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 "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1BarrierSet.hpp"
33 #include "gc/g1/g1CollectedHeap.inline.hpp"
34 #include "gc/g1/g1CollectionSet.hpp"
35 #include "gc/g1/g1CollectorPolicy.hpp"
36 #include "gc/g1/g1CollectorState.hpp"
37 #include "gc/g1/g1ConcurrentRefine.hpp"
38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1MemoryPool.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1SATBMarkQueueFilter.hpp"
56 #include "gc/g1/g1StringDedup.hpp"
57 #include "gc/g1/g1ThreadLocalData.hpp"
58 #include "gc/g1/g1YCTypes.hpp"
59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
60 #include "gc/g1/heapRegion.inline.hpp"
61 #include "gc/g1/heapRegionRemSet.hpp"
62 #include "gc/g1/heapRegionSet.inline.hpp"
63 #include "gc/g1/vm_operations_g1.hpp"
64 #include "gc/shared/adaptiveSizePolicy.hpp"
65 #include "gc/shared/gcHeapSummary.hpp"
66 #include "gc/shared/gcId.hpp"
67 #include "gc/shared/gcLocker.hpp"
68 #include "gc/shared/gcTimer.hpp"
69 #include "gc/shared/gcTrace.hpp"
70 #include "gc/shared/gcTraceTime.inline.hpp"
71 #include "gc/shared/generationSpec.hpp"
72 #include "gc/shared/isGCActiveMark.hpp"
73 #include "gc/shared/oopStorageParState.hpp"
74 #include "gc/shared/preservedMarks.inline.hpp"
75 #include "gc/shared/suspendibleThreadSet.hpp"
76 #include "gc/shared/referenceProcessor.inline.hpp"
77 #include "gc/shared/taskqueue.inline.hpp"
78 #include "gc/shared/weakProcessor.hpp"
79 #include "logging/log.hpp"
80 #include "memory/allocation.hpp"
81 #include "memory/iterator.hpp"
82 #include "memory/metaspaceShared.hpp"
83 #include "memory/resourceArea.hpp"
84 #include "oops/access.inline.hpp"
85 #include "oops/compressedOops.inline.hpp"
86 #include "oops/oop.inline.hpp"
87 #include "prims/resolvedMethodTable.hpp"
88 #include "runtime/atomic.hpp"
89 #include "runtime/flags/flagSetting.hpp"
90 #include "runtime/handles.inline.hpp"
91 #include "runtime/init.hpp"
92 #include "runtime/orderAccess.hpp"
93 #include "runtime/threadSMR.hpp"
94 #include "runtime/vmThread.hpp"
95 #include "utilities/align.hpp"
96 #include "utilities/globalDefinitions.hpp"
97 #include "utilities/stack.inline.hpp"
98
99 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
100
101 // INVARIANTS/NOTES
102 //
103 // All allocation activity covered by the G1CollectedHeap interface is
104 // serialized by acquiring the HeapLock. This happens in mem_allocate
105 // and allocate_new_tlab, which are the "entry" points to the
106 // allocation code from the rest of the JVM. (Note that this does not
107 // apply to TLAB allocation, which is not part of this interface: it
108 // is done by clients of this interface.)
109
110 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
111 private:
112 size_t _num_dirtied;
113 G1CollectedHeap* _g1h;
114 G1CardTable* _g1_ct;
115
116 HeapRegion* region_for_card(jbyte* card_ptr) const {
117 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
118 }
119
120 bool will_become_free(HeapRegion* hr) const {
121 // A region will be freed by free_collection_set if the region is in the
122 // collection set and has not had an evacuation failure.
123 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
124 }
125
126 public:
127 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
128 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
129
130 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
131 HeapRegion* hr = region_for_card(card_ptr);
132
133 // Should only dirty cards in regions that won't be freed.
134 if (!will_become_free(hr)) {
135 *card_ptr = G1CardTable::dirty_card_val();
136 _num_dirtied++;
137 }
138
139 return true;
140 }
141
142 size_t num_dirtied() const { return _num_dirtied; }
143 };
144
145
146 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
147 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
148 }
149
150 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
151 // The from card cache is not the memory that is actually committed. So we cannot
152 // take advantage of the zero_filled parameter.
153 reset_from_card_cache(start_idx, num_regions);
154 }
155
156
157 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
158 MemRegion mr) {
159 return new HeapRegion(hrs_index, bot(), mr);
160 }
161
162 // Private methods.
163
164 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
165 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
166 "the only time we use this to allocate a humongous region is "
167 "when we are allocating a single humongous region");
168
169 HeapRegion* res = _hrm.allocate_free_region(is_old);
170
171 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
172 // Currently, only attempts to allocate GC alloc regions set
173 // do_expand to true. So, we should only reach here during a
174 // safepoint. If this assumption changes we might have to
175 // reconsider the use of _expand_heap_after_alloc_failure.
176 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
177
178 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
179 word_size * HeapWordSize);
180
181 if (expand(word_size * HeapWordSize)) {
182 // Given that expand() succeeded in expanding the heap, and we
183 // always expand the heap by an amount aligned to the heap
184 // region size, the free list should in theory not be empty.
185 // In either case allocate_free_region() will check for NULL.
186 res = _hrm.allocate_free_region(is_old);
187 } else {
188 _expand_heap_after_alloc_failure = false;
189 }
190 }
191 return res;
192 }
193
194 HeapWord*
195 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
196 uint num_regions,
197 size_t word_size) {
198 assert(first != G1_NO_HRM_INDEX, "pre-condition");
199 assert(is_humongous(word_size), "word_size should be humongous");
200 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
201
202 // Index of last region in the series.
203 uint last = first + num_regions - 1;
204
205 // We need to initialize the region(s) we just discovered. This is
206 // a bit tricky given that it can happen concurrently with
207 // refinement threads refining cards on these regions and
208 // potentially wanting to refine the BOT as they are scanning
209 // those cards (this can happen shortly after a cleanup; see CR
210 // 6991377). So we have to set up the region(s) carefully and in
211 // a specific order.
212
213 // The word size sum of all the regions we will allocate.
214 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
215 assert(word_size <= word_size_sum, "sanity");
216
217 // This will be the "starts humongous" region.
218 HeapRegion* first_hr = region_at(first);
219 // The header of the new object will be placed at the bottom of
220 // the first region.
221 HeapWord* new_obj = first_hr->bottom();
222 // This will be the new top of the new object.
223 HeapWord* obj_top = new_obj + word_size;
224
225 // First, we need to zero the header of the space that we will be
226 // allocating. When we update top further down, some refinement
227 // threads might try to scan the region. By zeroing the header we
228 // ensure that any thread that will try to scan the region will
229 // come across the zero klass word and bail out.
230 //
231 // NOTE: It would not have been correct to have used
232 // CollectedHeap::fill_with_object() and make the space look like
233 // an int array. The thread that is doing the allocation will
234 // later update the object header to a potentially different array
235 // type and, for a very short period of time, the klass and length
236 // fields will be inconsistent. This could cause a refinement
237 // thread to calculate the object size incorrectly.
238 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
239
240 // Next, pad out the unused tail of the last region with filler
241 // objects, for improved usage accounting.
242 // How many words we use for filler objects.
243 size_t word_fill_size = word_size_sum - word_size;
244
245 // How many words memory we "waste" which cannot hold a filler object.
246 size_t words_not_fillable = 0;
247
248 if (word_fill_size >= min_fill_size()) {
249 fill_with_objects(obj_top, word_fill_size);
250 } else if (word_fill_size > 0) {
251 // We have space to fill, but we cannot fit an object there.
252 words_not_fillable = word_fill_size;
253 word_fill_size = 0;
254 }
255
256 // We will set up the first region as "starts humongous". This
257 // will also update the BOT covering all the regions to reflect
258 // that there is a single object that starts at the bottom of the
259 // first region.
260 first_hr->set_starts_humongous(obj_top, word_fill_size);
261 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
262 // Then, if there are any, we will set up the "continues
263 // humongous" regions.
264 HeapRegion* hr = NULL;
265 for (uint i = first + 1; i <= last; ++i) {
266 hr = region_at(i);
267 hr->set_continues_humongous(first_hr);
268 _g1_policy->remset_tracker()->update_at_allocate(hr);
269 }
270
271 // Up to this point no concurrent thread would have been able to
272 // do any scanning on any region in this series. All the top
273 // fields still point to bottom, so the intersection between
274 // [bottom,top] and [card_start,card_end] will be empty. Before we
275 // update the top fields, we'll do a storestore to make sure that
276 // no thread sees the update to top before the zeroing of the
277 // object header and the BOT initialization.
278 OrderAccess::storestore();
279
280 // Now, we will update the top fields of the "continues humongous"
281 // regions except the last one.
282 for (uint i = first; i < last; ++i) {
283 hr = region_at(i);
284 hr->set_top(hr->end());
285 }
286
287 hr = region_at(last);
288 // If we cannot fit a filler object, we must set top to the end
289 // of the humongous object, otherwise we cannot iterate the heap
290 // and the BOT will not be complete.
291 hr->set_top(hr->end() - words_not_fillable);
292
293 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
294 "obj_top should be in last region");
295
296 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
297
298 assert(words_not_fillable == 0 ||
299 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
300 "Miscalculation in humongous allocation");
301
302 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
303
304 for (uint i = first; i <= last; ++i) {
305 hr = region_at(i);
306 _humongous_set.add(hr);
307 _hr_printer.alloc(hr);
308 }
309
310 return new_obj;
311 }
312
313 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
314 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
315 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
316 }
317
318 // If could fit into free regions w/o expansion, try.
319 // Otherwise, if can expand, do so.
320 // Otherwise, if using ex regions might help, try with ex given back.
321 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
322 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
323
324 _verifier->verify_region_sets_optional();
325
326 uint first = G1_NO_HRM_INDEX;
327 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
328
329 if (obj_regions == 1) {
330 // Only one region to allocate, try to use a fast path by directly allocating
331 // from the free lists. Do not try to expand here, we will potentially do that
332 // later.
333 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
334 if (hr != NULL) {
335 first = hr->hrm_index();
336 }
337 } else {
338 // Policy: Try only empty regions (i.e. already committed first). Maybe we
339 // are lucky enough to find some.
340 first = _hrm.find_contiguous_only_empty(obj_regions);
341 if (first != G1_NO_HRM_INDEX) {
342 _hrm.allocate_free_regions_starting_at(first, obj_regions);
343 }
344 }
345
346 if (first == G1_NO_HRM_INDEX) {
347 // Policy: We could not find enough regions for the humongous object in the
348 // free list. Look through the heap to find a mix of free and uncommitted regions.
349 // If so, try expansion.
350 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
351 if (first != G1_NO_HRM_INDEX) {
352 // We found something. Make sure these regions are committed, i.e. expand
353 // the heap. Alternatively we could do a defragmentation GC.
354 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
355 word_size * HeapWordSize);
356
357 _hrm.expand_at(first, obj_regions, workers());
358 g1_policy()->record_new_heap_size(num_regions());
359
360 #ifdef ASSERT
361 for (uint i = first; i < first + obj_regions; ++i) {
362 HeapRegion* hr = region_at(i);
363 assert(hr->is_free(), "sanity");
364 assert(hr->is_empty(), "sanity");
365 assert(is_on_master_free_list(hr), "sanity");
366 }
367 #endif
368 _hrm.allocate_free_regions_starting_at(first, obj_regions);
369 } else {
370 // Policy: Potentially trigger a defragmentation GC.
371 }
372 }
373
374 HeapWord* result = NULL;
375 if (first != G1_NO_HRM_INDEX) {
376 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
377 assert(result != NULL, "it should always return a valid result");
378
379 // A successful humongous object allocation changes the used space
380 // information of the old generation so we need to recalculate the
381 // sizes and update the jstat counters here.
382 g1mm()->update_sizes();
383 }
384
385 _verifier->verify_region_sets_optional();
386
387 return result;
388 }
389
390 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
391 size_t requested_size,
392 size_t* actual_size) {
393 assert_heap_not_locked_and_not_at_safepoint();
394 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
395
396 return attempt_allocation(min_size, requested_size, actual_size);
397 }
398
399 HeapWord*
400 G1CollectedHeap::mem_allocate(size_t word_size,
401 bool* gc_overhead_limit_was_exceeded) {
402 assert_heap_not_locked_and_not_at_safepoint();
403
404 if (is_humongous(word_size)) {
405 return attempt_allocation_humongous(word_size);
406 }
407 size_t dummy = 0;
408 return attempt_allocation(word_size, word_size, &dummy);
409 }
410
411 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
412 ResourceMark rm; // For retrieving the thread names in log messages.
413
414 // Make sure you read the note in attempt_allocation_humongous().
415
416 assert_heap_not_locked_and_not_at_safepoint();
417 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
418 "be called for humongous allocation requests");
419
420 // We should only get here after the first-level allocation attempt
421 // (attempt_allocation()) failed to allocate.
422
423 // We will loop until a) we manage to successfully perform the
424 // allocation or b) we successfully schedule a collection which
425 // fails to perform the allocation. b) is the only case when we'll
426 // return NULL.
427 HeapWord* result = NULL;
428 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
429 bool should_try_gc;
430 uint gc_count_before;
431
432 {
433 MutexLockerEx x(Heap_lock);
434 result = _allocator->attempt_allocation_locked(word_size);
435 if (result != NULL) {
436 return result;
437 }
438
439 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
440 // This is different to when only GCLocker::needs_gc() is set: try to avoid
441 // waiting because the GCLocker is active to not wait too long.
442 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
443 // No need for an ergo message here, can_expand_young_list() does this when
444 // it returns true.
445 result = _allocator->attempt_allocation_force(word_size);
446 if (result != NULL) {
447 return result;
448 }
449 }
450 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
451 // the GCLocker initiated GC has been performed and then retry. This includes
452 // the case when the GC Locker is not active but has not been performed.
453 should_try_gc = !GCLocker::needs_gc();
454 // Read the GC count while still holding the Heap_lock.
455 gc_count_before = total_collections();
456 }
457
458 if (should_try_gc) {
459 bool succeeded;
460 result = do_collection_pause(word_size, gc_count_before, &succeeded,
461 GCCause::_g1_inc_collection_pause);
462 if (result != NULL) {
463 assert(succeeded, "only way to get back a non-NULL result");
464 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
465 Thread::current()->name(), p2i(result));
466 return result;
467 }
468
469 if (succeeded) {
470 // We successfully scheduled a collection which failed to allocate. No
471 // point in trying to allocate further. We'll just return NULL.
472 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
473 SIZE_FORMAT " words", Thread::current()->name(), word_size);
474 return NULL;
475 }
476 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
477 Thread::current()->name(), word_size);
478 } else {
479 // Failed to schedule a collection.
480 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
481 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
482 SIZE_FORMAT " words", Thread::current()->name(), word_size);
483 return NULL;
484 }
485 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
486 // The GCLocker is either active or the GCLocker initiated
487 // GC has not yet been performed. Stall until it is and
488 // then retry the allocation.
489 GCLocker::stall_until_clear();
490 gclocker_retry_count += 1;
491 }
492
493 // We can reach here if we were unsuccessful in scheduling a
494 // collection (because another thread beat us to it) or if we were
495 // stalled due to the GC locker. In either can we should retry the
496 // allocation attempt in case another thread successfully
497 // performed a collection and reclaimed enough space. We do the
498 // first attempt (without holding the Heap_lock) here and the
499 // follow-on attempt will be at the start of the next loop
500 // iteration (after taking the Heap_lock).
501 size_t dummy = 0;
502 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
503 if (result != NULL) {
504 return result;
505 }
506
507 // Give a warning if we seem to be looping forever.
508 if ((QueuedAllocationWarningCount > 0) &&
509 (try_count % QueuedAllocationWarningCount == 0)) {
510 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
511 Thread::current()->name(), try_count, word_size);
512 }
513 }
514
515 ShouldNotReachHere();
516 return NULL;
517 }
518
519 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
520 assert_at_safepoint_on_vm_thread();
521 if (_archive_allocator == NULL) {
522 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
523 }
524 }
525
526 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
527 // Allocations in archive regions cannot be of a size that would be considered
528 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
529 // may be different at archive-restore time.
530 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
531 }
532
533 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
534 assert_at_safepoint_on_vm_thread();
535 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
536 if (is_archive_alloc_too_large(word_size)) {
537 return NULL;
538 }
539 return _archive_allocator->archive_mem_allocate(word_size);
540 }
541
542 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
543 size_t end_alignment_in_bytes) {
544 assert_at_safepoint_on_vm_thread();
545 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
546
547 // Call complete_archive to do the real work, filling in the MemRegion
548 // array with the archive regions.
549 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
550 delete _archive_allocator;
551 _archive_allocator = NULL;
552 }
553
554 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
555 assert(ranges != NULL, "MemRegion array NULL");
556 assert(count != 0, "No MemRegions provided");
557 MemRegion reserved = _hrm.reserved();
558 for (size_t i = 0; i < count; i++) {
559 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
560 return false;
561 }
562 }
563 return true;
564 }
565
566 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
567 size_t count,
568 bool open) {
569 assert(!is_init_completed(), "Expect to be called at JVM init time");
570 assert(ranges != NULL, "MemRegion array NULL");
571 assert(count != 0, "No MemRegions provided");
572 MutexLockerEx x(Heap_lock);
573
574 MemRegion reserved = _hrm.reserved();
575 HeapWord* prev_last_addr = NULL;
576 HeapRegion* prev_last_region = NULL;
577
578 // Temporarily disable pretouching of heap pages. This interface is used
579 // when mmap'ing archived heap data in, so pre-touching is wasted.
580 FlagSetting fs(AlwaysPreTouch, false);
581
582 // Enable archive object checking used by G1MarkSweep. We have to let it know
583 // about each archive range, so that objects in those ranges aren't marked.
584 G1ArchiveAllocator::enable_archive_object_check();
585
586 // For each specified MemRegion range, allocate the corresponding G1
587 // regions and mark them as archive regions. We expect the ranges
588 // in ascending starting address order, without overlap.
589 for (size_t i = 0; i < count; i++) {
590 MemRegion curr_range = ranges[i];
591 HeapWord* start_address = curr_range.start();
592 size_t word_size = curr_range.word_size();
593 HeapWord* last_address = curr_range.last();
594 size_t commits = 0;
595
596 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
597 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
598 p2i(start_address), p2i(last_address));
599 guarantee(start_address > prev_last_addr,
600 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
601 p2i(start_address), p2i(prev_last_addr));
602 prev_last_addr = last_address;
603
604 // Check for ranges that start in the same G1 region in which the previous
605 // range ended, and adjust the start address so we don't try to allocate
606 // the same region again. If the current range is entirely within that
607 // region, skip it, just adjusting the recorded top.
608 HeapRegion* start_region = _hrm.addr_to_region(start_address);
609 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
610 start_address = start_region->end();
611 if (start_address > last_address) {
612 increase_used(word_size * HeapWordSize);
613 start_region->set_top(last_address + 1);
614 continue;
615 }
616 start_region->set_top(start_address);
617 curr_range = MemRegion(start_address, last_address + 1);
618 start_region = _hrm.addr_to_region(start_address);
619 }
620
621 // Perform the actual region allocation, exiting if it fails.
622 // Then note how much new space we have allocated.
