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/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/g1Allocator.inline.hpp"
31 #include "gc/g1/g1BarrierSet.hpp"
32 #include "gc/g1/g1CollectedHeap.inline.hpp"
33 #include "gc/g1/g1CollectionSet.hpp"
34 #include "gc/g1/g1CollectorPolicy.hpp"
35 #include "gc/g1/g1CollectorState.hpp"
36 #include "gc/g1/g1ConcurrentRefine.hpp"
37 #include "gc/g1/g1ConcurrentRefineThread.hpp"
38 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
39 #include "gc/g1/g1EvacStats.inline.hpp"
40 #include "gc/g1/g1FullCollector.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1HeapSizingPolicy.hpp"
43 #include "gc/g1/g1HeapTransition.hpp"
44 #include "gc/g1/g1HeapVerifier.hpp"
45 #include "gc/g1/g1HotCardCache.hpp"
46 #include "gc/g1/g1MemoryPool.hpp"
47 #include "gc/g1/g1OopClosures.inline.hpp"
48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc/g1/g1Policy.hpp"
50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
51 #include "gc/g1/g1RemSet.hpp"
52 #include "gc/g1/g1RootClosures.hpp"
53 #include "gc/g1/g1RootProcessor.hpp"
54 #include "gc/g1/g1SATBMarkQueueSet.hpp"
55 #include "gc/g1/g1StringDedup.hpp"
56 #include "gc/g1/g1ThreadLocalData.hpp"
57 #include "gc/g1/g1YCTypes.hpp"
58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
59 #include "gc/g1/heapRegion.inline.hpp"
60 #include "gc/g1/heapRegionRemSet.hpp"
61 #include "gc/g1/heapRegionSet.inline.hpp"
62 #include "gc/g1/vm_operations_g1.hpp"
63 #include "gc/shared/adaptiveSizePolicy.hpp"
64 #include "gc/shared/gcHeapSummary.hpp"
65 #include "gc/shared/gcId.hpp"
66 #include "gc/shared/gcLocker.hpp"
67 #include "gc/shared/gcTimer.hpp"
68 #include "gc/shared/gcTrace.hpp"
69 #include "gc/shared/gcTraceTime.inline.hpp"
70 #include "gc/shared/generationSpec.hpp"
71 #include "gc/shared/isGCActiveMark.hpp"
72 #include "gc/shared/oopStorageParState.hpp"
73 #include "gc/shared/parallelCleaning.hpp"
74 #include "gc/shared/preservedMarks.inline.hpp"
75 #include "gc/shared/suspendibleThreadSet.hpp"
76 #include "gc/shared/referenceProcessor.inline.hpp"
77 #include "gc/shared/taskqueue.inline.hpp"
78 #include "gc/shared/weakProcessor.inline.hpp"
79 #include "logging/log.hpp"
80 #include "memory/allocation.hpp"
81 #include "memory/iterator.hpp"
82 #include "memory/metaspaceShared.hpp"
83 #include "memory/resourceArea.hpp"
84 #include "oops/access.inline.hpp"
85 #include "oops/compressedOops.inline.hpp"
86 #include "oops/oop.inline.hpp"
87 #include "runtime/atomic.hpp"
88 #include "runtime/flags/flagSetting.hpp"
89 #include "runtime/handles.inline.hpp"
90 #include "runtime/init.hpp"
91 #include "runtime/orderAccess.hpp"
92 #include "runtime/threadSMR.hpp"
93 #include "runtime/vmThread.hpp"
94 #include "utilities/align.hpp"
95 #include "utilities/globalDefinitions.hpp"
96 #include "utilities/stack.inline.hpp"
97
98 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
99
100 // INVARIANTS/NOTES
101 //
102 // All allocation activity covered by the G1CollectedHeap interface is
103 // serialized by acquiring the HeapLock. This happens in mem_allocate
104 // and allocate_new_tlab, which are the "entry" points to the
105 // allocation code from the rest of the JVM. (Note that this does not
106 // apply to TLAB allocation, which is not part of this interface: it
107 // is done by clients of this interface.)
108
109 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
110 private:
111 size_t _num_dirtied;
112 G1CollectedHeap* _g1h;
113 G1CardTable* _g1_ct;
114
115 HeapRegion* region_for_card(jbyte* card_ptr) const {
116 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
117 }
118
119 bool will_become_free(HeapRegion* hr) const {
120 // A region will be freed by free_collection_set if the region is in the
121 // collection set and has not had an evacuation failure.
122 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
123 }
124
125 public:
126 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
127 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
128
129 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
130 HeapRegion* hr = region_for_card(card_ptr);
131
132 // Should only dirty cards in regions that won't be freed.
133 if (!will_become_free(hr)) {
134 *card_ptr = G1CardTable::dirty_card_val();
135 _num_dirtied++;
136 }
137
138 return true;
139 }
140
141 size_t num_dirtied() const { return _num_dirtied; }
142 };
143
144
145 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
146 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
147 }
148
149 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
150 // The from card cache is not the memory that is actually committed. So we cannot
151 // take advantage of the zero_filled parameter.
152 reset_from_card_cache(start_idx, num_regions);
153 }
154
155
156 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
157 MemRegion mr) {
158 return new HeapRegion(hrs_index, bot(), mr);
159 }
160
161 // Private methods.
162
163 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
164 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
165 "the only time we use this to allocate a humongous region is "
166 "when we are allocating a single humongous region");
167
168 HeapRegion* res = _hrm.allocate_free_region(is_old);
169
170 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
171 // Currently, only attempts to allocate GC alloc regions set
172 // do_expand to true. So, we should only reach here during a
173 // safepoint. If this assumption changes we might have to
174 // reconsider the use of _expand_heap_after_alloc_failure.
175 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
176
177 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
178 word_size * HeapWordSize);
179
180 if (expand(word_size * HeapWordSize)) {
181 // Given that expand() succeeded in expanding the heap, and we
182 // always expand the heap by an amount aligned to the heap
183 // region size, the free list should in theory not be empty.
184 // In either case allocate_free_region() will check for NULL.
185 res = _hrm.allocate_free_region(is_old);
186 } else {
187 _expand_heap_after_alloc_failure = false;
188 }
189 }
190 return res;
191 }
192
193 HeapWord*
194 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
195 uint num_regions,
196 size_t word_size) {
197 assert(first != G1_NO_HRM_INDEX, "pre-condition");
198 assert(is_humongous(word_size), "word_size should be humongous");
199 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
200
201 // Index of last region in the series.
202 uint last = first + num_regions - 1;
203
204 // We need to initialize the region(s) we just discovered. This is
205 // a bit tricky given that it can happen concurrently with
206 // refinement threads refining cards on these regions and
207 // potentially wanting to refine the BOT as they are scanning
208 // those cards (this can happen shortly after a cleanup; see CR
209 // 6991377). So we have to set up the region(s) carefully and in
210 // a specific order.
211
212 // The word size sum of all the regions we will allocate.
213 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
214 assert(word_size <= word_size_sum, "sanity");
215
216 // This will be the "starts humongous" region.
217 HeapRegion* first_hr = region_at(first);
218 // The header of the new object will be placed at the bottom of
219 // the first region.
220 HeapWord* new_obj = first_hr->bottom();
221 // This will be the new top of the new object.
222 HeapWord* obj_top = new_obj + word_size;
223
224 // First, we need to zero the header of the space that we will be
225 // allocating. When we update top further down, some refinement
226 // threads might try to scan the region. By zeroing the header we
227 // ensure that any thread that will try to scan the region will
228 // come across the zero klass word and bail out.
229 //
230 // NOTE: It would not have been correct to have used
231 // CollectedHeap::fill_with_object() and make the space look like
232 // an int array. The thread that is doing the allocation will
233 // later update the object header to a potentially different array
234 // type and, for a very short period of time, the klass and length
235 // fields will be inconsistent. This could cause a refinement
236 // thread to calculate the object size incorrectly.
237 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
238
239 // Next, pad out the unused tail of the last region with filler
240 // objects, for improved usage accounting.
241 // How many words we use for filler objects.
242 size_t word_fill_size = word_size_sum - word_size;
243
244 // How many words memory we "waste" which cannot hold a filler object.
245 size_t words_not_fillable = 0;
246
247 if (word_fill_size >= min_fill_size()) {
248 fill_with_objects(obj_top, word_fill_size);
249 } else if (word_fill_size > 0) {
250 // We have space to fill, but we cannot fit an object there.
251 words_not_fillable = word_fill_size;
252 word_fill_size = 0;
253 }
254
255 // We will set up the first region as "starts humongous". This
256 // will also update the BOT covering all the regions to reflect
257 // that there is a single object that starts at the bottom of the
258 // first region.
259 first_hr->set_starts_humongous(obj_top, word_fill_size);
260 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
261 // Then, if there are any, we will set up the "continues
262 // humongous" regions.
263 HeapRegion* hr = NULL;
264 for (uint i = first + 1; i <= last; ++i) {
265 hr = region_at(i);
266 hr->set_continues_humongous(first_hr);
267 _g1_policy->remset_tracker()->update_at_allocate(hr);
268 }
269
270 // Up to this point no concurrent thread would have been able to
271 // do any scanning on any region in this series. All the top
272 // fields still point to bottom, so the intersection between
273 // [bottom,top] and [card_start,card_end] will be empty. Before we
274 // update the top fields, we'll do a storestore to make sure that
275 // no thread sees the update to top before the zeroing of the
276 // object header and the BOT initialization.
277 OrderAccess::storestore();
278
279 // Now, we will update the top fields of the "continues humongous"
280 // regions except the last one.
281 for (uint i = first; i < last; ++i) {
282 hr = region_at(i);
283 hr->set_top(hr->end());
284 }
285
286 hr = region_at(last);
287 // If we cannot fit a filler object, we must set top to the end
288 // of the humongous object, otherwise we cannot iterate the heap
289 // and the BOT will not be complete.
290 hr->set_top(hr->end() - words_not_fillable);
291
292 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
293 "obj_top should be in last region");
294
295 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
296
297 assert(words_not_fillable == 0 ||
298 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
299 "Miscalculation in humongous allocation");
300
301 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
302
303 for (uint i = first; i <= last; ++i) {
304 hr = region_at(i);
305 _humongous_set.add(hr);
306 _hr_printer.alloc(hr);
307 }
308
309 return new_obj;
310 }
311
312 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
313 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
314 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
315 }
316
317 // If could fit into free regions w/o expansion, try.
318 // Otherwise, if can expand, do so.
319 // Otherwise, if using ex regions might help, try with ex given back.
320 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
321 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
322
323 _verifier->verify_region_sets_optional();
324
325 uint first = G1_NO_HRM_INDEX;
326 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
327
328 if (obj_regions == 1) {
329 // Only one region to allocate, try to use a fast path by directly allocating
330 // from the free lists. Do not try to expand here, we will potentially do that
331 // later.
332 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
333 if (hr != NULL) {
334 first = hr->hrm_index();
335 }
336 } else {
337 // Policy: Try only empty regions (i.e. already committed first). Maybe we
338 // are lucky enough to find some.
339 first = _hrm.find_contiguous_only_empty(obj_regions);
340 if (first != G1_NO_HRM_INDEX) {
341 _hrm.allocate_free_regions_starting_at(first, obj_regions);
342 }
343 }
344
345 if (first == G1_NO_HRM_INDEX) {
346 // Policy: We could not find enough regions for the humongous object in the
347 // free list. Look through the heap to find a mix of free and uncommitted regions.
348 // If so, try expansion.
349 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
350 if (first != G1_NO_HRM_INDEX) {
351 // We found something. Make sure these regions are committed, i.e. expand
352 // the heap. Alternatively we could do a defragmentation GC.
353 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
354 word_size * HeapWordSize);
355
356 _hrm.expand_at(first, obj_regions, workers());
357 g1_policy()->record_new_heap_size(num_regions());
358
359 #ifdef ASSERT
360 for (uint i = first; i < first + obj_regions; ++i) {
361 HeapRegion* hr = region_at(i);
362 assert(hr->is_free(), "sanity");
363 assert(hr->is_empty(), "sanity");
364 assert(is_on_master_free_list(hr), "sanity");
365 }
366 #endif
367 _hrm.allocate_free_regions_starting_at(first, obj_regions);
368 } else {
369 // Policy: Potentially trigger a defragmentation GC.
370 }
371 }
372
373 HeapWord* result = NULL;
374 if (first != G1_NO_HRM_INDEX) {
375 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
376 assert(result != NULL, "it should always return a valid result");
377
378 // A successful humongous object allocation changes the used space
379 // information of the old generation so we need to recalculate the
380 // sizes and update the jstat counters here.
381 g1mm()->update_sizes();
382 }
383
384 _verifier->verify_region_sets_optional();
385
386 return result;
387 }
388
389 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
390 size_t requested_size,
391 size_t* actual_size) {
392 assert_heap_not_locked_and_not_at_safepoint();
393 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
394
395 return attempt_allocation(min_size, requested_size, actual_size);
396 }
397
398 HeapWord*
399 G1CollectedHeap::mem_allocate(size_t word_size,
400 bool* gc_overhead_limit_was_exceeded) {
401 assert_heap_not_locked_and_not_at_safepoint();
402
403 if (is_humongous(word_size)) {
404 return attempt_allocation_humongous(word_size);
405 }
406 size_t dummy = 0;
407 return attempt_allocation(word_size, word_size, &dummy);
408 }
409
410 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
411 ResourceMark rm; // For retrieving the thread names in log messages.
412
413 // Make sure you read the note in attempt_allocation_humongous().
414
415 assert_heap_not_locked_and_not_at_safepoint();
416 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
417 "be called for humongous allocation requests");
418
419 // We should only get here after the first-level allocation attempt
420 // (attempt_allocation()) failed to allocate.
421
422 // We will loop until a) we manage to successfully perform the
423 // allocation or b) we successfully schedule a collection which
424 // fails to perform the allocation. b) is the only case when we'll
425 // return NULL.
426 HeapWord* result = NULL;
427 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
428 bool should_try_gc;
429 uint gc_count_before;
430
431 {
432 MutexLockerEx x(Heap_lock);
433 result = _allocator->attempt_allocation_locked(word_size);
434 if (result != NULL) {
435 return result;
436 }
437
438 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
439 // This is different to when only GCLocker::needs_gc() is set: try to avoid
440 // waiting because the GCLocker is active to not wait too long.
441 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
442 // No need for an ergo message here, can_expand_young_list() does this when
443 // it returns true.
444 result = _allocator->attempt_allocation_force(word_size);
445 if (result != NULL) {
446 return result;
447 }
448 }
449 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
450 // the GCLocker initiated GC has been performed and then retry. This includes
451 // the case when the GC Locker is not active but has not been performed.
452 should_try_gc = !GCLocker::needs_gc();
453 // Read the GC count while still holding the Heap_lock.
454 gc_count_before = total_collections();
455 }
456
457 if (should_try_gc) {
458 bool succeeded;
459 result = do_collection_pause(word_size, gc_count_before, &succeeded,
460 GCCause::_g1_inc_collection_pause);
461 if (result != NULL) {
462 assert(succeeded, "only way to get back a non-NULL result");
463 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
464 Thread::current()->name(), p2i(result));
465 return result;
466 }
467
468 if (succeeded) {
469 // We successfully scheduled a collection which failed to allocate. No
470 // point in trying to allocate further. We'll just return NULL.
471 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
472 SIZE_FORMAT " words", Thread::current()->name(), word_size);
473 return NULL;
474 }
475 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
476 Thread::current()->name(), word_size);
477 } else {
478 // Failed to schedule a collection.
479 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
480 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
481 SIZE_FORMAT " words", Thread::current()->name(), word_size);
482 return NULL;
483 }
484 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
485 // The GCLocker is either active or the GCLocker initiated
486 // GC has not yet been performed. Stall until it is and
487 // then retry the allocation.
488 GCLocker::stall_until_clear();
489 gclocker_retry_count += 1;
490 }
491
492 // We can reach here if we were unsuccessful in scheduling a
493 // collection (because another thread beat us to it) or if we were
494 // stalled due to the GC locker. In either can we should retry the
495 // allocation attempt in case another thread successfully
496 // performed a collection and reclaimed enough space. We do the
497 // first attempt (without holding the Heap_lock) here and the
498 // follow-on attempt will be at the start of the next loop
499 // iteration (after taking the Heap_lock).
500 size_t dummy = 0;
501 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
502 if (result != NULL) {
503 return result;
504 }
505
506 // Give a warning if we seem to be looping forever.
507 if ((QueuedAllocationWarningCount > 0) &&
508 (try_count % QueuedAllocationWarningCount == 0)) {
509 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
510 Thread::current()->name(), try_count, word_size);
511 }
512 }
513
514 ShouldNotReachHere();
515 return NULL;
516 }
517
518 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
519 assert_at_safepoint_on_vm_thread();
520 if (_archive_allocator == NULL) {
521 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
522 }
523 }
524
525 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
526 // Allocations in archive regions cannot be of a size that would be considered
527 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
528 // may be different at archive-restore time.
529 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
530 }
531
532 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
533 assert_at_safepoint_on_vm_thread();
534 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
535 if (is_archive_alloc_too_large(word_size)) {
536 return NULL;
537 }
538 return _archive_allocator->archive_mem_allocate(word_size);
539 }
540
541 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
542 size_t end_alignment_in_bytes) {
543 assert_at_safepoint_on_vm_thread();
544 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
545
546 // Call complete_archive to do the real work, filling in the MemRegion
547 // array with the archive regions.
548 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
549 delete _archive_allocator;
550 _archive_allocator = NULL;
551 }
552
553 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
554 assert(ranges != NULL, "MemRegion array NULL");
555 assert(count != 0, "No MemRegions provided");
556 MemRegion reserved = _hrm.reserved();
557 for (size_t i = 0; i < count; i++) {
558 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
559 return false;
560 }
561 }
562 return true;
563 }
564
565 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
566 size_t count,
567 bool open) {
568 assert(!is_init_completed(), "Expect to be called at JVM init time");
569 assert(ranges != NULL, "MemRegion array NULL");
570 assert(count != 0, "No MemRegions provided");
571 MutexLockerEx x(Heap_lock);
572
573 MemRegion reserved = _hrm.reserved();
574 HeapWord* prev_last_addr = NULL;
575 HeapRegion* prev_last_region = NULL;
576
577 // Temporarily disable pretouching of heap pages. This interface is used
578 // when mmap'ing archived heap data in, so pre-touching is wasted.
