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/concurrentMarkThread.inline.hpp"
33 #include "gc/g1/g1Allocator.inline.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/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1MemoryPool.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1StringDedup.hpp"
56 #include "gc/g1/g1YCTypes.hpp"
57 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
58 #include "gc/g1/heapRegion.inline.hpp"
59 #include "gc/g1/heapRegionRemSet.hpp"
60 #include "gc/g1/heapRegionSet.inline.hpp"
61 #include "gc/g1/vm_operations_g1.hpp"
62 #include "gc/shared/adaptiveSizePolicy.hpp"
63 #include "gc/shared/gcHeapSummary.hpp"
64 #include "gc/shared/gcId.hpp"
65 #include "gc/shared/gcLocker.hpp"
66 #include "gc/shared/gcTimer.hpp"
67 #include "gc/shared/gcTrace.hpp"
68 #include "gc/shared/gcTraceTime.inline.hpp"
69 #include "gc/shared/generationSpec.hpp"
70 #include "gc/shared/isGCActiveMark.hpp"
71 #include "gc/shared/preservedMarks.inline.hpp"
72 #include "gc/shared/suspendibleThreadSet.hpp"
73 #include "gc/shared/referenceProcessor.inline.hpp"
74 #include "gc/shared/taskqueue.inline.hpp"
75 #include "gc/shared/weakProcessor.hpp"
76 #include "logging/log.hpp"
77 #include "memory/allocation.hpp"
78 #include "memory/iterator.hpp"
79 #include "memory/resourceArea.hpp"
80 #include "oops/access.inline.hpp"
81 #include "oops/compressedOops.inline.hpp"
82 #include "oops/oop.inline.hpp"
83 #include "prims/resolvedMethodTable.hpp"
84 #include "runtime/atomic.hpp"
85 #include "runtime/handles.inline.hpp"
86 #include "runtime/init.hpp"
87 #include "runtime/orderAccess.inline.hpp"
88 #include "runtime/threadSMR.hpp"
89 #include "runtime/vmThread.hpp"
90 #include "utilities/align.hpp"
91 #include "utilities/globalDefinitions.hpp"
92 #include "utilities/stack.inline.hpp"
93
94 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
95
96 // INVARIANTS/NOTES
97 //
98 // All allocation activity covered by the G1CollectedHeap interface is
99 // serialized by acquiring the HeapLock. This happens in mem_allocate
100 // and allocate_new_tlab, which are the "entry" points to the
101 // allocation code from the rest of the JVM. (Note that this does not
102 // apply to TLAB allocation, which is not part of this interface: it
103 // is done by clients of this interface.)
104
105 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
106 private:
107 size_t _num_dirtied;
108 G1CollectedHeap* _g1h;
109 G1CardTable* _g1_ct;
110
111 HeapRegion* region_for_card(jbyte* card_ptr) const {
112 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
113 }
114
115 bool will_become_free(HeapRegion* hr) const {
116 // A region will be freed by free_collection_set if the region is in the
117 // collection set and has not had an evacuation failure.
118 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
119 }
120
121 public:
122 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
123 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
124
125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
126 HeapRegion* hr = region_for_card(card_ptr);
127
128 // Should only dirty cards in regions that won't be freed.
129 if (!will_become_free(hr)) {
130 *card_ptr = G1CardTable::dirty_card_val();
131 _num_dirtied++;
132 }
133
134 return true;
135 }
136
137 size_t num_dirtied() const { return _num_dirtied; }
138 };
139
140
141 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
142 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
143 }
144
145 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
146 // The from card cache is not the memory that is actually committed. So we cannot
147 // take advantage of the zero_filled parameter.
148 reset_from_card_cache(start_idx, num_regions);
149 }
150
151
152 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
153 MemRegion mr) {
154 return new HeapRegion(hrs_index, bot(), mr);
155 }
156
157 // Private methods.
158
159 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
160 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
161 "the only time we use this to allocate a humongous region is "
162 "when we are allocating a single humongous region");
163
164 HeapRegion* res = _hrm.allocate_free_region(is_old);
165
166 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
167 // Currently, only attempts to allocate GC alloc regions set
168 // do_expand to true. So, we should only reach here during a
169 // safepoint. If this assumption changes we might have to
170 // reconsider the use of _expand_heap_after_alloc_failure.
171 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
172
173 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
174 word_size * HeapWordSize);
175
176 if (expand(word_size * HeapWordSize)) {
177 // Given that expand() succeeded in expanding the heap, and we
178 // always expand the heap by an amount aligned to the heap
179 // region size, the free list should in theory not be empty.
180 // In either case allocate_free_region() will check for NULL.
181 res = _hrm.allocate_free_region(is_old);
182 } else {
183 _expand_heap_after_alloc_failure = false;
184 }
185 }
186 return res;
187 }
188
189 HeapWord*
190 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
191 uint num_regions,
192 size_t word_size) {
193 assert(first != G1_NO_HRM_INDEX, "pre-condition");
194 assert(is_humongous(word_size), "word_size should be humongous");
195 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
196
197 // Index of last region in the series.
198 uint last = first + num_regions - 1;
199
200 // We need to initialize the region(s) we just discovered. This is
201 // a bit tricky given that it can happen concurrently with
202 // refinement threads refining cards on these regions and
203 // potentially wanting to refine the BOT as they are scanning
204 // those cards (this can happen shortly after a cleanup; see CR
205 // 6991377). So we have to set up the region(s) carefully and in
206 // a specific order.
207
208 // The word size sum of all the regions we will allocate.
209 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
210 assert(word_size <= word_size_sum, "sanity");
211
212 // This will be the "starts humongous" region.
213 HeapRegion* first_hr = region_at(first);
214 // The header of the new object will be placed at the bottom of
215 // the first region.
216 HeapWord* new_obj = first_hr->bottom();
217 // This will be the new top of the new object.
218 HeapWord* obj_top = new_obj + word_size;
219
220 // First, we need to zero the header of the space that we will be
221 // allocating. When we update top further down, some refinement
222 // threads might try to scan the region. By zeroing the header we
223 // ensure that any thread that will try to scan the region will
224 // come across the zero klass word and bail out.
225 //
226 // NOTE: It would not have been correct to have used
227 // CollectedHeap::fill_with_object() and make the space look like
228 // an int array. The thread that is doing the allocation will
229 // later update the object header to a potentially different array
230 // type and, for a very short period of time, the klass and length
231 // fields will be inconsistent. This could cause a refinement
232 // thread to calculate the object size incorrectly.
233 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
234
235 // Next, pad out the unused tail of the last region with filler
236 // objects, for improved usage accounting.
237 // How many words we use for filler objects.
238 size_t word_fill_size = word_size_sum - word_size;
239
240 // How many words memory we "waste" which cannot hold a filler object.
241 size_t words_not_fillable = 0;
242
243 if (word_fill_size >= min_fill_size()) {
244 fill_with_objects(obj_top, word_fill_size);
245 } else if (word_fill_size > 0) {
246 // We have space to fill, but we cannot fit an object there.
247 words_not_fillable = word_fill_size;
248 word_fill_size = 0;
249 }
250
251 // We will set up the first region as "starts humongous". This
252 // will also update the BOT covering all the regions to reflect
253 // that there is a single object that starts at the bottom of the
254 // first region.
255 first_hr->set_starts_humongous(obj_top, word_fill_size);
256 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
257 // Then, if there are any, we will set up the "continues
258 // humongous" regions.
259 HeapRegion* hr = NULL;
260 for (uint i = first + 1; i <= last; ++i) {
261 hr = region_at(i);
262 hr->set_continues_humongous(first_hr);
263 _g1_policy->remset_tracker()->update_at_allocate(hr);
264 }
265
266 // Up to this point no concurrent thread would have been able to
267 // do any scanning on any region in this series. All the top
268 // fields still point to bottom, so the intersection between
269 // [bottom,top] and [card_start,card_end] will be empty. Before we
270 // update the top fields, we'll do a storestore to make sure that
271 // no thread sees the update to top before the zeroing of the
272 // object header and the BOT initialization.
273 OrderAccess::storestore();
274
275 // Now, we will update the top fields of the "continues humongous"
276 // regions except the last one.
277 for (uint i = first; i < last; ++i) {
278 hr = region_at(i);
279 hr->set_top(hr->end());
280 }
281
282 hr = region_at(last);
283 // If we cannot fit a filler object, we must set top to the end
284 // of the humongous object, otherwise we cannot iterate the heap
285 // and the BOT will not be complete.
286 hr->set_top(hr->end() - words_not_fillable);
287
288 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
289 "obj_top should be in last region");
290
291 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
292
293 assert(words_not_fillable == 0 ||
294 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
295 "Miscalculation in humongous allocation");
296
297 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
298
299 for (uint i = first; i <= last; ++i) {
300 hr = region_at(i);
301 _humongous_set.add(hr);
302 _hr_printer.alloc(hr);
303 }
304
305 return new_obj;
306 }
307
308 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
309 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
310 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
311 }
312
313 // If could fit into free regions w/o expansion, try.
314 // Otherwise, if can expand, do so.
315 // Otherwise, if using ex regions might help, try with ex given back.
316 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
317 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
318
319 _verifier->verify_region_sets_optional();
320
321 uint first = G1_NO_HRM_INDEX;
322 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
323
324 if (obj_regions == 1) {
325 // Only one region to allocate, try to use a fast path by directly allocating
326 // from the free lists. Do not try to expand here, we will potentially do that
327 // later.
328 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
329 if (hr != NULL) {
330 first = hr->hrm_index();
331 }
332 } else {
333 // Policy: Try only empty regions (i.e. already committed first). Maybe we
334 // are lucky enough to find some.
335 first = _hrm.find_contiguous_only_empty(obj_regions);
336 if (first != G1_NO_HRM_INDEX) {
337 _hrm.allocate_free_regions_starting_at(first, obj_regions);
338 }
339 }
340
341 if (first == G1_NO_HRM_INDEX) {
342 // Policy: We could not find enough regions for the humongous object in the
343 // free list. Look through the heap to find a mix of free and uncommitted regions.
344 // If so, try expansion.
345 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
346 if (first != G1_NO_HRM_INDEX) {
347 // We found something. Make sure these regions are committed, i.e. expand
348 // the heap. Alternatively we could do a defragmentation GC.
349 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
350 word_size * HeapWordSize);
351
352 _hrm.expand_at(first, obj_regions, workers());
353 g1_policy()->record_new_heap_size(num_regions());
354
355 #ifdef ASSERT
356 for (uint i = first; i < first + obj_regions; ++i) {
357 HeapRegion* hr = region_at(i);
358 assert(hr->is_free(), "sanity");
359 assert(hr->is_empty(), "sanity");
360 assert(is_on_master_free_list(hr), "sanity");
361 }
362 #endif
363 _hrm.allocate_free_regions_starting_at(first, obj_regions);
364 } else {
365 // Policy: Potentially trigger a defragmentation GC.
366 }
367 }
368
369 HeapWord* result = NULL;
370 if (first != G1_NO_HRM_INDEX) {
371 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
372 assert(result != NULL, "it should always return a valid result");
373
374 // A successful humongous object allocation changes the used space
375 // information of the old generation so we need to recalculate the
376 // sizes and update the jstat counters here.
377 g1mm()->update_sizes();
378 }
379
380 _verifier->verify_region_sets_optional();
381
382 return result;
383 }
384
385 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
386 assert_heap_not_locked_and_not_at_safepoint();
387 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
388
389 return attempt_allocation(word_size);
390 }
391
392 HeapWord*
393 G1CollectedHeap::mem_allocate(size_t word_size,
394 bool* gc_overhead_limit_was_exceeded) {
395 assert_heap_not_locked_and_not_at_safepoint();
396
397 if (is_humongous(word_size)) {
398 return attempt_allocation_humongous(word_size);
399 }
400 return attempt_allocation(word_size);
401 }
402
403 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
404 ResourceMark rm; // For retrieving the thread names in log messages.
405
406 // Make sure you read the note in attempt_allocation_humongous().
407
408 assert_heap_not_locked_and_not_at_safepoint();
409 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
410 "be called for humongous allocation requests");
411
412 // We should only get here after the first-level allocation attempt
413 // (attempt_allocation()) failed to allocate.
414
415 // We will loop until a) we manage to successfully perform the
416 // allocation or b) we successfully schedule a collection which
417 // fails to perform the allocation. b) is the only case when we'll
418 // return NULL.
419 HeapWord* result = NULL;
420 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
421 bool should_try_gc;
422 uint gc_count_before;
423
424 {
425 MutexLockerEx x(Heap_lock);
426 result = _allocator->attempt_allocation_locked(word_size);
427 if (result != NULL) {
428 return result;
429 }
430
431 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
432 // This is different to when only GCLocker::needs_gc() is set: try to avoid
433 // waiting because the GCLocker is active to not wait too long.
434 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
435 // No need for an ergo message here, can_expand_young_list() does this when
436 // it returns true.
437 result = _allocator->attempt_allocation_force(word_size);
438 if (result != NULL) {
439 return result;
440 }
441 }
442 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
443 // the GCLocker initiated GC has been performed and then retry. This includes
444 // the case when the GC Locker is not active but has not been performed.
445 should_try_gc = !GCLocker::needs_gc();
446 // Read the GC count while still holding the Heap_lock.
447 gc_count_before = total_collections();
448 }
449
450 if (should_try_gc) {
451 bool succeeded;
452 result = do_collection_pause(word_size, gc_count_before, &succeeded,
453 GCCause::_g1_inc_collection_pause);
454 if (result != NULL) {
455 assert(succeeded, "only way to get back a non-NULL result");
456 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
457 Thread::current()->name(), p2i(result));
458 return result;
459 }
460
461 if (succeeded) {
462 // We successfully scheduled a collection which failed to allocate. No
463 // point in trying to allocate further. We'll just return NULL.
464 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
465 SIZE_FORMAT " words", Thread::current()->name(), word_size);
466 return NULL;
467 }
468 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
469 Thread::current()->name(), word_size);
470 } else {
471 // Failed to schedule a collection.
472 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
473 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
474 SIZE_FORMAT " words", Thread::current()->name(), word_size);
475 return NULL;
476 }
477 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
478 // The GCLocker is either active or the GCLocker initiated
479 // GC has not yet been performed. Stall until it is and
480 // then retry the allocation.
481 GCLocker::stall_until_clear();
482 gclocker_retry_count += 1;
483 }
484
485 // We can reach here if we were unsuccessful in scheduling a
486 // collection (because another thread beat us to it) or if we were
487 // stalled due to the GC locker. In either can we should retry the
488 // allocation attempt in case another thread successfully
489 // performed a collection and reclaimed enough space. We do the
490 // first attempt (without holding the Heap_lock) here and the
491 // follow-on attempt will be at the start of the next loop
492 // iteration (after taking the Heap_lock).
493
494 result = _allocator->attempt_allocation(word_size);
495 if (result != NULL) {
496 return result;
497 }
498
499 // Give a warning if we seem to be looping forever.
500 if ((QueuedAllocationWarningCount > 0) &&
501 (try_count % QueuedAllocationWarningCount == 0)) {
502 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
503 Thread::current()->name(), try_count, word_size);
504 }
505 }
506
507 ShouldNotReachHere();
508 return NULL;
509 }
510
511 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
512 assert_at_safepoint_on_vm_thread();
513 if (_archive_allocator == NULL) {
514 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
515 }
516 }
517
518 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
519 // Allocations in archive regions cannot be of a size that would be considered
520 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
521 // may be different at archive-restore time.
522 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
523 }
524
525 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
526 assert_at_safepoint_on_vm_thread();
527 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
528 if (is_archive_alloc_too_large(word_size)) {
529 return NULL;
530 }
531 return _archive_allocator->archive_mem_allocate(word_size);
532 }
533
534 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
535 size_t end_alignment_in_bytes) {
536 assert_at_safepoint_on_vm_thread();
537 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
538
539 // Call complete_archive to do the real work, filling in the MemRegion
540 // array with the archive regions.
541 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
542 delete _archive_allocator;
543 _archive_allocator = NULL;
544 }
545
546 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
547 assert(ranges != NULL, "MemRegion array NULL");
548 assert(count != 0, "No MemRegions provided");
549 MemRegion reserved = _hrm.reserved();
550 for (size_t i = 0; i < count; i++) {
551 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
552 return false;
553 }
554 }
555 return true;
556 }
557
558 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
559 size_t count,
560 bool open) {
561 assert(!is_init_completed(), "Expect to be called at JVM init time");
562 assert(ranges != NULL, "MemRegion array NULL");
563 assert(count != 0, "No MemRegions provided");
564 MutexLockerEx x(Heap_lock);
565
566 MemRegion reserved = _hrm.reserved();
567 HeapWord* prev_last_addr = NULL;
568 HeapRegion* prev_last_region = NULL;
569
570 // Temporarily disable pretouching of heap pages. This interface is used
571 // when mmap'ing archived heap data in, so pre-touching is wasted.
572 FlagSetting fs(AlwaysPreTouch, false);
573
574 // Enable archive object checking used by G1MarkSweep. We have to let it know
575 // about each archive range, so that objects in those ranges aren't marked.
576 G1ArchiveAllocator::enable_archive_object_check();
577
578 // For each specified MemRegion range, allocate the corresponding G1
579 // regions and mark them as archive regions. We expect the ranges
580 // in ascending starting address order, without overlap.
581 for (size_t i = 0; i < count; i++) {
582 MemRegion curr_range = ranges[i];
583 HeapWord* start_address = curr_range.start();
584 size_t word_size = curr_range.word_size();
585 HeapWord* last_address = curr_range.last();
586 size_t commits = 0;
587
588 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
589 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
590 p2i(start_address), p2i(last_address));
591 guarantee(start_address > prev_last_addr,
592 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
593 p2i(start_address), p2i(prev_last_addr));
594 prev_last_addr = last_address;
595
596 // Check for ranges that start in the same G1 region in which the previous
597 // range ended, and adjust the start address so we don't try to allocate
598 // the same region again. If the current range is entirely within that
599 // region, skip it, just adjusting the recorded top.
600 HeapRegion* start_region = _hrm.addr_to_region(start_address);
601 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
602 start_address = start_region->end();
603 if (start_address > last_address) {
604 increase_used(word_size * HeapWordSize);
605 start_region->set_top(last_address + 1);
606 continue;
607 }
608 start_region->set_top(start_address);
609 curr_range = MemRegion(start_address, last_address + 1);
610 start_region = _hrm.addr_to_region(start_address);
611 }
612
613 // Perform the actual region allocation, exiting if it fails.
614 // Then note how much new space we have allocated.
615 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
616 return false;
617 }
618 increase_used(word_size * HeapWordSize);
619 if (commits != 0) {
620 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
621 HeapRegion::GrainWords * HeapWordSize * commits);
622
623 }
624
625 // Mark each G1 region touched by the range as archive, add it to
626 // the old set, and set top.
627 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
628 HeapRegion* last_region = _hrm.addr_to_region(last_address);
629 prev_last_region = last_region;
630
631 while (curr_region != NULL) {
632 assert(curr_region->is_empty() && !curr_region->is_pinned(),
633 "Region already in use (index %u)", curr_region->hrm_index());
634 if (open) {
635 curr_region->set_open_archive();
636 } else {
637 curr_region->set_closed_archive();
638 }
639 _hr_printer.alloc(curr_region);
640 _old_set.add(curr_region);
641 HeapWord* top;
642 HeapRegion* next_region;
643 if (curr_region != last_region) {
644 top = curr_region->end();
645 next_region = _hrm.next_region_in_heap(curr_region);
646 } else {
647 top = last_address + 1;
648 next_region = NULL;
649 }
650 curr_region->set_top(top);
651 curr_region->set_first_dead(top);
652 curr_region->set_end_of_live(top);
653 curr_region = next_region;
654 }
655
656 // Notify mark-sweep of the archive
657 G1ArchiveAllocator::set_range_archive(curr_range, open);
658 }
659 return true;
660 }
661
662 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
663 assert(!is_init_completed(), "Expect to be called at JVM init time");
664 assert(ranges != NULL, "MemRegion array NULL");
665 assert(count != 0, "No MemRegions provided");
666 MemRegion reserved = _hrm.reserved();
667 HeapWord *prev_last_addr = NULL;
668 HeapRegion* prev_last_region = NULL;
669
670 // For each MemRegion, create filler objects, if needed, in the G1 regions
671 // that contain the address range. The address range actually within the
672 // MemRegion will not be modified. That is assumed to have been initialized
673 // elsewhere, probably via an mmap of archived heap data.
