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/bufferingOopClosure.hpp"
32 #include "gc/g1/g1Allocator.inline.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1CollectedHeap.inline.hpp"
35 #include "gc/g1/g1CollectionSet.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1EvacStats.inline.hpp"
42 #include "gc/g1/g1FullCollector.hpp"
43 #include "gc/g1/g1GCPhaseTimes.hpp"
44 #include "gc/g1/g1HeapSizingPolicy.hpp"
45 #include "gc/g1/g1HeapTransition.hpp"
46 #include "gc/g1/g1HeapVerifier.hpp"
47 #include "gc/g1/g1HotCardCache.hpp"
48 #include "gc/g1/g1MemoryPool.hpp"
49 #include "gc/g1/g1OopClosures.inline.hpp"
50 #include "gc/g1/g1ParScanThreadState.inline.hpp"
51 #include "gc/g1/g1Policy.hpp"
52 #include "gc/g1/g1RegionToSpaceMapper.hpp"
53 #include "gc/g1/g1RemSet.hpp"
54 #include "gc/g1/g1RootClosures.hpp"
55 #include "gc/g1/g1RootProcessor.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/collectedHeap.inline.hpp"
66 #include "gc/shared/gcHeapSummary.hpp"
67 #include "gc/shared/gcId.hpp"
68 #include "gc/shared/gcLocker.hpp"
69 #include "gc/shared/gcTimer.hpp"
70 #include "gc/shared/gcTrace.hpp"
71 #include "gc/shared/gcTraceTime.inline.hpp"
72 #include "gc/shared/generationSpec.hpp"
73 #include "gc/shared/isGCActiveMark.hpp"
74 #include "gc/shared/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/resourceArea.hpp"
83 #include "oops/access.inline.hpp"
84 #include "oops/compressedOops.inline.hpp"
85 #include "oops/oop.inline.hpp"
86 #include "prims/resolvedMethodTable.hpp"
87 #include "runtime/atomic.hpp"
88 #include "runtime/handles.inline.hpp"
89 #include "runtime/init.hpp"
90 #include "runtime/orderAccess.inline.hpp"
91 #include "runtime/threadSMR.hpp"
92 #include "runtime/vmThread.hpp"
93 #include "utilities/align.hpp"
94 #include "utilities/globalDefinitions.hpp"
95 #include "utilities/stack.inline.hpp"
96
97 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
98
99 // INVARIANTS/NOTES
100 //
101 // All allocation activity covered by the G1CollectedHeap interface is
102 // serialized by acquiring the HeapLock. This happens in mem_allocate
103 // and allocate_new_tlab, which are the "entry" points to the
104 // allocation code from the rest of the JVM. (Note that this does not
105 // apply to TLAB allocation, which is not part of this interface: it
106 // is done by clients of this interface.)
107
108 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
109 private:
110 size_t _num_dirtied;
111 G1CollectedHeap* _g1h;
112 G1CardTable* _g1_ct;
113
114 HeapRegion* region_for_card(jbyte* card_ptr) const {
115 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
116 }
117
118 bool will_become_free(HeapRegion* hr) const {
119 // A region will be freed by free_collection_set if the region is in the
120 // collection set and has not had an evacuation failure.
121 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
122 }
123
124 public:
125 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
126 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
127
128 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
129 HeapRegion* hr = region_for_card(card_ptr);
130
131 // Should only dirty cards in regions that won't be freed.
132 if (!will_become_free(hr)) {
133 *card_ptr = G1CardTable::dirty_card_val();
134 _num_dirtied++;
135 }
136
137 return true;
138 }
139
140 size_t num_dirtied() const { return _num_dirtied; }
141 };
142
143
144 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
145 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
146 }
147
148 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
149 // The from card cache is not the memory that is actually committed. So we cannot
150 // take advantage of the zero_filled parameter.
151 reset_from_card_cache(start_idx, num_regions);
152 }
153
154
155 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
156 MemRegion mr) {
157 return new HeapRegion(hrs_index, bot(), mr);
158 }
159
160 // Private methods.
161
162 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
163 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
164 "the only time we use this to allocate a humongous region is "
165 "when we are allocating a single humongous region");
166
167 HeapRegion* res = _hrm.allocate_free_region(is_old);
168
169 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
170 // Currently, only attempts to allocate GC alloc regions set
171 // do_expand to true. So, we should only reach here during a
172 // safepoint. If this assumption changes we might have to
173 // reconsider the use of _expand_heap_after_alloc_failure.
174 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
175
176 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
177 word_size * HeapWordSize);
178
179 if (expand(word_size * HeapWordSize)) {
180 // Given that expand() succeeded in expanding the heap, and we
181 // always expand the heap by an amount aligned to the heap
182 // region size, the free list should in theory not be empty.
183 // In either case allocate_free_region() will check for NULL.
184 res = _hrm.allocate_free_region(is_old);
185 } else {
186 _expand_heap_after_alloc_failure = false;
187 }
188 }
189 return res;
190 }
191
192 HeapWord*
193 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
194 uint num_regions,
195 size_t word_size) {
196 assert(first != G1_NO_HRM_INDEX, "pre-condition");
197 assert(is_humongous(word_size), "word_size should be humongous");
198 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
199
200 // Index of last region in the series.
201 uint last = first + num_regions - 1;
202
203 // We need to initialize the region(s) we just discovered. This is
204 // a bit tricky given that it can happen concurrently with
205 // refinement threads refining cards on these regions and
206 // potentially wanting to refine the BOT as they are scanning
207 // those cards (this can happen shortly after a cleanup; see CR
208 // 6991377). So we have to set up the region(s) carefully and in
209 // a specific order.
210
211 // The word size sum of all the regions we will allocate.
212 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
213 assert(word_size <= word_size_sum, "sanity");
214
215 // This will be the "starts humongous" region.
216 HeapRegion* first_hr = region_at(first);
217 // The header of the new object will be placed at the bottom of
218 // the first region.
219 HeapWord* new_obj = first_hr->bottom();
220 // This will be the new top of the new object.
221 HeapWord* obj_top = new_obj + word_size;
222
223 // First, we need to zero the header of the space that we will be
224 // allocating. When we update top further down, some refinement
225 // threads might try to scan the region. By zeroing the header we
226 // ensure that any thread that will try to scan the region will
227 // come across the zero klass word and bail out.
228 //
229 // NOTE: It would not have been correct to have used
230 // CollectedHeap::fill_with_object() and make the space look like
231 // an int array. The thread that is doing the allocation will
232 // later update the object header to a potentially different array
233 // type and, for a very short period of time, the klass and length
234 // fields will be inconsistent. This could cause a refinement
235 // thread to calculate the object size incorrectly.
236 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
237
238 // Next, pad out the unused tail of the last region with filler
239 // objects, for improved usage accounting.
240 // How many words we use for filler objects.
241 size_t word_fill_size = word_size_sum - word_size;
242
243 // How many words memory we "waste" which cannot hold a filler object.
244 size_t words_not_fillable = 0;
245
246 if (word_fill_size >= min_fill_size()) {
247 fill_with_objects(obj_top, word_fill_size);
248 } else if (word_fill_size > 0) {
249 // We have space to fill, but we cannot fit an object there.
250 words_not_fillable = word_fill_size;
251 word_fill_size = 0;
252 }
253
254 // We will set up the first region as "starts humongous". This
255 // will also update the BOT covering all the regions to reflect
256 // that there is a single object that starts at the bottom of the
257 // first region.
258 first_hr->set_starts_humongous(obj_top, word_fill_size);
259 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
260 // Then, if there are any, we will set up the "continues
261 // humongous" regions.
262 HeapRegion* hr = NULL;
263 for (uint i = first + 1; i <= last; ++i) {
264 hr = region_at(i);
265 hr->set_continues_humongous(first_hr);
266 _g1_policy->remset_tracker()->update_at_allocate(hr);
267 }
268
269 // Up to this point no concurrent thread would have been able to
270 // do any scanning on any region in this series. All the top
271 // fields still point to bottom, so the intersection between
272 // [bottom,top] and [card_start,card_end] will be empty. Before we
273 // update the top fields, we'll do a storestore to make sure that
274 // no thread sees the update to top before the zeroing of the
275 // object header and the BOT initialization.
276 OrderAccess::storestore();
277
278 // Now, we will update the top fields of the "continues humongous"
279 // regions except the last one.
280 for (uint i = first; i < last; ++i) {
281 hr = region_at(i);
282 hr->set_top(hr->end());
283 }
284
285 hr = region_at(last);
286 // If we cannot fit a filler object, we must set top to the end
287 // of the humongous object, otherwise we cannot iterate the heap
288 // and the BOT will not be complete.
289 hr->set_top(hr->end() - words_not_fillable);
290
291 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
292 "obj_top should be in last region");
293
294 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
295
296 assert(words_not_fillable == 0 ||
297 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
298 "Miscalculation in humongous allocation");
299
300 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
301
302 for (uint i = first; i <= last; ++i) {
303 hr = region_at(i);
304 _humongous_set.add(hr);
305 _hr_printer.alloc(hr);
306 }
307
308 return new_obj;
309 }
310
311 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
312 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
313 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
314 }
315
316 // If could fit into free regions w/o expansion, try.
317 // Otherwise, if can expand, do so.
318 // Otherwise, if using ex regions might help, try with ex given back.
319 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
320 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
321
322 _verifier->verify_region_sets_optional();
323
324 uint first = G1_NO_HRM_INDEX;
325 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
326
327 if (obj_regions == 1) {
328 // Only one region to allocate, try to use a fast path by directly allocating
329 // from the free lists. Do not try to expand here, we will potentially do that
330 // later.
331 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
332 if (hr != NULL) {
333 first = hr->hrm_index();
334 }
335 } else {
336 // Policy: Try only empty regions (i.e. already committed first). Maybe we
337 // are lucky enough to find some.
338 first = _hrm.find_contiguous_only_empty(obj_regions);
339 if (first != G1_NO_HRM_INDEX) {
340 _hrm.allocate_free_regions_starting_at(first, obj_regions);
341 }
342 }
343
344 if (first == G1_NO_HRM_INDEX) {
345 // Policy: We could not find enough regions for the humongous object in the
346 // free list. Look through the heap to find a mix of free and uncommitted regions.
347 // If so, try expansion.
348 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
349 if (first != G1_NO_HRM_INDEX) {
350 // We found something. Make sure these regions are committed, i.e. expand
351 // the heap. Alternatively we could do a defragmentation GC.
352 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
353 word_size * HeapWordSize);
354
355 _hrm.expand_at(first, obj_regions, workers());
356 g1_policy()->record_new_heap_size(num_regions());
357
358 #ifdef ASSERT
359 for (uint i = first; i < first + obj_regions; ++i) {
360 HeapRegion* hr = region_at(i);
361 assert(hr->is_free(), "sanity");
362 assert(hr->is_empty(), "sanity");
363 assert(is_on_master_free_list(hr), "sanity");
364 }
365 #endif
366 _hrm.allocate_free_regions_starting_at(first, obj_regions);
367 } else {
368 // Policy: Potentially trigger a defragmentation GC.
369 }
370 }
371
372 HeapWord* result = NULL;
373 if (first != G1_NO_HRM_INDEX) {
374 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
375 assert(result != NULL, "it should always return a valid result");
376
377 // A successful humongous object allocation changes the used space
378 // information of the old generation so we need to recalculate the
379 // sizes and update the jstat counters here.
380 g1mm()->update_sizes();
381 }
382
383 _verifier->verify_region_sets_optional();
384
385 return result;
386 }
387
388 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
389 assert_heap_not_locked_and_not_at_safepoint();
390 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
391
392 return attempt_allocation(word_size);
393 }
394
395 HeapWord*
396 G1CollectedHeap::mem_allocate(size_t word_size, Klass* klass, Thread* thread,
397 bool* gc_overhead_limit_was_exceeded) {
398 assert_heap_not_locked_and_not_at_safepoint();
399
400 HeapWord* obj = allocate_from_tlab(klass, thread, word_size);
401 if (obj != NULL) {
402 return obj;
403 }
404 if (is_humongous(word_size)) {
405 return attempt_allocation_humongous(word_size);
406 }
407 return attempt_allocation(word_size);
408 }
409
410 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
411 ResourceMark rm; // For retrieving the thread names in log messages.
412
413 // Make sure you read the note in attempt_allocation_humongous().
414
415 assert_heap_not_locked_and_not_at_safepoint();
416 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
417 "be called for humongous allocation requests");
418
419 // We should only get here after the first-level allocation attempt
420 // (attempt_allocation()) failed to allocate.
421
422 // We will loop until a) we manage to successfully perform the
423 // allocation or b) we successfully schedule a collection which
424 // fails to perform the allocation. b) is the only case when we'll
425 // return NULL.
426 HeapWord* result = NULL;
427 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
428 bool should_try_gc;
429 uint gc_count_before;
430
431 {
432 MutexLockerEx x(Heap_lock);
433 result = _allocator->attempt_allocation_locked(word_size);
434 if (result != NULL) {
435 return result;
436 }
437
438 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
439 // This is different to when only GCLocker::needs_gc() is set: try to avoid
440 // waiting because the GCLocker is active to not wait too long.
441 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
442 // No need for an ergo message here, can_expand_young_list() does this when
443 // it returns true.
444 result = _allocator->attempt_allocation_force(word_size);
445 if (result != NULL) {
446 return result;
447 }
448 }
449 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
450 // the GCLocker initiated GC has been performed and then retry. This includes
451 // the case when the GC Locker is not active but has not been performed.
452 should_try_gc = !GCLocker::needs_gc();
453 // Read the GC count while still holding the Heap_lock.
454 gc_count_before = total_collections();
455 }
456
457 if (should_try_gc) {
458 bool succeeded;
459 result = do_collection_pause(word_size, gc_count_before, &succeeded,
460 GCCause::_g1_inc_collection_pause);
461 if (result != NULL) {
462 assert(succeeded, "only way to get back a non-NULL result");
463 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
464 Thread::current()->name(), p2i(result));
465 return result;
466 }
467
468 if (succeeded) {
469 // We successfully scheduled a collection which failed to allocate. No
470 // point in trying to allocate further. We'll just return NULL.
471 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
472 SIZE_FORMAT " words", Thread::current()->name(), word_size);
473 return NULL;
474 }
475 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
476 Thread::current()->name(), word_size);
477 } else {
478 // Failed to schedule a collection.
479 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
480 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
481 SIZE_FORMAT " words", Thread::current()->name(), word_size);
482 return NULL;
483 }
484 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
485 // The GCLocker is either active or the GCLocker initiated
486 // GC has not yet been performed. Stall until it is and
487 // then retry the allocation.
488 GCLocker::stall_until_clear();
489 gclocker_retry_count += 1;
490 }
491
492 // We can reach here if we were unsuccessful in scheduling a
493 // collection (because another thread beat us to it) or if we were
494 // stalled due to the GC locker. In either can we should retry the
495 // allocation attempt in case another thread successfully
496 // performed a collection and reclaimed enough space. We do the
497 // first attempt (without holding the Heap_lock) here and the
498 // follow-on attempt will be at the start of the next loop
499 // iteration (after taking the Heap_lock).
500
501 result = _allocator->attempt_allocation(word_size);
502 if (result != NULL) {
503 return result;
504 }
505
506 // Give a warning if we seem to be looping forever.
507 if ((QueuedAllocationWarningCount > 0) &&
508 (try_count % QueuedAllocationWarningCount == 0)) {
509 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
510 Thread::current()->name(), try_count, word_size);
511 }
512 }
513
514 ShouldNotReachHere();
515 return NULL;
516 }
517
518 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
519 assert_at_safepoint_on_vm_thread();
520 if (_archive_allocator == NULL) {
521 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
522 }
523 }
524
525 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
526 // Allocations in archive regions cannot be of a size that would be considered
527 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
528 // may be different at archive-restore time.
529 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
530 }
531
532 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
533 assert_at_safepoint_on_vm_thread();
534 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
535 if (is_archive_alloc_too_large(word_size)) {
536 return NULL;
537 }
538 return _archive_allocator->archive_mem_allocate(word_size);
539 }
540
541 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
542 size_t end_alignment_in_bytes) {
543 assert_at_safepoint_on_vm_thread();
544 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
545
546 // Call complete_archive to do the real work, filling in the MemRegion
547 // array with the archive regions.
548 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
549 delete _archive_allocator;
550 _archive_allocator = NULL;
551 }
552
553 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
554 assert(ranges != NULL, "MemRegion array NULL");
555 assert(count != 0, "No MemRegions provided");
556 MemRegion reserved = _hrm.reserved();
557 for (size_t i = 0; i < count; i++) {
558 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
559 return false;
560 }
561 }
562 return true;
563 }
564
565 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
566 size_t count,
567 bool open) {
568 assert(!is_init_completed(), "Expect to be called at JVM init time");
569 assert(ranges != NULL, "MemRegion array NULL");
570 assert(count != 0, "No MemRegions provided");
571 MutexLockerEx x(Heap_lock);
572
573 MemRegion reserved = _hrm.reserved();
574 HeapWord* prev_last_addr = NULL;
575 HeapRegion* prev_last_region = NULL;
576
577 // Temporarily disable pretouching of heap pages. This interface is used
578 // when mmap'ing archived heap data in, so pre-touching is wasted.
579 FlagSetting fs(AlwaysPreTouch, false);
580
581 // Enable archive object checking used by G1MarkSweep. We have to let it know
582 // about each archive range, so that objects in those ranges aren't marked.
583 G1ArchiveAllocator::enable_archive_object_check();
584
585 // For each specified MemRegion range, allocate the corresponding G1
586 // regions and mark them as archive regions. We expect the ranges
587 // in ascending starting address order, without overlap.
588 for (size_t i = 0; i < count; i++) {
589 MemRegion curr_range = ranges[i];
590 HeapWord* start_address = curr_range.start();
591 size_t word_size = curr_range.word_size();
592 HeapWord* last_address = curr_range.last();
593 size_t commits = 0;
594
595 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
596 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
597 p2i(start_address), p2i(last_address));
598 guarantee(start_address > prev_last_addr,
599 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
600 p2i(start_address), p2i(prev_last_addr));
601 prev_last_addr = last_address;
602
603 // Check for ranges that start in the same G1 region in which the previous
604 // range ended, and adjust the start address so we don't try to allocate
605 // the same region again. If the current range is entirely within that
606 // region, skip it, just adjusting the recorded top.
607 HeapRegion* start_region = _hrm.addr_to_region(start_address);
608 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
609 start_address = start_region->end();
610 if (start_address > last_address) {
611 increase_used(word_size * HeapWordSize);
612 start_region->set_top(last_address + 1);
613 continue;
614 }
615 start_region->set_top(start_address);
616 curr_range = MemRegion(start_address, last_address + 1);
617 start_region = _hrm.addr_to_region(start_address);
618 }
619
620 // Perform the actual region allocation, exiting if it fails.
621 // Then note how much new space we have allocated.
622 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
623 return false;
624 }
625 increase_used(word_size * HeapWordSize);
626 if (commits != 0) {
627 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
628 HeapRegion::GrainWords * HeapWordSize * commits);
629
630 }
631
632 // Mark each G1 region touched by the range as archive, add it to
633 // the old set, and set top.