579 FlagSetting fs(AlwaysPreTouch, false);
580
581 // Enable archive object checking used by G1MarkSweep. We have to let it know
582 // about each archive range, so that objects in those ranges aren't marked.
583 G1ArchiveAllocator::enable_archive_object_check();
584
585 // For each specified MemRegion range, allocate the corresponding G1
586 // regions and mark them as archive regions. We expect the ranges
587 // in ascending starting address order, without overlap.
588 for (size_t i = 0; i < count; i++) {
589 MemRegion curr_range = ranges[i];
590 HeapWord* start_address = curr_range.start();
591 size_t word_size = curr_range.word_size();
592 HeapWord* last_address = curr_range.last();
593 size_t commits = 0;
594
595 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
596 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
597 p2i(start_address), p2i(last_address));
598 guarantee(start_address > prev_last_addr,
599 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
600 p2i(start_address), p2i(prev_last_addr));
601 prev_last_addr = last_address;
602
603 // Check for ranges that start in the same G1 region in which the previous
604 // range ended, and adjust the start address so we don't try to allocate
605 // the same region again. If the current range is entirely within that
606 // region, skip it, just adjusting the recorded top.
607 HeapRegion* start_region = _hrm.addr_to_region(start_address);
608 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
609 start_address = start_region->end();
610 if (start_address > last_address) {
611 increase_used(word_size * HeapWordSize);
612 start_region->set_top(last_address + 1);
613 continue;
614 }
615 start_region->set_top(start_address);
616 curr_range = MemRegion(start_address, last_address + 1);
617 start_region = _hrm.addr_to_region(start_address);
618 }
619
620 // Perform the actual region allocation, exiting if it fails.
621 // Then note how much new space we have allocated.
622 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
623 return false;
624 }
625 increase_used(word_size * HeapWordSize);
626 if (commits != 0) {
627 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
628 HeapRegion::GrainWords * HeapWordSize * commits);
629
630 }
631
632 // Mark each G1 region touched by the range as archive, add it to
633 // the old set, and set top.
634 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
635 HeapRegion* last_region = _hrm.addr_to_region(last_address);
636 prev_last_region = last_region;
637
638 while (curr_region != NULL) {
639 assert(curr_region->is_empty() && !curr_region->is_pinned(),
640 "Region already in use (index %u)", curr_region->hrm_index());
641 if (open) {
642 curr_region->set_open_archive();
643 } else {
644 curr_region->set_closed_archive();
645 }
646 _hr_printer.alloc(curr_region);
647 _archive_set.add(curr_region);
648 HeapWord* top;
649 HeapRegion* next_region;
650 if (curr_region != last_region) {
651 top = curr_region->end();
652 next_region = _hrm.next_region_in_heap(curr_region);
653 } else {
654 top = last_address + 1;
655 next_region = NULL;
656 }
657 curr_region->set_top(top);
658 curr_region->set_first_dead(top);
659 curr_region->set_end_of_live(top);
660 curr_region = next_region;
661 }
662
663 // Notify mark-sweep of the archive
664 G1ArchiveAllocator::set_range_archive(curr_range, open);
665 }
666 return true;
667 }
668
669 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
670 assert(!is_init_completed(), "Expect to be called at JVM init time");
671 assert(ranges != NULL, "MemRegion array NULL");
672 assert(count != 0, "No MemRegions provided");
673 MemRegion reserved = _hrm.reserved();
674 HeapWord *prev_last_addr = NULL;
675 HeapRegion* prev_last_region = NULL;
676
677 // For each MemRegion, create filler objects, if needed, in the G1 regions
678 // that contain the address range. The address range actually within the
679 // MemRegion will not be modified. That is assumed to have been initialized
680 // elsewhere, probably via an mmap of archived heap data.
681 MutexLockerEx x(Heap_lock);
682 for (size_t i = 0; i < count; i++) {
683 HeapWord* start_address = ranges[i].start();
684 HeapWord* last_address = ranges[i].last();
685
686 assert(reserved.contains(start_address) && reserved.contains(last_address),
687 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
688 p2i(start_address), p2i(last_address));
689 assert(start_address > prev_last_addr,
690 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
691 p2i(start_address), p2i(prev_last_addr));
692
693 HeapRegion* start_region = _hrm.addr_to_region(start_address);
694 HeapRegion* last_region = _hrm.addr_to_region(last_address);
695 HeapWord* bottom_address = start_region->bottom();
696
697 // Check for a range beginning in the same region in which the
698 // previous one ended.
699 if (start_region == prev_last_region) {
700 bottom_address = prev_last_addr + 1;
701 }
702
703 // Verify that the regions were all marked as archive regions by
704 // alloc_archive_regions.
705 HeapRegion* curr_region = start_region;
706 while (curr_region != NULL) {
707 guarantee(curr_region->is_archive(),
708 "Expected archive region at index %u", curr_region->hrm_index());
709 if (curr_region != last_region) {
710 curr_region = _hrm.next_region_in_heap(curr_region);
711 } else {
712 curr_region = NULL;
713 }
714 }
715
716 prev_last_addr = last_address;
717 prev_last_region = last_region;
718
719 // Fill the memory below the allocated range with dummy object(s),
720 // if the region bottom does not match the range start, or if the previous
721 // range ended within the same G1 region, and there is a gap.
722 if (start_address != bottom_address) {
723 size_t fill_size = pointer_delta(start_address, bottom_address);
724 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
725 increase_used(fill_size * HeapWordSize);
726 }
727 }
728 }
729
730 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
731 size_t desired_word_size,
732 size_t* actual_word_size) {
733 assert_heap_not_locked_and_not_at_safepoint();
734 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
735 "be called for humongous allocation requests");
736
737 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
738
739 if (result == NULL) {
740 *actual_word_size = desired_word_size;
741 result = attempt_allocation_slow(desired_word_size);
742 }
743
744 assert_heap_not_locked();
745 if (result != NULL) {
746 assert(*actual_word_size != 0, "Actual size must have been set here");
747 dirty_young_block(result, *actual_word_size);
748 } else {
749 *actual_word_size = 0;
750 }
751
752 return result;
753 }
754
755 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
756 assert(!is_init_completed(), "Expect to be called at JVM init time");
757 assert(ranges != NULL, "MemRegion array NULL");
758 assert(count != 0, "No MemRegions provided");
759 MemRegion reserved = _hrm.reserved();
760 HeapWord* prev_last_addr = NULL;
761 HeapRegion* prev_last_region = NULL;
762 size_t size_used = 0;
763 size_t uncommitted_regions = 0;
764
765 // For each Memregion, free the G1 regions that constitute it, and
766 // notify mark-sweep that the range is no longer to be considered 'archive.'
767 MutexLockerEx x(Heap_lock);
768 for (size_t i = 0; i < count; i++) {
769 HeapWord* start_address = ranges[i].start();
770 HeapWord* last_address = ranges[i].last();
771
772 assert(reserved.contains(start_address) && reserved.contains(last_address),
773 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
774 p2i(start_address), p2i(last_address));
775 assert(start_address > prev_last_addr,
776 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
777 p2i(start_address), p2i(prev_last_addr));
778 size_used += ranges[i].byte_size();
779 prev_last_addr = last_address;
780
781 HeapRegion* start_region = _hrm.addr_to_region(start_address);
782 HeapRegion* last_region = _hrm.addr_to_region(last_address);
783
784 // Check for ranges that start in the same G1 region in which the previous
785 // range ended, and adjust the start address so we don't try to free
786 // the same region again. If the current range is entirely within that
787 // region, skip it.
788 if (start_region == prev_last_region) {
789 start_address = start_region->end();
790 if (start_address > last_address) {
791 continue;
792 }
793 start_region = _hrm.addr_to_region(start_address);
794 }
795 prev_last_region = last_region;
796
797 // After verifying that each region was marked as an archive region by
798 // alloc_archive_regions, set it free and empty and uncommit it.
799 HeapRegion* curr_region = start_region;
800 while (curr_region != NULL) {
801 guarantee(curr_region->is_archive(),
802 "Expected archive region at index %u", curr_region->hrm_index());
803 uint curr_index = curr_region->hrm_index();
804 _archive_set.remove(curr_region);
805 curr_region->set_free();
806 curr_region->set_top(curr_region->bottom());
807 if (curr_region != last_region) {
808 curr_region = _hrm.next_region_in_heap(curr_region);
809 } else {
810 curr_region = NULL;
811 }
812 _hrm.shrink_at(curr_index, 1);
813 uncommitted_regions++;
814 }
815
816 // Notify mark-sweep that this is no longer an archive range.
817 G1ArchiveAllocator::set_range_archive(ranges[i], false);
818 }
819
820 if (uncommitted_regions != 0) {
821 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
822 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
823 }
824 decrease_used(size_used);
825 }
826
827 oop G1CollectedHeap::materialize_archived_object(oop obj) {
828 assert(obj != NULL, "archived obj is NULL");
829 assert(MetaspaceShared::is_archive_object(obj), "must be archived object");
830
831 // Loading an archived object makes it strongly reachable. If it is
832 // loaded during concurrent marking, it must be enqueued to the SATB
833 // queue, shading the previously white object gray.
834 G1BarrierSet::enqueue(obj);
835
836 return obj;
837 }
838
839 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
840 ResourceMark rm; // For retrieving the thread names in log messages.
841
842 // The structure of this method has a lot of similarities to
843 // attempt_allocation_slow(). The reason these two were not merged
844 // into a single one is that such a method would require several "if
845 // allocation is not humongous do this, otherwise do that"
846 // conditional paths which would obscure its flow. In fact, an early
847 // version of this code did use a unified method which was harder to
848 // follow and, as a result, it had subtle bugs that were hard to
849 // track down. So keeping these two methods separate allows each to
850 // be more readable. It will be good to keep these two in sync as
851 // much as possible.
852
853 assert_heap_not_locked_and_not_at_safepoint();
854 assert(is_humongous(word_size), "attempt_allocation_humongous() "
855 "should only be called for humongous allocations");
856
857 // Humongous objects can exhaust the heap quickly, so we should check if we
858 // need to start a marking cycle at each humongous object allocation. We do
859 // the check before we do the actual allocation. The reason for doing it
860 // before the allocation is that we avoid having to keep track of the newly
861 // allocated memory while we do a GC.
862 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
863 word_size)) {
864 collect(GCCause::_g1_humongous_allocation);
865 }
866
867 // We will loop until a) we manage to successfully perform the
868 // allocation or b) we successfully schedule a collection which
869 // fails to perform the allocation. b) is the only case when we'll
870 // return NULL.
871 HeapWord* result = NULL;
872 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
873 bool should_try_gc;
874 uint gc_count_before;
875
876
877 {
878 MutexLockerEx x(Heap_lock);
879
880 // Given that humongous objects are not allocated in young
881 // regions, we'll first try to do the allocation without doing a
882 // collection hoping that there's enough space in the heap.
883 result = humongous_obj_allocate(word_size);
884 if (result != NULL) {
885 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
886 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
887 return result;
888 }
889
890 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
891 // the GCLocker initiated GC has been performed and then retry. This includes
892 // the case when the GC Locker is not active but has not been performed.
893 should_try_gc = !GCLocker::needs_gc();
894 // Read the GC count while still holding the Heap_lock.
895 gc_count_before = total_collections();
896 }
897
898 if (should_try_gc) {
899 bool succeeded;
900 result = do_collection_pause(word_size, gc_count_before, &succeeded,
901 GCCause::_g1_humongous_allocation);
902 if (result != NULL) {
903 assert(succeeded, "only way to get back a non-NULL result");
904 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
905 Thread::current()->name(), p2i(result));
906 return result;
907 }
908
909 if (succeeded) {
910 // We successfully scheduled a collection which failed to allocate. No
911 // point in trying to allocate further. We'll just return NULL.
912 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
913 SIZE_FORMAT " words", Thread::current()->name(), word_size);
914 return NULL;
915 }
916 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
917 Thread::current()->name(), word_size);
918 } else {
919 // Failed to schedule a collection.
920 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
921 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
922 SIZE_FORMAT " words", Thread::current()->name(), word_size);
923 return NULL;
924 }
925 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
926 // The GCLocker is either active or the GCLocker initiated
927 // GC has not yet been performed. Stall until it is and
928 // then retry the allocation.
929 GCLocker::stall_until_clear();
930 gclocker_retry_count += 1;
931 }
932
933
934 // We can reach here if we were unsuccessful in scheduling a
935 // collection (because another thread beat us to it) or if we were
936 // stalled due to the GC locker. In either can we should retry the
937 // allocation attempt in case another thread successfully
938 // performed a collection and reclaimed enough space.
939 // Humongous object allocation always needs a lock, so we wait for the retry
940 // in the next iteration of the loop, unlike for the regular iteration case.
941 // Give a warning if we seem to be looping forever.
942
943 if ((QueuedAllocationWarningCount > 0) &&
944 (try_count % QueuedAllocationWarningCount == 0)) {
945 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
946 Thread::current()->name(), try_count, word_size);
947 }
948 }
949
950 ShouldNotReachHere();
951 return NULL;
952 }
953
954 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
955 bool expect_null_mutator_alloc_region) {
956 assert_at_safepoint_on_vm_thread();
957 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
958 "the current alloc region was unexpectedly found to be non-NULL");
959
960 if (!is_humongous(word_size)) {
961 return _allocator->attempt_allocation_locked(word_size);
962 } else {
963 HeapWord* result = humongous_obj_allocate(word_size);
964 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
965 collector_state()->set_initiate_conc_mark_if_possible(true);
966 }
967 return result;
968 }
969
970 ShouldNotReachHere();
971 }
972
973 class PostCompactionPrinterClosure: public HeapRegionClosure {
974 private:
975 G1HRPrinter* _hr_printer;
976 public:
977 bool do_heap_region(HeapRegion* hr) {
978 assert(!hr->is_young(), "not expecting to find young regions");
979 _hr_printer->post_compaction(hr);
980 return false;
981 }
982
983 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
984 : _hr_printer(hr_printer) { }
985 };
986
987 void G1CollectedHeap::print_hrm_post_compaction() {
988 if (_hr_printer.is_active()) {
989 PostCompactionPrinterClosure cl(hr_printer());
990 heap_region_iterate(&cl);
991 }
992 }
993
994 void G1CollectedHeap::abort_concurrent_cycle() {
995 // If we start the compaction before the CM threads finish
996 // scanning the root regions we might trip them over as we'll
997 // be moving objects / updating references. So let's wait until
998 // they are done. By telling them to abort, they should complete
999 // early.
1000 _cm->root_regions()->abort();
1001 _cm->root_regions()->wait_until_scan_finished();
1002
1003 // Disable discovery and empty the discovered lists
1004 // for the CM ref processor.
1005 _ref_processor_cm->disable_discovery();
1006 _ref_processor_cm->abandon_partial_discovery();
1007 _ref_processor_cm->verify_no_references_recorded();
1008
1009 // Abandon current iterations of concurrent marking and concurrent
1010 // refinement, if any are in progress.
1011 concurrent_mark()->concurrent_cycle_abort();
1012 }
1013
1014 void G1CollectedHeap::prepare_heap_for_full_collection() {
1015 // Make sure we'll choose a new allocation region afterwards.
1016 _allocator->release_mutator_alloc_region();
1017 _allocator->abandon_gc_alloc_regions();
1018 g1_rem_set()->cleanupHRRS();
1019
1020 // We may have added regions to the current incremental collection
1021 // set between the last GC or pause and now. We need to clear the
1022 // incremental collection set and then start rebuilding it afresh
1023 // after this full GC.
1024 abandon_collection_set(collection_set());
1025
1026 tear_down_region_sets(false /* free_list_only */);
1027 }
1028
1029 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1030 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1031 assert(used() == recalculate_used(), "Should be equal");
1032 _verifier->verify_region_sets_optional();
1033 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1034 _verifier->check_bitmaps("Full GC Start");
1035 }
1036
1037 void G1CollectedHeap::prepare_heap_for_mutators() {
1038 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1039 ClassLoaderDataGraph::purge();
1040 MetaspaceUtils::verify_metrics();
1041
1042 // Prepare heap for normal collections.
1043 assert(num_free_regions() == 0, "we should not have added any free regions");
1044 rebuild_region_sets(false /* free_list_only */);
1045 abort_refinement();
1046 resize_if_necessary_after_full_collection();
1047
1048 // Rebuild the strong code root lists for each region
1049 rebuild_strong_code_roots();
1050
1051 // Start a new incremental collection set for the next pause
1052 start_new_collection_set();
1053
1054 _allocator->init_mutator_alloc_region();
1055
1056 // Post collection state updates.
1057 MetaspaceGC::compute_new_size();
1058 }
1059
1060 void G1CollectedHeap::abort_refinement() {
1061 if (_hot_card_cache->use_cache()) {
1062 _hot_card_cache->reset_hot_cache();
1063 }
1064
1065 // Discard all remembered set updates.
1066 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1067 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1068 }
1069
1070 void G1CollectedHeap::verify_after_full_collection() {
1071 _hrm.verify_optional();
1072 _verifier->verify_region_sets_optional();
1073 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1074 // Clear the previous marking bitmap, if needed for bitmap verification.
1075 // Note we cannot do this when we clear the next marking bitmap in
1076 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1077 // objects marked during a full GC against the previous bitmap.
1078 // But we need to clear it before calling check_bitmaps below since
1079 // the full GC has compacted objects and updated TAMS but not updated
1080 // the prev bitmap.
1081 if (G1VerifyBitmaps) {
1082 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1083 _cm->clear_prev_bitmap(workers());
1084 }
1085 _verifier->check_bitmaps("Full GC End");
1086
1087 // At this point there should be no regions in the
1088 // entire heap tagged as young.