623 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
624 return false;
625 }
626 increase_used(word_size * HeapWordSize);
627 if (commits != 0) {
628 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
629 HeapRegion::GrainWords * HeapWordSize * commits);
630
631 }
632
633 // Mark each G1 region touched by the range as archive, add it to
634 // the old set, and set top.
635 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
636 HeapRegion* last_region = _hrm.addr_to_region(last_address);
637 prev_last_region = last_region;
638
639 while (curr_region != NULL) {
640 assert(curr_region->is_empty() && !curr_region->is_pinned(),
641 "Region already in use (index %u)", curr_region->hrm_index());
642 if (open) {
643 curr_region->set_open_archive();
644 } else {
645 curr_region->set_closed_archive();
646 }
647 _hr_printer.alloc(curr_region);
648 _old_set.add(curr_region);
649 HeapWord* top;
650 HeapRegion* next_region;
651 if (curr_region != last_region) {
652 top = curr_region->end();
653 next_region = _hrm.next_region_in_heap(curr_region);
654 } else {
655 top = last_address + 1;
656 next_region = NULL;
657 }
658 curr_region->set_top(top);
659 curr_region->set_first_dead(top);
660 curr_region->set_end_of_live(top);
661 curr_region = next_region;
662 }
663
664 // Notify mark-sweep of the archive
665 G1ArchiveAllocator::set_range_archive(curr_range, open);
666 }
667 return true;
668 }
669
670 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
671 assert(!is_init_completed(), "Expect to be called at JVM init time");
672 assert(ranges != NULL, "MemRegion array NULL");
673 assert(count != 0, "No MemRegions provided");
674 MemRegion reserved = _hrm.reserved();
675 HeapWord *prev_last_addr = NULL;
676 HeapRegion* prev_last_region = NULL;
677
678 // For each MemRegion, create filler objects, if needed, in the G1 regions
679 // that contain the address range. The address range actually within the
680 // MemRegion will not be modified. That is assumed to have been initialized
681 // elsewhere, probably via an mmap of archived heap data.
682 MutexLockerEx x(Heap_lock);
683 for (size_t i = 0; i < count; i++) {
684 HeapWord* start_address = ranges[i].start();
685 HeapWord* last_address = ranges[i].last();
686
687 assert(reserved.contains(start_address) && reserved.contains(last_address),
688 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
689 p2i(start_address), p2i(last_address));
690 assert(start_address > prev_last_addr,
691 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
692 p2i(start_address), p2i(prev_last_addr));
693
694 HeapRegion* start_region = _hrm.addr_to_region(start_address);
695 HeapRegion* last_region = _hrm.addr_to_region(last_address);
696 HeapWord* bottom_address = start_region->bottom();
697
698 // Check for a range beginning in the same region in which the
699 // previous one ended.
700 if (start_region == prev_last_region) {
701 bottom_address = prev_last_addr + 1;
702 }
703
704 // Verify that the regions were all marked as archive regions by
705 // alloc_archive_regions.
706 HeapRegion* curr_region = start_region;
707 while (curr_region != NULL) {
708 guarantee(curr_region->is_archive(),
709 "Expected archive region at index %u", curr_region->hrm_index());
710 if (curr_region != last_region) {
711 curr_region = _hrm.next_region_in_heap(curr_region);
712 } else {
713 curr_region = NULL;
714 }
715 }
716
717 prev_last_addr = last_address;
718 prev_last_region = last_region;
719
720 // Fill the memory below the allocated range with dummy object(s),
721 // if the region bottom does not match the range start, or if the previous
722 // range ended within the same G1 region, and there is a gap.
723 if (start_address != bottom_address) {
724 size_t fill_size = pointer_delta(start_address, bottom_address);
725 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
726 increase_used(fill_size * HeapWordSize);
727 }
728 }
729 }
730
731 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
732 size_t desired_word_size,
733 size_t* actual_word_size) {
734 assert_heap_not_locked_and_not_at_safepoint();
735 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
736 "be called for humongous allocation requests");
737
738 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
739
740 if (result == NULL) {
741 *actual_word_size = desired_word_size;
742 result = attempt_allocation_slow(desired_word_size);
743 }
744
745 assert_heap_not_locked();
746 if (result != NULL) {
747 assert(*actual_word_size != 0, "Actual size must have been set here");
748 dirty_young_block(result, *actual_word_size);
749 } else {
750 *actual_word_size = 0;
751 }
752
753 return result;
754 }
755
756 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
757 assert(!is_init_completed(), "Expect to be called at JVM init time");
758 assert(ranges != NULL, "MemRegion array NULL");
759 assert(count != 0, "No MemRegions provided");
760 MemRegion reserved = _hrm.reserved();
761 HeapWord* prev_last_addr = NULL;
762 HeapRegion* prev_last_region = NULL;
763 size_t size_used = 0;
764 size_t uncommitted_regions = 0;
765
766 // For each Memregion, free the G1 regions that constitute it, and
767 // notify mark-sweep that the range is no longer to be considered 'archive.'
768 MutexLockerEx x(Heap_lock);
769 for (size_t i = 0; i < count; i++) {
770 HeapWord* start_address = ranges[i].start();
771 HeapWord* last_address = ranges[i].last();
772
773 assert(reserved.contains(start_address) && reserved.contains(last_address),
774 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
775 p2i(start_address), p2i(last_address));
776 assert(start_address > prev_last_addr,
777 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
778 p2i(start_address), p2i(prev_last_addr));
779 size_used += ranges[i].byte_size();
780 prev_last_addr = last_address;
781
782 HeapRegion* start_region = _hrm.addr_to_region(start_address);
783 HeapRegion* last_region = _hrm.addr_to_region(last_address);
784
785 // Check for ranges that start in the same G1 region in which the previous
786 // range ended, and adjust the start address so we don't try to free
787 // the same region again. If the current range is entirely within that
788 // region, skip it.
789 if (start_region == prev_last_region) {
790 start_address = start_region->end();
791 if (start_address > last_address) {
792 continue;
793 }
794 start_region = _hrm.addr_to_region(start_address);
795 }
796 prev_last_region = last_region;
797
798 // After verifying that each region was marked as an archive region by
799 // alloc_archive_regions, set it free and empty and uncommit it.
800 HeapRegion* curr_region = start_region;
801 while (curr_region != NULL) {
802 guarantee(curr_region->is_archive(),
803 "Expected archive region at index %u", curr_region->hrm_index());
804 uint curr_index = curr_region->hrm_index();
805 _old_set.remove(curr_region);
806 curr_region->set_free();
807 curr_region->set_top(curr_region->bottom());
808 if (curr_region != last_region) {
809 curr_region = _hrm.next_region_in_heap(curr_region);
810 } else {
811 curr_region = NULL;
812 }
813 _hrm.shrink_at(curr_index, 1);
814 uncommitted_regions++;
815 }
816
817 // Notify mark-sweep that this is no longer an archive range.
818 G1ArchiveAllocator::set_range_archive(ranges[i], false);
819 }
820
821 if (uncommitted_regions != 0) {
822 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
823 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
824 }
825 decrease_used(size_used);
826 }
827
828 oop G1CollectedHeap::materialize_archived_object(oop obj) {
829 assert(obj != NULL, "archived obj is NULL");
830 assert(MetaspaceShared::is_archive_object(obj), "must be archived object");
831
832 // Loading an archived object makes it strongly reachable. If it is
833 // loaded during concurrent marking, it must be enqueued to the SATB
834 // queue, shading the previously white object gray.
835 G1BarrierSet::enqueue(obj);
836
837 return obj;
838 }
839
840 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
841 ResourceMark rm; // For retrieving the thread names in log messages.
842
843 // The structure of this method has a lot of similarities to
844 // attempt_allocation_slow(). The reason these two were not merged
845 // into a single one is that such a method would require several "if
846 // allocation is not humongous do this, otherwise do that"
847 // conditional paths which would obscure its flow. In fact, an early
848 // version of this code did use a unified method which was harder to
849 // follow and, as a result, it had subtle bugs that were hard to
850 // track down. So keeping these two methods separate allows each to
851 // be more readable. It will be good to keep these two in sync as
852 // much as possible.
853
854 assert_heap_not_locked_and_not_at_safepoint();
855 assert(is_humongous(word_size), "attempt_allocation_humongous() "
856 "should only be called for humongous allocations");
857
858 // Humongous objects can exhaust the heap quickly, so we should check if we
859 // need to start a marking cycle at each humongous object allocation. We do
860 // the check before we do the actual allocation. The reason for doing it
861 // before the allocation is that we avoid having to keep track of the newly
862 // allocated memory while we do a GC.
863 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
864 word_size)) {
865 collect(GCCause::_g1_humongous_allocation);
866 }
867
868 // We will loop until a) we manage to successfully perform the
869 // allocation or b) we successfully schedule a collection which
870 // fails to perform the allocation. b) is the only case when we'll
871 // return NULL.
872 HeapWord* result = NULL;
873 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
874 bool should_try_gc;
875 uint gc_count_before;
876
877
878 {
879 MutexLockerEx x(Heap_lock);
880
881 // Given that humongous objects are not allocated in young
882 // regions, we'll first try to do the allocation without doing a
883 // collection hoping that there's enough space in the heap.
884 result = humongous_obj_allocate(word_size);
885 if (result != NULL) {
886 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
887 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
888 return result;
889 }
890
891 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
892 // the GCLocker initiated GC has been performed and then retry. This includes
893 // the case when the GC Locker is not active but has not been performed.
894 should_try_gc = !GCLocker::needs_gc();
895 // Read the GC count while still holding the Heap_lock.
896 gc_count_before = total_collections();
897 }
898
899 if (should_try_gc) {
900 bool succeeded;
901 result = do_collection_pause(word_size, gc_count_before, &succeeded,
902 GCCause::_g1_humongous_allocation);
903 if (result != NULL) {
904 assert(succeeded, "only way to get back a non-NULL result");
905 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
906 Thread::current()->name(), p2i(result));
907 return result;
908 }
909
910 if (succeeded) {
911 // We successfully scheduled a collection which failed to allocate. No
912 // point in trying to allocate further. We'll just return NULL.
913 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
914 SIZE_FORMAT " words", Thread::current()->name(), word_size);
915 return NULL;
916 }
917 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
918 Thread::current()->name(), word_size);
919 } else {
920 // Failed to schedule a collection.
921 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
922 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
923 SIZE_FORMAT " words", Thread::current()->name(), word_size);
924 return NULL;
925 }
926 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
927 // The GCLocker is either active or the GCLocker initiated
928 // GC has not yet been performed. Stall until it is and
929 // then retry the allocation.
930 GCLocker::stall_until_clear();
931 gclocker_retry_count += 1;
932 }
933
934
935 // We can reach here if we were unsuccessful in scheduling a
936 // collection (because another thread beat us to it) or if we were
937 // stalled due to the GC locker. In either can we should retry the
938 // allocation attempt in case another thread successfully
939 // performed a collection and reclaimed enough space.
940 // Humongous object allocation always needs a lock, so we wait for the retry
941 // in the next iteration of the loop, unlike for the regular iteration case.
942 // Give a warning if we seem to be looping forever.
943
944 if ((QueuedAllocationWarningCount > 0) &&
945 (try_count % QueuedAllocationWarningCount == 0)) {
946 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
947 Thread::current()->name(), try_count, word_size);
948 }
949 }
950
951 ShouldNotReachHere();
952 return NULL;
953 }
954
955 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
956 bool expect_null_mutator_alloc_region) {
957 assert_at_safepoint_on_vm_thread();
958 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
959 "the current alloc region was unexpectedly found to be non-NULL");
960
961 if (!is_humongous(word_size)) {
962 return _allocator->attempt_allocation_locked(word_size);
963 } else {
964 HeapWord* result = humongous_obj_allocate(word_size);
965 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
966 collector_state()->set_initiate_conc_mark_if_possible(true);
967 }
968 return result;
969 }
970
971 ShouldNotReachHere();
972 }
973
974 class PostCompactionPrinterClosure: public HeapRegionClosure {
975 private:
976 G1HRPrinter* _hr_printer;
977 public:
978 bool do_heap_region(HeapRegion* hr) {
979 assert(!hr->is_young(), "not expecting to find young regions");
980 _hr_printer->post_compaction(hr);
981 return false;
982 }
983
984 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
985 : _hr_printer(hr_printer) { }
986 };
987
988 void G1CollectedHeap::print_hrm_post_compaction() {
989 if (_hr_printer.is_active()) {
990 PostCompactionPrinterClosure cl(hr_printer());
991 heap_region_iterate(&cl);
992 }
993 }
994
995 void G1CollectedHeap::abort_concurrent_cycle() {
996 // If we start the compaction before the CM threads finish
997 // scanning the root regions we might trip them over as we'll
998 // be moving objects / updating references. So let's wait until
999 // they are done. By telling them to abort, they should complete
1000 // early.
1001 _cm->root_regions()->abort();
1002 _cm->root_regions()->wait_until_scan_finished();
1003
1004 // Disable discovery and empty the discovered lists
1005 // for the CM ref processor.
1006 _ref_processor_cm->disable_discovery();
1007 _ref_processor_cm->abandon_partial_discovery();
1008 _ref_processor_cm->verify_no_references_recorded();
1009
1010 // Abandon current iterations of concurrent marking and concurrent
1011 // refinement, if any are in progress.
1012 concurrent_mark()->concurrent_cycle_abort();
1013 }
1014
1015 void G1CollectedHeap::prepare_heap_for_full_collection() {
1016 // Make sure we'll choose a new allocation region afterwards.
1017 _allocator->release_mutator_alloc_region();
1018 _allocator->abandon_gc_alloc_regions();
1019 g1_rem_set()->cleanupHRRS();
1020
1021 // We may have added regions to the current incremental collection
1022 // set between the last GC or pause and now. We need to clear the
1023 // incremental collection set and then start rebuilding it afresh
1024 // after this full GC.
1025 abandon_collection_set(collection_set());
1026
1027 tear_down_region_sets(false /* free_list_only */);
1028 }
1029
1030 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1031 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1032 assert(used() == recalculate_used(), "Should be equal");
1033 _verifier->verify_region_sets_optional();
1034 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1035 _verifier->check_bitmaps("Full GC Start");
1036 }
1037
1038 void G1CollectedHeap::prepare_heap_for_mutators() {
1039 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1040 ClassLoaderDataGraph::purge();
1041 MetaspaceUtils::verify_metrics();
1042
1043 // Prepare heap for normal collections.
1044 assert(num_free_regions() == 0, "we should not have added any free regions");
1045 rebuild_region_sets(false /* free_list_only */);
1046 abort_refinement();
1047 resize_if_necessary_after_full_collection();
1048
1049 // Rebuild the strong code root lists for each region
1050 rebuild_strong_code_roots();
1051
1052 // Start a new incremental collection set for the next pause
1053 start_new_collection_set();
1054
1055 _allocator->init_mutator_alloc_region();
1056
1057 // Post collection state updates.
1058 MetaspaceGC::compute_new_size();
1059 }
1060
1061 void G1CollectedHeap::abort_refinement() {
1062 if (_hot_card_cache->use_cache()) {
1063 _hot_card_cache->reset_hot_cache();
1064 }
1065
1066 // Discard all remembered set updates.
1067 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1068 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1069 }
1070
1071 void G1CollectedHeap::verify_after_full_collection() {
1072 _hrm.verify_optional();
1073 _verifier->verify_region_sets_optional();
1074 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1075 // Clear the previous marking bitmap, if needed for bitmap verification.
1076 // Note we cannot do this when we clear the next marking bitmap in
1077 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1078 // objects marked during a full GC against the previous bitmap.
1079 // But we need to clear it before calling check_bitmaps below since
1080 // the full GC has compacted objects and updated TAMS but not updated
1081 // the prev bitmap.
1082 if (G1VerifyBitmaps) {
1083 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1084 _cm->clear_prev_bitmap(workers());
1085 }
1086 _verifier->check_bitmaps("Full GC End");
1087
1088 // At this point there should be no regions in the
1089 // entire heap tagged as young.
1090 assert(check_young_list_empty(), "young list should be empty at this point");
1091
1092 // Note: since we've just done a full GC, concurrent
1093 // marking is no longer active. Therefore we need not
1094 // re-enable reference discovery for the CM ref processor.
1095 // That will be done at the start of the next marking cycle.
1096 // We also know that the STW processor should no longer
1097 // discover any new references.
1098 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1099 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1100 _ref_processor_stw->verify_no_references_recorded();
1101 _ref_processor_cm->verify_no_references_recorded();
1102 }
1103
1104 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1105 // Post collection logging.
1106 // We should do this after we potentially resize the heap so
1107 // that all the COMMIT / UNCOMMIT events are generated before
1108 // the compaction events.
1109 print_hrm_post_compaction();
1110 heap_transition->print();
1111 print_heap_after_gc();
1112 print_heap_regions();
1113 #ifdef TRACESPINNING
1114 ParallelTaskTerminator::print_termination_counts();
1115 #endif
1116 }
1117
1118 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1119 bool clear_all_soft_refs) {
1120 assert_at_safepoint_on_vm_thread();
1121
1122 if (GCLocker::check_active_before_gc()) {
1123 // Full GC was not completed.
1124 return false;
1125 }
1126
1127 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1128 soft_ref_policy()->should_clear_all_soft_refs();
1129
1130 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1131 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1132
1133 collector.prepare_collection();
1134 collector.collect();
1135 collector.complete_collection();
1136
1137 // Full collection was successfully completed.
1138 return true;
1139 }
1140
1141 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1142 // Currently, there is no facility in the do_full_collection(bool) API to notify
1143 // the caller that the collection did not succeed (e.g., because it was locked
1144 // out by the GC locker). So, right now, we'll ignore the return value.
1145 bool dummy = do_full_collection(true, /* explicit_gc */
1146 clear_all_soft_refs);
1147 }
1148
1149 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1150 // Capacity, free and used after the GC counted as full regions to
1151 // include the waste in the following calculations.
1152 const size_t capacity_after_gc = capacity();
1153 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1154
1155 // This is enforced in arguments.cpp.
1156 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1157 "otherwise the code below doesn't make sense");
1158
1159 // We don't have floating point command-line arguments
1160 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1161 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1162 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1163 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1164
1165 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1166 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1167
1168 // We have to be careful here as these two calculations can overflow
1169 // 32-bit size_t's.
1170 double used_after_gc_d = (double) used_after_gc;
1171 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1172 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1173
1174 // Let's make sure that they are both under the max heap size, which
1175 // by default will make them fit into a size_t.
1176 double desired_capacity_upper_bound = (double) max_heap_size;
1177 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1178 desired_capacity_upper_bound);
1179 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1180 desired_capacity_upper_bound);
1181
1182 // We can now safely turn them into size_t's.
1183 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1184 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1185
1186 // This assert only makes sense here, before we adjust them
1187 // with respect to the min and max heap size.
1188 assert(minimum_desired_capacity <= maximum_desired_capacity,
1189 "minimum_desired_capacity = " SIZE_FORMAT ", "
1190 "maximum_desired_capacity = " SIZE_FORMAT,
1191 minimum_desired_capacity, maximum_desired_capacity);
1192
1193 // Should not be greater than the heap max size. No need to adjust
1194 // it with respect to the heap min size as it's a lower bound (i.e.,
1195 // we'll try to make the capacity larger than it, not smaller).
