurrent_start();
3717
3718 double start_clear_claimed_marks = os::elapsedTime();
3719
3720 ClassLoaderDataGraph::clear_claimed_marks();
3721
3722 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3723 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3724 }
3725
3726 // Should G1EvacuationFailureALot be in effect for this GC?
3727 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3728 }
3729
3730 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3731 protected:
3732 G1CollectedHeap* _g1h;
3733 G1ParScanThreadStateSet* _per_thread_states;
3734 G1ScannerTasksQueueSet* _task_queues;
3735 TaskTerminator _terminator;
3736 uint _num_workers;
3737
3738 void evacuate_live_objects(G1ParScanThreadState* pss,
3739 uint worker_id,
3740 G1GCPhaseTimes::GCParPhases objcopy_phase,
3741 G1GCPhaseTimes::GCParPhases termination_phase) {
3742 G1GCPhaseTimes* p = _g1h->phase_times();
3743
3744 Ticks start = Ticks::now();
3745 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3746 cl.do_void();
3747
3748 assert(pss->queue_is_empty(), "should be empty");
3749
3750 Tickspan evac_time = (Ticks::now() - start);
3751 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3752
3753 if (termination_phase == G1GCPhaseTimes::Termination) {
3754 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3755 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3756 } else {
3757 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3758 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3759 }
3760 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3761 }
3762
3763 virtual void start_work(uint worker_id) { }
3764
3765 virtual void end_work(uint worker_id) { }
3766
3767 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3768
3769 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3770
3771 public:
3772 G1EvacuateRegionsBaseTask(const char* name,
3773 G1ParScanThreadStateSet* per_thread_states,
3774 G1ScannerTasksQueueSet* task_queues,
3775 uint num_workers) :
3776 AbstractGangTask(name),
3777 _g1h(G1CollectedHeap::heap()),
3778 _per_thread_states(per_thread_states),
3779 _task_queues(task_queues),
3780 _terminator(num_workers, _task_queues),
3781 _num_workers(num_workers)
3782 { }
3783
3784 void work(uint worker_id) {
3785 start_work(worker_id);
3786
3787 {
3788 ResourceMark rm;
3789
3790 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3791 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3792
3793 scan_roots(pss, worker_id);
3794 evacuate_live_objects(pss, worker_id);
3795 }
3796
3797 end_work(worker_id);
3798 }
3799 };
3800
3801 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3802 G1RootProcessor* _root_processor;
3803
3804 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3805 _root_processor->evacuate_roots(pss, worker_id);
3806 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3807 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3808 }
3809
3810 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3811 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3812 }
3813
3814 void start_work(uint worker_id) {
3815 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3816 }
3817
3818 void end_work(uint worker_id) {
3819 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3820 }
3821
3822 public:
3823 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3824 G1ParScanThreadStateSet* per_thread_states,
3825 G1ScannerTasksQueueSet* task_queues,
3826 G1RootProcessor* root_processor,
3827 uint num_workers) :
3828 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3829 _root_processor(root_processor)
3830 { }
3831 };
3832
3833 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3834 G1GCPhaseTimes* p = phase_times();
3835
3836 {
3837 Ticks start = Ticks::now();
3838 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3839 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3840 }
3841
3842 Tickspan task_time;
3843 const uint num_workers = workers()->active_workers();
3844
3845 Ticks start_processing = Ticks::now();
3846 {
3847 G1RootProcessor root_processor(this, num_workers);
3848 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3849 task_time = run_task(&g1_par_task);
3850 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3851 // To extract its code root fixup time we measure total time of this scope and
3852 // subtract from the time the WorkGang task took.
3853 }
3854 Tickspan total_processing = Ticks::now() - start_processing;
3855
3856 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3857 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3858 }
3859
3860 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3861
3862 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3863 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3864 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3865 }
3866
3867 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3868 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3869 }
3870
3871 public:
3872 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3873 G1ScannerTasksQueueSet* queues,
3874 uint num_workers) :
3875 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3876 }
3877 };
3878
3879 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3880 class G1MarkScope : public MarkScope { };
3881
3882 Tickspan task_time;
3883
3884 Ticks start_processing = Ticks::now();
3885 {
3886 G1MarkScope code_mark_scope;
3887 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3888 task_time = run_task(&task);
3889 // See comment in evacuate_collection_set() for the reason of the scope.
