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/g1CollectedHeap.inline.hpp"
33 #include "gc/g1/g1CollectionSet.hpp"
34 #include "gc/g1/g1CollectorPolicy.hpp"
35 #include "gc/g1/g1CollectorState.hpp"
36 #include "gc/g1/g1ConcurrentRefine.hpp"
37 #include "gc/g1/g1ConcurrentRefineThread.hpp"
38 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
39 #include "gc/g1/g1EvacStats.inline.hpp"
40 #include "gc/g1/g1FullCollector.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1HeapSizingPolicy.hpp"
43 #include "gc/g1/g1HeapTransition.hpp"
44 #include "gc/g1/g1HeapVerifier.hpp"
45 #include "gc/g1/g1HotCardCache.hpp"
46 #include "gc/g1/g1MemoryPool.hpp"
47 #include "gc/g1/g1OopClosures.inline.hpp"
48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc/g1/g1Policy.hpp"
50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
51 #include "gc/g1/g1RemSet.hpp"
52 #include "gc/g1/g1RootClosures.hpp"
53 #include "gc/g1/g1RootProcessor.hpp"
54 #include "gc/g1/g1StringDedup.hpp"
55 #include "gc/g1/g1YCTypes.hpp"
56 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
57 #include "gc/g1/heapRegion.inline.hpp"
58 #include "gc/g1/heapRegionRemSet.hpp"
59 #include "gc/g1/heapRegionSet.inline.hpp"
60 #include "gc/g1/vm_operations_g1.hpp"
61 #include "gc/shared/adaptiveSizePolicy.hpp"
62 #include "gc/shared/gcHeapSummary.hpp"
63 #include "gc/shared/gcId.hpp"
64 #include "gc/shared/gcLocker.hpp"
65 #include "gc/shared/gcTimer.hpp"
66 #include "gc/shared/gcTrace.hpp"
67 #include "gc/shared/gcTraceTime.inline.hpp"
68 #include "gc/shared/generationSpec.hpp"
69 #include "gc/shared/isGCActiveMark.hpp"
70 #include "gc/shared/preservedMarks.inline.hpp"
71 #include "gc/shared/suspendibleThreadSet.hpp"
72 #include "gc/shared/referenceProcessor.inline.hpp"
73 #include "gc/shared/taskqueue.inline.hpp"
74 #include "gc/shared/weakProcessor.hpp"
75 #include "logging/log.hpp"
76 #include "memory/allocation.hpp"
77 #include "memory/iterator.hpp"
78 #include "memory/resourceArea.hpp"
79 #include "oops/access.inline.hpp"
80 #include "oops/compressedOops.inline.hpp"
81 #include "oops/oop.inline.hpp"
82 #include "prims/resolvedMethodTable.hpp"
83 #include "runtime/atomic.hpp"
84 #include "runtime/handles.inline.hpp"
85 #include "runtime/init.hpp"
86 #include "runtime/orderAccess.inline.hpp"
87 #include "runtime/threadSMR.hpp"
88 #include "runtime/vmThread.hpp"
89 #include "utilities/align.hpp"
90 #include "utilities/globalDefinitions.hpp"
91 #include "utilities/stack.inline.hpp"
92
93 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
94
95 // INVARIANTS/NOTES
96 //
97 // All allocation activity covered by the G1CollectedHeap interface is
98 // serialized by acquiring the HeapLock. This happens in mem_allocate
99 // and allocate_new_tlab, which are the "entry" points to the
100 // allocation code from the rest of the JVM. (Note that this does not
101 // apply to TLAB allocation, which is not part of this interface: it
102 // is done by clients of this interface.)
103
104 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
105 private:
106 size_t _num_dirtied;
107 G1CollectedHeap* _g1h;
108 G1CardTable* _g1_ct;
109
110 HeapRegion* region_for_card(jbyte* card_ptr) const {
111 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
112 }
113
114 bool will_become_free(HeapRegion* hr) const {
115 // A region will be freed by free_collection_set if the region is in the
116 // collection set and has not had an evacuation failure.
117 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
118 }
119
120 public:
121 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
122 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
123
124 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
125 HeapRegion* hr = region_for_card(card_ptr);
126
127 // Should only dirty cards in regions that won't be freed.
128 if (!will_become_free(hr)) {
129 *card_ptr = G1CardTable::dirty_card_val();
130 _num_dirtied++;
131 }
132
133 return true;
134 }
135
136 size_t num_dirtied() const { return _num_dirtied; }
137 };
138
139
140 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
141 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
142 }
143
144 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
145 // The from card cache is not the memory that is actually committed. So we cannot
146 // take advantage of the zero_filled parameter.
147 reset_from_card_cache(start_idx, num_regions);
148 }
149
150
151 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
152 MemRegion mr) {
153 return new HeapRegion(hrs_index, bot(), mr);
154 }
155
156 // Private methods.
157
158 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
159 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
160 "the only time we use this to allocate a humongous region is "
161 "when we are allocating a single humongous region");
162
163 HeapRegion* res = _hrm.allocate_free_region(is_old);
164
165 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
166 // Currently, only attempts to allocate GC alloc regions set
167 // do_expand to true. So, we should only reach here during a
168 // safepoint. If this assumption changes we might have to
169 // reconsider the use of _expand_heap_after_alloc_failure.
170 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
171
172 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
173 word_size * HeapWordSize);
174
175 if (expand(word_size * HeapWordSize)) {
176 // Given that expand() succeeded in expanding the heap, and we
177 // always expand the heap by an amount aligned to the heap
178 // region size, the free list should in theory not be empty.
179 // In either case allocate_free_region() will check for NULL.
180 res = _hrm.allocate_free_region(is_old);
181 } else {
182 _expand_heap_after_alloc_failure = false;
183 }
184 }
185 return res;
186 }
187
188 HeapWord*
189 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
190 uint num_regions,
191 size_t word_size) {
192 assert(first != G1_NO_HRM_INDEX, "pre-condition");
193 assert(is_humongous(word_size), "word_size should be humongous");
194 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
195
196 // Index of last region in the series.
197 uint last = first + num_regions - 1;
198
199 // We need to initialize the region(s) we just discovered. This is
200 // a bit tricky given that it can happen concurrently with
201 // refinement threads refining cards on these regions and
202 // potentially wanting to refine the BOT as they are scanning
203 // those cards (this can happen shortly after a cleanup; see CR
204 // 6991377). So we have to set up the region(s) carefully and in
205 // a specific order.
206
207 // The word size sum of all the regions we will allocate.
208 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
209 assert(word_size <= word_size_sum, "sanity");
210
211 // This will be the "starts humongous" region.
212 HeapRegion* first_hr = region_at(first);
213 // The header of the new object will be placed at the bottom of
214 // the first region.
215 HeapWord* new_obj = first_hr->bottom();
216 // This will be the new top of the new object.
217 HeapWord* obj_top = new_obj + word_size;
218
219 // First, we need to zero the header of the space that we will be
220 // allocating. When we update top further down, some refinement
221 // threads might try to scan the region. By zeroing the header we
222 // ensure that any thread that will try to scan the region will
223 // come across the zero klass word and bail out.
224 //
225 // NOTE: It would not have been correct to have used
226 // CollectedHeap::fill_with_object() and make the space look like
227 // an int array. The thread that is doing the allocation will
228 // later update the object header to a potentially different array
229 // type and, for a very short period of time, the klass and length
230 // fields will be inconsistent. This could cause a refinement
231 // thread to calculate the object size incorrectly.
232 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
233
234 // Next, pad out the unused tail of the last region with filler
235 // objects, for improved usage accounting.
236 // How many words we use for filler objects.
237 size_t word_fill_size = word_size_sum - word_size;
238
239 // How many words memory we "waste" which cannot hold a filler object.
240 size_t words_not_fillable = 0;
241
242 if (word_fill_size >= min_fill_size()) {
243 fill_with_objects(obj_top, word_fill_size);
244 } else if (word_fill_size > 0) {
245 // We have space to fill, but we cannot fit an object there.
246 words_not_fillable = word_fill_size;
247 word_fill_size = 0;
248 }
249
250 // We will set up the first region as "starts humongous". This
251 // will also update the BOT covering all the regions to reflect
252 // that there is a single object that starts at the bottom of the
253 // first region.
254 first_hr->set_starts_humongous(obj_top, word_fill_size);
255 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
256 // Then, if there are any, we will set up the "continues
257 // humongous" regions.
258 HeapRegion* hr = NULL;
259 for (uint i = first + 1; i <= last; ++i) {
260 hr = region_at(i);
261 hr->set_continues_humongous(first_hr);
262 _g1_policy->remset_tracker()->update_at_allocate(hr);
263 }
264
265 // Up to this point no concurrent thread would have been able to
266 // do any scanning on any region in this series. All the top
267 // fields still point to bottom, so the intersection between
268 // [bottom,top] and [card_start,card_end] will be empty. Before we
269 // update the top fields, we'll do a storestore to make sure that
270 // no thread sees the update to top before the zeroing of the
271 // object header and the BOT initialization.
272 OrderAccess::storestore();
273
274 // Now, we will update the top fields of the "continues humongous"
275 // regions except the last one.
276 for (uint i = first; i < last; ++i) {
277 hr = region_at(i);
278 hr->set_top(hr->end());
279 }
280
281 hr = region_at(last);
282 // If we cannot fit a filler object, we must set top to the end
283 // of the humongous object, otherwise we cannot iterate the heap
284 // and the BOT will not be complete.
285 hr->set_top(hr->end() - words_not_fillable);
286
287 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
288 "obj_top should be in last region");
289
290 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
291
292 assert(words_not_fillable == 0 ||
293 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
294 "Miscalculation in humongous allocation");
295
296 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
297
298 for (uint i = first; i <= last; ++i) {
299 hr = region_at(i);
300 _humongous_set.add(hr);
301 _hr_printer.alloc(hr);
302 }
303
304 return new_obj;
305 }
306
307 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
308 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
309 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
310 }
311
312 // If could fit into free regions w/o expansion, try.
313 // Otherwise, if can expand, do so.
314 // Otherwise, if using ex regions might help, try with ex given back.
315 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
316 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
317
318 _verifier->verify_region_sets_optional();
319
320 uint first = G1_NO_HRM_INDEX;
321 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
322
323 if (obj_regions == 1) {
324 // Only one region to allocate, try to use a fast path by directly allocating
325 // from the free lists. Do not try to expand here, we will potentially do that
326 // later.
327 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
328 if (hr != NULL) {
329 first = hr->hrm_index();
330 }
331 } else {
332 // Policy: Try only empty regions (i.e. already committed first). Maybe we
333 // are lucky enough to find some.
334 first = _hrm.find_contiguous_only_empty(obj_regions);
335 if (first != G1_NO_HRM_INDEX) {
336 _hrm.allocate_free_regions_starting_at(first, obj_regions);
337 }
338 }
339
340 if (first == G1_NO_HRM_INDEX) {
341 // Policy: We could not find enough regions for the humongous object in the
342 // free list. Look through the heap to find a mix of free and uncommitted regions.
343 // If so, try expansion.
344 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
345 if (first != G1_NO_HRM_INDEX) {
346 // We found something. Make sure these regions are committed, i.e. expand
347 // the heap. Alternatively we could do a defragmentation GC.
348 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
349 word_size * HeapWordSize);
350
351 _hrm.expand_at(first, obj_regions, workers());
352 g1_policy()->record_new_heap_size(num_regions());
353
354 #ifdef ASSERT
355 for (uint i = first; i < first + obj_regions; ++i) {
356 HeapRegion* hr = region_at(i);
357 assert(hr->is_free(), "sanity");
358 assert(hr->is_empty(), "sanity");
359 assert(is_on_master_free_list(hr), "sanity");
360 }
361 #endif
362 _hrm.allocate_free_regions_starting_at(first, obj_regions);
363 } else {
364 // Policy: Potentially trigger a defragmentation GC.
365 }
366 }
367
368 HeapWord* result = NULL;
369 if (first != G1_NO_HRM_INDEX) {
370 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
371 assert(result != NULL, "it should always return a valid result");
372
373 // A successful humongous object allocation changes the used space
374 // information of the old generation so we need to recalculate the
375 // sizes and update the jstat counters here.
376 g1mm()->update_sizes();
377 }
378
379 _verifier->verify_region_sets_optional();
380
381 return result;
382 }
383
384 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
385 assert_heap_not_locked_and_not_at_safepoint();
386 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
387
388 return attempt_allocation(word_size);
389 }
390
391 HeapWord*
392 G1CollectedHeap::mem_allocate(size_t word_size,
393 bool* gc_overhead_limit_was_exceeded) {
394 assert_heap_not_locked_and_not_at_safepoint();
395
396 if (is_humongous(word_size)) {
397 return attempt_allocation_humongous(word_size);
398 }
399 return attempt_allocation(word_size);
400 }
401
402 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
403 ResourceMark rm; // For retrieving the thread names in log messages.
404
405 // Make sure you read the note in attempt_allocation_humongous().
406
407 assert_heap_not_locked_and_not_at_safepoint();
408 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
409 "be called for humongous allocation requests");
410
411 // We should only get here after the first-level allocation attempt
412 // (attempt_allocation()) failed to allocate.
413
414 // We will loop until a) we manage to successfully perform the
415 // allocation or b) we successfully schedule a collection which
416 // fails to perform the allocation. b) is the only case when we'll
417 // return NULL.
418 HeapWord* result = NULL;
419 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
420 bool should_try_gc;
421 uint gc_count_before;
422
423 {
424 MutexLockerEx x(Heap_lock);
425 result = _allocator->attempt_allocation_locked(word_size);
426 if (result != NULL) {
427 return result;
428 }
429
430 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
431 // This is different to when only GCLocker::needs_gc() is set: try to avoid
432 // waiting because the GCLocker is active to not wait too long.
433 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
434 // No need for an ergo message here, can_expand_young_list() does this when
435 // it returns true.
436 result = _allocator->attempt_allocation_force(word_size);
437 if (result != NULL) {
438 return result;
439 }
440 }
441 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
442 // the GCLocker initiated GC has been performed and then retry. This includes
443 // the case when the GC Locker is not active but has not been performed.
444 should_try_gc = !GCLocker::needs_gc();
445 // Read the GC count while still holding the Heap_lock.
446 gc_count_before = total_collections();
447 }
448
449 if (should_try_gc) {
450 bool succeeded;
451 result = do_collection_pause(word_size, gc_count_before, &succeeded,
452 GCCause::_g1_inc_collection_pause);
453 if (result != NULL) {
454 assert(succeeded, "only way to get back a non-NULL result");
455 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
456 Thread::current()->name(), p2i(result));
457 return result;
458 }
459
460 if (succeeded) {
461 // We successfully scheduled a collection which failed to allocate. No
462 // point in trying to allocate further. We'll just return NULL.
463 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
464 SIZE_FORMAT " words", Thread::current()->name(), word_size);
465 return NULL;
466 }
467 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
468 Thread::current()->name(), word_size);
469 } else {
470 // Failed to schedule a collection.
471 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
472 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
473 SIZE_FORMAT " words", Thread::current()->name(), word_size);
474 return NULL;
475 }
476 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
477 // The GCLocker is either active or the GCLocker initiated
478 // GC has not yet been performed. Stall until it is and
479 // then retry the allocation.
480 GCLocker::stall_until_clear();
481 gclocker_retry_count += 1;
482 }
483
484 // We can reach here if we were unsuccessful in scheduling a
485 // collection (because another thread beat us to it) or if we were
486 // stalled due to the GC locker. In either can we should retry the
487 // allocation attempt in case another thread successfully
488 // performed a collection and reclaimed enough space. We do the
489 // first attempt (without holding the Heap_lock) here and the
490 // follow-on attempt will be at the start of the next loop
491 // iteration (after taking the Heap_lock).
492
493 result = _allocator->attempt_allocation(word_size);
494 if (result != NULL) {
495 return result;
496 }
497
498 // Give a warning if we seem to be looping forever.
499 if ((QueuedAllocationWarningCount > 0) &&
500 (try_count % QueuedAllocationWarningCount == 0)) {
501 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
502 Thread::current()->name(), try_count, word_size);
503 }
504 }
505
506 ShouldNotReachHere();
507 return NULL;
508 }
509
510 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
511 assert_at_safepoint_on_vm_thread();
512 if (_archive_allocator == NULL) {
513 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
514 }
515 }
516
517 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
518 // Allocations in archive regions cannot be of a size that would be considered
519 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
520 // may be different at archive-restore time.
521 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
522 }
523
524 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
525 assert_at_safepoint_on_vm_thread();
526 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
527 if (is_archive_alloc_too_large(word_size)) {
528 return NULL;
529 }
530 return _archive_allocator->archive_mem_allocate(word_size);
531 }
532
533 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
534 size_t end_alignment_in_bytes) {
535 assert_at_safepoint_on_vm_thread();
536 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
537
538 // Call complete_archive to do the real work, filling in the MemRegion
539 // array with the archive regions.
