1 /*
2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1BarrierSet.hpp"
33 #include "gc/g1/g1CollectedHeap.inline.hpp"
34 #include "gc/g1/g1CollectionSet.hpp"
35 #include "gc/g1/g1CollectorPolicy.hpp"
36 #include "gc/g1/g1CollectorState.hpp"
37 #include "gc/g1/g1ConcurrentRefine.hpp"
38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
40 #include "gc/g1/g1DirtyCardQueue.hpp"
41 #include "gc/g1/g1EvacStats.inline.hpp"
42 #include "gc/g1/g1FullCollector.hpp"
43 #include "gc/g1/g1GCPhaseTimes.hpp"
44 #include "gc/g1/g1HeapSizingPolicy.hpp"
45 #include "gc/g1/g1HeapTransition.hpp"
46 #include "gc/g1/g1HeapVerifier.hpp"
47 #include "gc/g1/g1HotCardCache.hpp"
48 #include "gc/g1/g1MemoryPool.hpp"
49 #include "gc/g1/g1OopClosures.inline.hpp"
50 #include "gc/g1/g1ParScanThreadState.inline.hpp"
51 #include "gc/g1/g1Policy.hpp"
52 #include "gc/g1/g1RegionToSpaceMapper.hpp"
53 #include "gc/g1/g1RemSet.hpp"
54 #include "gc/g1/g1RootClosures.hpp"
55 #include "gc/g1/g1RootProcessor.hpp"
56 #include "gc/g1/g1SATBMarkQueueSet.hpp"
57 #include "gc/g1/g1StringDedup.hpp"
58 #include "gc/g1/g1ThreadLocalData.hpp"
59 #include "gc/g1/g1YCTypes.hpp"
60 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
61 #include "gc/g1/g1VMOperations.hpp"
62 #include "gc/g1/heapRegion.inline.hpp"
63 #include "gc/g1/heapRegionRemSet.hpp"
64 #include "gc/g1/heapRegionSet.inline.hpp"
65 #include "gc/shared/gcBehaviours.hpp"
66 #include "gc/shared/gcHeapSummary.hpp"
67 #include "gc/shared/gcId.hpp"
68 #include "gc/shared/gcLocker.hpp"
69 #include "gc/shared/gcTimer.hpp"
70 #include "gc/shared/gcTrace.hpp"
71 #include "gc/shared/gcTraceTime.inline.hpp"
72 #include "gc/shared/generationSpec.hpp"
73 #include "gc/shared/isGCActiveMark.hpp"
74 #include "gc/shared/oopStorageParState.hpp"
75 #include "gc/shared/parallelCleaning.hpp"
76 #include "gc/shared/preservedMarks.inline.hpp"
77 #include "gc/shared/suspendibleThreadSet.hpp"
78 #include "gc/shared/referenceProcessor.inline.hpp"
79 #include "gc/shared/taskqueue.inline.hpp"
80 #include "gc/shared/weakProcessor.inline.hpp"
81 #include "gc/shared/workerPolicy.hpp"
82 #include "logging/log.hpp"
83 #include "memory/allocation.hpp"
84 #include "memory/iterator.hpp"
85 #include "memory/resourceArea.hpp"
86 #include "oops/access.inline.hpp"
87 #include "oops/compressedOops.inline.hpp"
88 #include "oops/oop.inline.hpp"
89 #include "runtime/atomic.hpp"
90 #include "runtime/flags/flagSetting.hpp"
91 #include "runtime/handles.inline.hpp"
92 #include "runtime/init.hpp"
93 #include "runtime/orderAccess.hpp"
94 #include "runtime/threadSMR.hpp"
95 #include "runtime/vmThread.hpp"
96 #include "utilities/align.hpp"
97 #include "utilities/globalDefinitions.hpp"
98 #include "utilities/stack.inline.hpp"
99
100 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
101
102 // INVARIANTS/NOTES
103 //
104 // All allocation activity covered by the G1CollectedHeap interface is
105 // serialized by acquiring the HeapLock. This happens in mem_allocate
106 // and allocate_new_tlab, which are the "entry" points to the
107 // allocation code from the rest of the JVM. (Note that this does not
108 // apply to TLAB allocation, which is not part of this interface: it
109 // is done by clients of this interface.)
110
111 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
112 private:
113 size_t _num_dirtied;
114 G1CollectedHeap* _g1h;
115 G1CardTable* _g1_ct;
116
117 HeapRegion* region_for_card(jbyte* card_ptr) const {
118 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
119 }
120
121 bool will_become_free(HeapRegion* hr) const {
122 // A region will be freed by free_collection_set if the region is in the
123 // collection set and has not had an evacuation failure.
124 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
125 }
126
127 public:
128 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
129 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
130
131 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
132 HeapRegion* hr = region_for_card(card_ptr);
133
134 // Should only dirty cards in regions that won't be freed.
135 if (!will_become_free(hr)) {
136 *card_ptr = G1CardTable::dirty_card_val();
137 _num_dirtied++;
138 }
139
140 return true;
141 }
142
143 size_t num_dirtied() const { return _num_dirtied; }
144 };
145
146
147 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
148 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
149 }
150
151 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
152 // The from card cache is not the memory that is actually committed. So we cannot
153 // take advantage of the zero_filled parameter.
154 reset_from_card_cache(start_idx, num_regions);
155 }
156
157
158 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
159 MemRegion mr) {
160 return new HeapRegion(hrs_index, bot(), mr);
161 }
162
163 // Private methods.
164
165 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
166 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
167 "the only time we use this to allocate a humongous region is "
168 "when we are allocating a single humongous region");
169
170 HeapRegion* res = _hrm->allocate_free_region(type);
171
172 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
173 // Currently, only attempts to allocate GC alloc regions set
174 // do_expand to true. So, we should only reach here during a
175 // safepoint. If this assumption changes we might have to
176 // reconsider the use of _expand_heap_after_alloc_failure.
177 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
178
179 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
180 word_size * HeapWordSize);
181
182 if (expand(word_size * HeapWordSize)) {
183 // Given that expand() succeeded in expanding the heap, and we
184 // always expand the heap by an amount aligned to the heap
185 // region size, the free list should in theory not be empty.
186 // In either case allocate_free_region() will check for NULL.
187 res = _hrm->allocate_free_region(type);
188 } else {
189 _expand_heap_after_alloc_failure = false;
190 }
191 }
192 return res;
193 }
194
195 HeapWord*
196 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
197 uint num_regions,
198 size_t word_size) {
199 assert(first != G1_NO_HRM_INDEX, "pre-condition");
200 assert(is_humongous(word_size), "word_size should be humongous");
201 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
202
203 // Index of last region in the series.
204 uint last = first + num_regions - 1;
205
206 // We need to initialize the region(s) we just discovered. This is
207 // a bit tricky given that it can happen concurrently with
208 // refinement threads refining cards on these regions and
209 // potentially wanting to refine the BOT as they are scanning
210 // those cards (this can happen shortly after a cleanup; see CR
211 // 6991377). So we have to set up the region(s) carefully and in
212 // a specific order.
213
214 // The word size sum of all the regions we will allocate.
215 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
216 assert(word_size <= word_size_sum, "sanity");
217
218 // This will be the "starts humongous" region.
219 HeapRegion* first_hr = region_at(first);
220 // The header of the new object will be placed at the bottom of
221 // the first region.
222 HeapWord* new_obj = first_hr->bottom();
223 // This will be the new top of the new object.
224 HeapWord* obj_top = new_obj + word_size;
225
226 // First, we need to zero the header of the space that we will be
227 // allocating. When we update top further down, some refinement
228 // threads might try to scan the region. By zeroing the header we
229 // ensure that any thread that will try to scan the region will
230 // come across the zero klass word and bail out.
231 //
232 // NOTE: It would not have been correct to have used
233 // CollectedHeap::fill_with_object() and make the space look like
234 // an int array. The thread that is doing the allocation will
235 // later update the object header to a potentially different array
236 // type and, for a very short period of time, the klass and length
237 // fields will be inconsistent. This could cause a refinement
238 // thread to calculate the object size incorrectly.
239 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
240
241 // Next, pad out the unused tail of the last region with filler
242 // objects, for improved usage accounting.
243 // How many words we use for filler objects.
244 size_t word_fill_size = word_size_sum - word_size;
245
246 // How many words memory we "waste" which cannot hold a filler object.
247 size_t words_not_fillable = 0;
248
249 if (word_fill_size >= min_fill_size()) {
250 fill_with_objects(obj_top, word_fill_size);
251 } else if (word_fill_size > 0) {
252 // We have space to fill, but we cannot fit an object there.
253 words_not_fillable = word_fill_size;
254 word_fill_size = 0;
255 }
256
257 // We will set up the first region as "starts humongous". This
258 // will also update the BOT covering all the regions to reflect
259 // that there is a single object that starts at the bottom of the
260 // first region.
261 first_hr->set_starts_humongous(obj_top, word_fill_size);
262 _policy->remset_tracker()->update_at_allocate(first_hr);
263 // Then, if there are any, we will set up the "continues
264 // humongous" regions.
265 HeapRegion* hr = NULL;
266 for (uint i = first + 1; i <= last; ++i) {
267 hr = region_at(i);
268 hr->set_continues_humongous(first_hr);
269 _policy->remset_tracker()->update_at_allocate(hr);
270 }
271
272 // Up to this point no concurrent thread would have been able to
273 // do any scanning on any region in this series. All the top
274 // fields still point to bottom, so the intersection between
275 // [bottom,top] and [card_start,card_end] will be empty. Before we
276 // update the top fields, we'll do a storestore to make sure that
277 // no thread sees the update to top before the zeroing of the
278 // object header and the BOT initialization.
279 OrderAccess::storestore();
280
281 // Now, we will update the top fields of the "continues humongous"
282 // regions except the last one.
283 for (uint i = first; i < last; ++i) {
284 hr = region_at(i);
285 hr->set_top(hr->end());
286 }
287
288 hr = region_at(last);
289 // If we cannot fit a filler object, we must set top to the end
290 // of the humongous object, otherwise we cannot iterate the heap
291 // and the BOT will not be complete.
292 hr->set_top(hr->end() - words_not_fillable);
293
294 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
295 "obj_top should be in last region");
296
297 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
298
299 assert(words_not_fillable == 0 ||
300 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
301 "Miscalculation in humongous allocation");
302
303 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
304
305 for (uint i = first; i <= last; ++i) {
306 hr = region_at(i);
307 _humongous_set.add(hr);
308 _hr_printer.alloc(hr);
309 }
310
311 return new_obj;
312 }
313
314 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
315 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
316 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
317 }
318
319 // If could fit into free regions w/o expansion, try.
320 // Otherwise, if can expand, do so.
321 // Otherwise, if using ex regions might help, try with ex given back.
322 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
323 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
324
325 _verifier->verify_region_sets_optional();
326
327 uint first = G1_NO_HRM_INDEX;
328 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
329
330 if (obj_regions == 1) {
331 // Only one region to allocate, try to use a fast path by directly allocating
332 // from the free lists. Do not try to expand here, we will potentially do that
333 // later.
334 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
335 if (hr != NULL) {
336 first = hr->hrm_index();
337 }
338 } else {
339 // Policy: Try only empty regions (i.e. already committed first). Maybe we
340 // are lucky enough to find some.
341 first = _hrm->find_contiguous_only_empty(obj_regions);
342 if (first != G1_NO_HRM_INDEX) {
343 _hrm->allocate_free_regions_starting_at(first, obj_regions);
344 }
345 }
346
347 if (first == G1_NO_HRM_INDEX) {
348 // Policy: We could not find enough regions for the humongous object in the
349 // free list. Look through the heap to find a mix of free and uncommitted regions.
350 // If so, try expansion.
351 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
352 if (first != G1_NO_HRM_INDEX) {
353 // We found something. Make sure these regions are committed, i.e. expand
354 // the heap. Alternatively we could do a defragmentation GC.
355 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
356 word_size * HeapWordSize);
357
358 _hrm->expand_at(first, obj_regions, workers());
359 policy()->record_new_heap_size(num_regions());
360
361 #ifdef ASSERT
362 for (uint i = first; i < first + obj_regions; ++i) {
363 HeapRegion* hr = region_at(i);
364 assert(hr->is_free(), "sanity");
365 assert(hr->is_empty(), "sanity");
366 assert(is_on_master_free_list(hr), "sanity");
367 }
368 #endif
369 _hrm->allocate_free_regions_starting_at(first, obj_regions);
370 } else {
371 // Policy: Potentially trigger a defragmentation GC.
372 }
373 }
374
375 HeapWord* result = NULL;
376 if (first != G1_NO_HRM_INDEX) {
377 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
378 assert(result != NULL, "it should always return a valid result");
379
380 // A successful humongous object allocation changes the used space
381 // information of the old generation so we need to recalculate the
382 // sizes and update the jstat counters here.
383 g1mm()->update_sizes();
384 }
385
386 _verifier->verify_region_sets_optional();
387
388 return result;
389 }
390
391 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
392 size_t requested_size,
393 size_t* actual_size) {
394 assert_heap_not_locked_and_not_at_safepoint();
395 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
396
397 return attempt_allocation(min_size, requested_size, actual_size);
398 }
399
400 HeapWord*
401 G1CollectedHeap::mem_allocate(size_t word_size,
402 bool* gc_overhead_limit_was_exceeded) {
403 assert_heap_not_locked_and_not_at_safepoint();
404
405 if (is_humongous(word_size)) {
406 return attempt_allocation_humongous(word_size);
407 }
408 size_t dummy = 0;
409 return attempt_allocation(word_size, word_size, &dummy);
410 }
411
412 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
413 ResourceMark rm; // For retrieving the thread names in log messages.
414
415 // Make sure you read the note in attempt_allocation_humongous().
416
417 assert_heap_not_locked_and_not_at_safepoint();
418 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
419 "be called for humongous allocation requests");
420
421 // We should only get here after the first-level allocation attempt
422 // (attempt_allocation()) failed to allocate.
423
424 // We will loop until a) we manage to successfully perform the
425 // allocation or b) we successfully schedule a collection which
426 // fails to perform the allocation. b) is the only case when we'll
427 // return NULL.
428 HeapWord* result = NULL;
429 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
430 bool should_try_gc;
431 uint gc_count_before;
432
433 {
434 MutexLockerEx x(Heap_lock);
435 result = _allocator->attempt_allocation_locked(word_size);
436 if (result != NULL) {
437 return result;
438 }
439
440 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
441 // This is different to when only GCLocker::needs_gc() is set: try to avoid
442 // waiting because the GCLocker is active to not wait too long.
443 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
444 // No need for an ergo message here, can_expand_young_list() does this when
445 // it returns true.
446 result = _allocator->attempt_allocation_force(word_size);
447 if (result != NULL) {
448 return result;
449 }
450 }
451 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
452 // the GCLocker initiated GC has been performed and then retry. This includes
453 // the case when the GC Locker is not active but has not been performed.
454 should_try_gc = !GCLocker::needs_gc();
455 // Read the GC count while still holding the Heap_lock.
456 gc_count_before = total_collections();
457 }
458
459 if (should_try_gc) {
460 bool succeeded;
461 result = do_collection_pause(word_size, gc_count_before, &succeeded,
462 GCCause::_g1_inc_collection_pause);
463 if (result != NULL) {
464 assert(succeeded, "only way to get back a non-NULL result");
465 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
466 Thread::current()->name(), p2i(result));
467 return result;
468 }
469
470 if (succeeded) {
471 // We successfully scheduled a collection which failed to allocate. No
472 // point in trying to allocate further. We'll just return NULL.
473 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
474 SIZE_FORMAT " words", Thread::current()->name(), word_size);
475 return NULL;
476 }
477 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
478 Thread::current()->name(), word_size);
479 } else {
480 // Failed to schedule a collection.
481 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
482 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
483 SIZE_FORMAT " words", Thread::current()->name(), word_size);
484 return NULL;
485 }
486 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
487 // The GCLocker is either active or the GCLocker initiated
488 // GC has not yet been performed. Stall until it is and
489 // then retry the allocation.
490 GCLocker::stall_until_clear();
491 gclocker_retry_count += 1;
492 }
493
494 // We can reach here if we were unsuccessful in scheduling a
495 // collection (because another thread beat us to it) or if we were
496 // stalled due to the GC locker. In either can we should retry the
497 // allocation attempt in case another thread successfully
498 // performed a collection and reclaimed enough space. We do the
499 // first attempt (without holding the Heap_lock) here and the
500 // follow-on attempt will be at the start of the next loop
501 // iteration (after taking the Heap_lock).
502 size_t dummy = 0;
503 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
504 if (result != NULL) {
505 return result;
506 }
507
508 // Give a warning if we seem to be looping forever.
509 if ((QueuedAllocationWarningCount > 0) &&
510 (try_count % QueuedAllocationWarningCount == 0)) {
511 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
512 Thread::current()->name(), try_count, word_size);
513 }
514 }
515
516 ShouldNotReachHere();
517 return NULL;
518 }
519
520 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
521 assert_at_safepoint_on_vm_thread();
522 if (_archive_allocator == NULL) {
523 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
524 }
525 }
526
527 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
528 // Allocations in archive regions cannot be of a size that would be considered
529 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
530 // may be different at archive-restore time.
531 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
532 }
533
534 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
535 assert_at_safepoint_on_vm_thread();
536 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
537 if (is_archive_alloc_too_large(word_size)) {
538 return NULL;
539 }
540 return _archive_allocator->archive_mem_allocate(word_size);
541 }
542
543 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
544 size_t end_alignment_in_bytes) {
545 assert_at_safepoint_on_vm_thread();
546 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
547
548 // Call complete_archive to do the real work, filling in the MemRegion
549 // array with the archive regions.
550 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
551 delete _archive_allocator;
552 _archive_allocator = NULL;
553 }
554
555 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
556 assert(ranges != NULL, "MemRegion array NULL");
557 assert(count != 0, "No MemRegions provided");
558 MemRegion reserved = _hrm->reserved();
559 for (size_t i = 0; i < count; i++) {
560 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
561 return false;
562 }
563 }
564 return true;
565 }
566
567 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
568 size_t count,
569 bool open) {
570 assert(!is_init_completed(), "Expect to be called at JVM init time");
571 assert(ranges != NULL, "MemRegion array NULL");
572 assert(count != 0, "No MemRegions provided");
573 MutexLockerEx x(Heap_lock);
574
575 MemRegion reserved = _hrm->reserved();
576 HeapWord* prev_last_addr = NULL;
577 HeapRegion* prev_last_region = NULL;
578
579 // Temporarily disable pretouching of heap pages. This interface is used
580 // when mmap'ing archived heap data in, so pre-touching is wasted.
581 FlagSetting fs(AlwaysPreTouch, false);
582
583 // Enable archive object checking used by G1MarkSweep. We have to let it know
584 // about each archive range, so that objects in those ranges aren't marked.