3890 }
3891 Tickspan total_processing = Ticks::now() - start_processing;
3892
3893 G1GCPhaseTimes* p = phase_times();
3894 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3895 }
3896
3897 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3898 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3899
3900 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3901
3902 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3903 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3904
3905 if (time_left_ms < 0 ||
3906 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3907 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3908 _collection_set.optional_region_length(), time_left_ms);
3909 break;
3910 }
3911
3912 {
3913 Ticks start = Ticks::now();
3914 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3915 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3916 }
3917
3918 {
3919 Ticks start = Ticks::now();
3920 evacuate_next_optional_regions(per_thread_states);
3921 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3922 }
3923 }
3924
3925 _collection_set.abandon_optional_collection_set(per_thread_states);
3926 }
3927
3928 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3929 G1RedirtyCardsQueueSet* rdcqs,
3930 G1ParScanThreadStateSet* per_thread_states) {
3931 G1GCPhaseTimes* p = phase_times();
3932
3933 rem_set()->cleanup_after_scan_heap_roots();
3934
3935 // Process any discovered reference objects - we have
3936 // to do this _before_ we retire the GC alloc regions
3937 // as we may have to copy some 'reachable' referent
3938 // objects (and their reachable sub-graphs) that were
3939 // not copied during the pause.
3940 process_discovered_references(per_thread_states);
3941
3942 G1STWIsAliveClosure is_alive(this);
3943 G1KeepAliveClosure keep_alive(this);
3944
3945 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
3946
3947 if (G1StringDedup::is_enabled()) {
3948 double string_dedup_time_ms = os::elapsedTime();
3949
3950 string_dedup_cleaning(&is_alive, &keep_alive, p);
3951
3952 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3953 p->record_string_deduplication_time(string_cleanup_time_ms);
3954 }
3955
3956 _allocator->release_gc_alloc_regions(evacuation_info);
3957
3958 if (evacuation_failed()) {
3959 restore_after_evac_failure(rdcqs);
3960
3961 // Reset the G1EvacuationFailureALot counters and flags
3962 NOT_PRODUCT(reset_evacuation_should_fail();)
3963
3964 double recalculate_used_start = os::elapsedTime();
3965 set_used(recalculate_used());
3966 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3967
3968 if (_archive_allocator != NULL) {
3969 _archive_allocator->clear_used();
3970 }
3971 for (uint i = 0; i < ParallelGCThreads; i++) {
3972 if (_evacuation_failed_info_array[i].has_failed()) {
3973 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3974 }
3975 }
3976 } else {
3977 // The "used" of the the collection set have already been subtracted
3978 // when they were freed. Add in the bytes used.
3979 increase_used(_bytes_used_during_gc);
3980 }
3981
3982 _preserved_marks_set.assert_empty();
3983
3984 merge_per_thread_state_info(per_thread_states);
3985
3986 // Reset and re-enable the hot card cache.
3987 // Note the counts for the cards in the regions in the
3988 // collection set are reset when the collection set is freed.
3989 _hot_card_cache->reset_hot_cache();
3990 _hot_card_cache->set_use_cache(true);
3991
3992 purge_code_root_memory();
3993
3994 redirty_logged_cards(rdcqs);
3995
3996 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3997
3998 eagerly_reclaim_humongous_regions();
3999
4000 record_obj_copy_mem_stats();
4001
4002 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4003 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4004
4005 #if COMPILER2_OR_JVMCI
4006 double start = os::elapsedTime();
4007 DerivedPointerTable::update_pointers();
4008 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4009 #endif
4010 policy()->print_age_table();
4011 }
4012
4013 void G1CollectedHeap::record_obj_copy_mem_stats() {
4014 policy()->old_gen_alloc_tracker()->
4015 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4016
4017 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4018 create_g1_evac_summary(&_old_evac_stats));
4019 }
4020
4021 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4022 assert(!hr->is_free(), "the region should not be free");
4023 assert(!hr->is_empty(), "the region should not be empty");
4024 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4025
4026 if (G1VerifyBitmaps) {
4027 MemRegion mr(hr->bottom(), hr->end());
4028 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4029 }
4030
4031 // Clear the card counts for this region.
4032 // Note: we only need to do this if the region is not young
4033 // (since we don't refine cards in young regions).
4034 if (!hr->is_young()) {
4035 _hot_card_cache->reset_card_counts(hr);
4036 }
4037
4038 // Reset region metadata to allow reuse.