540 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
541 delete _archive_allocator;
542 _archive_allocator = NULL;
543 }
544
545 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
546 assert(ranges != NULL, "MemRegion array NULL");
547 assert(count != 0, "No MemRegions provided");
548 MemRegion reserved = _hrm.reserved();
549 for (size_t i = 0; i < count; i++) {
550 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
551 return false;
552 }
553 }
554 return true;
555 }
556
557 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
558 size_t count,
559 bool open) {
560 assert(!is_init_completed(), "Expect to be called at JVM init time");
561 assert(ranges != NULL, "MemRegion array NULL");
562 assert(count != 0, "No MemRegions provided");
563 MutexLockerEx x(Heap_lock);
564
565 MemRegion reserved = _hrm.reserved();
566 HeapWord* prev_last_addr = NULL;
567 HeapRegion* prev_last_region = NULL;
568
569 // Temporarily disable pretouching of heap pages. This interface is used
570 // when mmap'ing archived heap data in, so pre-touching is wasted.
571 FlagSetting fs(AlwaysPreTouch, false);
572
573 // Enable archive object checking used by G1MarkSweep. We have to let it know
574 // about each archive range, so that objects in those ranges aren't marked.
575 G1ArchiveAllocator::enable_archive_object_check();
576
577 // For each specified MemRegion range, allocate the corresponding G1
578 // regions and mark them as archive regions. We expect the ranges
579 // in ascending starting address order, without overlap.
580 for (size_t i = 0; i < count; i++) {
581 MemRegion curr_range = ranges[i];
582 HeapWord* start_address = curr_range.start();
583 size_t word_size = curr_range.word_size();
584 HeapWord* last_address = curr_range.last();
585 size_t commits = 0;
586
587 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
588 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
589 p2i(start_address), p2i(last_address));
590 guarantee(start_address > prev_last_addr,
591 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
592 p2i(start_address), p2i(prev_last_addr));
593 prev_last_addr = last_address;
594
595 // Check for ranges that start in the same G1 region in which the previous
596 // range ended, and adjust the start address so we don't try to allocate
597 // the same region again. If the current range is entirely within that
598 // region, skip it, just adjusting the recorded top.
599 HeapRegion* start_region = _hrm.addr_to_region(start_address);
600 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
601 start_address = start_region->end();
602 if (start_address > last_address) {
603 increase_used(word_size * HeapWordSize);
604 start_region->set_top(last_address + 1);
605 continue;
606 }
607 start_region->set_top(start_address);
608 curr_range = MemRegion(start_address, last_address + 1);
609 start_region = _hrm.addr_to_region(start_address);
610 }
611
612 // Perform the actual region allocation, exiting if it fails.
613 // Then note how much new space we have allocated.
614 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
615 return false;
616 }
617 increase_used(word_size * HeapWordSize);
618 if (commits != 0) {
619 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
620 HeapRegion::GrainWords * HeapWordSize * commits);
621
622 }
623
624 // Mark each G1 region touched by the range as archive, add it to
625 // the old set, and set top.
626 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
627 HeapRegion* last_region = _hrm.addr_to_region(last_address);
628 prev_last_region = last_region;
629
630 while (curr_region != NULL) {
631 assert(curr_region->is_empty() && !curr_region->is_pinned(),
632 "Region already in use (index %u)", curr_region->hrm_index());
633 if (open) {
634 curr_region->set_open_archive();
635 } else {
636 curr_region->set_closed_archive();
637 }
638 _hr_printer.alloc(curr_region);
639 _old_set.add(curr_region);
640 HeapWord* top;
641 HeapRegion* next_region;
642 if (curr_region != last_region) {
643 top = curr_region->end();
644 next_region = _hrm.next_region_in_heap(curr_region);
645 } else {
646 top = last_address + 1;
647 next_region = NULL;
648 }
649 curr_region->set_top(top);
650 curr_region->set_first_dead(top);
651 curr_region->set_end_of_live(top);
652 curr_region = next_region;
653 }
654
655 // Notify mark-sweep of the archive
656 G1ArchiveAllocator::set_range_archive(curr_range, open);
657 }
658 return true;
659 }
660
661 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
662 assert(!is_init_completed(), "Expect to be called at JVM init time");
663 assert(ranges != NULL, "MemRegion array NULL");
664 assert(count != 0, "No MemRegions provided");
665 MemRegion reserved = _hrm.reserved();
666 HeapWord *prev_last_addr = NULL;
667 HeapRegion* prev_last_region = NULL;
668
669 // For each MemRegion, create filler objects, if needed, in the G1 regions
670 // that contain the address range. The address range actually within the
671 // MemRegion will not be modified. That is assumed to have been initialized
672 // elsewhere, probably via an mmap of archived heap data.
673 MutexLockerEx x(Heap_lock);
674 for (size_t i = 0; i < count; i++) {
675 HeapWord* start_address = ranges[i].start();
676 HeapWord* last_address = ranges[i].last();
677
678 assert(reserved.contains(start_address) && reserved.contains(last_address),
679 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
680 p2i(start_address), p2i(last_address));
681 assert(start_address > prev_last_addr,
682 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
683 p2i(start_address), p2i(prev_last_addr));
684
685 HeapRegion* start_region = _hrm.addr_to_region(start_address);
686 HeapRegion* last_region = _hrm.addr_to_region(last_address);
687 HeapWord* bottom_address = start_region->bottom();
688
689 // Check for a range beginning in the same region in which the
690 // previous one ended.
691 if (start_region == prev_last_region) {
692 bottom_address = prev_last_addr + 1;
693 }
694
695 // Verify that the regions were all marked as archive regions by
696 // alloc_archive_regions.
697 HeapRegion* curr_region = start_region;
698 while (curr_region != NULL) {
699 guarantee(curr_region->is_archive(),
700 "Expected archive region at index %u", curr_region->hrm_index());
701 if (curr_region != last_region) {
702 curr_region = _hrm.next_region_in_heap(curr_region);
703 } else {
704 curr_region = NULL;
705 }
706 }
707
708 prev_last_addr = last_address;
709 prev_last_region = last_region;
710
711 // Fill the memory below the allocated range with dummy object(s),
712 // if the region bottom does not match the range start, or if the previous
713 // range ended within the same G1 region, and there is a gap.
714 if (start_address != bottom_address) {
715 size_t fill_size = pointer_delta(start_address, bottom_address);
716 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
717 increase_used(fill_size * HeapWordSize);
718 }
719 }
720 }
721
722 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
723 assert_heap_not_locked_and_not_at_safepoint();
724 assert(!is_humongous(word_size), "attempt_allocation() should not "
725 "be called for humongous allocation requests");
726
727 HeapWord* result = _allocator->attempt_allocation(word_size);
728
729 if (result == NULL) {
730 result = attempt_allocation_slow(word_size);
731 }
732 assert_heap_not_locked();
733 if (result != NULL) {
734 dirty_young_block(result, word_size);
735 }
736 return result;
737 }
738
739 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
740 assert(!is_init_completed(), "Expect to be called at JVM init time");
741 assert(ranges != NULL, "MemRegion array NULL");
742 assert(count != 0, "No MemRegions provided");
743 MemRegion reserved = _hrm.reserved();
744 HeapWord* prev_last_addr = NULL;
745 HeapRegion* prev_last_region = NULL;
746 size_t size_used = 0;
747 size_t uncommitted_regions = 0;
748
749 // For each Memregion, free the G1 regions that constitute it, and
750 // notify mark-sweep that the range is no longer to be considered 'archive.'
751 MutexLockerEx x(Heap_lock);
752 for (size_t i = 0; i < count; i++) {
753 HeapWord* start_address = ranges[i].start();
754 HeapWord* last_address = ranges[i].last();
755
756 assert(reserved.contains(start_address) && reserved.contains(last_address),
757 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
758 p2i(start_address), p2i(last_address));
759 assert(start_address > prev_last_addr,
760 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
761 p2i(start_address), p2i(prev_last_addr));
762 size_used += ranges[i].byte_size();
763 prev_last_addr = last_address;
764
765 HeapRegion* start_region = _hrm.addr_to_region(start_address);
766 HeapRegion* last_region = _hrm.addr_to_region(last_address);
767
768 // Check for ranges that start in the same G1 region in which the previous
769 // range ended, and adjust the start address so we don't try to free
770 // the same region again. If the current range is entirely within that
771 // region, skip it.
772 if (start_region == prev_last_region) {
773 start_address = start_region->end();
774 if (start_address > last_address) {
775 continue;
776 }
777 start_region = _hrm.addr_to_region(start_address);
778 }
779 prev_last_region = last_region;
780
781 // After verifying that each region was marked as an archive region by
782 // alloc_archive_regions, set it free and empty and uncommit it.
783 HeapRegion* curr_region = start_region;
784 while (curr_region != NULL) {
785 guarantee(curr_region->is_archive(),
786 "Expected archive region at index %u", curr_region->hrm_index());
787 uint curr_index = curr_region->hrm_index();
788 _old_set.remove(curr_region);
789 curr_region->set_free();
790 curr_region->set_top(curr_region->bottom());
791 if (curr_region != last_region) {
792 curr_region = _hrm.next_region_in_heap(curr_region);
793 } else {
794 curr_region = NULL;
795 }
796 _hrm.shrink_at(curr_index, 1);
797 uncommitted_regions++;
798 }
799
800 // Notify mark-sweep that this is no longer an archive range.
801 G1ArchiveAllocator::set_range_archive(ranges[i], false);
802 }
803
804 if (uncommitted_regions != 0) {
805 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
806 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
807 }
808 decrease_used(size_used);
809 }
810
811 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
812 ResourceMark rm; // For retrieving the thread names in log messages.
813
814 // The structure of this method has a lot of similarities to
815 // attempt_allocation_slow(). The reason these two were not merged
816 // into a single one is that such a method would require several "if
817 // allocation is not humongous do this, otherwise do that"
818 // conditional paths which would obscure its flow. In fact, an early
819 // version of this code did use a unified method which was harder to
820 // follow and, as a result, it had subtle bugs that were hard to
821 // track down. So keeping these two methods separate allows each to
822 // be more readable. It will be good to keep these two in sync as
823 // much as possible.
824
825 assert_heap_not_locked_and_not_at_safepoint();
826 assert(is_humongous(word_size), "attempt_allocation_humongous() "
827 "should only be called for humongous allocations");
828
829 // Humongous objects can exhaust the heap quickly, so we should check if we
830 // need to start a marking cycle at each humongous object allocation. We do
831 // the check before we do the actual allocation. The reason for doing it
832 // before the allocation is that we avoid having to keep track of the newly
833 // allocated memory while we do a GC.
834 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
835 word_size)) {
836 collect(GCCause::_g1_humongous_allocation);
837 }
838
839 // We will loop until a) we manage to successfully perform the
840 // allocation or b) we successfully schedule a collection which
841 // fails to perform the allocation. b) is the only case when we'll
842 // return NULL.
843 HeapWord* result = NULL;
844 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
845 bool should_try_gc;
846 uint gc_count_before;
847
848
849 {
850 MutexLockerEx x(Heap_lock);
851
852 // Given that humongous objects are not allocated in young
853 // regions, we'll first try to do the allocation without doing a
854 // collection hoping that there's enough space in the heap.
855 result = humongous_obj_allocate(word_size);
856 if (result != NULL) {
857 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
858 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
859 return result;
860 }
861
862 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
863 // the GCLocker initiated GC has been performed and then retry. This includes
864 // the case when the GC Locker is not active but has not been performed.
865 should_try_gc = !GCLocker::needs_gc();
866 // Read the GC count while still holding the Heap_lock.
867 gc_count_before = total_collections();
868 }
869
870 if (should_try_gc) {
871 bool succeeded;
872 result = do_collection_pause(word_size, gc_count_before, &succeeded,
873 GCCause::_g1_humongous_allocation);
874 if (result != NULL) {
875 assert(succeeded, "only way to get back a non-NULL result");
876 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
877 Thread::current()->name(), p2i(result));
878 return result;
879 }
880
881 if (succeeded) {
882 // We successfully scheduled a collection which failed to allocate. No
883 // point in trying to allocate further. We'll just return NULL.
884 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
885 SIZE_FORMAT " words", Thread::current()->name(), word_size);
886 return NULL;
887 }
888 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
889 Thread::current()->name(), word_size);
890 } else {
891 // Failed to schedule a collection.
892 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
893 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
894 SIZE_FORMAT " words", Thread::current()->name(), word_size);
895 return NULL;
896 }
897 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
898 // The GCLocker is either active or the GCLocker initiated
899 // GC has not yet been performed. Stall until it is and
900 // then retry the allocation.
901 GCLocker::stall_until_clear();
902 gclocker_retry_count += 1;
903 }
904
905
906 // We can reach here if we were unsuccessful in scheduling a
907 // collection (because another thread beat us to it) or if we were
908 // stalled due to the GC locker. In either can we should retry the
909 // allocation attempt in case another thread successfully
910 // performed a collection and reclaimed enough space.
911 // Humongous object allocation always needs a lock, so we wait for the retry
912 // in the next iteration of the loop, unlike for the regular iteration case.
913 // Give a warning if we seem to be looping forever.
914
915 if ((QueuedAllocationWarningCount > 0) &&
916 (try_count % QueuedAllocationWarningCount == 0)) {
917 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
918 Thread::current()->name(), try_count, word_size);
919 }
920 }
921
922 ShouldNotReachHere();
923 return NULL;
924 }
925
926 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
927 bool expect_null_mutator_alloc_region) {
928 assert_at_safepoint_on_vm_thread();
929 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
930 "the current alloc region was unexpectedly found to be non-NULL");
931
932 if (!is_humongous(word_size)) {
933 return _allocator->attempt_allocation_locked(word_size);
934 } else {
935 HeapWord* result = humongous_obj_allocate(word_size);
936 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
937 collector_state()->set_initiate_conc_mark_if_possible(true);
938 }
939 return result;
940 }
941
942 ShouldNotReachHere();
943 }
944
945 class PostCompactionPrinterClosure: public HeapRegionClosure {
946 private:
947 G1HRPrinter* _hr_printer;
948 public:
949 bool do_heap_region(HeapRegion* hr) {
950 assert(!hr->is_young(), "not expecting to find young regions");
951 _hr_printer->post_compaction(hr);
952 return false;
953 }
954
955 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
956 : _hr_printer(hr_printer) { }
957 };
958
959 void G1CollectedHeap::print_hrm_post_compaction() {
960 if (_hr_printer.is_active()) {
961 PostCompactionPrinterClosure cl(hr_printer());
962 heap_region_iterate(&cl);
963 }
964 }
965
966 void G1CollectedHeap::abort_concurrent_cycle() {
967 // If we start the compaction before the CM threads finish
968 // scanning the root regions we might trip them over as we'll
969 // be moving objects / updating references. So let's wait until
970 // they are done. By telling them to abort, they should complete
971 // early.
972 _cm->root_regions()->abort();
973 _cm->root_regions()->wait_until_scan_finished();
974
975 // Disable discovery and empty the discovered lists
976 // for the CM ref processor.
977 ref_processor_cm()->disable_discovery();
978 ref_processor_cm()->abandon_partial_discovery();
979 ref_processor_cm()->verify_no_references_recorded();
980
981 // Abandon current iterations of concurrent marking and concurrent
982 // refinement, if any are in progress.
983 concurrent_mark()->concurrent_cycle_abort();
984 }
985
986 void G1CollectedHeap::prepare_heap_for_full_collection() {
987 // Make sure we'll choose a new allocation region afterwards.
988 _allocator->release_mutator_alloc_region();
989 _allocator->abandon_gc_alloc_regions();
990 g1_rem_set()->cleanupHRRS();
991
992 // We may have added regions to the current incremental collection
993 // set between the last GC or pause and now. We need to clear the
994 // incremental collection set and then start rebuilding it afresh
995 // after this full GC.
996 abandon_collection_set(collection_set());
997
998 tear_down_region_sets(false /* free_list_only */);
999 }
1000
1001 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1002 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1003 assert(used() == recalculate_used(), "Should be equal");
1004 _verifier->verify_region_sets_optional();
1005 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1006 _verifier->check_bitmaps("Full GC Start");
1007 }
1008
1009 void G1CollectedHeap::prepare_heap_for_mutators() {
1010 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1011 ClassLoaderDataGraph::purge();
1012 MetaspaceUtils::verify_metrics();
1013
1014 // Prepare heap for normal collections.
1015 assert(num_free_regions() == 0, "we should not have added any free regions");
1016 rebuild_region_sets(false /* free_list_only */);
1017 abort_refinement();
1018 resize_if_necessary_after_full_collection();
1019
1020 // Rebuild the strong code root lists for each region
1021 rebuild_strong_code_roots();
1022
1023 // Start a new incremental collection set for the next pause
1024 start_new_collection_set();
1025
1026 _allocator->init_mutator_alloc_region();
1027
1028 // Post collection state updates.
