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/gcBehaviours.hpp"
66 #include "gc/shared/gcHeapSummary.hpp"
67 #include "gc/shared/gcId.hpp"
68 #include "gc/shared/gcLocker.hpp"
69 #include "gc/shared/gcTimer.hpp"
70 #include "gc/shared/gcTrace.hpp"
71 #include "gc/shared/gcTraceTime.inline.hpp"
72 #include "gc/shared/generationSpec.hpp"
73 #include "gc/shared/isGCActiveMark.hpp"
74 #include "gc/shared/oopStorageParState.hpp"
75 #include "gc/shared/parallelCleaning.hpp"
76 #include "gc/shared/preservedMarks.inline.hpp"
77 #include "gc/shared/suspendibleThreadSet.hpp"
78 #include "gc/shared/referenceProcessor.inline.hpp"
79 #include "gc/shared/taskqueue.inline.hpp"
80 #include "gc/shared/weakProcessor.inline.hpp"
81 #include "logging/log.hpp"
82 #include "memory/allocation.hpp"
83 #include "memory/iterator.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(G1ArchiveAllocator::is_archived_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 hrm()->prepare_for_full_collection_start();
1030 }
1031
1032 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1033 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1034 assert(used() == recalculate_used(), "Should be equal");
1035 _verifier->verify_region_sets_optional();
1036 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1037 _verifier->check_bitmaps("Full GC Start");
1038 }
1039
1040 void G1CollectedHeap::prepare_heap_for_mutators() {
1041 hrm()->prepare_for_full_collection_end();
1042
1043 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1044 ClassLoaderDataGraph::purge();
1045 MetaspaceUtils::verify_metrics();
1046
1047 // Prepare heap for normal collections.
1048 assert(num_free_regions() == 0, "we should not have added any free regions");
1049 rebuild_region_sets(false /* free_list_only */);
1050 abort_refinement();
1051 resize_heap_if_necessary();
1052
1053 // Rebuild the strong code root lists for each region
1054 rebuild_strong_code_roots();
1055
1056 // Purge code root memory
1057 purge_code_root_memory();
1058
1059 // Start a new incremental collection set for the next pause
1060 start_new_collection_set();
1061
1062 _allocator->init_mutator_alloc_region();
1063
1064 // Post collection state updates.
1065 MetaspaceGC::compute_new_size();
1066 }
1067
1068 void G1CollectedHeap::abort_refinement() {
1069 if (_hot_card_cache->use_cache()) {
1070 _hot_card_cache->reset_hot_cache();
1071 }
1072
1073 // Discard all remembered set updates.
1074 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1075 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1076 }
1077
1078 void G1CollectedHeap::verify_after_full_collection() {
1079 _hrm->verify_optional();
1080 _verifier->verify_region_sets_optional();
1081 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1082 // Clear the previous marking bitmap, if needed for bitmap verification.
1083 // Note we cannot do this when we clear the next marking bitmap in
1084 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1085 // objects marked during a full GC against the previous bitmap.
1086 // But we need to clear it before calling check_bitmaps below since
1087 // the full GC has compacted objects and updated TAMS but not updated
1088 // the prev bitmap.
1089 if (G1VerifyBitmaps) {
1090 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1091 _cm->clear_prev_bitmap(workers());
1092 }
1093 // This call implicitly verifies that the next bitmap is clear after Full GC.
1094 _verifier->check_bitmaps("Full GC End");
1095
1096 // At this point there should be no regions in the
1097 // entire heap tagged as young.
1098 assert(check_young_list_empty(), "young list should be empty at this point");
1099
1100 // Note: since we've just done a full GC, concurrent
1101 // marking is no longer active. Therefore we need not
1102 // re-enable reference discovery for the CM ref processor.
1103 // That will be done at the start of the next marking cycle.
1104 // We also know that the STW processor should no longer
1105 // discover any new references.
1106 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1107 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1108 _ref_processor_stw->verify_no_references_recorded();
1109 _ref_processor_cm->verify_no_references_recorded();
1110 }
1111
1112 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1113 // Post collection logging.
1114 // We should do this after we potentially resize the heap so
1115 // that all the COMMIT / UNCOMMIT events are generated before
1116 // the compaction events.
1117 print_hrm_post_compaction();
1118 heap_transition->print();
1119 print_heap_after_gc();
1120 print_heap_regions();
1121 #ifdef TRACESPINNING
1122 ParallelTaskTerminator::print_termination_counts();
1123 #endif
1124 }
1125
1126 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1127 bool clear_all_soft_refs) {
1128 assert_at_safepoint_on_vm_thread();
1129
1130 if (GCLocker::check_active_before_gc()) {
1131 // Full GC was not completed.
1132 return false;
1133 }
1134
1135 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1136 soft_ref_policy()->should_clear_all_soft_refs();
1137
1138 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1139 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1140
1141 collector.prepare_collection();
1142 collector.collect();
1143 collector.complete_collection();
1144
1145 // Full collection was successfully completed.
1146 return true;
1147 }
1148
1149 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1150 // Currently, there is no facility in the do_full_collection(bool) API to notify
1151 // the caller that the collection did not succeed (e.g., because it was locked
1152 // out by the GC locker). So, right now, we'll ignore the return value.
1153 bool dummy = do_full_collection(true, /* explicit_gc */
1154 clear_all_soft_refs);
1155 }
1156
1157 void G1CollectedHeap::resize_heap_if_necessary() {
1158 // Capacity, free and used after the GC counted as full regions to
1159 // include the waste in the following calculations.
1160 const size_t capacity_after_gc = capacity();
1161 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1162
1163 // This is enforced in arguments.cpp.
1164 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1165 "otherwise the code below doesn't make sense");
1166
1167 // We don't have floating point command-line arguments
1168 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1169 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1170 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1171 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1172
1173 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1174 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1175
1176 // We have to be careful here as these two calculations can overflow
1177 // 32-bit size_t's.
1178 double used_after_gc_d = (double) used_after_gc;
1179 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1180 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1181
1182 // Let's make sure that they are both under the max heap size, which
1183 // by default will make them fit into a size_t.
1184 double desired_capacity_upper_bound = (double) max_heap_size;
1185 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1186 desired_capacity_upper_bound);
1187 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1188 desired_capacity_upper_bound);
1189
1190 // We can now safely turn them into size_t's.
1191 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1192 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1193
1194 // This assert only makes sense here, before we adjust them
1195 // with respect to the min and max heap size.
1196 assert(minimum_desired_capacity <= maximum_desired_capacity,
1197 "minimum_desired_capacity = " SIZE_FORMAT ", "
1198 "maximum_desired_capacity = " SIZE_FORMAT,
1199 minimum_desired_capacity, maximum_desired_capacity);
1200
1201 // Should not be greater than the heap max size. No need to adjust
1202 // it with respect to the heap min size as it's a lower bound (i.e.,
1203 // we'll try to make the capacity larger than it, not smaller).
1204 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1205 // Should not be less than the heap min size. No need to adjust it
1206 // with respect to the heap max size as it's an upper bound (i.e.,
1207 // we'll try to make the capacity smaller than it, not greater).
1208 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1209
1210 if (capacity_after_gc < minimum_desired_capacity) {
1211 // Don't expand unless it's significant
1212 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1213
1214 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1215 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1216 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1217 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1218
1219 expand(expand_bytes, _workers);
1220
1221 // No expansion, now see if we want to shrink
1222 } else if (capacity_after_gc > maximum_desired_capacity) {
1223 // Capacity too large, compute shrinking size
1224 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1225
1226 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1227 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1228 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1229 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1230
1231 shrink(shrink_bytes);
1232 }
1233 }
1234
1235 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1236 bool do_gc,
1237 bool clear_all_soft_refs,
1238 bool expect_null_mutator_alloc_region,
1239 bool* gc_succeeded) {
1240 *gc_succeeded = true;
1241 // Let's attempt the allocation first.
1242 HeapWord* result =
1243 attempt_allocation_at_safepoint(word_size,
1244 expect_null_mutator_alloc_region);
1245 if (result != NULL) {
1246 return result;
1247 }
1248
1249 // In a G1 heap, we're supposed to keep allocation from failing by
1250 // incremental pauses. Therefore, at least for now, we'll favor
1251 // expansion over collection. (This might change in the future if we can
1252 // do something smarter than full collection to satisfy a failed alloc.)
1253 result = expand_and_allocate(word_size);
1254 if (result != NULL) {
1255 return result;
1256 }
1257
1258 if (do_gc) {
1259 // Expansion didn't work, we'll try to do a Full GC.
1260 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1261 clear_all_soft_refs);
1262 }
1263
1264 return NULL;
1265 }
1266
1267 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1268 bool* succeeded) {
1269 assert_at_safepoint_on_vm_thread();
1270
1271 // Attempts to allocate followed by Full GC.
1272 HeapWord* result =
1273 satisfy_failed_allocation_helper(word_size,
1274 true, /* do_gc */
1275 false, /* clear_all_soft_refs */
1276 false, /* expect_null_mutator_alloc_region */
1277 succeeded);
1278
1279 if (result != NULL || !*succeeded) {
1280 return result;
1281 }
1282
1283 // Attempts to allocate followed by Full GC that will collect all soft references.
1284 result = satisfy_failed_allocation_helper(word_size,
1285 true, /* do_gc */
1286 true, /* clear_all_soft_refs */
1287 true, /* expect_null_mutator_alloc_region */
1288 succeeded);
1289
1290 if (result != NULL || !*succeeded) {
1291 return result;
1292 }
1293
1294 // Attempts to allocate, no GC
1295 result = satisfy_failed_allocation_helper(word_size,
1296 false, /* do_gc */
1297 false, /* clear_all_soft_refs */
1298 true, /* expect_null_mutator_alloc_region */
1299 succeeded);
1300
1301 if (result != NULL) {
1302 return result;
1303 }
1304
1305 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1306 "Flag should have been handled and cleared prior to this point");
1307
1308 // What else? We might try synchronous finalization later. If the total
1309 // space available is large enough for the allocation, then a more
1310 // complete compaction phase than we've tried so far might be
1311 // appropriate.
1312 return NULL;
1313 }
1314
1315 // Attempting to expand the heap sufficiently
1316 // to support an allocation of the given "word_size". If
1317 // successful, perform the allocation and return the address of the
1318 // allocated block, or else "NULL".
1319
1320 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1321 assert_at_safepoint_on_vm_thread();
1322
1323 _verifier->verify_region_sets_optional();
1324
1325 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1326 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1327 word_size * HeapWordSize);
1328
1329
1330 if (expand(expand_bytes, _workers)) {
1331 _hrm->verify_optional();
1332 _verifier->verify_region_sets_optional();
1333 return attempt_allocation_at_safepoint(word_size,
1334 false /* expect_null_mutator_alloc_region */);
1335 }
1336 return NULL;
1337 }
1338
1339 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1340 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1341 aligned_expand_bytes = align_up(aligned_expand_bytes,
1342 HeapRegion::GrainBytes);
1343
1344 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1345 expand_bytes, aligned_expand_bytes);
1346
1347 if (is_maximal_no_gc()) {
1348 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1349 return false;
1350 }
1351
1352 double expand_heap_start_time_sec = os::elapsedTime();
1353 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1354 assert(regions_to_expand > 0, "Must expand by at least one region");
1355
1356 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1357 if (expand_time_ms != NULL) {
1358 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1359 }
1360
1361 if (expanded_by > 0) {
1362 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1363 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1364 g1_policy()->record_new_heap_size(num_regions());
1365 } else {
1366 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1367
1368 // The expansion of the virtual storage space was unsuccessful.
1369 // Let's see if it was because we ran out of swap.
1370 if (G1ExitOnExpansionFailure &&
1371 _hrm->available() >= regions_to_expand) {
1372 // We had head room...
1373 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1374 }
1375 }
1376 return regions_to_expand > 0;
1377 }
1378
1379 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1380 size_t aligned_shrink_bytes =
1381 ReservedSpace::page_align_size_down(shrink_bytes);
1382 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1383 HeapRegion::GrainBytes);
1384 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1385
1386 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1387 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1388
1389
1390 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",
1391 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1392 if (num_regions_removed > 0) {
1393 g1_policy()->record_new_heap_size(num_regions());
1394 } else {
1395 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1396 }
1397 }
1398
1399 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1400 _verifier->verify_region_sets_optional();
1401
1402 // We should only reach here at the end of a Full GC or during Remark which
1403 // means we should not not be holding to any GC alloc regions. The method
1404 // below will make sure of that and do any remaining clean up.
1405 _allocator->abandon_gc_alloc_regions();
1406
1407 // Instead of tearing down / rebuilding the free lists here, we
1408 // could instead use the remove_all_pending() method on free_list to
1409 // remove only the ones that we need to remove.
1410 tear_down_region_sets(true /* free_list_only */);
1411 shrink_helper(shrink_bytes);
1412 rebuild_region_sets(true /* free_list_only */);
1413
1414 _hrm->verify_optional();
1415 _verifier->verify_region_sets_optional();
1416 }
1417
1418 class OldRegionSetChecker : public HeapRegionSetChecker {
1419 public:
1420 void check_mt_safety() {
1421 // Master Old Set MT safety protocol:
1422 // (a) If we're at a safepoint, operations on the master old set
1423 // should be invoked:
1424 // - by the VM thread (which will serialize them), or
1425 // - by the GC workers while holding the FreeList_lock, if we're
1426 // at a safepoint for an evacuation pause (this lock is taken
1427 // anyway when an GC alloc region is retired so that a new one
1428 // is allocated from the free list), or
1429 // - by the GC workers while holding the OldSets_lock, if we're at a
1430 // safepoint for a cleanup pause.
1431 // (b) If we're not at a safepoint, operations on the master old set
1432 // should be invoked while holding the Heap_lock.
1433
1434 if (SafepointSynchronize::is_at_safepoint()) {
1435 guarantee(Thread::current()->is_VM_thread() ||
1436 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1437 "master old set MT safety protocol at a safepoint");
1438 } else {
1439 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1440 }
1441 }
1442 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1443 const char* get_description() { return "Old Regions"; }
1444 };
1445
1446 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1447 public:
1448 void check_mt_safety() {
1449 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1450 "May only change archive regions during initialization or safepoint.");
1451 }
1452 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1453 const char* get_description() { return "Archive Regions"; }
1454 };
1455
1456 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1457 public:
1458 void check_mt_safety() {
1459 // Humongous Set MT safety protocol:
1460 // (a) If we're at a safepoint, operations on the master humongous
1461 // set should be invoked by either the VM thread (which will
1462 // serialize them) or by the GC workers while holding the
1463 // OldSets_lock.