1196 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1197 // Should not be less than the heap min size. No need to adjust it
1198 // with respect to the heap max size as it's an upper bound (i.e.,
1199 // we'll try to make the capacity smaller than it, not greater).
1200 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1201
1202 if (capacity_after_gc < minimum_desired_capacity) {
1203 // Don't expand unless it's significant
1204 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1205
1206 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1207 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1208 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1209 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1210
1211 expand(expand_bytes, _workers);
1212
1213 // No expansion, now see if we want to shrink
1214 } else if (capacity_after_gc > maximum_desired_capacity) {
1215 // Capacity too large, compute shrinking size
1216 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1217
1218 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1219 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1220 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1221 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1222
1223 shrink(shrink_bytes);
1224 }
1225 }
1226
1227 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1228 bool do_gc,
1229 bool clear_all_soft_refs,
1230 bool expect_null_mutator_alloc_region,
1231 bool* gc_succeeded) {
1232 *gc_succeeded = true;
1233 // Let's attempt the allocation first.
1234 HeapWord* result =
1235 attempt_allocation_at_safepoint(word_size,
1236 expect_null_mutator_alloc_region);
1237 if (result != NULL) {
1238 return result;
1239 }
1240
1241 // In a G1 heap, we're supposed to keep allocation from failing by
1242 // incremental pauses. Therefore, at least for now, we'll favor
1243 // expansion over collection. (This might change in the future if we can
1244 // do something smarter than full collection to satisfy a failed alloc.)
1245 result = expand_and_allocate(word_size);
1246 if (result != NULL) {
1247 return result;
1248 }
1249
1250 if (do_gc) {
1251 // Expansion didn't work, we'll try to do a Full GC.
1252 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1253 clear_all_soft_refs);
1254 }
1255
1256 return NULL;
1257 }
1258
1259 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1260 bool* succeeded) {
1261 assert_at_safepoint_on_vm_thread();
1262
1263 // Attempts to allocate followed by Full GC.
1264 HeapWord* result =
1265 satisfy_failed_allocation_helper(word_size,
1266 true, /* do_gc */
1267 false, /* clear_all_soft_refs */
1268 false, /* expect_null_mutator_alloc_region */
1269 succeeded);
1270
1271 if (result != NULL || !*succeeded) {
1272 return result;
1273 }
1274
1275 // Attempts to allocate followed by Full GC that will collect all soft references.
1276 result = satisfy_failed_allocation_helper(word_size,
1277 true, /* do_gc */
1278 true, /* clear_all_soft_refs */
1279 true, /* expect_null_mutator_alloc_region */
1280 succeeded);
1281
1282 if (result != NULL || !*succeeded) {
1283 return result;
1284 }
1285
1286 // Attempts to allocate, no GC
1287 result = satisfy_failed_allocation_helper(word_size,
1288 false, /* do_gc */
1289 false, /* clear_all_soft_refs */
1290 true, /* expect_null_mutator_alloc_region */
1291 succeeded);
1292
1293 if (result != NULL) {
1294 return result;
1295 }
1296
1297 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1298 "Flag should have been handled and cleared prior to this point");
1299
1300 // What else? We might try synchronous finalization later. If the total
1301 // space available is large enough for the allocation, then a more
1302 // complete compaction phase than we've tried so far might be
1303 // appropriate.
1304 return NULL;
1305 }
1306
1307 // Attempting to expand the heap sufficiently
1308 // to support an allocation of the given "word_size". If
1309 // successful, perform the allocation and return the address of the
1310 // allocated block, or else "NULL".
1311
1312 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1313 assert_at_safepoint_on_vm_thread();
1314
1315 _verifier->verify_region_sets_optional();
1316
1317 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1318 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1319 word_size * HeapWordSize);
1320
1321
1322 if (expand(expand_bytes, _workers)) {
1323 _hrm.verify_optional();
1324 _verifier->verify_region_sets_optional();
1325 return attempt_allocation_at_safepoint(word_size,
1326 false /* expect_null_mutator_alloc_region */);
1327 }
1328 return NULL;
1329 }
1330
1331 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1332 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1333 aligned_expand_bytes = align_up(aligned_expand_bytes,
1334 HeapRegion::GrainBytes);
1335
1336 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1337 expand_bytes, aligned_expand_bytes);
1338
1339 if (is_maximal_no_gc()) {
1340 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1341 return false;
1342 }
1343
1344 double expand_heap_start_time_sec = os::elapsedTime();
1345 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1346 assert(regions_to_expand > 0, "Must expand by at least one region");
1347
1348 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1349 if (expand_time_ms != NULL) {
1350 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1351 }
1352
1353 if (expanded_by > 0) {
1354 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1355 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1356 g1_policy()->record_new_heap_size(num_regions());
1357 } else {
1358 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1359
1360 // The expansion of the virtual storage space was unsuccessful.
1361 // Let's see if it was because we ran out of swap.
1362 if (G1ExitOnExpansionFailure &&
1363 _hrm.available() >= regions_to_expand) {
1364 // We had head room...
1365 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1366 }
1367 }
1368 return regions_to_expand > 0;
1369 }
1370
1371 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1372 size_t aligned_shrink_bytes =
1373 ReservedSpace::page_align_size_down(shrink_bytes);
1374 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1375 HeapRegion::GrainBytes);
1376 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1377
1378 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1379 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1380
1381
1382 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",
1383 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1384 if (num_regions_removed > 0) {
1385 g1_policy()->record_new_heap_size(num_regions());
1386 } else {
1387 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1388 }
1389 }
1390
1391 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1392 _verifier->verify_region_sets_optional();
1393
1394 // We should only reach here at the end of a Full GC which means we
1395 // should not not be holding to any GC alloc regions. The method
1396 // below will make sure of that and do any remaining clean up.
1397 _allocator->abandon_gc_alloc_regions();
1398
1399 // Instead of tearing down / rebuilding the free lists here, we
1400 // could instead use the remove_all_pending() method on free_list to
1401 // remove only the ones that we need to remove.
1402 tear_down_region_sets(true /* free_list_only */);
1403 shrink_helper(shrink_bytes);
1404 rebuild_region_sets(true /* free_list_only */);
1405
1406 _hrm.verify_optional();
1407 _verifier->verify_region_sets_optional();
1408 }
1409
1410 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1411 CollectedHeap(),
1412 _young_gen_sampling_thread(NULL),
1413 _workers(NULL),
1414 _collector_policy(collector_policy),
1415 _card_table(NULL),
1416 _soft_ref_policy(),
1417 _memory_manager("G1 Young Generation", "end of minor GC"),
1418 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1419 _eden_pool(NULL),
1420 _survivor_pool(NULL),
1421 _old_pool(NULL),
1422 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1423 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1424 _bot(NULL),
1425 _listener(),
1426 _hrm(),
1427 _allocator(NULL),
1428 _verifier(NULL),
1429 _summary_bytes_used(0),
1430 _archive_allocator(NULL),
1431 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1432 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1433 _expand_heap_after_alloc_failure(true),
1434 _g1mm(NULL),
1435 _humongous_reclaim_candidates(),
1436 _has_humongous_reclaim_candidates(false),
1437 _hr_printer(),
1438 _collector_state(),
1439 _old_marking_cycles_started(0),
1440 _old_marking_cycles_completed(0),
1441 _eden(),
1442 _survivor(),
1443 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1444 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1445 _g1_policy(new G1Policy(_gc_timer_stw)),
1446 _heap_sizing_policy(NULL),
1447 _collection_set(this, _g1_policy),
1448 _hot_card_cache(NULL),
1449 _g1_rem_set(NULL),
1450 _dirty_card_queue_set(false),
1451 _cm(NULL),
1452 _cm_thread(NULL),
1453 _cr(NULL),
1454 _task_queues(NULL),
1455 _evacuation_failed(false),
1456 _evacuation_failed_info_array(NULL),
1457 _preserved_marks_set(true /* in_c_heap */),
1458 #ifndef PRODUCT
1459 _evacuation_failure_alot_for_current_gc(false),
1460 _evacuation_failure_alot_gc_number(0),
1461 _evacuation_failure_alot_count(0),
1462 #endif
1463 _ref_processor_stw(NULL),
1464 _is_alive_closure_stw(this),
1465 _is_subject_to_discovery_stw(this),
1466 _ref_processor_cm(NULL),
1467 _is_alive_closure_cm(this),
1468 _is_subject_to_discovery_cm(this),
1469 _in_cset_fast_test() {
1470
1471 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1472 true /* are_GC_task_threads */,
1473 false /* are_ConcurrentGC_threads */);
1474 _workers->initialize_workers();
1475 _verifier = new G1HeapVerifier(this);
1476
1477 _allocator = new G1Allocator(this);
1478
1479 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1480
1481 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1482
1483 // Override the default _filler_array_max_size so that no humongous filler
1484 // objects are created.
1485 _filler_array_max_size = _humongous_object_threshold_in_words;
1486
1487 uint n_queues = ParallelGCThreads;
1488 _task_queues = new RefToScanQueueSet(n_queues);
1489
1490 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1491
1492 for (uint i = 0; i < n_queues; i++) {
1493 RefToScanQueue* q = new RefToScanQueue();
1494 q->initialize();
1495 _task_queues->register_queue(i, q);
1496 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1497 }
1498
1499 // Initialize the G1EvacuationFailureALot counters and flags.
1500 NOT_PRODUCT(reset_evacuation_should_fail();)
1501
1502 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1503 }
1504
1505 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1506 size_t size,
1507 size_t translation_factor) {
1508 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1509 // Allocate a new reserved space, preferring to use large pages.
1510 ReservedSpace rs(size, preferred_page_size);
1511 G1RegionToSpaceMapper* result =
1512 G1RegionToSpaceMapper::create_mapper(rs,
1513 size,
1514 rs.alignment(),
1515 HeapRegion::GrainBytes,
1516 translation_factor,
1517 mtGC);
1518
1519 os::trace_page_sizes_for_requested_size(description,
1520 size,
1521 preferred_page_size,
1522 rs.alignment(),
1523 rs.base(),
1524 rs.size());
1525
1526 return result;
1527 }
1528
1529 jint G1CollectedHeap::initialize_concurrent_refinement() {
1530 jint ecode = JNI_OK;
1531 _cr = G1ConcurrentRefine::create(&ecode);
1532 return ecode;
1533 }
1534
1535 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1536 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1537 if (_young_gen_sampling_thread->osthread() == NULL) {
1538 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1539 return JNI_ENOMEM;
1540 }
1541 return JNI_OK;
1542 }
1543
1544 jint G1CollectedHeap::initialize() {
1545 os::enable_vtime();
1546
1547 // Necessary to satisfy locking discipline assertions.
1548
1549 MutexLocker x(Heap_lock);
1550
1551 // While there are no constraints in the GC code that HeapWordSize
1552 // be any particular value, there are multiple other areas in the
1553 // system which believe this to be true (e.g. oop->object_size in some
1554 // cases incorrectly returns the size in wordSize units rather than
1555 // HeapWordSize).
1556 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1557
1558 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1559 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1560 size_t heap_alignment = collector_policy()->heap_alignment();
1561
1562 // Ensure that the sizes are properly aligned.
1563 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1564 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1565 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1566
1567 // Reserve the maximum.
1568
1569 // When compressed oops are enabled, the preferred heap base
1570 // is calculated by subtracting the requested size from the
1571 // 32Gb boundary and using the result as the base address for
1572 // heap reservation. If the requested size is not aligned to
1573 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1574 // into the ReservedHeapSpace constructor) then the actual
1575 // base of the reserved heap may end up differing from the
1576 // address that was requested (i.e. the preferred heap base).
1577 // If this happens then we could end up using a non-optimal
1578 // compressed oops mode.
1579
1580 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1581 heap_alignment);
1582
1583 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1584
1585 // Create the barrier set for the entire reserved region.
1586 G1CardTable* ct = new G1CardTable(reserved_region());
1587 ct->initialize();
1588 G1BarrierSet* bs = new G1BarrierSet(ct);
1589 bs->initialize();
1590 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1591 BarrierSet::set_barrier_set(bs);
1592 _card_table = ct;
1593
1594 // Create the hot card cache.
1595 _hot_card_cache = new G1HotCardCache(this);
1596
1597 // Carve out the G1 part of the heap.
1598 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1599 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1600 G1RegionToSpaceMapper* heap_storage =
1601 G1RegionToSpaceMapper::create_mapper(g1_rs,
1602 g1_rs.size(),
1603 page_size,
1604 HeapRegion::GrainBytes,
1605 1,
1606 mtJavaHeap);
1607 os::trace_page_sizes("Heap",
1608 collector_policy()->min_heap_byte_size(),
1609 max_byte_size,
1610 page_size,
1611 heap_rs.base(),
1612 heap_rs.size());
1613 heap_storage->set_mapping_changed_listener(&_listener);
1614
1615 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1616 G1RegionToSpaceMapper* bot_storage =
1617 create_aux_memory_mapper("Block Offset Table",
1618 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1619 G1BlockOffsetTable::heap_map_factor());
1620
1621 G1RegionToSpaceMapper* cardtable_storage =
1622 create_aux_memory_mapper("Card Table",
1623 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1624 G1CardTable::heap_map_factor());
1625
1626 G1RegionToSpaceMapper* card_counts_storage =
1627 create_aux_memory_mapper("Card Counts Table",
1628 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1629 G1CardCounts::heap_map_factor());
1630
1631 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1632 G1RegionToSpaceMapper* prev_bitmap_storage =
1633 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1634 G1RegionToSpaceMapper* next_bitmap_storage =
1635 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1636
1637 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1638 _card_table->initialize(cardtable_storage);
1639 // Do later initialization work for concurrent refinement.
1640 _hot_card_cache->initialize(card_counts_storage);
1641
1642 // 6843694 - ensure that the maximum region index can fit
1643 // in the remembered set structures.
1644 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1645 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1646
1647 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1648 // start within the first card.
1649 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1650 // Also create a G1 rem set.
1651 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1652 _g1_rem_set->initialize(max_capacity(), max_regions());
1653
1654 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1655 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1656 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1657 "too many cards per region");
1658
1659 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1660
1661 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1662
1663 {
1664 HeapWord* start = _hrm.reserved().start();
1665 HeapWord* end = _hrm.reserved().end();
1666 size_t granularity = HeapRegion::GrainBytes;
1667
1668 _in_cset_fast_test.initialize(start, end, granularity);
1669 _humongous_reclaim_candidates.initialize(start, end, granularity);
1670 }
1671
1672 // Create the G1ConcurrentMark data structure and thread.
1673 // (Must do this late, so that "max_regions" is defined.)
1674 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1675 if (_cm == NULL || !_cm->completed_initialization()) {
1676 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1677 return JNI_ENOMEM;
1678 }
1679 _cm_thread = _cm->cm_thread();
1680
1681 // Now expand into the initial heap size.
1682 if (!expand(init_byte_size, _workers)) {
1683 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1684 return JNI_ENOMEM;
1685 }
1686
1687 // Perform any initialization actions delegated to the policy.
1688 g1_policy()->init(this, &_collection_set);
1689
1690 G1SATBMarkQueueFilter* satb_filter = new G1SATBMarkQueueFilter(this);
1691 G1BarrierSet::satb_mark_queue_set().initialize(satb_filter,
1692 SATB_Q_CBL_mon,
1693 SATB_Q_FL_lock,
1694 G1SATBProcessCompletedThreshold,
1695 Shared_SATB_Q_lock);
1696
1697 jint ecode = initialize_concurrent_refinement();
1698 if (ecode != JNI_OK) {
1699 return ecode;
1700 }
1701
1702 ecode = initialize_young_gen_sampling_thread();
1703 if (ecode != JNI_OK) {
1704 return ecode;
1705 }
1706
1707 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1708 DirtyCardQ_FL_lock,
1709 (int)concurrent_refine()->yellow_zone(),
1710 (int)concurrent_refine()->red_zone(),
1711 Shared_DirtyCardQ_lock,
1712 NULL, // fl_owner
1713 true); // init_free_ids
1714
1715 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1716 DirtyCardQ_FL_lock,
1717 -1, // never trigger processing
1718 -1, // no limit on length
1719 Shared_DirtyCardQ_lock,
1720 &G1BarrierSet::dirty_card_queue_set());
1721
1722 // Here we allocate the dummy HeapRegion that is required by the
1723 // G1AllocRegion class.
1724 HeapRegion* dummy_region = _hrm.get_dummy_region();
1725
1726 // We'll re-use the same region whether the alloc region will
1727 // require BOT updates or not and, if it doesn't, then a non-young
1728 // region will complain that it cannot support allocations without
1729 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1730 dummy_region->set_eden();
1731 // Make sure it's full.
1732 dummy_region->set_top(dummy_region->end());
1733 G1AllocRegion::setup(this, dummy_region);
1734
1735 _allocator->init_mutator_alloc_region();
1736
1737 // Do create of the monitoring and management support so that
1738 // values in the heap have been properly initialized.
1739 _g1mm = new G1MonitoringSupport(this);
1740
1741 G1StringDedup::initialize();
1742
1743 _preserved_marks_set.init(ParallelGCThreads);
1744
1745 _collection_set.initialize(max_regions());
1746
1747 return JNI_OK;
1748 }
1749
1750 void G1CollectedHeap::initialize_serviceability() {
1751 _eden_pool = new G1EdenPool(this);
1752 _survivor_pool = new G1SurvivorPool(this);
1753 _old_pool = new G1OldGenPool(this);
1754
1755 _full_gc_memory_manager.add_pool(_eden_pool);
1756 _full_gc_memory_manager.add_pool(_survivor_pool);
1757 _full_gc_memory_manager.add_pool(_old_pool);
1758
1759 _memory_manager.add_pool(_eden_pool);
1760 _memory_manager.add_pool(_survivor_pool);
1761 _memory_manager.add_pool(_old_pool, false /* always_affected_by_gc */);
1762 }
1763
1764 void G1CollectedHeap::stop() {
1765 // Stop all concurrent threads. We do this to make sure these threads
1766 // do not continue to execute and access resources (e.g. logging)
1767 // that are destroyed during shutdown.
1768 _cr->stop();
1769 _young_gen_sampling_thread->stop();
1770 _cm_thread->stop();
1771 if (G1StringDedup::is_enabled()) {
1772 G1StringDedup::stop();
1773 }
1774 }
1775
1776 void G1CollectedHeap::safepoint_synchronize_begin() {
1777 SuspendibleThreadSet::synchronize();
1778 }
1779
1780 void G1CollectedHeap::safepoint_synchronize_end() {
1781 SuspendibleThreadSet::desynchronize();
1782 }
1783
1784 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1785 return HeapRegion::max_region_size();
1786 }
1787
1788 void G1CollectedHeap::post_initialize() {
1789 CollectedHeap::post_initialize();
1790 ref_processing_init();
1791 }
1792
1793 void G1CollectedHeap::ref_processing_init() {
1794 // Reference processing in G1 currently works as follows:
1795 //
1796 // * There are two reference processor instances. One is
1797 // used to record and process discovered references
1798 // during concurrent marking; the other is used to
1799 // record and process references during STW pauses
1800 // (both full and incremental).
