1 /*
2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1BarrierSet.hpp"
33 #include "gc/g1/g1CollectedHeap.inline.hpp"
34 #include "gc/g1/g1CollectionSet.hpp"
35 #include "gc/g1/g1CollectorPolicy.hpp"
36 #include "gc/g1/g1CollectorState.hpp"
37 #include "gc/g1/g1ConcurrentRefine.hpp"
38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1MemoryPool.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1StringDedup.hpp"
56 #include "gc/g1/g1ThreadLocalData.hpp"
57 #include "gc/g1/g1YCTypes.hpp"
58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
59 #include "gc/g1/heapRegion.inline.hpp"
60 #include "gc/g1/heapRegionRemSet.hpp"
61 #include "gc/g1/heapRegionSet.inline.hpp"
62 #include "gc/g1/vm_operations_g1.hpp"
63 #include "gc/shared/adaptiveSizePolicy.hpp"
64 #include "gc/shared/gcHeapSummary.hpp"
65 #include "gc/shared/gcId.hpp"
66 #include "gc/shared/gcLocker.hpp"
67 #include "gc/shared/gcTimer.hpp"
68 #include "gc/shared/gcTrace.hpp"
69 #include "gc/shared/gcTraceTime.inline.hpp"
70 #include "gc/shared/generationSpec.hpp"
71 #include "gc/shared/isGCActiveMark.hpp"
72 #include "gc/shared/oopStorageParState.hpp"
73 #include "gc/shared/preservedMarks.inline.hpp"
74 #include "gc/shared/suspendibleThreadSet.hpp"
75 #include "gc/shared/referenceProcessor.inline.hpp"
76 #include "gc/shared/taskqueue.inline.hpp"
77 #include "gc/shared/weakProcessor.hpp"
78 #include "logging/log.hpp"
79 #include "memory/allocation.hpp"
80 #include "memory/iterator.hpp"
81 #include "memory/resourceArea.hpp"
82 #include "oops/access.inline.hpp"
83 #include "oops/compressedOops.inline.hpp"
84 #include "oops/oop.inline.hpp"
85 #include "prims/resolvedMethodTable.hpp"
86 #include "runtime/atomic.hpp"
87 #include "runtime/flags/flagSetting.hpp"
88 #include "runtime/handles.inline.hpp"
89 #include "runtime/init.hpp"
90 #include "runtime/orderAccess.inline.hpp"
91 #include "runtime/threadSMR.hpp"
92 #include "runtime/vmThread.hpp"
93 #include "utilities/align.hpp"
94 #include "utilities/globalDefinitions.hpp"
95 #include "utilities/stack.inline.hpp"
96
97 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
98
99 // INVARIANTS/NOTES
100 //
101 // All allocation activity covered by the G1CollectedHeap interface is
102 // serialized by acquiring the HeapLock. This happens in mem_allocate
103 // and allocate_new_tlab, which are the "entry" points to the
104 // allocation code from the rest of the JVM. (Note that this does not
105 // apply to TLAB allocation, which is not part of this interface: it
106 // is done by clients of this interface.)
107
108 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
109 private:
110 size_t _num_dirtied;
111 G1CollectedHeap* _g1h;
112 G1CardTable* _g1_ct;
113
114 HeapRegion* region_for_card(jbyte* card_ptr) const {
115 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
116 }
117
118 bool will_become_free(HeapRegion* hr) const {
119 // A region will be freed by free_collection_set if the region is in the
120 // collection set and has not had an evacuation failure.
121 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
122 }
123
124 public:
125 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
126 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
127
128 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
129 HeapRegion* hr = region_for_card(card_ptr);
130
131 // Should only dirty cards in regions that won't be freed.
132 if (!will_become_free(hr)) {
133 *card_ptr = G1CardTable::dirty_card_val();
134 _num_dirtied++;
135 }
136
137 return true;
138 }
139
140 size_t num_dirtied() const { return _num_dirtied; }
141 };
142
143
144 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
145 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
146 }
147
148 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
149 // The from card cache is not the memory that is actually committed. So we cannot
150 // take advantage of the zero_filled parameter.
151 reset_from_card_cache(start_idx, num_regions);
152 }
153
154
155 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
156 MemRegion mr) {
157 return new HeapRegion(hrs_index, bot(), mr);
158 }
159
160 // Private methods.
161
162 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
163 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
164 "the only time we use this to allocate a humongous region is "
165 "when we are allocating a single humongous region");
166
167 HeapRegion* res = _hrm.allocate_free_region(is_old);
168
169 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
170 // Currently, only attempts to allocate GC alloc regions set
171 // do_expand to true. So, we should only reach here during a
172 // safepoint. If this assumption changes we might have to
173 // reconsider the use of _expand_heap_after_alloc_failure.
174 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
175
176 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
177 word_size * HeapWordSize);
178
179 if (expand(word_size * HeapWordSize)) {
180 // Given that expand() succeeded in expanding the heap, and we
181 // always expand the heap by an amount aligned to the heap
182 // region size, the free list should in theory not be empty.
183 // In either case allocate_free_region() will check for NULL.
184 res = _hrm.allocate_free_region(is_old);
185 } else {
186 _expand_heap_after_alloc_failure = false;
187 }
188 }
189 return res;
190 }
191
192 HeapWord*
193 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
194 uint num_regions,
195 size_t word_size) {
196 assert(first != G1_NO_HRM_INDEX, "pre-condition");
197 assert(is_humongous(word_size), "word_size should be humongous");
198 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
199
200 // Index of last region in the series.
201 uint last = first + num_regions - 1;
202
203 // We need to initialize the region(s) we just discovered. This is
204 // a bit tricky given that it can happen concurrently with
205 // refinement threads refining cards on these regions and
206 // potentially wanting to refine the BOT as they are scanning
207 // those cards (this can happen shortly after a cleanup; see CR
208 // 6991377). So we have to set up the region(s) carefully and in
209 // a specific order.
210
211 // The word size sum of all the regions we will allocate.
212 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
213 assert(word_size <= word_size_sum, "sanity");
214
215 // This will be the "starts humongous" region.
216 HeapRegion* first_hr = region_at(first);
217 // The header of the new object will be placed at the bottom of
218 // the first region.
219 HeapWord* new_obj = first_hr->bottom();
220 // This will be the new top of the new object.
221 HeapWord* obj_top = new_obj + word_size;
222
223 // First, we need to zero the header of the space that we will be
224 // allocating. When we update top further down, some refinement
225 // threads might try to scan the region. By zeroing the header we
226 // ensure that any thread that will try to scan the region will
227 // come across the zero klass word and bail out.
228 //
229 // NOTE: It would not have been correct to have used
230 // CollectedHeap::fill_with_object() and make the space look like
231 // an int array. The thread that is doing the allocation will
232 // later update the object header to a potentially different array
233 // type and, for a very short period of time, the klass and length
234 // fields will be inconsistent. This could cause a refinement
235 // thread to calculate the object size incorrectly.
236 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
237
238 // Next, pad out the unused tail of the last region with filler
239 // objects, for improved usage accounting.
240 // How many words we use for filler objects.
241 size_t word_fill_size = word_size_sum - word_size;
242
243 // How many words memory we "waste" which cannot hold a filler object.
244 size_t words_not_fillable = 0;
245
246 if (word_fill_size >= min_fill_size()) {
247 fill_with_objects(obj_top, word_fill_size);
248 } else if (word_fill_size > 0) {
249 // We have space to fill, but we cannot fit an object there.
250 words_not_fillable = word_fill_size;
251 word_fill_size = 0;
252 }
253
254 // We will set up the first region as "starts humongous". This
255 // will also update the BOT covering all the regions to reflect
256 // that there is a single object that starts at the bottom of the
257 // first region.
258 first_hr->set_starts_humongous(obj_top, word_fill_size);
259 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
260 // Then, if there are any, we will set up the "continues
261 // humongous" regions.
262 HeapRegion* hr = NULL;
263 for (uint i = first + 1; i <= last; ++i) {
264 hr = region_at(i);
265 hr->set_continues_humongous(first_hr);
266 _g1_policy->remset_tracker()->update_at_allocate(hr);
267 }
268
269 // Up to this point no concurrent thread would have been able to
270 // do any scanning on any region in this series. All the top
271 // fields still point to bottom, so the intersection between
272 // [bottom,top] and [card_start,card_end] will be empty. Before we
273 // update the top fields, we'll do a storestore to make sure that
274 // no thread sees the update to top before the zeroing of the
275 // object header and the BOT initialization.
276 OrderAccess::storestore();
277
278 // Now, we will update the top fields of the "continues humongous"
279 // regions except the last one.
280 for (uint i = first; i < last; ++i) {
281 hr = region_at(i);
282 hr->set_top(hr->end());
283 }
284
285 hr = region_at(last);
286 // If we cannot fit a filler object, we must set top to the end
287 // of the humongous object, otherwise we cannot iterate the heap
288 // and the BOT will not be complete.
289 hr->set_top(hr->end() - words_not_fillable);
290
291 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
292 "obj_top should be in last region");
293
294 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
295
296 assert(words_not_fillable == 0 ||
297 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
298 "Miscalculation in humongous allocation");
299
300 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
301
302 for (uint i = first; i <= last; ++i) {
303 hr = region_at(i);
304 _humongous_set.add(hr);
305 _hr_printer.alloc(hr);
306 }
307
308 return new_obj;
309 }
310
311 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
312 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
313 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
314 }
315
316 // If could fit into free regions w/o expansion, try.
317 // Otherwise, if can expand, do so.
318 // Otherwise, if using ex regions might help, try with ex given back.
319 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
320 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
321
322 _verifier->verify_region_sets_optional();
323
324 uint first = G1_NO_HRM_INDEX;
325 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
326
327 if (obj_regions == 1) {
328 // Only one region to allocate, try to use a fast path by directly allocating
329 // from the free lists. Do not try to expand here, we will potentially do that
330 // later.
331 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
332 if (hr != NULL) {
333 first = hr->hrm_index();
334 }
335 } else {
336 // Policy: Try only empty regions (i.e. already committed first). Maybe we
337 // are lucky enough to find some.
338 first = _hrm.find_contiguous_only_empty(obj_regions);
339 if (first != G1_NO_HRM_INDEX) {
340 _hrm.allocate_free_regions_starting_at(first, obj_regions);
341 }
342 }
343
344 if (first == G1_NO_HRM_INDEX) {
345 // Policy: We could not find enough regions for the humongous object in the
346 // free list. Look through the heap to find a mix of free and uncommitted regions.
347 // If so, try expansion.
348 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
349 if (first != G1_NO_HRM_INDEX) {
350 // We found something. Make sure these regions are committed, i.e. expand
351 // the heap. Alternatively we could do a defragmentation GC.
352 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
353 word_size * HeapWordSize);
354
355 _hrm.expand_at(first, obj_regions, workers());
356 g1_policy()->record_new_heap_size(num_regions());
357
358 #ifdef ASSERT
359 for (uint i = first; i < first + obj_regions; ++i) {
360 HeapRegion* hr = region_at(i);
361 assert(hr->is_free(), "sanity");
362 assert(hr->is_empty(), "sanity");
363 assert(is_on_master_free_list(hr), "sanity");
364 }
365 #endif
366 _hrm.allocate_free_regions_starting_at(first, obj_regions);
367 } else {
368 // Policy: Potentially trigger a defragmentation GC.
369 }
370 }
371
372 HeapWord* result = NULL;
373 if (first != G1_NO_HRM_INDEX) {
374 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
375 assert(result != NULL, "it should always return a valid result");
376
377 // A successful humongous object allocation changes the used space
378 // information of the old generation so we need to recalculate the
379 // sizes and update the jstat counters here.
380 g1mm()->update_sizes();
381 }
382
383 _verifier->verify_region_sets_optional();
384
385 return result;
386 }
387
388 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
389 size_t requested_size,
390 size_t* actual_size) {
391 assert_heap_not_locked_and_not_at_safepoint();
392 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
393
394 return attempt_allocation(min_size, requested_size, actual_size);
395 }
396
397 HeapWord*
398 G1CollectedHeap::mem_allocate(size_t word_size,
399 bool* gc_overhead_limit_was_exceeded) {
400 assert_heap_not_locked_and_not_at_safepoint();
401
402 if (is_humongous(word_size)) {
403 return attempt_allocation_humongous(word_size);
404 }
405 size_t dummy = 0;
406 return attempt_allocation(word_size, word_size, &dummy);
407 }
408
409 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
410 ResourceMark rm; // For retrieving the thread names in log messages.
411
412 // Make sure you read the note in attempt_allocation_humongous().
413
414 assert_heap_not_locked_and_not_at_safepoint();
415 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
416 "be called for humongous allocation requests");
417
418 // We should only get here after the first-level allocation attempt
419 // (attempt_allocation()) failed to allocate.
420
421 // We will loop until a) we manage to successfully perform the
422 // allocation or b) we successfully schedule a collection which
423 // fails to perform the allocation. b) is the only case when we'll
424 // return NULL.
425 HeapWord* result = NULL;
426 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
427 bool should_try_gc;
428 uint gc_count_before;
429
430 {
431 MutexLockerEx x(Heap_lock);
432 result = _allocator->attempt_allocation_locked(word_size);
433 if (result != NULL) {
434 return result;
435 }
436
437 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
438 // This is different to when only GCLocker::needs_gc() is set: try to avoid
439 // waiting because the GCLocker is active to not wait too long.
440 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
441 // No need for an ergo message here, can_expand_young_list() does this when
442 // it returns true.
443 result = _allocator->attempt_allocation_force(word_size);
444 if (result != NULL) {
445 return result;
446 }
447 }
448 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
449 // the GCLocker initiated GC has been performed and then retry. This includes
450 // the case when the GC Locker is not active but has not been performed.
451 should_try_gc = !GCLocker::needs_gc();
452 // Read the GC count while still holding the Heap_lock.
453 gc_count_before = total_collections();
454 }
455
456 if (should_try_gc) {
457 bool succeeded;
458 result = do_collection_pause(word_size, gc_count_before, &succeeded,
459 GCCause::_g1_inc_collection_pause);
460 if (result != NULL) {
461 assert(succeeded, "only way to get back a non-NULL result");
462 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
463 Thread::current()->name(), p2i(result));
464 return result;
465 }
466
467 if (succeeded) {
468 // We successfully scheduled a collection which failed to allocate. No
469 // point in trying to allocate further. We'll just return NULL.
470 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
471 SIZE_FORMAT " words", Thread::current()->name(), word_size);
472 return NULL;
473 }
474 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
475 Thread::current()->name(), word_size);
476 } else {
477 // Failed to schedule a collection.
478 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
479 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
480 SIZE_FORMAT " words", Thread::current()->name(), word_size);
481 return NULL;
482 }
483 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
484 // The GCLocker is either active or the GCLocker initiated
485 // GC has not yet been performed. Stall until it is and
486 // then retry the allocation.
487 GCLocker::stall_until_clear();
488 gclocker_retry_count += 1;
489 }
490
491 // We can reach here if we were unsuccessful in scheduling a
492 // collection (because another thread beat us to it) or if we were
493 // stalled due to the GC locker. In either can we should retry the
494 // allocation attempt in case another thread successfully
495 // performed a collection and reclaimed enough space. We do the
496 // first attempt (without holding the Heap_lock) here and the
497 // follow-on attempt will be at the start of the next loop
498 // iteration (after taking the Heap_lock).
499 size_t dummy = 0;
500 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
501 if (result != NULL) {
502 return result;
503 }
504
505 // Give a warning if we seem to be looping forever.
506 if ((QueuedAllocationWarningCount > 0) &&
507 (try_count % QueuedAllocationWarningCount == 0)) {
508 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
509 Thread::current()->name(), try_count, word_size);
510 }
511 }
512
513 ShouldNotReachHere();
514 return NULL;
515 }
516
517 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
518 assert_at_safepoint_on_vm_thread();
519 if (_archive_allocator == NULL) {
520 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
521 }
522 }
523
524 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
525 // Allocations in archive regions cannot be of a size that would be considered
526 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
527 // may be different at archive-restore time.
528 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
529 }
530
531 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
532 assert_at_safepoint_on_vm_thread();
533 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
534 if (is_archive_alloc_too_large(word_size)) {
535 return NULL;
536 }
537 return _archive_allocator->archive_mem_allocate(word_size);
538 }
539
540 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
541 size_t end_alignment_in_bytes) {
542 assert_at_safepoint_on_vm_thread();
543 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
544
545 // Call complete_archive to do the real work, filling in the MemRegion
546 // array with the archive regions.
547 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
548 delete _archive_allocator;
549 _archive_allocator = NULL;
550 }
551
552 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
553 assert(ranges != NULL, "MemRegion array NULL");
554 assert(count != 0, "No MemRegions provided");
555 MemRegion reserved = _hrm.reserved();
556 for (size_t i = 0; i < count; i++) {
557 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
558 return false;
559 }
560 }
561 return true;
562 }
563
564 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
565 size_t count,
566 bool open) {
567 assert(!is_init_completed(), "Expect to be called at JVM init time");
568 assert(ranges != NULL, "MemRegion array NULL");
569 assert(count != 0, "No MemRegions provided");
570 MutexLockerEx x(Heap_lock);
571
572 MemRegion reserved = _hrm.reserved();
573 HeapWord* prev_last_addr = NULL;
574 HeapRegion* prev_last_region = NULL;
575
576 // Temporarily disable pretouching of heap pages. This interface is used
577 // when mmap'ing archived heap data in, so pre-touching is wasted.