1464 // (b) If we're not at a safepoint, operations on the master
1465 // humongous set should be invoked while holding the Heap_lock.
1466
1467 if (SafepointSynchronize::is_at_safepoint()) {
1468 guarantee(Thread::current()->is_VM_thread() ||
1469 OldSets_lock->owned_by_self(),
1470 "master humongous set MT safety protocol at a safepoint");
1471 } else {
1472 guarantee(Heap_lock->owned_by_self(),
1473 "master humongous set MT safety protocol outside a safepoint");
1474 }
1475 }
1476 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1477 const char* get_description() { return "Humongous Regions"; }
1478 };
1479
1480 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1481 CollectedHeap(),
1482 _young_gen_sampling_thread(NULL),
1483 _workers(NULL),
1484 _collector_policy(collector_policy),
1485 _card_table(NULL),
1486 _soft_ref_policy(),
1487 _old_set("Old Region Set", new OldRegionSetChecker()),
1488 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1489 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1490 _bot(NULL),
1491 _listener(),
1492 _hrm(NULL),
1493 _is_hetero_heap(AllocateOldGenAt != NULL),
1494 _allocator(NULL),
1495 _verifier(NULL),
1496 _summary_bytes_used(0),
1497 _archive_allocator(NULL),
1498 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1499 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1500 _expand_heap_after_alloc_failure(true),
1501 _g1mm(NULL),
1502 _humongous_reclaim_candidates(),
1503 _has_humongous_reclaim_candidates(false),
1504 _hr_printer(),
1505 _collector_state(),
1506 _old_marking_cycles_started(0),
1507 _old_marking_cycles_completed(0),
1508 _eden(),
1509 _survivor(),
1510 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1511 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1512 _g1_policy(new G1Policy(_gc_timer_stw)),
1513 _heap_sizing_policy(NULL),
1514 _collection_set(this, _g1_policy),
1515 _hot_card_cache(NULL),
1516 _g1_rem_set(NULL),
1517 _dirty_card_queue_set(false),
1518 _cm(NULL),
1519 _cm_thread(NULL),
1520 _cr(NULL),
1521 _task_queues(NULL),
1522 _evacuation_failed(false),
1523 _evacuation_failed_info_array(NULL),
1524 _preserved_marks_set(true /* in_c_heap */),
1525 #ifndef PRODUCT
1526 _evacuation_failure_alot_for_current_gc(false),
1527 _evacuation_failure_alot_gc_number(0),
1528 _evacuation_failure_alot_count(0),
1529 #endif
1530 _ref_processor_stw(NULL),
1531 _is_alive_closure_stw(this),
1532 _is_subject_to_discovery_stw(this),
1533 _ref_processor_cm(NULL),
1534 _is_alive_closure_cm(this),
1535 _is_subject_to_discovery_cm(this),
1536 _in_cset_fast_test() {
1537
1538 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1539 true /* are_GC_task_threads */,
1540 false /* are_ConcurrentGC_threads */);
1541 _workers->initialize_workers();
1542 _verifier = new G1HeapVerifier(this);
1543
1544 _allocator = new G1Allocator(this);
1545
1546 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1547
1548 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1549
1550 // Override the default _filler_array_max_size so that no humongous filler
1551 // objects are created.
1552 _filler_array_max_size = _humongous_object_threshold_in_words;
1553
1554 uint n_queues = ParallelGCThreads;
1555 _task_queues = new RefToScanQueueSet(n_queues);
1556
1557 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1558
1559 for (uint i = 0; i < n_queues; i++) {
1560 RefToScanQueue* q = new RefToScanQueue();
1561 q->initialize();
1562 _task_queues->register_queue(i, q);
1563 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1564 }
1565
1566 // Initialize the G1EvacuationFailureALot counters and flags.
1567 NOT_PRODUCT(reset_evacuation_should_fail();)
1568
1569 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1570 }
1571
1572 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1573 size_t size,
1574 size_t translation_factor) {
1575 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1576 // Allocate a new reserved space, preferring to use large pages.
1577 ReservedSpace rs(size, preferred_page_size);
1578 G1RegionToSpaceMapper* result =
1579 G1RegionToSpaceMapper::create_mapper(rs,
1580 size,
1581 rs.alignment(),
1582 HeapRegion::GrainBytes,
1583 translation_factor,
1584 mtGC);
1585
1586 os::trace_page_sizes_for_requested_size(description,
1587 size,
1588 preferred_page_size,
1589 rs.alignment(),
1590 rs.base(),
1591 rs.size());
1592
1593 return result;
1594 }
1595
1596 jint G1CollectedHeap::initialize_concurrent_refinement() {
1597 jint ecode = JNI_OK;
1598 _cr = G1ConcurrentRefine::create(&ecode);
1599 return ecode;
1600 }
1601
1602 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1603 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1604 if (_young_gen_sampling_thread->osthread() == NULL) {
1605 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1606 return JNI_ENOMEM;
1607 }
1608 return JNI_OK;
1609 }
1610
1611 jint G1CollectedHeap::initialize() {
1612 os::enable_vtime();
1613
1614 // Necessary to satisfy locking discipline assertions.
1615
1616 MutexLocker x(Heap_lock);
1617
1618 // While there are no constraints in the GC code that HeapWordSize
1619 // be any particular value, there are multiple other areas in the
1620 // system which believe this to be true (e.g. oop->object_size in some
1621 // cases incorrectly returns the size in wordSize units rather than
1622 // HeapWordSize).
1623 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1624
1625 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1626 size_t max_byte_size = g1_collector_policy()->heap_reservation_size_bytes();
1627 size_t heap_alignment = collector_policy()->heap_alignment();
1628
1629 // Ensure that the sizes are properly aligned.
1630 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1631 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1632 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1633
1634 // Reserve the maximum.
1635
1636 // When compressed oops are enabled, the preferred heap base
1637 // is calculated by subtracting the requested size from the
1638 // 32Gb boundary and using the result as the base address for
1639 // heap reservation. If the requested size is not aligned to
1640 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1641 // into the ReservedHeapSpace constructor) then the actual
1642 // base of the reserved heap may end up differing from the
1643 // address that was requested (i.e. the preferred heap base).
1644 // If this happens then we could end up using a non-optimal
1645 // compressed oops mode.
1646
1647 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1648 heap_alignment);
1649
1650 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1651
1652 // Create the barrier set for the entire reserved region.
1653 G1CardTable* ct = new G1CardTable(reserved_region());
1654 ct->initialize();
1655 G1BarrierSet* bs = new G1BarrierSet(ct);
1656 bs->initialize();
1657 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1658 BarrierSet::set_barrier_set(bs);
1659 _card_table = ct;
1660
1661 G1BarrierSet::satb_mark_queue_set().initialize(this,
1662 SATB_Q_CBL_mon,
1663 &bs->satb_mark_queue_buffer_allocator(),
1664 G1SATBProcessCompletedThreshold,
1665 G1SATBBufferEnqueueingThresholdPercent,
1666 Shared_SATB_Q_lock);
1667
1668 // process_completed_threshold and max_completed_queue are updated
1669 // later, based on the concurrent refinement object.
1670 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1671 &bs->dirty_card_queue_buffer_allocator(),
1672 -1, // temp. never trigger
1673 -1, // temp. no limit
1674 Shared_DirtyCardQ_lock,
1675 true); // init_free_ids
1676
1677 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1678 &bs->dirty_card_queue_buffer_allocator(),
1679 -1, // never trigger processing
1680 -1, // no limit on length
1681 Shared_DirtyCardQ_lock);
1682
1683 // Create the hot card cache.
1684 _hot_card_cache = new G1HotCardCache(this);
1685
1686 // Carve out the G1 part of the heap.
1687 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1688 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1689 G1RegionToSpaceMapper* heap_storage =
1690 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1691 g1_rs.size(),
1692 page_size,
1693 HeapRegion::GrainBytes,
1694 1,
1695 mtJavaHeap);
1696 if(heap_storage == NULL) {
1697 vm_shutdown_during_initialization("Could not initialize G1 heap");
1698 return JNI_ERR;
1699 }
1700
1701 os::trace_page_sizes("Heap",
1702 collector_policy()->min_heap_byte_size(),
1703 max_byte_size,
1704 page_size,
1705 heap_rs.base(),
1706 heap_rs.size());
1707 heap_storage->set_mapping_changed_listener(&_listener);
1708
1709 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1710 G1RegionToSpaceMapper* bot_storage =
1711 create_aux_memory_mapper("Block Offset Table",
1712 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1713 G1BlockOffsetTable::heap_map_factor());
1714
1715 G1RegionToSpaceMapper* cardtable_storage =
1716 create_aux_memory_mapper("Card Table",
1717 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1718 G1CardTable::heap_map_factor());
1719
1720 G1RegionToSpaceMapper* card_counts_storage =
1721 create_aux_memory_mapper("Card Counts Table",
1722 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1723 G1CardCounts::heap_map_factor());
1724
1725 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1726 G1RegionToSpaceMapper* prev_bitmap_storage =
1727 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1728 G1RegionToSpaceMapper* next_bitmap_storage =
1729 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1730
1731 _hrm = HeapRegionManager::create_manager(this, collector_policy());
1732
1733 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1734 _card_table->initialize(cardtable_storage);
1735 // Do later initialization work for concurrent refinement.
1736 _hot_card_cache->initialize(card_counts_storage);
1737
1738 // 6843694 - ensure that the maximum region index can fit
1739 // in the remembered set structures.
1740 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1741 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1742
1743 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1744 // start within the first card.
1745 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1746 // Also create a G1 rem set.
1747 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1748 _g1_rem_set->initialize(max_reserved_capacity(), max_regions());
1749
1750 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1751 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1752 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1753 "too many cards per region");
1754
1755 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1756
1757 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1758
1759 {
1760 HeapWord* start = _hrm->reserved().start();
1761 HeapWord* end = _hrm->reserved().end();
1762 size_t granularity = HeapRegion::GrainBytes;
1763
1764 _in_cset_fast_test.initialize(start, end, granularity);
1765 _humongous_reclaim_candidates.initialize(start, end, granularity);
1766 }
1767
1768 // Create the G1ConcurrentMark data structure and thread.
1769 // (Must do this late, so that "max_regions" is defined.)
1770 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1771 if (_cm == NULL || !_cm->completed_initialization()) {
1772 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1773 return JNI_ENOMEM;
1774 }
1775 _cm_thread = _cm->cm_thread();
1776
1777 // Now expand into the initial heap size.
1778 if (!expand(init_byte_size, _workers)) {
1779 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1780 return JNI_ENOMEM;
1781 }
1782
1783 // Perform any initialization actions delegated to the policy.
1784 g1_policy()->init(this, &_collection_set);
1785
1786 // Now we know the target length of young list. So adjust the heap to provision that many regions on dram.
1787 if (is_hetero_heap()) {
1788 static_cast<HeterogeneousHeapRegionManager*>(hrm())->adjust_dram_regions((uint)g1_policy()->young_list_target_length(), workers());
1789 }
1790
1791 jint ecode = initialize_concurrent_refinement();
1792 if (ecode != JNI_OK) {
1793 return ecode;
1794 }
1795
1796 ecode = initialize_young_gen_sampling_thread();
1797 if (ecode != JNI_OK) {
1798 return ecode;
1799 }
1800
1801 {
1802 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1803 dcqs.set_process_completed_threshold((int)concurrent_refine()->yellow_zone());
1804 dcqs.set_max_completed_queue((int)concurrent_refine()->red_zone());
1805 }
1806
1807 // Here we allocate the dummy HeapRegion that is required by the
1808 // G1AllocRegion class.
1809 HeapRegion* dummy_region = _hrm->get_dummy_region();
1810
1811 // We'll re-use the same region whether the alloc region will
1812 // require BOT updates or not and, if it doesn't, then a non-young
1813 // region will complain that it cannot support allocations without
1814 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1815 dummy_region->set_eden();
1816 // Make sure it's full.
1817 dummy_region->set_top(dummy_region->end());
1818 G1AllocRegion::setup(this, dummy_region);
1819
1820 _allocator->init_mutator_alloc_region();
1821
1822 // Do create of the monitoring and management support so that
1823 // values in the heap have been properly initialized.
1824 _g1mm = new G1MonitoringSupport(this);
1825
1826 G1StringDedup::initialize();
1827
1828 _preserved_marks_set.init(ParallelGCThreads);
1829
1830 _collection_set.initialize(max_regions());
1831
1832 return JNI_OK;
1833 }
1834
1835 void G1CollectedHeap::stop() {
1836 // Stop all concurrent threads. We do this to make sure these threads
1837 // do not continue to execute and access resources (e.g. logging)
1838 // that are destroyed during shutdown.
1839 _cr->stop();
1840 _young_gen_sampling_thread->stop();
1841 _cm_thread->stop();
1842 if (G1StringDedup::is_enabled()) {
1843 G1StringDedup::stop();
1844 }
1845 }
1846
1847 void G1CollectedHeap::safepoint_synchronize_begin() {
1848 SuspendibleThreadSet::synchronize();
1849 }
1850
1851 void G1CollectedHeap::safepoint_synchronize_end() {
1852 SuspendibleThreadSet::desynchronize();
1853 }
1854
1855 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1856 return HeapRegion::max_region_size();
1857 }
1858
1859 void G1CollectedHeap::post_initialize() {
1860 CollectedHeap::post_initialize();
1861 ref_processing_init();
1862 }
1863
1864 void G1CollectedHeap::ref_processing_init() {
1865 // Reference processing in G1 currently works as follows:
1866 //
1867 // * There are two reference processor instances. One is
1868 // used to record and process discovered references
1869 // during concurrent marking; the other is used to
1870 // record and process references during STW pauses
1871 // (both full and incremental).
1872 // * Both ref processors need to 'span' the entire heap as
1873 // the regions in the collection set may be dotted around.
1874 //
1875 // * For the concurrent marking ref processor:
1876 // * Reference discovery is enabled at initial marking.
