1 /*
2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1BarrierSet.hpp"
33 #include "gc/g1/g1CollectedHeap.inline.hpp"
34 #include "gc/g1/g1CollectionSet.hpp"
35 #include "gc/g1/g1CollectorPolicy.hpp"
36 #include "gc/g1/g1CollectorState.hpp"
37 #include "gc/g1/g1ConcurrentRefine.hpp"
38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1MemoryPool.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1SATBMarkQueueSet.hpp"
56 #include "gc/g1/g1StringDedup.hpp"
57 #include "gc/g1/g1ThreadLocalData.hpp"
58 #include "gc/g1/g1YCTypes.hpp"
59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
60 #include "gc/g1/heapRegion.inline.hpp"
61 #include "gc/g1/heapRegionRemSet.hpp"
62 #include "gc/g1/heapRegionSet.inline.hpp"
63 #include "gc/g1/vm_operations_g1.hpp"
64 #include "gc/shared/adaptiveSizePolicy.hpp"
65 #include "gc/shared/gcHeapSummary.hpp"
66 #include "gc/shared/gcId.hpp"
67 #include "gc/shared/gcLocker.hpp"
68 #include "gc/shared/gcTimer.hpp"
69 #include "gc/shared/gcTrace.hpp"
70 #include "gc/shared/gcTraceTime.inline.hpp"
71 #include "gc/shared/generationSpec.hpp"
72 #include "gc/shared/isGCActiveMark.hpp"
73 #include "gc/shared/oopStorageParState.hpp"
74 #include "gc/shared/parallelCleaning.hpp"
75 #include "gc/shared/preservedMarks.inline.hpp"
76 #include "gc/shared/suspendibleThreadSet.hpp"
77 #include "gc/shared/referenceProcessor.inline.hpp"
78 #include "gc/shared/taskqueue.inline.hpp"
79 #include "gc/shared/weakProcessor.inline.hpp"
80 #include "logging/log.hpp"
81 #include "memory/allocation.hpp"
82 #include "memory/iterator.hpp"
83 #include "memory/metaspaceShared.inline.hpp"
84 #include "memory/resourceArea.hpp"
85 #include "oops/access.inline.hpp"
86 #include "oops/compressedOops.inline.hpp"
87 #include "oops/oop.inline.hpp"
88 #include "runtime/atomic.hpp"
89 #include "runtime/flags/flagSetting.hpp"
90 #include "runtime/handles.inline.hpp"
91 #include "runtime/init.hpp"
92 #include "runtime/orderAccess.hpp"
93 #include "runtime/threadSMR.hpp"
94 #include "runtime/vmThread.hpp"
95 #include "utilities/align.hpp"
96 #include "utilities/globalDefinitions.hpp"
97 #include "utilities/stack.inline.hpp"
98
99 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
100
101 // INVARIANTS/NOTES
102 //
103 // All allocation activity covered by the G1CollectedHeap interface is
104 // serialized by acquiring the HeapLock. This happens in mem_allocate
105 // and allocate_new_tlab, which are the "entry" points to the
106 // allocation code from the rest of the JVM. (Note that this does not
107 // apply to TLAB allocation, which is not part of this interface: it
108 // is done by clients of this interface.)
109
110 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
111 private:
112 size_t _num_dirtied;
113 G1CollectedHeap* _g1h;
114 G1CardTable* _g1_ct;
115
116 HeapRegion* region_for_card(jbyte* card_ptr) const {
117 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
118 }
119
120 bool will_become_free(HeapRegion* hr) const {
121 // A region will be freed by free_collection_set if the region is in the
122 // collection set and has not had an evacuation failure.
123 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
124 }
125
126 public:
127 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
128 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
129
130 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
131 HeapRegion* hr = region_for_card(card_ptr);
132
133 // Should only dirty cards in regions that won't be freed.
134 if (!will_become_free(hr)) {
135 *card_ptr = G1CardTable::dirty_card_val();
136 _num_dirtied++;
137 }
138
139 return true;
140 }
141
142 size_t num_dirtied() const { return _num_dirtied; }
143 };
144
145
146 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
147 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
148 }
149
150 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
151 // The from card cache is not the memory that is actually committed. So we cannot
152 // take advantage of the zero_filled parameter.
153 reset_from_card_cache(start_idx, num_regions);
154 }
155
156
157 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
158 MemRegion mr) {
159 return new HeapRegion(hrs_index, bot(), mr);
160 }
161
162 // Private methods.
163
164 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
165 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
166 "the only time we use this to allocate a humongous region is "
167 "when we are allocating a single humongous region");
168
169 HeapRegion* res = _hrm.allocate_free_region(is_old);
170
171 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
172 // Currently, only attempts to allocate GC alloc regions set
173 // do_expand to true. So, we should only reach here during a
174 // safepoint. If this assumption changes we might have to
175 // reconsider the use of _expand_heap_after_alloc_failure.
176 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
177
178 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
179 word_size * HeapWordSize);
180
181 if (expand(word_size * HeapWordSize)) {
182 // Given that expand() succeeded in expanding the heap, and we
183 // always expand the heap by an amount aligned to the heap
184 // region size, the free list should in theory not be empty.
185 // In either case allocate_free_region() will check for NULL.
186 res = _hrm.allocate_free_region(is_old);
187 } else {
188 _expand_heap_after_alloc_failure = false;
189 }
190 }
191 return res;
192 }
193
194 HeapWord*
195 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
196 uint num_regions,
197 size_t word_size) {
198 assert(first != G1_NO_HRM_INDEX, "pre-condition");
199 assert(is_humongous(word_size), "word_size should be humongous");
200 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
201
202 // Index of last region in the series.
203 uint last = first + num_regions - 1;
204
205 // We need to initialize the region(s) we just discovered. This is
206 // a bit tricky given that it can happen concurrently with
207 // refinement threads refining cards on these regions and
208 // potentially wanting to refine the BOT as they are scanning
209 // those cards (this can happen shortly after a cleanup; see CR
210 // 6991377). So we have to set up the region(s) carefully and in
211 // a specific order.
212
213 // The word size sum of all the regions we will allocate.
214 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
215 assert(word_size <= word_size_sum, "sanity");
216
217 // This will be the "starts humongous" region.
218 HeapRegion* first_hr = region_at(first);
219 // The header of the new object will be placed at the bottom of
220 // the first region.
221 HeapWord* new_obj = first_hr->bottom();
222 // This will be the new top of the new object.
223 HeapWord* obj_top = new_obj + word_size;
224
225 // First, we need to zero the header of the space that we will be
226 // allocating. When we update top further down, some refinement
227 // threads might try to scan the region. By zeroing the header we
228 // ensure that any thread that will try to scan the region will
229 // come across the zero klass word and bail out.
230 //
231 // NOTE: It would not have been correct to have used
232 // CollectedHeap::fill_with_object() and make the space look like
233 // an int array. The thread that is doing the allocation will
234 // later update the object header to a potentially different array
235 // type and, for a very short period of time, the klass and length
236 // fields will be inconsistent. This could cause a refinement
237 // thread to calculate the object size incorrectly.
238 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
239
240 // Next, pad out the unused tail of the last region with filler
241 // objects, for improved usage accounting.
242 // How many words we use for filler objects.
243 size_t word_fill_size = word_size_sum - word_size;
244
245 // How many words memory we "waste" which cannot hold a filler object.
246 size_t words_not_fillable = 0;
247
248 if (word_fill_size >= min_fill_size()) {
249 fill_with_objects(obj_top, word_fill_size);
250 } else if (word_fill_size > 0) {
251 // We have space to fill, but we cannot fit an object there.
252 words_not_fillable = word_fill_size;
253 word_fill_size = 0;
254 }
255
256 // We will set up the first region as "starts humongous". This
257 // will also update the BOT covering all the regions to reflect
258 // that there is a single object that starts at the bottom of the
259 // first region.
260 first_hr->set_starts_humongous(obj_top, word_fill_size);
261 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
262 // Then, if there are any, we will set up the "continues
263 // humongous" regions.
264 HeapRegion* hr = NULL;
265 for (uint i = first + 1; i <= last; ++i) {
266 hr = region_at(i);
267 hr->set_continues_humongous(first_hr);
268 _g1_policy->remset_tracker()->update_at_allocate(hr);
269 }
270
271 // Up to this point no concurrent thread would have been able to
272 // do any scanning on any region in this series. All the top
273 // fields still point to bottom, so the intersection between
274 // [bottom,top] and [card_start,card_end] will be empty. Before we
275 // update the top fields, we'll do a storestore to make sure that
276 // no thread sees the update to top before the zeroing of the
277 // object header and the BOT initialization.
278 OrderAccess::storestore();
279
280 // Now, we will update the top fields of the "continues humongous"
281 // regions except the last one.
282 for (uint i = first; i < last; ++i) {
283 hr = region_at(i);
284 hr->set_top(hr->end());
285 }
286
287 hr = region_at(last);
288 // If we cannot fit a filler object, we must set top to the end
289 // of the humongous object, otherwise we cannot iterate the heap
290 // and the BOT will not be complete.
291 hr->set_top(hr->end() - words_not_fillable);
292
293 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
294 "obj_top should be in last region");
295
296 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
297
298 assert(words_not_fillable == 0 ||
299 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
300 "Miscalculation in humongous allocation");
301
302 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
303
304 for (uint i = first; i <= last; ++i) {
305 hr = region_at(i);
306 _humongous_set.add(hr);
307 _hr_printer.alloc(hr);
308 }
309
310 return new_obj;
311 }
312
313 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
314 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
315 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
316 }
317
318 // If could fit into free regions w/o expansion, try.
319 // Otherwise, if can expand, do so.
320 // Otherwise, if using ex regions might help, try with ex given back.
321 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
322 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
323
324 _verifier->verify_region_sets_optional();
325
326 uint first = G1_NO_HRM_INDEX;
327 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
328
329 if (obj_regions == 1) {
330 // Only one region to allocate, try to use a fast path by directly allocating
331 // from the free lists. Do not try to expand here, we will potentially do that
332 // later.
333 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
334 if (hr != NULL) {
335 first = hr->hrm_index();
336 }
337 } else {
338 // Policy: Try only empty regions (i.e. already committed first). Maybe we
339 // are lucky enough to find some.
340 first = _hrm.find_contiguous_only_empty(obj_regions);
341 if (first != G1_NO_HRM_INDEX) {
342 _hrm.allocate_free_regions_starting_at(first, obj_regions);
343 }
344 }
345
346 if (first == G1_NO_HRM_INDEX) {
347 // Policy: We could not find enough regions for the humongous object in the
348 // free list. Look through the heap to find a mix of free and uncommitted regions.
349 // If so, try expansion.
350 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
351 if (first != G1_NO_HRM_INDEX) {
352 // We found something. Make sure these regions are committed, i.e. expand
353 // the heap. Alternatively we could do a defragmentation GC.
354 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
355 word_size * HeapWordSize);
356
357 _hrm.expand_at(first, obj_regions, workers());
358 g1_policy()->record_new_heap_size(num_regions());
359
360 #ifdef ASSERT
361 for (uint i = first; i < first + obj_regions; ++i) {
362 HeapRegion* hr = region_at(i);
363 assert(hr->is_free(), "sanity");
364 assert(hr->is_empty(), "sanity");
365 assert(is_on_master_free_list(hr), "sanity");
366 }
367 #endif
368 _hrm.allocate_free_regions_starting_at(first, obj_regions);
369 } else {
370 // Policy: Potentially trigger a defragmentation GC.
371 }
372 }
373
374 HeapWord* result = NULL;
375 if (first != G1_NO_HRM_INDEX) {
376 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
377 assert(result != NULL, "it should always return a valid result");
378
379 // A successful humongous object allocation changes the used space
380 // information of the old generation so we need to recalculate the
381 // sizes and update the jstat counters here.
382 g1mm()->update_sizes();
383 }
384
385 _verifier->verify_region_sets_optional();
386
387 return result;
388 }
389
390 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
391 size_t requested_size,
392 size_t* actual_size) {
393 assert_heap_not_locked_and_not_at_safepoint();
394 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
395
396 return attempt_allocation(min_size, requested_size, actual_size);
397 }
398
399 HeapWord*
400 G1CollectedHeap::mem_allocate(size_t word_size,
401 bool* gc_overhead_limit_was_exceeded) {
402 assert_heap_not_locked_and_not_at_safepoint();
403
404 if (is_humongous(word_size)) {
405 return attempt_allocation_humongous(word_size);
406 }
407 size_t dummy = 0;
408 return attempt_allocation(word_size, word_size, &dummy);
409 }
410
411 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
412 ResourceMark rm; // For retrieving the thread names in log messages.
413
414 // Make sure you read the note in attempt_allocation_humongous().
415
416 assert_heap_not_locked_and_not_at_safepoint();
417 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
418 "be called for humongous allocation requests");
419
420 // We should only get here after the first-level allocation attempt
421 // (attempt_allocation()) failed to allocate.
422
423 // We will loop until a) we manage to successfully perform the
424 // allocation or b) we successfully schedule a collection which
425 // fails to perform the allocation. b) is the only case when we'll
426 // return NULL.
427 HeapWord* result = NULL;
428 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
429 bool should_try_gc;
430 uint gc_count_before;
431
432 {
433 MutexLockerEx x(Heap_lock);
434 result = _allocator->attempt_allocation_locked(word_size);
435 if (result != NULL) {
436 return result;
437 }
438
439 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
440 // This is different to when only GCLocker::needs_gc() is set: try to avoid
441 // waiting because the GCLocker is active to not wait too long.
442 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
443 // No need for an ergo message here, can_expand_young_list() does this when
444 // it returns true.
445 result = _allocator->attempt_allocation_force(word_size);
446 if (result != NULL) {
447 return result;
448 }
449 }
450 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
451 // the GCLocker initiated GC has been performed and then retry. This includes
452 // the case when the GC Locker is not active but has not been performed.
453 should_try_gc = !GCLocker::needs_gc();
454 // Read the GC count while still holding the Heap_lock.
455 gc_count_before = total_collections();
456 }
457
458 if (should_try_gc) {
459 bool succeeded;
460 result = do_collection_pause(word_size, gc_count_before, &succeeded,
461 GCCause::_g1_inc_collection_pause);
462 if (result != NULL) {
463 assert(succeeded, "only way to get back a non-NULL result");
464 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
465 Thread::current()->name(), p2i(result));
466 return result;
467 }
468
469 if (succeeded) {
470 // We successfully scheduled a collection which failed to allocate. No
471 // point in trying to allocate further. We'll just return NULL.
472 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
473 SIZE_FORMAT " words", Thread::current()->name(), word_size);
474 return NULL;
475 }
476 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
477 Thread::current()->name(), word_size);
478 } else {
479 // Failed to schedule a collection.
480 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
481 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
482 SIZE_FORMAT " words", Thread::current()->name(), word_size);
483 return NULL;
484 }
485 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
486 // The GCLocker is either active or the GCLocker initiated
487 // GC has not yet been performed. Stall until it is and
488 // then retry the allocation.
489 GCLocker::stall_until_clear();
490 gclocker_retry_count += 1;
491 }
492
493 // We can reach here if we were unsuccessful in scheduling a
494 // collection (because another thread beat us to it) or if we were
495 // stalled due to the GC locker. In either can we should retry the
496 // allocation attempt in case another thread successfully
497 // performed a collection and reclaimed enough space. We do the
498 // first attempt (without holding the Heap_lock) here and the
499 // follow-on attempt will be at the start of the next loop
500 // iteration (after taking the Heap_lock).
501 size_t dummy = 0;
502 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
503 if (result != NULL) {
504 return result;
505 }
506
507 // Give a warning if we seem to be looping forever.
508 if ((QueuedAllocationWarningCount > 0) &&
509 (try_count % QueuedAllocationWarningCount == 0)) {
510 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
511 Thread::current()->name(), try_count, word_size);
512 }
513 }
514
515 ShouldNotReachHere();
516 return NULL;
517 }
518
519 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
520 assert_at_safepoint_on_vm_thread();
521 if (_archive_allocator == NULL) {
522 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
523 }
524 }
525
526 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
527 // Allocations in archive regions cannot be of a size that would be considered
528 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
529 // may be different at archive-restore time.
530 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
531 }
532
533 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
534 assert_at_safepoint_on_vm_thread();
535 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
536 if (is_archive_alloc_too_large(word_size)) {
537 return NULL;
538 }
539 return _archive_allocator->archive_mem_allocate(word_size);
540 }
541
542 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
543 size_t end_alignment_in_bytes) {
544 assert_at_safepoint_on_vm_thread();
545 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
546
547 // Call complete_archive to do the real work, filling in the MemRegion
548 // array with the archive regions.