578 FlagSetting fs(AlwaysPreTouch, false);
579
580 // Enable archive object checking used by G1MarkSweep. We have to let it know
581 // about each archive range, so that objects in those ranges aren't marked.
582 G1ArchiveAllocator::enable_archive_object_check();
583
584 // For each specified MemRegion range, allocate the corresponding G1
585 // regions and mark them as archive regions. We expect the ranges
586 // in ascending starting address order, without overlap.
587 for (size_t i = 0; i < count; i++) {
588 MemRegion curr_range = ranges[i];
589 HeapWord* start_address = curr_range.start();
590 size_t word_size = curr_range.word_size();
591 HeapWord* last_address = curr_range.last();
592 size_t commits = 0;
593
594 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
595 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
596 p2i(start_address), p2i(last_address));
597 guarantee(start_address > prev_last_addr,
598 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
599 p2i(start_address), p2i(prev_last_addr));
600 prev_last_addr = last_address;
601
602 // Check for ranges that start in the same G1 region in which the previous
603 // range ended, and adjust the start address so we don't try to allocate
604 // the same region again. If the current range is entirely within that
605 // region, skip it, just adjusting the recorded top.
606 HeapRegion* start_region = _hrm.addr_to_region(start_address);
607 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
608 start_address = start_region->end();
609 if (start_address > last_address) {
610 increase_used(word_size * HeapWordSize);
611 start_region->set_top(last_address + 1);
612 continue;
613 }
614 start_region->set_top(start_address);
615 curr_range = MemRegion(start_address, last_address + 1);
616 start_region = _hrm.addr_to_region(start_address);
617 }
618
619 // Perform the actual region allocation, exiting if it fails.
620 // Then note how much new space we have allocated.
621 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
622 return false;
623 }
624 increase_used(word_size * HeapWordSize);
625 if (commits != 0) {
626 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
627 HeapRegion::GrainWords * HeapWordSize * commits);
628
629 }
630
631 // Mark each G1 region touched by the range as archive, add it to
632 // the old set, and set top.
633 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
634 HeapRegion* last_region = _hrm.addr_to_region(last_address);
635 prev_last_region = last_region;
636
637 while (curr_region != NULL) {
638 assert(curr_region->is_empty() && !curr_region->is_pinned(),
639 "Region already in use (index %u)", curr_region->hrm_index());
640 if (open) {
641 curr_region->set_open_archive();
642 } else {
643 curr_region->set_closed_archive();
644 }
645 _hr_printer.alloc(curr_region);
646 _old_set.add(curr_region);
647 HeapWord* top;
648 HeapRegion* next_region;
649 if (curr_region != last_region) {
650 top = curr_region->end();
651 next_region = _hrm.next_region_in_heap(curr_region);
652 } else {
653 top = last_address + 1;
654 next_region = NULL;
655 }
656 curr_region->set_top(top);
657 curr_region->set_first_dead(top);
658 curr_region->set_end_of_live(top);
659 curr_region = next_region;
660 }
661
662 // Notify mark-sweep of the archive
663 G1ArchiveAllocator::set_range_archive(curr_range, open);
664 }
665 return true;
666 }
667
668 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
669 assert(!is_init_completed(), "Expect to be called at JVM init time");
670 assert(ranges != NULL, "MemRegion array NULL");
671 assert(count != 0, "No MemRegions provided");
672 MemRegion reserved = _hrm.reserved();
673 HeapWord *prev_last_addr = NULL;
674 HeapRegion* prev_last_region = NULL;
675
676 // For each MemRegion, create filler objects, if needed, in the G1 regions
677 // that contain the address range. The address range actually within the
678 // MemRegion will not be modified. That is assumed to have been initialized
679 // elsewhere, probably via an mmap of archived heap data.
680 MutexLockerEx x(Heap_lock);
681 for (size_t i = 0; i < count; i++) {
682 HeapWord* start_address = ranges[i].start();
683 HeapWord* last_address = ranges[i].last();
684
685 assert(reserved.contains(start_address) && reserved.contains(last_address),
686 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
687 p2i(start_address), p2i(last_address));
688 assert(start_address > prev_last_addr,
689 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
690 p2i(start_address), p2i(prev_last_addr));
691
692 HeapRegion* start_region = _hrm.addr_to_region(start_address);
693 HeapRegion* last_region = _hrm.addr_to_region(last_address);
694 HeapWord* bottom_address = start_region->bottom();
695
696 // Check for a range beginning in the same region in which the
697 // previous one ended.
698 if (start_region == prev_last_region) {
699 bottom_address = prev_last_addr + 1;
700 }
701
702 // Verify that the regions were all marked as archive regions by
703 // alloc_archive_regions.
704 HeapRegion* curr_region = start_region;
705 while (curr_region != NULL) {
706 guarantee(curr_region->is_archive(),
707 "Expected archive region at index %u", curr_region->hrm_index());
708 if (curr_region != last_region) {
709 curr_region = _hrm.next_region_in_heap(curr_region);
710 } else {
711 curr_region = NULL;
712 }
713 }
714
715 prev_last_addr = last_address;
716 prev_last_region = last_region;
717
718 // Fill the memory below the allocated range with dummy object(s),
719 // if the region bottom does not match the range start, or if the previous
720 // range ended within the same G1 region, and there is a gap.
721 if (start_address != bottom_address) {
722 size_t fill_size = pointer_delta(start_address, bottom_address);
723 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
724 increase_used(fill_size * HeapWordSize);
725 }
726 }
727 }
728
729 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
730 size_t desired_word_size,
731 size_t* actual_word_size) {
732 assert_heap_not_locked_and_not_at_safepoint();
733 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
734 "be called for humongous allocation requests");
735
736 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
737
738 if (result == NULL) {
739 *actual_word_size = desired_word_size;
740 result = attempt_allocation_slow(desired_word_size);
741 }
742
743 assert_heap_not_locked();
744 if (result != NULL) {
745 assert(*actual_word_size != 0, "Actual size must have been set here");
746 dirty_young_block(result, *actual_word_size);
747 } else {
748 *actual_word_size = 0;
749 }
750
751 return result;
752 }
753
754 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
755 assert(!is_init_completed(), "Expect to be called at JVM init time");
756 assert(ranges != NULL, "MemRegion array NULL");
757 assert(count != 0, "No MemRegions provided");
758 MemRegion reserved = _hrm.reserved();
759 HeapWord* prev_last_addr = NULL;
760 HeapRegion* prev_last_region = NULL;
761 size_t size_used = 0;
762 size_t uncommitted_regions = 0;
763
764 // For each Memregion, free the G1 regions that constitute it, and
765 // notify mark-sweep that the range is no longer to be considered 'archive.'
766 MutexLockerEx x(Heap_lock);
767 for (size_t i = 0; i < count; i++) {
768 HeapWord* start_address = ranges[i].start();
769 HeapWord* last_address = ranges[i].last();
770
771 assert(reserved.contains(start_address) && reserved.contains(last_address),
772 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
773 p2i(start_address), p2i(last_address));
774 assert(start_address > prev_last_addr,
775 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
776 p2i(start_address), p2i(prev_last_addr));
777 size_used += ranges[i].byte_size();
778 prev_last_addr = last_address;
779
780 HeapRegion* start_region = _hrm.addr_to_region(start_address);
781 HeapRegion* last_region = _hrm.addr_to_region(last_address);
782
783 // Check for ranges that start in the same G1 region in which the previous
784 // range ended, and adjust the start address so we don't try to free
785 // the same region again. If the current range is entirely within that
786 // region, skip it.
787 if (start_region == prev_last_region) {
788 start_address = start_region->end();
789 if (start_address > last_address) {
790 continue;
791 }
792 start_region = _hrm.addr_to_region(start_address);
793 }
794 prev_last_region = last_region;
795
796 // After verifying that each region was marked as an archive region by
797 // alloc_archive_regions, set it free and empty and uncommit it.
798 HeapRegion* curr_region = start_region;
799 while (curr_region != NULL) {
800 guarantee(curr_region->is_archive(),
801 "Expected archive region at index %u", curr_region->hrm_index());
802 uint curr_index = curr_region->hrm_index();
803 _old_set.remove(curr_region);
804 curr_region->set_free();
805 curr_region->set_top(curr_region->bottom());
806 if (curr_region != last_region) {
807 curr_region = _hrm.next_region_in_heap(curr_region);
808 } else {
809 curr_region = NULL;
810 }
811 _hrm.shrink_at(curr_index, 1);
812 uncommitted_regions++;
813 }
814
815 // Notify mark-sweep that this is no longer an archive range.
816 G1ArchiveAllocator::set_range_archive(ranges[i], false);
817 }
818
819 if (uncommitted_regions != 0) {
820 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
821 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
822 }
823 decrease_used(size_used);
824 }
825
826 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
827 ResourceMark rm; // For retrieving the thread names in log messages.
828
829 // The structure of this method has a lot of similarities to
830 // attempt_allocation_slow(). The reason these two were not merged
831 // into a single one is that such a method would require several "if
832 // allocation is not humongous do this, otherwise do that"
833 // conditional paths which would obscure its flow. In fact, an early
834 // version of this code did use a unified method which was harder to
835 // follow and, as a result, it had subtle bugs that were hard to
836 // track down. So keeping these two methods separate allows each to
837 // be more readable. It will be good to keep these two in sync as
838 // much as possible.
839
840 assert_heap_not_locked_and_not_at_safepoint();
841 assert(is_humongous(word_size), "attempt_allocation_humongous() "
842 "should only be called for humongous allocations");
843
844 // Humongous objects can exhaust the heap quickly, so we should check if we
845 // need to start a marking cycle at each humongous object allocation. We do
846 // the check before we do the actual allocation. The reason for doing it
847 // before the allocation is that we avoid having to keep track of the newly
848 // allocated memory while we do a GC.
849 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
850 word_size)) {
851 collect(GCCause::_g1_humongous_allocation);
852 }
853
854 // We will loop until a) we manage to successfully perform the
855 // allocation or b) we successfully schedule a collection which
856 // fails to perform the allocation. b) is the only case when we'll
857 // return NULL.
858 HeapWord* result = NULL;
859 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
860 bool should_try_gc;
861 uint gc_count_before;
862
863
864 {
865 MutexLockerEx x(Heap_lock);
866
867 // Given that humongous objects are not allocated in young
868 // regions, we'll first try to do the allocation without doing a
869 // collection hoping that there's enough space in the heap.
870 result = humongous_obj_allocate(word_size);
871 if (result != NULL) {
872 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
873 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
874 return result;
875 }
876
877 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
878 // the GCLocker initiated GC has been performed and then retry. This includes
879 // the case when the GC Locker is not active but has not been performed.
880 should_try_gc = !GCLocker::needs_gc();
881 // Read the GC count while still holding the Heap_lock.
882 gc_count_before = total_collections();
883 }
884
885 if (should_try_gc) {
886 bool succeeded;
887 result = do_collection_pause(word_size, gc_count_before, &succeeded,
888 GCCause::_g1_humongous_allocation);
889 if (result != NULL) {
890 assert(succeeded, "only way to get back a non-NULL result");
891 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
892 Thread::current()->name(), p2i(result));
893 return result;
894 }
895
896 if (succeeded) {
897 // We successfully scheduled a collection which failed to allocate. No
898 // point in trying to allocate further. We'll just return NULL.
899 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
900 SIZE_FORMAT " words", Thread::current()->name(), word_size);
901 return NULL;
902 }
903 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
904 Thread::current()->name(), word_size);
905 } else {
906 // Failed to schedule a collection.
907 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
908 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
909 SIZE_FORMAT " words", Thread::current()->name(), word_size);
910 return NULL;
911 }
912 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
913 // The GCLocker is either active or the GCLocker initiated
914 // GC has not yet been performed. Stall until it is and
915 // then retry the allocation.
916 GCLocker::stall_until_clear();
917 gclocker_retry_count += 1;
918 }
919
920
921 // We can reach here if we were unsuccessful in scheduling a
922 // collection (because another thread beat us to it) or if we were
923 // stalled due to the GC locker. In either can we should retry the
924 // allocation attempt in case another thread successfully
925 // performed a collection and reclaimed enough space.
926 // Humongous object allocation always needs a lock, so we wait for the retry
927 // in the next iteration of the loop, unlike for the regular iteration case.
928 // Give a warning if we seem to be looping forever.
929
930 if ((QueuedAllocationWarningCount > 0) &&
931 (try_count % QueuedAllocationWarningCount == 0)) {
932 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
933 Thread::current()->name(), try_count, word_size);
934 }
935 }
936
937 ShouldNotReachHere();
938 return NULL;
939 }
940
941 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
942 bool expect_null_mutator_alloc_region) {
943 assert_at_safepoint_on_vm_thread();
944 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
945 "the current alloc region was unexpectedly found to be non-NULL");
946
947 if (!is_humongous(word_size)) {
948 return _allocator->attempt_allocation_locked(word_size);
949 } else {
950 HeapWord* result = humongous_obj_allocate(word_size);
951 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
952 collector_state()->set_initiate_conc_mark_if_possible(true);
953 }
954 return result;
955 }
956
957 ShouldNotReachHere();
958 }
959
960 class PostCompactionPrinterClosure: public HeapRegionClosure {
961 private:
962 G1HRPrinter* _hr_printer;
963 public:
964 bool do_heap_region(HeapRegion* hr) {
965 assert(!hr->is_young(), "not expecting to find young regions");
966 _hr_printer->post_compaction(hr);
967 return false;
968 }
969
970 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
971 : _hr_printer(hr_printer) { }
972 };
973
974 void G1CollectedHeap::print_hrm_post_compaction() {
975 if (_hr_printer.is_active()) {
976 PostCompactionPrinterClosure cl(hr_printer());
977 heap_region_iterate(&cl);
978 }
979 }
980
981 void G1CollectedHeap::abort_concurrent_cycle() {
982 // If we start the compaction before the CM threads finish
983 // scanning the root regions we might trip them over as we'll
984 // be moving objects / updating references. So let's wait until
985 // they are done. By telling them to abort, they should complete
986 // early.
987 _cm->root_regions()->abort();
988 _cm->root_regions()->wait_until_scan_finished();
989
990 // Disable discovery and empty the discovered lists
991 // for the CM ref processor.
992 _ref_processor_cm->disable_discovery();
993 _ref_processor_cm->abandon_partial_discovery();
994 _ref_processor_cm->verify_no_references_recorded();
995
996 // Abandon current iterations of concurrent marking and concurrent
997 // refinement, if any are in progress.
998 concurrent_mark()->concurrent_cycle_abort();
999 }
1000
1001 void G1CollectedHeap::prepare_heap_for_full_collection() {
1002 // Make sure we'll choose a new allocation region afterwards.
1003 _allocator->release_mutator_alloc_region();
1004 _allocator->abandon_gc_alloc_regions();
1005 g1_rem_set()->cleanupHRRS();
1006
1007 // We may have added regions to the current incremental collection
1008 // set between the last GC or pause and now. We need to clear the
1009 // incremental collection set and then start rebuilding it afresh
1010 // after this full GC.
1011 abandon_collection_set(collection_set());
1012
1013 tear_down_region_sets(false /* free_list_only */);
1014 }
1015
1016 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1017 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1018 assert(used() == recalculate_used(), "Should be equal");
1019 _verifier->verify_region_sets_optional();
1020 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1021 _verifier->check_bitmaps("Full GC Start");
1022 }
1023
1024 void G1CollectedHeap::prepare_heap_for_mutators() {
1025 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1026 ClassLoaderDataGraph::purge();
1027 MetaspaceUtils::verify_metrics();
1028
1029 // Prepare heap for normal collections.
1030 assert(num_free_regions() == 0, "we should not have added any free regions");
1031 rebuild_region_sets(false /* free_list_only */);
1032 abort_refinement();
1033 resize_if_necessary_after_full_collection();
1034
1035 // Rebuild the strong code root lists for each region
1036 rebuild_strong_code_roots();
1037
1038 // Start a new incremental collection set for the next pause
1039 start_new_collection_set();
1040
1041 _allocator->init_mutator_alloc_region();
1042
1043 // Post collection state updates.
1044 MetaspaceGC::compute_new_size();
1045 }
1046
1047 void G1CollectedHeap::abort_refinement() {
1048 if (_hot_card_cache->use_cache()) {
1049 _hot_card_cache->reset_hot_cache();
1050 }
1051
1052 // Discard all remembered set updates.
1053 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1054 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1055 }
1056
1057 void G1CollectedHeap::verify_after_full_collection() {
1058 _hrm.verify_optional();
1059 _verifier->verify_region_sets_optional();
1060 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1061 // Clear the previous marking bitmap, if needed for bitmap verification.