1877 // * Reference discovery is disabled and the discovered
1878 // references processed etc during remarking.
1879 // * Reference discovery is MT (see below).
1880 // * Reference discovery requires a barrier (see below).
1881 // * Reference processing may or may not be MT
1882 // (depending on the value of ParallelRefProcEnabled
1883 // and ParallelGCThreads).
1884 // * A full GC disables reference discovery by the CM
1885 // ref processor and abandons any entries on it's
1886 // discovered lists.
1887 //
1888 // * For the STW processor:
1889 // * Non MT discovery is enabled at the start of a full GC.
1890 // * Processing and enqueueing during a full GC is non-MT.
1891 // * During a full GC, references are processed after marking.
1892 //
1893 // * Discovery (may or may not be MT) is enabled at the start
1894 // of an incremental evacuation pause.
1895 // * References are processed near the end of a STW evacuation pause.
1896 // * For both types of GC:
1897 // * Discovery is atomic - i.e. not concurrent.
1898 // * Reference discovery will not need a barrier.
1899
1900 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1901
1902 // Concurrent Mark ref processor
1903 _ref_processor_cm =
1904 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1905 mt_processing, // mt processing
1906 ParallelGCThreads, // degree of mt processing
1907 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1908 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1909 false, // Reference discovery is not atomic
1910 &_is_alive_closure_cm, // is alive closure
1911 true); // allow changes to number of processing threads
1912
1913 // STW ref processor
1914 _ref_processor_stw =
1915 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1916 mt_processing, // mt processing
1917 ParallelGCThreads, // degree of mt processing
1918 (ParallelGCThreads > 1), // mt discovery
1919 ParallelGCThreads, // degree of mt discovery
1920 true, // Reference discovery is atomic
1921 &_is_alive_closure_stw, // is alive closure
1922 true); // allow changes to number of processing threads
1923 }
1924
1925 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1926 return _collector_policy;
1927 }
1928
1929 G1CollectorPolicy* G1CollectedHeap::g1_collector_policy() const {
1930 return _collector_policy;
1931 }
1932
1933 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1934 return &_soft_ref_policy;
1935 }
1936
1937 size_t G1CollectedHeap::capacity() const {
1938 return _hrm->length() * HeapRegion::GrainBytes;
1939 }
1940
1941 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1942 return _hrm->total_free_bytes();
1943 }
1944
1945 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1946 _hot_card_cache->drain(cl, worker_i);
1947 }
1948
1949 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1950 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1951 size_t n_completed_buffers = 0;
1952 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1953 n_completed_buffers++;
1954 }
1955 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1956 dcqs.clear_n_completed_buffers();
1957 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1958 }
1959
1960 // Computes the sum of the storage used by the various regions.
1961 size_t G1CollectedHeap::used() const {
1962 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1963 if (_archive_allocator != NULL) {
1964 result += _archive_allocator->used();
1965 }
1966 return result;
1967 }
1968
1969 size_t G1CollectedHeap::used_unlocked() const {
1970 return _summary_bytes_used;
1971 }
1972
1973 class SumUsedClosure: public HeapRegionClosure {
1974 size_t _used;
1975 public:
1976 SumUsedClosure() : _used(0) {}
1977 bool do_heap_region(HeapRegion* r) {
1978 _used += r->used();
1979 return false;
1980 }
1981 size_t result() { return _used; }
1982 };
1983
1984 size_t G1CollectedHeap::recalculate_used() const {
1985 SumUsedClosure blk;
1986 heap_region_iterate(&blk);
1987 return blk.result();
1988 }
1989
1990 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1991 switch (cause) {
1992 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1993 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1994 case GCCause::_wb_conc_mark: return true;
1995 default : return false;
1996 }
1997 }
1998
1999 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2000 switch (cause) {
2001 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2002 case GCCause::_g1_humongous_allocation: return true;
2003 default: return is_user_requested_concurrent_full_gc(cause);
2004 }
2005 }
2006
2007 #ifndef PRODUCT
2008 void G1CollectedHeap::allocate_dummy_regions() {
2009 // Let's fill up most of the region
2010 size_t word_size = HeapRegion::GrainWords - 1024;
2011 // And as a result the region we'll allocate will be humongous.
2012 guarantee(is_humongous(word_size), "sanity");
2013
2014 // _filler_array_max_size is set to humongous object threshold
2015 // but temporarily change it to use CollectedHeap::fill_with_object().
2016 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2017
2018 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2019 // Let's use the existing mechanism for the allocation
2020 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2021 if (dummy_obj != NULL) {
2022 MemRegion mr(dummy_obj, word_size);
2023 CollectedHeap::fill_with_object(mr);
2024 } else {
2025 // If we can't allocate once, we probably cannot allocate
2026 // again. Let's get out of the loop.
2027 break;
2028 }
2029 }
2030 }
2031 #endif // !PRODUCT
2032
2033 void G1CollectedHeap::increment_old_marking_cycles_started() {
2034 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2035 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2036 "Wrong marking cycle count (started: %d, completed: %d)",
2037 _old_marking_cycles_started, _old_marking_cycles_completed);
2038
2039 _old_marking_cycles_started++;
2040 }
2041
2042 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2043 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2044
2045 // We assume that if concurrent == true, then the caller is a
2046 // concurrent thread that was joined the Suspendible Thread
2047 // Set. If there's ever a cheap way to check this, we should add an
2048 // assert here.
2049
2050 // Given that this method is called at the end of a Full GC or of a
2051 // concurrent cycle, and those can be nested (i.e., a Full GC can
2052 // interrupt a concurrent cycle), the number of full collections
2053 // completed should be either one (in the case where there was no
2054 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2055 // behind the number of full collections started.
2056
2057 // This is the case for the inner caller, i.e. a Full GC.
2058 assert(concurrent ||
2059 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2060 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2061 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2062 "is inconsistent with _old_marking_cycles_completed = %u",
2063 _old_marking_cycles_started, _old_marking_cycles_completed);
2064
2065 // This is the case for the outer caller, i.e. the concurrent cycle.
2066 assert(!concurrent ||
2067 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2068 "for outer caller (concurrent cycle): "
2069 "_old_marking_cycles_started = %u "
2070 "is inconsistent with _old_marking_cycles_completed = %u",
2071 _old_marking_cycles_started, _old_marking_cycles_completed);
2072
2073 _old_marking_cycles_completed += 1;
2074
2075 // We need to clear the "in_progress" flag in the CM thread before
2076 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2077 // is set) so that if a waiter requests another System.gc() it doesn't
2078 // incorrectly see that a marking cycle is still in progress.
2079 if (concurrent) {
2080 _cm_thread->set_idle();
2081 }
2082
2083 // This notify_all() will ensure that a thread that called
2084 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2085 // and it's waiting for a full GC to finish will be woken up. It is
2086 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2087 FullGCCount_lock->notify_all();
2088 }
2089
2090 void G1CollectedHeap::collect(GCCause::Cause cause) {
2091 assert_heap_not_locked();
2092
2093 uint gc_count_before;
2094 uint old_marking_count_before;
2095 uint full_gc_count_before;
2096 bool retry_gc;
2097
2098 do {
2099 retry_gc = false;
2100
2101 {
2102 MutexLocker ml(Heap_lock);
2103
2104 // Read the GC count while holding the Heap_lock
2105 gc_count_before = total_collections();
2106 full_gc_count_before = total_full_collections();
2107 old_marking_count_before = _old_marking_cycles_started;
2108 }
2109
2110 if (should_do_concurrent_full_gc(cause)) {
2111 // Schedule an initial-mark evacuation pause that will start a
2112 // concurrent cycle. We're setting word_size to 0 which means that
2113 // we are not requesting a post-GC allocation.
2114 VM_G1CollectForAllocation op(0, /* word_size */
2115 gc_count_before,
2116 cause,
2117 true, /* should_initiate_conc_mark */
2118 g1_policy()->max_pause_time_ms());
2119 VMThread::execute(&op);
2120 if (!op.pause_succeeded()) {
2121 if (old_marking_count_before == _old_marking_cycles_started) {
2122 retry_gc = op.should_retry_gc();
2123 } else {
2124 // A Full GC happened while we were trying to schedule the
2125 // initial-mark GC. No point in starting a new cycle given
2126 // that the whole heap was collected anyway.
2127 }
2128
2129 if (retry_gc) {
2130 if (GCLocker::is_active_and_needs_gc()) {
2131 GCLocker::stall_until_clear();
2132 }
2133 }
2134 }
2135 } else {
2136 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2137 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2138
2139 // Schedule a standard evacuation pause. We're setting word_size
2140 // to 0 which means that we are not requesting a post-GC allocation.
2141 VM_G1CollectForAllocation op(0, /* word_size */
2142 gc_count_before,
2143 cause,
2144 false, /* should_initiate_conc_mark */
2145 g1_policy()->max_pause_time_ms());
2146 VMThread::execute(&op);
2147 } else {
2148 // Schedule a Full GC.
2149 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2150 VMThread::execute(&op);
2151 }
2152 }
2153 } while (retry_gc);
2154 }
2155
2156 bool G1CollectedHeap::is_in(const void* p) const {
2157 if (_hrm->reserved().contains(p)) {
2158 // Given that we know that p is in the reserved space,
2159 // heap_region_containing() should successfully
2160 // return the containing region.
2161 HeapRegion* hr = heap_region_containing(p);
2162 return hr->is_in(p);
2163 } else {
2164 return false;
2165 }
2166 }
2167
2168 #ifdef ASSERT
2169 bool G1CollectedHeap::is_in_exact(const void* p) const {
2170 bool contains = reserved_region().contains(p);
2171 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2172 if (contains && available) {
2173 return true;
2174 } else {
2175 return false;
2176 }
2177 }
2178 #endif
2179
2180 // Iteration functions.
2181
2182 // Iterates an ObjectClosure over all objects within a HeapRegion.
2183
2184 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2185 ObjectClosure* _cl;
2186 public:
2187 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2188 bool do_heap_region(HeapRegion* r) {
2189 if (!r->is_continues_humongous()) {
2190 r->object_iterate(_cl);
2191 }
2192 return false;
2193 }
2194 };
2195
2196 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2197 IterateObjectClosureRegionClosure blk(cl);
2198 heap_region_iterate(&blk);
2199 }
2200
2201 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2202 _hrm->iterate(cl);
2203 }
2204
2205 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2206 HeapRegionClaimer *hrclaimer,
2207 uint worker_id) const {
2208 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2209 }
2210
2211 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2212 HeapRegionClaimer *hrclaimer) const {
2213 _hrm->par_iterate(cl, hrclaimer, 0);
2214 }
2215
2216 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2217 _collection_set.iterate(cl);
2218 }
2219
2220 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2221 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2222 }
2223
2224 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2225 HeapRegion* hr = heap_region_containing(addr);
2226 return hr->block_start(addr);
2227 }
2228
2229 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2230 HeapRegion* hr = heap_region_containing(addr);
2231 return hr->block_size(addr);
2232 }
2233
2234 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2235 HeapRegion* hr = heap_region_containing(addr);
2236 return hr->block_is_obj(addr);
2237 }
2238
2239 bool G1CollectedHeap::supports_tlab_allocation() const {
2240 return true;
2241 }
2242
2243 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2244 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2245 }
2246
2247 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2248 return _eden.length() * HeapRegion::GrainBytes;
2249 }
2250
2251 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2252 // must be equal to the humongous object limit.
2253 size_t G1CollectedHeap::max_tlab_size() const {
2254 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2255 }
2256
2257 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2258 return _allocator->unsafe_max_tlab_alloc();
2259 }
2260
2261 size_t G1CollectedHeap::max_capacity() const {
2262 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2263 }
2264
2265 size_t G1CollectedHeap::max_reserved_capacity() const {
2266 return _hrm->max_length() * HeapRegion::GrainBytes;
2267 }
2268
2269 jlong G1CollectedHeap::millis_since_last_gc() {
2270 // See the notes in GenCollectedHeap::millis_since_last_gc()
2271 // for more information about the implementation.
2272 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2273 _g1_policy->collection_pause_end_millis();
2274 if (ret_val < 0) {
2275 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2276 ". returning zero instead.", ret_val);
2277 return 0;
2278 }
2279 return ret_val;
2280 }
2281
2282 void G1CollectedHeap::deduplicate_string(oop str) {
2283 assert(java_lang_String::is_instance(str), "invariant");
2284
2285 if (G1StringDedup::is_enabled()) {
2286 G1StringDedup::deduplicate(str);
2287 }
2288 }
2289
2290 void G1CollectedHeap::prepare_for_verify() {
2291 _verifier->prepare_for_verify();
2292 }
2293
2294 void G1CollectedHeap::verify(VerifyOption vo) {
2295 _verifier->verify(vo);
2296 }
2297
2298 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2299 return true;
2300 }
2301
2302 const char* const* G1CollectedHeap::concurrent_phases() const {
2303 return _cm_thread->concurrent_phases();
2304 }
2305
2306 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2307 return _cm_thread->request_concurrent_phase(phase);
2308 }
2309
2310 class PrintRegionClosure: public HeapRegionClosure {
2311 outputStream* _st;
2312 public:
2313 PrintRegionClosure(outputStream* st) : _st(st) {}
2314 bool do_heap_region(HeapRegion* r) {
2315 r->print_on(_st);
2316 return false;
2317 }
2318 };
2319
2320 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2321 const HeapRegion* hr,
2322 const VerifyOption vo) const {
2323 switch (vo) {
2324 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2325 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2326 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2327 default: ShouldNotReachHere();
2328 }
2329 return false; // keep some compilers happy
2330 }
2331
2332 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2333 const VerifyOption vo) const {
2334 switch (vo) {
2335 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2336 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2337 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2338 default: ShouldNotReachHere();
2339 }
2340 return false; // keep some compilers happy
2341 }
2342
2343 void G1CollectedHeap::print_heap_regions() const {
2344 LogTarget(Trace, gc, heap, region) lt;
2345 if (lt.is_enabled()) {
2346 LogStream ls(lt);
2347 print_regions_on(&ls);
2348 }
2349 }
2350
2351 void G1CollectedHeap::print_on(outputStream* st) const {
2352 st->print(" %-20s", "garbage-first heap");
2353 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2354 capacity()/K, used_unlocked()/K);
2355 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2356 p2i(_hrm->reserved().start()),
2357 p2i(_hrm->reserved().end()));
2358 st->cr();
2359 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2360 uint young_regions = young_regions_count();
2361 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2362 (size_t) young_regions * HeapRegion::GrainBytes / K);
2363 uint survivor_regions = survivor_regions_count();
2364 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2365 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2366 st->cr();
2367 MetaspaceUtils::print_on(st);
2368 }
2369
2370 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2371 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2372 "HS=humongous(starts), HC=humongous(continues), "
2373 "CS=collection set, F=free, A=archive, "
2374 "TAMS=top-at-mark-start (previous, next)");
2375 PrintRegionClosure blk(st);
2376 heap_region_iterate(&blk);
2377 }
2378
2379 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2380 print_on(st);
2381
2382 // Print the per-region information.