585 G1ArchiveAllocator::enable_archive_object_check();
586
587 // For each specified MemRegion range, allocate the corresponding G1
588 // regions and mark them as archive regions. We expect the ranges
589 // in ascending starting address order, without overlap.
590 for (size_t i = 0; i < count; i++) {
591 MemRegion curr_range = ranges[i];
592 HeapWord* start_address = curr_range.start();
593 size_t word_size = curr_range.word_size();
594 HeapWord* last_address = curr_range.last();
595 size_t commits = 0;
596
597 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
598 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
599 p2i(start_address), p2i(last_address));
600 guarantee(start_address > prev_last_addr,
601 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
602 p2i(start_address), p2i(prev_last_addr));
603 prev_last_addr = last_address;
604
605 // Check for ranges that start in the same G1 region in which the previous
606 // range ended, and adjust the start address so we don't try to allocate
607 // the same region again. If the current range is entirely within that
608 // region, skip it, just adjusting the recorded top.
609 HeapRegion* start_region = _hrm->addr_to_region(start_address);
610 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
611 start_address = start_region->end();
612 if (start_address > last_address) {
613 increase_used(word_size * HeapWordSize);
614 start_region->set_top(last_address + 1);
615 continue;
616 }
617 start_region->set_top(start_address);
618 curr_range = MemRegion(start_address, last_address + 1);
619 start_region = _hrm->addr_to_region(start_address);
620 }
621
622 // Perform the actual region allocation, exiting if it fails.
623 // Then note how much new space we have allocated.
624 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
625 return false;
626 }
627 increase_used(word_size * HeapWordSize);
628 if (commits != 0) {
629 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
630 HeapRegion::GrainWords * HeapWordSize * commits);
631
632 }
633
634 // Mark each G1 region touched by the range as archive, add it to
635 // the old set, and set top.
636 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
637 HeapRegion* last_region = _hrm->addr_to_region(last_address);
638 prev_last_region = last_region;
639
640 while (curr_region != NULL) {
641 assert(curr_region->is_empty() && !curr_region->is_pinned(),
642 "Region already in use (index %u)", curr_region->hrm_index());
643 if (open) {
644 curr_region->set_open_archive();
645 } else {
646 curr_region->set_closed_archive();
647 }
648 _hr_printer.alloc(curr_region);
649 _archive_set.add(curr_region);
650 HeapWord* top;
651 HeapRegion* next_region;
652 if (curr_region != last_region) {
653 top = curr_region->end();
654 next_region = _hrm->next_region_in_heap(curr_region);
655 } else {
656 top = last_address + 1;
657 next_region = NULL;
658 }
659 curr_region->set_top(top);
660 curr_region->set_first_dead(top);
661 curr_region->set_end_of_live(top);
662 curr_region = next_region;
663 }
664
665 // Notify mark-sweep of the archive
666 G1ArchiveAllocator::set_range_archive(curr_range, open);
667 }
668 return true;
669 }
670
671 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
672 assert(!is_init_completed(), "Expect to be called at JVM init time");
673 assert(ranges != NULL, "MemRegion array NULL");
674 assert(count != 0, "No MemRegions provided");
675 MemRegion reserved = _hrm->reserved();
676 HeapWord *prev_last_addr = NULL;
677 HeapRegion* prev_last_region = NULL;
678
679 // For each MemRegion, create filler objects, if needed, in the G1 regions
680 // that contain the address range. The address range actually within the
681 // MemRegion will not be modified. That is assumed to have been initialized
682 // elsewhere, probably via an mmap of archived heap data.
683 MutexLockerEx x(Heap_lock);
684 for (size_t i = 0; i < count; i++) {
685 HeapWord* start_address = ranges[i].start();
686 HeapWord* last_address = ranges[i].last();
687
688 assert(reserved.contains(start_address) && reserved.contains(last_address),
689 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
690 p2i(start_address), p2i(last_address));
691 assert(start_address > prev_last_addr,
692 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
693 p2i(start_address), p2i(prev_last_addr));
694
695 HeapRegion* start_region = _hrm->addr_to_region(start_address);
696 HeapRegion* last_region = _hrm->addr_to_region(last_address);
697 HeapWord* bottom_address = start_region->bottom();
698
699 // Check for a range beginning in the same region in which the
700 // previous one ended.
701 if (start_region == prev_last_region) {
702 bottom_address = prev_last_addr + 1;
703 }
704
705 // Verify that the regions were all marked as archive regions by
706 // alloc_archive_regions.
707 HeapRegion* curr_region = start_region;
708 while (curr_region != NULL) {
709 guarantee(curr_region->is_archive(),
710 "Expected archive region at index %u", curr_region->hrm_index());
711 if (curr_region != last_region) {
712 curr_region = _hrm->next_region_in_heap(curr_region);
713 } else {
714 curr_region = NULL;
715 }
716 }
717
718 prev_last_addr = last_address;
719 prev_last_region = last_region;
720
721 // Fill the memory below the allocated range with dummy object(s),
722 // if the region bottom does not match the range start, or if the previous
723 // range ended within the same G1 region, and there is a gap.
724 if (start_address != bottom_address) {
725 size_t fill_size = pointer_delta(start_address, bottom_address);
726 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
727 increase_used(fill_size * HeapWordSize);
728 }
729 }
730 }
731
732 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
733 size_t desired_word_size,
734 size_t* actual_word_size) {
735 assert_heap_not_locked_and_not_at_safepoint();
736 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
737 "be called for humongous allocation requests");
738
739 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
740
741 if (result == NULL) {
742 *actual_word_size = desired_word_size;
743 result = attempt_allocation_slow(desired_word_size);
744 }
745
746 assert_heap_not_locked();
747 if (result != NULL) {
748 assert(*actual_word_size != 0, "Actual size must have been set here");
749 dirty_young_block(result, *actual_word_size);
750 } else {
751 *actual_word_size = 0;
752 }
753
754 return result;
755 }
756
757 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
758 assert(!is_init_completed(), "Expect to be called at JVM init time");
759 assert(ranges != NULL, "MemRegion array NULL");
760 assert(count != 0, "No MemRegions provided");
761 MemRegion reserved = _hrm->reserved();
762 HeapWord* prev_last_addr = NULL;
763 HeapRegion* prev_last_region = NULL;
764 size_t size_used = 0;
765 size_t uncommitted_regions = 0;
766
767 // For each Memregion, free the G1 regions that constitute it, and
768 // notify mark-sweep that the range is no longer to be considered 'archive.'
769 MutexLockerEx x(Heap_lock);
770 for (size_t i = 0; i < count; i++) {
771 HeapWord* start_address = ranges[i].start();
772 HeapWord* last_address = ranges[i].last();
773
774 assert(reserved.contains(start_address) && reserved.contains(last_address),
775 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
776 p2i(start_address), p2i(last_address));
777 assert(start_address > prev_last_addr,
778 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
779 p2i(start_address), p2i(prev_last_addr));
780 size_used += ranges[i].byte_size();
781 prev_last_addr = last_address;
782
783 HeapRegion* start_region = _hrm->addr_to_region(start_address);
784 HeapRegion* last_region = _hrm->addr_to_region(last_address);
785
786 // Check for ranges that start in the same G1 region in which the previous
787 // range ended, and adjust the start address so we don't try to free
788 // the same region again. If the current range is entirely within that
789 // region, skip it.
790 if (start_region == prev_last_region) {
791 start_address = start_region->end();
792 if (start_address > last_address) {
793 continue;
794 }
795 start_region = _hrm->addr_to_region(start_address);
796 }
797 prev_last_region = last_region;
798
799 // After verifying that each region was marked as an archive region by
800 // alloc_archive_regions, set it free and empty and uncommit it.
801 HeapRegion* curr_region = start_region;
802 while (curr_region != NULL) {
803 guarantee(curr_region->is_archive(),
804 "Expected archive region at index %u", curr_region->hrm_index());
805 uint curr_index = curr_region->hrm_index();
806 _archive_set.remove(curr_region);
807 curr_region->set_free();
808 curr_region->set_top(curr_region->bottom());
809 if (curr_region != last_region) {
810 curr_region = _hrm->next_region_in_heap(curr_region);
811 } else {
812 curr_region = NULL;
813 }
814 _hrm->shrink_at(curr_index, 1);
815 uncommitted_regions++;
816 }
817
818 // Notify mark-sweep that this is no longer an archive range.
819 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
820 }
821
822 if (uncommitted_regions != 0) {
823 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
824 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
825 }
826 decrease_used(size_used);
827 }
828
829 oop G1CollectedHeap::materialize_archived_object(oop obj) {
830 assert(obj != NULL, "archived obj is NULL");
831 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
832
833 // Loading an archived object makes it strongly reachable. If it is
834 // loaded during concurrent marking, it must be enqueued to the SATB
835 // queue, shading the previously white object gray.
836 G1BarrierSet::enqueue(obj);
837
838 return obj;
839 }
840
841 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
842 ResourceMark rm; // For retrieving the thread names in log messages.
843
844 // The structure of this method has a lot of similarities to
845 // attempt_allocation_slow(). The reason these two were not merged
846 // into a single one is that such a method would require several "if
847 // allocation is not humongous do this, otherwise do that"
848 // conditional paths which would obscure its flow. In fact, an early
849 // version of this code did use a unified method which was harder to
850 // follow and, as a result, it had subtle bugs that were hard to
851 // track down. So keeping these two methods separate allows each to
852 // be more readable. It will be good to keep these two in sync as
853 // much as possible.
854
855 assert_heap_not_locked_and_not_at_safepoint();
856 assert(is_humongous(word_size), "attempt_allocation_humongous() "
857 "should only be called for humongous allocations");
858
859 // Humongous objects can exhaust the heap quickly, so we should check if we
860 // need to start a marking cycle at each humongous object allocation. We do
861 // the check before we do the actual allocation. The reason for doing it
862 // before the allocation is that we avoid having to keep track of the newly
863 // allocated memory while we do a GC.
864 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
865 word_size)) {
866 collect(GCCause::_g1_humongous_allocation);
867 }
868
869 // We will loop until a) we manage to successfully perform the
870 // allocation or b) we successfully schedule a collection which
871 // fails to perform the allocation. b) is the only case when we'll
872 // return NULL.
873 HeapWord* result = NULL;
874 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
875 bool should_try_gc;
876 uint gc_count_before;
877
878
879 {
880 MutexLockerEx x(Heap_lock);
881
882 // Given that humongous objects are not allocated in young
883 // regions, we'll first try to do the allocation without doing a
884 // collection hoping that there's enough space in the heap.
885 result = humongous_obj_allocate(word_size);
886 if (result != NULL) {
887 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
888 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
889 return result;
890 }
891
892 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
893 // the GCLocker initiated GC has been performed and then retry. This includes
894 // the case when the GC Locker is not active but has not been performed.
895 should_try_gc = !GCLocker::needs_gc();
896 // Read the GC count while still holding the Heap_lock.
897 gc_count_before = total_collections();
898 }
899
900 if (should_try_gc) {
901 bool succeeded;
902 result = do_collection_pause(word_size, gc_count_before, &succeeded,
903 GCCause::_g1_humongous_allocation);
904 if (result != NULL) {
905 assert(succeeded, "only way to get back a non-NULL result");
906 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
907 Thread::current()->name(), p2i(result));
908 return result;
909 }
910
911 if (succeeded) {
912 // We successfully scheduled a collection which failed to allocate. No
913 // point in trying to allocate further. We'll just return NULL.
914 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
915 SIZE_FORMAT " words", Thread::current()->name(), word_size);
916 return NULL;
917 }
918 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
919 Thread::current()->name(), word_size);
920 } else {
921 // Failed to schedule a collection.
922 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
923 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
924 SIZE_FORMAT " words", Thread::current()->name(), word_size);
925 return NULL;
926 }
927 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
928 // The GCLocker is either active or the GCLocker initiated
929 // GC has not yet been performed. Stall until it is and
930 // then retry the allocation.
931 GCLocker::stall_until_clear();
932 gclocker_retry_count += 1;
933 }
934
935
936 // We can reach here if we were unsuccessful in scheduling a
937 // collection (because another thread beat us to it) or if we were
938 // stalled due to the GC locker. In either can we should retry the
939 // allocation attempt in case another thread successfully
940 // performed a collection and reclaimed enough space.
941 // Humongous object allocation always needs a lock, so we wait for the retry
942 // in the next iteration of the loop, unlike for the regular iteration case.
943 // Give a warning if we seem to be looping forever.
944
945 if ((QueuedAllocationWarningCount > 0) &&
946 (try_count % QueuedAllocationWarningCount == 0)) {
947 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
948 Thread::current()->name(), try_count, word_size);
949 }
950 }
951
952 ShouldNotReachHere();
953 return NULL;
954 }
955
956 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
957 bool expect_null_mutator_alloc_region) {
958 assert_at_safepoint_on_vm_thread();
959 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
960 "the current alloc region was unexpectedly found to be non-NULL");
961
962 if (!is_humongous(word_size)) {
963 return _allocator->attempt_allocation_locked(word_size);
964 } else {
965 HeapWord* result = humongous_obj_allocate(word_size);
966 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
967 collector_state()->set_initiate_conc_mark_if_possible(true);
968 }
969 return result;
970 }
971
972 ShouldNotReachHere();
973 }
974
975 class PostCompactionPrinterClosure: public HeapRegionClosure {
976 private:
977 G1HRPrinter* _hr_printer;
978 public:
979 bool do_heap_region(HeapRegion* hr) {
980 assert(!hr->is_young(), "not expecting to find young regions");
981 _hr_printer->post_compaction(hr);
982 return false;
983 }
984
985 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
986 : _hr_printer(hr_printer) { }
987 };
988
989 void G1CollectedHeap::print_hrm_post_compaction() {
990 if (_hr_printer.is_active()) {
991 PostCompactionPrinterClosure cl(hr_printer());
992 heap_region_iterate(&cl);
993 }
994 }
995
996 void G1CollectedHeap::abort_concurrent_cycle() {
997 // If we start the compaction before the CM threads finish
998 // scanning the root regions we might trip them over as we'll
999 // be moving objects / updating references. So let's wait until
1000 // they are done. By telling them to abort, they should complete
1001 // early.
1002 _cm->root_regions()->abort();
1003 _cm->root_regions()->wait_until_scan_finished();
1004
1005 // Disable discovery and empty the discovered lists
1006 // for the CM ref processor.
1007 _ref_processor_cm->disable_discovery();
1008 _ref_processor_cm->abandon_partial_discovery();
1009 _ref_processor_cm->verify_no_references_recorded();
1010
1011 // Abandon current iterations of concurrent marking and concurrent
1012 // refinement, if any are in progress.
1013 concurrent_mark()->concurrent_cycle_abort();
1014 }
1015
1016 void G1CollectedHeap::prepare_heap_for_full_collection() {
1017 // Make sure we'll choose a new allocation region afterwards.
1018 _allocator->release_mutator_alloc_region();
1019 _allocator->abandon_gc_alloc_regions();
1020
1021 // We may have added regions to the current incremental collection
1022 // set between the last GC or pause and now. We need to clear the
1023 // incremental collection set and then start rebuilding it afresh
1024 // after this full GC.
1025 abandon_collection_set(collection_set());
1026
1027 tear_down_region_sets(false /* free_list_only */);
1028
1029 hrm()->prepare_for_full_collection_start();
1030 }
1031
1032 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1033 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1034 assert(used() == recalculate_used(), "Should be equal");
1035 _verifier->verify_region_sets_optional();
1036 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1037 _verifier->check_bitmaps("Full GC Start");
1038 }
1039
1040 void G1CollectedHeap::prepare_heap_for_mutators() {
1041 hrm()->prepare_for_full_collection_end();
1042
1043 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1044 ClassLoaderDataGraph::purge();
1045 MetaspaceUtils::verify_metrics();
1046
1047 // Prepare heap for normal collections.
1048 assert(num_free_regions() == 0, "we should not have added any free regions");
1049 rebuild_region_sets(false /* free_list_only */);
1050 abort_refinement();
1051 resize_heap_if_necessary();
1052
1053 // Rebuild the strong code root lists for each region
1054 rebuild_strong_code_roots();
1055
1056 // Purge code root memory
1057 purge_code_root_memory();
1058
1059 // Start a new incremental collection set for the next pause
1060 start_new_collection_set();
1061
1062 _allocator->init_mutator_alloc_region();
1063
1064 // Post collection state updates.
1065 MetaspaceGC::compute_new_size();
1066 }
1067
1068 void G1CollectedHeap::abort_refinement() {
1069 if (_hot_card_cache->use_cache()) {
1070 _hot_card_cache->reset_hot_cache();
1071 }
1072
1073 // Discard all remembered set updates.
1074 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1075 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1076 }
1077
1078 void G1CollectedHeap::verify_after_full_collection() {
1079 _hrm->verify_optional();
1080 _verifier->verify_region_sets_optional();
1081 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1082 // Clear the previous marking bitmap, if needed for bitmap verification.
1083 // Note we cannot do this when we clear the next marking bitmap in
1084 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1085 // objects marked during a full GC against the previous bitmap.
1086 // But we need to clear it before calling check_bitmaps below since
1087 // the full GC has compacted objects and updated TAMS but not updated
1088 // the prev bitmap.
1089 if (G1VerifyBitmaps) {
1090 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1091 _cm->clear_prev_bitmap(workers());
1092 }
1093 // This call implicitly verifies that the next bitmap is clear after Full GC.
1094 _verifier->check_bitmaps("Full GC End");
1095
1096 // At this point there should be no regions in the
1097 // entire heap tagged as young.
1098 assert(check_young_list_empty(), "young list should be empty at this point");
1099
1100 // Note: since we've just done a full GC, concurrent
1101 // marking is no longer active. Therefore we need not
1102 // re-enable reference discovery for the CM ref processor.
1103 // That will be done at the start of the next marking cycle.
1104 // We also know that the STW processor should no longer
1105 // discover any new references.
1106 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1107 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1108 _ref_processor_stw->verify_no_references_recorded();
1109 _ref_processor_cm->verify_no_references_recorded();
1110 }
1111
1112 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1113 // Post collection logging.
1114 // We should do this after we potentially resize the heap so
1115 // that all the COMMIT / UNCOMMIT events are generated before
1116 // the compaction events.
1117 print_hrm_post_compaction();
1118 heap_transition->print();
1119 print_heap_after_gc();
1120 print_heap_regions();
1121 #ifdef TRACESPINNING
1122 ParallelTaskTerminator::print_termination_counts();
1123 #endif
1124 }
1125
1126 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1127 bool clear_all_soft_refs) {
1128 assert_at_safepoint_on_vm_thread();
1129
1130 if (GCLocker::check_active_before_gc()) {
1131 // Full GC was not completed.