549 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
550 delete _archive_allocator;
551 _archive_allocator = NULL;
552 }
553
554 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
555 assert(ranges != NULL, "MemRegion array NULL");
556 assert(count != 0, "No MemRegions provided");
557 MemRegion reserved = _hrm.reserved();
558 for (size_t i = 0; i < count; i++) {
559 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
560 return false;
561 }
562 }
563 return true;
564 }
565
566 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
567 size_t count,
568 bool open) {
569 assert(!is_init_completed(), "Expect to be called at JVM init time");
570 assert(ranges != NULL, "MemRegion array NULL");
571 assert(count != 0, "No MemRegions provided");
572 MutexLockerEx x(Heap_lock);
573
574 MemRegion reserved = _hrm.reserved();
575 HeapWord* prev_last_addr = NULL;
576 HeapRegion* prev_last_region = NULL;
577
578 // Temporarily disable pretouching of heap pages. This interface is used
579 // when mmap'ing archived heap data in, so pre-touching is wasted.
580 FlagSetting fs(AlwaysPreTouch, false);
581
582 // Enable archive object checking used by G1MarkSweep. We have to let it know
583 // about each archive range, so that objects in those ranges aren't marked.
584 G1ArchiveAllocator::enable_archive_object_check();
585
586 // For each specified MemRegion range, allocate the corresponding G1
587 // regions and mark them as archive regions. We expect the ranges
588 // in ascending starting address order, without overlap.
589 for (size_t i = 0; i < count; i++) {
590 MemRegion curr_range = ranges[i];
591 HeapWord* start_address = curr_range.start();
592 size_t word_size = curr_range.word_size();
593 HeapWord* last_address = curr_range.last();
594 size_t commits = 0;
595
596 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
597 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
598 p2i(start_address), p2i(last_address));
599 guarantee(start_address > prev_last_addr,
600 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
601 p2i(start_address), p2i(prev_last_addr));
602 prev_last_addr = last_address;
603
604 // Check for ranges that start in the same G1 region in which the previous
605 // range ended, and adjust the start address so we don't try to allocate
606 // the same region again. If the current range is entirely within that
607 // region, skip it, just adjusting the recorded top.
608 HeapRegion* start_region = _hrm.addr_to_region(start_address);
609 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
610 start_address = start_region->end();
611 if (start_address > last_address) {
612 increase_used(word_size * HeapWordSize);
613 start_region->set_top(last_address + 1);
614 continue;
615 }
616 start_region->set_top(start_address);
617 curr_range = MemRegion(start_address, last_address + 1);
618 start_region = _hrm.addr_to_region(start_address);
619 }
620
621 // Perform the actual region allocation, exiting if it fails.
622 // Then note how much new space we have allocated.
623 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
624 return false;
625 }
626 increase_used(word_size * HeapWordSize);
627 if (commits != 0) {
628 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
629 HeapRegion::GrainWords * HeapWordSize * commits);
630
631 }
632
633 // Mark each G1 region touched by the range as archive, add it to
634 // the old set, and set top.
635 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
636 HeapRegion* last_region = _hrm.addr_to_region(last_address);
637 prev_last_region = last_region;
638
639 while (curr_region != NULL) {
640 assert(curr_region->is_empty() && !curr_region->is_pinned(),
641 "Region already in use (index %u)", curr_region->hrm_index());
642 if (open) {
643 curr_region->set_open_archive();
644 } else {
645 curr_region->set_closed_archive();
646 }
647 _hr_printer.alloc(curr_region);
648 _archive_set.add(curr_region);
649 HeapWord* top;
650 HeapRegion* next_region;
651 if (curr_region != last_region) {
652 top = curr_region->end();
653 next_region = _hrm.next_region_in_heap(curr_region);
654 } else {
655 top = last_address + 1;
656 next_region = NULL;
657 }
658 curr_region->set_top(top);
659 curr_region->set_first_dead(top);
660 curr_region->set_end_of_live(top);
661 curr_region = next_region;
662 }
663
664 // Notify mark-sweep of the archive
665 G1ArchiveAllocator::set_range_archive(curr_range, open);
666 }
667 return true;
668 }
669
670 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
671 assert(!is_init_completed(), "Expect to be called at JVM init time");
672 assert(ranges != NULL, "MemRegion array NULL");
673 assert(count != 0, "No MemRegions provided");
674 MemRegion reserved = _hrm.reserved();
675 HeapWord *prev_last_addr = NULL;
676 HeapRegion* prev_last_region = NULL;
677
678 // For each MemRegion, create filler objects, if needed, in the G1 regions
679 // that contain the address range. The address range actually within the
680 // MemRegion will not be modified. That is assumed to have been initialized
681 // elsewhere, probably via an mmap of archived heap data.
682 MutexLockerEx x(Heap_lock);
683 for (size_t i = 0; i < count; i++) {
684 HeapWord* start_address = ranges[i].start();
685 HeapWord* last_address = ranges[i].last();
686
687 assert(reserved.contains(start_address) && reserved.contains(last_address),
688 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
689 p2i(start_address), p2i(last_address));
690 assert(start_address > prev_last_addr,
691 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
692 p2i(start_address), p2i(prev_last_addr));
693
694 HeapRegion* start_region = _hrm.addr_to_region(start_address);
695 HeapRegion* last_region = _hrm.addr_to_region(last_address);
696 HeapWord* bottom_address = start_region->bottom();
697
698 // Check for a range beginning in the same region in which the
699 // previous one ended.
700 if (start_region == prev_last_region) {
701 bottom_address = prev_last_addr + 1;
702 }
703
704 // Verify that the regions were all marked as archive regions by
705 // alloc_archive_regions.
706 HeapRegion* curr_region = start_region;
707 while (curr_region != NULL) {
708 guarantee(curr_region->is_archive(),
709 "Expected archive region at index %u", curr_region->hrm_index());
710 if (curr_region != last_region) {
711 curr_region = _hrm.next_region_in_heap(curr_region);
712 } else {
713 curr_region = NULL;
714 }
715 }
716
717 prev_last_addr = last_address;
718 prev_last_region = last_region;
719
720 // Fill the memory below the allocated range with dummy object(s),
721 // if the region bottom does not match the range start, or if the previous
722 // range ended within the same G1 region, and there is a gap.
723 if (start_address != bottom_address) {
724 size_t fill_size = pointer_delta(start_address, bottom_address);
725 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
726 increase_used(fill_size * HeapWordSize);
727 }
728 }
729 }
730
731 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
732 size_t desired_word_size,
733 size_t* actual_word_size) {
734 assert_heap_not_locked_and_not_at_safepoint();
735 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
736 "be called for humongous allocation requests");
737
738 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
739
740 if (result == NULL) {
741 *actual_word_size = desired_word_size;
742 result = attempt_allocation_slow(desired_word_size);
743 }
744
745 assert_heap_not_locked();
746 if (result != NULL) {
747 assert(*actual_word_size != 0, "Actual size must have been set here");
748 dirty_young_block(result, *actual_word_size);
749 } else {
750 *actual_word_size = 0;
751 }
752
753 return result;
754 }
755
756 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
757 assert(!is_init_completed(), "Expect to be called at JVM init time");
758 assert(ranges != NULL, "MemRegion array NULL");
759 assert(count != 0, "No MemRegions provided");
760 MemRegion reserved = _hrm.reserved();
761 HeapWord* prev_last_addr = NULL;
762 HeapRegion* prev_last_region = NULL;
763 size_t size_used = 0;
764 size_t uncommitted_regions = 0;
765
766 // For each Memregion, free the G1 regions that constitute it, and
767 // notify mark-sweep that the range is no longer to be considered 'archive.'
768 MutexLockerEx x(Heap_lock);
769 for (size_t i = 0; i < count; i++) {
770 HeapWord* start_address = ranges[i].start();
771 HeapWord* last_address = ranges[i].last();
772
773 assert(reserved.contains(start_address) && reserved.contains(last_address),
774 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
775 p2i(start_address), p2i(last_address));
776 assert(start_address > prev_last_addr,
777 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
778 p2i(start_address), p2i(prev_last_addr));
779 size_used += ranges[i].byte_size();
780 prev_last_addr = last_address;
781
782 HeapRegion* start_region = _hrm.addr_to_region(start_address);
783 HeapRegion* last_region = _hrm.addr_to_region(last_address);
784
785 // Check for ranges that start in the same G1 region in which the previous
786 // range ended, and adjust the start address so we don't try to free
787 // the same region again. If the current range is entirely within that
788 // region, skip it.
789 if (start_region == prev_last_region) {
790 start_address = start_region->end();
791 if (start_address > last_address) {
792 continue;
793 }
794 start_region = _hrm.addr_to_region(start_address);
795 }
796 prev_last_region = last_region;
797
798 // After verifying that each region was marked as an archive region by
799 // alloc_archive_regions, set it free and empty and uncommit it.
800 HeapRegion* curr_region = start_region;
801 while (curr_region != NULL) {
802 guarantee(curr_region->is_archive(),
803 "Expected archive region at index %u", curr_region->hrm_index());
804 uint curr_index = curr_region->hrm_index();
805 _archive_set.remove(curr_region);
806 curr_region->set_free();
807 curr_region->set_top(curr_region->bottom());
808 if (curr_region != last_region) {
809 curr_region = _hrm.next_region_in_heap(curr_region);
810 } else {
811 curr_region = NULL;
812 }
813 _hrm.shrink_at(curr_index, 1);
814 uncommitted_regions++;
815 }
816
817 // Notify mark-sweep that this is no longer an archive range.
818 G1ArchiveAllocator::set_range_archive(ranges[i], false);
819 }
820
821 if (uncommitted_regions != 0) {
822 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
823 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
824 }
825 decrease_used(size_used);
826 }
827
828 oop G1CollectedHeap::materialize_archived_object(oop obj) {
829 assert(obj != NULL, "archived obj is NULL");
830 assert(MetaspaceShared::is_archive_object(obj), "must be archived object");
831
832 // Loading an archived object makes it strongly reachable. If it is
833 // loaded during concurrent marking, it must be enqueued to the SATB
834 // queue, shading the previously white object gray.
835 G1BarrierSet::enqueue(obj);
836
837 return obj;
838 }
839
840 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
841 ResourceMark rm; // For retrieving the thread names in log messages.
842
843 // The structure of this method has a lot of similarities to
844 // attempt_allocation_slow(). The reason these two were not merged
845 // into a single one is that such a method would require several "if
846 // allocation is not humongous do this, otherwise do that"
847 // conditional paths which would obscure its flow. In fact, an early
848 // version of this code did use a unified method which was harder to
849 // follow and, as a result, it had subtle bugs that were hard to
850 // track down. So keeping these two methods separate allows each to
851 // be more readable. It will be good to keep these two in sync as
852 // much as possible.
853
854 assert_heap_not_locked_and_not_at_safepoint();
855 assert(is_humongous(word_size), "attempt_allocation_humongous() "
856 "should only be called for humongous allocations");
857
858 // Humongous objects can exhaust the heap quickly, so we should check if we
859 // need to start a marking cycle at each humongous object allocation. We do
860 // the check before we do the actual allocation. The reason for doing it
861 // before the allocation is that we avoid having to keep track of the newly
862 // allocated memory while we do a GC.
863 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
864 word_size)) {
865 collect(GCCause::_g1_humongous_allocation);
866 }
867
868 // We will loop until a) we manage to successfully perform the
869 // allocation or b) we successfully schedule a collection which
870 // fails to perform the allocation. b) is the only case when we'll
871 // return NULL.
872 HeapWord* result = NULL;
873 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
874 bool should_try_gc;
875 uint gc_count_before;
876
877
878 {
879 MutexLockerEx x(Heap_lock);
880
881 // Given that humongous objects are not allocated in young
882 // regions, we'll first try to do the allocation without doing a
883 // collection hoping that there's enough space in the heap.
884 result = humongous_obj_allocate(word_size);
885 if (result != NULL) {
886 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
887 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
888 return result;
889 }
890
891 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
892 // the GCLocker initiated GC has been performed and then retry. This includes
893 // the case when the GC Locker is not active but has not been performed.
894 should_try_gc = !GCLocker::needs_gc();
895 // Read the GC count while still holding the Heap_lock.
896 gc_count_before = total_collections();
897 }
898
899 if (should_try_gc) {
900 bool succeeded;
901 result = do_collection_pause(word_size, gc_count_before, &succeeded,
902 GCCause::_g1_humongous_allocation);
903 if (result != NULL) {
904 assert(succeeded, "only way to get back a non-NULL result");
905 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
906 Thread::current()->name(), p2i(result));
907 return result;
908 }
909
910 if (succeeded) {
911 // We successfully scheduled a collection which failed to allocate. No
912 // point in trying to allocate further. We'll just return NULL.
913 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
914 SIZE_FORMAT " words", Thread::current()->name(), word_size);
915 return NULL;
916 }
917 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
918 Thread::current()->name(), word_size);
919 } else {
920 // Failed to schedule a collection.
921 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
922 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
923 SIZE_FORMAT " words", Thread::current()->name(), word_size);
924 return NULL;
925 }
926 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
927 // The GCLocker is either active or the GCLocker initiated
928 // GC has not yet been performed. Stall until it is and
929 // then retry the allocation.
930 GCLocker::stall_until_clear();
931 gclocker_retry_count += 1;
932 }
933
934
935 // We can reach here if we were unsuccessful in scheduling a
936 // collection (because another thread beat us to it) or if we were
937 // stalled due to the GC locker. In either can we should retry the
938 // allocation attempt in case another thread successfully
939 // performed a collection and reclaimed enough space.
940 // Humongous object allocation always needs a lock, so we wait for the retry
941 // in the next iteration of the loop, unlike for the regular iteration case.
942 // Give a warning if we seem to be looping forever.
943
944 if ((QueuedAllocationWarningCount > 0) &&
945 (try_count % QueuedAllocationWarningCount == 0)) {
946 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
947 Thread::current()->name(), try_count, word_size);
948 }
949 }
950
951 ShouldNotReachHere();
952 return NULL;
953 }
954
955 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
956 bool expect_null_mutator_alloc_region) {
957 assert_at_safepoint_on_vm_thread();
958 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
959 "the current alloc region was unexpectedly found to be non-NULL");
960
961 if (!is_humongous(word_size)) {
962 return _allocator->attempt_allocation_locked(word_size);
963 } else {
964 HeapWord* result = humongous_obj_allocate(word_size);
965 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
966 collector_state()->set_initiate_conc_mark_if_possible(true);
967 }
968 return result;
969 }
970
971 ShouldNotReachHere();
972 }
973
974 class PostCompactionPrinterClosure: public HeapRegionClosure {
975 private:
976 G1HRPrinter* _hr_printer;
977 public:
978 bool do_heap_region(HeapRegion* hr) {
979 assert(!hr->is_young(), "not expecting to find young regions");
980 _hr_printer->post_compaction(hr);
981 return false;
982 }
983
984 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
985 : _hr_printer(hr_printer) { }
986 };
987
988 void G1CollectedHeap::print_hrm_post_compaction() {
989 if (_hr_printer.is_active()) {
990 PostCompactionPrinterClosure cl(hr_printer());
991 heap_region_iterate(&cl);
992 }
993 }
994
995 void G1CollectedHeap::abort_concurrent_cycle() {
996 // If we start the compaction before the CM threads finish
997 // scanning the root regions we might trip them over as we'll
998 // be moving objects / updating references. So let's wait until
999 // they are done. By telling them to abort, they should complete
1000 // early.
1001 _cm->root_regions()->abort();
1002 _cm->root_regions()->wait_until_scan_finished();
1003
1004 // Disable discovery and empty the discovered lists
1005 // for the CM ref processor.
1006 _ref_processor_cm->disable_discovery();
1007 _ref_processor_cm->abandon_partial_discovery();
1008 _ref_processor_cm->verify_no_references_recorded();
1009
1010 // Abandon current iterations of concurrent marking and concurrent
1011 // refinement, if any are in progress.
1012 concurrent_mark()->concurrent_cycle_abort();
1013 }
1014
1015 void G1CollectedHeap::prepare_heap_for_full_collection() {
1016 // Make sure we'll choose a new allocation region afterwards.
1017 _allocator->release_mutator_alloc_region();
1018 _allocator->abandon_gc_alloc_regions();
1019 g1_rem_set()->cleanupHRRS();
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
1030 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1031 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1032 assert(used() == recalculate_used(), "Should be equal");
1033 _verifier->verify_region_sets_optional();
1034 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1035 _verifier->check_bitmaps("Full GC Start");
1036 }
1037
1038 void G1CollectedHeap::prepare_heap_for_mutators() {
1039 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1040 ClassLoaderDataGraph::purge();
1041 MetaspaceUtils::verify_metrics();
1042
1043 // Prepare heap for normal collections.
1044 assert(num_free_regions() == 0, "we should not have added any free regions");
1045 rebuild_region_sets(false /* free_list_only */);
1046 abort_refinement();
1047 resize_if_necessary_after_full_collection();
1048
1049 // Rebuild the strong code root lists for each region
1050 rebuild_strong_code_roots();
1051
1052 // Start a new incremental collection set for the next pause
1053 start_new_collection_set();
1054
1055 _allocator->init_mutator_alloc_region();
1056
1057 // Post collection state updates.