4039 hr->hr_clear(true /* clear_space */);
4040 _policy->remset_tracker()->update_at_free(hr);
4041
4042 if (free_list != NULL) {
4043 free_list->add_ordered(hr);
4044 }
4045 }
4046
4047 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4048 FreeRegionList* free_list) {
4049 assert(hr->is_humongous(), "this is only for humongous regions");
4050 assert(free_list != NULL, "pre-condition");
4051 hr->clear_humongous();
4052 free_region(hr, free_list);
4053 }
4054
4055 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4056 const uint humongous_regions_removed) {
4057 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4058 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4059 _old_set.bulk_remove(old_regions_removed);
4060 _humongous_set.bulk_remove(humongous_regions_removed);
4061 }
4062
4063 }
4064
4065 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4066 assert(list != NULL, "list can't be null");
4067 if (!list->is_empty()) {
4068 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4069 _hrm->insert_list_into_free_list(list);
4070 }
4071 }
4072
4073 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4074 decrease_used(bytes);
4075 }
4076
4077 class G1FreeCollectionSetTask : public AbstractGangTask {
4078 // Helper class to keep statistics for the collection set freeing
4079 class FreeCSetStats {
4080 size_t _before_used_bytes; // Usage in regions successfully evacutate
4081 size_t _after_used_bytes; // Usage in regions failing evacuation
4082 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4083 size_t _failure_used_words; // Live size in failed regions
4084 size_t _failure_waste_words; // Wasted size in failed regions
4085 size_t _rs_length; // Remembered set size
4086 uint _regions_freed; // Number of regions freed
4087 public:
4088 FreeCSetStats() :
4089 _before_used_bytes(0),
4090 _after_used_bytes(0),
4091 _bytes_allocated_in_old_since_last_gc(0),
4092 _failure_used_words(0),
4093 _failure_waste_words(0),
4094 _rs_length(0),
4095 _regions_freed(0) { }
4096
4097 void merge_stats(FreeCSetStats* other) {
4098 assert(other != NULL, "invariant");
4099 _before_used_bytes += other->_before_used_bytes;
4100 _after_used_bytes += other->_after_used_bytes;
4101 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4102 _failure_used_words += other->_failure_used_words;
4103 _failure_waste_words += other->_failure_waste_words;
4104 _rs_length += other->_rs_length;
4105 _regions_freed += other->_regions_freed;
4106 }
4107
4108 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4109 evacuation_info->set_regions_freed(_regions_freed);
4110 evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4111
4112 g1h->decrement_summary_bytes(_before_used_bytes);
4113 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4114
4115 G1Policy *policy = g1h->policy();
4116 policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4117 policy->record_rs_length(_rs_length);
4118 policy->cset_regions_freed();
4119 }
4120
4121 void account_failed_region(HeapRegion* r) {
4122 size_t used_words = r->marked_bytes() / HeapWordSize;
4123 _failure_used_words += used_words;
4124 _failure_waste_words += HeapRegion::GrainWords - used_words;
4125 _after_used_bytes += r->used();
4126
4127 // When moving a young gen region to old gen, we "allocate" that whole
4128 // region there. This is in addition to any already evacuated objects.
4129 // Notify the policy about that. Old gen regions do not cause an
4130 // additional allocation: both the objects still in the region and the
4131 // ones already moved are accounted for elsewhere.
4132 if (r->is_young()) {
4133 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4134 }
4135 }
4136
4137 void account_evacuated_region(HeapRegion* r) {
4138 _before_used_bytes += r->used();
4139 _regions_freed += 1;
4140 }
4141
4142 void account_rs_length(HeapRegion* r) {
4143 _rs_length += r->rem_set()->occupied();
4144 }
4145 };
4146
4147 // Closure applied to all regions in the collection set.
4148 class FreeCSetClosure : public HeapRegionClosure {
4149 // Helper to send JFR events for regions.
4150 class JFREventForRegion {
4151 EventGCPhaseParallel _event;
4152 public:
4153 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4154 _event.set_gcId(GCId::current());
4155 _event.set_gcWorkerId(worker_id);
4156 if (region->is_young()) {
4157 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4158 } else {
4159 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4160 }
4161 }
4162
4163 ~JFREventForRegion() {
4164 _event.commit();
4165 }
4166 };
4167
4168 // Helper to do timing for region work.