2383 print_regions_on(st);
2384 }
2385
2386 void G1CollectedHeap::print_on_error(outputStream* st) const {
2387 this->CollectedHeap::print_on_error(st);
2388
2389 if (_cm != NULL) {
2390 st->cr();
2391 _cm->print_on_error(st);
2392 }
2393 }
2394
2395 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2396 workers()->print_worker_threads_on(st);
2397 _cm_thread->print_on(st);
2398 st->cr();
2399 _cm->print_worker_threads_on(st);
2400 _cr->print_threads_on(st);
2401 _young_gen_sampling_thread->print_on(st);
2402 if (G1StringDedup::is_enabled()) {
2403 G1StringDedup::print_worker_threads_on(st);
2404 }
2405 }
2406
2407 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2408 workers()->threads_do(tc);
2409 tc->do_thread(_cm_thread);
2410 _cm->threads_do(tc);
2411 _cr->threads_do(tc);
2412 tc->do_thread(_young_gen_sampling_thread);
2413 if (G1StringDedup::is_enabled()) {
2414 G1StringDedup::threads_do(tc);
2415 }
2416 }
2417
2418 void G1CollectedHeap::print_tracing_info() const {
2419 g1_rem_set()->print_summary_info();
2420 concurrent_mark()->print_summary_info();
2421 }
2422
2423 #ifndef PRODUCT
2424 // Helpful for debugging RSet issues.
2425
2426 class PrintRSetsClosure : public HeapRegionClosure {
2427 private:
2428 const char* _msg;
2429 size_t _occupied_sum;
2430
2431 public:
2432 bool do_heap_region(HeapRegion* r) {
2433 HeapRegionRemSet* hrrs = r->rem_set();
2434 size_t occupied = hrrs->occupied();
2435 _occupied_sum += occupied;
2436
2437 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2438 if (occupied == 0) {
2439 tty->print_cr(" RSet is empty");
2440 } else {
2441 hrrs->print();
2442 }
2443 tty->print_cr("----------");
2444 return false;
2445 }
2446
2447 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2448 tty->cr();
2449 tty->print_cr("========================================");
2450 tty->print_cr("%s", msg);
2451 tty->cr();
2452 }
2453
2454 ~PrintRSetsClosure() {
2455 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2456 tty->print_cr("========================================");
2457 tty->cr();
2458 }
2459 };
2460
2461 void G1CollectedHeap::print_cset_rsets() {
2462 PrintRSetsClosure cl("Printing CSet RSets");
2463 collection_set_iterate(&cl);
2464 }
2465
2466 void G1CollectedHeap::print_all_rsets() {
2467 PrintRSetsClosure cl("Printing All RSets");;
2468 heap_region_iterate(&cl);
2469 }
2470 #endif // PRODUCT
2471
2472 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2473
2474 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2475 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2476 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2477
2478 size_t eden_capacity_bytes =
2479 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2480
2481 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2482 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2483 eden_capacity_bytes, survivor_used_bytes, num_regions());
2484 }
2485
2486 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2487 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2488 stats->unused(), stats->used(), stats->region_end_waste(),
2489 stats->regions_filled(), stats->direct_allocated(),
2490 stats->failure_used(), stats->failure_waste());
2491 }
2492
2493 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2494 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2495 gc_tracer->report_gc_heap_summary(when, heap_summary);
2496
2497 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2498 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2499 }
2500
2501 G1CollectedHeap* G1CollectedHeap::heap() {
2502 CollectedHeap* heap = Universe::heap();
2503 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2504 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2505 return (G1CollectedHeap*)heap;
2506 }
2507
2508 void G1CollectedHeap::gc_prologue(bool full) {
2509 // always_do_update_barrier = false;
2510 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2511
2512 // This summary needs to be printed before incrementing total collections.
2513 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2514
2515 // Update common counters.
2516 increment_total_collections(full /* full gc */);
2517 if (full) {
2518 increment_old_marking_cycles_started();
2519 }
2520
2521 // Fill TLAB's and such
2522 double start = os::elapsedTime();
2523 ensure_parsability(true);
2524 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2525 }
2526
2527 void G1CollectedHeap::gc_epilogue(bool full) {
2528 // Update common counters.
2529 if (full) {
2530 // Update the number of full collections that have been completed.
2531 increment_old_marking_cycles_completed(false /* concurrent */);
2532 // Now we know the target length of young list. So adjust the heap to provision that many regions on dram.
2533 if (is_hetero_heap()) {
2534 static_cast<HeterogeneousHeapRegionManager*>(hrm())->adjust_dram_regions((uint)g1_policy()->young_list_target_length(), workers());
2535 }
2536 }
2537
2538 // We are at the end of the GC. Total collections has already been increased.
2539 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2540
2541 // FIXME: what is this about?
2542 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2543 // is set.
2544 #if COMPILER2_OR_JVMCI
2545 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2546 #endif
2547 // always_do_update_barrier = true;
2548
2549 double start = os::elapsedTime();
2550 resize_all_tlabs();
2551 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2552
2553 MemoryService::track_memory_usage();
2554 // We have just completed a GC. Update the soft reference
2555 // policy with the new heap occupancy
2556 Universe::update_heap_info_at_gc();
2557 }
2558
2559 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2560 uint gc_count_before,
2561 bool* succeeded,
2562 GCCause::Cause gc_cause) {
2563 assert_heap_not_locked_and_not_at_safepoint();
2564 VM_G1CollectForAllocation op(word_size,
2565 gc_count_before,
2566 gc_cause,
2567 false, /* should_initiate_conc_mark */
2568 g1_policy()->max_pause_time_ms());
2569 VMThread::execute(&op);
2570
2571 HeapWord* result = op.result();
2572 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2573 assert(result == NULL || ret_succeeded,
2574 "the result should be NULL if the VM did not succeed");
2575 *succeeded = ret_succeeded;
2576
2577 assert_heap_not_locked();
2578 return result;
2579 }
2580
2581 void G1CollectedHeap::do_concurrent_mark() {
2582 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2583 if (!_cm_thread->in_progress()) {
2584 _cm_thread->set_started();
2585 CGC_lock->notify();
2586 }
2587 }
2588
2589 size_t G1CollectedHeap::pending_card_num() {
2590 size_t extra_cards = 0;
2591 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2592 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2593 extra_cards += dcq.size();
2594 }
2595 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2596 size_t buffer_size = dcqs.buffer_size();
2597 size_t buffer_num = dcqs.completed_buffers_num();
2598
2599 return buffer_size * buffer_num + extra_cards;
2600 }
2601
2602 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2603 // We don't nominate objects with many remembered set entries, on
2604 // the assumption that such objects are likely still live.
2605 HeapRegionRemSet* rem_set = r->rem_set();
2606
2607 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2608 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2609 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2610 }
2611
2612 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2613 private:
2614 size_t _total_humongous;
2615 size_t _candidate_humongous;
2616
2617 DirtyCardQueue _dcq;
2618
2619 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2620 assert(region->is_starts_humongous(), "Must start a humongous object");
2621
2622 oop obj = oop(region->bottom());
2623
2624 // Dead objects cannot be eager reclaim candidates. Due to class
2625 // unloading it is unsafe to query their classes so we return early.
2626 if (g1h->is_obj_dead(obj, region)) {
2627 return false;
2628 }
2629
2630 // If we do not have a complete remembered set for the region, then we can
2631 // not be sure that we have all references to it.
2632 if (!region->rem_set()->is_complete()) {
2633 return false;
2634 }
2635 // Candidate selection must satisfy the following constraints
2636 // while concurrent marking is in progress:
2637 //
2638 // * In order to maintain SATB invariants, an object must not be
2639 // reclaimed if it was allocated before the start of marking and
2640 // has not had its references scanned. Such an object must have
2641 // its references (including type metadata) scanned to ensure no
2642 // live objects are missed by the marking process. Objects
2643 // allocated after the start of concurrent marking don't need to
2644 // be scanned.
2645 //
2646 // * An object must not be reclaimed if it is on the concurrent
2647 // mark stack. Objects allocated after the start of concurrent
2648 // marking are never pushed on the mark stack.
2649 //
2650 // Nominating only objects allocated after the start of concurrent
2651 // marking is sufficient to meet both constraints. This may miss
2652 // some objects that satisfy the constraints, but the marking data
2653 // structures don't support efficiently performing the needed
2654 // additional tests or scrubbing of the mark stack.
2655 //
2656 // However, we presently only nominate is_typeArray() objects.
2657 // A humongous object containing references induces remembered
2658 // set entries on other regions. In order to reclaim such an
2659 // object, those remembered sets would need to be cleaned up.
2660 //
2661 // We also treat is_typeArray() objects specially, allowing them
2662 // to be reclaimed even if allocated before the start of
2663 // concurrent mark. For this we rely on mark stack insertion to
2664 // exclude is_typeArray() objects, preventing reclaiming an object
2665 // that is in the mark stack. We also rely on the metadata for
2666 // such objects to be built-in and so ensured to be kept live.
2667 // Frequent allocation and drop of large binary blobs is an
2668 // important use case for eager reclaim, and this special handling
2669 // may reduce needed headroom.
2670
2671 return obj->is_typeArray() &&
2672 g1h->is_potential_eager_reclaim_candidate(region);
2673 }
2674
2675 public:
2676 RegisterHumongousWithInCSetFastTestClosure()
2677 : _total_humongous(0),
2678 _candidate_humongous(0),
2679 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2680 }
2681
2682 virtual bool do_heap_region(HeapRegion* r) {
2683 if (!r->is_starts_humongous()) {
2684 return false;
2685 }
2686 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2687
2688 bool is_candidate = humongous_region_is_candidate(g1h, r);
2689 uint rindex = r->hrm_index();
2690 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2691 if (is_candidate) {
2692 _candidate_humongous++;
2693 g1h->register_humongous_region_with_cset(rindex);
2694 // Is_candidate already filters out humongous object with large remembered sets.
2695 // If we have a humongous object with a few remembered sets, we simply flush these
2696 // remembered set entries into the DCQS. That will result in automatic
2697 // re-evaluation of their remembered set entries during the following evacuation
2698 // phase.
2699 if (!r->rem_set()->is_empty()) {
2700 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2701 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2702 G1CardTable* ct = g1h->card_table();
2703 HeapRegionRemSetIterator hrrs(r->rem_set());
2704 size_t card_index;
2705 while (hrrs.has_next(card_index)) {
2706 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2707 // The remembered set might contain references to already freed
2708 // regions. Filter out such entries to avoid failing card table
2709 // verification.
2710 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2711 if (*card_ptr != G1CardTable::dirty_card_val()) {
2712 *card_ptr = G1CardTable::dirty_card_val();
2713 _dcq.enqueue(card_ptr);
2714 }
2715 }
2716 }
2717 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2718 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2719 hrrs.n_yielded(), r->rem_set()->occupied());
2720 // We should only clear the card based remembered set here as we will not
2721 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2722 // (and probably never) we do not enter this path if there are other kind of
2723 // remembered sets for this region.
2724 r->rem_set()->clear_locked(true /* only_cardset */);
2725 // Clear_locked() above sets the state to Empty. However we want to continue
2726 // collecting remembered set entries for humongous regions that were not
2727 // reclaimed.
2728 r->rem_set()->set_state_complete();
2729 }
2730 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2731 }
2732 _total_humongous++;
2733
2734 return false;
2735 }
2736
2737 size_t total_humongous() const { return _total_humongous; }
2738 size_t candidate_humongous() const { return _candidate_humongous; }
2739
2740 void flush_rem_set_entries() { _dcq.flush(); }
2741 };
2742
2743 void G1CollectedHeap::register_humongous_regions_with_cset() {
2744 if (!G1EagerReclaimHumongousObjects) {
2745 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2746 return;
2747 }
2748 double time = os::elapsed_counter();
2749
2750 // Collect reclaim candidate information and register candidates with cset.
2751 RegisterHumongousWithInCSetFastTestClosure cl;
2752 heap_region_iterate(&cl);
2753
2754 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2755 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2756 cl.total_humongous(),
2757 cl.candidate_humongous());
2758 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2759
2760 // Finally flush all remembered set entries to re-check into the global DCQS.
2761 cl.flush_rem_set_entries();
2762 }
2763
2764 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2765 public:
2766 bool do_heap_region(HeapRegion* hr) {
2767 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2768 hr->verify_rem_set();
2769 }
2770 return false;
2771 }
2772 };
2773
2774 uint G1CollectedHeap::num_task_queues() const {
2775 return _task_queues->size();
2776 }
2777
2778 #if TASKQUEUE_STATS
2779 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2780 st->print_raw_cr("GC Task Stats");
2781 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2782 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2783 }
2784
2785 void G1CollectedHeap::print_taskqueue_stats() const {
2786 if (!log_is_enabled(Trace, gc, task, stats)) {
2787 return;
2788 }
2789 Log(gc, task, stats) log;
2790 ResourceMark rm;
2791 LogStream ls(log.trace());
2792 outputStream* st = &ls;
2793
2794 print_taskqueue_stats_hdr(st);
2795
2796 TaskQueueStats totals;
2797 const uint n = num_task_queues();
2798 for (uint i = 0; i < n; ++i) {
2799 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2800 totals += task_queue(i)->stats;
2801 }
2802 st->print_raw("tot "); totals.print(st); st->cr();
2803
2804 DEBUG_ONLY(totals.verify());
2805 }
2806
2807 void G1CollectedHeap::reset_taskqueue_stats() {
2808 const uint n = num_task_queues();
2809 for (uint i = 0; i < n; ++i) {
2810 task_queue(i)->stats.reset();
2811 }
2812 }
2813 #endif // TASKQUEUE_STATS
2814
2815 void G1CollectedHeap::wait_for_root_region_scanning() {
2816 double scan_wait_start = os::elapsedTime();
2817 // We have to wait until the CM threads finish scanning the
2818 // root regions as it's the only way to ensure that all the
2819 // objects on them have been correctly scanned before we start
2820 // moving them during the GC.