1089 assert(check_young_list_empty(), "young list should be empty at this point");
1090
1091 // Note: since we've just done a full GC, concurrent
1092 // marking is no longer active. Therefore we need not
1093 // re-enable reference discovery for the CM ref processor.
1094 // That will be done at the start of the next marking cycle.
1095 // We also know that the STW processor should no longer
1096 // discover any new references.
1097 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1098 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1099 _ref_processor_stw->verify_no_references_recorded();
1100 _ref_processor_cm->verify_no_references_recorded();
1101 }
1102
1103 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1104 // Post collection logging.
1105 // We should do this after we potentially resize the heap so
1106 // that all the COMMIT / UNCOMMIT events are generated before
1107 // the compaction events.
1108 print_hrm_post_compaction();
1109 heap_transition->print();
1110 print_heap_after_gc();
1111 print_heap_regions();
1112 #ifdef TRACESPINNING
1113 ParallelTaskTerminator::print_termination_counts();
1114 #endif
1115 }
1116
1117 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1118 bool clear_all_soft_refs) {
1119 assert_at_safepoint_on_vm_thread();
1120
1121 if (GCLocker::check_active_before_gc()) {
1122 // Full GC was not completed.
1123 return false;
1124 }
1125
1126 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1127 soft_ref_policy()->should_clear_all_soft_refs();
1128
1129 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1130 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1131
1132 collector.prepare_collection();
1133 collector.collect();
1134 collector.complete_collection();
1135
1136 // Full collection was successfully completed.
1137 return true;
1138 }
1139
1140 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1141 // Currently, there is no facility in the do_full_collection(bool) API to notify
1142 // the caller that the collection did not succeed (e.g., because it was locked
1143 // out by the GC locker). So, right now, we'll ignore the return value.
1144 bool dummy = do_full_collection(true, /* explicit_gc */
1145 clear_all_soft_refs);
1146 }
1147
1148 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1149 // Capacity, free and used after the GC counted as full regions to
1150 // include the waste in the following calculations.
1151 const size_t capacity_after_gc = capacity();
1152 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1153
1154 // This is enforced in arguments.cpp.
1155 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1156 "otherwise the code below doesn't make sense");
1157
1158 // We don't have floating point command-line arguments
1159 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1160 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1161 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1162 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1163
1164 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1165 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1166
1167 // We have to be careful here as these two calculations can overflow
1168 // 32-bit size_t's.
1169 double used_after_gc_d = (double) used_after_gc;
1170 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1171 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1172
1173 // Let's make sure that they are both under the max heap size, which
1174 // by default will make them fit into a size_t.
1175 double desired_capacity_upper_bound = (double) max_heap_size;
1176 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1177 desired_capacity_upper_bound);
1178 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1179 desired_capacity_upper_bound);
1180
1181 // We can now safely turn them into size_t's.
1182 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1183 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1184
1185 // This assert only makes sense here, before we adjust them
1186 // with respect to the min and max heap size.
1187 assert(minimum_desired_capacity <= maximum_desired_capacity,
1188 "minimum_desired_capacity = " SIZE_FORMAT ", "
1189 "maximum_desired_capacity = " SIZE_FORMAT,
1190 minimum_desired_capacity, maximum_desired_capacity);
1191
1192 // Should not be greater than the heap max size. No need to adjust
1193 // it with respect to the heap min size as it's a lower bound (i.e.,
1194 // we'll try to make the capacity larger than it, not smaller).
1195 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1196 // Should not be less than the heap min size. No need to adjust it
1197 // with respect to the heap max size as it's an upper bound (i.e.,
1198 // we'll try to make the capacity smaller than it, not greater).
1199 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1200
1201 if (capacity_after_gc < minimum_desired_capacity) {
1202 // Don't expand unless it's significant
1203 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1204
1205 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1206 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1207 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1208 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1209
1210 expand(expand_bytes, _workers);
1211
1212 // No expansion, now see if we want to shrink
1213 } else if (capacity_after_gc > maximum_desired_capacity) {
1214 // Capacity too large, compute shrinking size
1215 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1216
1217 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1218 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1219 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1220 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1221
1222 shrink(shrink_bytes);
1223 }
1224 }
1225
1226 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1227 bool do_gc,
1228 bool clear_all_soft_refs,
1229 bool expect_null_mutator_alloc_region,
1230 bool* gc_succeeded) {
1231 *gc_succeeded = true;
1232 // Let's attempt the allocation first.
1233 HeapWord* result =
1234 attempt_allocation_at_safepoint(word_size,
1235 expect_null_mutator_alloc_region);
1236 if (result != NULL) {
1237 return result;
1238 }
1239
1240 // In a G1 heap, we're supposed to keep allocation from failing by
1241 // incremental pauses. Therefore, at least for now, we'll favor
1242 // expansion over collection. (This might change in the future if we can
1243 // do something smarter than full collection to satisfy a failed alloc.)
1244 result = expand_and_allocate(word_size);
1245 if (result != NULL) {
1246 return result;
1247 }
1248
1249 if (do_gc) {
1250 // Expansion didn't work, we'll try to do a Full GC.
1251 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1252 clear_all_soft_refs);
1253 }
1254
1255 return NULL;
1256 }
1257
1258 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1259 bool* succeeded) {
1260 assert_at_safepoint_on_vm_thread();
1261
1262 // Attempts to allocate followed by Full GC.
1263 HeapWord* result =
1264 satisfy_failed_allocation_helper(word_size,
1265 true, /* do_gc */
1266 false, /* clear_all_soft_refs */
1267 false, /* expect_null_mutator_alloc_region */
1268 succeeded);
1269
1270 if (result != NULL || !*succeeded) {
1271 return result;
1272 }
1273
1274 // Attempts to allocate followed by Full GC that will collect all soft references.
1275 result = satisfy_failed_allocation_helper(word_size,
1276 true, /* do_gc */
1277 true, /* clear_all_soft_refs */
1278 true, /* expect_null_mutator_alloc_region */
1279 succeeded);
1280
1281 if (result != NULL || !*succeeded) {
1282 return result;
1283 }
1284
1285 // Attempts to allocate, no GC
1286 result = satisfy_failed_allocation_helper(word_size,
1287 false, /* do_gc */
1288 false, /* clear_all_soft_refs */
1289 true, /* expect_null_mutator_alloc_region */
1290 succeeded);
1291
1292 if (result != NULL) {
1293 return result;
1294 }
1295
1296 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1297 "Flag should have been handled and cleared prior to this point");
1298
1299 // What else? We might try synchronous finalization later. If the total
1300 // space available is large enough for the allocation, then a more
1301 // complete compaction phase than we've tried so far might be
1302 // appropriate.
1303 return NULL;
1304 }
1305
1306 // Attempting to expand the heap sufficiently
1307 // to support an allocation of the given "word_size". If
1308 // successful, perform the allocation and return the address of the
1309 // allocated block, or else "NULL".
1310
1311 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1312 assert_at_safepoint_on_vm_thread();
1313
1314 _verifier->verify_region_sets_optional();
1315
1316 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1317 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1318 word_size * HeapWordSize);
1319
1320
1321 if (expand(expand_bytes, _workers)) {
1322 _hrm.verify_optional();
1323 _verifier->verify_region_sets_optional();
1324 return attempt_allocation_at_safepoint(word_size,
1325 false /* expect_null_mutator_alloc_region */);
1326 }
1327 return NULL;
1328 }
1329
1330 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1331 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1332 aligned_expand_bytes = align_up(aligned_expand_bytes,
1333 HeapRegion::GrainBytes);
1334
1335 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1336 expand_bytes, aligned_expand_bytes);
1337
1338 if (is_maximal_no_gc()) {
1339 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1340 return false;
1341 }
1342
1343 double expand_heap_start_time_sec = os::elapsedTime();
1344 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1345 assert(regions_to_expand > 0, "Must expand by at least one region");
1346
1347 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1348 if (expand_time_ms != NULL) {
1349 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1350 }
1351
1352 if (expanded_by > 0) {
1353 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1354 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1355 g1_policy()->record_new_heap_size(num_regions());
1356 } else {
1357 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1358
1359 // The expansion of the virtual storage space was unsuccessful.
1360 // Let's see if it was because we ran out of swap.
1361 if (G1ExitOnExpansionFailure &&
1362 _hrm.available() >= regions_to_expand) {
1363 // We had head room...
1364 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1365 }
1366 }
1367 return regions_to_expand > 0;
1368 }
1369
1370 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1371 size_t aligned_shrink_bytes =
1372 ReservedSpace::page_align_size_down(shrink_bytes);
1373 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1374 HeapRegion::GrainBytes);
1375 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1376
1377 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1378 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1379
1380
1381 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",
1382 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1383 if (num_regions_removed > 0) {
1384 g1_policy()->record_new_heap_size(num_regions());
1385 } else {
1386 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1387 }
1388 }
1389
1390 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1391 _verifier->verify_region_sets_optional();
1392
1393 // We should only reach here at the end of a Full GC which means we
1394 // should not not be holding to any GC alloc regions. The method
1395 // below will make sure of that and do any remaining clean up.
1396 _allocator->abandon_gc_alloc_regions();
1397
1398 // Instead of tearing down / rebuilding the free lists here, we
1399 // could instead use the remove_all_pending() method on free_list to
1400 // remove only the ones that we need to remove.
1401 tear_down_region_sets(true /* free_list_only */);
1402 shrink_helper(shrink_bytes);
1403 rebuild_region_sets(true /* free_list_only */);
1404
1405 _hrm.verify_optional();
1406 _verifier->verify_region_sets_optional();
1407 }
1408
1409 class OldRegionSetChecker : public HeapRegionSetChecker {
1410 public:
1411 void check_mt_safety() {
1412 // Master Old Set MT safety protocol:
1413 // (a) If we're at a safepoint, operations on the master old set
1414 // should be invoked:
1415 // - by the VM thread (which will serialize them), or
1416 // - by the GC workers while holding the FreeList_lock, if we're
1417 // at a safepoint for an evacuation pause (this lock is taken
1418 // anyway when an GC alloc region is retired so that a new one
1419 // is allocated from the free list), or
1420 // - by the GC workers while holding the OldSets_lock, if we're at a
1421 // safepoint for a cleanup pause.
1422 // (b) If we're not at a safepoint, operations on the master old set
1423 // should be invoked while holding the Heap_lock.
1424
1425 if (SafepointSynchronize::is_at_safepoint()) {
1426 guarantee(Thread::current()->is_VM_thread() ||
1427 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1428 "master old set MT safety protocol at a safepoint");
1429 } else {
1430 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1431 }
1432 }
1433 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1434 const char* get_description() { return "Old Regions"; }
1435 };
1436
1437 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1438 public:
1439 void check_mt_safety() {
1440 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1441 "May only change archive regions during initialization or safepoint.");
1442 }
1443 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1444 const char* get_description() { return "Archive Regions"; }
1445 };
1446
1447 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1448 public:
1449 void check_mt_safety() {
1450 // Humongous Set MT safety protocol:
1451 // (a) If we're at a safepoint, operations on the master humongous
1452 // set should be invoked by either the VM thread (which will
1453 // serialize them) or by the GC workers while holding the
1454 // OldSets_lock.
1455 // (b) If we're not at a safepoint, operations on the master
1456 // humongous set should be invoked while holding the Heap_lock.
1457
1458 if (SafepointSynchronize::is_at_safepoint()) {
1459 guarantee(Thread::current()->is_VM_thread() ||
1460 OldSets_lock->owned_by_self(),
1461 "master humongous set MT safety protocol at a safepoint");
1462 } else {
1463 guarantee(Heap_lock->owned_by_self(),
1464 "master humongous set MT safety protocol outside a safepoint");
1465 }
1466 }
1467 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1468 const char* get_description() { return "Humongous Regions"; }
1469 };
1470
1471 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1472 CollectedHeap(),
1473 _young_gen_sampling_thread(NULL),
1474 _workers(NULL),
1475 _collector_policy(collector_policy),
1476 _card_table(NULL),
1477 _soft_ref_policy(),
1478 _old_set("Old Region Set", new OldRegionSetChecker()),
1479 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1480 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1481 _bot(NULL),
1482 _listener(),
1483 _hrm(),
1484 _allocator(NULL),
1485 _verifier(NULL),
1486 _summary_bytes_used(0),
1487 _archive_allocator(NULL),
1488 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1489 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1490 _expand_heap_after_alloc_failure(true),
1491 _g1mm(NULL),
1492 _humongous_reclaim_candidates(),
1493 _has_humongous_reclaim_candidates(false),
1494 _hr_printer(),
1495 _collector_state(),
1496 _old_marking_cycles_started(0),
1497 _old_marking_cycles_completed(0),
1498 _eden(),
1499 _survivor(),
1500 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1501 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1502 _g1_policy(new G1Policy(_gc_timer_stw)),
1503 _heap_sizing_policy(NULL),
1504 _collection_set(this, _g1_policy),
1505 _hot_card_cache(NULL),
1506 _g1_rem_set(NULL),
1507 _dirty_card_queue_set(false),
1508 _cm(NULL),
1509 _cm_thread(NULL),
1510 _cr(NULL),
1511 _task_queues(NULL),
1512 _evacuation_failed(false),
1513 _evacuation_failed_info_array(NULL),
1514 _preserved_marks_set(true /* in_c_heap */),
1515 #ifndef PRODUCT
1516 _evacuation_failure_alot_for_current_gc(false),
1517 _evacuation_failure_alot_gc_number(0),
1518 _evacuation_failure_alot_count(0),
1519 #endif
1520 _ref_processor_stw(NULL),
1521 _is_alive_closure_stw(this),
1522 _is_subject_to_discovery_stw(this),
1523 _ref_processor_cm(NULL),
1524 _is_alive_closure_cm(this),
1525 _is_subject_to_discovery_cm(this),
1526 _in_cset_fast_test() {
1527
1528 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1529 true /* are_GC_task_threads */,
1530 false /* are_ConcurrentGC_threads */);
1531 _workers->initialize_workers();
1532 _verifier = new G1HeapVerifier(this);
1533
1534 _allocator = new G1Allocator(this);
1535
1536 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1537
1538 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1539
1540 // Override the default _filler_array_max_size so that no humongous filler
1541 // objects are created.
1542 _filler_array_max_size = _humongous_object_threshold_in_words;
1543
1544 uint n_queues = ParallelGCThreads;
1545 _task_queues = new RefToScanQueueSet(n_queues);
1546
1547 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1548
1549 for (uint i = 0; i < n_queues; i++) {
1550 RefToScanQueue* q = new RefToScanQueue();
1551 q->initialize();
1552 _task_queues->register_queue(i, q);
1553 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1554 }
1555
1556 // Initialize the G1EvacuationFailureALot counters and flags.
1557 NOT_PRODUCT(reset_evacuation_should_fail();)
1558
1559 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1560 }
1561
1562 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1563 size_t size,
1564 size_t translation_factor) {
1565 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1566 // Allocate a new reserved space, preferring to use large pages.
1567 ReservedSpace rs(size, preferred_page_size);
1568 G1RegionToSpaceMapper* result =
1569 G1RegionToSpaceMapper::create_mapper(rs,
1570 size,
1571 rs.alignment(),
1572 HeapRegion::GrainBytes,
1573 translation_factor,
1574 mtGC);
1575
1576 os::trace_page_sizes_for_requested_size(description,
1577 size,
1578 preferred_page_size,
1579 rs.alignment(),
1580 rs.base(),
1581 rs.size());
1582
1583 return result;
1584 }
1585
1586 jint G1CollectedHeap::initialize_concurrent_refinement() {
1587 jint ecode = JNI_OK;
1588 _cr = G1ConcurrentRefine::create(&ecode);
1589 return ecode;
1590 }
1591
1592 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1593 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1594 if (_young_gen_sampling_thread->osthread() == NULL) {
1595 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1596 return JNI_ENOMEM;
1597 }
1598 return JNI_OK;
1599 }
1600
1601 jint G1CollectedHeap::initialize() {
1602 os::enable_vtime();
1603
1604 // Necessary to satisfy locking discipline assertions.
1605
1606 MutexLocker x(Heap_lock);
1607
1608 // While there are no constraints in the GC code that HeapWordSize
1609 // be any particular value, there are multiple other areas in the
1610 // system which believe this to be true (e.g. oop->object_size in some
1611 // cases incorrectly returns the size in wordSize units rather than
1612 // HeapWordSize).
1613 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1614
1615 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1616 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1617 size_t heap_alignment = collector_policy()->heap_alignment();
1618
1619 // Ensure that the sizes are properly aligned.
1620 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1621 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1622 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1623
1624 // Reserve the maximum.
1625
1626 // When compressed oops are enabled, the preferred heap base
1627 // is calculated by subtracting the requested size from the
1628 // 32Gb boundary and using the result as the base address for
1629 // heap reservation. If the requested size is not aligned to
1630 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1631 // into the ReservedHeapSpace constructor) then the actual
1632 // base of the reserved heap may end up differing from the
1633 // address that was requested (i.e. the preferred heap base).
1634 // If this happens then we could end up using a non-optimal
1635 // compressed oops mode.
1636
1637 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1638 heap_alignment);
1639
1640 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1641
1642 // Create the barrier set for the entire reserved region.
1643 G1CardTable* ct = new G1CardTable(reserved_region());
1644 ct->initialize();
1645 G1BarrierSet* bs = new G1BarrierSet(ct);
1646 bs->initialize();
1647 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1648 BarrierSet::set_barrier_set(bs);
1649 _card_table = ct;
1650
1651 // Create the hot card cache.
1652 _hot_card_cache = new G1HotCardCache(this);
1653
1654 // Carve out the G1 part of the heap.
