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/g1StringDedup.hpp"
55 #include "gc/g1/g1ThreadLocalData.hpp"
56 #include "gc/g1/g1YCTypes.hpp"
57 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
58 #include "gc/g1/heapRegion.inline.hpp"
59 #include "gc/g1/heapRegionRemSet.hpp"
60 #include "gc/g1/heapRegionSet.inline.hpp"
61 #include "gc/g1/vm_operations_g1.hpp"
62 #include "gc/shared/adaptiveSizePolicy.hpp"
63 #include "gc/shared/gcHeapSummary.hpp"
64 #include "gc/shared/gcId.hpp"
65 #include "gc/shared/gcLocker.hpp"
66 #include "gc/shared/gcTimer.hpp"
67 #include "gc/shared/gcTrace.hpp"
68 #include "gc/shared/gcTraceTime.inline.hpp"
69 #include "gc/shared/generationSpec.hpp"
70 #include "gc/shared/isGCActiveMark.hpp"
71 #include "gc/shared/oopStorageParState.hpp"
72 #include "gc/shared/preservedMarks.inline.hpp"
73 #include "gc/shared/suspendibleThreadSet.hpp"
74 #include "gc/shared/referenceProcessor.inline.hpp"
75 #include "gc/shared/taskqueue.inline.hpp"
76 #include "gc/shared/weakProcessor.hpp"
77 #include "logging/log.hpp"
78 #include "memory/allocation.hpp"
79 #include "memory/iterator.hpp"
80 #include "memory/metaspaceShared.hpp"
81 #include "memory/resourceArea.hpp"
82 #include "oops/access.inline.hpp"
83 #include "oops/compressedOops.inline.hpp"
84 #include "oops/oop.inline.hpp"
85 #include "prims/resolvedMethodTable.hpp"
86 #include "runtime/atomic.hpp"
87 #include "runtime/flags/flagSetting.hpp"
88 #include "runtime/handles.inline.hpp"
89 #include "runtime/init.hpp"
90 #include "runtime/orderAccess.hpp"
91 #include "runtime/threadSMR.hpp"
92 #include "runtime/vmThread.hpp"
93 #include "utilities/align.hpp"
94 #include "utilities/globalDefinitions.hpp"
95 #include "utilities/stack.inline.hpp"
96
97 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
98
99 // INVARIANTS/NOTES
100 //
101 // All allocation activity covered by the G1CollectedHeap interface is
102 // serialized by acquiring the HeapLock. This happens in mem_allocate
103 // and allocate_new_tlab, which are the "entry" points to the
104 // allocation code from the rest of the JVM. (Note that this does not
105 // apply to TLAB allocation, which is not part of this interface: it
106 // is done by clients of this interface.)
107
108 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
109 private:
110 size_t _num_dirtied;
111 G1CollectedHeap* _g1h;
112 G1CardTable* _g1_ct;
113
114 HeapRegion* region_for_card(jbyte* card_ptr) const {
115 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
116 }
117
118 bool will_become_free(HeapRegion* hr) const {
119 // A region will be freed by free_collection_set if the region is in the
120 // collection set and has not had an evacuation failure.
121 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
122 }
123
124 public:
125 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
126 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
127
128 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
129 HeapRegion* hr = region_for_card(card_ptr);
130
131 // Should only dirty cards in regions that won't be freed.
132 if (!will_become_free(hr)) {
133 *card_ptr = G1CardTable::dirty_card_val();
134 _num_dirtied++;
135 }
136
137 return true;
138 }
139
140 size_t num_dirtied() const { return _num_dirtied; }
141 };
142
143
144 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
145 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
146 }
147
148 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
149 // The from card cache is not the memory that is actually committed. So we cannot
150 // take advantage of the zero_filled parameter.
151 reset_from_card_cache(start_idx, num_regions);
152 }
153
154
155 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
156 MemRegion mr) {
157 return new HeapRegion(hrs_index, bot(), mr);
158 }
159
160 // Private methods.
161
162 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
163 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
164 "the only time we use this to allocate a humongous region is "
165 "when we are allocating a single humongous region");
166
167 HeapRegion* res = _hrm.allocate_free_region(is_old);
168
169 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
170 // Currently, only attempts to allocate GC alloc regions set
171 // do_expand to true. So, we should only reach here during a
172 // safepoint. If this assumption changes we might have to
173 // reconsider the use of _expand_heap_after_alloc_failure.
174 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
175
176 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
177 word_size * HeapWordSize);
178
179 if (expand(word_size * HeapWordSize)) {
180 // Given that expand() succeeded in expanding the heap, and we
181 // always expand the heap by an amount aligned to the heap
182 // region size, the free list should in theory not be empty.
183 // In either case allocate_free_region() will check for NULL.
184 res = _hrm.allocate_free_region(is_old);
185 } else {
186 _expand_heap_after_alloc_failure = false;
187 }
188 }
189 return res;
190 }
191
192 HeapWord*
193 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
194 uint num_regions,
195 size_t word_size) {
196 assert(first != G1_NO_HRM_INDEX, "pre-condition");
197 assert(is_humongous(word_size), "word_size should be humongous");
198 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
199
200 // Index of last region in the series.
201 uint last = first + num_regions - 1;
202
203 // We need to initialize the region(s) we just discovered. This is
204 // a bit tricky given that it can happen concurrently with
205 // refinement threads refining cards on these regions and
206 // potentially wanting to refine the BOT as they are scanning
207 // those cards (this can happen shortly after a cleanup; see CR
208 // 6991377). So we have to set up the region(s) carefully and in
209 // a specific order.
210
211 // The word size sum of all the regions we will allocate.
212 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
213 assert(word_size <= word_size_sum, "sanity");
214
215 // This will be the "starts humongous" region.
216 HeapRegion* first_hr = region_at(first);
217 // The header of the new object will be placed at the bottom of
218 // the first region.
219 HeapWord* new_obj = first_hr->bottom();
220 // This will be the new top of the new object.
221 HeapWord* obj_top = new_obj + word_size;
222
223 // First, we need to zero the header of the space that we will be
224 // allocating. When we update top further down, some refinement
225 // threads might try to scan the region. By zeroing the header we
226 // ensure that any thread that will try to scan the region will
227 // come across the zero klass word and bail out.
228 //
229 // NOTE: It would not have been correct to have used
230 // CollectedHeap::fill_with_object() and make the space look like
231 // an int array. The thread that is doing the allocation will
232 // later update the object header to a potentially different array
233 // type and, for a very short period of time, the klass and length
234 // fields will be inconsistent. This could cause a refinement
235 // thread to calculate the object size incorrectly.
236 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
237
238 // Next, pad out the unused tail of the last region with filler
239 // objects, for improved usage accounting.
240 // How many words we use for filler objects.
241 size_t word_fill_size = word_size_sum - word_size;
242
243 // How many words memory we "waste" which cannot hold a filler object.
244 size_t words_not_fillable = 0;
245
246 if (word_fill_size >= min_fill_size()) {
247 fill_with_objects(obj_top, word_fill_size);
248 } else if (word_fill_size > 0) {
249 // We have space to fill, but we cannot fit an object there.
250 words_not_fillable = word_fill_size;
251 word_fill_size = 0;
252 }
253
254 // We will set up the first region as "starts humongous". This
255 // will also update the BOT covering all the regions to reflect
256 // that there is a single object that starts at the bottom of the
257 // first region.
258 first_hr->set_starts_humongous(obj_top, word_fill_size);
259 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
260 // Then, if there are any, we will set up the "continues
261 // humongous" regions.
262 HeapRegion* hr = NULL;
263 for (uint i = first + 1; i <= last; ++i) {
264 hr = region_at(i);
265 hr->set_continues_humongous(first_hr);
266 _g1_policy->remset_tracker()->update_at_allocate(hr);
267 }
268
269 // Up to this point no concurrent thread would have been able to
270 // do any scanning on any region in this series. All the top
271 // fields still point to bottom, so the intersection between
272 // [bottom,top] and [card_start,card_end] will be empty. Before we
273 // update the top fields, we'll do a storestore to make sure that
274 // no thread sees the update to top before the zeroing of the
275 // object header and the BOT initialization.
276 OrderAccess::storestore();
277
278 // Now, we will update the top fields of the "continues humongous"
279 // regions except the last one.
280 for (uint i = first; i < last; ++i) {
281 hr = region_at(i);
282 hr->set_top(hr->end());
283 }
284
285 hr = region_at(last);
286 // If we cannot fit a filler object, we must set top to the end
287 // of the humongous object, otherwise we cannot iterate the heap
288 // and the BOT will not be complete.
289 hr->set_top(hr->end() - words_not_fillable);
290
291 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
292 "obj_top should be in last region");
293
294 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
295
296 assert(words_not_fillable == 0 ||
297 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
298 "Miscalculation in humongous allocation");
299
300 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
301
302 for (uint i = first; i <= last; ++i) {
303 hr = region_at(i);
304 _humongous_set.add(hr);
305 _hr_printer.alloc(hr);
306 }
307
308 return new_obj;
309 }
310
311 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
312 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
313 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
314 }
315
316 // If could fit into free regions w/o expansion, try.
317 // Otherwise, if can expand, do so.
318 // Otherwise, if using ex regions might help, try with ex given back.
319 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
320 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
321
322 _verifier->verify_region_sets_optional();
323
324 uint first = G1_NO_HRM_INDEX;
325 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
326
327 if (obj_regions == 1) {
328 // Only one region to allocate, try to use a fast path by directly allocating
329 // from the free lists. Do not try to expand here, we will potentially do that
330 // later.
331 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
332 if (hr != NULL) {
333 first = hr->hrm_index();
334 }
335 } else {
336 // Policy: Try only empty regions (i.e. already committed first). Maybe we
337 // are lucky enough to find some.
338 first = _hrm.find_contiguous_only_empty(obj_regions);
339 if (first != G1_NO_HRM_INDEX) {
340 _hrm.allocate_free_regions_starting_at(first, obj_regions);
341 }
342 }
343
344 if (first == G1_NO_HRM_INDEX) {
345 // Policy: We could not find enough regions for the humongous object in the
346 // free list. Look through the heap to find a mix of free and uncommitted regions.
347 // If so, try expansion.
348 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
349 if (first != G1_NO_HRM_INDEX) {
350 // We found something. Make sure these regions are committed, i.e. expand
351 // the heap. Alternatively we could do a defragmentation GC.
352 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
353 word_size * HeapWordSize);
354
355 _hrm.expand_at(first, obj_regions, workers());
356 g1_policy()->record_new_heap_size(num_regions());
357
358 #ifdef ASSERT
359 for (uint i = first; i < first + obj_regions; ++i) {
360 HeapRegion* hr = region_at(i);
361 assert(hr->is_free(), "sanity");
362 assert(hr->is_empty(), "sanity");
363 assert(is_on_master_free_list(hr), "sanity");
364 }
365 #endif
366 _hrm.allocate_free_regions_starting_at(first, obj_regions);
367 } else {
368 // Policy: Potentially trigger a defragmentation GC.
369 }
370 }
371
372 HeapWord* result = NULL;
373 if (first != G1_NO_HRM_INDEX) {
374 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
375 assert(result != NULL, "it should always return a valid result");
376
377 // A successful humongous object allocation changes the used space
378 // information of the old generation so we need to recalculate the
379 // sizes and update the jstat counters here.
380 g1mm()->update_sizes();
381 }
382
383 _verifier->verify_region_sets_optional();
384
385 return result;
386 }
387
388 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
389 size_t requested_size,
390 size_t* actual_size) {
391 assert_heap_not_locked_and_not_at_safepoint();
392 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
393
394 return attempt_allocation(min_size, requested_size, actual_size);
395 }
396
397 HeapWord*
398 G1CollectedHeap::mem_allocate(size_t word_size,
399 bool* gc_overhead_limit_was_exceeded) {
400 assert_heap_not_locked_and_not_at_safepoint();
401
402 if (is_humongous(word_size)) {
403 return attempt_allocation_humongous(word_size);
404 }
405 size_t dummy = 0;
406 return attempt_allocation(word_size, word_size, &dummy);
407 }
408
409 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
410 ResourceMark rm; // For retrieving the thread names in log messages.
411
412 // Make sure you read the note in attempt_allocation_humongous().
413
414 assert_heap_not_locked_and_not_at_safepoint();
415 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
416 "be called for humongous allocation requests");
417
418 // We should only get here after the first-level allocation attempt
419 // (attempt_allocation()) failed to allocate.
420
421 // We will loop until a) we manage to successfully perform the
422 // allocation or b) we successfully schedule a collection which
423 // fails to perform the allocation. b) is the only case when we'll
424 // return NULL.
425 HeapWord* result = NULL;
426 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
427 bool should_try_gc;
428 uint gc_count_before;
429
430 {
431 MutexLockerEx x(Heap_lock);
432 result = _allocator->attempt_allocation_locked(word_size);
433 if (result != NULL) {
434 return result;
435 }
436
437 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
438 // This is different to when only GCLocker::needs_gc() is set: try to avoid
439 // waiting because the GCLocker is active to not wait too long.
440 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
441 // No need for an ergo message here, can_expand_young_list() does this when
442 // it returns true.
443 result = _allocator->attempt_allocation_force(word_size);
444 if (result != NULL) {
445 return result;
446 }
447 }
448 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
449 // the GCLocker initiated GC has been performed and then retry. This includes
450 // the case when the GC Locker is not active but has not been performed.
451 should_try_gc = !GCLocker::needs_gc();
452 // Read the GC count while still holding the Heap_lock.
453 gc_count_before = total_collections();
454 }
455
456 if (should_try_gc) {
457 bool succeeded;
458 result = do_collection_pause(word_size, gc_count_before, &succeeded,
459 GCCause::_g1_inc_collection_pause);
460 if (result != NULL) {
461 assert(succeeded, "only way to get back a non-NULL result");
462 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
463 Thread::current()->name(), p2i(result));
464 return result;
465 }
466
467 if (succeeded) {
468 // We successfully scheduled a collection which failed to allocate. No
469 // point in trying to allocate further. We'll just return NULL.
470 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
471 SIZE_FORMAT " words", Thread::current()->name(), word_size);
472 return NULL;
473 }
474 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
475 Thread::current()->name(), word_size);
476 } else {
477 // Failed to schedule a collection.
478 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
479 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
480 SIZE_FORMAT " words", Thread::current()->name(), word_size);
481 return NULL;
482 }
483 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
484 // The GCLocker is either active or the GCLocker initiated
485 // GC has not yet been performed. Stall until it is and
486 // then retry the allocation.
487 GCLocker::stall_until_clear();
488 gclocker_retry_count += 1;
489 }
490
491 // We can reach here if we were unsuccessful in scheduling a
492 // collection (because another thread beat us to it) or if we were
493 // stalled due to the GC locker. In either can we should retry the
494 // allocation attempt in case another thread successfully
495 // performed a collection and reclaimed enough space. We do the
496 // first attempt (without holding the Heap_lock) here and the
497 // follow-on attempt will be at the start of the next loop
498 // iteration (after taking the Heap_lock).
499 size_t dummy = 0;
500 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
501 if (result != NULL) {
502 return result;
503 }
504
505 // Give a warning if we seem to be looping forever.
506 if ((QueuedAllocationWarningCount > 0) &&
507 (try_count % QueuedAllocationWarningCount == 0)) {
508 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
509 Thread::current()->name(), try_count, word_size);
510 }
511 }
512
513 ShouldNotReachHere();
514 return NULL;
515 }
516
517 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
518 assert_at_safepoint_on_vm_thread();
519 if (_archive_allocator == NULL) {
520 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
521 }
522 }
523
524 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
525 // Allocations in archive regions cannot be of a size that would be considered
526 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
527 // may be different at archive-restore time.
528 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
529 }
530
531 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
532 assert_at_safepoint_on_vm_thread();
533 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
534 if (is_archive_alloc_too_large(word_size)) {
535 return NULL;
536 }
537 return _archive_allocator->archive_mem_allocate(word_size);
538 }
539
540 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
541 size_t end_alignment_in_bytes) {
542 assert_at_safepoint_on_vm_thread();
543 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
544
545 // Call complete_archive to do the real work, filling in the MemRegion
546 // array with the archive regions.
547 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
548 delete _archive_allocator;
549 _archive_allocator = NULL;
550 }
551
552 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
553 assert(ranges != NULL, "MemRegion array NULL");
554 assert(count != 0, "No MemRegions provided");
555 MemRegion reserved = _hrm.reserved();
556 for (size_t i = 0; i < count; i++) {
557 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
558 return false;
559 }
560 }
561 return true;
562 }
563
564 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
565 size_t count,
566 bool open) {
567 assert(!is_init_completed(), "Expect to be called at JVM init time");
568 assert(ranges != NULL, "MemRegion array NULL");
569 assert(count != 0, "No MemRegions provided");
570 MutexLockerEx x(Heap_lock);
571
572 MemRegion reserved = _hrm.reserved();
573 HeapWord* prev_last_addr = NULL;
574 HeapRegion* prev_last_region = NULL;
575
576 // Temporarily disable pretouching of heap pages. This interface is used
577 // when mmap'ing archived heap data in, so pre-touching is wasted.
578 FlagSetting fs(AlwaysPreTouch, false);
579
580 // Enable archive object checking used by G1MarkSweep. We have to let it know
581 // about each archive range, so that objects in those ranges aren't marked.
582 G1ArchiveAllocator::enable_archive_object_check();
583
584 // For each specified MemRegion range, allocate the corresponding G1
585 // regions and mark them as archive regions. We expect the ranges
586 // in ascending starting address order, without overlap.
587 for (size_t i = 0; i < count; i++) {
588 MemRegion curr_range = ranges[i];
589 HeapWord* start_address = curr_range.start();
590 size_t word_size = curr_range.word_size();
591 HeapWord* last_address = curr_range.last();
592 size_t commits = 0;
593
594 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
595 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
596 p2i(start_address), p2i(last_address));
597 guarantee(start_address > prev_last_addr,
598 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
599 p2i(start_address), p2i(prev_last_addr));
600 prev_last_addr = last_address;
601
602 // Check for ranges that start in the same G1 region in which the previous
603 // range ended, and adjust the start address so we don't try to allocate
604 // the same region again. If the current range is entirely within that
605 // region, skip it, just adjusting the recorded top.
606 HeapRegion* start_region = _hrm.addr_to_region(start_address);
607 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
608 start_address = start_region->end();
609 if (start_address > last_address) {
610 increase_used(word_size * HeapWordSize);
611 start_region->set_top(last_address + 1);
612 continue;
613 }
614 start_region->set_top(start_address);
615 curr_range = MemRegion(start_address, last_address + 1);
616 start_region = _hrm.addr_to_region(start_address);
617 }
618
619 // Perform the actual region allocation, exiting if it fails.
620 // Then note how much new space we have allocated.
621 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
622 return false;
623 }
624 increase_used(word_size * HeapWordSize);
625 if (commits != 0) {
626 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
627 HeapRegion::GrainWords * HeapWordSize * commits);
628
629 }
630
631 // Mark each G1 region touched by the range as archive, add it to
632 // the old set, and set top.