1029 MetaspaceGC::compute_new_size();
1030 }
1031
1032 void G1CollectedHeap::abort_refinement() {
1033 if (_hot_card_cache->use_cache()) {
1034 _hot_card_cache->reset_hot_cache();
1035 }
1036
1037 // Discard all remembered set updates.
1038 JavaThread::dirty_card_queue_set().abandon_logs();
1039 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1040 }
1041
1042 void G1CollectedHeap::verify_after_full_collection() {
1043 _hrm.verify_optional();
1044 _verifier->verify_region_sets_optional();
1045 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1046 // Clear the previous marking bitmap, if needed for bitmap verification.
1047 // Note we cannot do this when we clear the next marking bitmap in
1048 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1049 // objects marked during a full GC against the previous bitmap.
1050 // But we need to clear it before calling check_bitmaps below since
1051 // the full GC has compacted objects and updated TAMS but not updated
1052 // the prev bitmap.
1053 if (G1VerifyBitmaps) {
1054 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1055 _cm->clear_prev_bitmap(workers());
1056 }
1057 _verifier->check_bitmaps("Full GC End");
1058
1059 // At this point there should be no regions in the
1060 // entire heap tagged as young.
1061 assert(check_young_list_empty(), "young list should be empty at this point");
1062
1063 // Note: since we've just done a full GC, concurrent
1064 // marking is no longer active. Therefore we need not
1065 // re-enable reference discovery for the CM ref processor.
1066 // That will be done at the start of the next marking cycle.
1067 // We also know that the STW processor should no longer
1068 // discover any new references.
1069 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1070 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1071 ref_processor_stw()->verify_no_references_recorded();
1072 ref_processor_cm()->verify_no_references_recorded();
1073 }
1074
1075 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1076 // Post collection logging.
1077 // We should do this after we potentially resize the heap so
1078 // that all the COMMIT / UNCOMMIT events are generated before
1079 // the compaction events.
1080 print_hrm_post_compaction();
1081 heap_transition->print();
1082 print_heap_after_gc();
1083 print_heap_regions();
1084 #ifdef TRACESPINNING
1085 ParallelTaskTerminator::print_termination_counts();
1086 #endif
1087 }
1088
1089 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1090 bool clear_all_soft_refs) {
1091 assert_at_safepoint_on_vm_thread();
1092
1093 if (GCLocker::check_active_before_gc()) {
1094 // Full GC was not completed.
1095 return false;
1096 }
1097
1098 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1099 soft_ref_policy()->should_clear_all_soft_refs();
1100
1101 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1102 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1103
1104 collector.prepare_collection();
1105 collector.collect();
1106 collector.complete_collection();
1107
1108 // Full collection was successfully completed.
1109 return true;
1110 }
1111
1112 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1113 // Currently, there is no facility in the do_full_collection(bool) API to notify
1114 // the caller that the collection did not succeed (e.g., because it was locked
1115 // out by the GC locker). So, right now, we'll ignore the return value.
1116 bool dummy = do_full_collection(true, /* explicit_gc */
1117 clear_all_soft_refs);
1118 }
1119
1120 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1121 // Capacity, free and used after the GC counted as full regions to
1122 // include the waste in the following calculations.
1123 const size_t capacity_after_gc = capacity();
1124 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1125
1126 // This is enforced in arguments.cpp.
1127 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1128 "otherwise the code below doesn't make sense");
1129
1130 // We don't have floating point command-line arguments
1131 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1132 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1133 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1134 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1135
1136 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1137 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1138
1139 // We have to be careful here as these two calculations can overflow
1140 // 32-bit size_t's.
1141 double used_after_gc_d = (double) used_after_gc;
1142 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1143 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1144
1145 // Let's make sure that they are both under the max heap size, which
1146 // by default will make them fit into a size_t.
1147 double desired_capacity_upper_bound = (double) max_heap_size;
1148 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1149 desired_capacity_upper_bound);
1150 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1151 desired_capacity_upper_bound);
1152
1153 // We can now safely turn them into size_t's.
1154 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1155 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1156
1157 // This assert only makes sense here, before we adjust them
1158 // with respect to the min and max heap size.
1159 assert(minimum_desired_capacity <= maximum_desired_capacity,
1160 "minimum_desired_capacity = " SIZE_FORMAT ", "
1161 "maximum_desired_capacity = " SIZE_FORMAT,
1162 minimum_desired_capacity, maximum_desired_capacity);
1163
1164 // Should not be greater than the heap max size. No need to adjust
1165 // it with respect to the heap min size as it's a lower bound (i.e.,
1166 // we'll try to make the capacity larger than it, not smaller).
1167 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1168 // Should not be less than the heap min size. No need to adjust it
1169 // with respect to the heap max size as it's an upper bound (i.e.,
1170 // we'll try to make the capacity smaller than it, not greater).
1171 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1172
1173 if (capacity_after_gc < minimum_desired_capacity) {
1174 // Don't expand unless it's significant
1175 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1176
1177 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1178 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1179 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1180 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1181
1182 expand(expand_bytes, _workers);
1183
1184 // No expansion, now see if we want to shrink
1185 } else if (capacity_after_gc > maximum_desired_capacity) {
1186 // Capacity too large, compute shrinking size
1187 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1188
1189 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1190 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1191 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1192 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1193
1194 shrink(shrink_bytes);
1195 }
1196 }
1197
1198 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1199 bool do_gc,
1200 bool clear_all_soft_refs,
1201 bool expect_null_mutator_alloc_region,
1202 bool* gc_succeeded) {
1203 *gc_succeeded = true;
1204 // Let's attempt the allocation first.
1205 HeapWord* result =
1206 attempt_allocation_at_safepoint(word_size,
1207 expect_null_mutator_alloc_region);
1208 if (result != NULL) {
1209 return result;
1210 }
1211
1212 // In a G1 heap, we're supposed to keep allocation from failing by
1213 // incremental pauses. Therefore, at least for now, we'll favor
1214 // expansion over collection. (This might change in the future if we can
1215 // do something smarter than full collection to satisfy a failed alloc.)
1216 result = expand_and_allocate(word_size);
1217 if (result != NULL) {
1218 return result;
1219 }
1220
1221 if (do_gc) {
1222 // Expansion didn't work, we'll try to do a Full GC.
1223 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1224 clear_all_soft_refs);
1225 }
1226
1227 return NULL;
1228 }
1229
1230 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1231 bool* succeeded) {
1232 assert_at_safepoint_on_vm_thread();
1233
1234 // Attempts to allocate followed by Full GC.
1235 HeapWord* result =
1236 satisfy_failed_allocation_helper(word_size,
1237 true, /* do_gc */
1238 false, /* clear_all_soft_refs */
1239 false, /* expect_null_mutator_alloc_region */
1240 succeeded);
1241
1242 if (result != NULL || !*succeeded) {
1243 return result;
1244 }
1245
1246 // Attempts to allocate followed by Full GC that will collect all soft references.
1247 result = satisfy_failed_allocation_helper(word_size,
1248 true, /* do_gc */
1249 true, /* clear_all_soft_refs */
1250 true, /* expect_null_mutator_alloc_region */
1251 succeeded);
1252
1253 if (result != NULL || !*succeeded) {
1254 return result;
1255 }
1256
1257 // Attempts to allocate, no GC
1258 result = satisfy_failed_allocation_helper(word_size,
1259 false, /* do_gc */
1260 false, /* clear_all_soft_refs */
1261 true, /* expect_null_mutator_alloc_region */
1262 succeeded);
1263
1264 if (result != NULL) {
1265 return result;
1266 }
1267
1268 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1269 "Flag should have been handled and cleared prior to this point");
1270
1271 // What else? We might try synchronous finalization later. If the total
1272 // space available is large enough for the allocation, then a more
1273 // complete compaction phase than we've tried so far might be
1274 // appropriate.
1275 return NULL;
1276 }
1277
1278 // Attempting to expand the heap sufficiently
1279 // to support an allocation of the given "word_size". If
1280 // successful, perform the allocation and return the address of the
1281 // allocated block, or else "NULL".
1282
1283 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1284 assert_at_safepoint_on_vm_thread();
1285
1286 _verifier->verify_region_sets_optional();
1287
1288 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1289 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1290 word_size * HeapWordSize);
1291
1292
1293 if (expand(expand_bytes, _workers)) {
1294 _hrm.verify_optional();
1295 _verifier->verify_region_sets_optional();
1296 return attempt_allocation_at_safepoint(word_size,
1297 false /* expect_null_mutator_alloc_region */);
1298 }
1299 return NULL;
1300 }
1301
1302 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1303 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1304 aligned_expand_bytes = align_up(aligned_expand_bytes,
1305 HeapRegion::GrainBytes);
1306
1307 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1308 expand_bytes, aligned_expand_bytes);
1309
1310 if (is_maximal_no_gc()) {
1311 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1312 return false;
1313 }
1314
1315 double expand_heap_start_time_sec = os::elapsedTime();
1316 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1317 assert(regions_to_expand > 0, "Must expand by at least one region");
1318
1319 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1320 if (expand_time_ms != NULL) {
1321 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1322 }
1323
1324 if (expanded_by > 0) {
1325 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1326 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1327 g1_policy()->record_new_heap_size(num_regions());
1328 } else {
1329 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1330
1331 // The expansion of the virtual storage space was unsuccessful.
1332 // Let's see if it was because we ran out of swap.
1333 if (G1ExitOnExpansionFailure &&
1334 _hrm.available() >= regions_to_expand) {
1335 // We had head room...
1336 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1337 }
1338 }
1339 return regions_to_expand > 0;
1340 }
1341
1342 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1343 size_t aligned_shrink_bytes =
1344 ReservedSpace::page_align_size_down(shrink_bytes);
1345 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1346 HeapRegion::GrainBytes);
1347 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1348
1349 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1350 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1351
1352
1353 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",
1354 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1355 if (num_regions_removed > 0) {
1356 g1_policy()->record_new_heap_size(num_regions());
1357 } else {
1358 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1359 }
1360 }
1361
1362 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1363 _verifier->verify_region_sets_optional();
1364
1365 // We should only reach here at the end of a Full GC which means we
1366 // should not not be holding to any GC alloc regions. The method
1367 // below will make sure of that and do any remaining clean up.
1368 _allocator->abandon_gc_alloc_regions();
1369
1370 // Instead of tearing down / rebuilding the free lists here, we
1371 // could instead use the remove_all_pending() method on free_list to
1372 // remove only the ones that we need to remove.
1373 tear_down_region_sets(true /* free_list_only */);
1374 shrink_helper(shrink_bytes);
1375 rebuild_region_sets(true /* free_list_only */);
1376
1377 _hrm.verify_optional();
1378 _verifier->verify_region_sets_optional();
1379 }
1380
1381 // Public methods.
1382
1383 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1384 CollectedHeap(),
1385 _young_gen_sampling_thread(NULL),
1386 _collector_policy(collector_policy),
1387 _soft_ref_policy(),
1388 _card_table(NULL),
1389 _memory_manager("G1 Young Generation", "end of minor GC"),
1390 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1391 _eden_pool(NULL),
1392 _survivor_pool(NULL),
1393 _old_pool(NULL),
1394 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1395 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1396 _g1_policy(new G1Policy(_gc_timer_stw)),
1397 _collection_set(this, _g1_policy),
1398 _dirty_card_queue_set(false),
1399 _is_alive_closure_cm(this),
1400 _is_alive_closure_stw(this),
1401 _ref_processor_cm(NULL),
1402 _ref_processor_stw(NULL),
1403 _bot(NULL),
1404 _hot_card_cache(NULL),
1405 _g1_rem_set(NULL),
1406 _cr(NULL),
1407 _g1mm(NULL),
1408 _preserved_marks_set(true /* in_c_heap */),
1409 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1410 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1411 _humongous_reclaim_candidates(),
1412 _has_humongous_reclaim_candidates(false),
1413 _archive_allocator(NULL),
1414 _summary_bytes_used(0),
1415 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1416 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1417 _expand_heap_after_alloc_failure(true),
1418 _old_marking_cycles_started(0),
1419 _old_marking_cycles_completed(0),
1420 _in_cset_fast_test() {
1421
1422 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1423 /* are_GC_task_threads */true,
1424 /* are_ConcurrentGC_threads */false);
1425 _workers->initialize_workers();
1426 _verifier = new G1HeapVerifier(this);
1427
1428 _allocator = new G1DefaultAllocator(this);
1429
1430 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1431
1432 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1433
1434 // Override the default _filler_array_max_size so that no humongous filler
1435 // objects are created.
1436 _filler_array_max_size = _humongous_object_threshold_in_words;
1437
1438 uint n_queues = ParallelGCThreads;
1439 _task_queues = new RefToScanQueueSet(n_queues);
1440
1441 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1442
1443 for (uint i = 0; i < n_queues; i++) {
1444 RefToScanQueue* q = new RefToScanQueue();
1445 q->initialize();
1446 _task_queues->register_queue(i, q);
1447 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1448 }
1449
1450 // Initialize the G1EvacuationFailureALot counters and flags.
1451 NOT_PRODUCT(reset_evacuation_should_fail();)
1452
1453 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1454 }
1455
1456 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1457 size_t size,
1458 size_t translation_factor) {
1459 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1460 // Allocate a new reserved space, preferring to use large pages.
1461 ReservedSpace rs(size, preferred_page_size);
1462 G1RegionToSpaceMapper* result =
1463 G1RegionToSpaceMapper::create_mapper(rs,
1464 size,
1465 rs.alignment(),
1466 HeapRegion::GrainBytes,
1467 translation_factor,
1468 mtGC);
1469
1470 os::trace_page_sizes_for_requested_size(description,
1471 size,
1472 preferred_page_size,
1473 rs.alignment(),
1474 rs.base(),
1475 rs.size());
1476
1477 return result;
1478 }
1479
1480 jint G1CollectedHeap::initialize_concurrent_refinement() {
1481 jint ecode = JNI_OK;
1482 _cr = G1ConcurrentRefine::create(&ecode);
1483 return ecode;
1484 }
1485
1486 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1487 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1488 if (_young_gen_sampling_thread->osthread() == NULL) {
1489 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1490 return JNI_ENOMEM;
1491 }
1492 return JNI_OK;
1493 }
1494
1495 jint G1CollectedHeap::initialize() {
1496 os::enable_vtime();
1497
1498 // Necessary to satisfy locking discipline assertions.
1499
1500 MutexLocker x(Heap_lock);
1501
1502 // While there are no constraints in the GC code that HeapWordSize
1503 // be any particular value, there are multiple other areas in the
1504 // system which believe this to be true (e.g. oop->object_size in some
1505 // cases incorrectly returns the size in wordSize units rather than
1506 // HeapWordSize).
1507 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1508
1509 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1510 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1511 size_t heap_alignment = collector_policy()->heap_alignment();
1512
1513 // Ensure that the sizes are properly aligned.
1514 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1515 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1516 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1517
1518 // Reserve the maximum.
1519
1520 // When compressed oops are enabled, the preferred heap base
1521 // is calculated by subtracting the requested size from the
1522 // 32Gb boundary and using the result as the base address for
1523 // heap reservation. If the requested size is not aligned to
1524 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1525 // into the ReservedHeapSpace constructor) then the actual
1526 // base of the reserved heap may end up differing from the
1527 // address that was requested (i.e. the preferred heap base).
1528 // If this happens then we could end up using a non-optimal
1529 // compressed oops mode.
1530
1531 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1532 heap_alignment);
1533
1534 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1535
1536 // Create the barrier set for the entire reserved region.
1537 G1CardTable* ct = new G1CardTable(reserved_region());
1538 ct->initialize();
1539 G1BarrierSet* bs = new G1BarrierSet(ct);
1540 bs->initialize();
1541 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1542 set_barrier_set(bs);
1543 _card_table = ct;
1544
1545 // Create the hot card cache.
1546 _hot_card_cache = new G1HotCardCache(this);
1547
1548 // Carve out the G1 part of the heap.
1549 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1550 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1551 G1RegionToSpaceMapper* heap_storage =
1552 G1RegionToSpaceMapper::create_mapper(g1_rs,
1553 g1_rs.size(),
1554 page_size,
1555 HeapRegion::GrainBytes,
1556 1,
1557 mtJavaHeap);
1558 os::trace_page_sizes("Heap",
1559 collector_policy()->min_heap_byte_size(),
1560 max_byte_size,
1561 page_size,
1562 heap_rs.base(),
1563 heap_rs.size());
1564 heap_storage->set_mapping_changed_listener(&_listener);
1565
1566 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1567 G1RegionToSpaceMapper* bot_storage =
1568 create_aux_memory_mapper("Block Offset Table",
1569 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1570 G1BlockOffsetTable::heap_map_factor());
1571
1572 G1RegionToSpaceMapper* cardtable_storage =
1573 create_aux_memory_mapper("Card Table",
1574 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1575 G1CardTable::heap_map_factor());
1576
1577 G1RegionToSpaceMapper* card_counts_storage =
1578 create_aux_memory_mapper("Card Counts Table",
1579 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1580 G1CardCounts::heap_map_factor());
1581
1582 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1583 G1RegionToSpaceMapper* prev_bitmap_storage =
1584 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1585 G1RegionToSpaceMapper* next_bitmap_storage =
1586 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1587
1588 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1589 _card_table->initialize(cardtable_storage);
1590 // Do later initialization work for concurrent refinement.