1062 // Note we cannot do this when we clear the next marking bitmap in
1063 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1064 // objects marked during a full GC against the previous bitmap.
1065 // But we need to clear it before calling check_bitmaps below since
1066 // the full GC has compacted objects and updated TAMS but not updated
1067 // the prev bitmap.
1068 if (G1VerifyBitmaps) {
1069 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1070 _cm->clear_prev_bitmap(workers());
1071 }
1072 _verifier->check_bitmaps("Full GC End");
1073
1074 // At this point there should be no regions in the
1075 // entire heap tagged as young.
1076 assert(check_young_list_empty(), "young list should be empty at this point");
1077
1078 // Note: since we've just done a full GC, concurrent
1079 // marking is no longer active. Therefore we need not
1080 // re-enable reference discovery for the CM ref processor.
1081 // That will be done at the start of the next marking cycle.
1082 // We also know that the STW processor should no longer
1083 // discover any new references.
1084 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1085 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1086 _ref_processor_stw->verify_no_references_recorded();
1087 _ref_processor_cm->verify_no_references_recorded();
1088 }
1089
1090 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1091 // Post collection logging.
1092 // We should do this after we potentially resize the heap so
1093 // that all the COMMIT / UNCOMMIT events are generated before
1094 // the compaction events.
1095 print_hrm_post_compaction();
1096 heap_transition->print();
1097 print_heap_after_gc();
1098 print_heap_regions();
1099 #ifdef TRACESPINNING
1100 ParallelTaskTerminator::print_termination_counts();
1101 #endif
1102 }
1103
1104 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1105 bool clear_all_soft_refs) {
1106 assert_at_safepoint_on_vm_thread();
1107
1108 if (GCLocker::check_active_before_gc()) {
1109 // Full GC was not completed.
1110 return false;
1111 }
1112
1113 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1114 soft_ref_policy()->should_clear_all_soft_refs();
1115
1116 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1117 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1118
1119 collector.prepare_collection();
1120 collector.collect();
1121 collector.complete_collection();
1122
1123 // Full collection was successfully completed.
1124 return true;
1125 }
1126
1127 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1128 // Currently, there is no facility in the do_full_collection(bool) API to notify
1129 // the caller that the collection did not succeed (e.g., because it was locked
1130 // out by the GC locker). So, right now, we'll ignore the return value.
1131 bool dummy = do_full_collection(true, /* explicit_gc */
1132 clear_all_soft_refs);
1133 }
1134
1135 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1136 // Capacity, free and used after the GC counted as full regions to
1137 // include the waste in the following calculations.
1138 const size_t capacity_after_gc = capacity();
1139 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1140
1141 // This is enforced in arguments.cpp.
1142 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1143 "otherwise the code below doesn't make sense");
1144
1145 // We don't have floating point command-line arguments
1146 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1147 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1148 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1149 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1150
1151 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1152 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1153
1154 // We have to be careful here as these two calculations can overflow
1155 // 32-bit size_t's.
1156 double used_after_gc_d = (double) used_after_gc;
1157 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1158 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1159
1160 // Let's make sure that they are both under the max heap size, which
1161 // by default will make them fit into a size_t.
1162 double desired_capacity_upper_bound = (double) max_heap_size;
1163 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1164 desired_capacity_upper_bound);
1165 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1166 desired_capacity_upper_bound);
1167
1168 // We can now safely turn them into size_t's.
1169 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1170 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1171
1172 // This assert only makes sense here, before we adjust them
1173 // with respect to the min and max heap size.
1174 assert(minimum_desired_capacity <= maximum_desired_capacity,
1175 "minimum_desired_capacity = " SIZE_FORMAT ", "
1176 "maximum_desired_capacity = " SIZE_FORMAT,
1177 minimum_desired_capacity, maximum_desired_capacity);
1178
1179 // Should not be greater than the heap max size. No need to adjust
1180 // it with respect to the heap min size as it's a lower bound (i.e.,
1181 // we'll try to make the capacity larger than it, not smaller).
1182 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1183 // Should not be less than the heap min size. No need to adjust it
1184 // with respect to the heap max size as it's an upper bound (i.e.,
1185 // we'll try to make the capacity smaller than it, not greater).
1186 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1187
1188 if (capacity_after_gc < minimum_desired_capacity) {
1189 // Don't expand unless it's significant
1190 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1191
1192 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1193 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1194 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1195 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1196
1197 expand(expand_bytes, _workers);
1198
1199 // No expansion, now see if we want to shrink
1200 } else if (capacity_after_gc > maximum_desired_capacity) {
1201 // Capacity too large, compute shrinking size
1202 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1203
1204 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1205 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1206 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1207 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1208
1209 shrink(shrink_bytes);
1210 }
1211 }
1212
1213 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1214 bool do_gc,
1215 bool clear_all_soft_refs,
1216 bool expect_null_mutator_alloc_region,
1217 bool* gc_succeeded) {
1218 *gc_succeeded = true;
1219 // Let's attempt the allocation first.
1220 HeapWord* result =
1221 attempt_allocation_at_safepoint(word_size,
1222 expect_null_mutator_alloc_region);
1223 if (result != NULL) {
1224 return result;
1225 }
1226
1227 // In a G1 heap, we're supposed to keep allocation from failing by
1228 // incremental pauses. Therefore, at least for now, we'll favor
1229 // expansion over collection. (This might change in the future if we can
1230 // do something smarter than full collection to satisfy a failed alloc.)
1231 result = expand_and_allocate(word_size);
1232 if (result != NULL) {
1233 return result;
1234 }
1235
1236 if (do_gc) {
1237 // Expansion didn't work, we'll try to do a Full GC.
1238 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1239 clear_all_soft_refs);
1240 }
1241
1242 return NULL;
1243 }
1244
1245 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1246 bool* succeeded) {
1247 assert_at_safepoint_on_vm_thread();
1248
1249 // Attempts to allocate followed by Full GC.
1250 HeapWord* result =
1251 satisfy_failed_allocation_helper(word_size,
1252 true, /* do_gc */
1253 false, /* clear_all_soft_refs */
1254 false, /* expect_null_mutator_alloc_region */
1255 succeeded);
1256
1257 if (result != NULL || !*succeeded) {
1258 return result;
1259 }
1260
1261 // Attempts to allocate followed by Full GC that will collect all soft references.
1262 result = satisfy_failed_allocation_helper(word_size,
1263 true, /* do_gc */
1264 true, /* clear_all_soft_refs */
1265 true, /* expect_null_mutator_alloc_region */
1266 succeeded);
1267
1268 if (result != NULL || !*succeeded) {
1269 return result;
1270 }
1271
1272 // Attempts to allocate, no GC
1273 result = satisfy_failed_allocation_helper(word_size,
1274 false, /* do_gc */
1275 false, /* clear_all_soft_refs */
1276 true, /* expect_null_mutator_alloc_region */
1277 succeeded);
1278
1279 if (result != NULL) {
1280 return result;
1281 }
1282
1283 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1284 "Flag should have been handled and cleared prior to this point");
1285
1286 // What else? We might try synchronous finalization later. If the total
1287 // space available is large enough for the allocation, then a more
1288 // complete compaction phase than we've tried so far might be
1289 // appropriate.
1290 return NULL;
1291 }
1292
1293 // Attempting to expand the heap sufficiently
1294 // to support an allocation of the given "word_size". If
1295 // successful, perform the allocation and return the address of the
1296 // allocated block, or else "NULL".
1297
1298 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1299 assert_at_safepoint_on_vm_thread();
1300
1301 _verifier->verify_region_sets_optional();
1302
1303 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1304 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1305 word_size * HeapWordSize);
1306
1307
1308 if (expand(expand_bytes, _workers)) {
1309 _hrm.verify_optional();
1310 _verifier->verify_region_sets_optional();
1311 return attempt_allocation_at_safepoint(word_size,
1312 false /* expect_null_mutator_alloc_region */);
1313 }
1314 return NULL;
1315 }
1316
1317 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1318 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1319 aligned_expand_bytes = align_up(aligned_expand_bytes,
1320 HeapRegion::GrainBytes);
1321
1322 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1323 expand_bytes, aligned_expand_bytes);
1324
1325 if (is_maximal_no_gc()) {
1326 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1327 return false;
1328 }
1329
1330 double expand_heap_start_time_sec = os::elapsedTime();
1331 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1332 assert(regions_to_expand > 0, "Must expand by at least one region");
1333
1334 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1335 if (expand_time_ms != NULL) {
1336 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1337 }
1338
1339 if (expanded_by > 0) {
1340 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1341 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1342 g1_policy()->record_new_heap_size(num_regions());
1343 } else {
1344 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1345
1346 // The expansion of the virtual storage space was unsuccessful.
1347 // Let's see if it was because we ran out of swap.
1348 if (G1ExitOnExpansionFailure &&
1349 _hrm.available() >= regions_to_expand) {
1350 // We had head room...
1351 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1352 }
1353 }
1354 return regions_to_expand > 0;
1355 }
1356
1357 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1358 size_t aligned_shrink_bytes =
1359 ReservedSpace::page_align_size_down(shrink_bytes);
1360 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1361 HeapRegion::GrainBytes);
1362 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1363
1364 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1365 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1366
1367
1368 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",
1369 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1370 if (num_regions_removed > 0) {
1371 g1_policy()->record_new_heap_size(num_regions());
1372 } else {
1373 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1374 }
1375 }
1376
1377 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1378 _verifier->verify_region_sets_optional();
1379
1380 // We should only reach here at the end of a Full GC which means we
1381 // should not not be holding to any GC alloc regions. The method
1382 // below will make sure of that and do any remaining clean up.
1383 _allocator->abandon_gc_alloc_regions();
1384
1385 // Instead of tearing down / rebuilding the free lists here, we
1386 // could instead use the remove_all_pending() method on free_list to
1387 // remove only the ones that we need to remove.
1388 tear_down_region_sets(true /* free_list_only */);
1389 shrink_helper(shrink_bytes);
1390 rebuild_region_sets(true /* free_list_only */);
1391
1392 _hrm.verify_optional();
1393 _verifier->verify_region_sets_optional();
1394 }
1395
1396 // Public methods.
1397
1398 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1399 CollectedHeap(),
1400 _young_gen_sampling_thread(NULL),
1401 _collector_policy(collector_policy),
1402 _soft_ref_policy(),
1403 _card_table(NULL),
1404 _memory_manager("G1 Young Generation", "end of minor GC"),
1405 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1406 _eden_pool(NULL),
1407 _survivor_pool(NULL),
1408 _old_pool(NULL),
1409 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1410 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1411 _g1_policy(new G1Policy(_gc_timer_stw)),
1412 _collection_set(this, _g1_policy),
1413 _dirty_card_queue_set(false),
1414 _ref_processor_stw(NULL),
1415 _is_alive_closure_stw(this),
1416 _is_subject_to_discovery_stw(this),
1417 _ref_processor_cm(NULL),
1418 _is_alive_closure_cm(this),
1419 _is_subject_to_discovery_cm(this),
1420 _bot(NULL),
1421 _hot_card_cache(NULL),
1422 _g1_rem_set(NULL),
1423 _cr(NULL),
1424 _g1mm(NULL),
1425 _preserved_marks_set(true /* in_c_heap */),
1426 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1427 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1428 _humongous_reclaim_candidates(),
1429 _has_humongous_reclaim_candidates(false),
1430 _archive_allocator(NULL),
1431 _summary_bytes_used(0),
1432 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1433 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1434 _expand_heap_after_alloc_failure(true),
1435 _old_marking_cycles_started(0),
1436 _old_marking_cycles_completed(0),
1437 _in_cset_fast_test() {
1438
1439 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1440 /* are_GC_task_threads */true,
1441 /* are_ConcurrentGC_threads */false);
1442 _workers->initialize_workers();
1443 _verifier = new G1HeapVerifier(this);
1444
1445 _allocator = new G1Allocator(this);
1446
1447 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1448
1449 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1450
1451 // Override the default _filler_array_max_size so that no humongous filler
1452 // objects are created.
1453 _filler_array_max_size = _humongous_object_threshold_in_words;
1454
1455 uint n_queues = ParallelGCThreads;
1456 _task_queues = new RefToScanQueueSet(n_queues);
1457
1458 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1459
1460 for (uint i = 0; i < n_queues; i++) {
1461 RefToScanQueue* q = new RefToScanQueue();
1462 q->initialize();
1463 _task_queues->register_queue(i, q);
1464 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1465 }
1466
1467 // Initialize the G1EvacuationFailureALot counters and flags.
1468 NOT_PRODUCT(reset_evacuation_should_fail();)
1469
1470 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1471 }
1472
1473 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1474 size_t size,
1475 size_t translation_factor) {
1476 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1477 // Allocate a new reserved space, preferring to use large pages.
1478 ReservedSpace rs(size, preferred_page_size);
1479 G1RegionToSpaceMapper* result =
1480 G1RegionToSpaceMapper::create_mapper(rs,
1481 size,
1482 rs.alignment(),
1483 HeapRegion::GrainBytes,
1484 translation_factor,
1485 mtGC);
1486
1487 os::trace_page_sizes_for_requested_size(description,
1488 size,
1489 preferred_page_size,
1490 rs.alignment(),
1491 rs.base(),
1492 rs.size());
1493
1494 return result;
1495 }
1496
1497 jint G1CollectedHeap::initialize_concurrent_refinement() {
1498 jint ecode = JNI_OK;
1499 _cr = G1ConcurrentRefine::create(&ecode);
1500 return ecode;
1501 }
1502
1503 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1504 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1505 if (_young_gen_sampling_thread->osthread() == NULL) {
1506 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1507 return JNI_ENOMEM;
1508 }
1509 return JNI_OK;
1510 }
1511
1512 jint G1CollectedHeap::initialize() {
1513 os::enable_vtime();
1514
1515 // Necessary to satisfy locking discipline assertions.
1516
1517 MutexLocker x(Heap_lock);
1518
1519 // While there are no constraints in the GC code that HeapWordSize
1520 // be any particular value, there are multiple other areas in the
1521 // system which believe this to be true (e.g. oop->object_size in some
1522 // cases incorrectly returns the size in wordSize units rather than
1523 // HeapWordSize).
1524 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1525
1526 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1527 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1528 size_t heap_alignment = collector_policy()->heap_alignment();
1529
1530 // Ensure that the sizes are properly aligned.
1531 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1532 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1533 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1534
1535 // Reserve the maximum.
1536
1537 // When compressed oops are enabled, the preferred heap base
1538 // is calculated by subtracting the requested size from the
1539 // 32Gb boundary and using the result as the base address for
1540 // heap reservation. If the requested size is not aligned to
1541 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1542 // into the ReservedHeapSpace constructor) then the actual
1543 // base of the reserved heap may end up differing from the
1544 // address that was requested (i.e. the preferred heap base).
1545 // If this happens then we could end up using a non-optimal
1546 // compressed oops mode.
1547
1548 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1549 heap_alignment);
1550
1551 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1552
1553 // Create the barrier set for the entire reserved region.
1554 G1CardTable* ct = new G1CardTable(reserved_region());
1555 ct->initialize();
1556 G1BarrierSet* bs = new G1BarrierSet(ct);
1557 bs->initialize();
1558 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1559 BarrierSet::set_barrier_set(bs);
1560 _card_table = ct;
1561
1562 // Create the hot card cache.
1563 _hot_card_cache = new G1HotCardCache(this);
1564
1565 // Carve out the G1 part of the heap.
1566 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1567 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1568 G1RegionToSpaceMapper* heap_storage =
1569 G1RegionToSpaceMapper::create_mapper(g1_rs,
1570 g1_rs.size(),
1571 page_size,
1572 HeapRegion::GrainBytes,
1573 1,
1574 mtJavaHeap);
1575 os::trace_page_sizes("Heap",
1576 collector_policy()->min_heap_byte_size(),
1577 max_byte_size,
1578 page_size,
1579 heap_rs.base(),
1580 heap_rs.size());
1581 heap_storage->set_mapping_changed_listener(&_listener);
1582
1583 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1584 G1RegionToSpaceMapper* bot_storage =
1585 create_aux_memory_mapper("Block Offset Table",
1586 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1587 G1BlockOffsetTable::heap_map_factor());
1588
1589 G1RegionToSpaceMapper* cardtable_storage =
1590 create_aux_memory_mapper("Card Table",
1591 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1592 G1CardTable::heap_map_factor());
1593
1594 G1RegionToSpaceMapper* card_counts_storage =
1595 create_aux_memory_mapper("Card Counts Table",
1596 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1597 G1CardCounts::heap_map_factor());
1598
1599 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1600 G1RegionToSpaceMapper* prev_bitmap_storage =
1601 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1602 G1RegionToSpaceMapper* next_bitmap_storage =
1603 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1604
1605 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1606 _card_table->initialize(cardtable_storage);
1607 // Do later initialization work for concurrent refinement.
1608 _hot_card_cache->initialize(card_counts_storage);
1609
1610 // 6843694 - ensure that the maximum region index can fit
1611 // in the remembered set structures.