674 MutexLockerEx x(Heap_lock);
675 for (size_t i = 0; i < count; i++) {
676 HeapWord* start_address = ranges[i].start();
677 HeapWord* last_address = ranges[i].last();
678
679 assert(reserved.contains(start_address) && reserved.contains(last_address),
680 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
681 p2i(start_address), p2i(last_address));
682 assert(start_address > prev_last_addr,
683 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
684 p2i(start_address), p2i(prev_last_addr));
685
686 HeapRegion* start_region = _hrm.addr_to_region(start_address);
687 HeapRegion* last_region = _hrm.addr_to_region(last_address);
688 HeapWord* bottom_address = start_region->bottom();
689
690 // Check for a range beginning in the same region in which the
691 // previous one ended.
692 if (start_region == prev_last_region) {
693 bottom_address = prev_last_addr + 1;
694 }
695
696 // Verify that the regions were all marked as archive regions by
697 // alloc_archive_regions.
698 HeapRegion* curr_region = start_region;
699 while (curr_region != NULL) {
700 guarantee(curr_region->is_archive(),
701 "Expected archive region at index %u", curr_region->hrm_index());
702 if (curr_region != last_region) {
703 curr_region = _hrm.next_region_in_heap(curr_region);
704 } else {
705 curr_region = NULL;
706 }
707 }
708
709 prev_last_addr = last_address;
710 prev_last_region = last_region;
711
712 // Fill the memory below the allocated range with dummy object(s),
713 // if the region bottom does not match the range start, or if the previous
714 // range ended within the same G1 region, and there is a gap.
715 if (start_address != bottom_address) {
716 size_t fill_size = pointer_delta(start_address, bottom_address);
717 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
718 increase_used(fill_size * HeapWordSize);
719 }
720 }
721 }
722
723 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
724 assert_heap_not_locked_and_not_at_safepoint();
725 assert(!is_humongous(word_size), "attempt_allocation() should not "
726 "be called for humongous allocation requests");
727
728 HeapWord* result = _allocator->attempt_allocation(word_size);
729
730 if (result == NULL) {
731 result = attempt_allocation_slow(word_size);
732 }
733 assert_heap_not_locked();
734 if (result != NULL) {
735 dirty_young_block(result, word_size);
736 }
737 return result;
738 }
739
740 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
741 assert(!is_init_completed(), "Expect to be called at JVM init time");
742 assert(ranges != NULL, "MemRegion array NULL");
743 assert(count != 0, "No MemRegions provided");
744 MemRegion reserved = _hrm.reserved();
745 HeapWord* prev_last_addr = NULL;
746 HeapRegion* prev_last_region = NULL;
747 size_t size_used = 0;
748 size_t uncommitted_regions = 0;
749
750 // For each Memregion, free the G1 regions that constitute it, and
751 // notify mark-sweep that the range is no longer to be considered 'archive.'
752 MutexLockerEx x(Heap_lock);
753 for (size_t i = 0; i < count; i++) {
754 HeapWord* start_address = ranges[i].start();
755 HeapWord* last_address = ranges[i].last();
756
757 assert(reserved.contains(start_address) && reserved.contains(last_address),
758 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
759 p2i(start_address), p2i(last_address));
760 assert(start_address > prev_last_addr,
761 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
762 p2i(start_address), p2i(prev_last_addr));
763 size_used += ranges[i].byte_size();
764 prev_last_addr = last_address;
765
766 HeapRegion* start_region = _hrm.addr_to_region(start_address);
767 HeapRegion* last_region = _hrm.addr_to_region(last_address);
768
769 // Check for ranges that start in the same G1 region in which the previous
770 // range ended, and adjust the start address so we don't try to free
771 // the same region again. If the current range is entirely within that
772 // region, skip it.
773 if (start_region == prev_last_region) {
774 start_address = start_region->end();
775 if (start_address > last_address) {
776 continue;
777 }
778 start_region = _hrm.addr_to_region(start_address);
779 }
780 prev_last_region = last_region;
781
782 // After verifying that each region was marked as an archive region by
783 // alloc_archive_regions, set it free and empty and uncommit it.
784 HeapRegion* curr_region = start_region;
785 while (curr_region != NULL) {
786 guarantee(curr_region->is_archive(),
787 "Expected archive region at index %u", curr_region->hrm_index());
788 uint curr_index = curr_region->hrm_index();
789 _old_set.remove(curr_region);
790 curr_region->set_free();
791 curr_region->set_top(curr_region->bottom());
792 if (curr_region != last_region) {
793 curr_region = _hrm.next_region_in_heap(curr_region);
794 } else {
795 curr_region = NULL;
796 }
797 _hrm.shrink_at(curr_index, 1);
798 uncommitted_regions++;
799 }
800
801 // Notify mark-sweep that this is no longer an archive range.
802 G1ArchiveAllocator::set_range_archive(ranges[i], false);
803 }
804
805 if (uncommitted_regions != 0) {
806 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
807 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
808 }
809 decrease_used(size_used);
810 }
811
812 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
813 ResourceMark rm; // For retrieving the thread names in log messages.
814
815 // The structure of this method has a lot of similarities to
816 // attempt_allocation_slow(). The reason these two were not merged
817 // into a single one is that such a method would require several "if
818 // allocation is not humongous do this, otherwise do that"
819 // conditional paths which would obscure its flow. In fact, an early
820 // version of this code did use a unified method which was harder to
821 // follow and, as a result, it had subtle bugs that were hard to
822 // track down. So keeping these two methods separate allows each to
823 // be more readable. It will be good to keep these two in sync as
824 // much as possible.
825
826 assert_heap_not_locked_and_not_at_safepoint();
827 assert(is_humongous(word_size), "attempt_allocation_humongous() "
828 "should only be called for humongous allocations");
829
830 // Humongous objects can exhaust the heap quickly, so we should check if we
831 // need to start a marking cycle at each humongous object allocation. We do
832 // the check before we do the actual allocation. The reason for doing it
833 // before the allocation is that we avoid having to keep track of the newly
834 // allocated memory while we do a GC.
835 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
836 word_size)) {
837 collect(GCCause::_g1_humongous_allocation);
838 }
839
840 // We will loop until a) we manage to successfully perform the
841 // allocation or b) we successfully schedule a collection which
842 // fails to perform the allocation. b) is the only case when we'll
843 // return NULL.
844 HeapWord* result = NULL;
845 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
846 bool should_try_gc;
847 uint gc_count_before;
848
849
850 {
851 MutexLockerEx x(Heap_lock);
852
853 // Given that humongous objects are not allocated in young
854 // regions, we'll first try to do the allocation without doing a
855 // collection hoping that there's enough space in the heap.
856 result = humongous_obj_allocate(word_size);
857 if (result != NULL) {
858 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
859 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
860 return result;
861 }
862
863 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
864 // the GCLocker initiated GC has been performed and then retry. This includes
865 // the case when the GC Locker is not active but has not been performed.
866 should_try_gc = !GCLocker::needs_gc();
867 // Read the GC count while still holding the Heap_lock.
868 gc_count_before = total_collections();
869 }
870
871 if (should_try_gc) {
872 bool succeeded;
873 result = do_collection_pause(word_size, gc_count_before, &succeeded,
874 GCCause::_g1_humongous_allocation);
875 if (result != NULL) {
876 assert(succeeded, "only way to get back a non-NULL result");
877 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
878 Thread::current()->name(), p2i(result));
879 return result;
880 }
881
882 if (succeeded) {
883 // We successfully scheduled a collection which failed to allocate. No
884 // point in trying to allocate further. We'll just return NULL.
885 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
886 SIZE_FORMAT " words", Thread::current()->name(), word_size);
887 return NULL;
888 }
889 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
890 Thread::current()->name(), word_size);
891 } else {
892 // Failed to schedule a collection.
893 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
894 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
895 SIZE_FORMAT " words", Thread::current()->name(), word_size);
896 return NULL;
897 }
898 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
899 // The GCLocker is either active or the GCLocker initiated
900 // GC has not yet been performed. Stall until it is and
901 // then retry the allocation.
902 GCLocker::stall_until_clear();
903 gclocker_retry_count += 1;
904 }
905
906
907 // We can reach here if we were unsuccessful in scheduling a
908 // collection (because another thread beat us to it) or if we were
909 // stalled due to the GC locker. In either can we should retry the
910 // allocation attempt in case another thread successfully
911 // performed a collection and reclaimed enough space.
912 // Humongous object allocation always needs a lock, so we wait for the retry
913 // in the next iteration of the loop, unlike for the regular iteration case.
914 // Give a warning if we seem to be looping forever.
915
916 if ((QueuedAllocationWarningCount > 0) &&
917 (try_count % QueuedAllocationWarningCount == 0)) {
918 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
919 Thread::current()->name(), try_count, word_size);
920 }
921 }
922
923 ShouldNotReachHere();
924 return NULL;
925 }
926
927 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
928 bool expect_null_mutator_alloc_region) {
929 assert_at_safepoint_on_vm_thread();
930 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
931 "the current alloc region was unexpectedly found to be non-NULL");
932
933 if (!is_humongous(word_size)) {
934 return _allocator->attempt_allocation_locked(word_size);
935 } else {
936 HeapWord* result = humongous_obj_allocate(word_size);
937 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
938 collector_state()->set_initiate_conc_mark_if_possible(true);
939 }
940 return result;
941 }
942
943 ShouldNotReachHere();
944 }
945
946 class PostCompactionPrinterClosure: public HeapRegionClosure {
947 private:
948 G1HRPrinter* _hr_printer;
949 public:
950 bool do_heap_region(HeapRegion* hr) {
951 assert(!hr->is_young(), "not expecting to find young regions");
952 _hr_printer->post_compaction(hr);
953 return false;
954 }
955
956 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
957 : _hr_printer(hr_printer) { }
958 };
959
960 void G1CollectedHeap::print_hrm_post_compaction() {
961 if (_hr_printer.is_active()) {
962 PostCompactionPrinterClosure cl(hr_printer());
963 heap_region_iterate(&cl);
964 }
965 }
966
967 void G1CollectedHeap::abort_concurrent_cycle() {
968 // If we start the compaction before the CM threads finish
969 // scanning the root regions we might trip them over as we'll
970 // be moving objects / updating references. So let's wait until
971 // they are done. By telling them to abort, they should complete
972 // early.
973 _cm->root_regions()->abort();
974 _cm->root_regions()->wait_until_scan_finished();
975
976 // Disable discovery and empty the discovered lists
977 // for the CM ref processor.
978 ref_processor_cm()->disable_discovery();
979 ref_processor_cm()->abandon_partial_discovery();
980 ref_processor_cm()->verify_no_references_recorded();
981
982 // Abandon current iterations of concurrent marking and concurrent
983 // refinement, if any are in progress.
984 concurrent_mark()->concurrent_cycle_abort();
985 }
986
987 void G1CollectedHeap::prepare_heap_for_full_collection() {
988 // Make sure we'll choose a new allocation region afterwards.
989 _allocator->release_mutator_alloc_region();
990 _allocator->abandon_gc_alloc_regions();
991 g1_rem_set()->cleanupHRRS();
992
993 // We may have added regions to the current incremental collection
994 // set between the last GC or pause and now. We need to clear the
995 // incremental collection set and then start rebuilding it afresh
996 // after this full GC.
997 abandon_collection_set(collection_set());
998
999 tear_down_region_sets(false /* free_list_only */);
1000 }
1001
1002 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1003 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1004 assert(used() == recalculate_used(), "Should be equal");
1005 _verifier->verify_region_sets_optional();
1006 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1007 _verifier->check_bitmaps("Full GC Start");
1008 }
1009
1010 void G1CollectedHeap::prepare_heap_for_mutators() {
1011 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1012 ClassLoaderDataGraph::purge();
1013 MetaspaceUtils::verify_metrics();
1014
1015 // Prepare heap for normal collections.
1016 assert(num_free_regions() == 0, "we should not have added any free regions");
1017 rebuild_region_sets(false /* free_list_only */);
1018 abort_refinement();
1019 resize_if_necessary_after_full_collection();
1020
1021 // Rebuild the strong code root lists for each region
1022 rebuild_strong_code_roots();
1023
1024 // Start a new incremental collection set for the next pause
1025 start_new_collection_set();
1026
1027 _allocator->init_mutator_alloc_region();
1028
1029 // Post collection state updates.
1030 MetaspaceGC::compute_new_size();
1031 }
1032
1033 void G1CollectedHeap::abort_refinement() {
1034 if (_hot_card_cache->use_cache()) {
1035 _hot_card_cache->reset_hot_cache();
1036 }
1037
1038 // Discard all remembered set updates.
1039 JavaThread::dirty_card_queue_set().abandon_logs();
1040 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1041 }
1042
1043 void G1CollectedHeap::verify_after_full_collection() {
1044 _hrm.verify_optional();
1045 _verifier->verify_region_sets_optional();
1046 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1047 // Clear the previous marking bitmap, if needed for bitmap verification.
1048 // Note we cannot do this when we clear the next marking bitmap in
1049 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1050 // objects marked during a full GC against the previous bitmap.
1051 // But we need to clear it before calling check_bitmaps below since
1052 // the full GC has compacted objects and updated TAMS but not updated
1053 // the prev bitmap.
1054 if (G1VerifyBitmaps) {
1055 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1056 _cm->clear_prev_bitmap(workers());
1057 }
1058 _verifier->check_bitmaps("Full GC End");
1059
1060 // At this point there should be no regions in the
1061 // entire heap tagged as young.
1062 assert(check_young_list_empty(), "young list should be empty at this point");
1063
1064 // Note: since we've just done a full GC, concurrent
1065 // marking is no longer active. Therefore we need not
1066 // re-enable reference discovery for the CM ref processor.
1067 // That will be done at the start of the next marking cycle.
1068 // We also know that the STW processor should no longer
1069 // discover any new references.
1070 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1071 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1072 ref_processor_stw()->verify_no_references_recorded();
1073 ref_processor_cm()->verify_no_references_recorded();
1074 }
1075
1076 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1077 // Post collection logging.
1078 // We should do this after we potentially resize the heap so
1079 // that all the COMMIT / UNCOMMIT events are generated before
1080 // the compaction events.
1081 print_hrm_post_compaction();
1082 heap_transition->print();
1083 print_heap_after_gc();
1084 print_heap_regions();
1085 #ifdef TRACESPINNING
1086 ParallelTaskTerminator::print_termination_counts();
1087 #endif
1088 }
1089
1090 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1091 bool clear_all_soft_refs) {
1092 assert_at_safepoint_on_vm_thread();
1093
1094 if (GCLocker::check_active_before_gc()) {
1095 // Full GC was not completed.
1096 return false;
1097 }
1098
1099 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1100 soft_ref_policy()->should_clear_all_soft_refs();
1101
1102 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1103 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1104
1105 collector.prepare_collection();
1106 collector.collect();
1107 collector.complete_collection();
1108
1109 // Full collection was successfully completed.
1110 return true;
1111 }
1112
1113 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1114 // Currently, there is no facility in the do_full_collection(bool) API to notify
1115 // the caller that the collection did not succeed (e.g., because it was locked
1116 // out by the GC locker). So, right now, we'll ignore the return value.
1117 bool dummy = do_full_collection(true, /* explicit_gc */
1118 clear_all_soft_refs);
1119 }
1120
1121 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1122 // Capacity, free and used after the GC counted as full regions to
1123 // include the waste in the following calculations.
1124 const size_t capacity_after_gc = capacity();
1125 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1126
1127 // This is enforced in arguments.cpp.
1128 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1129 "otherwise the code below doesn't make sense");
1130
1131 // We don't have floating point command-line arguments
1132 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1133 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1134 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1135 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1136
1137 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1138 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1139
1140 // We have to be careful here as these two calculations can overflow
1141 // 32-bit size_t's.
1142 double used_after_gc_d = (double) used_after_gc;
1143 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1144 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1145
1146 // Let's make sure that they are both under the max heap size, which
1147 // by default will make them fit into a size_t.
1148 double desired_capacity_upper_bound = (double) max_heap_size;
1149 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1150 desired_capacity_upper_bound);
1151 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1152 desired_capacity_upper_bound);
1153
1154 // We can now safely turn them into size_t's.
1155 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1156 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1157
1158 // This assert only makes sense here, before we adjust them
1159 // with respect to the min and max heap size.
1160 assert(minimum_desired_capacity <= maximum_desired_capacity,
1161 "minimum_desired_capacity = " SIZE_FORMAT ", "
1162 "maximum_desired_capacity = " SIZE_FORMAT,
1163 minimum_desired_capacity, maximum_desired_capacity);
1164
1165 // Should not be greater than the heap max size. No need to adjust
1166 // it with respect to the heap min size as it's a lower bound (i.e.,
1167 // we'll try to make the capacity larger than it, not smaller).
1168 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1169 // Should not be less than the heap min size. No need to adjust it
1170 // with respect to the heap max size as it's an upper bound (i.e.,
1171 // we'll try to make the capacity smaller than it, not greater).
1172 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1173
1174 if (capacity_after_gc < minimum_desired_capacity) {
1175 // Don't expand unless it's significant
1176 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1177
1178 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1179 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1180 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1181 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1182
1183 expand(expand_bytes, _workers);
1184
1185 // No expansion, now see if we want to shrink
1186 } else if (capacity_after_gc > maximum_desired_capacity) {
1187 // Capacity too large, compute shrinking size
1188 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1189
1190 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1191 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1192 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1193 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1194
1195 shrink(shrink_bytes);
1196 }
1197 }
1198
1199 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1200 bool do_gc,
1201 bool clear_all_soft_refs,
1202 bool expect_null_mutator_alloc_region,
1203 bool* gc_succeeded) {
1204 *gc_succeeded = true;
1205 // Let's attempt the allocation first.
1206 HeapWord* result =
1207 attempt_allocation_at_safepoint(word_size,
1208 expect_null_mutator_alloc_region);
1209 if (result != NULL) {
1210 return result;
1211 }
1212
1213 // In a G1 heap, we're supposed to keep allocation from failing by
1214 // incremental pauses. Therefore, at least for now, we'll favor
1215 // expansion over collection. (This might change in the future if we can
1216 // do something smarter than full collection to satisfy a failed alloc.)
1217 result = expand_and_allocate(word_size);
1218 if (result != NULL) {
1219 return result;
1220 }
1221
1222 if (do_gc) {
1223 // Expansion didn't work, we'll try to do a Full GC.
1224 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1225 clear_all_soft_refs);
1226 }
1227
1228 return NULL;
1229 }
1230
1231 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1232 bool* succeeded) {
1233 assert_at_safepoint_on_vm_thread();
1234
1235 // Attempts to allocate followed by Full GC.
1236 HeapWord* result =
1237 satisfy_failed_allocation_helper(word_size,
1238 true, /* do_gc */
1239 false, /* clear_all_soft_refs */
1240 false, /* expect_null_mutator_alloc_region */
1241 succeeded);
1242
1243 if (result != NULL || !*succeeded) {
1244 return result;
1245 }
1246
1247 // Attempts to allocate followed by Full GC that will collect all soft references.