4169 class TimerForRegion {
4170 Tickspan& _time;
4171 Ticks _start_time;
4172 public:
4173 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4174 ~TimerForRegion() {
4175 _time += Ticks::now() - _start_time;
4176 }
4177 };
4178
4179 // FreeCSetClosure members
4180 G1CollectedHeap* _g1h;
4181 const size_t* _surviving_young_words;
4182 uint _worker_id;
4183 Tickspan _young_time;
4184 Tickspan _non_young_time;
4185 FreeCSetStats* _stats;
4186
4187 void assert_in_cset(HeapRegion* r) {
4188 assert(r->young_index_in_cset() != 0 &&
4189 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4190 "Young index %u is wrong for region %u of type %s with %u young regions",
4191 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4192 }
4193
4194 void handle_evacuated_region(HeapRegion* r) {
4195 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4196 stats()->account_evacuated_region(r);
4197
4198 // Free the region and and its remembered set.
4199 _g1h->free_region(r, NULL);
4200 }
4201
4202 void handle_failed_region(HeapRegion* r) {
4203 // Do some allocation statistics accounting. Regions that failed evacuation
4204 // are always made old, so there is no need to update anything in the young
4205 // gen statistics, but we need to update old gen statistics.
4206 stats()->account_failed_region(r);
4207
4208 // Update the region state due to the failed evacuation.
4209 r->handle_evacuation_failure();
4210
4211 // Add region to old set, need to hold lock.
4212 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4213 _g1h->old_set_add(r);
4214 }
4215
4216 Tickspan& timer_for_region(HeapRegion* r) {
4217 return r->is_young() ? _young_time : _non_young_time;
4218 }
4219
4220 FreeCSetStats* stats() {
4221 return _stats;
4222 }
4223 public:
4224 FreeCSetClosure(const size_t* surviving_young_words,
4225 uint worker_id,
4226 FreeCSetStats* stats) :
4227 HeapRegionClosure(),
4228 _g1h(G1CollectedHeap::heap()),
4229 _surviving_young_words(surviving_young_words),
4230 _worker_id(worker_id),
4231 _young_time(),
4232 _non_young_time(),
4233 _stats(stats) { }
4234
4235 virtual bool do_heap_region(HeapRegion* r) {
4236 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4237 JFREventForRegion event(r, _worker_id);
4238 TimerForRegion timer(timer_for_region(r));
4239
4240 _g1h->clear_region_attr(r);
4241 stats()->account_rs_length(r);
4242
4243 if (r->is_young()) {
4244 assert_in_cset(r);
4245 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4246 }
4247
4248 if (r->evacuation_failed()) {
4249 handle_failed_region(r);
4250 } else {
4251 handle_evacuated_region(r);
4252 }
4253 assert(!_g1h->is_on_master_free_list(r), "sanity");
4254
4255 return false;
4256 }
4257
4258 void report_timing(Tickspan parallel_time) {
4259 G1GCPhaseTimes* pt = _g1h->phase_times();
4260 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4261 if (_young_time.value() > 0) {
4262 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4263 }
4264 if (_non_young_time.value() > 0) {
4265 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4266 }
4267 }
4268 };
4269
4270 // G1FreeCollectionSetTask members
4271 G1CollectedHeap* _g1h;
4272 G1EvacuationInfo* _evacuation_info;
4273 FreeCSetStats* _worker_stats;
4274 HeapRegionClaimer _claimer;
4275 const size_t* _surviving_young_words;
4276 uint _active_workers;
4277
4278 FreeCSetStats* worker_stats(uint worker) {
4279 return &_worker_stats[worker];
4280 }
4281
4282 void report_statistics() {
4283 // Merge the accounting
4284 FreeCSetStats total_stats;
4285 for (uint worker = 0; worker < _active_workers; worker++) {
4286 total_stats.merge_stats(worker_stats(worker));
4287 }
4288 total_stats.report(_g1h, _evacuation_info);
4289 }
4290
4291 public:
4292 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4293 AbstractGangTask("G1 Free Collection Set"),
4294 _g1h(G1CollectedHeap::heap()),
4295 _evacuation_info(evacuation_info),
4296 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4297 _claimer(active_workers),
4298 _surviving_young_words(surviving_young_words),
4299 _active_workers(active_workers) {
4300 for (uint worker = 0; worker < active_workers; worker++) {
4301 ::new (&_worker_stats[worker]) FreeCSetStats();
4302 }
4303 }
4304
4305 ~G1FreeCollectionSetTask() {
4306 Ticks serial_time = Ticks::now();
4307 report_statistics();
4308 for (uint worker = 0; worker < _active_workers; worker++) {
4309 _worker_stats[worker].~FreeCSetStats();
4310 }
4311 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4312 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4313 }
4314
4315 virtual void work(uint worker_id) {
4316 EventGCPhaseParallel event;
4317 Ticks start = Ticks::now();
4318 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4319 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4320
4321 // Report the total parallel time along with some more detailed metrics.