634 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
635 HeapRegion* last_region = _hrm.addr_to_region(last_address);
636 prev_last_region = last_region;
637
638 while (curr_region != NULL) {
639 assert(curr_region->is_empty() && !curr_region->is_pinned(),
640 "Region already in use (index %u)", curr_region->hrm_index());
641 if (open) {
642 curr_region->set_open_archive();
643 } else {
644 curr_region->set_closed_archive();
645 }
646 _hr_printer.alloc(curr_region);
647 _old_set.add(curr_region);
648 HeapWord* top;
649 HeapRegion* next_region;
650 if (curr_region != last_region) {
651 top = curr_region->end();
652 next_region = _hrm.next_region_in_heap(curr_region);
653 } else {
654 top = last_address + 1;
655 next_region = NULL;
656 }
657 curr_region->set_top(top);
658 curr_region->set_first_dead(top);
659 curr_region->set_end_of_live(top);
660 curr_region = next_region;
661 }
662
663 // Notify mark-sweep of the archive
664 G1ArchiveAllocator::set_range_archive(curr_range, open);
665 }
666 return true;
667 }
668
669 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
670 assert(!is_init_completed(), "Expect to be called at JVM init time");
671 assert(ranges != NULL, "MemRegion array NULL");
672 assert(count != 0, "No MemRegions provided");
673 MemRegion reserved = _hrm.reserved();
674 HeapWord *prev_last_addr = NULL;
675 HeapRegion* prev_last_region = NULL;
676
677 // For each MemRegion, create filler objects, if needed, in the G1 regions
678 // that contain the address range. The address range actually within the
679 // MemRegion will not be modified. That is assumed to have been initialized
680 // elsewhere, probably via an mmap of archived heap data.
681 MutexLockerEx x(Heap_lock);
682 for (size_t i = 0; i < count; i++) {
683 HeapWord* start_address = ranges[i].start();
684 HeapWord* last_address = ranges[i].last();
685
686 assert(reserved.contains(start_address) && reserved.contains(last_address),
687 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
688 p2i(start_address), p2i(last_address));
689 assert(start_address > prev_last_addr,
690 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
691 p2i(start_address), p2i(prev_last_addr));
692
693 HeapRegion* start_region = _hrm.addr_to_region(start_address);
694 HeapRegion* last_region = _hrm.addr_to_region(last_address);
695 HeapWord* bottom_address = start_region->bottom();
696
697 // Check for a range beginning in the same region in which the
698 // previous one ended.
699 if (start_region == prev_last_region) {
700 bottom_address = prev_last_addr + 1;
701 }
702
703 // Verify that the regions were all marked as archive regions by
704 // alloc_archive_regions.
705 HeapRegion* curr_region = start_region;
706 while (curr_region != NULL) {
707 guarantee(curr_region->is_archive(),
708 "Expected archive region at index %u", curr_region->hrm_index());
709 if (curr_region != last_region) {
710 curr_region = _hrm.next_region_in_heap(curr_region);
711 } else {
712 curr_region = NULL;
713 }
714 }
715
716 prev_last_addr = last_address;
717 prev_last_region = last_region;
718
719 // Fill the memory below the allocated range with dummy object(s),
720 // if the region bottom does not match the range start, or if the previous
721 // range ended within the same G1 region, and there is a gap.
722 if (start_address != bottom_address) {
723 size_t fill_size = pointer_delta(start_address, bottom_address);
724 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
725 increase_used(fill_size * HeapWordSize);
726 }
727 }
728 }
729
730 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
731 assert_heap_not_locked_and_not_at_safepoint();
732 assert(!is_humongous(word_size), "attempt_allocation() should not "
733 "be called for humongous allocation requests");
734
735 HeapWord* result = _allocator->attempt_allocation(word_size);
736
737 if (result == NULL) {
738 result = attempt_allocation_slow(word_size);
739 }
740 assert_heap_not_locked();
741 if (result != NULL) {
742 dirty_young_block(result, word_size);
743 }
744 return result;
745 }
746
747 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
748 assert(!is_init_completed(), "Expect to be called at JVM init time");
749 assert(ranges != NULL, "MemRegion array NULL");
750 assert(count != 0, "No MemRegions provided");
751 MemRegion reserved = _hrm.reserved();
752 HeapWord* prev_last_addr = NULL;
753 HeapRegion* prev_last_region = NULL;
754 size_t size_used = 0;
755 size_t uncommitted_regions = 0;
756
757 // For each Memregion, free the G1 regions that constitute it, and
758 // notify mark-sweep that the range is no longer to be considered 'archive.'
759 MutexLockerEx x(Heap_lock);
760 for (size_t i = 0; i < count; i++) {
761 HeapWord* start_address = ranges[i].start();
762 HeapWord* last_address = ranges[i].last();
763
764 assert(reserved.contains(start_address) && reserved.contains(last_address),
765 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
766 p2i(start_address), p2i(last_address));
767 assert(start_address > prev_last_addr,
768 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
769 p2i(start_address), p2i(prev_last_addr));
770 size_used += ranges[i].byte_size();
771 prev_last_addr = last_address;
772
773 HeapRegion* start_region = _hrm.addr_to_region(start_address);
774 HeapRegion* last_region = _hrm.addr_to_region(last_address);
775
776 // Check for ranges that start in the same G1 region in which the previous
777 // range ended, and adjust the start address so we don't try to free
778 // the same region again. If the current range is entirely within that
779 // region, skip it.
780 if (start_region == prev_last_region) {
781 start_address = start_region->end();
782 if (start_address > last_address) {
783 continue;
784 }
785 start_region = _hrm.addr_to_region(start_address);
786 }
787 prev_last_region = last_region;
788
789 // After verifying that each region was marked as an archive region by
790 // alloc_archive_regions, set it free and empty and uncommit it.
791 HeapRegion* curr_region = start_region;
792 while (curr_region != NULL) {
793 guarantee(curr_region->is_archive(),
794 "Expected archive region at index %u", curr_region->hrm_index());
795 uint curr_index = curr_region->hrm_index();
796 _old_set.remove(curr_region);
797 curr_region->set_free();
798 curr_region->set_top(curr_region->bottom());
799 if (curr_region != last_region) {
800 curr_region = _hrm.next_region_in_heap(curr_region);
801 } else {
802 curr_region = NULL;
803 }
804 _hrm.shrink_at(curr_index, 1);
805 uncommitted_regions++;
806 }
807
808 // Notify mark-sweep that this is no longer an archive range.
809 G1ArchiveAllocator::set_range_archive(ranges[i], false);
810 }
811
812 if (uncommitted_regions != 0) {
813 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
814 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
815 }
816 decrease_used(size_used);
817 }
818
819 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
820 ResourceMark rm; // For retrieving the thread names in log messages.
821
822 // The structure of this method has a lot of similarities to
823 // attempt_allocation_slow(). The reason these two were not merged
824 // into a single one is that such a method would require several "if
825 // allocation is not humongous do this, otherwise do that"
826 // conditional paths which would obscure its flow. In fact, an early
827 // version of this code did use a unified method which was harder to
828 // follow and, as a result, it had subtle bugs that were hard to
829 // track down. So keeping these two methods separate allows each to
830 // be more readable. It will be good to keep these two in sync as
831 // much as possible.
832
833 assert_heap_not_locked_and_not_at_safepoint();
834 assert(is_humongous(word_size), "attempt_allocation_humongous() "
835 "should only be called for humongous allocations");
836
837 // Humongous objects can exhaust the heap quickly, so we should check if we
838 // need to start a marking cycle at each humongous object allocation. We do
839 // the check before we do the actual allocation. The reason for doing it
840 // before the allocation is that we avoid having to keep track of the newly
841 // allocated memory while we do a GC.
842 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
843 word_size)) {
844 collect(GCCause::_g1_humongous_allocation);
845 }
846
847 // We will loop until a) we manage to successfully perform the
848 // allocation or b) we successfully schedule a collection which
849 // fails to perform the allocation. b) is the only case when we'll
850 // return NULL.
851 HeapWord* result = NULL;
852 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
853 bool should_try_gc;
854 uint gc_count_before;
855
856
857 {
858 MutexLockerEx x(Heap_lock);
859
860 // Given that humongous objects are not allocated in young
861 // regions, we'll first try to do the allocation without doing a
862 // collection hoping that there's enough space in the heap.
863 result = humongous_obj_allocate(word_size);
864 if (result != NULL) {
865 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
866 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
867 return result;
868 }
869
870 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
871 // the GCLocker initiated GC has been performed and then retry. This includes
872 // the case when the GC Locker is not active but has not been performed.
873 should_try_gc = !GCLocker::needs_gc();
874 // Read the GC count while still holding the Heap_lock.
875 gc_count_before = total_collections();
876 }
877
878 if (should_try_gc) {
879 bool succeeded;
880 result = do_collection_pause(word_size, gc_count_before, &succeeded,
881 GCCause::_g1_humongous_allocation);
882 if (result != NULL) {
883 assert(succeeded, "only way to get back a non-NULL result");
884 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
885 Thread::current()->name(), p2i(result));
886 return result;
887 }
888
889 if (succeeded) {
890 // We successfully scheduled a collection which failed to allocate. No
891 // point in trying to allocate further. We'll just return NULL.
892 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
893 SIZE_FORMAT " words", Thread::current()->name(), word_size);
894 return NULL;
895 }
896 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
897 Thread::current()->name(), word_size);
898 } else {
899 // Failed to schedule a collection.
900 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
901 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
902 SIZE_FORMAT " words", Thread::current()->name(), word_size);
903 return NULL;
904 }
905 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
906 // The GCLocker is either active or the GCLocker initiated
907 // GC has not yet been performed. Stall until it is and
908 // then retry the allocation.
909 GCLocker::stall_until_clear();
910 gclocker_retry_count += 1;
911 }
912
913
914 // We can reach here if we were unsuccessful in scheduling a
915 // collection (because another thread beat us to it) or if we were
916 // stalled due to the GC locker. In either can we should retry the
917 // allocation attempt in case another thread successfully
918 // performed a collection and reclaimed enough space.
919 // Humongous object allocation always needs a lock, so we wait for the retry
920 // in the next iteration of the loop, unlike for the regular iteration case.
921 // Give a warning if we seem to be looping forever.
922
923 if ((QueuedAllocationWarningCount > 0) &&
924 (try_count % QueuedAllocationWarningCount == 0)) {
925 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
926 Thread::current()->name(), try_count, word_size);
927 }
928 }
929
930 ShouldNotReachHere();
931 return NULL;
932 }
933
934 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
935 bool expect_null_mutator_alloc_region) {
936 assert_at_safepoint_on_vm_thread();
937 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
938 "the current alloc region was unexpectedly found to be non-NULL");
939
940 if (!is_humongous(word_size)) {
941 return _allocator->attempt_allocation_locked(word_size);
942 } else {
943 HeapWord* result = humongous_obj_allocate(word_size);
944 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
945 collector_state()->set_initiate_conc_mark_if_possible(true);
946 }
947 return result;
948 }
949
950 ShouldNotReachHere();
951 }
952
953 class PostCompactionPrinterClosure: public HeapRegionClosure {
954 private:
955 G1HRPrinter* _hr_printer;
956 public:
957 bool do_heap_region(HeapRegion* hr) {
958 assert(!hr->is_young(), "not expecting to find young regions");
959 _hr_printer->post_compaction(hr);
960 return false;
961 }
962
963 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
964 : _hr_printer(hr_printer) { }
965 };
966
967 void G1CollectedHeap::print_hrm_post_compaction() {
968 if (_hr_printer.is_active()) {
969 PostCompactionPrinterClosure cl(hr_printer());
970 heap_region_iterate(&cl);
971 }
972 }
973
974 void G1CollectedHeap::abort_concurrent_cycle() {
975 // If we start the compaction before the CM threads finish
976 // scanning the root regions we might trip them over as we'll
977 // be moving objects / updating references. So let's wait until
978 // they are done. By telling them to abort, they should complete
979 // early.
980 _cm->root_regions()->abort();
981 _cm->root_regions()->wait_until_scan_finished();
982
983 // Disable discovery and empty the discovered lists
984 // for the CM ref processor.
985 ref_processor_cm()->disable_discovery();
986 ref_processor_cm()->abandon_partial_discovery();
987 ref_processor_cm()->verify_no_references_recorded();
988
989 // Abandon current iterations of concurrent marking and concurrent
990 // refinement, if any are in progress.
991 concurrent_mark()->concurrent_cycle_abort();
992 }
993
994 void G1CollectedHeap::prepare_heap_for_full_collection() {
995 // Make sure we'll choose a new allocation region afterwards.
996 _allocator->release_mutator_alloc_region();
997 _allocator->abandon_gc_alloc_regions();
998 g1_rem_set()->cleanupHRRS();
999
1000 // We may have added regions to the current incremental collection
1001 // set between the last GC or pause and now. We need to clear the
1002 // incremental collection set and then start rebuilding it afresh
1003 // after this full GC.
1004 abandon_collection_set(collection_set());
1005
1006 tear_down_region_sets(false /* free_list_only */);
1007 }
1008
1009 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1010 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1011 assert(used() == recalculate_used(), "Should be equal");
1012 _verifier->verify_region_sets_optional();
1013 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1014 _verifier->check_bitmaps("Full GC Start");
1015 }
1016
1017 void G1CollectedHeap::prepare_heap_for_mutators() {
1018 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1019 ClassLoaderDataGraph::purge();
1020 MetaspaceUtils::verify_metrics();
1021
1022 // Prepare heap for normal collections.
1023 assert(num_free_regions() == 0, "we should not have added any free regions");
1024 rebuild_region_sets(false /* free_list_only */);
1025 abort_refinement();
1026 resize_if_necessary_after_full_collection();
1027
1028 // Rebuild the strong code root lists for each region
1029 rebuild_strong_code_roots();
1030
1031 // Start a new incremental collection set for the next pause
1032 start_new_collection_set();
1033
1034 _allocator->init_mutator_alloc_region();
1035
1036 // Post collection state updates.
1037 MetaspaceGC::compute_new_size();
1038 }
1039
1040 void G1CollectedHeap::abort_refinement() {
1041 if (_hot_card_cache->use_cache()) {
1042 _hot_card_cache->reset_hot_cache();
1043 }
1044
1045 // Discard all remembered set updates.
1046 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1047 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1048 }
1049
1050 void G1CollectedHeap::verify_after_full_collection() {
1051 _hrm.verify_optional();
1052 _verifier->verify_region_sets_optional();
1053 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1054 // Clear the previous marking bitmap, if needed for bitmap verification.
1055 // Note we cannot do this when we clear the next marking bitmap in
1056 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1057 // objects marked during a full GC against the previous bitmap.
1058 // But we need to clear it before calling check_bitmaps below since
1059 // the full GC has compacted objects and updated TAMS but not updated
1060 // the prev bitmap.
1061 if (G1VerifyBitmaps) {
1062 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1063 _cm->clear_prev_bitmap(workers());
1064 }
1065 _verifier->check_bitmaps("Full GC End");
1066
1067 // At this point there should be no regions in the
1068 // entire heap tagged as young.
1069 assert(check_young_list_empty(), "young list should be empty at this point");
1070
1071 // Note: since we've just done a full GC, concurrent
1072 // marking is no longer active. Therefore we need not
1073 // re-enable reference discovery for the CM ref processor.
1074 // That will be done at the start of the next marking cycle.
1075 // We also know that the STW processor should no longer
1076 // discover any new references.
1077 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1078 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1079 ref_processor_stw()->verify_no_references_recorded();
1080 ref_processor_cm()->verify_no_references_recorded();
1081 }
1082
1083 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1084 // Post collection logging.
1085 // We should do this after we potentially resize the heap so
1086 // that all the COMMIT / UNCOMMIT events are generated before
1087 // the compaction events.
1088 print_hrm_post_compaction();
1089 heap_transition->print();
1090 print_heap_after_gc();
1091 print_heap_regions();
1092 #ifdef TRACESPINNING
1093 ParallelTaskTerminator::print_termination_counts();
1094 #endif
1095 }
1096
1097 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1098 bool clear_all_soft_refs) {
1099 assert_at_safepoint_on_vm_thread();
1100
1101 if (GCLocker::check_active_before_gc()) {
1102 // Full GC was not completed.
1103 return false;
1104 }
1105
1106 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1107 soft_ref_policy()->should_clear_all_soft_refs();
1108
1109 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1110 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1111
1112 collector.prepare_collection();
1113 collector.collect();
1114 collector.complete_collection();
1115
1116 // Full collection was successfully completed.
1117 return true;
1118 }
1119
1120 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1121 // Currently, there is no facility in the do_full_collection(bool) API to notify
1122 // the caller that the collection did not succeed (e.g., because it was locked
1123 // out by the GC locker). So, right now, we'll ignore the return value.
1124 bool dummy = do_full_collection(true, /* explicit_gc */
1125 clear_all_soft_refs);
1126 }
1127
1128 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1129 // Capacity, free and used after the GC counted as full regions to
1130 // include the waste in the following calculations.
1131 const size_t capacity_after_gc = capacity();
1132 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1133
1134 // This is enforced in arguments.cpp.
1135 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1136 "otherwise the code below doesn't make sense");
1137
1138 // We don't have floating point command-line arguments
1139 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1140 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1141 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1142 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1143
1144 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1145 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1146
1147 // We have to be careful here as these two calculations can overflow
1148 // 32-bit size_t's.
1149 double used_after_gc_d = (double) used_after_gc;
1150 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1151 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1152
1153 // Let's make sure that they are both under the max heap size, which
1154 // by default will make them fit into a size_t.
1155 double desired_capacity_upper_bound = (double) max_heap_size;
1156 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1157 desired_capacity_upper_bound);
1158 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1159 desired_capacity_upper_bound);
1160
1161 // We can now safely turn them into size_t's.
1162 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1163 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1164
1165 // This assert only makes sense here, before we adjust them
1166 // with respect to the min and max heap size.
1167 assert(minimum_desired_capacity <= maximum_desired_capacity,
1168 "minimum_desired_capacity = " SIZE_FORMAT ", "
1169 "maximum_desired_capacity = " SIZE_FORMAT,
1170 minimum_desired_capacity, maximum_desired_capacity);
1171
1172 // Should not be greater than the heap max size. No need to adjust
1173 // it with respect to the heap min size as it's a lower bound (i.e.,
1174 // we'll try to make the capacity larger than it, not smaller).
1175 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1176 // Should not be less than the heap min size. No need to adjust it
1177 // with respect to the heap max size as it's an upper bound (i.e.,
1178 // we'll try to make the capacity smaller than it, not greater).
1179 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1180
1181 if (capacity_after_gc < minimum_desired_capacity) {
1182 // Don't expand unless it's significant
1183 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1184
1185 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1186 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1187 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1188 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1189
1190 expand(expand_bytes, _workers);
1191
1192 // No expansion, now see if we want to shrink
1193 } else if (capacity_after_gc > maximum_desired_capacity) {
1194 // Capacity too large, compute shrinking size
1195 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1196
1197 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1198 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1199 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1200 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1201
1202 shrink(shrink_bytes);
1203 }
1204 }
1205
1206 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1207 bool do_gc,
1208 bool clear_all_soft_refs,
1209 bool expect_null_mutator_alloc_region,
1210 bool* gc_succeeded) {
1211 *gc_succeeded = true;
1212 // Let's attempt the allocation first.
1213 HeapWord* result =
1214 attempt_allocation_at_safepoint(word_size,
1215 expect_null_mutator_alloc_region);
1216 if (result != NULL) {
1217 return result;
1218 }
1219
1220 // In a G1 heap, we're supposed to keep allocation from failing by
1221 // incremental pauses. Therefore, at least for now, we'll favor
1222 // expansion over collection. (This might change in the future if we can
1223 // do something smarter than full collection to satisfy a failed alloc.)
1224 result = expand_and_allocate(word_size);
1225 if (result != NULL) {
1226 return result;
1227 }
1228
1229 if (do_gc) {
1230 // Expansion didn't work, we'll try to do a Full GC.
1231 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1232 clear_all_soft_refs);
1233 }
1234
1235 return NULL;
1236 }
1237
1238 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1239 bool* succeeded) {
1240 assert_at_safepoint_on_vm_thread();
1241
1242 // Attempts to allocate followed by Full GC.