1248 result = satisfy_failed_allocation_helper(word_size,
1249 true, /* do_gc */
1250 true, /* clear_all_soft_refs */
1251 true, /* expect_null_mutator_alloc_region */
1252 succeeded);
1253
1254 if (result != NULL || !*succeeded) {
1255 return result;
1256 }
1257
1258 // Attempts to allocate, no GC
1259 result = satisfy_failed_allocation_helper(word_size,
1260 false, /* do_gc */
1261 false, /* clear_all_soft_refs */
1262 true, /* expect_null_mutator_alloc_region */
1263 succeeded);
1264
1265 if (result != NULL) {
1266 return result;
1267 }
1268
1269 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1270 "Flag should have been handled and cleared prior to this point");
1271
1272 // What else? We might try synchronous finalization later. If the total
1273 // space available is large enough for the allocation, then a more
1274 // complete compaction phase than we've tried so far might be
1275 // appropriate.
1276 return NULL;
1277 }
1278
1279 // Attempting to expand the heap sufficiently
1280 // to support an allocation of the given "word_size". If
1281 // successful, perform the allocation and return the address of the
1282 // allocated block, or else "NULL".
1283
1284 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1285 assert_at_safepoint_on_vm_thread();
1286
1287 _verifier->verify_region_sets_optional();
1288
1289 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1290 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1291 word_size * HeapWordSize);
1292
1293
1294 if (expand(expand_bytes, _workers)) {
1295 _hrm.verify_optional();
1296 _verifier->verify_region_sets_optional();
1297 return attempt_allocation_at_safepoint(word_size,
1298 false /* expect_null_mutator_alloc_region */);
1299 }
1300 return NULL;
1301 }
1302
1303 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1304 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1305 aligned_expand_bytes = align_up(aligned_expand_bytes,
1306 HeapRegion::GrainBytes);
1307
1308 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1309 expand_bytes, aligned_expand_bytes);
1310
1311 if (is_maximal_no_gc()) {
1312 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1313 return false;
1314 }
1315
1316 double expand_heap_start_time_sec = os::elapsedTime();
1317 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1318 assert(regions_to_expand > 0, "Must expand by at least one region");
1319
1320 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1321 if (expand_time_ms != NULL) {
1322 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1323 }
1324
1325 if (expanded_by > 0) {
1326 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1327 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1328 g1_policy()->record_new_heap_size(num_regions());
1329 } else {
1330 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1331
1332 // The expansion of the virtual storage space was unsuccessful.
1333 // Let's see if it was because we ran out of swap.
1334 if (G1ExitOnExpansionFailure &&
1335 _hrm.available() >= regions_to_expand) {
1336 // We had head room...
1337 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1338 }
1339 }
1340 return regions_to_expand > 0;
1341 }
1342
1343 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1344 size_t aligned_shrink_bytes =
1345 ReservedSpace::page_align_size_down(shrink_bytes);
1346 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1347 HeapRegion::GrainBytes);
1348 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1349
1350 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1351 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1352
1353
1354 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",
1355 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1356 if (num_regions_removed > 0) {
1357 g1_policy()->record_new_heap_size(num_regions());
1358 } else {
1359 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1360 }
1361 }
1362
1363 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1364 _verifier->verify_region_sets_optional();
1365
1366 // We should only reach here at the end of a Full GC which means we
1367 // should not not be holding to any GC alloc regions. The method
1368 // below will make sure of that and do any remaining clean up.
1369 _allocator->abandon_gc_alloc_regions();
1370
1371 // Instead of tearing down / rebuilding the free lists here, we
1372 // could instead use the remove_all_pending() method on free_list to
1373 // remove only the ones that we need to remove.
1374 tear_down_region_sets(true /* free_list_only */);
1375 shrink_helper(shrink_bytes);
1376 rebuild_region_sets(true /* free_list_only */);
1377
1378 _hrm.verify_optional();
1379 _verifier->verify_region_sets_optional();
1380 }
1381
1382 // Public methods.
1383
1384 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1385 CollectedHeap(),
1386 _young_gen_sampling_thread(NULL),
1387 _collector_policy(collector_policy),
1388 _soft_ref_policy(),
1389 _card_table(NULL),
1390 _memory_manager("G1 Young Generation", "end of minor GC"),
1391 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1392 _eden_pool(NULL),
1393 _survivor_pool(NULL),
1394 _old_pool(NULL),
1395 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1396 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1397 _g1_policy(new G1Policy(_gc_timer_stw)),
1398 _collection_set(this, _g1_policy),
1399 _dirty_card_queue_set(false),
1400 _is_alive_closure_cm(this),
1401 _is_alive_closure_stw(this),
1402 _ref_processor_cm(NULL),
1403 _ref_processor_stw(NULL),
1404 _bot(NULL),
1405 _hot_card_cache(NULL),
1406 _g1_rem_set(NULL),
1407 _cr(NULL),
1408 _g1mm(NULL),
1409 _preserved_marks_set(true /* in_c_heap */),
1410 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1411 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1412 _humongous_reclaim_candidates(),
1413 _has_humongous_reclaim_candidates(false),
1414 _archive_allocator(NULL),
1415 _summary_bytes_used(0),
1416 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1417 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1418 _expand_heap_after_alloc_failure(true),
1419 _old_marking_cycles_started(0),
1420 _old_marking_cycles_completed(0),
1421 _in_cset_fast_test() {
1422
1423 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1424 /* are_GC_task_threads */true,
1425 /* are_ConcurrentGC_threads */false);
1426 _workers->initialize_workers();
1427 _verifier = new G1HeapVerifier(this);
1428
1429 _allocator = new G1DefaultAllocator(this);
1430
1431 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1432
1433 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1434
1435 // Override the default _filler_array_max_size so that no humongous filler
1436 // objects are created.
1437 _filler_array_max_size = _humongous_object_threshold_in_words;
1438
1439 uint n_queues = ParallelGCThreads;
1440 _task_queues = new RefToScanQueueSet(n_queues);
1441
1442 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1443
1444 for (uint i = 0; i < n_queues; i++) {
1445 RefToScanQueue* q = new RefToScanQueue();
1446 q->initialize();
1447 _task_queues->register_queue(i, q);
1448 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1449 }
1450
1451 // Initialize the G1EvacuationFailureALot counters and flags.
1452 NOT_PRODUCT(reset_evacuation_should_fail();)
1453
1454 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1455 }
1456
1457 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1458 size_t size,
1459 size_t translation_factor) {
1460 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1461 // Allocate a new reserved space, preferring to use large pages.
1462 ReservedSpace rs(size, preferred_page_size);
1463 G1RegionToSpaceMapper* result =
1464 G1RegionToSpaceMapper::create_mapper(rs,
1465 size,
1466 rs.alignment(),
1467 HeapRegion::GrainBytes,
1468 translation_factor,
1469 mtGC);
1470
1471 os::trace_page_sizes_for_requested_size(description,
1472 size,
1473 preferred_page_size,
1474 rs.alignment(),
1475 rs.base(),
1476 rs.size());
1477
1478 return result;
1479 }
1480
1481 jint G1CollectedHeap::initialize_concurrent_refinement() {
1482 jint ecode = JNI_OK;
1483 _cr = G1ConcurrentRefine::create(&ecode);
1484 return ecode;
1485 }
1486
1487 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1488 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1489 if (_young_gen_sampling_thread->osthread() == NULL) {
1490 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1491 return JNI_ENOMEM;
1492 }
1493 return JNI_OK;
1494 }
1495
1496 jint G1CollectedHeap::initialize() {
1497 os::enable_vtime();
1498
1499 // Necessary to satisfy locking discipline assertions.
1500
1501 MutexLocker x(Heap_lock);
1502
1503 // While there are no constraints in the GC code that HeapWordSize
1504 // be any particular value, there are multiple other areas in the
1505 // system which believe this to be true (e.g. oop->object_size in some
1506 // cases incorrectly returns the size in wordSize units rather than
1507 // HeapWordSize).
1508 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1509
1510 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1511 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1512 size_t heap_alignment = collector_policy()->heap_alignment();
1513
1514 // Ensure that the sizes are properly aligned.
1515 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1516 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1517 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1518
1519 // Reserve the maximum.
1520
1521 // When compressed oops are enabled, the preferred heap base
1522 // is calculated by subtracting the requested size from the
1523 // 32Gb boundary and using the result as the base address for
1524 // heap reservation. If the requested size is not aligned to
1525 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1526 // into the ReservedHeapSpace constructor) then the actual
1527 // base of the reserved heap may end up differing from the
1528 // address that was requested (i.e. the preferred heap base).
1529 // If this happens then we could end up using a non-optimal
1530 // compressed oops mode.
1531
1532 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1533 heap_alignment);
1534
1535 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1536
1537 // Create the barrier set for the entire reserved region.
1538 G1CardTable* ct = new G1CardTable(reserved_region());
1539 ct->initialize();
1540 G1BarrierSet* bs = new G1BarrierSet(ct);
1541 bs->initialize();
1542 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1543 set_barrier_set(bs);
1544 _card_table = ct;
1545
1546 // Create the hot card cache.
1547 _hot_card_cache = new G1HotCardCache(this);
1548
1549 // Carve out the G1 part of the heap.
1550 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1551 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1552 G1RegionToSpaceMapper* heap_storage =
1553 G1RegionToSpaceMapper::create_mapper(g1_rs,
1554 g1_rs.size(),
1555 page_size,
1556 HeapRegion::GrainBytes,
1557 1,
1558 mtJavaHeap);
1559 os::trace_page_sizes("Heap",
1560 collector_policy()->min_heap_byte_size(),
1561 max_byte_size,
1562 page_size,
1563 heap_rs.base(),
1564 heap_rs.size());
1565 heap_storage->set_mapping_changed_listener(&_listener);
1566
1567 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1568 G1RegionToSpaceMapper* bot_storage =
1569 create_aux_memory_mapper("Block Offset Table",
1570 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1571 G1BlockOffsetTable::heap_map_factor());
1572
1573 G1RegionToSpaceMapper* cardtable_storage =
1574 create_aux_memory_mapper("Card Table",
1575 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1576 G1CardTable::heap_map_factor());
1577
1578 G1RegionToSpaceMapper* card_counts_storage =
1579 create_aux_memory_mapper("Card Counts Table",
1580 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1581 G1CardCounts::heap_map_factor());
1582
1583 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1584 G1RegionToSpaceMapper* prev_bitmap_storage =
1585 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1586 G1RegionToSpaceMapper* next_bitmap_storage =
1587 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1588
1589 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1590 _card_table->initialize(cardtable_storage);
1591 // Do later initialization work for concurrent refinement.
1592 _hot_card_cache->initialize(card_counts_storage);
1593
1594 // 6843694 - ensure that the maximum region index can fit
1595 // in the remembered set structures.
1596 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1597 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1598
1599 // Also create a G1 rem set.
1600 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1601 _g1_rem_set->initialize(max_capacity(), max_regions());
1602
1603 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1604 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1605 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1606 "too many cards per region");
1607
1608 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1609
1610 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1611
1612 {
1613 HeapWord* start = _hrm.reserved().start();
1614 HeapWord* end = _hrm.reserved().end();
1615 size_t granularity = HeapRegion::GrainBytes;
1616
1617 _in_cset_fast_test.initialize(start, end, granularity);
1618 _humongous_reclaim_candidates.initialize(start, end, granularity);
1619 }
1620
1621 // Create the G1ConcurrentMark data structure and thread.
1622 // (Must do this late, so that "max_regions" is defined.)
1623 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1624 if (_cm == NULL || !_cm->completed_initialization()) {
1625 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1626 return JNI_ENOMEM;
1627 }
1628 _cmThread = _cm->cm_thread();
1629
1630 // Now expand into the initial heap size.
1631 if (!expand(init_byte_size, _workers)) {
1632 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1633 return JNI_ENOMEM;
1634 }
1635
1636 // Perform any initialization actions delegated to the policy.
1637 g1_policy()->init(this, &_collection_set);
1638
1639 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1640 SATB_Q_FL_lock,
1641 G1SATBProcessCompletedThreshold,
1642 Shared_SATB_Q_lock);
1643
1644 jint ecode = initialize_concurrent_refinement();
1645 if (ecode != JNI_OK) {
1646 return ecode;
1647 }
1648
1649 ecode = initialize_young_gen_sampling_thread();
1650 if (ecode != JNI_OK) {
1651 return ecode;
1652 }
1653
1654 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1655 DirtyCardQ_FL_lock,
1656 (int)concurrent_refine()->yellow_zone(),
1657 (int)concurrent_refine()->red_zone(),
1658 Shared_DirtyCardQ_lock,
1659 NULL, // fl_owner
1660 true); // init_free_ids
1661
1662 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1663 DirtyCardQ_FL_lock,
1664 -1, // never trigger processing
1665 -1, // no limit on length
1666 Shared_DirtyCardQ_lock,
1667 &JavaThread::dirty_card_queue_set());
1668
1669 // Here we allocate the dummy HeapRegion that is required by the
1670 // G1AllocRegion class.
1671 HeapRegion* dummy_region = _hrm.get_dummy_region();
1672
1673 // We'll re-use the same region whether the alloc region will
1674 // require BOT updates or not and, if it doesn't, then a non-young
1675 // region will complain that it cannot support allocations without
1676 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1677 dummy_region->set_eden();
1678 // Make sure it's full.
1679 dummy_region->set_top(dummy_region->end());
1680 G1AllocRegion::setup(this, dummy_region);
1681
1682 _allocator->init_mutator_alloc_region();
1683
1684 // Do create of the monitoring and management support so that
1685 // values in the heap have been properly initialized.
1686 _g1mm = new G1MonitoringSupport(this);
1687
1688 G1StringDedup::initialize();
1689
1690 _preserved_marks_set.init(ParallelGCThreads);
1691
1692 _collection_set.initialize(max_regions());
1693
1694 return JNI_OK;
1695 }
1696
1697 void G1CollectedHeap::initialize_serviceability() {
1698 _eden_pool = new G1EdenPool(this);
1699 _survivor_pool = new G1SurvivorPool(this);
1700 _old_pool = new G1OldGenPool(this);
1701
1702 _full_gc_memory_manager.add_pool(_eden_pool);
1703 _full_gc_memory_manager.add_pool(_survivor_pool);
1704 _full_gc_memory_manager.add_pool(_old_pool);
1705
1706 _memory_manager.add_pool(_eden_pool);
1707 _memory_manager.add_pool(_survivor_pool);
1708
1709 }
1710
1711 void G1CollectedHeap::stop() {
1712 // Stop all concurrent threads. We do this to make sure these threads
1713 // do not continue to execute and access resources (e.g. logging)
1714 // that are destroyed during shutdown.
1715 _cr->stop();
1716 _young_gen_sampling_thread->stop();
1717 _cmThread->stop();
1718 if (G1StringDedup::is_enabled()) {
1719 G1StringDedup::stop();
1720 }
1721 }
1722
1723 void G1CollectedHeap::safepoint_synchronize_begin() {
1724 SuspendibleThreadSet::synchronize();
1725 }
1726
1727 void G1CollectedHeap::safepoint_synchronize_end() {
1728 SuspendibleThreadSet::desynchronize();
1729 }
1730
1731 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1732 return HeapRegion::max_region_size();
1733 }
1734
1735 void G1CollectedHeap::post_initialize() {
1736 CollectedHeap::post_initialize();
1737 ref_processing_init();
1738 }
1739
1740 void G1CollectedHeap::ref_processing_init() {
1741 // Reference processing in G1 currently works as follows:
1742 //
1743 // * There are two reference processor instances. One is
1744 // used to record and process discovered references
1745 // during concurrent marking; the other is used to
1746 // record and process references during STW pauses
1747 // (both full and incremental).
1748 // * Both ref processors need to 'span' the entire heap as
1749 // the regions in the collection set may be dotted around.
1750 //
1751 // * For the concurrent marking ref processor:
1752 // * Reference discovery is enabled at initial marking.
1753 // * Reference discovery is disabled and the discovered
1754 // references processed etc during remarking.
1755 // * Reference discovery is MT (see below).
1756 // * Reference discovery requires a barrier (see below).
1757 // * Reference processing may or may not be MT
1758 // (depending on the value of ParallelRefProcEnabled
1759 // and ParallelGCThreads).
1760 // * A full GC disables reference discovery by the CM
1761 // ref processor and abandons any entries on it's
1762 // discovered lists.
1763 //
1764 // * For the STW processor:
1765 // * Non MT discovery is enabled at the start of a full GC.
1766 // * Processing and enqueueing during a full GC is non-MT.
1767 // * During a full GC, references are processed after marking.
1768 //
1769 // * Discovery (may or may not be MT) is enabled at the start
1770 // of an incremental evacuation pause.
1771 // * References are processed near the end of a STW evacuation pause.
1772 // * For both types of GC:
1773 // * Discovery is atomic - i.e. not concurrent.
1774 // * Reference discovery will not need a barrier.
1775
1776 MemRegion mr = reserved_region();
1777
1778 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1779
1780 // Concurrent Mark ref processor
1781 _ref_processor_cm =
1782 new ReferenceProcessor(mr, // span
1783 mt_processing,
1784 // mt processing
1785 ParallelGCThreads,
1786 // degree of mt processing
1787 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1788 // mt discovery
1789 MAX2(ParallelGCThreads, ConcGCThreads),
1790 // degree of mt discovery
1791 false,
1792 // Reference discovery is not atomic
1793 &_is_alive_closure_cm);
1794 // is alive closure
1795 // (for efficiency/performance)
1796
1797 // STW ref processor
1798 _ref_processor_stw =
1799 new ReferenceProcessor(mr, // span
1800 mt_processing,
1801 // mt processing
1802 ParallelGCThreads,
1803 // degree of mt processing
1804 (ParallelGCThreads > 1),
1805 // mt discovery
1806 ParallelGCThreads,
1807 // degree of mt discovery
1808 true,
1809 // Reference discovery is atomic
1810 &_is_alive_closure_stw);
1811 // is alive closure
1812 // (for efficiency/performance)
1813 }
1814
1815 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1816 return _collector_policy;
1817 }
1818
1819 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1820 return &_soft_ref_policy;
1821 }
1822
1823 size_t G1CollectedHeap::capacity() const {
1824 return _hrm.length() * HeapRegion::GrainBytes;
1825 }
1826
1827 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1828 return _hrm.total_free_bytes();
1829 }
1830
1831 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1832 _hot_card_cache->drain(cl, worker_i);
1833 }
1834
1835 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1836 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1837 size_t n_completed_buffers = 0;
1838 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1839 n_completed_buffers++;
1840 }
1841 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1842 dcqs.clear_n_completed_buffers();
1843 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1844 }
1845
1846 // Computes the sum of the storage used by the various regions.
1847 size_t G1CollectedHeap::used() const {
1848 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1849 if (_archive_allocator != NULL) {
1850 result += _archive_allocator->used();
1851 }
1852 return result;
1853 }
1854
1855 size_t G1CollectedHeap::used_unlocked() const {
1856 return _summary_bytes_used;
1857 }
1858
1859 class SumUsedClosure: public HeapRegionClosure {
1860 size_t _used;
1861 public:
1862 SumUsedClosure() : _used(0) {}
1863 bool do_heap_region(HeapRegion* r) {
1864 _used += r->used();
1865 return false;
1866 }
1867 size_t result() { return _used; }
1868 };
1869
1870 size_t G1CollectedHeap::recalculate_used() const {
1871 double recalculate_used_start = os::elapsedTime();
1872
1873 SumUsedClosure blk;
1874 heap_region_iterate(&blk);
1875
1876 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1877 return blk.result();
1878 }
1879
1880 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1881 switch (cause) {
1882 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1883 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1884 case GCCause::_wb_conc_mark: return true;
1885 default : return false;
1886 }
1887 }
1888
1889 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1890 switch (cause) {
1891 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1892 case GCCause::_g1_humongous_allocation: return true;
1893 default: return is_user_requested_concurrent_full_gc(cause);
1894 }
1895 }
1896
1897 #ifndef PRODUCT
1898 void G1CollectedHeap::allocate_dummy_regions() {
1899 // Let's fill up most of the region
1900 size_t word_size = HeapRegion::GrainWords - 1024;
1901 // And as a result the region we'll allocate will be humongous.