1612 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1613 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1614
1615 // Also create a G1 rem set.
1616 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1617 _g1_rem_set->initialize(max_capacity(), max_regions());
1618
1619 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1620 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1621 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1622 "too many cards per region");
1623
1624 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1625
1626 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1627
1628 {
1629 HeapWord* start = _hrm.reserved().start();
1630 HeapWord* end = _hrm.reserved().end();
1631 size_t granularity = HeapRegion::GrainBytes;
1632
1633 _in_cset_fast_test.initialize(start, end, granularity);
1634 _humongous_reclaim_candidates.initialize(start, end, granularity);
1635 }
1636
1637 // Create the G1ConcurrentMark data structure and thread.
1638 // (Must do this late, so that "max_regions" is defined.)
1639 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1640 if (_cm == NULL || !_cm->completed_initialization()) {
1641 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1642 return JNI_ENOMEM;
1643 }
1644 _cm_thread = _cm->cm_thread();
1645
1646 // Now expand into the initial heap size.
1647 if (!expand(init_byte_size, _workers)) {
1648 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1649 return JNI_ENOMEM;
1650 }
1651
1652 // Perform any initialization actions delegated to the policy.
1653 g1_policy()->init(this, &_collection_set);
1654
1655 G1BarrierSet::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1656 SATB_Q_FL_lock,
1657 G1SATBProcessCompletedThreshold,
1658 Shared_SATB_Q_lock);
1659
1660 jint ecode = initialize_concurrent_refinement();
1661 if (ecode != JNI_OK) {
1662 return ecode;
1663 }
1664
1665 ecode = initialize_young_gen_sampling_thread();
1666 if (ecode != JNI_OK) {
1667 return ecode;
1668 }
1669
1670 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1671 DirtyCardQ_FL_lock,
1672 (int)concurrent_refine()->yellow_zone(),
1673 (int)concurrent_refine()->red_zone(),
1674 Shared_DirtyCardQ_lock,
1675 NULL, // fl_owner
1676 true); // init_free_ids
1677
1678 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1679 DirtyCardQ_FL_lock,
1680 -1, // never trigger processing
1681 -1, // no limit on length
1682 Shared_DirtyCardQ_lock,
1683 &G1BarrierSet::dirty_card_queue_set());
1684
1685 // Here we allocate the dummy HeapRegion that is required by the
1686 // G1AllocRegion class.
1687 HeapRegion* dummy_region = _hrm.get_dummy_region();
1688
1689 // We'll re-use the same region whether the alloc region will
1690 // require BOT updates or not and, if it doesn't, then a non-young
1691 // region will complain that it cannot support allocations without
1692 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1693 dummy_region->set_eden();
1694 // Make sure it's full.
1695 dummy_region->set_top(dummy_region->end());
1696 G1AllocRegion::setup(this, dummy_region);
1697
1698 _allocator->init_mutator_alloc_region();
1699
1700 // Do create of the monitoring and management support so that
1701 // values in the heap have been properly initialized.
1702 _g1mm = new G1MonitoringSupport(this);
1703
1704 G1StringDedup::initialize();
1705
1706 _preserved_marks_set.init(ParallelGCThreads);
1707
1708 _collection_set.initialize(max_regions());
1709
1710 return JNI_OK;
1711 }
1712
1713 void G1CollectedHeap::initialize_serviceability() {
1714 _eden_pool = new G1EdenPool(this);
1715 _survivor_pool = new G1SurvivorPool(this);
1716 _old_pool = new G1OldGenPool(this);
1717
1718 _full_gc_memory_manager.add_pool(_eden_pool);
1719 _full_gc_memory_manager.add_pool(_survivor_pool);
1720 _full_gc_memory_manager.add_pool(_old_pool);
1721
1722 _memory_manager.add_pool(_eden_pool);
1723 _memory_manager.add_pool(_survivor_pool);
1724
1725 }
1726
1727 void G1CollectedHeap::stop() {
1728 // Stop all concurrent threads. We do this to make sure these threads
1729 // do not continue to execute and access resources (e.g. logging)
1730 // that are destroyed during shutdown.
1731 _cr->stop();
1732 _young_gen_sampling_thread->stop();
1733 _cm_thread->stop();
1734 if (G1StringDedup::is_enabled()) {
1735 G1StringDedup::stop();
1736 }
1737 }
1738
1739 void G1CollectedHeap::safepoint_synchronize_begin() {
1740 SuspendibleThreadSet::synchronize();
1741 }
1742
1743 void G1CollectedHeap::safepoint_synchronize_end() {
1744 SuspendibleThreadSet::desynchronize();
1745 }
1746
1747 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1748 return HeapRegion::max_region_size();
1749 }
1750
1751 void G1CollectedHeap::post_initialize() {
1752 CollectedHeap::post_initialize();
1753 ref_processing_init();
1754 }
1755
1756 void G1CollectedHeap::ref_processing_init() {
1757 // Reference processing in G1 currently works as follows:
1758 //
1759 // * There are two reference processor instances. One is
1760 // used to record and process discovered references
1761 // during concurrent marking; the other is used to
1762 // record and process references during STW pauses
1763 // (both full and incremental).
1764 // * Both ref processors need to 'span' the entire heap as
1765 // the regions in the collection set may be dotted around.
1766 //
1767 // * For the concurrent marking ref processor:
1768 // * Reference discovery is enabled at initial marking.
1769 // * Reference discovery is disabled and the discovered
1770 // references processed etc during remarking.
1771 // * Reference discovery is MT (see below).
1772 // * Reference discovery requires a barrier (see below).
1773 // * Reference processing may or may not be MT
1774 // (depending on the value of ParallelRefProcEnabled
1775 // and ParallelGCThreads).
1776 // * A full GC disables reference discovery by the CM
1777 // ref processor and abandons any entries on it's
1778 // discovered lists.
1779 //
1780 // * For the STW processor:
1781 // * Non MT discovery is enabled at the start of a full GC.
1782 // * Processing and enqueueing during a full GC is non-MT.
1783 // * During a full GC, references are processed after marking.
1784 //
1785 // * Discovery (may or may not be MT) is enabled at the start
1786 // of an incremental evacuation pause.
1787 // * References are processed near the end of a STW evacuation pause.
1788 // * For both types of GC:
1789 // * Discovery is atomic - i.e. not concurrent.
1790 // * Reference discovery will not need a barrier.
1791
1792 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1793
1794 // Concurrent Mark ref processor
1795 _ref_processor_cm =
1796 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1797 mt_processing, // mt processing
1798 ParallelGCThreads, // degree of mt processing
1799 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1800 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1801 false, // Reference discovery is not atomic
1802 &_is_alive_closure_cm); // is alive closure
1803
1804 // STW ref processor
1805 _ref_processor_stw =
1806 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1807 mt_processing, // mt processing
1808 ParallelGCThreads, // degree of mt processing
1809 (ParallelGCThreads > 1), // mt discovery
1810 ParallelGCThreads, // degree of mt discovery
1811 true, // Reference discovery is atomic
1812 &_is_alive_closure_stw); // is alive closure
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 = G1BarrierSet::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, G1GCPhaseTimes::UpdateRSProcessedBuffers);
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 _cm_thread->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::deduplicate_string(oop str) {
2169 assert(java_lang_String::is_instance(str), "invariant");
2170
2171 if (G1StringDedup::is_enabled()) {
2172 G1StringDedup::deduplicate(str);
2173 }
2174 }
2175
2176 void G1CollectedHeap::prepare_for_verify() {
2177 _verifier->prepare_for_verify();
2178 }
2179
2180 void G1CollectedHeap::verify(VerifyOption vo) {
2181 _verifier->verify(vo);
2182 }
2183
2184 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2185 return true;
2186 }
2187
2188 const char* const* G1CollectedHeap::concurrent_phases() const {
2189 return _cm_thread->concurrent_phases();
2190 }
2191
2192 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2193 return _cm_thread->request_concurrent_phase(phase);
2194 }
2195
2196 class PrintRegionClosure: public HeapRegionClosure {
2197 outputStream* _st;
2198 public:
2199 PrintRegionClosure(outputStream* st) : _st(st) {}
2200 bool do_heap_region(HeapRegion* r) {
2201 r->print_on(_st);
2202 return false;
2203 }
2204 };
2205
2206 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2207 const HeapRegion* hr,
2208 const VerifyOption vo) const {
2209 switch (vo) {
2210 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2211 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2212 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2213 default: ShouldNotReachHere();
2214 }
2215 return false; // keep some compilers happy
2216 }
2217
2218 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2219 const VerifyOption vo) const {
2220 switch (vo) {
2221 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2222 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2223 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2224 default: ShouldNotReachHere();
2225 }
2226 return false; // keep some compilers happy
2227 }
2228
2229 void G1CollectedHeap::print_heap_regions() const {
2230 LogTarget(Trace, gc, heap, region) lt;
2231 if (lt.is_enabled()) {
2232 LogStream ls(lt);
2233 print_regions_on(&ls);
2234 }
2235 }
2236
2237 void G1CollectedHeap::print_on(outputStream* st) const {
2238 st->print(" %-20s", "garbage-first heap");
2239 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2240 capacity()/K, used_unlocked()/K);
2241 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2242 p2i(_hrm.reserved().start()),
2243 p2i(_hrm.reserved().end()));
2244 st->cr();
2245 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2246 uint young_regions = young_regions_count();
2247 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2248 (size_t) young_regions * HeapRegion::GrainBytes / K);
2249 uint survivor_regions = survivor_regions_count();
2250 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2251 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2252 st->cr();
2253 MetaspaceUtils::print_on(st);
2254 }
2255
2256 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2257 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2258 "HS=humongous(starts), HC=humongous(continues), "
2259 "CS=collection set, F=free, A=archive, "
2260 "TAMS=top-at-mark-start (previous, next)");
2261 PrintRegionClosure blk(st);
2262 heap_region_iterate(&blk);
2263 }
2264
2265 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2266 print_on(st);
2267
2268 // Print the per-region information.
2269 print_regions_on(st);
2270 }
2271
2272 void G1CollectedHeap::print_on_error(outputStream* st) const {
2273 this->CollectedHeap::print_on_error(st);
2274
2275 if (_cm != NULL) {
2276 st->cr();
2277 _cm->print_on_error(st);
2278 }
2279 }
2280
2281 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2282 workers()->print_worker_threads_on(st);
2283 _cm_thread->print_on(st);
2284 st->cr();
2285 _cm->print_worker_threads_on(st);
2286 _cr->print_threads_on(st);
2287 _young_gen_sampling_thread->print_on(st);
2288 if (G1StringDedup::is_enabled()) {
2289 G1StringDedup::print_worker_threads_on(st);
2290 }
2291 }
2292
2293 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2294 workers()->threads_do(tc);
2295 tc->do_thread(_cm_thread);
2296 _cm->threads_do(tc);
2297 _cr->threads_do(tc);
2298 tc->do_thread(_young_gen_sampling_thread);
2299 if (G1StringDedup::is_enabled()) {
2300 G1StringDedup::threads_do(tc);
2301 }
2302 }
2303
2304 void G1CollectedHeap::print_tracing_info() const {
2305 g1_rem_set()->print_summary_info();
2306 concurrent_mark()->print_summary_info();
2307 }
2308
2309 #ifndef PRODUCT
2310 // Helpful for debugging RSet issues.
2311
2312 class PrintRSetsClosure : public HeapRegionClosure {
2313 private:
2314 const char* _msg;
2315 size_t _occupied_sum;
2316
2317 public:
2318 bool do_heap_region(HeapRegion* r) {
2319 HeapRegionRemSet* hrrs = r->rem_set();
2320 size_t occupied = hrrs->occupied();
2321 _occupied_sum += occupied;
2322
2323 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2324 if (occupied == 0) {
2325 tty->print_cr(" RSet is empty");
2326 } else {
2327 hrrs->print();
2328 }
2329 tty->print_cr("----------");
2330 return false;
2331 }
2332
2333 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2334 tty->cr();
2335 tty->print_cr("========================================");
2336 tty->print_cr("%s", msg);
2337 tty->cr();
2338 }
2339
2340 ~PrintRSetsClosure() {
2341 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2342 tty->print_cr("========================================");
2343 tty->cr();
2344 }
2345 };
2346
2347 void G1CollectedHeap::print_cset_rsets() {
2348 PrintRSetsClosure cl("Printing CSet RSets");
2349 collection_set_iterate(&cl);
2350 }
2351
2352 void G1CollectedHeap::print_all_rsets() {
2353 PrintRSetsClosure cl("Printing All RSets");;
2354 heap_region_iterate(&cl);
2355 }
2356 #endif // PRODUCT
2357
2358 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2359
2360 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2361 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2362 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2363
2364 size_t eden_capacity_bytes =
2365 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2366
2367 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2368 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2369 eden_capacity_bytes, survivor_used_bytes, num_regions());
2370 }
2371
2372 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2373 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2374 stats->unused(), stats->used(), stats->region_end_waste(),
2375 stats->regions_filled(), stats->direct_allocated(),
2376 stats->failure_used(), stats->failure_waste());
2377 }
2378
2379 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2380 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2381 gc_tracer->report_gc_heap_summary(when, heap_summary);
2382
2383 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2384 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2385 }
2386
2387 G1CollectedHeap* G1CollectedHeap::heap() {
2388 CollectedHeap* heap = Universe::heap();
2389 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2390 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2391 return (G1CollectedHeap*)heap;
2392 }
2393
2394 void G1CollectedHeap::gc_prologue(bool full) {
2395 // always_do_update_barrier = false;
2396 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2397
2398 // This summary needs to be printed before incrementing total collections.
2399 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2400
2401 // Update common counters.
2402 increment_total_collections(full /* full gc */);
2403 if (full) {
2404 increment_old_marking_cycles_started();
2405 }
2406
2407 // Fill TLAB's and such
2408 double start = os::elapsedTime();
2409 accumulate_statistics_all_tlabs();
2410 ensure_parsability(true);
2411 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2412 }
2413
2414 void G1CollectedHeap::gc_epilogue(bool full) {
2415 // Update common counters.
2416 if (full) {
2417 // Update the number of full collections that have been completed.
2418 increment_old_marking_cycles_completed(false /* concurrent */);
2419 }
2420
2421 // We are at the end of the GC. Total collections has already been increased.
2422 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2423
2424 // FIXME: what is this about?
2425 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2426 // is set.
2427 #if COMPILER2_OR_JVMCI
2428 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2429 #endif
2430 // always_do_update_barrier = true;
2431
2432 double start = os::elapsedTime();
2433 resize_all_tlabs();
2434 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2435
2436 MemoryService::track_memory_usage();
2437 // We have just completed a GC. Update the soft reference
2438 // policy with the new heap occupancy
2439 Universe::update_heap_info_at_gc();
2440 }
2441
2442 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2443 uint gc_count_before,
2444 bool* succeeded,
2445 GCCause::Cause gc_cause) {
2446 assert_heap_not_locked_and_not_at_safepoint();
2447 VM_G1CollectForAllocation op(word_size,
2448 gc_count_before,
2449 gc_cause,
2450 false, /* should_initiate_conc_mark */
2451 g1_policy()->max_pause_time_ms());
2452 VMThread::execute(&op);
2453
2454 HeapWord* result = op.result();
2455 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2456 assert(result == NULL || ret_succeeded,
2457 "the result should be NULL if the VM did not succeed");
2458 *succeeded = ret_succeeded;
2459
2460 assert_heap_not_locked();
2461 return result;
2462 }
2463
2464 void G1CollectedHeap::do_concurrent_mark() {
2465 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2466 if (!_cm_thread->in_progress()) {
2467 _cm_thread->set_started();
2468 CGC_lock->notify();
2469 }
2470 }
2471
2472 size_t G1CollectedHeap::pending_card_num() {
2473 size_t extra_cards = 0;
2474 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2475 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2476 extra_cards += dcq.size();
2477 }
2478 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2479 size_t buffer_size = dcqs.buffer_size();
2480 size_t buffer_num = dcqs.completed_buffers_num();
2481
2482 return buffer_size * buffer_num + extra_cards;
2483 }
2484
2485 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2486 // We don't nominate objects with many remembered set entries, on
2487 // the assumption that such objects are likely still live.
2488 HeapRegionRemSet* rem_set = r->rem_set();
2489
2490 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2491 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2492 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2493 }
2494
2495 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2496 private:
2497 size_t _total_humongous;
2498 size_t _candidate_humongous;
2499
2500 DirtyCardQueue _dcq;
2501
2502 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2503 assert(region->is_starts_humongous(), "Must start a humongous object");
2504
2505 oop obj = oop(region->bottom());
2506
2507 // Dead objects cannot be eager reclaim candidates. Due to class
2508 // unloading it is unsafe to query their classes so we return early.
2509 if (g1h->is_obj_dead(obj, region)) {
2510 return false;
2511 }
2512
2513 // If we do not have a complete remembered set for the region, then we can
2514 // not be sure that we have all references to it.