633 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
634 HeapRegion* last_region = _hrm.addr_to_region(last_address);
635 prev_last_region = last_region;
636
637 while (curr_region != NULL) {
638 assert(curr_region->is_empty() && !curr_region->is_pinned(),
639 "Region already in use (index %u)", curr_region->hrm_index());
640 if (open) {
641 curr_region->set_open_archive();
642 } else {
643 curr_region->set_closed_archive();
644 }
645 _hr_printer.alloc(curr_region);
646 _old_set.add(curr_region);
647 HeapWord* top;
648 HeapRegion* next_region;
649 if (curr_region != last_region) {
650 top = curr_region->end();
651 next_region = _hrm.next_region_in_heap(curr_region);
652 } else {
653 top = last_address + 1;
654 next_region = NULL;
655 }
656 curr_region->set_top(top);
657 curr_region->set_first_dead(top);
658 curr_region->set_end_of_live(top);
659 curr_region = next_region;
660 }
661
662 // Notify mark-sweep of the archive
663 G1ArchiveAllocator::set_range_archive(curr_range, open);
664 }
665 return true;
666 }
667
668 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
669 assert(!is_init_completed(), "Expect to be called at JVM init time");
670 assert(ranges != NULL, "MemRegion array NULL");
671 assert(count != 0, "No MemRegions provided");
672 MemRegion reserved = _hrm.reserved();
673 HeapWord *prev_last_addr = NULL;
674 HeapRegion* prev_last_region = NULL;
675
676 // For each MemRegion, create filler objects, if needed, in the G1 regions
677 // that contain the address range. The address range actually within the
678 // MemRegion will not be modified. That is assumed to have been initialized
679 // elsewhere, probably via an mmap of archived heap data.
680 MutexLockerEx x(Heap_lock);
681 for (size_t i = 0; i < count; i++) {
682 HeapWord* start_address = ranges[i].start();
683 HeapWord* last_address = ranges[i].last();
684
685 assert(reserved.contains(start_address) && reserved.contains(last_address),
686 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
687 p2i(start_address), p2i(last_address));
688 assert(start_address > prev_last_addr,
689 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
690 p2i(start_address), p2i(prev_last_addr));
691
692 HeapRegion* start_region = _hrm.addr_to_region(start_address);
693 HeapRegion* last_region = _hrm.addr_to_region(last_address);
694 HeapWord* bottom_address = start_region->bottom();
695
696 // Check for a range beginning in the same region in which the
697 // previous one ended.
698 if (start_region == prev_last_region) {
699 bottom_address = prev_last_addr + 1;
700 }
701
702 // Verify that the regions were all marked as archive regions by
703 // alloc_archive_regions.
704 HeapRegion* curr_region = start_region;
705 while (curr_region != NULL) {
706 guarantee(curr_region->is_archive(),
707 "Expected archive region at index %u", curr_region->hrm_index());
708 if (curr_region != last_region) {
709 curr_region = _hrm.next_region_in_heap(curr_region);
710 } else {
711 curr_region = NULL;
712 }
713 }
714
715 prev_last_addr = last_address;
716 prev_last_region = last_region;
717
718 // Fill the memory below the allocated range with dummy object(s),
719 // if the region bottom does not match the range start, or if the previous
720 // range ended within the same G1 region, and there is a gap.
721 if (start_address != bottom_address) {
722 size_t fill_size = pointer_delta(start_address, bottom_address);
723 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
724 increase_used(fill_size * HeapWordSize);
725 }
726 }
727 }
728
729 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
730 size_t desired_word_size,
731 size_t* actual_word_size) {
732 assert_heap_not_locked_and_not_at_safepoint();
733 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
734 "be called for humongous allocation requests");
735
736 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
737
738 if (result == NULL) {
739 *actual_word_size = desired_word_size;
740 result = attempt_allocation_slow(desired_word_size);
741 }
742
743 assert_heap_not_locked();
744 if (result != NULL) {
745 assert(*actual_word_size != 0, "Actual size must have been set here");
746 dirty_young_block(result, *actual_word_size);
747 } else {
748 *actual_word_size = 0;
749 }
750
751 return result;
752 }
753
754 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
755 assert(!is_init_completed(), "Expect to be called at JVM init time");
756 assert(ranges != NULL, "MemRegion array NULL");
757 assert(count != 0, "No MemRegions provided");
758 MemRegion reserved = _hrm.reserved();
759 HeapWord* prev_last_addr = NULL;
760 HeapRegion* prev_last_region = NULL;
761 size_t size_used = 0;
762 size_t uncommitted_regions = 0;
763
764 // For each Memregion, free the G1 regions that constitute it, and
765 // notify mark-sweep that the range is no longer to be considered 'archive.'
766 MutexLockerEx x(Heap_lock);
767 for (size_t i = 0; i < count; i++) {
768 HeapWord* start_address = ranges[i].start();
769 HeapWord* last_address = ranges[i].last();
770
771 assert(reserved.contains(start_address) && reserved.contains(last_address),
772 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
773 p2i(start_address), p2i(last_address));
774 assert(start_address > prev_last_addr,
775 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
776 p2i(start_address), p2i(prev_last_addr));
777 size_used += ranges[i].byte_size();
778 prev_last_addr = last_address;
779
780 HeapRegion* start_region = _hrm.addr_to_region(start_address);
781 HeapRegion* last_region = _hrm.addr_to_region(last_address);
782
783 // Check for ranges that start in the same G1 region in which the previous
784 // range ended, and adjust the start address so we don't try to free
785 // the same region again. If the current range is entirely within that
786 // region, skip it.
787 if (start_region == prev_last_region) {
788 start_address = start_region->end();
789 if (start_address > last_address) {
790 continue;
791 }
792 start_region = _hrm.addr_to_region(start_address);
793 }
794 prev_last_region = last_region;
795
796 // After verifying that each region was marked as an archive region by
797 // alloc_archive_regions, set it free and empty and uncommit it.
798 HeapRegion* curr_region = start_region;
799 while (curr_region != NULL) {
800 guarantee(curr_region->is_archive(),
801 "Expected archive region at index %u", curr_region->hrm_index());
802 uint curr_index = curr_region->hrm_index();
803 _old_set.remove(curr_region);
804 curr_region->set_free();
805 curr_region->set_top(curr_region->bottom());
806 if (curr_region != last_region) {
807 curr_region = _hrm.next_region_in_heap(curr_region);
808 } else {
809 curr_region = NULL;
810 }
811 _hrm.shrink_at(curr_index, 1);
812 uncommitted_regions++;
813 }
814
815 // Notify mark-sweep that this is no longer an archive range.
816 G1ArchiveAllocator::set_range_archive(ranges[i], false);
817 }
818
819 if (uncommitted_regions != 0) {
820 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
821 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
822 }
823 decrease_used(size_used);
824 }
825
826 oop G1CollectedHeap::materialize_archived_object(oop obj) {
827 assert(obj != NULL, "archived obj is NULL");
828 assert(MetaspaceShared::is_archive_object(obj), "must be archived object");
829
830 // Loading an archived object makes it strongly reachable. If it is
831 // loaded during concurrent marking, it must be enqueued to the SATB
832 // queue, shading the previously white object gray.
833 G1BarrierSet::enqueue(obj);
834
835 return obj;
836 }
837
838 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
839 ResourceMark rm; // For retrieving the thread names in log messages.
840
841 // The structure of this method has a lot of similarities to
842 // attempt_allocation_slow(). The reason these two were not merged
843 // into a single one is that such a method would require several "if
844 // allocation is not humongous do this, otherwise do that"
845 // conditional paths which would obscure its flow. In fact, an early
846 // version of this code did use a unified method which was harder to
847 // follow and, as a result, it had subtle bugs that were hard to
848 // track down. So keeping these two methods separate allows each to
849 // be more readable. It will be good to keep these two in sync as
850 // much as possible.
851
852 assert_heap_not_locked_and_not_at_safepoint();
853 assert(is_humongous(word_size), "attempt_allocation_humongous() "
854 "should only be called for humongous allocations");
855
856 // Humongous objects can exhaust the heap quickly, so we should check if we
857 // need to start a marking cycle at each humongous object allocation. We do
858 // the check before we do the actual allocation. The reason for doing it
859 // before the allocation is that we avoid having to keep track of the newly
860 // allocated memory while we do a GC.
861 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
862 word_size)) {
863 collect(GCCause::_g1_humongous_allocation);
864 }
865
866 // We will loop until a) we manage to successfully perform the
867 // allocation or b) we successfully schedule a collection which
868 // fails to perform the allocation. b) is the only case when we'll
869 // return NULL.
870 HeapWord* result = NULL;
871 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
872 bool should_try_gc;
873 uint gc_count_before;
874
875
876 {
877 MutexLockerEx x(Heap_lock);
878
879 // Given that humongous objects are not allocated in young
880 // regions, we'll first try to do the allocation without doing a
881 // collection hoping that there's enough space in the heap.
882 result = humongous_obj_allocate(word_size);
883 if (result != NULL) {
884 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
885 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
886 return result;
887 }
888
889 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
890 // the GCLocker initiated GC has been performed and then retry. This includes
891 // the case when the GC Locker is not active but has not been performed.
892 should_try_gc = !GCLocker::needs_gc();
893 // Read the GC count while still holding the Heap_lock.
894 gc_count_before = total_collections();
895 }
896
897 if (should_try_gc) {
898 bool succeeded;
899 result = do_collection_pause(word_size, gc_count_before, &succeeded,
900 GCCause::_g1_humongous_allocation);
901 if (result != NULL) {
902 assert(succeeded, "only way to get back a non-NULL result");
903 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
904 Thread::current()->name(), p2i(result));
905 return result;
906 }
907
908 if (succeeded) {
909 // We successfully scheduled a collection which failed to allocate. No
910 // point in trying to allocate further. We'll just return NULL.
911 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
912 SIZE_FORMAT " words", Thread::current()->name(), word_size);
913 return NULL;
914 }
915 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
916 Thread::current()->name(), word_size);
917 } else {
918 // Failed to schedule a collection.
919 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
920 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
921 SIZE_FORMAT " words", Thread::current()->name(), word_size);
922 return NULL;
923 }
924 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
925 // The GCLocker is either active or the GCLocker initiated
926 // GC has not yet been performed. Stall until it is and
927 // then retry the allocation.
928 GCLocker::stall_until_clear();
929 gclocker_retry_count += 1;
930 }
931
932
933 // We can reach here if we were unsuccessful in scheduling a
934 // collection (because another thread beat us to it) or if we were
935 // stalled due to the GC locker. In either can we should retry the
936 // allocation attempt in case another thread successfully
937 // performed a collection and reclaimed enough space.
938 // Humongous object allocation always needs a lock, so we wait for the retry
939 // in the next iteration of the loop, unlike for the regular iteration case.
940 // Give a warning if we seem to be looping forever.
941
942 if ((QueuedAllocationWarningCount > 0) &&
943 (try_count % QueuedAllocationWarningCount == 0)) {
944 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
945 Thread::current()->name(), try_count, word_size);
946 }
947 }
948
949 ShouldNotReachHere();
950 return NULL;
951 }
952
953 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
954 bool expect_null_mutator_alloc_region) {
955 assert_at_safepoint_on_vm_thread();
956 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
957 "the current alloc region was unexpectedly found to be non-NULL");
958
959 if (!is_humongous(word_size)) {
960 return _allocator->attempt_allocation_locked(word_size);
961 } else {
962 HeapWord* result = humongous_obj_allocate(word_size);
963 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
964 collector_state()->set_initiate_conc_mark_if_possible(true);
965 }
966 return result;
967 }
968
969 ShouldNotReachHere();
970 }
971
972 class PostCompactionPrinterClosure: public HeapRegionClosure {
973 private:
974 G1HRPrinter* _hr_printer;
975 public:
976 bool do_heap_region(HeapRegion* hr) {
977 assert(!hr->is_young(), "not expecting to find young regions");
978 _hr_printer->post_compaction(hr);
979 return false;
980 }
981
982 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
983 : _hr_printer(hr_printer) { }
984 };
985
986 void G1CollectedHeap::print_hrm_post_compaction() {
987 if (_hr_printer.is_active()) {
988 PostCompactionPrinterClosure cl(hr_printer());
989 heap_region_iterate(&cl);
990 }
991 }
992
993 void G1CollectedHeap::abort_concurrent_cycle() {
994 // If we start the compaction before the CM threads finish
995 // scanning the root regions we might trip them over as we'll
996 // be moving objects / updating references. So let's wait until
997 // they are done. By telling them to abort, they should complete
998 // early.
999 _cm->root_regions()->abort();
1000 _cm->root_regions()->wait_until_scan_finished();
1001
1002 // Disable discovery and empty the discovered lists
1003 // for the CM ref processor.
1004 _ref_processor_cm->disable_discovery();
1005 _ref_processor_cm->abandon_partial_discovery();
1006 _ref_processor_cm->verify_no_references_recorded();
1007
1008 // Abandon current iterations of concurrent marking and concurrent
1009 // refinement, if any are in progress.
1010 concurrent_mark()->concurrent_cycle_abort();
1011 }
1012
1013 void G1CollectedHeap::prepare_heap_for_full_collection() {
1014 // Make sure we'll choose a new allocation region afterwards.
1015 _allocator->release_mutator_alloc_region();
1016 _allocator->abandon_gc_alloc_regions();
1017 g1_rem_set()->cleanupHRRS();
1018
1019 // We may have added regions to the current incremental collection
1020 // set between the last GC or pause and now. We need to clear the
1021 // incremental collection set and then start rebuilding it afresh
1022 // after this full GC.
1023 abandon_collection_set(collection_set());
1024
1025 tear_down_region_sets(false /* free_list_only */);
1026 }
1027
1028 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1029 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1030 assert(used() == recalculate_used(), "Should be equal");
1031 _verifier->verify_region_sets_optional();
1032 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1033 _verifier->check_bitmaps("Full GC Start");
1034 }
1035
1036 void G1CollectedHeap::prepare_heap_for_mutators() {
1037 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1038 ClassLoaderDataGraph::purge();
1039 MetaspaceUtils::verify_metrics();
1040
1041 // Prepare heap for normal collections.
1042 assert(num_free_regions() == 0, "we should not have added any free regions");
1043 rebuild_region_sets(false /* free_list_only */);
1044 abort_refinement();
1045 resize_if_necessary_after_full_collection();
1046
1047 // Rebuild the strong code root lists for each region
1048 rebuild_strong_code_roots();
1049
1050 // Start a new incremental collection set for the next pause
1051 start_new_collection_set();
1052
1053 _allocator->init_mutator_alloc_region();
1054
1055 // Post collection state updates.
1056 MetaspaceGC::compute_new_size();
1057 }
1058
1059 void G1CollectedHeap::abort_refinement() {
1060 if (_hot_card_cache->use_cache()) {
1061 _hot_card_cache->reset_hot_cache();
1062 }
1063
1064 // Discard all remembered set updates.
1065 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1066 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1067 }
1068
1069 void G1CollectedHeap::verify_after_full_collection() {
1070 _hrm.verify_optional();
1071 _verifier->verify_region_sets_optional();
1072 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1073 // Clear the previous marking bitmap, if needed for bitmap verification.
1074 // Note we cannot do this when we clear the next marking bitmap in
1075 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1076 // objects marked during a full GC against the previous bitmap.
1077 // But we need to clear it before calling check_bitmaps below since
1078 // the full GC has compacted objects and updated TAMS but not updated
1079 // the prev bitmap.
1080 if (G1VerifyBitmaps) {
1081 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1082 _cm->clear_prev_bitmap(workers());
1083 }
1084 _verifier->check_bitmaps("Full GC End");
1085
1086 // At this point there should be no regions in the
1087 // entire heap tagged as young.
1088 assert(check_young_list_empty(), "young list should be empty at this point");
1089
1090 // Note: since we've just done a full GC, concurrent
1091 // marking is no longer active. Therefore we need not
1092 // re-enable reference discovery for the CM ref processor.
1093 // That will be done at the start of the next marking cycle.
1094 // We also know that the STW processor should no longer
1095 // discover any new references.
1096 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1097 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1098 _ref_processor_stw->verify_no_references_recorded();
1099 _ref_processor_cm->verify_no_references_recorded();
1100 }
1101
1102 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1103 // Post collection logging.
1104 // We should do this after we potentially resize the heap so
1105 // that all the COMMIT / UNCOMMIT events are generated before
1106 // the compaction events.
1107 print_hrm_post_compaction();
1108 heap_transition->print();
1109 print_heap_after_gc();
1110 print_heap_regions();
1111 #ifdef TRACESPINNING
1112 ParallelTaskTerminator::print_termination_counts();
1113 #endif
1114 }
1115
1116 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1117 bool clear_all_soft_refs) {
1118 assert_at_safepoint_on_vm_thread();
1119
1120 if (GCLocker::check_active_before_gc()) {
1121 // Full GC was not completed.
1122 return false;
1123 }
1124
1125 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1126 soft_ref_policy()->should_clear_all_soft_refs();
1127
1128 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1129 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1130
1131 collector.prepare_collection();
1132 collector.collect();
1133 collector.complete_collection();
1134
1135 // Full collection was successfully completed.
1136 return true;
1137 }
1138
1139 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1140 // Currently, there is no facility in the do_full_collection(bool) API to notify
1141 // the caller that the collection did not succeed (e.g., because it was locked
1142 // out by the GC locker). So, right now, we'll ignore the return value.
1143 bool dummy = do_full_collection(true, /* explicit_gc */
1144 clear_all_soft_refs);
1145 }
1146
1147 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1148 // Capacity, free and used after the GC counted as full regions to
1149 // include the waste in the following calculations.
1150 const size_t capacity_after_gc = capacity();
1151 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1152
1153 // This is enforced in arguments.cpp.
1154 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1155 "otherwise the code below doesn't make sense");
1156
1157 // We don't have floating point command-line arguments
1158 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1159 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1160 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1161 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1162
1163 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1164 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1165
1166 // We have to be careful here as these two calculations can overflow
1167 // 32-bit size_t's.
1168 double used_after_gc_d = (double) used_after_gc;
1169 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1170 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1171
1172 // Let's make sure that they are both under the max heap size, which
1173 // by default will make them fit into a size_t.
1174 double desired_capacity_upper_bound = (double) max_heap_size;
1175 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1176 desired_capacity_upper_bound);
1177 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1178 desired_capacity_upper_bound);
1179
1180 // We can now safely turn them into size_t's.
1181 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1182 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1183
1184 // This assert only makes sense here, before we adjust them
1185 // with respect to the min and max heap size.
1186 assert(minimum_desired_capacity <= maximum_desired_capacity,
1187 "minimum_desired_capacity = " SIZE_FORMAT ", "
1188 "maximum_desired_capacity = " SIZE_FORMAT,
1189 minimum_desired_capacity, maximum_desired_capacity);
1190
1191 // Should not be greater than the heap max size. No need to adjust
1192 // it with respect to the heap min size as it's a lower bound (i.e.,
1193 // we'll try to make the capacity larger than it, not smaller).