1902 guarantee(is_humongous(word_size), "sanity");
1903
1904 // _filler_array_max_size is set to humongous object threshold
1905 // but temporarily change it to use CollectedHeap::fill_with_object().
1906 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1907
1908 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1909 // Let's use the existing mechanism for the allocation
1910 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1911 if (dummy_obj != NULL) {
1912 MemRegion mr(dummy_obj, word_size);
1913 CollectedHeap::fill_with_object(mr);
1914 } else {
1915 // If we can't allocate once, we probably cannot allocate
1916 // again. Let's get out of the loop.
1917 break;
1918 }
1919 }
1920 }
1921 #endif // !PRODUCT
1922
1923 void G1CollectedHeap::increment_old_marking_cycles_started() {
1924 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1925 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1926 "Wrong marking cycle count (started: %d, completed: %d)",
1927 _old_marking_cycles_started, _old_marking_cycles_completed);
1928
1929 _old_marking_cycles_started++;
1930 }
1931
1932 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
1933 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1934
1935 // We assume that if concurrent == true, then the caller is a
1936 // concurrent thread that was joined the Suspendible Thread
1937 // Set. If there's ever a cheap way to check this, we should add an
1938 // assert here.
1939
1940 // Given that this method is called at the end of a Full GC or of a
1941 // concurrent cycle, and those can be nested (i.e., a Full GC can
1942 // interrupt a concurrent cycle), the number of full collections
1943 // completed should be either one (in the case where there was no
1944 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1945 // behind the number of full collections started.
1946
1947 // This is the case for the inner caller, i.e. a Full GC.
1948 assert(concurrent ||
1949 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1950 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1951 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1952 "is inconsistent with _old_marking_cycles_completed = %u",
1953 _old_marking_cycles_started, _old_marking_cycles_completed);
1954
1955 // This is the case for the outer caller, i.e. the concurrent cycle.
1956 assert(!concurrent ||
1957 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1958 "for outer caller (concurrent cycle): "
1959 "_old_marking_cycles_started = %u "
1960 "is inconsistent with _old_marking_cycles_completed = %u",
1961 _old_marking_cycles_started, _old_marking_cycles_completed);
1962
1963 _old_marking_cycles_completed += 1;
1964
1965 // We need to clear the "in_progress" flag in the CM thread before
1966 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1967 // is set) so that if a waiter requests another System.gc() it doesn't
1968 // incorrectly see that a marking cycle is still in progress.
1969 if (concurrent) {
1970 _cmThread->set_idle();
1971 }
1972
1973 // This notify_all() will ensure that a thread that called
1974 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
1975 // and it's waiting for a full GC to finish will be woken up. It is
1976 // waiting in VM_G1CollectForAllocation::doit_epilogue().
1977 FullGCCount_lock->notify_all();
1978 }
1979
1980 void G1CollectedHeap::collect(GCCause::Cause cause) {
1981 assert_heap_not_locked();
1982
1983 uint gc_count_before;
1984 uint old_marking_count_before;
1985 uint full_gc_count_before;
1986 bool retry_gc;
1987
1988 do {
1989 retry_gc = false;
1990
1991 {
1992 MutexLocker ml(Heap_lock);
1993
1994 // Read the GC count while holding the Heap_lock
1995 gc_count_before = total_collections();
1996 full_gc_count_before = total_full_collections();
1997 old_marking_count_before = _old_marking_cycles_started;
1998 }
1999
2000 if (should_do_concurrent_full_gc(cause)) {
2001 // Schedule an initial-mark evacuation pause that will start a
2002 // concurrent cycle. We're setting word_size to 0 which means that
2003 // we are not requesting a post-GC allocation.
2004 VM_G1CollectForAllocation op(0, /* word_size */
2005 gc_count_before,
2006 cause,
2007 true, /* should_initiate_conc_mark */
2008 g1_policy()->max_pause_time_ms());
2009 VMThread::execute(&op);
2010 if (!op.pause_succeeded()) {
2011 if (old_marking_count_before == _old_marking_cycles_started) {
2012 retry_gc = op.should_retry_gc();
2013 } else {
2014 // A Full GC happened while we were trying to schedule the
2015 // initial-mark GC. No point in starting a new cycle given
2016 // that the whole heap was collected anyway.
2017 }
2018
2019 if (retry_gc) {
2020 if (GCLocker::is_active_and_needs_gc()) {
2021 GCLocker::stall_until_clear();
2022 }
2023 }
2024 }
2025 } else {
2026 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2027 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2028
2029 // Schedule a standard evacuation pause. We're setting word_size
2030 // to 0 which means that we are not requesting a post-GC allocation.
2031 VM_G1CollectForAllocation op(0, /* word_size */
2032 gc_count_before,
2033 cause,
2034 false, /* should_initiate_conc_mark */
2035 g1_policy()->max_pause_time_ms());
2036 VMThread::execute(&op);
2037 } else {
2038 // Schedule a Full GC.
2039 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2040 VMThread::execute(&op);
2041 }
2042 }
2043 } while (retry_gc);
2044 }
2045
2046 bool G1CollectedHeap::is_in(const void* p) const {
2047 if (_hrm.reserved().contains(p)) {
2048 // Given that we know that p is in the reserved space,
2049 // heap_region_containing() should successfully
2050 // return the containing region.
2051 HeapRegion* hr = heap_region_containing(p);
2052 return hr->is_in(p);
2053 } else {
2054 return false;
2055 }
2056 }
2057
2058 #ifdef ASSERT
2059 bool G1CollectedHeap::is_in_exact(const void* p) const {
2060 bool contains = reserved_region().contains(p);
2061 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2062 if (contains && available) {
2063 return true;
2064 } else {
2065 return false;
2066 }
2067 }
2068 #endif
2069
2070 // Iteration functions.
2071
2072 // Iterates an ObjectClosure over all objects within a HeapRegion.
2073
2074 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2075 ObjectClosure* _cl;
2076 public:
2077 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2078 bool do_heap_region(HeapRegion* r) {
2079 if (!r->is_continues_humongous()) {
2080 r->object_iterate(_cl);
2081 }
2082 return false;
2083 }
2084 };
2085
2086 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2087 IterateObjectClosureRegionClosure blk(cl);
2088 heap_region_iterate(&blk);
2089 }
2090
2091 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2092 _hrm.iterate(cl);
2093 }
2094
2095 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2096 HeapRegionClaimer *hrclaimer,
2097 uint worker_id) const {
2098 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2099 }
2100
2101 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2102 HeapRegionClaimer *hrclaimer) const {
2103 _hrm.par_iterate(cl, hrclaimer, 0);
2104 }
2105
2106 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2107 _collection_set.iterate(cl);
2108 }
2109
2110 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2111 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2112 }
2113
2114 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2115 HeapRegion* hr = heap_region_containing(addr);
2116 return hr->block_start(addr);
2117 }
2118
2119 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2120 HeapRegion* hr = heap_region_containing(addr);
2121 return hr->block_size(addr);
2122 }
2123
2124 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2125 HeapRegion* hr = heap_region_containing(addr);
2126 return hr->block_is_obj(addr);
2127 }
2128
2129 bool G1CollectedHeap::supports_tlab_allocation() const {
2130 return true;
2131 }
2132
2133 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2134 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2135 }
2136
2137 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2138 return _eden.length() * HeapRegion::GrainBytes;
2139 }
2140
2141 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2142 // must be equal to the humongous object limit.
2143 size_t G1CollectedHeap::max_tlab_size() const {
2144 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2145 }
2146
2147 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2148 return _allocator->unsafe_max_tlab_alloc();
2149 }
2150
2151 size_t G1CollectedHeap::max_capacity() const {
2152 return _hrm.reserved().byte_size();
2153 }
2154
2155 jlong G1CollectedHeap::millis_since_last_gc() {
2156 // See the notes in GenCollectedHeap::millis_since_last_gc()
2157 // for more information about the implementation.
2158 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2159 _g1_policy->collection_pause_end_millis();
2160 if (ret_val < 0) {
2161 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2162 ". returning zero instead.", ret_val);
2163 return 0;
2164 }
2165 return ret_val;
2166 }
2167
2168 void G1CollectedHeap::prepare_for_verify() {
2169 _verifier->prepare_for_verify();
2170 }
2171
2172 void G1CollectedHeap::verify(VerifyOption vo) {
2173 _verifier->verify(vo);
2174 }
2175
2176 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2177 return true;
2178 }
2179
2180 const char* const* G1CollectedHeap::concurrent_phases() const {
2181 return _cmThread->concurrent_phases();
2182 }
2183
2184 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2185 return _cmThread->request_concurrent_phase(phase);
2186 }
2187
2188 class PrintRegionClosure: public HeapRegionClosure {
2189 outputStream* _st;
2190 public:
2191 PrintRegionClosure(outputStream* st) : _st(st) {}
2192 bool do_heap_region(HeapRegion* r) {
2193 r->print_on(_st);
2194 return false;
2195 }
2196 };
2197
2198 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2199 const HeapRegion* hr,
2200 const VerifyOption vo) const {
2201 switch (vo) {
2202 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2203 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2204 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2205 default: ShouldNotReachHere();
2206 }
2207 return false; // keep some compilers happy
2208 }
2209
2210 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2211 const VerifyOption vo) const {
2212 switch (vo) {
2213 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2214 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2215 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2216 default: ShouldNotReachHere();
2217 }
2218 return false; // keep some compilers happy
2219 }
2220
2221 void G1CollectedHeap::print_heap_regions() const {
2222 LogTarget(Trace, gc, heap, region) lt;
2223 if (lt.is_enabled()) {
2224 LogStream ls(lt);
2225 print_regions_on(&ls);
2226 }
2227 }
2228
2229 void G1CollectedHeap::print_on(outputStream* st) const {
2230 st->print(" %-20s", "garbage-first heap");
2231 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2232 capacity()/K, used_unlocked()/K);
2233 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2234 p2i(_hrm.reserved().start()),
2235 p2i(_hrm.reserved().end()));
2236 st->cr();
2237 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2238 uint young_regions = young_regions_count();
2239 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2240 (size_t) young_regions * HeapRegion::GrainBytes / K);
2241 uint survivor_regions = survivor_regions_count();
2242 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2243 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2244 st->cr();
2245 MetaspaceUtils::print_on(st);
2246 }
2247
2248 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2249 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2250 "HS=humongous(starts), HC=humongous(continues), "
2251 "CS=collection set, F=free, A=archive, "
2252 "TAMS=top-at-mark-start (previous, next)");
2253 PrintRegionClosure blk(st);
2254 heap_region_iterate(&blk);
2255 }
2256
2257 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2258 print_on(st);
2259
2260 // Print the per-region information.
2261 print_regions_on(st);
2262 }
2263
2264 void G1CollectedHeap::print_on_error(outputStream* st) const {
2265 this->CollectedHeap::print_on_error(st);
2266
2267 if (_cm != NULL) {
2268 st->cr();
2269 _cm->print_on_error(st);
2270 }
2271 }
2272
2273 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2274 workers()->print_worker_threads_on(st);
2275 _cmThread->print_on(st);
2276 st->cr();
2277 _cm->print_worker_threads_on(st);
2278 _cr->print_threads_on(st);
2279 _young_gen_sampling_thread->print_on(st);
2280 if (G1StringDedup::is_enabled()) {
2281 G1StringDedup::print_worker_threads_on(st);
2282 }
2283 }
2284
2285 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2286 workers()->threads_do(tc);
2287 tc->do_thread(_cmThread);
2288 _cm->threads_do(tc);
2289 _cr->threads_do(tc);
2290 tc->do_thread(_young_gen_sampling_thread);
2291 if (G1StringDedup::is_enabled()) {
2292 G1StringDedup::threads_do(tc);
2293 }
2294 }
2295
2296 void G1CollectedHeap::print_tracing_info() const {
2297 g1_rem_set()->print_summary_info();
2298 concurrent_mark()->print_summary_info();
2299 }
2300
2301 #ifndef PRODUCT
2302 // Helpful for debugging RSet issues.
2303
2304 class PrintRSetsClosure : public HeapRegionClosure {
2305 private:
2306 const char* _msg;
2307 size_t _occupied_sum;
2308
2309 public:
2310 bool do_heap_region(HeapRegion* r) {
2311 HeapRegionRemSet* hrrs = r->rem_set();
2312 size_t occupied = hrrs->occupied();
2313 _occupied_sum += occupied;
2314
2315 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2316 if (occupied == 0) {
2317 tty->print_cr(" RSet is empty");
2318 } else {
2319 hrrs->print();
2320 }
2321 tty->print_cr("----------");
2322 return false;
2323 }
2324
2325 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2326 tty->cr();
2327 tty->print_cr("========================================");
2328 tty->print_cr("%s", msg);
2329 tty->cr();
2330 }
2331
2332 ~PrintRSetsClosure() {
2333 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2334 tty->print_cr("========================================");
2335 tty->cr();
2336 }
2337 };
2338
2339 void G1CollectedHeap::print_cset_rsets() {
2340 PrintRSetsClosure cl("Printing CSet RSets");
2341 collection_set_iterate(&cl);
2342 }
2343
2344 void G1CollectedHeap::print_all_rsets() {
2345 PrintRSetsClosure cl("Printing All RSets");;
2346 heap_region_iterate(&cl);
2347 }
2348 #endif // PRODUCT
2349
2350 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2351
2352 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2353 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2354 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2355
2356 size_t eden_capacity_bytes =
2357 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2358
2359 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2360 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2361 eden_capacity_bytes, survivor_used_bytes, num_regions());
2362 }
2363
2364 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2365 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2366 stats->unused(), stats->used(), stats->region_end_waste(),
2367 stats->regions_filled(), stats->direct_allocated(),
2368 stats->failure_used(), stats->failure_waste());
2369 }
2370
2371 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2372 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2373 gc_tracer->report_gc_heap_summary(when, heap_summary);
2374
2375 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2376 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2377 }
2378
2379 G1CollectedHeap* G1CollectedHeap::heap() {
2380 CollectedHeap* heap = Universe::heap();
2381 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2382 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2383 return (G1CollectedHeap*)heap;
2384 }
2385
2386 void G1CollectedHeap::gc_prologue(bool full) {
2387 // always_do_update_barrier = false;
2388 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2389
2390 // This summary needs to be printed before incrementing total collections.
2391 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2392
2393 // Update common counters.
2394 increment_total_collections(full /* full gc */);
2395 if (full) {
2396 increment_old_marking_cycles_started();
2397 }
2398
2399 // Fill TLAB's and such
2400 double start = os::elapsedTime();
2401 accumulate_statistics_all_tlabs();
2402 ensure_parsability(true);
2403 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2404 }
2405
2406 void G1CollectedHeap::gc_epilogue(bool full) {
2407 // Update common counters.
2408 if (full) {
2409 // Update the number of full collections that have been completed.
2410 increment_old_marking_cycles_completed(false /* concurrent */);
2411 }
2412
2413 // We are at the end of the GC. Total collections has already been increased.
2414 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2415
2416 // FIXME: what is this about?
2417 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2418 // is set.
2419 #if COMPILER2_OR_JVMCI
2420 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2421 #endif
2422 // always_do_update_barrier = true;
2423
2424 double start = os::elapsedTime();
2425 resize_all_tlabs();
2426 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2427
2428 MemoryService::track_memory_usage();
2429 // We have just completed a GC. Update the soft reference
2430 // policy with the new heap occupancy
2431 Universe::update_heap_info_at_gc();
2432 }
2433
2434 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2435 uint gc_count_before,
2436 bool* succeeded,
2437 GCCause::Cause gc_cause) {
2438 assert_heap_not_locked_and_not_at_safepoint();
2439 VM_G1CollectForAllocation op(word_size,
2440 gc_count_before,
2441 gc_cause,
2442 false, /* should_initiate_conc_mark */
2443 g1_policy()->max_pause_time_ms());
2444 VMThread::execute(&op);
2445
2446 HeapWord* result = op.result();
2447 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2448 assert(result == NULL || ret_succeeded,
2449 "the result should be NULL if the VM did not succeed");
2450 *succeeded = ret_succeeded;
2451
2452 assert_heap_not_locked();
2453 return result;
2454 }
2455
2456 void G1CollectedHeap::do_concurrent_mark() {
2457 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2458 if (!_cmThread->in_progress()) {
2459 _cmThread->set_started();
2460 CGC_lock->notify();
2461 }
2462 }
2463
2464 size_t G1CollectedHeap::pending_card_num() {
2465 size_t extra_cards = 0;
2466 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2467 DirtyCardQueue& dcq = curr->dirty_card_queue();
2468 extra_cards += dcq.size();
2469 }
2470 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2471 size_t buffer_size = dcqs.buffer_size();
2472 size_t buffer_num = dcqs.completed_buffers_num();
2473
2474 return buffer_size * buffer_num + extra_cards;
2475 }
2476
2477 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2478 // We don't nominate objects with many remembered set entries, on
2479 // the assumption that such objects are likely still live.
2480 HeapRegionRemSet* rem_set = r->rem_set();
2481
2482 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2483 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2484 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2485 }
2486
2487 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2488 private:
2489 size_t _total_humongous;
2490 size_t _candidate_humongous;
2491
2492 DirtyCardQueue _dcq;
2493
2494 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2495 assert(region->is_starts_humongous(), "Must start a humongous object");
2496
2497 oop obj = oop(region->bottom());
2498
2499 // Dead objects cannot be eager reclaim candidates. Due to class
2500 // unloading it is unsafe to query their classes so we return early.
2501 if (g1h->is_obj_dead(obj, region)) {
2502 return false;
2503 }
2504
2505 // If we do not have a complete remembered set for the region, then we can
2506 // not be sure that we have all references to it.
2507 if (!region->rem_set()->is_complete()) {
2508 return false;
2509 }
2510 // Candidate selection must satisfy the following constraints
2511 // while concurrent marking is in progress:
2512 //
2513 // * In order to maintain SATB invariants, an object must not be
2514 // reclaimed if it was allocated before the start of marking and
2515 // has not had its references scanned. Such an object must have
2516 // its references (including type metadata) scanned to ensure no
2517 // live objects are missed by the marking process. Objects
2518 // allocated after the start of concurrent marking don't need to
2519 // be scanned.
2520 //
2521 // * An object must not be reclaimed if it is on the concurrent
2522 // mark stack. Objects allocated after the start of concurrent
2523 // marking are never pushed on the mark stack.
2524 //
2525 // Nominating only objects allocated after the start of concurrent
2526 // marking is sufficient to meet both constraints. This may miss
2527 // some objects that satisfy the constraints, but the marking data
2528 // structures don't support efficiently performing the needed
2529 // additional tests or scrubbing of the mark stack.
2530 //
2531 // However, we presently only nominate is_typeArray() objects.
2532 // A humongous object containing references induces remembered
2533 // set entries on other regions. In order to reclaim such an
2534 // object, those remembered sets would need to be cleaned up.
2535 //
2536 // We also treat is_typeArray() objects specially, allowing them
2537 // to be reclaimed even if allocated before the start of
2538 // concurrent mark. For this we rely on mark stack insertion to
2539 // exclude is_typeArray() objects, preventing reclaiming an object
2540 // that is in the mark stack. We also rely on the metadata for
2541 // such objects to be built-in and so ensured to be kept live.