2515 if (!region->rem_set()->is_complete()) {
2516 return false;
2517 }
2518 // Candidate selection must satisfy the following constraints
2519 // while concurrent marking is in progress:
2520 //
2521 // * In order to maintain SATB invariants, an object must not be
2522 // reclaimed if it was allocated before the start of marking and
2523 // has not had its references scanned. Such an object must have
2524 // its references (including type metadata) scanned to ensure no
2525 // live objects are missed by the marking process. Objects
2526 // allocated after the start of concurrent marking don't need to
2527 // be scanned.
2528 //
2529 // * An object must not be reclaimed if it is on the concurrent
2530 // mark stack. Objects allocated after the start of concurrent
2531 // marking are never pushed on the mark stack.
2532 //
2533 // Nominating only objects allocated after the start of concurrent
2534 // marking is sufficient to meet both constraints. This may miss
2535 // some objects that satisfy the constraints, but the marking data
2536 // structures don't support efficiently performing the needed
2537 // additional tests or scrubbing of the mark stack.
2538 //
2539 // However, we presently only nominate is_typeArray() objects.
2540 // A humongous object containing references induces remembered
2541 // set entries on other regions. In order to reclaim such an
2542 // object, those remembered sets would need to be cleaned up.
2543 //
2544 // We also treat is_typeArray() objects specially, allowing them
2545 // to be reclaimed even if allocated before the start of
2546 // concurrent mark. For this we rely on mark stack insertion to
2547 // exclude is_typeArray() objects, preventing reclaiming an object
2548 // that is in the mark stack. We also rely on the metadata for
2549 // such objects to be built-in and so ensured to be kept live.
2550 // Frequent allocation and drop of large binary blobs is an
2551 // important use case for eager reclaim, and this special handling
2552 // may reduce needed headroom.
2553
2554 return obj->is_typeArray() &&
2555 g1h->is_potential_eager_reclaim_candidate(region);
2556 }
2557
2558 public:
2559 RegisterHumongousWithInCSetFastTestClosure()
2560 : _total_humongous(0),
2561 _candidate_humongous(0),
2562 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2563 }
2564
2565 virtual bool do_heap_region(HeapRegion* r) {
2566 if (!r->is_starts_humongous()) {
2567 return false;
2568 }
2569 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2570
2571 bool is_candidate = humongous_region_is_candidate(g1h, r);
2572 uint rindex = r->hrm_index();
2573 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2574 if (is_candidate) {
2575 _candidate_humongous++;
2576 g1h->register_humongous_region_with_cset(rindex);
2577 // Is_candidate already filters out humongous object with large remembered sets.
2578 // If we have a humongous object with a few remembered sets, we simply flush these
2579 // remembered set entries into the DCQS. That will result in automatic
2580 // re-evaluation of their remembered set entries during the following evacuation
2581 // phase.
2582 if (!r->rem_set()->is_empty()) {
2583 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2584 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2585 G1CardTable* ct = g1h->card_table();
2586 HeapRegionRemSetIterator hrrs(r->rem_set());
2587 size_t card_index;
2588 while (hrrs.has_next(card_index)) {
2589 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2590 // The remembered set might contain references to already freed
2591 // regions. Filter out such entries to avoid failing card table
2592 // verification.
2593 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2594 if (*card_ptr != G1CardTable::dirty_card_val()) {
2595 *card_ptr = G1CardTable::dirty_card_val();
2596 _dcq.enqueue(card_ptr);
2597 }
2598 }
2599 }
2600 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2601 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2602 hrrs.n_yielded(), r->rem_set()->occupied());
2603 // We should only clear the card based remembered set here as we will not
2604 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2605 // (and probably never) we do not enter this path if there are other kind of
2606 // remembered sets for this region.
2607 r->rem_set()->clear_locked(true /* only_cardset */);
2608 // Clear_locked() above sets the state to Empty. However we want to continue
2609 // collecting remembered set entries for humongous regions that were not
2610 // reclaimed.
2611 r->rem_set()->set_state_complete();
2612 }
2613 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2614 }
2615 _total_humongous++;
2616
2617 return false;
2618 }
2619
2620 size_t total_humongous() const { return _total_humongous; }
2621 size_t candidate_humongous() const { return _candidate_humongous; }
2622
2623 void flush_rem_set_entries() { _dcq.flush(); }
2624 };
2625
2626 void G1CollectedHeap::register_humongous_regions_with_cset() {
2627 if (!G1EagerReclaimHumongousObjects) {
2628 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2629 return;
2630 }
2631 double time = os::elapsed_counter();
2632
2633 // Collect reclaim candidate information and register candidates with cset.
2634 RegisterHumongousWithInCSetFastTestClosure cl;
2635 heap_region_iterate(&cl);
2636
2637 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2638 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2639 cl.total_humongous(),
2640 cl.candidate_humongous());
2641 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2642
2643 // Finally flush all remembered set entries to re-check into the global DCQS.
2644 cl.flush_rem_set_entries();
2645 }
2646
2647 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2648 public:
2649 bool do_heap_region(HeapRegion* hr) {
2650 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2651 hr->verify_rem_set();
2652 }
2653 return false;
2654 }
2655 };
2656
2657 uint G1CollectedHeap::num_task_queues() const {
2658 return _task_queues->size();
2659 }
2660
2661 #if TASKQUEUE_STATS
2662 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2663 st->print_raw_cr("GC Task Stats");
2664 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2665 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2666 }
2667
2668 void G1CollectedHeap::print_taskqueue_stats() const {
2669 if (!log_is_enabled(Trace, gc, task, stats)) {
2670 return;
2671 }
2672 Log(gc, task, stats) log;
2673 ResourceMark rm;
2674 LogStream ls(log.trace());
2675 outputStream* st = &ls;
2676
2677 print_taskqueue_stats_hdr(st);
2678
2679 TaskQueueStats totals;
2680 const uint n = num_task_queues();
2681 for (uint i = 0; i < n; ++i) {
2682 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2683 totals += task_queue(i)->stats;
2684 }
2685 st->print_raw("tot "); totals.print(st); st->cr();
2686
2687 DEBUG_ONLY(totals.verify());
2688 }
2689
2690 void G1CollectedHeap::reset_taskqueue_stats() {
2691 const uint n = num_task_queues();
2692 for (uint i = 0; i < n; ++i) {
2693 task_queue(i)->stats.reset();
2694 }
2695 }
2696 #endif // TASKQUEUE_STATS
2697
2698 void G1CollectedHeap::wait_for_root_region_scanning() {
2699 double scan_wait_start = os::elapsedTime();
2700 // We have to wait until the CM threads finish scanning the
2701 // root regions as it's the only way to ensure that all the
2702 // objects on them have been correctly scanned before we start
2703 // moving them during the GC.
2704 bool waited = _cm->root_regions()->wait_until_scan_finished();
2705 double wait_time_ms = 0.0;
2706 if (waited) {
2707 double scan_wait_end = os::elapsedTime();
2708 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2709 }
2710 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2711 }
2712
2713 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2714 private:
2715 G1HRPrinter* _hr_printer;
2716 public:
2717 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2718
2719 virtual bool do_heap_region(HeapRegion* r) {
2720 _hr_printer->cset(r);
2721 return false;
2722 }
2723 };
2724
2725 void G1CollectedHeap::start_new_collection_set() {
2726 collection_set()->start_incremental_building();
2727
2728 clear_cset_fast_test();
2729
2730 guarantee(_eden.length() == 0, "eden should have been cleared");
2731 g1_policy()->transfer_survivors_to_cset(survivor());
2732 }
2733
2734 bool
2735 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2736 assert_at_safepoint_on_vm_thread();
2737 guarantee(!is_gc_active(), "collection is not reentrant");
2738
2739 if (GCLocker::check_active_before_gc()) {
2740 return false;
2741 }
2742
2743 _gc_timer_stw->register_gc_start();
2744
2745 GCIdMark gc_id_mark;
2746 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2747
2748 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2749 ResourceMark rm;
2750
2751 g1_policy()->note_gc_start();
2752
2753 wait_for_root_region_scanning();
2754
2755 print_heap_before_gc();
2756 print_heap_regions();
2757 trace_heap_before_gc(_gc_tracer_stw);
2758
2759 _verifier->verify_region_sets_optional();
2760 _verifier->verify_dirty_young_regions();
2761
2762 // We should not be doing initial mark unless the conc mark thread is running
2763 if (!_cm_thread->should_terminate()) {
2764 // This call will decide whether this pause is an initial-mark
2765 // pause. If it is, in_initial_mark_gc() will return true
2766 // for the duration of this pause.
2767 g1_policy()->decide_on_conc_mark_initiation();
2768 }
2769
2770 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2771 assert(!collector_state()->in_initial_mark_gc() ||
2772 collector_state()->in_young_only_phase(), "sanity");
2773
2774 // We also do not allow mixed GCs during marking.
2775 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2776
2777 // Record whether this pause is an initial mark. When the current
2778 // thread has completed its logging output and it's safe to signal
2779 // the CM thread, the flag's value in the policy has been reset.
2780 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2781
2782 // Inner scope for scope based logging, timers, and stats collection
2783 {
2784 EvacuationInfo evacuation_info;
2785
2786 if (collector_state()->in_initial_mark_gc()) {
2787 // We are about to start a marking cycle, so we increment the
2788 // full collection counter.
2789 increment_old_marking_cycles_started();
2790 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2791 }
2792
2793 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2794
2795 GCTraceCPUTime tcpu;
2796
2797 G1HeapVerifier::G1VerifyType verify_type;
2798 FormatBuffer<> gc_string("Pause ");
2799 if (collector_state()->in_initial_mark_gc()) {
2800 gc_string.append("Initial Mark");
2801 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2802 } else if (collector_state()->in_young_only_phase()) {
2803 gc_string.append("Young");
2804 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2805 } else {
2806 gc_string.append("Mixed");
2807 verify_type = G1HeapVerifier::G1VerifyMixed;
2808 }
2809 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2810
2811 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2812 workers()->active_workers(),
2813 Threads::number_of_non_daemon_threads());
2814 active_workers = workers()->update_active_workers(active_workers);
2815 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2816
2817 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2818 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2819
2820 G1HeapTransition heap_transition(this);
2821 size_t heap_used_bytes_before_gc = used();
2822
2823 // Don't dynamically change the number of GC threads this early. A value of
2824 // 0 is used to indicate serial work. When parallel work is done,
2825 // it will be set.
2826
2827 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2828 IsGCActiveMark x;
2829
2830 gc_prologue(false);
2831
2832 if (VerifyRememberedSets) {
2833 log_info(gc, verify)("[Verifying RemSets before GC]");
2834 VerifyRegionRemSetClosure v_cl;
2835 heap_region_iterate(&v_cl);
2836 }
2837
2838 _verifier->verify_before_gc(verify_type);
2839
2840 _verifier->check_bitmaps("GC Start");
2841
2842 #if COMPILER2_OR_JVMCI
2843 DerivedPointerTable::clear();
2844 #endif
2845
2846 // Please see comment in g1CollectedHeap.hpp and
2847 // G1CollectedHeap::ref_processing_init() to see how
2848 // reference processing currently works in G1.
2849
2850 // Enable discovery in the STW reference processor
2851 _ref_processor_stw->enable_discovery();
2852
2853 {
2854 // We want to temporarily turn off discovery by the
2855 // CM ref processor, if necessary, and turn it back on
2856 // on again later if we do. Using a scoped
2857 // NoRefDiscovery object will do this.
2858 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2859
2860 // Forget the current alloc region (we might even choose it to be part
2861 // of the collection set!).
2862 _allocator->release_mutator_alloc_region();
2863
2864 // This timing is only used by the ergonomics to handle our pause target.
2865 // It is unclear why this should not include the full pause. We will
2866 // investigate this in CR 7178365.
2867 //
2868 // Preserving the old comment here if that helps the investigation:
2869 //
2870 // The elapsed time induced by the start time below deliberately elides
2871 // the possible verification above.
2872 double sample_start_time_sec = os::elapsedTime();
2873
2874 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2875
2876 if (collector_state()->in_initial_mark_gc()) {
2877 concurrent_mark()->pre_initial_mark();
2878 }
2879
2880 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2881
2882 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2883
2884 // Make sure the remembered sets are up to date. This needs to be
2885 // done before register_humongous_regions_with_cset(), because the
2886 // remembered sets are used there to choose eager reclaim candidates.
2887 // If the remembered sets are not up to date we might miss some
2888 // entries that need to be handled.
2889 g1_rem_set()->cleanupHRRS();
2890
2891 register_humongous_regions_with_cset();
2892
2893 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2894
2895 // We call this after finalize_cset() to
2896 // ensure that the CSet has been finalized.
2897 _cm->verify_no_cset_oops();
2898
2899 if (_hr_printer.is_active()) {
2900 G1PrintCollectionSetClosure cl(&_hr_printer);
2901 _collection_set.iterate(&cl);
2902 }
2903
2904 // Initialize the GC alloc regions.
2905 _allocator->init_gc_alloc_regions(evacuation_info);
2906
2907 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2908 pre_evacuate_collection_set();
2909
2910 // Actually do the work...
2911 evacuate_collection_set(&per_thread_states);
2912
2913 post_evacuate_collection_set(evacuation_info, &per_thread_states);
2914
2915 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2916 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2917
2918 eagerly_reclaim_humongous_regions();
2919
2920 record_obj_copy_mem_stats();
2921 _survivor_evac_stats.adjust_desired_plab_sz();
2922 _old_evac_stats.adjust_desired_plab_sz();
2923
2924 double start = os::elapsedTime();
2925 start_new_collection_set();
2926 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2927
2928 if (evacuation_failed()) {
2929 set_used(recalculate_used());
2930 if (_archive_allocator != NULL) {
2931 _archive_allocator->clear_used();
2932 }
2933 for (uint i = 0; i < ParallelGCThreads; i++) {
2934 if (_evacuation_failed_info_array[i].has_failed()) {
2935 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
2936 }
2937 }
2938 } else {
2939 // The "used" of the the collection set have already been subtracted
2940 // when they were freed. Add in the bytes evacuated.
2941 increase_used(g1_policy()->bytes_copied_during_gc());
2942 }
2943
2944 if (collector_state()->in_initial_mark_gc()) {
2945 // We have to do this before we notify the CM threads that
2946 // they can start working to make sure that all the
2947 // appropriate initialization is done on the CM object.
2948 concurrent_mark()->post_initial_mark();
2949 // Note that we don't actually trigger the CM thread at
2950 // this point. We do that later when we're sure that
2951 // the current thread has completed its logging output.
2952 }
2953
2954 allocate_dummy_regions();
2955
2956 _allocator->init_mutator_alloc_region();
2957
2958 {
2959 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2960 if (expand_bytes > 0) {
2961 size_t bytes_before = capacity();
2962 // No need for an ergo logging here,
2963 // expansion_amount() does this when it returns a value > 0.
2964 double expand_ms;
2965 if (!expand(expand_bytes, _workers, &expand_ms)) {
2966 // We failed to expand the heap. Cannot do anything about it.
2967 }
2968 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
2969 }
2970 }
2971
2972 // We redo the verification but now wrt to the new CSet which
2973 // has just got initialized after the previous CSet was freed.
2974 _cm->verify_no_cset_oops();
2975
2976 // This timing is only used by the ergonomics to handle our pause target.
2977 // It is unclear why this should not include the full pause. We will
2978 // investigate this in CR 7178365.
2979 double sample_end_time_sec = os::elapsedTime();
2980 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
2981 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
2982 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
2983
2984 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
2985 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
2986
2987 if (VerifyRememberedSets) {
2988 log_info(gc, verify)("[Verifying RemSets after GC]");
2989 VerifyRegionRemSetClosure v_cl;
2990 heap_region_iterate(&v_cl);
2991 }
2992
2993 _verifier->verify_after_gc(verify_type);
2994 _verifier->check_bitmaps("GC End");
2995
2996 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
2997 _ref_processor_stw->verify_no_references_recorded();
2998
2999 // CM reference discovery will be re-enabled if necessary.
3000 }
3001
3002 #ifdef TRACESPINNING
3003 ParallelTaskTerminator::print_termination_counts();
3004 #endif
3005
3006 gc_epilogue(false);
3007 }
3008
3009 // Print the remainder of the GC log output.
3010 if (evacuation_failed()) {
3011 log_info(gc)("To-space exhausted");
3012 }
3013
3014 g1_policy()->print_phases();
3015 heap_transition.print();
3016
3017 // It is not yet to safe to tell the concurrent mark to
3018 // start as we have some optional output below. We don't want the
3019 // output from the concurrent mark thread interfering with this
3020 // logging output either.
3021
3022 _hrm.verify_optional();
3023 _verifier->verify_region_sets_optional();
3024
3025 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3026 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3027
3028 print_heap_after_gc();
3029 print_heap_regions();
3030 trace_heap_after_gc(_gc_tracer_stw);
3031
3032 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3033 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3034 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3035 // before any GC notifications are raised.
3036 g1mm()->update_sizes();
3037
3038 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3039 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3040 _gc_timer_stw->register_gc_end();
3041 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3042 }
3043 // It should now be safe to tell the concurrent mark thread to start
3044 // without its logging output interfering with the logging output
3045 // that came from the pause.