1194 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1195 // Should not be less than the heap min size. No need to adjust it
1196 // with respect to the heap max size as it's an upper bound (i.e.,
1197 // we'll try to make the capacity smaller than it, not greater).
1198 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1199
1200 if (capacity_after_gc < minimum_desired_capacity) {
1201 // Don't expand unless it's significant
1202 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1203
1204 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1205 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1206 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1207 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1208
1209 expand(expand_bytes, _workers);
1210
1211 // No expansion, now see if we want to shrink
1212 } else if (capacity_after_gc > maximum_desired_capacity) {
1213 // Capacity too large, compute shrinking size
1214 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1215
1216 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1217 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1218 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1219 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1220
1221 shrink(shrink_bytes);
1222 }
1223 }
1224
1225 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1226 bool do_gc,
1227 bool clear_all_soft_refs,
1228 bool expect_null_mutator_alloc_region,
1229 bool* gc_succeeded) {
1230 *gc_succeeded = true;
1231 // Let's attempt the allocation first.
1232 HeapWord* result =
1233 attempt_allocation_at_safepoint(word_size,
1234 expect_null_mutator_alloc_region);
1235 if (result != NULL) {
1236 return result;
1237 }
1238
1239 // In a G1 heap, we're supposed to keep allocation from failing by
1240 // incremental pauses. Therefore, at least for now, we'll favor
1241 // expansion over collection. (This might change in the future if we can
1242 // do something smarter than full collection to satisfy a failed alloc.)
1243 result = expand_and_allocate(word_size);
1244 if (result != NULL) {
1245 return result;
1246 }
1247
1248 if (do_gc) {
1249 // Expansion didn't work, we'll try to do a Full GC.
1250 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1251 clear_all_soft_refs);
1252 }
1253
1254 return NULL;
1255 }
1256
1257 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1258 bool* succeeded) {
1259 assert_at_safepoint_on_vm_thread();
1260
1261 // Attempts to allocate followed by Full GC.
1262 HeapWord* result =
1263 satisfy_failed_allocation_helper(word_size,
1264 true, /* do_gc */
1265 false, /* clear_all_soft_refs */
1266 false, /* expect_null_mutator_alloc_region */
1267 succeeded);
1268
1269 if (result != NULL || !*succeeded) {
1270 return result;
1271 }
1272
1273 // Attempts to allocate followed by Full GC that will collect all soft references.
1274 result = satisfy_failed_allocation_helper(word_size,
1275 true, /* do_gc */
1276 true, /* clear_all_soft_refs */
1277 true, /* expect_null_mutator_alloc_region */
1278 succeeded);
1279
1280 if (result != NULL || !*succeeded) {
1281 return result;
1282 }
1283
1284 // Attempts to allocate, no GC
1285 result = satisfy_failed_allocation_helper(word_size,
1286 false, /* do_gc */
1287 false, /* clear_all_soft_refs */
1288 true, /* expect_null_mutator_alloc_region */
1289 succeeded);
1290
1291 if (result != NULL) {
1292 return result;
1293 }
1294
1295 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1296 "Flag should have been handled and cleared prior to this point");
1297
1298 // What else? We might try synchronous finalization later. If the total
1299 // space available is large enough for the allocation, then a more
1300 // complete compaction phase than we've tried so far might be
1301 // appropriate.
1302 return NULL;
1303 }
1304
1305 // Attempting to expand the heap sufficiently
1306 // to support an allocation of the given "word_size". If
1307 // successful, perform the allocation and return the address of the
1308 // allocated block, or else "NULL".
1309
1310 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1311 assert_at_safepoint_on_vm_thread();
1312
1313 _verifier->verify_region_sets_optional();
1314
1315 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1316 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1317 word_size * HeapWordSize);
1318
1319
1320 if (expand(expand_bytes, _workers)) {
1321 _hrm.verify_optional();
1322 _verifier->verify_region_sets_optional();
1323 return attempt_allocation_at_safepoint(word_size,
1324 false /* expect_null_mutator_alloc_region */);
1325 }
1326 return NULL;
1327 }
1328
1329 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1330 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1331 aligned_expand_bytes = align_up(aligned_expand_bytes,
1332 HeapRegion::GrainBytes);
1333
1334 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1335 expand_bytes, aligned_expand_bytes);
1336
1337 if (is_maximal_no_gc()) {
1338 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1339 return false;
1340 }
1341
1342 double expand_heap_start_time_sec = os::elapsedTime();
1343 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1344 assert(regions_to_expand > 0, "Must expand by at least one region");
1345
1346 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1347 if (expand_time_ms != NULL) {
1348 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1349 }
1350
1351 if (expanded_by > 0) {
1352 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1353 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1354 g1_policy()->record_new_heap_size(num_regions());
1355 } else {
1356 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1357
1358 // The expansion of the virtual storage space was unsuccessful.
1359 // Let's see if it was because we ran out of swap.
1360 if (G1ExitOnExpansionFailure &&
1361 _hrm.available() >= regions_to_expand) {
1362 // We had head room...
1363 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1364 }
1365 }
1366 return regions_to_expand > 0;
1367 }
1368
1369 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1370 size_t aligned_shrink_bytes =
1371 ReservedSpace::page_align_size_down(shrink_bytes);
1372 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1373 HeapRegion::GrainBytes);
1374 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1375
1376 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1377 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1378
1379
1380 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",
1381 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1382 if (num_regions_removed > 0) {
1383 g1_policy()->record_new_heap_size(num_regions());
1384 } else {
1385 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1386 }
1387 }
1388
1389 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1390 _verifier->verify_region_sets_optional();
1391
1392 // We should only reach here at the end of a Full GC which means we
1393 // should not not be holding to any GC alloc regions. The method
1394 // below will make sure of that and do any remaining clean up.
1395 _allocator->abandon_gc_alloc_regions();
1396
1397 // Instead of tearing down / rebuilding the free lists here, we
1398 // could instead use the remove_all_pending() method on free_list to
1399 // remove only the ones that we need to remove.
1400 tear_down_region_sets(true /* free_list_only */);
1401 shrink_helper(shrink_bytes);
1402 rebuild_region_sets(true /* free_list_only */);
1403
1404 _hrm.verify_optional();
1405 _verifier->verify_region_sets_optional();
1406 }
1407
1408 // Public methods.
1409
1410 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1411 CollectedHeap(),
1412 _young_gen_sampling_thread(NULL),
1413 _collector_policy(collector_policy),
1414 _soft_ref_policy(),
1415 _card_table(NULL),
1416 _memory_manager("G1 Young Generation", "end of minor GC"),
1417 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1418 _eden_pool(NULL),
1419 _survivor_pool(NULL),
1420 _old_pool(NULL),
1421 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1422 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1423 _g1_policy(new G1Policy(_gc_timer_stw)),
1424 _collection_set(this, _g1_policy),
1425 _dirty_card_queue_set(false),
1426 _ref_processor_stw(NULL),
1427 _is_alive_closure_stw(this),
1428 _is_subject_to_discovery_stw(this),
1429 _ref_processor_cm(NULL),
1430 _is_alive_closure_cm(this),
1431 _is_subject_to_discovery_cm(this),
1432 _bot(NULL),
1433 _hot_card_cache(NULL),
1434 _g1_rem_set(NULL),
1435 _cr(NULL),
1436 _g1mm(NULL),
1437 _preserved_marks_set(true /* in_c_heap */),
1438 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1439 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1440 _humongous_reclaim_candidates(),
1441 _has_humongous_reclaim_candidates(false),
1442 _archive_allocator(NULL),
1443 _summary_bytes_used(0),
1444 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1445 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1446 _expand_heap_after_alloc_failure(true),
1447 _old_marking_cycles_started(0),
1448 _old_marking_cycles_completed(0),
1449 _in_cset_fast_test() {
1450
1451 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1452 /* are_GC_task_threads */true,
1453 /* are_ConcurrentGC_threads */false);
1454 _workers->initialize_workers();
1455 _verifier = new G1HeapVerifier(this);
1456
1457 _allocator = new G1Allocator(this);
1458
1459 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1460
1461 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1462
1463 // Override the default _filler_array_max_size so that no humongous filler
1464 // objects are created.
1465 _filler_array_max_size = _humongous_object_threshold_in_words;
1466
1467 uint n_queues = ParallelGCThreads;
1468 _task_queues = new RefToScanQueueSet(n_queues);
1469
1470 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1471
1472 for (uint i = 0; i < n_queues; i++) {
1473 RefToScanQueue* q = new RefToScanQueue();
1474 q->initialize();
1475 _task_queues->register_queue(i, q);
1476 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1477 }
1478
1479 // Initialize the G1EvacuationFailureALot counters and flags.
1480 NOT_PRODUCT(reset_evacuation_should_fail();)
1481
1482 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1483 }
1484
1485 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1486 size_t size,
1487 size_t translation_factor) {
1488 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1489 // Allocate a new reserved space, preferring to use large pages.
1490 ReservedSpace rs(size, preferred_page_size);
1491 G1RegionToSpaceMapper* result =
1492 G1RegionToSpaceMapper::create_mapper(rs,
1493 size,
1494 rs.alignment(),
1495 HeapRegion::GrainBytes,
1496 translation_factor,
1497 mtGC);
1498
1499 os::trace_page_sizes_for_requested_size(description,
1500 size,
1501 preferred_page_size,
1502 rs.alignment(),
1503 rs.base(),
1504 rs.size());
1505
1506 return result;
1507 }
1508
1509 jint G1CollectedHeap::initialize_concurrent_refinement() {
1510 jint ecode = JNI_OK;
1511 _cr = G1ConcurrentRefine::create(&ecode);
1512 return ecode;
1513 }
1514
1515 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1516 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1517 if (_young_gen_sampling_thread->osthread() == NULL) {
1518 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1519 return JNI_ENOMEM;
1520 }
1521 return JNI_OK;
1522 }
1523
1524 jint G1CollectedHeap::initialize() {
1525 os::enable_vtime();
1526
1527 // Necessary to satisfy locking discipline assertions.
1528
1529 MutexLocker x(Heap_lock);
1530
1531 // While there are no constraints in the GC code that HeapWordSize
1532 // be any particular value, there are multiple other areas in the
1533 // system which believe this to be true (e.g. oop->object_size in some
1534 // cases incorrectly returns the size in wordSize units rather than
1535 // HeapWordSize).
1536 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1537
1538 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1539 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1540 size_t heap_alignment = collector_policy()->heap_alignment();
1541
1542 // Ensure that the sizes are properly aligned.
1543 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1544 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1545 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1546
1547 // Reserve the maximum.
1548
1549 // When compressed oops are enabled, the preferred heap base
1550 // is calculated by subtracting the requested size from the
1551 // 32Gb boundary and using the result as the base address for
1552 // heap reservation. If the requested size is not aligned to
1553 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1554 // into the ReservedHeapSpace constructor) then the actual
1555 // base of the reserved heap may end up differing from the
1556 // address that was requested (i.e. the preferred heap base).
1557 // If this happens then we could end up using a non-optimal
1558 // compressed oops mode.
1559
1560 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1561 heap_alignment);
1562
1563 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1564
1565 // Create the barrier set for the entire reserved region.
1566 G1CardTable* ct = new G1CardTable(reserved_region());
1567 ct->initialize();
1568 G1BarrierSet* bs = new G1BarrierSet(ct);
1569 bs->initialize();
1570 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1571 BarrierSet::set_barrier_set(bs);
1572 _card_table = ct;
1573
1574 // Create the hot card cache.
1575 _hot_card_cache = new G1HotCardCache(this);
1576
1577 // Carve out the G1 part of the heap.
1578 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1579 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1580 G1RegionToSpaceMapper* heap_storage =
1581 G1RegionToSpaceMapper::create_mapper(g1_rs,
1582 g1_rs.size(),
1583 page_size,
1584 HeapRegion::GrainBytes,
1585 1,
1586 mtJavaHeap);
1587 os::trace_page_sizes("Heap",
1588 collector_policy()->min_heap_byte_size(),
1589 max_byte_size,
1590 page_size,
1591 heap_rs.base(),
1592 heap_rs.size());
1593 heap_storage->set_mapping_changed_listener(&_listener);
1594
1595 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1596 G1RegionToSpaceMapper* bot_storage =
1597 create_aux_memory_mapper("Block Offset Table",
1598 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1599 G1BlockOffsetTable::heap_map_factor());
1600
1601 G1RegionToSpaceMapper* cardtable_storage =
1602 create_aux_memory_mapper("Card Table",
1603 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1604 G1CardTable::heap_map_factor());
1605
1606 G1RegionToSpaceMapper* card_counts_storage =
1607 create_aux_memory_mapper("Card Counts Table",
1608 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1609 G1CardCounts::heap_map_factor());
1610
1611 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1612 G1RegionToSpaceMapper* prev_bitmap_storage =
1613 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1614 G1RegionToSpaceMapper* next_bitmap_storage =
1615 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1616
1617 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1618 _card_table->initialize(cardtable_storage);
1619 // Do later initialization work for concurrent refinement.
1620 _hot_card_cache->initialize(card_counts_storage);
1621
1622 // 6843694 - ensure that the maximum region index can fit
1623 // in the remembered set structures.
1624 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1625 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1626
1627 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1628 // start within the first card.
1629 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1630 // Also create a G1 rem set.
1631 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1632 _g1_rem_set->initialize(max_capacity(), max_regions());
1633
1634 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1635 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1636 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1637 "too many cards per region");
1638
1639 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1640
1641 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1642
1643 {
1644 HeapWord* start = _hrm.reserved().start();
1645 HeapWord* end = _hrm.reserved().end();
1646 size_t granularity = HeapRegion::GrainBytes;
1647
1648 _in_cset_fast_test.initialize(start, end, granularity);
1649 _humongous_reclaim_candidates.initialize(start, end, granularity);
1650 }
1651
1652 // Create the G1ConcurrentMark data structure and thread.
1653 // (Must do this late, so that "max_regions" is defined.)
1654 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1655 if (_cm == NULL || !_cm->completed_initialization()) {
1656 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1657 return JNI_ENOMEM;
1658 }
1659 _cm_thread = _cm->cm_thread();
1660
1661 // Now expand into the initial heap size.
1662 if (!expand(init_byte_size, _workers)) {
1663 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1664 return JNI_ENOMEM;
1665 }
1666
1667 // Perform any initialization actions delegated to the policy.
1668 g1_policy()->init(this, &_collection_set);
1669
1670 G1BarrierSet::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1671 SATB_Q_FL_lock,
1672 G1SATBProcessCompletedThreshold,
1673 Shared_SATB_Q_lock);
1674
1675 jint ecode = initialize_concurrent_refinement();
1676 if (ecode != JNI_OK) {
1677 return ecode;
1678 }
1679
1680 ecode = initialize_young_gen_sampling_thread();
1681 if (ecode != JNI_OK) {
1682 return ecode;
1683 }
1684
1685 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1686 DirtyCardQ_FL_lock,
1687 (int)concurrent_refine()->yellow_zone(),
1688 (int)concurrent_refine()->red_zone(),
1689 Shared_DirtyCardQ_lock,
1690 NULL, // fl_owner
1691 true); // init_free_ids
1692
1693 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1694 DirtyCardQ_FL_lock,
1695 -1, // never trigger processing
1696 -1, // no limit on length
1697 Shared_DirtyCardQ_lock,
1698 &G1BarrierSet::dirty_card_queue_set());
1699
1700 // Here we allocate the dummy HeapRegion that is required by the
1701 // G1AllocRegion class.
1702 HeapRegion* dummy_region = _hrm.get_dummy_region();
1703
1704 // We'll re-use the same region whether the alloc region will
1705 // require BOT updates or not and, if it doesn't, then a non-young
1706 // region will complain that it cannot support allocations without
1707 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1708 dummy_region->set_eden();
1709 // Make sure it's full.
1710 dummy_region->set_top(dummy_region->end());
1711 G1AllocRegion::setup(this, dummy_region);
1712
1713 _allocator->init_mutator_alloc_region();
1714
1715 // Do create of the monitoring and management support so that
1716 // values in the heap have been properly initialized.
1717 _g1mm = new G1MonitoringSupport(this);
1718
1719 G1StringDedup::initialize();
1720
1721 _preserved_marks_set.init(ParallelGCThreads);
1722
1723 _collection_set.initialize(max_regions());
1724
1725 return JNI_OK;
1726 }
1727
1728 void G1CollectedHeap::initialize_serviceability() {
1729 _eden_pool = new G1EdenPool(this);
1730 _survivor_pool = new G1SurvivorPool(this);
1731 _old_pool = new G1OldGenPool(this);
1732
1733 _full_gc_memory_manager.add_pool(_eden_pool);
1734 _full_gc_memory_manager.add_pool(_survivor_pool);
1735 _full_gc_memory_manager.add_pool(_old_pool);
1736
1737 _memory_manager.add_pool(_eden_pool);
1738 _memory_manager.add_pool(_survivor_pool);
1739 _memory_manager.add_pool(_old_pool, false /* always_affected_by_gc */);
1740 }
1741
1742 void G1CollectedHeap::stop() {
1743 // Stop all concurrent threads. We do this to make sure these threads
1744 // do not continue to execute and access resources (e.g. logging)
1745 // that are destroyed during shutdown.
1746 _cr->stop();
1747 _young_gen_sampling_thread->stop();
1748 _cm_thread->stop();
1749 if (G1StringDedup::is_enabled()) {
1750 G1StringDedup::stop();
1751 }
1752 }
1753
1754 void G1CollectedHeap::safepoint_synchronize_begin() {
1755 SuspendibleThreadSet::synchronize();
1756 }
1757
1758 void G1CollectedHeap::safepoint_synchronize_end() {
1759 SuspendibleThreadSet::desynchronize();
1760 }
1761
1762 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1763 return HeapRegion::max_region_size();
1764 }
1765
1766 void G1CollectedHeap::post_initialize() {
1767 CollectedHeap::post_initialize();
1768 ref_processing_init();
1769 }
1770
1771 void G1CollectedHeap::ref_processing_init() {
1772 // Reference processing in G1 currently works as follows:
1773 //
1774 // * There are two reference processor instances. One is
1775 // used to record and process discovered references
1776 // during concurrent marking; the other is used to
1777 // record and process references during STW pauses
1778 // (both full and incremental).
1779 // * Both ref processors need to 'span' the entire heap as
1780 // the regions in the collection set may be dotted around.
1781 //
1782 // * For the concurrent marking ref processor:
1783 // * Reference discovery is enabled at initial marking.
1784 // * Reference discovery is disabled and the discovered
1785 // references processed etc during remarking.
1786 // * Reference discovery is MT (see below).
1787 // * Reference discovery requires a barrier (see below).
1788 // * Reference processing may or may not be MT
1789 // (depending on the value of ParallelRefProcEnabled
1790 // and ParallelGCThreads).
1791 // * A full GC disables reference discovery by the CM
1792 // ref processor and abandons any entries on it's
1793 // discovered lists.