2542 // Frequent allocation and drop of large binary blobs is an
2543 // important use case for eager reclaim, and this special handling
2544 // may reduce needed headroom.
2545
2546 return obj->is_typeArray() &&
2547 g1h->is_potential_eager_reclaim_candidate(region);
2548 }
2549
2550 public:
2551 RegisterHumongousWithInCSetFastTestClosure()
2552 : _total_humongous(0),
2553 _candidate_humongous(0),
2554 _dcq(&JavaThread::dirty_card_queue_set()) {
2555 }
2556
2557 virtual bool do_heap_region(HeapRegion* r) {
2558 if (!r->is_starts_humongous()) {
2559 return false;
2560 }
2561 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2562
2563 bool is_candidate = humongous_region_is_candidate(g1h, r);
2564 uint rindex = r->hrm_index();
2565 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2566 if (is_candidate) {
2567 _candidate_humongous++;
2568 g1h->register_humongous_region_with_cset(rindex);
2569 // Is_candidate already filters out humongous object with large remembered sets.
2570 // If we have a humongous object with a few remembered sets, we simply flush these
2571 // remembered set entries into the DCQS. That will result in automatic
2572 // re-evaluation of their remembered set entries during the following evacuation
2573 // phase.
2574 if (!r->rem_set()->is_empty()) {
2575 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2576 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2577 G1CardTable* ct = g1h->card_table();
2578 HeapRegionRemSetIterator hrrs(r->rem_set());
2579 size_t card_index;
2580 while (hrrs.has_next(card_index)) {
2581 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2582 // The remembered set might contain references to already freed
2583 // regions. Filter out such entries to avoid failing card table
2584 // verification.
2585 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2586 if (*card_ptr != G1CardTable::dirty_card_val()) {
2587 *card_ptr = G1CardTable::dirty_card_val();
2588 _dcq.enqueue(card_ptr);
2589 }
2590 }
2591 }
2592 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2593 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2594 hrrs.n_yielded(), r->rem_set()->occupied());
2595 // We should only clear the card based remembered set here as we will not
2596 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2597 // (and probably never) we do not enter this path if there are other kind of
2598 // remembered sets for this region.
2599 r->rem_set()->clear_locked(true /* only_cardset */);
2600 // Clear_locked() above sets the state to Empty. However we want to continue
2601 // collecting remembered set entries for humongous regions that were not
2602 // reclaimed.
2603 r->rem_set()->set_state_complete();
2604 }
2605 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2606 }
2607 _total_humongous++;
2608
2609 return false;
2610 }
2611
2612 size_t total_humongous() const { return _total_humongous; }
2613 size_t candidate_humongous() const { return _candidate_humongous; }
2614
2615 void flush_rem_set_entries() { _dcq.flush(); }
2616 };
2617
2618 void G1CollectedHeap::register_humongous_regions_with_cset() {
2619 if (!G1EagerReclaimHumongousObjects) {
2620 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2621 return;
2622 }
2623 double time = os::elapsed_counter();
2624
2625 // Collect reclaim candidate information and register candidates with cset.
2626 RegisterHumongousWithInCSetFastTestClosure cl;
2627 heap_region_iterate(&cl);
2628
2629 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2630 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2631 cl.total_humongous(),
2632 cl.candidate_humongous());
2633 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2634
2635 // Finally flush all remembered set entries to re-check into the global DCQS.
2636 cl.flush_rem_set_entries();
2637 }
2638
2639 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2640 public:
2641 bool do_heap_region(HeapRegion* hr) {
2642 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2643 hr->verify_rem_set();
2644 }
2645 return false;
2646 }
2647 };
2648
2649 uint G1CollectedHeap::num_task_queues() const {
2650 return _task_queues->size();
2651 }
2652
2653 #if TASKQUEUE_STATS
2654 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2655 st->print_raw_cr("GC Task Stats");
2656 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2657 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2658 }
2659
2660 void G1CollectedHeap::print_taskqueue_stats() const {
2661 if (!log_is_enabled(Trace, gc, task, stats)) {
2662 return;
2663 }
2664 Log(gc, task, stats) log;
2665 ResourceMark rm;
2666 LogStream ls(log.trace());
2667 outputStream* st = &ls;
2668
2669 print_taskqueue_stats_hdr(st);
2670
2671 TaskQueueStats totals;
2672 const uint n = num_task_queues();
2673 for (uint i = 0; i < n; ++i) {
2674 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2675 totals += task_queue(i)->stats;
2676 }
2677 st->print_raw("tot "); totals.print(st); st->cr();
2678
2679 DEBUG_ONLY(totals.verify());
2680 }
2681
2682 void G1CollectedHeap::reset_taskqueue_stats() {
2683 const uint n = num_task_queues();
2684 for (uint i = 0; i < n; ++i) {
2685 task_queue(i)->stats.reset();
2686 }
2687 }
2688 #endif // TASKQUEUE_STATS
2689
2690 void G1CollectedHeap::wait_for_root_region_scanning() {
2691 double scan_wait_start = os::elapsedTime();
2692 // We have to wait until the CM threads finish scanning the
2693 // root regions as it's the only way to ensure that all the
2694 // objects on them have been correctly scanned before we start
2695 // moving them during the GC.
2696 bool waited = _cm->root_regions()->wait_until_scan_finished();
2697 double wait_time_ms = 0.0;
2698 if (waited) {
2699 double scan_wait_end = os::elapsedTime();
2700 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2701 }
2702 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2703 }
2704
2705 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2706 private:
2707 G1HRPrinter* _hr_printer;
2708 public:
2709 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2710
2711 virtual bool do_heap_region(HeapRegion* r) {
2712 _hr_printer->cset(r);
2713 return false;
2714 }
2715 };
2716
2717 void G1CollectedHeap::start_new_collection_set() {
2718 collection_set()->start_incremental_building();
2719
2720 clear_cset_fast_test();
2721
2722 guarantee(_eden.length() == 0, "eden should have been cleared");
2723 g1_policy()->transfer_survivors_to_cset(survivor());
2724 }
2725
2726 bool
2727 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2728 assert_at_safepoint_on_vm_thread();
2729 guarantee(!is_gc_active(), "collection is not reentrant");
2730
2731 if (GCLocker::check_active_before_gc()) {
2732 return false;
2733 }
2734
2735 _gc_timer_stw->register_gc_start();
2736
2737 GCIdMark gc_id_mark;
2738 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2739
2740 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2741 ResourceMark rm;
2742
2743 g1_policy()->note_gc_start();
2744
2745 wait_for_root_region_scanning();
2746
2747 print_heap_before_gc();
2748 print_heap_regions();
2749 trace_heap_before_gc(_gc_tracer_stw);
2750
2751 _verifier->verify_region_sets_optional();
2752 _verifier->verify_dirty_young_regions();
2753
2754 // We should not be doing initial mark unless the conc mark thread is running
2755 if (!_cmThread->should_terminate()) {
2756 // This call will decide whether this pause is an initial-mark
2757 // pause. If it is, in_initial_mark_gc() will return true
2758 // for the duration of this pause.
2759 g1_policy()->decide_on_conc_mark_initiation();
2760 }
2761
2762 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2763 assert(!collector_state()->in_initial_mark_gc() ||
2764 collector_state()->in_young_only_phase(), "sanity");
2765
2766 // We also do not allow mixed GCs during marking.
2767 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2768
2769 // Record whether this pause is an initial mark. When the current
2770 // thread has completed its logging output and it's safe to signal
2771 // the CM thread, the flag's value in the policy has been reset.
2772 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2773
2774 // Inner scope for scope based logging, timers, and stats collection
2775 {
2776 EvacuationInfo evacuation_info;
2777
2778 if (collector_state()->in_initial_mark_gc()) {
2779 // We are about to start a marking cycle, so we increment the
2780 // full collection counter.
2781 increment_old_marking_cycles_started();
2782 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2783 }
2784
2785 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2786
2787 GCTraceCPUTime tcpu;
2788
2789 G1HeapVerifier::G1VerifyType verify_type;
2790 FormatBuffer<> gc_string("Pause ");
2791 if (collector_state()->in_initial_mark_gc()) {
2792 gc_string.append("Initial Mark");
2793 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2794 } else if (collector_state()->in_young_only_phase()) {
2795 gc_string.append("Young");
2796 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2797 } else {
2798 gc_string.append("Mixed");
2799 verify_type = G1HeapVerifier::G1VerifyMixed;
2800 }
2801 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2802
2803 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2804 workers()->active_workers(),
2805 Threads::number_of_non_daemon_threads());
2806 active_workers = workers()->update_active_workers(active_workers);
2807 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2808
2809 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2810 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2811
2812 G1HeapTransition heap_transition(this);
2813 size_t heap_used_bytes_before_gc = used();
2814
2815 // Don't dynamically change the number of GC threads this early. A value of
2816 // 0 is used to indicate serial work. When parallel work is done,
2817 // it will be set.
2818
2819 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2820 IsGCActiveMark x;
2821
2822 gc_prologue(false);
2823
2824 if (VerifyRememberedSets) {
2825 log_info(gc, verify)("[Verifying RemSets before GC]");
2826 VerifyRegionRemSetClosure v_cl;
2827 heap_region_iterate(&v_cl);
2828 }
2829
2830 _verifier->verify_before_gc(verify_type);
2831
2832 _verifier->check_bitmaps("GC Start");
2833
2834 #if COMPILER2_OR_JVMCI
2835 DerivedPointerTable::clear();
2836 #endif
2837
2838 // Please see comment in g1CollectedHeap.hpp and
2839 // G1CollectedHeap::ref_processing_init() to see how
2840 // reference processing currently works in G1.
2841
2842 // Enable discovery in the STW reference processor
2843 if (g1_policy()->should_process_references()) {
2844 ref_processor_stw()->enable_discovery();
2845 } else {
2846 ref_processor_stw()->disable_discovery();
2847 }
2848
2849 {
2850 // We want to temporarily turn off discovery by the
2851 // CM ref processor, if necessary, and turn it back on
2852 // on again later if we do. Using a scoped
2853 // NoRefDiscovery object will do this.
2854 NoRefDiscovery no_cm_discovery(ref_processor_cm());
2855
2856 // Forget the current alloc region (we might even choose it to be part
2857 // of the collection set!).
2858 _allocator->release_mutator_alloc_region();
2859
2860 // This timing is only used by the ergonomics to handle our pause target.
2861 // It is unclear why this should not include the full pause. We will
2862 // investigate this in CR 7178365.
2863 //
2864 // Preserving the old comment here if that helps the investigation:
2865 //
2866 // The elapsed time induced by the start time below deliberately elides
2867 // the possible verification above.
2868 double sample_start_time_sec = os::elapsedTime();
2869
2870 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2871
2872 if (collector_state()->in_initial_mark_gc()) {
2873 concurrent_mark()->pre_initial_mark();
2874 }
2875
2876 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2877
2878 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2879
2880 // Make sure the remembered sets are up to date. This needs to be
2881 // done before register_humongous_regions_with_cset(), because the
2882 // remembered sets are used there to choose eager reclaim candidates.
2883 // If the remembered sets are not up to date we might miss some
2884 // entries that need to be handled.
2885 g1_rem_set()->cleanupHRRS();
2886
2887 register_humongous_regions_with_cset();
2888
2889 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2890
2891 // We call this after finalize_cset() to
2892 // ensure that the CSet has been finalized.
2893 _cm->verify_no_cset_oops();
2894
2895 if (_hr_printer.is_active()) {
2896 G1PrintCollectionSetClosure cl(&_hr_printer);
2897 _collection_set.iterate(&cl);
2898 }
2899
2900 // Initialize the GC alloc regions.
2901 _allocator->init_gc_alloc_regions(evacuation_info);
2902
2903 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2904 pre_evacuate_collection_set();
2905
2906 // Actually do the work...
2907 evacuate_collection_set(&per_thread_states);
2908
2909 post_evacuate_collection_set(evacuation_info, &per_thread_states);
2910
2911 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2912 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2913
2914 eagerly_reclaim_humongous_regions();
2915
2916 record_obj_copy_mem_stats();
2917 _survivor_evac_stats.adjust_desired_plab_sz();
2918 _old_evac_stats.adjust_desired_plab_sz();
2919
2920 double start = os::elapsedTime();
2921 start_new_collection_set();
2922 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2923
2924 if (evacuation_failed()) {
2925 set_used(recalculate_used());
2926 if (_archive_allocator != NULL) {
2927 _archive_allocator->clear_used();
2928 }
2929 for (uint i = 0; i < ParallelGCThreads; i++) {
2930 if (_evacuation_failed_info_array[i].has_failed()) {
2931 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
2932 }
2933 }
2934 } else {
2935 // The "used" of the the collection set have already been subtracted
2936 // when they were freed. Add in the bytes evacuated.
2937 increase_used(g1_policy()->bytes_copied_during_gc());
2938 }
2939
2940 if (collector_state()->in_initial_mark_gc()) {
2941 // We have to do this before we notify the CM threads that
2942 // they can start working to make sure that all the
2943 // appropriate initialization is done on the CM object.
2944 concurrent_mark()->post_initial_mark();
2945 // Note that we don't actually trigger the CM thread at
2946 // this point. We do that later when we're sure that
2947 // the current thread has completed its logging output.
2948 }
2949
2950 allocate_dummy_regions();
2951
2952 _allocator->init_mutator_alloc_region();
2953
2954 {
2955 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2956 if (expand_bytes > 0) {
2957 size_t bytes_before = capacity();
2958 // No need for an ergo logging here,
2959 // expansion_amount() does this when it returns a value > 0.
2960 double expand_ms;
2961 if (!expand(expand_bytes, _workers, &expand_ms)) {
2962 // We failed to expand the heap. Cannot do anything about it.
2963 }
2964 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
2965 }
2966 }
2967
2968 // We redo the verification but now wrt to the new CSet which
2969 // has just got initialized after the previous CSet was freed.
2970 _cm->verify_no_cset_oops();
2971
2972 // This timing is only used by the ergonomics to handle our pause target.
2973 // It is unclear why this should not include the full pause. We will
2974 // investigate this in CR 7178365.
2975 double sample_end_time_sec = os::elapsedTime();
2976 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
2977 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
2978 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
2979
2980 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
2981 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
2982
2983 if (VerifyRememberedSets) {
2984 log_info(gc, verify)("[Verifying RemSets after GC]");
2985 VerifyRegionRemSetClosure v_cl;
2986 heap_region_iterate(&v_cl);
2987 }
2988
2989 _verifier->verify_after_gc(verify_type);
2990 _verifier->check_bitmaps("GC End");
2991
2992 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
2993 ref_processor_stw()->verify_no_references_recorded();
2994
2995 // CM reference discovery will be re-enabled if necessary.
2996 }
2997
2998 #ifdef TRACESPINNING
2999 ParallelTaskTerminator::print_termination_counts();
3000 #endif
3001
3002 gc_epilogue(false);
3003 }
3004
3005 // Print the remainder of the GC log output.
3006 if (evacuation_failed()) {
3007 log_info(gc)("To-space exhausted");
3008 }
3009
3010 g1_policy()->print_phases();
3011 heap_transition.print();
3012
3013 // It is not yet to safe to tell the concurrent mark to
3014 // start as we have some optional output below. We don't want the
3015 // output from the concurrent mark thread interfering with this
3016 // logging output either.
3017
3018 _hrm.verify_optional();
3019 _verifier->verify_region_sets_optional();
3020
3021 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3022 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3023
3024 print_heap_after_gc();
3025 print_heap_regions();
3026 trace_heap_after_gc(_gc_tracer_stw);
3027
3028 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3029 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3030 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3031 // before any GC notifications are raised.
3032 g1mm()->update_sizes();
3033
3034 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3035 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3036 _gc_timer_stw->register_gc_end();
3037 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3038 }
3039 // It should now be safe to tell the concurrent mark thread to start
3040 // without its logging output interfering with the logging output
3041 // that came from the pause.
3042
3043 if (should_start_conc_mark) {
3044 // CAUTION: after the doConcurrentMark() call below,
3045 // the concurrent marking thread(s) could be running
3046 // concurrently with us. Make sure that anything after
3047 // this point does not assume that we are the only GC thread
3048 // running. Note: of course, the actual marking work will
3049 // not start until the safepoint itself is released in
3050 // SuspendibleThreadSet::desynchronize().
3051 do_concurrent_mark();
3052 }
3053
3054 return true;
3055 }
3056
3057 void G1CollectedHeap::remove_self_forwarding_pointers() {
3058 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3059 workers()->run_task(&rsfp_task);
3060 }
3061
3062 void G1CollectedHeap::restore_after_evac_failure() {
3063 double remove_self_forwards_start = os::elapsedTime();
3064
3065 remove_self_forwarding_pointers();
3066 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3067 _preserved_marks_set.restore(&task_executor);
3068
3069 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3070 }
3071
3072 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3073 if (!_evacuation_failed) {
3074 _evacuation_failed = true;
3075 }
3076
3077 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3078 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3079 }
3080
3081 bool G1ParEvacuateFollowersClosure::offer_termination() {
3082 G1ParScanThreadState* const pss = par_scan_state();
3083 start_term_time();
3084 const bool res = terminator()->offer_termination();
3085 end_term_time();
3086 return res;
3087 }
3088
3089 void G1ParEvacuateFollowersClosure::do_void() {
3090 G1ParScanThreadState* const pss = par_scan_state();
3091 pss->trim_queue();
3092 do {
3093 pss->steal_and_trim_queue(queues());
3094 } while (!offer_termination());
3095 }
3096
3097 class G1ParTask : public AbstractGangTask {
3098 protected:
3099 G1CollectedHeap* _g1h;
3100 G1ParScanThreadStateSet* _pss;
3101 RefToScanQueueSet* _queues;
3102 G1RootProcessor* _root_processor;
3103 ParallelTaskTerminator _terminator;
3104 uint _n_workers;
3105
3106 public:
3107 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3108 : AbstractGangTask("G1 collection"),
3109 _g1h(g1h),
3110 _pss(per_thread_states),
3111 _queues(task_queues),
3112 _root_processor(root_processor),
3113 _terminator(n_workers, _queues),
3114 _n_workers(n_workers)
3115 {}
3116
3117 void work(uint worker_id) {
3118 if (worker_id >= _n_workers) return; // no work needed this round
3119
3120 double start_sec = os::elapsedTime();
3121 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3122
3123 {
3124 ResourceMark rm;
3125 HandleMark hm;
3126
3127 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3128
3129 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3130 pss->set_ref_processor(rp);
3131
3132 double start_strong_roots_sec = os::elapsedTime();
3133
3134 _root_processor->evacuate_roots(pss->closures(), worker_id);
3135
3136 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3137 // treating the nmethods visited to act as roots for concurrent marking.
3138 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3139 // objects copied by the current evacuation.
3140 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3141 pss->closures()->weak_codeblobs(),
3142 worker_id);
3143
3144 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3145
3146 double term_sec = 0.0;
3147 size_t evac_term_attempts = 0;
3148 {
3149 double start = os::elapsedTime();
3150 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3151 evac.do_void();
3152
3153 evac_term_attempts = evac.term_attempts();
3154 term_sec = evac.term_time();
3155 double elapsed_sec = os::elapsedTime() - start;
3156 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3157 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3158 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3159 }
3160
3161 assert(pss->queue_is_empty(), "should be empty");
3162
3163 if (log_is_enabled(Debug, gc, task, stats)) {
3164 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3165 size_t lab_waste;
3166 size_t lab_undo_waste;
3167 pss->waste(lab_waste, lab_undo_waste);
3168 _g1h->print_termination_stats(worker_id,
3169 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3170 strong_roots_sec * 1000.0, /* strong roots time */
3171 term_sec * 1000.0, /* evac term time */
3172 evac_term_attempts, /* evac term attempts */
3173 lab_waste, /* alloc buffer waste */
3174 lab_undo_waste /* undo waste */
3175 );
3176 }
3177
3178 // Close the inner scope so that the ResourceMark and HandleMark
3179 // destructors are executed here and are included as part of the
3180 // "GC Worker Time".