1591 _hot_card_cache->initialize(card_counts_storage);
1592
1593 // 6843694 - ensure that the maximum region index can fit
1594 // in the remembered set structures.
1595 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1596 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1597
1598 // Also create a G1 rem set.
1599 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1600 _g1_rem_set->initialize(max_capacity(), max_regions());
1601
1602 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1603 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1604 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1605 "too many cards per region");
1606
1607 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1608
1609 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1610
1611 {
1612 HeapWord* start = _hrm.reserved().start();
1613 HeapWord* end = _hrm.reserved().end();
1614 size_t granularity = HeapRegion::GrainBytes;
1615
1616 _in_cset_fast_test.initialize(start, end, granularity);
1617 _humongous_reclaim_candidates.initialize(start, end, granularity);
1618 }
1619
1620 // Create the G1ConcurrentMark data structure and thread.
1621 // (Must do this late, so that "max_regions" is defined.)
1622 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1623 if (_cm == NULL || !_cm->completed_initialization()) {
1624 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1625 return JNI_ENOMEM;
1626 }
1627 _cmThread = _cm->cm_thread();
1628
1629 // Now expand into the initial heap size.
1630 if (!expand(init_byte_size, _workers)) {
1631 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1632 return JNI_ENOMEM;
1633 }
1634
1635 // Perform any initialization actions delegated to the policy.
1636 g1_policy()->init(this, &_collection_set);
1637
1638 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1639 SATB_Q_FL_lock,
1640 G1SATBProcessCompletedThreshold,
1641 Shared_SATB_Q_lock);
1642
1643 jint ecode = initialize_concurrent_refinement();
1644 if (ecode != JNI_OK) {
1645 return ecode;
1646 }
1647
1648 ecode = initialize_young_gen_sampling_thread();
1649 if (ecode != JNI_OK) {
1650 return ecode;
1651 }
1652
1653 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1654 DirtyCardQ_FL_lock,
1655 (int)concurrent_refine()->yellow_zone(),
1656 (int)concurrent_refine()->red_zone(),
1657 Shared_DirtyCardQ_lock,
1658 NULL, // fl_owner
1659 true); // init_free_ids
1660
1661 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1662 DirtyCardQ_FL_lock,
1663 -1, // never trigger processing
1664 -1, // no limit on length
1665 Shared_DirtyCardQ_lock,
1666 &JavaThread::dirty_card_queue_set());
1667
1668 // Here we allocate the dummy HeapRegion that is required by the
1669 // G1AllocRegion class.
1670 HeapRegion* dummy_region = _hrm.get_dummy_region();
1671
1672 // We'll re-use the same region whether the alloc region will
1673 // require BOT updates or not and, if it doesn't, then a non-young
1674 // region will complain that it cannot support allocations without
1675 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1676 dummy_region->set_eden();
1677 // Make sure it's full.
1678 dummy_region->set_top(dummy_region->end());
1679 G1AllocRegion::setup(this, dummy_region);
1680
1681 _allocator->init_mutator_alloc_region();
1682
1683 // Do create of the monitoring and management support so that
1684 // values in the heap have been properly initialized.
1685 _g1mm = new G1MonitoringSupport(this);
1686
1687 G1StringDedup::initialize();
1688
1689 _preserved_marks_set.init(ParallelGCThreads);
1690
1691 _collection_set.initialize(max_regions());
1692
1693 return JNI_OK;
1694 }
1695
1696 void G1CollectedHeap::initialize_serviceability() {
1697 _eden_pool = new G1EdenPool(this);
1698 _survivor_pool = new G1SurvivorPool(this);
1699 _old_pool = new G1OldGenPool(this);
1700
1701 _full_gc_memory_manager.add_pool(_eden_pool);
1702 _full_gc_memory_manager.add_pool(_survivor_pool);
1703 _full_gc_memory_manager.add_pool(_old_pool);
1704
1705 _memory_manager.add_pool(_eden_pool);
1706 _memory_manager.add_pool(_survivor_pool);
1707
1708 }
1709
1710 void G1CollectedHeap::stop() {
1711 // Stop all concurrent threads. We do this to make sure these threads
1712 // do not continue to execute and access resources (e.g. logging)
1713 // that are destroyed during shutdown.
1714 _cr->stop();
1715 _young_gen_sampling_thread->stop();
1716 _cmThread->stop();
1717 if (G1StringDedup::is_enabled()) {
1718 G1StringDedup::stop();
1719 }
1720 }
1721
1722 void G1CollectedHeap::safepoint_synchronize_begin() {
1723 SuspendibleThreadSet::synchronize();
1724 }
1725
1726 void G1CollectedHeap::safepoint_synchronize_end() {
1727 SuspendibleThreadSet::desynchronize();
1728 }
1729
1730 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1731 return HeapRegion::max_region_size();
1732 }
1733
1734 void G1CollectedHeap::post_initialize() {
1735 CollectedHeap::post_initialize();
1736 ref_processing_init();
1737 }
1738
1739 void G1CollectedHeap::ref_processing_init() {
1740 // Reference processing in G1 currently works as follows:
1741 //
1742 // * There are two reference processor instances. One is
1743 // used to record and process discovered references
1744 // during concurrent marking; the other is used to
1745 // record and process references during STW pauses
1746 // (both full and incremental).
1747 // * Both ref processors need to 'span' the entire heap as
1748 // the regions in the collection set may be dotted around.
1749 //
1750 // * For the concurrent marking ref processor:
1751 // * Reference discovery is enabled at initial marking.
1752 // * Reference discovery is disabled and the discovered
1753 // references processed etc during remarking.
1754 // * Reference discovery is MT (see below).
1755 // * Reference discovery requires a barrier (see below).
1756 // * Reference processing may or may not be MT
1757 // (depending on the value of ParallelRefProcEnabled
1758 // and ParallelGCThreads).
1759 // * A full GC disables reference discovery by the CM
1760 // ref processor and abandons any entries on it's
1761 // discovered lists.
1762 //
1763 // * For the STW processor:
1764 // * Non MT discovery is enabled at the start of a full GC.
1765 // * Processing and enqueueing during a full GC is non-MT.
1766 // * During a full GC, references are processed after marking.
1767 //
1768 // * Discovery (may or may not be MT) is enabled at the start
1769 // of an incremental evacuation pause.
1770 // * References are processed near the end of a STW evacuation pause.
1771 // * For both types of GC:
1772 // * Discovery is atomic - i.e. not concurrent.
1773 // * Reference discovery will not need a barrier.
1774
1775 MemRegion mr = reserved_region();
1776
1777 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1778
1779 // Concurrent Mark ref processor
1780 _ref_processor_cm =
1781 new ReferenceProcessor(mr, // span
1782 mt_processing,
1783 // mt processing
1784 ParallelGCThreads,
1785 // degree of mt processing
1786 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1787 // mt discovery
1788 MAX2(ParallelGCThreads, ConcGCThreads),
1789 // degree of mt discovery
1790 false,
1791 // Reference discovery is not atomic
1792 &_is_alive_closure_cm);
1793 // is alive closure
1794 // (for efficiency/performance)
1795
1796 // STW ref processor
1797 _ref_processor_stw =
1798 new ReferenceProcessor(mr, // span
1799 mt_processing,
1800 // mt processing
1801 ParallelGCThreads,
1802 // degree of mt processing
1803 (ParallelGCThreads > 1),
1804 // mt discovery
1805 ParallelGCThreads,
1806 // degree of mt discovery
1807 true,
1808 // Reference discovery is atomic
1809 &_is_alive_closure_stw);
1810 // is alive closure
1811 // (for efficiency/performance)
1812 }
1813
1814 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1815 return _collector_policy;
1816 }
1817
1818 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1819 return &_soft_ref_policy;
1820 }
1821
1822 size_t G1CollectedHeap::capacity() const {
1823 return _hrm.length() * HeapRegion::GrainBytes;
1824 }
1825
1826 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1827 return _hrm.total_free_bytes();
1828 }
1829
1830 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1831 _hot_card_cache->drain(cl, worker_i);
1832 }
1833
1834 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1835 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1836 size_t n_completed_buffers = 0;
1837 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1838 n_completed_buffers++;
1839 }
1840 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1841 dcqs.clear_n_completed_buffers();
1842 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1843 }
1844
1845 // Computes the sum of the storage used by the various regions.
1846 size_t G1CollectedHeap::used() const {
1847 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1848 if (_archive_allocator != NULL) {
1849 result += _archive_allocator->used();
1850 }
1851 return result;
1852 }
1853
1854 size_t G1CollectedHeap::used_unlocked() const {
1855 return _summary_bytes_used;
1856 }
1857
1858 class SumUsedClosure: public HeapRegionClosure {
1859 size_t _used;
1860 public:
1861 SumUsedClosure() : _used(0) {}
1862 bool do_heap_region(HeapRegion* r) {
1863 _used += r->used();
1864 return false;
1865 }
1866 size_t result() { return _used; }
1867 };
1868
1869 size_t G1CollectedHeap::recalculate_used() const {
1870 double recalculate_used_start = os::elapsedTime();
1871
1872 SumUsedClosure blk;
1873 heap_region_iterate(&blk);
1874
1875 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1876 return blk.result();
1877 }
1878
1879 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1880 switch (cause) {
1881 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1882 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1883 case GCCause::_wb_conc_mark: return true;
1884 default : return false;
1885 }
1886 }
1887
1888 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1889 switch (cause) {
1890 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1891 case GCCause::_g1_humongous_allocation: return true;
1892 default: return is_user_requested_concurrent_full_gc(cause);
1893 }
1894 }
1895
1896 #ifndef PRODUCT
1897 void G1CollectedHeap::allocate_dummy_regions() {
1898 // Let's fill up most of the region
1899 size_t word_size = HeapRegion::GrainWords - 1024;
1900 // And as a result the region we'll allocate will be humongous.
1901 guarantee(is_humongous(word_size), "sanity");
1902
1903 // _filler_array_max_size is set to humongous object threshold
1904 // but temporarily change it to use CollectedHeap::fill_with_object().
1905 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1906
1907 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1908 // Let's use the existing mechanism for the allocation
1909 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1910 if (dummy_obj != NULL) {
1911 MemRegion mr(dummy_obj, word_size);
1912 CollectedHeap::fill_with_object(mr);
1913 } else {
1914 // If we can't allocate once, we probably cannot allocate
1915 // again. Let's get out of the loop.
1916 break;
1917 }
1918 }
1919 }
1920 #endif // !PRODUCT
1921
1922 void G1CollectedHeap::increment_old_marking_cycles_started() {
1923 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1924 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1925 "Wrong marking cycle count (started: %d, completed: %d)",
1926 _old_marking_cycles_started, _old_marking_cycles_completed);
1927
1928 _old_marking_cycles_started++;
1929 }
1930
1931 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
1932 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1933
1934 // We assume that if concurrent == true, then the caller is a
1935 // concurrent thread that was joined the Suspendible Thread
1936 // Set. If there's ever a cheap way to check this, we should add an
1937 // assert here.
1938
1939 // Given that this method is called at the end of a Full GC or of a
1940 // concurrent cycle, and those can be nested (i.e., a Full GC can
1941 // interrupt a concurrent cycle), the number of full collections
1942 // completed should be either one (in the case where there was no
1943 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1944 // behind the number of full collections started.
1945
1946 // This is the case for the inner caller, i.e. a Full GC.
1947 assert(concurrent ||
1948 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1949 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1950 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1951 "is inconsistent with _old_marking_cycles_completed = %u",
1952 _old_marking_cycles_started, _old_marking_cycles_completed);
1953
1954 // This is the case for the outer caller, i.e. the concurrent cycle.
1955 assert(!concurrent ||
1956 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1957 "for outer caller (concurrent cycle): "
1958 "_old_marking_cycles_started = %u "
1959 "is inconsistent with _old_marking_cycles_completed = %u",
1960 _old_marking_cycles_started, _old_marking_cycles_completed);
1961
1962 _old_marking_cycles_completed += 1;
1963
1964 // We need to clear the "in_progress" flag in the CM thread before
1965 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1966 // is set) so that if a waiter requests another System.gc() it doesn't
1967 // incorrectly see that a marking cycle is still in progress.
1968 if (concurrent) {
1969 _cmThread->set_idle();
1970 }
1971
1972 // This notify_all() will ensure that a thread that called
1973 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
1974 // and it's waiting for a full GC to finish will be woken up. It is
1975 // waiting in VM_G1CollectForAllocation::doit_epilogue().
1976 FullGCCount_lock->notify_all();
1977 }
1978
1979 void G1CollectedHeap::collect(GCCause::Cause cause) {
1980 assert_heap_not_locked();
1981
1982 uint gc_count_before;
1983 uint old_marking_count_before;
1984 uint full_gc_count_before;
1985 bool retry_gc;
1986
1987 do {
1988 retry_gc = false;
1989
1990 {
1991 MutexLocker ml(Heap_lock);
1992
1993 // Read the GC count while holding the Heap_lock
1994 gc_count_before = total_collections();
1995 full_gc_count_before = total_full_collections();
1996 old_marking_count_before = _old_marking_cycles_started;
1997 }
1998
1999 if (should_do_concurrent_full_gc(cause)) {
2000 // Schedule an initial-mark evacuation pause that will start a
2001 // concurrent cycle. We're setting word_size to 0 which means that
2002 // we are not requesting a post-GC allocation.
2003 VM_G1CollectForAllocation op(0, /* word_size */
2004 gc_count_before,
2005 cause,
2006 true, /* should_initiate_conc_mark */
2007 g1_policy()->max_pause_time_ms());
2008 VMThread::execute(&op);
2009 if (!op.pause_succeeded()) {
2010 if (old_marking_count_before == _old_marking_cycles_started) {
2011 retry_gc = op.should_retry_gc();
2012 } else {
2013 // A Full GC happened while we were trying to schedule the
2014 // initial-mark GC. No point in starting a new cycle given
2015 // that the whole heap was collected anyway.
2016 }
2017
2018 if (retry_gc) {
2019 if (GCLocker::is_active_and_needs_gc()) {
2020 GCLocker::stall_until_clear();
2021 }
2022 }
2023 }
2024 } else {
2025 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2026 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2027
2028 // Schedule a standard evacuation pause. We're setting word_size
2029 // to 0 which means that we are not requesting a post-GC allocation.
2030 VM_G1CollectForAllocation op(0, /* word_size */
2031 gc_count_before,
2032 cause,
2033 false, /* should_initiate_conc_mark */
2034 g1_policy()->max_pause_time_ms());
2035 VMThread::execute(&op);
2036 } else {
2037 // Schedule a Full GC.
2038 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2039 VMThread::execute(&op);
2040 }
2041 }
2042 } while (retry_gc);
2043 }
2044
2045 bool G1CollectedHeap::is_in(const void* p) const {
2046 if (_hrm.reserved().contains(p)) {
2047 // Given that we know that p is in the reserved space,
2048 // heap_region_containing() should successfully
2049 // return the containing region.
2050 HeapRegion* hr = heap_region_containing(p);
2051 return hr->is_in(p);
2052 } else {
2053 return false;
2054 }
2055 }
2056
2057 #ifdef ASSERT
2058 bool G1CollectedHeap::is_in_exact(const void* p) const {
2059 bool contains = reserved_region().contains(p);
2060 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2061 if (contains && available) {
2062 return true;
2063 } else {
2064 return false;
2065 }
2066 }
2067 #endif
2068
2069 // Iteration functions.
2070
2071 // Iterates an ObjectClosure over all objects within a HeapRegion.
2072
2073 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2074 ObjectClosure* _cl;
2075 public:
2076 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2077 bool do_heap_region(HeapRegion* r) {
2078 if (!r->is_continues_humongous()) {
2079 r->object_iterate(_cl);
2080 }
2081 return false;
2082 }
2083 };
2084
2085 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2086 IterateObjectClosureRegionClosure blk(cl);
2087 heap_region_iterate(&blk);
2088 }
2089
2090 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2091 _hrm.iterate(cl);
2092 }
2093
2094 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2095 HeapRegionClaimer *hrclaimer,
2096 uint worker_id) const {
2097 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2098 }
2099
2100 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2101 HeapRegionClaimer *hrclaimer) const {
2102 _hrm.par_iterate(cl, hrclaimer, 0);
2103 }
2104
2105 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2106 _collection_set.iterate(cl);
2107 }
2108
2109 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2110 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2111 }
2112
2113 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2114 HeapRegion* hr = heap_region_containing(addr);
2115 return hr->block_start(addr);
2116 }
2117
2118 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2119 HeapRegion* hr = heap_region_containing(addr);
2120 return hr->block_size(addr);
2121 }
2122
2123 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2124 HeapRegion* hr = heap_region_containing(addr);
2125 return hr->block_is_obj(addr);
2126 }
2127
2128 bool G1CollectedHeap::supports_tlab_allocation() const {
2129 return true;
2130 }
2131
2132 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2133 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2134 }
2135
2136 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2137 return _eden.length() * HeapRegion::GrainBytes;
2138 }
2139
2140 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2141 // must be equal to the humongous object limit.