1794 //
1795 // * For the STW processor:
1796 // * Non MT discovery is enabled at the start of a full GC.
1797 // * Processing and enqueueing during a full GC is non-MT.
1798 // * During a full GC, references are processed after marking.
1799 //
1800 // * Discovery (may or may not be MT) is enabled at the start
1801 // of an incremental evacuation pause.
1802 // * References are processed near the end of a STW evacuation pause.
1803 // * For both types of GC:
1804 // * Discovery is atomic - i.e. not concurrent.
1805 // * Reference discovery will not need a barrier.
1806
1807 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1808
1809 // Concurrent Mark ref processor
1810 _ref_processor_cm =
1811 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1812 mt_processing, // mt processing
1813 ParallelGCThreads, // degree of mt processing
1814 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1815 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1816 false, // Reference discovery is not atomic
1817 &_is_alive_closure_cm, // is alive closure
1818 true); // allow changes to number of processing threads
1819
1820 // STW ref processor
1821 _ref_processor_stw =
1822 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1823 mt_processing, // mt processing
1824 ParallelGCThreads, // degree of mt processing
1825 (ParallelGCThreads > 1), // mt discovery
1826 ParallelGCThreads, // degree of mt discovery
1827 true, // Reference discovery is atomic
1828 &_is_alive_closure_stw, // is alive closure
1829 true); // allow changes to number of processing threads
1830 }
1831
1832 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1833 return _collector_policy;
1834 }
1835
1836 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1837 return &_soft_ref_policy;
1838 }
1839
1840 size_t G1CollectedHeap::capacity() const {
1841 return _hrm.length() * HeapRegion::GrainBytes;
1842 }
1843
1844 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1845 return _hrm.total_free_bytes();
1846 }
1847
1848 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1849 _hot_card_cache->drain(cl, worker_i);
1850 }
1851
1852 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1853 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1854 size_t n_completed_buffers = 0;
1855 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1856 n_completed_buffers++;
1857 }
1858 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1859 dcqs.clear_n_completed_buffers();
1860 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1861 }
1862
1863 // Computes the sum of the storage used by the various regions.
1864 size_t G1CollectedHeap::used() const {
1865 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1866 if (_archive_allocator != NULL) {
1867 result += _archive_allocator->used();
1868 }
1869 return result;
1870 }
1871
1872 size_t G1CollectedHeap::used_unlocked() const {
1873 return _summary_bytes_used;
1874 }
1875
1876 class SumUsedClosure: public HeapRegionClosure {
1877 size_t _used;
1878 public:
1879 SumUsedClosure() : _used(0) {}
1880 bool do_heap_region(HeapRegion* r) {
1881 _used += r->used();
1882 return false;
1883 }
1884 size_t result() { return _used; }
1885 };
1886
1887 size_t G1CollectedHeap::recalculate_used() const {
1888 double recalculate_used_start = os::elapsedTime();
1889
1890 SumUsedClosure blk;
1891 heap_region_iterate(&blk);
1892
1893 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1894 return blk.result();
1895 }
1896
1897 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1898 switch (cause) {
1899 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1900 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1901 case GCCause::_wb_conc_mark: return true;
1902 default : return false;
1903 }
1904 }
1905
1906 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1907 switch (cause) {
1908 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1909 case GCCause::_g1_humongous_allocation: return true;
1910 default: return is_user_requested_concurrent_full_gc(cause);
1911 }
1912 }
1913
1914 #ifndef PRODUCT
1915 void G1CollectedHeap::allocate_dummy_regions() {
1916 // Let's fill up most of the region
1917 size_t word_size = HeapRegion::GrainWords - 1024;
1918 // And as a result the region we'll allocate will be humongous.
1919 guarantee(is_humongous(word_size), "sanity");
1920
1921 // _filler_array_max_size is set to humongous object threshold
1922 // but temporarily change it to use CollectedHeap::fill_with_object().
1923 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1924
1925 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1926 // Let's use the existing mechanism for the allocation
1927 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1928 if (dummy_obj != NULL) {
1929 MemRegion mr(dummy_obj, word_size);
1930 CollectedHeap::fill_with_object(mr);
1931 } else {
1932 // If we can't allocate once, we probably cannot allocate
1933 // again. Let's get out of the loop.
1934 break;
1935 }
1936 }
1937 }
1938 #endif // !PRODUCT
1939
1940 void G1CollectedHeap::increment_old_marking_cycles_started() {
1941 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1942 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1943 "Wrong marking cycle count (started: %d, completed: %d)",
1944 _old_marking_cycles_started, _old_marking_cycles_completed);
1945
1946 _old_marking_cycles_started++;
1947 }
1948
1949 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
1950 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1951
1952 // We assume that if concurrent == true, then the caller is a
1953 // concurrent thread that was joined the Suspendible Thread
1954 // Set. If there's ever a cheap way to check this, we should add an
1955 // assert here.
1956
1957 // Given that this method is called at the end of a Full GC or of a
1958 // concurrent cycle, and those can be nested (i.e., a Full GC can
1959 // interrupt a concurrent cycle), the number of full collections
1960 // completed should be either one (in the case where there was no
1961 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1962 // behind the number of full collections started.
1963
1964 // This is the case for the inner caller, i.e. a Full GC.
1965 assert(concurrent ||
1966 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1967 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1968 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1969 "is inconsistent with _old_marking_cycles_completed = %u",
1970 _old_marking_cycles_started, _old_marking_cycles_completed);
1971
1972 // This is the case for the outer caller, i.e. the concurrent cycle.
1973 assert(!concurrent ||
1974 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1975 "for outer caller (concurrent cycle): "
1976 "_old_marking_cycles_started = %u "
1977 "is inconsistent with _old_marking_cycles_completed = %u",
1978 _old_marking_cycles_started, _old_marking_cycles_completed);
1979
1980 _old_marking_cycles_completed += 1;
1981
1982 // We need to clear the "in_progress" flag in the CM thread before
1983 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1984 // is set) so that if a waiter requests another System.gc() it doesn't
1985 // incorrectly see that a marking cycle is still in progress.
1986 if (concurrent) {
1987 _cm_thread->set_idle();
1988 }
1989
1990 // This notify_all() will ensure that a thread that called
1991 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
1992 // and it's waiting for a full GC to finish will be woken up. It is
1993 // waiting in VM_G1CollectForAllocation::doit_epilogue().
1994 FullGCCount_lock->notify_all();
1995 }
1996
1997 void G1CollectedHeap::collect(GCCause::Cause cause) {
1998 assert_heap_not_locked();
1999
2000 uint gc_count_before;
2001 uint old_marking_count_before;
2002 uint full_gc_count_before;
2003 bool retry_gc;
2004
2005 do {
2006 retry_gc = false;
2007
2008 {
2009 MutexLocker ml(Heap_lock);
2010
2011 // Read the GC count while holding the Heap_lock
2012 gc_count_before = total_collections();
2013 full_gc_count_before = total_full_collections();
2014 old_marking_count_before = _old_marking_cycles_started;
2015 }
2016
2017 if (should_do_concurrent_full_gc(cause)) {
2018 // Schedule an initial-mark evacuation pause that will start a
2019 // concurrent cycle. We're setting word_size to 0 which means that
2020 // we are not requesting a post-GC allocation.
2021 VM_G1CollectForAllocation op(0, /* word_size */
2022 gc_count_before,
2023 cause,
2024 true, /* should_initiate_conc_mark */
2025 g1_policy()->max_pause_time_ms());
2026 VMThread::execute(&op);
2027 if (!op.pause_succeeded()) {
2028 if (old_marking_count_before == _old_marking_cycles_started) {
2029 retry_gc = op.should_retry_gc();
2030 } else {
2031 // A Full GC happened while we were trying to schedule the
2032 // initial-mark GC. No point in starting a new cycle given
2033 // that the whole heap was collected anyway.
2034 }
2035
2036 if (retry_gc) {
2037 if (GCLocker::is_active_and_needs_gc()) {
2038 GCLocker::stall_until_clear();
2039 }
2040 }
2041 }
2042 } else {
2043 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2044 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2045
2046 // Schedule a standard evacuation pause. We're setting word_size
2047 // to 0 which means that we are not requesting a post-GC allocation.
2048 VM_G1CollectForAllocation op(0, /* word_size */
2049 gc_count_before,
2050 cause,
2051 false, /* should_initiate_conc_mark */
2052 g1_policy()->max_pause_time_ms());
2053 VMThread::execute(&op);
2054 } else {
2055 // Schedule a Full GC.
2056 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2057 VMThread::execute(&op);
2058 }
2059 }
2060 } while (retry_gc);
2061 }
2062
2063 bool G1CollectedHeap::is_in(const void* p) const {
2064 if (_hrm.reserved().contains(p)) {
2065 // Given that we know that p is in the reserved space,
2066 // heap_region_containing() should successfully
2067 // return the containing region.
2068 HeapRegion* hr = heap_region_containing(p);
2069 return hr->is_in(p);
2070 } else {
2071 return false;
2072 }
2073 }
2074
2075 #ifdef ASSERT
2076 bool G1CollectedHeap::is_in_exact(const void* p) const {
2077 bool contains = reserved_region().contains(p);
2078 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2079 if (contains && available) {
2080 return true;
2081 } else {
2082 return false;
2083 }
2084 }
2085 #endif
2086
2087 // Iteration functions.
2088
2089 // Iterates an ObjectClosure over all objects within a HeapRegion.
2090
2091 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2092 ObjectClosure* _cl;
2093 public:
2094 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2095 bool do_heap_region(HeapRegion* r) {
2096 if (!r->is_continues_humongous()) {
2097 r->object_iterate(_cl);
2098 }
2099 return false;
2100 }
2101 };
2102
2103 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2104 IterateObjectClosureRegionClosure blk(cl);
2105 heap_region_iterate(&blk);
2106 }
2107
2108 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2109 _hrm.iterate(cl);
2110 }
2111
2112 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2113 HeapRegionClaimer *hrclaimer,
2114 uint worker_id) const {
2115 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2116 }
2117
2118 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2119 HeapRegionClaimer *hrclaimer) const {
2120 _hrm.par_iterate(cl, hrclaimer, 0);
2121 }
2122
2123 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2124 _collection_set.iterate(cl);
2125 }
2126
2127 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2128 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2129 }
2130
2131 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2132 HeapRegion* hr = heap_region_containing(addr);
2133 return hr->block_start(addr);
2134 }
2135
2136 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2137 HeapRegion* hr = heap_region_containing(addr);
2138 return hr->block_size(addr);
2139 }
2140
2141 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2142 HeapRegion* hr = heap_region_containing(addr);
2143 return hr->block_is_obj(addr);
2144 }
2145
2146 bool G1CollectedHeap::supports_tlab_allocation() const {
2147 return true;
2148 }
2149
2150 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2151 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2152 }
2153
2154 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2155 return _eden.length() * HeapRegion::GrainBytes;
2156 }
2157
2158 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2159 // must be equal to the humongous object limit.
2160 size_t G1CollectedHeap::max_tlab_size() const {
2161 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2162 }
2163
2164 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2165 return _allocator->unsafe_max_tlab_alloc();
2166 }
2167
2168 size_t G1CollectedHeap::max_capacity() const {
2169 return _hrm.reserved().byte_size();
2170 }
2171
2172 jlong G1CollectedHeap::millis_since_last_gc() {
2173 // See the notes in GenCollectedHeap::millis_since_last_gc()
2174 // for more information about the implementation.
2175 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2176 _g1_policy->collection_pause_end_millis();
2177 if (ret_val < 0) {
2178 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2179 ". returning zero instead.", ret_val);
2180 return 0;
2181 }
2182 return ret_val;
2183 }
2184
2185 void G1CollectedHeap::deduplicate_string(oop str) {
2186 assert(java_lang_String::is_instance(str), "invariant");
2187
2188 if (G1StringDedup::is_enabled()) {
2189 G1StringDedup::deduplicate(str);
2190 }
2191 }
2192
2193 void G1CollectedHeap::prepare_for_verify() {
2194 _verifier->prepare_for_verify();
2195 }
2196
2197 void G1CollectedHeap::verify(VerifyOption vo) {
2198 _verifier->verify(vo);
2199 }
2200
2201 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2202 return true;
2203 }
2204
2205 const char* const* G1CollectedHeap::concurrent_phases() const {
2206 return _cm_thread->concurrent_phases();
2207 }
2208
2209 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2210 return _cm_thread->request_concurrent_phase(phase);
2211 }
2212
2213 class PrintRegionClosure: public HeapRegionClosure {
2214 outputStream* _st;
2215 public:
2216 PrintRegionClosure(outputStream* st) : _st(st) {}
2217 bool do_heap_region(HeapRegion* r) {
2218 r->print_on(_st);
2219 return false;
2220 }
2221 };
2222
2223 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2224 const HeapRegion* hr,
2225 const VerifyOption vo) const {
2226 switch (vo) {
2227 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2228 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2229 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2230 default: ShouldNotReachHere();
2231 }
2232 return false; // keep some compilers happy
2233 }
2234
2235 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2236 const VerifyOption vo) const {
2237 switch (vo) {
2238 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2239 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2240 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2241 default: ShouldNotReachHere();
2242 }
2243 return false; // keep some compilers happy
2244 }
2245
2246 void G1CollectedHeap::print_heap_regions() const {
2247 LogTarget(Trace, gc, heap, region) lt;
2248 if (lt.is_enabled()) {
2249 LogStream ls(lt);
2250 print_regions_on(&ls);
2251 }
2252 }
2253
2254 void G1CollectedHeap::print_on(outputStream* st) const {
2255 st->print(" %-20s", "garbage-first heap");
2256 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2257 capacity()/K, used_unlocked()/K);
2258 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2259 p2i(_hrm.reserved().start()),
2260 p2i(_hrm.reserved().end()));
2261 st->cr();
2262 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2263 uint young_regions = young_regions_count();
2264 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2265 (size_t) young_regions * HeapRegion::GrainBytes / K);
2266 uint survivor_regions = survivor_regions_count();
2267 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2268 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2269 st->cr();
2270 MetaspaceUtils::print_on(st);
2271 }
2272
2273 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2274 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2275 "HS=humongous(starts), HC=humongous(continues), "
2276 "CS=collection set, F=free, A=archive, "
2277 "TAMS=top-at-mark-start (previous, next)");
2278 PrintRegionClosure blk(st);
2279 heap_region_iterate(&blk);
2280 }
2281
2282 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2283 print_on(st);
2284
2285 // Print the per-region information.
2286 print_regions_on(st);
2287 }
2288
2289 void G1CollectedHeap::print_on_error(outputStream* st) const {
2290 this->CollectedHeap::print_on_error(st);
2291
2292 if (_cm != NULL) {
2293 st->cr();
2294 _cm->print_on_error(st);
2295 }
2296 }
2297
2298 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2299 workers()->print_worker_threads_on(st);
2300 _cm_thread->print_on(st);
2301 st->cr();
2302 _cm->print_worker_threads_on(st);
2303 _cr->print_threads_on(st);
2304 _young_gen_sampling_thread->print_on(st);
2305 if (G1StringDedup::is_enabled()) {
2306 G1StringDedup::print_worker_threads_on(st);
2307 }
2308 }
2309
2310 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2311 workers()->threads_do(tc);
2312 tc->do_thread(_cm_thread);
2313 _cm->threads_do(tc);
2314 _cr->threads_do(tc);
2315 tc->do_thread(_young_gen_sampling_thread);
2316 if (G1StringDedup::is_enabled()) {
2317 G1StringDedup::threads_do(tc);
2318 }
2319 }
2320
2321 void G1CollectedHeap::print_tracing_info() const {
2322 g1_rem_set()->print_summary_info();
2323 concurrent_mark()->print_summary_info();
2324 }
2325
2326 #ifndef PRODUCT
2327 // Helpful for debugging RSet issues.
2328
2329 class PrintRSetsClosure : public HeapRegionClosure {
2330 private:
2331 const char* _msg;
2332 size_t _occupied_sum;
2333
2334 public:
2335 bool do_heap_region(HeapRegion* r) {
2336 HeapRegionRemSet* hrrs = r->rem_set();
2337 size_t occupied = hrrs->occupied();
2338 _occupied_sum += occupied;
2339
2340 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2341 if (occupied == 0) {
2342 tty->print_cr(" RSet is empty");
2343 } else {
2344 hrrs->print();
2345 }
2346 tty->print_cr("----------");
2347 return false;
2348 }
2349
2350 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2351 tty->cr();
2352 tty->print_cr("========================================");
2353 tty->print_cr("%s", msg);
2354 tty->cr();
2355 }
2356
2357 ~PrintRSetsClosure() {
2358 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2359 tty->print_cr("========================================");
2360 tty->cr();
2361 }
2362 };
2363
2364 void G1CollectedHeap::print_cset_rsets() {
2365 PrintRSetsClosure cl("Printing CSet RSets");
2366 collection_set_iterate(&cl);
2367 }
2368
2369 void G1CollectedHeap::print_all_rsets() {
2370 PrintRSetsClosure cl("Printing All RSets");;
2371 heap_region_iterate(&cl);
2372 }
2373 #endif // PRODUCT
2374
2375 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2376
2377 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2378 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2379 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2380
2381 size_t eden_capacity_bytes =
2382 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2383
2384 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2385 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2386 eden_capacity_bytes, survivor_used_bytes, num_regions());
2387 }
2388
2389 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2390 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2391 stats->unused(), stats->used(), stats->region_end_waste(),
2392 stats->regions_filled(), stats->direct_allocated(),
2393 stats->failure_used(), stats->failure_waste());
2394 }
2395
2396 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2397 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2398 gc_tracer->report_gc_heap_summary(when, heap_summary);
2399
2400 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2401 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2402 }
2403
2404 G1CollectedHeap* G1CollectedHeap::heap() {
2405 CollectedHeap* heap = Universe::heap();
2406 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2407 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2408 return (G1CollectedHeap*)heap;
2409 }
2410
2411 void G1CollectedHeap::gc_prologue(bool full) {
2412 // always_do_update_barrier = false;
2413 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2414
2415 // This summary needs to be printed before incrementing total collections.
2416 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2417
2418 // Update common counters.
2419 increment_total_collections(full /* full gc */);
2420 if (full) {
2421 increment_old_marking_cycles_started();
2422 }
2423
2424 // Fill TLAB's and such
2425 double start = os::elapsedTime();
2426 accumulate_statistics_all_tlabs();
2427 ensure_parsability(true);
2428 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2429 }
2430
2431 void G1CollectedHeap::gc_epilogue(bool full) {
2432 // Update common counters.
2433 if (full) {
2434 // Update the number of full collections that have been completed.
2435 increment_old_marking_cycles_completed(false /* concurrent */);
2436 }
2437
2438 // We are at the end of the GC. Total collections has already been increased.
2439 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2440
2441 // FIXME: what is this about?
2442 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2443 // is set.