1243 HeapWord* result =
1244 satisfy_failed_allocation_helper(word_size,
1245 true, /* do_gc */
1246 false, /* clear_all_soft_refs */
1247 false, /* expect_null_mutator_alloc_region */
1248 succeeded);
1249
1250 if (result != NULL || !*succeeded) {
1251 return result;
1252 }
1253
1254 // Attempts to allocate followed by Full GC that will collect all soft references.
1255 result = satisfy_failed_allocation_helper(word_size,
1256 true, /* do_gc */
1257 true, /* clear_all_soft_refs */
1258 true, /* expect_null_mutator_alloc_region */
1259 succeeded);
1260
1261 if (result != NULL || !*succeeded) {
1262 return result;
1263 }
1264
1265 // Attempts to allocate, no GC
1266 result = satisfy_failed_allocation_helper(word_size,
1267 false, /* do_gc */
1268 false, /* clear_all_soft_refs */
1269 true, /* expect_null_mutator_alloc_region */
1270 succeeded);
1271
1272 if (result != NULL) {
1273 return result;
1274 }
1275
1276 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1277 "Flag should have been handled and cleared prior to this point");
1278
1279 // What else? We might try synchronous finalization later. If the total
1280 // space available is large enough for the allocation, then a more
1281 // complete compaction phase than we've tried so far might be
1282 // appropriate.
1283 return NULL;
1284 }
1285
1286 // Attempting to expand the heap sufficiently
1287 // to support an allocation of the given "word_size". If
1288 // successful, perform the allocation and return the address of the
1289 // allocated block, or else "NULL".
1290
1291 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1292 assert_at_safepoint_on_vm_thread();
1293
1294 _verifier->verify_region_sets_optional();
1295
1296 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1297 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1298 word_size * HeapWordSize);
1299
1300
1301 if (expand(expand_bytes, _workers)) {
1302 _hrm.verify_optional();
1303 _verifier->verify_region_sets_optional();
1304 return attempt_allocation_at_safepoint(word_size,
1305 false /* expect_null_mutator_alloc_region */);
1306 }
1307 return NULL;
1308 }
1309
1310 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1311 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1312 aligned_expand_bytes = align_up(aligned_expand_bytes,
1313 HeapRegion::GrainBytes);
1314
1315 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1316 expand_bytes, aligned_expand_bytes);
1317
1318 if (is_maximal_no_gc()) {
1319 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1320 return false;
1321 }
1322
1323 double expand_heap_start_time_sec = os::elapsedTime();
1324 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1325 assert(regions_to_expand > 0, "Must expand by at least one region");
1326
1327 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1328 if (expand_time_ms != NULL) {
1329 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1330 }
1331
1332 if (expanded_by > 0) {
1333 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1334 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1335 g1_policy()->record_new_heap_size(num_regions());
1336 } else {
1337 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1338
1339 // The expansion of the virtual storage space was unsuccessful.
1340 // Let's see if it was because we ran out of swap.
1341 if (G1ExitOnExpansionFailure &&
1342 _hrm.available() >= regions_to_expand) {
1343 // We had head room...
1344 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1345 }
1346 }
1347 return regions_to_expand > 0;
1348 }
1349
1350 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1351 size_t aligned_shrink_bytes =
1352 ReservedSpace::page_align_size_down(shrink_bytes);
1353 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1354 HeapRegion::GrainBytes);
1355 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1356
1357 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1358 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1359
1360
1361 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",
1362 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1363 if (num_regions_removed > 0) {
1364 g1_policy()->record_new_heap_size(num_regions());
1365 } else {
1366 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1367 }
1368 }
1369
1370 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1371 _verifier->verify_region_sets_optional();
1372
1373 // We should only reach here at the end of a Full GC which means we
1374 // should not not be holding to any GC alloc regions. The method
1375 // below will make sure of that and do any remaining clean up.
1376 _allocator->abandon_gc_alloc_regions();
1377
1378 // Instead of tearing down / rebuilding the free lists here, we
1379 // could instead use the remove_all_pending() method on free_list to
1380 // remove only the ones that we need to remove.
1381 tear_down_region_sets(true /* free_list_only */);
1382 shrink_helper(shrink_bytes);
1383 rebuild_region_sets(true /* free_list_only */);
1384
1385 _hrm.verify_optional();
1386 _verifier->verify_region_sets_optional();
1387 }
1388
1389 // Public methods.
1390
1391 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1392 CollectedHeap(),
1393 _young_gen_sampling_thread(NULL),
1394 _collector_policy(collector_policy),
1395 _soft_ref_policy(),
1396 _card_table(NULL),
1397 _memory_manager("G1 Young Generation", "end of minor GC"),
1398 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1399 _eden_pool(NULL),
1400 _survivor_pool(NULL),
1401 _old_pool(NULL),
1402 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1403 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1404 _g1_policy(new G1Policy(_gc_timer_stw)),
1405 _collection_set(this, _g1_policy),
1406 _dirty_card_queue_set(false),
1407 _is_alive_closure_cm(this),
1408 _is_alive_closure_stw(this),
1409 _ref_processor_cm(NULL),
1410 _ref_processor_stw(NULL),
1411 _bot(NULL),
1412 _hot_card_cache(NULL),
1413 _g1_rem_set(NULL),
1414 _cr(NULL),
1415 _g1mm(NULL),
1416 _preserved_marks_set(true /* in_c_heap */),
1417 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1418 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1419 _humongous_reclaim_candidates(),
1420 _has_humongous_reclaim_candidates(false),
1421 _archive_allocator(NULL),
1422 _summary_bytes_used(0),
1423 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1424 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1425 _expand_heap_after_alloc_failure(true),
1426 _old_marking_cycles_started(0),
1427 _old_marking_cycles_completed(0),
1428 _in_cset_fast_test() {
1429
1430 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1431 /* are_GC_task_threads */true,
1432 /* are_ConcurrentGC_threads */false);
1433 _workers->initialize_workers();
1434 _verifier = new G1HeapVerifier(this);
1435
1436 _allocator = new G1Allocator(this);
1437
1438 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1439
1440 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1441
1442 // Override the default _filler_array_max_size so that no humongous filler
1443 // objects are created.
1444 _filler_array_max_size = _humongous_object_threshold_in_words;
1445
1446 uint n_queues = ParallelGCThreads;
1447 _task_queues = new RefToScanQueueSet(n_queues);
1448
1449 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1450
1451 for (uint i = 0; i < n_queues; i++) {
1452 RefToScanQueue* q = new RefToScanQueue();
1453 q->initialize();
1454 _task_queues->register_queue(i, q);
1455 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1456 }
1457
1458 // Initialize the G1EvacuationFailureALot counters and flags.
1459 NOT_PRODUCT(reset_evacuation_should_fail();)
1460
1461 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1462 }
1463
1464 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1465 size_t size,
1466 size_t translation_factor) {
1467 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1468 // Allocate a new reserved space, preferring to use large pages.
1469 ReservedSpace rs(size, preferred_page_size);
1470 G1RegionToSpaceMapper* result =
1471 G1RegionToSpaceMapper::create_mapper(rs,
1472 size,
1473 rs.alignment(),
1474 HeapRegion::GrainBytes,
1475 translation_factor,
1476 mtGC);
1477
1478 os::trace_page_sizes_for_requested_size(description,
1479 size,
1480 preferred_page_size,
1481 rs.alignment(),
1482 rs.base(),
1483 rs.size());
1484
1485 return result;
1486 }
1487
1488 jint G1CollectedHeap::initialize_concurrent_refinement() {
1489 jint ecode = JNI_OK;
1490 _cr = G1ConcurrentRefine::create(&ecode);
1491 return ecode;
1492 }
1493
1494 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1495 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1496 if (_young_gen_sampling_thread->osthread() == NULL) {
1497 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1498 return JNI_ENOMEM;
1499 }
1500 return JNI_OK;
1501 }
1502
1503 jint G1CollectedHeap::initialize() {
1504 os::enable_vtime();
1505
1506 // Necessary to satisfy locking discipline assertions.
1507
1508 MutexLocker x(Heap_lock);
1509
1510 // While there are no constraints in the GC code that HeapWordSize
1511 // be any particular value, there are multiple other areas in the
1512 // system which believe this to be true (e.g. oop->object_size in some
1513 // cases incorrectly returns the size in wordSize units rather than
1514 // HeapWordSize).
1515 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1516
1517 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1518 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1519 size_t heap_alignment = collector_policy()->heap_alignment();
1520
1521 // Ensure that the sizes are properly aligned.
1522 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1523 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1524 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1525
1526 // Reserve the maximum.
1527
1528 // When compressed oops are enabled, the preferred heap base
1529 // is calculated by subtracting the requested size from the
1530 // 32Gb boundary and using the result as the base address for
1531 // heap reservation. If the requested size is not aligned to
1532 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1533 // into the ReservedHeapSpace constructor) then the actual
1534 // base of the reserved heap may end up differing from the
1535 // address that was requested (i.e. the preferred heap base).
1536 // If this happens then we could end up using a non-optimal
1537 // compressed oops mode.
1538
1539 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1540 heap_alignment);
1541
1542 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1543
1544 // Create the barrier set for the entire reserved region.
1545 G1CardTable* ct = new G1CardTable(reserved_region());
1546 ct->initialize();
1547 G1BarrierSet* bs = new G1BarrierSet(ct);
1548 bs->initialize();
1549 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1550 BarrierSet::set_barrier_set(bs);
1551 _card_table = ct;
1552
1553 // Create the hot card cache.
1554 _hot_card_cache = new G1HotCardCache(this);
1555
1556 // Carve out the G1 part of the heap.
1557 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1558 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1559 G1RegionToSpaceMapper* heap_storage =
1560 G1RegionToSpaceMapper::create_mapper(g1_rs,
1561 g1_rs.size(),
1562 page_size,
1563 HeapRegion::GrainBytes,
1564 1,
1565 mtJavaHeap);
1566 os::trace_page_sizes("Heap",
1567 collector_policy()->min_heap_byte_size(),
1568 max_byte_size,
1569 page_size,
1570 heap_rs.base(),
1571 heap_rs.size());
1572 heap_storage->set_mapping_changed_listener(&_listener);
1573
1574 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1575 G1RegionToSpaceMapper* bot_storage =
1576 create_aux_memory_mapper("Block Offset Table",
1577 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1578 G1BlockOffsetTable::heap_map_factor());
1579
1580 G1RegionToSpaceMapper* cardtable_storage =
1581 create_aux_memory_mapper("Card Table",
1582 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1583 G1CardTable::heap_map_factor());
1584
1585 G1RegionToSpaceMapper* card_counts_storage =
1586 create_aux_memory_mapper("Card Counts Table",
1587 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1588 G1CardCounts::heap_map_factor());
1589
1590 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1591 G1RegionToSpaceMapper* prev_bitmap_storage =
1592 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1593 G1RegionToSpaceMapper* next_bitmap_storage =
1594 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1595
1596 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1597 _card_table->initialize(cardtable_storage);
1598 // Do later initialization work for concurrent refinement.
1599 _hot_card_cache->initialize(card_counts_storage);
1600
1601 // 6843694 - ensure that the maximum region index can fit
1602 // in the remembered set structures.
1603 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1604 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1605
1606 // Also create a G1 rem set.
1607 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1608 _g1_rem_set->initialize(max_capacity(), max_regions());
1609
1610 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1611 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1612 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1613 "too many cards per region");
1614
1615 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1616
1617 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1618
1619 {
1620 HeapWord* start = _hrm.reserved().start();
1621 HeapWord* end = _hrm.reserved().end();
1622 size_t granularity = HeapRegion::GrainBytes;
1623
1624 _in_cset_fast_test.initialize(start, end, granularity);
1625 _humongous_reclaim_candidates.initialize(start, end, granularity);
1626 }
1627
1628 // Create the G1ConcurrentMark data structure and thread.
1629 // (Must do this late, so that "max_regions" is defined.)
1630 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1631 if (_cm == NULL || !_cm->completed_initialization()) {
1632 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1633 return JNI_ENOMEM;
1634 }
1635 _cm_thread = _cm->cm_thread();
1636
1637 // Now expand into the initial heap size.
1638 if (!expand(init_byte_size, _workers)) {
1639 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1640 return JNI_ENOMEM;
1641 }
1642
1643 // Perform any initialization actions delegated to the policy.
1644 g1_policy()->init(this, &_collection_set);
1645
1646 G1BarrierSet::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1647 SATB_Q_FL_lock,
1648 G1SATBProcessCompletedThreshold,
1649 Shared_SATB_Q_lock);
1650
1651 jint ecode = initialize_concurrent_refinement();
1652 if (ecode != JNI_OK) {
1653 return ecode;
1654 }
1655
1656 ecode = initialize_young_gen_sampling_thread();
1657 if (ecode != JNI_OK) {
1658 return ecode;
1659 }
1660
1661 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1662 DirtyCardQ_FL_lock,
1663 (int)concurrent_refine()->yellow_zone(),
1664 (int)concurrent_refine()->red_zone(),
1665 Shared_DirtyCardQ_lock,
1666 NULL, // fl_owner
1667 true); // init_free_ids
1668
1669 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1670 DirtyCardQ_FL_lock,
1671 -1, // never trigger processing
1672 -1, // no limit on length
1673 Shared_DirtyCardQ_lock,
1674 &G1BarrierSet::dirty_card_queue_set());
1675
1676 // Here we allocate the dummy HeapRegion that is required by the
1677 // G1AllocRegion class.
1678 HeapRegion* dummy_region = _hrm.get_dummy_region();
1679
1680 // We'll re-use the same region whether the alloc region will
1681 // require BOT updates or not and, if it doesn't, then a non-young
1682 // region will complain that it cannot support allocations without
1683 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1684 dummy_region->set_eden();
1685 // Make sure it's full.
1686 dummy_region->set_top(dummy_region->end());
1687 G1AllocRegion::setup(this, dummy_region);
1688
1689 _allocator->init_mutator_alloc_region();
1690
1691 // Do create of the monitoring and management support so that
1692 // values in the heap have been properly initialized.
1693 _g1mm = new G1MonitoringSupport(this);
1694
1695 G1StringDedup::initialize();
1696
1697 _preserved_marks_set.init(ParallelGCThreads);
1698
1699 _collection_set.initialize(max_regions());
1700
1701 return JNI_OK;
1702 }
1703
1704 void G1CollectedHeap::initialize_serviceability() {
1705 _eden_pool = new G1EdenPool(this);
1706 _survivor_pool = new G1SurvivorPool(this);
1707 _old_pool = new G1OldGenPool(this);
1708
1709 _full_gc_memory_manager.add_pool(_eden_pool);
1710 _full_gc_memory_manager.add_pool(_survivor_pool);
1711 _full_gc_memory_manager.add_pool(_old_pool);
1712
1713 _memory_manager.add_pool(_eden_pool);
1714 _memory_manager.add_pool(_survivor_pool);
1715
1716 }
1717
1718 void G1CollectedHeap::stop() {
1719 // Stop all concurrent threads. We do this to make sure these threads
1720 // do not continue to execute and access resources (e.g. logging)
1721 // that are destroyed during shutdown.
1722 _cr->stop();
1723 _young_gen_sampling_thread->stop();
1724 _cm_thread->stop();
1725 if (G1StringDedup::is_enabled()) {
1726 G1StringDedup::stop();
1727 }
1728 }
1729
1730 void G1CollectedHeap::safepoint_synchronize_begin() {
1731 SuspendibleThreadSet::synchronize();
1732 }
1733
1734 void G1CollectedHeap::safepoint_synchronize_end() {
1735 SuspendibleThreadSet::desynchronize();
1736 }
1737
1738 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1739 return HeapRegion::max_region_size();
1740 }
1741
1742 void G1CollectedHeap::post_initialize() {
1743 CollectedHeap::post_initialize();
1744 ref_processing_init();
1745 }
1746
1747 void G1CollectedHeap::ref_processing_init() {
1748 // Reference processing in G1 currently works as follows:
1749 //
1750 // * There are two reference processor instances. One is
1751 // used to record and process discovered references
1752 // during concurrent marking; the other is used to
1753 // record and process references during STW pauses
1754 // (both full and incremental).
1755 // * Both ref processors need to 'span' the entire heap as
1756 // the regions in the collection set may be dotted around.
1757 //
1758 // * For the concurrent marking ref processor:
1759 // * Reference discovery is enabled at initial marking.
1760 // * Reference discovery is disabled and the discovered
1761 // references processed etc during remarking.
1762 // * Reference discovery is MT (see below).
1763 // * Reference discovery requires a barrier (see below).
1764 // * Reference processing may or may not be MT
1765 // (depending on the value of ParallelRefProcEnabled
1766 // and ParallelGCThreads).
1767 // * A full GC disables reference discovery by the CM
1768 // ref processor and abandons any entries on it's
1769 // discovered lists.
1770 //
1771 // * For the STW processor:
1772 // * Non MT discovery is enabled at the start of a full GC.
1773 // * Processing and enqueueing during a full GC is non-MT.
1774 // * During a full GC, references are processed after marking.
1775 //
1776 // * Discovery (may or may not be MT) is enabled at the start
1777 // of an incremental evacuation pause.
1778 // * References are processed near the end of a STW evacuation pause.
1779 // * For both types of GC:
1780 // * Discovery is atomic - i.e. not concurrent.
1781 // * Reference discovery will not need a barrier.
1782
1783 MemRegion mr = reserved_region();
1784
1785 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1786
1787 // Concurrent Mark ref processor
1788 _ref_processor_cm =
1789 new ReferenceProcessor(mr, // span
1790 mt_processing,
1791 // mt processing
1792 ParallelGCThreads,
1793 // degree of mt processing
1794 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1795 // mt discovery
1796 MAX2(ParallelGCThreads, ConcGCThreads),
1797 // degree of mt discovery
1798 false,
1799 // Reference discovery is not atomic
1800 &_is_alive_closure_cm);
1801 // is alive closure
1802 // (for efficiency/performance)
1803
1804 // STW ref processor
1805 _ref_processor_stw =
1806 new ReferenceProcessor(mr, // span
1807 mt_processing,
1808 // mt processing
1809 ParallelGCThreads,
1810 // degree of mt processing
1811 (ParallelGCThreads > 1),
1812 // mt discovery
1813 ParallelGCThreads,
1814 // degree of mt discovery
1815 true,
1816 // Reference discovery is atomic
1817 &_is_alive_closure_stw);
1818 // is alive closure
1819 // (for efficiency/performance)
1820 }
1821
1822 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1823 return _collector_policy;
1824 }
1825
1826 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1827 return &_soft_ref_policy;
1828 }
1829
1830 size_t G1CollectedHeap::capacity() const {
1831 return _hrm.length() * HeapRegion::GrainBytes;
1832 }
1833
1834 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1835 return _hrm.total_free_bytes();
1836 }
1837
1838 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1839 _hot_card_cache->drain(cl, worker_i);
1840 }
1841
1842 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1843 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1844 size_t n_completed_buffers = 0;
1845 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1846 n_completed_buffers++;
1847 }
1848 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1849 dcqs.clear_n_completed_buffers();
1850 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1851 }
1852
1853 // Computes the sum of the storage used by the various regions.