2821 bool waited = _cm->root_regions()->wait_until_scan_finished();
2822 double wait_time_ms = 0.0;
2823 if (waited) {
2824 double scan_wait_end = os::elapsedTime();
2825 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2826 }
2827 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2828 }
2829
2830 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2831 private:
2832 G1HRPrinter* _hr_printer;
2833 public:
2834 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2835
2836 virtual bool do_heap_region(HeapRegion* r) {
2837 _hr_printer->cset(r);
2838 return false;
2839 }
2840 };
2841
2842 void G1CollectedHeap::start_new_collection_set() {
2843 collection_set()->start_incremental_building();
2844
2845 clear_cset_fast_test();
2846
2847 guarantee(_eden.length() == 0, "eden should have been cleared");
2848 g1_policy()->transfer_survivors_to_cset(survivor());
2849 }
2850
2851 bool
2852 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2853 assert_at_safepoint_on_vm_thread();
2854 guarantee(!is_gc_active(), "collection is not reentrant");
2855
2856 if (GCLocker::check_active_before_gc()) {
2857 return false;
2858 }
2859
2860 _gc_timer_stw->register_gc_start();
2861
2862 GCIdMark gc_id_mark;
2863 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2864
2865 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2866 ResourceMark rm;
2867
2868 g1_policy()->note_gc_start();
2869
2870 wait_for_root_region_scanning();
2871
2872 print_heap_before_gc();
2873 print_heap_regions();
2874 trace_heap_before_gc(_gc_tracer_stw);
2875
2876 _verifier->verify_region_sets_optional();
2877 _verifier->verify_dirty_young_regions();
2878
2879 // We should not be doing initial mark unless the conc mark thread is running
2880 if (!_cm_thread->should_terminate()) {
2881 // This call will decide whether this pause is an initial-mark
2882 // pause. If it is, in_initial_mark_gc() will return true
2883 // for the duration of this pause.
2884 g1_policy()->decide_on_conc_mark_initiation();
2885 }
2886
2887 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2888 assert(!collector_state()->in_initial_mark_gc() ||
2889 collector_state()->in_young_only_phase(), "sanity");
2890
2891 // We also do not allow mixed GCs during marking.
2892 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2893
2894 // Record whether this pause is an initial mark. When the current
2895 // thread has completed its logging output and it's safe to signal
2896 // the CM thread, the flag's value in the policy has been reset.
2897 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2898
2899 // Inner scope for scope based logging, timers, and stats collection
2900 {
2901 EvacuationInfo evacuation_info;
2902
2903 if (collector_state()->in_initial_mark_gc()) {
2904 // We are about to start a marking cycle, so we increment the
2905 // full collection counter.
2906 increment_old_marking_cycles_started();
2907 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2908 }
2909
2910 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2911
2912 GCTraceCPUTime tcpu;
2913
2914 G1HeapVerifier::G1VerifyType verify_type;
2915 FormatBuffer<> gc_string("Pause Young ");
2916 if (collector_state()->in_initial_mark_gc()) {
2917 gc_string.append("(Concurrent Start)");
2918 verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2919 } else if (collector_state()->in_young_only_phase()) {
2920 if (collector_state()->in_young_gc_before_mixed()) {
2921 gc_string.append("(Prepare Mixed)");
2922 } else {
2923 gc_string.append("(Normal)");
2924 }
2925 verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2926 } else {
2927 gc_string.append("(Mixed)");
2928 verify_type = G1HeapVerifier::G1VerifyMixed;
2929 }
2930 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2931
2932 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2933 workers()->active_workers(),
2934 Threads::number_of_non_daemon_threads());
2935 active_workers = workers()->update_active_workers(active_workers);
2936 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2937
2938 G1MonitoringScope ms(g1mm(),
2939 false /* full_gc */,
2940 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2941
2942 G1HeapTransition heap_transition(this);
2943 size_t heap_used_bytes_before_gc = used();
2944
2945 // Don't dynamically change the number of GC threads this early. A value of
2946 // 0 is used to indicate serial work. When parallel work is done,
2947 // it will be set.
2948
2949 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2950 IsGCActiveMark x;
2951
2952 gc_prologue(false);
2953
2954 if (VerifyRememberedSets) {
2955 log_info(gc, verify)("[Verifying RemSets before GC]");
2956 VerifyRegionRemSetClosure v_cl;
2957 heap_region_iterate(&v_cl);
2958 }
2959
2960 _verifier->verify_before_gc(verify_type);
2961
2962 _verifier->check_bitmaps("GC Start");
2963
2964 #if COMPILER2_OR_JVMCI
2965 DerivedPointerTable::clear();
2966 #endif
2967
2968 // Please see comment in g1CollectedHeap.hpp and
2969 // G1CollectedHeap::ref_processing_init() to see how
2970 // reference processing currently works in G1.
2971
2972 // Enable discovery in the STW reference processor
2973 _ref_processor_stw->enable_discovery();
2974
2975 {
2976 // We want to temporarily turn off discovery by the
2977 // CM ref processor, if necessary, and turn it back on
2978 // on again later if we do. Using a scoped
2979 // NoRefDiscovery object will do this.
2980 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2981
2982 // Forget the current alloc region (we might even choose it to be part
2983 // of the collection set!).
2984 _allocator->release_mutator_alloc_region();
2985
2986 // This timing is only used by the ergonomics to handle our pause target.
2987 // It is unclear why this should not include the full pause. We will
2988 // investigate this in CR 7178365.
2989 //
2990 // Preserving the old comment here if that helps the investigation:
2991 //
2992 // The elapsed time induced by the start time below deliberately elides
2993 // the possible verification above.
2994 double sample_start_time_sec = os::elapsedTime();
2995
2996 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2997
2998 if (collector_state()->in_initial_mark_gc()) {
2999 concurrent_mark()->pre_initial_mark();
3000 }
3001
3002 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3003
3004 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3005
3006 // Make sure the remembered sets are up to date. This needs to be
3007 // done before register_humongous_regions_with_cset(), because the
3008 // remembered sets are used there to choose eager reclaim candidates.
3009 // If the remembered sets are not up to date we might miss some
3010 // entries that need to be handled.
3011 g1_rem_set()->cleanupHRRS();
3012
3013 register_humongous_regions_with_cset();
3014
3015 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3016
3017 // We call this after finalize_cset() to
3018 // ensure that the CSet has been finalized.
3019 _cm->verify_no_cset_oops();
3020
3021 if (_hr_printer.is_active()) {
3022 G1PrintCollectionSetClosure cl(&_hr_printer);
3023 _collection_set.iterate(&cl);
3024 }
3025
3026 // Initialize the GC alloc regions.
3027 _allocator->init_gc_alloc_regions(evacuation_info);
3028
3029 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3030 pre_evacuate_collection_set();
3031
3032 // Actually do the work...
3033 evacuate_collection_set(&per_thread_states);
3034
3035 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3036
3037 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3038 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3039
3040 eagerly_reclaim_humongous_regions();
3041
3042 record_obj_copy_mem_stats();
3043 _survivor_evac_stats.adjust_desired_plab_sz();
3044 _old_evac_stats.adjust_desired_plab_sz();
3045
3046 double start = os::elapsedTime();
3047 start_new_collection_set();
3048 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3049
3050 if (evacuation_failed()) {
3051 double recalculate_used_start = os::elapsedTime();
3052 set_used(recalculate_used());
3053 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3054
3055 if (_archive_allocator != NULL) {
3056 _archive_allocator->clear_used();
3057 }
3058 for (uint i = 0; i < ParallelGCThreads; i++) {
3059 if (_evacuation_failed_info_array[i].has_failed()) {
3060 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3061 }
3062 }
3063 } else {
3064 // The "used" of the the collection set have already been subtracted
3065 // when they were freed. Add in the bytes evacuated.
3066 increase_used(g1_policy()->bytes_copied_during_gc());
3067 }
3068
3069 if (collector_state()->in_initial_mark_gc()) {
3070 // We have to do this before we notify the CM threads that
3071 // they can start working to make sure that all the
3072 // appropriate initialization is done on the CM object.
3073 concurrent_mark()->post_initial_mark();
3074 // Note that we don't actually trigger the CM thread at
3075 // this point. We do that later when we're sure that
3076 // the current thread has completed its logging output.
3077 }
3078
3079 allocate_dummy_regions();
3080
3081 _allocator->init_mutator_alloc_region();
3082
3083 {
3084 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3085 if (expand_bytes > 0) {
3086 size_t bytes_before = capacity();
3087 // No need for an ergo logging here,
3088 // expansion_amount() does this when it returns a value > 0.
3089 double expand_ms;
3090 if (!expand(expand_bytes, _workers, &expand_ms)) {
3091 // We failed to expand the heap. Cannot do anything about it.
3092 }
3093 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3094 }
3095 }
3096
3097 // We redo the verification but now wrt to the new CSet which
3098 // has just got initialized after the previous CSet was freed.
3099 _cm->verify_no_cset_oops();
3100
3101 // This timing is only used by the ergonomics to handle our pause target.
3102 // It is unclear why this should not include the full pause. We will
3103 // investigate this in CR 7178365.
3104 double sample_end_time_sec = os::elapsedTime();
3105 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3106 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3107 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3108
3109 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3110 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3111
3112 if (VerifyRememberedSets) {
3113 log_info(gc, verify)("[Verifying RemSets after GC]");
3114 VerifyRegionRemSetClosure v_cl;
3115 heap_region_iterate(&v_cl);
3116 }
3117
3118 _verifier->verify_after_gc(verify_type);
3119 _verifier->check_bitmaps("GC End");
3120
3121 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3122 _ref_processor_stw->verify_no_references_recorded();
3123
3124 // CM reference discovery will be re-enabled if necessary.
3125 }
3126
3127 #ifdef TRACESPINNING
3128 ParallelTaskTerminator::print_termination_counts();
3129 #endif
3130
3131 gc_epilogue(false);
3132 }
3133
3134 // Print the remainder of the GC log output.
3135 if (evacuation_failed()) {
3136 log_info(gc)("To-space exhausted");
3137 }
3138
3139 g1_policy()->print_phases();
3140 heap_transition.print();
3141
3142 // It is not yet to safe to tell the concurrent mark to
3143 // start as we have some optional output below. We don't want the
3144 // output from the concurrent mark thread interfering with this
3145 // logging output either.
3146
3147 _hrm->verify_optional();
3148 _verifier->verify_region_sets_optional();
3149
3150 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3151 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3152
3153 print_heap_after_gc();
3154 print_heap_regions();
3155 trace_heap_after_gc(_gc_tracer_stw);
3156
3157 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3158 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3159 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3160 // before any GC notifications are raised.
3161 g1mm()->update_sizes();
3162
3163 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3164 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3165 _gc_timer_stw->register_gc_end();
3166 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3167 }
3168 // It should now be safe to tell the concurrent mark thread to start
3169 // without its logging output interfering with the logging output
3170 // that came from the pause.
3171
3172 if (should_start_conc_mark) {
3173 // CAUTION: after the doConcurrentMark() call below,
3174 // the concurrent marking thread(s) could be running
3175 // concurrently with us. Make sure that anything after
3176 // this point does not assume that we are the only GC thread
3177 // running. Note: of course, the actual marking work will
3178 // not start until the safepoint itself is released in
3179 // SuspendibleThreadSet::desynchronize().
3180 do_concurrent_mark();
3181 }
3182
3183 return true;
3184 }
3185
3186 void G1CollectedHeap::remove_self_forwarding_pointers() {
3187 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3188 workers()->run_task(&rsfp_task);
3189 }
3190
3191 void G1CollectedHeap::restore_after_evac_failure() {
3192 double remove_self_forwards_start = os::elapsedTime();
3193
3194 remove_self_forwarding_pointers();
3195 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3196 _preserved_marks_set.restore(&task_executor);
3197
3198 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3199 }
3200
3201 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3202 if (!_evacuation_failed) {
3203 _evacuation_failed = true;
3204 }
3205
3206 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3207 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3208 }
3209
3210 bool G1ParEvacuateFollowersClosure::offer_termination() {
3211 EventGCPhaseParallel event;
3212 G1ParScanThreadState* const pss = par_scan_state();
3213 start_term_time();
3214 const bool res = terminator()->offer_termination();
3215 end_term_time();
3216 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3217 return res;
3218 }
3219
3220 void G1ParEvacuateFollowersClosure::do_void() {
3221 EventGCPhaseParallel event;
3222 G1ParScanThreadState* const pss = par_scan_state();
3223 pss->trim_queue();
3224 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3225 do {
3226 EventGCPhaseParallel event;
3227 pss->steal_and_trim_queue(queues());
3228 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3229 } while (!offer_termination());
3230 }
3231
3232 class G1ParTask : public AbstractGangTask {
3233 protected:
3234 G1CollectedHeap* _g1h;
3235 G1ParScanThreadStateSet* _pss;
3236 RefToScanQueueSet* _queues;
3237 G1RootProcessor* _root_processor;
3238 ParallelTaskTerminator _terminator;
3239 uint _n_workers;
3240
3241 public:
3242 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3243 : AbstractGangTask("G1 collection"),
3244 _g1h(g1h),
3245 _pss(per_thread_states),
3246 _queues(task_queues),
3247 _root_processor(root_processor),
3248 _terminator(n_workers, _queues),
3249 _n_workers(n_workers)
3250 {}
3251
3252 void work(uint worker_id) {
3253 if (worker_id >= _n_workers) return; // no work needed this round
3254
3255 double start_sec = os::elapsedTime();
3256 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3257
3258 {
3259 ResourceMark rm;
3260 HandleMark hm;
3261
3262 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3263
3264 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3265 pss->set_ref_discoverer(rp);
3266
3267 double start_strong_roots_sec = os::elapsedTime();
3268
3269 _root_processor->evacuate_roots(pss, worker_id);
3270
3271 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3272 // treating the nmethods visited to act as roots for concurrent marking.