2444 #if COMPILER2_OR_JVMCI
2445 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2446 #endif
2447 // always_do_update_barrier = true;
2448
2449 double start = os::elapsedTime();
2450 resize_all_tlabs();
2451 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2452
2453 MemoryService::track_memory_usage();
2454 // We have just completed a GC. Update the soft reference
2455 // policy with the new heap occupancy
2456 Universe::update_heap_info_at_gc();
2457 }
2458
2459 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2460 uint gc_count_before,
2461 bool* succeeded,
2462 GCCause::Cause gc_cause) {
2463 assert_heap_not_locked_and_not_at_safepoint();
2464 VM_G1CollectForAllocation op(word_size,
2465 gc_count_before,
2466 gc_cause,
2467 false, /* should_initiate_conc_mark */
2468 g1_policy()->max_pause_time_ms());
2469 VMThread::execute(&op);
2470
2471 HeapWord* result = op.result();
2472 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2473 assert(result == NULL || ret_succeeded,
2474 "the result should be NULL if the VM did not succeed");
2475 *succeeded = ret_succeeded;
2476
2477 assert_heap_not_locked();
2478 return result;
2479 }
2480
2481 void G1CollectedHeap::do_concurrent_mark() {
2482 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2483 if (!_cm_thread->in_progress()) {
2484 _cm_thread->set_started();
2485 CGC_lock->notify();
2486 }
2487 }
2488
2489 size_t G1CollectedHeap::pending_card_num() {
2490 size_t extra_cards = 0;
2491 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2492 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2493 extra_cards += dcq.size();
2494 }
2495 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2496 size_t buffer_size = dcqs.buffer_size();
2497 size_t buffer_num = dcqs.completed_buffers_num();
2498
2499 return buffer_size * buffer_num + extra_cards;
2500 }
2501
2502 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2503 // We don't nominate objects with many remembered set entries, on
2504 // the assumption that such objects are likely still live.
2505 HeapRegionRemSet* rem_set = r->rem_set();
2506
2507 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2508 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2509 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2510 }
2511
2512 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2513 private:
2514 size_t _total_humongous;
2515 size_t _candidate_humongous;
2516
2517 DirtyCardQueue _dcq;
2518
2519 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2520 assert(region->is_starts_humongous(), "Must start a humongous object");
2521
2522 oop obj = oop(region->bottom());
2523
2524 // Dead objects cannot be eager reclaim candidates. Due to class
2525 // unloading it is unsafe to query their classes so we return early.
2526 if (g1h->is_obj_dead(obj, region)) {
2527 return false;
2528 }
2529
2530 // If we do not have a complete remembered set for the region, then we can
2531 // not be sure that we have all references to it.
2532 if (!region->rem_set()->is_complete()) {
2533 return false;
2534 }
2535 // Candidate selection must satisfy the following constraints
2536 // while concurrent marking is in progress:
2537 //
2538 // * In order to maintain SATB invariants, an object must not be
2539 // reclaimed if it was allocated before the start of marking and
2540 // has not had its references scanned. Such an object must have
2541 // its references (including type metadata) scanned to ensure no
2542 // live objects are missed by the marking process. Objects
2543 // allocated after the start of concurrent marking don't need to
2544 // be scanned.
2545 //
2546 // * An object must not be reclaimed if it is on the concurrent
2547 // mark stack. Objects allocated after the start of concurrent
2548 // marking are never pushed on the mark stack.
2549 //
2550 // Nominating only objects allocated after the start of concurrent
2551 // marking is sufficient to meet both constraints. This may miss
2552 // some objects that satisfy the constraints, but the marking data
2553 // structures don't support efficiently performing the needed
2554 // additional tests or scrubbing of the mark stack.
2555 //
2556 // However, we presently only nominate is_typeArray() objects.
2557 // A humongous object containing references induces remembered
2558 // set entries on other regions. In order to reclaim such an
2559 // object, those remembered sets would need to be cleaned up.
2560 //
2561 // We also treat is_typeArray() objects specially, allowing them
2562 // to be reclaimed even if allocated before the start of
2563 // concurrent mark. For this we rely on mark stack insertion to
2564 // exclude is_typeArray() objects, preventing reclaiming an object
2565 // that is in the mark stack. We also rely on the metadata for
2566 // such objects to be built-in and so ensured to be kept live.
2567 // Frequent allocation and drop of large binary blobs is an
2568 // important use case for eager reclaim, and this special handling
2569 // may reduce needed headroom.
2570
2571 return obj->is_typeArray() &&
2572 g1h->is_potential_eager_reclaim_candidate(region);
2573 }
2574
2575 public:
2576 RegisterHumongousWithInCSetFastTestClosure()
2577 : _total_humongous(0),
2578 _candidate_humongous(0),
2579 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2580 }
2581
2582 virtual bool do_heap_region(HeapRegion* r) {
2583 if (!r->is_starts_humongous()) {
2584 return false;
2585 }
2586 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2587
2588 bool is_candidate = humongous_region_is_candidate(g1h, r);
2589 uint rindex = r->hrm_index();
2590 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2591 if (is_candidate) {
2592 _candidate_humongous++;
2593 g1h->register_humongous_region_with_cset(rindex);
2594 // Is_candidate already filters out humongous object with large remembered sets.
2595 // If we have a humongous object with a few remembered sets, we simply flush these
2596 // remembered set entries into the DCQS. That will result in automatic
2597 // re-evaluation of their remembered set entries during the following evacuation
2598 // phase.
2599 if (!r->rem_set()->is_empty()) {
2600 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2601 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2602 G1CardTable* ct = g1h->card_table();
2603 HeapRegionRemSetIterator hrrs(r->rem_set());
2604 size_t card_index;
2605 while (hrrs.has_next(card_index)) {
2606 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2607 // The remembered set might contain references to already freed
2608 // regions. Filter out such entries to avoid failing card table
2609 // verification.
2610 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2611 if (*card_ptr != G1CardTable::dirty_card_val()) {
2612 *card_ptr = G1CardTable::dirty_card_val();
2613 _dcq.enqueue(card_ptr);
2614 }
2615 }
2616 }
2617 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2618 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2619 hrrs.n_yielded(), r->rem_set()->occupied());
2620 // We should only clear the card based remembered set here as we will not
2621 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2622 // (and probably never) we do not enter this path if there are other kind of
2623 // remembered sets for this region.
2624 r->rem_set()->clear_locked(true /* only_cardset */);
2625 // Clear_locked() above sets the state to Empty. However we want to continue
2626 // collecting remembered set entries for humongous regions that were not
2627 // reclaimed.
2628 r->rem_set()->set_state_complete();
2629 }
2630 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2631 }
2632 _total_humongous++;
2633
2634 return false;
2635 }
2636
2637 size_t total_humongous() const { return _total_humongous; }
2638 size_t candidate_humongous() const { return _candidate_humongous; }
2639
2640 void flush_rem_set_entries() { _dcq.flush(); }
2641 };
2642
2643 void G1CollectedHeap::register_humongous_regions_with_cset() {
2644 if (!G1EagerReclaimHumongousObjects) {
2645 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2646 return;
2647 }
2648 double time = os::elapsed_counter();
2649
2650 // Collect reclaim candidate information and register candidates with cset.
2651 RegisterHumongousWithInCSetFastTestClosure cl;
2652 heap_region_iterate(&cl);
2653
2654 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2655 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2656 cl.total_humongous(),
2657 cl.candidate_humongous());
2658 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2659
2660 // Finally flush all remembered set entries to re-check into the global DCQS.
2661 cl.flush_rem_set_entries();
2662 }
2663
2664 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2665 public:
2666 bool do_heap_region(HeapRegion* hr) {
2667 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2668 hr->verify_rem_set();
2669 }
2670 return false;
2671 }
2672 };
2673
2674 uint G1CollectedHeap::num_task_queues() const {
2675 return _task_queues->size();
2676 }
2677
2678 #if TASKQUEUE_STATS
2679 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2680 st->print_raw_cr("GC Task Stats");
2681 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2682 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2683 }
2684
2685 void G1CollectedHeap::print_taskqueue_stats() const {
2686 if (!log_is_enabled(Trace, gc, task, stats)) {
2687 return;
2688 }
2689 Log(gc, task, stats) log;
2690 ResourceMark rm;
2691 LogStream ls(log.trace());
2692 outputStream* st = &ls;
2693
2694 print_taskqueue_stats_hdr(st);
2695
2696 TaskQueueStats totals;
2697 const uint n = num_task_queues();
2698 for (uint i = 0; i < n; ++i) {
2699 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2700 totals += task_queue(i)->stats;
2701 }
2702 st->print_raw("tot "); totals.print(st); st->cr();
2703
2704 DEBUG_ONLY(totals.verify());
2705 }
2706
2707 void G1CollectedHeap::reset_taskqueue_stats() {
2708 const uint n = num_task_queues();
2709 for (uint i = 0; i < n; ++i) {
2710 task_queue(i)->stats.reset();
2711 }
2712 }
2713 #endif // TASKQUEUE_STATS
2714
2715 void G1CollectedHeap::wait_for_root_region_scanning() {
2716 double scan_wait_start = os::elapsedTime();
2717 // We have to wait until the CM threads finish scanning the
2718 // root regions as it's the only way to ensure that all the
2719 // objects on them have been correctly scanned before we start
2720 // moving them during the GC.
2721 bool waited = _cm->root_regions()->wait_until_scan_finished();
2722 double wait_time_ms = 0.0;
2723 if (waited) {
2724 double scan_wait_end = os::elapsedTime();
2725 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2726 }
2727 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2728 }
2729
2730 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2731 private:
2732 G1HRPrinter* _hr_printer;
2733 public:
2734 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2735
2736 virtual bool do_heap_region(HeapRegion* r) {
2737 _hr_printer->cset(r);
2738 return false;
2739 }
2740 };
2741
2742 void G1CollectedHeap::start_new_collection_set() {
2743 collection_set()->start_incremental_building();
2744
2745 clear_cset_fast_test();
2746
2747 guarantee(_eden.length() == 0, "eden should have been cleared");
2748 g1_policy()->transfer_survivors_to_cset(survivor());
2749 }
2750
2751 bool
2752 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2753 assert_at_safepoint_on_vm_thread();
2754 guarantee(!is_gc_active(), "collection is not reentrant");
2755
2756 if (GCLocker::check_active_before_gc()) {
2757 return false;
2758 }
2759
2760 _gc_timer_stw->register_gc_start();
2761
2762 GCIdMark gc_id_mark;
2763 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2764
2765 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2766 ResourceMark rm;
2767
2768 g1_policy()->note_gc_start();
2769
2770 wait_for_root_region_scanning();
2771
2772 print_heap_before_gc();
2773 print_heap_regions();
2774 trace_heap_before_gc(_gc_tracer_stw);
2775
2776 _verifier->verify_region_sets_optional();
2777 _verifier->verify_dirty_young_regions();
2778
2779 // We should not be doing initial mark unless the conc mark thread is running
2780 if (!_cm_thread->should_terminate()) {
2781 // This call will decide whether this pause is an initial-mark
2782 // pause. If it is, in_initial_mark_gc() will return true
2783 // for the duration of this pause.
2784 g1_policy()->decide_on_conc_mark_initiation();
2785 }
2786
2787 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2788 assert(!collector_state()->in_initial_mark_gc() ||
2789 collector_state()->in_young_only_phase(), "sanity");
2790
2791 // We also do not allow mixed GCs during marking.
2792 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2793
2794 // Record whether this pause is an initial mark. When the current
2795 // thread has completed its logging output and it's safe to signal
2796 // the CM thread, the flag's value in the policy has been reset.
2797 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2798
2799 // Inner scope for scope based logging, timers, and stats collection
2800 {
2801 EvacuationInfo evacuation_info;
2802
2803 if (collector_state()->in_initial_mark_gc()) {
2804 // We are about to start a marking cycle, so we increment the
2805 // full collection counter.
2806 increment_old_marking_cycles_started();
2807 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2808 }
2809
2810 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2811
2812 GCTraceCPUTime tcpu;
2813
2814 G1HeapVerifier::G1VerifyType verify_type;
2815 FormatBuffer<> gc_string("Pause Young ");
2816 if (collector_state()->in_initial_mark_gc()) {
2817 gc_string.append("(Concurrent Start)");
2818 verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2819 } else if (collector_state()->in_young_only_phase()) {
2820 if (collector_state()->in_young_gc_before_mixed()) {
2821 gc_string.append("(Prepare Mixed)");
2822 } else {
2823 gc_string.append("(Normal)");
2824 }
2825 verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2826 } else {
2827 gc_string.append("(Mixed)");
2828 verify_type = G1HeapVerifier::G1VerifyMixed;
2829 }
2830 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2831
2832 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2833 workers()->active_workers(),
2834 Threads::number_of_non_daemon_threads());
2835 active_workers = workers()->update_active_workers(active_workers);
2836 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2837
2838 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2839 TraceMemoryManagerStats tms(&_memory_manager, gc_cause(),
2840 collector_state()->yc_type() == Mixed /* allMemoryPoolsAffected */);
2841
2842 G1HeapTransition heap_transition(this);
2843 size_t heap_used_bytes_before_gc = used();
2844
2845 // Don't dynamically change the number of GC threads this early. A value of
2846 // 0 is used to indicate serial work. When parallel work is done,
2847 // it will be set.
2848
2849 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2850 IsGCActiveMark x;
2851
2852 gc_prologue(false);
2853
2854 if (VerifyRememberedSets) {
2855 log_info(gc, verify)("[Verifying RemSets before GC]");
2856 VerifyRegionRemSetClosure v_cl;
2857 heap_region_iterate(&v_cl);
2858 }
2859
2860 _verifier->verify_before_gc(verify_type);
2861
2862 _verifier->check_bitmaps("GC Start");
2863
2864 #if COMPILER2_OR_JVMCI
2865 DerivedPointerTable::clear();
2866 #endif
2867
2868 // Please see comment in g1CollectedHeap.hpp and
2869 // G1CollectedHeap::ref_processing_init() to see how
2870 // reference processing currently works in G1.
2871
2872 // Enable discovery in the STW reference processor
2873 _ref_processor_stw->enable_discovery();
2874
2875 {
2876 // We want to temporarily turn off discovery by the
2877 // CM ref processor, if necessary, and turn it back on
2878 // on again later if we do. Using a scoped
2879 // NoRefDiscovery object will do this.
2880 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2881
2882 // Forget the current alloc region (we might even choose it to be part
2883 // of the collection set!).
2884 _allocator->release_mutator_alloc_region();
2885
2886 // This timing is only used by the ergonomics to handle our pause target.
2887 // It is unclear why this should not include the full pause. We will
2888 // investigate this in CR 7178365.
2889 //
2890 // Preserving the old comment here if that helps the investigation:
2891 //
2892 // The elapsed time induced by the start time below deliberately elides
2893 // the possible verification above.
2894 double sample_start_time_sec = os::elapsedTime();
2895
2896 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2897
2898 if (collector_state()->in_initial_mark_gc()) {
2899 concurrent_mark()->pre_initial_mark();
2900 }
2901
2902 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2903
2904 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2905
2906 // Make sure the remembered sets are up to date. This needs to be
2907 // done before register_humongous_regions_with_cset(), because the
2908 // remembered sets are used there to choose eager reclaim candidates.
2909 // If the remembered sets are not up to date we might miss some
2910 // entries that need to be handled.
2911 g1_rem_set()->cleanupHRRS();
2912
2913 register_humongous_regions_with_cset();
2914
2915 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2916
2917 // We call this after finalize_cset() to
2918 // ensure that the CSet has been finalized.
2919 _cm->verify_no_cset_oops();
2920
2921 if (_hr_printer.is_active()) {
2922 G1PrintCollectionSetClosure cl(&_hr_printer);
2923 _collection_set.iterate(&cl);
2924 }
2925
2926 // Initialize the GC alloc regions.
2927 _allocator->init_gc_alloc_regions(evacuation_info);
2928
2929 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2930 pre_evacuate_collection_set();
2931
2932 // Actually do the work...
2933 evacuate_collection_set(&per_thread_states);
2934
2935 post_evacuate_collection_set(evacuation_info, &per_thread_states);
2936
2937 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2938 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2939
2940 eagerly_reclaim_humongous_regions();
2941
2942 record_obj_copy_mem_stats();
2943 _survivor_evac_stats.adjust_desired_plab_sz();
2944 _old_evac_stats.adjust_desired_plab_sz();
2945
2946 double start = os::elapsedTime();
2947 start_new_collection_set();
2948 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2949
2950 if (evacuation_failed()) {
2951 set_used(recalculate_used());
2952 if (_archive_allocator != NULL) {
2953 _archive_allocator->clear_used();
2954 }
2955 for (uint i = 0; i < ParallelGCThreads; i++) {
2956 if (_evacuation_failed_info_array[i].has_failed()) {
2957 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
2958 }
2959 }
2960 } else {
2961 // The "used" of the the collection set have already been subtracted
2962 // when they were freed. Add in the bytes evacuated.
2963 increase_used(g1_policy()->bytes_copied_during_gc());
2964 }
2965
2966 if (collector_state()->in_initial_mark_gc()) {
2967 // We have to do this before we notify the CM threads that
2968 // they can start working to make sure that all the
2969 // appropriate initialization is done on the CM object.
2970 concurrent_mark()->post_initial_mark();
2971 // Note that we don't actually trigger the CM thread at
2972 // this point. We do that later when we're sure that
2973 // the current thread has completed its logging output.
2974 }
2975
2976 allocate_dummy_regions();
2977
2978 _allocator->init_mutator_alloc_region();
2979
2980 {
2981 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2982 if (expand_bytes > 0) {
2983 size_t bytes_before = capacity();
2984 // No need for an ergo logging here,
2985 // expansion_amount() does this when it returns a value > 0.
2986 double expand_ms;
2987 if (!expand(expand_bytes, _workers, &expand_ms)) {
2988 // We failed to expand the heap. Cannot do anything about it.
2989 }
2990 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
2991 }
2992 }
2993
2994 // We redo the verification but now wrt to the new CSet which
2995 // has just got initialized after the previous CSet was freed.
2996 _cm->verify_no_cset_oops();
2997
2998 // This timing is only used by the ergonomics to handle our pause target.
2999 // It is unclear why this should not include the full pause. We will
3000 // investigate this in CR 7178365.
3001 double sample_end_time_sec = os::elapsedTime();
3002 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3003 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3004 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3005
3006 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3007 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3008
3009 if (VerifyRememberedSets) {
3010 log_info(gc, verify)("[Verifying RemSets after GC]");
3011 VerifyRegionRemSetClosure v_cl;
3012 heap_region_iterate(&v_cl);
3013 }
3014
3015 _verifier->verify_after_gc(verify_type);
3016 _verifier->check_bitmaps("GC End");
3017
3018 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3019 _ref_processor_stw->verify_no_references_recorded();
3020
3021 // CM reference discovery will be re-enabled if necessary.
3022 }
3023
3024 #ifdef TRACESPINNING
3025 ParallelTaskTerminator::print_termination_counts();
3026 #endif
3027
3028 gc_epilogue(false);
3029 }
3030
3031 // Print the remainder of the GC log output.