3181 }
3182 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3183 }
3184 };
3185
3186 void G1CollectedHeap::print_termination_stats_hdr() {
3187 log_debug(gc, task, stats)("GC Termination Stats");
3188 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3189 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3190 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3191 }
3192
3193 void G1CollectedHeap::print_termination_stats(uint worker_id,
3194 double elapsed_ms,
3195 double strong_roots_ms,
3196 double term_ms,
3197 size_t term_attempts,
3198 size_t alloc_buffer_waste,
3199 size_t undo_waste) const {
3200 log_debug(gc, task, stats)
3201 ("%3d %9.2f %9.2f %6.2f "
3202 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3203 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3204 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3205 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3206 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3207 alloc_buffer_waste * HeapWordSize / K,
3208 undo_waste * HeapWordSize / K);
3209 }
3210
3211 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3212 private:
3213 BoolObjectClosure* _is_alive;
3214 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3215
3216 int _initial_string_table_size;
3217 int _initial_symbol_table_size;
3218
3219 bool _process_strings;
3220 int _strings_processed;
3221 int _strings_removed;
3222
3223 bool _process_symbols;
3224 int _symbols_processed;
3225 int _symbols_removed;
3226
3227 bool _process_string_dedup;
3228
3229 public:
3230 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3231 AbstractGangTask("String/Symbol Unlinking"),
3232 _is_alive(is_alive),
3233 _dedup_closure(is_alive, NULL, false),
3234 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3235 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3236 _process_string_dedup(process_string_dedup) {
3237
3238 _initial_string_table_size = StringTable::the_table()->table_size();
3239 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3240 if (process_strings) {
3241 StringTable::clear_parallel_claimed_index();
3242 }
3243 if (process_symbols) {
3244 SymbolTable::clear_parallel_claimed_index();
3245 }
3246 }
3247
3248 ~G1StringAndSymbolCleaningTask() {
3249 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3250 "claim value %d after unlink less than initial string table size %d",
3251 StringTable::parallel_claimed_index(), _initial_string_table_size);
3252 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3253 "claim value %d after unlink less than initial symbol table size %d",
3254 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3255
3256 log_info(gc, stringtable)(
3257 "Cleaned string and symbol table, "
3258 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3259 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3260 strings_processed(), strings_removed(),
3261 symbols_processed(), symbols_removed());
3262 }
3263
3264 void work(uint worker_id) {
3265 int strings_processed = 0;
3266 int strings_removed = 0;
3267 int symbols_processed = 0;
3268 int symbols_removed = 0;
3269 if (_process_strings) {
3270 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3271 Atomic::add(strings_processed, &_strings_processed);
3272 Atomic::add(strings_removed, &_strings_removed);
3273 }
3274 if (_process_symbols) {
3275 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3276 Atomic::add(symbols_processed, &_symbols_processed);
3277 Atomic::add(symbols_removed, &_symbols_removed);
3278 }
3279 if (_process_string_dedup) {
3280 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3281 }
3282 }
3283
3284 size_t strings_processed() const { return (size_t)_strings_processed; }
3285 size_t strings_removed() const { return (size_t)_strings_removed; }
3286
3287 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3288 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3289 };
3290
3291 class G1CodeCacheUnloadingTask {
3292 private:
3293 static Monitor* _lock;
3294
3295 BoolObjectClosure* const _is_alive;
3296 const bool _unloading_occurred;
3297 const uint _num_workers;
3298
3299 // Variables used to claim nmethods.
3300 CompiledMethod* _first_nmethod;
3301 CompiledMethod* volatile _claimed_nmethod;
3302
3303 // The list of nmethods that need to be processed by the second pass.
3304 CompiledMethod* volatile _postponed_list;
3305 volatile uint _num_entered_barrier;
3306
3307 public:
3308 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3309 _is_alive(is_alive),
3310 _unloading_occurred(unloading_occurred),
3311 _num_workers(num_workers),
3312 _first_nmethod(NULL),
3313 _claimed_nmethod(NULL),
3314 _postponed_list(NULL),
3315 _num_entered_barrier(0)
3316 {
3317 CompiledMethod::increase_unloading_clock();
3318 // Get first alive nmethod
3319 CompiledMethodIterator iter = CompiledMethodIterator();
3320 if(iter.next_alive()) {
3321 _first_nmethod = iter.method();
3322 }
3323 _claimed_nmethod = _first_nmethod;
3324 }
3325
3326 ~G1CodeCacheUnloadingTask() {
3327 CodeCache::verify_clean_inline_caches();
3328
3329 CodeCache::set_needs_cache_clean(false);
3330 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3331
3332 CodeCache::verify_icholder_relocations();
3333 }
3334
3335 private:
3336 void add_to_postponed_list(CompiledMethod* nm) {
3337 CompiledMethod* old;
3338 do {
3339 old = _postponed_list;
3340 nm->set_unloading_next(old);
3341 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3342 }
3343
3344 void clean_nmethod(CompiledMethod* nm) {
3345 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3346
3347 if (postponed) {
3348 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3349 add_to_postponed_list(nm);
3350 }
3351
3352 // Mark that this thread has been cleaned/unloaded.
3353 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3354 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3355 }
3356
3357 void clean_nmethod_postponed(CompiledMethod* nm) {
3358 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3359 }
3360
3361 static const int MaxClaimNmethods = 16;
3362
3363 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3364 CompiledMethod* first;
3365 CompiledMethodIterator last;
3366
3367 do {
3368 *num_claimed_nmethods = 0;
3369
3370 first = _claimed_nmethod;
3371 last = CompiledMethodIterator(first);
3372
3373 if (first != NULL) {
3374
3375 for (int i = 0; i < MaxClaimNmethods; i++) {
3376 if (!last.next_alive()) {
3377 break;
3378 }
3379 claimed_nmethods[i] = last.method();
3380 (*num_claimed_nmethods)++;
3381 }
3382 }
3383
3384 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3385 }
3386
3387 CompiledMethod* claim_postponed_nmethod() {
3388 CompiledMethod* claim;
3389 CompiledMethod* next;
3390
3391 do {
3392 claim = _postponed_list;
3393 if (claim == NULL) {
3394 return NULL;
3395 }
3396
3397 next = claim->unloading_next();
3398
3399 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3400
3401 return claim;
3402 }
3403
3404 public:
3405 // Mark that we're done with the first pass of nmethod cleaning.
3406 void barrier_mark(uint worker_id) {
3407 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3408 _num_entered_barrier++;
3409 if (_num_entered_barrier == _num_workers) {
3410 ml.notify_all();
3411 }
3412 }
3413
3414 // See if we have to wait for the other workers to
3415 // finish their first-pass nmethod cleaning work.
3416 void barrier_wait(uint worker_id) {
3417 if (_num_entered_barrier < _num_workers) {
3418 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3419 while (_num_entered_barrier < _num_workers) {
3420 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3421 }
3422 }
3423 }
3424
3425 // Cleaning and unloading of nmethods. Some work has to be postponed
3426 // to the second pass, when we know which nmethods survive.
3427 void work_first_pass(uint worker_id) {
3428 // The first nmethods is claimed by the first worker.
3429 if (worker_id == 0 && _first_nmethod != NULL) {
3430 clean_nmethod(_first_nmethod);
3431 _first_nmethod = NULL;
3432 }
3433
3434 int num_claimed_nmethods;
3435 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3436
3437 while (true) {
3438 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3439
3440 if (num_claimed_nmethods == 0) {
3441 break;
3442 }
3443
3444 for (int i = 0; i < num_claimed_nmethods; i++) {
3445 clean_nmethod(claimed_nmethods[i]);
3446 }
3447 }
3448 }
3449
3450 void work_second_pass(uint worker_id) {
3451 CompiledMethod* nm;
3452 // Take care of postponed nmethods.
3453 while ((nm = claim_postponed_nmethod()) != NULL) {
3454 clean_nmethod_postponed(nm);
3455 }
3456 }
3457 };
3458
3459 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3460
3461 class G1KlassCleaningTask : public StackObj {
3462 BoolObjectClosure* _is_alive;
3463 volatile int _clean_klass_tree_claimed;
3464 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3465
3466 public:
3467 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3468 _is_alive(is_alive),
3469 _clean_klass_tree_claimed(0),
3470 _klass_iterator() {
3471 }
3472
3473 private:
3474 bool claim_clean_klass_tree_task() {
3475 if (_clean_klass_tree_claimed) {
3476 return false;
3477 }
3478
3479 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3480 }
3481
3482 InstanceKlass* claim_next_klass() {
3483 Klass* klass;
3484 do {
3485 klass =_klass_iterator.next_klass();
3486 } while (klass != NULL && !klass->is_instance_klass());
3487
3488 // this can be null so don't call InstanceKlass::cast
3489 return static_cast<InstanceKlass*>(klass);
3490 }
3491
3492 public:
3493
3494 void clean_klass(InstanceKlass* ik) {
3495 ik->clean_weak_instanceklass_links(_is_alive);
3496 }
3497
3498 void work() {
3499 ResourceMark rm;
3500
3501 // One worker will clean the subklass/sibling klass tree.
3502 if (claim_clean_klass_tree_task()) {
3503 Klass::clean_subklass_tree(_is_alive);
3504 }
3505
3506 // All workers will help cleaning the classes,
3507 InstanceKlass* klass;
3508 while ((klass = claim_next_klass()) != NULL) {
3509 clean_klass(klass);
3510 }
3511 }
3512 };
3513
3514 class G1ResolvedMethodCleaningTask : public StackObj {
3515 BoolObjectClosure* _is_alive;
3516 volatile int _resolved_method_task_claimed;
3517 public:
3518 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3519 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3520
3521 bool claim_resolved_method_task() {
3522 if (_resolved_method_task_claimed) {
3523 return false;
3524 }
3525 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3526 }
3527
3528 // These aren't big, one thread can do it all.
3529 void work() {
3530 if (claim_resolved_method_task()) {
3531 ResolvedMethodTable::unlink(_is_alive);
3532 }
3533 }
3534 };
3535
3536
3537 // To minimize the remark pause times, the tasks below are done in parallel.
3538 class G1ParallelCleaningTask : public AbstractGangTask {
3539 private:
3540 G1StringAndSymbolCleaningTask _string_symbol_task;
3541 G1CodeCacheUnloadingTask _code_cache_task;
3542 G1KlassCleaningTask _klass_cleaning_task;
3543 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3544
3545 public:
3546 // The constructor is run in the VMThread.
3547 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3548 AbstractGangTask("Parallel Cleaning"),
3549 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3550 _code_cache_task(num_workers, is_alive, unloading_occurred),
3551 _klass_cleaning_task(is_alive),
3552 _resolved_method_cleaning_task(is_alive) {
3553 }
3554
3555 // The parallel work done by all worker threads.
3556 void work(uint worker_id) {
3557 // Do first pass of code cache cleaning.
3558 _code_cache_task.work_first_pass(worker_id);
3559
3560 // Let the threads mark that the first pass is done.
3561 _code_cache_task.barrier_mark(worker_id);
3562
3563 // Clean the Strings and Symbols.
3564 _string_symbol_task.work(worker_id);
3565
3566 // Clean unreferenced things in the ResolvedMethodTable
3567 _resolved_method_cleaning_task.work();
3568
3569 // Wait for all workers to finish the first code cache cleaning pass.
3570 _code_cache_task.barrier_wait(worker_id);
3571
3572 // Do the second code cache cleaning work, which realize on
3573 // the liveness information gathered during the first pass.
3574 _code_cache_task.work_second_pass(worker_id);
3575
3576 // Clean all klasses that were not unloaded.
3577 _klass_cleaning_task.work();
3578 }
3579 };
3580
3581
3582 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3583 bool class_unloading_occurred) {
3584 uint n_workers = workers()->active_workers();
3585
3586 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3587 workers()->run_task(&g1_unlink_task);
3588 }
3589
3590 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3591 bool process_strings,
3592 bool process_symbols,
3593 bool process_string_dedup) {
3594 if (!process_strings && !process_symbols && !process_string_dedup) {
3595 // Nothing to clean.
3596 return;
3597 }
3598
3599 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3600 workers()->run_task(&g1_unlink_task);
3601
3602 }
3603
3604 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3605 private:
3606 DirtyCardQueueSet* _queue;
3607 G1CollectedHeap* _g1h;
3608 public:
3609 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3610 _queue(queue), _g1h(g1h) { }
3611
3612 virtual void work(uint worker_id) {
3613 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3614 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3615
3616 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3617 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3618
3619 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3620 }
3621 };
3622
3623 void G1CollectedHeap::redirty_logged_cards() {
3624 double redirty_logged_cards_start = os::elapsedTime();
3625
3626 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3627 dirty_card_queue_set().reset_for_par_iteration();
3628 workers()->run_task(&redirty_task);
3629
3630 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3631 dcq.merge_bufferlists(&dirty_card_queue_set());
3632 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3633
3634 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3635 }
3636
3637 // Weak Reference Processing support
3638
3639 // An always "is_alive" closure that is used to preserve referents.
3640 // If the object is non-null then it's alive. Used in the preservation
3641 // of referent objects that are pointed to by reference objects
3642 // discovered by the CM ref processor.
3643 class G1AlwaysAliveClosure: public BoolObjectClosure {
3644 G1CollectedHeap* _g1;
3645 public:
3646 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3647 bool do_object_b(oop p) {
3648 if (p != NULL) {
3649 return true;
3650 }
3651 return false;
3652 }
3653 };
3654
3655 bool G1STWIsAliveClosure::do_object_b(oop p) {
3656 // An object is reachable if it is outside the collection set,
3657 // or is inside and copied.
3658 return !_g1->is_in_cset(p) || p->is_forwarded();
3659 }
3660
3661 // Non Copying Keep Alive closure
3662 class G1KeepAliveClosure: public OopClosure {
3663 G1CollectedHeap* _g1;
3664 public:
3665 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3666 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3667 void do_oop(oop* p) {
3668 oop obj = *p;
3669 assert(obj != NULL, "the caller should have filtered out NULL values");
3670
3671 const InCSetState cset_state = _g1->in_cset_state(obj);
3672 if (!cset_state.is_in_cset_or_humongous()) {
3673 return;
3674 }
3675 if (cset_state.is_in_cset()) {
3676 assert( obj->is_forwarded(), "invariant" );
3677 *p = obj->forwardee();
3678 } else {
3679 assert(!obj->is_forwarded(), "invariant" );
3680 assert(cset_state.is_humongous(),
3681 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3682 _g1->set_humongous_is_live(obj);
3683 }
3684 }
3685 };
3686
3687 // Copying Keep Alive closure - can be called from both
3688 // serial and parallel code as long as different worker
3689 // threads utilize different G1ParScanThreadState instances
3690 // and different queues.
3691
3692 class G1CopyingKeepAliveClosure: public OopClosure {
3693 G1CollectedHeap* _g1h;
3694 OopClosure* _copy_non_heap_obj_cl;
3695 G1ParScanThreadState* _par_scan_state;
3696
3697 public:
3698 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3699 OopClosure* non_heap_obj_cl,
3700 G1ParScanThreadState* pss):
3701 _g1h(g1h),
3702 _copy_non_heap_obj_cl(non_heap_obj_cl),
3703 _par_scan_state(pss)
3704 {}
3705
3706 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3707 virtual void do_oop( oop* p) { do_oop_work(p); }
3708
3709 template <class T> void do_oop_work(T* p) {
3710 oop obj = RawAccess<>::oop_load(p);
3711
3712 if (_g1h->is_in_cset_or_humongous(obj)) {
3713 // If the referent object has been forwarded (either copied
3714 // to a new location or to itself in the event of an
3715 // evacuation failure) then we need to update the reference
3716 // field and, if both reference and referent are in the G1
3717 // heap, update the RSet for the referent.
3718 //
3719 // If the referent has not been forwarded then we have to keep
3720 // it alive by policy. Therefore we have copy the referent.
3721 //
3722 // If the reference field is in the G1 heap then we can push
3723 // on the PSS queue. When the queue is drained (after each
3724 // phase of reference processing) the object and it's followers
3725 // will be copied, the reference field set to point to the
3726 // new location, and the RSet updated. Otherwise we need to
3727 // use the the non-heap or metadata closures directly to copy
3728 // the referent object and update the pointer, while avoiding
3729 // updating the RSet.
3730
3731 if (_g1h->is_in_g1_reserved(p)) {
3732 _par_scan_state->push_on_queue(p);
3733 } else {
3734 assert(!Metaspace::contains((const void*)p),
3735 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3736 _copy_non_heap_obj_cl->do_oop(p);
3737 }
3738 }
3739 }
3740 };
3741
3742 // Serial drain queue closure. Called as the 'complete_gc'
3743 // closure for each discovered list in some of the
3744 // reference processing phases.
3745
3746 class G1STWDrainQueueClosure: public VoidClosure {
3747 protected:
3748 G1CollectedHeap* _g1h;
3749 G1ParScanThreadState* _par_scan_state;
3750
3751 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3752
3753 public:
3754 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3755 _g1h(g1h),
3756 _par_scan_state(pss)
3757 { }
3758
3759 void do_void() {
3760 G1ParScanThreadState* const pss = par_scan_state();
3761 pss->trim_queue();
3762 }
3763 };
3764
3765 // Parallel Reference Processing closures
3766
3767 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3768 // processing during G1 evacuation pauses.
3769
3770 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3771 private:
3772 G1CollectedHeap* _g1h;
3773 G1ParScanThreadStateSet* _pss;
3774 RefToScanQueueSet* _queues;
3775 WorkGang* _workers;
3776 uint _active_workers;
3777
3778 public:
3779 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3780 G1ParScanThreadStateSet* per_thread_states,
3781 WorkGang* workers,
3782 RefToScanQueueSet *task_queues,
3783 uint n_workers) :
3784 _g1h(g1h),
3785 _pss(per_thread_states),
3786 _queues(task_queues),
3787 _workers(workers),
3788 _active_workers(n_workers)
3789 {
3790 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3791 }
3792
3793 // Executes the given task using concurrent marking worker threads.
3794 virtual void execute(ProcessTask& task);
3795 virtual void execute(EnqueueTask& task);
3796 };
3797
3798 // Gang task for possibly parallel reference processing
3799
3800 class G1STWRefProcTaskProxy: public AbstractGangTask {
3801 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3802 ProcessTask& _proc_task;
3803 G1CollectedHeap* _g1h;
3804 G1ParScanThreadStateSet* _pss;
3805 RefToScanQueueSet* _task_queues;
3806 ParallelTaskTerminator* _terminator;
3807
3808 public:
3809 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3810 G1CollectedHeap* g1h,
3811 G1ParScanThreadStateSet* per_thread_states,
3812 RefToScanQueueSet *task_queues,
3813 ParallelTaskTerminator* terminator) :
3814 AbstractGangTask("Process reference objects in parallel"),
3815 _proc_task(proc_task),
3816 _g1h(g1h),
3817 _pss(per_thread_states),
3818 _task_queues(task_queues),
3819 _terminator(terminator)
3820 {}
3821
3822 virtual void work(uint worker_id) {
3823 // The reference processing task executed by a single worker.
3824 ResourceMark rm;
3825 HandleMark hm;
3826
3827 G1STWIsAliveClosure is_alive(_g1h);
3828
3829 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3830 pss->set_ref_processor(NULL);
3831
3832 // Keep alive closure.
3833 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3834
3835 // Complete GC closure
3836 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3837
3838 // Call the reference processing task's work routine.