1132 return false;
1133 }
1134
1135 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1136 soft_ref_policy()->should_clear_all_soft_refs();
1137
1138 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1139 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1140
1141 collector.prepare_collection();
1142 collector.collect();
1143 collector.complete_collection();
1144
1145 // Full collection was successfully completed.
1146 return true;
1147 }
1148
1149 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1150 // Currently, there is no facility in the do_full_collection(bool) API to notify
1151 // the caller that the collection did not succeed (e.g., because it was locked
1152 // out by the GC locker). So, right now, we'll ignore the return value.
1153 bool dummy = do_full_collection(true, /* explicit_gc */
1154 clear_all_soft_refs);
1155 }
1156
1157 void G1CollectedHeap::resize_heap_if_necessary() {
1158 assert_at_safepoint_on_vm_thread();
1159
1160 // Capacity, free and used after the GC counted as full regions to
1161 // include the waste in the following calculations.
1162 const size_t capacity_after_gc = capacity();
1163 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1164
1165 // This is enforced in arguments.cpp.
1166 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1167 "otherwise the code below doesn't make sense");
1168
1169 // We don't have floating point command-line arguments
1170 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1171 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1172 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1173 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1174
1175 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1176 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1177
1178 // We have to be careful here as these two calculations can overflow
1179 // 32-bit size_t's.
1180 double used_after_gc_d = (double) used_after_gc;
1181 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1182 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1183
1184 // Let's make sure that they are both under the max heap size, which
1185 // by default will make them fit into a size_t.
1186 double desired_capacity_upper_bound = (double) max_heap_size;
1187 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1188 desired_capacity_upper_bound);
1189 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1190 desired_capacity_upper_bound);
1191
1192 // We can now safely turn them into size_t's.
1193 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1194 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1195
1196 // This assert only makes sense here, before we adjust them
1197 // with respect to the min and max heap size.
1198 assert(minimum_desired_capacity <= maximum_desired_capacity,
1199 "minimum_desired_capacity = " SIZE_FORMAT ", "
1200 "maximum_desired_capacity = " SIZE_FORMAT,
1201 minimum_desired_capacity, maximum_desired_capacity);
1202
1203 // Should not be greater than the heap max size. No need to adjust
1204 // it with respect to the heap min size as it's a lower bound (i.e.,
1205 // we'll try to make the capacity larger than it, not smaller).
1206 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1207 // Should not be less than the heap min size. No need to adjust it
1208 // with respect to the heap max size as it's an upper bound (i.e.,
1209 // we'll try to make the capacity smaller than it, not greater).
1210 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1211
1212 if (capacity_after_gc < minimum_desired_capacity) {
1213 // Don't expand unless it's significant
1214 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1215
1216 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1217 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1218 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1219 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1220
1221 expand(expand_bytes, _workers);
1222
1223 // No expansion, now see if we want to shrink
1224 } else if (capacity_after_gc > maximum_desired_capacity) {
1225 // Capacity too large, compute shrinking size
1226 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1227
1228 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1229 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1230 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1231 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1232
1233 shrink(shrink_bytes);
1234 }
1235 }
1236
1237 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1238 bool do_gc,
1239 bool clear_all_soft_refs,
1240 bool expect_null_mutator_alloc_region,
1241 bool* gc_succeeded) {
1242 *gc_succeeded = true;
1243 // Let's attempt the allocation first.
1244 HeapWord* result =
1245 attempt_allocation_at_safepoint(word_size,
1246 expect_null_mutator_alloc_region);
1247 if (result != NULL) {
1248 return result;
1249 }
1250
1251 // In a G1 heap, we're supposed to keep allocation from failing by
1252 // incremental pauses. Therefore, at least for now, we'll favor
1253 // expansion over collection. (This might change in the future if we can
1254 // do something smarter than full collection to satisfy a failed alloc.)
1255 result = expand_and_allocate(word_size);
1256 if (result != NULL) {
1257 return result;
1258 }
1259
1260 if (do_gc) {
1261 // Expansion didn't work, we'll try to do a Full GC.
1262 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1263 clear_all_soft_refs);
1264 }
1265
1266 return NULL;
1267 }
1268
1269 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1270 bool* succeeded) {
1271 assert_at_safepoint_on_vm_thread();
1272
1273 // Attempts to allocate followed by Full GC.
1274 HeapWord* result =
1275 satisfy_failed_allocation_helper(word_size,
1276 true, /* do_gc */
1277 false, /* clear_all_soft_refs */
1278 false, /* expect_null_mutator_alloc_region */
1279 succeeded);
1280
1281 if (result != NULL || !*succeeded) {
1282 return result;
1283 }
1284
1285 // Attempts to allocate followed by Full GC that will collect all soft references.
1286 result = satisfy_failed_allocation_helper(word_size,
1287 true, /* do_gc */
1288 true, /* clear_all_soft_refs */
1289 true, /* expect_null_mutator_alloc_region */
1290 succeeded);
1291
1292 if (result != NULL || !*succeeded) {
1293 return result;
1294 }
1295
1296 // Attempts to allocate, no GC
1297 result = satisfy_failed_allocation_helper(word_size,
1298 false, /* do_gc */
1299 false, /* clear_all_soft_refs */
1300 true, /* expect_null_mutator_alloc_region */
1301 succeeded);
1302
1303 if (result != NULL) {
1304 return result;
1305 }
1306
1307 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1308 "Flag should have been handled and cleared prior to this point");
1309
1310 // What else? We might try synchronous finalization later. If the total
1311 // space available is large enough for the allocation, then a more
1312 // complete compaction phase than we've tried so far might be
1313 // appropriate.
1314 return NULL;
1315 }
1316
1317 // Attempting to expand the heap sufficiently
1318 // to support an allocation of the given "word_size". If
1319 // successful, perform the allocation and return the address of the
1320 // allocated block, or else "NULL".
1321
1322 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1323 assert_at_safepoint_on_vm_thread();
1324
1325 _verifier->verify_region_sets_optional();
1326
1327 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1328 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1329 word_size * HeapWordSize);
1330
1331
1332 if (expand(expand_bytes, _workers)) {
1333 _hrm->verify_optional();
1334 _verifier->verify_region_sets_optional();
1335 return attempt_allocation_at_safepoint(word_size,
1336 false /* expect_null_mutator_alloc_region */);
1337 }
1338 return NULL;
1339 }
1340
1341 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1342 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1343 aligned_expand_bytes = align_up(aligned_expand_bytes,
1344 HeapRegion::GrainBytes);
1345
1346 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1347 expand_bytes, aligned_expand_bytes);
1348
1349 if (is_maximal_no_gc()) {
1350 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1351 return false;
1352 }
1353
1354 double expand_heap_start_time_sec = os::elapsedTime();
1355 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1356 assert(regions_to_expand > 0, "Must expand by at least one region");
1357
1358 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1359 if (expand_time_ms != NULL) {
1360 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1361 }
1362
1363 if (expanded_by > 0) {
1364 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1365 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1366 policy()->record_new_heap_size(num_regions());
1367 } else {
1368 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1369
1370 // The expansion of the virtual storage space was unsuccessful.
1371 // Let's see if it was because we ran out of swap.
1372 if (G1ExitOnExpansionFailure &&
1373 _hrm->available() >= regions_to_expand) {
1374 // We had head room...
1375 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1376 }
1377 }
1378 return regions_to_expand > 0;
1379 }
1380
1381 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1382 size_t aligned_shrink_bytes =
1383 ReservedSpace::page_align_size_down(shrink_bytes);
1384 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1385 HeapRegion::GrainBytes);
1386 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1387
1388 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1389 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1390
1391
1392 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1393 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1394 if (num_regions_removed > 0) {
1395 policy()->record_new_heap_size(num_regions());
1396 } else {
1397 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1398 }
1399 }
1400
1401 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1402 _verifier->verify_region_sets_optional();
1403
1404 // We should only reach here at the end of a Full GC or during Remark which
1405 // means we should not not be holding to any GC alloc regions. The method
1406 // below will make sure of that and do any remaining clean up.
1407 _allocator->abandon_gc_alloc_regions();
1408
1409 // Instead of tearing down / rebuilding the free lists here, we
1410 // could instead use the remove_all_pending() method on free_list to
1411 // remove only the ones that we need to remove.
1412 tear_down_region_sets(true /* free_list_only */);
1413 shrink_helper(shrink_bytes);
1414 rebuild_region_sets(true /* free_list_only */);
1415
1416 _hrm->verify_optional();
1417 _verifier->verify_region_sets_optional();
1418 }
1419
1420 class OldRegionSetChecker : public HeapRegionSetChecker {
1421 public:
1422 void check_mt_safety() {
1423 // Master Old Set MT safety protocol:
1424 // (a) If we're at a safepoint, operations on the master old set
1425 // should be invoked:
1426 // - by the VM thread (which will serialize them), or
1427 // - by the GC workers while holding the FreeList_lock, if we're
1428 // at a safepoint for an evacuation pause (this lock is taken
1429 // anyway when an GC alloc region is retired so that a new one
1430 // is allocated from the free list), or
1431 // - by the GC workers while holding the OldSets_lock, if we're at a
1432 // safepoint for a cleanup pause.
1433 // (b) If we're not at a safepoint, operations on the master old set
1434 // should be invoked while holding the Heap_lock.
1435
1436 if (SafepointSynchronize::is_at_safepoint()) {
1437 guarantee(Thread::current()->is_VM_thread() ||
1438 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1439 "master old set MT safety protocol at a safepoint");
1440 } else {
1441 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1442 }
1443 }
1444 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1445 const char* get_description() { return "Old Regions"; }
1446 };
1447
1448 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1449 public:
1450 void check_mt_safety() {
1451 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1452 "May only change archive regions during initialization or safepoint.");
1453 }
1454 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1455 const char* get_description() { return "Archive Regions"; }
1456 };
1457
1458 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1459 public:
1460 void check_mt_safety() {
1461 // Humongous Set MT safety protocol:
1462 // (a) If we're at a safepoint, operations on the master humongous
1463 // set should be invoked by either the VM thread (which will
1464 // serialize them) or by the GC workers while holding the
1465 // OldSets_lock.
1466 // (b) If we're not at a safepoint, operations on the master
1467 // humongous set should be invoked while holding the Heap_lock.
1468
1469 if (SafepointSynchronize::is_at_safepoint()) {
1470 guarantee(Thread::current()->is_VM_thread() ||
1471 OldSets_lock->owned_by_self(),
1472 "master humongous set MT safety protocol at a safepoint");
1473 } else {
1474 guarantee(Heap_lock->owned_by_self(),
1475 "master humongous set MT safety protocol outside a safepoint");
1476 }
1477 }
1478 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1479 const char* get_description() { return "Humongous Regions"; }
1480 };
1481
1482 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1483 CollectedHeap(),
1484 _young_gen_sampling_thread(NULL),
1485 _workers(NULL),
1486 _collector_policy(collector_policy),
1487 _card_table(NULL),
1488 _soft_ref_policy(),
1489 _old_set("Old Region Set", new OldRegionSetChecker()),
1490 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1491 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1492 _bot(NULL),
1493 _listener(),
1494 _hrm(NULL),
1495 _allocator(NULL),
1496 _verifier(NULL),
1497 _summary_bytes_used(0),
1498 _archive_allocator(NULL),
1499 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1500 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1501 _expand_heap_after_alloc_failure(true),
1502 _g1mm(NULL),
1503 _humongous_reclaim_candidates(),
1504 _has_humongous_reclaim_candidates(false),
1505 _hr_printer(),
1506 _collector_state(),
1507 _old_marking_cycles_started(0),
1508 _old_marking_cycles_completed(0),
1509 _eden(),
1510 _survivor(),
1511 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1512 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1513 _policy(G1Policy::create_policy(collector_policy, _gc_timer_stw)),
1514 _heap_sizing_policy(NULL),
1515 _collection_set(this, _policy),
1516 _hot_card_cache(NULL),
1517 _rem_set(NULL),
1518 _dirty_card_queue_set(false),
1519 _cm(NULL),
1520 _cm_thread(NULL),
1521 _cr(NULL),
1522 _task_queues(NULL),
1523 _evacuation_failed(false),
1524 _evacuation_failed_info_array(NULL),
1525 _preserved_marks_set(true /* in_c_heap */),
1526 #ifndef PRODUCT
1527 _evacuation_failure_alot_for_current_gc(false),
1528 _evacuation_failure_alot_gc_number(0),
1529 _evacuation_failure_alot_count(0),
1530 #endif
1531 _ref_processor_stw(NULL),
1532 _is_alive_closure_stw(this),
1533 _is_subject_to_discovery_stw(this),
1534 _ref_processor_cm(NULL),
1535 _is_alive_closure_cm(this),
1536 _is_subject_to_discovery_cm(this),
1537 _in_cset_fast_test() {
1538
1539 _verifier = new G1HeapVerifier(this);
1540
1541 _allocator = new G1Allocator(this);
1542
1543 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1544
1545 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1546
1547 // Override the default _filler_array_max_size so that no humongous filler
1548 // objects are created.
1549 _filler_array_max_size = _humongous_object_threshold_in_words;
1550
1551 uint n_queues = ParallelGCThreads;
1552 _task_queues = new RefToScanQueueSet(n_queues);
1553
1554 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1555
1556 for (uint i = 0; i < n_queues; i++) {
1557 RefToScanQueue* q = new RefToScanQueue();
1558 q->initialize();
1559 _task_queues->register_queue(i, q);
1560 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1561 }
1562
1563 // Initialize the G1EvacuationFailureALot counters and flags.
1564 NOT_PRODUCT(reset_evacuation_should_fail();)
1565
1566 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1567 }
1568
1569 static size_t actual_reserved_page_size(ReservedSpace rs) {
1570 size_t page_size = os::vm_page_size();
1571 if (UseLargePages) {
1572 // There are two ways to manage large page memory.
1573 // 1. OS supports committing large page memory.
1574 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1575 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1576 // we reserved memory without large page.
1577 if (os::can_commit_large_page_memory() || rs.special()) {
1578 page_size = rs.alignment();
1579 }
1580 }
1581
1582 return page_size;
1583 }
1584
1585 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1586 size_t size,
1587 size_t translation_factor) {
1588 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1589 // Allocate a new reserved space, preferring to use large pages.
1590 ReservedSpace rs(size, preferred_page_size);
1591 size_t page_size = actual_reserved_page_size(rs);
1592 G1RegionToSpaceMapper* result =
1593 G1RegionToSpaceMapper::create_mapper(rs,
1594 size,
1595 page_size,
1596 HeapRegion::GrainBytes,
1597 translation_factor,
1598 mtGC);
1599
1600 os::trace_page_sizes_for_requested_size(description,
1601 size,
1602 preferred_page_size,
1603 page_size,
1604 rs.base(),
1605 rs.size());
1606
1607 return result;
1608 }
1609
1610 jint G1CollectedHeap::initialize_concurrent_refinement() {
1611 jint ecode = JNI_OK;
1612 _cr = G1ConcurrentRefine::create(&ecode);
1613 return ecode;
1614 }
1615
1616 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1617 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1618 if (_young_gen_sampling_thread->osthread() == NULL) {
1619 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1620 return JNI_ENOMEM;
1621 }
1622 return JNI_OK;
1623 }
1624
1625 jint G1CollectedHeap::initialize() {
1626 os::enable_vtime();
1627
1628 // Necessary to satisfy locking discipline assertions.
1629
1630 MutexLocker x(Heap_lock);
1631
1632 // While there are no constraints in the GC code that HeapWordSize
1633 // be any particular value, there are multiple other areas in the
1634 // system which believe this to be true (e.g. oop->object_size in some
1635 // cases incorrectly returns the size in wordSize units rather than
1636 // HeapWordSize).
1637 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1638
1639 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1640 size_t max_byte_size = _collector_policy->heap_reserved_size_bytes();
1641 size_t heap_alignment = collector_policy()->heap_alignment();
1642
1643 // Ensure that the sizes are properly aligned.
1644 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1645 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1646 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1647
1648 // Reserve the maximum.
1649
1650 // When compressed oops are enabled, the preferred heap base
1651 // is calculated by subtracting the requested size from the
1652 // 32Gb boundary and using the result as the base address for
1653 // heap reservation. If the requested size is not aligned to
1654 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1655 // into the ReservedHeapSpace constructor) then the actual
1656 // base of the reserved heap may end up differing from the
1657 // address that was requested (i.e. the preferred heap base).
1658 // If this happens then we could end up using a non-optimal
1659 // compressed oops mode.
1660
1661 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1662 heap_alignment);
1663
1664 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1665
1666 // Create the barrier set for the entire reserved region.
1667 G1CardTable* ct = new G1CardTable(reserved_region());
1668 ct->initialize();
1669 G1BarrierSet* bs = new G1BarrierSet(ct);
1670 bs->initialize();
1671 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1672 BarrierSet::set_barrier_set(bs);
1673 _card_table = ct;
1674
1675 G1BarrierSet::satb_mark_queue_set().initialize(this,
1676 SATB_Q_CBL_mon,
1677 &bs->satb_mark_queue_buffer_allocator(),
1678 G1SATBProcessCompletedThreshold,
1679 G1SATBBufferEnqueueingThresholdPercent,
1680 Shared_SATB_Q_lock);
1681
1682 // process_completed_buffers_threshold and max_completed_buffers are updated
1683 // later, based on the concurrent refinement object.
1684 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1685 &bs->dirty_card_queue_buffer_allocator(),
1686 Shared_DirtyCardQ_lock,
1687 true); // init_free_ids
1688
1689 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1690 &bs->dirty_card_queue_buffer_allocator(),
1691 Shared_DirtyCardQ_lock);
1692
1693 // Create the hot card cache.
1694 _hot_card_cache = new G1HotCardCache(this);
1695
1696 // Carve out the G1 part of the heap.
1697 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1698 size_t page_size = actual_reserved_page_size(heap_rs);
1699 G1RegionToSpaceMapper* heap_storage =
1700 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1701 g1_rs.size(),
1702 page_size,
1703 HeapRegion::GrainBytes,
1704 1,
1705 mtJavaHeap);
1706 if(heap_storage == NULL) {
1707 vm_shutdown_during_initialization("Could not initialize G1 heap");
1708 return JNI_ERR;
1709 }
1710
1711 os::trace_page_sizes("Heap",
1712 collector_policy()->min_heap_byte_size(),
1713 max_byte_size,
1714 page_size,
1715 heap_rs.base(),
1716 heap_rs.size());
1717 heap_storage->set_mapping_changed_listener(&_listener);
1718
1719 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1720 G1RegionToSpaceMapper* bot_storage =
1721 create_aux_memory_mapper("Block Offset Table",
1722 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1723 G1BlockOffsetTable::heap_map_factor());
1724
1725 G1RegionToSpaceMapper* cardtable_storage =
1726 create_aux_memory_mapper("Card Table",
1727 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1728 G1CardTable::heap_map_factor());
1729
1730 G1RegionToSpaceMapper* card_counts_storage =
1731 create_aux_memory_mapper("Card Counts Table",
1732 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1733 G1CardCounts::heap_map_factor());
1734
1735 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1736 G1RegionToSpaceMapper* prev_bitmap_storage =
1737 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1738 G1RegionToSpaceMapper* next_bitmap_storage =
1739 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1740
1741 _hrm = HeapRegionManager::create_manager(this, _collector_policy);
1742
1743 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1744 _card_table->initialize(cardtable_storage);
1745 // Do later initialization work for concurrent refinement.