3032 if (evacuation_failed()) {
3033 log_info(gc)("To-space exhausted");
3034 }
3035
3036 g1_policy()->print_phases();
3037 heap_transition.print();
3038
3039 // It is not yet to safe to tell the concurrent mark to
3040 // start as we have some optional output below. We don't want the
3041 // output from the concurrent mark thread interfering with this
3042 // logging output either.
3043
3044 _hrm.verify_optional();
3045 _verifier->verify_region_sets_optional();
3046
3047 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3048 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3049
3050 print_heap_after_gc();
3051 print_heap_regions();
3052 trace_heap_after_gc(_gc_tracer_stw);
3053
3054 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3055 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3056 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3057 // before any GC notifications are raised.
3058 g1mm()->update_sizes();
3059
3060 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3061 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3062 _gc_timer_stw->register_gc_end();
3063 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3064 }
3065 // It should now be safe to tell the concurrent mark thread to start
3066 // without its logging output interfering with the logging output
3067 // that came from the pause.
3068
3069 if (should_start_conc_mark) {
3070 // CAUTION: after the doConcurrentMark() call below,
3071 // the concurrent marking thread(s) could be running
3072 // concurrently with us. Make sure that anything after
3073 // this point does not assume that we are the only GC thread
3074 // running. Note: of course, the actual marking work will
3075 // not start until the safepoint itself is released in
3076 // SuspendibleThreadSet::desynchronize().
3077 do_concurrent_mark();
3078 }
3079
3080 return true;
3081 }
3082
3083 void G1CollectedHeap::remove_self_forwarding_pointers() {
3084 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3085 workers()->run_task(&rsfp_task);
3086 }
3087
3088 void G1CollectedHeap::restore_after_evac_failure() {
3089 double remove_self_forwards_start = os::elapsedTime();
3090
3091 remove_self_forwarding_pointers();
3092 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3093 _preserved_marks_set.restore(&task_executor);
3094
3095 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3096 }
3097
3098 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3099 if (!_evacuation_failed) {
3100 _evacuation_failed = true;
3101 }
3102
3103 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3104 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3105 }
3106
3107 bool G1ParEvacuateFollowersClosure::offer_termination() {
3108 G1ParScanThreadState* const pss = par_scan_state();
3109 start_term_time();
3110 const bool res = terminator()->offer_termination();
3111 end_term_time();
3112 return res;
3113 }
3114
3115 void G1ParEvacuateFollowersClosure::do_void() {
3116 G1ParScanThreadState* const pss = par_scan_state();
3117 pss->trim_queue();
3118 do {
3119 pss->steal_and_trim_queue(queues());
3120 } while (!offer_termination());
3121 }
3122
3123 class G1ParTask : public AbstractGangTask {
3124 protected:
3125 G1CollectedHeap* _g1h;
3126 G1ParScanThreadStateSet* _pss;
3127 RefToScanQueueSet* _queues;
3128 G1RootProcessor* _root_processor;
3129 ParallelTaskTerminator _terminator;
3130 uint _n_workers;
3131
3132 public:
3133 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3134 : AbstractGangTask("G1 collection"),
3135 _g1h(g1h),
3136 _pss(per_thread_states),
3137 _queues(task_queues),
3138 _root_processor(root_processor),
3139 _terminator(n_workers, _queues),
3140 _n_workers(n_workers)
3141 {}
3142
3143 void work(uint worker_id) {
3144 if (worker_id >= _n_workers) return; // no work needed this round
3145
3146 double start_sec = os::elapsedTime();
3147 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3148
3149 {
3150 ResourceMark rm;
3151 HandleMark hm;
3152
3153 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3154
3155 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3156 pss->set_ref_discoverer(rp);
3157
3158 double start_strong_roots_sec = os::elapsedTime();
3159
3160 _root_processor->evacuate_roots(pss, worker_id);
3161
3162 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3163 // treating the nmethods visited to act as roots for concurrent marking.
3164 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3165 // objects copied by the current evacuation.
3166 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3167
3168 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3169
3170 double term_sec = 0.0;
3171 size_t evac_term_attempts = 0;
3172 {
3173 double start = os::elapsedTime();
3174 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3175 evac.do_void();
3176
3177 evac_term_attempts = evac.term_attempts();
3178 term_sec = evac.term_time();
3179 double elapsed_sec = os::elapsedTime() - start;
3180
3181 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3182 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3183 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3184 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3185 }
3186
3187 assert(pss->queue_is_empty(), "should be empty");
3188
3189 if (log_is_enabled(Debug, gc, task, stats)) {
3190 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3191 size_t lab_waste;
3192 size_t lab_undo_waste;
3193 pss->waste(lab_waste, lab_undo_waste);
3194 _g1h->print_termination_stats(worker_id,
3195 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3196 strong_roots_sec * 1000.0, /* strong roots time */
3197 term_sec * 1000.0, /* evac term time */
3198 evac_term_attempts, /* evac term attempts */
3199 lab_waste, /* alloc buffer waste */
3200 lab_undo_waste /* undo waste */
3201 );
3202 }
3203
3204 // Close the inner scope so that the ResourceMark and HandleMark
3205 // destructors are executed here and are included as part of the
3206 // "GC Worker Time".
3207 }
3208 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3209 }
3210 };
3211
3212 void G1CollectedHeap::print_termination_stats_hdr() {
3213 log_debug(gc, task, stats)("GC Termination Stats");
3214 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3215 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3216 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3217 }
3218
3219 void G1CollectedHeap::print_termination_stats(uint worker_id,
3220 double elapsed_ms,
3221 double strong_roots_ms,
3222 double term_ms,
3223 size_t term_attempts,
3224 size_t alloc_buffer_waste,
3225 size_t undo_waste) const {
3226 log_debug(gc, task, stats)
3227 ("%3d %9.2f %9.2f %6.2f "
3228 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3229 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3230 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3231 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3232 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3233 alloc_buffer_waste * HeapWordSize / K,
3234 undo_waste * HeapWordSize / K);
3235 }
3236
3237 class G1StringCleaningTask : public AbstractGangTask {
3238 private:
3239 BoolObjectClosure* _is_alive;
3240 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3241 OopStorage::ParState<false /* concurrent */, false /* const */> _par_state_string;
3242
3243 int _initial_string_table_size;
3244
3245 bool _process_strings;
3246 int _strings_processed;
3247 int _strings_removed;
3248
3249 bool _process_string_dedup;
3250
3251 public:
3252 G1StringCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_string_dedup) :
3253 AbstractGangTask("String Unlinking"),
3254 _is_alive(is_alive),
3255 _dedup_closure(is_alive, NULL, false),
3256 _par_state_string(StringTable::weak_storage()),
3257 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3258 _process_string_dedup(process_string_dedup) {
3259
3260 _initial_string_table_size = (int) StringTable::the_table()->table_size();
3261 if (process_strings) {
3262 StringTable::reset_dead_counter();
3263 }
3264 }
3265
3266 ~G1StringCleaningTask() {
3267 log_info(gc, stringtable)(
3268 "Cleaned string table, "
3269 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3270 strings_processed(), strings_removed());
3271 if (_process_strings) {
3272 StringTable::finish_dead_counter();
3273 }
3274 }
3275
3276 void work(uint worker_id) {
3277 int strings_processed = 0;
3278 int strings_removed = 0;
3279 if (_process_strings) {
3280 StringTable::possibly_parallel_unlink(&_par_state_string, _is_alive, &strings_processed, &strings_removed);
3281 Atomic::add(strings_processed, &_strings_processed);
3282 Atomic::add(strings_removed, &_strings_removed);
3283 }
3284 if (_process_string_dedup) {
3285 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3286 }
3287 }
3288
3289 size_t strings_processed() const { return (size_t)_strings_processed; }
3290 size_t strings_removed() const { return (size_t)_strings_removed; }
3291 };
3292
3293 class G1CodeCacheUnloadingTask {
3294 private:
3295 static Monitor* _lock;
3296
3297 BoolObjectClosure* const _is_alive;
3298 const bool _unloading_occurred;
3299 const uint _num_workers;
3300
3301 // Variables used to claim nmethods.
3302 CompiledMethod* _first_nmethod;
3303 CompiledMethod* volatile _claimed_nmethod;
3304
3305 // The list of nmethods that need to be processed by the second pass.
3306 CompiledMethod* volatile _postponed_list;
3307 volatile uint _num_entered_barrier;
3308
3309 public:
3310 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3311 _is_alive(is_alive),
3312 _unloading_occurred(unloading_occurred),
3313 _num_workers(num_workers),
3314 _first_nmethod(NULL),
3315 _claimed_nmethod(NULL),
3316 _postponed_list(NULL),
3317 _num_entered_barrier(0)
3318 {
3319 CompiledMethod::increase_unloading_clock();
3320 // Get first alive nmethod
3321 CompiledMethodIterator iter = CompiledMethodIterator();
3322 if(iter.next_alive()) {
3323 _first_nmethod = iter.method();
3324 }
3325 _claimed_nmethod = _first_nmethod;
3326 }
3327
3328 ~G1CodeCacheUnloadingTask() {
3329 CodeCache::verify_clean_inline_caches();
3330
3331 CodeCache::set_needs_cache_clean(false);
3332 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3333
3334 CodeCache::verify_icholder_relocations();
3335 }
3336
3337 private:
3338 void add_to_postponed_list(CompiledMethod* nm) {
3339 CompiledMethod* old;
3340 do {
3341 old = _postponed_list;
3342 nm->set_unloading_next(old);
3343 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3344 }
3345
3346 void clean_nmethod(CompiledMethod* nm) {
3347 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3348
3349 if (postponed) {
3350 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3351 add_to_postponed_list(nm);
3352 }
3353
3354 // Mark that this nmethod has been cleaned/unloaded.
3355 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3356 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3357 }
3358
3359 void clean_nmethod_postponed(CompiledMethod* nm) {
3360 nm->do_unloading_parallel_postponed();
3361 }
3362
3363 static const int MaxClaimNmethods = 16;
3364
3365 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3366 CompiledMethod* first;
3367 CompiledMethodIterator last;
3368
3369 do {
3370 *num_claimed_nmethods = 0;
3371
3372 first = _claimed_nmethod;
3373 last = CompiledMethodIterator(first);
3374
3375 if (first != NULL) {
3376
3377 for (int i = 0; i < MaxClaimNmethods; i++) {
3378 if (!last.next_alive()) {
3379 break;
3380 }
3381 claimed_nmethods[i] = last.method();
3382 (*num_claimed_nmethods)++;
3383 }
3384 }
3385
3386 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3387 }
3388
3389 CompiledMethod* claim_postponed_nmethod() {
3390 CompiledMethod* claim;
3391 CompiledMethod* next;
3392
3393 do {
3394 claim = _postponed_list;
3395 if (claim == NULL) {
3396 return NULL;
3397 }
3398
3399 next = claim->unloading_next();
3400
3401 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3402
3403 return claim;
3404 }
3405
3406 public:
3407 // Mark that we're done with the first pass of nmethod cleaning.
3408 void barrier_mark(uint worker_id) {
3409 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3410 _num_entered_barrier++;
3411 if (_num_entered_barrier == _num_workers) {
3412 ml.notify_all();
3413 }
3414 }
3415
3416 // See if we have to wait for the other workers to
3417 // finish their first-pass nmethod cleaning work.
3418 void barrier_wait(uint worker_id) {
3419 if (_num_entered_barrier < _num_workers) {
3420 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3421 while (_num_entered_barrier < _num_workers) {
3422 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3423 }
3424 }
3425 }
3426
3427 // Cleaning and unloading of nmethods. Some work has to be postponed
3428 // to the second pass, when we know which nmethods survive.
3429 void work_first_pass(uint worker_id) {
3430 // The first nmethods is claimed by the first worker.
3431 if (worker_id == 0 && _first_nmethod != NULL) {
3432 clean_nmethod(_first_nmethod);
3433 _first_nmethod = NULL;
3434 }
3435
3436 int num_claimed_nmethods;
3437 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3438
3439 while (true) {
3440 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3441
3442 if (num_claimed_nmethods == 0) {
3443 break;
3444 }
3445
3446 for (int i = 0; i < num_claimed_nmethods; i++) {
3447 clean_nmethod(claimed_nmethods[i]);
3448 }
3449 }
3450 }
3451
3452 void work_second_pass(uint worker_id) {
3453 CompiledMethod* nm;
3454 // Take care of postponed nmethods.
3455 while ((nm = claim_postponed_nmethod()) != NULL) {
3456 clean_nmethod_postponed(nm);
3457 }
3458 }
3459 };
3460
3461 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3462
3463 class G1KlassCleaningTask : public StackObj {
3464 volatile int _clean_klass_tree_claimed;
3465 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3466
3467 public:
3468 G1KlassCleaningTask() :
3469 _clean_klass_tree_claimed(0),
3470 _klass_iterator() {
3471 }
3472
3473 private:
3474 bool claim_clean_klass_tree_task() {
3475 if (_clean_klass_tree_claimed) {
3476 return false;
3477 }
3478
3479 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3480 }
3481
3482 InstanceKlass* claim_next_klass() {
3483 Klass* klass;
3484 do {
3485 klass =_klass_iterator.next_klass();
3486 } while (klass != NULL && !klass->is_instance_klass());
3487
3488 // this can be null so don't call InstanceKlass::cast
3489 return static_cast<InstanceKlass*>(klass);
3490 }
3491
3492 public:
3493
3494 void clean_klass(InstanceKlass* ik) {
3495 ik->clean_weak_instanceklass_links();
3496 }
3497
3498 void work() {
3499 ResourceMark rm;
3500
3501 // One worker will clean the subklass/sibling klass tree.
3502 if (claim_clean_klass_tree_task()) {
3503 Klass::clean_subklass_tree();
3504 }
3505
3506 // All workers will help cleaning the classes,
3507 InstanceKlass* klass;
3508 while ((klass = claim_next_klass()) != NULL) {
3509 clean_klass(klass);
3510 }
3511 }
3512 };
3513
3514 class G1ResolvedMethodCleaningTask : public StackObj {
3515 volatile int _resolved_method_task_claimed;
3516 public:
3517 G1ResolvedMethodCleaningTask() :
3518 _resolved_method_task_claimed(0) {}
3519
3520 bool claim_resolved_method_task() {
3521 if (_resolved_method_task_claimed) {
3522 return false;
3523 }
3524 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3525 }
3526
3527 // These aren't big, one thread can do it all.
3528 void work() {
3529 if (claim_resolved_method_task()) {
3530 ResolvedMethodTable::unlink();
3531 }
3532 }
3533 };
3534
3535
3536 // To minimize the remark pause times, the tasks below are done in parallel.
3537 class G1ParallelCleaningTask : public AbstractGangTask {
3538 private:
3539 bool _unloading_occurred;
3540 G1StringCleaningTask _string_task;
3541 G1CodeCacheUnloadingTask _code_cache_task;
3542 G1KlassCleaningTask _klass_cleaning_task;
3543 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3544
3545 public:
3546 // The constructor is run in the VMThread.
3547 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3548 AbstractGangTask("Parallel Cleaning"),
3549 _string_task(is_alive, true, G1StringDedup::is_enabled()),
3550 _code_cache_task(num_workers, is_alive, unloading_occurred),
3551 _klass_cleaning_task(),
3552 _unloading_occurred(unloading_occurred),
3553 _resolved_method_cleaning_task() {
3554 }
3555
3556 // The parallel work done by all worker threads.
3557 void work(uint worker_id) {
3558 // Do first pass of code cache cleaning.
3559 _code_cache_task.work_first_pass(worker_id);
3560
3561 // Let the threads mark that the first pass is done.
3562 _code_cache_task.barrier_mark(worker_id);
3563
3564 // Clean the Strings.
3565 _string_task.work(worker_id);
3566
3567 // Clean unreferenced things in the ResolvedMethodTable
3568 _resolved_method_cleaning_task.work();
3569
3570 // Wait for all workers to finish the first code cache cleaning pass.
3571 _code_cache_task.barrier_wait(worker_id);
3572
3573 // Do the second code cache cleaning work, which realize on
3574 // the liveness information gathered during the first pass.
3575 _code_cache_task.work_second_pass(worker_id);
3576
3577 // Clean all klasses that were not unloaded.
3578 // The weak metadata in klass doesn't need to be
3579 // processed if there was no unloading.
3580 if (_unloading_occurred) {
3581 _klass_cleaning_task.work();
3582 }
3583 }
3584 };
3585
3586
3587 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3588 bool class_unloading_occurred) {
3589 uint n_workers = workers()->active_workers();
3590
3591 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3592 workers()->run_task(&g1_unlink_task);
3593 }
3594
3595 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3596 bool process_strings,
3597 bool process_string_dedup) {
3598 if (!process_strings && !process_string_dedup) {
3599 // Nothing to clean.
3600 return;
3601 }
3602
3603 G1StringCleaningTask g1_unlink_task(is_alive, process_strings, process_string_dedup);
3604 workers()->run_task(&g1_unlink_task);
3605 }
3606
3607 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3608 private:
3609 DirtyCardQueueSet* _queue;
3610 G1CollectedHeap* _g1h;
3611 public:
3612 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3613 _queue(queue), _g1h(g1h) { }
3614
3615 virtual void work(uint worker_id) {
3616 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3617 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3618
3619 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3620 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3621
3622 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3623 }
3624 };
3625
3626 void G1CollectedHeap::redirty_logged_cards() {
3627 double redirty_logged_cards_start = os::elapsedTime();
3628
3629 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3630 dirty_card_queue_set().reset_for_par_iteration();
3631 workers()->run_task(&redirty_task);
3632
3633 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3634 dcq.merge_bufferlists(&dirty_card_queue_set());
3635 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3636
3637 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3638 }
3639
3640 // Weak Reference Processing support
3641
3642 bool G1STWIsAliveClosure::do_object_b(oop p) {
3643 // An object is reachable if it is outside the collection set,
3644 // or is inside and copied.
3645 return !_g1h->is_in_cset(p) || p->is_forwarded();
3646 }
3647
3648 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3649 assert(obj != NULL, "must not be NULL");
3650 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3651 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3652 // may falsely indicate that this is not the case here: however the collection set only
3653 // contains old regions when concurrent mark is not running.
3654 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3655 }
3656
3657 // Non Copying Keep Alive closure
3658 class G1KeepAliveClosure: public OopClosure {
3659 G1CollectedHeap*_g1h;
3660 public:
3661 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3662 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3663 void do_oop(oop* p) {
3664 oop obj = *p;
3665 assert(obj != NULL, "the caller should have filtered out NULL values");
3666
3667 const InCSetState cset_state =_g1h->in_cset_state(obj);
3668 if (!cset_state.is_in_cset_or_humongous()) {
3669 return;
3670 }
3671 if (cset_state.is_in_cset()) {
3672 assert( obj->is_forwarded(), "invariant" );
3673 *p = obj->forwardee();
3674 } else {
3675 assert(!obj->is_forwarded(), "invariant" );
3676 assert(cset_state.is_humongous(),
3677 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3678 _g1h->set_humongous_is_live(obj);
3679 }
3680 }
3681 };
3682
3683 // Copying Keep Alive closure - can be called from both
3684 // serial and parallel code as long as different worker
3685 // threads utilize different G1ParScanThreadState instances
3686 // and different queues.