3046
3047 if (should_start_conc_mark) {
3048 // CAUTION: after the doConcurrentMark() call below,
3049 // the concurrent marking thread(s) could be running
3050 // concurrently with us. Make sure that anything after
3051 // this point does not assume that we are the only GC thread
3052 // running. Note: of course, the actual marking work will
3053 // not start until the safepoint itself is released in
3054 // SuspendibleThreadSet::desynchronize().
3055 do_concurrent_mark();
3056 }
3057
3058 return true;
3059 }
3060
3061 void G1CollectedHeap::remove_self_forwarding_pointers() {
3062 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3063 workers()->run_task(&rsfp_task);
3064 }
3065
3066 void G1CollectedHeap::restore_after_evac_failure() {
3067 double remove_self_forwards_start = os::elapsedTime();
3068
3069 remove_self_forwarding_pointers();
3070 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3071 _preserved_marks_set.restore(&task_executor);
3072
3073 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3074 }
3075
3076 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3077 if (!_evacuation_failed) {
3078 _evacuation_failed = true;
3079 }
3080
3081 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3082 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3083 }
3084
3085 bool G1ParEvacuateFollowersClosure::offer_termination() {
3086 G1ParScanThreadState* const pss = par_scan_state();
3087 start_term_time();
3088 const bool res = terminator()->offer_termination();
3089 end_term_time();
3090 return res;
3091 }
3092
3093 void G1ParEvacuateFollowersClosure::do_void() {
3094 G1ParScanThreadState* const pss = par_scan_state();
3095 pss->trim_queue();
3096 do {
3097 pss->steal_and_trim_queue(queues());
3098 } while (!offer_termination());
3099 }
3100
3101 class G1ParTask : public AbstractGangTask {
3102 protected:
3103 G1CollectedHeap* _g1h;
3104 G1ParScanThreadStateSet* _pss;
3105 RefToScanQueueSet* _queues;
3106 G1RootProcessor* _root_processor;
3107 ParallelTaskTerminator _terminator;
3108 uint _n_workers;
3109
3110 public:
3111 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3112 : AbstractGangTask("G1 collection"),
3113 _g1h(g1h),
3114 _pss(per_thread_states),
3115 _queues(task_queues),
3116 _root_processor(root_processor),
3117 _terminator(n_workers, _queues),
3118 _n_workers(n_workers)
3119 {}
3120
3121 void work(uint worker_id) {
3122 if (worker_id >= _n_workers) return; // no work needed this round
3123
3124 double start_sec = os::elapsedTime();
3125 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3126
3127 {
3128 ResourceMark rm;
3129 HandleMark hm;
3130
3131 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3132
3133 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3134 pss->set_ref_discoverer(rp);
3135
3136 double start_strong_roots_sec = os::elapsedTime();
3137
3138 _root_processor->evacuate_roots(pss, worker_id);
3139
3140 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3141 // treating the nmethods visited to act as roots for concurrent marking.
3142 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3143 // objects copied by the current evacuation.
3144 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3145
3146 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3147
3148 double term_sec = 0.0;
3149 size_t evac_term_attempts = 0;
3150 {
3151 double start = os::elapsedTime();
3152 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3153 evac.do_void();
3154
3155 evac_term_attempts = evac.term_attempts();
3156 term_sec = evac.term_time();
3157 double elapsed_sec = os::elapsedTime() - start;
3158
3159 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3160 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3161 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3162 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3163 }
3164
3165 assert(pss->queue_is_empty(), "should be empty");
3166
3167 if (log_is_enabled(Debug, gc, task, stats)) {
3168 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3169 size_t lab_waste;
3170 size_t lab_undo_waste;
3171 pss->waste(lab_waste, lab_undo_waste);
3172 _g1h->print_termination_stats(worker_id,
3173 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3174 strong_roots_sec * 1000.0, /* strong roots time */
3175 term_sec * 1000.0, /* evac term time */
3176 evac_term_attempts, /* evac term attempts */
3177 lab_waste, /* alloc buffer waste */
3178 lab_undo_waste /* undo waste */
3179 );
3180 }
3181
3182 // Close the inner scope so that the ResourceMark and HandleMark
3183 // destructors are executed here and are included as part of the
3184 // "GC Worker Time".
3185 }
3186 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3187 }
3188 };
3189
3190 void G1CollectedHeap::print_termination_stats_hdr() {
3191 log_debug(gc, task, stats)("GC Termination Stats");
3192 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3193 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3194 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3195 }
3196
3197 void G1CollectedHeap::print_termination_stats(uint worker_id,
3198 double elapsed_ms,
3199 double strong_roots_ms,
3200 double term_ms,
3201 size_t term_attempts,
3202 size_t alloc_buffer_waste,
3203 size_t undo_waste) const {
3204 log_debug(gc, task, stats)
3205 ("%3d %9.2f %9.2f %6.2f "
3206 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3207 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3208 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3209 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3210 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3211 alloc_buffer_waste * HeapWordSize / K,
3212 undo_waste * HeapWordSize / K);
3213 }
3214
3215 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3216 private:
3217 BoolObjectClosure* _is_alive;
3218 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3219 OopStorage::ParState<false /* concurrent */, false /* const */> _par_state_string;
3220
3221 int _initial_string_table_size;
3222 int _initial_symbol_table_size;
3223
3224 bool _process_strings;
3225 int _strings_processed;
3226 int _strings_removed;
3227
3228 bool _process_symbols;
3229 int _symbols_processed;
3230 int _symbols_removed;
3231
3232 bool _process_string_dedup;
3233
3234 public:
3235 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3236 AbstractGangTask("String/Symbol Unlinking"),
3237 _is_alive(is_alive),
3238 _dedup_closure(is_alive, NULL, false),
3239 _par_state_string(StringTable::weak_storage()),
3240 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3241 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3242 _process_string_dedup(process_string_dedup) {
3243
3244 _initial_string_table_size = (int) StringTable::the_table()->table_size();
3245 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3246 if (process_symbols) {
3247 SymbolTable::clear_parallel_claimed_index();
3248 }
3249 }
3250
3251 ~G1StringAndSymbolCleaningTask() {
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(&_par_state_string, _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();
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 volatile int _clean_klass_tree_claimed;
3463 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3464
3465 public:
3466 G1KlassCleaningTask() :
3467 _clean_klass_tree_claimed(0),
3468 _klass_iterator() {
3469 }
3470
3471 private:
3472 bool claim_clean_klass_tree_task() {
3473 if (_clean_klass_tree_claimed) {
3474 return false;
3475 }
3476
3477 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3478 }
3479
3480 InstanceKlass* claim_next_klass() {
3481 Klass* klass;
3482 do {
3483 klass =_klass_iterator.next_klass();
3484 } while (klass != NULL && !klass->is_instance_klass());
3485
3486 // this can be null so don't call InstanceKlass::cast
3487 return static_cast<InstanceKlass*>(klass);
3488 }
3489
3490 public:
3491
3492 void clean_klass(InstanceKlass* ik) {
3493 ik->clean_weak_instanceklass_links();
3494 }
3495
3496 void work() {
3497 ResourceMark rm;
3498
3499 // One worker will clean the subklass/sibling klass tree.
3500 if (claim_clean_klass_tree_task()) {
3501 Klass::clean_subklass_tree();
3502 }
3503
3504 // All workers will help cleaning the classes,
3505 InstanceKlass* klass;
3506 while ((klass = claim_next_klass()) != NULL) {
3507 clean_klass(klass);
3508 }
3509 }
3510 };
3511
3512 class G1ResolvedMethodCleaningTask : public StackObj {
3513 volatile int _resolved_method_task_claimed;
3514 public:
3515 G1ResolvedMethodCleaningTask() :
3516 _resolved_method_task_claimed(0) {}
3517
3518 bool claim_resolved_method_task() {
3519 if (_resolved_method_task_claimed) {
3520 return false;
3521 }
3522 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3523 }
3524
3525 // These aren't big, one thread can do it all.
3526 void work() {
3527 if (claim_resolved_method_task()) {
3528 ResolvedMethodTable::unlink();
3529 }
3530 }
3531 };
3532
3533
3534 // To minimize the remark pause times, the tasks below are done in parallel.
3535 class G1ParallelCleaningTask : public AbstractGangTask {
3536 private:
3537 bool _unloading_occurred;
3538 G1StringAndSymbolCleaningTask _string_symbol_task;
3539 G1CodeCacheUnloadingTask _code_cache_task;
3540 G1KlassCleaningTask _klass_cleaning_task;
3541 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3542
3543 public:
3544 // The constructor is run in the VMThread.
3545 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3546 AbstractGangTask("Parallel Cleaning"),
3547 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3548 _code_cache_task(num_workers, is_alive, unloading_occurred),
3549 _klass_cleaning_task(),
3550 _unloading_occurred(unloading_occurred),
3551 _resolved_method_cleaning_task() {
3552 }
3553
3554 // The parallel work done by all worker threads.
3555 void work(uint worker_id) {
3556 // Do first pass of code cache cleaning.
3557 _code_cache_task.work_first_pass(worker_id);
3558
3559 // Let the threads mark that the first pass is done.
3560 _code_cache_task.barrier_mark(worker_id);
3561
3562 // Clean the Strings and Symbols.
3563 _string_symbol_task.work(worker_id);
3564
3565 // Clean unreferenced things in the ResolvedMethodTable
3566 _resolved_method_cleaning_task.work();
3567
3568 // Wait for all workers to finish the first code cache cleaning pass.
3569 _code_cache_task.barrier_wait(worker_id);
3570
3571 // Do the second code cache cleaning work, which realize on
3572 // the liveness information gathered during the first pass.
3573 _code_cache_task.work_second_pass(worker_id);
3574
3575 // Clean all klasses that were not unloaded.
3576 // The weak metadata in klass doesn't need to be
3577 // processed if there was no unloading.
3578 if (_unloading_occurred) {
3579 _klass_cleaning_task.work();
3580 }
3581 }
3582 };
3583
3584
3585 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3586 bool class_unloading_occurred) {
3587 uint n_workers = workers()->active_workers();
3588
3589 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3590 workers()->run_task(&g1_unlink_task);
3591 }
3592
3593 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3594 bool process_strings,
3595 bool process_symbols,
3596 bool process_string_dedup) {
3597 if (!process_strings && !process_symbols && !process_string_dedup) {
3598 // Nothing to clean.
3599 return;
3600 }
3601
3602 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3603 workers()->run_task(&g1_unlink_task);
3604
3605 }
3606
3607 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3608 private:
3609 DirtyCardQueueSet* _queue;
3610 G1CollectedHeap* _g1h;
3611 public:
3612 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3613 _queue(queue), _g1h(g1h) { }
3614
3615 virtual void work(uint worker_id) {
3616 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3617 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3618
3619 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3620 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3621
3622 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3623 }
3624 };
3625
3626 void G1CollectedHeap::redirty_logged_cards() {
3627 double redirty_logged_cards_start = os::elapsedTime();
3628
3629 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3630 dirty_card_queue_set().reset_for_par_iteration();
3631 workers()->run_task(&redirty_task);
3632
3633 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3634 dcq.merge_bufferlists(&dirty_card_queue_set());
3635 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3636
3637 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3638 }
3639
3640 // Weak Reference Processing support
3641
3642 bool G1STWIsAliveClosure::do_object_b(oop p) {
3643 // An object is reachable if it is outside the collection set,
3644 // or is inside and copied.
3645 return !_g1h->is_in_cset(p) || p->is_forwarded();
3646 }
3647
3648 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3649 assert(obj != NULL, "must not be NULL");
3650 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3651 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3652 // may falsely indicate that this is not the case here: however the collection set only
3653 // contains old regions when concurrent mark is not running.
3654 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3655 }
3656
3657 // Non Copying Keep Alive closure
3658 class G1KeepAliveClosure: public OopClosure {
3659 G1CollectedHeap*_g1h;
3660 public:
3661 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3662 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3663 void do_oop(oop* p) {
3664 oop obj = *p;
3665 assert(obj != NULL, "the caller should have filtered out NULL values");
3666
3667 const InCSetState cset_state =_g1h->in_cset_state(obj);
3668 if (!cset_state.is_in_cset_or_humongous()) {
3669 return;
3670 }
3671 if (cset_state.is_in_cset()) {
3672 assert( obj->is_forwarded(), "invariant" );
3673 *p = obj->forwardee();
3674 } else {
3675 assert(!obj->is_forwarded(), "invariant" );
3676 assert(cset_state.is_humongous(),
3677 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3678 _g1h->set_humongous_is_live(obj);
3679 }
3680 }
3681 };
3682
3683 // Copying Keep Alive closure - can be called from both
3684 // serial and parallel code as long as different worker
3685 // threads utilize different G1ParScanThreadState instances
3686 // and different queues.
3687
3688 class G1CopyingKeepAliveClosure: public OopClosure {
3689 G1CollectedHeap* _g1h;
3690 OopClosure* _copy_non_heap_obj_cl;
3691 G1ParScanThreadState* _par_scan_state;
3692
3693 public:
3694 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3695 OopClosure* non_heap_obj_cl,
3696 G1ParScanThreadState* pss):
3697 _g1h(g1h),
3698 _copy_non_heap_obj_cl(non_heap_obj_cl),
3699 _par_scan_state(pss)
3700 {}
3701
3702 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3703 virtual void do_oop( oop* p) { do_oop_work(p); }
3704
3705 template <class T> void do_oop_work(T* p) {
3706 oop obj = RawAccess<>::oop_load(p);
3707
3708 if (_g1h->is_in_cset_or_humongous(obj)) {
3709 // If the referent object has been forwarded (either copied
3710 // to a new location or to itself in the event of an
3711 // evacuation failure) then we need to update the reference
3712 // field and, if both reference and referent are in the G1
3713 // heap, update the RSet for the referent.
3714 //
3715 // If the referent has not been forwarded then we have to keep
3716 // it alive by policy. Therefore we have copy the referent.
3717 //
3718 // If the reference field is in the G1 heap then we can push
3719 // on the PSS queue. When the queue is drained (after each
3720 // phase of reference processing) the object and it's followers
3721 // will be copied, the reference field set to point to the
3722 // new location, and the RSet updated. Otherwise we need to
3723 // use the the non-heap or metadata closures directly to copy
3724 // the referent object and update the pointer, while avoiding
3725 // updating the RSet.
3726
3727 if (_g1h->is_in_g1_reserved(p)) {
3728 _par_scan_state->push_on_queue(p);
3729 } else {
3730 assert(!Metaspace::contains((const void*)p),
3731 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3732 _copy_non_heap_obj_cl->do_oop(p);
3733 }
3734 }
3735 }
3736 };
3737
3738 // Serial drain queue closure. Called as the 'complete_gc'
3739 // closure for each discovered list in some of the
3740 // reference processing phases.
3741
3742 class G1STWDrainQueueClosure: public VoidClosure {
3743 protected:
3744 G1CollectedHeap* _g1h;
3745 G1ParScanThreadState* _par_scan_state;
3746
3747 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3748
3749 public:
3750 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3751 _g1h(g1h),
3752 _par_scan_state(pss)
3753 { }
3754
3755 void do_void() {
3756 G1ParScanThreadState* const pss = par_scan_state();
3757 pss->trim_queue();
3758 }
3759 };
3760
3761 // Parallel Reference Processing closures
3762
3763 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3764 // processing during G1 evacuation pauses.
3765
3766 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3767 private:
3768 G1CollectedHeap* _g1h;
3769 G1ParScanThreadStateSet* _pss;
3770 RefToScanQueueSet* _queues;
3771 WorkGang* _workers;
3772 uint _active_workers;
3773
3774 public:
3775 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3776 G1ParScanThreadStateSet* per_thread_states,
3777 WorkGang* workers,
3778 RefToScanQueueSet *task_queues,
3779 uint n_workers) :
3780 _g1h(g1h),
3781 _pss(per_thread_states),
3782 _queues(task_queues),
3783 _workers(workers),
3784 _active_workers(n_workers)
3785 {
3786 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3787 }
3788
3789 // Executes the given task using concurrent marking worker threads.
3790 virtual void execute(ProcessTask& task);
3791 };
3792
3793 // Gang task for possibly parallel reference processing
3794
3795 class G1STWRefProcTaskProxy: public AbstractGangTask {
3796 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3797 ProcessTask& _proc_task;
3798 G1CollectedHeap* _g1h;
3799 G1ParScanThreadStateSet* _pss;
3800 RefToScanQueueSet* _task_queues;
3801 ParallelTaskTerminator* _terminator;
3802
3803 public:
3804 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3805 G1CollectedHeap* g1h,
3806 G1ParScanThreadStateSet* per_thread_states,
3807 RefToScanQueueSet *task_queues,
3808 ParallelTaskTerminator* terminator) :
3809 AbstractGangTask("Process reference objects in parallel"),
3810 _proc_task(proc_task),
3811 _g1h(g1h),
3812 _pss(per_thread_states),
3813 _task_queues(task_queues),
3814 _terminator(terminator)
3815 {}
3816
3817 virtual void work(uint worker_id) {
3818 // The reference processing task executed by a single worker.