1746 _hot_card_cache->initialize(card_counts_storage);
1747
1748 // 6843694 - ensure that the maximum region index can fit
1749 // in the remembered set structures.
1750 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1751 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1752
1753 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1754 // start within the first card.
1755 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1756 // Also create a G1 rem set.
1757 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1758 _rem_set->initialize(max_reserved_capacity(), max_regions());
1759
1760 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1761 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1762 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1763 "too many cards per region");
1764
1765 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1766
1767 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1768
1769 {
1770 HeapWord* start = _hrm->reserved().start();
1771 HeapWord* end = _hrm->reserved().end();
1772 size_t granularity = HeapRegion::GrainBytes;
1773
1774 _in_cset_fast_test.initialize(start, end, granularity);
1775 _humongous_reclaim_candidates.initialize(start, end, granularity);
1776 }
1777
1778 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1779 true /* are_GC_task_threads */,
1780 false /* are_ConcurrentGC_threads */);
1781 if (_workers == NULL) {
1782 return JNI_ENOMEM;
1783 }
1784 _workers->initialize_workers();
1785
1786 // Create the G1ConcurrentMark data structure and thread.
1787 // (Must do this late, so that "max_regions" is defined.)
1788 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1789 if (_cm == NULL || !_cm->completed_initialization()) {
1790 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1791 return JNI_ENOMEM;
1792 }
1793 _cm_thread = _cm->cm_thread();
1794
1795 // Now expand into the initial heap size.
1796 if (!expand(init_byte_size, _workers)) {
1797 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1798 return JNI_ENOMEM;
1799 }
1800
1801 // Perform any initialization actions delegated to the policy.
1802 policy()->init(this, &_collection_set);
1803
1804 jint ecode = initialize_concurrent_refinement();
1805 if (ecode != JNI_OK) {
1806 return ecode;
1807 }
1808
1809 ecode = initialize_young_gen_sampling_thread();
1810 if (ecode != JNI_OK) {
1811 return ecode;
1812 }
1813
1814 {
1815 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1816 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone());
1817 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone());
1818 }
1819
1820 // Here we allocate the dummy HeapRegion that is required by the
1821 // G1AllocRegion class.
1822 HeapRegion* dummy_region = _hrm->get_dummy_region();
1823
1824 // We'll re-use the same region whether the alloc region will
1825 // require BOT updates or not and, if it doesn't, then a non-young
1826 // region will complain that it cannot support allocations without
1827 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1828 dummy_region->set_eden();
1829 // Make sure it's full.
1830 dummy_region->set_top(dummy_region->end());
1831 G1AllocRegion::setup(this, dummy_region);
1832
1833 _allocator->init_mutator_alloc_region();
1834
1835 // Do create of the monitoring and management support so that
1836 // values in the heap have been properly initialized.
1837 _g1mm = new G1MonitoringSupport(this);
1838
1839 G1StringDedup::initialize();
1840
1841 _preserved_marks_set.init(ParallelGCThreads);
1842
1843 _collection_set.initialize(max_regions());
1844
1845 return JNI_OK;
1846 }
1847
1848 void G1CollectedHeap::stop() {
1849 // Stop all concurrent threads. We do this to make sure these threads
1850 // do not continue to execute and access resources (e.g. logging)
1851 // that are destroyed during shutdown.
1852 _cr->stop();
1853 _young_gen_sampling_thread->stop();
1854 _cm_thread->stop();
1855 if (G1StringDedup::is_enabled()) {
1856 G1StringDedup::stop();
1857 }
1858 }
1859
1860 void G1CollectedHeap::safepoint_synchronize_begin() {
1861 SuspendibleThreadSet::synchronize();
1862 }
1863
1864 void G1CollectedHeap::safepoint_synchronize_end() {
1865 SuspendibleThreadSet::desynchronize();
1866 }
1867
1868 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1869 return HeapRegion::max_region_size();
1870 }
1871
1872 void G1CollectedHeap::post_initialize() {
1873 CollectedHeap::post_initialize();
1874 ref_processing_init();
1875 }
1876
1877 void G1CollectedHeap::ref_processing_init() {
1878 // Reference processing in G1 currently works as follows:
1879 //
1880 // * There are two reference processor instances. One is
1881 // used to record and process discovered references
1882 // during concurrent marking; the other is used to
1883 // record and process references during STW pauses
1884 // (both full and incremental).
1885 // * Both ref processors need to 'span' the entire heap as
1886 // the regions in the collection set may be dotted around.
1887 //
1888 // * For the concurrent marking ref processor:
1889 // * Reference discovery is enabled at initial marking.
1890 // * Reference discovery is disabled and the discovered
1891 // references processed etc during remarking.
1892 // * Reference discovery is MT (see below).
1893 // * Reference discovery requires a barrier (see below).
1894 // * Reference processing may or may not be MT
1895 // (depending on the value of ParallelRefProcEnabled
1896 // and ParallelGCThreads).
1897 // * A full GC disables reference discovery by the CM
1898 // ref processor and abandons any entries on it's
1899 // discovered lists.
1900 //
1901 // * For the STW processor:
1902 // * Non MT discovery is enabled at the start of a full GC.
1903 // * Processing and enqueueing during a full GC is non-MT.
1904 // * During a full GC, references are processed after marking.
1905 //
1906 // * Discovery (may or may not be MT) is enabled at the start
1907 // of an incremental evacuation pause.
1908 // * References are processed near the end of a STW evacuation pause.
1909 // * For both types of GC:
1910 // * Discovery is atomic - i.e. not concurrent.
1911 // * Reference discovery will not need a barrier.
1912
1913 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1914
1915 // Concurrent Mark ref processor
1916 _ref_processor_cm =
1917 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1918 mt_processing, // mt processing
1919 ParallelGCThreads, // degree of mt processing
1920 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1921 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1922 false, // Reference discovery is not atomic
1923 &_is_alive_closure_cm, // is alive closure
1924 true); // allow changes to number of processing threads
1925
1926 // STW ref processor
1927 _ref_processor_stw =
1928 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1929 mt_processing, // mt processing
1930 ParallelGCThreads, // degree of mt processing
1931 (ParallelGCThreads > 1), // mt discovery
1932 ParallelGCThreads, // degree of mt discovery
1933 true, // Reference discovery is atomic
1934 &_is_alive_closure_stw, // is alive closure
1935 true); // allow changes to number of processing threads
1936 }
1937
1938 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1939 return _collector_policy;
1940 }
1941
1942 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1943 return &_soft_ref_policy;
1944 }
1945
1946 size_t G1CollectedHeap::capacity() const {
1947 return _hrm->length() * HeapRegion::GrainBytes;
1948 }
1949
1950 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1951 return _hrm->total_free_bytes();
1952 }
1953
1954 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1955 _hot_card_cache->drain(cl, worker_i);
1956 }
1957
1958 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1959 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1960 size_t n_completed_buffers = 0;
1961 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1962 n_completed_buffers++;
1963 }
1964 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!");
1965 phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1966 }
1967
1968 // Computes the sum of the storage used by the various regions.
1969 size_t G1CollectedHeap::used() const {
1970 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1971 if (_archive_allocator != NULL) {
1972 result += _archive_allocator->used();
1973 }
1974 return result;
1975 }
1976
1977 size_t G1CollectedHeap::used_unlocked() const {
1978 return _summary_bytes_used;
1979 }
1980
1981 class SumUsedClosure: public HeapRegionClosure {
1982 size_t _used;
1983 public:
1984 SumUsedClosure() : _used(0) {}
1985 bool do_heap_region(HeapRegion* r) {
1986 _used += r->used();
1987 return false;
1988 }
1989 size_t result() { return _used; }
1990 };
1991
1992 size_t G1CollectedHeap::recalculate_used() const {
1993 SumUsedClosure blk;
1994 heap_region_iterate(&blk);
1995 return blk.result();
1996 }
1997
1998 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1999 switch (cause) {
2000 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2001 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2002 case GCCause::_wb_conc_mark: return true;
2003 default : return false;
2004 }
2005 }
2006
2007 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2008 switch (cause) {
2009 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2010 case GCCause::_g1_humongous_allocation: return true;
2011 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2012 default: return is_user_requested_concurrent_full_gc(cause);
2013 }
2014 }
2015
2016 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2017 if(policy()->force_upgrade_to_full()) {
2018 return true;
2019 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2020 return false;
2021 } else if (has_regions_left_for_allocation()) {
2022 return false;
2023 } else {
2024 return true;
2025 }
2026 }
2027
2028 #ifndef PRODUCT
2029 void G1CollectedHeap::allocate_dummy_regions() {
2030 // Let's fill up most of the region
2031 size_t word_size = HeapRegion::GrainWords - 1024;
2032 // And as a result the region we'll allocate will be humongous.
2033 guarantee(is_humongous(word_size), "sanity");
2034
2035 // _filler_array_max_size is set to humongous object threshold
2036 // but temporarily change it to use CollectedHeap::fill_with_object().
2037 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2038
2039 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2040 // Let's use the existing mechanism for the allocation
2041 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2042 if (dummy_obj != NULL) {
2043 MemRegion mr(dummy_obj, word_size);
2044 CollectedHeap::fill_with_object(mr);
2045 } else {
2046 // If we can't allocate once, we probably cannot allocate
2047 // again. Let's get out of the loop.
2048 break;
2049 }
2050 }
2051 }
2052 #endif // !PRODUCT
2053
2054 void G1CollectedHeap::increment_old_marking_cycles_started() {
2055 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2056 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2057 "Wrong marking cycle count (started: %d, completed: %d)",
2058 _old_marking_cycles_started, _old_marking_cycles_completed);
2059
2060 _old_marking_cycles_started++;
2061 }
2062
2063 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2064 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2065
2066 // We assume that if concurrent == true, then the caller is a
2067 // concurrent thread that was joined the Suspendible Thread
2068 // Set. If there's ever a cheap way to check this, we should add an
2069 // assert here.
2070
2071 // Given that this method is called at the end of a Full GC or of a
2072 // concurrent cycle, and those can be nested (i.e., a Full GC can
2073 // interrupt a concurrent cycle), the number of full collections
2074 // completed should be either one (in the case where there was no
2075 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2076 // behind the number of full collections started.
2077
2078 // This is the case for the inner caller, i.e. a Full GC.
2079 assert(concurrent ||
2080 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2081 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2082 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2083 "is inconsistent with _old_marking_cycles_completed = %u",
2084 _old_marking_cycles_started, _old_marking_cycles_completed);
2085
2086 // This is the case for the outer caller, i.e. the concurrent cycle.
2087 assert(!concurrent ||
2088 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2089 "for outer caller (concurrent cycle): "
2090 "_old_marking_cycles_started = %u "
2091 "is inconsistent with _old_marking_cycles_completed = %u",
2092 _old_marking_cycles_started, _old_marking_cycles_completed);
2093
2094 _old_marking_cycles_completed += 1;
2095
2096 // We need to clear the "in_progress" flag in the CM thread before
2097 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2098 // is set) so that if a waiter requests another System.gc() it doesn't
2099 // incorrectly see that a marking cycle is still in progress.
2100 if (concurrent) {
2101 _cm_thread->set_idle();
2102 }
2103
2104 // This notify_all() will ensure that a thread that called
2105 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2106 // and it's waiting for a full GC to finish will be woken up. It is
2107 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2108 FullGCCount_lock->notify_all();
2109 }
2110
2111 void G1CollectedHeap::collect(GCCause::Cause cause) {
2112 try_collect(cause, true);
2113 }
2114
2115 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2116 assert_heap_not_locked();
2117
2118 bool gc_succeeded;
2119 bool should_retry_gc;
2120
2121 do {
2122 should_retry_gc = false;
2123
2124 uint gc_count_before;
2125 uint old_marking_count_before;
2126 uint full_gc_count_before;
2127
2128 {
2129 MutexLocker ml(Heap_lock);
2130
2131 // Read the GC count while holding the Heap_lock
2132 gc_count_before = total_collections();
2133 full_gc_count_before = total_full_collections();
2134 old_marking_count_before = _old_marking_cycles_started;
2135 }
2136
2137 if (should_do_concurrent_full_gc(cause)) {
2138 // Schedule an initial-mark evacuation pause that will start a
2139 // concurrent cycle. We're setting word_size to 0 which means that
2140 // we are not requesting a post-GC allocation.
2141 VM_G1CollectForAllocation op(0, /* word_size */
2142 gc_count_before,
2143 cause,
2144 true, /* should_initiate_conc_mark */
2145 policy()->max_pause_time_ms());
2146 VMThread::execute(&op);
2147 gc_succeeded = op.gc_succeeded();
2148 if (!gc_succeeded && retry_on_gc_failure) {
2149 if (old_marking_count_before == _old_marking_cycles_started) {
2150 should_retry_gc = op.should_retry_gc();
2151 } else {
2152 // A Full GC happened while we were trying to schedule the
2153 // concurrent cycle. No point in starting a new cycle given
2154 // that the whole heap was collected anyway.
2155 }
2156
2157 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2158 GCLocker::stall_until_clear();
2159 }
2160 }
2161 } else {
2162 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2163 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2164
2165 // Schedule a standard evacuation pause. We're setting word_size
2166 // to 0 which means that we are not requesting a post-GC allocation.
2167 VM_G1CollectForAllocation op(0, /* word_size */
2168 gc_count_before,
2169 cause,
2170 false, /* should_initiate_conc_mark */
2171 policy()->max_pause_time_ms());
2172 VMThread::execute(&op);
2173 gc_succeeded = op.gc_succeeded();
2174 } else {
2175 // Schedule a Full GC.
2176 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2177 VMThread::execute(&op);
2178 gc_succeeded = op.gc_succeeded();
2179 }
2180 }
2181 } while (should_retry_gc);
2182 return gc_succeeded;
2183 }
2184
2185 bool G1CollectedHeap::is_in(const void* p) const {
2186 if (_hrm->reserved().contains(p)) {
2187 // Given that we know that p is in the reserved space,
2188 // heap_region_containing() should successfully
2189 // return the containing region.
2190 HeapRegion* hr = heap_region_containing(p);
2191 return hr->is_in(p);
2192 } else {
2193 return false;
2194 }
2195 }
2196
2197 #ifdef ASSERT
2198 bool G1CollectedHeap::is_in_exact(const void* p) const {
2199 bool contains = reserved_region().contains(p);
2200 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2201 if (contains && available) {
2202 return true;
2203 } else {
2204 return false;
2205 }
2206 }
2207 #endif
2208
2209 // Iteration functions.
2210
2211 // Iterates an ObjectClosure over all objects within a HeapRegion.
2212
2213 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2214 ObjectClosure* _cl;
2215 public:
2216 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2217 bool do_heap_region(HeapRegion* r) {
2218 if (!r->is_continues_humongous()) {
2219 r->object_iterate(_cl);
2220 }
2221 return false;
2222 }
2223 };
2224
2225 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2226 IterateObjectClosureRegionClosure blk(cl);
2227 heap_region_iterate(&blk);
2228 }
2229
2230 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2231 _hrm->iterate(cl);
2232 }
2233
2234 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2235 HeapRegionClaimer *hrclaimer,
2236 uint worker_id) const {
2237 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2238 }
2239
2240 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2241 HeapRegionClaimer *hrclaimer) const {
2242 _hrm->par_iterate(cl, hrclaimer, 0);
2243 }
2244
2245 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2246 _collection_set.iterate(cl);
2247 }
2248
2249 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2250 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2251 }
2252
2253 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2254 HeapRegion* hr = heap_region_containing(addr);
2255 return hr->block_start(addr);
2256 }
2257
2258 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2259 HeapRegion* hr = heap_region_containing(addr);
2260 return hr->block_size(addr);
2261 }
2262
2263 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2264 HeapRegion* hr = heap_region_containing(addr);
2265 return hr->block_is_obj(addr);
2266 }
2267
2268 bool G1CollectedHeap::supports_tlab_allocation() const {
2269 return true;
2270 }
2271
2272 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2273 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2274 }
2275
2276 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2277 return _eden.length() * HeapRegion::GrainBytes;
2278 }
2279
2280 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2281 // must be equal to the humongous object limit.
2282 size_t G1CollectedHeap::max_tlab_size() const {
2283 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2284 }
2285
2286 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2287 return _allocator->unsafe_max_tlab_alloc();
2288 }
2289
2290 size_t G1CollectedHeap::max_capacity() const {
2291 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2292 }
2293
2294 size_t G1CollectedHeap::max_reserved_capacity() const {
2295 return _hrm->max_length() * HeapRegion::GrainBytes;
2296 }
2297
2298 jlong G1CollectedHeap::millis_since_last_gc() {
2299 // See the notes in GenCollectedHeap::millis_since_last_gc()
2300 // for more information about the implementation.