3687
3688 class G1CopyingKeepAliveClosure: public OopClosure {
3689 G1CollectedHeap* _g1h;
3690 G1ParScanThreadState* _par_scan_state;
3691
3692 public:
3693 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3694 G1ParScanThreadState* pss):
3695 _g1h(g1h),
3696 _par_scan_state(pss)
3697 {}
3698
3699 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3700 virtual void do_oop( oop* p) { do_oop_work(p); }
3701
3702 template <class T> void do_oop_work(T* p) {
3703 oop obj = RawAccess<>::oop_load(p);
3704
3705 if (_g1h->is_in_cset_or_humongous(obj)) {
3706 // If the referent object has been forwarded (either copied
3707 // to a new location or to itself in the event of an
3708 // evacuation failure) then we need to update the reference
3709 // field and, if both reference and referent are in the G1
3710 // heap, update the RSet for the referent.
3711 //
3712 // If the referent has not been forwarded then we have to keep
3713 // it alive by policy. Therefore we have copy the referent.
3714 //
3715 // When the queue is drained (after each phase of reference processing)
3716 // the object and it's followers will be copied, the reference field set
3717 // to point to the new location, and the RSet updated.
3718 _par_scan_state->push_on_queue(p);
3719 }
3720 }
3721 };
3722
3723 // Serial drain queue closure. Called as the 'complete_gc'
3724 // closure for each discovered list in some of the
3725 // reference processing phases.
3726
3727 class G1STWDrainQueueClosure: public VoidClosure {
3728 protected:
3729 G1CollectedHeap* _g1h;
3730 G1ParScanThreadState* _par_scan_state;
3731
3732 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3733
3734 public:
3735 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3736 _g1h(g1h),
3737 _par_scan_state(pss)
3738 { }
3739
3740 void do_void() {
3741 G1ParScanThreadState* const pss = par_scan_state();
3742 pss->trim_queue();
3743 }
3744 };
3745
3746 // Parallel Reference Processing closures
3747
3748 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3749 // processing during G1 evacuation pauses.
3750
3751 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3752 private:
3753 G1CollectedHeap* _g1h;
3754 G1ParScanThreadStateSet* _pss;
3755 RefToScanQueueSet* _queues;
3756 WorkGang* _workers;
3757
3758 public:
3759 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3760 G1ParScanThreadStateSet* per_thread_states,
3761 WorkGang* workers,
3762 RefToScanQueueSet *task_queues) :
3763 _g1h(g1h),
3764 _pss(per_thread_states),
3765 _queues(task_queues),
3766 _workers(workers)
3767 {
3768 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3769 }
3770
3771 // Executes the given task using concurrent marking worker threads.
3772 virtual void execute(ProcessTask& task, uint ergo_workers);
3773 };
3774
3775 // Gang task for possibly parallel reference processing
3776
3777 class G1STWRefProcTaskProxy: public AbstractGangTask {
3778 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3779 ProcessTask& _proc_task;
3780 G1CollectedHeap* _g1h;
3781 G1ParScanThreadStateSet* _pss;
3782 RefToScanQueueSet* _task_queues;
3783 ParallelTaskTerminator* _terminator;
3784
3785 public:
3786 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3787 G1CollectedHeap* g1h,
3788 G1ParScanThreadStateSet* per_thread_states,
3789 RefToScanQueueSet *task_queues,
3790 ParallelTaskTerminator* terminator) :
3791 AbstractGangTask("Process reference objects in parallel"),
3792 _proc_task(proc_task),
3793 _g1h(g1h),
3794 _pss(per_thread_states),
3795 _task_queues(task_queues),
3796 _terminator(terminator)
3797 {}
3798
3799 virtual void work(uint worker_id) {
3800 // The reference processing task executed by a single worker.
3801 ResourceMark rm;
3802 HandleMark hm;
3803
3804 G1STWIsAliveClosure is_alive(_g1h);
3805
3806 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3807 pss->set_ref_discoverer(NULL);
3808
3809 // Keep alive closure.
3810 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3811
3812 // Complete GC closure
3813 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3814
3815 // Call the reference processing task's work routine.
3816 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3817
3818 // Note we cannot assert that the refs array is empty here as not all
3819 // of the processing tasks (specifically phase2 - pp2_work) execute
3820 // the complete_gc closure (which ordinarily would drain the queue) so
3821 // the queue may not be empty.
3822 }
3823 };
3824
3825 // Driver routine for parallel reference processing.
3826 // Creates an instance of the ref processing gang
3827 // task and has the worker threads execute it.
3828 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3829 assert(_workers != NULL, "Need parallel worker threads.");
3830
3831 assert(_workers->active_workers() >= ergo_workers,
3832 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3833 ergo_workers, _workers->active_workers());
3834 ParallelTaskTerminator terminator(ergo_workers, _queues);
3835 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3836
3837 _workers->run_task(&proc_task_proxy, ergo_workers);
3838 }
3839
3840 // End of weak reference support closures
3841
3842 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3843 double ref_proc_start = os::elapsedTime();
3844
3845 ReferenceProcessor* rp = _ref_processor_stw;
3846 assert(rp->discovery_enabled(), "should have been enabled");
3847
3848 // Closure to test whether a referent is alive.
3849 G1STWIsAliveClosure is_alive(this);
3850
3851 // Even when parallel reference processing is enabled, the processing
3852 // of JNI refs is serial and performed serially by the current thread
3853 // rather than by a worker. The following PSS will be used for processing
3854 // JNI refs.
3855
3856 // Use only a single queue for this PSS.
3857 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3858 pss->set_ref_discoverer(NULL);
3859 assert(pss->queue_is_empty(), "pre-condition");
3860
3861 // Keep alive closure.
3862 G1CopyingKeepAliveClosure keep_alive(this, pss);
3863
3864 // Serial Complete GC closure
3865 G1STWDrainQueueClosure drain_queue(this, pss);
3866
3867 // Setup the soft refs policy...
3868 rp->setup_policy(false);
3869
3870 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3871
3872 ReferenceProcessorStats stats;
3873 if (!rp->processing_is_mt()) {
3874 // Serial reference processing...
3875 stats = rp->process_discovered_references(&is_alive,
3876 &keep_alive,
3877 &drain_queue,
3878 NULL,
3879 pt);
3880 } else {
3881 uint no_of_gc_workers = workers()->active_workers();
3882
3883 // Parallel reference processing
3884 assert(no_of_gc_workers <= rp->max_num_queues(),
3885 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3886 no_of_gc_workers, rp->max_num_queues());
3887
3888 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3889 stats = rp->process_discovered_references(&is_alive,
3890 &keep_alive,
3891 &drain_queue,
3892 &par_task_executor,
3893 pt);
3894 }
3895
3896 _gc_tracer_stw->report_gc_reference_stats(stats);
3897
3898 // We have completed copying any necessary live referent objects.
3899 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3900
3901 make_pending_list_reachable();
3902
3903 rp->verify_no_references_recorded();
3904
3905 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3906 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3907 }
3908
3909 void G1CollectedHeap::make_pending_list_reachable() {
3910 if (collector_state()->in_initial_mark_gc()) {
3911 oop pll_head = Universe::reference_pending_list();
3912 if (pll_head != NULL) {
3913 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3914 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3915 }
3916 }
3917 }
3918
3919 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3920 double merge_pss_time_start = os::elapsedTime();
3921 per_thread_states->flush();
3922 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3923 }
3924
3925 void G1CollectedHeap::pre_evacuate_collection_set() {
3926 _expand_heap_after_alloc_failure = true;
3927 _evacuation_failed = false;
3928
3929 // Disable the hot card cache.
3930 _hot_card_cache->reset_hot_cache_claimed_index();
3931 _hot_card_cache->set_use_cache(false);
3932
3933 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3934 _preserved_marks_set.assert_empty();
3935
3936 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3937
3938 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3939 if (collector_state()->in_initial_mark_gc()) {
3940 double start_clear_claimed_marks = os::elapsedTime();
3941
3942 ClassLoaderDataGraph::clear_claimed_marks();
3943
3944 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3945 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3946 }
3947 }
3948
3949 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3950 // Should G1EvacuationFailureALot be in effect for this GC?
3951 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3952
3953 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3954
3955 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3956
3957 double start_par_time_sec = os::elapsedTime();
3958 double end_par_time_sec;
3959
3960 {
3961 const uint n_workers = workers()->active_workers();
3962 G1RootProcessor root_processor(this, n_workers);
3963 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3964
3965 print_termination_stats_hdr();
3966
3967 workers()->run_task(&g1_par_task);
3968 end_par_time_sec = os::elapsedTime();
3969
3970 // Closing the inner scope will execute the destructor
3971 // for the G1RootProcessor object. We record the current
3972 // elapsed time before closing the scope so that time
3973 // taken for the destructor is NOT included in the
3974 // reported parallel time.
3975 }
3976
3977 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3978 phase_times->record_par_time(par_time_ms);
3979
3980 double code_root_fixup_time_ms =
3981 (os::elapsedTime() - end_par_time_sec) * 1000.0;
3982 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3983 }
3984
3985 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3986 // Also cleans the card table from temporary duplicate detection information used
3987 // during UpdateRS/ScanRS.
3988 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3989
3990 // Process any discovered reference objects - we have
3991 // to do this _before_ we retire the GC alloc regions
3992 // as we may have to copy some 'reachable' referent
3993 // objects (and their reachable sub-graphs) that were
3994 // not copied during the pause.
3995 process_discovered_references(per_thread_states);
3996
3997 // FIXME
3998 // CM's reference processing also cleans up the string table.
3999 // Should we do that here also? We could, but it is a serial operation
4000 // and could significantly increase the pause time.
4001
4002 G1STWIsAliveClosure is_alive(this);
4003 G1KeepAliveClosure keep_alive(this);
4004
4005 {
4006 double start = os::elapsedTime();
4007
4008 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4009
4010 double time_ms = (os::elapsedTime() - start) * 1000.0;
4011 g1_policy()->phase_times()->record_weak_ref_proc_time(time_ms);
4012 }
4013
4014 if (G1StringDedup::is_enabled()) {
4015 double fixup_start = os::elapsedTime();
4016
4017 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4018
4019 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4020 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4021 }
4022
4023 if (evacuation_failed()) {
4024 restore_after_evac_failure();
4025
4026 // Reset the G1EvacuationFailureALot counters and flags
4027 // Note: the values are reset only when an actual
4028 // evacuation failure occurs.
4029 NOT_PRODUCT(reset_evacuation_should_fail();)
4030 }
4031
4032 _preserved_marks_set.assert_empty();
4033
4034 _allocator->release_gc_alloc_regions(evacuation_info);
4035
4036 merge_per_thread_state_info(per_thread_states);
4037
4038 // Reset and re-enable the hot card cache.
4039 // Note the counts for the cards in the regions in the
4040 // collection set are reset when the collection set is freed.
4041 _hot_card_cache->reset_hot_cache();
4042 _hot_card_cache->set_use_cache(true);
4043
4044 purge_code_root_memory();
4045
4046 redirty_logged_cards();
4047 #if COMPILER2_OR_JVMCI
4048 double start = os::elapsedTime();
4049 DerivedPointerTable::update_pointers();
4050 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4051 #endif
4052 g1_policy()->print_age_table();
4053 }
4054
4055 void G1CollectedHeap::record_obj_copy_mem_stats() {
4056 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4057
4058 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4059 create_g1_evac_summary(&_old_evac_stats));
4060 }
4061
4062 void G1CollectedHeap::free_region(HeapRegion* hr,
4063 FreeRegionList* free_list,
4064 bool skip_remset,
4065 bool skip_hot_card_cache,
4066 bool locked) {
4067 assert(!hr->is_free(), "the region should not be free");
4068 assert(!hr->is_empty(), "the region should not be empty");
4069 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4070 assert(free_list != NULL, "pre-condition");
4071
4072 if (G1VerifyBitmaps) {
4073 MemRegion mr(hr->bottom(), hr->end());
4074 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4075 }
4076
4077 // Clear the card counts for this region.
4078 // Note: we only need to do this if the region is not young
4079 // (since we don't refine cards in young regions).
4080 if (!skip_hot_card_cache && !hr->is_young()) {
4081 _hot_card_cache->reset_card_counts(hr);
4082 }
4083 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4084 _g1_policy->remset_tracker()->update_at_free(hr);
4085 free_list->add_ordered(hr);
4086 }
4087
4088 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4089 FreeRegionList* free_list) {
4090 assert(hr->is_humongous(), "this is only for humongous regions");
4091 assert(free_list != NULL, "pre-condition");
4092 hr->clear_humongous();
4093 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4094 }
4095
4096 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4097 const uint humongous_regions_removed) {
4098 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4099 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4100 _old_set.bulk_remove(old_regions_removed);
4101 _humongous_set.bulk_remove(humongous_regions_removed);
4102 }
4103
4104 }
4105
4106 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4107 assert(list != NULL, "list can't be null");
4108 if (!list->is_empty()) {
4109 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4110 _hrm.insert_list_into_free_list(list);
4111 }
4112 }
4113
4114 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4115 decrease_used(bytes);
4116 }
4117
4118 class G1FreeCollectionSetTask : public AbstractGangTask {
4119 private:
4120
4121 // Closure applied to all regions in the collection set to do work that needs to
4122 // be done serially in a single thread.
4123 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4124 private:
4125 EvacuationInfo* _evacuation_info;
4126 const size_t* _surviving_young_words;
4127
4128 // Bytes used in successfully evacuated regions before the evacuation.
4129 size_t _before_used_bytes;
4130 // Bytes used in unsucessfully evacuated regions before the evacuation
4131 size_t _after_used_bytes;
4132
4133 size_t _bytes_allocated_in_old_since_last_gc;
4134
4135 size_t _failure_used_words;
4136 size_t _failure_waste_words;
4137
4138 FreeRegionList _local_free_list;
4139 public:
4140 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4141 HeapRegionClosure(),
4142 _evacuation_info(evacuation_info),
4143 _surviving_young_words(surviving_young_words),
4144 _before_used_bytes(0),
4145 _after_used_bytes(0),
4146 _bytes_allocated_in_old_since_last_gc(0),
4147 _failure_used_words(0),
4148 _failure_waste_words(0),
4149 _local_free_list("Local Region List for CSet Freeing") {
4150 }
4151
4152 virtual bool do_heap_region(HeapRegion* r) {
4153 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4154
4155 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4156 g1h->clear_in_cset(r);
4157
4158 if (r->is_young()) {
4159 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4160 "Young index %d is wrong for region %u of type %s with %u young regions",
4161 r->young_index_in_cset(),
4162 r->hrm_index(),
4163 r->get_type_str(),
4164 g1h->collection_set()->young_region_length());
4165 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4166 r->record_surv_words_in_group(words_survived);
4167 }
4168
4169 if (!r->evacuation_failed()) {
4170 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4171 _before_used_bytes += r->used();
4172 g1h->free_region(r,
4173 &_local_free_list,
4174 true, /* skip_remset */
4175 true, /* skip_hot_card_cache */
4176 true /* locked */);
4177 } else {
4178 r->uninstall_surv_rate_group();
4179 r->set_young_index_in_cset(-1);
4180 r->set_evacuation_failed(false);
4181 // When moving a young gen region to old gen, we "allocate" that whole region
4182 // there. This is in addition to any already evacuated objects. Notify the
4183 // policy about that.
4184 // Old gen regions do not cause an additional allocation: both the objects
4185 // still in the region and the ones already moved are accounted for elsewhere.
4186 if (r->is_young()) {
4187 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4188 }
4189 // The region is now considered to be old.
4190 r->set_old();
4191 // Do some allocation statistics accounting. Regions that failed evacuation
4192 // are always made old, so there is no need to update anything in the young
4193 // gen statistics, but we need to update old gen statistics.
4194 size_t used_words = r->marked_bytes() / HeapWordSize;
4195
4196 _failure_used_words += used_words;
4197 _failure_waste_words += HeapRegion::GrainWords - used_words;
4198
4199 g1h->old_set_add(r);
4200 _after_used_bytes += r->used();
4201 }
4202 return false;
4203 }
4204
4205 void complete_work() {
4206 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4207
4208 _evacuation_info->set_regions_freed(_local_free_list.length());
4209 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4210
4211 g1h->prepend_to_freelist(&_local_free_list);
4212 g1h->decrement_summary_bytes(_before_used_bytes);
4213
4214 G1Policy* policy = g1h->g1_policy();
4215 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4216
4217 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4218 }
4219 };
4220
4221 G1CollectionSet* _collection_set;
4222 G1SerialFreeCollectionSetClosure _cl;
4223 const size_t* _surviving_young_words;
4224
4225 size_t _rs_lengths;
4226
4227 volatile jint _serial_work_claim;
4228
4229 struct WorkItem {
4230 uint region_idx;
4231 bool is_young;
4232 bool evacuation_failed;
4233
4234 WorkItem(HeapRegion* r) {
4235 region_idx = r->hrm_index();
4236 is_young = r->is_young();
4237 evacuation_failed = r->evacuation_failed();
4238 }
4239 };
4240
4241 volatile size_t _parallel_work_claim;
4242 size_t _num_work_items;
4243 WorkItem* _work_items;
4244
4245 void do_serial_work() {
4246 // Need to grab the lock to be allowed to modify the old region list.
4247 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4248 _collection_set->iterate(&_cl);
4249 }
4250
4251 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4252 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4253
4254 HeapRegion* r = g1h->region_at(region_idx);
4255 assert(!g1h->is_on_master_free_list(r), "sanity");
4256
4257 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4258
4259 if (!is_young) {
4260 g1h->_hot_card_cache->reset_card_counts(r);
4261 }
4262
4263 if (!evacuation_failed) {
4264 r->rem_set()->clear_locked();
4265 }
4266 }
4267
4268 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4269 private:
4270 size_t _cur_idx;
4271 WorkItem* _work_items;
4272 public:
4273 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4274
4275 virtual bool do_heap_region(HeapRegion* r) {
4276 _work_items[_cur_idx++] = WorkItem(r);
4277 return false;
4278 }
4279 };
4280
4281 void prepare_work() {
4282 G1PrepareFreeCollectionSetClosure cl(_work_items);
4283 _collection_set->iterate(&cl);
4284 }
4285
4286 void complete_work() {
4287 _cl.complete_work();
4288
4289 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4290 policy->record_max_rs_lengths(_rs_lengths);
4291 policy->cset_regions_freed();
4292 }
4293 public:
4294 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4295 AbstractGangTask("G1 Free Collection Set"),
4296 _cl(evacuation_info, surviving_young_words),
4297 _collection_set(collection_set),
4298 _surviving_young_words(surviving_young_words),
4299 _serial_work_claim(0),
4300 _rs_lengths(0),
4301 _parallel_work_claim(0),
4302 _num_work_items(collection_set->region_length()),
4303 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4304 prepare_work();
4305 }
4306
4307 ~G1FreeCollectionSetTask() {
4308 complete_work();
4309 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4310 }
4311
4312 // Chunk size for work distribution. The chosen value has been determined experimentally
4313 // to be a good tradeoff between overhead and achievable parallelism.