2142 size_t G1CollectedHeap::max_tlab_size() const {
2143 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2144 }
2145
2146 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2147 return _allocator->unsafe_max_tlab_alloc();
2148 }
2149
2150 size_t G1CollectedHeap::max_capacity() const {
2151 return _hrm.reserved().byte_size();
2152 }
2153
2154 jlong G1CollectedHeap::millis_since_last_gc() {
2155 // See the notes in GenCollectedHeap::millis_since_last_gc()
2156 // for more information about the implementation.
2157 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2158 _g1_policy->collection_pause_end_millis();
2159 if (ret_val < 0) {
2160 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2161 ". returning zero instead.", ret_val);
2162 return 0;
2163 }
2164 return ret_val;
2165 }
2166
2167 void G1CollectedHeap::prepare_for_verify() {
2168 _verifier->prepare_for_verify();
2169 }
2170
2171 void G1CollectedHeap::verify(VerifyOption vo) {
2172 _verifier->verify(vo);
2173 }
2174
2175 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2176 return true;
2177 }
2178
2179 const char* const* G1CollectedHeap::concurrent_phases() const {
2180 return _cmThread->concurrent_phases();
2181 }
2182
2183 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2184 return _cmThread->request_concurrent_phase(phase);
2185 }
2186
2187 class PrintRegionClosure: public HeapRegionClosure {
2188 outputStream* _st;
2189 public:
2190 PrintRegionClosure(outputStream* st) : _st(st) {}
2191 bool do_heap_region(HeapRegion* r) {
2192 r->print_on(_st);
2193 return false;
2194 }
2195 };
2196
2197 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2198 const HeapRegion* hr,
2199 const VerifyOption vo) const {
2200 switch (vo) {
2201 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2202 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2203 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2204 default: ShouldNotReachHere();
2205 }
2206 return false; // keep some compilers happy
2207 }
2208
2209 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2210 const VerifyOption vo) const {
2211 switch (vo) {
2212 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2213 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2214 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2215 default: ShouldNotReachHere();
2216 }
2217 return false; // keep some compilers happy
2218 }
2219
2220 void G1CollectedHeap::print_heap_regions() const {
2221 LogTarget(Trace, gc, heap, region) lt;
2222 if (lt.is_enabled()) {
2223 LogStream ls(lt);
2224 print_regions_on(&ls);
2225 }
2226 }
2227
2228 void G1CollectedHeap::print_on(outputStream* st) const {
2229 st->print(" %-20s", "garbage-first heap");
2230 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2231 capacity()/K, used_unlocked()/K);
2232 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2233 p2i(_hrm.reserved().start()),
2234 p2i(_hrm.reserved().end()));
2235 st->cr();
2236 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2237 uint young_regions = young_regions_count();
2238 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2239 (size_t) young_regions * HeapRegion::GrainBytes / K);
2240 uint survivor_regions = survivor_regions_count();
2241 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2242 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2243 st->cr();
2244 MetaspaceUtils::print_on(st);
2245 }
2246
2247 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2248 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2249 "HS=humongous(starts), HC=humongous(continues), "
2250 "CS=collection set, F=free, A=archive, "
2251 "TAMS=top-at-mark-start (previous, next)");
2252 PrintRegionClosure blk(st);
2253 heap_region_iterate(&blk);
2254 }
2255
2256 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2257 print_on(st);
2258
2259 // Print the per-region information.
2260 print_regions_on(st);
2261 }
2262
2263 void G1CollectedHeap::print_on_error(outputStream* st) const {
2264 this->CollectedHeap::print_on_error(st);
2265
2266 if (_cm != NULL) {
2267 st->cr();
2268 _cm->print_on_error(st);
2269 }
2270 }
2271
2272 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2273 workers()->print_worker_threads_on(st);
2274 _cmThread->print_on(st);
2275 st->cr();
2276 _cm->print_worker_threads_on(st);
2277 _cr->print_threads_on(st);
2278 _young_gen_sampling_thread->print_on(st);
2279 if (G1StringDedup::is_enabled()) {
2280 G1StringDedup::print_worker_threads_on(st);
2281 }
2282 }
2283
2284 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2285 workers()->threads_do(tc);
2286 tc->do_thread(_cmThread);
2287 _cm->threads_do(tc);
2288 _cr->threads_do(tc);
2289 tc->do_thread(_young_gen_sampling_thread);
2290 if (G1StringDedup::is_enabled()) {
2291 G1StringDedup::threads_do(tc);
2292 }
2293 }
2294
2295 void G1CollectedHeap::print_tracing_info() const {
2296 g1_rem_set()->print_summary_info();
2297 concurrent_mark()->print_summary_info();
2298 }
2299
2300 #ifndef PRODUCT
2301 // Helpful for debugging RSet issues.
2302
2303 class PrintRSetsClosure : public HeapRegionClosure {
2304 private:
2305 const char* _msg;
2306 size_t _occupied_sum;
2307
2308 public:
2309 bool do_heap_region(HeapRegion* r) {
2310 HeapRegionRemSet* hrrs = r->rem_set();
2311 size_t occupied = hrrs->occupied();
2312 _occupied_sum += occupied;
2313
2314 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2315 if (occupied == 0) {
2316 tty->print_cr(" RSet is empty");
2317 } else {
2318 hrrs->print();
2319 }
2320 tty->print_cr("----------");
2321 return false;
2322 }
2323
2324 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2325 tty->cr();
2326 tty->print_cr("========================================");
2327 tty->print_cr("%s", msg);
2328 tty->cr();
2329 }
2330
2331 ~PrintRSetsClosure() {
2332 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2333 tty->print_cr("========================================");
2334 tty->cr();
2335 }
2336 };
2337
2338 void G1CollectedHeap::print_cset_rsets() {
2339 PrintRSetsClosure cl("Printing CSet RSets");
2340 collection_set_iterate(&cl);
2341 }
2342
2343 void G1CollectedHeap::print_all_rsets() {
2344 PrintRSetsClosure cl("Printing All RSets");;
2345 heap_region_iterate(&cl);
2346 }
2347 #endif // PRODUCT
2348
2349 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2350
2351 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2352 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2353 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2354
2355 size_t eden_capacity_bytes =
2356 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2357
2358 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2359 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2360 eden_capacity_bytes, survivor_used_bytes, num_regions());
2361 }
2362
2363 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2364 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2365 stats->unused(), stats->used(), stats->region_end_waste(),
2366 stats->regions_filled(), stats->direct_allocated(),
2367 stats->failure_used(), stats->failure_waste());
2368 }
2369
2370 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2371 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2372 gc_tracer->report_gc_heap_summary(when, heap_summary);
2373
2374 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2375 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2376 }
2377
2378 G1CollectedHeap* G1CollectedHeap::heap() {
2379 CollectedHeap* heap = Universe::heap();
2380 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2381 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2382 return (G1CollectedHeap*)heap;
2383 }
2384
2385 void G1CollectedHeap::gc_prologue(bool full) {
2386 // always_do_update_barrier = false;
2387 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2388
2389 // This summary needs to be printed before incrementing total collections.
2390 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2391
2392 // Update common counters.
2393 increment_total_collections(full /* full gc */);
2394 if (full) {
2395 increment_old_marking_cycles_started();
2396 }
2397
2398 // Fill TLAB's and such
2399 double start = os::elapsedTime();
2400 accumulate_statistics_all_tlabs();
2401 ensure_parsability(true);
2402 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2403 }
2404
2405 void G1CollectedHeap::gc_epilogue(bool full) {
2406 // Update common counters.
2407 if (full) {
2408 // Update the number of full collections that have been completed.
2409 increment_old_marking_cycles_completed(false /* concurrent */);
2410 }
2411
2412 // We are at the end of the GC. Total collections has already been increased.
2413 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2414
2415 // FIXME: what is this about?
2416 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2417 // is set.
2418 #if COMPILER2_OR_JVMCI
2419 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2420 #endif
2421 // always_do_update_barrier = true;
2422
2423 double start = os::elapsedTime();
2424 resize_all_tlabs();
2425 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2426
2427 MemoryService::track_memory_usage();
2428 // We have just completed a GC. Update the soft reference
2429 // policy with the new heap occupancy
2430 Universe::update_heap_info_at_gc();
2431 }
2432
2433 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2434 uint gc_count_before,
2435 bool* succeeded,
2436 GCCause::Cause gc_cause) {
2437 assert_heap_not_locked_and_not_at_safepoint();
2438 VM_G1CollectForAllocation op(word_size,
2439 gc_count_before,
2440 gc_cause,
2441 false, /* should_initiate_conc_mark */
2442 g1_policy()->max_pause_time_ms());
2443 VMThread::execute(&op);
2444
2445 HeapWord* result = op.result();
2446 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2447 assert(result == NULL || ret_succeeded,
2448 "the result should be NULL if the VM did not succeed");
2449 *succeeded = ret_succeeded;
2450
2451 assert_heap_not_locked();
2452 return result;
2453 }
2454
2455 void G1CollectedHeap::do_concurrent_mark() {
2456 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2457 if (!_cmThread->in_progress()) {
2458 _cmThread->set_started();
2459 CGC_lock->notify();
2460 }
2461 }
2462
2463 size_t G1CollectedHeap::pending_card_num() {
2464 size_t extra_cards = 0;
2465 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2466 DirtyCardQueue& dcq = curr->dirty_card_queue();
2467 extra_cards += dcq.size();
2468 }
2469 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2470 size_t buffer_size = dcqs.buffer_size();
2471 size_t buffer_num = dcqs.completed_buffers_num();
2472
2473 return buffer_size * buffer_num + extra_cards;
2474 }
2475
2476 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2477 // We don't nominate objects with many remembered set entries, on
2478 // the assumption that such objects are likely still live.
2479 HeapRegionRemSet* rem_set = r->rem_set();
2480
2481 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2482 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2483 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2484 }
2485
2486 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2487 private:
2488 size_t _total_humongous;
2489 size_t _candidate_humongous;
2490
2491 DirtyCardQueue _dcq;
2492
2493 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2494 assert(region->is_starts_humongous(), "Must start a humongous object");
2495
2496 oop obj = oop(region->bottom());
2497
2498 // Dead objects cannot be eager reclaim candidates. Due to class
2499 // unloading it is unsafe to query their classes so we return early.
2500 if (g1h->is_obj_dead(obj, region)) {
2501 return false;
2502 }
2503
2504 // If we do not have a complete remembered set for the region, then we can
2505 // not be sure that we have all references to it.
2506 if (!region->rem_set()->is_complete()) {
2507 return false;
2508 }
2509 // Candidate selection must satisfy the following constraints
2510 // while concurrent marking is in progress:
2511 //
2512 // * In order to maintain SATB invariants, an object must not be
2513 // reclaimed if it was allocated before the start of marking and
2514 // has not had its references scanned. Such an object must have
2515 // its references (including type metadata) scanned to ensure no
2516 // live objects are missed by the marking process. Objects
2517 // allocated after the start of concurrent marking don't need to
2518 // be scanned.
2519 //
2520 // * An object must not be reclaimed if it is on the concurrent
2521 // mark stack. Objects allocated after the start of concurrent
2522 // marking are never pushed on the mark stack.
2523 //
2524 // Nominating only objects allocated after the start of concurrent
2525 // marking is sufficient to meet both constraints. This may miss
2526 // some objects that satisfy the constraints, but the marking data
2527 // structures don't support efficiently performing the needed
2528 // additional tests or scrubbing of the mark stack.
2529 //
2530 // However, we presently only nominate is_typeArray() objects.
2531 // A humongous object containing references induces remembered
2532 // set entries on other regions. In order to reclaim such an
2533 // object, those remembered sets would need to be cleaned up.
2534 //
2535 // We also treat is_typeArray() objects specially, allowing them
2536 // to be reclaimed even if allocated before the start of
2537 // concurrent mark. For this we rely on mark stack insertion to
2538 // exclude is_typeArray() objects, preventing reclaiming an object
2539 // that is in the mark stack. We also rely on the metadata for
2540 // such objects to be built-in and so ensured to be kept live.
2541 // Frequent allocation and drop of large binary blobs is an
2542 // important use case for eager reclaim, and this special handling
2543 // may reduce needed headroom.
2544
2545 return obj->is_typeArray() &&
2546 g1h->is_potential_eager_reclaim_candidate(region);
2547 }
2548
2549 public:
2550 RegisterHumongousWithInCSetFastTestClosure()
2551 : _total_humongous(0),
2552 _candidate_humongous(0),
2553 _dcq(&JavaThread::dirty_card_queue_set()) {
2554 }
2555
2556 virtual bool do_heap_region(HeapRegion* r) {
2557 if (!r->is_starts_humongous()) {
2558 return false;
2559 }
2560 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2561
2562 bool is_candidate = humongous_region_is_candidate(g1h, r);
2563 uint rindex = r->hrm_index();
2564 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2565 if (is_candidate) {
2566 _candidate_humongous++;
2567 g1h->register_humongous_region_with_cset(rindex);
2568 // Is_candidate already filters out humongous object with large remembered sets.
2569 // If we have a humongous object with a few remembered sets, we simply flush these
2570 // remembered set entries into the DCQS. That will result in automatic
2571 // re-evaluation of their remembered set entries during the following evacuation
2572 // phase.
2573 if (!r->rem_set()->is_empty()) {
2574 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2575 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2576 G1CardTable* ct = g1h->card_table();
2577 HeapRegionRemSetIterator hrrs(r->rem_set());
2578 size_t card_index;
2579 while (hrrs.has_next(card_index)) {
2580 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2581 // The remembered set might contain references to already freed
2582 // regions. Filter out such entries to avoid failing card table
2583 // verification.
2584 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2585 if (*card_ptr != G1CardTable::dirty_card_val()) {
2586 *card_ptr = G1CardTable::dirty_card_val();
2587 _dcq.enqueue(card_ptr);
2588 }
2589 }
2590 }
2591 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2592 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2593 hrrs.n_yielded(), r->rem_set()->occupied());
2594 // We should only clear the card based remembered set here as we will not
2595 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2596 // (and probably never) we do not enter this path if there are other kind of
2597 // remembered sets for this region.
2598 r->rem_set()->clear_locked(true /* only_cardset */);
2599 // Clear_locked() above sets the state to Empty. However we want to continue
2600 // collecting remembered set entries for humongous regions that were not
2601 // reclaimed.
2602 r->rem_set()->set_state_complete();
2603 }
2604 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2605 }
2606 _total_humongous++;
2607
2608 return false;
2609 }
2610
2611 size_t total_humongous() const { return _total_humongous; }
2612 size_t candidate_humongous() const { return _candidate_humongous; }
2613
2614 void flush_rem_set_entries() { _dcq.flush(); }
2615 };
2616
2617 void G1CollectedHeap::register_humongous_regions_with_cset() {
2618 if (!G1EagerReclaimHumongousObjects) {
2619 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2620 return;
2621 }
2622 double time = os::elapsed_counter();
2623
2624 // Collect reclaim candidate information and register candidates with cset.
2625 RegisterHumongousWithInCSetFastTestClosure cl;
2626 heap_region_iterate(&cl);
2627
2628 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2629 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2630 cl.total_humongous(),
2631 cl.candidate_humongous());
2632 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2633
2634 // Finally flush all remembered set entries to re-check into the global DCQS.
2635 cl.flush_rem_set_entries();
2636 }
2637
2638 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2639 public:
2640 bool do_heap_region(HeapRegion* hr) {
2641 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2642 hr->verify_rem_set();
2643 }
2644 return false;
2645 }
2646 };
2647
2648 uint G1CollectedHeap::num_task_queues() const {
2649 return _task_queues->size();
2650 }
2651
2652 #if TASKQUEUE_STATS
2653 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2654 st->print_raw_cr("GC Task Stats");
2655 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2656 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2657 }
2658
2659 void G1CollectedHeap::print_taskqueue_stats() const {
2660 if (!log_is_enabled(Trace, gc, task, stats)) {
2661 return;
2662 }
2663 Log(gc, task, stats) log;
2664 ResourceMark rm;
2665 LogStream ls(log.trace());
2666 outputStream* st = &ls;
2667
2668 print_taskqueue_stats_hdr(st);
2669
2670 TaskQueueStats totals;
2671 const uint n = num_task_queues();
2672 for (uint i = 0; i < n; ++i) {
2673 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2674 totals += task_queue(i)->stats;
2675 }
2676 st->print_raw("tot "); totals.print(st); st->cr();
2677
2678 DEBUG_ONLY(totals.verify());
2679 }
2680
2681 void G1CollectedHeap::reset_taskqueue_stats() {
2682 const uint n = num_task_queues();
2683 for (uint i = 0; i < n; ++i) {
2684 task_queue(i)->stats.reset();
2685 }
2686 }
2687 #endif // TASKQUEUE_STATS
2688
2689 void G1CollectedHeap::wait_for_root_region_scanning() {
2690 double scan_wait_start = os::elapsedTime();
2691 // We have to wait until the CM threads finish scanning the
2692 // root regions as it's the only way to ensure that all the
2693 // objects on them have been correctly scanned before we start
2694 // moving them during the GC.