1058 MetaspaceGC::compute_new_size();
1059 }
1060
1061 void G1CollectedHeap::abort_refinement() {
1062 if (_hot_card_cache->use_cache()) {
1063 _hot_card_cache->reset_hot_cache();
1064 }
1065
1066 // Discard all remembered set updates.
1067 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1068 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1069 }
1070
1071 void G1CollectedHeap::verify_after_full_collection() {
1072 _hrm.verify_optional();
1073 _verifier->verify_region_sets_optional();
1074 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1075 // Clear the previous marking bitmap, if needed for bitmap verification.
1076 // Note we cannot do this when we clear the next marking bitmap in
1077 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1078 // objects marked during a full GC against the previous bitmap.
1079 // But we need to clear it before calling check_bitmaps below since
1080 // the full GC has compacted objects and updated TAMS but not updated
1081 // the prev bitmap.
1082 if (G1VerifyBitmaps) {
1083 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1084 _cm->clear_prev_bitmap(workers());
1085 }
1086 // This call implicitly verifies that the next bitmap is clear after Full GC.
1087 _verifier->check_bitmaps("Full GC End");
1088
1089 // At this point there should be no regions in the
1090 // entire heap tagged as young.
1091 assert(check_young_list_empty(), "young list should be empty at this point");
1092
1093 // Note: since we've just done a full GC, concurrent
1094 // marking is no longer active. Therefore we need not
1095 // re-enable reference discovery for the CM ref processor.
1096 // That will be done at the start of the next marking cycle.
1097 // We also know that the STW processor should no longer
1098 // discover any new references.
1099 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1100 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1101 _ref_processor_stw->verify_no_references_recorded();
1102 _ref_processor_cm->verify_no_references_recorded();
1103 }
1104
1105 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1106 // Post collection logging.
1107 // We should do this after we potentially resize the heap so
1108 // that all the COMMIT / UNCOMMIT events are generated before
1109 // the compaction events.
1110 print_hrm_post_compaction();
1111 heap_transition->print();
1112 print_heap_after_gc();
1113 print_heap_regions();
1114 #ifdef TRACESPINNING
1115 ParallelTaskTerminator::print_termination_counts();
1116 #endif
1117 }
1118
1119 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1120 bool clear_all_soft_refs) {
1121 assert_at_safepoint_on_vm_thread();
1122
1123 if (GCLocker::check_active_before_gc()) {
1124 // Full GC was not completed.
1125 return false;
1126 }
1127
1128 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1129 soft_ref_policy()->should_clear_all_soft_refs();
1130
1131 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1132 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1133
1134 collector.prepare_collection();
1135 collector.collect();
1136 collector.complete_collection();
1137
1138 // Full collection was successfully completed.
1139 return true;
1140 }
1141
1142 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1143 // Currently, there is no facility in the do_full_collection(bool) API to notify
1144 // the caller that the collection did not succeed (e.g., because it was locked
1145 // out by the GC locker). So, right now, we'll ignore the return value.
1146 bool dummy = do_full_collection(true, /* explicit_gc */
1147 clear_all_soft_refs);
1148 }
1149
1150 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1151 // Capacity, free and used after the GC counted as full regions to
1152 // include the waste in the following calculations.
1153 const size_t capacity_after_gc = capacity();
1154 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1155
1156 // This is enforced in arguments.cpp.
1157 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1158 "otherwise the code below doesn't make sense");
1159
1160 // We don't have floating point command-line arguments
1161 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1162 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1163 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1164 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1165
1166 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1167 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1168
1169 // We have to be careful here as these two calculations can overflow
1170 // 32-bit size_t's.
1171 double used_after_gc_d = (double) used_after_gc;
1172 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1173 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1174
1175 // Let's make sure that they are both under the max heap size, which
1176 // by default will make them fit into a size_t.
1177 double desired_capacity_upper_bound = (double) max_heap_size;
1178 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1179 desired_capacity_upper_bound);
1180 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1181 desired_capacity_upper_bound);
1182
1183 // We can now safely turn them into size_t's.
1184 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1185 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1186
1187 // This assert only makes sense here, before we adjust them
1188 // with respect to the min and max heap size.
1189 assert(minimum_desired_capacity <= maximum_desired_capacity,
1190 "minimum_desired_capacity = " SIZE_FORMAT ", "
1191 "maximum_desired_capacity = " SIZE_FORMAT,
1192 minimum_desired_capacity, maximum_desired_capacity);
1193
1194 // Should not be greater than the heap max size. No need to adjust
1195 // it with respect to the heap min size as it's a lower bound (i.e.,
1196 // we'll try to make the capacity larger than it, not smaller).
1197 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1198 // Should not be less than the heap min size. No need to adjust it
1199 // with respect to the heap max size as it's an upper bound (i.e.,
1200 // we'll try to make the capacity smaller than it, not greater).
1201 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1202
1203 if (capacity_after_gc < minimum_desired_capacity) {
1204 // Don't expand unless it's significant
1205 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1206
1207 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1208 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1209 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1210 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1211
1212 expand(expand_bytes, _workers);
1213
1214 // No expansion, now see if we want to shrink
1215 } else if (capacity_after_gc > maximum_desired_capacity) {
1216 // Capacity too large, compute shrinking size
1217 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1218
1219 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1220 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1221 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1222 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1223
1224 shrink(shrink_bytes);
1225 }
1226 }
1227
1228 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1229 bool do_gc,
1230 bool clear_all_soft_refs,
1231 bool expect_null_mutator_alloc_region,
1232 bool* gc_succeeded) {
1233 *gc_succeeded = true;
1234 // Let's attempt the allocation first.
1235 HeapWord* result =
1236 attempt_allocation_at_safepoint(word_size,
1237 expect_null_mutator_alloc_region);
1238 if (result != NULL) {
1239 return result;
1240 }
1241
1242 // In a G1 heap, we're supposed to keep allocation from failing by
1243 // incremental pauses. Therefore, at least for now, we'll favor
1244 // expansion over collection. (This might change in the future if we can
1245 // do something smarter than full collection to satisfy a failed alloc.)
1246 result = expand_and_allocate(word_size);
1247 if (result != NULL) {
1248 return result;
1249 }
1250
1251 if (do_gc) {
1252 // Expansion didn't work, we'll try to do a Full GC.
1253 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1254 clear_all_soft_refs);
1255 }
1256
1257 return NULL;
1258 }
1259
1260 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1261 bool* succeeded) {
1262 assert_at_safepoint_on_vm_thread();
1263
1264 // Attempts to allocate followed by Full GC.
1265 HeapWord* result =
1266 satisfy_failed_allocation_helper(word_size,
1267 true, /* do_gc */
1268 false, /* clear_all_soft_refs */
1269 false, /* expect_null_mutator_alloc_region */
1270 succeeded);
1271
1272 if (result != NULL || !*succeeded) {
1273 return result;
1274 }
1275
1276 // Attempts to allocate followed by Full GC that will collect all soft references.
1277 result = satisfy_failed_allocation_helper(word_size,
1278 true, /* do_gc */
1279 true, /* clear_all_soft_refs */
1280 true, /* expect_null_mutator_alloc_region */
1281 succeeded);
1282
1283 if (result != NULL || !*succeeded) {
1284 return result;
1285 }
1286
1287 // Attempts to allocate, no GC
1288 result = satisfy_failed_allocation_helper(word_size,
1289 false, /* do_gc */
1290 false, /* clear_all_soft_refs */
1291 true, /* expect_null_mutator_alloc_region */
1292 succeeded);
1293
1294 if (result != NULL) {
1295 return result;
1296 }
1297
1298 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1299 "Flag should have been handled and cleared prior to this point");
1300
1301 // What else? We might try synchronous finalization later. If the total
1302 // space available is large enough for the allocation, then a more
1303 // complete compaction phase than we've tried so far might be
1304 // appropriate.
1305 return NULL;
1306 }
1307
1308 // Attempting to expand the heap sufficiently
1309 // to support an allocation of the given "word_size". If
1310 // successful, perform the allocation and return the address of the
1311 // allocated block, or else "NULL".
1312
1313 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1314 assert_at_safepoint_on_vm_thread();
1315
1316 _verifier->verify_region_sets_optional();
1317
1318 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1319 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1320 word_size * HeapWordSize);
1321
1322
1323 if (expand(expand_bytes, _workers)) {
1324 _hrm.verify_optional();
1325 _verifier->verify_region_sets_optional();
1326 return attempt_allocation_at_safepoint(word_size,
1327 false /* expect_null_mutator_alloc_region */);
1328 }
1329 return NULL;
1330 }
1331
1332 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1333 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1334 aligned_expand_bytes = align_up(aligned_expand_bytes,
1335 HeapRegion::GrainBytes);
1336
1337 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1338 expand_bytes, aligned_expand_bytes);
1339
1340 if (is_maximal_no_gc()) {
1341 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1342 return false;
1343 }
1344
1345 double expand_heap_start_time_sec = os::elapsedTime();
1346 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1347 assert(regions_to_expand > 0, "Must expand by at least one region");
1348
1349 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1350 if (expand_time_ms != NULL) {
1351 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1352 }
1353
1354 if (expanded_by > 0) {
1355 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1356 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1357 g1_policy()->record_new_heap_size(num_regions());
1358 } else {
1359 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1360
1361 // The expansion of the virtual storage space was unsuccessful.
1362 // Let's see if it was because we ran out of swap.
1363 if (G1ExitOnExpansionFailure &&
1364 _hrm.available() >= regions_to_expand) {
1365 // We had head room...
1366 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1367 }
1368 }
1369 return regions_to_expand > 0;
1370 }
1371
1372 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1373 size_t aligned_shrink_bytes =
1374 ReservedSpace::page_align_size_down(shrink_bytes);
1375 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1376 HeapRegion::GrainBytes);
1377 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1378
1379 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1380 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1381
1382
1383 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",
1384 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1385 if (num_regions_removed > 0) {
1386 g1_policy()->record_new_heap_size(num_regions());
1387 } else {
1388 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1389 }
1390 }
1391
1392 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1393 _verifier->verify_region_sets_optional();
1394
1395 // We should only reach here at the end of a Full GC which means we
1396 // should not not be holding to any GC alloc regions. The method
1397 // below will make sure of that and do any remaining clean up.
1398 _allocator->abandon_gc_alloc_regions();
1399
1400 // Instead of tearing down / rebuilding the free lists here, we
1401 // could instead use the remove_all_pending() method on free_list to
1402 // remove only the ones that we need to remove.
1403 tear_down_region_sets(true /* free_list_only */);
1404 shrink_helper(shrink_bytes);
1405 rebuild_region_sets(true /* free_list_only */);
1406
1407 _hrm.verify_optional();
1408 _verifier->verify_region_sets_optional();
1409 }
1410
1411 class OldRegionSetChecker : public HeapRegionSetChecker {
1412 public:
1413 void check_mt_safety() {
1414 // Master Old Set MT safety protocol:
1415 // (a) If we're at a safepoint, operations on the master old set
1416 // should be invoked:
1417 // - by the VM thread (which will serialize them), or
1418 // - by the GC workers while holding the FreeList_lock, if we're
1419 // at a safepoint for an evacuation pause (this lock is taken
1420 // anyway when an GC alloc region is retired so that a new one
1421 // is allocated from the free list), or
1422 // - by the GC workers while holding the OldSets_lock, if we're at a
1423 // safepoint for a cleanup pause.
1424 // (b) If we're not at a safepoint, operations on the master old set
1425 // should be invoked while holding the Heap_lock.
1426
1427 if (SafepointSynchronize::is_at_safepoint()) {
1428 guarantee(Thread::current()->is_VM_thread() ||
1429 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1430 "master old set MT safety protocol at a safepoint");
1431 } else {
1432 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1433 }
1434 }
1435 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1436 const char* get_description() { return "Old Regions"; }
1437 };
1438
1439 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1440 public:
1441 void check_mt_safety() {
1442 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1443 "May only change archive regions during initialization or safepoint.");
1444 }
1445 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1446 const char* get_description() { return "Archive Regions"; }
1447 };
1448
1449 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1450 public:
1451 void check_mt_safety() {
1452 // Humongous Set MT safety protocol:
1453 // (a) If we're at a safepoint, operations on the master humongous
1454 // set should be invoked by either the VM thread (which will
1455 // serialize them) or by the GC workers while holding the
1456 // OldSets_lock.
1457 // (b) If we're not at a safepoint, operations on the master
1458 // humongous set should be invoked while holding the Heap_lock.
1459
1460 if (SafepointSynchronize::is_at_safepoint()) {
1461 guarantee(Thread::current()->is_VM_thread() ||
1462 OldSets_lock->owned_by_self(),
1463 "master humongous set MT safety protocol at a safepoint");
1464 } else {
1465 guarantee(Heap_lock->owned_by_self(),
1466 "master humongous set MT safety protocol outside a safepoint");
1467 }
1468 }
1469 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1470 const char* get_description() { return "Humongous Regions"; }
1471 };
1472
1473 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1474 CollectedHeap(),
1475 _young_gen_sampling_thread(NULL),
1476 _workers(NULL),
1477 _collector_policy(collector_policy),
1478 _card_table(NULL),
1479 _soft_ref_policy(),
1480 _old_set("Old Region Set", new OldRegionSetChecker()),
1481 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1482 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1483 _bot(NULL),
1484 _listener(),
1485 _hrm(),
1486 _allocator(NULL),
1487 _verifier(NULL),
1488 _summary_bytes_used(0),
1489 _archive_allocator(NULL),
1490 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1491 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1492 _expand_heap_after_alloc_failure(true),
1493 _g1mm(NULL),
1494 _humongous_reclaim_candidates(),
1495 _has_humongous_reclaim_candidates(false),
1496 _hr_printer(),
1497 _collector_state(),
1498 _old_marking_cycles_started(0),
1499 _old_marking_cycles_completed(0),
1500 _eden(),
1501 _survivor(),
1502 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1503 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1504 _g1_policy(new G1Policy(_gc_timer_stw)),
1505 _heap_sizing_policy(NULL),
1506 _collection_set(this, _g1_policy),
1507 _hot_card_cache(NULL),
1508 _g1_rem_set(NULL),
1509 _dirty_card_queue_set(false),
1510 _cm(NULL),
1511 _cm_thread(NULL),
1512 _cr(NULL),
1513 _task_queues(NULL),
1514 _evacuation_failed(false),
1515 _evacuation_failed_info_array(NULL),
1516 _preserved_marks_set(true /* in_c_heap */),
1517 #ifndef PRODUCT
1518 _evacuation_failure_alot_for_current_gc(false),
1519 _evacuation_failure_alot_gc_number(0),
1520 _evacuation_failure_alot_count(0),
1521 #endif
1522 _ref_processor_stw(NULL),
1523 _is_alive_closure_stw(this),
1524 _is_subject_to_discovery_stw(this),
1525 _ref_processor_cm(NULL),
1526 _is_alive_closure_cm(this),
1527 _is_subject_to_discovery_cm(this),
1528 _in_cset_fast_test() {
1529
1530 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1531 true /* are_GC_task_threads */,
1532 false /* are_ConcurrentGC_threads */);
1533 _workers->initialize_workers();
1534 _verifier = new G1HeapVerifier(this);
1535
1536 _allocator = new G1Allocator(this);
1537
1538 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1539
1540 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1541
1542 // Override the default _filler_array_max_size so that no humongous filler
1543 // objects are created.
1544 _filler_array_max_size = _humongous_object_threshold_in_words;
1545
1546 uint n_queues = ParallelGCThreads;
1547 _task_queues = new RefToScanQueueSet(n_queues);
1548
1549 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1550
1551 for (uint i = 0; i < n_queues; i++) {
1552 RefToScanQueue* q = new RefToScanQueue();
1553 q->initialize();
1554 _task_queues->register_queue(i, q);
1555 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1556 }
1557
1558 // Initialize the G1EvacuationFailureALot counters and flags.
1559 NOT_PRODUCT(reset_evacuation_should_fail();)
1560
1561 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1562 }
1563
1564 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1565 size_t size,
1566 size_t translation_factor) {
1567 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1568 // Allocate a new reserved space, preferring to use large pages.
1569 ReservedSpace rs(size, preferred_page_size);
1570 G1RegionToSpaceMapper* result =
1571 G1RegionToSpaceMapper::create_mapper(rs,
1572 size,
1573 rs.alignment(),
1574 HeapRegion::GrainBytes,
1575 translation_factor,
1576 mtGC);
1577
1578 os::trace_page_sizes_for_requested_size(description,
1579 size,
1580 preferred_page_size,
1581 rs.alignment(),
1582 rs.base(),
1583 rs.size());
1584
1585 return result;
1586 }
1587
1588 jint G1CollectedHeap::initialize_concurrent_refinement() {
1589 jint ecode = JNI_OK;
1590 _cr = G1ConcurrentRefine::create(&ecode);
1591 return ecode;
1592 }
1593
1594 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1595 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1596 if (_young_gen_sampling_thread->osthread() == NULL) {
1597 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1598 return JNI_ENOMEM;
1599 }
1600 return JNI_OK;
1601 }
1602
1603 jint G1CollectedHeap::initialize() {
1604 os::enable_vtime();
1605
1606 // Necessary to satisfy locking discipline assertions.