4314 static uint chunk_size() { return 32; }
4315
4316 virtual void work(uint worker_id) {
4317 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4318
4319 // Claim serial work.
4320 if (_serial_work_claim == 0) {
4321 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4322 if (value == 0) {
4323 double serial_time = os::elapsedTime();
4324 do_serial_work();
4325 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4326 }
4327 }
4328
4329 // Start parallel work.
4330 double young_time = 0.0;
4331 bool has_young_time = false;
4332 double non_young_time = 0.0;
4333 bool has_non_young_time = false;
4334
4335 while (true) {
4336 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4337 size_t cur = end - chunk_size();
4338
4339 if (cur >= _num_work_items) {
4340 break;
4341 }
4342
4343 double start_time = os::elapsedTime();
4344
4345 end = MIN2(end, _num_work_items);
4346
4347 for (; cur < end; cur++) {
4348 bool is_young = _work_items[cur].is_young;
4349
4350 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4351
4352 double end_time = os::elapsedTime();
4353 double time_taken = end_time - start_time;
4354 if (is_young) {
4355 young_time += time_taken;
4356 has_young_time = true;
4357 } else {
4358 non_young_time += time_taken;
4359 has_non_young_time = true;
4360 }
4361 start_time = end_time;
4362 }
4363 }
4364
4365 if (has_young_time) {
4366 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4367 }
4368 if (has_non_young_time) {
4369 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4370 }
4371 }
4372 };
4373
4374 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4375 _eden.clear();
4376
4377 double free_cset_start_time = os::elapsedTime();
4378
4379 {
4380 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4381 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4382
4383 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4384
4385 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4386 cl.name(),
4387 num_workers,
4388 _collection_set.region_length());
4389 workers()->run_task(&cl, num_workers);
4390 }
4391 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4392
4393 collection_set->clear();
4394 }
4395
4396 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4397 private:
4398 FreeRegionList* _free_region_list;
4399 HeapRegionSet* _proxy_set;
4400 uint _humongous_objects_reclaimed;
4401 uint _humongous_regions_reclaimed;
4402 size_t _freed_bytes;
4403 public:
4404
4405 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4406 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4407 }
4408
4409 virtual bool do_heap_region(HeapRegion* r) {
4410 if (!r->is_starts_humongous()) {
4411 return false;
4412 }
4413
4414 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4415
4416 oop obj = (oop)r->bottom();
4417 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4418
4419 // The following checks whether the humongous object is live are sufficient.
4420 // The main additional check (in addition to having a reference from the roots
4421 // or the young gen) is whether the humongous object has a remembered set entry.
4422 //
4423 // A humongous object cannot be live if there is no remembered set for it
4424 // because:
4425 // - there can be no references from within humongous starts regions referencing
4426 // the object because we never allocate other objects into them.
4427 // (I.e. there are no intra-region references that may be missed by the
4428 // remembered set)
4429 // - as soon there is a remembered set entry to the humongous starts region
4430 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4431 // until the end of a concurrent mark.
4432 //
4433 // It is not required to check whether the object has been found dead by marking
4434 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4435 // all objects allocated during that time are considered live.
4436 // SATB marking is even more conservative than the remembered set.
4437 // So if at this point in the collection there is no remembered set entry,
4438 // nobody has a reference to it.
4439 // At the start of collection we flush all refinement logs, and remembered sets
4440 // are completely up-to-date wrt to references to the humongous object.
4441 //
4442 // Other implementation considerations:
4443 // - never consider object arrays at this time because they would pose
4444 // considerable effort for cleaning up the the remembered sets. This is
4445 // required because stale remembered sets might reference locations that
4446 // are currently allocated into.
4447 uint region_idx = r->hrm_index();
4448 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4449 !r->rem_set()->is_empty()) {
4450 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",
4451 region_idx,
4452 (size_t)obj->size() * HeapWordSize,
4453 p2i(r->bottom()),
4454 r->rem_set()->occupied(),
4455 r->rem_set()->strong_code_roots_list_length(),
4456 next_bitmap->is_marked(r->bottom()),
4457 g1h->is_humongous_reclaim_candidate(region_idx),
4458 obj->is_typeArray()
4459 );
4460 return false;
4461 }
4462
4463 guarantee(obj->is_typeArray(),
4464 "Only eagerly reclaiming type arrays is supported, but the object "
4465 PTR_FORMAT " is not.", p2i(r->bottom()));
4466
4467 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",
4468 region_idx,
4469 (size_t)obj->size() * HeapWordSize,
4470 p2i(r->bottom()),
4471 r->rem_set()->occupied(),
4472 r->rem_set()->strong_code_roots_list_length(),
4473 next_bitmap->is_marked(r->bottom()),
4474 g1h->is_humongous_reclaim_candidate(region_idx),
4475 obj->is_typeArray()
4476 );
4477
4478 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4479 cm->humongous_object_eagerly_reclaimed(r);
4480 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4481 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4482 region_idx,
4483 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4484 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4485 _humongous_objects_reclaimed++;
4486 do {
4487 HeapRegion* next = g1h->next_region_in_humongous(r);
4488 _freed_bytes += r->used();
4489 r->set_containing_set(NULL);
4490 _humongous_regions_reclaimed++;
4491 g1h->free_humongous_region(r, _free_region_list);
4492 r = next;
4493 } while (r != NULL);
4494
4495 return false;
4496 }
4497
4498 uint humongous_objects_reclaimed() {
4499 return _humongous_objects_reclaimed;
4500 }
4501
4502 uint humongous_regions_reclaimed() {
4503 return _humongous_regions_reclaimed;
4504 }
4505
4506 size_t bytes_freed() const {
4507 return _freed_bytes;
4508 }
4509 };
4510
4511 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4512 assert_at_safepoint_on_vm_thread();
4513
4514 if (!G1EagerReclaimHumongousObjects ||
4515 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4516 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4517 return;
4518 }
4519
4520 double start_time = os::elapsedTime();
4521
4522 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4523
4524 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4525 heap_region_iterate(&cl);
4526
4527 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4528
4529 G1HRPrinter* hrp = hr_printer();
4530 if (hrp->is_active()) {
4531 FreeRegionListIterator iter(&local_cleanup_list);
4532 while (iter.more_available()) {
4533 HeapRegion* hr = iter.get_next();
4534 hrp->cleanup(hr);
4535 }
4536 }
4537
4538 prepend_to_freelist(&local_cleanup_list);
4539 decrement_summary_bytes(cl.bytes_freed());
4540
4541 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4542 cl.humongous_objects_reclaimed());
4543 }
4544
4545 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4546 public:
4547 virtual bool do_heap_region(HeapRegion* r) {
4548 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4549 G1CollectedHeap::heap()->clear_in_cset(r);
4550 r->set_young_index_in_cset(-1);
4551 return false;
4552 }
4553 };
4554
4555 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4556 G1AbandonCollectionSetClosure cl;
4557 collection_set->iterate(&cl);
4558
4559 collection_set->clear();
4560 collection_set->stop_incremental_building();
4561 }
4562
4563 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4564 return _allocator->is_retained_old_region(hr);
4565 }
4566
4567 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4568 _eden.add(hr);
4569 _g1_policy->set_region_eden(hr);
4570 }
4571
4572 #ifdef ASSERT
4573
4574 class NoYoungRegionsClosure: public HeapRegionClosure {
4575 private:
4576 bool _success;
4577 public:
4578 NoYoungRegionsClosure() : _success(true) { }
4579 bool do_heap_region(HeapRegion* r) {
4580 if (r->is_young()) {
4581 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4582 p2i(r->bottom()), p2i(r->end()));
4583 _success = false;
4584 }
4585 return false;
4586 }
4587 bool success() { return _success; }
4588 };
4589
4590 bool G1CollectedHeap::check_young_list_empty() {
4591 bool ret = (young_regions_count() == 0);
4592
4593 NoYoungRegionsClosure closure;
4594 heap_region_iterate(&closure);
4595 ret = ret && closure.success();
4596
4597 return ret;
4598 }
4599
4600 #endif // ASSERT
4601
4602 class TearDownRegionSetsClosure : public HeapRegionClosure {
4603 private:
4604 HeapRegionSet *_old_set;
4605
4606 public:
4607 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4608
4609 bool do_heap_region(HeapRegion* r) {
4610 if (r->is_old()) {
4611 _old_set->remove(r);
4612 } else if(r->is_young()) {
4613 r->uninstall_surv_rate_group();
4614 } else {
4615 // We ignore free regions, we'll empty the free list afterwards.
4616 // We ignore humongous regions, we're not tearing down the
4617 // humongous regions set.
4618 assert(r->is_free() || r->is_humongous(),
4619 "it cannot be another type");
4620 }
4621 return false;
4622 }
4623
4624 ~TearDownRegionSetsClosure() {
4625 assert(_old_set->is_empty(), "post-condition");
4626 }
4627 };
4628
4629 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4630 assert_at_safepoint_on_vm_thread();
4631
4632 if (!free_list_only) {
4633 TearDownRegionSetsClosure cl(&_old_set);
4634 heap_region_iterate(&cl);
4635
4636 // Note that emptying the _young_list is postponed and instead done as
4637 // the first step when rebuilding the regions sets again. The reason for
4638 // this is that during a full GC string deduplication needs to know if
4639 // a collected region was young or old when the full GC was initiated.
4640 }
4641 _hrm.remove_all_free_regions();
4642 }
4643
4644 void G1CollectedHeap::increase_used(size_t bytes) {
4645 _summary_bytes_used += bytes;
4646 }
4647
4648 void G1CollectedHeap::decrease_used(size_t bytes) {
4649 assert(_summary_bytes_used >= bytes,
4650 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4651 _summary_bytes_used, bytes);
4652 _summary_bytes_used -= bytes;
4653 }
4654
4655 void G1CollectedHeap::set_used(size_t bytes) {
4656 _summary_bytes_used = bytes;
4657 }
4658
4659 class RebuildRegionSetsClosure : public HeapRegionClosure {
4660 private:
4661 bool _free_list_only;
4662 HeapRegionSet* _old_set;
4663 HeapRegionManager* _hrm;
4664 size_t _total_used;
4665
4666 public:
4667 RebuildRegionSetsClosure(bool free_list_only,
4668 HeapRegionSet* old_set, HeapRegionManager* hrm) :
4669 _free_list_only(free_list_only),
4670 _old_set(old_set), _hrm(hrm), _total_used(0) {
4671 assert(_hrm->num_free_regions() == 0, "pre-condition");
4672 if (!free_list_only) {
4673 assert(_old_set->is_empty(), "pre-condition");
4674 }
4675 }
4676
4677 bool do_heap_region(HeapRegion* r) {
4678 // After full GC, no region should have a remembered set.
4679 r->rem_set()->clear(true);
4680 if (r->is_empty()) {
4681 // Add free regions to the free list
4682 r->set_free();
4683 _hrm->insert_into_free_list(r);
4684 } else if (!_free_list_only) {
4685
4686 if (r->is_humongous()) {
4687 // We ignore humongous regions. We left the humongous set unchanged.
4688 } else {
4689 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4690 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
4691 r->move_to_old();
4692 _old_set->add(r);
4693 }
4694 _total_used += r->used();
4695 }
4696
4697 return false;
4698 }
4699
4700 size_t total_used() {
4701 return _total_used;
4702 }
4703 };
4704
4705 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4706 assert_at_safepoint_on_vm_thread();
4707
4708 if (!free_list_only) {
4709 _eden.clear();
4710 _survivor.clear();
4711 }
4712
4713 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4714 heap_region_iterate(&cl);
4715
4716 if (!free_list_only) {
4717 set_used(cl.total_used());
4718 if (_archive_allocator != NULL) {
4719 _archive_allocator->clear_used();
4720 }
4721 }
4722 assert(used_unlocked() == recalculate_used(),
4723 "inconsistent used_unlocked(), "
4724 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4725 used_unlocked(), recalculate_used());
4726 }
4727
4728 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4729 HeapRegion* hr = heap_region_containing(p);
4730 return hr->is_in(p);
4731 }
4732
4733 // Methods for the mutator alloc region
4734
4735 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4736 bool force) {
4737 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4738 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4739 if (force || should_allocate) {
4740 HeapRegion* new_alloc_region = new_region(word_size,
4741 false /* is_old */,
4742 false /* do_expand */);
4743 if (new_alloc_region != NULL) {
4744 set_region_short_lived_locked(new_alloc_region);
4745 _hr_printer.alloc(new_alloc_region, !should_allocate);
4746 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4747 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4748 return new_alloc_region;
4749 }
4750 }
4751 return NULL;
4752 }
4753
4754 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4755 size_t allocated_bytes) {
4756 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4757 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4758
4759 collection_set()->add_eden_region(alloc_region);
4760 increase_used(allocated_bytes);
4761 _hr_printer.retire(alloc_region);
4762 // We update the eden sizes here, when the region is retired,
4763 // instead of when it's allocated, since this is the point that its
4764 // used space has been recored in _summary_bytes_used.
4765 g1mm()->update_eden_size();
4766 }
4767
4768 // Methods for the GC alloc regions
4769
4770 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4771 if (dest.is_old()) {
4772 return true;
4773 } else {
4774 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4775 }
4776 }
4777
4778 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4779 assert(FreeList_lock->owned_by_self(), "pre-condition");
4780
4781 if (!has_more_regions(dest)) {
4782 return NULL;
4783 }
4784
4785 const bool is_survivor = dest.is_young();
4786
4787 HeapRegion* new_alloc_region = new_region(word_size,
4788 !is_survivor,
4789 true /* do_expand */);
4790 if (new_alloc_region != NULL) {
4791 if (is_survivor) {
4792 new_alloc_region->set_survivor();
4793 _survivor.add(new_alloc_region);
4794 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4795 } else {
4796 new_alloc_region->set_old();
4797 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4798 }
4799 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4800 _hr_printer.alloc(new_alloc_region);
4801 bool during_im = collector_state()->in_initial_mark_gc();
4802 new_alloc_region->note_start_of_copying(during_im);
4803 return new_alloc_region;
4804 }
4805 return NULL;
4806 }
4807
4808 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4809 size_t allocated_bytes,
4810 InCSetState dest) {
4811 bool during_im = collector_state()->in_initial_mark_gc();
4812 alloc_region->note_end_of_copying(during_im);
4813 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4814 if (dest.is_old()) {
4815 _old_set.add(alloc_region);
4816 }
4817 _hr_printer.retire(alloc_region);
4818 }
4819
4820 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4821 bool expanded = false;
4822 uint index = _hrm.find_highest_free(&expanded);
4823
4824 if (index != G1_NO_HRM_INDEX) {
4825 if (expanded) {
4826 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4827 HeapRegion::GrainWords * HeapWordSize);
4828 }
4829 _hrm.allocate_free_regions_starting_at(index, 1);
4830 return region_at(index);
4831 }
4832 return NULL;
4833 }
4834
4835 // Optimized nmethod scanning
4836
4837 class RegisterNMethodOopClosure: public OopClosure {
4838 G1CollectedHeap* _g1h;
4839 nmethod* _nm;
4840
4841 template <class T> void do_oop_work(T* p) {
4842 T heap_oop = RawAccess<>::oop_load(p);
4843 if (!CompressedOops::is_null(heap_oop)) {
4844 oop obj = CompressedOops::decode_not_null(heap_oop);
4845 HeapRegion* hr = _g1h->heap_region_containing(obj);
4846 assert(!hr->is_continues_humongous(),
4847 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4848 " starting at " HR_FORMAT,
4849 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4850
4851 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4852 hr->add_strong_code_root_locked(_nm);
4853 }
4854 }
4855
4856 public:
4857 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4858 _g1h(g1h), _nm(nm) {}
4859
4860 void do_oop(oop* p) { do_oop_work(p); }
4861 void do_oop(narrowOop* p) { do_oop_work(p); }
4862 };
4863
4864 class UnregisterNMethodOopClosure: public OopClosure {
4865 G1CollectedHeap* _g1h;
4866 nmethod* _nm;
4867
4868 template <class T> void do_oop_work(T* p) {
4869 T heap_oop = RawAccess<>::oop_load(p);
4870 if (!CompressedOops::is_null(heap_oop)) {
4871 oop obj = CompressedOops::decode_not_null(heap_oop);
4872 HeapRegion* hr = _g1h->heap_region_containing(obj);
4873 assert(!hr->is_continues_humongous(),
4874 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4875 " starting at " HR_FORMAT,
4876 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4877
4878 hr->remove_strong_code_root(_nm);
4879 }
4880 }
4881
4882 public:
4883 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4884 _g1h(g1h), _nm(nm) {}
4885
4886 void do_oop(oop* p) { do_oop_work(p); }
4887 void do_oop(narrowOop* p) { do_oop_work(p); }
4888 };
4889
4890 // Returns true if the reference points to an object that
4891 // can move in an incremental collection.
4892 bool G1CollectedHeap::is_scavengable(oop obj) {
4893 HeapRegion* hr = heap_region_containing(obj);
4894 return !hr->is_pinned();
4895 }
4896
4897 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4898 guarantee(nm != NULL, "sanity");
4899 RegisterNMethodOopClosure reg_cl(this, nm);
4900 nm->oops_do(®_cl);
4901 }
4902
4903 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4904 guarantee(nm != NULL, "sanity");
4905 UnregisterNMethodOopClosure reg_cl(this, nm);
4906 nm->oops_do(®_cl, true);
4907 }
4908
4909 void G1CollectedHeap::purge_code_root_memory() {
4910 double purge_start = os::elapsedTime();
4911 G1CodeRootSet::purge();
4912 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4913 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4914 }
4915
4916 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4917 G1CollectedHeap* _g1h;
4918
4919 public:
4920 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4921 _g1h(g1h) {}
4922
4923 void do_code_blob(CodeBlob* cb) {
4924 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4925 if (nm == NULL) {
4926 return;
4927 }
4928
4929 if (ScavengeRootsInCode) {
4930 _g1h->register_nmethod(nm);
4931 }
4932 }
4933 };
4934
4935 void G1CollectedHeap::rebuild_strong_code_roots() {
4936 RebuildStrongCodeRootClosure blob_cl(this);
4937 CodeCache::blobs_do(&blob_cl);
4938 }
4939
4940 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4941 GrowableArray<GCMemoryManager*> memory_managers(2);
4942 memory_managers.append(&_memory_manager);
4943 memory_managers.append(&_full_gc_memory_manager);
4944 return memory_managers;
4945 }
4946
4947 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4948 GrowableArray<MemoryPool*> memory_pools(3);
4949 memory_pools.append(_eden_pool);
4950 memory_pools.append(_survivor_pool);
4951 memory_pools.append(_old_pool);
4952 return memory_pools;
4953 }