2695 bool waited = _cm->root_regions()->wait_until_scan_finished();
2696 double wait_time_ms = 0.0;
2697 if (waited) {
2698 double scan_wait_end = os::elapsedTime();
2699 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2700 }
2701 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2702 }
2703
2704 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2705 private:
2706 G1HRPrinter* _hr_printer;
2707 public:
2708 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2709
2710 virtual bool do_heap_region(HeapRegion* r) {
2711 _hr_printer->cset(r);
2712 return false;
2713 }
2714 };
2715
2716 void G1CollectedHeap::start_new_collection_set() {
2717 collection_set()->start_incremental_building();
2718
2719 clear_cset_fast_test();
2720
2721 guarantee(_eden.length() == 0, "eden should have been cleared");
2722 g1_policy()->transfer_survivors_to_cset(survivor());
2723 }
2724
2725 bool
2726 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2727 assert_at_safepoint_on_vm_thread();
2728 guarantee(!is_gc_active(), "collection is not reentrant");
2729
2730 if (GCLocker::check_active_before_gc()) {
2731 return false;
2732 }
2733
2734 _gc_timer_stw->register_gc_start();
2735
2736 GCIdMark gc_id_mark;
2737 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2738
2739 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2740 ResourceMark rm;
2741
2742 g1_policy()->note_gc_start();
2743
2744 wait_for_root_region_scanning();
2745
2746 print_heap_before_gc();
2747 print_heap_regions();
2748 trace_heap_before_gc(_gc_tracer_stw);
2749
2750 _verifier->verify_region_sets_optional();
2751 _verifier->verify_dirty_young_regions();
2752
2753 // We should not be doing initial mark unless the conc mark thread is running
2754 if (!_cmThread->should_terminate()) {
2755 // This call will decide whether this pause is an initial-mark
2756 // pause. If it is, in_initial_mark_gc() will return true
2757 // for the duration of this pause.
2758 g1_policy()->decide_on_conc_mark_initiation();
2759 }
2760
2761 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2762 assert(!collector_state()->in_initial_mark_gc() ||
2763 collector_state()->in_young_only_phase(), "sanity");
2764
2765 // We also do not allow mixed GCs during marking.
2766 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2767
2768 // Record whether this pause is an initial mark. When the current
2769 // thread has completed its logging output and it's safe to signal
2770 // the CM thread, the flag's value in the policy has been reset.
2771 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2772
2773 // Inner scope for scope based logging, timers, and stats collection
2774 {
2775 EvacuationInfo evacuation_info;
2776
2777 if (collector_state()->in_initial_mark_gc()) {
2778 // We are about to start a marking cycle, so we increment the
2779 // full collection counter.
2780 increment_old_marking_cycles_started();
2781 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2782 }
2783
2784 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2785
2786 GCTraceCPUTime tcpu;
2787
2788 G1HeapVerifier::G1VerifyType verify_type;
2789 FormatBuffer<> gc_string("Pause ");
2790 if (collector_state()->in_initial_mark_gc()) {
2791 gc_string.append("Initial Mark");
2792 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2793 } else if (collector_state()->in_young_only_phase()) {
2794 gc_string.append("Young");
2795 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2796 } else {
2797 gc_string.append("Mixed");
2798 verify_type = G1HeapVerifier::G1VerifyMixed;
2799 }
2800 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2801
2802 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2803 workers()->active_workers(),
2804 Threads::number_of_non_daemon_threads());
2805 active_workers = workers()->update_active_workers(active_workers);
2806 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2807
2808 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2809 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2810
2811 G1HeapTransition heap_transition(this);
2812 size_t heap_used_bytes_before_gc = used();
2813
2814 // Don't dynamically change the number of GC threads this early. A value of
2815 // 0 is used to indicate serial work. When parallel work is done,
2816 // it will be set.
2817
2818 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2819 IsGCActiveMark x;
2820
2821 gc_prologue(false);
2822
2823 if (VerifyRememberedSets) {
2824 log_info(gc, verify)("[Verifying RemSets before GC]");
2825 VerifyRegionRemSetClosure v_cl;
2826 heap_region_iterate(&v_cl);
2827 }
2828
2829 _verifier->verify_before_gc(verify_type);
2830
2831 _verifier->check_bitmaps("GC Start");
2832
2833 #if COMPILER2_OR_JVMCI
2834 DerivedPointerTable::clear();
2835 #endif
2836
2837 // Please see comment in g1CollectedHeap.hpp and
2838 // G1CollectedHeap::ref_processing_init() to see how
2839 // reference processing currently works in G1.
2840
2841 // Enable discovery in the STW reference processor
2842 if (g1_policy()->should_process_references()) {
2843 ref_processor_stw()->enable_discovery();
2844 } else {
2845 ref_processor_stw()->disable_discovery();
2846 }
2847
2848 {
2849 // We want to temporarily turn off discovery by the
2850 // CM ref processor, if necessary, and turn it back on
2851 // on again later if we do. Using a scoped
2852 // NoRefDiscovery object will do this.
2853 NoRefDiscovery no_cm_discovery(ref_processor_cm());
2854
2855 // Forget the current alloc region (we might even choose it to be part
2856 // of the collection set!).
2857 _allocator->release_mutator_alloc_region();
2858
2859 // This timing is only used by the ergonomics to handle our pause target.
2860 // It is unclear why this should not include the full pause. We will
2861 // investigate this in CR 7178365.
2862 //
2863 // Preserving the old comment here if that helps the investigation:
2864 //
2865 // The elapsed time induced by the start time below deliberately elides
2866 // the possible verification above.
2867 double sample_start_time_sec = os::elapsedTime();
2868
2869 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2870
2871 if (collector_state()->in_initial_mark_gc()) {
2872 concurrent_mark()->pre_initial_mark();
2873 }
2874
2875 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2876
2877 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2878
2879 // Make sure the remembered sets are up to date. This needs to be
2880 // done before register_humongous_regions_with_cset(), because the
2881 // remembered sets are used there to choose eager reclaim candidates.
2882 // If the remembered sets are not up to date we might miss some
2883 // entries that need to be handled.
2884 g1_rem_set()->cleanupHRRS();
2885
2886 register_humongous_regions_with_cset();
2887
2888 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2889
2890 // We call this after finalize_cset() to
2891 // ensure that the CSet has been finalized.
2892 _cm->verify_no_cset_oops();
2893
2894 if (_hr_printer.is_active()) {
2895 G1PrintCollectionSetClosure cl(&_hr_printer);
2896 _collection_set.iterate(&cl);
2897 }
2898
2899 // Initialize the GC alloc regions.
2900 _allocator->init_gc_alloc_regions(evacuation_info);
2901
2902 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2903 pre_evacuate_collection_set();
2904
2905 // Actually do the work...
2906 evacuate_collection_set(&per_thread_states);
2907
2908 post_evacuate_collection_set(evacuation_info, &per_thread_states);
2909
2910 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2911 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2912
2913 eagerly_reclaim_humongous_regions();
2914
2915 record_obj_copy_mem_stats();
2916 _survivor_evac_stats.adjust_desired_plab_sz();
2917 _old_evac_stats.adjust_desired_plab_sz();
2918
2919 double start = os::elapsedTime();
2920 start_new_collection_set();
2921 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2922
2923 if (evacuation_failed()) {
2924 set_used(recalculate_used());
2925 if (_archive_allocator != NULL) {
2926 _archive_allocator->clear_used();
2927 }
2928 for (uint i = 0; i < ParallelGCThreads; i++) {
2929 if (_evacuation_failed_info_array[i].has_failed()) {
2930 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
2931 }
2932 }
2933 } else {
2934 // The "used" of the the collection set have already been subtracted
2935 // when they were freed. Add in the bytes evacuated.
2936 increase_used(g1_policy()->bytes_copied_during_gc());
2937 }
2938
2939 if (collector_state()->in_initial_mark_gc()) {
2940 // We have to do this before we notify the CM threads that
2941 // they can start working to make sure that all the
2942 // appropriate initialization is done on the CM object.
2943 concurrent_mark()->post_initial_mark();
2944 // Note that we don't actually trigger the CM thread at
2945 // this point. We do that later when we're sure that
2946 // the current thread has completed its logging output.
2947 }
2948
2949 allocate_dummy_regions();
2950
2951 _allocator->init_mutator_alloc_region();
2952
2953 {
2954 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2955 if (expand_bytes > 0) {
2956 size_t bytes_before = capacity();
2957 // No need for an ergo logging here,
2958 // expansion_amount() does this when it returns a value > 0.
2959 double expand_ms;
2960 if (!expand(expand_bytes, _workers, &expand_ms)) {
2961 // We failed to expand the heap. Cannot do anything about it.
2962 }
2963 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
2964 }
2965 }
2966
2967 // We redo the verification but now wrt to the new CSet which
2968 // has just got initialized after the previous CSet was freed.
2969 _cm->verify_no_cset_oops();
2970
2971 // This timing is only used by the ergonomics to handle our pause target.
2972 // It is unclear why this should not include the full pause. We will
2973 // investigate this in CR 7178365.
2974 double sample_end_time_sec = os::elapsedTime();
2975 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
2976 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
2977 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
2978
2979 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
2980 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
2981
2982 if (VerifyRememberedSets) {
2983 log_info(gc, verify)("[Verifying RemSets after GC]");
2984 VerifyRegionRemSetClosure v_cl;
2985 heap_region_iterate(&v_cl);
2986 }
2987
2988 _verifier->verify_after_gc(verify_type);
2989 _verifier->check_bitmaps("GC End");
2990
2991 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
2992 ref_processor_stw()->verify_no_references_recorded();
2993
2994 // CM reference discovery will be re-enabled if necessary.
2995 }
2996
2997 #ifdef TRACESPINNING
2998 ParallelTaskTerminator::print_termination_counts();
2999 #endif
3000
3001 gc_epilogue(false);
3002 }
3003
3004 // Print the remainder of the GC log output.
3005 if (evacuation_failed()) {
3006 log_info(gc)("To-space exhausted");
3007 }
3008
3009 g1_policy()->print_phases();
3010 heap_transition.print();
3011
3012 // It is not yet to safe to tell the concurrent mark to
3013 // start as we have some optional output below. We don't want the
3014 // output from the concurrent mark thread interfering with this
3015 // logging output either.
3016
3017 _hrm.verify_optional();
3018 _verifier->verify_region_sets_optional();
3019
3020 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3021 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3022
3023 print_heap_after_gc();
3024 print_heap_regions();
3025 trace_heap_after_gc(_gc_tracer_stw);
3026
3027 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3028 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3029 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3030 // before any GC notifications are raised.
3031 g1mm()->update_sizes();
3032
3033 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3034 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3035 _gc_timer_stw->register_gc_end();
3036 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3037 }
3038 // It should now be safe to tell the concurrent mark thread to start
3039 // without its logging output interfering with the logging output
3040 // that came from the pause.
3041
3042 if (should_start_conc_mark) {
3043 // CAUTION: after the doConcurrentMark() call below,
3044 // the concurrent marking thread(s) could be running
3045 // concurrently with us. Make sure that anything after
3046 // this point does not assume that we are the only GC thread
3047 // running. Note: of course, the actual marking work will
3048 // not start until the safepoint itself is released in
3049 // SuspendibleThreadSet::desynchronize().
3050 do_concurrent_mark();
3051 }
3052
3053 return true;
3054 }
3055
3056 void G1CollectedHeap::remove_self_forwarding_pointers() {
3057 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3058 workers()->run_task(&rsfp_task);
3059 }
3060
3061 void G1CollectedHeap::restore_after_evac_failure() {
3062 double remove_self_forwards_start = os::elapsedTime();
3063
3064 remove_self_forwarding_pointers();
3065 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3066 _preserved_marks_set.restore(&task_executor);
3067
3068 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3069 }
3070
3071 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3072 if (!_evacuation_failed) {
3073 _evacuation_failed = true;
3074 }
3075
3076 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3077 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3078 }
3079
3080 bool G1ParEvacuateFollowersClosure::offer_termination() {
3081 G1ParScanThreadState* const pss = par_scan_state();
3082 start_term_time();
3083 const bool res = terminator()->offer_termination();
3084 end_term_time();
3085 return res;
3086 }
3087
3088 void G1ParEvacuateFollowersClosure::do_void() {
3089 G1ParScanThreadState* const pss = par_scan_state();
3090 pss->trim_queue();
3091 do {
3092 pss->steal_and_trim_queue(queues());
3093 } while (!offer_termination());
3094 }
3095
3096 class G1ParTask : public AbstractGangTask {
3097 protected:
3098 G1CollectedHeap* _g1h;
3099 G1ParScanThreadStateSet* _pss;
3100 RefToScanQueueSet* _queues;
3101 G1RootProcessor* _root_processor;
3102 ParallelTaskTerminator _terminator;
3103 uint _n_workers;
3104
3105 public:
3106 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3107 : AbstractGangTask("G1 collection"),
3108 _g1h(g1h),
3109 _pss(per_thread_states),
3110 _queues(task_queues),
3111 _root_processor(root_processor),
3112 _terminator(n_workers, _queues),
3113 _n_workers(n_workers)
3114 {}
3115
3116 void work(uint worker_id) {
3117 if (worker_id >= _n_workers) return; // no work needed this round
3118
3119 double start_sec = os::elapsedTime();
3120 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3121
3122 {
3123 ResourceMark rm;
3124 HandleMark hm;
3125
3126 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3127
3128 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3129 pss->set_ref_processor(rp);
3130
3131 double start_strong_roots_sec = os::elapsedTime();
3132
3133 _root_processor->evacuate_roots(pss->closures(), worker_id);
3134
3135 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3136 // treating the nmethods visited to act as roots for concurrent marking.
3137 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3138 // objects copied by the current evacuation.
3139 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3140
3141 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3142
3143 double term_sec = 0.0;
3144 size_t evac_term_attempts = 0;
3145 {
3146 double start = os::elapsedTime();
3147 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3148 evac.do_void();
3149
3150 evac_term_attempts = evac.term_attempts();
3151 term_sec = evac.term_time();
3152 double elapsed_sec = os::elapsedTime() - start;
3153
3154 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3155 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3156 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3157 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3158 }
3159
3160 assert(pss->queue_is_empty(), "should be empty");
3161
3162 if (log_is_enabled(Debug, gc, task, stats)) {
3163 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3164 size_t lab_waste;
3165 size_t lab_undo_waste;
3166 pss->waste(lab_waste, lab_undo_waste);
3167 _g1h->print_termination_stats(worker_id,
3168 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3169 strong_roots_sec * 1000.0, /* strong roots time */
3170 term_sec * 1000.0, /* evac term time */
3171 evac_term_attempts, /* evac term attempts */
3172 lab_waste, /* alloc buffer waste */
3173 lab_undo_waste /* undo waste */
3174 );
3175 }
3176
3177 // Close the inner scope so that the ResourceMark and HandleMark
3178 // destructors are executed here and are included as part of the
3179 // "GC Worker Time".