1854 size_t G1CollectedHeap::used() const {
1855 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1856 if (_archive_allocator != NULL) {
1857 result += _archive_allocator->used();
1858 }
1859 return result;
1860 }
1861
1862 size_t G1CollectedHeap::used_unlocked() const {
1863 return _summary_bytes_used;
1864 }
1865
1866 class SumUsedClosure: public HeapRegionClosure {
1867 size_t _used;
1868 public:
1869 SumUsedClosure() : _used(0) {}
1870 bool do_heap_region(HeapRegion* r) {
1871 _used += r->used();
1872 return false;
1873 }
1874 size_t result() { return _used; }
1875 };
1876
1877 size_t G1CollectedHeap::recalculate_used() const {
1878 double recalculate_used_start = os::elapsedTime();
1879
1880 SumUsedClosure blk;
1881 heap_region_iterate(&blk);
1882
1883 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1884 return blk.result();
1885 }
1886
1887 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1888 switch (cause) {
1889 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1890 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1891 case GCCause::_wb_conc_mark: return true;
1892 default : return false;
1893 }
1894 }
1895
1896 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1897 switch (cause) {
1898 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1899 case GCCause::_g1_humongous_allocation: return true;
1900 default: return is_user_requested_concurrent_full_gc(cause);
1901 }
1902 }
1903
1904 #ifndef PRODUCT
1905 void G1CollectedHeap::allocate_dummy_regions() {
1906 // Let's fill up most of the region
1907 size_t word_size = HeapRegion::GrainWords - 1024;
1908 // And as a result the region we'll allocate will be humongous.
1909 guarantee(is_humongous(word_size), "sanity");
1910
1911 // _filler_array_max_size is set to humongous object threshold
1912 // but temporarily change it to use CollectedHeap::fill_with_object().
1913 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1914
1915 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1916 // Let's use the existing mechanism for the allocation
1917 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1918 if (dummy_obj != NULL) {
1919 MemRegion mr(dummy_obj, word_size);
1920 CollectedHeap::fill_with_object(mr);
1921 } else {
1922 // If we can't allocate once, we probably cannot allocate
1923 // again. Let's get out of the loop.
1924 break;
1925 }
1926 }
1927 }
1928 #endif // !PRODUCT
1929
1930 void G1CollectedHeap::increment_old_marking_cycles_started() {
1931 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1932 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1933 "Wrong marking cycle count (started: %d, completed: %d)",
1934 _old_marking_cycles_started, _old_marking_cycles_completed);
1935
1936 _old_marking_cycles_started++;
1937 }
1938
1939 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
1940 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1941
1942 // We assume that if concurrent == true, then the caller is a
1943 // concurrent thread that was joined the Suspendible Thread
1944 // Set. If there's ever a cheap way to check this, we should add an
1945 // assert here.
1946
1947 // Given that this method is called at the end of a Full GC or of a
1948 // concurrent cycle, and those can be nested (i.e., a Full GC can
1949 // interrupt a concurrent cycle), the number of full collections
1950 // completed should be either one (in the case where there was no
1951 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1952 // behind the number of full collections started.
1953
1954 // This is the case for the inner caller, i.e. a Full GC.
1955 assert(concurrent ||
1956 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1957 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1958 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1959 "is inconsistent with _old_marking_cycles_completed = %u",
1960 _old_marking_cycles_started, _old_marking_cycles_completed);
1961
1962 // This is the case for the outer caller, i.e. the concurrent cycle.
1963 assert(!concurrent ||
1964 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1965 "for outer caller (concurrent cycle): "
1966 "_old_marking_cycles_started = %u "
1967 "is inconsistent with _old_marking_cycles_completed = %u",
1968 _old_marking_cycles_started, _old_marking_cycles_completed);
1969
1970 _old_marking_cycles_completed += 1;
1971
1972 // We need to clear the "in_progress" flag in the CM thread before
1973 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1974 // is set) so that if a waiter requests another System.gc() it doesn't
1975 // incorrectly see that a marking cycle is still in progress.
1976 if (concurrent) {
1977 _cm_thread->set_idle();
1978 }
1979
1980 // This notify_all() will ensure that a thread that called
1981 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
1982 // and it's waiting for a full GC to finish will be woken up. It is
1983 // waiting in VM_G1CollectForAllocation::doit_epilogue().
1984 FullGCCount_lock->notify_all();
1985 }
1986
1987 void G1CollectedHeap::collect(GCCause::Cause cause) {
1988 assert_heap_not_locked();
1989
1990 uint gc_count_before;
1991 uint old_marking_count_before;
1992 uint full_gc_count_before;
1993 bool retry_gc;
1994
1995 do {
1996 retry_gc = false;
1997
1998 {
1999 MutexLocker ml(Heap_lock);
2000
2001 // Read the GC count while holding the Heap_lock
2002 gc_count_before = total_collections();
2003 full_gc_count_before = total_full_collections();
2004 old_marking_count_before = _old_marking_cycles_started;
2005 }
2006
2007 if (should_do_concurrent_full_gc(cause)) {
2008 // Schedule an initial-mark evacuation pause that will start a
2009 // concurrent cycle. We're setting word_size to 0 which means that
2010 // we are not requesting a post-GC allocation.
2011 VM_G1CollectForAllocation op(0, /* word_size */
2012 gc_count_before,
2013 cause,
2014 true, /* should_initiate_conc_mark */
2015 g1_policy()->max_pause_time_ms());
2016 VMThread::execute(&op);
2017 if (!op.pause_succeeded()) {
2018 if (old_marking_count_before == _old_marking_cycles_started) {
2019 retry_gc = op.should_retry_gc();
2020 } else {
2021 // A Full GC happened while we were trying to schedule the
2022 // initial-mark GC. No point in starting a new cycle given
2023 // that the whole heap was collected anyway.
2024 }
2025
2026 if (retry_gc) {
2027 if (GCLocker::is_active_and_needs_gc()) {
2028 GCLocker::stall_until_clear();
2029 }
2030 }
2031 }
2032 } else {
2033 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2034 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2035
2036 // Schedule a standard evacuation pause. We're setting word_size
2037 // to 0 which means that we are not requesting a post-GC allocation.
2038 VM_G1CollectForAllocation op(0, /* word_size */
2039 gc_count_before,
2040 cause,
2041 false, /* should_initiate_conc_mark */
2042 g1_policy()->max_pause_time_ms());
2043 VMThread::execute(&op);
2044 } else {
2045 // Schedule a Full GC.
2046 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2047 VMThread::execute(&op);
2048 }
2049 }
2050 } while (retry_gc);
2051 }
2052
2053 bool G1CollectedHeap::is_in(const void* p) const {
2054 if (_hrm.reserved().contains(p)) {
2055 // Given that we know that p is in the reserved space,
2056 // heap_region_containing() should successfully
2057 // return the containing region.
2058 HeapRegion* hr = heap_region_containing(p);
2059 return hr->is_in(p);
2060 } else {
2061 return false;
2062 }
2063 }
2064
2065 #ifdef ASSERT
2066 bool G1CollectedHeap::is_in_exact(const void* p) const {
2067 bool contains = reserved_region().contains(p);
2068 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2069 if (contains && available) {
2070 return true;
2071 } else {
2072 return false;
2073 }
2074 }
2075 #endif
2076
2077 // Iteration functions.
2078
2079 // Iterates an ObjectClosure over all objects within a HeapRegion.
2080
2081 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2082 ObjectClosure* _cl;
2083 public:
2084 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2085 bool do_heap_region(HeapRegion* r) {
2086 if (!r->is_continues_humongous()) {
2087 r->object_iterate(_cl);
2088 }
2089 return false;
2090 }
2091 };
2092
2093 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2094 IterateObjectClosureRegionClosure blk(cl);
2095 heap_region_iterate(&blk);
2096 }
2097
2098 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2099 _hrm.iterate(cl);
2100 }
2101
2102 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2103 HeapRegionClaimer *hrclaimer,
2104 uint worker_id) const {
2105 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2106 }
2107
2108 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2109 HeapRegionClaimer *hrclaimer) const {
2110 _hrm.par_iterate(cl, hrclaimer, 0);
2111 }
2112
2113 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2114 _collection_set.iterate(cl);
2115 }
2116
2117 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2118 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2119 }
2120
2121 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2122 HeapRegion* hr = heap_region_containing(addr);
2123 return hr->block_start(addr);
2124 }
2125
2126 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2127 HeapRegion* hr = heap_region_containing(addr);
2128 return hr->block_size(addr);
2129 }
2130
2131 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2132 HeapRegion* hr = heap_region_containing(addr);
2133 return hr->block_is_obj(addr);
2134 }
2135
2136 bool G1CollectedHeap::supports_tlab_allocation() const {
2137 return true;
2138 }
2139
2140 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2141 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2142 }
2143
2144 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2145 return _eden.length() * HeapRegion::GrainBytes;
2146 }
2147
2148 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2149 // must be equal to the humongous object limit.
2150 size_t G1CollectedHeap::max_tlab_size() const {
2151 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2152 }
2153
2154 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2155 return _allocator->unsafe_max_tlab_alloc();
2156 }
2157
2158 size_t G1CollectedHeap::max_capacity() const {
2159 return _hrm.reserved().byte_size();
2160 }
2161
2162 jlong G1CollectedHeap::millis_since_last_gc() {
2163 // See the notes in GenCollectedHeap::millis_since_last_gc()
2164 // for more information about the implementation.
2165 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2166 _g1_policy->collection_pause_end_millis();
2167 if (ret_val < 0) {
2168 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2169 ". returning zero instead.", ret_val);
2170 return 0;
2171 }
2172 return ret_val;
2173 }
2174
2175 void G1CollectedHeap::prepare_for_verify() {
2176 _verifier->prepare_for_verify();
2177 }
2178
2179 void G1CollectedHeap::verify(VerifyOption vo) {
2180 _verifier->verify(vo);
2181 }
2182
2183 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2184 return true;
2185 }
2186
2187 const char* const* G1CollectedHeap::concurrent_phases() const {
2188 return _cm_thread->concurrent_phases();
2189 }
2190
2191 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2192 return _cm_thread->request_concurrent_phase(phase);
2193 }
2194
2195 class PrintRegionClosure: public HeapRegionClosure {
2196 outputStream* _st;
2197 public:
2198 PrintRegionClosure(outputStream* st) : _st(st) {}
2199 bool do_heap_region(HeapRegion* r) {
2200 r->print_on(_st);
2201 return false;
2202 }
2203 };
2204
2205 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2206 const HeapRegion* hr,
2207 const VerifyOption vo) const {
2208 switch (vo) {
2209 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2210 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2211 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2212 default: ShouldNotReachHere();
2213 }
2214 return false; // keep some compilers happy
2215 }
2216
2217 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2218 const VerifyOption vo) const {
2219 switch (vo) {
2220 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2221 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2222 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2223 default: ShouldNotReachHere();
2224 }
2225 return false; // keep some compilers happy
2226 }
2227
2228 void G1CollectedHeap::print_heap_regions() const {
2229 LogTarget(Trace, gc, heap, region) lt;
2230 if (lt.is_enabled()) {
2231 LogStream ls(lt);
2232 print_regions_on(&ls);
2233 }
2234 }
2235
2236 void G1CollectedHeap::print_on(outputStream* st) const {
2237 st->print(" %-20s", "garbage-first heap");
2238 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2239 capacity()/K, used_unlocked()/K);
2240 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2241 p2i(_hrm.reserved().start()),
2242 p2i(_hrm.reserved().end()));
2243 st->cr();
2244 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2245 uint young_regions = young_regions_count();
2246 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2247 (size_t) young_regions * HeapRegion::GrainBytes / K);
2248 uint survivor_regions = survivor_regions_count();
2249 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2250 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2251 st->cr();
2252 MetaspaceUtils::print_on(st);
2253 }
2254
2255 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2256 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2257 "HS=humongous(starts), HC=humongous(continues), "
2258 "CS=collection set, F=free, A=archive, "
2259 "TAMS=top-at-mark-start (previous, next)");
2260 PrintRegionClosure blk(st);
2261 heap_region_iterate(&blk);
2262 }
2263
2264 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2265 print_on(st);
2266
2267 // Print the per-region information.
2268 print_regions_on(st);
2269 }
2270
2271 void G1CollectedHeap::print_on_error(outputStream* st) const {
2272 this->CollectedHeap::print_on_error(st);
2273
2274 if (_cm != NULL) {
2275 st->cr();
2276 _cm->print_on_error(st);
2277 }
2278 }
2279
2280 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2281 workers()->print_worker_threads_on(st);
2282 _cm_thread->print_on(st);
2283 st->cr();
2284 _cm->print_worker_threads_on(st);
2285 _cr->print_threads_on(st);
2286 _young_gen_sampling_thread->print_on(st);
2287 if (G1StringDedup::is_enabled()) {
2288 G1StringDedup::print_worker_threads_on(st);
2289 }
2290 }
2291
2292 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2293 workers()->threads_do(tc);
2294 tc->do_thread(_cm_thread);
2295 _cm->threads_do(tc);
2296 _cr->threads_do(tc);
2297 tc->do_thread(_young_gen_sampling_thread);
2298 if (G1StringDedup::is_enabled()) {
2299 G1StringDedup::threads_do(tc);
2300 }
2301 }
2302
2303 void G1CollectedHeap::print_tracing_info() const {
2304 g1_rem_set()->print_summary_info();
2305 concurrent_mark()->print_summary_info();
2306 }
2307
2308 #ifndef PRODUCT
2309 // Helpful for debugging RSet issues.
2310
2311 class PrintRSetsClosure : public HeapRegionClosure {
2312 private:
2313 const char* _msg;
2314 size_t _occupied_sum;
2315
2316 public:
2317 bool do_heap_region(HeapRegion* r) {
2318 HeapRegionRemSet* hrrs = r->rem_set();
2319 size_t occupied = hrrs->occupied();
2320 _occupied_sum += occupied;
2321
2322 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2323 if (occupied == 0) {
2324 tty->print_cr(" RSet is empty");
2325 } else {
2326 hrrs->print();
2327 }
2328 tty->print_cr("----------");
2329 return false;
2330 }
2331
2332 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2333 tty->cr();
2334 tty->print_cr("========================================");
2335 tty->print_cr("%s", msg);
2336 tty->cr();
2337 }
2338
2339 ~PrintRSetsClosure() {
2340 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2341 tty->print_cr("========================================");
2342 tty->cr();
2343 }
2344 };
2345
2346 void G1CollectedHeap::print_cset_rsets() {
2347 PrintRSetsClosure cl("Printing CSet RSets");
2348 collection_set_iterate(&cl);
2349 }
2350
2351 void G1CollectedHeap::print_all_rsets() {
2352 PrintRSetsClosure cl("Printing All RSets");;
2353 heap_region_iterate(&cl);
2354 }
2355 #endif // PRODUCT
2356
2357 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2358
2359 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2360 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2361 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2362
2363 size_t eden_capacity_bytes =
2364 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2365
2366 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2367 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2368 eden_capacity_bytes, survivor_used_bytes, num_regions());
2369 }
2370
2371 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2372 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2373 stats->unused(), stats->used(), stats->region_end_waste(),
2374 stats->regions_filled(), stats->direct_allocated(),
2375 stats->failure_used(), stats->failure_waste());
2376 }
2377
2378 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2379 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2380 gc_tracer->report_gc_heap_summary(when, heap_summary);
2381
2382 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2383 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2384 }
2385
2386 G1CollectedHeap* G1CollectedHeap::heap() {
2387 CollectedHeap* heap = Universe::heap();
2388 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2389 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2390 return (G1CollectedHeap*)heap;
2391 }
2392
2393 void G1CollectedHeap::gc_prologue(bool full) {
2394 // always_do_update_barrier = false;
2395 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2396
2397 // This summary needs to be printed before incrementing total collections.
2398 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2399
2400 // Update common counters.
2401 increment_total_collections(full /* full gc */);
2402 if (full) {
2403 increment_old_marking_cycles_started();
2404 }
2405
2406 // Fill TLAB's and such
2407 double start = os::elapsedTime();
2408 accumulate_statistics_all_tlabs();
2409 ensure_parsability(true);
2410 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2411 }
2412
2413 void G1CollectedHeap::gc_epilogue(bool full) {
2414 // Update common counters.
2415 if (full) {
2416 // Update the number of full collections that have been completed.
2417 increment_old_marking_cycles_completed(false /* concurrent */);
2418 }
2419
2420 // We are at the end of the GC. Total collections has already been increased.
2421 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2422
2423 // FIXME: what is this about?
2424 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2425 // is set.
2426 #if COMPILER2_OR_JVMCI
2427 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2428 #endif
2429 // always_do_update_barrier = true;
2430
2431 double start = os::elapsedTime();
2432 resize_all_tlabs();
2433 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2434
2435 MemoryService::track_memory_usage();
2436 // We have just completed a GC. Update the soft reference
2437 // policy with the new heap occupancy
2438 Universe::update_heap_info_at_gc();
2439 }
2440
2441 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2442 uint gc_count_before,
2443 bool* succeeded,
2444 GCCause::Cause gc_cause) {
2445 assert_heap_not_locked_and_not_at_safepoint();
2446 VM_G1CollectForAllocation op(word_size,
2447 gc_count_before,
2448 gc_cause,
2449 false, /* should_initiate_conc_mark */
2450 g1_policy()->max_pause_time_ms());
2451 VMThread::execute(&op);
2452
2453 HeapWord* result = op.result();
2454 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2455 assert(result == NULL || ret_succeeded,
2456 "the result should be NULL if the VM did not succeed");
2457 *succeeded = ret_succeeded;
2458
2459 assert_heap_not_locked();
2460 return result;
2461 }
2462
2463 void G1CollectedHeap::do_concurrent_mark() {
2464 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2465 if (!_cm_thread->in_progress()) {
2466 _cm_thread->set_started();
2467 CGC_lock->notify();
2468 }
2469 }
2470
2471 size_t G1CollectedHeap::pending_card_num() {
2472 size_t extra_cards = 0;
2473 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2474 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2475 extra_cards += dcq.size();
2476 }
2477 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2478 size_t buffer_size = dcqs.buffer_size();
2479 size_t buffer_num = dcqs.completed_buffers_num();
2480
2481 return buffer_size * buffer_num + extra_cards;
2482 }
2483
2484 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2485 // We don't nominate objects with many remembered set entries, on
2486 // the assumption that such objects are likely still live.
2487 HeapRegionRemSet* rem_set = r->rem_set();
2488
2489 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2490 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2491 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2492 }
2493
2494 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2495 private:
2496 size_t _total_humongous;
2497 size_t _candidate_humongous;
2498
2499 DirtyCardQueue _dcq;
2500
2501 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2502 assert(region->is_starts_humongous(), "Must start a humongous object");
2503
2504 oop obj = oop(region->bottom());
2505
2506 // Dead objects cannot be eager reclaim candidates. Due to class
2507 // unloading it is unsafe to query their classes so we return early.
2508 if (g1h->is_obj_dead(obj, region)) {
2509 return false;
2510 }
2511
2512 // If we do not have a complete remembered set for the region, then we can
2513 // not be sure that we have all references to it.
2514 if (!region->rem_set()->is_complete()) {
2515 return false;
2516 }
2517 // Candidate selection must satisfy the following constraints
2518 // while concurrent marking is in progress:
2519 //
2520 // * In order to maintain SATB invariants, an object must not be
2521 // reclaimed if it was allocated before the start of marking and
2522 // has not had its references scanned. Such an object must have
2523 // its references (including type metadata) scanned to ensure no
2524 // live objects are missed by the marking process. Objects
2525 // allocated after the start of concurrent marking don't need to
2526 // be scanned.
2527 //
2528 // * An object must not be reclaimed if it is on the concurrent
2529 // mark stack. Objects allocated after the start of concurrent
2530 // marking are never pushed on the mark stack.
2531 //
2532 // Nominating only objects allocated after the start of concurrent
2533 // marking is sufficient to meet both constraints. This may miss
2534 // some objects that satisfy the constraints, but the marking data
2535 // structures don't support efficiently performing the needed
2536 // additional tests or scrubbing of the mark stack.
2537 //
2538 // However, we presently only nominate is_typeArray() objects.
2539 // A humongous object containing references induces remembered
2540 // set entries on other regions. In order to reclaim such an
2541 // object, those remembered sets would need to be cleaned up.