1607
1608 MutexLocker x(Heap_lock);
1609
1610 // While there are no constraints in the GC code that HeapWordSize
1611 // be any particular value, there are multiple other areas in the
1612 // system which believe this to be true (e.g. oop->object_size in some
1613 // cases incorrectly returns the size in wordSize units rather than
1614 // HeapWordSize).
1615 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1616
1617 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1618 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1619 size_t heap_alignment = collector_policy()->heap_alignment();
1620
1621 // Ensure that the sizes are properly aligned.
1622 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1623 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1624 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1625
1626 // Reserve the maximum.
1627
1628 // When compressed oops are enabled, the preferred heap base
1629 // is calculated by subtracting the requested size from the
1630 // 32Gb boundary and using the result as the base address for
1631 // heap reservation. If the requested size is not aligned to
1632 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1633 // into the ReservedHeapSpace constructor) then the actual
1634 // base of the reserved heap may end up differing from the
1635 // address that was requested (i.e. the preferred heap base).
1636 // If this happens then we could end up using a non-optimal
1637 // compressed oops mode.
1638
1639 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1640 heap_alignment);
1641
1642 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1643
1644 // Create the barrier set for the entire reserved region.
1645 G1CardTable* ct = new G1CardTable(reserved_region());
1646 ct->initialize();
1647 G1BarrierSet* bs = new G1BarrierSet(ct);
1648 bs->initialize();
1649 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1650 BarrierSet::set_barrier_set(bs);
1651 _card_table = ct;
1652
1653 // Create the hot card cache.
1654 _hot_card_cache = new G1HotCardCache(this);
1655
1656 // Carve out the G1 part of the heap.
1657 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1658 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1659 G1RegionToSpaceMapper* heap_storage =
1660 G1RegionToSpaceMapper::create_mapper(g1_rs,
1661 g1_rs.size(),
1662 page_size,
1663 HeapRegion::GrainBytes,
1664 1,
1665 mtJavaHeap);
1666 os::trace_page_sizes("Heap",
1667 collector_policy()->min_heap_byte_size(),
1668 max_byte_size,
1669 page_size,
1670 heap_rs.base(),
1671 heap_rs.size());
1672 heap_storage->set_mapping_changed_listener(&_listener);
1673
1674 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1675 G1RegionToSpaceMapper* bot_storage =
1676 create_aux_memory_mapper("Block Offset Table",
1677 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1678 G1BlockOffsetTable::heap_map_factor());
1679
1680 G1RegionToSpaceMapper* cardtable_storage =
1681 create_aux_memory_mapper("Card Table",
1682 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1683 G1CardTable::heap_map_factor());
1684
1685 G1RegionToSpaceMapper* card_counts_storage =
1686 create_aux_memory_mapper("Card Counts Table",
1687 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1688 G1CardCounts::heap_map_factor());
1689
1690 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1691 G1RegionToSpaceMapper* prev_bitmap_storage =
1692 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1693 G1RegionToSpaceMapper* next_bitmap_storage =
1694 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1695
1696 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1697 _card_table->initialize(cardtable_storage);
1698 // Do later initialization work for concurrent refinement.
1699 _hot_card_cache->initialize(card_counts_storage);
1700
1701 // 6843694 - ensure that the maximum region index can fit
1702 // in the remembered set structures.
1703 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1704 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1705
1706 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1707 // start within the first card.
1708 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1709 // Also create a G1 rem set.
1710 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1711 _g1_rem_set->initialize(max_capacity(), max_regions());
1712
1713 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1714 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1715 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1716 "too many cards per region");
1717
1718 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1719
1720 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1721
1722 {
1723 HeapWord* start = _hrm.reserved().start();
1724 HeapWord* end = _hrm.reserved().end();
1725 size_t granularity = HeapRegion::GrainBytes;
1726
1727 _in_cset_fast_test.initialize(start, end, granularity);
1728 _humongous_reclaim_candidates.initialize(start, end, granularity);
1729 }
1730
1731 // Create the G1ConcurrentMark data structure and thread.
1732 // (Must do this late, so that "max_regions" is defined.)
1733 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1734 if (_cm == NULL || !_cm->completed_initialization()) {
1735 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1736 return JNI_ENOMEM;
1737 }
1738 _cm_thread = _cm->cm_thread();
1739
1740 // Now expand into the initial heap size.
1741 if (!expand(init_byte_size, _workers)) {
1742 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1743 return JNI_ENOMEM;
1744 }
1745
1746 // Perform any initialization actions delegated to the policy.
1747 g1_policy()->init(this, &_collection_set);
1748
1749 G1BarrierSet::satb_mark_queue_set().initialize(this,
1750 SATB_Q_CBL_mon,
1751 SATB_Q_FL_lock,
1752 G1SATBProcessCompletedThreshold,
1753 G1SATBBufferEnqueueingThresholdPercent,
1754 Shared_SATB_Q_lock);
1755
1756 jint ecode = initialize_concurrent_refinement();
1757 if (ecode != JNI_OK) {
1758 return ecode;
1759 }
1760
1761 ecode = initialize_young_gen_sampling_thread();
1762 if (ecode != JNI_OK) {
1763 return ecode;
1764 }
1765
1766 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1767 DirtyCardQ_FL_lock,
1768 (int)concurrent_refine()->yellow_zone(),
1769 (int)concurrent_refine()->red_zone(),
1770 Shared_DirtyCardQ_lock,
1771 NULL, // fl_owner
1772 true); // init_free_ids
1773
1774 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1775 DirtyCardQ_FL_lock,
1776 -1, // never trigger processing
1777 -1, // no limit on length
1778 Shared_DirtyCardQ_lock,
1779 &G1BarrierSet::dirty_card_queue_set());
1780
1781 // Here we allocate the dummy HeapRegion that is required by the
1782 // G1AllocRegion class.
1783 HeapRegion* dummy_region = _hrm.get_dummy_region();
1784
1785 // We'll re-use the same region whether the alloc region will
1786 // require BOT updates or not and, if it doesn't, then a non-young
1787 // region will complain that it cannot support allocations without
1788 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1789 dummy_region->set_eden();
1790 // Make sure it's full.
1791 dummy_region->set_top(dummy_region->end());
1792 G1AllocRegion::setup(this, dummy_region);
1793
1794 _allocator->init_mutator_alloc_region();
1795
1796 // Do create of the monitoring and management support so that
1797 // values in the heap have been properly initialized.
1798 _g1mm = new G1MonitoringSupport(this);
1799
1800 G1StringDedup::initialize();
1801
1802 _preserved_marks_set.init(ParallelGCThreads);
1803
1804 _collection_set.initialize(max_regions());
1805
1806 return JNI_OK;
1807 }
1808
1809 void G1CollectedHeap::stop() {
1810 // Stop all concurrent threads. We do this to make sure these threads
1811 // do not continue to execute and access resources (e.g. logging)
1812 // that are destroyed during shutdown.
1813 _cr->stop();
1814 _young_gen_sampling_thread->stop();
1815 _cm_thread->stop();
1816 if (G1StringDedup::is_enabled()) {
1817 G1StringDedup::stop();
1818 }
1819 }
1820
1821 void G1CollectedHeap::safepoint_synchronize_begin() {
1822 SuspendibleThreadSet::synchronize();
1823 }
1824
1825 void G1CollectedHeap::safepoint_synchronize_end() {
1826 SuspendibleThreadSet::desynchronize();
1827 }
1828
1829 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1830 return HeapRegion::max_region_size();
1831 }
1832
1833 void G1CollectedHeap::post_initialize() {
1834 CollectedHeap::post_initialize();
1835 ref_processing_init();
1836 }
1837
1838 void G1CollectedHeap::ref_processing_init() {
1839 // Reference processing in G1 currently works as follows:
1840 //
1841 // * There are two reference processor instances. One is
1842 // used to record and process discovered references
1843 // during concurrent marking; the other is used to
1844 // record and process references during STW pauses
1845 // (both full and incremental).
1846 // * Both ref processors need to 'span' the entire heap as
1847 // the regions in the collection set may be dotted around.
1848 //
1849 // * For the concurrent marking ref processor:
1850 // * Reference discovery is enabled at initial marking.
1851 // * Reference discovery is disabled and the discovered
1852 // references processed etc during remarking.
1853 // * Reference discovery is MT (see below).
1854 // * Reference discovery requires a barrier (see below).
1855 // * Reference processing may or may not be MT
1856 // (depending on the value of ParallelRefProcEnabled
1857 // and ParallelGCThreads).
1858 // * A full GC disables reference discovery by the CM
1859 // ref processor and abandons any entries on it's
1860 // discovered lists.
1861 //
1862 // * For the STW processor:
1863 // * Non MT discovery is enabled at the start of a full GC.
1864 // * Processing and enqueueing during a full GC is non-MT.
1865 // * During a full GC, references are processed after marking.
1866 //
1867 // * Discovery (may or may not be MT) is enabled at the start
1868 // of an incremental evacuation pause.
1869 // * References are processed near the end of a STW evacuation pause.
1870 // * For both types of GC:
1871 // * Discovery is atomic - i.e. not concurrent.
1872 // * Reference discovery will not need a barrier.
1873
1874 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1875
1876 // Concurrent Mark ref processor
1877 _ref_processor_cm =
1878 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1879 mt_processing, // mt processing
1880 ParallelGCThreads, // degree of mt processing
1881 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1882 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1883 false, // Reference discovery is not atomic
1884 &_is_alive_closure_cm, // is alive closure
1885 true); // allow changes to number of processing threads
1886
1887 // STW ref processor
1888 _ref_processor_stw =
1889 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1890 mt_processing, // mt processing
1891 ParallelGCThreads, // degree of mt processing
1892 (ParallelGCThreads > 1), // mt discovery
1893 ParallelGCThreads, // degree of mt discovery
1894 true, // Reference discovery is atomic
1895 &_is_alive_closure_stw, // is alive closure
1896 true); // allow changes to number of processing threads
1897 }
1898
1899 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1900 return _collector_policy;
1901 }
1902
1903 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1904 return &_soft_ref_policy;
1905 }
1906
1907 size_t G1CollectedHeap::capacity() const {
1908 return _hrm.length() * HeapRegion::GrainBytes;
1909 }
1910
1911 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1912 return _hrm.total_free_bytes();
1913 }
1914
1915 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1916 _hot_card_cache->drain(cl, worker_i);
1917 }
1918
1919 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1920 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1921 size_t n_completed_buffers = 0;
1922 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1923 n_completed_buffers++;
1924 }
1925 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1926 dcqs.clear_n_completed_buffers();
1927 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1928 }
1929
1930 // Computes the sum of the storage used by the various regions.
1931 size_t G1CollectedHeap::used() const {
1932 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1933 if (_archive_allocator != NULL) {
1934 result += _archive_allocator->used();
1935 }
1936 return result;
1937 }
1938
1939 size_t G1CollectedHeap::used_unlocked() const {
1940 return _summary_bytes_used;
1941 }
1942
1943 class SumUsedClosure: public HeapRegionClosure {
1944 size_t _used;
1945 public:
1946 SumUsedClosure() : _used(0) {}
1947 bool do_heap_region(HeapRegion* r) {
1948 _used += r->used();
1949 return false;
1950 }
1951 size_t result() { return _used; }
1952 };
1953
1954 size_t G1CollectedHeap::recalculate_used() const {
1955 SumUsedClosure blk;
1956 heap_region_iterate(&blk);
1957 return blk.result();
1958 }
1959
1960 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1961 switch (cause) {
1962 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1963 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1964 case GCCause::_wb_conc_mark: return true;
1965 default : return false;
1966 }
1967 }
1968
1969 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1970 switch (cause) {
1971 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1972 case GCCause::_g1_humongous_allocation: return true;
1973 default: return is_user_requested_concurrent_full_gc(cause);
1974 }
1975 }
1976
1977 #ifndef PRODUCT
1978 void G1CollectedHeap::allocate_dummy_regions() {
1979 // Let's fill up most of the region
1980 size_t word_size = HeapRegion::GrainWords - 1024;
1981 // And as a result the region we'll allocate will be humongous.
1982 guarantee(is_humongous(word_size), "sanity");
1983
1984 // _filler_array_max_size is set to humongous object threshold
1985 // but temporarily change it to use CollectedHeap::fill_with_object().
1986 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1987
1988 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1989 // Let's use the existing mechanism for the allocation
1990 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1991 if (dummy_obj != NULL) {
1992 MemRegion mr(dummy_obj, word_size);
1993 CollectedHeap::fill_with_object(mr);
1994 } else {
1995 // If we can't allocate once, we probably cannot allocate
1996 // again. Let's get out of the loop.
1997 break;
1998 }
1999 }
2000 }
2001 #endif // !PRODUCT
2002
2003 void G1CollectedHeap::increment_old_marking_cycles_started() {
2004 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2005 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2006 "Wrong marking cycle count (started: %d, completed: %d)",
2007 _old_marking_cycles_started, _old_marking_cycles_completed);
2008
2009 _old_marking_cycles_started++;
2010 }
2011
2012 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2013 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2014
2015 // We assume that if concurrent == true, then the caller is a
2016 // concurrent thread that was joined the Suspendible Thread
2017 // Set. If there's ever a cheap way to check this, we should add an
2018 // assert here.
2019
2020 // Given that this method is called at the end of a Full GC or of a
2021 // concurrent cycle, and those can be nested (i.e., a Full GC can
2022 // interrupt a concurrent cycle), the number of full collections
2023 // completed should be either one (in the case where there was no
2024 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2025 // behind the number of full collections started.
2026
2027 // This is the case for the inner caller, i.e. a Full GC.
2028 assert(concurrent ||
2029 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2030 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2031 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2032 "is inconsistent with _old_marking_cycles_completed = %u",
2033 _old_marking_cycles_started, _old_marking_cycles_completed);
2034
2035 // This is the case for the outer caller, i.e. the concurrent cycle.
2036 assert(!concurrent ||
2037 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2038 "for outer caller (concurrent cycle): "
2039 "_old_marking_cycles_started = %u "
2040 "is inconsistent with _old_marking_cycles_completed = %u",
2041 _old_marking_cycles_started, _old_marking_cycles_completed);
2042
2043 _old_marking_cycles_completed += 1;
2044
2045 // We need to clear the "in_progress" flag in the CM thread before
2046 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2047 // is set) so that if a waiter requests another System.gc() it doesn't
2048 // incorrectly see that a marking cycle is still in progress.
2049 if (concurrent) {
2050 _cm_thread->set_idle();
2051 }
2052
2053 // This notify_all() will ensure that a thread that called
2054 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2055 // and it's waiting for a full GC to finish will be woken up. It is
2056 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2057 FullGCCount_lock->notify_all();
2058 }
2059
2060 void G1CollectedHeap::collect(GCCause::Cause cause) {
2061 assert_heap_not_locked();
2062
2063 uint gc_count_before;
2064 uint old_marking_count_before;
2065 uint full_gc_count_before;
2066 bool retry_gc;
2067
2068 do {
2069 retry_gc = false;
2070
2071 {
2072 MutexLocker ml(Heap_lock);
2073
2074 // Read the GC count while holding the Heap_lock
2075 gc_count_before = total_collections();
2076 full_gc_count_before = total_full_collections();
2077 old_marking_count_before = _old_marking_cycles_started;
2078 }
2079
2080 if (should_do_concurrent_full_gc(cause)) {
2081 // Schedule an initial-mark evacuation pause that will start a
2082 // concurrent cycle. We're setting word_size to 0 which means that
2083 // we are not requesting a post-GC allocation.
2084 VM_G1CollectForAllocation op(0, /* word_size */
2085 gc_count_before,
2086 cause,
2087 true, /* should_initiate_conc_mark */
2088 g1_policy()->max_pause_time_ms());
2089 VMThread::execute(&op);
2090 if (!op.pause_succeeded()) {
2091 if (old_marking_count_before == _old_marking_cycles_started) {
2092 retry_gc = op.should_retry_gc();
2093 } else {
2094 // A Full GC happened while we were trying to schedule the
2095 // initial-mark GC. No point in starting a new cycle given
2096 // that the whole heap was collected anyway.
2097 }
2098
2099 if (retry_gc) {
2100 if (GCLocker::is_active_and_needs_gc()) {
2101 GCLocker::stall_until_clear();
2102 }
2103 }
2104 }
2105 } else {
2106 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2107 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2108
2109 // Schedule a standard evacuation pause. We're setting word_size
2110 // to 0 which means that we are not requesting a post-GC allocation.