4322 cl.report_timing(Ticks::now() - start);
4323 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4324 }
4325 };
4326
4327 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4328 _eden.clear();
4329
4330 // The free collections set is split up in two tasks, the first
4331 // frees the collection set and records what regions are free,
4332 // and the second one rebuilds the free list. This proved to be
4333 // more efficient than adding a sorted list to another.
4334
4335 Ticks free_cset_start_time = Ticks::now();
4336 {
4337 uint const num_cs_regions = _collection_set.region_length();
4338 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4339 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4340
4341 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4342 cl.name(), num_workers, num_cs_regions, num_regions());
4343 workers()->run_task(&cl, num_workers);
4344 }
4345
4346 Ticks free_cset_end_time = Ticks::now();
4347 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4348
4349 // Now rebuild the free region list.
4350 hrm()->rebuild_free_list(workers());
4351 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4352
4353 collection_set->clear();
4354 }
4355
4356 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4357 private:
4358 FreeRegionList* _free_region_list;
4359 HeapRegionSet* _proxy_set;
4360 uint _humongous_objects_reclaimed;
4361 uint _humongous_regions_reclaimed;
4362 size_t _freed_bytes;
4363 public:
4364
4365 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4366 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4367 }
4368
4369 virtual bool do_heap_region(HeapRegion* r) {
4370 if (!r->is_starts_humongous()) {
4371 return false;
4372 }
4373
4374 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4375
4376 oop obj = (oop)r->bottom();
4377 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4378
4379 // The following checks whether the humongous object is live are sufficient.
4380 // The main additional check (in addition to having a reference from the roots
4381 // or the young gen) is whether the humongous object has a remembered set entry.
4382 //
4383 // A humongous object cannot be live if there is no remembered set for it
4384 // because:
4385 // - there can be no references from within humongous starts regions referencing
4386 // the object because we never allocate other objects into them.
4387 // (I.e. there are no intra-region references that may be missed by the
4388 // remembered set)
4389 // - as soon there is a remembered set entry to the humongous starts region
4390 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4391 // until the end of a concurrent mark.
4392 //
4393 // It is not required to check whether the object has been found dead by marking
4394 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4395 // all objects allocated during that time are considered live.
4396 // SATB marking is even more conservative than the remembered set.
4397 // So if at this point in the collection there is no remembered set entry,
4398 // nobody has a reference to it.
4399 // At the start of collection we flush all refinement logs, and remembered sets
4400 // are completely up-to-date wrt to references to the humongous object.
4401 //
4402 // Other implementation considerations:
4403 // - never consider object arrays at this time because they would pose
4404 // considerable effort for cleaning up the the remembered sets. This is
4405 // required because stale remembered sets might reference locations that
4406 // are currently allocated into.
4407 uint region_idx = r->hrm_index();
4408 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4409 !r->rem_set()->is_empty()) {
4410 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",
4411 region_idx,
4412 (size_t)obj->size() * HeapWordSize,
4413 p2i(r->bottom()),
4414 r->rem_set()->occupied(),
4415 r->rem_set()->strong_code_roots_list_length(),
4416 next_bitmap->is_marked(r->bottom()),
4417 g1h->is_humongous_reclaim_candidate(region_idx),
4418 obj->is_typeArray()
4419 );
4420 return false;
4421 }
4422
4423 guarantee(obj->is_typeArray(),
4424 "Only eagerly reclaiming type arrays is supported, but the object "
4425 PTR_FORMAT " is not.", p2i(r->bottom()));
4426
4427 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",
4428 region_idx,
4429 (size_t)obj->size() * HeapWordSize,
4430 p2i(r->bottom()),
4431 r->rem_set()->occupied(),
4432 r->rem_set()->strong_code_roots_list_length(),
4433 next_bitmap->is_marked(r->bottom()),
4434 g1h->is_humongous_reclaim_candidate(region_idx),
4435 obj->is_typeArray()
4436 );
4437
4438 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4439 cm->humongous_object_eagerly_reclaimed(r);