2542 //
2543 // We also treat is_typeArray() objects specially, allowing them
2544 // to be reclaimed even if allocated before the start of
2545 // concurrent mark. For this we rely on mark stack insertion to
2546 // exclude is_typeArray() objects, preventing reclaiming an object
2547 // that is in the mark stack. We also rely on the metadata for
2548 // such objects to be built-in and so ensured to be kept live.
2549 // Frequent allocation and drop of large binary blobs is an
2550 // important use case for eager reclaim, and this special handling
2551 // may reduce needed headroom.
2552
2553 return obj->is_typeArray() &&
2554 g1h->is_potential_eager_reclaim_candidate(region);
2555 }
2556
2557 public:
2558 RegisterHumongousWithInCSetFastTestClosure()
2559 : _total_humongous(0),
2560 _candidate_humongous(0),
2561 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2562 }
2563
2564 virtual bool do_heap_region(HeapRegion* r) {
2565 if (!r->is_starts_humongous()) {
2566 return false;
2567 }
2568 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2569
2570 bool is_candidate = humongous_region_is_candidate(g1h, r);
2571 uint rindex = r->hrm_index();
2572 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2573 if (is_candidate) {
2574 _candidate_humongous++;
2575 g1h->register_humongous_region_with_cset(rindex);
2576 // Is_candidate already filters out humongous object with large remembered sets.
2577 // If we have a humongous object with a few remembered sets, we simply flush these
2578 // remembered set entries into the DCQS. That will result in automatic
2579 // re-evaluation of their remembered set entries during the following evacuation
2580 // phase.
2581 if (!r->rem_set()->is_empty()) {
2582 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2583 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2584 G1CardTable* ct = g1h->card_table();
2585 HeapRegionRemSetIterator hrrs(r->rem_set());
2586 size_t card_index;
2587 while (hrrs.has_next(card_index)) {
2588 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2589 // The remembered set might contain references to already freed
2590 // regions. Filter out such entries to avoid failing card table
2591 // verification.
2592 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2593 if (*card_ptr != G1CardTable::dirty_card_val()) {
2594 *card_ptr = G1CardTable::dirty_card_val();
2595 _dcq.enqueue(card_ptr);
2596 }
2597 }
2598 }
2599 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2600 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2601 hrrs.n_yielded(), r->rem_set()->occupied());
2602 // We should only clear the card based remembered set here as we will not
2603 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2604 // (and probably never) we do not enter this path if there are other kind of
2605 // remembered sets for this region.
2606 r->rem_set()->clear_locked(true /* only_cardset */);
2607 // Clear_locked() above sets the state to Empty. However we want to continue
2608 // collecting remembered set entries for humongous regions that were not
2609 // reclaimed.
2610 r->rem_set()->set_state_complete();
2611 }
2612 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2613 }
2614 _total_humongous++;
2615
2616 return false;
2617 }
2618
2619 size_t total_humongous() const { return _total_humongous; }
2620 size_t candidate_humongous() const { return _candidate_humongous; }
2621
2622 void flush_rem_set_entries() { _dcq.flush(); }
2623 };
2624
2625 void G1CollectedHeap::register_humongous_regions_with_cset() {
2626 if (!G1EagerReclaimHumongousObjects) {
2627 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2628 return;
2629 }
2630 double time = os::elapsed_counter();
2631
2632 // Collect reclaim candidate information and register candidates with cset.
2633 RegisterHumongousWithInCSetFastTestClosure cl;
2634 heap_region_iterate(&cl);
2635
2636 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2637 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2638 cl.total_humongous(),
2639 cl.candidate_humongous());
2640 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2641
2642 // Finally flush all remembered set entries to re-check into the global DCQS.
2643 cl.flush_rem_set_entries();
2644 }
2645
2646 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2647 public:
2648 bool do_heap_region(HeapRegion* hr) {
2649 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2650 hr->verify_rem_set();
2651 }
2652 return false;
2653 }
2654 };
2655
2656 uint G1CollectedHeap::num_task_queues() const {
2657 return _task_queues->size();
2658 }
2659
2660 #if TASKQUEUE_STATS
2661 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2662 st->print_raw_cr("GC Task Stats");
2663 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2664 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2665 }
2666
2667 void G1CollectedHeap::print_taskqueue_stats() const {
2668 if (!log_is_enabled(Trace, gc, task, stats)) {
2669 return;
2670 }
2671 Log(gc, task, stats) log;
2672 ResourceMark rm;
2673 LogStream ls(log.trace());
2674 outputStream* st = &ls;
2675
2676 print_taskqueue_stats_hdr(st);
2677
2678 TaskQueueStats totals;
2679 const uint n = num_task_queues();
2680 for (uint i = 0; i < n; ++i) {
2681 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2682 totals += task_queue(i)->stats;
2683 }
2684 st->print_raw("tot "); totals.print(st); st->cr();
2685
2686 DEBUG_ONLY(totals.verify());
2687 }
2688
2689 void G1CollectedHeap::reset_taskqueue_stats() {
2690 const uint n = num_task_queues();
2691 for (uint i = 0; i < n; ++i) {
2692 task_queue(i)->stats.reset();
2693 }
2694 }
2695 #endif // TASKQUEUE_STATS
2696
2697 void G1CollectedHeap::wait_for_root_region_scanning() {
2698 double scan_wait_start = os::elapsedTime();
2699 // We have to wait until the CM threads finish scanning the
2700 // root regions as it's the only way to ensure that all the
2701 // objects on them have been correctly scanned before we start
2702 // moving them during the GC.
2703 bool waited = _cm->root_regions()->wait_until_scan_finished();
2704 double wait_time_ms = 0.0;
2705 if (waited) {
2706 double scan_wait_end = os::elapsedTime();
2707 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2708 }
2709 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2710 }
2711
2712 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2713 private:
2714 G1HRPrinter* _hr_printer;
2715 public:
2716 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2717
2718 virtual bool do_heap_region(HeapRegion* r) {
2719 _hr_printer->cset(r);
2720 return false;
2721 }
2722 };
2723
2724 void G1CollectedHeap::start_new_collection_set() {
2725 collection_set()->start_incremental_building();
2726
2727 clear_cset_fast_test();
2728
2729 guarantee(_eden.length() == 0, "eden should have been cleared");
2730 g1_policy()->transfer_survivors_to_cset(survivor());
2731 }
2732
2733 bool
2734 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2735 assert_at_safepoint_on_vm_thread();
2736 guarantee(!is_gc_active(), "collection is not reentrant");
2737
2738 if (GCLocker::check_active_before_gc()) {
2739 return false;
2740 }
2741
2742 _gc_timer_stw->register_gc_start();
2743
2744 GCIdMark gc_id_mark;
2745 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2746
2747 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2748 ResourceMark rm;
2749
2750 g1_policy()->note_gc_start();
2751
2752 wait_for_root_region_scanning();
2753
2754 print_heap_before_gc();
2755 print_heap_regions();
2756 trace_heap_before_gc(_gc_tracer_stw);
2757
2758 _verifier->verify_region_sets_optional();
2759 _verifier->verify_dirty_young_regions();
2760
2761 // We should not be doing initial mark unless the conc mark thread is running
2762 if (!_cm_thread->should_terminate()) {
2763 // This call will decide whether this pause is an initial-mark
2764 // pause. If it is, in_initial_mark_gc() will return true
2765 // for the duration of this pause.
2766 g1_policy()->decide_on_conc_mark_initiation();
2767 }
2768
2769 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2770 assert(!collector_state()->in_initial_mark_gc() ||
2771 collector_state()->in_young_only_phase(), "sanity");
2772
2773 // We also do not allow mixed GCs during marking.
2774 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2775
2776 // Record whether this pause is an initial mark. When the current
2777 // thread has completed its logging output and it's safe to signal
2778 // the CM thread, the flag's value in the policy has been reset.
2779 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2780
2781 // Inner scope for scope based logging, timers, and stats collection
2782 {
2783 EvacuationInfo evacuation_info;
2784
2785 if (collector_state()->in_initial_mark_gc()) {
2786 // We are about to start a marking cycle, so we increment the
2787 // full collection counter.
2788 increment_old_marking_cycles_started();
2789 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2790 }
2791
2792 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2793
2794 GCTraceCPUTime tcpu;
2795
2796 G1HeapVerifier::G1VerifyType verify_type;
2797 FormatBuffer<> gc_string("Pause ");
2798 if (collector_state()->in_initial_mark_gc()) {
2799 gc_string.append("Initial Mark");
2800 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2801 } else if (collector_state()->in_young_only_phase()) {
2802 gc_string.append("Young");
2803 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2804 } else {
2805 gc_string.append("Mixed");
2806 verify_type = G1HeapVerifier::G1VerifyMixed;
2807 }
2808 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2809
2810 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2811 workers()->active_workers(),
2812 Threads::number_of_non_daemon_threads());
2813 active_workers = workers()->update_active_workers(active_workers);
2814 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2815
2816 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2817 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2818
2819 G1HeapTransition heap_transition(this);
2820 size_t heap_used_bytes_before_gc = used();
2821
2822 // Don't dynamically change the number of GC threads this early. A value of
2823 // 0 is used to indicate serial work. When parallel work is done,
2824 // it will be set.
2825
2826 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2827 IsGCActiveMark x;
2828
2829 gc_prologue(false);
2830
2831 if (VerifyRememberedSets) {
2832 log_info(gc, verify)("[Verifying RemSets before GC]");
2833 VerifyRegionRemSetClosure v_cl;
2834 heap_region_iterate(&v_cl);
2835 }
2836
2837 _verifier->verify_before_gc(verify_type);
2838
2839 _verifier->check_bitmaps("GC Start");
2840
2841 #if COMPILER2_OR_JVMCI
2842 DerivedPointerTable::clear();
2843 #endif
2844
2845 // Please see comment in g1CollectedHeap.hpp and
2846 // G1CollectedHeap::ref_processing_init() to see how
2847 // reference processing currently works in G1.
2848
2849 // Enable discovery in the STW reference processor
2850 ref_processor_stw()->enable_discovery();
2851
2852 {
2853 // We want to temporarily turn off discovery by the
2854 // CM ref processor, if necessary, and turn it back on
2855 // on again later if we do. Using a scoped
2856 // NoRefDiscovery object will do this.
2857 NoRefDiscovery no_cm_discovery(ref_processor_cm());
2858
2859 // Forget the current alloc region (we might even choose it to be part
2860 // of the collection set!).
2861 _allocator->release_mutator_alloc_region();
2862
2863 // This timing is only used by the ergonomics to handle our pause target.
2864 // It is unclear why this should not include the full pause. We will
2865 // investigate this in CR 7178365.
2866 //
2867 // Preserving the old comment here if that helps the investigation:
2868 //
2869 // The elapsed time induced by the start time below deliberately elides
2870 // the possible verification above.
2871 double sample_start_time_sec = os::elapsedTime();
2872
2873 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2874
2875 if (collector_state()->in_initial_mark_gc()) {
2876 concurrent_mark()->pre_initial_mark();
2877 }
2878
2879 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2880
2881 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2882
2883 // Make sure the remembered sets are up to date. This needs to be
2884 // done before register_humongous_regions_with_cset(), because the
2885 // remembered sets are used there to choose eager reclaim candidates.
2886 // If the remembered sets are not up to date we might miss some
2887 // entries that need to be handled.
2888 g1_rem_set()->cleanupHRRS();
2889
2890 register_humongous_regions_with_cset();
2891
2892 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2893
2894 // We call this after finalize_cset() to
2895 // ensure that the CSet has been finalized.
2896 _cm->verify_no_cset_oops();
2897
2898 if (_hr_printer.is_active()) {
2899 G1PrintCollectionSetClosure cl(&_hr_printer);
2900 _collection_set.iterate(&cl);
2901 }
2902
2903 // Initialize the GC alloc regions.
2904 _allocator->init_gc_alloc_regions(evacuation_info);
2905
2906 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2907 pre_evacuate_collection_set();
2908
2909 // Actually do the work...
2910 evacuate_collection_set(&per_thread_states);
2911
2912 post_evacuate_collection_set(evacuation_info, &per_thread_states);
2913
2914 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2915 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2916
2917 eagerly_reclaim_humongous_regions();
2918
2919 record_obj_copy_mem_stats();
2920 _survivor_evac_stats.adjust_desired_plab_sz();
2921 _old_evac_stats.adjust_desired_plab_sz();
2922
2923 double start = os::elapsedTime();
2924 start_new_collection_set();
2925 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2926
2927 if (evacuation_failed()) {
2928 set_used(recalculate_used());
2929 if (_archive_allocator != NULL) {
2930 _archive_allocator->clear_used();
2931 }
2932 for (uint i = 0; i < ParallelGCThreads; i++) {
2933 if (_evacuation_failed_info_array[i].has_failed()) {
2934 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
2935 }
2936 }
2937 } else {
2938 // The "used" of the the collection set have already been subtracted
2939 // when they were freed. Add in the bytes evacuated.
2940 increase_used(g1_policy()->bytes_copied_during_gc());
2941 }
2942
2943 if (collector_state()->in_initial_mark_gc()) {
2944 // We have to do this before we notify the CM threads that
2945 // they can start working to make sure that all the
2946 // appropriate initialization is done on the CM object.
2947 concurrent_mark()->post_initial_mark();
2948 // Note that we don't actually trigger the CM thread at
2949 // this point. We do that later when we're sure that
2950 // the current thread has completed its logging output.
2951 }
2952
2953 allocate_dummy_regions();
2954
2955 _allocator->init_mutator_alloc_region();
2956
2957 {
2958 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2959 if (expand_bytes > 0) {
2960 size_t bytes_before = capacity();
2961 // No need for an ergo logging here,
2962 // expansion_amount() does this when it returns a value > 0.
2963 double expand_ms;
2964 if (!expand(expand_bytes, _workers, &expand_ms)) {
2965 // We failed to expand the heap. Cannot do anything about it.
2966 }
2967 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
2968 }
2969 }
2970
2971 // We redo the verification but now wrt to the new CSet which
2972 // has just got initialized after the previous CSet was freed.
2973 _cm->verify_no_cset_oops();
2974
2975 // This timing is only used by the ergonomics to handle our pause target.
2976 // It is unclear why this should not include the full pause. We will
2977 // investigate this in CR 7178365.
2978 double sample_end_time_sec = os::elapsedTime();
2979 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
2980 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
2981 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
2982
2983 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
2984 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
2985
2986 if (VerifyRememberedSets) {
2987 log_info(gc, verify)("[Verifying RemSets after GC]");
2988 VerifyRegionRemSetClosure v_cl;
2989 heap_region_iterate(&v_cl);
2990 }
2991
2992 _verifier->verify_after_gc(verify_type);
2993 _verifier->check_bitmaps("GC End");
2994
2995 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
2996 ref_processor_stw()->verify_no_references_recorded();
2997
2998 // CM reference discovery will be re-enabled if necessary.
2999 }
3000
3001 #ifdef TRACESPINNING
3002 ParallelTaskTerminator::print_termination_counts();
3003 #endif
3004
3005 gc_epilogue(false);
3006 }
3007
3008 // Print the remainder of the GC log output.
3009 if (evacuation_failed()) {
3010 log_info(gc)("To-space exhausted");
3011 }
3012
3013 g1_policy()->print_phases();
3014 heap_transition.print();
3015
3016 // It is not yet to safe to tell the concurrent mark to
3017 // start as we have some optional output below. We don't want the
3018 // output from the concurrent mark thread interfering with this
3019 // logging output either.
3020
3021 _hrm.verify_optional();
3022 _verifier->verify_region_sets_optional();
3023
3024 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3025 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3026
3027 print_heap_after_gc();
3028 print_heap_regions();
3029 trace_heap_after_gc(_gc_tracer_stw);
3030
3031 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3032 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3033 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3034 // before any GC notifications are raised.
3035 g1mm()->update_sizes();
3036
3037 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3038 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3039 _gc_timer_stw->register_gc_end();
3040 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3041 }
3042 // It should now be safe to tell the concurrent mark thread to start
3043 // without its logging output interfering with the logging output
3044 // that came from the pause.
3045
3046 if (should_start_conc_mark) {
3047 // CAUTION: after the doConcurrentMark() call below,
3048 // the concurrent marking thread(s) could be running
3049 // concurrently with us. Make sure that anything after
3050 // this point does not assume that we are the only GC thread
3051 // running. Note: of course, the actual marking work will
3052 // not start until the safepoint itself is released in
3053 // SuspendibleThreadSet::desynchronize().
3054 do_concurrent_mark();
3055 }
3056
3057 return true;
3058 }
3059
3060 void G1CollectedHeap::remove_self_forwarding_pointers() {
3061 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3062 workers()->run_task(&rsfp_task);
3063 }
3064
3065 void G1CollectedHeap::restore_after_evac_failure() {
3066 double remove_self_forwards_start = os::elapsedTime();
3067
3068 remove_self_forwarding_pointers();
3069 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3070 _preserved_marks_set.restore(&task_executor);
3071
3072 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3073 }
3074
3075 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3076 if (!_evacuation_failed) {
3077 _evacuation_failed = true;
3078 }
3079
3080 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3081 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3082 }
3083
3084 bool G1ParEvacuateFollowersClosure::offer_termination() {
3085 G1ParScanThreadState* const pss = par_scan_state();
3086 start_term_time();
3087 const bool res = terminator()->offer_termination();
3088 end_term_time();
3089 return res;
3090 }
3091
3092 void G1ParEvacuateFollowersClosure::do_void() {
3093 G1ParScanThreadState* const pss = par_scan_state();
3094 pss->trim_queue();
3095 do {
3096 pss->steal_and_trim_queue(queues());
3097 } while (!offer_termination());
3098 }
3099
3100 class G1ParTask : public AbstractGangTask {
3101 protected:
3102 G1CollectedHeap* _g1h;
3103 G1ParScanThreadStateSet* _pss;
3104 RefToScanQueueSet* _queues;
3105 G1RootProcessor* _root_processor;
3106 ParallelTaskTerminator _terminator;
3107 uint _n_workers;
3108
3109 public:
3110 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3111 : AbstractGangTask("G1 collection"),
3112 _g1h(g1h),
3113 _pss(per_thread_states),
3114 _queues(task_queues),
3115 _root_processor(root_processor),
3116 _terminator(n_workers, _queues),
3117 _n_workers(n_workers)
3118 {}
3119
3120 void work(uint worker_id) {
3121 if (worker_id >= _n_workers) return; // no work needed this round
3122
3123 double start_sec = os::elapsedTime();
3124 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3125
3126 {
3127 ResourceMark rm;
3128 HandleMark hm;
3129
3130 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3131
3132 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3133 pss->set_ref_processor(rp);
3134
3135 double start_strong_roots_sec = os::elapsedTime();
3136
3137 _root_processor->evacuate_roots(pss->closures(), worker_id);
3138
3139 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3140 // treating the nmethods visited to act as roots for concurrent marking.
3141 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3142 // objects copied by the current evacuation.
3143 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3144 pss->closures()->weak_codeblobs(),
3145 worker_id);
3146
3147 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3148
3149 double term_sec = 0.0;
3150 size_t evac_term_attempts = 0;
3151 {
3152 double start = os::elapsedTime();
3153 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3154 evac.do_void();
3155
3156 evac_term_attempts = evac.term_attempts();
3157 term_sec = evac.term_time();
3158 double elapsed_sec = os::elapsedTime() - start;
3159 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3160 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3161 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3162 }
3163
3164 assert(pss->queue_is_empty(), "should be empty");
3165
3166 if (log_is_enabled(Debug, gc, task, stats)) {
3167 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3168 size_t lab_waste;
3169 size_t lab_undo_waste;
3170 pss->waste(lab_waste, lab_undo_waste);
3171 _g1h->print_termination_stats(worker_id,
3172 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3173 strong_roots_sec * 1000.0, /* strong roots time */
3174 term_sec * 1000.0, /* evac term time */
3175 evac_term_attempts, /* evac term attempts */
3176 lab_waste, /* alloc buffer waste */
3177 lab_undo_waste /* undo waste */
3178 );
3179 }
3180
3181 // Close the inner scope so that the ResourceMark and HandleMark
3182 // destructors are executed here and are included as part of the
3183 // "GC Worker Time".