1655 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1656 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1657 G1RegionToSpaceMapper* heap_storage =
1658 G1RegionToSpaceMapper::create_mapper(g1_rs,
1659 g1_rs.size(),
1660 page_size,
1661 HeapRegion::GrainBytes,
1662 1,
1663 mtJavaHeap);
1664 os::trace_page_sizes("Heap",
1665 collector_policy()->min_heap_byte_size(),
1666 max_byte_size,
1667 page_size,
1668 heap_rs.base(),
1669 heap_rs.size());
1670 heap_storage->set_mapping_changed_listener(&_listener);
1671
1672 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1673 G1RegionToSpaceMapper* bot_storage =
1674 create_aux_memory_mapper("Block Offset Table",
1675 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1676 G1BlockOffsetTable::heap_map_factor());
1677
1678 G1RegionToSpaceMapper* cardtable_storage =
1679 create_aux_memory_mapper("Card Table",
1680 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1681 G1CardTable::heap_map_factor());
1682
1683 G1RegionToSpaceMapper* card_counts_storage =
1684 create_aux_memory_mapper("Card Counts Table",
1685 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1686 G1CardCounts::heap_map_factor());
1687
1688 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1689 G1RegionToSpaceMapper* prev_bitmap_storage =
1690 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1691 G1RegionToSpaceMapper* next_bitmap_storage =
1692 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1693
1694 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1695 _card_table->initialize(cardtable_storage);
1696 // Do later initialization work for concurrent refinement.
1697 _hot_card_cache->initialize(card_counts_storage);
1698
1699 // 6843694 - ensure that the maximum region index can fit
1700 // in the remembered set structures.
1701 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1702 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1703
1704 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1705 // start within the first card.
1706 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1707 // Also create a G1 rem set.
1708 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1709 _g1_rem_set->initialize(max_capacity(), max_regions());
1710
1711 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1712 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1713 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1714 "too many cards per region");
1715
1716 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1717
1718 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1719
1720 {
1721 HeapWord* start = _hrm.reserved().start();
1722 HeapWord* end = _hrm.reserved().end();
1723 size_t granularity = HeapRegion::GrainBytes;
1724
1725 _in_cset_fast_test.initialize(start, end, granularity);
1726 _humongous_reclaim_candidates.initialize(start, end, granularity);
1727 }
1728
1729 // Create the G1ConcurrentMark data structure and thread.
1730 // (Must do this late, so that "max_regions" is defined.)
1731 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1732 if (_cm == NULL || !_cm->completed_initialization()) {
1733 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1734 return JNI_ENOMEM;
1735 }
1736 _cm_thread = _cm->cm_thread();
1737
1738 // Now expand into the initial heap size.
1739 if (!expand(init_byte_size, _workers)) {
1740 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1741 return JNI_ENOMEM;
1742 }
1743
1744 // Perform any initialization actions delegated to the policy.
1745 g1_policy()->init(this, &_collection_set);
1746
1747 G1BarrierSet::satb_mark_queue_set().initialize(this,
1748 SATB_Q_CBL_mon,
1749 SATB_Q_FL_lock,
1750 G1SATBProcessCompletedThreshold,
1751 G1SATBBufferEnqueueingThresholdPercent,
1752 Shared_SATB_Q_lock);
1753
1754 jint ecode = initialize_concurrent_refinement();
1755 if (ecode != JNI_OK) {
1756 return ecode;
1757 }
1758
1759 ecode = initialize_young_gen_sampling_thread();
1760 if (ecode != JNI_OK) {
1761 return ecode;
1762 }
1763
1764 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1765 DirtyCardQ_FL_lock,
1766 (int)concurrent_refine()->yellow_zone(),
1767 (int)concurrent_refine()->red_zone(),
1768 Shared_DirtyCardQ_lock,
1769 NULL, // fl_owner
1770 true); // init_free_ids
1771
1772 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1773 DirtyCardQ_FL_lock,
1774 -1, // never trigger processing
1775 -1, // no limit on length
1776 Shared_DirtyCardQ_lock,
1777 &G1BarrierSet::dirty_card_queue_set());
1778
1779 // Here we allocate the dummy HeapRegion that is required by the
1780 // G1AllocRegion class.
1781 HeapRegion* dummy_region = _hrm.get_dummy_region();
1782
1783 // We'll re-use the same region whether the alloc region will
1784 // require BOT updates or not and, if it doesn't, then a non-young
1785 // region will complain that it cannot support allocations without
1786 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1787 dummy_region->set_eden();
1788 // Make sure it's full.
1789 dummy_region->set_top(dummy_region->end());
1790 G1AllocRegion::setup(this, dummy_region);
1791
1792 _allocator->init_mutator_alloc_region();
1793
1794 // Do create of the monitoring and management support so that
1795 // values in the heap have been properly initialized.
1796 _g1mm = new G1MonitoringSupport(this);
1797
1798 G1StringDedup::initialize();
1799
1800 _preserved_marks_set.init(ParallelGCThreads);
1801
1802 _collection_set.initialize(max_regions());
1803
1804 return JNI_OK;
1805 }
1806
1807 void G1CollectedHeap::stop() {
1808 // Stop all concurrent threads. We do this to make sure these threads
1809 // do not continue to execute and access resources (e.g. logging)
1810 // that are destroyed during shutdown.
1811 _cr->stop();
1812 _young_gen_sampling_thread->stop();
1813 _cm_thread->stop();
1814 if (G1StringDedup::is_enabled()) {
1815 G1StringDedup::stop();
1816 }
1817 }
1818
1819 void G1CollectedHeap::safepoint_synchronize_begin() {
1820 SuspendibleThreadSet::synchronize();
1821 }
1822
1823 void G1CollectedHeap::safepoint_synchronize_end() {
1824 SuspendibleThreadSet::desynchronize();
1825 }
1826
1827 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1828 return HeapRegion::max_region_size();
1829 }
1830
1831 void G1CollectedHeap::post_initialize() {
1832 CollectedHeap::post_initialize();
1833 ref_processing_init();
1834 }
1835
1836 void G1CollectedHeap::ref_processing_init() {
1837 // Reference processing in G1 currently works as follows:
1838 //
1839 // * There are two reference processor instances. One is
1840 // used to record and process discovered references
1841 // during concurrent marking; the other is used to
1842 // record and process references during STW pauses
1843 // (both full and incremental).
1844 // * Both ref processors need to 'span' the entire heap as
1845 // the regions in the collection set may be dotted around.
1846 //
1847 // * For the concurrent marking ref processor:
1848 // * Reference discovery is enabled at initial marking.
1849 // * Reference discovery is disabled and the discovered
1850 // references processed etc during remarking.
1851 // * Reference discovery is MT (see below).
1852 // * Reference discovery requires a barrier (see below).
1853 // * Reference processing may or may not be MT
1854 // (depending on the value of ParallelRefProcEnabled
1855 // and ParallelGCThreads).
1856 // * A full GC disables reference discovery by the CM
1857 // ref processor and abandons any entries on it's
1858 // discovered lists.
1859 //
1860 // * For the STW processor:
1861 // * Non MT discovery is enabled at the start of a full GC.
1862 // * Processing and enqueueing during a full GC is non-MT.
1863 // * During a full GC, references are processed after marking.
1864 //
1865 // * Discovery (may or may not be MT) is enabled at the start
1866 // of an incremental evacuation pause.
1867 // * References are processed near the end of a STW evacuation pause.
1868 // * For both types of GC:
1869 // * Discovery is atomic - i.e. not concurrent.
1870 // * Reference discovery will not need a barrier.
1871
1872 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1873
1874 // Concurrent Mark ref processor
1875 _ref_processor_cm =
1876 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1877 mt_processing, // mt processing
1878 ParallelGCThreads, // degree of mt processing
1879 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1880 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1881 false, // Reference discovery is not atomic
1882 &_is_alive_closure_cm, // is alive closure
1883 true); // allow changes to number of processing threads
1884
1885 // STW ref processor
1886 _ref_processor_stw =
1887 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1888 mt_processing, // mt processing
1889 ParallelGCThreads, // degree of mt processing
1890 (ParallelGCThreads > 1), // mt discovery
1891 ParallelGCThreads, // degree of mt discovery
1892 true, // Reference discovery is atomic
1893 &_is_alive_closure_stw, // is alive closure
1894 true); // allow changes to number of processing threads
1895 }
1896
1897 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1898 return _collector_policy;
1899 }
1900
1901 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1902 return &_soft_ref_policy;
1903 }
1904
1905 size_t G1CollectedHeap::capacity() const {
1906 return _hrm.length() * HeapRegion::GrainBytes;
1907 }
1908
1909 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1910 return _hrm.total_free_bytes();
1911 }
1912
1913 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1914 _hot_card_cache->drain(cl, worker_i);
1915 }
1916
1917 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1918 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1919 size_t n_completed_buffers = 0;
1920 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1921 n_completed_buffers++;
1922 }
1923 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1924 dcqs.clear_n_completed_buffers();
1925 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1926 }
1927
1928 // Computes the sum of the storage used by the various regions.
1929 size_t G1CollectedHeap::used() const {
1930 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1931 if (_archive_allocator != NULL) {
1932 result += _archive_allocator->used();
1933 }
1934 return result;
1935 }
1936
1937 size_t G1CollectedHeap::used_unlocked() const {
1938 return _summary_bytes_used;
1939 }
1940
1941 class SumUsedClosure: public HeapRegionClosure {
1942 size_t _used;
1943 public:
1944 SumUsedClosure() : _used(0) {}
1945 bool do_heap_region(HeapRegion* r) {
1946 _used += r->used();
1947 return false;
1948 }
1949 size_t result() { return _used; }
1950 };
1951
1952 size_t G1CollectedHeap::recalculate_used() const {
1953 SumUsedClosure blk;
1954 heap_region_iterate(&blk);
1955 return blk.result();
1956 }
1957
1958 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1959 switch (cause) {
1960 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1961 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1962 case GCCause::_wb_conc_mark: return true;
1963 default : return false;
1964 }
1965 }
1966
1967 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1968 switch (cause) {
1969 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1970 case GCCause::_g1_humongous_allocation: return true;
1971 default: return is_user_requested_concurrent_full_gc(cause);
1972 }
1973 }
1974
1975 #ifndef PRODUCT
1976 void G1CollectedHeap::allocate_dummy_regions() {
1977 // Let's fill up most of the region
1978 size_t word_size = HeapRegion::GrainWords - 1024;
1979 // And as a result the region we'll allocate will be humongous.
1980 guarantee(is_humongous(word_size), "sanity");
1981
1982 // _filler_array_max_size is set to humongous object threshold
1983 // but temporarily change it to use CollectedHeap::fill_with_object().
1984 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1985
1986 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1987 // Let's use the existing mechanism for the allocation
1988 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1989 if (dummy_obj != NULL) {
1990 MemRegion mr(dummy_obj, word_size);
1991 CollectedHeap::fill_with_object(mr);
1992 } else {
1993 // If we can't allocate once, we probably cannot allocate
1994 // again. Let's get out of the loop.
1995 break;
1996 }
1997 }
1998 }
1999 #endif // !PRODUCT
2000
2001 void G1CollectedHeap::increment_old_marking_cycles_started() {
2002 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2003 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2004 "Wrong marking cycle count (started: %d, completed: %d)",
2005 _old_marking_cycles_started, _old_marking_cycles_completed);
2006
2007 _old_marking_cycles_started++;
2008 }
2009
2010 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2011 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2012
2013 // We assume that if concurrent == true, then the caller is a
2014 // concurrent thread that was joined the Suspendible Thread
2015 // Set. If there's ever a cheap way to check this, we should add an
2016 // assert here.
2017
2018 // Given that this method is called at the end of a Full GC or of a
2019 // concurrent cycle, and those can be nested (i.e., a Full GC can
2020 // interrupt a concurrent cycle), the number of full collections
2021 // completed should be either one (in the case where there was no
2022 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2023 // behind the number of full collections started.
2024
2025 // This is the case for the inner caller, i.e. a Full GC.
2026 assert(concurrent ||
2027 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2028 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2029 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2030 "is inconsistent with _old_marking_cycles_completed = %u",
2031 _old_marking_cycles_started, _old_marking_cycles_completed);
2032
2033 // This is the case for the outer caller, i.e. the concurrent cycle.
2034 assert(!concurrent ||
2035 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2036 "for outer caller (concurrent cycle): "
2037 "_old_marking_cycles_started = %u "
2038 "is inconsistent with _old_marking_cycles_completed = %u",
2039 _old_marking_cycles_started, _old_marking_cycles_completed);
2040
2041 _old_marking_cycles_completed += 1;
2042
2043 // We need to clear the "in_progress" flag in the CM thread before
2044 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2045 // is set) so that if a waiter requests another System.gc() it doesn't
2046 // incorrectly see that a marking cycle is still in progress.
2047 if (concurrent) {
2048 _cm_thread->set_idle();
2049 }
2050
2051 // This notify_all() will ensure that a thread that called
2052 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2053 // and it's waiting for a full GC to finish will be woken up. It is
2054 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2055 FullGCCount_lock->notify_all();
2056 }
2057
2058 void G1CollectedHeap::collect(GCCause::Cause cause) {
2059 assert_heap_not_locked();
2060
2061 uint gc_count_before;
2062 uint old_marking_count_before;
2063 uint full_gc_count_before;
2064 bool retry_gc;
2065
2066 do {
2067 retry_gc = false;
2068
2069 {
2070 MutexLocker ml(Heap_lock);
2071
2072 // Read the GC count while holding the Heap_lock
2073 gc_count_before = total_collections();
2074 full_gc_count_before = total_full_collections();
2075 old_marking_count_before = _old_marking_cycles_started;
2076 }
2077
2078 if (should_do_concurrent_full_gc(cause)) {
2079 // Schedule an initial-mark evacuation pause that will start a
2080 // concurrent cycle. We're setting word_size to 0 which means that
2081 // we are not requesting a post-GC allocation.
2082 VM_G1CollectForAllocation op(0, /* word_size */
2083 gc_count_before,
2084 cause,
2085 true, /* should_initiate_conc_mark */
2086 g1_policy()->max_pause_time_ms());
2087 VMThread::execute(&op);
2088 if (!op.pause_succeeded()) {
2089 if (old_marking_count_before == _old_marking_cycles_started) {
2090 retry_gc = op.should_retry_gc();
2091 } else {
2092 // A Full GC happened while we were trying to schedule the
2093 // initial-mark GC. No point in starting a new cycle given
2094 // that the whole heap was collected anyway.
2095 }
2096
2097 if (retry_gc) {
2098 if (GCLocker::is_active_and_needs_gc()) {
2099 GCLocker::stall_until_clear();
2100 }
2101 }
2102 }
2103 } else {
2104 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2105 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2106
2107 // Schedule a standard evacuation pause. We're setting word_size
2108 // to 0 which means that we are not requesting a post-GC allocation.
2109 VM_G1CollectForAllocation op(0, /* word_size */
2110 gc_count_before,
2111 cause,
2112 false, /* should_initiate_conc_mark */
2113 g1_policy()->max_pause_time_ms());
2114 VMThread::execute(&op);
2115 } else {
2116 // Schedule a Full GC.
2117 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2118 VMThread::execute(&op);
2119 }
2120 }
2121 } while (retry_gc);
2122 }
2123
2124 bool G1CollectedHeap::is_in(const void* p) const {
2125 if (_hrm.reserved().contains(p)) {
2126 // Given that we know that p is in the reserved space,
2127 // heap_region_containing() should successfully
2128 // return the containing region.
2129 HeapRegion* hr = heap_region_containing(p);
2130 return hr->is_in(p);
2131 } else {
2132 return false;
2133 }
2134 }
2135
2136 #ifdef ASSERT
2137 bool G1CollectedHeap::is_in_exact(const void* p) const {
2138 bool contains = reserved_region().contains(p);
2139 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2140 if (contains && available) {
2141 return true;
2142 } else {
2143 return false;
2144 }
2145 }
2146 #endif
2147
2148 // Iteration functions.
2149
2150 // Iterates an ObjectClosure over all objects within a HeapRegion.
2151
2152 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2153 ObjectClosure* _cl;
2154 public:
2155 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2156 bool do_heap_region(HeapRegion* r) {
2157 if (!r->is_continues_humongous()) {
2158 r->object_iterate(_cl);
2159 }
2160 return false;
2161 }
2162 };
2163
2164 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2165 IterateObjectClosureRegionClosure blk(cl);
2166 heap_region_iterate(&blk);
2167 }
2168
2169 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2170 _hrm.iterate(cl);
2171 }
2172
2173 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2174 HeapRegionClaimer *hrclaimer,
2175 uint worker_id) const {
2176 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2177 }
2178
2179 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2180 HeapRegionClaimer *hrclaimer) const {
2181 _hrm.par_iterate(cl, hrclaimer, 0);
2182 }
2183
2184 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2185 _collection_set.iterate(cl);
2186 }
2187
2188 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2189 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2190 }
2191
2192 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2193 HeapRegion* hr = heap_region_containing(addr);
2194 return hr->block_start(addr);
2195 }
2196
2197 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2198 HeapRegion* hr = heap_region_containing(addr);
2199 return hr->block_size(addr);
2200 }
2201
2202 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2203 HeapRegion* hr = heap_region_containing(addr);
2204 return hr->block_is_obj(addr);
2205 }
2206
2207 bool G1CollectedHeap::supports_tlab_allocation() const {
2208 return true;
2209 }
2210
2211 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2212 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2213 }
2214
2215 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2216 return _eden.length() * HeapRegion::GrainBytes;
2217 }
2218
2219 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2220 // must be equal to the humongous object limit.
2221 size_t G1CollectedHeap::max_tlab_size() const {
2222 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2223 }
2224
2225 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2226 return _allocator->unsafe_max_tlab_alloc();
2227 }
2228
2229 size_t G1CollectedHeap::max_capacity() const {
2230 return _hrm.reserved().byte_size();
2231 }
2232
2233 jlong G1CollectedHeap::millis_since_last_gc() {
2234 // See the notes in GenCollectedHeap::millis_since_last_gc()
2235 // for more information about the implementation.