2111 VM_G1CollectForAllocation op(0, /* word_size */
2112 gc_count_before,
2113 cause,
2114 false, /* should_initiate_conc_mark */
2115 g1_policy()->max_pause_time_ms());
2116 VMThread::execute(&op);
2117 } else {
2118 // Schedule a Full GC.
2119 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2120 VMThread::execute(&op);
2121 }
2122 }
2123 } while (retry_gc);
2124 }
2125
2126 bool G1CollectedHeap::is_in(const void* p) const {
2127 if (_hrm.reserved().contains(p)) {
2128 // Given that we know that p is in the reserved space,
2129 // heap_region_containing() should successfully
2130 // return the containing region.
2131 HeapRegion* hr = heap_region_containing(p);
2132 return hr->is_in(p);
2133 } else {
2134 return false;
2135 }
2136 }
2137
2138 #ifdef ASSERT
2139 bool G1CollectedHeap::is_in_exact(const void* p) const {
2140 bool contains = reserved_region().contains(p);
2141 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2142 if (contains && available) {
2143 return true;
2144 } else {
2145 return false;
2146 }
2147 }
2148 #endif
2149
2150 // Iteration functions.
2151
2152 // Iterates an ObjectClosure over all objects within a HeapRegion.
2153
2154 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2155 ObjectClosure* _cl;
2156 public:
2157 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2158 bool do_heap_region(HeapRegion* r) {
2159 if (!r->is_continues_humongous()) {
2160 r->object_iterate(_cl);
2161 }
2162 return false;
2163 }
2164 };
2165
2166 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2167 IterateObjectClosureRegionClosure blk(cl);
2168 heap_region_iterate(&blk);
2169 }
2170
2171 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2172 _hrm.iterate(cl);
2173 }
2174
2175 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2176 HeapRegionClaimer *hrclaimer,
2177 uint worker_id) const {
2178 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2179 }
2180
2181 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2182 HeapRegionClaimer *hrclaimer) const {
2183 _hrm.par_iterate(cl, hrclaimer, 0);
2184 }
2185
2186 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2187 _collection_set.iterate(cl);
2188 }
2189
2190 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2191 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2192 }
2193
2194 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2195 HeapRegion* hr = heap_region_containing(addr);
2196 return hr->block_start(addr);
2197 }
2198
2199 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2200 HeapRegion* hr = heap_region_containing(addr);
2201 return hr->block_size(addr);
2202 }
2203
2204 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2205 HeapRegion* hr = heap_region_containing(addr);
2206 return hr->block_is_obj(addr);
2207 }
2208
2209 bool G1CollectedHeap::supports_tlab_allocation() const {
2210 return true;
2211 }
2212
2213 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2214 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2215 }
2216
2217 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2218 return _eden.length() * HeapRegion::GrainBytes;
2219 }
2220
2221 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2222 // must be equal to the humongous object limit.
2223 size_t G1CollectedHeap::max_tlab_size() const {
2224 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2225 }
2226
2227 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2228 return _allocator->unsafe_max_tlab_alloc();
2229 }
2230
2231 size_t G1CollectedHeap::max_capacity() const {
2232 return _hrm.reserved().byte_size();
2233 }
2234
2235 jlong G1CollectedHeap::millis_since_last_gc() {
2236 // See the notes in GenCollectedHeap::millis_since_last_gc()
2237 // for more information about the implementation.
2238 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2239 _g1_policy->collection_pause_end_millis();
2240 if (ret_val < 0) {
2241 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2242 ". returning zero instead.", ret_val);
2243 return 0;
2244 }
2245 return ret_val;
2246 }
2247
2248 void G1CollectedHeap::deduplicate_string(oop str) {
2249 assert(java_lang_String::is_instance(str), "invariant");
2250
2251 if (G1StringDedup::is_enabled()) {
2252 G1StringDedup::deduplicate(str);
2253 }
2254 }
2255
2256 void G1CollectedHeap::prepare_for_verify() {
2257 _verifier->prepare_for_verify();
2258 }
2259
2260 void G1CollectedHeap::verify(VerifyOption vo) {
2261 _verifier->verify(vo);
2262 }
2263
2264 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2265 return true;
2266 }
2267
2268 const char* const* G1CollectedHeap::concurrent_phases() const {
2269 return _cm_thread->concurrent_phases();
2270 }
2271
2272 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2273 return _cm_thread->request_concurrent_phase(phase);
2274 }
2275
2276 class PrintRegionClosure: public HeapRegionClosure {
2277 outputStream* _st;
2278 public:
2279 PrintRegionClosure(outputStream* st) : _st(st) {}
2280 bool do_heap_region(HeapRegion* r) {
2281 r->print_on(_st);
2282 return false;
2283 }
2284 };
2285
2286 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2287 const HeapRegion* hr,
2288 const VerifyOption vo) const {
2289 switch (vo) {
2290 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2291 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2292 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2293 default: ShouldNotReachHere();
2294 }
2295 return false; // keep some compilers happy
2296 }
2297
2298 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2299 const VerifyOption vo) const {
2300 switch (vo) {
2301 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2302 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2303 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2304 default: ShouldNotReachHere();
2305 }
2306 return false; // keep some compilers happy
2307 }
2308
2309 void G1CollectedHeap::print_heap_regions() const {
2310 LogTarget(Trace, gc, heap, region) lt;
2311 if (lt.is_enabled()) {
2312 LogStream ls(lt);
2313 print_regions_on(&ls);
2314 }
2315 }
2316
2317 void G1CollectedHeap::print_on(outputStream* st) const {
2318 st->print(" %-20s", "garbage-first heap");
2319 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2320 capacity()/K, used_unlocked()/K);
2321 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2322 p2i(_hrm.reserved().start()),
2323 p2i(_hrm.reserved().end()));
2324 st->cr();
2325 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2326 uint young_regions = young_regions_count();
2327 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2328 (size_t) young_regions * HeapRegion::GrainBytes / K);
2329 uint survivor_regions = survivor_regions_count();
2330 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2331 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2332 st->cr();
2333 MetaspaceUtils::print_on(st);
2334 }
2335
2336 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2337 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2338 "HS=humongous(starts), HC=humongous(continues), "
2339 "CS=collection set, F=free, A=archive, "
2340 "TAMS=top-at-mark-start (previous, next)");
2341 PrintRegionClosure blk(st);
2342 heap_region_iterate(&blk);
2343 }
2344
2345 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2346 print_on(st);
2347
2348 // Print the per-region information.
2349 print_regions_on(st);
2350 }
2351
2352 void G1CollectedHeap::print_on_error(outputStream* st) const {
2353 this->CollectedHeap::print_on_error(st);
2354
2355 if (_cm != NULL) {
2356 st->cr();
2357 _cm->print_on_error(st);
2358 }
2359 }
2360
2361 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2362 workers()->print_worker_threads_on(st);
2363 _cm_thread->print_on(st);
2364 st->cr();
2365 _cm->print_worker_threads_on(st);
2366 _cr->print_threads_on(st);
2367 _young_gen_sampling_thread->print_on(st);
2368 if (G1StringDedup::is_enabled()) {
2369 G1StringDedup::print_worker_threads_on(st);
2370 }
2371 }
2372
2373 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2374 workers()->threads_do(tc);
2375 tc->do_thread(_cm_thread);
2376 _cm->threads_do(tc);
2377 _cr->threads_do(tc);
2378 tc->do_thread(_young_gen_sampling_thread);
2379 if (G1StringDedup::is_enabled()) {
2380 G1StringDedup::threads_do(tc);
2381 }
2382 }
2383
2384 void G1CollectedHeap::print_tracing_info() const {
2385 g1_rem_set()->print_summary_info();
2386 concurrent_mark()->print_summary_info();
2387 }
2388
2389 #ifndef PRODUCT
2390 // Helpful for debugging RSet issues.
2391
2392 class PrintRSetsClosure : public HeapRegionClosure {
2393 private:
2394 const char* _msg;
2395 size_t _occupied_sum;
2396
2397 public:
2398 bool do_heap_region(HeapRegion* r) {
2399 HeapRegionRemSet* hrrs = r->rem_set();
2400 size_t occupied = hrrs->occupied();
2401 _occupied_sum += occupied;
2402
2403 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2404 if (occupied == 0) {
2405 tty->print_cr(" RSet is empty");
2406 } else {
2407 hrrs->print();
2408 }
2409 tty->print_cr("----------");
2410 return false;
2411 }
2412
2413 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2414 tty->cr();
2415 tty->print_cr("========================================");
2416 tty->print_cr("%s", msg);
2417 tty->cr();
2418 }
2419
2420 ~PrintRSetsClosure() {
2421 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2422 tty->print_cr("========================================");
2423 tty->cr();
2424 }
2425 };
2426
2427 void G1CollectedHeap::print_cset_rsets() {
2428 PrintRSetsClosure cl("Printing CSet RSets");
2429 collection_set_iterate(&cl);
2430 }
2431
2432 void G1CollectedHeap::print_all_rsets() {
2433 PrintRSetsClosure cl("Printing All RSets");;
2434 heap_region_iterate(&cl);
2435 }
2436 #endif // PRODUCT
2437
2438 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2439
2440 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2441 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2442 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2443
2444 size_t eden_capacity_bytes =
2445 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2446
2447 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2448 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2449 eden_capacity_bytes, survivor_used_bytes, num_regions());
2450 }
2451
2452 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2453 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2454 stats->unused(), stats->used(), stats->region_end_waste(),
2455 stats->regions_filled(), stats->direct_allocated(),
2456 stats->failure_used(), stats->failure_waste());
2457 }
2458
2459 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2460 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2461 gc_tracer->report_gc_heap_summary(when, heap_summary);
2462
2463 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2464 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2465 }
2466
2467 G1CollectedHeap* G1CollectedHeap::heap() {
2468 CollectedHeap* heap = Universe::heap();
2469 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2470 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2471 return (G1CollectedHeap*)heap;
2472 }
2473
2474 void G1CollectedHeap::gc_prologue(bool full) {
2475 // always_do_update_barrier = false;
2476 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2477
2478 // This summary needs to be printed before incrementing total collections.
2479 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2480
2481 // Update common counters.
2482 increment_total_collections(full /* full gc */);
2483 if (full) {
2484 increment_old_marking_cycles_started();
2485 }
2486
2487 // Fill TLAB's and such
2488 double start = os::elapsedTime();
2489 ensure_parsability(true);
2490 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2491 }
2492
2493 void G1CollectedHeap::gc_epilogue(bool full) {
2494 // Update common counters.
2495 if (full) {
2496 // Update the number of full collections that have been completed.
2497 increment_old_marking_cycles_completed(false /* concurrent */);
2498 }
2499
2500 // We are at the end of the GC. Total collections has already been increased.
2501 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2502
2503 // FIXME: what is this about?
2504 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2505 // is set.
2506 #if COMPILER2_OR_JVMCI
2507 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2508 #endif
2509 // always_do_update_barrier = true;
2510
2511 double start = os::elapsedTime();
2512 resize_all_tlabs();
2513 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2514
2515 MemoryService::track_memory_usage();
2516 // We have just completed a GC. Update the soft reference
2517 // policy with the new heap occupancy
2518 Universe::update_heap_info_at_gc();
2519 }
2520
2521 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2522 uint gc_count_before,
2523 bool* succeeded,
2524 GCCause::Cause gc_cause) {
2525 assert_heap_not_locked_and_not_at_safepoint();
2526 VM_G1CollectForAllocation op(word_size,
2527 gc_count_before,
2528 gc_cause,
2529 false, /* should_initiate_conc_mark */
2530 g1_policy()->max_pause_time_ms());
2531 VMThread::execute(&op);
2532
2533 HeapWord* result = op.result();
2534 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2535 assert(result == NULL || ret_succeeded,
2536 "the result should be NULL if the VM did not succeed");
2537 *succeeded = ret_succeeded;
2538
2539 assert_heap_not_locked();
2540 return result;
2541 }
2542
2543 void G1CollectedHeap::do_concurrent_mark() {
2544 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2545 if (!_cm_thread->in_progress()) {
2546 _cm_thread->set_started();
2547 CGC_lock->notify();
2548 }
2549 }
2550
2551 size_t G1CollectedHeap::pending_card_num() {
2552 size_t extra_cards = 0;
2553 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2554 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2555 extra_cards += dcq.size();
2556 }
2557 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2558 size_t buffer_size = dcqs.buffer_size();
2559 size_t buffer_num = dcqs.completed_buffers_num();
2560
2561 return buffer_size * buffer_num + extra_cards;
2562 }
2563
2564 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2565 // We don't nominate objects with many remembered set entries, on
2566 // the assumption that such objects are likely still live.
2567 HeapRegionRemSet* rem_set = r->rem_set();
2568
2569 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2570 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2571 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2572 }
2573
2574 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2575 private:
2576 size_t _total_humongous;
2577 size_t _candidate_humongous;
2578
2579 DirtyCardQueue _dcq;
2580
2581 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2582 assert(region->is_starts_humongous(), "Must start a humongous object");
2583
2584 oop obj = oop(region->bottom());
2585
2586 // Dead objects cannot be eager reclaim candidates. Due to class
2587 // unloading it is unsafe to query their classes so we return early.
2588 if (g1h->is_obj_dead(obj, region)) {
2589 return false;
2590 }
2591
2592 // If we do not have a complete remembered set for the region, then we can
2593 // not be sure that we have all references to it.
2594 if (!region->rem_set()->is_complete()) {
2595 return false;
2596 }
2597 // Candidate selection must satisfy the following constraints
2598 // while concurrent marking is in progress:
2599 //
2600 // * In order to maintain SATB invariants, an object must not be
2601 // reclaimed if it was allocated before the start of marking and
2602 // has not had its references scanned. Such an object must have
2603 // its references (including type metadata) scanned to ensure no
2604 // live objects are missed by the marking process. Objects
2605 // allocated after the start of concurrent marking don't need to
2606 // be scanned.
2607 //
2608 // * An object must not be reclaimed if it is on the concurrent
2609 // mark stack. Objects allocated after the start of concurrent
2610 // marking are never pushed on the mark stack.
2611 //
2612 // Nominating only objects allocated after the start of concurrent
2613 // marking is sufficient to meet both constraints. This may miss
2614 // some objects that satisfy the constraints, but the marking data
2615 // structures don't support efficiently performing the needed
2616 // additional tests or scrubbing of the mark stack.
2617 //
2618 // However, we presently only nominate is_typeArray() objects.
2619 // A humongous object containing references induces remembered
2620 // set entries on other regions. In order to reclaim such an
2621 // object, those remembered sets would need to be cleaned up.
2622 //
2623 // We also treat is_typeArray() objects specially, allowing them
2624 // to be reclaimed even if allocated before the start of
2625 // concurrent mark. For this we rely on mark stack insertion to
2626 // exclude is_typeArray() objects, preventing reclaiming an object
2627 // that is in the mark stack. We also rely on the metadata for
2628 // such objects to be built-in and so ensured to be kept live.
2629 // Frequent allocation and drop of large binary blobs is an
2630 // important use case for eager reclaim, and this special handling
2631 // may reduce needed headroom.
2632
2633 return obj->is_typeArray() &&
2634 g1h->is_potential_eager_reclaim_candidate(region);
2635 }
2636
2637 public:
2638 RegisterHumongousWithInCSetFastTestClosure()
2639 : _total_humongous(0),
2640 _candidate_humongous(0),
2641 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2642 }
2643
2644 virtual bool do_heap_region(HeapRegion* r) {
2645 if (!r->is_starts_humongous()) {
2646 return false;
2647 }
2648 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2649
2650 bool is_candidate = humongous_region_is_candidate(g1h, r);
2651 uint rindex = r->hrm_index();
2652 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2653 if (is_candidate) {
2654 _candidate_humongous++;
2655 g1h->register_humongous_region_with_cset(rindex);
2656 // Is_candidate already filters out humongous object with large remembered sets.
2657 // If we have a humongous object with a few remembered sets, we simply flush these
2658 // remembered set entries into the DCQS. That will result in automatic
2659 // re-evaluation of their remembered set entries during the following evacuation
2660 // phase.
2661 if (!r->rem_set()->is_empty()) {
2662 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2663 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2664 G1CardTable* ct = g1h->card_table();
2665 HeapRegionRemSetIterator hrrs(r->rem_set());
2666 size_t card_index;
2667 while (hrrs.has_next(card_index)) {
2668 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2669 // The remembered set might contain references to already freed
2670 // regions. Filter out such entries to avoid failing card table
2671 // verification.
2672 if (!g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2673 continue;
2674 }
2675 if (*card_ptr != G1CardTable::dirty_card_val()) {
2676 *card_ptr = G1CardTable::dirty_card_val();
2677 _dcq.enqueue(card_ptr);
2678 }
2679 }
2680 // We should only clear the card based remembered set here as we will not
2681 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2682 // (and probably never) we do not enter this path if there are other kind of
2683 // remembered sets for this region.