3184 }
3185 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3186 }
3187 };
3188
3189 void G1CollectedHeap::print_termination_stats_hdr() {
3190 log_debug(gc, task, stats)("GC Termination Stats");
3191 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3192 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3193 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3194 }
3195
3196 void G1CollectedHeap::print_termination_stats(uint worker_id,
3197 double elapsed_ms,
3198 double strong_roots_ms,
3199 double term_ms,
3200 size_t term_attempts,
3201 size_t alloc_buffer_waste,
3202 size_t undo_waste) const {
3203 log_debug(gc, task, stats)
3204 ("%3d %9.2f %9.2f %6.2f "
3205 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3206 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3207 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3208 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3209 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3210 alloc_buffer_waste * HeapWordSize / K,
3211 undo_waste * HeapWordSize / K);
3212 }
3213
3214 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3215 private:
3216 BoolObjectClosure* _is_alive;
3217 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3218
3219 int _initial_string_table_size;
3220 int _initial_symbol_table_size;
3221
3222 bool _process_strings;
3223 int _strings_processed;
3224 int _strings_removed;
3225
3226 bool _process_symbols;
3227 int _symbols_processed;
3228 int _symbols_removed;
3229
3230 bool _process_string_dedup;
3231
3232 public:
3233 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3234 AbstractGangTask("String/Symbol Unlinking"),
3235 _is_alive(is_alive),
3236 _dedup_closure(is_alive, NULL, false),
3237 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3238 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3239 _process_string_dedup(process_string_dedup) {
3240
3241 _initial_string_table_size = StringTable::the_table()->table_size();
3242 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3243 if (process_strings) {
3244 StringTable::clear_parallel_claimed_index();
3245 }
3246 if (process_symbols) {
3247 SymbolTable::clear_parallel_claimed_index();
3248 }
3249 }
3250
3251 ~G1StringAndSymbolCleaningTask() {
3252 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3253 "claim value %d after unlink less than initial string table size %d",
3254 StringTable::parallel_claimed_index(), _initial_string_table_size);
3255 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3256 "claim value %d after unlink less than initial symbol table size %d",
3257 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3258
3259 log_info(gc, stringtable)(
3260 "Cleaned string and symbol table, "
3261 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3262 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3263 strings_processed(), strings_removed(),
3264 symbols_processed(), symbols_removed());
3265 }
3266
3267 void work(uint worker_id) {
3268 int strings_processed = 0;
3269 int strings_removed = 0;
3270 int symbols_processed = 0;
3271 int symbols_removed = 0;
3272 if (_process_strings) {
3273 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3274 Atomic::add(strings_processed, &_strings_processed);
3275 Atomic::add(strings_removed, &_strings_removed);
3276 }
3277 if (_process_symbols) {
3278 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3279 Atomic::add(symbols_processed, &_symbols_processed);
3280 Atomic::add(symbols_removed, &_symbols_removed);
3281 }
3282 if (_process_string_dedup) {
3283 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3284 }
3285 }
3286
3287 size_t strings_processed() const { return (size_t)_strings_processed; }
3288 size_t strings_removed() const { return (size_t)_strings_removed; }
3289
3290 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3291 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3292 };
3293
3294 class G1CodeCacheUnloadingTask {
3295 private:
3296 static Monitor* _lock;
3297
3298 BoolObjectClosure* const _is_alive;
3299 const bool _unloading_occurred;
3300 const uint _num_workers;
3301
3302 // Variables used to claim nmethods.
3303 CompiledMethod* _first_nmethod;
3304 CompiledMethod* volatile _claimed_nmethod;
3305
3306 // The list of nmethods that need to be processed by the second pass.
3307 CompiledMethod* volatile _postponed_list;
3308 volatile uint _num_entered_barrier;
3309
3310 public:
3311 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3312 _is_alive(is_alive),
3313 _unloading_occurred(unloading_occurred),
3314 _num_workers(num_workers),
3315 _first_nmethod(NULL),
3316 _claimed_nmethod(NULL),
3317 _postponed_list(NULL),
3318 _num_entered_barrier(0)
3319 {
3320 CompiledMethod::increase_unloading_clock();
3321 // Get first alive nmethod
3322 CompiledMethodIterator iter = CompiledMethodIterator();
3323 if(iter.next_alive()) {
3324 _first_nmethod = iter.method();
3325 }
3326 _claimed_nmethod = _first_nmethod;
3327 }
3328
3329 ~G1CodeCacheUnloadingTask() {
3330 CodeCache::verify_clean_inline_caches();
3331
3332 CodeCache::set_needs_cache_clean(false);
3333 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3334
3335 CodeCache::verify_icholder_relocations();
3336 }
3337
3338 private:
3339 void add_to_postponed_list(CompiledMethod* nm) {
3340 CompiledMethod* old;
3341 do {
3342 old = _postponed_list;
3343 nm->set_unloading_next(old);
3344 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3345 }
3346
3347 void clean_nmethod(CompiledMethod* nm) {
3348 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3349
3350 if (postponed) {
3351 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3352 add_to_postponed_list(nm);
3353 }
3354
3355 // Mark that this thread has been cleaned/unloaded.
3356 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3357 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3358 }
3359
3360 void clean_nmethod_postponed(CompiledMethod* nm) {
3361 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3362 }
3363
3364 static const int MaxClaimNmethods = 16;
3365
3366 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3367 CompiledMethod* first;
3368 CompiledMethodIterator last;
3369
3370 do {
3371 *num_claimed_nmethods = 0;
3372
3373 first = _claimed_nmethod;
3374 last = CompiledMethodIterator(first);
3375
3376 if (first != NULL) {
3377
3378 for (int i = 0; i < MaxClaimNmethods; i++) {
3379 if (!last.next_alive()) {
3380 break;
3381 }
3382 claimed_nmethods[i] = last.method();
3383 (*num_claimed_nmethods)++;
3384 }
3385 }
3386
3387 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3388 }
3389
3390 CompiledMethod* claim_postponed_nmethod() {
3391 CompiledMethod* claim;
3392 CompiledMethod* next;
3393
3394 do {
3395 claim = _postponed_list;
3396 if (claim == NULL) {
3397 return NULL;
3398 }
3399
3400 next = claim->unloading_next();
3401
3402 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3403
3404 return claim;
3405 }
3406
3407 public:
3408 // Mark that we're done with the first pass of nmethod cleaning.
3409 void barrier_mark(uint worker_id) {
3410 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3411 _num_entered_barrier++;
3412 if (_num_entered_barrier == _num_workers) {
3413 ml.notify_all();
3414 }
3415 }
3416
3417 // See if we have to wait for the other workers to
3418 // finish their first-pass nmethod cleaning work.
3419 void barrier_wait(uint worker_id) {
3420 if (_num_entered_barrier < _num_workers) {
3421 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3422 while (_num_entered_barrier < _num_workers) {
3423 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3424 }
3425 }
3426 }
3427
3428 // Cleaning and unloading of nmethods. Some work has to be postponed
3429 // to the second pass, when we know which nmethods survive.
3430 void work_first_pass(uint worker_id) {
3431 // The first nmethods is claimed by the first worker.
3432 if (worker_id == 0 && _first_nmethod != NULL) {
3433 clean_nmethod(_first_nmethod);
3434 _first_nmethod = NULL;
3435 }
3436
3437 int num_claimed_nmethods;
3438 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3439
3440 while (true) {
3441 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3442
3443 if (num_claimed_nmethods == 0) {
3444 break;
3445 }
3446
3447 for (int i = 0; i < num_claimed_nmethods; i++) {
3448 clean_nmethod(claimed_nmethods[i]);
3449 }
3450 }
3451 }
3452
3453 void work_second_pass(uint worker_id) {
3454 CompiledMethod* nm;
3455 // Take care of postponed nmethods.
3456 while ((nm = claim_postponed_nmethod()) != NULL) {
3457 clean_nmethod_postponed(nm);
3458 }
3459 }
3460 };
3461
3462 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3463
3464 class G1KlassCleaningTask : public StackObj {
3465 BoolObjectClosure* _is_alive;
3466 volatile int _clean_klass_tree_claimed;
3467 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3468
3469 public:
3470 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3471 _is_alive(is_alive),
3472 _clean_klass_tree_claimed(0),
3473 _klass_iterator() {
3474 }
3475
3476 private:
3477 bool claim_clean_klass_tree_task() {
3478 if (_clean_klass_tree_claimed) {
3479 return false;
3480 }
3481
3482 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3483 }
3484
3485 InstanceKlass* claim_next_klass() {
3486 Klass* klass;
3487 do {
3488 klass =_klass_iterator.next_klass();
3489 } while (klass != NULL && !klass->is_instance_klass());
3490
3491 // this can be null so don't call InstanceKlass::cast
3492 return static_cast<InstanceKlass*>(klass);
3493 }
3494
3495 public:
3496
3497 void clean_klass(InstanceKlass* ik) {
3498 ik->clean_weak_instanceklass_links(_is_alive);
3499 }
3500
3501 void work() {
3502 ResourceMark rm;
3503
3504 // One worker will clean the subklass/sibling klass tree.
3505 if (claim_clean_klass_tree_task()) {
3506 Klass::clean_subklass_tree(_is_alive);
3507 }
3508
3509 // All workers will help cleaning the classes,
3510 InstanceKlass* klass;
3511 while ((klass = claim_next_klass()) != NULL) {
3512 clean_klass(klass);
3513 }
3514 }
3515 };
3516
3517 class G1ResolvedMethodCleaningTask : public StackObj {
3518 BoolObjectClosure* _is_alive;
3519 volatile int _resolved_method_task_claimed;
3520 public:
3521 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3522 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3523
3524 bool claim_resolved_method_task() {
3525 if (_resolved_method_task_claimed) {
3526 return false;
3527 }
3528 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3529 }
3530
3531 // These aren't big, one thread can do it all.
3532 void work() {
3533 if (claim_resolved_method_task()) {
3534 ResolvedMethodTable::unlink(_is_alive);
3535 }
3536 }
3537 };
3538
3539
3540 // To minimize the remark pause times, the tasks below are done in parallel.
3541 class G1ParallelCleaningTask : public AbstractGangTask {
3542 private:
3543 G1StringAndSymbolCleaningTask _string_symbol_task;
3544 G1CodeCacheUnloadingTask _code_cache_task;
3545 G1KlassCleaningTask _klass_cleaning_task;
3546 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3547
3548 public:
3549 // The constructor is run in the VMThread.
3550 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3551 AbstractGangTask("Parallel Cleaning"),
3552 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3553 _code_cache_task(num_workers, is_alive, unloading_occurred),
3554 _klass_cleaning_task(is_alive),
3555 _resolved_method_cleaning_task(is_alive) {
3556 }
3557
3558 // The parallel work done by all worker threads.
3559 void work(uint worker_id) {
3560 // Do first pass of code cache cleaning.
3561 _code_cache_task.work_first_pass(worker_id);
3562
3563 // Let the threads mark that the first pass is done.
3564 _code_cache_task.barrier_mark(worker_id);
3565
3566 // Clean the Strings and Symbols.
3567 _string_symbol_task.work(worker_id);
3568
3569 // Clean unreferenced things in the ResolvedMethodTable
3570 _resolved_method_cleaning_task.work();
3571
3572 // Wait for all workers to finish the first code cache cleaning pass.
3573 _code_cache_task.barrier_wait(worker_id);
3574
3575 // Do the second code cache cleaning work, which realize on
3576 // the liveness information gathered during the first pass.
3577 _code_cache_task.work_second_pass(worker_id);
3578
3579 // Clean all klasses that were not unloaded.
3580 _klass_cleaning_task.work();
3581 }
3582 };
3583
3584
3585 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3586 bool class_unloading_occurred) {
3587 uint n_workers = workers()->active_workers();
3588
3589 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3590 workers()->run_task(&g1_unlink_task);
3591 }
3592
3593 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3594 bool process_strings,
3595 bool process_symbols,
3596 bool process_string_dedup) {
3597 if (!process_strings && !process_symbols && !process_string_dedup) {
3598 // Nothing to clean.
3599 return;
3600 }
3601
3602 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3603 workers()->run_task(&g1_unlink_task);
3604
3605 }
3606
3607 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3608 private:
3609 DirtyCardQueueSet* _queue;
3610 G1CollectedHeap* _g1h;
3611 public:
3612 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3613 _queue(queue), _g1h(g1h) { }
3614
3615 virtual void work(uint worker_id) {
3616 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3617 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3618
3619 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3620 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3621
3622 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3623 }
3624 };
3625
3626 void G1CollectedHeap::redirty_logged_cards() {
3627 double redirty_logged_cards_start = os::elapsedTime();
3628
3629 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3630 dirty_card_queue_set().reset_for_par_iteration();
3631 workers()->run_task(&redirty_task);
3632
3633 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3634 dcq.merge_bufferlists(&dirty_card_queue_set());
3635 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3636
3637 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3638 }
3639
3640 // Weak Reference Processing support
3641
3642 // An always "is_alive" closure that is used to preserve referents.
3643 // If the object is non-null then it's alive. Used in the preservation
3644 // of referent objects that are pointed to by reference objects
3645 // discovered by the CM ref processor.
3646 class G1AlwaysAliveClosure: public BoolObjectClosure {
3647 G1CollectedHeap* _g1;
3648 public:
3649 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3650 bool do_object_b(oop p) {
3651 if (p != NULL) {
3652 return true;
3653 }
3654 return false;
3655 }
3656 };
3657
3658 bool G1STWIsAliveClosure::do_object_b(oop p) {
3659 // An object is reachable if it is outside the collection set,
3660 // or is inside and copied.
3661 return !_g1->is_in_cset(p) || p->is_forwarded();
3662 }
3663
3664 // Non Copying Keep Alive closure
3665 class G1KeepAliveClosure: public OopClosure {
3666 G1CollectedHeap* _g1;
3667 public:
3668 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3669 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3670 void do_oop(oop* p) {
3671 oop obj = *p;
3672 assert(obj != NULL, "the caller should have filtered out NULL values");
3673
3674 const InCSetState cset_state = _g1->in_cset_state(obj);
3675 if (!cset_state.is_in_cset_or_humongous()) {
3676 return;
3677 }
3678 if (cset_state.is_in_cset()) {
3679 assert( obj->is_forwarded(), "invariant" );
3680 *p = obj->forwardee();
3681 } else {
3682 assert(!obj->is_forwarded(), "invariant" );
3683 assert(cset_state.is_humongous(),
3684 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3685 _g1->set_humongous_is_live(obj);
3686 }
3687 }
3688 };
3689
3690 // Copying Keep Alive closure - can be called from both
3691 // serial and parallel code as long as different worker
3692 // threads utilize different G1ParScanThreadState instances
3693 // and different queues.
3694
3695 class G1CopyingKeepAliveClosure: public OopClosure {
3696 G1CollectedHeap* _g1h;
3697 OopClosure* _copy_non_heap_obj_cl;
3698 G1ParScanThreadState* _par_scan_state;
3699
3700 public:
3701 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3702 OopClosure* non_heap_obj_cl,
3703 G1ParScanThreadState* pss):
3704 _g1h(g1h),
3705 _copy_non_heap_obj_cl(non_heap_obj_cl),
3706 _par_scan_state(pss)
3707 {}
3708
3709 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3710 virtual void do_oop( oop* p) { do_oop_work(p); }
3711
3712 template <class T> void do_oop_work(T* p) {
3713 oop obj = RawAccess<>::oop_load(p);
3714
3715 if (_g1h->is_in_cset_or_humongous(obj)) {
3716 // If the referent object has been forwarded (either copied
3717 // to a new location or to itself in the event of an
3718 // evacuation failure) then we need to update the reference
3719 // field and, if both reference and referent are in the G1
3720 // heap, update the RSet for the referent.
3721 //
3722 // If the referent has not been forwarded then we have to keep
3723 // it alive by policy. Therefore we have copy the referent.
3724 //
3725 // If the reference field is in the G1 heap then we can push
3726 // on the PSS queue. When the queue is drained (after each
3727 // phase of reference processing) the object and it's followers
3728 // will be copied, the reference field set to point to the
3729 // new location, and the RSet updated. Otherwise we need to
3730 // use the the non-heap or metadata closures directly to copy
3731 // the referent object and update the pointer, while avoiding
3732 // updating the RSet.
3733
3734 if (_g1h->is_in_g1_reserved(p)) {
3735 _par_scan_state->push_on_queue(p);
3736 } else {
3737 assert(!Metaspace::contains((const void*)p),
3738 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3739 _copy_non_heap_obj_cl->do_oop(p);
3740 }
3741 }
3742 }
3743 };
3744
3745 // Serial drain queue closure. Called as the 'complete_gc'
3746 // closure for each discovered list in some of the
3747 // reference processing phases.
3748
3749 class G1STWDrainQueueClosure: public VoidClosure {
3750 protected:
3751 G1CollectedHeap* _g1h;
3752 G1ParScanThreadState* _par_scan_state;
3753
3754 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3755
3756 public:
3757 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3758 _g1h(g1h),
3759 _par_scan_state(pss)
3760 { }
3761
3762 void do_void() {
3763 G1ParScanThreadState* const pss = par_scan_state();
3764 pss->trim_queue();
3765 }
3766 };
3767
3768 // Parallel Reference Processing closures
3769
3770 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3771 // processing during G1 evacuation pauses.
3772
3773 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3774 private:
3775 G1CollectedHeap* _g1h;
3776 G1ParScanThreadStateSet* _pss;
3777 RefToScanQueueSet* _queues;
3778 WorkGang* _workers;
3779 uint _active_workers;
3780
3781 public:
3782 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3783 G1ParScanThreadStateSet* per_thread_states,
3784 WorkGang* workers,
3785 RefToScanQueueSet *task_queues,
3786 uint n_workers) :
3787 _g1h(g1h),
3788 _pss(per_thread_states),
3789 _queues(task_queues),
3790 _workers(workers),
3791 _active_workers(n_workers)
3792 {
3793 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3794 }
3795
3796 // Executes the given task using concurrent marking worker threads.
3797 virtual void execute(ProcessTask& task);
3798 virtual void execute(EnqueueTask& task);
3799 };
3800
3801 // Gang task for possibly parallel reference processing
3802
3803 class G1STWRefProcTaskProxy: public AbstractGangTask {
3804 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3805 ProcessTask& _proc_task;
3806 G1CollectedHeap* _g1h;
3807 G1ParScanThreadStateSet* _pss;
3808 RefToScanQueueSet* _task_queues;
3809 ParallelTaskTerminator* _terminator;
3810
3811 public:
3812 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3813 G1CollectedHeap* g1h,
3814 G1ParScanThreadStateSet* per_thread_states,
3815 RefToScanQueueSet *task_queues,
3816 ParallelTaskTerminator* terminator) :
3817 AbstractGangTask("Process reference objects in parallel"),
3818 _proc_task(proc_task),
3819 _g1h(g1h),
3820 _pss(per_thread_states),
3821 _task_queues(task_queues),
3822 _terminator(terminator)
3823 {}
3824
3825 virtual void work(uint worker_id) {
3826 // The reference processing task executed by a single worker.
3827 ResourceMark rm;
3828 HandleMark hm;
3829
3830 G1STWIsAliveClosure is_alive(_g1h);
3831
3832 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3833 pss->set_ref_processor(NULL);
3834
3835 // Keep alive closure.