3839 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3840
3841 // Note we cannot assert that the refs array is empty here as not all
3842 // of the processing tasks (specifically phase2 - pp2_work) execute
3843 // the complete_gc closure (which ordinarily would drain the queue) so
3844 // the queue may not be empty.
3845 }
3846 };
3847
3848 // Driver routine for parallel reference processing.
3849 // Creates an instance of the ref processing gang
3850 // task and has the worker threads execute it.
3851 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3852 assert(_workers != NULL, "Need parallel worker threads.");
3853
3854 ParallelTaskTerminator terminator(_active_workers, _queues);
3855 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3856
3857 _workers->run_task(&proc_task_proxy);
3858 }
3859
3860 // Gang task for parallel reference enqueueing.
3861
3862 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3863 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3864 EnqueueTask& _enq_task;
3865
3866 public:
3867 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3868 AbstractGangTask("Enqueue reference objects in parallel"),
3869 _enq_task(enq_task)
3870 { }
3871
3872 virtual void work(uint worker_id) {
3873 _enq_task.work(worker_id);
3874 }
3875 };
3876
3877 // Driver routine for parallel reference enqueueing.
3878 // Creates an instance of the ref enqueueing gang
3879 // task and has the worker threads execute it.
3880
3881 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
3882 assert(_workers != NULL, "Need parallel worker threads.");
3883
3884 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
3885
3886 _workers->run_task(&enq_task_proxy);
3887 }
3888
3889 // End of weak reference support closures
3890
3891 // Abstract task used to preserve (i.e. copy) any referent objects
3892 // that are in the collection set and are pointed to by reference
3893 // objects discovered by the CM ref processor.
3894
3895 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
3896 protected:
3897 G1CollectedHeap* _g1h;
3898 G1ParScanThreadStateSet* _pss;
3899 RefToScanQueueSet* _queues;
3900 ParallelTaskTerminator _terminator;
3901 uint _n_workers;
3902
3903 public:
3904 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
3905 AbstractGangTask("ParPreserveCMReferents"),
3906 _g1h(g1h),
3907 _pss(per_thread_states),
3908 _queues(task_queues),
3909 _terminator(workers, _queues),
3910 _n_workers(workers)
3911 {
3912 g1h->ref_processor_cm()->set_active_mt_degree(workers);
3913 }
3914
3915 void work(uint worker_id) {
3916 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
3917
3918 ResourceMark rm;
3919 HandleMark hm;
3920
3921 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3922 pss->set_ref_processor(NULL);
3923 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3924
3925 // Is alive closure
3926 G1AlwaysAliveClosure always_alive(_g1h);
3927
3928 // Copying keep alive closure. Applied to referent objects that need
3929 // to be copied.
3930 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3931
3932 ReferenceProcessor* rp = _g1h->ref_processor_cm();
3933
3934 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
3935 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
3936
3937 // limit is set using max_num_q() - which was set using ParallelGCThreads.
3938 // So this must be true - but assert just in case someone decides to
3939 // change the worker ids.
3940 assert(worker_id < limit, "sanity");
3941 assert(!rp->discovery_is_atomic(), "check this code");
3942
3943 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
3944 for (uint idx = worker_id; idx < limit; idx += stride) {
3945 DiscoveredList& ref_list = rp->discovered_refs()[idx];
3946
3947 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
3948 while (iter.has_next()) {
3949 // Since discovery is not atomic for the CM ref processor, we
3950 // can see some null referent objects.
3951 iter.load_ptrs(DEBUG_ONLY(true));
3952 oop ref = iter.obj();
3953
3954 // This will filter nulls.
3955 if (iter.is_referent_alive()) {
3956 iter.make_referent_alive();
3957 }
3958 iter.move_to_next();
3959 }
3960 }
3961
3962 // Drain the queue - which may cause stealing
3963 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
3964 drain_queue.do_void();
3965 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
3966 assert(pss->queue_is_empty(), "should be");
3967 }
3968 };
3969
3970 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
3971 // Any reference objects, in the collection set, that were 'discovered'
3972 // by the CM ref processor should have already been copied (either by
3973 // applying the external root copy closure to the discovered lists, or
3974 // by following an RSet entry).
3975 //
3976 // But some of the referents, that are in the collection set, that these
3977 // reference objects point to may not have been copied: the STW ref
3978 // processor would have seen that the reference object had already
3979 // been 'discovered' and would have skipped discovering the reference,
3980 // but would not have treated the reference object as a regular oop.
3981 // As a result the copy closure would not have been applied to the
3982 // referent object.
3983 //
3984 // We need to explicitly copy these referent objects - the references
3985 // will be processed at the end of remarking.
3986 //
3987 // We also need to do this copying before we process the reference
3988 // objects discovered by the STW ref processor in case one of these
3989 // referents points to another object which is also referenced by an
3990 // object discovered by the STW ref processor.
3991 double preserve_cm_referents_time = 0.0;
3992
3993 // To avoid spawning task when there is no work to do, check that
3994 // a concurrent cycle is active and that some references have been
3995 // discovered.
3996 if (concurrent_mark()->cm_thread()->during_cycle() &&
3997 ref_processor_cm()->has_discovered_references()) {
3998 double preserve_cm_referents_start = os::elapsedTime();
3999 uint no_of_gc_workers = workers()->active_workers();
4000 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4001 per_thread_states,
4002 no_of_gc_workers,
4003 _task_queues);
4004 workers()->run_task(&keep_cm_referents);
4005 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4006 }
4007
4008 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4009 }
4010
4011 // Weak Reference processing during an evacuation pause (part 1).
4012 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4013 double ref_proc_start = os::elapsedTime();
4014
4015 ReferenceProcessor* rp = _ref_processor_stw;
4016 assert(rp->discovery_enabled(), "should have been enabled");
4017
4018 // Closure to test whether a referent is alive.
4019 G1STWIsAliveClosure is_alive(this);
4020
4021 // Even when parallel reference processing is enabled, the processing
4022 // of JNI refs is serial and performed serially by the current thread
4023 // rather than by a worker. The following PSS will be used for processing
4024 // JNI refs.
4025
4026 // Use only a single queue for this PSS.
4027 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4028 pss->set_ref_processor(NULL);
4029 assert(pss->queue_is_empty(), "pre-condition");
4030
4031 // Keep alive closure.
4032 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4033
4034 // Serial Complete GC closure
4035 G1STWDrainQueueClosure drain_queue(this, pss);
4036
4037 // Setup the soft refs policy...
4038 rp->setup_policy(false);
4039
4040 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4041
4042 ReferenceProcessorStats stats;
4043 if (!rp->processing_is_mt()) {
4044 // Serial reference processing...
4045 stats = rp->process_discovered_references(&is_alive,
4046 &keep_alive,
4047 &drain_queue,
4048 NULL,
4049 pt);
4050 } else {
4051 uint no_of_gc_workers = workers()->active_workers();
4052
4053 // Parallel reference processing
4054 assert(no_of_gc_workers <= rp->max_num_q(),
4055 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4056 no_of_gc_workers, rp->max_num_q());
4057
4058 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4059 stats = rp->process_discovered_references(&is_alive,
4060 &keep_alive,
4061 &drain_queue,
4062 &par_task_executor,
4063 pt);
4064 }
4065
4066 _gc_tracer_stw->report_gc_reference_stats(stats);
4067
4068 // We have completed copying any necessary live referent objects.
4069 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4070
4071 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4072 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4073 }
4074
4075 // Weak Reference processing during an evacuation pause (part 2).
4076 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4077 double ref_enq_start = os::elapsedTime();
4078
4079 ReferenceProcessor* rp = _ref_processor_stw;
4080 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4081
4082 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4083
4084 // Now enqueue any remaining on the discovered lists on to
4085 // the pending list.
4086 if (!rp->processing_is_mt()) {
4087 // Serial reference processing...
4088 rp->enqueue_discovered_references(NULL, pt);
4089 } else {
4090 // Parallel reference enqueueing
4091
4092 uint n_workers = workers()->active_workers();
4093
4094 assert(n_workers <= rp->max_num_q(),
4095 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4096 n_workers, rp->max_num_q());
4097
4098 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4099 rp->enqueue_discovered_references(&par_task_executor, pt);
4100 }
4101
4102 rp->verify_no_references_recorded();
4103 assert(!rp->discovery_enabled(), "should have been disabled");
4104
4105 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4106 // ensure that it is marked in the bitmap for concurrent marking to discover.
4107 if (collector_state()->in_initial_mark_gc()) {
4108 oop pll_head = Universe::reference_pending_list();
4109 if (pll_head != NULL) {
4110 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
4111 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
4112 }
4113 }
4114
4115 // FIXME
4116 // CM's reference processing also cleans up the string and symbol tables.
4117 // Should we do that here also? We could, but it is a serial operation
4118 // and could significantly increase the pause time.
4119
4120 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4121 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4122 }
4123
4124 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4125 double merge_pss_time_start = os::elapsedTime();
4126 per_thread_states->flush();
4127 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4128 }
4129
4130 void G1CollectedHeap::pre_evacuate_collection_set() {
4131 _expand_heap_after_alloc_failure = true;
4132 _evacuation_failed = false;
4133
4134 // Disable the hot card cache.
4135 _hot_card_cache->reset_hot_cache_claimed_index();
4136 _hot_card_cache->set_use_cache(false);
4137
4138 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4139 _preserved_marks_set.assert_empty();
4140
4141 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4142
4143 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4144 if (collector_state()->in_initial_mark_gc()) {
4145 double start_clear_claimed_marks = os::elapsedTime();
4146
4147 ClassLoaderDataGraph::clear_claimed_marks();
4148
4149 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4150 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4151 }
4152 }
4153
4154 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
4155 // Should G1EvacuationFailureALot be in effect for this GC?
4156 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4157
4158 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4159
4160 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4161
4162 double start_par_time_sec = os::elapsedTime();
4163 double end_par_time_sec;
4164
4165 {
4166 const uint n_workers = workers()->active_workers();
4167 G1RootProcessor root_processor(this, n_workers);
4168 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4169
4170 print_termination_stats_hdr();
4171
4172 workers()->run_task(&g1_par_task);
4173 end_par_time_sec = os::elapsedTime();
4174
4175 // Closing the inner scope will execute the destructor
4176 // for the G1RootProcessor object. We record the current
4177 // elapsed time before closing the scope so that time
4178 // taken for the destructor is NOT included in the
4179 // reported parallel time.
4180 }
4181
4182 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4183 phase_times->record_par_time(par_time_ms);
4184
4185 double code_root_fixup_time_ms =
4186 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4187 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4188 }
4189
4190 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4191 // Process any discovered reference objects - we have
4192 // to do this _before_ we retire the GC alloc regions
4193 // as we may have to copy some 'reachable' referent
4194 // objects (and their reachable sub-graphs) that were
4195 // not copied during the pause.
4196 if (g1_policy()->should_process_references()) {
4197 preserve_cm_referents(per_thread_states);
4198 process_discovered_references(per_thread_states);
4199 } else {
4200 ref_processor_stw()->verify_no_references_recorded();
4201 }
4202
4203 G1STWIsAliveClosure is_alive(this);
4204 G1KeepAliveClosure keep_alive(this);
4205
4206 {
4207 double start = os::elapsedTime();
4208
4209 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4210
4211 double time_ms = (os::elapsedTime() - start) * 1000.0;
4212 g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4213 }
4214
4215 if (G1StringDedup::is_enabled()) {
4216 double fixup_start = os::elapsedTime();
4217
4218 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4219
4220 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4221 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4222 }
4223
4224 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4225
4226 if (evacuation_failed()) {
4227 restore_after_evac_failure();
4228
4229 // Reset the G1EvacuationFailureALot counters and flags
4230 // Note: the values are reset only when an actual
4231 // evacuation failure occurs.
4232 NOT_PRODUCT(reset_evacuation_should_fail();)
4233 }
4234
4235 _preserved_marks_set.assert_empty();
4236
4237 // Enqueue any remaining references remaining on the STW
4238 // reference processor's discovered lists. We need to do
4239 // this after the card table is cleaned (and verified) as
4240 // the act of enqueueing entries on to the pending list
4241 // will log these updates (and dirty their associated
4242 // cards). We need these updates logged to update any
4243 // RSets.
4244 if (g1_policy()->should_process_references()) {
4245 enqueue_discovered_references(per_thread_states);
4246 } else {
4247 g1_policy()->phase_times()->record_ref_enq_time(0);
4248 }
4249
4250 _allocator->release_gc_alloc_regions(evacuation_info);
4251
4252 merge_per_thread_state_info(per_thread_states);
4253
4254 // Reset and re-enable the hot card cache.
4255 // Note the counts for the cards in the regions in the
4256 // collection set are reset when the collection set is freed.
4257 _hot_card_cache->reset_hot_cache();
4258 _hot_card_cache->set_use_cache(true);
4259
4260 purge_code_root_memory();
4261
4262 redirty_logged_cards();
4263 #if COMPILER2_OR_JVMCI
4264 double start = os::elapsedTime();
4265 DerivedPointerTable::update_pointers();
4266 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4267 #endif
4268 g1_policy()->print_age_table();
4269 }
4270
4271 void G1CollectedHeap::record_obj_copy_mem_stats() {
4272 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4273
4274 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4275 create_g1_evac_summary(&_old_evac_stats));
4276 }
4277
4278 void G1CollectedHeap::free_region(HeapRegion* hr,
4279 FreeRegionList* free_list,
4280 bool skip_remset,
4281 bool skip_hot_card_cache,
4282 bool locked) {
4283 assert(!hr->is_free(), "the region should not be free");
4284 assert(!hr->is_empty(), "the region should not be empty");
4285 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4286 assert(free_list != NULL, "pre-condition");
4287
4288 if (G1VerifyBitmaps) {
4289 MemRegion mr(hr->bottom(), hr->end());
4290 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4291 }
4292
4293 // Clear the card counts for this region.
4294 // Note: we only need to do this if the region is not young
4295 // (since we don't refine cards in young regions).
4296 if (!skip_hot_card_cache && !hr->is_young()) {
4297 _hot_card_cache->reset_card_counts(hr);
4298 }
4299 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4300 _g1_policy->remset_tracker()->update_at_free(hr);
4301 free_list->add_ordered(hr);
4302 }
4303
4304 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4305 FreeRegionList* free_list) {
4306 assert(hr->is_humongous(), "this is only for humongous regions");
4307 assert(free_list != NULL, "pre-condition");
4308 hr->clear_humongous();
4309 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4310 }
4311
4312 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4313 const uint humongous_regions_removed) {
4314 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4315 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4316 _old_set.bulk_remove(old_regions_removed);
4317 _humongous_set.bulk_remove(humongous_regions_removed);
4318 }
4319
4320 }
4321
4322 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4323 assert(list != NULL, "list can't be null");
4324 if (!list->is_empty()) {
4325 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4326 _hrm.insert_list_into_free_list(list);
4327 }
4328 }
4329
4330 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4331 decrease_used(bytes);
4332 }
4333
4334 class G1FreeCollectionSetTask : public AbstractGangTask {
4335 private:
4336
4337 // Closure applied to all regions in the collection set to do work that needs to
4338 // be done serially in a single thread.
4339 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4340 private:
4341 EvacuationInfo* _evacuation_info;
4342 const size_t* _surviving_young_words;
4343
4344 // Bytes used in successfully evacuated regions before the evacuation.
4345 size_t _before_used_bytes;
4346 // Bytes used in unsucessfully evacuated regions before the evacuation
4347 size_t _after_used_bytes;
4348
4349 size_t _bytes_allocated_in_old_since_last_gc;
4350
4351 size_t _failure_used_words;
4352 size_t _failure_waste_words;
4353
4354 FreeRegionList _local_free_list;
4355 public:
4356 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4357 HeapRegionClosure(),
4358 _evacuation_info(evacuation_info),
4359 _surviving_young_words(surviving_young_words),
4360 _before_used_bytes(0),
4361 _after_used_bytes(0),
4362 _bytes_allocated_in_old_since_last_gc(0),
4363 _failure_used_words(0),
4364 _failure_waste_words(0),
4365 _local_free_list("Local Region List for CSet Freeing") {
4366 }
4367
4368 virtual bool do_heap_region(HeapRegion* r) {
4369 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4370
4371 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4372 g1h->clear_in_cset(r);
4373
4374 if (r->is_young()) {
4375 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4376 "Young index %d is wrong for region %u of type %s with %u young regions",
4377 r->young_index_in_cset(),
4378 r->hrm_index(),
4379 r->get_type_str(),
4380 g1h->collection_set()->young_region_length());
4381 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4382 r->record_surv_words_in_group(words_survived);
4383 }
4384
4385 if (!r->evacuation_failed()) {
4386 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4387 _before_used_bytes += r->used();
4388 g1h->free_region(r,
4389 &_local_free_list,
4390 true, /* skip_remset */
4391 true, /* skip_hot_card_cache */
4392 true /* locked */);
4393 } else {
4394 r->uninstall_surv_rate_group();
4395 r->set_young_index_in_cset(-1);
4396 r->set_evacuation_failed(false);
4397 // When moving a young gen region to old gen, we "allocate" that whole region
4398 // there. This is in addition to any already evacuated objects. Notify the
4399 // policy about that.
4400 // Old gen regions do not cause an additional allocation: both the objects
4401 // still in the region and the ones already moved are accounted for elsewhere.
4402 if (r->is_young()) {
4403 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4404 }
4405 // The region is now considered to be old.
4406 r->set_old();
4407 // Do some allocation statistics accounting. Regions that failed evacuation
4408 // are always made old, so there is no need to update anything in the young
4409 // gen statistics, but we need to update old gen statistics.
4410 size_t used_words = r->marked_bytes() / HeapWordSize;
4411
4412 _failure_used_words += used_words;
4413 _failure_waste_words += HeapRegion::GrainWords - used_words;
4414
4415 g1h->old_set_add(r);
4416 _after_used_bytes += r->used();
4417 }
4418 return false;
4419 }
4420
4421 void complete_work() {
4422 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4423
4424 _evacuation_info->set_regions_freed(_local_free_list.length());
4425 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4426
4427 g1h->prepend_to_freelist(&_local_free_list);
4428 g1h->decrement_summary_bytes(_before_used_bytes);
4429
4430 G1Policy* policy = g1h->g1_policy();
4431 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4432
4433 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4434 }
4435 };
4436
4437 G1CollectionSet* _collection_set;
4438 G1SerialFreeCollectionSetClosure _cl;
4439 const size_t* _surviving_young_words;
4440
4441 size_t _rs_lengths;
4442
4443 volatile jint _serial_work_claim;
4444
4445 struct WorkItem {
4446 uint region_idx;
4447 bool is_young;
4448 bool evacuation_failed;
4449
4450 WorkItem(HeapRegion* r) {
4451 region_idx = r->hrm_index();
4452 is_young = r->is_young();
4453 evacuation_failed = r->evacuation_failed();
4454 }
4455 };
4456
4457 volatile size_t _parallel_work_claim;
4458 size_t _num_work_items;
4459 WorkItem* _work_items;
4460
4461 void do_serial_work() {
4462 // Need to grab the lock to be allowed to modify the old region list.