4440 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4441 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4442 region_idx,
4443 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4444 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4445 _humongous_objects_reclaimed++;
4446 do {
4447 HeapRegion* next = g1h->next_region_in_humongous(r);
4448 _freed_bytes += r->used();
4449 r->set_containing_set(NULL);
4450 _humongous_regions_reclaimed++;
4451 g1h->free_humongous_region(r, _free_region_list);
4452 r = next;
4453 } while (r != NULL);
4454
4455 return false;
4456 }
4457
4458 uint humongous_objects_reclaimed() {
4459 return _humongous_objects_reclaimed;
4460 }
4461
4462 uint humongous_regions_reclaimed() {
4463 return _humongous_regions_reclaimed;
4464 }
4465
4466 size_t bytes_freed() const {
4467 return _freed_bytes;
4468 }
4469 };
4470
4471 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4472 assert_at_safepoint_on_vm_thread();
4473
4474 if (!G1EagerReclaimHumongousObjects ||
4475 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4476 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4477 return;
4478 }
4479
4480 double start_time = os::elapsedTime();
4481
4482 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4483
4484 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4485 heap_region_iterate(&cl);
4486
4487 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4488
4489 G1HRPrinter* hrp = hr_printer();
4490 if (hrp->is_active()) {
4491 FreeRegionListIterator iter(&local_cleanup_list);
4492 while (iter.more_available()) {
4493 HeapRegion* hr = iter.get_next();
4494 hrp->cleanup(hr);
4495 }
4496 }
4497
4498 prepend_to_freelist(&local_cleanup_list);
4499 decrement_summary_bytes(cl.bytes_freed());
4500
4501 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4502 cl.humongous_objects_reclaimed());
4503 }
4504
4505 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4506 public:
4507 virtual bool do_heap_region(HeapRegion* r) {
4508 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4509 G1CollectedHeap::heap()->clear_region_attr(r);
4510 r->clear_young_index_in_cset();
4511 return false;
4512 }
4513 };
4514
4515 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4516 G1AbandonCollectionSetClosure cl;
4517 collection_set_iterate_all(&cl);
4518
4519 collection_set->clear();
4520 collection_set->stop_incremental_building();
4521 }
4522
4523 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4524 return _allocator->is_retained_old_region(hr);
4525 }
4526
4527 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4528 _eden.add(hr);
4529 _policy->set_region_eden(hr);
4530 }
4531
4532 #ifdef ASSERT
4533
4534 class NoYoungRegionsClosure: public HeapRegionClosure {
4535 private:
4536 bool _success;
4537 public:
4538 NoYoungRegionsClosure() : _success(true) { }
4539 bool do_heap_region(HeapRegion* r) {
4540 if (r->is_young()) {
4541 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4542 p2i(r->bottom()), p2i(r->end()));
4543 _success = false;
4544 }
4545 return false;
4546 }
4547 bool success() { return _success; }
4548 };
4549
4550 bool G1CollectedHeap::check_young_list_empty() {
4551 bool ret = (young_regions_count() == 0);
4552
4553 NoYoungRegionsClosure closure;
4554 heap_region_iterate(&closure);
4555 ret = ret && closure.success();
4556
4557 return ret;
4558 }
4559
4560 #endif // ASSERT
4561
4562 class TearDownRegionSetsClosure : public HeapRegionClosure {
4563 HeapRegionSet *_old_set;
4564
4565 public:
4566 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4567
4568 bool do_heap_region(HeapRegion* r) {
4569 if (r->is_old()) {
4570 _old_set->remove(r);
4571 } else if(r->is_young()) {
4572 r->uninstall_surv_rate_group();
4573 } else {
4574 // We ignore free regions, we'll empty the free list afterwards.
4575 // We ignore humongous and archive regions, we're not tearing down these
4576 // sets.
4577 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4578 "it cannot be another type");
4579 }
4580 return false;
4581 }
4582
4583 ~TearDownRegionSetsClosure() {
4584 assert(_old_set->is_empty(), "post-condition");
4585 }
4586 };
4587
4588 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4589 assert_at_safepoint_on_vm_thread();
4590
4591 if (!free_list_only) {
4592 TearDownRegionSetsClosure cl(&_old_set);
4593 heap_region_iterate(&cl);
4594
4595 // Note that emptying the _young_list is postponed and instead done as
4596 // the first step when rebuilding the regions sets again. The reason for
4597 // this is that during a full GC string deduplication needs to know if
4598 // a collected region was young or old when the full GC was initiated.