2301 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2302 _policy->collection_pause_end_millis();
2303 if (ret_val < 0) {
2304 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2305 ". returning zero instead.", ret_val);
2306 return 0;
2307 }
2308 return ret_val;
2309 }
2310
2311 void G1CollectedHeap::deduplicate_string(oop str) {
2312 assert(java_lang_String::is_instance(str), "invariant");
2313
2314 if (G1StringDedup::is_enabled()) {
2315 G1StringDedup::deduplicate(str);
2316 }
2317 }
2318
2319 void G1CollectedHeap::prepare_for_verify() {
2320 _verifier->prepare_for_verify();
2321 }
2322
2323 void G1CollectedHeap::verify(VerifyOption vo) {
2324 _verifier->verify(vo);
2325 }
2326
2327 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2328 return true;
2329 }
2330
2331 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2332 return _cm_thread->request_concurrent_phase(phase);
2333 }
2334
2335 bool G1CollectedHeap::is_heterogeneous_heap() const {
2336 return _collector_policy->is_heterogeneous_heap();
2337 }
2338
2339 class PrintRegionClosure: public HeapRegionClosure {
2340 outputStream* _st;
2341 public:
2342 PrintRegionClosure(outputStream* st) : _st(st) {}
2343 bool do_heap_region(HeapRegion* r) {
2344 r->print_on(_st);
2345 return false;
2346 }
2347 };
2348
2349 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2350 const HeapRegion* hr,
2351 const VerifyOption vo) const {
2352 switch (vo) {
2353 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2354 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2355 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2356 default: ShouldNotReachHere();
2357 }
2358 return false; // keep some compilers happy
2359 }
2360
2361 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2362 const VerifyOption vo) const {
2363 switch (vo) {
2364 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2365 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2366 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2367 default: ShouldNotReachHere();
2368 }
2369 return false; // keep some compilers happy
2370 }
2371
2372 void G1CollectedHeap::print_heap_regions() const {
2373 LogTarget(Trace, gc, heap, region) lt;
2374 if (lt.is_enabled()) {
2375 LogStream ls(lt);
2376 print_regions_on(&ls);
2377 }
2378 }
2379
2380 void G1CollectedHeap::print_on(outputStream* st) const {
2381 st->print(" %-20s", "garbage-first heap");
2382 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2383 capacity()/K, used_unlocked()/K);
2384 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2385 p2i(_hrm->reserved().start()),
2386 p2i(_hrm->reserved().end()));
2387 st->cr();
2388 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2389 uint young_regions = young_regions_count();
2390 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2391 (size_t) young_regions * HeapRegion::GrainBytes / K);
2392 uint survivor_regions = survivor_regions_count();
2393 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2394 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2395 st->cr();
2396 MetaspaceUtils::print_on(st);
2397 }
2398
2399 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2400 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2401 "HS=humongous(starts), HC=humongous(continues), "
2402 "CS=collection set, F=free, A=archive, "
2403 "TAMS=top-at-mark-start (previous, next)");
2404 PrintRegionClosure blk(st);
2405 heap_region_iterate(&blk);
2406 }
2407
2408 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2409 print_on(st);
2410
2411 // Print the per-region information.
2412 print_regions_on(st);
2413 }
2414
2415 void G1CollectedHeap::print_on_error(outputStream* st) const {
2416 this->CollectedHeap::print_on_error(st);
2417
2418 if (_cm != NULL) {
2419 st->cr();
2420 _cm->print_on_error(st);
2421 }
2422 }
2423
2424 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2425 workers()->print_worker_threads_on(st);
2426 _cm_thread->print_on(st);
2427 st->cr();
2428 _cm->print_worker_threads_on(st);
2429 _cr->print_threads_on(st);
2430 _young_gen_sampling_thread->print_on(st);
2431 if (G1StringDedup::is_enabled()) {
2432 G1StringDedup::print_worker_threads_on(st);
2433 }
2434 }
2435
2436 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2437 workers()->threads_do(tc);
2438 tc->do_thread(_cm_thread);
2439 _cm->threads_do(tc);
2440 _cr->threads_do(tc);
2441 tc->do_thread(_young_gen_sampling_thread);
2442 if (G1StringDedup::is_enabled()) {
2443 G1StringDedup::threads_do(tc);
2444 }
2445 }
2446
2447 void G1CollectedHeap::print_tracing_info() const {
2448 rem_set()->print_summary_info();
2449 concurrent_mark()->print_summary_info();
2450 }
2451
2452 #ifndef PRODUCT
2453 // Helpful for debugging RSet issues.
2454
2455 class PrintRSetsClosure : public HeapRegionClosure {
2456 private:
2457 const char* _msg;
2458 size_t _occupied_sum;
2459
2460 public:
2461 bool do_heap_region(HeapRegion* r) {
2462 HeapRegionRemSet* hrrs = r->rem_set();
2463 size_t occupied = hrrs->occupied();
2464 _occupied_sum += occupied;
2465
2466 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2467 if (occupied == 0) {
2468 tty->print_cr(" RSet is empty");
2469 } else {
2470 hrrs->print();
2471 }
2472 tty->print_cr("----------");
2473 return false;
2474 }
2475
2476 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2477 tty->cr();
2478 tty->print_cr("========================================");
2479 tty->print_cr("%s", msg);
2480 tty->cr();
2481 }
2482
2483 ~PrintRSetsClosure() {
2484 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2485 tty->print_cr("========================================");
2486 tty->cr();
2487 }
2488 };
2489
2490 void G1CollectedHeap::print_cset_rsets() {
2491 PrintRSetsClosure cl("Printing CSet RSets");
2492 collection_set_iterate(&cl);
2493 }
2494
2495 void G1CollectedHeap::print_all_rsets() {
2496 PrintRSetsClosure cl("Printing All RSets");;
2497 heap_region_iterate(&cl);
2498 }
2499 #endif // PRODUCT
2500
2501 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2502
2503 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2504 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2505 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2506
2507 size_t eden_capacity_bytes =
2508 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2509
2510 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2511 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2512 eden_capacity_bytes, survivor_used_bytes, num_regions());
2513 }
2514
2515 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2516 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2517 stats->unused(), stats->used(), stats->region_end_waste(),
2518 stats->regions_filled(), stats->direct_allocated(),
2519 stats->failure_used(), stats->failure_waste());
2520 }
2521
2522 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2523 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2524 gc_tracer->report_gc_heap_summary(when, heap_summary);
2525
2526 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2527 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2528 }
2529
2530 G1CollectedHeap* G1CollectedHeap::heap() {
2531 CollectedHeap* heap = Universe::heap();
2532 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2533 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2534 return (G1CollectedHeap*)heap;
2535 }
2536
2537 void G1CollectedHeap::gc_prologue(bool full) {
2538 // always_do_update_barrier = false;
2539 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2540
2541 // This summary needs to be printed before incrementing total collections.
2542 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2543
2544 // Update common counters.
2545 increment_total_collections(full /* full gc */);
2546 if (full || collector_state()->in_initial_mark_gc()) {
2547 increment_old_marking_cycles_started();
2548 }
2549
2550 // Fill TLAB's and such
2551 double start = os::elapsedTime();
2552 ensure_parsability(true);
2553 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2554 }
2555
2556 void G1CollectedHeap::gc_epilogue(bool full) {
2557 // Update common counters.
2558 if (full) {
2559 // Update the number of full collections that have been completed.
2560 increment_old_marking_cycles_completed(false /* concurrent */);
2561 }
2562
2563 // We are at the end of the GC. Total collections has already been increased.
2564 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2565
2566 // FIXME: what is this about?
2567 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2568 // is set.
2569 #if COMPILER2_OR_JVMCI
2570 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2571 #endif
2572 // always_do_update_barrier = true;
2573
2574 double start = os::elapsedTime();
2575 resize_all_tlabs();
2576 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2577
2578 MemoryService::track_memory_usage();
2579 // We have just completed a GC. Update the soft reference
2580 // policy with the new heap occupancy
2581 Universe::update_heap_info_at_gc();
2582 }
2583
2584 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2585 uint gc_count_before,
2586 bool* succeeded,
2587 GCCause::Cause gc_cause) {
2588 assert_heap_not_locked_and_not_at_safepoint();
2589 VM_G1CollectForAllocation op(word_size,
2590 gc_count_before,
2591 gc_cause,
2592 false, /* should_initiate_conc_mark */
2593 policy()->max_pause_time_ms());
2594 VMThread::execute(&op);
2595
2596 HeapWord* result = op.result();
2597 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2598 assert(result == NULL || ret_succeeded,
2599 "the result should be NULL if the VM did not succeed");
2600 *succeeded = ret_succeeded;
2601
2602 assert_heap_not_locked();
2603 return result;
2604 }
2605
2606 void G1CollectedHeap::do_concurrent_mark() {
2607 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2608 if (!_cm_thread->in_progress()) {
2609 _cm_thread->set_started();
2610 CGC_lock->notify();
2611 }
2612 }
2613
2614 size_t G1CollectedHeap::pending_card_num() {
2615 size_t extra_cards = 0;
2616 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2617 G1DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2618 extra_cards += dcq.size();
2619 }
2620 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2621 size_t buffer_size = dcqs.buffer_size();
2622 size_t buffer_num = dcqs.completed_buffers_num();
2623
2624 return buffer_size * buffer_num + extra_cards;
2625 }
2626
2627 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2628 // We don't nominate objects with many remembered set entries, on
2629 // the assumption that such objects are likely still live.
2630 HeapRegionRemSet* rem_set = r->rem_set();
2631
2632 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2633 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2634 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2635 }
2636
2637 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2638 private:
2639 size_t _total_humongous;
2640 size_t _candidate_humongous;
2641
2642 G1DirtyCardQueue _dcq;
2643
2644 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2645 assert(region->is_starts_humongous(), "Must start a humongous object");
2646
2647 oop obj = oop(region->bottom());
2648
2649 // Dead objects cannot be eager reclaim candidates. Due to class
2650 // unloading it is unsafe to query their classes so we return early.
2651 if (g1h->is_obj_dead(obj, region)) {
2652 return false;
2653 }
2654
2655 // If we do not have a complete remembered set for the region, then we can
2656 // not be sure that we have all references to it.
2657 if (!region->rem_set()->is_complete()) {
2658 return false;
2659 }
2660 // Candidate selection must satisfy the following constraints
2661 // while concurrent marking is in progress:
2662 //
2663 // * In order to maintain SATB invariants, an object must not be
2664 // reclaimed if it was allocated before the start of marking and
2665 // has not had its references scanned. Such an object must have
2666 // its references (including type metadata) scanned to ensure no
2667 // live objects are missed by the marking process. Objects
2668 // allocated after the start of concurrent marking don't need to
2669 // be scanned.
2670 //
2671 // * An object must not be reclaimed if it is on the concurrent
2672 // mark stack. Objects allocated after the start of concurrent
2673 // marking are never pushed on the mark stack.
2674 //
2675 // Nominating only objects allocated after the start of concurrent
2676 // marking is sufficient to meet both constraints. This may miss
2677 // some objects that satisfy the constraints, but the marking data
2678 // structures don't support efficiently performing the needed
2679 // additional tests or scrubbing of the mark stack.
2680 //
2681 // However, we presently only nominate is_typeArray() objects.
2682 // A humongous object containing references induces remembered
2683 // set entries on other regions. In order to reclaim such an
2684 // object, those remembered sets would need to be cleaned up.
2685 //
2686 // We also treat is_typeArray() objects specially, allowing them
2687 // to be reclaimed even if allocated before the start of
2688 // concurrent mark. For this we rely on mark stack insertion to
2689 // exclude is_typeArray() objects, preventing reclaiming an object
2690 // that is in the mark stack. We also rely on the metadata for
2691 // such objects to be built-in and so ensured to be kept live.
2692 // Frequent allocation and drop of large binary blobs is an
2693 // important use case for eager reclaim, and this special handling
2694 // may reduce needed headroom.
2695
2696 return obj->is_typeArray() &&
2697 g1h->is_potential_eager_reclaim_candidate(region);
2698 }
2699
2700 public:
2701 RegisterHumongousWithInCSetFastTestClosure()
2702 : _total_humongous(0),
2703 _candidate_humongous(0),
2704 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2705 }
2706
2707 virtual bool do_heap_region(HeapRegion* r) {
2708 if (!r->is_starts_humongous()) {
2709 return false;
2710 }
2711 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2712
2713 bool is_candidate = humongous_region_is_candidate(g1h, r);
2714 uint rindex = r->hrm_index();
2715 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2716 if (is_candidate) {
2717 _candidate_humongous++;
2718 g1h->register_humongous_region_with_cset(rindex);
2719 // Is_candidate already filters out humongous object with large remembered sets.
2720 // If we have a humongous object with a few remembered sets, we simply flush these
2721 // remembered set entries into the DCQS. That will result in automatic
2722 // re-evaluation of their remembered set entries during the following evacuation
2723 // phase.
2724 if (!r->rem_set()->is_empty()) {
2725 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2726 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2727 G1CardTable* ct = g1h->card_table();
2728 HeapRegionRemSetIterator hrrs(r->rem_set());
2729 size_t card_index;
2730 while (hrrs.has_next(card_index)) {
2731 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2732 // The remembered set might contain references to already freed
2733 // regions. Filter out such entries to avoid failing card table
2734 // verification.
2735 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2736 if (*card_ptr != G1CardTable::dirty_card_val()) {
2737 *card_ptr = G1CardTable::dirty_card_val();
2738 _dcq.enqueue(card_ptr);
2739 }
2740 }
2741 }
2742 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2743 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2744 hrrs.n_yielded(), r->rem_set()->occupied());
2745 // We should only clear the card based remembered set here as we will not
2746 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2747 // (and probably never) we do not enter this path if there are other kind of
2748 // remembered sets for this region.
2749 r->rem_set()->clear_locked(true /* only_cardset */);
2750 // Clear_locked() above sets the state to Empty. However we want to continue
2751 // collecting remembered set entries for humongous regions that were not
2752 // reclaimed.
2753 r->rem_set()->set_state_complete();
2754 }
2755 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2756 }
2757 _total_humongous++;
2758
2759 return false;
2760 }
2761
2762 size_t total_humongous() const { return _total_humongous; }
2763 size_t candidate_humongous() const { return _candidate_humongous; }
2764
2765 void flush_rem_set_entries() { _dcq.flush(); }
2766 };
2767
2768 void G1CollectedHeap::register_humongous_regions_with_cset() {
2769 if (!G1EagerReclaimHumongousObjects) {
2770 phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2771 return;
2772 }
2773 double time = os::elapsed_counter();
2774
2775 // Collect reclaim candidate information and register candidates with cset.
2776 RegisterHumongousWithInCSetFastTestClosure cl;
2777 heap_region_iterate(&cl);
2778
2779 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2780 phase_times()->record_fast_reclaim_humongous_stats(time,
2781 cl.total_humongous(),
2782 cl.candidate_humongous());
2783 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2784
2785 // Finally flush all remembered set entries to re-check into the global DCQS.
2786 cl.flush_rem_set_entries();
2787 }
2788
2789 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2790 public:
2791 bool do_heap_region(HeapRegion* hr) {
2792 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2793 hr->verify_rem_set();
2794 }
2795 return false;
2796 }
2797 };
2798
2799 uint G1CollectedHeap::num_task_queues() const {
2800 return _task_queues->size();
2801 }
2802
2803 #if TASKQUEUE_STATS
2804 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2805 st->print_raw_cr("GC Task Stats");
2806 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2807 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2808 }
2809
2810 void G1CollectedHeap::print_taskqueue_stats() const {
2811 if (!log_is_enabled(Trace, gc, task, stats)) {
2812 return;
2813 }
2814 Log(gc, task, stats) log;
2815 ResourceMark rm;
2816 LogStream ls(log.trace());
2817 outputStream* st = &ls;
2818
2819 print_taskqueue_stats_hdr(st);
2820
2821 TaskQueueStats totals;
2822 const uint n = num_task_queues();
2823 for (uint i = 0; i < n; ++i) {
2824 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2825 totals += task_queue(i)->stats;
2826 }
2827 st->print_raw("tot "); totals.print(st); st->cr();
2828
2829 DEBUG_ONLY(totals.verify());
2830 }
2831
2832 void G1CollectedHeap::reset_taskqueue_stats() {
2833 const uint n = num_task_queues();
2834 for (uint i = 0; i < n; ++i) {
2835 task_queue(i)->stats.reset();
2836 }
2837 }
2838 #endif // TASKQUEUE_STATS
2839
2840 void G1CollectedHeap::wait_for_root_region_scanning() {
2841 double scan_wait_start = os::elapsedTime();
2842 // We have to wait until the CM threads finish scanning the
2843 // root regions as it's the only way to ensure that all the
2844 // objects on them have been correctly scanned before we start
2845 // moving them during the GC.
2846 bool waited = _cm->root_regions()->wait_until_scan_finished();
2847 double wait_time_ms = 0.0;
2848 if (waited) {
2849 double scan_wait_end = os::elapsedTime();
2850 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2851 }
2852 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2853 }
2854
2855 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2856 private:
2857 G1HRPrinter* _hr_printer;
2858 public:
2859 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2860
2861 virtual bool do_heap_region(HeapRegion* r) {
2862 _hr_printer->cset(r);
2863 return false;
2864 }
2865 };
2866
2867 void G1CollectedHeap::start_new_collection_set() {
2868 double start = os::elapsedTime();
2869
2870 collection_set()->start_incremental_building();
2871
2872 clear_cset_fast_test();
2873
2874 guarantee(_eden.length() == 0, "eden should have been cleared");
2875 policy()->transfer_survivors_to_cset(survivor());
2876
2877 // We redo the verification but now wrt to the new CSet which
2878 // has just got initialized after the previous CSet was freed.
2879 _cm->verify_no_collection_set_oops_in_stacks();
2880
2881 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2882 }
2883
2884 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms){
2885 policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2886 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2887
2888 _cm->verify_no_collection_set_oops_in_stacks();
2889
2890 if (_hr_printer.is_active()) {
2891 G1PrintCollectionSetClosure cl(&_hr_printer);
2892 _collection_set.iterate(&cl);
2893 }
2894 }
2895
2896 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2897 if (collector_state()->in_initial_mark_gc()) {
2898 return G1HeapVerifier::G1VerifyConcurrentStart;
2899 } else if (collector_state()->in_young_only_phase()) {
2900 return G1HeapVerifier::G1VerifyYoungNormal;
2901 } else {
2902 return G1HeapVerifier::G1VerifyMixed;
2903 }
2904 }
2905
2906 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2907 if (VerifyRememberedSets) {
2908 log_info(gc, verify)("[Verifying RemSets before GC]");
2909 VerifyRegionRemSetClosure v_cl;
2910 heap_region_iterate(&v_cl);
2911 }
2912 _verifier->verify_before_gc(type);
2913 _verifier->check_bitmaps("GC Start");
2914 }
2915
2916 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2917 if (VerifyRememberedSets) {
2918 log_info(gc, verify)("[Verifying RemSets after GC]");
2919 VerifyRegionRemSetClosure v_cl;
2920 heap_region_iterate(&v_cl);
2921 }
2922 _verifier->verify_after_gc(type);
2923 _verifier->check_bitmaps("GC End");
2924 }
2925
2926 void G1CollectedHeap::expand_heap_after_young_collection(){
2927 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2928 if (expand_bytes > 0) {
2929 // No need for an ergo logging here,
2930 // expansion_amount() does this when it returns a value > 0.
2931 double expand_ms;
2932 if (!expand(expand_bytes, _workers, &expand_ms)) {
2933 // We failed to expand the heap. Cannot do anything about it.