1801 // * Both ref processors need to 'span' the entire heap as
1802 // the regions in the collection set may be dotted around.
1803 //
1804 // * For the concurrent marking ref processor:
1805 // * Reference discovery is enabled at initial marking.
1806 // * Reference discovery is disabled and the discovered
1807 // references processed etc during remarking.
1808 // * Reference discovery is MT (see below).
1809 // * Reference discovery requires a barrier (see below).
1810 // * Reference processing may or may not be MT
1811 // (depending on the value of ParallelRefProcEnabled
1812 // and ParallelGCThreads).
1813 // * A full GC disables reference discovery by the CM
1814 // ref processor and abandons any entries on it's
1815 // discovered lists.
1816 //
1817 // * For the STW processor:
1818 // * Non MT discovery is enabled at the start of a full GC.
1819 // * Processing and enqueueing during a full GC is non-MT.
1820 // * During a full GC, references are processed after marking.
1821 //
1822 // * Discovery (may or may not be MT) is enabled at the start
1823 // of an incremental evacuation pause.
1824 // * References are processed near the end of a STW evacuation pause.
1825 // * For both types of GC:
1826 // * Discovery is atomic - i.e. not concurrent.
1827 // * Reference discovery will not need a barrier.
1828
1829 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1830
1831 // Concurrent Mark ref processor
1832 _ref_processor_cm =
1833 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1834 mt_processing, // mt processing
1835 ParallelGCThreads, // degree of mt processing
1836 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1837 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1838 false, // Reference discovery is not atomic
1839 &_is_alive_closure_cm, // is alive closure
1840 true); // allow changes to number of processing threads
1841
1842 // STW ref processor
1843 _ref_processor_stw =
1844 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1845 mt_processing, // mt processing
1846 ParallelGCThreads, // degree of mt processing
1847 (ParallelGCThreads > 1), // mt discovery
1848 ParallelGCThreads, // degree of mt discovery
1849 true, // Reference discovery is atomic
1850 &_is_alive_closure_stw, // is alive closure
1851 true); // allow changes to number of processing threads
1852 }
1853
1854 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1855 return _collector_policy;
1856 }
1857
1858 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1859 return &_soft_ref_policy;
1860 }
1861
1862 size_t G1CollectedHeap::capacity() const {
1863 return _hrm.length() * HeapRegion::GrainBytes;
1864 }
1865
1866 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1867 return _hrm.total_free_bytes();
1868 }
1869
1870 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1871 _hot_card_cache->drain(cl, worker_i);
1872 }
1873
1874 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1875 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1876 size_t n_completed_buffers = 0;
1877 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1878 n_completed_buffers++;
1879 }
1880 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1881 dcqs.clear_n_completed_buffers();
1882 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1883 }
1884
1885 // Computes the sum of the storage used by the various regions.
1886 size_t G1CollectedHeap::used() const {
1887 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1888 if (_archive_allocator != NULL) {
1889 result += _archive_allocator->used();
1890 }
1891 return result;
1892 }
1893
1894 size_t G1CollectedHeap::used_unlocked() const {
1895 return _summary_bytes_used;
1896 }
1897
1898 class SumUsedClosure: public HeapRegionClosure {
1899 size_t _used;
1900 public:
1901 SumUsedClosure() : _used(0) {}
1902 bool do_heap_region(HeapRegion* r) {
1903 _used += r->used();
1904 return false;
1905 }
1906 size_t result() { return _used; }
1907 };
1908
1909 size_t G1CollectedHeap::recalculate_used() const {
1910 double recalculate_used_start = os::elapsedTime();
1911
1912 SumUsedClosure blk;
1913 heap_region_iterate(&blk);
1914
1915 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1916 return blk.result();
1917 }
1918
1919 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1920 switch (cause) {
1921 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1922 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1923 case GCCause::_wb_conc_mark: return true;
1924 default : return false;
1925 }
1926 }
1927
1928 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1929 switch (cause) {
1930 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1931 case GCCause::_g1_humongous_allocation: return true;
1932 default: return is_user_requested_concurrent_full_gc(cause);
1933 }
1934 }
1935
1936 #ifndef PRODUCT
1937 void G1CollectedHeap::allocate_dummy_regions() {
1938 // Let's fill up most of the region
1939 size_t word_size = HeapRegion::GrainWords - 1024;
1940 // And as a result the region we'll allocate will be humongous.
1941 guarantee(is_humongous(word_size), "sanity");
1942
1943 // _filler_array_max_size is set to humongous object threshold
1944 // but temporarily change it to use CollectedHeap::fill_with_object().
1945 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1946
1947 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1948 // Let's use the existing mechanism for the allocation
1949 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1950 if (dummy_obj != NULL) {
1951 MemRegion mr(dummy_obj, word_size);
1952 CollectedHeap::fill_with_object(mr);
1953 } else {
1954 // If we can't allocate once, we probably cannot allocate
1955 // again. Let's get out of the loop.
1956 break;
1957 }
1958 }
1959 }
1960 #endif // !PRODUCT
1961
1962 void G1CollectedHeap::increment_old_marking_cycles_started() {
1963 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1964 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1965 "Wrong marking cycle count (started: %d, completed: %d)",
1966 _old_marking_cycles_started, _old_marking_cycles_completed);
1967
1968 _old_marking_cycles_started++;
1969 }
1970
1971 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
1972 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1973
1974 // We assume that if concurrent == true, then the caller is a
1975 // concurrent thread that was joined the Suspendible Thread
1976 // Set. If there's ever a cheap way to check this, we should add an
1977 // assert here.
1978
1979 // Given that this method is called at the end of a Full GC or of a
1980 // concurrent cycle, and those can be nested (i.e., a Full GC can
1981 // interrupt a concurrent cycle), the number of full collections
1982 // completed should be either one (in the case where there was no
1983 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1984 // behind the number of full collections started.
1985
1986 // This is the case for the inner caller, i.e. a Full GC.
1987 assert(concurrent ||
1988 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1989 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1990 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1991 "is inconsistent with _old_marking_cycles_completed = %u",
1992 _old_marking_cycles_started, _old_marking_cycles_completed);
1993
1994 // This is the case for the outer caller, i.e. the concurrent cycle.
1995 assert(!concurrent ||
1996 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1997 "for outer caller (concurrent cycle): "
1998 "_old_marking_cycles_started = %u "
1999 "is inconsistent with _old_marking_cycles_completed = %u",
2000 _old_marking_cycles_started, _old_marking_cycles_completed);
2001
2002 _old_marking_cycles_completed += 1;
2003
2004 // We need to clear the "in_progress" flag in the CM thread before
2005 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2006 // is set) so that if a waiter requests another System.gc() it doesn't
2007 // incorrectly see that a marking cycle is still in progress.
2008 if (concurrent) {
2009 _cm_thread->set_idle();
2010 }
2011
2012 // This notify_all() will ensure that a thread that called
2013 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2014 // and it's waiting for a full GC to finish will be woken up. It is
2015 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2016 FullGCCount_lock->notify_all();
2017 }
2018
2019 void G1CollectedHeap::collect(GCCause::Cause cause) {
2020 assert_heap_not_locked();
2021
2022 uint gc_count_before;
2023 uint old_marking_count_before;
2024 uint full_gc_count_before;
2025 bool retry_gc;
2026
2027 do {
2028 retry_gc = false;
2029
2030 {
2031 MutexLocker ml(Heap_lock);
2032
2033 // Read the GC count while holding the Heap_lock
2034 gc_count_before = total_collections();
2035 full_gc_count_before = total_full_collections();
2036 old_marking_count_before = _old_marking_cycles_started;
2037 }
2038
2039 if (should_do_concurrent_full_gc(cause)) {
2040 // Schedule an initial-mark evacuation pause that will start a
2041 // concurrent cycle. We're setting word_size to 0 which means that
2042 // we are not requesting a post-GC allocation.
2043 VM_G1CollectForAllocation op(0, /* word_size */
2044 gc_count_before,
2045 cause,
2046 true, /* should_initiate_conc_mark */
2047 g1_policy()->max_pause_time_ms());
2048 VMThread::execute(&op);
2049 if (!op.pause_succeeded()) {
2050 if (old_marking_count_before == _old_marking_cycles_started) {
2051 retry_gc = op.should_retry_gc();
2052 } else {
2053 // A Full GC happened while we were trying to schedule the
2054 // initial-mark GC. No point in starting a new cycle given
2055 // that the whole heap was collected anyway.
2056 }
2057
2058 if (retry_gc) {
2059 if (GCLocker::is_active_and_needs_gc()) {
2060 GCLocker::stall_until_clear();
2061 }
2062 }
2063 }
2064 } else {
2065 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2066 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2067
2068 // Schedule a standard evacuation pause. We're setting word_size
2069 // to 0 which means that we are not requesting a post-GC allocation.
2070 VM_G1CollectForAllocation op(0, /* word_size */
2071 gc_count_before,
2072 cause,
2073 false, /* should_initiate_conc_mark */
2074 g1_policy()->max_pause_time_ms());
2075 VMThread::execute(&op);
2076 } else {
2077 // Schedule a Full GC.
2078 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2079 VMThread::execute(&op);
2080 }
2081 }
2082 } while (retry_gc);
2083 }
2084
2085 bool G1CollectedHeap::is_in(const void* p) const {
2086 if (_hrm.reserved().contains(p)) {
2087 // Given that we know that p is in the reserved space,
2088 // heap_region_containing() should successfully
2089 // return the containing region.
2090 HeapRegion* hr = heap_region_containing(p);
2091 return hr->is_in(p);
2092 } else {
2093 return false;
2094 }
2095 }
2096
2097 #ifdef ASSERT
2098 bool G1CollectedHeap::is_in_exact(const void* p) const {
2099 bool contains = reserved_region().contains(p);
2100 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2101 if (contains && available) {
2102 return true;
2103 } else {
2104 return false;
2105 }
2106 }
2107 #endif
2108
2109 // Iteration functions.
2110
2111 // Iterates an ObjectClosure over all objects within a HeapRegion.
2112
2113 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2114 ObjectClosure* _cl;
2115 public:
2116 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2117 bool do_heap_region(HeapRegion* r) {
2118 if (!r->is_continues_humongous()) {
2119 r->object_iterate(_cl);
2120 }
2121 return false;
2122 }
2123 };
2124
2125 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2126 IterateObjectClosureRegionClosure blk(cl);
2127 heap_region_iterate(&blk);
2128 }
2129
2130 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2131 _hrm.iterate(cl);
2132 }
2133
2134 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2135 HeapRegionClaimer *hrclaimer,
2136 uint worker_id) const {
2137 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2138 }
2139
2140 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2141 HeapRegionClaimer *hrclaimer) const {
2142 _hrm.par_iterate(cl, hrclaimer, 0);
2143 }
2144
2145 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2146 _collection_set.iterate(cl);
2147 }
2148
2149 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2150 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2151 }
2152
2153 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2154 HeapRegion* hr = heap_region_containing(addr);
2155 return hr->block_start(addr);
2156 }
2157
2158 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2159 HeapRegion* hr = heap_region_containing(addr);
2160 return hr->block_size(addr);
2161 }
2162
2163 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2164 HeapRegion* hr = heap_region_containing(addr);
2165 return hr->block_is_obj(addr);
2166 }
2167
2168 bool G1CollectedHeap::supports_tlab_allocation() const {
2169 return true;
2170 }
2171
2172 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2173 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2174 }
2175
2176 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2177 return _eden.length() * HeapRegion::GrainBytes;
2178 }
2179
2180 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2181 // must be equal to the humongous object limit.
2182 size_t G1CollectedHeap::max_tlab_size() const {
2183 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2184 }
2185
2186 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2187 return _allocator->unsafe_max_tlab_alloc();
2188 }
2189
2190 size_t G1CollectedHeap::max_capacity() const {
2191 return _hrm.reserved().byte_size();
2192 }
2193
2194 jlong G1CollectedHeap::millis_since_last_gc() {
2195 // See the notes in GenCollectedHeap::millis_since_last_gc()
2196 // for more information about the implementation.
2197 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2198 _g1_policy->collection_pause_end_millis();
2199 if (ret_val < 0) {
2200 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2201 ". returning zero instead.", ret_val);
2202 return 0;
2203 }
2204 return ret_val;
2205 }
2206
2207 void G1CollectedHeap::deduplicate_string(oop str) {
2208 assert(java_lang_String::is_instance(str), "invariant");
2209
2210 if (G1StringDedup::is_enabled()) {
2211 G1StringDedup::deduplicate(str);
2212 }
2213 }
2214
2215 void G1CollectedHeap::prepare_for_verify() {
2216 _verifier->prepare_for_verify();
2217 }
2218
2219 void G1CollectedHeap::verify(VerifyOption vo) {
2220 _verifier->verify(vo);
2221 }
2222
2223 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2224 return true;
2225 }
2226
2227 const char* const* G1CollectedHeap::concurrent_phases() const {
2228 return _cm_thread->concurrent_phases();
2229 }
2230
2231 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2232 return _cm_thread->request_concurrent_phase(phase);
2233 }
2234
2235 class PrintRegionClosure: public HeapRegionClosure {
2236 outputStream* _st;
2237 public:
2238 PrintRegionClosure(outputStream* st) : _st(st) {}
2239 bool do_heap_region(HeapRegion* r) {
2240 r->print_on(_st);
2241 return false;
2242 }
2243 };
2244
2245 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2246 const HeapRegion* hr,
2247 const VerifyOption vo) const {
2248 switch (vo) {
2249 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2250 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2251 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2252 default: ShouldNotReachHere();
2253 }
2254 return false; // keep some compilers happy
2255 }
2256
2257 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2258 const VerifyOption vo) const {
2259 switch (vo) {
2260 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2261 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2262 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2263 default: ShouldNotReachHere();
2264 }
2265 return false; // keep some compilers happy
2266 }
2267
2268 void G1CollectedHeap::print_heap_regions() const {
2269 LogTarget(Trace, gc, heap, region) lt;
2270 if (lt.is_enabled()) {
2271 LogStream ls(lt);
2272 print_regions_on(&ls);
2273 }
2274 }
2275
2276 void G1CollectedHeap::print_on(outputStream* st) const {
2277 st->print(" %-20s", "garbage-first heap");
2278 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2279 capacity()/K, used_unlocked()/K);
2280 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2281 p2i(_hrm.reserved().start()),
2282 p2i(_hrm.reserved().end()));
2283 st->cr();
2284 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2285 uint young_regions = young_regions_count();
2286 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2287 (size_t) young_regions * HeapRegion::GrainBytes / K);
2288 uint survivor_regions = survivor_regions_count();
2289 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2290 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2291 st->cr();
2292 MetaspaceUtils::print_on(st);
2293 }
2294
2295 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2296 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2297 "HS=humongous(starts), HC=humongous(continues), "
2298 "CS=collection set, F=free, A=archive, "
2299 "TAMS=top-at-mark-start (previous, next)");
2300 PrintRegionClosure blk(st);
2301 heap_region_iterate(&blk);
2302 }
2303
2304 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2305 print_on(st);
2306
2307 // Print the per-region information.
2308 print_regions_on(st);
2309 }
2310
2311 void G1CollectedHeap::print_on_error(outputStream* st) const {
2312 this->CollectedHeap::print_on_error(st);
2313
2314 if (_cm != NULL) {
2315 st->cr();
2316 _cm->print_on_error(st);
2317 }
2318 }
2319
2320 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2321 workers()->print_worker_threads_on(st);
2322 _cm_thread->print_on(st);
2323 st->cr();
2324 _cm->print_worker_threads_on(st);
2325 _cr->print_threads_on(st);
2326 _young_gen_sampling_thread->print_on(st);
2327 if (G1StringDedup::is_enabled()) {
2328 G1StringDedup::print_worker_threads_on(st);
2329 }
2330 }
2331
2332 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2333 workers()->threads_do(tc);
2334 tc->do_thread(_cm_thread);
2335 _cm->threads_do(tc);
2336 _cr->threads_do(tc);
2337 tc->do_thread(_young_gen_sampling_thread);
2338 if (G1StringDedup::is_enabled()) {
2339 G1StringDedup::threads_do(tc);
2340 }
2341 }
2342
2343 void G1CollectedHeap::print_tracing_info() const {
2344 g1_rem_set()->print_summary_info();
2345 concurrent_mark()->print_summary_info();
2346 }
2347
2348 #ifndef PRODUCT
2349 // Helpful for debugging RSet issues.
2350
2351 class PrintRSetsClosure : public HeapRegionClosure {
2352 private:
2353 const char* _msg;
2354 size_t _occupied_sum;
2355
2356 public:
2357 bool do_heap_region(HeapRegion* r) {
2358 HeapRegionRemSet* hrrs = r->rem_set();
2359 size_t occupied = hrrs->occupied();
2360 _occupied_sum += occupied;
2361
2362 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2363 if (occupied == 0) {
2364 tty->print_cr(" RSet is empty");
2365 } else {
2366 hrrs->print();
2367 }
2368 tty->print_cr("----------");
2369 return false;
2370 }
2371
2372 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2373 tty->cr();
2374 tty->print_cr("========================================");
2375 tty->print_cr("%s", msg);
2376 tty->cr();
2377 }
2378
2379 ~PrintRSetsClosure() {
2380 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2381 tty->print_cr("========================================");
2382 tty->cr();
2383 }
2384 };
2385
2386 void G1CollectedHeap::print_cset_rsets() {
2387 PrintRSetsClosure cl("Printing CSet RSets");
2388 collection_set_iterate(&cl);
2389 }
2390
2391 void G1CollectedHeap::print_all_rsets() {
2392 PrintRSetsClosure cl("Printing All RSets");;
2393 heap_region_iterate(&cl);
2394 }
2395 #endif // PRODUCT
2396
2397 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2398
2399 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2400 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2401 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2402
2403 size_t eden_capacity_bytes =
2404 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2405
2406 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2407 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2408 eden_capacity_bytes, survivor_used_bytes, num_regions());
2409 }
2410
2411 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2412 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2413 stats->unused(), stats->used(), stats->region_end_waste(),
2414 stats->regions_filled(), stats->direct_allocated(),
2415 stats->failure_used(), stats->failure_waste());
2416 }
2417
2418 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2419 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2420 gc_tracer->report_gc_heap_summary(when, heap_summary);
2421
2422 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2423 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2424 }
2425
2426 G1CollectedHeap* G1CollectedHeap::heap() {
2427 CollectedHeap* heap = Universe::heap();
2428 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2429 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2430 return (G1CollectedHeap*)heap;
2431 }
2432
2433 void G1CollectedHeap::gc_prologue(bool full) {
2434 // always_do_update_barrier = false;
2435 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2436
2437 // This summary needs to be printed before incrementing total collections.
2438 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2439
2440 // Update common counters.
2441 increment_total_collections(full /* full gc */);
2442 if (full) {
2443 increment_old_marking_cycles_started();
2444 }
2445
2446 // Fill TLAB's and such
2447 double start = os::elapsedTime();
2448 accumulate_statistics_all_tlabs();
2449 ensure_parsability(true);
2450 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2451 }
2452
2453 void G1CollectedHeap::gc_epilogue(bool full) {
2454 // Update common counters.
2455 if (full) {
2456 // Update the number of full collections that have been completed.