2236 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2237 _g1_policy->collection_pause_end_millis();
2238 if (ret_val < 0) {
2239 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2240 ". returning zero instead.", ret_val);
2241 return 0;
2242 }
2243 return ret_val;
2244 }
2245
2246 void G1CollectedHeap::deduplicate_string(oop str) {
2247 assert(java_lang_String::is_instance(str), "invariant");
2248
2249 if (G1StringDedup::is_enabled()) {
2250 G1StringDedup::deduplicate(str);
2251 }
2252 }
2253
2254 void G1CollectedHeap::prepare_for_verify() {
2255 _verifier->prepare_for_verify();
2256 }
2257
2258 void G1CollectedHeap::verify(VerifyOption vo) {
2259 _verifier->verify(vo);
2260 }
2261
2262 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2263 return true;
2264 }
2265
2266 const char* const* G1CollectedHeap::concurrent_phases() const {
2267 return _cm_thread->concurrent_phases();
2268 }
2269
2270 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2271 return _cm_thread->request_concurrent_phase(phase);
2272 }
2273
2274 class PrintRegionClosure: public HeapRegionClosure {
2275 outputStream* _st;
2276 public:
2277 PrintRegionClosure(outputStream* st) : _st(st) {}
2278 bool do_heap_region(HeapRegion* r) {
2279 r->print_on(_st);
2280 return false;
2281 }
2282 };
2283
2284 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2285 const HeapRegion* hr,
2286 const VerifyOption vo) const {
2287 switch (vo) {
2288 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2289 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2290 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2291 default: ShouldNotReachHere();
2292 }
2293 return false; // keep some compilers happy
2294 }
2295
2296 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2297 const VerifyOption vo) const {
2298 switch (vo) {
2299 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2300 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2301 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2302 default: ShouldNotReachHere();
2303 }
2304 return false; // keep some compilers happy
2305 }
2306
2307 void G1CollectedHeap::print_heap_regions() const {
2308 LogTarget(Trace, gc, heap, region) lt;
2309 if (lt.is_enabled()) {
2310 LogStream ls(lt);
2311 print_regions_on(&ls);
2312 }
2313 }
2314
2315 void G1CollectedHeap::print_on(outputStream* st) const {
2316 st->print(" %-20s", "garbage-first heap");
2317 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2318 capacity()/K, used_unlocked()/K);
2319 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2320 p2i(_hrm.reserved().start()),
2321 p2i(_hrm.reserved().end()));
2322 st->cr();
2323 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2324 uint young_regions = young_regions_count();
2325 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2326 (size_t) young_regions * HeapRegion::GrainBytes / K);
2327 uint survivor_regions = survivor_regions_count();
2328 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2329 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2330 st->cr();
2331 MetaspaceUtils::print_on(st);
2332 }
2333
2334 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2335 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2336 "HS=humongous(starts), HC=humongous(continues), "
2337 "CS=collection set, F=free, A=archive, "
2338 "TAMS=top-at-mark-start (previous, next)");
2339 PrintRegionClosure blk(st);
2340 heap_region_iterate(&blk);
2341 }
2342
2343 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2344 print_on(st);
2345
2346 // Print the per-region information.
2347 print_regions_on(st);
2348 }
2349
2350 void G1CollectedHeap::print_on_error(outputStream* st) const {
2351 this->CollectedHeap::print_on_error(st);
2352
2353 if (_cm != NULL) {
2354 st->cr();
2355 _cm->print_on_error(st);
2356 }
2357 }
2358
2359 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2360 workers()->print_worker_threads_on(st);
2361 _cm_thread->print_on(st);
2362 st->cr();
2363 _cm->print_worker_threads_on(st);
2364 _cr->print_threads_on(st);
2365 _young_gen_sampling_thread->print_on(st);
2366 if (G1StringDedup::is_enabled()) {
2367 G1StringDedup::print_worker_threads_on(st);
2368 }
2369 }
2370
2371 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2372 workers()->threads_do(tc);
2373 tc->do_thread(_cm_thread);
2374 _cm->threads_do(tc);
2375 _cr->threads_do(tc);
2376 tc->do_thread(_young_gen_sampling_thread);
2377 if (G1StringDedup::is_enabled()) {
2378 G1StringDedup::threads_do(tc);
2379 }
2380 }
2381
2382 void G1CollectedHeap::print_tracing_info() const {
2383 g1_rem_set()->print_summary_info();
2384 concurrent_mark()->print_summary_info();
2385 }
2386
2387 #ifndef PRODUCT
2388 // Helpful for debugging RSet issues.
2389
2390 class PrintRSetsClosure : public HeapRegionClosure {
2391 private:
2392 const char* _msg;
2393 size_t _occupied_sum;
2394
2395 public:
2396 bool do_heap_region(HeapRegion* r) {
2397 HeapRegionRemSet* hrrs = r->rem_set();
2398 size_t occupied = hrrs->occupied();
2399 _occupied_sum += occupied;
2400
2401 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2402 if (occupied == 0) {
2403 tty->print_cr(" RSet is empty");
2404 } else {
2405 hrrs->print();
2406 }
2407 tty->print_cr("----------");
2408 return false;
2409 }
2410
2411 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2412 tty->cr();
2413 tty->print_cr("========================================");
2414 tty->print_cr("%s", msg);
2415 tty->cr();
2416 }
2417
2418 ~PrintRSetsClosure() {
2419 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2420 tty->print_cr("========================================");
2421 tty->cr();
2422 }
2423 };
2424
2425 void G1CollectedHeap::print_cset_rsets() {
2426 PrintRSetsClosure cl("Printing CSet RSets");
2427 collection_set_iterate(&cl);
2428 }
2429
2430 void G1CollectedHeap::print_all_rsets() {
2431 PrintRSetsClosure cl("Printing All RSets");;
2432 heap_region_iterate(&cl);
2433 }
2434 #endif // PRODUCT
2435
2436 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2437
2438 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2439 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2440 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2441
2442 size_t eden_capacity_bytes =
2443 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2444
2445 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2446 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2447 eden_capacity_bytes, survivor_used_bytes, num_regions());
2448 }
2449
2450 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2451 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2452 stats->unused(), stats->used(), stats->region_end_waste(),
2453 stats->regions_filled(), stats->direct_allocated(),
2454 stats->failure_used(), stats->failure_waste());
2455 }
2456
2457 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2458 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2459 gc_tracer->report_gc_heap_summary(when, heap_summary);
2460
2461 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2462 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2463 }
2464
2465 G1CollectedHeap* G1CollectedHeap::heap() {
2466 CollectedHeap* heap = Universe::heap();
2467 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2468 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2469 return (G1CollectedHeap*)heap;
2470 }
2471
2472 void G1CollectedHeap::gc_prologue(bool full) {
2473 // always_do_update_barrier = false;
2474 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2475
2476 // This summary needs to be printed before incrementing total collections.
2477 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2478
2479 // Update common counters.
2480 increment_total_collections(full /* full gc */);
2481 if (full) {
2482 increment_old_marking_cycles_started();
2483 }
2484
2485 // Fill TLAB's and such
2486 double start = os::elapsedTime();
2487 accumulate_statistics_all_tlabs();
2488 ensure_parsability(true);
2489 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2490 }
2491
2492 void G1CollectedHeap::gc_epilogue(bool full) {
2493 // Update common counters.
2494 if (full) {
2495 // Update the number of full collections that have been completed.
2496 increment_old_marking_cycles_completed(false /* concurrent */);
2497 }
2498
2499 // We are at the end of the GC. Total collections has already been increased.
2500 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2501
2502 // FIXME: what is this about?
2503 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2504 // is set.
2505 #if COMPILER2_OR_JVMCI
2506 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2507 #endif
2508 // always_do_update_barrier = true;
2509
2510 double start = os::elapsedTime();
2511 resize_all_tlabs();
2512 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2513
2514 MemoryService::track_memory_usage();
2515 // We have just completed a GC. Update the soft reference
2516 // policy with the new heap occupancy
2517 Universe::update_heap_info_at_gc();
2518 }
2519
2520 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2521 uint gc_count_before,
2522 bool* succeeded,
2523 GCCause::Cause gc_cause) {
2524 assert_heap_not_locked_and_not_at_safepoint();
2525 VM_G1CollectForAllocation op(word_size,
2526 gc_count_before,
2527 gc_cause,
2528 false, /* should_initiate_conc_mark */
2529 g1_policy()->max_pause_time_ms());
2530 VMThread::execute(&op);
2531
2532 HeapWord* result = op.result();
2533 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2534 assert(result == NULL || ret_succeeded,
2535 "the result should be NULL if the VM did not succeed");
2536 *succeeded = ret_succeeded;
2537
2538 assert_heap_not_locked();
2539 return result;
2540 }
2541
2542 void G1CollectedHeap::do_concurrent_mark() {
2543 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2544 if (!_cm_thread->in_progress()) {
2545 _cm_thread->set_started();
2546 CGC_lock->notify();
2547 }
2548 }
2549
2550 size_t G1CollectedHeap::pending_card_num() {
2551 size_t extra_cards = 0;
2552 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2553 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2554 extra_cards += dcq.size();
2555 }
2556 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2557 size_t buffer_size = dcqs.buffer_size();
2558 size_t buffer_num = dcqs.completed_buffers_num();
2559
2560 return buffer_size * buffer_num + extra_cards;
2561 }
2562
2563 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2564 // We don't nominate objects with many remembered set entries, on
2565 // the assumption that such objects are likely still live.
2566 HeapRegionRemSet* rem_set = r->rem_set();
2567
2568 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2569 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2570 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2571 }
2572
2573 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2574 private:
2575 size_t _total_humongous;
2576 size_t _candidate_humongous;
2577
2578 DirtyCardQueue _dcq;
2579
2580 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2581 assert(region->is_starts_humongous(), "Must start a humongous object");
2582
2583 oop obj = oop(region->bottom());
2584
2585 // Dead objects cannot be eager reclaim candidates. Due to class
2586 // unloading it is unsafe to query their classes so we return early.
2587 if (g1h->is_obj_dead(obj, region)) {
2588 return false;
2589 }
2590
2591 // If we do not have a complete remembered set for the region, then we can
2592 // not be sure that we have all references to it.
2593 if (!region->rem_set()->is_complete()) {
2594 return false;
2595 }
2596 // Candidate selection must satisfy the following constraints
2597 // while concurrent marking is in progress:
2598 //
2599 // * In order to maintain SATB invariants, an object must not be
2600 // reclaimed if it was allocated before the start of marking and
2601 // has not had its references scanned. Such an object must have
2602 // its references (including type metadata) scanned to ensure no
2603 // live objects are missed by the marking process. Objects
2604 // allocated after the start of concurrent marking don't need to
2605 // be scanned.
2606 //
2607 // * An object must not be reclaimed if it is on the concurrent
2608 // mark stack. Objects allocated after the start of concurrent
2609 // marking are never pushed on the mark stack.
2610 //
2611 // Nominating only objects allocated after the start of concurrent
2612 // marking is sufficient to meet both constraints. This may miss
2613 // some objects that satisfy the constraints, but the marking data
2614 // structures don't support efficiently performing the needed
2615 // additional tests or scrubbing of the mark stack.
2616 //
2617 // However, we presently only nominate is_typeArray() objects.
2618 // A humongous object containing references induces remembered
2619 // set entries on other regions. In order to reclaim such an
2620 // object, those remembered sets would need to be cleaned up.
2621 //
2622 // We also treat is_typeArray() objects specially, allowing them
2623 // to be reclaimed even if allocated before the start of
2624 // concurrent mark. For this we rely on mark stack insertion to
2625 // exclude is_typeArray() objects, preventing reclaiming an object
2626 // that is in the mark stack. We also rely on the metadata for
2627 // such objects to be built-in and so ensured to be kept live.
2628 // Frequent allocation and drop of large binary blobs is an
2629 // important use case for eager reclaim, and this special handling
2630 // may reduce needed headroom.
2631
2632 return obj->is_typeArray() &&
2633 g1h->is_potential_eager_reclaim_candidate(region);
2634 }
2635
2636 public:
2637 RegisterHumongousWithInCSetFastTestClosure()
2638 : _total_humongous(0),
2639 _candidate_humongous(0),
2640 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2641 }
2642
2643 virtual bool do_heap_region(HeapRegion* r) {
2644 if (!r->is_starts_humongous()) {
2645 return false;
2646 }
2647 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2648
2649 bool is_candidate = humongous_region_is_candidate(g1h, r);
2650 uint rindex = r->hrm_index();
2651 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2652 if (is_candidate) {
2653 _candidate_humongous++;
2654 g1h->register_humongous_region_with_cset(rindex);
2655 // Is_candidate already filters out humongous object with large remembered sets.
2656 // If we have a humongous object with a few remembered sets, we simply flush these
2657 // remembered set entries into the DCQS. That will result in automatic
2658 // re-evaluation of their remembered set entries during the following evacuation
2659 // phase.
2660 if (!r->rem_set()->is_empty()) {
2661 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2662 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2663 G1CardTable* ct = g1h->card_table();
2664 HeapRegionRemSetIterator hrrs(r->rem_set());
2665 size_t card_index;
2666 while (hrrs.has_next(card_index)) {
2667 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2668 // The remembered set might contain references to already freed
2669 // regions. Filter out such entries to avoid failing card table
2670 // verification.
2671 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2672 if (*card_ptr != G1CardTable::dirty_card_val()) {
2673 *card_ptr = G1CardTable::dirty_card_val();
2674 _dcq.enqueue(card_ptr);
2675 }
2676 }
2677 }
2678 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2679 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2680 hrrs.n_yielded(), r->rem_set()->occupied());
2681 // We should only clear the card based remembered set here as we will not
2682 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2683 // (and probably never) we do not enter this path if there are other kind of
2684 // remembered sets for this region.
2685 r->rem_set()->clear_locked(true /* only_cardset */);
2686 // Clear_locked() above sets the state to Empty. However we want to continue
2687 // collecting remembered set entries for humongous regions that were not
2688 // reclaimed.
2689 r->rem_set()->set_state_complete();
2690 }
2691 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2692 }
2693 _total_humongous++;
2694
2695 return false;
2696 }
2697
2698 size_t total_humongous() const { return _total_humongous; }
2699 size_t candidate_humongous() const { return _candidate_humongous; }
2700
2701 void flush_rem_set_entries() { _dcq.flush(); }
2702 };
2703
2704 void G1CollectedHeap::register_humongous_regions_with_cset() {
2705 if (!G1EagerReclaimHumongousObjects) {
2706 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2707 return;
2708 }
2709 double time = os::elapsed_counter();
2710
2711 // Collect reclaim candidate information and register candidates with cset.
2712 RegisterHumongousWithInCSetFastTestClosure cl;
2713 heap_region_iterate(&cl);
2714
2715 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2716 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2717 cl.total_humongous(),
2718 cl.candidate_humongous());
2719 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2720
2721 // Finally flush all remembered set entries to re-check into the global DCQS.
2722 cl.flush_rem_set_entries();
2723 }
2724
2725 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2726 public:
2727 bool do_heap_region(HeapRegion* hr) {
2728 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2729 hr->verify_rem_set();
2730 }
2731 return false;
2732 }
2733 };
2734
2735 uint G1CollectedHeap::num_task_queues() const {
2736 return _task_queues->size();
2737 }
2738
2739 #if TASKQUEUE_STATS
2740 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2741 st->print_raw_cr("GC Task Stats");
2742 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2743 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2744 }
2745
2746 void G1CollectedHeap::print_taskqueue_stats() const {
2747 if (!log_is_enabled(Trace, gc, task, stats)) {
2748 return;
2749 }
2750 Log(gc, task, stats) log;
2751 ResourceMark rm;
2752 LogStream ls(log.trace());
2753 outputStream* st = &ls;
2754
2755 print_taskqueue_stats_hdr(st);
2756
2757 TaskQueueStats totals;
2758 const uint n = num_task_queues();
2759 for (uint i = 0; i < n; ++i) {
2760 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2761 totals += task_queue(i)->stats;
2762 }
2763 st->print_raw("tot "); totals.print(st); st->cr();
2764
2765 DEBUG_ONLY(totals.verify());
2766 }
2767
2768 void G1CollectedHeap::reset_taskqueue_stats() {
2769 const uint n = num_task_queues();
2770 for (uint i = 0; i < n; ++i) {
2771 task_queue(i)->stats.reset();
2772 }
2773 }
2774 #endif // TASKQUEUE_STATS
2775
2776 void G1CollectedHeap::wait_for_root_region_scanning() {
2777 double scan_wait_start = os::elapsedTime();
2778 // We have to wait until the CM threads finish scanning the
2779 // root regions as it's the only way to ensure that all the
2780 // objects on them have been correctly scanned before we start
2781 // moving them during the GC.
2782 bool waited = _cm->root_regions()->wait_until_scan_finished();
2783 double wait_time_ms = 0.0;
2784 if (waited) {
2785 double scan_wait_end = os::elapsedTime();
2786 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2787 }
2788 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2789 }
2790
2791 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2792 private:
2793 G1HRPrinter* _hr_printer;
2794 public:
2795 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2796
2797 virtual bool do_heap_region(HeapRegion* r) {
2798 _hr_printer->cset(r);
2799 return false;
2800 }
2801 };
2802
2803 void G1CollectedHeap::start_new_collection_set() {
2804 collection_set()->start_incremental_building();
2805
2806 clear_cset_fast_test();
2807
2808 guarantee(_eden.length() == 0, "eden should have been cleared");
2809 g1_policy()->transfer_survivors_to_cset(survivor());
2810 }
2811
2812 bool
2813 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2814 assert_at_safepoint_on_vm_thread();
2815 guarantee(!is_gc_active(), "collection is not reentrant");
2816
2817 if (GCLocker::check_active_before_gc()) {
2818 return false;
2819 }
2820
2821 _gc_timer_stw->register_gc_start();
2822
2823 GCIdMark gc_id_mark;
2824 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2825
2826 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2827 ResourceMark rm;
2828
2829 g1_policy()->note_gc_start();
2830
2831 wait_for_root_region_scanning();
2832
2833 print_heap_before_gc();
2834 print_heap_regions();
2835 trace_heap_before_gc(_gc_tracer_stw);
2836
2837 _verifier->verify_region_sets_optional();
2838 _verifier->verify_dirty_young_regions();
2839
2840 // We should not be doing initial mark unless the conc mark thread is running
2841 if (!_cm_thread->should_terminate()) {
2842 // This call will decide whether this pause is an initial-mark
2843 // pause. If it is, in_initial_mark_gc() will return true
2844 // for the duration of this pause.