3836 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3837
3838 // Complete GC closure
3839 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3840
3841 // Call the reference processing task's work routine.
3842 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3843
3844 // Note we cannot assert that the refs array is empty here as not all
3845 // of the processing tasks (specifically phase2 - pp2_work) execute
3846 // the complete_gc closure (which ordinarily would drain the queue) so
3847 // the queue may not be empty.
3848 }
3849 };
3850
3851 // Driver routine for parallel reference processing.
3852 // Creates an instance of the ref processing gang
3853 // task and has the worker threads execute it.
3854 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3855 assert(_workers != NULL, "Need parallel worker threads.");
3856
3857 ParallelTaskTerminator terminator(_active_workers, _queues);
3858 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3859
3860 _workers->run_task(&proc_task_proxy);
3861 }
3862
3863 // Gang task for parallel reference enqueueing.
3864
3865 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3866 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3867 EnqueueTask& _enq_task;
3868
3869 public:
3870 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3871 AbstractGangTask("Enqueue reference objects in parallel"),
3872 _enq_task(enq_task)
3873 { }
3874
3875 virtual void work(uint worker_id) {
3876 _enq_task.work(worker_id);
3877 }
3878 };
3879
3880 // Driver routine for parallel reference enqueueing.
3881 // Creates an instance of the ref enqueueing gang
3882 // task and has the worker threads execute it.
3883
3884 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
3885 assert(_workers != NULL, "Need parallel worker threads.");
3886
3887 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
3888
3889 _workers->run_task(&enq_task_proxy);
3890 }
3891
3892 // End of weak reference support closures
3893
3894 // Abstract task used to preserve (i.e. copy) any referent objects
3895 // that are in the collection set and are pointed to by reference
3896 // objects discovered by the CM ref processor.
3897
3898 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
3899 protected:
3900 G1CollectedHeap* _g1h;
3901 G1ParScanThreadStateSet* _pss;
3902 RefToScanQueueSet* _queues;
3903 ParallelTaskTerminator _terminator;
3904 uint _n_workers;
3905
3906 public:
3907 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
3908 AbstractGangTask("ParPreserveCMReferents"),
3909 _g1h(g1h),
3910 _pss(per_thread_states),
3911 _queues(task_queues),
3912 _terminator(workers, _queues),
3913 _n_workers(workers)
3914 {
3915 g1h->ref_processor_cm()->set_active_mt_degree(workers);
3916 }
3917
3918 void work(uint worker_id) {
3919 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
3920
3921 ResourceMark rm;
3922 HandleMark hm;
3923
3924 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3925 pss->set_ref_processor(NULL);
3926 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3927
3928 // Is alive closure
3929 G1AlwaysAliveClosure always_alive(_g1h);
3930
3931 // Copying keep alive closure. Applied to referent objects that need
3932 // to be copied.
3933 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3934
3935 ReferenceProcessor* rp = _g1h->ref_processor_cm();
3936
3937 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
3938 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
3939
3940 // limit is set using max_num_q() - which was set using ParallelGCThreads.
3941 // So this must be true - but assert just in case someone decides to
3942 // change the worker ids.
3943 assert(worker_id < limit, "sanity");
3944 assert(!rp->discovery_is_atomic(), "check this code");
3945
3946 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
3947 for (uint idx = worker_id; idx < limit; idx += stride) {
3948 DiscoveredList& ref_list = rp->discovered_refs()[idx];
3949
3950 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
3951 while (iter.has_next()) {
3952 // Since discovery is not atomic for the CM ref processor, we
3953 // can see some null referent objects.
3954 iter.load_ptrs(DEBUG_ONLY(true));
3955 oop ref = iter.obj();
3956
3957 // This will filter nulls.
3958 if (iter.is_referent_alive()) {
3959 iter.make_referent_alive();
3960 }
3961 iter.move_to_next();
3962 }
3963 }
3964
3965 // Drain the queue - which may cause stealing
3966 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
3967 drain_queue.do_void();
3968 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
3969 assert(pss->queue_is_empty(), "should be");
3970 }
3971 };
3972
3973 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
3974 // Any reference objects, in the collection set, that were 'discovered'
3975 // by the CM ref processor should have already been copied (either by
3976 // applying the external root copy closure to the discovered lists, or
3977 // by following an RSet entry).
3978 //
3979 // But some of the referents, that are in the collection set, that these
3980 // reference objects point to may not have been copied: the STW ref
3981 // processor would have seen that the reference object had already
3982 // been 'discovered' and would have skipped discovering the reference,
3983 // but would not have treated the reference object as a regular oop.
3984 // As a result the copy closure would not have been applied to the
3985 // referent object.
3986 //
3987 // We need to explicitly copy these referent objects - the references
3988 // will be processed at the end of remarking.
3989 //
3990 // We also need to do this copying before we process the reference
3991 // objects discovered by the STW ref processor in case one of these
3992 // referents points to another object which is also referenced by an
3993 // object discovered by the STW ref processor.
3994 double preserve_cm_referents_time = 0.0;
3995
3996 // To avoid spawning task when there is no work to do, check that
3997 // a concurrent cycle is active and that some references have been
3998 // discovered.
3999 if (concurrent_mark()->cm_thread()->during_cycle() &&
4000 ref_processor_cm()->has_discovered_references()) {
4001 double preserve_cm_referents_start = os::elapsedTime();
4002 uint no_of_gc_workers = workers()->active_workers();
4003 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4004 per_thread_states,
4005 no_of_gc_workers,
4006 _task_queues);
4007 workers()->run_task(&keep_cm_referents);
4008 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4009 }
4010
4011 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4012 }
4013
4014 // Weak Reference processing during an evacuation pause (part 1).
4015 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4016 double ref_proc_start = os::elapsedTime();
4017
4018 ReferenceProcessor* rp = _ref_processor_stw;
4019 assert(rp->discovery_enabled(), "should have been enabled");
4020
4021 // Closure to test whether a referent is alive.
4022 G1STWIsAliveClosure is_alive(this);
4023
4024 // Even when parallel reference processing is enabled, the processing
4025 // of JNI refs is serial and performed serially by the current thread
4026 // rather than by a worker. The following PSS will be used for processing
4027 // JNI refs.
4028
4029 // Use only a single queue for this PSS.
4030 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4031 pss->set_ref_processor(NULL);
4032 assert(pss->queue_is_empty(), "pre-condition");
4033
4034 // Keep alive closure.
4035 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4036
4037 // Serial Complete GC closure
4038 G1STWDrainQueueClosure drain_queue(this, pss);
4039
4040 // Setup the soft refs policy...
4041 rp->setup_policy(false);
4042
4043 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4044
4045 ReferenceProcessorStats stats;
4046 if (!rp->processing_is_mt()) {
4047 // Serial reference processing...
4048 stats = rp->process_discovered_references(&is_alive,
4049 &keep_alive,
4050 &drain_queue,
4051 NULL,
4052 pt);
4053 } else {
4054 uint no_of_gc_workers = workers()->active_workers();
4055
4056 // Parallel reference processing
4057 assert(no_of_gc_workers <= rp->max_num_q(),
4058 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4059 no_of_gc_workers, rp->max_num_q());
4060
4061 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4062 stats = rp->process_discovered_references(&is_alive,
4063 &keep_alive,
4064 &drain_queue,
4065 &par_task_executor,
4066 pt);
4067 }
4068
4069 _gc_tracer_stw->report_gc_reference_stats(stats);
4070
4071 // We have completed copying any necessary live referent objects.
4072 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4073
4074 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4075 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4076 }
4077
4078 // Weak Reference processing during an evacuation pause (part 2).
4079 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4080 double ref_enq_start = os::elapsedTime();
4081
4082 ReferenceProcessor* rp = _ref_processor_stw;
4083 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4084
4085 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4086
4087 // Now enqueue any remaining on the discovered lists on to
4088 // the pending list.
4089 if (!rp->processing_is_mt()) {
4090 // Serial reference processing...
4091 rp->enqueue_discovered_references(NULL, pt);
4092 } else {
4093 // Parallel reference enqueueing
4094
4095 uint n_workers = workers()->active_workers();
4096
4097 assert(n_workers <= rp->max_num_q(),
4098 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4099 n_workers, rp->max_num_q());
4100
4101 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4102 rp->enqueue_discovered_references(&par_task_executor, pt);
4103 }
4104
4105 rp->verify_no_references_recorded();
4106 assert(!rp->discovery_enabled(), "should have been disabled");
4107
4108 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4109 // ensure that it is marked in the bitmap for concurrent marking to discover.
4110 if (collector_state()->in_initial_mark_gc()) {
4111 oop pll_head = Universe::reference_pending_list();
4112 if (pll_head != NULL) {
4113 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
4114 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
4115 }
4116 }
4117
4118 // FIXME
4119 // CM's reference processing also cleans up the string and symbol tables.
4120 // Should we do that here also? We could, but it is a serial operation
4121 // and could significantly increase the pause time.
4122
4123 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4124 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4125 }
4126
4127 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4128 double merge_pss_time_start = os::elapsedTime();
4129 per_thread_states->flush();
4130 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4131 }
4132
4133 void G1CollectedHeap::pre_evacuate_collection_set() {
4134 _expand_heap_after_alloc_failure = true;
4135 _evacuation_failed = false;
4136
4137 // Disable the hot card cache.
4138 _hot_card_cache->reset_hot_cache_claimed_index();
4139 _hot_card_cache->set_use_cache(false);
4140
4141 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4142 _preserved_marks_set.assert_empty();
4143
4144 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4145
4146 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4147 if (collector_state()->in_initial_mark_gc()) {
4148 double start_clear_claimed_marks = os::elapsedTime();
4149
4150 ClassLoaderDataGraph::clear_claimed_marks();
4151
4152 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4153 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4154 }
4155 }
4156
4157 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
4158 // Should G1EvacuationFailureALot be in effect for this GC?
4159 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4160
4161 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4162
4163 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4164
4165 double start_par_time_sec = os::elapsedTime();
4166 double end_par_time_sec;
4167
4168 {
4169 const uint n_workers = workers()->active_workers();
4170 G1RootProcessor root_processor(this, n_workers);
4171 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4172
4173 print_termination_stats_hdr();
4174
4175 workers()->run_task(&g1_par_task);
4176 end_par_time_sec = os::elapsedTime();
4177
4178 // Closing the inner scope will execute the destructor
4179 // for the G1RootProcessor object. We record the current
4180 // elapsed time before closing the scope so that time
4181 // taken for the destructor is NOT included in the
4182 // reported parallel time.
4183 }
4184
4185 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4186 phase_times->record_par_time(par_time_ms);
4187
4188 double code_root_fixup_time_ms =
4189 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4190 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4191 }
4192
4193 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4194 // Process any discovered reference objects - we have
4195 // to do this _before_ we retire the GC alloc regions
4196 // as we may have to copy some 'reachable' referent
4197 // objects (and their reachable sub-graphs) that were
4198 // not copied during the pause.
4199 preserve_cm_referents(per_thread_states);
4200 process_discovered_references(per_thread_states);
4201
4202 G1STWIsAliveClosure is_alive(this);
4203 G1KeepAliveClosure keep_alive(this);
4204
4205 {
4206 double start = os::elapsedTime();
4207
4208 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4209
4210 double time_ms = (os::elapsedTime() - start) * 1000.0;
4211 g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4212 }
4213
4214 if (G1StringDedup::is_enabled()) {
4215 double fixup_start = os::elapsedTime();
4216
4217 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4218
4219 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4220 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4221 }
4222
4223 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4224
4225 if (evacuation_failed()) {
4226 restore_after_evac_failure();
4227
4228 // Reset the G1EvacuationFailureALot counters and flags
4229 // Note: the values are reset only when an actual
4230 // evacuation failure occurs.
4231 NOT_PRODUCT(reset_evacuation_should_fail();)
4232 }
4233
4234 _preserved_marks_set.assert_empty();
4235
4236 // Enqueue any remaining references remaining on the STW
4237 // reference processor's discovered lists. We need to do
4238 // this after the card table is cleaned (and verified) as
4239 // the act of enqueueing entries on to the pending list
4240 // will log these updates (and dirty their associated
4241 // cards). We need these updates logged to update any
4242 // RSets.
4243 enqueue_discovered_references(per_thread_states);
4244
4245 _allocator->release_gc_alloc_regions(evacuation_info);
4246
4247 merge_per_thread_state_info(per_thread_states);
4248
4249 // Reset and re-enable the hot card cache.
4250 // Note the counts for the cards in the regions in the
4251 // collection set are reset when the collection set is freed.
4252 _hot_card_cache->reset_hot_cache();
4253 _hot_card_cache->set_use_cache(true);
4254
4255 purge_code_root_memory();
4256
4257 redirty_logged_cards();
4258 #if COMPILER2_OR_JVMCI
4259 double start = os::elapsedTime();
4260 DerivedPointerTable::update_pointers();
4261 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4262 #endif
4263 g1_policy()->print_age_table();
4264 }
4265
4266 void G1CollectedHeap::record_obj_copy_mem_stats() {
4267 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4268
4269 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4270 create_g1_evac_summary(&_old_evac_stats));
4271 }
4272
4273 void G1CollectedHeap::free_region(HeapRegion* hr,
4274 FreeRegionList* free_list,
4275 bool skip_remset,
4276 bool skip_hot_card_cache,
4277 bool locked) {
4278 assert(!hr->is_free(), "the region should not be free");
4279 assert(!hr->is_empty(), "the region should not be empty");
4280 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4281 assert(free_list != NULL, "pre-condition");
4282
4283 if (G1VerifyBitmaps) {
4284 MemRegion mr(hr->bottom(), hr->end());
4285 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4286 }
4287
4288 // Clear the card counts for this region.
4289 // Note: we only need to do this if the region is not young
4290 // (since we don't refine cards in young regions).
4291 if (!skip_hot_card_cache && !hr->is_young()) {
4292 _hot_card_cache->reset_card_counts(hr);
4293 }
4294 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4295 _g1_policy->remset_tracker()->update_at_free(hr);
4296 free_list->add_ordered(hr);
4297 }
4298
4299 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4300 FreeRegionList* free_list) {
4301 assert(hr->is_humongous(), "this is only for humongous regions");
4302 assert(free_list != NULL, "pre-condition");
4303 hr->clear_humongous();
4304 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4305 }
4306
4307 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4308 const uint humongous_regions_removed) {
4309 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4310 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4311 _old_set.bulk_remove(old_regions_removed);
4312 _humongous_set.bulk_remove(humongous_regions_removed);
4313 }
4314
4315 }
4316
4317 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4318 assert(list != NULL, "list can't be null");
4319 if (!list->is_empty()) {
4320 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4321 _hrm.insert_list_into_free_list(list);
4322 }
4323 }
4324
4325 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4326 decrease_used(bytes);
4327 }
4328
4329 class G1FreeCollectionSetTask : public AbstractGangTask {
4330 private:
4331
4332 // Closure applied to all regions in the collection set to do work that needs to
4333 // be done serially in a single thread.
4334 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4335 private:
4336 EvacuationInfo* _evacuation_info;
4337 const size_t* _surviving_young_words;
4338
4339 // Bytes used in successfully evacuated regions before the evacuation.
4340 size_t _before_used_bytes;
4341 // Bytes used in unsucessfully evacuated regions before the evacuation
4342 size_t _after_used_bytes;
4343
4344 size_t _bytes_allocated_in_old_since_last_gc;
4345
4346 size_t _failure_used_words;
4347 size_t _failure_waste_words;
4348
4349 FreeRegionList _local_free_list;
4350 public:
4351 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4352 HeapRegionClosure(),
4353 _evacuation_info(evacuation_info),
4354 _surviving_young_words(surviving_young_words),
4355 _before_used_bytes(0),
4356 _after_used_bytes(0),
4357 _bytes_allocated_in_old_since_last_gc(0),
4358 _failure_used_words(0),
4359 _failure_waste_words(0),
4360 _local_free_list("Local Region List for CSet Freeing") {
4361 }
4362
4363 virtual bool do_heap_region(HeapRegion* r) {
4364 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4365
4366 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4367 g1h->clear_in_cset(r);
4368
4369 if (r->is_young()) {
4370 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4371 "Young index %d is wrong for region %u of type %s with %u young regions",
4372 r->young_index_in_cset(),
4373 r->hrm_index(),
4374 r->get_type_str(),
4375 g1h->collection_set()->young_region_length());
4376 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4377 r->record_surv_words_in_group(words_survived);
4378 }
4379
4380 if (!r->evacuation_failed()) {
4381 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4382 _before_used_bytes += r->used();
4383 g1h->free_region(r,
4384 &_local_free_list,
4385 true, /* skip_remset */
4386 true, /* skip_hot_card_cache */
4387 true /* locked */);
4388 } else {
4389 r->uninstall_surv_rate_group();
4390 r->set_young_index_in_cset(-1);
4391 r->set_evacuation_failed(false);
4392 // When moving a young gen region to old gen, we "allocate" that whole region
4393 // there. This is in addition to any already evacuated objects. Notify the
4394 // policy about that.
4395 // Old gen regions do not cause an additional allocation: both the objects
4396 // still in the region and the ones already moved are accounted for elsewhere.
4397 if (r->is_young()) {
4398 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4399 }
4400 // The region is now considered to be old.
4401 r->set_old();
4402 // Do some allocation statistics accounting. Regions that failed evacuation
4403 // are always made old, so there is no need to update anything in the young
4404 // gen statistics, but we need to update old gen statistics.
4405 size_t used_words = r->marked_bytes() / HeapWordSize;
4406
4407 _failure_used_words += used_words;
4408 _failure_waste_words += HeapRegion::GrainWords - used_words;
4409
4410 g1h->old_set_add(r);
4411 _after_used_bytes += r->used();
4412 }
4413 return false;
4414 }
4415
4416 void complete_work() {
4417 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4418
4419 _evacuation_info->set_regions_freed(_local_free_list.length());
4420 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4421
4422 g1h->prepend_to_freelist(&_local_free_list);
4423 g1h->decrement_summary_bytes(_before_used_bytes);
4424
4425 G1Policy* policy = g1h->g1_policy();
4426 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4427
4428 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4429 }
4430 };
4431
4432 G1CollectionSet* _collection_set;
4433 G1SerialFreeCollectionSetClosure _cl;
4434 const size_t* _surviving_young_words;
4435
4436 size_t _rs_lengths;
4437
4438 volatile jint _serial_work_claim;
4439
4440 struct WorkItem {
4441 uint region_idx;
4442 bool is_young;
4443 bool evacuation_failed;
4444
4445 WorkItem(HeapRegion* r) {
4446 region_idx = r->hrm_index();
4447 is_young = r->is_young();
4448 evacuation_failed = r->evacuation_failed();
4449 }
4450 };
4451
4452 volatile size_t _parallel_work_claim;
4453 size_t _num_work_items;
4454 WorkItem* _work_items;
4455
4456 void do_serial_work() {
4457 // Need to grab the lock to be allowed to modify the old region list.