3180 }
3181 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3182 }
3183 };
3184
3185 void G1CollectedHeap::print_termination_stats_hdr() {
3186 log_debug(gc, task, stats)("GC Termination Stats");
3187 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3188 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3189 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3190 }
3191
3192 void G1CollectedHeap::print_termination_stats(uint worker_id,
3193 double elapsed_ms,
3194 double strong_roots_ms,
3195 double term_ms,
3196 size_t term_attempts,
3197 size_t alloc_buffer_waste,
3198 size_t undo_waste) const {
3199 log_debug(gc, task, stats)
3200 ("%3d %9.2f %9.2f %6.2f "
3201 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3202 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3203 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3204 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3205 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3206 alloc_buffer_waste * HeapWordSize / K,
3207 undo_waste * HeapWordSize / K);
3208 }
3209
3210 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3211 private:
3212 BoolObjectClosure* _is_alive;
3213 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3214
3215 int _initial_string_table_size;
3216 int _initial_symbol_table_size;
3217
3218 bool _process_strings;
3219 int _strings_processed;
3220 int _strings_removed;
3221
3222 bool _process_symbols;
3223 int _symbols_processed;
3224 int _symbols_removed;
3225
3226 bool _process_string_dedup;
3227
3228 public:
3229 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3230 AbstractGangTask("String/Symbol Unlinking"),
3231 _is_alive(is_alive),
3232 _dedup_closure(is_alive, NULL, false),
3233 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3234 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3235 _process_string_dedup(process_string_dedup) {
3236
3237 _initial_string_table_size = StringTable::the_table()->table_size();
3238 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3239 if (process_strings) {
3240 StringTable::clear_parallel_claimed_index();
3241 }
3242 if (process_symbols) {
3243 SymbolTable::clear_parallel_claimed_index();
3244 }
3245 }
3246
3247 ~G1StringAndSymbolCleaningTask() {
3248 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3249 "claim value %d after unlink less than initial string table size %d",
3250 StringTable::parallel_claimed_index(), _initial_string_table_size);
3251 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3252 "claim value %d after unlink less than initial symbol table size %d",
3253 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3254
3255 log_info(gc, stringtable)(
3256 "Cleaned string and symbol table, "
3257 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3258 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3259 strings_processed(), strings_removed(),
3260 symbols_processed(), symbols_removed());
3261 }
3262
3263 void work(uint worker_id) {
3264 int strings_processed = 0;
3265 int strings_removed = 0;
3266 int symbols_processed = 0;
3267 int symbols_removed = 0;
3268 if (_process_strings) {
3269 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3270 Atomic::add(strings_processed, &_strings_processed);
3271 Atomic::add(strings_removed, &_strings_removed);
3272 }
3273 if (_process_symbols) {
3274 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3275 Atomic::add(symbols_processed, &_symbols_processed);
3276 Atomic::add(symbols_removed, &_symbols_removed);
3277 }
3278 if (_process_string_dedup) {
3279 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3280 }
3281 }
3282
3283 size_t strings_processed() const { return (size_t)_strings_processed; }
3284 size_t strings_removed() const { return (size_t)_strings_removed; }
3285
3286 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3287 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3288 };
3289
3290 class G1CodeCacheUnloadingTask {
3291 private:
3292 static Monitor* _lock;
3293
3294 BoolObjectClosure* const _is_alive;
3295 const bool _unloading_occurred;
3296 const uint _num_workers;
3297
3298 // Variables used to claim nmethods.
3299 CompiledMethod* _first_nmethod;
3300 CompiledMethod* volatile _claimed_nmethod;
3301
3302 // The list of nmethods that need to be processed by the second pass.
3303 CompiledMethod* volatile _postponed_list;
3304 volatile uint _num_entered_barrier;
3305
3306 public:
3307 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3308 _is_alive(is_alive),
3309 _unloading_occurred(unloading_occurred),
3310 _num_workers(num_workers),
3311 _first_nmethod(NULL),
3312 _claimed_nmethod(NULL),
3313 _postponed_list(NULL),
3314 _num_entered_barrier(0)
3315 {
3316 CompiledMethod::increase_unloading_clock();
3317 // Get first alive nmethod
3318 CompiledMethodIterator iter = CompiledMethodIterator();
3319 if(iter.next_alive()) {
3320 _first_nmethod = iter.method();
3321 }
3322 _claimed_nmethod = _first_nmethod;
3323 }
3324
3325 ~G1CodeCacheUnloadingTask() {
3326 CodeCache::verify_clean_inline_caches();
3327
3328 CodeCache::set_needs_cache_clean(false);
3329 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3330
3331 CodeCache::verify_icholder_relocations();
3332 }
3333
3334 private:
3335 void add_to_postponed_list(CompiledMethod* nm) {
3336 CompiledMethod* old;
3337 do {
3338 old = _postponed_list;
3339 nm->set_unloading_next(old);
3340 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3341 }
3342
3343 void clean_nmethod(CompiledMethod* nm) {
3344 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3345
3346 if (postponed) {
3347 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3348 add_to_postponed_list(nm);
3349 }
3350
3351 // Mark that this thread has been cleaned/unloaded.
3352 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3353 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3354 }
3355
3356 void clean_nmethod_postponed(CompiledMethod* nm) {
3357 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3358 }
3359
3360 static const int MaxClaimNmethods = 16;
3361
3362 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3363 CompiledMethod* first;
3364 CompiledMethodIterator last;
3365
3366 do {
3367 *num_claimed_nmethods = 0;
3368
3369 first = _claimed_nmethod;
3370 last = CompiledMethodIterator(first);
3371
3372 if (first != NULL) {
3373
3374 for (int i = 0; i < MaxClaimNmethods; i++) {
3375 if (!last.next_alive()) {
3376 break;
3377 }
3378 claimed_nmethods[i] = last.method();
3379 (*num_claimed_nmethods)++;
3380 }
3381 }
3382
3383 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3384 }
3385
3386 CompiledMethod* claim_postponed_nmethod() {
3387 CompiledMethod* claim;
3388 CompiledMethod* next;
3389
3390 do {
3391 claim = _postponed_list;
3392 if (claim == NULL) {
3393 return NULL;
3394 }
3395
3396 next = claim->unloading_next();
3397
3398 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3399
3400 return claim;
3401 }
3402
3403 public:
3404 // Mark that we're done with the first pass of nmethod cleaning.
3405 void barrier_mark(uint worker_id) {
3406 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3407 _num_entered_barrier++;
3408 if (_num_entered_barrier == _num_workers) {
3409 ml.notify_all();
3410 }
3411 }
3412
3413 // See if we have to wait for the other workers to
3414 // finish their first-pass nmethod cleaning work.
3415 void barrier_wait(uint worker_id) {
3416 if (_num_entered_barrier < _num_workers) {
3417 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3418 while (_num_entered_barrier < _num_workers) {
3419 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3420 }
3421 }
3422 }
3423
3424 // Cleaning and unloading of nmethods. Some work has to be postponed
3425 // to the second pass, when we know which nmethods survive.
3426 void work_first_pass(uint worker_id) {
3427 // The first nmethods is claimed by the first worker.
3428 if (worker_id == 0 && _first_nmethod != NULL) {
3429 clean_nmethod(_first_nmethod);
3430 _first_nmethod = NULL;
3431 }
3432
3433 int num_claimed_nmethods;
3434 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3435
3436 while (true) {
3437 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3438
3439 if (num_claimed_nmethods == 0) {
3440 break;
3441 }
3442
3443 for (int i = 0; i < num_claimed_nmethods; i++) {
3444 clean_nmethod(claimed_nmethods[i]);
3445 }
3446 }
3447 }
3448
3449 void work_second_pass(uint worker_id) {
3450 CompiledMethod* nm;
3451 // Take care of postponed nmethods.
3452 while ((nm = claim_postponed_nmethod()) != NULL) {
3453 clean_nmethod_postponed(nm);
3454 }
3455 }
3456 };
3457
3458 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3459
3460 class G1KlassCleaningTask : public StackObj {
3461 BoolObjectClosure* _is_alive;
3462 volatile int _clean_klass_tree_claimed;
3463 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3464
3465 public:
3466 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3467 _is_alive(is_alive),
3468 _clean_klass_tree_claimed(0),
3469 _klass_iterator() {
3470 }
3471
3472 private:
3473 bool claim_clean_klass_tree_task() {
3474 if (_clean_klass_tree_claimed) {
3475 return false;
3476 }
3477
3478 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3479 }
3480
3481 InstanceKlass* claim_next_klass() {
3482 Klass* klass;
3483 do {
3484 klass =_klass_iterator.next_klass();
3485 } while (klass != NULL && !klass->is_instance_klass());
3486
3487 // this can be null so don't call InstanceKlass::cast
3488 return static_cast<InstanceKlass*>(klass);
3489 }
3490
3491 public:
3492
3493 void clean_klass(InstanceKlass* ik) {
3494 ik->clean_weak_instanceklass_links(_is_alive);
3495 }
3496
3497 void work() {
3498 ResourceMark rm;
3499
3500 // One worker will clean the subklass/sibling klass tree.
3501 if (claim_clean_klass_tree_task()) {
3502 Klass::clean_subklass_tree(_is_alive);
3503 }
3504
3505 // All workers will help cleaning the classes,
3506 InstanceKlass* klass;
3507 while ((klass = claim_next_klass()) != NULL) {
3508 clean_klass(klass);
3509 }
3510 }
3511 };
3512
3513 class G1ResolvedMethodCleaningTask : public StackObj {
3514 BoolObjectClosure* _is_alive;
3515 volatile int _resolved_method_task_claimed;
3516 public:
3517 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3518 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3519
3520 bool claim_resolved_method_task() {
3521 if (_resolved_method_task_claimed) {
3522 return false;
3523 }
3524 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3525 }
3526
3527 // These aren't big, one thread can do it all.
3528 void work() {
3529 if (claim_resolved_method_task()) {
3530 ResolvedMethodTable::unlink(_is_alive);
3531 }
3532 }
3533 };
3534
3535
3536 // To minimize the remark pause times, the tasks below are done in parallel.
3537 class G1ParallelCleaningTask : public AbstractGangTask {
3538 private:
3539 G1StringAndSymbolCleaningTask _string_symbol_task;
3540 G1CodeCacheUnloadingTask _code_cache_task;
3541 G1KlassCleaningTask _klass_cleaning_task;
3542 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3543
3544 public:
3545 // The constructor is run in the VMThread.
3546 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3547 AbstractGangTask("Parallel Cleaning"),
3548 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3549 _code_cache_task(num_workers, is_alive, unloading_occurred),
3550 _klass_cleaning_task(is_alive),
3551 _resolved_method_cleaning_task(is_alive) {
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 _klass_cleaning_task.work();
3577 }
3578 };
3579
3580
3581 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3582 bool class_unloading_occurred) {
3583 uint n_workers = workers()->active_workers();
3584
3585 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3586 workers()->run_task(&g1_unlink_task);
3587 }
3588
3589 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3590 bool process_strings,
3591 bool process_symbols,
3592 bool process_string_dedup) {
3593 if (!process_strings && !process_symbols && !process_string_dedup) {
3594 // Nothing to clean.
3595 return;
3596 }
3597
3598 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3599 workers()->run_task(&g1_unlink_task);
3600
3601 }
3602
3603 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3604 private:
3605 DirtyCardQueueSet* _queue;
3606 G1CollectedHeap* _g1h;
3607 public:
3608 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3609 _queue(queue), _g1h(g1h) { }
3610
3611 virtual void work(uint worker_id) {
3612 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3613 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3614
3615 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3616 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3617
3618 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3619 }
3620 };
3621
3622 void G1CollectedHeap::redirty_logged_cards() {
3623 double redirty_logged_cards_start = os::elapsedTime();
3624
3625 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3626 dirty_card_queue_set().reset_for_par_iteration();
3627 workers()->run_task(&redirty_task);
3628
3629 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3630 dcq.merge_bufferlists(&dirty_card_queue_set());
3631 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3632
3633 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3634 }
3635
3636 // Weak Reference Processing support
3637
3638 // An always "is_alive" closure that is used to preserve referents.
3639 // If the object is non-null then it's alive. Used in the preservation
3640 // of referent objects that are pointed to by reference objects
3641 // discovered by the CM ref processor.
3642 class G1AlwaysAliveClosure: public BoolObjectClosure {
3643 public:
3644 bool do_object_b(oop p) {
3645 if (p != NULL) {
3646 return true;
3647 }
3648 return false;
3649 }
3650 };
3651
3652 bool G1STWIsAliveClosure::do_object_b(oop p) {
3653 // An object is reachable if it is outside the collection set,
3654 // or is inside and copied.
3655 return !_g1h->is_in_cset(p) || p->is_forwarded();
3656 }
3657
3658 // Non Copying Keep Alive closure
3659 class G1KeepAliveClosure: public OopClosure {
3660 G1CollectedHeap*_g1h;
3661 public:
3662 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3663 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3664 void do_oop(oop* p) {
3665 oop obj = *p;
3666 assert(obj != NULL, "the caller should have filtered out NULL values");
3667
3668 const InCSetState cset_state =_g1h->in_cset_state(obj);
3669 if (!cset_state.is_in_cset_or_humongous()) {
3670 return;
3671 }
3672 if (cset_state.is_in_cset()) {
3673 assert( obj->is_forwarded(), "invariant" );
3674 *p = obj->forwardee();
3675 } else {
3676 assert(!obj->is_forwarded(), "invariant" );
3677 assert(cset_state.is_humongous(),
3678 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3679 _g1h->set_humongous_is_live(obj);
3680 }
3681 }
3682 };
3683
3684 // Copying Keep Alive closure - can be called from both
3685 // serial and parallel code as long as different worker
3686 // threads utilize different G1ParScanThreadState instances
3687 // and different queues.
3688
3689 class G1CopyingKeepAliveClosure: public OopClosure {
3690 G1CollectedHeap* _g1h;
3691 OopClosure* _copy_non_heap_obj_cl;
3692 G1ParScanThreadState* _par_scan_state;
3693
3694 public:
3695 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3696 OopClosure* non_heap_obj_cl,
3697 G1ParScanThreadState* pss):
3698 _g1h(g1h),
3699 _copy_non_heap_obj_cl(non_heap_obj_cl),
3700 _par_scan_state(pss)
3701 {}
3702
3703 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3704 virtual void do_oop( oop* p) { do_oop_work(p); }
3705
3706 template <class T> void do_oop_work(T* p) {
3707 oop obj = RawAccess<>::oop_load(p);
3708
3709 if (_g1h->is_in_cset_or_humongous(obj)) {
3710 // If the referent object has been forwarded (either copied
3711 // to a new location or to itself in the event of an
3712 // evacuation failure) then we need to update the reference
3713 // field and, if both reference and referent are in the G1
3714 // heap, update the RSet for the referent.
3715 //
3716 // If the referent has not been forwarded then we have to keep
3717 // it alive by policy. Therefore we have copy the referent.
3718 //
3719 // If the reference field is in the G1 heap then we can push
3720 // on the PSS queue. When the queue is drained (after each
3721 // phase of reference processing) the object and it's followers
3722 // will be copied, the reference field set to point to the
3723 // new location, and the RSet updated. Otherwise we need to
3724 // use the the non-heap or metadata closures directly to copy
3725 // the referent object and update the pointer, while avoiding
3726 // updating the RSet.
3727
3728 if (_g1h->is_in_g1_reserved(p)) {
3729 _par_scan_state->push_on_queue(p);
3730 } else {
3731 assert(!Metaspace::contains((const void*)p),
3732 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3733 _copy_non_heap_obj_cl->do_oop(p);
3734 }
3735 }
3736 }
3737 };
3738
3739 // Serial drain queue closure. Called as the 'complete_gc'
3740 // closure for each discovered list in some of the
3741 // reference processing phases.
3742
3743 class G1STWDrainQueueClosure: public VoidClosure {
3744 protected:
3745 G1CollectedHeap* _g1h;
3746 G1ParScanThreadState* _par_scan_state;
3747
3748 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3749
3750 public:
3751 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3752 _g1h(g1h),
3753 _par_scan_state(pss)
3754 { }
3755
3756 void do_void() {
3757 G1ParScanThreadState* const pss = par_scan_state();
3758 pss->trim_queue();
3759 }
3760 };
3761
3762 // Parallel Reference Processing closures
3763
3764 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3765 // processing during G1 evacuation pauses.
3766
3767 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3768 private:
3769 G1CollectedHeap* _g1h;
3770 G1ParScanThreadStateSet* _pss;
3771 RefToScanQueueSet* _queues;
3772 WorkGang* _workers;
3773 uint _active_workers;
3774
3775 public:
3776 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3777 G1ParScanThreadStateSet* per_thread_states,
3778 WorkGang* workers,
3779 RefToScanQueueSet *task_queues,
3780 uint n_workers) :
3781 _g1h(g1h),
3782 _pss(per_thread_states),
3783 _queues(task_queues),
3784 _workers(workers),
3785 _active_workers(n_workers)
3786 {
3787 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3788 }
3789
3790 // Executes the given task using concurrent marking worker threads.
3791 virtual void execute(ProcessTask& task);
3792 virtual void execute(EnqueueTask& task);
3793 };
3794
3795 // Gang task for possibly parallel reference processing
3796
3797 class G1STWRefProcTaskProxy: public AbstractGangTask {
3798 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3799 ProcessTask& _proc_task;
3800 G1CollectedHeap* _g1h;
3801 G1ParScanThreadStateSet* _pss;
3802 RefToScanQueueSet* _task_queues;
3803 ParallelTaskTerminator* _terminator;
3804
3805 public:
3806 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3807 G1CollectedHeap* g1h,
3808 G1ParScanThreadStateSet* per_thread_states,
3809 RefToScanQueueSet *task_queues,
3810 ParallelTaskTerminator* terminator) :
3811 AbstractGangTask("Process reference objects in parallel"),
3812 _proc_task(proc_task),
3813 _g1h(g1h),
3814 _pss(per_thread_states),
3815 _task_queues(task_queues),
3816 _terminator(terminator)
3817 {}
3818
3819 virtual void work(uint worker_id) {
3820 // The reference processing task executed by a single worker.