4463 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4464 _collection_set->iterate(&_cl);
4465 }
4466
4467 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4468 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4469
4470 HeapRegion* r = g1h->region_at(region_idx);
4471 assert(!g1h->is_on_master_free_list(r), "sanity");
4472
4473 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4474
4475 if (!is_young) {
4476 g1h->_hot_card_cache->reset_card_counts(r);
4477 }
4478
4479 if (!evacuation_failed) {
4480 r->rem_set()->clear_locked();
4481 }
4482 }
4483
4484 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4485 private:
4486 size_t _cur_idx;
4487 WorkItem* _work_items;
4488 public:
4489 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4490
4491 virtual bool do_heap_region(HeapRegion* r) {
4492 _work_items[_cur_idx++] = WorkItem(r);
4493 return false;
4494 }
4495 };
4496
4497 void prepare_work() {
4498 G1PrepareFreeCollectionSetClosure cl(_work_items);
4499 _collection_set->iterate(&cl);
4500 }
4501
4502 void complete_work() {
4503 _cl.complete_work();
4504
4505 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4506 policy->record_max_rs_lengths(_rs_lengths);
4507 policy->cset_regions_freed();
4508 }
4509 public:
4510 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4511 AbstractGangTask("G1 Free Collection Set"),
4512 _cl(evacuation_info, surviving_young_words),
4513 _collection_set(collection_set),
4514 _surviving_young_words(surviving_young_words),
4515 _serial_work_claim(0),
4516 _rs_lengths(0),
4517 _parallel_work_claim(0),
4518 _num_work_items(collection_set->region_length()),
4519 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4520 prepare_work();
4521 }
4522
4523 ~G1FreeCollectionSetTask() {
4524 complete_work();
4525 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4526 }
4527
4528 // Chunk size for work distribution. The chosen value has been determined experimentally
4529 // to be a good tradeoff between overhead and achievable parallelism.
4530 static uint chunk_size() { return 32; }
4531
4532 virtual void work(uint worker_id) {
4533 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4534
4535 // Claim serial work.
4536 if (_serial_work_claim == 0) {
4537 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4538 if (value == 0) {
4539 double serial_time = os::elapsedTime();
4540 do_serial_work();
4541 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4542 }
4543 }
4544
4545 // Start parallel work.
4546 double young_time = 0.0;
4547 bool has_young_time = false;
4548 double non_young_time = 0.0;
4549 bool has_non_young_time = false;
4550
4551 while (true) {
4552 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4553 size_t cur = end - chunk_size();
4554
4555 if (cur >= _num_work_items) {
4556 break;
4557 }
4558
4559 double start_time = os::elapsedTime();
4560
4561 end = MIN2(end, _num_work_items);
4562
4563 for (; cur < end; cur++) {
4564 bool is_young = _work_items[cur].is_young;
4565
4566 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4567
4568 double end_time = os::elapsedTime();
4569 double time_taken = end_time - start_time;
4570 if (is_young) {
4571 young_time += time_taken;
4572 has_young_time = true;
4573 } else {
4574 non_young_time += time_taken;
4575 has_non_young_time = true;
4576 }
4577 start_time = end_time;
4578 }
4579 }
4580
4581 if (has_young_time) {
4582 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4583 }
4584 if (has_non_young_time) {
4585 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4586 }
4587 }
4588 };
4589
4590 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4591 _eden.clear();
4592
4593 double free_cset_start_time = os::elapsedTime();
4594
4595 {
4596 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4597 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4598
4599 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4600
4601 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4602 cl.name(),
4603 num_workers,
4604 _collection_set.region_length());
4605 workers()->run_task(&cl, num_workers);
4606 }
4607 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4608
4609 collection_set->clear();
4610 }
4611
4612 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4613 private:
4614 FreeRegionList* _free_region_list;
4615 HeapRegionSet* _proxy_set;
4616 uint _humongous_objects_reclaimed;
4617 uint _humongous_regions_reclaimed;
4618 size_t _freed_bytes;
4619 public:
4620
4621 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4622 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4623 }
4624
4625 virtual bool do_heap_region(HeapRegion* r) {
4626 if (!r->is_starts_humongous()) {
4627 return false;
4628 }
4629
4630 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4631
4632 oop obj = (oop)r->bottom();
4633 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4634
4635 // The following checks whether the humongous object is live are sufficient.
4636 // The main additional check (in addition to having a reference from the roots
4637 // or the young gen) is whether the humongous object has a remembered set entry.
4638 //
4639 // A humongous object cannot be live if there is no remembered set for it
4640 // because:
4641 // - there can be no references from within humongous starts regions referencing
4642 // the object because we never allocate other objects into them.
4643 // (I.e. there are no intra-region references that may be missed by the
4644 // remembered set)
4645 // - as soon there is a remembered set entry to the humongous starts region
4646 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4647 // until the end of a concurrent mark.
4648 //
4649 // It is not required to check whether the object has been found dead by marking
4650 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4651 // all objects allocated during that time are considered live.
4652 // SATB marking is even more conservative than the remembered set.
4653 // So if at this point in the collection there is no remembered set entry,
4654 // nobody has a reference to it.
4655 // At the start of collection we flush all refinement logs, and remembered sets
4656 // are completely up-to-date wrt to references to the humongous object.
4657 //
4658 // Other implementation considerations:
4659 // - never consider object arrays at this time because they would pose
4660 // considerable effort for cleaning up the the remembered sets. This is
4661 // required because stale remembered sets might reference locations that
4662 // are currently allocated into.
4663 uint region_idx = r->hrm_index();
4664 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4665 !r->rem_set()->is_empty()) {
4666 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",
4667 region_idx,
4668 (size_t)obj->size() * HeapWordSize,
4669 p2i(r->bottom()),
4670 r->rem_set()->occupied(),
4671 r->rem_set()->strong_code_roots_list_length(),
4672 next_bitmap->is_marked(r->bottom()),
4673 g1h->is_humongous_reclaim_candidate(region_idx),
4674 obj->is_typeArray()
4675 );
4676 return false;
4677 }
4678
4679 guarantee(obj->is_typeArray(),
4680 "Only eagerly reclaiming type arrays is supported, but the object "
4681 PTR_FORMAT " is not.", p2i(r->bottom()));
4682
4683 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",
4684 region_idx,
4685 (size_t)obj->size() * HeapWordSize,
4686 p2i(r->bottom()),
4687 r->rem_set()->occupied(),
4688 r->rem_set()->strong_code_roots_list_length(),
4689 next_bitmap->is_marked(r->bottom()),
4690 g1h->is_humongous_reclaim_candidate(region_idx),
4691 obj->is_typeArray()
4692 );
4693
4694 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4695 cm->humongous_object_eagerly_reclaimed(r);
4696 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4697 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4698 region_idx,
4699 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4700 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4701 _humongous_objects_reclaimed++;
4702 do {
4703 HeapRegion* next = g1h->next_region_in_humongous(r);
4704 _freed_bytes += r->used();
4705 r->set_containing_set(NULL);
4706 _humongous_regions_reclaimed++;
4707 g1h->free_humongous_region(r, _free_region_list);
4708 r = next;
4709 } while (r != NULL);
4710
4711 return false;
4712 }
4713
4714 uint humongous_objects_reclaimed() {
4715 return _humongous_objects_reclaimed;
4716 }
4717
4718 uint humongous_regions_reclaimed() {
4719 return _humongous_regions_reclaimed;
4720 }
4721
4722 size_t bytes_freed() const {
4723 return _freed_bytes;
4724 }
4725 };
4726
4727 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4728 assert_at_safepoint_on_vm_thread();
4729
4730 if (!G1EagerReclaimHumongousObjects ||
4731 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4732 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4733 return;
4734 }
4735
4736 double start_time = os::elapsedTime();
4737
4738 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4739
4740 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4741 heap_region_iterate(&cl);
4742
4743 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4744
4745 G1HRPrinter* hrp = hr_printer();
4746 if (hrp->is_active()) {
4747 FreeRegionListIterator iter(&local_cleanup_list);
4748 while (iter.more_available()) {
4749 HeapRegion* hr = iter.get_next();
4750 hrp->cleanup(hr);
4751 }
4752 }
4753
4754 prepend_to_freelist(&local_cleanup_list);
4755 decrement_summary_bytes(cl.bytes_freed());
4756
4757 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4758 cl.humongous_objects_reclaimed());
4759 }
4760
4761 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4762 public:
4763 virtual bool do_heap_region(HeapRegion* r) {
4764 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4765 G1CollectedHeap::heap()->clear_in_cset(r);
4766 r->set_young_index_in_cset(-1);
4767 return false;
4768 }
4769 };
4770
4771 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4772 G1AbandonCollectionSetClosure cl;
4773 collection_set->iterate(&cl);
4774
4775 collection_set->clear();
4776 collection_set->stop_incremental_building();
4777 }
4778
4779 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4780 return _allocator->is_retained_old_region(hr);
4781 }
4782
4783 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4784 _eden.add(hr);
4785 _g1_policy->set_region_eden(hr);
4786 }
4787
4788 #ifdef ASSERT
4789
4790 class NoYoungRegionsClosure: public HeapRegionClosure {
4791 private:
4792 bool _success;
4793 public:
4794 NoYoungRegionsClosure() : _success(true) { }
4795 bool do_heap_region(HeapRegion* r) {
4796 if (r->is_young()) {
4797 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4798 p2i(r->bottom()), p2i(r->end()));
4799 _success = false;
4800 }
4801 return false;
4802 }
4803 bool success() { return _success; }
4804 };
4805
4806 bool G1CollectedHeap::check_young_list_empty() {
4807 bool ret = (young_regions_count() == 0);
4808
4809 NoYoungRegionsClosure closure;
4810 heap_region_iterate(&closure);
4811 ret = ret && closure.success();
4812
4813 return ret;
4814 }
4815
4816 #endif // ASSERT
4817
4818 class TearDownRegionSetsClosure : public HeapRegionClosure {
4819 private:
4820 HeapRegionSet *_old_set;
4821
4822 public:
4823 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4824
4825 bool do_heap_region(HeapRegion* r) {
4826 if (r->is_old()) {
4827 _old_set->remove(r);
4828 } else if(r->is_young()) {
4829 r->uninstall_surv_rate_group();
4830 } else {
4831 // We ignore free regions, we'll empty the free list afterwards.
4832 // We ignore humongous regions, we're not tearing down the
4833 // humongous regions set.
4834 assert(r->is_free() || r->is_humongous(),
4835 "it cannot be another type");
4836 }
4837 return false;
4838 }
4839
4840 ~TearDownRegionSetsClosure() {
4841 assert(_old_set->is_empty(), "post-condition");
4842 }
4843 };
4844
4845 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4846 assert_at_safepoint_on_vm_thread();
4847
4848 if (!free_list_only) {
4849 TearDownRegionSetsClosure cl(&_old_set);
4850 heap_region_iterate(&cl);
4851
4852 // Note that emptying the _young_list is postponed and instead done as
4853 // the first step when rebuilding the regions sets again. The reason for
4854 // this is that during a full GC string deduplication needs to know if
4855 // a collected region was young or old when the full GC was initiated.
4856 }
4857 _hrm.remove_all_free_regions();
4858 }
4859
4860 void G1CollectedHeap::increase_used(size_t bytes) {
4861 _summary_bytes_used += bytes;
4862 }
4863
4864 void G1CollectedHeap::decrease_used(size_t bytes) {
4865 assert(_summary_bytes_used >= bytes,
4866 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4867 _summary_bytes_used, bytes);
4868 _summary_bytes_used -= bytes;
4869 }
4870
4871 void G1CollectedHeap::set_used(size_t bytes) {
4872 _summary_bytes_used = bytes;
4873 }
4874
4875 class RebuildRegionSetsClosure : public HeapRegionClosure {
4876 private:
4877 bool _free_list_only;
4878 HeapRegionSet* _old_set;
4879 HeapRegionManager* _hrm;
4880 size_t _total_used;
4881
4882 public:
4883 RebuildRegionSetsClosure(bool free_list_only,
4884 HeapRegionSet* old_set, HeapRegionManager* hrm) :
4885 _free_list_only(free_list_only),
4886 _old_set(old_set), _hrm(hrm), _total_used(0) {
4887 assert(_hrm->num_free_regions() == 0, "pre-condition");
4888 if (!free_list_only) {
4889 assert(_old_set->is_empty(), "pre-condition");
4890 }
4891 }
4892
4893 bool do_heap_region(HeapRegion* r) {
4894 // After full GC, no region should have a remembered set.
4895 r->rem_set()->clear(true);
4896 if (r->is_empty()) {
4897 // Add free regions to the free list
4898 r->set_free();
4899 _hrm->insert_into_free_list(r);
4900 } else if (!_free_list_only) {
4901
4902 if (r->is_humongous()) {
4903 // We ignore humongous regions. We left the humongous set unchanged.
4904 } else {
4905 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4906 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
4907 r->move_to_old();
4908 _old_set->add(r);
4909 }
4910 _total_used += r->used();
4911 }
4912
4913 return false;
4914 }
4915
4916 size_t total_used() {
4917 return _total_used;
4918 }
4919 };
4920
4921 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4922 assert_at_safepoint_on_vm_thread();
4923
4924 if (!free_list_only) {
4925 _eden.clear();
4926 _survivor.clear();
4927 }
4928
4929 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4930 heap_region_iterate(&cl);
4931
4932 if (!free_list_only) {
4933 set_used(cl.total_used());
4934 if (_archive_allocator != NULL) {
4935 _archive_allocator->clear_used();
4936 }
4937 }
4938 assert(used_unlocked() == recalculate_used(),
4939 "inconsistent used_unlocked(), "
4940 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4941 used_unlocked(), recalculate_used());
4942 }
4943
4944 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4945 HeapRegion* hr = heap_region_containing(p);
4946 return hr->is_in(p);
4947 }
4948
4949 // Methods for the mutator alloc region
4950
4951 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4952 bool force) {
4953 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4954 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4955 if (force || should_allocate) {
4956 HeapRegion* new_alloc_region = new_region(word_size,
4957 false /* is_old */,
4958 false /* do_expand */);
4959 if (new_alloc_region != NULL) {
4960 set_region_short_lived_locked(new_alloc_region);
4961 _hr_printer.alloc(new_alloc_region, !should_allocate);
4962 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4963 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4964 return new_alloc_region;
4965 }
4966 }
4967 return NULL;
4968 }
4969
4970 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4971 size_t allocated_bytes) {
4972 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4973 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4974
4975 collection_set()->add_eden_region(alloc_region);
4976 increase_used(allocated_bytes);
4977 _hr_printer.retire(alloc_region);
4978 // We update the eden sizes here, when the region is retired,
4979 // instead of when it's allocated, since this is the point that its
4980 // used space has been recored in _summary_bytes_used.
4981 g1mm()->update_eden_size();
4982 }
4983
4984 // Methods for the GC alloc regions
4985
4986 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4987 if (dest.is_old()) {
4988 return true;
4989 } else {
4990 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4991 }
4992 }
4993
4994 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4995 assert(FreeList_lock->owned_by_self(), "pre-condition");
4996
4997 if (!has_more_regions(dest)) {
4998 return NULL;
4999 }
5000
5001 const bool is_survivor = dest.is_young();
5002
5003 HeapRegion* new_alloc_region = new_region(word_size,
5004 !is_survivor,
5005 true /* do_expand */);
5006 if (new_alloc_region != NULL) {
5007 if (is_survivor) {
5008 new_alloc_region->set_survivor();
5009 _survivor.add(new_alloc_region);
5010 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5011 } else {
5012 new_alloc_region->set_old();
5013 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5014 }
5015 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
5016 _hr_printer.alloc(new_alloc_region);
5017 bool during_im = collector_state()->in_initial_mark_gc();
5018 new_alloc_region->note_start_of_copying(during_im);
5019 return new_alloc_region;
5020 }
5021 return NULL;
5022 }
5023
5024 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5025 size_t allocated_bytes,
5026 InCSetState dest) {
5027 bool during_im = collector_state()->in_initial_mark_gc();
5028 alloc_region->note_end_of_copying(during_im);
5029 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5030 if (dest.is_old()) {
5031 _old_set.add(alloc_region);
5032 }
5033 _hr_printer.retire(alloc_region);
5034 }
5035
5036 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5037 bool expanded = false;
5038 uint index = _hrm.find_highest_free(&expanded);
5039
5040 if (index != G1_NO_HRM_INDEX) {
5041 if (expanded) {
5042 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5043 HeapRegion::GrainWords * HeapWordSize);
5044 }
5045 _hrm.allocate_free_regions_starting_at(index, 1);
5046 return region_at(index);
5047 }
5048 return NULL;
5049 }
5050
5051 // Optimized nmethod scanning
5052
5053 class RegisterNMethodOopClosure: public OopClosure {
5054 G1CollectedHeap* _g1h;
5055 nmethod* _nm;
5056
5057 template <class T> void do_oop_work(T* p) {
5058 T heap_oop = RawAccess<>::oop_load(p);
5059 if (!CompressedOops::is_null(heap_oop)) {
5060 oop obj = CompressedOops::decode_not_null(heap_oop);
5061 HeapRegion* hr = _g1h->heap_region_containing(obj);
5062 assert(!hr->is_continues_humongous(),
5063 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5064 " starting at " HR_FORMAT,
5065 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5066
5067 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5068 hr->add_strong_code_root_locked(_nm);
5069 }
5070 }
5071
5072 public:
5073 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5074 _g1h(g1h), _nm(nm) {}
5075
5076 void do_oop(oop* p) { do_oop_work(p); }
5077 void do_oop(narrowOop* p) { do_oop_work(p); }
5078 };
5079
5080 class UnregisterNMethodOopClosure: public OopClosure {
5081 G1CollectedHeap* _g1h;
5082 nmethod* _nm;
5083
5084 template <class T> void do_oop_work(T* p) {
5085 T heap_oop = RawAccess<>::oop_load(p);
5086 if (!CompressedOops::is_null(heap_oop)) {
5087 oop obj = CompressedOops::decode_not_null(heap_oop);
5088 HeapRegion* hr = _g1h->heap_region_containing(obj);
5089 assert(!hr->is_continues_humongous(),
5090 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5091 " starting at " HR_FORMAT,
5092 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5093
5094 hr->remove_strong_code_root(_nm);
5095 }
5096 }
5097
5098 public:
5099 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5100 _g1h(g1h), _nm(nm) {}
5101
5102 void do_oop(oop* p) { do_oop_work(p); }
5103 void do_oop(narrowOop* p) { do_oop_work(p); }
5104 };
5105
5106 // Returns true if the reference points to an object that
5107 // can move in an incremental collection.
5108 bool G1CollectedHeap::is_scavengable(oop obj) {
5109 HeapRegion* hr = heap_region_containing(obj);
5110 return !hr->is_pinned();
5111 }
5112
5113 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5114 guarantee(nm != NULL, "sanity");
5115 RegisterNMethodOopClosure reg_cl(this, nm);
5116 nm->oops_do(®_cl);
5117 }
5118
5119 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5120 guarantee(nm != NULL, "sanity");
5121 UnregisterNMethodOopClosure reg_cl(this, nm);
5122 nm->oops_do(®_cl, true);
5123 }
5124
5125 void G1CollectedHeap::purge_code_root_memory() {
5126 double purge_start = os::elapsedTime();
5127 G1CodeRootSet::purge();
5128 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5129 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5130 }
5131
5132 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5133 G1CollectedHeap* _g1h;
5134
5135 public:
5136 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5137 _g1h(g1h) {}
5138
5139 void do_code_blob(CodeBlob* cb) {
5140 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5141 if (nm == NULL) {
5142 return;
5143 }
5144
5145 if (ScavengeRootsInCode) {
5146 _g1h->register_nmethod(nm);
5147 }
5148 }
5149 };
5150
5151 void G1CollectedHeap::rebuild_strong_code_roots() {
5152 RebuildStrongCodeRootClosure blob_cl(this);
5153 CodeCache::blobs_do(&blob_cl);
5154 }
5155
5156 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5157 GrowableArray<GCMemoryManager*> memory_managers(2);
5158 memory_managers.append(&_memory_manager);
5159 memory_managers.append(&_full_gc_memory_manager);
5160 return memory_managers;
5161 }
5162
5163 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5164 GrowableArray<MemoryPool*> memory_pools(3);
5165 memory_pools.append(_eden_pool);
5166 memory_pools.append(_survivor_pool);
5167 memory_pools.append(_old_pool);
5168 return memory_pools;
5169 }