2457 increment_old_marking_cycles_completed(false /* concurrent */);
2458 }
2459
2460 // We are at the end of the GC. Total collections has already been increased.
2461 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2462
2463 // FIXME: what is this about?
2464 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2465 // is set.
2466 #if COMPILER2_OR_JVMCI
2467 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2468 #endif
2469 // always_do_update_barrier = true;
2470
2471 double start = os::elapsedTime();
2472 resize_all_tlabs();
2473 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2474
2475 MemoryService::track_memory_usage();
2476 // We have just completed a GC. Update the soft reference
2477 // policy with the new heap occupancy
2478 Universe::update_heap_info_at_gc();
2479 }
2480
2481 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2482 uint gc_count_before,
2483 bool* succeeded,
2484 GCCause::Cause gc_cause) {
2485 assert_heap_not_locked_and_not_at_safepoint();
2486 VM_G1CollectForAllocation op(word_size,
2487 gc_count_before,
2488 gc_cause,
2489 false, /* should_initiate_conc_mark */
2490 g1_policy()->max_pause_time_ms());
2491 VMThread::execute(&op);
2492
2493 HeapWord* result = op.result();
2494 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2495 assert(result == NULL || ret_succeeded,
2496 "the result should be NULL if the VM did not succeed");
2497 *succeeded = ret_succeeded;
2498
2499 assert_heap_not_locked();
2500 return result;
2501 }
2502
2503 void G1CollectedHeap::do_concurrent_mark() {
2504 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2505 if (!_cm_thread->in_progress()) {
2506 _cm_thread->set_started();
2507 CGC_lock->notify();
2508 }
2509 }
2510
2511 size_t G1CollectedHeap::pending_card_num() {
2512 size_t extra_cards = 0;
2513 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2514 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2515 extra_cards += dcq.size();
2516 }
2517 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2518 size_t buffer_size = dcqs.buffer_size();
2519 size_t buffer_num = dcqs.completed_buffers_num();
2520
2521 return buffer_size * buffer_num + extra_cards;
2522 }
2523
2524 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2525 // We don't nominate objects with many remembered set entries, on
2526 // the assumption that such objects are likely still live.
2527 HeapRegionRemSet* rem_set = r->rem_set();
2528
2529 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2530 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2531 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2532 }
2533
2534 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2535 private:
2536 size_t _total_humongous;
2537 size_t _candidate_humongous;
2538
2539 DirtyCardQueue _dcq;
2540
2541 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2542 assert(region->is_starts_humongous(), "Must start a humongous object");
2543
2544 oop obj = oop(region->bottom());
2545
2546 // Dead objects cannot be eager reclaim candidates. Due to class
2547 // unloading it is unsafe to query their classes so we return early.
2548 if (g1h->is_obj_dead(obj, region)) {
2549 return false;
2550 }
2551
2552 // If we do not have a complete remembered set for the region, then we can
2553 // not be sure that we have all references to it.
2554 if (!region->rem_set()->is_complete()) {
2555 return false;
2556 }
2557 // Candidate selection must satisfy the following constraints
2558 // while concurrent marking is in progress:
2559 //
2560 // * In order to maintain SATB invariants, an object must not be
2561 // reclaimed if it was allocated before the start of marking and
2562 // has not had its references scanned. Such an object must have
2563 // its references (including type metadata) scanned to ensure no
2564 // live objects are missed by the marking process. Objects
2565 // allocated after the start of concurrent marking don't need to
2566 // be scanned.
2567 //
2568 // * An object must not be reclaimed if it is on the concurrent
2569 // mark stack. Objects allocated after the start of concurrent
2570 // marking are never pushed on the mark stack.
2571 //
2572 // Nominating only objects allocated after the start of concurrent
2573 // marking is sufficient to meet both constraints. This may miss
2574 // some objects that satisfy the constraints, but the marking data
2575 // structures don't support efficiently performing the needed
2576 // additional tests or scrubbing of the mark stack.
2577 //
2578 // However, we presently only nominate is_typeArray() objects.
2579 // A humongous object containing references induces remembered
2580 // set entries on other regions. In order to reclaim such an
2581 // object, those remembered sets would need to be cleaned up.
2582 //
2583 // We also treat is_typeArray() objects specially, allowing them
2584 // to be reclaimed even if allocated before the start of
2585 // concurrent mark. For this we rely on mark stack insertion to
2586 // exclude is_typeArray() objects, preventing reclaiming an object
2587 // that is in the mark stack. We also rely on the metadata for
2588 // such objects to be built-in and so ensured to be kept live.
2589 // Frequent allocation and drop of large binary blobs is an
2590 // important use case for eager reclaim, and this special handling
2591 // may reduce needed headroom.
2592
2593 return obj->is_typeArray() &&
2594 g1h->is_potential_eager_reclaim_candidate(region);
2595 }
2596
2597 public:
2598 RegisterHumongousWithInCSetFastTestClosure()
2599 : _total_humongous(0),
2600 _candidate_humongous(0),
2601 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2602 }
2603
2604 virtual bool do_heap_region(HeapRegion* r) {
2605 if (!r->is_starts_humongous()) {
2606 return false;
2607 }
2608 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2609
2610 bool is_candidate = humongous_region_is_candidate(g1h, r);
2611 uint rindex = r->hrm_index();
2612 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2613 if (is_candidate) {
2614 _candidate_humongous++;
2615 g1h->register_humongous_region_with_cset(rindex);
2616 // Is_candidate already filters out humongous object with large remembered sets.
2617 // If we have a humongous object with a few remembered sets, we simply flush these
2618 // remembered set entries into the DCQS. That will result in automatic
2619 // re-evaluation of their remembered set entries during the following evacuation
2620 // phase.
2621 if (!r->rem_set()->is_empty()) {
2622 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2623 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2624 G1CardTable* ct = g1h->card_table();
2625 HeapRegionRemSetIterator hrrs(r->rem_set());
2626 size_t card_index;
2627 while (hrrs.has_next(card_index)) {
2628 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2629 // The remembered set might contain references to already freed
2630 // regions. Filter out such entries to avoid failing card table
2631 // verification.
2632 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2633 if (*card_ptr != G1CardTable::dirty_card_val()) {
2634 *card_ptr = G1CardTable::dirty_card_val();
2635 _dcq.enqueue(card_ptr);
2636 }
2637 }
2638 }
2639 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2640 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2641 hrrs.n_yielded(), r->rem_set()->occupied());
2642 // We should only clear the card based remembered set here as we will not
2643 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2644 // (and probably never) we do not enter this path if there are other kind of
2645 // remembered sets for this region.
2646 r->rem_set()->clear_locked(true /* only_cardset */);
2647 // Clear_locked() above sets the state to Empty. However we want to continue
2648 // collecting remembered set entries for humongous regions that were not
2649 // reclaimed.
2650 r->rem_set()->set_state_complete();
2651 }
2652 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2653 }
2654 _total_humongous++;
2655
2656 return false;
2657 }
2658
2659 size_t total_humongous() const { return _total_humongous; }
2660 size_t candidate_humongous() const { return _candidate_humongous; }
2661
2662 void flush_rem_set_entries() { _dcq.flush(); }
2663 };
2664
2665 void G1CollectedHeap::register_humongous_regions_with_cset() {
2666 if (!G1EagerReclaimHumongousObjects) {
2667 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2668 return;
2669 }
2670 double time = os::elapsed_counter();
2671
2672 // Collect reclaim candidate information and register candidates with cset.
2673 RegisterHumongousWithInCSetFastTestClosure cl;
2674 heap_region_iterate(&cl);
2675
2676 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2677 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2678 cl.total_humongous(),
2679 cl.candidate_humongous());
2680 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2681
2682 // Finally flush all remembered set entries to re-check into the global DCQS.
2683 cl.flush_rem_set_entries();
2684 }
2685
2686 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2687 public:
2688 bool do_heap_region(HeapRegion* hr) {
2689 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2690 hr->verify_rem_set();
2691 }
2692 return false;
2693 }
2694 };
2695
2696 uint G1CollectedHeap::num_task_queues() const {
2697 return _task_queues->size();
2698 }
2699
2700 #if TASKQUEUE_STATS
2701 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2702 st->print_raw_cr("GC Task Stats");
2703 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2704 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2705 }
2706
2707 void G1CollectedHeap::print_taskqueue_stats() const {
2708 if (!log_is_enabled(Trace, gc, task, stats)) {
2709 return;
2710 }
2711 Log(gc, task, stats) log;
2712 ResourceMark rm;
2713 LogStream ls(log.trace());
2714 outputStream* st = &ls;
2715
2716 print_taskqueue_stats_hdr(st);
2717
2718 TaskQueueStats totals;
2719 const uint n = num_task_queues();
2720 for (uint i = 0; i < n; ++i) {
2721 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2722 totals += task_queue(i)->stats;
2723 }
2724 st->print_raw("tot "); totals.print(st); st->cr();
2725
2726 DEBUG_ONLY(totals.verify());
2727 }
2728
2729 void G1CollectedHeap::reset_taskqueue_stats() {
2730 const uint n = num_task_queues();
2731 for (uint i = 0; i < n; ++i) {
2732 task_queue(i)->stats.reset();
2733 }
2734 }
2735 #endif // TASKQUEUE_STATS
2736
2737 void G1CollectedHeap::wait_for_root_region_scanning() {
2738 double scan_wait_start = os::elapsedTime();
2739 // We have to wait until the CM threads finish scanning the
2740 // root regions as it's the only way to ensure that all the
2741 // objects on them have been correctly scanned before we start
2742 // moving them during the GC.
2743 bool waited = _cm->root_regions()->wait_until_scan_finished();
2744 double wait_time_ms = 0.0;
2745 if (waited) {
2746 double scan_wait_end = os::elapsedTime();
2747 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2748 }
2749 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2750 }
2751
2752 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2753 private:
2754 G1HRPrinter* _hr_printer;
2755 public:
2756 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2757
2758 virtual bool do_heap_region(HeapRegion* r) {
2759 _hr_printer->cset(r);
2760 return false;
2761 }
2762 };
2763
2764 void G1CollectedHeap::start_new_collection_set() {
2765 collection_set()->start_incremental_building();
2766
2767 clear_cset_fast_test();
2768
2769 guarantee(_eden.length() == 0, "eden should have been cleared");
2770 g1_policy()->transfer_survivors_to_cset(survivor());
2771 }
2772
2773 bool
2774 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2775 assert_at_safepoint_on_vm_thread();
2776 guarantee(!is_gc_active(), "collection is not reentrant");
2777
2778 if (GCLocker::check_active_before_gc()) {
2779 return false;
2780 }
2781
2782 _gc_timer_stw->register_gc_start();
2783
2784 GCIdMark gc_id_mark;
2785 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2786
2787 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2788 ResourceMark rm;
2789
2790 g1_policy()->note_gc_start();
2791
2792 wait_for_root_region_scanning();
2793
2794 print_heap_before_gc();
2795 print_heap_regions();
2796 trace_heap_before_gc(_gc_tracer_stw);
2797
2798 _verifier->verify_region_sets_optional();
2799 _verifier->verify_dirty_young_regions();
2800
2801 // We should not be doing initial mark unless the conc mark thread is running
2802 if (!_cm_thread->should_terminate()) {
2803 // This call will decide whether this pause is an initial-mark
2804 // pause. If it is, in_initial_mark_gc() will return true
2805 // for the duration of this pause.
2806 g1_policy()->decide_on_conc_mark_initiation();
2807 }
2808
2809 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2810 assert(!collector_state()->in_initial_mark_gc() ||
2811 collector_state()->in_young_only_phase(), "sanity");
2812
2813 // We also do not allow mixed GCs during marking.
2814 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2815
2816 // Record whether this pause is an initial mark. When the current
2817 // thread has completed its logging output and it's safe to signal
2818 // the CM thread, the flag's value in the policy has been reset.
2819 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2820
2821 // Inner scope for scope based logging, timers, and stats collection
2822 {
2823 EvacuationInfo evacuation_info;
2824
2825 if (collector_state()->in_initial_mark_gc()) {
2826 // We are about to start a marking cycle, so we increment the
2827 // full collection counter.
2828 increment_old_marking_cycles_started();
2829 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2830 }
2831
2832 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2833
2834 GCTraceCPUTime tcpu;
2835
2836 G1HeapVerifier::G1VerifyType verify_type;
2837 FormatBuffer<> gc_string("Pause Young ");
2838 if (collector_state()->in_initial_mark_gc()) {
2839 gc_string.append("(Concurrent Start)");
2840 verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2841 } else if (collector_state()->in_young_only_phase()) {
2842 if (collector_state()->in_young_gc_before_mixed()) {
2843 gc_string.append("(Prepare Mixed)");
2844 } else {
2845 gc_string.append("(Normal)");
2846 }
2847 verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2848 } else {
2849 gc_string.append("(Mixed)");
2850 verify_type = G1HeapVerifier::G1VerifyMixed;
2851 }
2852 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2853
2854 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2855 workers()->active_workers(),
2856 Threads::number_of_non_daemon_threads());
2857 active_workers = workers()->update_active_workers(active_workers);
2858 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2859
2860 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2861 TraceMemoryManagerStats tms(&_memory_manager, gc_cause(),
2862 collector_state()->yc_type() == Mixed /* allMemoryPoolsAffected */);
2863
2864 G1HeapTransition heap_transition(this);
2865 size_t heap_used_bytes_before_gc = used();
2866
2867 // Don't dynamically change the number of GC threads this early. A value of
2868 // 0 is used to indicate serial work. When parallel work is done,
2869 // it will be set.
2870
2871 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2872 IsGCActiveMark x;
2873
2874 gc_prologue(false);
2875
2876 if (VerifyRememberedSets) {
2877 log_info(gc, verify)("[Verifying RemSets before GC]");
2878 VerifyRegionRemSetClosure v_cl;
2879 heap_region_iterate(&v_cl);
2880 }
2881
2882 _verifier->verify_before_gc(verify_type);
2883
2884 _verifier->check_bitmaps("GC Start");
2885
2886 #if COMPILER2_OR_JVMCI
2887 DerivedPointerTable::clear();
2888 #endif
2889
2890 // Please see comment in g1CollectedHeap.hpp and
2891 // G1CollectedHeap::ref_processing_init() to see how
2892 // reference processing currently works in G1.
2893
2894 // Enable discovery in the STW reference processor
2895 _ref_processor_stw->enable_discovery();
2896
2897 {
2898 // We want to temporarily turn off discovery by the
2899 // CM ref processor, if necessary, and turn it back on
2900 // on again later if we do. Using a scoped
2901 // NoRefDiscovery object will do this.
2902 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2903
2904 // Forget the current alloc region (we might even choose it to be part
2905 // of the collection set!).
2906 _allocator->release_mutator_alloc_region();
2907
2908 // This timing is only used by the ergonomics to handle our pause target.
2909 // It is unclear why this should not include the full pause. We will
2910 // investigate this in CR 7178365.
2911 //
2912 // Preserving the old comment here if that helps the investigation:
2913 //
2914 // The elapsed time induced by the start time below deliberately elides
2915 // the possible verification above.
2916 double sample_start_time_sec = os::elapsedTime();
2917
2918 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2919
2920 if (collector_state()->in_initial_mark_gc()) {
2921 concurrent_mark()->pre_initial_mark();
2922 }
2923
2924 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2925
2926 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2927
2928 // Make sure the remembered sets are up to date. This needs to be
2929 // done before register_humongous_regions_with_cset(), because the
2930 // remembered sets are used there to choose eager reclaim candidates.
2931 // If the remembered sets are not up to date we might miss some
2932 // entries that need to be handled.
2933 g1_rem_set()->cleanupHRRS();
2934
2935 register_humongous_regions_with_cset();
2936
2937 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2938
2939 // We call this after finalize_cset() to
2940 // ensure that the CSet has been finalized.
2941 _cm->verify_no_cset_oops();
2942
2943 if (_hr_printer.is_active()) {
2944 G1PrintCollectionSetClosure cl(&_hr_printer);
2945 _collection_set.iterate(&cl);
2946 }
2947
2948 // Initialize the GC alloc regions.
2949 _allocator->init_gc_alloc_regions(evacuation_info);
2950
2951 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2952 pre_evacuate_collection_set();
2953
2954 // Actually do the work...
2955 evacuate_collection_set(&per_thread_states);
2956
2957 post_evacuate_collection_set(evacuation_info, &per_thread_states);
2958
2959 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2960 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2961
2962 eagerly_reclaim_humongous_regions();
2963
2964 record_obj_copy_mem_stats();
2965 _survivor_evac_stats.adjust_desired_plab_sz();
2966 _old_evac_stats.adjust_desired_plab_sz();
2967
2968 double start = os::elapsedTime();
2969 start_new_collection_set();
2970 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2971
2972 if (evacuation_failed()) {
2973 set_used(recalculate_used());
2974 if (_archive_allocator != NULL) {
2975 _archive_allocator->clear_used();
2976 }
2977 for (uint i = 0; i < ParallelGCThreads; i++) {
2978 if (_evacuation_failed_info_array[i].has_failed()) {
2979 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
2980 }
2981 }
2982 } else {
2983 // The "used" of the the collection set have already been subtracted
2984 // when they were freed. Add in the bytes evacuated.
2985 increase_used(g1_policy()->bytes_copied_during_gc());
2986 }
2987
2988 if (collector_state()->in_initial_mark_gc()) {
2989 // We have to do this before we notify the CM threads that
2990 // they can start working to make sure that all the
2991 // appropriate initialization is done on the CM object.
2992 concurrent_mark()->post_initial_mark();
2993 // Note that we don't actually trigger the CM thread at
2994 // this point. We do that later when we're sure that
2995 // the current thread has completed its logging output.
2996 }
2997
2998 allocate_dummy_regions();
2999
3000 _allocator->init_mutator_alloc_region();
3001
3002 {
3003 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3004 if (expand_bytes > 0) {
3005 size_t bytes_before = capacity();
3006 // No need for an ergo logging here,
3007 // expansion_amount() does this when it returns a value > 0.
3008 double expand_ms;
3009 if (!expand(expand_bytes, _workers, &expand_ms)) {
3010 // We failed to expand the heap. Cannot do anything about it.
3011 }
3012 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3013 }
3014 }
3015
3016 // We redo the verification but now wrt to the new CSet which
3017 // has just got initialized after the previous CSet was freed.
3018 _cm->verify_no_cset_oops();
3019
3020 // This timing is only used by the ergonomics to handle our pause target.
3021 // It is unclear why this should not include the full pause. We will
3022 // investigate this in CR 7178365.
3023 double sample_end_time_sec = os::elapsedTime();
3024 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3025 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3026 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3027
3028 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3029 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3030
3031 if (VerifyRememberedSets) {
3032 log_info(gc, verify)("[Verifying RemSets after GC]");
3033 VerifyRegionRemSetClosure v_cl;
3034 heap_region_iterate(&v_cl);
3035 }
3036
3037 _verifier->verify_after_gc(verify_type);
3038 _verifier->check_bitmaps("GC End");
3039
3040 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3041 _ref_processor_stw->verify_no_references_recorded();
3042
3043 // CM reference discovery will be re-enabled if necessary.