3273 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3274 // objects copied by the current evacuation.
3275 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3276
3277 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3278
3279 double term_sec = 0.0;
3280 size_t evac_term_attempts = 0;
3281 {
3282 double start = os::elapsedTime();
3283 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3284 evac.do_void();
3285
3286 evac_term_attempts = evac.term_attempts();
3287 term_sec = evac.term_time();
3288 double elapsed_sec = os::elapsedTime() - start;
3289
3290 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3291 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3292 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3293 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3294 }
3295
3296 assert(pss->queue_is_empty(), "should be empty");
3297
3298 if (log_is_enabled(Debug, gc, task, stats)) {
3299 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3300 size_t lab_waste;
3301 size_t lab_undo_waste;
3302 pss->waste(lab_waste, lab_undo_waste);
3303 _g1h->print_termination_stats(worker_id,
3304 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3305 strong_roots_sec * 1000.0, /* strong roots time */
3306 term_sec * 1000.0, /* evac term time */
3307 evac_term_attempts, /* evac term attempts */
3308 lab_waste, /* alloc buffer waste */
3309 lab_undo_waste /* undo waste */
3310 );
3311 }
3312
3313 // Close the inner scope so that the ResourceMark and HandleMark
3314 // destructors are executed here and are included as part of the
3315 // "GC Worker Time".
3316 }
3317 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3318 }
3319 };
3320
3321 void G1CollectedHeap::print_termination_stats_hdr() {
3322 log_debug(gc, task, stats)("GC Termination Stats");
3323 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3324 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3325 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3326 }
3327
3328 void G1CollectedHeap::print_termination_stats(uint worker_id,
3329 double elapsed_ms,
3330 double strong_roots_ms,
3331 double term_ms,
3332 size_t term_attempts,
3333 size_t alloc_buffer_waste,
3334 size_t undo_waste) const {
3335 log_debug(gc, task, stats)
3336 ("%3d %9.2f %9.2f %6.2f "
3337 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3338 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3339 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3340 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3341 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3342 alloc_buffer_waste * HeapWordSize / K,
3343 undo_waste * HeapWordSize / K);
3344 }
3345
3346 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3347 bool class_unloading_occurred) {
3348 uint n_workers = workers()->active_workers();
3349
3350 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3351 ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
3352 workers()->run_task(&g1_unlink_task);
3353 }
3354
3355 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3356 bool process_strings,
3357 bool process_string_dedup) {
3358 if (!process_strings && !process_string_dedup) {
3359 // Nothing to clean.
3360 return;
3361 }
3362
3363 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3364 StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
3365 workers()->run_task(&g1_unlink_task);
3366 }
3367
3368 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3369 private:
3370 DirtyCardQueueSet* _queue;
3371 G1CollectedHeap* _g1h;
3372 public:
3373 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3374 _queue(queue), _g1h(g1h) { }
3375
3376 virtual void work(uint worker_id) {
3377 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3378 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3379
3380 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3381 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3382
3383 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3384 }
3385 };
3386
3387 void G1CollectedHeap::redirty_logged_cards() {
3388 double redirty_logged_cards_start = os::elapsedTime();
3389
3390 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3391 dirty_card_queue_set().reset_for_par_iteration();
3392 workers()->run_task(&redirty_task);
3393
3394 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3395 dcq.merge_bufferlists(&dirty_card_queue_set());
3396 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3397
3398 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3399 }
3400
3401 // Weak Reference Processing support
3402
3403 bool G1STWIsAliveClosure::do_object_b(oop p) {
3404 // An object is reachable if it is outside the collection set,
3405 // or is inside and copied.
3406 return !_g1h->is_in_cset(p) || p->is_forwarded();
3407 }
3408
3409 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3410 assert(obj != NULL, "must not be NULL");
3411 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3412 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3413 // may falsely indicate that this is not the case here: however the collection set only
3414 // contains old regions when concurrent mark is not running.
3415 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3416 }
3417
3418 // Non Copying Keep Alive closure
3419 class G1KeepAliveClosure: public OopClosure {
3420 G1CollectedHeap*_g1h;
3421 public:
3422 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3423 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3424 void do_oop(oop* p) {
3425 oop obj = *p;
3426 assert(obj != NULL, "the caller should have filtered out NULL values");
3427
3428 const InCSetState cset_state =_g1h->in_cset_state(obj);
3429 if (!cset_state.is_in_cset_or_humongous()) {
3430 return;
3431 }
3432 if (cset_state.is_in_cset()) {
3433 assert( obj->is_forwarded(), "invariant" );
3434 *p = obj->forwardee();
3435 } else {
3436 assert(!obj->is_forwarded(), "invariant" );
3437 assert(cset_state.is_humongous(),
3438 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3439 _g1h->set_humongous_is_live(obj);
3440 }
3441 }
3442 };
3443
3444 // Copying Keep Alive closure - can be called from both
3445 // serial and parallel code as long as different worker
3446 // threads utilize different G1ParScanThreadState instances
3447 // and different queues.
3448
3449 class G1CopyingKeepAliveClosure: public OopClosure {
3450 G1CollectedHeap* _g1h;
3451 G1ParScanThreadState* _par_scan_state;
3452
3453 public:
3454 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3455 G1ParScanThreadState* pss):
3456 _g1h(g1h),
3457 _par_scan_state(pss)
3458 {}
3459
3460 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3461 virtual void do_oop( oop* p) { do_oop_work(p); }
3462
3463 template <class T> void do_oop_work(T* p) {
3464 oop obj = RawAccess<>::oop_load(p);
3465
3466 if (_g1h->is_in_cset_or_humongous(obj)) {
3467 // If the referent object has been forwarded (either copied
3468 // to a new location or to itself in the event of an
3469 // evacuation failure) then we need to update the reference
3470 // field and, if both reference and referent are in the G1
3471 // heap, update the RSet for the referent.
3472 //
3473 // If the referent has not been forwarded then we have to keep
3474 // it alive by policy. Therefore we have copy the referent.
3475 //
3476 // When the queue is drained (after each phase of reference processing)
3477 // the object and it's followers will be copied, the reference field set
3478 // to point to the new location, and the RSet updated.
3479 _par_scan_state->push_on_queue(p);
3480 }
3481 }
3482 };
3483
3484 // Serial drain queue closure. Called as the 'complete_gc'
3485 // closure for each discovered list in some of the
3486 // reference processing phases.
3487
3488 class G1STWDrainQueueClosure: public VoidClosure {
3489 protected:
3490 G1CollectedHeap* _g1h;
3491 G1ParScanThreadState* _par_scan_state;
3492
3493 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3494
3495 public:
3496 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3497 _g1h(g1h),
3498 _par_scan_state(pss)
3499 { }
3500
3501 void do_void() {
3502 G1ParScanThreadState* const pss = par_scan_state();
3503 pss->trim_queue();
3504 }
3505 };
3506
3507 // Parallel Reference Processing closures
3508
3509 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3510 // processing during G1 evacuation pauses.
3511
3512 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3513 private:
3514 G1CollectedHeap* _g1h;
3515 G1ParScanThreadStateSet* _pss;
3516 RefToScanQueueSet* _queues;
3517 WorkGang* _workers;
3518
3519 public:
3520 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3521 G1ParScanThreadStateSet* per_thread_states,
3522 WorkGang* workers,
3523 RefToScanQueueSet *task_queues) :
3524 _g1h(g1h),
3525 _pss(per_thread_states),
3526 _queues(task_queues),
3527 _workers(workers)
3528 {
3529 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3530 }
3531
3532 // Executes the given task using concurrent marking worker threads.
3533 virtual void execute(ProcessTask& task, uint ergo_workers);
3534 };
3535
3536 // Gang task for possibly parallel reference processing
3537
3538 class G1STWRefProcTaskProxy: public AbstractGangTask {
3539 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3540 ProcessTask& _proc_task;
3541 G1CollectedHeap* _g1h;
3542 G1ParScanThreadStateSet* _pss;
3543 RefToScanQueueSet* _task_queues;
3544 ParallelTaskTerminator* _terminator;
3545
3546 public:
3547 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3548 G1CollectedHeap* g1h,
3549 G1ParScanThreadStateSet* per_thread_states,
3550 RefToScanQueueSet *task_queues,
3551 ParallelTaskTerminator* terminator) :
3552 AbstractGangTask("Process reference objects in parallel"),
3553 _proc_task(proc_task),
3554 _g1h(g1h),
3555 _pss(per_thread_states),
3556 _task_queues(task_queues),
3557 _terminator(terminator)
3558 {}
3559
3560 virtual void work(uint worker_id) {
3561 // The reference processing task executed by a single worker.
3562 ResourceMark rm;
3563 HandleMark hm;
3564
3565 G1STWIsAliveClosure is_alive(_g1h);
3566
3567 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3568 pss->set_ref_discoverer(NULL);
3569
3570 // Keep alive closure.
3571 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3572
3573 // Complete GC closure
3574 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3575
3576 // Call the reference processing task's work routine.
3577 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3578
3579 // Note we cannot assert that the refs array is empty here as not all
3580 // of the processing tasks (specifically phase2 - pp2_work) execute
3581 // the complete_gc closure (which ordinarily would drain the queue) so
3582 // the queue may not be empty.
3583 }
3584 };
3585
3586 // Driver routine for parallel reference processing.
3587 // Creates an instance of the ref processing gang
3588 // task and has the worker threads execute it.
3589 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3590 assert(_workers != NULL, "Need parallel worker threads.");
3591
3592 assert(_workers->active_workers() >= ergo_workers,
3593 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3594 ergo_workers, _workers->active_workers());
3595 ParallelTaskTerminator terminator(ergo_workers, _queues);
3596 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3597
3598 _workers->run_task(&proc_task_proxy, ergo_workers);
3599 }
3600
3601 // End of weak reference support closures
3602
3603 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3604 double ref_proc_start = os::elapsedTime();
3605
3606 ReferenceProcessor* rp = _ref_processor_stw;
3607 assert(rp->discovery_enabled(), "should have been enabled");
3608
3609 // Closure to test whether a referent is alive.
3610 G1STWIsAliveClosure is_alive(this);
3611
3612 // Even when parallel reference processing is enabled, the processing
3613 // of JNI refs is serial and performed serially by the current thread
3614 // rather than by a worker. The following PSS will be used for processing
3615 // JNI refs.
3616
3617 // Use only a single queue for this PSS.
3618 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3619 pss->set_ref_discoverer(NULL);
3620 assert(pss->queue_is_empty(), "pre-condition");
3621
3622 // Keep alive closure.
3623 G1CopyingKeepAliveClosure keep_alive(this, pss);
3624
3625 // Serial Complete GC closure
3626 G1STWDrainQueueClosure drain_queue(this, pss);
3627
3628 // Setup the soft refs policy...
3629 rp->setup_policy(false);
3630
3631 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3632
3633 ReferenceProcessorStats stats;
3634 if (!rp->processing_is_mt()) {
3635 // Serial reference processing...
3636 stats = rp->process_discovered_references(&is_alive,
3637 &keep_alive,
3638 &drain_queue,
3639 NULL,
3640 pt);
3641 } else {
3642 uint no_of_gc_workers = workers()->active_workers();
3643
3644 // Parallel reference processing
3645 assert(no_of_gc_workers <= rp->max_num_queues(),
3646 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3647 no_of_gc_workers, rp->max_num_queues());
3648
3649 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3650 stats = rp->process_discovered_references(&is_alive,
3651 &keep_alive,
3652 &drain_queue,
3653 &par_task_executor,
3654 pt);
3655 }
3656
3657 _gc_tracer_stw->report_gc_reference_stats(stats);
3658
3659 // We have completed copying any necessary live referent objects.
3660 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3661
3662 make_pending_list_reachable();
3663
3664 rp->verify_no_references_recorded();
3665
3666 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3667 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3668 }
3669
3670 void G1CollectedHeap::make_pending_list_reachable() {
3671 if (collector_state()->in_initial_mark_gc()) {
3672 oop pll_head = Universe::reference_pending_list();
3673 if (pll_head != NULL) {
3674 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3675 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3676 }
3677 }
3678 }
3679
3680 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3681 double merge_pss_time_start = os::elapsedTime();
3682 per_thread_states->flush();
3683 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3684 }
3685
3686 void G1CollectedHeap::pre_evacuate_collection_set() {
3687 _expand_heap_after_alloc_failure = true;
3688 _evacuation_failed = false;
3689
3690 // Disable the hot card cache.
3691 _hot_card_cache->reset_hot_cache_claimed_index();
3692 _hot_card_cache->set_use_cache(false);
3693
3694 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3695 _preserved_marks_set.assert_empty();
3696
3697 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3698
3699 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3700 if (collector_state()->in_initial_mark_gc()) {
3701 double start_clear_claimed_marks = os::elapsedTime();
3702
3703 ClassLoaderDataGraph::clear_claimed_marks();
3704
3705 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3706 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3707 }
3708 }
3709
3710 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3711 // Should G1EvacuationFailureALot be in effect for this GC?
3712 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3713
3714 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3715
3716 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3717
3718 double start_par_time_sec = os::elapsedTime();
3719 double end_par_time_sec;
3720
3721 {
3722 const uint n_workers = workers()->active_workers();
3723 G1RootProcessor root_processor(this, n_workers);
3724 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3725
3726 print_termination_stats_hdr();
3727
3728 workers()->run_task(&g1_par_task);
3729 end_par_time_sec = os::elapsedTime();
3730
3731 // Closing the inner scope will execute the destructor
3732 // for the G1RootProcessor object. We record the current
3733 // elapsed time before closing the scope so that time
3734 // taken for the destructor is NOT included in the
3735 // reported parallel time.
3736 }
3737
3738 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3739 phase_times->record_par_time(par_time_ms);
3740
3741 double code_root_fixup_time_ms =
3742 (os::elapsedTime() - end_par_time_sec) * 1000.0;
3743 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3744 }
3745
3746 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3747 // Also cleans the card table from temporary duplicate detection information used
3748 // during UpdateRS/ScanRS.
3749 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3750
3751 // Process any discovered reference objects - we have
3752 // to do this _before_ we retire the GC alloc regions
3753 // as we may have to copy some 'reachable' referent
3754 // objects (and their reachable sub-graphs) that were
3755 // not copied during the pause.