3819 ResourceMark rm;
3820 HandleMark hm;
3821
3822 G1STWIsAliveClosure is_alive(_g1h);
3823
3824 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3825 pss->set_ref_discoverer(NULL);
3826
3827 // Keep alive closure.
3828 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3829
3830 // Complete GC closure
3831 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3832
3833 // Call the reference processing task's work routine.
3834 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3835
3836 // Note we cannot assert that the refs array is empty here as not all
3837 // of the processing tasks (specifically phase2 - pp2_work) execute
3838 // the complete_gc closure (which ordinarily would drain the queue) so
3839 // the queue may not be empty.
3840 }
3841 };
3842
3843 // Driver routine for parallel reference processing.
3844 // Creates an instance of the ref processing gang
3845 // task and has the worker threads execute it.
3846 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3847 assert(_workers != NULL, "Need parallel worker threads.");
3848
3849 ParallelTaskTerminator terminator(_active_workers, _queues);
3850 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3851
3852 _workers->run_task(&proc_task_proxy);
3853 }
3854
3855 // End of weak reference support closures
3856
3857 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3858 double ref_proc_start = os::elapsedTime();
3859
3860 ReferenceProcessor* rp = _ref_processor_stw;
3861 assert(rp->discovery_enabled(), "should have been enabled");
3862
3863 // Closure to test whether a referent is alive.
3864 G1STWIsAliveClosure is_alive(this);
3865
3866 // Even when parallel reference processing is enabled, the processing
3867 // of JNI refs is serial and performed serially by the current thread
3868 // rather than by a worker. The following PSS will be used for processing
3869 // JNI refs.
3870
3871 // Use only a single queue for this PSS.
3872 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3873 pss->set_ref_discoverer(NULL);
3874 assert(pss->queue_is_empty(), "pre-condition");
3875
3876 // Keep alive closure.
3877 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
3878
3879 // Serial Complete GC closure
3880 G1STWDrainQueueClosure drain_queue(this, pss);
3881
3882 // Setup the soft refs policy...
3883 rp->setup_policy(false);
3884
3885 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3886
3887 ReferenceProcessorStats stats;
3888 if (!rp->processing_is_mt()) {
3889 // Serial reference processing...
3890 stats = rp->process_discovered_references(&is_alive,
3891 &keep_alive,
3892 &drain_queue,
3893 NULL,
3894 pt);
3895 } else {
3896 uint no_of_gc_workers = workers()->active_workers();
3897
3898 // Parallel reference processing
3899 assert(no_of_gc_workers <= rp->max_num_queues(),
3900 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3901 no_of_gc_workers, rp->max_num_queues());
3902
3903 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
3904 stats = rp->process_discovered_references(&is_alive,
3905 &keep_alive,
3906 &drain_queue,
3907 &par_task_executor,
3908 pt);
3909 }
3910
3911 _gc_tracer_stw->report_gc_reference_stats(stats);
3912
3913 // We have completed copying any necessary live referent objects.
3914 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3915
3916 make_pending_list_reachable();
3917
3918 rp->verify_no_references_recorded();
3919
3920 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3921 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3922 }
3923
3924 void G1CollectedHeap::make_pending_list_reachable() {
3925 if (collector_state()->in_initial_mark_gc()) {
3926 oop pll_head = Universe::reference_pending_list();
3927 if (pll_head != NULL) {
3928 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3929 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3930 }
3931 }
3932 }
3933
3934 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3935 double merge_pss_time_start = os::elapsedTime();
3936 per_thread_states->flush();
3937 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3938 }
3939
3940 void G1CollectedHeap::pre_evacuate_collection_set() {
3941 _expand_heap_after_alloc_failure = true;
3942 _evacuation_failed = false;
3943
3944 // Disable the hot card cache.
3945 _hot_card_cache->reset_hot_cache_claimed_index();
3946 _hot_card_cache->set_use_cache(false);
3947
3948 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3949 _preserved_marks_set.assert_empty();
3950
3951 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3952
3953 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3954 if (collector_state()->in_initial_mark_gc()) {
3955 double start_clear_claimed_marks = os::elapsedTime();
3956
3957 ClassLoaderDataGraph::clear_claimed_marks();
3958
3959 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3960 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3961 }
3962 }
3963
3964 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3965 // Should G1EvacuationFailureALot be in effect for this GC?
3966 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3967
3968 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3969
3970 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3971
3972 double start_par_time_sec = os::elapsedTime();
3973 double end_par_time_sec;
3974
3975 {
3976 const uint n_workers = workers()->active_workers();
3977 G1RootProcessor root_processor(this, n_workers);
3978 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3979
3980 print_termination_stats_hdr();
3981
3982 workers()->run_task(&g1_par_task);
3983 end_par_time_sec = os::elapsedTime();
3984
3985 // Closing the inner scope will execute the destructor
3986 // for the G1RootProcessor object. We record the current
3987 // elapsed time before closing the scope so that time
3988 // taken for the destructor is NOT included in the
3989 // reported parallel time.
3990 }
3991
3992 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3993 phase_times->record_par_time(par_time_ms);
3994
3995 double code_root_fixup_time_ms =
3996 (os::elapsedTime() - end_par_time_sec) * 1000.0;
3997 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3998 }
3999
4000 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4001 // Also cleans the card table from temporary duplicate detection information used
4002 // during UpdateRS/ScanRS.
4003 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4004
4005 // Process any discovered reference objects - we have
4006 // to do this _before_ we retire the GC alloc regions
4007 // as we may have to copy some 'reachable' referent
4008 // objects (and their reachable sub-graphs) that were
4009 // not copied during the pause.
4010 process_discovered_references(per_thread_states);
4011
4012 // FIXME
4013 // CM's reference processing also cleans up the string and symbol tables.
4014 // Should we do that here also? We could, but it is a serial operation
4015 // and could significantly increase the pause time.
4016
4017 G1STWIsAliveClosure is_alive(this);
4018 G1KeepAliveClosure keep_alive(this);
4019
4020 {
4021 double start = os::elapsedTime();
4022
4023 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4024
4025 double time_ms = (os::elapsedTime() - start) * 1000.0;
4026 g1_policy()->phase_times()->record_weak_ref_proc_time(time_ms);
4027 }
4028
4029 if (G1StringDedup::is_enabled()) {
4030 double fixup_start = os::elapsedTime();
4031
4032 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4033
4034 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4035 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4036 }
4037
4038 if (evacuation_failed()) {
4039 restore_after_evac_failure();
4040
4041 // Reset the G1EvacuationFailureALot counters and flags
4042 // Note: the values are reset only when an actual
4043 // evacuation failure occurs.
4044 NOT_PRODUCT(reset_evacuation_should_fail();)
4045 }
4046
4047 _preserved_marks_set.assert_empty();
4048
4049 _allocator->release_gc_alloc_regions(evacuation_info);
4050
4051 merge_per_thread_state_info(per_thread_states);
4052
4053 // Reset and re-enable the hot card cache.
4054 // Note the counts for the cards in the regions in the
4055 // collection set are reset when the collection set is freed.
4056 _hot_card_cache->reset_hot_cache();
4057 _hot_card_cache->set_use_cache(true);
4058
4059 purge_code_root_memory();
4060
4061 redirty_logged_cards();
4062 #if COMPILER2_OR_JVMCI
4063 double start = os::elapsedTime();
4064 DerivedPointerTable::update_pointers();
4065 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4066 #endif
4067 g1_policy()->print_age_table();
4068 }
4069
4070 void G1CollectedHeap::record_obj_copy_mem_stats() {
4071 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4072
4073 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4074 create_g1_evac_summary(&_old_evac_stats));
4075 }
4076
4077 void G1CollectedHeap::free_region(HeapRegion* hr,
4078 FreeRegionList* free_list,
4079 bool skip_remset,
4080 bool skip_hot_card_cache,
4081 bool locked) {
4082 assert(!hr->is_free(), "the region should not be free");
4083 assert(!hr->is_empty(), "the region should not be empty");
4084 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4085 assert(free_list != NULL, "pre-condition");
4086
4087 if (G1VerifyBitmaps) {
4088 MemRegion mr(hr->bottom(), hr->end());
4089 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4090 }
4091
4092 // Clear the card counts for this region.
4093 // Note: we only need to do this if the region is not young
4094 // (since we don't refine cards in young regions).
4095 if (!skip_hot_card_cache && !hr->is_young()) {
4096 _hot_card_cache->reset_card_counts(hr);
4097 }
4098 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4099 _g1_policy->remset_tracker()->update_at_free(hr);
4100 free_list->add_ordered(hr);
4101 }
4102
4103 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4104 FreeRegionList* free_list) {
4105 assert(hr->is_humongous(), "this is only for humongous regions");
4106 assert(free_list != NULL, "pre-condition");
4107 hr->clear_humongous();
4108 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4109 }
4110
4111 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4112 const uint humongous_regions_removed) {
4113 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4114 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4115 _old_set.bulk_remove(old_regions_removed);
4116 _humongous_set.bulk_remove(humongous_regions_removed);
4117 }
4118
4119 }
4120
4121 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4122 assert(list != NULL, "list can't be null");
4123 if (!list->is_empty()) {
4124 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4125 _hrm.insert_list_into_free_list(list);
4126 }
4127 }
4128
4129 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4130 decrease_used(bytes);
4131 }
4132
4133 class G1FreeCollectionSetTask : public AbstractGangTask {
4134 private:
4135
4136 // Closure applied to all regions in the collection set to do work that needs to
4137 // be done serially in a single thread.
4138 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4139 private:
4140 EvacuationInfo* _evacuation_info;
4141 const size_t* _surviving_young_words;
4142
4143 // Bytes used in successfully evacuated regions before the evacuation.
4144 size_t _before_used_bytes;
4145 // Bytes used in unsucessfully evacuated regions before the evacuation
4146 size_t _after_used_bytes;
4147
4148 size_t _bytes_allocated_in_old_since_last_gc;
4149
4150 size_t _failure_used_words;
4151 size_t _failure_waste_words;
4152
4153 FreeRegionList _local_free_list;
4154 public:
4155 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4156 HeapRegionClosure(),
4157 _evacuation_info(evacuation_info),
4158 _surviving_young_words(surviving_young_words),
4159 _before_used_bytes(0),
4160 _after_used_bytes(0),
4161 _bytes_allocated_in_old_since_last_gc(0),
4162 _failure_used_words(0),
4163 _failure_waste_words(0),
4164 _local_free_list("Local Region List for CSet Freeing") {
4165 }
4166
4167 virtual bool do_heap_region(HeapRegion* r) {
4168 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4169
4170 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4171 g1h->clear_in_cset(r);
4172
4173 if (r->is_young()) {
4174 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4175 "Young index %d is wrong for region %u of type %s with %u young regions",
4176 r->young_index_in_cset(),
4177 r->hrm_index(),
4178 r->get_type_str(),
4179 g1h->collection_set()->young_region_length());
4180 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4181 r->record_surv_words_in_group(words_survived);
4182 }
4183
4184 if (!r->evacuation_failed()) {
4185 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4186 _before_used_bytes += r->used();
4187 g1h->free_region(r,
4188 &_local_free_list,
4189 true, /* skip_remset */
4190 true, /* skip_hot_card_cache */
4191 true /* locked */);
4192 } else {
4193 r->uninstall_surv_rate_group();
4194 r->set_young_index_in_cset(-1);
4195 r->set_evacuation_failed(false);
4196 // When moving a young gen region to old gen, we "allocate" that whole region
4197 // there. This is in addition to any already evacuated objects. Notify the
4198 // policy about that.
4199 // Old gen regions do not cause an additional allocation: both the objects
4200 // still in the region and the ones already moved are accounted for elsewhere.
4201 if (r->is_young()) {
4202 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4203 }
4204 // The region is now considered to be old.
4205 r->set_old();
4206 // Do some allocation statistics accounting. Regions that failed evacuation
4207 // are always made old, so there is no need to update anything in the young
4208 // gen statistics, but we need to update old gen statistics.
4209 size_t used_words = r->marked_bytes() / HeapWordSize;
4210
4211 _failure_used_words += used_words;
4212 _failure_waste_words += HeapRegion::GrainWords - used_words;
4213
4214 g1h->old_set_add(r);
4215 _after_used_bytes += r->used();
4216 }
4217 return false;
4218 }
4219
4220 void complete_work() {
4221 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4222
4223 _evacuation_info->set_regions_freed(_local_free_list.length());
4224 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4225
4226 g1h->prepend_to_freelist(&_local_free_list);
4227 g1h->decrement_summary_bytes(_before_used_bytes);
4228
4229 G1Policy* policy = g1h->g1_policy();
4230 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4231
4232 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4233 }
4234 };
4235
4236 G1CollectionSet* _collection_set;
4237 G1SerialFreeCollectionSetClosure _cl;
4238 const size_t* _surviving_young_words;
4239
4240 size_t _rs_lengths;
4241
4242 volatile jint _serial_work_claim;
4243
4244 struct WorkItem {
4245 uint region_idx;
4246 bool is_young;
4247 bool evacuation_failed;
4248
4249 WorkItem(HeapRegion* r) {
4250 region_idx = r->hrm_index();
4251 is_young = r->is_young();
4252 evacuation_failed = r->evacuation_failed();
4253 }
4254 };
4255
4256 volatile size_t _parallel_work_claim;
4257 size_t _num_work_items;
4258 WorkItem* _work_items;
4259
4260 void do_serial_work() {
4261 // Need to grab the lock to be allowed to modify the old region list.
4262 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4263 _collection_set->iterate(&_cl);
4264 }
4265
4266 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4267 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4268
4269 HeapRegion* r = g1h->region_at(region_idx);
4270 assert(!g1h->is_on_master_free_list(r), "sanity");
4271
4272 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4273
4274 if (!is_young) {
4275 g1h->_hot_card_cache->reset_card_counts(r);
4276 }
4277
4278 if (!evacuation_failed) {
4279 r->rem_set()->clear_locked();
4280 }
4281 }
4282
4283 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4284 private:
4285 size_t _cur_idx;
4286 WorkItem* _work_items;
4287 public:
4288 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4289
4290 virtual bool do_heap_region(HeapRegion* r) {
4291 _work_items[_cur_idx++] = WorkItem(r);
4292 return false;
4293 }
4294 };
4295
4296 void prepare_work() {
4297 G1PrepareFreeCollectionSetClosure cl(_work_items);
4298 _collection_set->iterate(&cl);
4299 }
4300
4301 void complete_work() {
4302 _cl.complete_work();
4303
4304 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4305 policy->record_max_rs_lengths(_rs_lengths);
4306 policy->cset_regions_freed();
4307 }
4308 public:
4309 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4310 AbstractGangTask("G1 Free Collection Set"),
4311 _cl(evacuation_info, surviving_young_words),
4312 _collection_set(collection_set),
4313 _surviving_young_words(surviving_young_words),
4314 _serial_work_claim(0),
4315 _rs_lengths(0),
4316 _parallel_work_claim(0),
4317 _num_work_items(collection_set->region_length()),
4318 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4319 prepare_work();
4320 }
4321
4322 ~G1FreeCollectionSetTask() {
4323 complete_work();
4324 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4325 }
4326
4327 // Chunk size for work distribution. The chosen value has been determined experimentally
4328 // to be a good tradeoff between overhead and achievable parallelism.
4329 static uint chunk_size() { return 32; }
4330
4331 virtual void work(uint worker_id) {
4332 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4333
4334 // Claim serial work.
4335 if (_serial_work_claim == 0) {
4336 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4337 if (value == 0) {
4338 double serial_time = os::elapsedTime();
4339 do_serial_work();
4340 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4341 }
4342 }
4343
4344 // Start parallel work.
4345 double young_time = 0.0;
4346 bool has_young_time = false;
4347 double non_young_time = 0.0;
4348 bool has_non_young_time = false;
4349
4350 while (true) {
4351 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4352 size_t cur = end - chunk_size();
4353
4354 if (cur >= _num_work_items) {
4355 break;
4356 }
4357
4358 double start_time = os::elapsedTime();
4359
4360 end = MIN2(end, _num_work_items);
4361
4362 for (; cur < end; cur++) {
4363 bool is_young = _work_items[cur].is_young;
4364
4365 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4366
4367 double end_time = os::elapsedTime();
4368 double time_taken = end_time - start_time;
4369 if (is_young) {
4370 young_time += time_taken;
4371 has_young_time = true;
4372 } else {
4373 non_young_time += time_taken;
4374 has_non_young_time = true;
4375 }
4376 start_time = end_time;
4377 }
4378 }
4379
4380 if (has_young_time) {
4381 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4382 }
4383 if (has_non_young_time) {
4384 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4385 }
4386 }
4387 };
4388
4389 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4390 _eden.clear();
4391
4392 double free_cset_start_time = os::elapsedTime();
4393
4394 {
4395 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4396 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4397
4398 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4399
4400 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4401 cl.name(),
4402 num_workers,
4403 _collection_set.region_length());
4404 workers()->run_task(&cl, num_workers);
4405 }
4406 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4407
4408 collection_set->clear();
4409 }
4410
4411 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4412 private:
4413 FreeRegionList* _free_region_list;
4414 HeapRegionSet* _proxy_set;
4415 uint _humongous_objects_reclaimed;
4416 uint _humongous_regions_reclaimed;
4417 size_t _freed_bytes;
4418 public:
4419
4420 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4421 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4422 }
4423
4424 virtual bool do_heap_region(HeapRegion* r) {
4425 if (!r->is_starts_humongous()) {
4426 return false;
4427 }
4428
4429 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4430
4431 oop obj = (oop)r->bottom();
4432 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4433
4434 // The following checks whether the humongous object is live are sufficient.