4599 }
4600 _hrm->remove_all_free_regions();
4601 }
4602
4603 void G1CollectedHeap::increase_used(size_t bytes) {
4604 _summary_bytes_used += bytes;
4605 }
4606
4607 void G1CollectedHeap::decrease_used(size_t bytes) {
4608 assert(_summary_bytes_used >= bytes,
4609 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4610 _summary_bytes_used, bytes);
4611 _summary_bytes_used -= bytes;
4612 }
4613
4614 void G1CollectedHeap::set_used(size_t bytes) {
4615 _summary_bytes_used = bytes;
4616 }
4617
4618 class RebuildRegionSetsClosure : public HeapRegionClosure {
4619 private:
4620 bool _free_list_only;
4621
4622 HeapRegionSet* _old_set;
4623 HeapRegionManager* _hrm;
4624
4625 size_t _total_used;
4626
4627 public:
4628 RebuildRegionSetsClosure(bool free_list_only,
4629 HeapRegionSet* old_set,
4630 HeapRegionManager* hrm) :
4631 _free_list_only(free_list_only),
4632 _old_set(old_set), _hrm(hrm), _total_used(0) {
4633 assert(_hrm->num_free_regions() == 0, "pre-condition");
4634 if (!free_list_only) {
4635 assert(_old_set->is_empty(), "pre-condition");
4636 }
4637 }
4638
4639 bool do_heap_region(HeapRegion* r) {
4640 if (r->is_empty()) {
4641 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4642 // Add free regions to the free list
4643 r->set_free();
4644 _hrm->insert_into_free_list(r);
4645 } else if (!_free_list_only) {
4646 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4647
4648 if (r->is_archive() || r->is_humongous()) {
4649 // We ignore archive and humongous regions. We left these sets unchanged.
4650 } else {
4651 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4652 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4653 r->move_to_old();
4654 _old_set->add(r);
4655 }
4656 _total_used += r->used();
4657 }
4658
4659 return false;
4660 }
4661
4662 size_t total_used() {
4663 return _total_used;
4664 }
4665 };
4666
4667 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4668 assert_at_safepoint_on_vm_thread();
4669
4670 if (!free_list_only) {
4671 _eden.clear();
4672 _survivor.clear();
4673 }
4674
4675 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4676 heap_region_iterate(&cl);
4677
4678 if (!free_list_only) {
4679 set_used(cl.total_used());
4680 if (_archive_allocator != NULL) {
4681 _archive_allocator->clear_used();
4682 }
4683 }
4684 assert_used_and_recalculate_used_equal(this);
4685 }
4686
4687 // Methods for the mutator alloc region
4688
4689 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4690 bool force,
4691 uint node_index) {
4692 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4693 bool should_allocate = policy()->should_allocate_mutator_region();
4694 if (force || should_allocate) {
4695 HeapRegion* new_alloc_region = new_region(word_size,
4696 HeapRegionType::Eden,
4697 false /* do_expand */,
4698 node_index);
4699 if (new_alloc_region != NULL) {
4700 set_region_short_lived_locked(new_alloc_region);
4701 _hr_printer.alloc(new_alloc_region, !should_allocate);
4702 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4703 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4704 return new_alloc_region;
4705 }
4706 }
4707 return NULL;
4708 }
4709
4710 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4711 size_t allocated_bytes) {
4712 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4713 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4714
4715 collection_set()->add_eden_region(alloc_region);
4716 increase_used(allocated_bytes);
4717 _eden.add_used_bytes(allocated_bytes);
4718 _hr_printer.retire(alloc_region);
4719
4720 // We update the eden sizes here, when the region is retired,
4721 // instead of when it's allocated, since this is the point that its
4722 // used space has been recorded in _summary_bytes_used.