2934 }
2935 phase_times()->record_expand_heap_time(expand_ms);
2936 }
2937 }
2938
2939 const char* G1CollectedHeap::young_gc_name() const {
2940 if (collector_state()->in_initial_mark_gc()) {
2941 return "Pause Young (Concurrent Start)";
2942 } else if (collector_state()->in_young_only_phase()) {
2943 if (collector_state()->in_young_gc_before_mixed()) {
2944 return "Pause Young (Prepare Mixed)";
2945 } else {
2946 return "Pause Young (Normal)";
2947 }
2948 } else {
2949 return "Pause Young (Mixed)";
2950 }
2951 }
2952
2953 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2954 assert_at_safepoint_on_vm_thread();
2955 guarantee(!is_gc_active(), "collection is not reentrant");
2956
2957 if (GCLocker::check_active_before_gc()) {
2958 return false;
2959 }
2960
2961 GCIdMark gc_id_mark;
2962
2963 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2964 ResourceMark rm;
2965
2966 policy()->note_gc_start();
2967
2968 _gc_timer_stw->register_gc_start();
2969 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2970
2971 wait_for_root_region_scanning();
2972
2973 print_heap_before_gc();
2974 print_heap_regions();
2975 trace_heap_before_gc(_gc_tracer_stw);
2976
2977 _verifier->verify_region_sets_optional();
2978 _verifier->verify_dirty_young_regions();
2979
2980 // We should not be doing initial mark unless the conc mark thread is running
2981 if (!_cm_thread->should_terminate()) {
2982 // This call will decide whether this pause is an initial-mark
2983 // pause. If it is, in_initial_mark_gc() will return true
2984 // for the duration of this pause.
2985 policy()->decide_on_conc_mark_initiation();
2986 }
2987
2988 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2989 assert(!collector_state()->in_initial_mark_gc() ||
2990 collector_state()->in_young_only_phase(), "sanity");
2991 // We also do not allow mixed GCs during marking.
2992 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2993
2994 // Record whether this pause is an initial mark. When the current
2995 // thread has completed its logging output and it's safe to signal
2996 // the CM thread, the flag's value in the policy has been reset.
2997 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2998 if (should_start_conc_mark) {
2999 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3000 }
3001
3002 // Inner scope for scope based logging, timers, and stats collection
3003 {
3004 G1EvacuationInfo evacuation_info;
3005
3006 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3007
3008 GCTraceCPUTime tcpu;
3009
3010 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3011
3012 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3013 workers()->active_workers(),
3014 Threads::number_of_non_daemon_threads());
3015 active_workers = workers()->update_active_workers(active_workers);
3016 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3017
3018 G1MonitoringScope ms(g1mm(),
3019 false /* full_gc */,
3020 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3021
3022 G1HeapTransition heap_transition(this);
3023 size_t heap_used_bytes_before_gc = used();
3024
3025 {
3026 IsGCActiveMark x;
3027
3028 gc_prologue(false);
3029
3030 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3031 verify_before_young_collection(verify_type);
3032
3033 {
3034 // The elapsed time induced by the start time below deliberately elides
3035 // the possible verification above.
3036 double sample_start_time_sec = os::elapsedTime();
3037
3038 // Please see comment in g1CollectedHeap.hpp and
3039 // G1CollectedHeap::ref_processing_init() to see how
3040 // reference processing currently works in G1.
3041 _ref_processor_stw->enable_discovery();
3042
3043 // We want to temporarily turn off discovery by the
3044 // CM ref processor, if necessary, and turn it back on
3045 // on again later if we do. Using a scoped
3046 // NoRefDiscovery object will do this.
3047 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3048
3049 policy()->record_collection_pause_start(sample_start_time_sec);
3050
3051 // Forget the current allocation region (we might even choose it to be part
3052 // of the collection set!).
3053 _allocator->release_mutator_alloc_region();
3054
3055 calculate_collection_set(evacuation_info, target_pause_time_ms);
3056
3057 G1ParScanThreadStateSet per_thread_states(this,
3058 workers()->active_workers(),
3059 collection_set()->young_region_length(),
3060 collection_set()->optional_region_length());
3061 pre_evacuate_collection_set(evacuation_info);
3062
3063 // Actually do the work...
3064 evacuate_collection_set(&per_thread_states);
3065 evacuate_optional_collection_set(&per_thread_states);
3066
3067 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3068
3069 start_new_collection_set();
3070
3071 _survivor_evac_stats.adjust_desired_plab_sz();
3072 _old_evac_stats.adjust_desired_plab_sz();
3073
3074 if (should_start_conc_mark) {
3075 // We have to do this before we notify the CM threads that
3076 // they can start working to make sure that all the
3077 // appropriate initialization is done on the CM object.
3078 concurrent_mark()->post_initial_mark();
3079 // Note that we don't actually trigger the CM thread at
3080 // this point. We do that later when we're sure that
3081 // the current thread has completed its logging output.
3082 }
3083
3084 allocate_dummy_regions();
3085
3086 _allocator->init_mutator_alloc_region();
3087
3088 expand_heap_after_young_collection();
3089
3090 double sample_end_time_sec = os::elapsedTime();
3091 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3092 size_t total_cards_scanned = phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3093 policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3094 }
3095
3096 verify_after_young_collection(verify_type);
3097
3098 #ifdef TRACESPINNING
3099 ParallelTaskTerminator::print_termination_counts();
3100 #endif
3101
3102 gc_epilogue(false);
3103 }
3104
3105 // Print the remainder of the GC log output.
3106 if (evacuation_failed()) {
3107 log_info(gc)("To-space exhausted");
3108 }
3109
3110 policy()->print_phases();
3111 heap_transition.print();
3112
3113 _hrm->verify_optional();
3114 _verifier->verify_region_sets_optional();
3115
3116 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3117 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3118
3119 print_heap_after_gc();
3120 print_heap_regions();
3121 trace_heap_after_gc(_gc_tracer_stw);
3122
3123 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3124 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3125 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3126 // before any GC notifications are raised.
3127 g1mm()->update_sizes();
3128
3129 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3130 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3131 _gc_timer_stw->register_gc_end();
3132 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3133 }
3134 // It should now be safe to tell the concurrent mark thread to start
3135 // without its logging output interfering with the logging output
3136 // that came from the pause.
3137
3138 if (should_start_conc_mark) {
3139 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3140 // thread(s) could be running concurrently with us. Make sure that anything
3141 // after this point does not assume that we are the only GC thread running.
3142 // Note: of course, the actual marking work will not start until the safepoint
3143 // itself is released in SuspendibleThreadSet::desynchronize().
3144 do_concurrent_mark();
3145 }
3146
3147 return true;
3148 }
3149
3150 void G1CollectedHeap::remove_self_forwarding_pointers() {
3151 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3152 workers()->run_task(&rsfp_task);
3153 }
3154
3155 void G1CollectedHeap::restore_after_evac_failure() {
3156 double remove_self_forwards_start = os::elapsedTime();
3157
3158 remove_self_forwarding_pointers();
3159 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3160 _preserved_marks_set.restore(&task_executor);
3161
3162 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3163 }
3164
3165 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3166 if (!_evacuation_failed) {
3167 _evacuation_failed = true;
3168 }
3169
3170 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3171 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3172 }
3173
3174 bool G1ParEvacuateFollowersClosure::offer_termination() {
3175 EventGCPhaseParallel event;
3176 G1ParScanThreadState* const pss = par_scan_state();
3177 start_term_time();
3178 const bool res = terminator()->offer_termination();
3179 end_term_time();
3180 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3181 return res;
3182 }
3183
3184 void G1ParEvacuateFollowersClosure::do_void() {
3185 EventGCPhaseParallel event;
3186 G1ParScanThreadState* const pss = par_scan_state();
3187 pss->trim_queue();
3188 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3189 do {
3190 EventGCPhaseParallel event;
3191 pss->steal_and_trim_queue(queues());
3192 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3193 } while (!offer_termination());
3194 }
3195
3196 class G1ParTask : public AbstractGangTask {
3197 protected:
3198 G1CollectedHeap* _g1h;
3199 G1ParScanThreadStateSet* _pss;
3200 RefToScanQueueSet* _queues;
3201 G1RootProcessor* _root_processor;
3202 TaskTerminator _terminator;
3203 uint _n_workers;
3204
3205 public:
3206 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3207 : AbstractGangTask("G1 collection"),
3208 _g1h(g1h),
3209 _pss(per_thread_states),
3210 _queues(task_queues),
3211 _root_processor(root_processor),
3212 _terminator(n_workers, _queues),
3213 _n_workers(n_workers)
3214 {}
3215
3216 void work(uint worker_id) {
3217 if (worker_id >= _n_workers) return; // no work needed this round
3218
3219 double start_sec = os::elapsedTime();
3220 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3221
3222 {
3223 ResourceMark rm;
3224 HandleMark hm;
3225
3226 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3227
3228 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3229 pss->set_ref_discoverer(rp);
3230
3231 double start_strong_roots_sec = os::elapsedTime();
3232
3233 _root_processor->evacuate_roots(pss, worker_id);
3234
3235 _g1h->rem_set()->oops_into_collection_set_do(pss, worker_id);
3236
3237 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3238
3239 double term_sec = 0.0;
3240 size_t evac_term_attempts = 0;
3241 {
3242 double start = os::elapsedTime();
3243 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, _terminator.terminator(), G1GCPhaseTimes::ObjCopy);
3244 evac.do_void();
3245
3246 evac_term_attempts = evac.term_attempts();
3247 term_sec = evac.term_time();
3248 double elapsed_sec = os::elapsedTime() - start;
3249
3250 G1GCPhaseTimes* p = _g1h->phase_times();
3251 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3252
3253 p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy,
3254 worker_id,
3255 pss->lab_waste_words() * HeapWordSize,
3256 G1GCPhaseTimes::ObjCopyLABWaste);
3257 p->record_or_add_thread_work_item(G1GCPhaseTimes::ObjCopy,
3258 worker_id,
3259 pss->lab_undo_waste_words() * HeapWordSize,
3260 G1GCPhaseTimes::ObjCopyLABUndoWaste);
3261
3262 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3263 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3264 }
3265
3266 assert(pss->queue_is_empty(), "should be empty");
3267
3268 // Close the inner scope so that the ResourceMark and HandleMark
3269 // destructors are executed here and are included as part of the
3270 // "GC Worker Time".
3271 }
3272 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3273 }
3274 };
3275
3276 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3277 bool class_unloading_occurred) {
3278 uint num_workers = workers()->active_workers();
3279 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3280 workers()->run_task(&unlink_task);
3281 }
3282
3283 // Clean string dedup data structures.
3284 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3285 // record the durations of the phases. Hence the almost-copy.
3286 class G1StringDedupCleaningTask : public AbstractGangTask {
3287 BoolObjectClosure* _is_alive;
3288 OopClosure* _keep_alive;
3289 G1GCPhaseTimes* _phase_times;
3290
3291 public:
3292 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3293 OopClosure* keep_alive,
3294 G1GCPhaseTimes* phase_times) :
3295 AbstractGangTask("Partial Cleaning Task"),
3296 _is_alive(is_alive),
3297 _keep_alive(keep_alive),
3298 _phase_times(phase_times)
3299 {
3300 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3301 StringDedup::gc_prologue(true);
3302 }
3303
3304 ~G1StringDedupCleaningTask() {
3305 StringDedup::gc_epilogue();
3306 }
3307
3308 void work(uint worker_id) {
3309 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3310 {
3311 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3312 StringDedupQueue::unlink_or_oops_do(&cl);
3313 }
3314 {
3315 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3316 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3317 }
3318 }
3319 };
3320
3321 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3322 OopClosure* keep_alive,
3323 G1GCPhaseTimes* phase_times) {
3324 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3325 workers()->run_task(&cl);
3326 }
3327
3328 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3329 private:
3330 G1DirtyCardQueueSet* _queue;
3331 G1CollectedHeap* _g1h;
3332 public:
3333 G1RedirtyLoggedCardsTask(G1DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3334 _queue(queue), _g1h(g1h) { }
3335
3336 virtual void work(uint worker_id) {
3337 G1GCPhaseTimes* p = _g1h->phase_times();
3338 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3339
3340 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3341 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3342
3343 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3344 }
3345 };
3346
3347 void G1CollectedHeap::redirty_logged_cards() {
3348 double redirty_logged_cards_start = os::elapsedTime();
3349
3350 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3351 dirty_card_queue_set().reset_for_par_iteration();
3352 workers()->run_task(&redirty_task);
3353
3354 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3355 dcq.merge_bufferlists(&dirty_card_queue_set());
3356 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3357
3358 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3359 }
3360
3361 // Weak Reference Processing support
3362
3363 bool G1STWIsAliveClosure::do_object_b(oop p) {
3364 // An object is reachable if it is outside the collection set,
3365 // or is inside and copied.
3366 return !_g1h->is_in_cset(p) || p->is_forwarded();
3367 }
3368
3369 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3370 assert(obj != NULL, "must not be NULL");
3371 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3372 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3373 // may falsely indicate that this is not the case here: however the collection set only
3374 // contains old regions when concurrent mark is not running.
3375 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3376 }
3377
3378 // Non Copying Keep Alive closure
3379 class G1KeepAliveClosure: public OopClosure {
3380 G1CollectedHeap*_g1h;
3381 public:
3382 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3383 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3384 void do_oop(oop* p) {
3385 oop obj = *p;
3386 assert(obj != NULL, "the caller should have filtered out NULL values");
3387
3388 const InCSetState cset_state =_g1h->in_cset_state(obj);
3389 if (!cset_state.is_in_cset_or_humongous()) {
3390 return;
3391 }
3392 if (cset_state.is_in_cset()) {
3393 assert( obj->is_forwarded(), "invariant" );
3394 *p = obj->forwardee();
3395 } else {
3396 assert(!obj->is_forwarded(), "invariant" );
3397 assert(cset_state.is_humongous(),
3398 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3399 _g1h->set_humongous_is_live(obj);
3400 }
3401 }
3402 };
3403
3404 // Copying Keep Alive closure - can be called from both
3405 // serial and parallel code as long as different worker
3406 // threads utilize different G1ParScanThreadState instances
3407 // and different queues.
3408
3409 class G1CopyingKeepAliveClosure: public OopClosure {
3410 G1CollectedHeap* _g1h;
3411 G1ParScanThreadState* _par_scan_state;
3412
3413 public:
3414 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3415 G1ParScanThreadState* pss):
3416 _g1h(g1h),
3417 _par_scan_state(pss)
3418 {}
3419
3420 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3421 virtual void do_oop( oop* p) { do_oop_work(p); }
3422
3423 template <class T> void do_oop_work(T* p) {
3424 oop obj = RawAccess<>::oop_load(p);
3425
3426 if (_g1h->is_in_cset_or_humongous(obj)) {
3427 // If the referent object has been forwarded (either copied
3428 // to a new location or to itself in the event of an
3429 // evacuation failure) then we need to update the reference
3430 // field and, if both reference and referent are in the G1
3431 // heap, update the RSet for the referent.
3432 //
3433 // If the referent has not been forwarded then we have to keep
3434 // it alive by policy. Therefore we have copy the referent.
3435 //
3436 // When the queue is drained (after each phase of reference processing)
3437 // the object and it's followers will be copied, the reference field set
3438 // to point to the new location, and the RSet updated.
3439 _par_scan_state->push_on_queue(p);
3440 }
3441 }
3442 };
3443
3444 // Serial drain queue closure. Called as the 'complete_gc'
3445 // closure for each discovered list in some of the
3446 // reference processing phases.
3447
3448 class G1STWDrainQueueClosure: public VoidClosure {
3449 protected:
3450 G1CollectedHeap* _g1h;
3451 G1ParScanThreadState* _par_scan_state;
3452
3453 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3454
3455 public:
3456 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3457 _g1h(g1h),
3458 _par_scan_state(pss)
3459 { }
3460
3461 void do_void() {
3462 G1ParScanThreadState* const pss = par_scan_state();
3463 pss->trim_queue();
3464 }
3465 };
3466
3467 // Parallel Reference Processing closures
3468
3469 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3470 // processing during G1 evacuation pauses.
3471
3472 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3473 private:
3474 G1CollectedHeap* _g1h;
3475 G1ParScanThreadStateSet* _pss;
3476 RefToScanQueueSet* _queues;
3477 WorkGang* _workers;
3478
3479 public:
3480 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3481 G1ParScanThreadStateSet* per_thread_states,
3482 WorkGang* workers,
3483 RefToScanQueueSet *task_queues) :
3484 _g1h(g1h),
3485 _pss(per_thread_states),
3486 _queues(task_queues),
3487 _workers(workers)
3488 {
3489 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3490 }
3491
3492 // Executes the given task using concurrent marking worker threads.
3493 virtual void execute(ProcessTask& task, uint ergo_workers);
3494 };
3495
3496 // Gang task for possibly parallel reference processing
3497
3498 class G1STWRefProcTaskProxy: public AbstractGangTask {
3499 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3500 ProcessTask& _proc_task;
3501 G1CollectedHeap* _g1h;
3502 G1ParScanThreadStateSet* _pss;
3503 RefToScanQueueSet* _task_queues;
3504 ParallelTaskTerminator* _terminator;
3505
3506 public:
3507 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3508 G1CollectedHeap* g1h,
3509 G1ParScanThreadStateSet* per_thread_states,
3510 RefToScanQueueSet *task_queues,
3511 ParallelTaskTerminator* terminator) :
3512 AbstractGangTask("Process reference objects in parallel"),
3513 _proc_task(proc_task),
3514 _g1h(g1h),
3515 _pss(per_thread_states),
3516 _task_queues(task_queues),
3517 _terminator(terminator)
3518 {}
3519
3520 virtual void work(uint worker_id) {
3521 // The reference processing task executed by a single worker.
3522 ResourceMark rm;
3523 HandleMark hm;
3524
3525 G1STWIsAliveClosure is_alive(_g1h);
3526
3527 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3528 pss->set_ref_discoverer(NULL);
3529
3530 // Keep alive closure.
3531 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3532
3533 // Complete GC closure
3534 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3535
3536 // Call the reference processing task's work routine.
3537 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3538
3539 // Note we cannot assert that the refs array is empty here as not all
3540 // of the processing tasks (specifically phase2 - pp2_work) execute
3541 // the complete_gc closure (which ordinarily would drain the queue) so
3542 // the queue may not be empty.
3543 }
3544 };
3545
3546 // Driver routine for parallel reference processing.
3547 // Creates an instance of the ref processing gang
3548 // task and has the worker threads execute it.
3549 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3550 assert(_workers != NULL, "Need parallel worker threads.");
3551
3552 assert(_workers->active_workers() >= ergo_workers,
3553 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3554 ergo_workers, _workers->active_workers());
3555 TaskTerminator terminator(ergo_workers, _queues);
3556 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3557
3558 _workers->run_task(&proc_task_proxy, ergo_workers);
3559 }
3560
3561 // End of weak reference support closures
3562
3563 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3564 double ref_proc_start = os::elapsedTime();
3565
3566 ReferenceProcessor* rp = _ref_processor_stw;
3567 assert(rp->discovery_enabled(), "should have been enabled");
3568
3569 // Closure to test whether a referent is alive.
3570 G1STWIsAliveClosure is_alive(this);
3571
3572 // Even when parallel reference processing is enabled, the processing
3573 // of JNI refs is serial and performed serially by the current thread
3574 // rather than by a worker. The following PSS will be used for processing
3575 // JNI refs.