3756 process_discovered_references(per_thread_states);
3757
3758 // FIXME
3759 // CM's reference processing also cleans up the string table.
3760 // Should we do that here also? We could, but it is a serial operation
3761 // and could significantly increase the pause time.
3762
3763 G1STWIsAliveClosure is_alive(this);
3764 G1KeepAliveClosure keep_alive(this);
3765
3766 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3767 g1_policy()->phase_times()->weak_phase_times());
3768
3769 if (G1StringDedup::is_enabled()) {
3770 double fixup_start = os::elapsedTime();
3771
3772 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
3773
3774 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
3775 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
3776 }
3777
3778 if (evacuation_failed()) {
3779 restore_after_evac_failure();
3780
3781 // Reset the G1EvacuationFailureALot counters and flags
3782 // Note: the values are reset only when an actual
3783 // evacuation failure occurs.
3784 NOT_PRODUCT(reset_evacuation_should_fail();)
3785 }
3786
3787 _preserved_marks_set.assert_empty();
3788
3789 _allocator->release_gc_alloc_regions(evacuation_info);
3790
3791 merge_per_thread_state_info(per_thread_states);
3792
3793 // Reset and re-enable the hot card cache.
3794 // Note the counts for the cards in the regions in the
3795 // collection set are reset when the collection set is freed.
3796 _hot_card_cache->reset_hot_cache();
3797 _hot_card_cache->set_use_cache(true);
3798
3799 purge_code_root_memory();
3800
3801 redirty_logged_cards();
3802 #if COMPILER2_OR_JVMCI
3803 double start = os::elapsedTime();
3804 DerivedPointerTable::update_pointers();
3805 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3806 #endif
3807 g1_policy()->print_age_table();
3808 }
3809
3810 void G1CollectedHeap::record_obj_copy_mem_stats() {
3811 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3812
3813 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3814 create_g1_evac_summary(&_old_evac_stats));
3815 }
3816
3817 void G1CollectedHeap::free_region(HeapRegion* hr,
3818 FreeRegionList* free_list,
3819 bool skip_remset,
3820 bool skip_hot_card_cache,
3821 bool locked) {
3822 assert(!hr->is_free(), "the region should not be free");
3823 assert(!hr->is_empty(), "the region should not be empty");
3824 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3825 assert(free_list != NULL, "pre-condition");
3826
3827 if (G1VerifyBitmaps) {
3828 MemRegion mr(hr->bottom(), hr->end());
3829 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3830 }
3831
3832 // Clear the card counts for this region.
3833 // Note: we only need to do this if the region is not young
3834 // (since we don't refine cards in young regions).
3835 if (!skip_hot_card_cache && !hr->is_young()) {
3836 _hot_card_cache->reset_card_counts(hr);
3837 }
3838 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3839 _g1_policy->remset_tracker()->update_at_free(hr);
3840 free_list->add_ordered(hr);
3841 }
3842
3843 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3844 FreeRegionList* free_list) {
3845 assert(hr->is_humongous(), "this is only for humongous regions");
3846 assert(free_list != NULL, "pre-condition");
3847 hr->clear_humongous();
3848 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3849 }
3850
3851 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3852 const uint humongous_regions_removed) {
3853 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3854 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3855 _old_set.bulk_remove(old_regions_removed);
3856 _humongous_set.bulk_remove(humongous_regions_removed);
3857 }
3858
3859 }
3860
3861 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3862 assert(list != NULL, "list can't be null");
3863 if (!list->is_empty()) {
3864 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3865 _hrm->insert_list_into_free_list(list);
3866 }
3867 }
3868
3869 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3870 decrease_used(bytes);
3871 }
3872
3873 class G1FreeCollectionSetTask : public AbstractGangTask {
3874 private:
3875
3876 // Closure applied to all regions in the collection set to do work that needs to
3877 // be done serially in a single thread.
3878 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3879 private:
3880 EvacuationInfo* _evacuation_info;
3881 const size_t* _surviving_young_words;
3882
3883 // Bytes used in successfully evacuated regions before the evacuation.
3884 size_t _before_used_bytes;
3885 // Bytes used in unsucessfully evacuated regions before the evacuation
3886 size_t _after_used_bytes;
3887
3888 size_t _bytes_allocated_in_old_since_last_gc;
3889
3890 size_t _failure_used_words;
3891 size_t _failure_waste_words;
3892
3893 FreeRegionList _local_free_list;
3894 public:
3895 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3896 HeapRegionClosure(),
3897 _evacuation_info(evacuation_info),
3898 _surviving_young_words(surviving_young_words),
3899 _before_used_bytes(0),
3900 _after_used_bytes(0),
3901 _bytes_allocated_in_old_since_last_gc(0),
3902 _failure_used_words(0),
3903 _failure_waste_words(0),
3904 _local_free_list("Local Region List for CSet Freeing") {
3905 }
3906
3907 virtual bool do_heap_region(HeapRegion* r) {
3908 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3909
3910 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3911 g1h->clear_in_cset(r);
3912
3913 if (r->is_young()) {
3914 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3915 "Young index %d is wrong for region %u of type %s with %u young regions",
3916 r->young_index_in_cset(),
3917 r->hrm_index(),
3918 r->get_type_str(),
3919 g1h->collection_set()->young_region_length());
3920 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3921 r->record_surv_words_in_group(words_survived);
3922 }
3923
3924 if (!r->evacuation_failed()) {
3925 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
3926 _before_used_bytes += r->used();
3927 g1h->free_region(r,
3928 &_local_free_list,
3929 true, /* skip_remset */
3930 true, /* skip_hot_card_cache */
3931 true /* locked */);
3932 } else {
3933 r->uninstall_surv_rate_group();
3934 r->set_young_index_in_cset(-1);
3935 r->set_evacuation_failed(false);
3936 // When moving a young gen region to old gen, we "allocate" that whole region
3937 // there. This is in addition to any already evacuated objects. Notify the
3938 // policy about that.
3939 // Old gen regions do not cause an additional allocation: both the objects
3940 // still in the region and the ones already moved are accounted for elsewhere.
3941 if (r->is_young()) {
3942 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
3943 }
3944 // The region is now considered to be old.
3945 if(g1h->is_hetero_heap()) {
3946 if(!r->is_old()) {
3947 // The region was young before, set it as pre-matured old so that next mixed gc can move
3948 // its contents to old region which is on nv-dimm
3949 r->set_premature_old();
3950 }
3951 } else {
3952 r->set_old();
3953 }
3954 // Do some allocation statistics accounting. Regions that failed evacuation
3955 // are always made old, so there is no need to update anything in the young
3956 // gen statistics, but we need to update old gen statistics.
3957 size_t used_words = r->marked_bytes() / HeapWordSize;
3958
3959 _failure_used_words += used_words;
3960 _failure_waste_words += HeapRegion::GrainWords - used_words;
3961
3962 g1h->old_set_add(r);
3963 _after_used_bytes += r->used();
3964 }
3965 return false;
3966 }
3967
3968 void complete_work() {
3969 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3970
3971 _evacuation_info->set_regions_freed(_local_free_list.length());
3972 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
3973
3974 g1h->prepend_to_freelist(&_local_free_list);
3975 g1h->decrement_summary_bytes(_before_used_bytes);
3976
3977 G1Policy* policy = g1h->g1_policy();
3978 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
3979
3980 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
3981 }
3982 };
3983
3984 G1CollectionSet* _collection_set;
3985 G1SerialFreeCollectionSetClosure _cl;
3986 const size_t* _surviving_young_words;
3987
3988 size_t _rs_lengths;
3989
3990 volatile jint _serial_work_claim;
3991
3992 struct WorkItem {
3993 uint region_idx;
3994 bool is_young;
3995 bool evacuation_failed;
3996
3997 WorkItem(HeapRegion* r) {
3998 region_idx = r->hrm_index();
3999 is_young = r->is_young();
4000 evacuation_failed = r->evacuation_failed();
4001 }
4002 };
4003
4004 volatile size_t _parallel_work_claim;
4005 size_t _num_work_items;
4006 WorkItem* _work_items;
4007
4008 void do_serial_work() {
4009 // Need to grab the lock to be allowed to modify the old region list.
4010 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4011 _collection_set->iterate(&_cl);
4012 }
4013
4014 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4015 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4016
4017 HeapRegion* r = g1h->region_at(region_idx);
4018 assert(!g1h->is_on_master_free_list(r), "sanity");
4019
4020 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4021
4022 if (!is_young) {
4023 g1h->_hot_card_cache->reset_card_counts(r);
4024 }
4025
4026 if (!evacuation_failed) {
4027 r->rem_set()->clear_locked();
4028 }
4029 }
4030
4031 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4032 private:
4033 size_t _cur_idx;
4034 WorkItem* _work_items;
4035 public:
4036 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4037
4038 virtual bool do_heap_region(HeapRegion* r) {
4039 _work_items[_cur_idx++] = WorkItem(r);
4040 return false;
4041 }
4042 };
4043
4044 void prepare_work() {
4045 G1PrepareFreeCollectionSetClosure cl(_work_items);
4046 _collection_set->iterate(&cl);
4047 }
4048
4049 void complete_work() {
4050 _cl.complete_work();
4051
4052 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4053 policy->record_max_rs_lengths(_rs_lengths);
4054 policy->cset_regions_freed();
4055 }
4056 public:
4057 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4058 AbstractGangTask("G1 Free Collection Set"),
4059 _collection_set(collection_set),
4060 _cl(evacuation_info, surviving_young_words),
4061 _surviving_young_words(surviving_young_words),
4062 _rs_lengths(0),
4063 _serial_work_claim(0),
4064 _parallel_work_claim(0),
4065 _num_work_items(collection_set->region_length()),
4066 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4067 prepare_work();
4068 }
4069
4070 ~G1FreeCollectionSetTask() {
4071 complete_work();
4072 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4073 }
4074
4075 // Chunk size for work distribution. The chosen value has been determined experimentally
4076 // to be a good tradeoff between overhead and achievable parallelism.
4077 static uint chunk_size() { return 32; }
4078
4079 virtual void work(uint worker_id) {
4080 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4081
4082 // Claim serial work.
4083 if (_serial_work_claim == 0) {
4084 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4085 if (value == 0) {
4086 double serial_time = os::elapsedTime();
4087 do_serial_work();
4088 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4089 }
4090 }
4091
4092 // Start parallel work.
4093 double young_time = 0.0;
4094 bool has_young_time = false;
4095 double non_young_time = 0.0;
4096 bool has_non_young_time = false;
4097
4098 while (true) {
4099 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4100 size_t cur = end - chunk_size();
4101
4102 if (cur >= _num_work_items) {
4103 break;
4104 }
4105
4106 EventGCPhaseParallel event;
4107 double start_time = os::elapsedTime();
4108
4109 end = MIN2(end, _num_work_items);
4110
4111 for (; cur < end; cur++) {
4112 bool is_young = _work_items[cur].is_young;
4113
4114 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4115
4116 double end_time = os::elapsedTime();
4117 double time_taken = end_time - start_time;
4118 if (is_young) {
4119 young_time += time_taken;
4120 has_young_time = true;
4121 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4122 } else {
4123 non_young_time += time_taken;
4124 has_non_young_time = true;
4125 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4126 }
4127 start_time = end_time;
4128 }
4129 }
4130
4131 if (has_young_time) {
4132 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4133 }
4134 if (has_non_young_time) {
4135 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4136 }
4137 }
4138 };
4139
4140 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4141 _eden.clear();
4142
4143 double free_cset_start_time = os::elapsedTime();
4144
4145 {
4146 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4147 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4148
4149 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4150
4151 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4152 cl.name(),
4153 num_workers,
4154 _collection_set.region_length());
4155 workers()->run_task(&cl, num_workers);
4156 }
4157 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4158
4159 collection_set->clear();
4160 }
4161
4162 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4163 private:
4164 FreeRegionList* _free_region_list;
4165 HeapRegionSet* _proxy_set;
4166 uint _humongous_objects_reclaimed;
4167 uint _humongous_regions_reclaimed;
4168 size_t _freed_bytes;
4169 public:
4170
4171 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4172 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4173 }
4174
4175 virtual bool do_heap_region(HeapRegion* r) {
4176 if (!r->is_starts_humongous()) {
4177 return false;
4178 }
4179
4180 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4181
4182 oop obj = (oop)r->bottom();
4183 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4184
4185 // The following checks whether the humongous object is live are sufficient.
4186 // The main additional check (in addition to having a reference from the roots
4187 // or the young gen) is whether the humongous object has a remembered set entry.
4188 //
4189 // A humongous object cannot be live if there is no remembered set for it
4190 // because:
4191 // - there can be no references from within humongous starts regions referencing
4192 // the object because we never allocate other objects into them.
4193 // (I.e. there are no intra-region references that may be missed by the
4194 // remembered set)
4195 // - as soon there is a remembered set entry to the humongous starts region
4196 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4197 // until the end of a concurrent mark.
4198 //
4199 // It is not required to check whether the object has been found dead by marking
4200 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4201 // all objects allocated during that time are considered live.
4202 // SATB marking is even more conservative than the remembered set.
4203 // So if at this point in the collection there is no remembered set entry,
4204 // nobody has a reference to it.
4205 // At the start of collection we flush all refinement logs, and remembered sets
4206 // are completely up-to-date wrt to references to the humongous object.
4207 //
4208 // Other implementation considerations:
4209 // - never consider object arrays at this time because they would pose
4210 // considerable effort for cleaning up the the remembered sets. This is
4211 // required because stale remembered sets might reference locations that
4212 // are currently allocated into.