2845 g1_policy()->decide_on_conc_mark_initiation();
2846 }
2847
2848 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2849 assert(!collector_state()->in_initial_mark_gc() ||
2850 collector_state()->in_young_only_phase(), "sanity");
2851
2852 // We also do not allow mixed GCs during marking.
2853 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2854
2855 // Record whether this pause is an initial mark. When the current
2856 // thread has completed its logging output and it's safe to signal
2857 // the CM thread, the flag's value in the policy has been reset.
2858 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2859
2860 // Inner scope for scope based logging, timers, and stats collection
2861 {
2862 EvacuationInfo evacuation_info;
2863
2864 if (collector_state()->in_initial_mark_gc()) {
2865 // We are about to start a marking cycle, so we increment the
2866 // full collection counter.
2867 increment_old_marking_cycles_started();
2868 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2869 }
2870
2871 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2872
2873 GCTraceCPUTime tcpu;
2874
2875 G1HeapVerifier::G1VerifyType verify_type;
2876 FormatBuffer<> gc_string("Pause Young ");
2877 if (collector_state()->in_initial_mark_gc()) {
2878 gc_string.append("(Concurrent Start)");
2879 verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2880 } else if (collector_state()->in_young_only_phase()) {
2881 if (collector_state()->in_young_gc_before_mixed()) {
2882 gc_string.append("(Prepare Mixed)");
2883 } else {
2884 gc_string.append("(Normal)");
2885 }
2886 verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2887 } else {
2888 gc_string.append("(Mixed)");
2889 verify_type = G1HeapVerifier::G1VerifyMixed;
2890 }
2891 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2892
2893 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2894 workers()->active_workers(),
2895 Threads::number_of_non_daemon_threads());
2896 active_workers = workers()->update_active_workers(active_workers);
2897 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2898
2899 G1MonitoringScope ms(g1mm(),
2900 false /* full_gc */,
2901 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2902
2903 G1HeapTransition heap_transition(this);
2904 size_t heap_used_bytes_before_gc = used();
2905
2906 // Don't dynamically change the number of GC threads this early. A value of
2907 // 0 is used to indicate serial work. When parallel work is done,
2908 // it will be set.
2909
2910 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2911 IsGCActiveMark x;
2912
2913 gc_prologue(false);
2914
2915 if (VerifyRememberedSets) {
2916 log_info(gc, verify)("[Verifying RemSets before GC]");
2917 VerifyRegionRemSetClosure v_cl;
2918 heap_region_iterate(&v_cl);
2919 }
2920
2921 _verifier->verify_before_gc(verify_type);
2922
2923 _verifier->check_bitmaps("GC Start");
2924
2925 #if COMPILER2_OR_JVMCI
2926 DerivedPointerTable::clear();
2927 #endif
2928
2929 // Please see comment in g1CollectedHeap.hpp and
2930 // G1CollectedHeap::ref_processing_init() to see how
2931 // reference processing currently works in G1.
2932
2933 // Enable discovery in the STW reference processor
2934 _ref_processor_stw->enable_discovery();
2935
2936 {
2937 // We want to temporarily turn off discovery by the
2938 // CM ref processor, if necessary, and turn it back on
2939 // on again later if we do. Using a scoped
2940 // NoRefDiscovery object will do this.
2941 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2942
2943 // Forget the current alloc region (we might even choose it to be part
2944 // of the collection set!).
2945 _allocator->release_mutator_alloc_region();
2946
2947 // This timing is only used by the ergonomics to handle our pause target.
2948 // It is unclear why this should not include the full pause. We will
2949 // investigate this in CR 7178365.
2950 //
2951 // Preserving the old comment here if that helps the investigation:
2952 //
2953 // The elapsed time induced by the start time below deliberately elides
2954 // the possible verification above.
2955 double sample_start_time_sec = os::elapsedTime();
2956
2957 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2958
2959 if (collector_state()->in_initial_mark_gc()) {
2960 concurrent_mark()->pre_initial_mark();
2961 }
2962
2963 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2964
2965 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2966
2967 // Make sure the remembered sets are up to date. This needs to be
2968 // done before register_humongous_regions_with_cset(), because the
2969 // remembered sets are used there to choose eager reclaim candidates.
2970 // If the remembered sets are not up to date we might miss some
2971 // entries that need to be handled.
2972 g1_rem_set()->cleanupHRRS();
2973
2974 register_humongous_regions_with_cset();
2975
2976 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2977
2978 // We call this after finalize_cset() to
2979 // ensure that the CSet has been finalized.
2980 _cm->verify_no_cset_oops();
2981
2982 if (_hr_printer.is_active()) {
2983 G1PrintCollectionSetClosure cl(&_hr_printer);
2984 _collection_set.iterate(&cl);
2985 }
2986
2987 // Initialize the GC alloc regions.
2988 _allocator->init_gc_alloc_regions(evacuation_info);
2989
2990 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2991 pre_evacuate_collection_set();
2992
2993 // Actually do the work...
2994 evacuate_collection_set(&per_thread_states);
2995
2996 post_evacuate_collection_set(evacuation_info, &per_thread_states);
2997
2998 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2999 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3000
3001 eagerly_reclaim_humongous_regions();
3002
3003 record_obj_copy_mem_stats();
3004 _survivor_evac_stats.adjust_desired_plab_sz();
3005 _old_evac_stats.adjust_desired_plab_sz();
3006
3007 double start = os::elapsedTime();
3008 start_new_collection_set();
3009 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3010
3011 if (evacuation_failed()) {
3012 double recalculate_used_start = os::elapsedTime();
3013 set_used(recalculate_used());
3014 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3015
3016 if (_archive_allocator != NULL) {
3017 _archive_allocator->clear_used();
3018 }
3019 for (uint i = 0; i < ParallelGCThreads; i++) {
3020 if (_evacuation_failed_info_array[i].has_failed()) {
3021 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3022 }
3023 }
3024 } else {
3025 // The "used" of the the collection set have already been subtracted
3026 // when they were freed. Add in the bytes evacuated.
3027 increase_used(g1_policy()->bytes_copied_during_gc());
3028 }
3029
3030 if (collector_state()->in_initial_mark_gc()) {
3031 // We have to do this before we notify the CM threads that
3032 // they can start working to make sure that all the
3033 // appropriate initialization is done on the CM object.
3034 concurrent_mark()->post_initial_mark();
3035 // Note that we don't actually trigger the CM thread at
3036 // this point. We do that later when we're sure that
3037 // the current thread has completed its logging output.
3038 }
3039
3040 allocate_dummy_regions();
3041
3042 _allocator->init_mutator_alloc_region();
3043
3044 {
3045 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3046 if (expand_bytes > 0) {
3047 size_t bytes_before = capacity();
3048 // No need for an ergo logging here,
3049 // expansion_amount() does this when it returns a value > 0.
3050 double expand_ms;
3051 if (!expand(expand_bytes, _workers, &expand_ms)) {
3052 // We failed to expand the heap. Cannot do anything about it.
3053 }
3054 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3055 }
3056 }
3057
3058 // We redo the verification but now wrt to the new CSet which
3059 // has just got initialized after the previous CSet was freed.
3060 _cm->verify_no_cset_oops();
3061
3062 // This timing is only used by the ergonomics to handle our pause target.
3063 // It is unclear why this should not include the full pause. We will
3064 // investigate this in CR 7178365.
3065 double sample_end_time_sec = os::elapsedTime();
3066 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3067 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3068 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3069
3070 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3071 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3072
3073 if (VerifyRememberedSets) {
3074 log_info(gc, verify)("[Verifying RemSets after GC]");
3075 VerifyRegionRemSetClosure v_cl;
3076 heap_region_iterate(&v_cl);
3077 }
3078
3079 _verifier->verify_after_gc(verify_type);
3080 _verifier->check_bitmaps("GC End");
3081
3082 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3083 _ref_processor_stw->verify_no_references_recorded();
3084
3085 // CM reference discovery will be re-enabled if necessary.
3086 }
3087
3088 #ifdef TRACESPINNING
3089 ParallelTaskTerminator::print_termination_counts();
3090 #endif
3091
3092 gc_epilogue(false);
3093 }
3094
3095 // Print the remainder of the GC log output.
3096 if (evacuation_failed()) {
3097 log_info(gc)("To-space exhausted");
3098 }
3099
3100 g1_policy()->print_phases();
3101 heap_transition.print();
3102
3103 // It is not yet to safe to tell the concurrent mark to
3104 // start as we have some optional output below. We don't want the
3105 // output from the concurrent mark thread interfering with this
3106 // logging output either.
3107
3108 _hrm.verify_optional();
3109 _verifier->verify_region_sets_optional();
3110
3111 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3112 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3113
3114 print_heap_after_gc();
3115 print_heap_regions();
3116 trace_heap_after_gc(_gc_tracer_stw);
3117
3118 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3119 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3120 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3121 // before any GC notifications are raised.
3122 g1mm()->update_sizes();
3123
3124 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3125 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3126 _gc_timer_stw->register_gc_end();
3127 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3128 }
3129 // It should now be safe to tell the concurrent mark thread to start
3130 // without its logging output interfering with the logging output
3131 // that came from the pause.
3132
3133 if (should_start_conc_mark) {
3134 // CAUTION: after the doConcurrentMark() call below,
3135 // the concurrent marking thread(s) could be running
3136 // concurrently with us. Make sure that anything after
3137 // this point does not assume that we are the only GC thread
3138 // running. Note: of course, the actual marking work will
3139 // not start until the safepoint itself is released in
3140 // SuspendibleThreadSet::desynchronize().
3141 do_concurrent_mark();
3142 }
3143
3144 return true;
3145 }
3146
3147 void G1CollectedHeap::remove_self_forwarding_pointers() {
3148 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3149 workers()->run_task(&rsfp_task);
3150 }
3151
3152 void G1CollectedHeap::restore_after_evac_failure() {
3153 double remove_self_forwards_start = os::elapsedTime();
3154
3155 remove_self_forwarding_pointers();
3156 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3157 _preserved_marks_set.restore(&task_executor);
3158
3159 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3160 }
3161
3162 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3163 if (!_evacuation_failed) {
3164 _evacuation_failed = true;
3165 }
3166
3167 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3168 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3169 }
3170
3171 bool G1ParEvacuateFollowersClosure::offer_termination() {
3172 G1ParScanThreadState* const pss = par_scan_state();
3173 start_term_time();
3174 const bool res = terminator()->offer_termination();
3175 end_term_time();
3176 return res;
3177 }
3178
3179 void G1ParEvacuateFollowersClosure::do_void() {
3180 G1ParScanThreadState* const pss = par_scan_state();
3181 pss->trim_queue();
3182 do {
3183 pss->steal_and_trim_queue(queues());
3184 } while (!offer_termination());
3185 }
3186
3187 class G1ParTask : public AbstractGangTask {
3188 protected:
3189 G1CollectedHeap* _g1h;
3190 G1ParScanThreadStateSet* _pss;
3191 RefToScanQueueSet* _queues;
3192 G1RootProcessor* _root_processor;
3193 ParallelTaskTerminator _terminator;
3194 uint _n_workers;
3195
3196 public:
3197 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3198 : AbstractGangTask("G1 collection"),
3199 _g1h(g1h),
3200 _pss(per_thread_states),
3201 _queues(task_queues),
3202 _root_processor(root_processor),
3203 _terminator(n_workers, _queues),
3204 _n_workers(n_workers)
3205 {}
3206
3207 void work(uint worker_id) {
3208 if (worker_id >= _n_workers) return; // no work needed this round
3209
3210 double start_sec = os::elapsedTime();
3211 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3212
3213 {
3214 ResourceMark rm;
3215 HandleMark hm;
3216
3217 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3218
3219 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3220 pss->set_ref_discoverer(rp);
3221
3222 double start_strong_roots_sec = os::elapsedTime();
3223
3224 _root_processor->evacuate_roots(pss, worker_id);
3225
3226 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3227 // treating the nmethods visited to act as roots for concurrent marking.
3228 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3229 // objects copied by the current evacuation.
3230 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3231
3232 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3233
3234 double term_sec = 0.0;
3235 size_t evac_term_attempts = 0;
3236 {
3237 double start = os::elapsedTime();
3238 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3239 evac.do_void();
3240
3241 evac_term_attempts = evac.term_attempts();
3242 term_sec = evac.term_time();
3243 double elapsed_sec = os::elapsedTime() - start;
3244
3245 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3246 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3247 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3248 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3249 }
3250
3251 assert(pss->queue_is_empty(), "should be empty");
3252
3253 if (log_is_enabled(Debug, gc, task, stats)) {
3254 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3255 size_t lab_waste;
3256 size_t lab_undo_waste;
3257 pss->waste(lab_waste, lab_undo_waste);
3258 _g1h->print_termination_stats(worker_id,
3259 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3260 strong_roots_sec * 1000.0, /* strong roots time */
3261 term_sec * 1000.0, /* evac term time */
3262 evac_term_attempts, /* evac term attempts */
3263 lab_waste, /* alloc buffer waste */
3264 lab_undo_waste /* undo waste */
3265 );
3266 }
3267
3268 // Close the inner scope so that the ResourceMark and HandleMark
3269 // destructors are executed here and are included as part of the
3270 // "GC Worker Time".
3271 }
3272 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3273 }
3274 };
3275
3276 void G1CollectedHeap::print_termination_stats_hdr() {
3277 log_debug(gc, task, stats)("GC Termination Stats");
3278 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3279 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3280 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3281 }
3282
3283 void G1CollectedHeap::print_termination_stats(uint worker_id,
3284 double elapsed_ms,
3285 double strong_roots_ms,
3286 double term_ms,
3287 size_t term_attempts,
3288 size_t alloc_buffer_waste,
3289 size_t undo_waste) const {
3290 log_debug(gc, task, stats)
3291 ("%3d %9.2f %9.2f %6.2f "
3292 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3293 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3294 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3295 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3296 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3297 alloc_buffer_waste * HeapWordSize / K,
3298 undo_waste * HeapWordSize / K);
3299 }
3300
3301 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3302 bool class_unloading_occurred) {
3303 uint n_workers = workers()->active_workers();
3304
3305 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3306 ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
3307 workers()->run_task(&g1_unlink_task);
3308 }
3309
3310 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3311 bool process_strings,
3312 bool process_string_dedup) {
3313 if (!process_strings && !process_string_dedup) {
3314 // Nothing to clean.
3315 return;
3316 }
3317
3318 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3319 StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
3320 workers()->run_task(&g1_unlink_task);
3321 }
3322
3323 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3324 private:
3325 DirtyCardQueueSet* _queue;
3326 G1CollectedHeap* _g1h;
3327 public:
3328 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3329 _queue(queue), _g1h(g1h) { }
3330
3331 virtual void work(uint worker_id) {
3332 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3333 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3334
3335 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3336 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3337
3338 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3339 }
3340 };
3341
3342 void G1CollectedHeap::redirty_logged_cards() {
3343 double redirty_logged_cards_start = os::elapsedTime();
3344
3345 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3346 dirty_card_queue_set().reset_for_par_iteration();
3347 workers()->run_task(&redirty_task);
3348
3349 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3350 dcq.merge_bufferlists(&dirty_card_queue_set());
3351 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3352
3353 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3354 }
3355
3356 // Weak Reference Processing support
3357
3358 bool G1STWIsAliveClosure::do_object_b(oop p) {
3359 // An object is reachable if it is outside the collection set,
3360 // or is inside and copied.
3361 return !_g1h->is_in_cset(p) || p->is_forwarded();
3362 }
3363
3364 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3365 assert(obj != NULL, "must not be NULL");
3366 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3367 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3368 // may falsely indicate that this is not the case here: however the collection set only
3369 // contains old regions when concurrent mark is not running.
3370 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3371 }
3372
3373 // Non Copying Keep Alive closure
3374 class G1KeepAliveClosure: public OopClosure {
3375 G1CollectedHeap*_g1h;
3376 public:
3377 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3378 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3379 void do_oop(oop* p) {
3380 oop obj = *p;
3381 assert(obj != NULL, "the caller should have filtered out NULL values");
3382
3383 const InCSetState cset_state =_g1h->in_cset_state(obj);
3384 if (!cset_state.is_in_cset_or_humongous()) {
3385 return;
3386 }
3387 if (cset_state.is_in_cset()) {
3388 assert( obj->is_forwarded(), "invariant" );
3389 *p = obj->forwardee();
3390 } else {
3391 assert(!obj->is_forwarded(), "invariant" );
3392 assert(cset_state.is_humongous(),
3393 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3394 _g1h->set_humongous_is_live(obj);
3395 }
3396 }
3397 };
3398
3399 // Copying Keep Alive closure - can be called from both
3400 // serial and parallel code as long as different worker
3401 // threads utilize different G1ParScanThreadState instances
3402 // and different queues.
3403
3404 class G1CopyingKeepAliveClosure: public OopClosure {
3405 G1CollectedHeap* _g1h;
3406 G1ParScanThreadState* _par_scan_state;
3407
3408 public:
3409 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3410 G1ParScanThreadState* pss):
3411 _g1h(g1h),
3412 _par_scan_state(pss)
3413 {}
3414
3415 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3416 virtual void do_oop( oop* p) { do_oop_work(p); }
3417
3418 template <class T> void do_oop_work(T* p) {
3419 oop obj = RawAccess<>::oop_load(p);
3420
3421 if (_g1h->is_in_cset_or_humongous(obj)) {
3422 // If the referent object has been forwarded (either copied
3423 // to a new location or to itself in the event of an
3424 // evacuation failure) then we need to update the reference
3425 // field and, if both reference and referent are in the G1
3426 // heap, update the RSet for the referent.
3427 //
3428 // If the referent has not been forwarded then we have to keep
3429 // it alive by policy. Therefore we have copy the referent.
3430 //
3431 // When the queue is drained (after each phase of reference processing)
3432 // the object and it's followers will be copied, the reference field set
3433 // to point to the new location, and the RSet updated.
3434 _par_scan_state->push_on_queue(p);
3435 }
3436 }
3437 };
3438
3439 // Serial drain queue closure. Called as the 'complete_gc'
3440 // closure for each discovered list in some of the
3441 // reference processing phases.