4723 g1mm()->update_eden_size();
4724 }
4725
4726 // Methods for the GC alloc regions
4727
4728 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4729 if (dest.is_old()) {
4730 return true;
4731 } else {
4732 return survivor_regions_count() < policy()->max_survivor_regions();
4733 }
4734 }
4735
4736 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4737 assert(FreeList_lock->owned_by_self(), "pre-condition");
4738
4739 if (!has_more_regions(dest)) {
4740 return NULL;
4741 }
4742
4743 HeapRegionType type;
4744 if (dest.is_young()) {
4745 type = HeapRegionType::Survivor;
4746 } else {
4747 type = HeapRegionType::Old;
4748 }
4749
4750 HeapRegion* new_alloc_region = new_region(word_size,
4751 type,
4752 true /* do_expand */,
4753 node_index);
4754
4755 if (new_alloc_region != NULL) {
4756 if (type.is_survivor()) {
4757 new_alloc_region->set_survivor();
4758 _survivor.add(new_alloc_region);
4759 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4760 } else {
4761 new_alloc_region->set_old();
4762 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4763 }
4764 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4765 register_region_with_region_attr(new_alloc_region);
4766 _hr_printer.alloc(new_alloc_region);
4767 return new_alloc_region;
4768 }
4769 return NULL;
4770 }
4771
4772 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4773 size_t allocated_bytes,
4774 G1HeapRegionAttr dest) {
4775 _bytes_used_during_gc += allocated_bytes;
4776 if (dest.is_old()) {
4777 old_set_add(alloc_region);
4778 } else {
4779 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4780 _survivor.add_used_bytes(allocated_bytes);
4781 }
4782
4783 bool const during_im = collector_state()->in_concurrent_start_gc();
4784 if (during_im && allocated_bytes > 0) {
4785 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4786 }
4787 _hr_printer.retire(alloc_region);
4788 }
4789
4790 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4791 bool expanded = false;
4792 uint index = _hrm->find_highest_free(&expanded);
4793
4794 if (index != G1_NO_HRM_INDEX) {
4795 if (expanded) {
4796 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4797 HeapRegion::GrainWords * HeapWordSize);
4798 }
4799 return _hrm->allocate_free_regions_starting_at(index, 1);
4800 }
4801 return NULL;
4802 }
4803
4804 // Optimized nmethod scanning
4805
4806 class RegisterNMethodOopClosure: public OopClosure {
4807 G1CollectedHeap* _g1h;
4808 nmethod* _nm;
4809
4810 template <class T> void do_oop_work(T* p) {
4811 T heap_oop = RawAccess<>::oop_load(p);
4812 if (!CompressedOops::is_null(heap_oop)) {
4813 oop obj = CompressedOops::decode_not_null(heap_oop);
4814 HeapRegion* hr = _g1h->heap_region_containing(obj);
4815 assert(!hr->is_continues_humongous(),
4816 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4817 " starting at " HR_FORMAT,
4818 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4819
4820 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4821 hr->add_strong_code_root_locked(_nm);
4822 }
4823 }
4824
4825 public:
4826 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4827 _g1h(g1h), _nm(nm) {}
4828
4829 void do_oop(oop* p) { do_oop_work(p); }
4830 void do_oop(narrowOop* p) { do_oop_work(p); }
4831 };
4832
4833 class UnregisterNMethodOopClosure: public OopClosure {
4834 G1CollectedHeap* _g1h;
4835 nmethod* _nm;
4836
4837 template <class T> void do_oop_work(T* p) {
4838 T heap_oop = RawAccess<>::oop_load(p);
4839 if (!CompressedOops::is_null(heap_oop)) {
4840 oop obj = CompressedOops::decode_not_null(heap_oop);
4841 HeapRegion* hr = _g1h->heap_region_containing(obj);
4842 assert(!hr->is_continues_humongous(),
4843 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4844 " starting at " HR_FORMAT,
4845 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4846
4847 hr->remove_strong_code_root(_nm);
4848 }
4849 }
4850
4851 public:
4852 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4853 _g1h(g1h), _nm(nm) {}
4854
4855 void do_oop(oop* p) { do_oop_work(p); }
4856 void do_oop(narrowOop* p) { do_oop_work(p); }
4857 };
4858
4859 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4860 guarantee(nm != NULL, "sanity");
4861 RegisterNMethodOopClosure reg_cl(this, nm);
4862 nm->oops_do(®_cl);
4863 }
4864
4865 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4866 guarantee(nm != NULL, "sanity");
4867 UnregisterNMethodOopClosure reg_cl(this, nm);
4868 nm->oops_do(®_cl, true);
4869 }
4870
4871 void G1CollectedHeap::purge_code_root_memory() {
4872 double purge_start = os::elapsedTime();
4873 G1CodeRootSet::purge();
4874 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4875 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4876 }
4877
4878 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4879 G1CollectedHeap* _g1h;
4880
4881 public:
4882 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4883 _g1h(g1h) {}
4884
4885 void do_code_blob(CodeBlob* cb) {
4886 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4887 if (nm == NULL) {
4888 return;
4889 }
4890
4891 _g1h->register_nmethod(nm);
4892 }
4893 };
4894
4895 void G1CollectedHeap::rebuild_strong_code_roots() {
4896 RebuildStrongCodeRootClosure blob_cl(this);
4897 CodeCache::blobs_do(&blob_cl);
4898 }
4899
4900 void G1CollectedHeap::initialize_serviceability() {
4901 _g1mm->initialize_serviceability();
4902 }
4903
4904 MemoryUsage G1CollectedHeap::memory_usage() {
4905 return _g1mm->memory_usage();
4906 }
4907
4908 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4909 return _g1mm->memory_managers();
4910 }
4911
4912 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4913 return _g1mm->memory_pools();
4914 }