3044 }
3045
3046 #ifdef TRACESPINNING
3047 ParallelTaskTerminator::print_termination_counts();
3048 #endif
3049
3050 gc_epilogue(false);
3051 }
3052
3053 // Print the remainder of the GC log output.
3054 if (evacuation_failed()) {
3055 log_info(gc)("To-space exhausted");
3056 }
3057
3058 g1_policy()->print_phases();
3059 heap_transition.print();
3060
3061 // It is not yet to safe to tell the concurrent mark to
3062 // start as we have some optional output below. We don't want the
3063 // output from the concurrent mark thread interfering with this
3064 // logging output either.
3065
3066 _hrm.verify_optional();
3067 _verifier->verify_region_sets_optional();
3068
3069 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3070 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3071
3072 print_heap_after_gc();
3073 print_heap_regions();
3074 trace_heap_after_gc(_gc_tracer_stw);
3075
3076 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3077 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3078 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3079 // before any GC notifications are raised.
3080 g1mm()->update_sizes();
3081
3082 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3083 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3084 _gc_timer_stw->register_gc_end();
3085 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3086 }
3087 // It should now be safe to tell the concurrent mark thread to start
3088 // without its logging output interfering with the logging output
3089 // that came from the pause.
3090
3091 if (should_start_conc_mark) {
3092 // CAUTION: after the doConcurrentMark() call below,
3093 // the concurrent marking thread(s) could be running
3094 // concurrently with us. Make sure that anything after
3095 // this point does not assume that we are the only GC thread
3096 // running. Note: of course, the actual marking work will
3097 // not start until the safepoint itself is released in
3098 // SuspendibleThreadSet::desynchronize().
3099 do_concurrent_mark();
3100 }
3101
3102 return true;
3103 }
3104
3105 void G1CollectedHeap::remove_self_forwarding_pointers() {
3106 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3107 workers()->run_task(&rsfp_task);
3108 }
3109
3110 void G1CollectedHeap::restore_after_evac_failure() {
3111 double remove_self_forwards_start = os::elapsedTime();
3112
3113 remove_self_forwarding_pointers();
3114 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3115 _preserved_marks_set.restore(&task_executor);
3116
3117 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3118 }
3119
3120 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3121 if (!_evacuation_failed) {
3122 _evacuation_failed = true;
3123 }
3124
3125 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3126 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3127 }
3128
3129 bool G1ParEvacuateFollowersClosure::offer_termination() {
3130 G1ParScanThreadState* const pss = par_scan_state();
3131 start_term_time();
3132 const bool res = terminator()->offer_termination();
3133 end_term_time();
3134 return res;
3135 }
3136
3137 void G1ParEvacuateFollowersClosure::do_void() {
3138 G1ParScanThreadState* const pss = par_scan_state();
3139 pss->trim_queue();
3140 do {
3141 pss->steal_and_trim_queue(queues());
3142 } while (!offer_termination());
3143 }
3144
3145 class G1ParTask : public AbstractGangTask {
3146 protected:
3147 G1CollectedHeap* _g1h;
3148 G1ParScanThreadStateSet* _pss;
3149 RefToScanQueueSet* _queues;
3150 G1RootProcessor* _root_processor;
3151 ParallelTaskTerminator _terminator;
3152 uint _n_workers;
3153
3154 public:
3155 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3156 : AbstractGangTask("G1 collection"),
3157 _g1h(g1h),
3158 _pss(per_thread_states),
3159 _queues(task_queues),
3160 _root_processor(root_processor),
3161 _terminator(n_workers, _queues),
3162 _n_workers(n_workers)
3163 {}
3164
3165 void work(uint worker_id) {
3166 if (worker_id >= _n_workers) return; // no work needed this round
3167
3168 double start_sec = os::elapsedTime();
3169 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3170
3171 {
3172 ResourceMark rm;
3173 HandleMark hm;
3174
3175 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3176
3177 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3178 pss->set_ref_discoverer(rp);
3179
3180 double start_strong_roots_sec = os::elapsedTime();
3181
3182 _root_processor->evacuate_roots(pss, worker_id);
3183
3184 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3185 // treating the nmethods visited to act as roots for concurrent marking.
3186 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3187 // objects copied by the current evacuation.
3188 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3189
3190 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3191
3192 double term_sec = 0.0;
3193 size_t evac_term_attempts = 0;
3194 {
3195 double start = os::elapsedTime();
3196 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3197 evac.do_void();
3198
3199 evac_term_attempts = evac.term_attempts();
3200 term_sec = evac.term_time();
3201 double elapsed_sec = os::elapsedTime() - start;
3202
3203 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3204 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3205 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3206 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3207 }
3208
3209 assert(pss->queue_is_empty(), "should be empty");
3210
3211 if (log_is_enabled(Debug, gc, task, stats)) {
3212 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3213 size_t lab_waste;
3214 size_t lab_undo_waste;
3215 pss->waste(lab_waste, lab_undo_waste);
3216 _g1h->print_termination_stats(worker_id,
3217 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3218 strong_roots_sec * 1000.0, /* strong roots time */
3219 term_sec * 1000.0, /* evac term time */
3220 evac_term_attempts, /* evac term attempts */
3221 lab_waste, /* alloc buffer waste */
3222 lab_undo_waste /* undo waste */
3223 );
3224 }
3225
3226 // Close the inner scope so that the ResourceMark and HandleMark
3227 // destructors are executed here and are included as part of the
3228 // "GC Worker Time".
3229 }
3230 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3231 }
3232 };
3233
3234 void G1CollectedHeap::print_termination_stats_hdr() {
3235 log_debug(gc, task, stats)("GC Termination Stats");
3236 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3237 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3238 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3239 }
3240
3241 void G1CollectedHeap::print_termination_stats(uint worker_id,
3242 double elapsed_ms,
3243 double strong_roots_ms,
3244 double term_ms,
3245 size_t term_attempts,
3246 size_t alloc_buffer_waste,
3247 size_t undo_waste) const {
3248 log_debug(gc, task, stats)
3249 ("%3d %9.2f %9.2f %6.2f "
3250 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3251 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3252 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3253 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3254 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3255 alloc_buffer_waste * HeapWordSize / K,
3256 undo_waste * HeapWordSize / K);
3257 }
3258
3259 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3260 private:
3261 BoolObjectClosure* _is_alive;
3262 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3263 OopStorage::ParState<false /* concurrent */, false /* const */> _par_state_string;
3264
3265 int _initial_string_table_size;
3266 int _initial_symbol_table_size;
3267
3268 bool _process_strings;
3269 int _strings_processed;
3270 int _strings_removed;
3271
3272 bool _process_symbols;
3273 int _symbols_processed;
3274 int _symbols_removed;
3275
3276 bool _process_string_dedup;
3277
3278 public:
3279 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3280 AbstractGangTask("String/Symbol Unlinking"),
3281 _is_alive(is_alive),
3282 _dedup_closure(is_alive, NULL, false),
3283 _par_state_string(StringTable::weak_storage()),
3284 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3285 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3286 _process_string_dedup(process_string_dedup) {
3287
3288 _initial_string_table_size = (int) StringTable::the_table()->table_size();
3289 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3290 if (process_symbols) {
3291 SymbolTable::clear_parallel_claimed_index();
3292 }
3293 if (process_strings) {
3294 StringTable::reset_dead_counter();
3295 }
3296 }
3297
3298 ~G1StringAndSymbolCleaningTask() {
3299 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3300 "claim value %d after unlink less than initial symbol table size %d",
3301 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3302
3303 log_info(gc, stringtable)(
3304 "Cleaned string and symbol table, "
3305 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3306 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3307 strings_processed(), strings_removed(),
3308 symbols_processed(), symbols_removed());
3309 if (_process_strings) {
3310 StringTable::finish_dead_counter();
3311 }
3312 }
3313
3314 void work(uint worker_id) {
3315 int strings_processed = 0;
3316 int strings_removed = 0;
3317 int symbols_processed = 0;
3318 int symbols_removed = 0;
3319 if (_process_strings) {
3320 StringTable::possibly_parallel_unlink(&_par_state_string, _is_alive, &strings_processed, &strings_removed);
3321 Atomic::add(strings_processed, &_strings_processed);
3322 Atomic::add(strings_removed, &_strings_removed);
3323 }
3324 if (_process_symbols) {
3325 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3326 Atomic::add(symbols_processed, &_symbols_processed);
3327 Atomic::add(symbols_removed, &_symbols_removed);
3328 }
3329 if (_process_string_dedup) {
3330 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3331 }
3332 }
3333
3334 size_t strings_processed() const { return (size_t)_strings_processed; }
3335 size_t strings_removed() const { return (size_t)_strings_removed; }
3336
3337 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3338 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3339 };
3340
3341 class G1CodeCacheUnloadingTask {
3342 private:
3343 static Monitor* _lock;
3344
3345 BoolObjectClosure* const _is_alive;
3346 const bool _unloading_occurred;
3347 const uint _num_workers;
3348
3349 // Variables used to claim nmethods.
3350 CompiledMethod* _first_nmethod;
3351 CompiledMethod* volatile _claimed_nmethod;
3352
3353 // The list of nmethods that need to be processed by the second pass.
3354 CompiledMethod* volatile _postponed_list;
3355 volatile uint _num_entered_barrier;
3356
3357 public:
3358 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3359 _is_alive(is_alive),
3360 _unloading_occurred(unloading_occurred),
3361 _num_workers(num_workers),
3362 _first_nmethod(NULL),
3363 _claimed_nmethod(NULL),
3364 _postponed_list(NULL),
3365 _num_entered_barrier(0)
3366 {
3367 CompiledMethod::increase_unloading_clock();
3368 // Get first alive nmethod
3369 CompiledMethodIterator iter = CompiledMethodIterator();
3370 if(iter.next_alive()) {
3371 _first_nmethod = iter.method();
3372 }
3373 _claimed_nmethod = _first_nmethod;
3374 }
3375
3376 ~G1CodeCacheUnloadingTask() {
3377 CodeCache::verify_clean_inline_caches();
3378
3379 CodeCache::set_needs_cache_clean(false);
3380 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3381
3382 CodeCache::verify_icholder_relocations();
3383 }
3384
3385 private:
3386 void add_to_postponed_list(CompiledMethod* nm) {
3387 CompiledMethod* old;
3388 do {
3389 old = _postponed_list;
3390 nm->set_unloading_next(old);
3391 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3392 }
3393
3394 void clean_nmethod(CompiledMethod* nm) {
3395 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3396
3397 if (postponed) {
3398 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3399 add_to_postponed_list(nm);
3400 }
3401
3402 // Mark that this nmethod has been cleaned/unloaded.
3403 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3404 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3405 }
3406
3407 void clean_nmethod_postponed(CompiledMethod* nm) {
3408 nm->do_unloading_parallel_postponed();
3409 }
3410
3411 static const int MaxClaimNmethods = 16;
3412
3413 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3414 CompiledMethod* first;
3415 CompiledMethodIterator last;
3416
3417 do {
3418 *num_claimed_nmethods = 0;
3419
3420 first = _claimed_nmethod;
3421 last = CompiledMethodIterator(first);
3422
3423 if (first != NULL) {
3424
3425 for (int i = 0; i < MaxClaimNmethods; i++) {
3426 if (!last.next_alive()) {
3427 break;
3428 }
3429 claimed_nmethods[i] = last.method();
3430 (*num_claimed_nmethods)++;
3431 }
3432 }
3433
3434 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3435 }
3436
3437 CompiledMethod* claim_postponed_nmethod() {
3438 CompiledMethod* claim;
3439 CompiledMethod* next;
3440
3441 do {
3442 claim = _postponed_list;
3443 if (claim == NULL) {
3444 return NULL;
3445 }
3446
3447 next = claim->unloading_next();
3448
3449 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3450
3451 return claim;
3452 }
3453
3454 public:
3455 // Mark that we're done with the first pass of nmethod cleaning.
3456 void barrier_mark(uint worker_id) {
3457 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3458 _num_entered_barrier++;
3459 if (_num_entered_barrier == _num_workers) {
3460 ml.notify_all();
3461 }
3462 }
3463
3464 // See if we have to wait for the other workers to
3465 // finish their first-pass nmethod cleaning work.
3466 void barrier_wait(uint worker_id) {
3467 if (_num_entered_barrier < _num_workers) {
3468 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3469 while (_num_entered_barrier < _num_workers) {
3470 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3471 }
3472 }
3473 }
3474
3475 // Cleaning and unloading of nmethods. Some work has to be postponed
3476 // to the second pass, when we know which nmethods survive.
3477 void work_first_pass(uint worker_id) {
3478 // The first nmethods is claimed by the first worker.
3479 if (worker_id == 0 && _first_nmethod != NULL) {
3480 clean_nmethod(_first_nmethod);
3481 _first_nmethod = NULL;
3482 }
3483
3484 int num_claimed_nmethods;
3485 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3486
3487 while (true) {
3488 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3489
3490 if (num_claimed_nmethods == 0) {
3491 break;
3492 }
3493
3494 for (int i = 0; i < num_claimed_nmethods; i++) {
3495 clean_nmethod(claimed_nmethods[i]);
3496 }
3497 }
3498 }
3499
3500 void work_second_pass(uint worker_id) {
3501 CompiledMethod* nm;
3502 // Take care of postponed nmethods.
3503 while ((nm = claim_postponed_nmethod()) != NULL) {
3504 clean_nmethod_postponed(nm);
3505 }
3506 }
3507 };
3508
3509 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3510
3511 class G1KlassCleaningTask : public StackObj {
3512 volatile int _clean_klass_tree_claimed;
3513 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3514
3515 public:
3516 G1KlassCleaningTask() :
3517 _clean_klass_tree_claimed(0),
3518 _klass_iterator() {
3519 }
3520
3521 private:
3522 bool claim_clean_klass_tree_task() {
3523 if (_clean_klass_tree_claimed) {
3524 return false;
3525 }
3526
3527 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3528 }
3529
3530 InstanceKlass* claim_next_klass() {
3531 Klass* klass;
3532 do {
3533 klass =_klass_iterator.next_klass();
3534 } while (klass != NULL && !klass->is_instance_klass());
3535
3536 // this can be null so don't call InstanceKlass::cast
3537 return static_cast<InstanceKlass*>(klass);
3538 }
3539
3540 public:
3541
3542 void clean_klass(InstanceKlass* ik) {
3543 ik->clean_weak_instanceklass_links();
3544 }
3545
3546 void work() {
3547 ResourceMark rm;
3548
3549 // One worker will clean the subklass/sibling klass tree.
3550 if (claim_clean_klass_tree_task()) {
3551 Klass::clean_subklass_tree();
3552 }
3553
3554 // All workers will help cleaning the classes,
3555 InstanceKlass* klass;
3556 while ((klass = claim_next_klass()) != NULL) {
3557 clean_klass(klass);
3558 }
3559 }
3560 };
3561
3562 class G1ResolvedMethodCleaningTask : public StackObj {
3563 volatile int _resolved_method_task_claimed;
3564 public:
3565 G1ResolvedMethodCleaningTask() :
3566 _resolved_method_task_claimed(0) {}
3567
3568 bool claim_resolved_method_task() {
3569 if (_resolved_method_task_claimed) {
3570 return false;
3571 }
3572 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3573 }
3574
3575 // These aren't big, one thread can do it all.
3576 void work() {
3577 if (claim_resolved_method_task()) {
3578 ResolvedMethodTable::unlink();
3579 }
3580 }
3581 };
3582
3583
3584 // To minimize the remark pause times, the tasks below are done in parallel.
3585 class G1ParallelCleaningTask : public AbstractGangTask {
3586 private:
3587 bool _unloading_occurred;
3588 G1StringAndSymbolCleaningTask _string_symbol_task;
3589 G1CodeCacheUnloadingTask _code_cache_task;
3590 G1KlassCleaningTask _klass_cleaning_task;
3591 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3592
3593 public:
3594 // The constructor is run in the VMThread.
3595 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3596 AbstractGangTask("Parallel Cleaning"),
3597 _unloading_occurred(unloading_occurred),
3598 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3599 _code_cache_task(num_workers, is_alive, unloading_occurred),
3600 _klass_cleaning_task(),
3601 _resolved_method_cleaning_task() {
3602 }
3603
3604 // The parallel work done by all worker threads.
3605 void work(uint worker_id) {
3606 // Do first pass of code cache cleaning.
3607 _code_cache_task.work_first_pass(worker_id);
3608
3609 // Let the threads mark that the first pass is done.
3610 _code_cache_task.barrier_mark(worker_id);
3611
3612 // Clean the Strings and Symbols.
3613 _string_symbol_task.work(worker_id);
3614
3615 // Clean unreferenced things in the ResolvedMethodTable
3616 _resolved_method_cleaning_task.work();
3617
3618 // Wait for all workers to finish the first code cache cleaning pass.
3619 _code_cache_task.barrier_wait(worker_id);
3620
3621 // Do the second code cache cleaning work, which realize on
3622 // the liveness information gathered during the first pass.
3623 _code_cache_task.work_second_pass(worker_id);
3624
3625 // Clean all klasses that were not unloaded.
3626 // The weak metadata in klass doesn't need to be
3627 // processed if there was no unloading.
3628 if (_unloading_occurred) {
3629 _klass_cleaning_task.work();
3630 }
3631 }
3632 };
3633
3634
3635 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3636 bool class_unloading_occurred) {
3637 uint n_workers = workers()->active_workers();
3638
3639 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3640 workers()->run_task(&g1_unlink_task);
3641 }
3642
3643 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3644 bool process_strings,
3645 bool process_symbols,
3646 bool process_string_dedup) {
3647 if (!process_strings && !process_symbols && !process_string_dedup) {
3648 // Nothing to clean.
3649 return;
3650 }
3651
3652 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3653 workers()->run_task(&g1_unlink_task);
3654
3655 }
3656
3657 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3658 private:
3659 DirtyCardQueueSet* _queue;
3660 G1CollectedHeap* _g1h;
3661 public:
3662 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3663 _queue(queue), _g1h(g1h) { }
3664
3665 virtual void work(uint worker_id) {
3666 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3667 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3668
3669 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3670 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3671
3672 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3673 }
3674 };
3675
3676 void G1CollectedHeap::redirty_logged_cards() {
3677 double redirty_logged_cards_start = os::elapsedTime();
3678
3679 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3680 dirty_card_queue_set().reset_for_par_iteration();
3681 workers()->run_task(&redirty_task);
3682
3683 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3684 dcq.merge_bufferlists(&dirty_card_queue_set());
3685 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3686
3687 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3688 }
3689
3690 // Weak Reference Processing support
3691
3692 bool G1STWIsAliveClosure::do_object_b(oop p) {
3693 // An object is reachable if it is outside the collection set,
3694 // or is inside and copied.
3695 return !_g1h->is_in_cset(p) || p->is_forwarded();
3696 }
3697
3698 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3699 assert(obj != NULL, "must not be NULL");
3700 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3701 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3702 // may falsely indicate that this is not the case here: however the collection set only
3703 // contains old regions when concurrent mark is not running.