2684 r->rem_set()->clear_locked(true /* only_cardset */);
2685 // Clear_locked() above sets the state to Empty. However we want to continue
2686 // collecting remembered set entries for humongous regions that were not
2687 // reclaimed.
2688 r->rem_set()->set_state_complete();
2689 }
2690 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2691 }
2692 _total_humongous++;
2693
2694 return false;
2695 }
2696
2697 size_t total_humongous() const { return _total_humongous; }
2698 size_t candidate_humongous() const { return _candidate_humongous; }
2699
2700 void flush_rem_set_entries() { _dcq.flush(); }
2701 };
2702
2703 void G1CollectedHeap::register_humongous_regions_with_cset() {
2704 if (!G1EagerReclaimHumongousObjects) {
2705 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2706 return;
2707 }
2708 double time = os::elapsed_counter();
2709
2710 // Collect reclaim candidate information and register candidates with cset.
2711 RegisterHumongousWithInCSetFastTestClosure cl;
2712 heap_region_iterate(&cl);
2713
2714 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2715 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2716 cl.total_humongous(),
2717 cl.candidate_humongous());
2718 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2719
2720 // Finally flush all remembered set entries to re-check into the global DCQS.
2721 cl.flush_rem_set_entries();
2722 }
2723
2724 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2725 public:
2726 bool do_heap_region(HeapRegion* hr) {
2727 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2728 hr->verify_rem_set();
2729 }
2730 return false;
2731 }
2732 };
2733
2734 uint G1CollectedHeap::num_task_queues() const {
2735 return _task_queues->size();
2736 }
2737
2738 #if TASKQUEUE_STATS
2739 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2740 st->print_raw_cr("GC Task Stats");
2741 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2742 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2743 }
2744
2745 void G1CollectedHeap::print_taskqueue_stats() const {
2746 if (!log_is_enabled(Trace, gc, task, stats)) {
2747 return;
2748 }
2749 Log(gc, task, stats) log;
2750 ResourceMark rm;
2751 LogStream ls(log.trace());
2752 outputStream* st = &ls;
2753
2754 print_taskqueue_stats_hdr(st);
2755
2756 TaskQueueStats totals;
2757 const uint n = num_task_queues();
2758 for (uint i = 0; i < n; ++i) {
2759 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2760 totals += task_queue(i)->stats;
2761 }
2762 st->print_raw("tot "); totals.print(st); st->cr();
2763
2764 DEBUG_ONLY(totals.verify());
2765 }
2766
2767 void G1CollectedHeap::reset_taskqueue_stats() {
2768 const uint n = num_task_queues();
2769 for (uint i = 0; i < n; ++i) {
2770 task_queue(i)->stats.reset();
2771 }
2772 }
2773 #endif // TASKQUEUE_STATS
2774
2775 void G1CollectedHeap::wait_for_root_region_scanning() {
2776 double scan_wait_start = os::elapsedTime();
2777 // We have to wait until the CM threads finish scanning the
2778 // root regions as it's the only way to ensure that all the
2779 // objects on them have been correctly scanned before we start
2780 // moving them during the GC.
2781 bool waited = _cm->root_regions()->wait_until_scan_finished();
2782 double wait_time_ms = 0.0;
2783 if (waited) {
2784 double scan_wait_end = os::elapsedTime();
2785 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2786 }
2787 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2788 }
2789
2790 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2791 private:
2792 G1HRPrinter* _hr_printer;
2793 public:
2794 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2795
2796 virtual bool do_heap_region(HeapRegion* r) {
2797 _hr_printer->cset(r);
2798 return false;
2799 }
2800 };
2801
2802 void G1CollectedHeap::start_new_collection_set() {
2803 collection_set()->start_incremental_building();
2804
2805 clear_cset_fast_test();
2806
2807 guarantee(_eden.length() == 0, "eden should have been cleared");
2808 g1_policy()->transfer_survivors_to_cset(survivor());
2809 }
2810
2811 bool
2812 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2813 assert_at_safepoint_on_vm_thread();
2814 guarantee(!is_gc_active(), "collection is not reentrant");
2815
2816 if (GCLocker::check_active_before_gc()) {
2817 return false;
2818 }
2819
2820 _gc_timer_stw->register_gc_start();
2821
2822 GCIdMark gc_id_mark;
2823 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2824
2825 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2826 ResourceMark rm;
2827
2828 g1_policy()->note_gc_start();
2829
2830 wait_for_root_region_scanning();
2831
2832 print_heap_before_gc();
2833 print_heap_regions();
2834 trace_heap_before_gc(_gc_tracer_stw);
2835
2836 _verifier->verify_region_sets_optional();
2837 _verifier->verify_dirty_young_regions();
2838
2839 // We should not be doing initial mark unless the conc mark thread is running
2840 if (!_cm_thread->should_terminate()) {
2841 // This call will decide whether this pause is an initial-mark
2842 // pause. If it is, in_initial_mark_gc() will return true
2843 // for the duration of this pause.
2844 g1_policy()->decide_on_conc_mark_initiation();
2845 }
2846
2847 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2848 assert(!collector_state()->in_initial_mark_gc() ||
2849 collector_state()->in_young_only_phase(), "sanity");
2850
2851 // We also do not allow mixed GCs during marking.
2852 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2853
2854 // Record whether this pause is an initial mark. When the current
2855 // thread has completed its logging output and it's safe to signal
2856 // the CM thread, the flag's value in the policy has been reset.
2857 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2858
2859 // Inner scope for scope based logging, timers, and stats collection
2860 {
2861 EvacuationInfo evacuation_info;
2862
2863 if (collector_state()->in_initial_mark_gc()) {
2864 // We are about to start a marking cycle, so we increment the
2865 // full collection counter.
2866 increment_old_marking_cycles_started();
2867 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2868 }
2869
2870 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2871
2872 GCTraceCPUTime tcpu;
2873
2874 G1HeapVerifier::G1VerifyType verify_type;
2875 FormatBuffer<> gc_string("Pause Young ");
2876 if (collector_state()->in_initial_mark_gc()) {
2877 gc_string.append("(Concurrent Start)");
2878 verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2879 } else if (collector_state()->in_young_only_phase()) {
2880 if (collector_state()->in_young_gc_before_mixed()) {
2881 gc_string.append("(Prepare Mixed)");
2882 } else {
2883 gc_string.append("(Normal)");
2884 }
2885 verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2886 } else {
2887 gc_string.append("(Mixed)");
2888 verify_type = G1HeapVerifier::G1VerifyMixed;
2889 }
2890 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2891
2892 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2893 workers()->active_workers(),
2894 Threads::number_of_non_daemon_threads());
2895 active_workers = workers()->update_active_workers(active_workers);
2896 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2897
2898 G1MonitoringScope ms(g1mm(),
2899 false /* full_gc */,
2900 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2901
2902 G1HeapTransition heap_transition(this);
2903 size_t heap_used_bytes_before_gc = used();
2904
2905 // Don't dynamically change the number of GC threads this early. A value of
2906 // 0 is used to indicate serial work. When parallel work is done,
2907 // it will be set.
2908
2909 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2910 IsGCActiveMark x;
2911
2912 gc_prologue(false);
2913
2914 if (VerifyRememberedSets) {
2915 log_info(gc, verify)("[Verifying RemSets before GC]");
2916 VerifyRegionRemSetClosure v_cl;
2917 heap_region_iterate(&v_cl);
2918 }
2919
2920 _verifier->verify_before_gc(verify_type);
2921
2922 _verifier->check_bitmaps("GC Start");
2923
2924 #if COMPILER2_OR_JVMCI
2925 DerivedPointerTable::clear();
2926 #endif
2927
2928 // Please see comment in g1CollectedHeap.hpp and
2929 // G1CollectedHeap::ref_processing_init() to see how
2930 // reference processing currently works in G1.
2931
2932 // Enable discovery in the STW reference processor
2933 _ref_processor_stw->enable_discovery();
2934
2935 {
2936 // We want to temporarily turn off discovery by the
2937 // CM ref processor, if necessary, and turn it back on
2938 // on again later if we do. Using a scoped
2939 // NoRefDiscovery object will do this.
2940 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2941
2942 // Forget the current alloc region (we might even choose it to be part
2943 // of the collection set!).
2944 _allocator->release_mutator_alloc_region();
2945
2946 // This timing is only used by the ergonomics to handle our pause target.
2947 // It is unclear why this should not include the full pause. We will
2948 // investigate this in CR 7178365.
2949 //
2950 // Preserving the old comment here if that helps the investigation:
2951 //
2952 // The elapsed time induced by the start time below deliberately elides
2953 // the possible verification above.
2954 double sample_start_time_sec = os::elapsedTime();
2955
2956 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2957
2958 if (collector_state()->in_initial_mark_gc()) {
2959 concurrent_mark()->pre_initial_mark();
2960 }
2961
2962 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2963
2964 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2965
2966 // Make sure the remembered sets are up to date. This needs to be
2967 // done before register_humongous_regions_with_cset(), because the
2968 // remembered sets are used there to choose eager reclaim candidates.
2969 // If the remembered sets are not up to date we might miss some
2970 // entries that need to be handled.
2971 g1_rem_set()->cleanupHRRS();
2972
2973 register_humongous_regions_with_cset();
2974
2975 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2976
2977 // We call this after finalize_cset() to
2978 // ensure that the CSet has been finalized.
2979 _cm->verify_no_cset_oops();
2980
2981 if (_hr_printer.is_active()) {
2982 G1PrintCollectionSetClosure cl(&_hr_printer);
2983 _collection_set.iterate(&cl);
2984 }
2985
2986 // Initialize the GC alloc regions.
2987 _allocator->init_gc_alloc_regions(evacuation_info);
2988
2989 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2990 pre_evacuate_collection_set();
2991
2992 // Actually do the work...
2993 evacuate_collection_set(&per_thread_states);
2994
2995 post_evacuate_collection_set(evacuation_info, &per_thread_states);
2996
2997 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2998 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2999
3000 eagerly_reclaim_humongous_regions();
3001
3002 record_obj_copy_mem_stats();
3003 _survivor_evac_stats.adjust_desired_plab_sz();
3004 _old_evac_stats.adjust_desired_plab_sz();
3005
3006 double start = os::elapsedTime();
3007 start_new_collection_set();
3008 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3009
3010 if (evacuation_failed()) {
3011 double recalculate_used_start = os::elapsedTime();
3012 set_used(recalculate_used());
3013 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3014
3015 if (_archive_allocator != NULL) {
3016 _archive_allocator->clear_used();
3017 }
3018 for (uint i = 0; i < ParallelGCThreads; i++) {
3019 if (_evacuation_failed_info_array[i].has_failed()) {
3020 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3021 }
3022 }
3023 } else {
3024 // The "used" of the the collection set have already been subtracted
3025 // when they were freed. Add in the bytes evacuated.
3026 increase_used(g1_policy()->bytes_copied_during_gc());
3027 }
3028
3029 if (collector_state()->in_initial_mark_gc()) {
3030 // We have to do this before we notify the CM threads that
3031 // they can start working to make sure that all the
3032 // appropriate initialization is done on the CM object.
3033 concurrent_mark()->post_initial_mark();
3034 // Note that we don't actually trigger the CM thread at
3035 // this point. We do that later when we're sure that
3036 // the current thread has completed its logging output.
3037 }
3038
3039 allocate_dummy_regions();
3040
3041 _allocator->init_mutator_alloc_region();
3042
3043 {
3044 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3045 if (expand_bytes > 0) {
3046 size_t bytes_before = capacity();
3047 // No need for an ergo logging here,
3048 // expansion_amount() does this when it returns a value > 0.
3049 double expand_ms;
3050 if (!expand(expand_bytes, _workers, &expand_ms)) {
3051 // We failed to expand the heap. Cannot do anything about it.
3052 }
3053 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3054 }
3055 }
3056
3057 // We redo the verification but now wrt to the new CSet which
3058 // has just got initialized after the previous CSet was freed.
3059 _cm->verify_no_cset_oops();
3060
3061 // This timing is only used by the ergonomics to handle our pause target.
3062 // It is unclear why this should not include the full pause. We will
3063 // investigate this in CR 7178365.
3064 double sample_end_time_sec = os::elapsedTime();
3065 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3066 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3067 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3068
3069 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3070 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3071
3072 if (VerifyRememberedSets) {
3073 log_info(gc, verify)("[Verifying RemSets after GC]");
3074 VerifyRegionRemSetClosure v_cl;
3075 heap_region_iterate(&v_cl);
3076 }
3077
3078 _verifier->verify_after_gc(verify_type);
3079 _verifier->check_bitmaps("GC End");
3080
3081 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3082 _ref_processor_stw->verify_no_references_recorded();
3083
3084 // CM reference discovery will be re-enabled if necessary.
3085 }
3086
3087 #ifdef TRACESPINNING
3088 ParallelTaskTerminator::print_termination_counts();
3089 #endif
3090
3091 gc_epilogue(false);
3092 }
3093
3094 // Print the remainder of the GC log output.
3095 if (evacuation_failed()) {
3096 log_info(gc)("To-space exhausted");
3097 }
3098
3099 g1_policy()->print_phases();
3100 heap_transition.print();
3101
3102 // It is not yet to safe to tell the concurrent mark to
3103 // start as we have some optional output below. We don't want the
3104 // output from the concurrent mark thread interfering with this
3105 // logging output either.
3106
3107 _hrm.verify_optional();
3108 _verifier->verify_region_sets_optional();
3109
3110 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3111 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3112
3113 print_heap_after_gc();
3114 print_heap_regions();
3115 trace_heap_after_gc(_gc_tracer_stw);
3116
3117 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3118 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3119 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3120 // before any GC notifications are raised.
3121 g1mm()->update_sizes();
3122
3123 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3124 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3125 _gc_timer_stw->register_gc_end();
3126 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3127 }
3128 // It should now be safe to tell the concurrent mark thread to start
3129 // without its logging output interfering with the logging output
3130 // that came from the pause.
3131
3132 if (should_start_conc_mark) {
3133 // CAUTION: after the doConcurrentMark() call below,
3134 // the concurrent marking thread(s) could be running
3135 // concurrently with us. Make sure that anything after
3136 // this point does not assume that we are the only GC thread
3137 // running. Note: of course, the actual marking work will
3138 // not start until the safepoint itself is released in
3139 // SuspendibleThreadSet::desynchronize().
3140 do_concurrent_mark();
3141 }
3142
3143 return true;
3144 }
3145
3146 void G1CollectedHeap::remove_self_forwarding_pointers() {
3147 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3148 workers()->run_task(&rsfp_task);
3149 }
3150
3151 void G1CollectedHeap::restore_after_evac_failure() {
3152 double remove_self_forwards_start = os::elapsedTime();
3153
3154 remove_self_forwarding_pointers();
3155 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3156 _preserved_marks_set.restore(&task_executor);
3157
3158 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3159 }
3160
3161 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3162 if (!_evacuation_failed) {
3163 _evacuation_failed = true;
3164 }
3165
3166 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3167 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3168 }
3169
3170 bool G1ParEvacuateFollowersClosure::offer_termination() {
3171 EventGCPhaseParallel event;
3172 G1ParScanThreadState* const pss = par_scan_state();
3173 start_term_time();
3174 const bool res = terminator()->offer_termination();
3175 end_term_time();
3176 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3177 return res;
3178 }
3179
3180 void G1ParEvacuateFollowersClosure::do_void() {
3181 EventGCPhaseParallel event;
3182 G1ParScanThreadState* const pss = par_scan_state();
3183 pss->trim_queue();
3184 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3185 do {
3186 EventGCPhaseParallel event;
3187 pss->steal_and_trim_queue(queues());
3188 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3189 } while (!offer_termination());
3190 }
3191
3192 class G1ParTask : public AbstractGangTask {
3193 protected:
3194 G1CollectedHeap* _g1h;
3195 G1ParScanThreadStateSet* _pss;
3196 RefToScanQueueSet* _queues;
3197 G1RootProcessor* _root_processor;
3198 ParallelTaskTerminator _terminator;
3199 uint _n_workers;
3200
3201 public:
3202 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3203 : AbstractGangTask("G1 collection"),
3204 _g1h(g1h),
3205 _pss(per_thread_states),
3206 _queues(task_queues),
3207 _root_processor(root_processor),
3208 _terminator(n_workers, _queues),
3209 _n_workers(n_workers)
3210 {}
3211
3212 void work(uint worker_id) {
3213 if (worker_id >= _n_workers) return; // no work needed this round
3214
3215 double start_sec = os::elapsedTime();
3216 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3217
3218 {
3219 ResourceMark rm;
3220 HandleMark hm;
3221
3222 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3223
3224 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3225 pss->set_ref_discoverer(rp);
3226
3227 double start_strong_roots_sec = os::elapsedTime();
3228
3229 _root_processor->evacuate_roots(pss, worker_id);
3230
3231 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3232 // treating the nmethods visited to act as roots for concurrent marking.