3576
3577 // Use only a single queue for this PSS.
3578 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3579 pss->set_ref_discoverer(NULL);
3580 assert(pss->queue_is_empty(), "pre-condition");
3581
3582 // Keep alive closure.
3583 G1CopyingKeepAliveClosure keep_alive(this, pss);
3584
3585 // Serial Complete GC closure
3586 G1STWDrainQueueClosure drain_queue(this, pss);
3587
3588 // Setup the soft refs policy...
3589 rp->setup_policy(false);
3590
3591 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3592
3593 ReferenceProcessorStats stats;
3594 if (!rp->processing_is_mt()) {
3595 // Serial reference processing...
3596 stats = rp->process_discovered_references(&is_alive,
3597 &keep_alive,
3598 &drain_queue,
3599 NULL,
3600 pt);
3601 } else {
3602 uint no_of_gc_workers = workers()->active_workers();
3603
3604 // Parallel reference processing
3605 assert(no_of_gc_workers <= rp->max_num_queues(),
3606 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3607 no_of_gc_workers, rp->max_num_queues());
3608
3609 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3610 stats = rp->process_discovered_references(&is_alive,
3611 &keep_alive,
3612 &drain_queue,
3613 &par_task_executor,
3614 pt);
3615 }
3616
3617 _gc_tracer_stw->report_gc_reference_stats(stats);
3618
3619 // We have completed copying any necessary live referent objects.
3620 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3621
3622 make_pending_list_reachable();
3623
3624 assert(!rp->discovery_enabled(), "Postcondition");
3625 rp->verify_no_references_recorded();
3626
3627 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3628 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3629 }
3630
3631 void G1CollectedHeap::make_pending_list_reachable() {
3632 if (collector_state()->in_initial_mark_gc()) {
3633 oop pll_head = Universe::reference_pending_list();
3634 if (pll_head != NULL) {
3635 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3636 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3637 }
3638 }
3639 }
3640
3641 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3642 double merge_pss_time_start = os::elapsedTime();
3643 per_thread_states->flush();
3644 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3645 }
3646
3647 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info) {
3648 _expand_heap_after_alloc_failure = true;
3649 _evacuation_failed = false;
3650
3651 // Disable the hot card cache.
3652 _hot_card_cache->reset_hot_cache_claimed_index();
3653 _hot_card_cache->set_use_cache(false);
3654
3655 // Initialize the GC alloc regions.
3656 _allocator->init_gc_alloc_regions(evacuation_info);
3657
3658 register_humongous_regions_with_cset();
3659 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3660
3661 rem_set()->prepare_for_oops_into_collection_set_do();
3662 _preserved_marks_set.assert_empty();
3663
3664 #if COMPILER2_OR_JVMCI
3665 DerivedPointerTable::clear();
3666 #endif
3667
3668 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3669 if (collector_state()->in_initial_mark_gc()) {
3670 concurrent_mark()->pre_initial_mark();
3671
3672 double start_clear_claimed_marks = os::elapsedTime();
3673
3674 ClassLoaderDataGraph::clear_claimed_marks();
3675
3676 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3677 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3678 }
3679 }
3680
3681 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3682 // Should G1EvacuationFailureALot be in effect for this GC?
3683 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3684
3685 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3686
3687 double start_par_time_sec = os::elapsedTime();
3688 double end_par_time_sec;
3689
3690 {
3691 const uint n_workers = workers()->active_workers();
3692 G1RootProcessor root_processor(this, n_workers);
3693 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3694
3695 workers()->run_task(&g1_par_task);
3696 end_par_time_sec = os::elapsedTime();
3697
3698 // Closing the inner scope will execute the destructor
3699 // for the G1RootProcessor object. We record the current
3700 // elapsed time before closing the scope so that time
3701 // taken for the destructor is NOT included in the
3702 // reported parallel time.
3703 }
3704
3705 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3706 phase_times()->record_par_time(par_time_ms);
3707
3708 double code_root_fixup_time_ms =
3709 (os::elapsedTime() - end_par_time_sec) * 1000.0;
3710 phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
3711 }
3712
3713 class G1EvacuateOptionalRegionTask : public AbstractGangTask {
3714 G1CollectedHeap* _g1h;
3715 G1ParScanThreadStateSet* _per_thread_states;
3716 G1OptionalCSet* _optional;
3717 RefToScanQueueSet* _queues;
3718 ParallelTaskTerminator _terminator;
3719
3720 Tickspan trim_ticks(G1ParScanThreadState* pss) {
3721 Tickspan copy_time = pss->trim_ticks();
3722 pss->reset_trim_ticks();
3723 return copy_time;
3724 }
3725
3726 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3727 G1EvacuationRootClosures* root_cls = pss->closures();
3728 G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss);
3729
3730 size_t scanned = 0;
3731 size_t claimed = 0;
3732 size_t skipped = 0;
3733 size_t used_memory = 0;
3734
3735 Ticks start = Ticks::now();
3736 Tickspan copy_time;
3737
3738 for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) {
3739 HeapRegion* hr = _optional->region_at(i);
3740 G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl);
3741 pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops());
3742 copy_time += trim_ticks(pss);
3743
3744 G1ScanRSForRegionClosure scan_rs_cl(_g1h->rem_set()->scan_state(), &obj_cl, pss, G1GCPhaseTimes::OptScanRS, worker_id);
3745 scan_rs_cl.do_heap_region(hr);
3746 copy_time += trim_ticks(pss);
3747 scanned += scan_rs_cl.cards_scanned();
3748 claimed += scan_rs_cl.cards_claimed();
3749 skipped += scan_rs_cl.cards_skipped();
3750
3751 // Chunk lists for this region is no longer needed.
3752 used_memory += pss->oops_into_optional_region(hr)->used_memory();
3753 }
3754
3755 Tickspan scan_time = (Ticks::now() - start) - copy_time;
3756 G1GCPhaseTimes* p = _g1h->phase_times();
3757 p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds());
3758 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds());
3759
3760 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards);
3761 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards);
3762 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards);
3763 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, used_memory, G1GCPhaseTimes::OptCSetUsedMemory);
3764 }
3765
3766 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3767 Ticks start = Ticks::now();
3768 G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy);
3769 cl.do_void();
3770
3771 Tickspan evac_time = (Ticks::now() - start);
3772 G1GCPhaseTimes* p = _g1h->phase_times();
3773 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds());
3774 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation");
3775 }
3776
3777 public:
3778 G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h,
3779 G1ParScanThreadStateSet* per_thread_states,
3780 G1OptionalCSet* cset,
3781 RefToScanQueueSet* queues,
3782 uint n_workers) :
3783 AbstractGangTask("G1 Evacuation Optional Region Task"),
3784 _g1h(g1h),
3785 _per_thread_states(per_thread_states),
3786 _optional(cset),
3787 _queues(queues),
3788 _terminator(n_workers, _queues) {
3789 }
3790
3791 void work(uint worker_id) {
3792 ResourceMark rm;
3793 HandleMark hm;
3794
3795 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3796 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3797
3798 scan_roots(pss, worker_id);
3799 evacuate_live_objects(pss, worker_id);
3800 }
3801 };
3802
3803 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) {
3804 class G1MarkScope : public MarkScope {};
3805 G1MarkScope code_mark_scope;
3806
3807 G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers());
3808 workers()->run_task(&task);
3809 }
3810
3811 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3812 G1OptionalCSet optional_cset(&_collection_set, per_thread_states);
3813 if (optional_cset.is_empty()) {
3814 return;
3815 }
3816
3817 if (evacuation_failed()) {
3818 return;
3819 }
3820
3821 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3822
3823 double start_time_sec = os::elapsedTime();
3824
3825 do {
3826 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3827 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3828
3829 if (time_left_ms < 0) {
3830 log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms);
3831 break;
3832 }
3833
3834 optional_cset.prepare_evacuation(time_left_ms * _policy->optional_evacuation_fraction());
3835 if (optional_cset.prepare_failed()) {
3836 log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms);
3837 break;
3838 }
3839
3840 evacuate_optional_regions(per_thread_states, &optional_cset);
3841
3842 optional_cset.complete_evacuation();
3843 if (optional_cset.evacuation_failed()) {
3844 break;
3845 }
3846 } while (!optional_cset.is_empty());
3847
3848 phase_times()->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0);
3849 }
3850
3851 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3852 // Also cleans the card table from temporary duplicate detection information used
3853 // during UpdateRS/ScanRS.
3854 rem_set()->cleanup_after_oops_into_collection_set_do();
3855
3856 // Process any discovered reference objects - we have
3857 // to do this _before_ we retire the GC alloc regions
3858 // as we may have to copy some 'reachable' referent
3859 // objects (and their reachable sub-graphs) that were
3860 // not copied during the pause.
3861 process_discovered_references(per_thread_states);
3862
3863 G1STWIsAliveClosure is_alive(this);
3864 G1KeepAliveClosure keep_alive(this);
3865
3866 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3867 phase_times()->weak_phase_times());
3868
3869 if (G1StringDedup::is_enabled()) {
3870 double string_dedup_time_ms = os::elapsedTime();
3871
3872 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3873
3874 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3875 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3876 }
3877
3878 _allocator->release_gc_alloc_regions(evacuation_info);
3879
3880 if (evacuation_failed()) {
3881 restore_after_evac_failure();
3882
3883 // Reset the G1EvacuationFailureALot counters and flags
3884 NOT_PRODUCT(reset_evacuation_should_fail();)
3885
3886 double recalculate_used_start = os::elapsedTime();
3887 set_used(recalculate_used());
3888 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3889
3890 if (_archive_allocator != NULL) {
3891 _archive_allocator->clear_used();
3892 }
3893 for (uint i = 0; i < ParallelGCThreads; i++) {
3894 if (_evacuation_failed_info_array[i].has_failed()) {
3895 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3896 }
3897 }
3898 } else {
3899 // The "used" of the the collection set have already been subtracted
3900 // when they were freed. Add in the bytes evacuated.
3901 increase_used(policy()->bytes_copied_during_gc());
3902 }
3903
3904 _preserved_marks_set.assert_empty();
3905
3906 merge_per_thread_state_info(per_thread_states);
3907
3908 // Reset and re-enable the hot card cache.
3909 // Note the counts for the cards in the regions in the
3910 // collection set are reset when the collection set is freed.
3911 _hot_card_cache->reset_hot_cache();
3912 _hot_card_cache->set_use_cache(true);
3913
3914 purge_code_root_memory();
3915
3916 redirty_logged_cards();
3917
3918 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3919
3920 eagerly_reclaim_humongous_regions();
3921
3922 record_obj_copy_mem_stats();
3923
3924 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3925 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3926
3927 #if COMPILER2_OR_JVMCI
3928 double start = os::elapsedTime();
3929 DerivedPointerTable::update_pointers();
3930 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3931 #endif
3932 policy()->print_age_table();
3933 }
3934
3935 void G1CollectedHeap::record_obj_copy_mem_stats() {
3936 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3937
3938 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3939 create_g1_evac_summary(&_old_evac_stats));
3940 }
3941
3942 void G1CollectedHeap::free_region(HeapRegion* hr,
3943 FreeRegionList* free_list,
3944 bool skip_remset,
3945 bool skip_hot_card_cache,
3946 bool locked) {
3947 assert(!hr->is_free(), "the region should not be free");
3948 assert(!hr->is_empty(), "the region should not be empty");
3949 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3950 assert(free_list != NULL, "pre-condition");
3951
3952 if (G1VerifyBitmaps) {
3953 MemRegion mr(hr->bottom(), hr->end());
3954 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3955 }
3956
3957 // Clear the card counts for this region.
3958 // Note: we only need to do this if the region is not young
3959 // (since we don't refine cards in young regions).
3960 if (!skip_hot_card_cache && !hr->is_young()) {
3961 _hot_card_cache->reset_card_counts(hr);
3962 }
3963 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3964 _policy->remset_tracker()->update_at_free(hr);
3965 free_list->add_ordered(hr);
3966 }
3967
3968 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3969 FreeRegionList* free_list) {
3970 assert(hr->is_humongous(), "this is only for humongous regions");
3971 assert(free_list != NULL, "pre-condition");
3972 hr->clear_humongous();
3973 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3974 }
3975
3976 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3977 const uint humongous_regions_removed) {
3978 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3979 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3980 _old_set.bulk_remove(old_regions_removed);
3981 _humongous_set.bulk_remove(humongous_regions_removed);
3982 }
3983
3984 }
3985
3986 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3987 assert(list != NULL, "list can't be null");
3988 if (!list->is_empty()) {
3989 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3990 _hrm->insert_list_into_free_list(list);
3991 }
3992 }
3993
3994 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3995 decrease_used(bytes);
3996 }
3997
3998 class G1FreeCollectionSetTask : public AbstractGangTask {
3999 private:
4000
4001 // Closure applied to all regions in the collection set to do work that needs to
4002 // be done serially in a single thread.
4003 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4004 private:
4005 G1EvacuationInfo* _evacuation_info;
4006 const size_t* _surviving_young_words;
4007
4008 // Bytes used in successfully evacuated regions before the evacuation.
4009 size_t _before_used_bytes;
4010 // Bytes used in unsucessfully evacuated regions before the evacuation
4011 size_t _after_used_bytes;
4012
4013 size_t _bytes_allocated_in_old_since_last_gc;
4014
4015 size_t _failure_used_words;
4016 size_t _failure_waste_words;
4017
4018 FreeRegionList _local_free_list;
4019 public:
4020 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4021 HeapRegionClosure(),
4022 _evacuation_info(evacuation_info),
4023 _surviving_young_words(surviving_young_words),
4024 _before_used_bytes(0),
4025 _after_used_bytes(0),
4026 _bytes_allocated_in_old_since_last_gc(0),
4027 _failure_used_words(0),
4028 _failure_waste_words(0),
4029 _local_free_list("Local Region List for CSet Freeing") {
4030 }
4031
4032 virtual bool do_heap_region(HeapRegion* r) {
4033 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4034
4035 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4036 g1h->clear_in_cset(r);
4037
4038 if (r->is_young()) {
4039 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4040 "Young index %d is wrong for region %u of type %s with %u young regions",
4041 r->young_index_in_cset(),
4042 r->hrm_index(),
4043 r->get_type_str(),
4044 g1h->collection_set()->young_region_length());
4045 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4046 r->record_surv_words_in_group(words_survived);
4047 }
4048
4049 if (!r->evacuation_failed()) {
4050 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4051 _before_used_bytes += r->used();
4052 g1h->free_region(r,
4053 &_local_free_list,
4054 true, /* skip_remset */
4055 true, /* skip_hot_card_cache */
4056 true /* locked */);
4057 } else {
4058 r->uninstall_surv_rate_group();
4059 r->set_young_index_in_cset(-1);
4060 r->set_evacuation_failed(false);
4061 // When moving a young gen region to old gen, we "allocate" that whole region
4062 // there. This is in addition to any already evacuated objects. Notify the
4063 // policy about that.
4064 // Old gen regions do not cause an additional allocation: both the objects
4065 // still in the region and the ones already moved are accounted for elsewhere.
4066 if (r->is_young()) {
4067 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4068 }
4069 // The region is now considered to be old.
4070 r->set_old();
4071 // Do some allocation statistics accounting. Regions that failed evacuation
4072 // are always made old, so there is no need to update anything in the young
4073 // gen statistics, but we need to update old gen statistics.
4074 size_t used_words = r->marked_bytes() / HeapWordSize;
4075
4076 _failure_used_words += used_words;
4077 _failure_waste_words += HeapRegion::GrainWords - used_words;
4078
4079 g1h->old_set_add(r);
4080 _after_used_bytes += r->used();
4081 }
4082 return false;
4083 }
4084
4085 void complete_work() {
4086 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4087
4088 _evacuation_info->set_regions_freed(_local_free_list.length());
4089 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4090
4091 g1h->prepend_to_freelist(&_local_free_list);
4092 g1h->decrement_summary_bytes(_before_used_bytes);
4093
4094 G1Policy* policy = g1h->policy();
4095 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4096
4097 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4098 }
4099 };
4100
4101 G1CollectionSet* _collection_set;
4102 G1SerialFreeCollectionSetClosure _cl;
4103 const size_t* _surviving_young_words;
4104
4105 size_t _rs_lengths;
4106
4107 volatile jint _serial_work_claim;
4108
4109 struct WorkItem {
4110 uint region_idx;
4111 bool is_young;
4112 bool evacuation_failed;
4113
4114 WorkItem(HeapRegion* r) {
4115 region_idx = r->hrm_index();
4116 is_young = r->is_young();
4117 evacuation_failed = r->evacuation_failed();
4118 }
4119 };
4120
4121 volatile size_t _parallel_work_claim;
4122 size_t _num_work_items;
4123 WorkItem* _work_items;
4124
4125 void do_serial_work() {
4126 // Need to grab the lock to be allowed to modify the old region list.
4127 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4128 _collection_set->iterate(&_cl);
4129 }
4130
4131 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4132 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4133
4134 HeapRegion* r = g1h->region_at(region_idx);
4135 assert(!g1h->is_on_master_free_list(r), "sanity");
4136
4137 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4138
4139 if (!is_young) {
4140 g1h->_hot_card_cache->reset_card_counts(r);
4141 }
4142
4143 if (!evacuation_failed) {
4144 r->rem_set()->clear_locked();
4145 }
4146 }
4147
4148 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4149 private:
4150 size_t _cur_idx;
4151 WorkItem* _work_items;
4152 public:
4153 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4154
4155 virtual bool do_heap_region(HeapRegion* r) {
4156 _work_items[_cur_idx++] = WorkItem(r);
4157 return false;
4158 }
4159 };
4160
4161 void prepare_work() {
4162 G1PrepareFreeCollectionSetClosure cl(_work_items);
4163 _collection_set->iterate(&cl);
4164 }
4165
4166 void complete_work() {
4167 _cl.complete_work();
4168
4169 G1Policy* policy = G1CollectedHeap::heap()->policy();
4170 policy->record_max_rs_lengths(_rs_lengths);
4171 policy->cset_regions_freed();
4172 }
4173 public:
4174 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4175 AbstractGangTask("G1 Free Collection Set"),
4176 _collection_set(collection_set),
4177 _cl(evacuation_info, surviving_young_words),
4178 _surviving_young_words(surviving_young_words),
4179 _rs_lengths(0),
4180 _serial_work_claim(0),
4181 _parallel_work_claim(0),
4182 _num_work_items(collection_set->region_length()),
4183 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4184 prepare_work();
4185 }
4186
4187 ~G1FreeCollectionSetTask() {
4188 complete_work();
4189 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4190 }
4191
4192 // Chunk size for work distribution. The chosen value has been determined experimentally
4193 // to be a good tradeoff between overhead and achievable parallelism.