3442
3443 class G1STWDrainQueueClosure: public VoidClosure {
3444 protected:
3445 G1CollectedHeap* _g1h;
3446 G1ParScanThreadState* _par_scan_state;
3447
3448 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3449
3450 public:
3451 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3452 _g1h(g1h),
3453 _par_scan_state(pss)
3454 { }
3455
3456 void do_void() {
3457 G1ParScanThreadState* const pss = par_scan_state();
3458 pss->trim_queue();
3459 }
3460 };
3461
3462 // Parallel Reference Processing closures
3463
3464 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3465 // processing during G1 evacuation pauses.
3466
3467 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3468 private:
3469 G1CollectedHeap* _g1h;
3470 G1ParScanThreadStateSet* _pss;
3471 RefToScanQueueSet* _queues;
3472 WorkGang* _workers;
3473
3474 public:
3475 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3476 G1ParScanThreadStateSet* per_thread_states,
3477 WorkGang* workers,
3478 RefToScanQueueSet *task_queues) :
3479 _g1h(g1h),
3480 _pss(per_thread_states),
3481 _queues(task_queues),
3482 _workers(workers)
3483 {
3484 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3485 }
3486
3487 // Executes the given task using concurrent marking worker threads.
3488 virtual void execute(ProcessTask& task, uint ergo_workers);
3489 };
3490
3491 // Gang task for possibly parallel reference processing
3492
3493 class G1STWRefProcTaskProxy: public AbstractGangTask {
3494 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3495 ProcessTask& _proc_task;
3496 G1CollectedHeap* _g1h;
3497 G1ParScanThreadStateSet* _pss;
3498 RefToScanQueueSet* _task_queues;
3499 ParallelTaskTerminator* _terminator;
3500
3501 public:
3502 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3503 G1CollectedHeap* g1h,
3504 G1ParScanThreadStateSet* per_thread_states,
3505 RefToScanQueueSet *task_queues,
3506 ParallelTaskTerminator* terminator) :
3507 AbstractGangTask("Process reference objects in parallel"),
3508 _proc_task(proc_task),
3509 _g1h(g1h),
3510 _pss(per_thread_states),
3511 _task_queues(task_queues),
3512 _terminator(terminator)
3513 {}
3514
3515 virtual void work(uint worker_id) {
3516 // The reference processing task executed by a single worker.
3517 ResourceMark rm;
3518 HandleMark hm;
3519
3520 G1STWIsAliveClosure is_alive(_g1h);
3521
3522 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3523 pss->set_ref_discoverer(NULL);
3524
3525 // Keep alive closure.
3526 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3527
3528 // Complete GC closure
3529 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3530
3531 // Call the reference processing task's work routine.
3532 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3533
3534 // Note we cannot assert that the refs array is empty here as not all
3535 // of the processing tasks (specifically phase2 - pp2_work) execute
3536 // the complete_gc closure (which ordinarily would drain the queue) so
3537 // the queue may not be empty.
3538 }
3539 };
3540
3541 // Driver routine for parallel reference processing.
3542 // Creates an instance of the ref processing gang
3543 // task and has the worker threads execute it.
3544 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3545 assert(_workers != NULL, "Need parallel worker threads.");
3546
3547 assert(_workers->active_workers() >= ergo_workers,
3548 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3549 ergo_workers, _workers->active_workers());
3550 ParallelTaskTerminator terminator(ergo_workers, _queues);
3551 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3552
3553 _workers->run_task(&proc_task_proxy, ergo_workers);
3554 }
3555
3556 // End of weak reference support closures
3557
3558 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3559 double ref_proc_start = os::elapsedTime();
3560
3561 ReferenceProcessor* rp = _ref_processor_stw;
3562 assert(rp->discovery_enabled(), "should have been enabled");
3563
3564 // Closure to test whether a referent is alive.
3565 G1STWIsAliveClosure is_alive(this);
3566
3567 // Even when parallel reference processing is enabled, the processing
3568 // of JNI refs is serial and performed serially by the current thread
3569 // rather than by a worker. The following PSS will be used for processing
3570 // JNI refs.
3571
3572 // Use only a single queue for this PSS.
3573 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3574 pss->set_ref_discoverer(NULL);
3575 assert(pss->queue_is_empty(), "pre-condition");
3576
3577 // Keep alive closure.
3578 G1CopyingKeepAliveClosure keep_alive(this, pss);
3579
3580 // Serial Complete GC closure
3581 G1STWDrainQueueClosure drain_queue(this, pss);
3582
3583 // Setup the soft refs policy...
3584 rp->setup_policy(false);
3585
3586 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3587
3588 ReferenceProcessorStats stats;
3589 if (!rp->processing_is_mt()) {
3590 // Serial reference processing...
3591 stats = rp->process_discovered_references(&is_alive,
3592 &keep_alive,
3593 &drain_queue,
3594 NULL,
3595 pt);
3596 } else {
3597 uint no_of_gc_workers = workers()->active_workers();
3598
3599 // Parallel reference processing
3600 assert(no_of_gc_workers <= rp->max_num_queues(),
3601 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3602 no_of_gc_workers, rp->max_num_queues());
3603
3604 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3605 stats = rp->process_discovered_references(&is_alive,
3606 &keep_alive,
3607 &drain_queue,
3608 &par_task_executor,
3609 pt);
3610 }
3611
3612 _gc_tracer_stw->report_gc_reference_stats(stats);
3613
3614 // We have completed copying any necessary live referent objects.
3615 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3616
3617 make_pending_list_reachable();
3618
3619 rp->verify_no_references_recorded();
3620
3621 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3622 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3623 }
3624
3625 void G1CollectedHeap::make_pending_list_reachable() {
3626 if (collector_state()->in_initial_mark_gc()) {
3627 oop pll_head = Universe::reference_pending_list();
3628 if (pll_head != NULL) {
3629 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3630 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3631 }
3632 }
3633 }
3634
3635 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3636 double merge_pss_time_start = os::elapsedTime();
3637 per_thread_states->flush();
3638 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3639 }
3640
3641 void G1CollectedHeap::pre_evacuate_collection_set() {
3642 _expand_heap_after_alloc_failure = true;
3643 _evacuation_failed = false;
3644
3645 // Disable the hot card cache.
3646 _hot_card_cache->reset_hot_cache_claimed_index();
3647 _hot_card_cache->set_use_cache(false);
3648
3649 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3650 _preserved_marks_set.assert_empty();
3651
3652 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3653
3654 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3655 if (collector_state()->in_initial_mark_gc()) {
3656 double start_clear_claimed_marks = os::elapsedTime();
3657
3658 ClassLoaderDataGraph::clear_claimed_marks();
3659
3660 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3661 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3662 }
3663 }
3664
3665 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3666 // Should G1EvacuationFailureALot be in effect for this GC?
3667 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3668
3669 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3670
3671 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3672
3673 double start_par_time_sec = os::elapsedTime();
3674 double end_par_time_sec;
3675
3676 {
3677 const uint n_workers = workers()->active_workers();
3678 G1RootProcessor root_processor(this, n_workers);
3679 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3680
3681 print_termination_stats_hdr();
3682
3683 workers()->run_task(&g1_par_task);
3684 end_par_time_sec = os::elapsedTime();
3685
3686 // Closing the inner scope will execute the destructor
3687 // for the G1RootProcessor object. We record the current
3688 // elapsed time before closing the scope so that time
3689 // taken for the destructor is NOT included in the
3690 // reported parallel time.
3691 }
3692
3693 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3694 phase_times->record_par_time(par_time_ms);
3695
3696 double code_root_fixup_time_ms =
3697 (os::elapsedTime() - end_par_time_sec) * 1000.0;
3698 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3699 }
3700
3701 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3702 // Also cleans the card table from temporary duplicate detection information used
3703 // during UpdateRS/ScanRS.
3704 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3705
3706 // Process any discovered reference objects - we have
3707 // to do this _before_ we retire the GC alloc regions
3708 // as we may have to copy some 'reachable' referent
3709 // objects (and their reachable sub-graphs) that were
3710 // not copied during the pause.
3711 process_discovered_references(per_thread_states);
3712
3713 // FIXME
3714 // CM's reference processing also cleans up the string table.
3715 // Should we do that here also? We could, but it is a serial operation
3716 // and could significantly increase the pause time.
3717
3718 G1STWIsAliveClosure is_alive(this);
3719 G1KeepAliveClosure keep_alive(this);
3720
3721 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3722 g1_policy()->phase_times()->weak_phase_times());
3723
3724 if (G1StringDedup::is_enabled()) {
3725 double fixup_start = os::elapsedTime();
3726
3727 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
3728
3729 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
3730 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
3731 }
3732
3733 if (evacuation_failed()) {
3734 restore_after_evac_failure();
3735
3736 // Reset the G1EvacuationFailureALot counters and flags
3737 // Note: the values are reset only when an actual
3738 // evacuation failure occurs.
3739 NOT_PRODUCT(reset_evacuation_should_fail();)
3740 }
3741
3742 _preserved_marks_set.assert_empty();
3743
3744 _allocator->release_gc_alloc_regions(evacuation_info);
3745
3746 merge_per_thread_state_info(per_thread_states);
3747
3748 // Reset and re-enable the hot card cache.
3749 // Note the counts for the cards in the regions in the
3750 // collection set are reset when the collection set is freed.
3751 _hot_card_cache->reset_hot_cache();
3752 _hot_card_cache->set_use_cache(true);
3753
3754 purge_code_root_memory();
3755
3756 redirty_logged_cards();
3757 #if COMPILER2_OR_JVMCI
3758 double start = os::elapsedTime();
3759 DerivedPointerTable::update_pointers();
3760 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3761 #endif
3762 g1_policy()->print_age_table();
3763 }
3764
3765 void G1CollectedHeap::record_obj_copy_mem_stats() {
3766 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3767
3768 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3769 create_g1_evac_summary(&_old_evac_stats));
3770 }
3771
3772 void G1CollectedHeap::free_region(HeapRegion* hr,
3773 FreeRegionList* free_list,
3774 bool skip_remset,
3775 bool skip_hot_card_cache,
3776 bool locked) {
3777 assert(!hr->is_free(), "the region should not be free");
3778 assert(!hr->is_empty(), "the region should not be empty");
3779 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
3780 assert(free_list != NULL, "pre-condition");
3781
3782 if (G1VerifyBitmaps) {
3783 MemRegion mr(hr->bottom(), hr->end());
3784 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3785 }
3786
3787 // Clear the card counts for this region.
3788 // Note: we only need to do this if the region is not young
3789 // (since we don't refine cards in young regions).
3790 if (!skip_hot_card_cache && !hr->is_young()) {
3791 _hot_card_cache->reset_card_counts(hr);
3792 }
3793 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3794 _g1_policy->remset_tracker()->update_at_free(hr);
3795 free_list->add_ordered(hr);
3796 }
3797
3798 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3799 FreeRegionList* free_list) {
3800 assert(hr->is_humongous(), "this is only for humongous regions");
3801 assert(free_list != NULL, "pre-condition");
3802 hr->clear_humongous();
3803 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3804 }
3805
3806 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3807 const uint humongous_regions_removed) {
3808 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3809 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3810 _old_set.bulk_remove(old_regions_removed);
3811 _humongous_set.bulk_remove(humongous_regions_removed);
3812 }
3813
3814 }
3815
3816 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3817 assert(list != NULL, "list can't be null");
3818 if (!list->is_empty()) {
3819 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3820 _hrm.insert_list_into_free_list(list);
3821 }
3822 }
3823
3824 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3825 decrease_used(bytes);
3826 }
3827
3828 class G1FreeCollectionSetTask : public AbstractGangTask {
3829 private:
3830
3831 // Closure applied to all regions in the collection set to do work that needs to
3832 // be done serially in a single thread.
3833 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3834 private:
3835 EvacuationInfo* _evacuation_info;
3836 const size_t* _surviving_young_words;
3837
3838 // Bytes used in successfully evacuated regions before the evacuation.
3839 size_t _before_used_bytes;
3840 // Bytes used in unsucessfully evacuated regions before the evacuation
3841 size_t _after_used_bytes;
3842
3843 size_t _bytes_allocated_in_old_since_last_gc;
3844
3845 size_t _failure_used_words;
3846 size_t _failure_waste_words;
3847
3848 FreeRegionList _local_free_list;
3849 public:
3850 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3851 HeapRegionClosure(),
3852 _evacuation_info(evacuation_info),
3853 _surviving_young_words(surviving_young_words),
3854 _before_used_bytes(0),
3855 _after_used_bytes(0),
3856 _bytes_allocated_in_old_since_last_gc(0),
3857 _failure_used_words(0),
3858 _failure_waste_words(0),
3859 _local_free_list("Local Region List for CSet Freeing") {
3860 }
3861
3862 virtual bool do_heap_region(HeapRegion* r) {
3863 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3864
3865 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3866 g1h->clear_in_cset(r);
3867
3868 if (r->is_young()) {
3869 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3870 "Young index %d is wrong for region %u of type %s with %u young regions",
3871 r->young_index_in_cset(),
3872 r->hrm_index(),
3873 r->get_type_str(),
3874 g1h->collection_set()->young_region_length());
3875 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3876 r->record_surv_words_in_group(words_survived);
3877 }
3878
3879 if (!r->evacuation_failed()) {
3880 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
3881 _before_used_bytes += r->used();
3882 g1h->free_region(r,
3883 &_local_free_list,
3884 true, /* skip_remset */
3885 true, /* skip_hot_card_cache */
3886 true /* locked */);
3887 } else {
3888 r->uninstall_surv_rate_group();
3889 r->set_young_index_in_cset(-1);
3890 r->set_evacuation_failed(false);
3891 // When moving a young gen region to old gen, we "allocate" that whole region
3892 // there. This is in addition to any already evacuated objects. Notify the
3893 // policy about that.
3894 // Old gen regions do not cause an additional allocation: both the objects
3895 // still in the region and the ones already moved are accounted for elsewhere.
3896 if (r->is_young()) {
3897 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
3898 }
3899 // The region is now considered to be old.
3900 r->set_old();
3901 // Do some allocation statistics accounting. Regions that failed evacuation
3902 // are always made old, so there is no need to update anything in the young
3903 // gen statistics, but we need to update old gen statistics.
3904 size_t used_words = r->marked_bytes() / HeapWordSize;
3905
3906 _failure_used_words += used_words;
3907 _failure_waste_words += HeapRegion::GrainWords - used_words;
3908
3909 g1h->old_set_add(r);
3910 _after_used_bytes += r->used();
3911 }
3912 return false;
3913 }
3914
3915 void complete_work() {
3916 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3917
3918 _evacuation_info->set_regions_freed(_local_free_list.length());
3919 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
3920
3921 g1h->prepend_to_freelist(&_local_free_list);
3922 g1h->decrement_summary_bytes(_before_used_bytes);
3923
3924 G1Policy* policy = g1h->g1_policy();
3925 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
3926
3927 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
3928 }
3929 };
3930
3931 G1CollectionSet* _collection_set;
3932 G1SerialFreeCollectionSetClosure _cl;
3933 const size_t* _surviving_young_words;
3934
3935 size_t _rs_lengths;
3936
3937 volatile jint _serial_work_claim;
3938
3939 struct WorkItem {
3940 uint region_idx;
3941 bool is_young;
3942 bool evacuation_failed;
3943
3944 WorkItem(HeapRegion* r) {
3945 region_idx = r->hrm_index();
3946 is_young = r->is_young();
3947 evacuation_failed = r->evacuation_failed();
3948 }
3949 };
3950
3951 volatile size_t _parallel_work_claim;
3952 size_t _num_work_items;
3953 WorkItem* _work_items;
3954
3955 void do_serial_work() {
3956 // Need to grab the lock to be allowed to modify the old region list.
3957 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3958 _collection_set->iterate(&_cl);
3959 }
3960
3961 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
3962 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3963
3964 HeapRegion* r = g1h->region_at(region_idx);
3965 assert(!g1h->is_on_master_free_list(r), "sanity");
3966
3967 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
3968
3969 if (!is_young) {
3970 g1h->_hot_card_cache->reset_card_counts(r);
3971 }
3972
3973 if (!evacuation_failed) {
3974 r->rem_set()->clear_locked();
3975 }
3976 }
3977
3978 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
3979 private:
3980 size_t _cur_idx;
3981 WorkItem* _work_items;
3982 public:
3983 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
3984
3985 virtual bool do_heap_region(HeapRegion* r) {
3986 _work_items[_cur_idx++] = WorkItem(r);
3987 return false;
3988 }
3989 };
3990
3991 void prepare_work() {
3992 G1PrepareFreeCollectionSetClosure cl(_work_items);
3993 _collection_set->iterate(&cl);
3994 }
3995
3996 void complete_work() {
3997 _cl.complete_work();
3998
3999 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4000 policy->record_max_rs_lengths(_rs_lengths);
4001 policy->cset_regions_freed();
4002 }
4003 public:
4004 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4005 AbstractGangTask("G1 Free Collection Set"),
4006 _collection_set(collection_set),
4007 _cl(evacuation_info, surviving_young_words),
4008 _surviving_young_words(surviving_young_words),
4009 _rs_lengths(0),
4010 _serial_work_claim(0),
4011 _parallel_work_claim(0),
4012 _num_work_items(collection_set->region_length()),
4013 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4014 prepare_work();
4015 }
4016
4017 ~G1FreeCollectionSetTask() {
4018 complete_work();
4019 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4020 }
4021
4022 // Chunk size for work distribution. The chosen value has been determined experimentally
4023 // to be a good tradeoff between overhead and achievable parallelism.
4024 static uint chunk_size() { return 32; }
4025
4026 virtual void work(uint worker_id) {
4027 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4028
4029 // Claim serial work.
4030 if (_serial_work_claim == 0) {
4031 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4032 if (value == 0) {
4033 double serial_time = os::elapsedTime();
4034 do_serial_work();
4035 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4036 }
4037 }
4038
4039 // Start parallel work.