3233 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3234 // objects copied by the current evacuation.
3235 _g1h->g1_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);
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->g1_policy()->phase_times();
3251 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3252 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3253 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3254 }
3255
3256 assert(pss->queue_is_empty(), "should be empty");
3257
3258 if (log_is_enabled(Debug, gc, task, stats)) {
3259 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3260 size_t lab_waste;
3261 size_t lab_undo_waste;
3262 pss->waste(lab_waste, lab_undo_waste);
3263 _g1h->print_termination_stats(worker_id,
3264 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3265 strong_roots_sec * 1000.0, /* strong roots time */
3266 term_sec * 1000.0, /* evac term time */
3267 evac_term_attempts, /* evac term attempts */
3268 lab_waste, /* alloc buffer waste */
3269 lab_undo_waste /* undo waste */
3270 );
3271 }
3272
3273 // Close the inner scope so that the ResourceMark and HandleMark
3274 // destructors are executed here and are included as part of the
3275 // "GC Worker Time".
3276 }
3277 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3278 }
3279 };
3280
3281 void G1CollectedHeap::print_termination_stats_hdr() {
3282 log_debug(gc, task, stats)("GC Termination Stats");
3283 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3284 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3285 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3286 }
3287
3288 void G1CollectedHeap::print_termination_stats(uint worker_id,
3289 double elapsed_ms,
3290 double strong_roots_ms,
3291 double term_ms,
3292 size_t term_attempts,
3293 size_t alloc_buffer_waste,
3294 size_t undo_waste) const {
3295 log_debug(gc, task, stats)
3296 ("%3d %9.2f %9.2f %6.2f "
3297 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3298 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3299 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3300 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3301 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3302 alloc_buffer_waste * HeapWordSize / K,
3303 undo_waste * HeapWordSize / K);
3304 }
3305
3306 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3307 bool class_unloading_occurred) {
3308 uint n_workers = workers()->active_workers();
3309
3310 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3311 ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
3312 workers()->run_task(&g1_unlink_task);
3313 }
3314
3315 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3316 bool process_strings,
3317 bool process_string_dedup) {
3318 if (!process_strings && !process_string_dedup) {
3319 // Nothing to clean.
3320 return;
3321 }
3322
3323 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3324 StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
3325 workers()->run_task(&g1_unlink_task);
3326 }
3327
3328 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3329 private:
3330 DirtyCardQueueSet* _queue;
3331 G1CollectedHeap* _g1h;
3332 public:
3333 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3334 _queue(queue), _g1h(g1h) { }
3335
3336 virtual void work(uint worker_id) {
3337 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3338 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3339
3340 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3341 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3342
3343 phase_times->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 DirtyCardQueueSet& 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 g1_policy()->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);
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 ParallelTaskTerminator terminator(ergo_workers, _queues);
3556 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &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 = g1_policy()->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 rp->verify_no_references_recorded();
3625
3626 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3627 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3628 }
3629
3630 void G1CollectedHeap::make_pending_list_reachable() {
3631 if (collector_state()->in_initial_mark_gc()) {
3632 oop pll_head = Universe::reference_pending_list();
3633 if (pll_head != NULL) {
3634 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3635 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3636 }
3637 }
3638 }
3639
3640 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3641 double merge_pss_time_start = os::elapsedTime();
3642 per_thread_states->flush();
3643 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3644 }
3645
3646 void G1CollectedHeap::pre_evacuate_collection_set() {
3647 _expand_heap_after_alloc_failure = true;
3648 _evacuation_failed = false;
3649
3650 // Disable the hot card cache.
3651 _hot_card_cache->reset_hot_cache_claimed_index();
3652 _hot_card_cache->set_use_cache(false);
3653
3654 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3655 _preserved_marks_set.assert_empty();
3656
3657 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3658
3659 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3660 if (collector_state()->in_initial_mark_gc()) {
3661 double start_clear_claimed_marks = os::elapsedTime();
3662
3663 ClassLoaderDataGraph::clear_claimed_marks();
3664
3665 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3666 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3667 }
3668 }
3669
3670 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3671 // Should G1EvacuationFailureALot be in effect for this GC?
3672 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3673
3674 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3675
3676 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3677
3678 double start_par_time_sec = os::elapsedTime();
3679 double end_par_time_sec;
3680
3681 {
3682 const uint n_workers = workers()->active_workers();
3683 G1RootProcessor root_processor(this, n_workers);
3684 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3685
3686 print_termination_stats_hdr();
3687
3688 workers()->run_task(&g1_par_task);
3689 end_par_time_sec = os::elapsedTime();
3690
3691 // Closing the inner scope will execute the destructor
3692 // for the G1RootProcessor object. We record the current
3693 // elapsed time before closing the scope so that time
3694 // taken for the destructor is NOT included in the
3695 // reported parallel time.
3696 }
3697
3698 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3699 phase_times->record_par_time(par_time_ms);
3700
3701 double code_root_fixup_time_ms =
3702 (os::elapsedTime() - end_par_time_sec) * 1000.0;
3703 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3704 }
3705
3706 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3707 // Also cleans the card table from temporary duplicate detection information used
3708 // during UpdateRS/ScanRS.
3709 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3710
3711 // Process any discovered reference objects - we have
3712 // to do this _before_ we retire the GC alloc regions
3713 // as we may have to copy some 'reachable' referent
3714 // objects (and their reachable sub-graphs) that were
3715 // not copied during the pause.
3716 process_discovered_references(per_thread_states);
3717
3718 // FIXME
3719 // CM's reference processing also cleans up the string table.
3720 // Should we do that here also? We could, but it is a serial operation
3721 // and could significantly increase the pause time.
3722
3723 G1STWIsAliveClosure is_alive(this);
3724 G1KeepAliveClosure keep_alive(this);
3725
3726 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3727 g1_policy()->phase_times()->weak_phase_times());
3728
3729 if (G1StringDedup::is_enabled()) {
3730 double fixup_start = os::elapsedTime();
3731
3732 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
3733
3734 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
3735 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
3736 }
3737
3738 if (evacuation_failed()) {
3739 restore_after_evac_failure();
3740
3741 // Reset the G1EvacuationFailureALot counters and flags
3742 // Note: the values are reset only when an actual
3743 // evacuation failure occurs.
3744 NOT_PRODUCT(reset_evacuation_should_fail();)
3745 }
3746
3747 _preserved_marks_set.assert_empty();
3748
3749 _allocator->release_gc_alloc_regions(evacuation_info);
3750
3751 merge_per_thread_state_info(per_thread_states);
3752
3753 // Reset and re-enable the hot card cache.
3754 // Note the counts for the cards in the regions in the
3755 // collection set are reset when the collection set is freed.
3756 _hot_card_cache->reset_hot_cache();
3757 _hot_card_cache->set_use_cache(true);
3758
3759 purge_code_root_memory();
3760
3761 redirty_logged_cards();
3762 #if COMPILER2_OR_JVMCI
3763 double start = os::elapsedTime();
3764 DerivedPointerTable::update_pointers();
3765 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3766 #endif
3767 g1_policy()->print_age_table();
3768 }
3769
3770 void G1CollectedHeap::record_obj_copy_mem_stats() {
3771 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3772
3773 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3774 create_g1_evac_summary(&_old_evac_stats));
3775 }
3776
3777 void G1CollectedHeap::free_region(HeapRegion* hr,
3778 FreeRegionList* free_list,
3779 bool skip_remset,
3780 bool skip_hot_card_cache,
3781 bool locked) {
3782 assert(!hr->is_free(), "the region should not be free");
3783 assert(!hr->is_empty(), "the region should not be empty");
3784 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
3785 assert(free_list != NULL, "pre-condition");
3786
3787 if (G1VerifyBitmaps) {
3788 MemRegion mr(hr->bottom(), hr->end());
3789 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3790 }
3791
3792 // Clear the card counts for this region.
3793 // Note: we only need to do this if the region is not young
3794 // (since we don't refine cards in young regions).
3795 if (!skip_hot_card_cache && !hr->is_young()) {
3796 _hot_card_cache->reset_card_counts(hr);
3797 }
3798 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3799 _g1_policy->remset_tracker()->update_at_free(hr);
3800 free_list->add_ordered(hr);
3801 }
3802
3803 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3804 FreeRegionList* free_list) {
3805 assert(hr->is_humongous(), "this is only for humongous regions");
3806 assert(free_list != NULL, "pre-condition");
3807 hr->clear_humongous();
3808 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3809 }
3810
3811 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3812 const uint humongous_regions_removed) {
3813 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3814 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3815 _old_set.bulk_remove(old_regions_removed);
3816 _humongous_set.bulk_remove(humongous_regions_removed);
3817 }
3818
3819 }
3820
3821 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3822 assert(list != NULL, "list can't be null");
3823 if (!list->is_empty()) {
3824 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3825 _hrm.insert_list_into_free_list(list);
3826 }
3827 }
3828
3829 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3830 decrease_used(bytes);
3831 }
3832
3833 class G1FreeCollectionSetTask : public AbstractGangTask {
3834 private:
3835
3836 // Closure applied to all regions in the collection set to do work that needs to
3837 // be done serially in a single thread.
3838 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3839 private:
3840 EvacuationInfo* _evacuation_info;
3841 const size_t* _surviving_young_words;
3842
3843 // Bytes used in successfully evacuated regions before the evacuation.
3844 size_t _before_used_bytes;
3845 // Bytes used in unsucessfully evacuated regions before the evacuation
3846 size_t _after_used_bytes;
3847
3848 size_t _bytes_allocated_in_old_since_last_gc;
3849
3850 size_t _failure_used_words;
3851 size_t _failure_waste_words;
3852
3853 FreeRegionList _local_free_list;
3854 public:
3855 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3856 HeapRegionClosure(),
3857 _evacuation_info(evacuation_info),
3858 _surviving_young_words(surviving_young_words),
3859 _before_used_bytes(0),
3860 _after_used_bytes(0),
3861 _bytes_allocated_in_old_since_last_gc(0),
3862 _failure_used_words(0),
3863 _failure_waste_words(0),
3864 _local_free_list("Local Region List for CSet Freeing") {
3865 }
3866
3867 virtual bool do_heap_region(HeapRegion* r) {
3868 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3869
3870 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3871 g1h->clear_in_cset(r);
3872
3873 if (r->is_young()) {
3874 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3875 "Young index %d is wrong for region %u of type %s with %u young regions",
3876 r->young_index_in_cset(),
3877 r->hrm_index(),
3878 r->get_type_str(),
3879 g1h->collection_set()->young_region_length());
3880 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3881 r->record_surv_words_in_group(words_survived);
3882 }
3883
3884 if (!r->evacuation_failed()) {
3885 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
3886 _before_used_bytes += r->used();
3887 g1h->free_region(r,
3888 &_local_free_list,
3889 true, /* skip_remset */
3890 true, /* skip_hot_card_cache */
3891 true /* locked */);
3892 } else {
3893 r->uninstall_surv_rate_group();
3894 r->set_young_index_in_cset(-1);
3895 r->set_evacuation_failed(false);
3896 // When moving a young gen region to old gen, we "allocate" that whole region
3897 // there. This is in addition to any already evacuated objects. Notify the
3898 // policy about that.
3899 // Old gen regions do not cause an additional allocation: both the objects
3900 // still in the region and the ones already moved are accounted for elsewhere.
3901 if (r->is_young()) {
3902 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
3903 }
3904 // The region is now considered to be old.
3905 r->set_old();
3906 // Do some allocation statistics accounting. Regions that failed evacuation
3907 // are always made old, so there is no need to update anything in the young
3908 // gen statistics, but we need to update old gen statistics.
3909 size_t used_words = r->marked_bytes() / HeapWordSize;
3910
3911 _failure_used_words += used_words;
3912 _failure_waste_words += HeapRegion::GrainWords - used_words;
3913
3914 g1h->old_set_add(r);
3915 _after_used_bytes += r->used();
3916 }
3917 return false;
3918 }
3919
3920 void complete_work() {
3921 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3922
3923 _evacuation_info->set_regions_freed(_local_free_list.length());
3924 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
3925
3926 g1h->prepend_to_freelist(&_local_free_list);
3927 g1h->decrement_summary_bytes(_before_used_bytes);
3928
3929 G1Policy* policy = g1h->g1_policy();
3930 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
3931
3932 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
3933 }
3934 };
3935
3936 G1CollectionSet* _collection_set;
3937 G1SerialFreeCollectionSetClosure _cl;
3938 const size_t* _surviving_young_words;
3939
3940 size_t _rs_lengths;
3941
3942 volatile jint _serial_work_claim;
3943
3944 struct WorkItem {
3945 uint region_idx;
3946 bool is_young;
3947 bool evacuation_failed;
3948
3949 WorkItem(HeapRegion* r) {
3950 region_idx = r->hrm_index();
3951 is_young = r->is_young();
3952 evacuation_failed = r->evacuation_failed();
3953 }
3954 };
3955
3956 volatile size_t _parallel_work_claim;
3957 size_t _num_work_items;
3958 WorkItem* _work_items;
3959
3960 void do_serial_work() {
3961 // Need to grab the lock to be allowed to modify the old region list.
3962 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3963 _collection_set->iterate(&_cl);
3964 }
3965
3966 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
3967 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3968
3969 HeapRegion* r = g1h->region_at(region_idx);
3970 assert(!g1h->is_on_master_free_list(r), "sanity");
3971
3972 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
3973
3974 if (!is_young) {
3975 g1h->_hot_card_cache->reset_card_counts(r);
3976 }
3977
3978 if (!evacuation_failed) {
3979 r->rem_set()->clear_locked();
3980 }
3981 }
3982
3983 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
3984 private:
3985 size_t _cur_idx;
3986 WorkItem* _work_items;
3987 public:
3988 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
3989
3990 virtual bool do_heap_region(HeapRegion* r) {
3991 _work_items[_cur_idx++] = WorkItem(r);
3992 return false;
3993 }
3994 };
3995
3996 void prepare_work() {
3997 G1PrepareFreeCollectionSetClosure cl(_work_items);
3998 _collection_set->iterate(&cl);
3999 }
4000
4001 void complete_work() {
4002 _cl.complete_work();
4003
4004 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4005 policy->record_max_rs_lengths(_rs_lengths);
4006 policy->cset_regions_freed();
4007 }
4008 public:
4009 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4010 AbstractGangTask("G1 Free Collection Set"),
4011 _collection_set(collection_set),
4012 _cl(evacuation_info, surviving_young_words),
4013 _surviving_young_words(surviving_young_words),
4014 _rs_lengths(0),
4015 _serial_work_claim(0),
4016 _parallel_work_claim(0),
4017 _num_work_items(collection_set->region_length()),
4018 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4019 prepare_work();
4020 }
4021
4022 ~G1FreeCollectionSetTask() {
4023 complete_work();
4024 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4025 }
4026
4027 // Chunk size for work distribution. The chosen value has been determined experimentally
4028 // to be a good tradeoff between overhead and achievable parallelism.
4029 static uint chunk_size() { return 32; }
4030
4031 virtual void work(uint worker_id) {
4032 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4033
4034 // Claim serial work.
4035 if (_serial_work_claim == 0) {
4036 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4037 if (value == 0) {
4038 double serial_time = os::elapsedTime();
4039 do_serial_work();
4040 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4041 }
4042 }
4043
4044 // Start parallel work.
4045 double young_time = 0.0;
4046 bool has_young_time = false;
4047 double non_young_time = 0.0;
4048 bool has_non_young_time = false;
4049
4050 while (true) {
4051 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4052 size_t cur = end - chunk_size();
4053
4054 if (cur >= _num_work_items) {
4055 break;
4056 }
4057
4058 EventGCPhaseParallel event;
4059 double start_time = os::elapsedTime();
4060
4061 end = MIN2(end, _num_work_items);
4062
4063 for (; cur < end; cur++) {
4064 bool is_young = _work_items[cur].is_young;
4065
4066 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4067
4068 double end_time = os::elapsedTime();
4069 double time_taken = end_time - start_time;
4070 if (is_young) {
4071 young_time += time_taken;
4072 has_young_time = true;
4073 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4074 } else {
4075 non_young_time += time_taken;
4076 has_non_young_time = true;
4077 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4078 }
4079 start_time = end_time;
4080 }
4081 }
4082
4083 if (has_young_time) {
4084 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4085 }
4086 if (has_non_young_time) {
4087 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4088 }
4089 }
4090 };
4091
4092 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4093 _eden.clear();
4094
4095 double free_cset_start_time = os::elapsedTime();
4096
4097 {
4098 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4099 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4100
4101 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4102
4103 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4104 cl.name(),
4105 num_workers,
4106 _collection_set.region_length());
4107 workers()->run_task(&cl, num_workers);
4108 }
4109 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4110
4111 collection_set->clear();
4112 }
4113
4114 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4115 private:
4116 FreeRegionList* _free_region_list;
4117 HeapRegionSet* _proxy_set;
4118 uint _humongous_objects_reclaimed;
4119 uint _humongous_regions_reclaimed;
4120 size_t _freed_bytes;
4121 public:
4122
4123 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4124 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4125 }
4126
4127 virtual bool do_heap_region(HeapRegion* r) {
4128 if (!r->is_starts_humongous()) {
4129 return false;
4130 }
4131
4132 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4133
4134 oop obj = (oop)r->bottom();
4135 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4136
4137 // The following checks whether the humongous object is live are sufficient.