3704 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3705 }
3706
3707 // Non Copying Keep Alive closure
3708 class G1KeepAliveClosure: public OopClosure {
3709 G1CollectedHeap*_g1h;
3710 public:
3711 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3712 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3713 void do_oop(oop* p) {
3714 oop obj = *p;
3715 assert(obj != NULL, "the caller should have filtered out NULL values");
3716
3717 const InCSetState cset_state =_g1h->in_cset_state(obj);
3718 if (!cset_state.is_in_cset_or_humongous()) {
3719 return;
3720 }
3721 if (cset_state.is_in_cset()) {
3722 assert( obj->is_forwarded(), "invariant" );
3723 *p = obj->forwardee();
3724 } else {
3725 assert(!obj->is_forwarded(), "invariant" );
3726 assert(cset_state.is_humongous(),
3727 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3728 _g1h->set_humongous_is_live(obj);
3729 }
3730 }
3731 };
3732
3733 // Copying Keep Alive closure - can be called from both
3734 // serial and parallel code as long as different worker
3735 // threads utilize different G1ParScanThreadState instances
3736 // and different queues.
3737
3738 class G1CopyingKeepAliveClosure: public OopClosure {
3739 G1CollectedHeap* _g1h;
3740 G1ParScanThreadState* _par_scan_state;
3741
3742 public:
3743 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3744 G1ParScanThreadState* pss):
3745 _g1h(g1h),
3746 _par_scan_state(pss)
3747 {}
3748
3749 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3750 virtual void do_oop( oop* p) { do_oop_work(p); }
3751
3752 template <class T> void do_oop_work(T* p) {
3753 oop obj = RawAccess<>::oop_load(p);
3754
3755 if (_g1h->is_in_cset_or_humongous(obj)) {
3756 // If the referent object has been forwarded (either copied
3757 // to a new location or to itself in the event of an
3758 // evacuation failure) then we need to update the reference
3759 // field and, if both reference and referent are in the G1
3760 // heap, update the RSet for the referent.
3761 //
3762 // If the referent has not been forwarded then we have to keep
3763 // it alive by policy. Therefore we have copy the referent.
3764 //
3765 // When the queue is drained (after each phase of reference processing)
3766 // the object and it's followers will be copied, the reference field set
3767 // to point to the new location, and the RSet updated.
3768 _par_scan_state->push_on_queue(p);
3769 }
3770 }
3771 };
3772
3773 // Serial drain queue closure. Called as the 'complete_gc'
3774 // closure for each discovered list in some of the
3775 // reference processing phases.
3776
3777 class G1STWDrainQueueClosure: public VoidClosure {
3778 protected:
3779 G1CollectedHeap* _g1h;
3780 G1ParScanThreadState* _par_scan_state;
3781
3782 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3783
3784 public:
3785 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3786 _g1h(g1h),
3787 _par_scan_state(pss)
3788 { }
3789
3790 void do_void() {
3791 G1ParScanThreadState* const pss = par_scan_state();
3792 pss->trim_queue();
3793 }
3794 };
3795
3796 // Parallel Reference Processing closures
3797
3798 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3799 // processing during G1 evacuation pauses.
3800
3801 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3802 private:
3803 G1CollectedHeap* _g1h;
3804 G1ParScanThreadStateSet* _pss;
3805 RefToScanQueueSet* _queues;
3806 WorkGang* _workers;
3807
3808 public:
3809 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3810 G1ParScanThreadStateSet* per_thread_states,
3811 WorkGang* workers,
3812 RefToScanQueueSet *task_queues) :
3813 _g1h(g1h),
3814 _pss(per_thread_states),
3815 _queues(task_queues),
3816 _workers(workers)
3817 {
3818 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3819 }
3820
3821 // Executes the given task using concurrent marking worker threads.
3822 virtual void execute(ProcessTask& task, uint ergo_workers);
3823 };
3824
3825 // Gang task for possibly parallel reference processing
3826
3827 class G1STWRefProcTaskProxy: public AbstractGangTask {
3828 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3829 ProcessTask& _proc_task;
3830 G1CollectedHeap* _g1h;
3831 G1ParScanThreadStateSet* _pss;
3832 RefToScanQueueSet* _task_queues;
3833 ParallelTaskTerminator* _terminator;
3834
3835 public:
3836 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3837 G1CollectedHeap* g1h,
3838 G1ParScanThreadStateSet* per_thread_states,
3839 RefToScanQueueSet *task_queues,
3840 ParallelTaskTerminator* terminator) :
3841 AbstractGangTask("Process reference objects in parallel"),
3842 _proc_task(proc_task),
3843 _g1h(g1h),
3844 _pss(per_thread_states),
3845 _task_queues(task_queues),
3846 _terminator(terminator)
3847 {}
3848
3849 virtual void work(uint worker_id) {
3850 // The reference processing task executed by a single worker.
3851 ResourceMark rm;
3852 HandleMark hm;
3853
3854 G1STWIsAliveClosure is_alive(_g1h);
3855
3856 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3857 pss->set_ref_discoverer(NULL);
3858
3859 // Keep alive closure.
3860 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3861
3862 // Complete GC closure
3863 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3864
3865 // Call the reference processing task's work routine.
3866 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3867
3868 // Note we cannot assert that the refs array is empty here as not all
3869 // of the processing tasks (specifically phase2 - pp2_work) execute
3870 // the complete_gc closure (which ordinarily would drain the queue) so
3871 // the queue may not be empty.
3872 }
3873 };
3874
3875 // Driver routine for parallel reference processing.
3876 // Creates an instance of the ref processing gang
3877 // task and has the worker threads execute it.
3878 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3879 assert(_workers != NULL, "Need parallel worker threads.");
3880
3881 assert(_workers->active_workers() >= ergo_workers,
3882 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3883 ergo_workers, _workers->active_workers());
3884 ParallelTaskTerminator terminator(ergo_workers, _queues);
3885 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3886
3887 _workers->run_task(&proc_task_proxy, ergo_workers);
3888 }
3889
3890 // End of weak reference support closures
3891
3892 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3893 double ref_proc_start = os::elapsedTime();
3894
3895 ReferenceProcessor* rp = _ref_processor_stw;
3896 assert(rp->discovery_enabled(), "should have been enabled");
3897
3898 // Closure to test whether a referent is alive.
3899 G1STWIsAliveClosure is_alive(this);
3900
3901 // Even when parallel reference processing is enabled, the processing
3902 // of JNI refs is serial and performed serially by the current thread
3903 // rather than by a worker. The following PSS will be used for processing
3904 // JNI refs.
3905
3906 // Use only a single queue for this PSS.
3907 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3908 pss->set_ref_discoverer(NULL);
3909 assert(pss->queue_is_empty(), "pre-condition");
3910
3911 // Keep alive closure.
3912 G1CopyingKeepAliveClosure keep_alive(this, pss);
3913
3914 // Serial Complete GC closure
3915 G1STWDrainQueueClosure drain_queue(this, pss);
3916
3917 // Setup the soft refs policy...
3918 rp->setup_policy(false);
3919
3920 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3921
3922 ReferenceProcessorStats stats;
3923 if (!rp->processing_is_mt()) {
3924 // Serial reference processing...
3925 stats = rp->process_discovered_references(&is_alive,
3926 &keep_alive,
3927 &drain_queue,
3928 NULL,
3929 pt);
3930 } else {
3931 uint no_of_gc_workers = workers()->active_workers();
3932
3933 // Parallel reference processing
3934 assert(no_of_gc_workers <= rp->max_num_queues(),
3935 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3936 no_of_gc_workers, rp->max_num_queues());
3937
3938 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3939 stats = rp->process_discovered_references(&is_alive,
3940 &keep_alive,
3941 &drain_queue,
3942 &par_task_executor,
3943 pt);
3944 }
3945
3946 _gc_tracer_stw->report_gc_reference_stats(stats);
3947
3948 // We have completed copying any necessary live referent objects.
3949 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3950
3951 make_pending_list_reachable();
3952
3953 rp->verify_no_references_recorded();
3954
3955 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3956 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3957 }
3958
3959 void G1CollectedHeap::make_pending_list_reachable() {
3960 if (collector_state()->in_initial_mark_gc()) {
3961 oop pll_head = Universe::reference_pending_list();
3962 if (pll_head != NULL) {
3963 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3964 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3965 }
3966 }
3967 }
3968
3969 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3970 double merge_pss_time_start = os::elapsedTime();
3971 per_thread_states->flush();
3972 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3973 }
3974
3975 void G1CollectedHeap::pre_evacuate_collection_set() {
3976 _expand_heap_after_alloc_failure = true;
3977 _evacuation_failed = false;
3978
3979 // Disable the hot card cache.
3980 _hot_card_cache->reset_hot_cache_claimed_index();
3981 _hot_card_cache->set_use_cache(false);
3982
3983 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3984 _preserved_marks_set.assert_empty();
3985
3986 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3987
3988 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3989 if (collector_state()->in_initial_mark_gc()) {
3990 double start_clear_claimed_marks = os::elapsedTime();
3991
3992 ClassLoaderDataGraph::clear_claimed_marks();
3993
3994 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3995 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3996 }
3997 }
3998
3999 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
4000 // Should G1EvacuationFailureALot be in effect for this GC?
4001 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4002
4003 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4004
4005 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4006
4007 double start_par_time_sec = os::elapsedTime();
4008 double end_par_time_sec;
4009
4010 {
4011 const uint n_workers = workers()->active_workers();
4012 G1RootProcessor root_processor(this, n_workers);
4013 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4014
4015 print_termination_stats_hdr();
4016
4017 workers()->run_task(&g1_par_task);
4018 end_par_time_sec = os::elapsedTime();
4019
4020 // Closing the inner scope will execute the destructor
4021 // for the G1RootProcessor object. We record the current
4022 // elapsed time before closing the scope so that time
4023 // taken for the destructor is NOT included in the
4024 // reported parallel time.
4025 }
4026
4027 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4028 phase_times->record_par_time(par_time_ms);
4029
4030 double code_root_fixup_time_ms =
4031 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4032 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4033 }
4034
4035 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4036 // Also cleans the card table from temporary duplicate detection information used
4037 // during UpdateRS/ScanRS.
4038 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4039
4040 // Process any discovered reference objects - we have
4041 // to do this _before_ we retire the GC alloc regions
4042 // as we may have to copy some 'reachable' referent
4043 // objects (and their reachable sub-graphs) that were
4044 // not copied during the pause.
4045 process_discovered_references(per_thread_states);
4046
4047 // FIXME
4048 // CM's reference processing also cleans up the string and symbol tables.
4049 // Should we do that here also? We could, but it is a serial operation
4050 // and could significantly increase the pause time.
4051
4052 G1STWIsAliveClosure is_alive(this);
4053 G1KeepAliveClosure keep_alive(this);
4054
4055 {
4056 double start = os::elapsedTime();
4057
4058 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4059
4060 double time_ms = (os::elapsedTime() - start) * 1000.0;
4061 g1_policy()->phase_times()->record_weak_ref_proc_time(time_ms);
4062 }
4063
4064 if (G1StringDedup::is_enabled()) {
4065 double fixup_start = os::elapsedTime();
4066
4067 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4068
4069 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4070 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4071 }
4072
4073 if (evacuation_failed()) {
4074 restore_after_evac_failure();
4075
4076 // Reset the G1EvacuationFailureALot counters and flags
4077 // Note: the values are reset only when an actual
4078 // evacuation failure occurs.
4079 NOT_PRODUCT(reset_evacuation_should_fail();)
4080 }
4081
4082 _preserved_marks_set.assert_empty();
4083
4084 _allocator->release_gc_alloc_regions(evacuation_info);
4085
4086 merge_per_thread_state_info(per_thread_states);
4087
4088 // Reset and re-enable the hot card cache.
4089 // Note the counts for the cards in the regions in the
4090 // collection set are reset when the collection set is freed.
4091 _hot_card_cache->reset_hot_cache();
4092 _hot_card_cache->set_use_cache(true);
4093
4094 purge_code_root_memory();
4095
4096 redirty_logged_cards();
4097 #if COMPILER2_OR_JVMCI
4098 double start = os::elapsedTime();
4099 DerivedPointerTable::update_pointers();
4100 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4101 #endif
4102 g1_policy()->print_age_table();
4103 }
4104
4105 void G1CollectedHeap::record_obj_copy_mem_stats() {
4106 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4107
4108 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4109 create_g1_evac_summary(&_old_evac_stats));
4110 }
4111
4112 void G1CollectedHeap::free_region(HeapRegion* hr,
4113 FreeRegionList* free_list,
4114 bool skip_remset,
4115 bool skip_hot_card_cache,
4116 bool locked) {
4117 assert(!hr->is_free(), "the region should not be free");
4118 assert(!hr->is_empty(), "the region should not be empty");
4119 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4120 assert(free_list != NULL, "pre-condition");
4121
4122 if (G1VerifyBitmaps) {
4123 MemRegion mr(hr->bottom(), hr->end());
4124 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4125 }
4126
4127 // Clear the card counts for this region.
4128 // Note: we only need to do this if the region is not young
4129 // (since we don't refine cards in young regions).
4130 if (!skip_hot_card_cache && !hr->is_young()) {
4131 _hot_card_cache->reset_card_counts(hr);
4132 }
4133 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4134 _g1_policy->remset_tracker()->update_at_free(hr);
4135 free_list->add_ordered(hr);
4136 }
4137
4138 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4139 FreeRegionList* free_list) {
4140 assert(hr->is_humongous(), "this is only for humongous regions");
4141 assert(free_list != NULL, "pre-condition");
4142 hr->clear_humongous();
4143 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4144 }
4145
4146 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4147 const uint humongous_regions_removed) {
4148 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4149 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4150 _old_set.bulk_remove(old_regions_removed);
4151 _humongous_set.bulk_remove(humongous_regions_removed);
4152 }
4153
4154 }
4155
4156 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4157 assert(list != NULL, "list can't be null");
4158 if (!list->is_empty()) {
4159 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4160 _hrm.insert_list_into_free_list(list);
4161 }
4162 }
4163
4164 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4165 decrease_used(bytes);
4166 }
4167
4168 class G1FreeCollectionSetTask : public AbstractGangTask {
4169 private:
4170
4171 // Closure applied to all regions in the collection set to do work that needs to
4172 // be done serially in a single thread.
4173 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4174 private:
4175 EvacuationInfo* _evacuation_info;
4176 const size_t* _surviving_young_words;
4177
4178 // Bytes used in successfully evacuated regions before the evacuation.
4179 size_t _before_used_bytes;
4180 // Bytes used in unsucessfully evacuated regions before the evacuation
4181 size_t _after_used_bytes;
4182
4183 size_t _bytes_allocated_in_old_since_last_gc;
4184
4185 size_t _failure_used_words;
4186 size_t _failure_waste_words;
4187
4188 FreeRegionList _local_free_list;
4189 public:
4190 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4191 HeapRegionClosure(),
4192 _evacuation_info(evacuation_info),
4193 _surviving_young_words(surviving_young_words),
4194 _before_used_bytes(0),
4195 _after_used_bytes(0),
4196 _bytes_allocated_in_old_since_last_gc(0),
4197 _failure_used_words(0),
4198 _failure_waste_words(0),
4199 _local_free_list("Local Region List for CSet Freeing") {
4200 }
4201
4202 virtual bool do_heap_region(HeapRegion* r) {
4203 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4204
4205 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4206 g1h->clear_in_cset(r);
4207
4208 if (r->is_young()) {
4209 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4210 "Young index %d is wrong for region %u of type %s with %u young regions",
4211 r->young_index_in_cset(),
4212 r->hrm_index(),
4213 r->get_type_str(),
4214 g1h->collection_set()->young_region_length());
4215 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4216 r->record_surv_words_in_group(words_survived);
4217 }
4218
4219 if (!r->evacuation_failed()) {
4220 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4221 _before_used_bytes += r->used();
4222 g1h->free_region(r,
4223 &_local_free_list,
4224 true, /* skip_remset */
4225 true, /* skip_hot_card_cache */
4226 true /* locked */);
4227 } else {
4228 r->uninstall_surv_rate_group();
4229 r->set_young_index_in_cset(-1);
4230 r->set_evacuation_failed(false);
4231 // When moving a young gen region to old gen, we "allocate" that whole region
4232 // there. This is in addition to any already evacuated objects. Notify the
4233 // policy about that.
4234 // Old gen regions do not cause an additional allocation: both the objects
4235 // still in the region and the ones already moved are accounted for elsewhere.
4236 if (r->is_young()) {
4237 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4238 }
4239 // The region is now considered to be old.
4240 r->set_old();
4241 // Do some allocation statistics accounting. Regions that failed evacuation
4242 // are always made old, so there is no need to update anything in the young
4243 // gen statistics, but we need to update old gen statistics.
4244 size_t used_words = r->marked_bytes() / HeapWordSize;
4245
4246 _failure_used_words += used_words;
4247 _failure_waste_words += HeapRegion::GrainWords - used_words;
4248
4249 g1h->old_set_add(r);
4250 _after_used_bytes += r->used();
4251 }
4252 return false;
4253 }
4254
4255 void complete_work() {
4256 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4257
4258 _evacuation_info->set_regions_freed(_local_free_list.length());
4259 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4260
4261 g1h->prepend_to_freelist(&_local_free_list);
4262 g1h->decrement_summary_bytes(_before_used_bytes);
4263
4264 G1Policy* policy = g1h->g1_policy();
4265 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4266
4267 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4268 }
4269 };
4270
4271 G1CollectionSet* _collection_set;
4272 G1SerialFreeCollectionSetClosure _cl;
4273 const size_t* _surviving_young_words;
4274
4275 size_t _rs_lengths;
4276
4277 volatile jint _serial_work_claim;
4278
4279 struct WorkItem {
4280 uint region_idx;
4281 bool is_young;
4282 bool evacuation_failed;
4283
4284 WorkItem(HeapRegion* r) {
4285 region_idx = r->hrm_index();
4286 is_young = r->is_young();
4287 evacuation_failed = r->evacuation_failed();
4288 }
4289 };
4290
4291 volatile size_t _parallel_work_claim;
4292 size_t _num_work_items;
4293 WorkItem* _work_items;
4294
4295 void do_serial_work() {
4296 // Need to grab the lock to be allowed to modify the old region list.
4297 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4298 _collection_set->iterate(&_cl);
4299 }
4300
4301 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4302 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4303
4304 HeapRegion* r = g1h->region_at(region_idx);
4305 assert(!g1h->is_on_master_free_list(r), "sanity");
4306
4307 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4308
4309 if (!is_young) {
4310 g1h->_hot_card_cache->reset_card_counts(r);
4311 }
4312
4313 if (!evacuation_failed) {
4314 r->rem_set()->clear_locked();
4315 }
4316 }
4317
4318 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4319 private:
4320 size_t _cur_idx;
4321 WorkItem* _work_items;
4322 public:
4323 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4324
4325 virtual bool do_heap_region(HeapRegion* r) {
4326 _work_items[_cur_idx++] = WorkItem(r);
4327 return false;
4328 }
4329 };
4330
4331 void prepare_work() {
4332 G1PrepareFreeCollectionSetClosure cl(_work_items);
4333 _collection_set->iterate(&cl);
4334 }
4335
4336 void complete_work() {
4337 _cl.complete_work();
4338
4339 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4340 policy->record_max_rs_lengths(_rs_lengths);
4341 policy->cset_regions_freed();
4342 }
4343 public:
4344 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4345 AbstractGangTask("G1 Free Collection Set"),
4346 _collection_set(collection_set),
4347 _cl(evacuation_info, surviving_young_words),
4348 _surviving_young_words(surviving_young_words),
4349 _rs_lengths(0),
4350 _serial_work_claim(0),
4351 _parallel_work_claim(0),
4352 _num_work_items(collection_set->region_length()),
4353 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4354 prepare_work();
4355 }
4356
4357 ~G1FreeCollectionSetTask() {
4358 complete_work();
4359 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4360 }
4361
4362 // Chunk size for work distribution. The chosen value has been determined experimentally
4363 // to be a good tradeoff between overhead and achievable parallelism.