4040 double young_time = 0.0;
4041 bool has_young_time = false;
4042 double non_young_time = 0.0;
4043 bool has_non_young_time = false;
4044
4045 while (true) {
4046 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4047 size_t cur = end - chunk_size();
4048
4049 if (cur >= _num_work_items) {
4050 break;
4051 }
4052
4053 double start_time = os::elapsedTime();
4054
4055 end = MIN2(end, _num_work_items);
4056
4057 for (; cur < end; cur++) {
4058 bool is_young = _work_items[cur].is_young;
4059
4060 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4061
4062 double end_time = os::elapsedTime();
4063 double time_taken = end_time - start_time;
4064 if (is_young) {
4065 young_time += time_taken;
4066 has_young_time = true;
4067 } else {
4068 non_young_time += time_taken;
4069 has_non_young_time = true;
4070 }
4071 start_time = end_time;
4072 }
4073 }
4074
4075 if (has_young_time) {
4076 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4077 }
4078 if (has_non_young_time) {
4079 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4080 }
4081 }
4082 };
4083
4084 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4085 _eden.clear();
4086
4087 double free_cset_start_time = os::elapsedTime();
4088
4089 {
4090 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4091 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4092
4093 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4094
4095 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4096 cl.name(),
4097 num_workers,
4098 _collection_set.region_length());
4099 workers()->run_task(&cl, num_workers);
4100 }
4101 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4102
4103 collection_set->clear();
4104 }
4105
4106 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4107 private:
4108 FreeRegionList* _free_region_list;
4109 HeapRegionSet* _proxy_set;
4110 uint _humongous_objects_reclaimed;
4111 uint _humongous_regions_reclaimed;
4112 size_t _freed_bytes;
4113 public:
4114
4115 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4116 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4117 }
4118
4119 virtual bool do_heap_region(HeapRegion* r) {
4120 if (!r->is_starts_humongous()) {
4121 return false;
4122 }
4123
4124 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4125
4126 oop obj = (oop)r->bottom();
4127 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4128
4129 // The following checks whether the humongous object is live are sufficient.
4130 // The main additional check (in addition to having a reference from the roots
4131 // or the young gen) is whether the humongous object has a remembered set entry.
4132 //
4133 // A humongous object cannot be live if there is no remembered set for it
4134 // because:
4135 // - there can be no references from within humongous starts regions referencing
4136 // the object because we never allocate other objects into them.
4137 // (I.e. there are no intra-region references that may be missed by the
4138 // remembered set)
4139 // - as soon there is a remembered set entry to the humongous starts region
4140 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4141 // until the end of a concurrent mark.
4142 //
4143 // It is not required to check whether the object has been found dead by marking
4144 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4145 // all objects allocated during that time are considered live.
4146 // SATB marking is even more conservative than the remembered set.
4147 // So if at this point in the collection there is no remembered set entry,
4148 // nobody has a reference to it.
4149 // At the start of collection we flush all refinement logs, and remembered sets
4150 // are completely up-to-date wrt to references to the humongous object.
4151 //
4152 // Other implementation considerations:
4153 // - never consider object arrays at this time because they would pose
4154 // considerable effort for cleaning up the the remembered sets. This is
4155 // required because stale remembered sets might reference locations that
4156 // are currently allocated into.
4157 uint region_idx = r->hrm_index();
4158 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4159 !r->rem_set()->is_empty()) {
4160 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",
4161 region_idx,
4162 (size_t)obj->size() * HeapWordSize,
4163 p2i(r->bottom()),
4164 r->rem_set()->occupied(),
4165 r->rem_set()->strong_code_roots_list_length(),
4166 next_bitmap->is_marked(r->bottom()),
4167 g1h->is_humongous_reclaim_candidate(region_idx),
4168 obj->is_typeArray()
4169 );
4170 return false;
4171 }
4172
4173 guarantee(obj->is_typeArray(),
4174 "Only eagerly reclaiming type arrays is supported, but the object "
4175 PTR_FORMAT " is not.", p2i(r->bottom()));
4176
4177 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",
4178 region_idx,
4179 (size_t)obj->size() * HeapWordSize,
4180 p2i(r->bottom()),
4181 r->rem_set()->occupied(),
4182 r->rem_set()->strong_code_roots_list_length(),
4183 next_bitmap->is_marked(r->bottom()),
4184 g1h->is_humongous_reclaim_candidate(region_idx),
4185 obj->is_typeArray()
4186 );
4187
4188 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4189 cm->humongous_object_eagerly_reclaimed(r);
4190 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4191 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4192 region_idx,
4193 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4194 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4195 _humongous_objects_reclaimed++;
4196 do {
4197 HeapRegion* next = g1h->next_region_in_humongous(r);
4198 _freed_bytes += r->used();
4199 r->set_containing_set(NULL);
4200 _humongous_regions_reclaimed++;
4201 g1h->free_humongous_region(r, _free_region_list);
4202 r = next;
4203 } while (r != NULL);
4204
4205 return false;
4206 }
4207
4208 uint humongous_objects_reclaimed() {
4209 return _humongous_objects_reclaimed;
4210 }
4211
4212 uint humongous_regions_reclaimed() {
4213 return _humongous_regions_reclaimed;
4214 }
4215
4216 size_t bytes_freed() const {
4217 return _freed_bytes;
4218 }
4219 };
4220
4221 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4222 assert_at_safepoint_on_vm_thread();
4223
4224 if (!G1EagerReclaimHumongousObjects ||
4225 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4226 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4227 return;
4228 }
4229
4230 double start_time = os::elapsedTime();
4231
4232 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4233
4234 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4235 heap_region_iterate(&cl);
4236
4237 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4238
4239 G1HRPrinter* hrp = hr_printer();
4240 if (hrp->is_active()) {
4241 FreeRegionListIterator iter(&local_cleanup_list);
4242 while (iter.more_available()) {
4243 HeapRegion* hr = iter.get_next();
4244 hrp->cleanup(hr);
4245 }
4246 }
4247
4248 prepend_to_freelist(&local_cleanup_list);
4249 decrement_summary_bytes(cl.bytes_freed());
4250
4251 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4252 cl.humongous_objects_reclaimed());
4253 }
4254
4255 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4256 public:
4257 virtual bool do_heap_region(HeapRegion* r) {
4258 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4259 G1CollectedHeap::heap()->clear_in_cset(r);
4260 r->set_young_index_in_cset(-1);
4261 return false;
4262 }
4263 };
4264
4265 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4266 G1AbandonCollectionSetClosure cl;
4267 collection_set->iterate(&cl);
4268
4269 collection_set->clear();
4270 collection_set->stop_incremental_building();
4271 }
4272
4273 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4274 return _allocator->is_retained_old_region(hr);
4275 }
4276
4277 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4278 _eden.add(hr);
4279 _g1_policy->set_region_eden(hr);
4280 }
4281
4282 #ifdef ASSERT
4283
4284 class NoYoungRegionsClosure: public HeapRegionClosure {
4285 private:
4286 bool _success;
4287 public:
4288 NoYoungRegionsClosure() : _success(true) { }
4289 bool do_heap_region(HeapRegion* r) {
4290 if (r->is_young()) {
4291 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4292 p2i(r->bottom()), p2i(r->end()));
4293 _success = false;
4294 }
4295 return false;
4296 }
4297 bool success() { return _success; }
4298 };
4299
4300 bool G1CollectedHeap::check_young_list_empty() {
4301 bool ret = (young_regions_count() == 0);
4302
4303 NoYoungRegionsClosure closure;
4304 heap_region_iterate(&closure);
4305 ret = ret && closure.success();
4306
4307 return ret;
4308 }
4309
4310 #endif // ASSERT
4311
4312 class TearDownRegionSetsClosure : public HeapRegionClosure {
4313 HeapRegionSet *_old_set;
4314
4315 public:
4316 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4317
4318 bool do_heap_region(HeapRegion* r) {
4319 if (r->is_old()) {
4320 _old_set->remove(r);
4321 } else if(r->is_young()) {
4322 r->uninstall_surv_rate_group();
4323 } else {
4324 // We ignore free regions, we'll empty the free list afterwards.
4325 // We ignore humongous and archive regions, we're not tearing down these
4326 // sets.
4327 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4328 "it cannot be another type");
4329 }
4330 return false;
4331 }
4332
4333 ~TearDownRegionSetsClosure() {
4334 assert(_old_set->is_empty(), "post-condition");
4335 }
4336 };
4337
4338 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4339 assert_at_safepoint_on_vm_thread();
4340
4341 if (!free_list_only) {
4342 TearDownRegionSetsClosure cl(&_old_set);
4343 heap_region_iterate(&cl);
4344
4345 // Note that emptying the _young_list is postponed and instead done as
4346 // the first step when rebuilding the regions sets again. The reason for
4347 // this is that during a full GC string deduplication needs to know if
4348 // a collected region was young or old when the full GC was initiated.
4349 }
4350 _hrm.remove_all_free_regions();
4351 }
4352
4353 void G1CollectedHeap::increase_used(size_t bytes) {
4354 _summary_bytes_used += bytes;
4355 }
4356
4357 void G1CollectedHeap::decrease_used(size_t bytes) {
4358 assert(_summary_bytes_used >= bytes,
4359 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4360 _summary_bytes_used, bytes);
4361 _summary_bytes_used -= bytes;
4362 }
4363
4364 void G1CollectedHeap::set_used(size_t bytes) {
4365 _summary_bytes_used = bytes;
4366 }
4367
4368 class RebuildRegionSetsClosure : public HeapRegionClosure {
4369 private:
4370 bool _free_list_only;
4371
4372 HeapRegionSet* _old_set;
4373 HeapRegionManager* _hrm;
4374
4375 size_t _total_used;
4376
4377 public:
4378 RebuildRegionSetsClosure(bool free_list_only,
4379 HeapRegionSet* old_set,
4380 HeapRegionManager* hrm) :
4381 _free_list_only(free_list_only),
4382 _old_set(old_set), _hrm(hrm), _total_used(0) {
4383 assert(_hrm->num_free_regions() == 0, "pre-condition");
4384 if (!free_list_only) {
4385 assert(_old_set->is_empty(), "pre-condition");
4386 }
4387 }
4388
4389 bool do_heap_region(HeapRegion* r) {
4390 // After full GC, no region should have a remembered set.
4391 r->rem_set()->clear(true);
4392 if (r->is_empty()) {
4393 // Add free regions to the free list
4394 r->set_free();
4395 _hrm->insert_into_free_list(r);
4396 } else if (!_free_list_only) {
4397
4398 if (r->is_archive() || r->is_humongous()) {
4399 // We ignore archive and humongous regions. We left these sets unchanged.
4400 } else {
4401 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4402 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4403 r->move_to_old();
4404 _old_set->add(r);
4405 }
4406 _total_used += r->used();
4407 }
4408
4409 return false;
4410 }
4411
4412 size_t total_used() {
4413 return _total_used;
4414 }
4415 };
4416
4417 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4418 assert_at_safepoint_on_vm_thread();
4419
4420 if (!free_list_only) {
4421 _eden.clear();
4422 _survivor.clear();
4423 }
4424
4425 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4426 heap_region_iterate(&cl);
4427
4428 if (!free_list_only) {
4429 set_used(cl.total_used());
4430 if (_archive_allocator != NULL) {
4431 _archive_allocator->clear_used();
4432 }
4433 }
4434 assert(used_unlocked() == recalculate_used(),
4435 "inconsistent used_unlocked(), "
4436 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4437 used_unlocked(), recalculate_used());
4438 }
4439
4440 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4441 HeapRegion* hr = heap_region_containing(p);
4442 return hr->is_in(p);
4443 }
4444
4445 // Methods for the mutator alloc region
4446
4447 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4448 bool force) {
4449 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4450 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4451 if (force || should_allocate) {
4452 HeapRegion* new_alloc_region = new_region(word_size,
4453 false /* is_old */,
4454 false /* do_expand */);
4455 if (new_alloc_region != NULL) {
4456 set_region_short_lived_locked(new_alloc_region);
4457 _hr_printer.alloc(new_alloc_region, !should_allocate);
4458 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4459 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4460 return new_alloc_region;
4461 }
4462 }
4463 return NULL;
4464 }
4465
4466 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4467 size_t allocated_bytes) {
4468 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4469 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4470
4471 collection_set()->add_eden_region(alloc_region);
4472 increase_used(allocated_bytes);
4473 _hr_printer.retire(alloc_region);
4474 // We update the eden sizes here, when the region is retired,
4475 // instead of when it's allocated, since this is the point that its
4476 // used space has been recorded in _summary_bytes_used.
4477 g1mm()->update_eden_size();
4478 }
4479
4480 // Methods for the GC alloc regions
4481
4482 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4483 if (dest.is_old()) {
4484 return true;
4485 } else {
4486 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4487 }
4488 }
4489
4490 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4491 assert(FreeList_lock->owned_by_self(), "pre-condition");
4492
4493 if (!has_more_regions(dest)) {
4494 return NULL;
4495 }
4496
4497 const bool is_survivor = dest.is_young();
4498
4499 HeapRegion* new_alloc_region = new_region(word_size,
4500 !is_survivor,
4501 true /* do_expand */);
4502 if (new_alloc_region != NULL) {
4503 if (is_survivor) {
4504 new_alloc_region->set_survivor();
4505 _survivor.add(new_alloc_region);
4506 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4507 } else {
4508 new_alloc_region->set_old();
4509 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4510 }
4511 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4512 _hr_printer.alloc(new_alloc_region);
4513 bool during_im = collector_state()->in_initial_mark_gc();
4514 new_alloc_region->note_start_of_copying(during_im);
4515 return new_alloc_region;
4516 }
4517 return NULL;
4518 }
4519
4520 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4521 size_t allocated_bytes,
4522 InCSetState dest) {
4523 bool during_im = collector_state()->in_initial_mark_gc();
4524 alloc_region->note_end_of_copying(during_im);
4525 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4526 if (dest.is_old()) {
4527 old_set_add(alloc_region);
4528 }
4529 _hr_printer.retire(alloc_region);
4530 }
4531
4532 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4533 bool expanded = false;
4534 uint index = _hrm.find_highest_free(&expanded);
4535
4536 if (index != G1_NO_HRM_INDEX) {
4537 if (expanded) {
4538 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4539 HeapRegion::GrainWords * HeapWordSize);
4540 }
4541 _hrm.allocate_free_regions_starting_at(index, 1);
4542 return region_at(index);
4543 }
4544 return NULL;
4545 }
4546
4547 // Optimized nmethod scanning
4548
4549 class RegisterNMethodOopClosure: public OopClosure {
4550 G1CollectedHeap* _g1h;
4551 nmethod* _nm;
4552
4553 template <class T> void do_oop_work(T* p) {
4554 T heap_oop = RawAccess<>::oop_load(p);
4555 if (!CompressedOops::is_null(heap_oop)) {
4556 oop obj = CompressedOops::decode_not_null(heap_oop);
4557 HeapRegion* hr = _g1h->heap_region_containing(obj);
4558 assert(!hr->is_continues_humongous(),
4559 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4560 " starting at " HR_FORMAT,
4561 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4562
4563 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4564 hr->add_strong_code_root_locked(_nm);
4565 }
4566 }
4567
4568 public:
4569 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4570 _g1h(g1h), _nm(nm) {}
4571
4572 void do_oop(oop* p) { do_oop_work(p); }
4573 void do_oop(narrowOop* p) { do_oop_work(p); }
4574 };
4575
4576 class UnregisterNMethodOopClosure: public OopClosure {
4577 G1CollectedHeap* _g1h;
4578 nmethod* _nm;
4579
4580 template <class T> void do_oop_work(T* p) {
4581 T heap_oop = RawAccess<>::oop_load(p);
4582 if (!CompressedOops::is_null(heap_oop)) {
4583 oop obj = CompressedOops::decode_not_null(heap_oop);
4584 HeapRegion* hr = _g1h->heap_region_containing(obj);
4585 assert(!hr->is_continues_humongous(),
4586 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4587 " starting at " HR_FORMAT,
4588 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4589
4590 hr->remove_strong_code_root(_nm);
4591 }
4592 }
4593
4594 public:
4595 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4596 _g1h(g1h), _nm(nm) {}
4597
4598 void do_oop(oop* p) { do_oop_work(p); }
4599 void do_oop(narrowOop* p) { do_oop_work(p); }
4600 };
4601
4602 // Returns true if the reference points to an object that
4603 // can move in an incremental collection.
4604 bool G1CollectedHeap::is_scavengable(oop obj) {
4605 HeapRegion* hr = heap_region_containing(obj);
4606 return !hr->is_pinned();
4607 }
4608
4609 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4610 guarantee(nm != NULL, "sanity");
4611 RegisterNMethodOopClosure reg_cl(this, nm);
4612 nm->oops_do(®_cl);
4613 }
4614
4615 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4616 guarantee(nm != NULL, "sanity");
4617 UnregisterNMethodOopClosure reg_cl(this, nm);
4618 nm->oops_do(®_cl, true);
4619 }
4620
4621 void G1CollectedHeap::purge_code_root_memory() {
4622 double purge_start = os::elapsedTime();
4623 G1CodeRootSet::purge();
4624 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4625 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4626 }
4627
4628 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4629 G1CollectedHeap* _g1h;
4630
4631 public:
4632 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4633 _g1h(g1h) {}
4634
4635 void do_code_blob(CodeBlob* cb) {
4636 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4637 if (nm == NULL) {
4638 return;
4639 }
4640
4641 if (ScavengeRootsInCode) {
4642 _g1h->register_nmethod(nm);
4643 }
4644 }
4645 };
4646
4647 void G1CollectedHeap::rebuild_strong_code_roots() {
4648 RebuildStrongCodeRootClosure blob_cl(this);
4649 CodeCache::blobs_do(&blob_cl);
4650 }
4651
4652 void G1CollectedHeap::initialize_serviceability() {
4653 _g1mm->initialize_serviceability();
4654 }
4655
4656 MemoryUsage G1CollectedHeap::memory_usage() {
4657 return _g1mm->memory_usage();
4658 }
4659
4660 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4661 return _g1mm->memory_managers();
4662 }
4663
4664 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4665 return _g1mm->memory_pools();
4666 }