4138 // The main additional check (in addition to having a reference from the roots
4139 // or the young gen) is whether the humongous object has a remembered set entry.
4140 //
4141 // A humongous object cannot be live if there is no remembered set for it
4142 // because:
4143 // - there can be no references from within humongous starts regions referencing
4144 // the object because we never allocate other objects into them.
4145 // (I.e. there are no intra-region references that may be missed by the
4146 // remembered set)
4147 // - as soon there is a remembered set entry to the humongous starts region
4148 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4149 // until the end of a concurrent mark.
4150 //
4151 // It is not required to check whether the object has been found dead by marking
4152 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4153 // all objects allocated during that time are considered live.
4154 // SATB marking is even more conservative than the remembered set.
4155 // So if at this point in the collection there is no remembered set entry,
4156 // nobody has a reference to it.
4157 // At the start of collection we flush all refinement logs, and remembered sets
4158 // are completely up-to-date wrt to references to the humongous object.
4159 //
4160 // Other implementation considerations:
4161 // - never consider object arrays at this time because they would pose
4162 // considerable effort for cleaning up the the remembered sets. This is
4163 // required because stale remembered sets might reference locations that
4164 // are currently allocated into.
4165 uint region_idx = r->hrm_index();
4166 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4167 !r->rem_set()->is_empty()) {
4168 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",
4169 region_idx,
4170 (size_t)obj->size() * HeapWordSize,
4171 p2i(r->bottom()),
4172 r->rem_set()->occupied(),
4173 r->rem_set()->strong_code_roots_list_length(),
4174 next_bitmap->is_marked(r->bottom()),
4175 g1h->is_humongous_reclaim_candidate(region_idx),
4176 obj->is_typeArray()
4177 );
4178 return false;
4179 }
4180
4181 guarantee(obj->is_typeArray(),
4182 "Only eagerly reclaiming type arrays is supported, but the object "
4183 PTR_FORMAT " is not.", p2i(r->bottom()));
4184
4185 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",
4186 region_idx,
4187 (size_t)obj->size() * HeapWordSize,
4188 p2i(r->bottom()),
4189 r->rem_set()->occupied(),
4190 r->rem_set()->strong_code_roots_list_length(),
4191 next_bitmap->is_marked(r->bottom()),
4192 g1h->is_humongous_reclaim_candidate(region_idx),
4193 obj->is_typeArray()
4194 );
4195
4196 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4197 cm->humongous_object_eagerly_reclaimed(r);
4198 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4199 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4200 region_idx,
4201 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4202 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4203 _humongous_objects_reclaimed++;
4204 do {
4205 HeapRegion* next = g1h->next_region_in_humongous(r);
4206 _freed_bytes += r->used();
4207 r->set_containing_set(NULL);
4208 _humongous_regions_reclaimed++;
4209 g1h->free_humongous_region(r, _free_region_list);
4210 r = next;
4211 } while (r != NULL);
4212
4213 return false;
4214 }
4215
4216 uint humongous_objects_reclaimed() {
4217 return _humongous_objects_reclaimed;
4218 }
4219
4220 uint humongous_regions_reclaimed() {
4221 return _humongous_regions_reclaimed;
4222 }
4223
4224 size_t bytes_freed() const {
4225 return _freed_bytes;
4226 }
4227 };
4228
4229 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4230 assert_at_safepoint_on_vm_thread();
4231
4232 if (!G1EagerReclaimHumongousObjects ||
4233 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4234 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4235 return;
4236 }
4237
4238 double start_time = os::elapsedTime();
4239
4240 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4241
4242 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4243 heap_region_iterate(&cl);
4244
4245 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4246
4247 G1HRPrinter* hrp = hr_printer();
4248 if (hrp->is_active()) {
4249 FreeRegionListIterator iter(&local_cleanup_list);
4250 while (iter.more_available()) {
4251 HeapRegion* hr = iter.get_next();
4252 hrp->cleanup(hr);
4253 }
4254 }
4255
4256 prepend_to_freelist(&local_cleanup_list);
4257 decrement_summary_bytes(cl.bytes_freed());
4258
4259 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4260 cl.humongous_objects_reclaimed());
4261 }
4262
4263 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4264 public:
4265 virtual bool do_heap_region(HeapRegion* r) {
4266 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4267 G1CollectedHeap::heap()->clear_in_cset(r);
4268 r->set_young_index_in_cset(-1);
4269 return false;
4270 }
4271 };
4272
4273 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4274 G1AbandonCollectionSetClosure cl;
4275 collection_set->iterate(&cl);
4276
4277 collection_set->clear();
4278 collection_set->stop_incremental_building();
4279 }
4280
4281 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4282 return _allocator->is_retained_old_region(hr);
4283 }
4284
4285 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4286 _eden.add(hr);
4287 _g1_policy->set_region_eden(hr);
4288 }
4289
4290 #ifdef ASSERT
4291
4292 class NoYoungRegionsClosure: public HeapRegionClosure {
4293 private:
4294 bool _success;
4295 public:
4296 NoYoungRegionsClosure() : _success(true) { }
4297 bool do_heap_region(HeapRegion* r) {
4298 if (r->is_young()) {
4299 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4300 p2i(r->bottom()), p2i(r->end()));
4301 _success = false;
4302 }
4303 return false;
4304 }
4305 bool success() { return _success; }
4306 };
4307
4308 bool G1CollectedHeap::check_young_list_empty() {
4309 bool ret = (young_regions_count() == 0);
4310
4311 NoYoungRegionsClosure closure;
4312 heap_region_iterate(&closure);
4313 ret = ret && closure.success();
4314
4315 return ret;
4316 }
4317
4318 #endif // ASSERT
4319
4320 class TearDownRegionSetsClosure : public HeapRegionClosure {
4321 HeapRegionSet *_old_set;
4322
4323 public:
4324 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4325
4326 bool do_heap_region(HeapRegion* r) {
4327 if (r->is_old()) {
4328 _old_set->remove(r);
4329 } else if(r->is_young()) {
4330 r->uninstall_surv_rate_group();
4331 } else {
4332 // We ignore free regions, we'll empty the free list afterwards.
4333 // We ignore humongous and archive regions, we're not tearing down these
4334 // sets.
4335 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4336 "it cannot be another type");
4337 }
4338 return false;
4339 }
4340
4341 ~TearDownRegionSetsClosure() {
4342 assert(_old_set->is_empty(), "post-condition");
4343 }
4344 };
4345
4346 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4347 assert_at_safepoint_on_vm_thread();
4348
4349 if (!free_list_only) {
4350 TearDownRegionSetsClosure cl(&_old_set);
4351 heap_region_iterate(&cl);
4352
4353 // Note that emptying the _young_list is postponed and instead done as
4354 // the first step when rebuilding the regions sets again. The reason for
4355 // this is that during a full GC string deduplication needs to know if
4356 // a collected region was young or old when the full GC was initiated.
4357 }
4358 _hrm.remove_all_free_regions();
4359 }
4360
4361 void G1CollectedHeap::increase_used(size_t bytes) {
4362 _summary_bytes_used += bytes;
4363 }
4364
4365 void G1CollectedHeap::decrease_used(size_t bytes) {
4366 assert(_summary_bytes_used >= bytes,
4367 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4368 _summary_bytes_used, bytes);
4369 _summary_bytes_used -= bytes;
4370 }
4371
4372 void G1CollectedHeap::set_used(size_t bytes) {
4373 _summary_bytes_used = bytes;
4374 }
4375
4376 class RebuildRegionSetsClosure : public HeapRegionClosure {
4377 private:
4378 bool _free_list_only;
4379
4380 HeapRegionSet* _old_set;
4381 HeapRegionManager* _hrm;
4382
4383 size_t _total_used;
4384
4385 public:
4386 RebuildRegionSetsClosure(bool free_list_only,
4387 HeapRegionSet* old_set,
4388 HeapRegionManager* hrm) :
4389 _free_list_only(free_list_only),
4390 _old_set(old_set), _hrm(hrm), _total_used(0) {
4391 assert(_hrm->num_free_regions() == 0, "pre-condition");
4392 if (!free_list_only) {
4393 assert(_old_set->is_empty(), "pre-condition");
4394 }
4395 }
4396
4397 bool do_heap_region(HeapRegion* r) {
4398 // After full GC, no region should have a remembered set.
4399 r->rem_set()->clear(true);
4400 if (r->is_empty()) {
4401 // Add free regions to the free list
4402 r->set_free();
4403 _hrm->insert_into_free_list(r);
4404 } else if (!_free_list_only) {
4405
4406 if (r->is_archive() || r->is_humongous()) {
4407 // We ignore archive and humongous regions. We left these sets unchanged.
4408 } else {
4409 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4410 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4411 r->move_to_old();
4412 _old_set->add(r);
4413 }
4414 _total_used += r->used();
4415 }
4416
4417 return false;
4418 }
4419
4420 size_t total_used() {
4421 return _total_used;
4422 }
4423 };
4424
4425 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4426 assert_at_safepoint_on_vm_thread();
4427
4428 if (!free_list_only) {
4429 _eden.clear();
4430 _survivor.clear();
4431 }
4432
4433 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4434 heap_region_iterate(&cl);
4435
4436 if (!free_list_only) {
4437 set_used(cl.total_used());
4438 if (_archive_allocator != NULL) {
4439 _archive_allocator->clear_used();
4440 }
4441 }
4442 assert(used_unlocked() == recalculate_used(),
4443 "inconsistent used_unlocked(), "
4444 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4445 used_unlocked(), recalculate_used());
4446 }
4447
4448 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4449 HeapRegion* hr = heap_region_containing(p);
4450 return hr->is_in(p);
4451 }
4452
4453 // Methods for the mutator alloc region
4454
4455 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4456 bool force) {
4457 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4458 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4459 if (force || should_allocate) {
4460 HeapRegion* new_alloc_region = new_region(word_size,
4461 false /* is_old */,
4462 false /* do_expand */);
4463 if (new_alloc_region != NULL) {
4464 set_region_short_lived_locked(new_alloc_region);
4465 _hr_printer.alloc(new_alloc_region, !should_allocate);
4466 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4467 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4468 return new_alloc_region;
4469 }
4470 }
4471 return NULL;
4472 }
4473
4474 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4475 size_t allocated_bytes) {
4476 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4477 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4478
4479 collection_set()->add_eden_region(alloc_region);
4480 increase_used(allocated_bytes);
4481 _hr_printer.retire(alloc_region);
4482 // We update the eden sizes here, when the region is retired,
4483 // instead of when it's allocated, since this is the point that its
4484 // used space has been recorded in _summary_bytes_used.
4485 g1mm()->update_eden_size();
4486 }
4487
4488 // Methods for the GC alloc regions
4489
4490 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4491 if (dest.is_old()) {
4492 return true;
4493 } else {
4494 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4495 }
4496 }
4497
4498 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4499 assert(FreeList_lock->owned_by_self(), "pre-condition");
4500
4501 if (!has_more_regions(dest)) {
4502 return NULL;
4503 }
4504
4505 const bool is_survivor = dest.is_young();
4506
4507 HeapRegion* new_alloc_region = new_region(word_size,
4508 !is_survivor,
4509 true /* do_expand */);
4510 if (new_alloc_region != NULL) {
4511 if (is_survivor) {
4512 new_alloc_region->set_survivor();
4513 _survivor.add(new_alloc_region);
4514 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4515 } else {
4516 new_alloc_region->set_old();
4517 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4518 }
4519 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4520 _hr_printer.alloc(new_alloc_region);
4521 bool during_im = collector_state()->in_initial_mark_gc();
4522 new_alloc_region->note_start_of_copying(during_im);
4523 return new_alloc_region;
4524 }
4525 return NULL;
4526 }
4527
4528 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4529 size_t allocated_bytes,
4530 InCSetState dest) {
4531 bool during_im = collector_state()->in_initial_mark_gc();
4532 alloc_region->note_end_of_copying(during_im);
4533 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4534 if (dest.is_old()) {
4535 old_set_add(alloc_region);
4536 }
4537 _hr_printer.retire(alloc_region);
4538 }
4539
4540 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4541 bool expanded = false;
4542 uint index = _hrm.find_highest_free(&expanded);
4543
4544 if (index != G1_NO_HRM_INDEX) {
4545 if (expanded) {
4546 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4547 HeapRegion::GrainWords * HeapWordSize);
4548 }
4549 _hrm.allocate_free_regions_starting_at(index, 1);
4550 return region_at(index);
4551 }
4552 return NULL;
4553 }
4554
4555 // Optimized nmethod scanning
4556
4557 class RegisterNMethodOopClosure: public OopClosure {
4558 G1CollectedHeap* _g1h;
4559 nmethod* _nm;
4560
4561 template <class T> void do_oop_work(T* p) {
4562 T heap_oop = RawAccess<>::oop_load(p);
4563 if (!CompressedOops::is_null(heap_oop)) {
4564 oop obj = CompressedOops::decode_not_null(heap_oop);
4565 HeapRegion* hr = _g1h->heap_region_containing(obj);
4566 assert(!hr->is_continues_humongous(),
4567 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4568 " starting at " HR_FORMAT,
4569 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4570
4571 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4572 hr->add_strong_code_root_locked(_nm);
4573 }
4574 }
4575
4576 public:
4577 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4578 _g1h(g1h), _nm(nm) {}
4579
4580 void do_oop(oop* p) { do_oop_work(p); }
4581 void do_oop(narrowOop* p) { do_oop_work(p); }
4582 };
4583
4584 class UnregisterNMethodOopClosure: public OopClosure {
4585 G1CollectedHeap* _g1h;
4586 nmethod* _nm;
4587
4588 template <class T> void do_oop_work(T* p) {
4589 T heap_oop = RawAccess<>::oop_load(p);
4590 if (!CompressedOops::is_null(heap_oop)) {
4591 oop obj = CompressedOops::decode_not_null(heap_oop);
4592 HeapRegion* hr = _g1h->heap_region_containing(obj);
4593 assert(!hr->is_continues_humongous(),
4594 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4595 " starting at " HR_FORMAT,
4596 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4597
4598 hr->remove_strong_code_root(_nm);
4599 }
4600 }
4601
4602 public:
4603 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4604 _g1h(g1h), _nm(nm) {}
4605
4606 void do_oop(oop* p) { do_oop_work(p); }
4607 void do_oop(narrowOop* p) { do_oop_work(p); }
4608 };
4609
4610 // Returns true if the reference points to an object that
4611 // can move in an incremental collection.
4612 bool G1CollectedHeap::is_scavengable(oop obj) {
4613 HeapRegion* hr = heap_region_containing(obj);
4614 return !hr->is_pinned();
4615 }
4616
4617 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4618 guarantee(nm != NULL, "sanity");
4619 RegisterNMethodOopClosure reg_cl(this, nm);
4620 nm->oops_do(®_cl);
4621 }
4622
4623 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4624 guarantee(nm != NULL, "sanity");
4625 UnregisterNMethodOopClosure reg_cl(this, nm);
4626 nm->oops_do(®_cl, true);
4627 }
4628
4629 void G1CollectedHeap::purge_code_root_memory() {
4630 double purge_start = os::elapsedTime();
4631 G1CodeRootSet::purge();
4632 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4633 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4634 }
4635
4636 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4637 G1CollectedHeap* _g1h;
4638
4639 public:
4640 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4641 _g1h(g1h) {}
4642
4643 void do_code_blob(CodeBlob* cb) {
4644 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4645 if (nm == NULL) {
4646 return;
4647 }
4648
4649 if (ScavengeRootsInCode) {
4650 _g1h->register_nmethod(nm);
4651 }
4652 }
4653 };
4654
4655 void G1CollectedHeap::rebuild_strong_code_roots() {
4656 RebuildStrongCodeRootClosure blob_cl(this);
4657 CodeCache::blobs_do(&blob_cl);
4658 }
4659
4660 void G1CollectedHeap::initialize_serviceability() {
4661 _g1mm->initialize_serviceability();
4662 }
4663
4664 MemoryUsage G1CollectedHeap::memory_usage() {
4665 return _g1mm->memory_usage();
4666 }
4667
4668 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4669 return _g1mm->memory_managers();
4670 }
4671
4672 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4673 return _g1mm->memory_pools();
4674 }