4194 static uint chunk_size() { return 32; }
4195
4196 virtual void work(uint worker_id) {
4197 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4198
4199 // Claim serial work.
4200 if (_serial_work_claim == 0) {
4201 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4202 if (value == 0) {
4203 double serial_time = os::elapsedTime();
4204 do_serial_work();
4205 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4206 }
4207 }
4208
4209 // Start parallel work.
4210 double young_time = 0.0;
4211 bool has_young_time = false;
4212 double non_young_time = 0.0;
4213 bool has_non_young_time = false;
4214
4215 while (true) {
4216 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4217 size_t cur = end - chunk_size();
4218
4219 if (cur >= _num_work_items) {
4220 break;
4221 }
4222
4223 EventGCPhaseParallel event;
4224 double start_time = os::elapsedTime();
4225
4226 end = MIN2(end, _num_work_items);
4227
4228 for (; cur < end; cur++) {
4229 bool is_young = _work_items[cur].is_young;
4230
4231 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4232
4233 double end_time = os::elapsedTime();
4234 double time_taken = end_time - start_time;
4235 if (is_young) {
4236 young_time += time_taken;
4237 has_young_time = true;
4238 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4239 } else {
4240 non_young_time += time_taken;
4241 has_non_young_time = true;
4242 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4243 }
4244 start_time = end_time;
4245 }
4246 }
4247
4248 if (has_young_time) {
4249 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4250 }
4251 if (has_non_young_time) {
4252 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4253 }
4254 }
4255 };
4256
4257 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4258 _eden.clear();
4259
4260 double free_cset_start_time = os::elapsedTime();
4261
4262 {
4263 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4264 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4265
4266 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4267
4268 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4269 cl.name(),
4270 num_workers,
4271 _collection_set.region_length());
4272 workers()->run_task(&cl, num_workers);
4273 }
4274 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4275
4276 collection_set->clear();
4277 }
4278
4279 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4280 private:
4281 FreeRegionList* _free_region_list;
4282 HeapRegionSet* _proxy_set;
4283 uint _humongous_objects_reclaimed;
4284 uint _humongous_regions_reclaimed;
4285 size_t _freed_bytes;
4286 public:
4287
4288 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4289 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4290 }
4291
4292 virtual bool do_heap_region(HeapRegion* r) {
4293 if (!r->is_starts_humongous()) {
4294 return false;
4295 }
4296
4297 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4298
4299 oop obj = (oop)r->bottom();
4300 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4301
4302 // The following checks whether the humongous object is live are sufficient.
4303 // The main additional check (in addition to having a reference from the roots
4304 // or the young gen) is whether the humongous object has a remembered set entry.
4305 //
4306 // A humongous object cannot be live if there is no remembered set for it
4307 // because:
4308 // - there can be no references from within humongous starts regions referencing
4309 // the object because we never allocate other objects into them.
4310 // (I.e. there are no intra-region references that may be missed by the
4311 // remembered set)
4312 // - as soon there is a remembered set entry to the humongous starts region
4313 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4314 // until the end of a concurrent mark.
4315 //
4316 // It is not required to check whether the object has been found dead by marking
4317 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4318 // all objects allocated during that time are considered live.
4319 // SATB marking is even more conservative than the remembered set.
4320 // So if at this point in the collection there is no remembered set entry,
4321 // nobody has a reference to it.
4322 // At the start of collection we flush all refinement logs, and remembered sets
4323 // are completely up-to-date wrt to references to the humongous object.
4324 //
4325 // Other implementation considerations:
4326 // - never consider object arrays at this time because they would pose
4327 // considerable effort for cleaning up the the remembered sets. This is
4328 // required because stale remembered sets might reference locations that
4329 // are currently allocated into.
4330 uint region_idx = r->hrm_index();
4331 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4332 !r->rem_set()->is_empty()) {
4333 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",
4334 region_idx,
4335 (size_t)obj->size() * HeapWordSize,
4336 p2i(r->bottom()),
4337 r->rem_set()->occupied(),
4338 r->rem_set()->strong_code_roots_list_length(),
4339 next_bitmap->is_marked(r->bottom()),
4340 g1h->is_humongous_reclaim_candidate(region_idx),
4341 obj->is_typeArray()
4342 );
4343 return false;
4344 }
4345
4346 guarantee(obj->is_typeArray(),
4347 "Only eagerly reclaiming type arrays is supported, but the object "
4348 PTR_FORMAT " is not.", p2i(r->bottom()));
4349
4350 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",
4351 region_idx,
4352 (size_t)obj->size() * HeapWordSize,
4353 p2i(r->bottom()),
4354 r->rem_set()->occupied(),
4355 r->rem_set()->strong_code_roots_list_length(),
4356 next_bitmap->is_marked(r->bottom()),
4357 g1h->is_humongous_reclaim_candidate(region_idx),
4358 obj->is_typeArray()
4359 );
4360
4361 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4362 cm->humongous_object_eagerly_reclaimed(r);
4363 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4364 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4365 region_idx,
4366 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4367 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4368 _humongous_objects_reclaimed++;
4369 do {
4370 HeapRegion* next = g1h->next_region_in_humongous(r);
4371 _freed_bytes += r->used();
4372 r->set_containing_set(NULL);
4373 _humongous_regions_reclaimed++;
4374 g1h->free_humongous_region(r, _free_region_list);
4375 r = next;
4376 } while (r != NULL);
4377
4378 return false;
4379 }
4380
4381 uint humongous_objects_reclaimed() {
4382 return _humongous_objects_reclaimed;
4383 }
4384
4385 uint humongous_regions_reclaimed() {
4386 return _humongous_regions_reclaimed;
4387 }
4388
4389 size_t bytes_freed() const {
4390 return _freed_bytes;
4391 }
4392 };
4393
4394 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4395 assert_at_safepoint_on_vm_thread();
4396
4397 if (!G1EagerReclaimHumongousObjects ||
4398 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4399 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4400 return;
4401 }
4402
4403 double start_time = os::elapsedTime();
4404
4405 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4406
4407 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4408 heap_region_iterate(&cl);
4409
4410 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4411
4412 G1HRPrinter* hrp = hr_printer();
4413 if (hrp->is_active()) {
4414 FreeRegionListIterator iter(&local_cleanup_list);
4415 while (iter.more_available()) {
4416 HeapRegion* hr = iter.get_next();
4417 hrp->cleanup(hr);
4418 }
4419 }
4420
4421 prepend_to_freelist(&local_cleanup_list);
4422 decrement_summary_bytes(cl.bytes_freed());
4423
4424 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4425 cl.humongous_objects_reclaimed());
4426 }
4427
4428 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4429 public:
4430 virtual bool do_heap_region(HeapRegion* r) {
4431 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4432 G1CollectedHeap::heap()->clear_in_cset(r);
4433 r->set_young_index_in_cset(-1);
4434 return false;
4435 }
4436 };
4437
4438 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4439 G1AbandonCollectionSetClosure cl;
4440 collection_set->iterate(&cl);
4441
4442 collection_set->clear();
4443 collection_set->stop_incremental_building();
4444 }
4445
4446 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4447 return _allocator->is_retained_old_region(hr);
4448 }
4449
4450 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4451 _eden.add(hr);
4452 _policy->set_region_eden(hr);
4453 }
4454
4455 #ifdef ASSERT
4456
4457 class NoYoungRegionsClosure: public HeapRegionClosure {
4458 private:
4459 bool _success;
4460 public:
4461 NoYoungRegionsClosure() : _success(true) { }
4462 bool do_heap_region(HeapRegion* r) {
4463 if (r->is_young()) {
4464 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4465 p2i(r->bottom()), p2i(r->end()));
4466 _success = false;
4467 }
4468 return false;
4469 }
4470 bool success() { return _success; }
4471 };
4472
4473 bool G1CollectedHeap::check_young_list_empty() {
4474 bool ret = (young_regions_count() == 0);
4475
4476 NoYoungRegionsClosure closure;
4477 heap_region_iterate(&closure);
4478 ret = ret && closure.success();
4479
4480 return ret;
4481 }
4482
4483 #endif // ASSERT
4484
4485 class TearDownRegionSetsClosure : public HeapRegionClosure {
4486 HeapRegionSet *_old_set;
4487
4488 public:
4489 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4490
4491 bool do_heap_region(HeapRegion* r) {
4492 if (r->is_old()) {
4493 _old_set->remove(r);
4494 } else if(r->is_young()) {
4495 r->uninstall_surv_rate_group();
4496 } else {
4497 // We ignore free regions, we'll empty the free list afterwards.
4498 // We ignore humongous and archive regions, we're not tearing down these
4499 // sets.
4500 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4501 "it cannot be another type");
4502 }
4503 return false;
4504 }
4505
4506 ~TearDownRegionSetsClosure() {
4507 assert(_old_set->is_empty(), "post-condition");
4508 }
4509 };
4510
4511 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4512 assert_at_safepoint_on_vm_thread();
4513
4514 if (!free_list_only) {
4515 TearDownRegionSetsClosure cl(&_old_set);
4516 heap_region_iterate(&cl);
4517
4518 // Note that emptying the _young_list is postponed and instead done as
4519 // the first step when rebuilding the regions sets again. The reason for
4520 // this is that during a full GC string deduplication needs to know if
4521 // a collected region was young or old when the full GC was initiated.
4522 }
4523 _hrm->remove_all_free_regions();
4524 }
4525
4526 void G1CollectedHeap::increase_used(size_t bytes) {
4527 _summary_bytes_used += bytes;
4528 }
4529
4530 void G1CollectedHeap::decrease_used(size_t bytes) {
4531 assert(_summary_bytes_used >= bytes,
4532 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4533 _summary_bytes_used, bytes);
4534 _summary_bytes_used -= bytes;
4535 }
4536
4537 void G1CollectedHeap::set_used(size_t bytes) {
4538 _summary_bytes_used = bytes;
4539 }
4540
4541 class RebuildRegionSetsClosure : public HeapRegionClosure {
4542 private:
4543 bool _free_list_only;
4544
4545 HeapRegionSet* _old_set;
4546 HeapRegionManager* _hrm;
4547
4548 size_t _total_used;
4549
4550 public:
4551 RebuildRegionSetsClosure(bool free_list_only,
4552 HeapRegionSet* old_set,
4553 HeapRegionManager* hrm) :
4554 _free_list_only(free_list_only),
4555 _old_set(old_set), _hrm(hrm), _total_used(0) {
4556 assert(_hrm->num_free_regions() == 0, "pre-condition");
4557 if (!free_list_only) {
4558 assert(_old_set->is_empty(), "pre-condition");
4559 }
4560 }
4561
4562 bool do_heap_region(HeapRegion* r) {
4563 if (r->is_empty()) {
4564 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4565 // Add free regions to the free list
4566 r->set_free();
4567 _hrm->insert_into_free_list(r);
4568 } else if (!_free_list_only) {
4569 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4570
4571 if (r->is_archive() || r->is_humongous()) {
4572 // We ignore archive and humongous regions. We left these sets unchanged.
4573 } else {
4574 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4575 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4576 r->move_to_old();
4577 _old_set->add(r);
4578 }
4579 _total_used += r->used();
4580 }
4581
4582 return false;
4583 }
4584
4585 size_t total_used() {
4586 return _total_used;
4587 }
4588 };
4589
4590 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4591 assert_at_safepoint_on_vm_thread();
4592
4593 if (!free_list_only) {
4594 _eden.clear();
4595 _survivor.clear();
4596 }
4597
4598 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4599 heap_region_iterate(&cl);
4600
4601 if (!free_list_only) {
4602 set_used(cl.total_used());
4603 if (_archive_allocator != NULL) {
4604 _archive_allocator->clear_used();
4605 }
4606 }
4607 assert(used() == recalculate_used(),
4608 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4609 used(), recalculate_used());
4610 }
4611
4612 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4613 HeapRegion* hr = heap_region_containing(p);
4614 return hr->is_in(p);
4615 }
4616
4617 // Methods for the mutator alloc region
4618
4619 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4620 bool force) {
4621 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4622 bool should_allocate = policy()->should_allocate_mutator_region();
4623 if (force || should_allocate) {
4624 HeapRegion* new_alloc_region = new_region(word_size,
4625 HeapRegionType::Eden,
4626 false /* do_expand */);
4627 if (new_alloc_region != NULL) {
4628 set_region_short_lived_locked(new_alloc_region);
4629 _hr_printer.alloc(new_alloc_region, !should_allocate);
4630 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4631 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4632 return new_alloc_region;
4633 }
4634 }
4635 return NULL;
4636 }
4637
4638 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4639 size_t allocated_bytes) {
4640 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4641 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4642
4643 collection_set()->add_eden_region(alloc_region);
4644 increase_used(allocated_bytes);
4645 _hr_printer.retire(alloc_region);
4646 // We update the eden sizes here, when the region is retired,
4647 // instead of when it's allocated, since this is the point that its
4648 // used space has been recorded in _summary_bytes_used.
4649 g1mm()->update_eden_size();
4650 }
4651
4652 // Methods for the GC alloc regions
4653
4654 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4655 if (dest.is_old()) {
4656 return true;
4657 } else {
4658 return survivor_regions_count() < policy()->max_survivor_regions();
4659 }
4660 }
4661
4662 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4663 assert(FreeList_lock->owned_by_self(), "pre-condition");
4664
4665 if (!has_more_regions(dest)) {
4666 return NULL;
4667 }
4668
4669 HeapRegionType type;
4670 if (dest.is_young()) {
4671 type = HeapRegionType::Survivor;
4672 } else {
4673 type = HeapRegionType::Old;
4674 }
4675
4676 HeapRegion* new_alloc_region = new_region(word_size,
4677 type,
4678 true /* do_expand */);
4679
4680 if (new_alloc_region != NULL) {
4681 if (type.is_survivor()) {
4682 new_alloc_region->set_survivor();
4683 _survivor.add(new_alloc_region);
4684 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4685 } else {
4686 new_alloc_region->set_old();
4687 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4688 }
4689 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4690 _hr_printer.alloc(new_alloc_region);
4691 return new_alloc_region;
4692 }
4693 return NULL;
4694 }
4695
4696 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4697 size_t allocated_bytes,
4698 InCSetState dest) {
4699 policy()->record_bytes_copied_during_gc(allocated_bytes);
4700 if (dest.is_old()) {
4701 old_set_add(alloc_region);
4702 }
4703
4704 bool const during_im = collector_state()->in_initial_mark_gc();
4705 if (during_im && allocated_bytes > 0) {
4706 _cm->root_regions()->add(alloc_region);
4707 }
4708 _hr_printer.retire(alloc_region);
4709 }
4710
4711 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4712 bool expanded = false;
4713 uint index = _hrm->find_highest_free(&expanded);
4714
4715 if (index != G1_NO_HRM_INDEX) {
4716 if (expanded) {
4717 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4718 HeapRegion::GrainWords * HeapWordSize);
4719 }
4720 _hrm->allocate_free_regions_starting_at(index, 1);
4721 return region_at(index);
4722 }
4723 return NULL;
4724 }
4725
4726 // Optimized nmethod scanning
4727
4728 class RegisterNMethodOopClosure: public OopClosure {
4729 G1CollectedHeap* _g1h;
4730 nmethod* _nm;
4731
4732 template <class T> void do_oop_work(T* p) {
4733 T heap_oop = RawAccess<>::oop_load(p);
4734 if (!CompressedOops::is_null(heap_oop)) {
4735 oop obj = CompressedOops::decode_not_null(heap_oop);
4736 HeapRegion* hr = _g1h->heap_region_containing(obj);
4737 assert(!hr->is_continues_humongous(),
4738 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4739 " starting at " HR_FORMAT,
4740 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4741
4742 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4743 hr->add_strong_code_root_locked(_nm);
4744 }
4745 }
4746
4747 public:
4748 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4749 _g1h(g1h), _nm(nm) {}
4750
4751 void do_oop(oop* p) { do_oop_work(p); }
4752 void do_oop(narrowOop* p) { do_oop_work(p); }
4753 };
4754
4755 class UnregisterNMethodOopClosure: public OopClosure {
4756 G1CollectedHeap* _g1h;
4757 nmethod* _nm;
4758
4759 template <class T> void do_oop_work(T* p) {
4760 T heap_oop = RawAccess<>::oop_load(p);
4761 if (!CompressedOops::is_null(heap_oop)) {
4762 oop obj = CompressedOops::decode_not_null(heap_oop);
4763 HeapRegion* hr = _g1h->heap_region_containing(obj);
4764 assert(!hr->is_continues_humongous(),
4765 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4766 " starting at " HR_FORMAT,
4767 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4768
4769 hr->remove_strong_code_root(_nm);
4770 }
4771 }
4772
4773 public:
4774 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4775 _g1h(g1h), _nm(nm) {}
4776
4777 void do_oop(oop* p) { do_oop_work(p); }
4778 void do_oop(narrowOop* p) { do_oop_work(p); }
4779 };
4780
4781 // Returns true if the reference points to an object that
4782 // can move in an incremental collection.
4783 bool G1CollectedHeap::is_scavengable(oop obj) {
4784 HeapRegion* hr = heap_region_containing(obj);
4785 return !hr->is_pinned();
4786 }
4787
4788 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4789 guarantee(nm != NULL, "sanity");
4790 RegisterNMethodOopClosure reg_cl(this, nm);
4791 nm->oops_do(®_cl);
4792 }
4793
4794 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4795 guarantee(nm != NULL, "sanity");
4796 UnregisterNMethodOopClosure reg_cl(this, nm);
4797 nm->oops_do(®_cl, true);
4798 }
4799
4800 void G1CollectedHeap::purge_code_root_memory() {
4801 double purge_start = os::elapsedTime();
4802 G1CodeRootSet::purge();
4803 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4804 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4805 }
4806
4807 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4808 G1CollectedHeap* _g1h;
4809
4810 public:
4811 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4812 _g1h(g1h) {}
4813
4814 void do_code_blob(CodeBlob* cb) {
4815 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4816 if (nm == NULL) {
4817 return;
4818 }
4819
4820 if (ScavengeRootsInCode) {
4821 _g1h->register_nmethod(nm);
4822 }
4823 }
4824 };
4825
4826 void G1CollectedHeap::rebuild_strong_code_roots() {
4827 RebuildStrongCodeRootClosure blob_cl(this);
4828 CodeCache::blobs_do(&blob_cl);
4829 }
4830
4831 void G1CollectedHeap::initialize_serviceability() {
4832 _g1mm->initialize_serviceability();
4833 }
4834
4835 MemoryUsage G1CollectedHeap::memory_usage() {
4836 return _g1mm->memory_usage();
4837 }
4838
4839 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4840 return _g1mm->memory_managers();
4841 }
4842
4843 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4844 return _g1mm->memory_pools();
4845 }