4435 // The main additional check (in addition to having a reference from the roots
4436 // or the young gen) is whether the humongous object has a remembered set entry.
4437 //
4438 // A humongous object cannot be live if there is no remembered set for it
4439 // because:
4440 // - there can be no references from within humongous starts regions referencing
4441 // the object because we never allocate other objects into them.
4442 // (I.e. there are no intra-region references that may be missed by the
4443 // remembered set)
4444 // - as soon there is a remembered set entry to the humongous starts region
4445 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4446 // until the end of a concurrent mark.
4447 //
4448 // It is not required to check whether the object has been found dead by marking
4449 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4450 // all objects allocated during that time are considered live.
4451 // SATB marking is even more conservative than the remembered set.
4452 // So if at this point in the collection there is no remembered set entry,
4453 // nobody has a reference to it.
4454 // At the start of collection we flush all refinement logs, and remembered sets
4455 // are completely up-to-date wrt to references to the humongous object.
4456 //
4457 // Other implementation considerations:
4458 // - never consider object arrays at this time because they would pose
4459 // considerable effort for cleaning up the the remembered sets. This is
4460 // required because stale remembered sets might reference locations that
4461 // are currently allocated into.
4462 uint region_idx = r->hrm_index();
4463 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4464 !r->rem_set()->is_empty()) {
4465 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",
4466 region_idx,
4467 (size_t)obj->size() * HeapWordSize,
4468 p2i(r->bottom()),
4469 r->rem_set()->occupied(),
4470 r->rem_set()->strong_code_roots_list_length(),
4471 next_bitmap->is_marked(r->bottom()),
4472 g1h->is_humongous_reclaim_candidate(region_idx),
4473 obj->is_typeArray()
4474 );
4475 return false;
4476 }
4477
4478 guarantee(obj->is_typeArray(),
4479 "Only eagerly reclaiming type arrays is supported, but the object "
4480 PTR_FORMAT " is not.", p2i(r->bottom()));
4481
4482 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",
4483 region_idx,
4484 (size_t)obj->size() * HeapWordSize,
4485 p2i(r->bottom()),
4486 r->rem_set()->occupied(),
4487 r->rem_set()->strong_code_roots_list_length(),
4488 next_bitmap->is_marked(r->bottom()),
4489 g1h->is_humongous_reclaim_candidate(region_idx),
4490 obj->is_typeArray()
4491 );
4492
4493 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4494 cm->humongous_object_eagerly_reclaimed(r);
4495 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4496 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4497 region_idx,
4498 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4499 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4500 _humongous_objects_reclaimed++;
4501 do {
4502 HeapRegion* next = g1h->next_region_in_humongous(r);
4503 _freed_bytes += r->used();
4504 r->set_containing_set(NULL);
4505 _humongous_regions_reclaimed++;
4506 g1h->free_humongous_region(r, _free_region_list);
4507 r = next;
4508 } while (r != NULL);
4509
4510 return false;
4511 }
4512
4513 uint humongous_objects_reclaimed() {
4514 return _humongous_objects_reclaimed;
4515 }
4516
4517 uint humongous_regions_reclaimed() {
4518 return _humongous_regions_reclaimed;
4519 }
4520
4521 size_t bytes_freed() const {
4522 return _freed_bytes;
4523 }
4524 };
4525
4526 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4527 assert_at_safepoint_on_vm_thread();
4528
4529 if (!G1EagerReclaimHumongousObjects ||
4530 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4531 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4532 return;
4533 }
4534
4535 double start_time = os::elapsedTime();
4536
4537 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4538
4539 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4540 heap_region_iterate(&cl);
4541
4542 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4543
4544 G1HRPrinter* hrp = hr_printer();
4545 if (hrp->is_active()) {
4546 FreeRegionListIterator iter(&local_cleanup_list);
4547 while (iter.more_available()) {
4548 HeapRegion* hr = iter.get_next();
4549 hrp->cleanup(hr);
4550 }
4551 }
4552
4553 prepend_to_freelist(&local_cleanup_list);
4554 decrement_summary_bytes(cl.bytes_freed());
4555
4556 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4557 cl.humongous_objects_reclaimed());
4558 }
4559
4560 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4561 public:
4562 virtual bool do_heap_region(HeapRegion* r) {
4563 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4564 G1CollectedHeap::heap()->clear_in_cset(r);
4565 r->set_young_index_in_cset(-1);
4566 return false;
4567 }
4568 };
4569
4570 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4571 G1AbandonCollectionSetClosure cl;
4572 collection_set->iterate(&cl);
4573
4574 collection_set->clear();
4575 collection_set->stop_incremental_building();
4576 }
4577
4578 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4579 return _allocator->is_retained_old_region(hr);
4580 }
4581
4582 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4583 _eden.add(hr);
4584 _g1_policy->set_region_eden(hr);
4585 }
4586
4587 #ifdef ASSERT
4588
4589 class NoYoungRegionsClosure: public HeapRegionClosure {
4590 private:
4591 bool _success;
4592 public:
4593 NoYoungRegionsClosure() : _success(true) { }
4594 bool do_heap_region(HeapRegion* r) {
4595 if (r->is_young()) {
4596 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4597 p2i(r->bottom()), p2i(r->end()));
4598 _success = false;
4599 }
4600 return false;
4601 }
4602 bool success() { return _success; }
4603 };
4604
4605 bool G1CollectedHeap::check_young_list_empty() {
4606 bool ret = (young_regions_count() == 0);
4607
4608 NoYoungRegionsClosure closure;
4609 heap_region_iterate(&closure);
4610 ret = ret && closure.success();
4611
4612 return ret;
4613 }
4614
4615 #endif // ASSERT
4616
4617 class TearDownRegionSetsClosure : public HeapRegionClosure {
4618 private:
4619 HeapRegionSet *_old_set;
4620
4621 public:
4622 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4623
4624 bool do_heap_region(HeapRegion* r) {
4625 if (r->is_old()) {
4626 _old_set->remove(r);
4627 } else if(r->is_young()) {
4628 r->uninstall_surv_rate_group();
4629 } else {
4630 // We ignore free regions, we'll empty the free list afterwards.
4631 // We ignore humongous regions, we're not tearing down the
4632 // humongous regions set.
4633 assert(r->is_free() || r->is_humongous(),
4634 "it cannot be another type");
4635 }
4636 return false;
4637 }
4638
4639 ~TearDownRegionSetsClosure() {
4640 assert(_old_set->is_empty(), "post-condition");
4641 }
4642 };
4643
4644 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4645 assert_at_safepoint_on_vm_thread();
4646
4647 if (!free_list_only) {
4648 TearDownRegionSetsClosure cl(&_old_set);
4649 heap_region_iterate(&cl);
4650
4651 // Note that emptying the _young_list is postponed and instead done as
4652 // the first step when rebuilding the regions sets again. The reason for
4653 // this is that during a full GC string deduplication needs to know if
4654 // a collected region was young or old when the full GC was initiated.
4655 }
4656 _hrm.remove_all_free_regions();
4657 }
4658
4659 void G1CollectedHeap::increase_used(size_t bytes) {
4660 _summary_bytes_used += bytes;
4661 }
4662
4663 void G1CollectedHeap::decrease_used(size_t bytes) {
4664 assert(_summary_bytes_used >= bytes,
4665 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4666 _summary_bytes_used, bytes);
4667 _summary_bytes_used -= bytes;
4668 }
4669
4670 void G1CollectedHeap::set_used(size_t bytes) {
4671 _summary_bytes_used = bytes;
4672 }
4673
4674 class RebuildRegionSetsClosure : public HeapRegionClosure {
4675 private:
4676 bool _free_list_only;
4677 HeapRegionSet* _old_set;
4678 HeapRegionManager* _hrm;
4679 size_t _total_used;
4680
4681 public:
4682 RebuildRegionSetsClosure(bool free_list_only,
4683 HeapRegionSet* old_set, HeapRegionManager* hrm) :
4684 _free_list_only(free_list_only),
4685 _old_set(old_set), _hrm(hrm), _total_used(0) {
4686 assert(_hrm->num_free_regions() == 0, "pre-condition");
4687 if (!free_list_only) {
4688 assert(_old_set->is_empty(), "pre-condition");
4689 }
4690 }
4691
4692 bool do_heap_region(HeapRegion* r) {
4693 // After full GC, no region should have a remembered set.
4694 r->rem_set()->clear(true);
4695 if (r->is_empty()) {
4696 // Add free regions to the free list
4697 r->set_free();
4698 _hrm->insert_into_free_list(r);
4699 } else if (!_free_list_only) {
4700
4701 if (r->is_humongous()) {
4702 // We ignore humongous regions. We left the humongous set unchanged.
4703 } else {
4704 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4705 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
4706 r->move_to_old();
4707 _old_set->add(r);
4708 }
4709 _total_used += r->used();
4710 }
4711
4712 return false;
4713 }
4714
4715 size_t total_used() {
4716 return _total_used;
4717 }
4718 };
4719
4720 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4721 assert_at_safepoint_on_vm_thread();
4722
4723 if (!free_list_only) {
4724 _eden.clear();
4725 _survivor.clear();
4726 }
4727
4728 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4729 heap_region_iterate(&cl);
4730
4731 if (!free_list_only) {
4732 set_used(cl.total_used());
4733 if (_archive_allocator != NULL) {
4734 _archive_allocator->clear_used();
4735 }
4736 }
4737 assert(used_unlocked() == recalculate_used(),
4738 "inconsistent used_unlocked(), "
4739 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4740 used_unlocked(), recalculate_used());
4741 }
4742
4743 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4744 HeapRegion* hr = heap_region_containing(p);
4745 return hr->is_in(p);
4746 }
4747
4748 // Methods for the mutator alloc region
4749
4750 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4751 bool force) {
4752 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4753 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4754 if (force || should_allocate) {
4755 HeapRegion* new_alloc_region = new_region(word_size,
4756 false /* is_old */,
4757 false /* do_expand */);
4758 if (new_alloc_region != NULL) {
4759 set_region_short_lived_locked(new_alloc_region);
4760 _hr_printer.alloc(new_alloc_region, !should_allocate);
4761 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4762 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4763 return new_alloc_region;
4764 }
4765 }
4766 return NULL;
4767 }
4768
4769 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4770 size_t allocated_bytes) {
4771 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4772 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4773
4774 collection_set()->add_eden_region(alloc_region);
4775 increase_used(allocated_bytes);
4776 _hr_printer.retire(alloc_region);
4777 // We update the eden sizes here, when the region is retired,
4778 // instead of when it's allocated, since this is the point that its
4779 // used space has been recored in _summary_bytes_used.
4780 g1mm()->update_eden_size();
4781 }
4782
4783 // Methods for the GC alloc regions
4784
4785 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4786 if (dest.is_old()) {
4787 return true;
4788 } else {
4789 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4790 }
4791 }
4792
4793 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4794 assert(FreeList_lock->owned_by_self(), "pre-condition");
4795
4796 if (!has_more_regions(dest)) {
4797 return NULL;
4798 }
4799
4800 const bool is_survivor = dest.is_young();
4801
4802 HeapRegion* new_alloc_region = new_region(word_size,
4803 !is_survivor,
4804 true /* do_expand */);
4805 if (new_alloc_region != NULL) {
4806 if (is_survivor) {
4807 new_alloc_region->set_survivor();
4808 _survivor.add(new_alloc_region);
4809 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4810 } else {
4811 new_alloc_region->set_old();
4812 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4813 }
4814 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4815 _hr_printer.alloc(new_alloc_region);
4816 bool during_im = collector_state()->in_initial_mark_gc();
4817 new_alloc_region->note_start_of_copying(during_im);
4818 return new_alloc_region;
4819 }
4820 return NULL;
4821 }
4822
4823 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4824 size_t allocated_bytes,
4825 InCSetState dest) {
4826 bool during_im = collector_state()->in_initial_mark_gc();
4827 alloc_region->note_end_of_copying(during_im);
4828 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4829 if (dest.is_old()) {
4830 _old_set.add(alloc_region);
4831 }
4832 _hr_printer.retire(alloc_region);
4833 }
4834
4835 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4836 bool expanded = false;
4837 uint index = _hrm.find_highest_free(&expanded);
4838
4839 if (index != G1_NO_HRM_INDEX) {
4840 if (expanded) {
4841 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4842 HeapRegion::GrainWords * HeapWordSize);
4843 }
4844 _hrm.allocate_free_regions_starting_at(index, 1);
4845 return region_at(index);
4846 }
4847 return NULL;
4848 }
4849
4850 // Optimized nmethod scanning
4851
4852 class RegisterNMethodOopClosure: public OopClosure {
4853 G1CollectedHeap* _g1h;
4854 nmethod* _nm;
4855
4856 template <class T> void do_oop_work(T* p) {
4857 T heap_oop = RawAccess<>::oop_load(p);
4858 if (!CompressedOops::is_null(heap_oop)) {
4859 oop obj = CompressedOops::decode_not_null(heap_oop);
4860 HeapRegion* hr = _g1h->heap_region_containing(obj);
4861 assert(!hr->is_continues_humongous(),
4862 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4863 " starting at " HR_FORMAT,
4864 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4865
4866 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4867 hr->add_strong_code_root_locked(_nm);
4868 }
4869 }
4870
4871 public:
4872 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4873 _g1h(g1h), _nm(nm) {}
4874
4875 void do_oop(oop* p) { do_oop_work(p); }
4876 void do_oop(narrowOop* p) { do_oop_work(p); }
4877 };
4878
4879 class UnregisterNMethodOopClosure: public OopClosure {
4880 G1CollectedHeap* _g1h;
4881 nmethod* _nm;
4882
4883 template <class T> void do_oop_work(T* p) {
4884 T heap_oop = RawAccess<>::oop_load(p);
4885 if (!CompressedOops::is_null(heap_oop)) {
4886 oop obj = CompressedOops::decode_not_null(heap_oop);
4887 HeapRegion* hr = _g1h->heap_region_containing(obj);
4888 assert(!hr->is_continues_humongous(),
4889 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4890 " starting at " HR_FORMAT,
4891 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4892
4893 hr->remove_strong_code_root(_nm);
4894 }
4895 }
4896
4897 public:
4898 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4899 _g1h(g1h), _nm(nm) {}
4900
4901 void do_oop(oop* p) { do_oop_work(p); }
4902 void do_oop(narrowOop* p) { do_oop_work(p); }
4903 };
4904
4905 // Returns true if the reference points to an object that
4906 // can move in an incremental collection.
4907 bool G1CollectedHeap::is_scavengable(oop obj) {
4908 HeapRegion* hr = heap_region_containing(obj);
4909 return !hr->is_pinned();
4910 }
4911
4912 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4913 guarantee(nm != NULL, "sanity");
4914 RegisterNMethodOopClosure reg_cl(this, nm);
4915 nm->oops_do(®_cl);
4916 }
4917
4918 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4919 guarantee(nm != NULL, "sanity");
4920 UnregisterNMethodOopClosure reg_cl(this, nm);
4921 nm->oops_do(®_cl, true);
4922 }
4923
4924 void G1CollectedHeap::purge_code_root_memory() {
4925 double purge_start = os::elapsedTime();
4926 G1CodeRootSet::purge();
4927 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4928 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4929 }
4930
4931 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4932 G1CollectedHeap* _g1h;
4933
4934 public:
4935 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4936 _g1h(g1h) {}
4937
4938 void do_code_blob(CodeBlob* cb) {
4939 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4940 if (nm == NULL) {
4941 return;
4942 }
4943
4944 if (ScavengeRootsInCode) {
4945 _g1h->register_nmethod(nm);
4946 }
4947 }
4948 };
4949
4950 void G1CollectedHeap::rebuild_strong_code_roots() {
4951 RebuildStrongCodeRootClosure blob_cl(this);
4952 CodeCache::blobs_do(&blob_cl);
4953 }
4954
4955 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4956 GrowableArray<GCMemoryManager*> memory_managers(2);
4957 memory_managers.append(&_memory_manager);
4958 memory_managers.append(&_full_gc_memory_manager);
4959 return memory_managers;
4960 }
4961
4962 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4963 GrowableArray<MemoryPool*> memory_pools(3);
4964 memory_pools.append(_eden_pool);
4965 memory_pools.append(_survivor_pool);
4966 memory_pools.append(_old_pool);
4967 return memory_pools;
4968 }