4213 uint region_idx = r->hrm_index();
4214 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4215 !r->rem_set()->is_empty()) {
4216 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",
4217 region_idx,
4218 (size_t)obj->size() * HeapWordSize,
4219 p2i(r->bottom()),
4220 r->rem_set()->occupied(),
4221 r->rem_set()->strong_code_roots_list_length(),
4222 next_bitmap->is_marked(r->bottom()),
4223 g1h->is_humongous_reclaim_candidate(region_idx),
4224 obj->is_typeArray()
4225 );
4226 return false;
4227 }
4228
4229 guarantee(obj->is_typeArray(),
4230 "Only eagerly reclaiming type arrays is supported, but the object "
4231 PTR_FORMAT " is not.", p2i(r->bottom()));
4232
4233 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",
4234 region_idx,
4235 (size_t)obj->size() * HeapWordSize,
4236 p2i(r->bottom()),
4237 r->rem_set()->occupied(),
4238 r->rem_set()->strong_code_roots_list_length(),
4239 next_bitmap->is_marked(r->bottom()),
4240 g1h->is_humongous_reclaim_candidate(region_idx),
4241 obj->is_typeArray()
4242 );
4243
4244 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4245 cm->humongous_object_eagerly_reclaimed(r);
4246 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4247 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4248 region_idx,
4249 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4250 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4251 _humongous_objects_reclaimed++;
4252 do {
4253 HeapRegion* next = g1h->next_region_in_humongous(r);
4254 _freed_bytes += r->used();
4255 r->set_containing_set(NULL);
4256 _humongous_regions_reclaimed++;
4257 g1h->free_humongous_region(r, _free_region_list);
4258 r = next;
4259 } while (r != NULL);
4260
4261 return false;
4262 }
4263
4264 uint humongous_objects_reclaimed() {
4265 return _humongous_objects_reclaimed;
4266 }
4267
4268 uint humongous_regions_reclaimed() {
4269 return _humongous_regions_reclaimed;
4270 }
4271
4272 size_t bytes_freed() const {
4273 return _freed_bytes;
4274 }
4275 };
4276
4277 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4278 assert_at_safepoint_on_vm_thread();
4279
4280 if (!G1EagerReclaimHumongousObjects ||
4281 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4282 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4283 return;
4284 }
4285
4286 double start_time = os::elapsedTime();
4287
4288 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4289
4290 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4291 heap_region_iterate(&cl);
4292
4293 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4294
4295 G1HRPrinter* hrp = hr_printer();
4296 if (hrp->is_active()) {
4297 FreeRegionListIterator iter(&local_cleanup_list);
4298 while (iter.more_available()) {
4299 HeapRegion* hr = iter.get_next();
4300 hrp->cleanup(hr);
4301 }
4302 }
4303
4304 prepend_to_freelist(&local_cleanup_list);
4305 decrement_summary_bytes(cl.bytes_freed());
4306
4307 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4308 cl.humongous_objects_reclaimed());
4309 }
4310
4311 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4312 public:
4313 virtual bool do_heap_region(HeapRegion* r) {
4314 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4315 G1CollectedHeap::heap()->clear_in_cset(r);
4316 r->set_young_index_in_cset(-1);
4317 return false;
4318 }
4319 };
4320
4321 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4322 G1AbandonCollectionSetClosure cl;
4323 collection_set->iterate(&cl);
4324
4325 collection_set->clear();
4326 collection_set->stop_incremental_building();
4327 }
4328
4329 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4330 return _allocator->is_retained_old_region(hr);
4331 }
4332
4333 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4334 _eden.add(hr);
4335 _g1_policy->set_region_eden(hr);
4336 }
4337
4338 #ifdef ASSERT
4339
4340 class NoYoungRegionsClosure: public HeapRegionClosure {
4341 private:
4342 bool _success;
4343 public:
4344 NoYoungRegionsClosure() : _success(true) { }
4345 bool do_heap_region(HeapRegion* r) {
4346 if (r->is_young()) {
4347 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4348 p2i(r->bottom()), p2i(r->end()));
4349 _success = false;
4350 }
4351 return false;
4352 }
4353 bool success() { return _success; }
4354 };
4355
4356 bool G1CollectedHeap::check_young_list_empty() {
4357 bool ret = (young_regions_count() == 0);
4358
4359 NoYoungRegionsClosure closure;
4360 heap_region_iterate(&closure);
4361 ret = ret && closure.success();
4362
4363 return ret;
4364 }
4365
4366 #endif // ASSERT
4367
4368 class TearDownRegionSetsClosure : public HeapRegionClosure {
4369 HeapRegionSet *_old_set;
4370
4371 public:
4372 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4373
4374 bool do_heap_region(HeapRegion* r) {
4375 if (r->is_old()) {
4376 _old_set->remove(r);
4377 } else if(r->is_young()) {
4378 r->uninstall_surv_rate_group();
4379 } else {
4380 // We ignore free regions, we'll empty the free list afterwards.
4381 // We ignore humongous and archive regions, we're not tearing down these
4382 // sets.
4383 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4384 "it cannot be another type");
4385 }
4386 return false;
4387 }
4388
4389 ~TearDownRegionSetsClosure() {
4390 assert(_old_set->is_empty(), "post-condition");
4391 }
4392 };
4393
4394 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4395 assert_at_safepoint_on_vm_thread();
4396
4397 if (!free_list_only) {
4398 TearDownRegionSetsClosure cl(&_old_set);
4399 heap_region_iterate(&cl);
4400
4401 // Note that emptying the _young_list is postponed and instead done as
4402 // the first step when rebuilding the regions sets again. The reason for
4403 // this is that during a full GC string deduplication needs to know if
4404 // a collected region was young or old when the full GC was initiated.
4405 }
4406 _hrm->remove_all_free_regions();
4407 }
4408
4409 void G1CollectedHeap::increase_used(size_t bytes) {
4410 _summary_bytes_used += bytes;
4411 }
4412
4413 void G1CollectedHeap::decrease_used(size_t bytes) {
4414 assert(_summary_bytes_used >= bytes,
4415 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4416 _summary_bytes_used, bytes);
4417 _summary_bytes_used -= bytes;
4418 }
4419
4420 void G1CollectedHeap::set_used(size_t bytes) {
4421 _summary_bytes_used = bytes;
4422 }
4423
4424 class RebuildRegionSetsClosure : public HeapRegionClosure {
4425 private:
4426 bool _free_list_only;
4427
4428 HeapRegionSet* _old_set;
4429 HeapRegionManager* _hrm;
4430
4431 size_t _total_used;
4432
4433 public:
4434 RebuildRegionSetsClosure(bool free_list_only,
4435 HeapRegionSet* old_set,
4436 HeapRegionManager* hrm) :
4437 _free_list_only(free_list_only),
4438 _old_set(old_set), _hrm(hrm), _total_used(0) {
4439 assert(_hrm->num_free_regions() == 0, "pre-condition");
4440 if (!free_list_only) {
4441 assert(_old_set->is_empty(), "pre-condition");
4442 }
4443 }
4444
4445 bool do_heap_region(HeapRegion* r) {
4446 if (r->is_empty()) {
4447 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4448 // Add free regions to the free list
4449 r->set_free();
4450 _hrm->insert_into_free_list(r);
4451 } else if (!_free_list_only) {
4452 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4453
4454 if (r->is_archive() || r->is_humongous()) {
4455 // We ignore archive and humongous regions. We left these sets unchanged.
4456 } else {
4457 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4458 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4459 r->move_to_old();
4460 _old_set->add(r);
4461 }
4462 _total_used += r->used();
4463 }
4464
4465 return false;
4466 }
4467
4468 size_t total_used() {
4469 return _total_used;
4470 }
4471 };
4472
4473 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4474 assert_at_safepoint_on_vm_thread();
4475
4476 if (!free_list_only) {
4477 _eden.clear();
4478 _survivor.clear();
4479 }
4480
4481 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4482 heap_region_iterate(&cl);
4483
4484 if (!free_list_only) {
4485 set_used(cl.total_used());
4486 if (_archive_allocator != NULL) {
4487 _archive_allocator->clear_used();
4488 }
4489 }
4490 assert(used() == recalculate_used(),
4491 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4492 used(), recalculate_used());
4493 }
4494
4495 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4496 HeapRegion* hr = heap_region_containing(p);
4497 return hr->is_in(p);
4498 }
4499
4500 // Methods for the mutator alloc region
4501
4502 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4503 bool force) {
4504 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4505 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4506 if (force || should_allocate) {
4507 HeapRegion* new_alloc_region = new_region(word_size,
4508 false /* is_old */,
4509 false /* do_expand */);
4510 if (new_alloc_region != NULL) {
4511 set_region_short_lived_locked(new_alloc_region);
4512 _hr_printer.alloc(new_alloc_region, !should_allocate);
4513 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4514 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4515 return new_alloc_region;
4516 }
4517 }
4518 return NULL;
4519 }
4520
4521 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4522 size_t allocated_bytes) {
4523 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4524 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4525
4526 collection_set()->add_eden_region(alloc_region);
4527 increase_used(allocated_bytes);
4528 _hr_printer.retire(alloc_region);
4529 // We update the eden sizes here, when the region is retired,
4530 // instead of when it's allocated, since this is the point that its
4531 // used space has been recorded in _summary_bytes_used.
4532 g1mm()->update_eden_size();
4533 }
4534
4535 // Methods for the GC alloc regions
4536
4537 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4538 if (dest.is_old()) {
4539 return true;
4540 } else {
4541 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4542 }
4543 }
4544
4545 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4546 assert(FreeList_lock->owned_by_self(), "pre-condition");
4547
4548 if (!has_more_regions(dest)) {
4549 return NULL;
4550 }
4551
4552 const bool is_survivor = dest.is_young();
4553
4554 HeapRegion* new_alloc_region = new_region(word_size,
4555 !is_survivor,
4556 true /* do_expand */);
4557 if (new_alloc_region != NULL) {
4558 if (is_survivor) {
4559 new_alloc_region->set_survivor();
4560 _survivor.add(new_alloc_region);
4561 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4562 } else {
4563 new_alloc_region->set_old();
4564 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4565 }
4566 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4567 _hr_printer.alloc(new_alloc_region);
4568 bool during_im = collector_state()->in_initial_mark_gc();
4569 new_alloc_region->note_start_of_copying(during_im);
4570 return new_alloc_region;
4571 }
4572 return NULL;
4573 }
4574
4575 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4576 size_t allocated_bytes,
4577 InCSetState dest) {
4578 bool during_im = collector_state()->in_initial_mark_gc();
4579 alloc_region->note_end_of_copying(during_im);
4580 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4581 if (dest.is_old()) {
4582 old_set_add(alloc_region);
4583 }
4584 _hr_printer.retire(alloc_region);
4585 }
4586
4587 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4588 bool expanded = false;
4589 uint index = _hrm->find_highest_free(&expanded);
4590
4591 if (index != G1_NO_HRM_INDEX) {
4592 if (expanded) {
4593 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4594 HeapRegion::GrainWords * HeapWordSize);
4595 }
4596 _hrm->allocate_free_regions_starting_at(index, 1);
4597 return region_at(index);
4598 }
4599 return NULL;
4600 }
4601
4602 // Optimized nmethod scanning
4603
4604 class RegisterNMethodOopClosure: public OopClosure {
4605 G1CollectedHeap* _g1h;
4606 nmethod* _nm;
4607
4608 template <class T> void do_oop_work(T* p) {
4609 T heap_oop = RawAccess<>::oop_load(p);
4610 if (!CompressedOops::is_null(heap_oop)) {
4611 oop obj = CompressedOops::decode_not_null(heap_oop);
4612 HeapRegion* hr = _g1h->heap_region_containing(obj);
4613 assert(!hr->is_continues_humongous(),
4614 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4615 " starting at " HR_FORMAT,
4616 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4617
4618 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4619 hr->add_strong_code_root_locked(_nm);
4620 }
4621 }
4622
4623 public:
4624 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4625 _g1h(g1h), _nm(nm) {}
4626
4627 void do_oop(oop* p) { do_oop_work(p); }
4628 void do_oop(narrowOop* p) { do_oop_work(p); }
4629 };
4630
4631 class UnregisterNMethodOopClosure: public OopClosure {
4632 G1CollectedHeap* _g1h;
4633 nmethod* _nm;
4634
4635 template <class T> void do_oop_work(T* p) {
4636 T heap_oop = RawAccess<>::oop_load(p);
4637 if (!CompressedOops::is_null(heap_oop)) {
4638 oop obj = CompressedOops::decode_not_null(heap_oop);
4639 HeapRegion* hr = _g1h->heap_region_containing(obj);
4640 assert(!hr->is_continues_humongous(),
4641 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4642 " starting at " HR_FORMAT,
4643 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4644
4645 hr->remove_strong_code_root(_nm);
4646 }
4647 }
4648
4649 public:
4650 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4651 _g1h(g1h), _nm(nm) {}
4652
4653 void do_oop(oop* p) { do_oop_work(p); }
4654 void do_oop(narrowOop* p) { do_oop_work(p); }
4655 };
4656
4657 // Returns true if the reference points to an object that
4658 // can move in an incremental collection.
4659 bool G1CollectedHeap::is_scavengable(oop obj) {
4660 HeapRegion* hr = heap_region_containing(obj);
4661 return !hr->is_pinned();
4662 }
4663
4664 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4665 guarantee(nm != NULL, "sanity");
4666 RegisterNMethodOopClosure reg_cl(this, nm);
4667 nm->oops_do(®_cl);
4668 }
4669
4670 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4671 guarantee(nm != NULL, "sanity");
4672 UnregisterNMethodOopClosure reg_cl(this, nm);
4673 nm->oops_do(®_cl, true);
4674 }
4675
4676 void G1CollectedHeap::purge_code_root_memory() {
4677 double purge_start = os::elapsedTime();
4678 G1CodeRootSet::purge();
4679 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4680 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4681 }
4682
4683 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4684 G1CollectedHeap* _g1h;
4685
4686 public:
4687 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4688 _g1h(g1h) {}
4689
4690 void do_code_blob(CodeBlob* cb) {
4691 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4692 if (nm == NULL) {
4693 return;
4694 }
4695
4696 if (ScavengeRootsInCode) {
4697 _g1h->register_nmethod(nm);
4698 }
4699 }
4700 };
4701
4702 void G1CollectedHeap::rebuild_strong_code_roots() {
4703 RebuildStrongCodeRootClosure blob_cl(this);
4704 CodeCache::blobs_do(&blob_cl);
4705 }
4706
4707 void G1CollectedHeap::initialize_serviceability() {
4708 _g1mm->initialize_serviceability();
4709 }
4710
4711 MemoryUsage G1CollectedHeap::memory_usage() {
4712 return _g1mm->memory_usage();
4713 }
4714
4715 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4716 return _g1mm->memory_managers();
4717 }
4718
4719 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4720 return _g1mm->memory_pools();
4721 }