4364 static uint chunk_size() { return 32; }
4365
4366 virtual void work(uint worker_id) {
4367 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4368
4369 // Claim serial work.
4370 if (_serial_work_claim == 0) {
4371 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4372 if (value == 0) {
4373 double serial_time = os::elapsedTime();
4374 do_serial_work();
4375 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4376 }
4377 }
4378
4379 // Start parallel work.
4380 double young_time = 0.0;
4381 bool has_young_time = false;
4382 double non_young_time = 0.0;
4383 bool has_non_young_time = false;
4384
4385 while (true) {
4386 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4387 size_t cur = end - chunk_size();
4388
4389 if (cur >= _num_work_items) {
4390 break;
4391 }
4392
4393 double start_time = os::elapsedTime();
4394
4395 end = MIN2(end, _num_work_items);
4396
4397 for (; cur < end; cur++) {
4398 bool is_young = _work_items[cur].is_young;
4399
4400 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4401
4402 double end_time = os::elapsedTime();
4403 double time_taken = end_time - start_time;
4404 if (is_young) {
4405 young_time += time_taken;
4406 has_young_time = true;
4407 } else {
4408 non_young_time += time_taken;
4409 has_non_young_time = true;
4410 }
4411 start_time = end_time;
4412 }
4413 }
4414
4415 if (has_young_time) {
4416 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4417 }
4418 if (has_non_young_time) {
4419 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4420 }
4421 }
4422 };
4423
4424 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4425 _eden.clear();
4426
4427 double free_cset_start_time = os::elapsedTime();
4428
4429 {
4430 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4431 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4432
4433 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4434
4435 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4436 cl.name(),
4437 num_workers,
4438 _collection_set.region_length());
4439 workers()->run_task(&cl, num_workers);
4440 }
4441 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4442
4443 collection_set->clear();
4444 }
4445
4446 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4447 private:
4448 FreeRegionList* _free_region_list;
4449 HeapRegionSet* _proxy_set;
4450 uint _humongous_objects_reclaimed;
4451 uint _humongous_regions_reclaimed;
4452 size_t _freed_bytes;
4453 public:
4454
4455 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4456 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4457 }
4458
4459 virtual bool do_heap_region(HeapRegion* r) {
4460 if (!r->is_starts_humongous()) {
4461 return false;
4462 }
4463
4464 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4465
4466 oop obj = (oop)r->bottom();
4467 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4468
4469 // The following checks whether the humongous object is live are sufficient.
4470 // The main additional check (in addition to having a reference from the roots
4471 // or the young gen) is whether the humongous object has a remembered set entry.
4472 //
4473 // A humongous object cannot be live if there is no remembered set for it
4474 // because:
4475 // - there can be no references from within humongous starts regions referencing
4476 // the object because we never allocate other objects into them.
4477 // (I.e. there are no intra-region references that may be missed by the
4478 // remembered set)
4479 // - as soon there is a remembered set entry to the humongous starts region
4480 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4481 // until the end of a concurrent mark.
4482 //
4483 // It is not required to check whether the object has been found dead by marking
4484 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4485 // all objects allocated during that time are considered live.
4486 // SATB marking is even more conservative than the remembered set.
4487 // So if at this point in the collection there is no remembered set entry,
4488 // nobody has a reference to it.
4489 // At the start of collection we flush all refinement logs, and remembered sets
4490 // are completely up-to-date wrt to references to the humongous object.
4491 //
4492 // Other implementation considerations:
4493 // - never consider object arrays at this time because they would pose
4494 // considerable effort for cleaning up the the remembered sets. This is
4495 // required because stale remembered sets might reference locations that
4496 // are currently allocated into.
4497 uint region_idx = r->hrm_index();
4498 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4499 !r->rem_set()->is_empty()) {
4500 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",
4501 region_idx,
4502 (size_t)obj->size() * HeapWordSize,
4503 p2i(r->bottom()),
4504 r->rem_set()->occupied(),
4505 r->rem_set()->strong_code_roots_list_length(),
4506 next_bitmap->is_marked(r->bottom()),
4507 g1h->is_humongous_reclaim_candidate(region_idx),
4508 obj->is_typeArray()
4509 );
4510 return false;
4511 }
4512
4513 guarantee(obj->is_typeArray(),
4514 "Only eagerly reclaiming type arrays is supported, but the object "
4515 PTR_FORMAT " is not.", p2i(r->bottom()));
4516
4517 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",
4518 region_idx,
4519 (size_t)obj->size() * HeapWordSize,
4520 p2i(r->bottom()),
4521 r->rem_set()->occupied(),
4522 r->rem_set()->strong_code_roots_list_length(),
4523 next_bitmap->is_marked(r->bottom()),
4524 g1h->is_humongous_reclaim_candidate(region_idx),
4525 obj->is_typeArray()
4526 );
4527
4528 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4529 cm->humongous_object_eagerly_reclaimed(r);
4530 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4531 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4532 region_idx,
4533 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4534 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4535 _humongous_objects_reclaimed++;
4536 do {
4537 HeapRegion* next = g1h->next_region_in_humongous(r);
4538 _freed_bytes += r->used();
4539 r->set_containing_set(NULL);
4540 _humongous_regions_reclaimed++;
4541 g1h->free_humongous_region(r, _free_region_list);
4542 r = next;
4543 } while (r != NULL);
4544
4545 return false;
4546 }
4547
4548 uint humongous_objects_reclaimed() {
4549 return _humongous_objects_reclaimed;
4550 }
4551
4552 uint humongous_regions_reclaimed() {
4553 return _humongous_regions_reclaimed;
4554 }
4555
4556 size_t bytes_freed() const {
4557 return _freed_bytes;
4558 }
4559 };
4560
4561 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4562 assert_at_safepoint_on_vm_thread();
4563
4564 if (!G1EagerReclaimHumongousObjects ||
4565 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4566 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4567 return;
4568 }
4569
4570 double start_time = os::elapsedTime();
4571
4572 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4573
4574 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4575 heap_region_iterate(&cl);
4576
4577 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4578
4579 G1HRPrinter* hrp = hr_printer();
4580 if (hrp->is_active()) {
4581 FreeRegionListIterator iter(&local_cleanup_list);
4582 while (iter.more_available()) {
4583 HeapRegion* hr = iter.get_next();
4584 hrp->cleanup(hr);
4585 }
4586 }
4587
4588 prepend_to_freelist(&local_cleanup_list);
4589 decrement_summary_bytes(cl.bytes_freed());
4590
4591 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4592 cl.humongous_objects_reclaimed());
4593 }
4594
4595 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4596 public:
4597 virtual bool do_heap_region(HeapRegion* r) {
4598 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4599 G1CollectedHeap::heap()->clear_in_cset(r);
4600 r->set_young_index_in_cset(-1);
4601 return false;
4602 }
4603 };
4604
4605 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4606 G1AbandonCollectionSetClosure cl;
4607 collection_set->iterate(&cl);
4608
4609 collection_set->clear();
4610 collection_set->stop_incremental_building();
4611 }
4612
4613 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4614 return _allocator->is_retained_old_region(hr);
4615 }
4616
4617 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4618 _eden.add(hr);
4619 _g1_policy->set_region_eden(hr);
4620 }
4621
4622 #ifdef ASSERT
4623
4624 class NoYoungRegionsClosure: public HeapRegionClosure {
4625 private:
4626 bool _success;
4627 public:
4628 NoYoungRegionsClosure() : _success(true) { }
4629 bool do_heap_region(HeapRegion* r) {
4630 if (r->is_young()) {
4631 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4632 p2i(r->bottom()), p2i(r->end()));
4633 _success = false;
4634 }
4635 return false;
4636 }
4637 bool success() { return _success; }
4638 };
4639
4640 bool G1CollectedHeap::check_young_list_empty() {
4641 bool ret = (young_regions_count() == 0);
4642
4643 NoYoungRegionsClosure closure;
4644 heap_region_iterate(&closure);
4645 ret = ret && closure.success();
4646
4647 return ret;
4648 }
4649
4650 #endif // ASSERT
4651
4652 class TearDownRegionSetsClosure : public HeapRegionClosure {
4653 private:
4654 HeapRegionSet *_old_set;
4655
4656 public:
4657 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4658
4659 bool do_heap_region(HeapRegion* r) {
4660 if (r->is_old()) {
4661 _old_set->remove(r);
4662 } else if(r->is_young()) {
4663 r->uninstall_surv_rate_group();
4664 } else {
4665 // We ignore free regions, we'll empty the free list afterwards.
4666 // We ignore humongous regions, we're not tearing down the
4667 // humongous regions set.
4668 assert(r->is_free() || r->is_humongous(),
4669 "it cannot be another type");
4670 }
4671 return false;
4672 }
4673
4674 ~TearDownRegionSetsClosure() {
4675 assert(_old_set->is_empty(), "post-condition");
4676 }
4677 };
4678
4679 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4680 assert_at_safepoint_on_vm_thread();
4681
4682 if (!free_list_only) {
4683 TearDownRegionSetsClosure cl(&_old_set);
4684 heap_region_iterate(&cl);
4685
4686 // Note that emptying the _young_list is postponed and instead done as
4687 // the first step when rebuilding the regions sets again. The reason for
4688 // this is that during a full GC string deduplication needs to know if
4689 // a collected region was young or old when the full GC was initiated.
4690 }
4691 _hrm.remove_all_free_regions();
4692 }
4693
4694 void G1CollectedHeap::increase_used(size_t bytes) {
4695 _summary_bytes_used += bytes;
4696 }
4697
4698 void G1CollectedHeap::decrease_used(size_t bytes) {
4699 assert(_summary_bytes_used >= bytes,
4700 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4701 _summary_bytes_used, bytes);
4702 _summary_bytes_used -= bytes;
4703 }
4704
4705 void G1CollectedHeap::set_used(size_t bytes) {
4706 _summary_bytes_used = bytes;
4707 }
4708
4709 class RebuildRegionSetsClosure : public HeapRegionClosure {
4710 private:
4711 bool _free_list_only;
4712 HeapRegionSet* _old_set;
4713 HeapRegionManager* _hrm;
4714 size_t _total_used;
4715
4716 public:
4717 RebuildRegionSetsClosure(bool free_list_only,
4718 HeapRegionSet* old_set, HeapRegionManager* hrm) :
4719 _free_list_only(free_list_only),
4720 _old_set(old_set), _hrm(hrm), _total_used(0) {
4721 assert(_hrm->num_free_regions() == 0, "pre-condition");
4722 if (!free_list_only) {
4723 assert(_old_set->is_empty(), "pre-condition");
4724 }
4725 }
4726
4727 bool do_heap_region(HeapRegion* r) {
4728 // After full GC, no region should have a remembered set.
4729 r->rem_set()->clear(true);
4730 if (r->is_empty()) {
4731 // Add free regions to the free list
4732 r->set_free();
4733 _hrm->insert_into_free_list(r);
4734 } else if (!_free_list_only) {
4735
4736 if (r->is_humongous()) {
4737 // We ignore humongous regions. We left the humongous set unchanged.
4738 } else {
4739 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4740 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
4741 r->move_to_old();
4742 _old_set->add(r);
4743 }
4744 _total_used += r->used();
4745 }
4746
4747 return false;
4748 }
4749
4750 size_t total_used() {
4751 return _total_used;
4752 }
4753 };
4754
4755 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4756 assert_at_safepoint_on_vm_thread();
4757
4758 if (!free_list_only) {
4759 _eden.clear();
4760 _survivor.clear();
4761 }
4762
4763 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4764 heap_region_iterate(&cl);
4765
4766 if (!free_list_only) {
4767 set_used(cl.total_used());
4768 if (_archive_allocator != NULL) {
4769 _archive_allocator->clear_used();
4770 }
4771 }
4772 assert(used_unlocked() == recalculate_used(),
4773 "inconsistent used_unlocked(), "
4774 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4775 used_unlocked(), recalculate_used());
4776 }
4777
4778 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4779 HeapRegion* hr = heap_region_containing(p);
4780 return hr->is_in(p);
4781 }
4782
4783 // Methods for the mutator alloc region
4784
4785 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4786 bool force) {
4787 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4788 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4789 if (force || should_allocate) {
4790 HeapRegion* new_alloc_region = new_region(word_size,
4791 false /* is_old */,
4792 false /* do_expand */);
4793 if (new_alloc_region != NULL) {
4794 set_region_short_lived_locked(new_alloc_region);
4795 _hr_printer.alloc(new_alloc_region, !should_allocate);
4796 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4797 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4798 return new_alloc_region;
4799 }
4800 }
4801 return NULL;
4802 }
4803
4804 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4805 size_t allocated_bytes) {
4806 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4807 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4808
4809 collection_set()->add_eden_region(alloc_region);
4810 increase_used(allocated_bytes);
4811 _hr_printer.retire(alloc_region);
4812 // We update the eden sizes here, when the region is retired,
4813 // instead of when it's allocated, since this is the point that its
4814 // used space has been recored in _summary_bytes_used.
4815 g1mm()->update_eden_size();
4816 }
4817
4818 // Methods for the GC alloc regions
4819
4820 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4821 if (dest.is_old()) {
4822 return true;
4823 } else {
4824 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4825 }
4826 }
4827
4828 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4829 assert(FreeList_lock->owned_by_self(), "pre-condition");
4830
4831 if (!has_more_regions(dest)) {
4832 return NULL;
4833 }
4834
4835 const bool is_survivor = dest.is_young();
4836
4837 HeapRegion* new_alloc_region = new_region(word_size,
4838 !is_survivor,
4839 true /* do_expand */);
4840 if (new_alloc_region != NULL) {
4841 if (is_survivor) {
4842 new_alloc_region->set_survivor();
4843 _survivor.add(new_alloc_region);
4844 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4845 } else {
4846 new_alloc_region->set_old();
4847 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4848 }
4849 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4850 _hr_printer.alloc(new_alloc_region);
4851 bool during_im = collector_state()->in_initial_mark_gc();
4852 new_alloc_region->note_start_of_copying(during_im);
4853 return new_alloc_region;
4854 }
4855 return NULL;
4856 }
4857
4858 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4859 size_t allocated_bytes,
4860 InCSetState dest) {
4861 bool during_im = collector_state()->in_initial_mark_gc();
4862 alloc_region->note_end_of_copying(during_im);
4863 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4864 if (dest.is_old()) {
4865 _old_set.add(alloc_region);
4866 }
4867 _hr_printer.retire(alloc_region);
4868 }
4869
4870 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4871 bool expanded = false;
4872 uint index = _hrm.find_highest_free(&expanded);
4873
4874 if (index != G1_NO_HRM_INDEX) {
4875 if (expanded) {
4876 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4877 HeapRegion::GrainWords * HeapWordSize);
4878 }
4879 _hrm.allocate_free_regions_starting_at(index, 1);
4880 return region_at(index);
4881 }
4882 return NULL;
4883 }
4884
4885 // Optimized nmethod scanning
4886
4887 class RegisterNMethodOopClosure: public OopClosure {
4888 G1CollectedHeap* _g1h;
4889 nmethod* _nm;
4890
4891 template <class T> void do_oop_work(T* p) {
4892 T heap_oop = RawAccess<>::oop_load(p);
4893 if (!CompressedOops::is_null(heap_oop)) {
4894 oop obj = CompressedOops::decode_not_null(heap_oop);
4895 HeapRegion* hr = _g1h->heap_region_containing(obj);
4896 assert(!hr->is_continues_humongous(),
4897 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4898 " starting at " HR_FORMAT,
4899 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4900
4901 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4902 hr->add_strong_code_root_locked(_nm);
4903 }
4904 }
4905
4906 public:
4907 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4908 _g1h(g1h), _nm(nm) {}
4909
4910 void do_oop(oop* p) { do_oop_work(p); }
4911 void do_oop(narrowOop* p) { do_oop_work(p); }
4912 };
4913
4914 class UnregisterNMethodOopClosure: public OopClosure {
4915 G1CollectedHeap* _g1h;
4916 nmethod* _nm;
4917
4918 template <class T> void do_oop_work(T* p) {
4919 T heap_oop = RawAccess<>::oop_load(p);
4920 if (!CompressedOops::is_null(heap_oop)) {
4921 oop obj = CompressedOops::decode_not_null(heap_oop);
4922 HeapRegion* hr = _g1h->heap_region_containing(obj);
4923 assert(!hr->is_continues_humongous(),
4924 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4925 " starting at " HR_FORMAT,
4926 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4927
4928 hr->remove_strong_code_root(_nm);
4929 }
4930 }
4931
4932 public:
4933 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4934 _g1h(g1h), _nm(nm) {}
4935
4936 void do_oop(oop* p) { do_oop_work(p); }
4937 void do_oop(narrowOop* p) { do_oop_work(p); }
4938 };
4939
4940 // Returns true if the reference points to an object that
4941 // can move in an incremental collection.
4942 bool G1CollectedHeap::is_scavengable(oop obj) {
4943 HeapRegion* hr = heap_region_containing(obj);
4944 return !hr->is_pinned();
4945 }
4946
4947 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4948 guarantee(nm != NULL, "sanity");
4949 RegisterNMethodOopClosure reg_cl(this, nm);
4950 nm->oops_do(®_cl);
4951 }
4952
4953 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4954 guarantee(nm != NULL, "sanity");
4955 UnregisterNMethodOopClosure reg_cl(this, nm);
4956 nm->oops_do(®_cl, true);
4957 }
4958
4959 void G1CollectedHeap::purge_code_root_memory() {
4960 double purge_start = os::elapsedTime();
4961 G1CodeRootSet::purge();
4962 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4963 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4964 }
4965
4966 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4967 G1CollectedHeap* _g1h;
4968
4969 public:
4970 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4971 _g1h(g1h) {}
4972
4973 void do_code_blob(CodeBlob* cb) {
4974 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4975 if (nm == NULL) {
4976 return;
4977 }
4978
4979 if (ScavengeRootsInCode) {
4980 _g1h->register_nmethod(nm);
4981 }
4982 }
4983 };
4984
4985 void G1CollectedHeap::rebuild_strong_code_roots() {
4986 RebuildStrongCodeRootClosure blob_cl(this);
4987 CodeCache::blobs_do(&blob_cl);
4988 }
4989
4990 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4991 GrowableArray<GCMemoryManager*> memory_managers(2);
4992 memory_managers.append(&_memory_manager);
4993 memory_managers.append(&_full_gc_memory_manager);
4994 return memory_managers;
4995 }
4996
4997 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4998 GrowableArray<MemoryPool*> memory_pools(3);
4999 memory_pools.append(_eden_pool);
5000 memory_pools.append(_survivor_pool);
5001 memory_pools.append(_old_pool);
5002 return memory_pools;
5003 }