4458 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4459 _collection_set->iterate(&_cl);
4460 }
4461
4462 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4463 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4464
4465 HeapRegion* r = g1h->region_at(region_idx);
4466 assert(!g1h->is_on_master_free_list(r), "sanity");
4467
4468 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4469
4470 if (!is_young) {
4471 g1h->_hot_card_cache->reset_card_counts(r);
4472 }
4473
4474 if (!evacuation_failed) {
4475 r->rem_set()->clear_locked();
4476 }
4477 }
4478
4479 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4480 private:
4481 size_t _cur_idx;
4482 WorkItem* _work_items;
4483 public:
4484 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4485
4486 virtual bool do_heap_region(HeapRegion* r) {
4487 _work_items[_cur_idx++] = WorkItem(r);
4488 return false;
4489 }
4490 };
4491
4492 void prepare_work() {
4493 G1PrepareFreeCollectionSetClosure cl(_work_items);
4494 _collection_set->iterate(&cl);
4495 }
4496
4497 void complete_work() {
4498 _cl.complete_work();
4499
4500 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4501 policy->record_max_rs_lengths(_rs_lengths);
4502 policy->cset_regions_freed();
4503 }
4504 public:
4505 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4506 AbstractGangTask("G1 Free Collection Set"),
4507 _cl(evacuation_info, surviving_young_words),
4508 _collection_set(collection_set),
4509 _surviving_young_words(surviving_young_words),
4510 _serial_work_claim(0),
4511 _rs_lengths(0),
4512 _parallel_work_claim(0),
4513 _num_work_items(collection_set->region_length()),
4514 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4515 prepare_work();
4516 }
4517
4518 ~G1FreeCollectionSetTask() {
4519 complete_work();
4520 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4521 }
4522
4523 // Chunk size for work distribution. The chosen value has been determined experimentally
4524 // to be a good tradeoff between overhead and achievable parallelism.
4525 static uint chunk_size() { return 32; }
4526
4527 virtual void work(uint worker_id) {
4528 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4529
4530 // Claim serial work.
4531 if (_serial_work_claim == 0) {
4532 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4533 if (value == 0) {
4534 double serial_time = os::elapsedTime();
4535 do_serial_work();
4536 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4537 }
4538 }
4539
4540 // Start parallel work.
4541 double young_time = 0.0;
4542 bool has_young_time = false;
4543 double non_young_time = 0.0;
4544 bool has_non_young_time = false;
4545
4546 while (true) {
4547 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4548 size_t cur = end - chunk_size();
4549
4550 if (cur >= _num_work_items) {
4551 break;
4552 }
4553
4554 double start_time = os::elapsedTime();
4555
4556 end = MIN2(end, _num_work_items);
4557
4558 for (; cur < end; cur++) {
4559 bool is_young = _work_items[cur].is_young;
4560
4561 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4562
4563 double end_time = os::elapsedTime();
4564 double time_taken = end_time - start_time;
4565 if (is_young) {
4566 young_time += time_taken;
4567 has_young_time = true;
4568 } else {
4569 non_young_time += time_taken;
4570 has_non_young_time = true;
4571 }
4572 start_time = end_time;
4573 }
4574 }
4575
4576 if (has_young_time) {
4577 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4578 }
4579 if (has_non_young_time) {
4580 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4581 }
4582 }
4583 };
4584
4585 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4586 _eden.clear();
4587
4588 double free_cset_start_time = os::elapsedTime();
4589
4590 {
4591 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4592 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4593
4594 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4595
4596 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4597 cl.name(),
4598 num_workers,
4599 _collection_set.region_length());
4600 workers()->run_task(&cl, num_workers);
4601 }
4602 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4603
4604 collection_set->clear();
4605 }
4606
4607 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4608 private:
4609 FreeRegionList* _free_region_list;
4610 HeapRegionSet* _proxy_set;
4611 uint _humongous_objects_reclaimed;
4612 uint _humongous_regions_reclaimed;
4613 size_t _freed_bytes;
4614 public:
4615
4616 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4617 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4618 }
4619
4620 virtual bool do_heap_region(HeapRegion* r) {
4621 if (!r->is_starts_humongous()) {
4622 return false;
4623 }
4624
4625 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4626
4627 oop obj = (oop)r->bottom();
4628 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4629
4630 // The following checks whether the humongous object is live are sufficient.
4631 // The main additional check (in addition to having a reference from the roots
4632 // or the young gen) is whether the humongous object has a remembered set entry.
4633 //
4634 // A humongous object cannot be live if there is no remembered set for it
4635 // because:
4636 // - there can be no references from within humongous starts regions referencing
4637 // the object because we never allocate other objects into them.
4638 // (I.e. there are no intra-region references that may be missed by the
4639 // remembered set)
4640 // - as soon there is a remembered set entry to the humongous starts region
4641 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4642 // until the end of a concurrent mark.
4643 //
4644 // It is not required to check whether the object has been found dead by marking
4645 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4646 // all objects allocated during that time are considered live.
4647 // SATB marking is even more conservative than the remembered set.
4648 // So if at this point in the collection there is no remembered set entry,
4649 // nobody has a reference to it.
4650 // At the start of collection we flush all refinement logs, and remembered sets
4651 // are completely up-to-date wrt to references to the humongous object.
4652 //
4653 // Other implementation considerations:
4654 // - never consider object arrays at this time because they would pose
4655 // considerable effort for cleaning up the the remembered sets. This is
4656 // required because stale remembered sets might reference locations that
4657 // are currently allocated into.
4658 uint region_idx = r->hrm_index();
4659 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4660 !r->rem_set()->is_empty()) {
4661 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",
4662 region_idx,
4663 (size_t)obj->size() * HeapWordSize,
4664 p2i(r->bottom()),
4665 r->rem_set()->occupied(),
4666 r->rem_set()->strong_code_roots_list_length(),
4667 next_bitmap->is_marked(r->bottom()),
4668 g1h->is_humongous_reclaim_candidate(region_idx),
4669 obj->is_typeArray()
4670 );
4671 return false;
4672 }
4673
4674 guarantee(obj->is_typeArray(),
4675 "Only eagerly reclaiming type arrays is supported, but the object "
4676 PTR_FORMAT " is not.", p2i(r->bottom()));
4677
4678 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",
4679 region_idx,
4680 (size_t)obj->size() * HeapWordSize,
4681 p2i(r->bottom()),
4682 r->rem_set()->occupied(),
4683 r->rem_set()->strong_code_roots_list_length(),
4684 next_bitmap->is_marked(r->bottom()),
4685 g1h->is_humongous_reclaim_candidate(region_idx),
4686 obj->is_typeArray()
4687 );
4688
4689 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4690 cm->humongous_object_eagerly_reclaimed(r);
4691 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4692 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4693 region_idx,
4694 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4695 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4696 _humongous_objects_reclaimed++;
4697 do {
4698 HeapRegion* next = g1h->next_region_in_humongous(r);
4699 _freed_bytes += r->used();
4700 r->set_containing_set(NULL);
4701 _humongous_regions_reclaimed++;
4702 g1h->free_humongous_region(r, _free_region_list);
4703 r = next;
4704 } while (r != NULL);
4705
4706 return false;
4707 }
4708
4709 uint humongous_objects_reclaimed() {
4710 return _humongous_objects_reclaimed;
4711 }
4712
4713 uint humongous_regions_reclaimed() {
4714 return _humongous_regions_reclaimed;
4715 }
4716
4717 size_t bytes_freed() const {
4718 return _freed_bytes;
4719 }
4720 };
4721
4722 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4723 assert_at_safepoint_on_vm_thread();
4724
4725 if (!G1EagerReclaimHumongousObjects ||
4726 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4727 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4728 return;
4729 }
4730
4731 double start_time = os::elapsedTime();
4732
4733 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4734
4735 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4736 heap_region_iterate(&cl);
4737
4738 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4739
4740 G1HRPrinter* hrp = hr_printer();
4741 if (hrp->is_active()) {
4742 FreeRegionListIterator iter(&local_cleanup_list);
4743 while (iter.more_available()) {
4744 HeapRegion* hr = iter.get_next();
4745 hrp->cleanup(hr);
4746 }
4747 }
4748
4749 prepend_to_freelist(&local_cleanup_list);
4750 decrement_summary_bytes(cl.bytes_freed());
4751
4752 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4753 cl.humongous_objects_reclaimed());
4754 }
4755
4756 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4757 public:
4758 virtual bool do_heap_region(HeapRegion* r) {
4759 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4760 G1CollectedHeap::heap()->clear_in_cset(r);
4761 r->set_young_index_in_cset(-1);
4762 return false;
4763 }
4764 };
4765
4766 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4767 G1AbandonCollectionSetClosure cl;
4768 collection_set->iterate(&cl);
4769
4770 collection_set->clear();
4771 collection_set->stop_incremental_building();
4772 }
4773
4774 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4775 return _allocator->is_retained_old_region(hr);
4776 }
4777
4778 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4779 _eden.add(hr);
4780 _g1_policy->set_region_eden(hr);
4781 }
4782
4783 #ifdef ASSERT
4784
4785 class NoYoungRegionsClosure: public HeapRegionClosure {
4786 private:
4787 bool _success;
4788 public:
4789 NoYoungRegionsClosure() : _success(true) { }
4790 bool do_heap_region(HeapRegion* r) {
4791 if (r->is_young()) {
4792 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4793 p2i(r->bottom()), p2i(r->end()));
4794 _success = false;
4795 }
4796 return false;
4797 }
4798 bool success() { return _success; }
4799 };
4800
4801 bool G1CollectedHeap::check_young_list_empty() {
4802 bool ret = (young_regions_count() == 0);
4803
4804 NoYoungRegionsClosure closure;
4805 heap_region_iterate(&closure);
4806 ret = ret && closure.success();
4807
4808 return ret;
4809 }
4810
4811 #endif // ASSERT
4812
4813 class TearDownRegionSetsClosure : public HeapRegionClosure {
4814 private:
4815 HeapRegionSet *_old_set;
4816
4817 public:
4818 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4819
4820 bool do_heap_region(HeapRegion* r) {
4821 if (r->is_old()) {
4822 _old_set->remove(r);
4823 } else if(r->is_young()) {
4824 r->uninstall_surv_rate_group();
4825 } else {
4826 // We ignore free regions, we'll empty the free list afterwards.
4827 // We ignore humongous regions, we're not tearing down the
4828 // humongous regions set.
4829 assert(r->is_free() || r->is_humongous(),
4830 "it cannot be another type");
4831 }
4832 return false;
4833 }
4834
4835 ~TearDownRegionSetsClosure() {
4836 assert(_old_set->is_empty(), "post-condition");
4837 }
4838 };
4839
4840 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4841 assert_at_safepoint_on_vm_thread();
4842
4843 if (!free_list_only) {
4844 TearDownRegionSetsClosure cl(&_old_set);
4845 heap_region_iterate(&cl);
4846
4847 // Note that emptying the _young_list is postponed and instead done as
4848 // the first step when rebuilding the regions sets again. The reason for
4849 // this is that during a full GC string deduplication needs to know if
4850 // a collected region was young or old when the full GC was initiated.
4851 }
4852 _hrm.remove_all_free_regions();
4853 }
4854
4855 void G1CollectedHeap::increase_used(size_t bytes) {
4856 _summary_bytes_used += bytes;
4857 }
4858
4859 void G1CollectedHeap::decrease_used(size_t bytes) {
4860 assert(_summary_bytes_used >= bytes,
4861 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4862 _summary_bytes_used, bytes);
4863 _summary_bytes_used -= bytes;
4864 }
4865
4866 void G1CollectedHeap::set_used(size_t bytes) {
4867 _summary_bytes_used = bytes;
4868 }
4869
4870 class RebuildRegionSetsClosure : public HeapRegionClosure {
4871 private:
4872 bool _free_list_only;
4873 HeapRegionSet* _old_set;
4874 HeapRegionManager* _hrm;
4875 size_t _total_used;
4876
4877 public:
4878 RebuildRegionSetsClosure(bool free_list_only,
4879 HeapRegionSet* old_set, HeapRegionManager* hrm) :
4880 _free_list_only(free_list_only),
4881 _old_set(old_set), _hrm(hrm), _total_used(0) {
4882 assert(_hrm->num_free_regions() == 0, "pre-condition");
4883 if (!free_list_only) {
4884 assert(_old_set->is_empty(), "pre-condition");
4885 }
4886 }
4887
4888 bool do_heap_region(HeapRegion* r) {
4889 // After full GC, no region should have a remembered set.
4890 r->rem_set()->clear(true);
4891 if (r->is_empty()) {
4892 // Add free regions to the free list
4893 r->set_free();
4894 _hrm->insert_into_free_list(r);
4895 } else if (!_free_list_only) {
4896
4897 if (r->is_humongous()) {
4898 // We ignore humongous regions. We left the humongous set unchanged.
4899 } else {
4900 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4901 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
4902 r->move_to_old();
4903 _old_set->add(r);
4904 }
4905 _total_used += r->used();
4906 }
4907
4908 return false;
4909 }
4910
4911 size_t total_used() {
4912 return _total_used;
4913 }
4914 };
4915
4916 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4917 assert_at_safepoint_on_vm_thread();
4918
4919 if (!free_list_only) {
4920 _eden.clear();
4921 _survivor.clear();
4922 }
4923
4924 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4925 heap_region_iterate(&cl);
4926
4927 if (!free_list_only) {
4928 set_used(cl.total_used());
4929 if (_archive_allocator != NULL) {
4930 _archive_allocator->clear_used();
4931 }
4932 }
4933 assert(used_unlocked() == recalculate_used(),
4934 "inconsistent used_unlocked(), "
4935 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4936 used_unlocked(), recalculate_used());
4937 }
4938
4939 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4940 HeapRegion* hr = heap_region_containing(p);
4941 return hr->is_in(p);
4942 }
4943
4944 // Methods for the mutator alloc region
4945
4946 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4947 bool force) {
4948 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4949 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4950 if (force || should_allocate) {
4951 HeapRegion* new_alloc_region = new_region(word_size,
4952 false /* is_old */,
4953 false /* do_expand */);
4954 if (new_alloc_region != NULL) {
4955 set_region_short_lived_locked(new_alloc_region);
4956 _hr_printer.alloc(new_alloc_region, !should_allocate);
4957 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4958 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4959 return new_alloc_region;
4960 }
4961 }
4962 return NULL;
4963 }
4964
4965 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4966 size_t allocated_bytes) {
4967 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4968 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4969
4970 collection_set()->add_eden_region(alloc_region);
4971 increase_used(allocated_bytes);
4972 _hr_printer.retire(alloc_region);
4973 // We update the eden sizes here, when the region is retired,
4974 // instead of when it's allocated, since this is the point that its
4975 // used space has been recored in _summary_bytes_used.
4976 g1mm()->update_eden_size();
4977 }
4978
4979 // Methods for the GC alloc regions
4980
4981 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4982 if (dest.is_old()) {
4983 return true;
4984 } else {
4985 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4986 }
4987 }
4988
4989 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4990 assert(FreeList_lock->owned_by_self(), "pre-condition");
4991
4992 if (!has_more_regions(dest)) {
4993 return NULL;
4994 }
4995
4996 const bool is_survivor = dest.is_young();
4997
4998 HeapRegion* new_alloc_region = new_region(word_size,
4999 !is_survivor,
5000 true /* do_expand */);
5001 if (new_alloc_region != NULL) {
5002 if (is_survivor) {
5003 new_alloc_region->set_survivor();
5004 _survivor.add(new_alloc_region);
5005 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5006 } else {
5007 new_alloc_region->set_old();
5008 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5009 }
5010 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
5011 _hr_printer.alloc(new_alloc_region);
5012 bool during_im = collector_state()->in_initial_mark_gc();
5013 new_alloc_region->note_start_of_copying(during_im);
5014 return new_alloc_region;
5015 }
5016 return NULL;
5017 }
5018
5019 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5020 size_t allocated_bytes,
5021 InCSetState dest) {
5022 bool during_im = collector_state()->in_initial_mark_gc();
5023 alloc_region->note_end_of_copying(during_im);
5024 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5025 if (dest.is_old()) {
5026 _old_set.add(alloc_region);
5027 }
5028 _hr_printer.retire(alloc_region);
5029 }
5030
5031 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5032 bool expanded = false;
5033 uint index = _hrm.find_highest_free(&expanded);
5034
5035 if (index != G1_NO_HRM_INDEX) {
5036 if (expanded) {
5037 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5038 HeapRegion::GrainWords * HeapWordSize);
5039 }
5040 _hrm.allocate_free_regions_starting_at(index, 1);
5041 return region_at(index);
5042 }
5043 return NULL;
5044 }
5045
5046 // Optimized nmethod scanning
5047
5048 class RegisterNMethodOopClosure: public OopClosure {
5049 G1CollectedHeap* _g1h;
5050 nmethod* _nm;
5051
5052 template <class T> void do_oop_work(T* p) {
5053 T heap_oop = RawAccess<>::oop_load(p);
5054 if (!CompressedOops::is_null(heap_oop)) {
5055 oop obj = CompressedOops::decode_not_null(heap_oop);
5056 HeapRegion* hr = _g1h->heap_region_containing(obj);
5057 assert(!hr->is_continues_humongous(),
5058 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5059 " starting at " HR_FORMAT,
5060 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5061
5062 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5063 hr->add_strong_code_root_locked(_nm);
5064 }
5065 }
5066
5067 public:
5068 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5069 _g1h(g1h), _nm(nm) {}
5070
5071 void do_oop(oop* p) { do_oop_work(p); }
5072 void do_oop(narrowOop* p) { do_oop_work(p); }
5073 };
5074
5075 class UnregisterNMethodOopClosure: public OopClosure {
5076 G1CollectedHeap* _g1h;
5077 nmethod* _nm;
5078
5079 template <class T> void do_oop_work(T* p) {
5080 T heap_oop = RawAccess<>::oop_load(p);
5081 if (!CompressedOops::is_null(heap_oop)) {
5082 oop obj = CompressedOops::decode_not_null(heap_oop);
5083 HeapRegion* hr = _g1h->heap_region_containing(obj);
5084 assert(!hr->is_continues_humongous(),
5085 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5086 " starting at " HR_FORMAT,
5087 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5088
5089 hr->remove_strong_code_root(_nm);
5090 }
5091 }
5092
5093 public:
5094 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5095 _g1h(g1h), _nm(nm) {}
5096
5097 void do_oop(oop* p) { do_oop_work(p); }
5098 void do_oop(narrowOop* p) { do_oop_work(p); }
5099 };
5100
5101 // Returns true if the reference points to an object that
5102 // can move in an incremental collection.
5103 bool G1CollectedHeap::is_scavengable(oop obj) {
5104 HeapRegion* hr = heap_region_containing(obj);
5105 return !hr->is_pinned();
5106 }
5107
5108 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5109 guarantee(nm != NULL, "sanity");
5110 RegisterNMethodOopClosure reg_cl(this, nm);
5111 nm->oops_do(®_cl);
5112 }
5113
5114 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5115 guarantee(nm != NULL, "sanity");
5116 UnregisterNMethodOopClosure reg_cl(this, nm);
5117 nm->oops_do(®_cl, true);
5118 }
5119
5120 void G1CollectedHeap::purge_code_root_memory() {
5121 double purge_start = os::elapsedTime();
5122 G1CodeRootSet::purge();
5123 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5124 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5125 }
5126
5127 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5128 G1CollectedHeap* _g1h;
5129
5130 public:
5131 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5132 _g1h(g1h) {}
5133
5134 void do_code_blob(CodeBlob* cb) {
5135 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5136 if (nm == NULL) {
5137 return;
5138 }
5139
5140 if (ScavengeRootsInCode) {
5141 _g1h->register_nmethod(nm);
5142 }
5143 }
5144 };
5145
5146 void G1CollectedHeap::rebuild_strong_code_roots() {
5147 RebuildStrongCodeRootClosure blob_cl(this);
5148 CodeCache::blobs_do(&blob_cl);
5149 }
5150
5151 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5152 GrowableArray<GCMemoryManager*> memory_managers(2);
5153 memory_managers.append(&_memory_manager);
5154 memory_managers.append(&_full_gc_memory_manager);
5155 return memory_managers;
5156 }
5157
5158 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5159 GrowableArray<MemoryPool*> memory_pools(3);
5160 memory_pools.append(_eden_pool);
5161 memory_pools.append(_survivor_pool);
5162 memory_pools.append(_old_pool);
5163 return memory_pools;
5164 }