3821 ResourceMark rm;
3822 HandleMark hm;
3823
3824 G1STWIsAliveClosure is_alive(_g1h);
3825
3826 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3827 pss->set_ref_processor(NULL);
3828
3829 // Keep alive closure.
3830 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3831
3832 // Complete GC closure
3833 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3834
3835 // Call the reference processing task's work routine.
3836 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3837
3838 // Note we cannot assert that the refs array is empty here as not all
3839 // of the processing tasks (specifically phase2 - pp2_work) execute
3840 // the complete_gc closure (which ordinarily would drain the queue) so
3841 // the queue may not be empty.
3842 }
3843 };
3844
3845 // Driver routine for parallel reference processing.
3846 // Creates an instance of the ref processing gang
3847 // task and has the worker threads execute it.
3848 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3849 assert(_workers != NULL, "Need parallel worker threads.");
3850
3851 ParallelTaskTerminator terminator(_active_workers, _queues);
3852 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3853
3854 _workers->run_task(&proc_task_proxy);
3855 }
3856
3857 // Gang task for parallel reference enqueueing.
3858
3859 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3860 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3861 EnqueueTask& _enq_task;
3862
3863 public:
3864 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3865 AbstractGangTask("Enqueue reference objects in parallel"),
3866 _enq_task(enq_task)
3867 { }
3868
3869 virtual void work(uint worker_id) {
3870 _enq_task.work(worker_id);
3871 }
3872 };
3873
3874 // Driver routine for parallel reference enqueueing.
3875 // Creates an instance of the ref enqueueing gang
3876 // task and has the worker threads execute it.
3877
3878 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
3879 assert(_workers != NULL, "Need parallel worker threads.");
3880
3881 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
3882
3883 _workers->run_task(&enq_task_proxy);
3884 }
3885
3886 // End of weak reference support closures
3887
3888 // Abstract task used to preserve (i.e. copy) any referent objects
3889 // that are in the collection set and are pointed to by reference
3890 // objects discovered by the CM ref processor.
3891
3892 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
3893 protected:
3894 G1CollectedHeap* _g1h;
3895 G1ParScanThreadStateSet* _pss;
3896 RefToScanQueueSet* _queues;
3897 ParallelTaskTerminator _terminator;
3898 uint _n_workers;
3899
3900 public:
3901 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
3902 AbstractGangTask("ParPreserveCMReferents"),
3903 _g1h(g1h),
3904 _pss(per_thread_states),
3905 _queues(task_queues),
3906 _terminator(workers, _queues),
3907 _n_workers(workers)
3908 {
3909 g1h->ref_processor_cm()->set_active_mt_degree(workers);
3910 }
3911
3912 void work(uint worker_id) {
3913 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
3914
3915 ResourceMark rm;
3916 HandleMark hm;
3917
3918 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3919 pss->set_ref_processor(NULL);
3920 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3921
3922 // Is alive closure
3923 G1AlwaysAliveClosure always_alive;
3924
3925 // Copying keep alive closure. Applied to referent objects that need
3926 // to be copied.
3927 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3928
3929 ReferenceProcessor* rp = _g1h->ref_processor_cm();
3930
3931 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
3932 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
3933
3934 // limit is set using max_num_q() - which was set using ParallelGCThreads.
3935 // So this must be true - but assert just in case someone decides to
3936 // change the worker ids.
3937 assert(worker_id < limit, "sanity");
3938 assert(!rp->discovery_is_atomic(), "check this code");
3939
3940 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
3941 for (uint idx = worker_id; idx < limit; idx += stride) {
3942 DiscoveredList& ref_list = rp->discovered_refs()[idx];
3943
3944 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
3945 while (iter.has_next()) {
3946 // Since discovery is not atomic for the CM ref processor, we
3947 // can see some null referent objects.
3948 iter.load_ptrs(DEBUG_ONLY(true));
3949 oop ref = iter.obj();
3950
3951 // This will filter nulls.
3952 if (iter.is_referent_alive()) {
3953 iter.make_referent_alive();
3954 }
3955 iter.move_to_next();
3956 }
3957 }
3958
3959 // Drain the queue - which may cause stealing
3960 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
3961 drain_queue.do_void();
3962 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
3963 assert(pss->queue_is_empty(), "should be");
3964 }
3965 };
3966
3967 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
3968 // Any reference objects, in the collection set, that were 'discovered'
3969 // by the CM ref processor should have already been copied (either by
3970 // applying the external root copy closure to the discovered lists, or
3971 // by following an RSet entry).
3972 //
3973 // But some of the referents, that are in the collection set, that these
3974 // reference objects point to may not have been copied: the STW ref
3975 // processor would have seen that the reference object had already
3976 // been 'discovered' and would have skipped discovering the reference,
3977 // but would not have treated the reference object as a regular oop.
3978 // As a result the copy closure would not have been applied to the
3979 // referent object.
3980 //
3981 // We need to explicitly copy these referent objects - the references
3982 // will be processed at the end of remarking.
3983 //
3984 // We also need to do this copying before we process the reference
3985 // objects discovered by the STW ref processor in case one of these
3986 // referents points to another object which is also referenced by an
3987 // object discovered by the STW ref processor.
3988 double preserve_cm_referents_time = 0.0;
3989
3990 // To avoid spawning task when there is no work to do, check that
3991 // a concurrent cycle is active and that some references have been
3992 // discovered.
3993 if (concurrent_mark()->cm_thread()->during_cycle() &&
3994 ref_processor_cm()->has_discovered_references()) {
3995 double preserve_cm_referents_start = os::elapsedTime();
3996 uint no_of_gc_workers = workers()->active_workers();
3997 G1ParPreserveCMReferentsTask keep_cm_referents(this,
3998 per_thread_states,
3999 no_of_gc_workers,
4000 _task_queues);
4001 workers()->run_task(&keep_cm_referents);
4002 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4003 }
4004
4005 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4006 }
4007
4008 // Weak Reference processing during an evacuation pause (part 1).
4009 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4010 double ref_proc_start = os::elapsedTime();
4011
4012 ReferenceProcessor* rp = _ref_processor_stw;
4013 assert(rp->discovery_enabled(), "should have been enabled");
4014
4015 // Closure to test whether a referent is alive.
4016 G1STWIsAliveClosure is_alive(this);
4017
4018 // Even when parallel reference processing is enabled, the processing
4019 // of JNI refs is serial and performed serially by the current thread
4020 // rather than by a worker. The following PSS will be used for processing
4021 // JNI refs.
4022
4023 // Use only a single queue for this PSS.
4024 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4025 pss->set_ref_processor(NULL);
4026 assert(pss->queue_is_empty(), "pre-condition");
4027
4028 // Keep alive closure.
4029 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4030
4031 // Serial Complete GC closure
4032 G1STWDrainQueueClosure drain_queue(this, pss);
4033
4034 // Setup the soft refs policy...
4035 rp->setup_policy(false);
4036
4037 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4038
4039 ReferenceProcessorStats stats;
4040 if (!rp->processing_is_mt()) {
4041 // Serial reference processing...
4042 stats = rp->process_discovered_references(&is_alive,
4043 &keep_alive,
4044 &drain_queue,
4045 NULL,
4046 pt);
4047 } else {
4048 uint no_of_gc_workers = workers()->active_workers();
4049
4050 // Parallel reference processing
4051 assert(no_of_gc_workers <= rp->max_num_q(),
4052 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4053 no_of_gc_workers, rp->max_num_q());
4054
4055 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4056 stats = rp->process_discovered_references(&is_alive,
4057 &keep_alive,
4058 &drain_queue,
4059 &par_task_executor,
4060 pt);
4061 }
4062
4063 _gc_tracer_stw->report_gc_reference_stats(stats);
4064
4065 // We have completed copying any necessary live referent objects.
4066 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4067
4068 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4069 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4070 }
4071
4072 // Weak Reference processing during an evacuation pause (part 2).
4073 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4074 double ref_enq_start = os::elapsedTime();
4075
4076 ReferenceProcessor* rp = _ref_processor_stw;
4077 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4078
4079 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4080
4081 // Now enqueue any remaining on the discovered lists on to
4082 // the pending list.
4083 if (!rp->processing_is_mt()) {
4084 // Serial reference processing...
4085 rp->enqueue_discovered_references(NULL, pt);
4086 } else {
4087 // Parallel reference enqueueing
4088
4089 uint n_workers = workers()->active_workers();
4090
4091 assert(n_workers <= rp->max_num_q(),
4092 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4093 n_workers, rp->max_num_q());
4094
4095 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4096 rp->enqueue_discovered_references(&par_task_executor, pt);
4097 }
4098
4099 rp->verify_no_references_recorded();
4100 assert(!rp->discovery_enabled(), "should have been disabled");
4101
4102 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4103 // ensure that it is marked in the bitmap for concurrent marking to discover.
4104 if (collector_state()->in_initial_mark_gc()) {
4105 oop pll_head = Universe::reference_pending_list();
4106 if (pll_head != NULL) {
4107 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
4108 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
4109 }
4110 }
4111
4112 // FIXME
4113 // CM's reference processing also cleans up the string and symbol tables.
4114 // Should we do that here also? We could, but it is a serial operation
4115 // and could significantly increase the pause time.
4116
4117 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4118 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4119 }
4120
4121 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4122 double merge_pss_time_start = os::elapsedTime();
4123 per_thread_states->flush();
4124 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4125 }
4126
4127 void G1CollectedHeap::pre_evacuate_collection_set() {
4128 _expand_heap_after_alloc_failure = true;
4129 _evacuation_failed = false;
4130
4131 // Disable the hot card cache.
4132 _hot_card_cache->reset_hot_cache_claimed_index();
4133 _hot_card_cache->set_use_cache(false);
4134
4135 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4136 _preserved_marks_set.assert_empty();
4137
4138 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4139
4140 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4141 if (collector_state()->in_initial_mark_gc()) {
4142 double start_clear_claimed_marks = os::elapsedTime();
4143
4144 ClassLoaderDataGraph::clear_claimed_marks();
4145
4146 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4147 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4148 }
4149 }
4150
4151 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
4152 // Should G1EvacuationFailureALot be in effect for this GC?
4153 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4154
4155 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4156
4157 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4158
4159 double start_par_time_sec = os::elapsedTime();
4160 double end_par_time_sec;
4161
4162 {
4163 const uint n_workers = workers()->active_workers();
4164 G1RootProcessor root_processor(this, n_workers);
4165 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4166
4167 print_termination_stats_hdr();
4168
4169 workers()->run_task(&g1_par_task);
4170 end_par_time_sec = os::elapsedTime();
4171
4172 // Closing the inner scope will execute the destructor
4173 // for the G1RootProcessor object. We record the current
4174 // elapsed time before closing the scope so that time
4175 // taken for the destructor is NOT included in the
4176 // reported parallel time.
4177 }
4178
4179 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4180 phase_times->record_par_time(par_time_ms);
4181
4182 double code_root_fixup_time_ms =
4183 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4184 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4185 }
4186
4187 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4188 // Process any discovered reference objects - we have
4189 // to do this _before_ we retire the GC alloc regions
4190 // as we may have to copy some 'reachable' referent
4191 // objects (and their reachable sub-graphs) that were
4192 // not copied during the pause.
4193 if (g1_policy()->should_process_references()) {
4194 preserve_cm_referents(per_thread_states);
4195 process_discovered_references(per_thread_states);
4196 } else {
4197 ref_processor_stw()->verify_no_references_recorded();
4198 }
4199
4200 G1STWIsAliveClosure is_alive(this);
4201 G1KeepAliveClosure keep_alive(this);
4202
4203 {
4204 double start = os::elapsedTime();
4205
4206 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4207
4208 double time_ms = (os::elapsedTime() - start) * 1000.0;
4209 g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4210 }
4211
4212 if (G1StringDedup::is_enabled()) {
4213 double fixup_start = os::elapsedTime();
4214
4215 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4216
4217 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4218 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4219 }
4220
4221 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4222
4223 if (evacuation_failed()) {
4224 restore_after_evac_failure();
4225
4226 // Reset the G1EvacuationFailureALot counters and flags
4227 // Note: the values are reset only when an actual
4228 // evacuation failure occurs.
4229 NOT_PRODUCT(reset_evacuation_should_fail();)
4230 }
4231
4232 _preserved_marks_set.assert_empty();
4233
4234 // Enqueue any remaining references remaining on the STW
4235 // reference processor's discovered lists. We need to do
4236 // this after the card table is cleaned (and verified) as
4237 // the act of enqueueing entries on to the pending list
4238 // will log these updates (and dirty their associated
4239 // cards). We need these updates logged to update any
4240 // RSets.
4241 if (g1_policy()->should_process_references()) {
4242 enqueue_discovered_references(per_thread_states);
4243 } else {
4244 g1_policy()->phase_times()->record_ref_enq_time(0);
4245 }
4246
4247 _allocator->release_gc_alloc_regions(evacuation_info);
4248
4249 merge_per_thread_state_info(per_thread_states);
4250
4251 // Reset and re-enable the hot card cache.
4252 // Note the counts for the cards in the regions in the
4253 // collection set are reset when the collection set is freed.
4254 _hot_card_cache->reset_hot_cache();
4255 _hot_card_cache->set_use_cache(true);
4256
4257 purge_code_root_memory();
4258
4259 redirty_logged_cards();
4260 #if COMPILER2_OR_JVMCI
4261 double start = os::elapsedTime();
4262 DerivedPointerTable::update_pointers();
4263 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4264 #endif
4265 g1_policy()->print_age_table();
4266 }
4267
4268 void G1CollectedHeap::record_obj_copy_mem_stats() {
4269 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4270
4271 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4272 create_g1_evac_summary(&_old_evac_stats));
4273 }
4274
4275 void G1CollectedHeap::free_region(HeapRegion* hr,
4276 FreeRegionList* free_list,
4277 bool skip_remset,
4278 bool skip_hot_card_cache,
4279 bool locked) {
4280 assert(!hr->is_free(), "the region should not be free");
4281 assert(!hr->is_empty(), "the region should not be empty");
4282 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4283 assert(free_list != NULL, "pre-condition");
4284
4285 if (G1VerifyBitmaps) {
4286 MemRegion mr(hr->bottom(), hr->end());
4287 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4288 }
4289
4290 // Clear the card counts for this region.
4291 // Note: we only need to do this if the region is not young
4292 // (since we don't refine cards in young regions).
4293 if (!skip_hot_card_cache && !hr->is_young()) {
4294 _hot_card_cache->reset_card_counts(hr);
4295 }
4296 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4297 _g1_policy->remset_tracker()->update_at_free(hr);
4298 free_list->add_ordered(hr);
4299 }
4300
4301 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4302 FreeRegionList* free_list) {
4303 assert(hr->is_humongous(), "this is only for humongous regions");
4304 assert(free_list != NULL, "pre-condition");
4305 hr->clear_humongous();
4306 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4307 }
4308
4309 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4310 const uint humongous_regions_removed) {
4311 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4312 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4313 _old_set.bulk_remove(old_regions_removed);
4314 _humongous_set.bulk_remove(humongous_regions_removed);
4315 }
4316
4317 }
4318
4319 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4320 assert(list != NULL, "list can't be null");
4321 if (!list->is_empty()) {
4322 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4323 _hrm.insert_list_into_free_list(list);
4324 }
4325 }
4326
4327 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4328 decrease_used(bytes);
4329 }
4330
4331 class G1FreeCollectionSetTask : public AbstractGangTask {
4332 private:
4333
4334 // Closure applied to all regions in the collection set to do work that needs to
4335 // be done serially in a single thread.
4336 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4337 private:
4338 EvacuationInfo* _evacuation_info;
4339 const size_t* _surviving_young_words;
4340
4341 // Bytes used in successfully evacuated regions before the evacuation.
4342 size_t _before_used_bytes;
4343 // Bytes used in unsucessfully evacuated regions before the evacuation
4344 size_t _after_used_bytes;
4345
4346 size_t _bytes_allocated_in_old_since_last_gc;
4347
4348 size_t _failure_used_words;
4349 size_t _failure_waste_words;
4350
4351 FreeRegionList _local_free_list;
4352 public:
4353 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4354 HeapRegionClosure(),
4355 _evacuation_info(evacuation_info),
4356 _surviving_young_words(surviving_young_words),
4357 _before_used_bytes(0),
4358 _after_used_bytes(0),
4359 _bytes_allocated_in_old_since_last_gc(0),
4360 _failure_used_words(0),
4361 _failure_waste_words(0),
4362 _local_free_list("Local Region List for CSet Freeing") {
4363 }
4364
4365 virtual bool do_heap_region(HeapRegion* r) {
4366 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4367
4368 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4369 g1h->clear_in_cset(r);
4370
4371 if (r->is_young()) {
4372 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4373 "Young index %d is wrong for region %u of type %s with %u young regions",
4374 r->young_index_in_cset(),
4375 r->hrm_index(),
4376 r->get_type_str(),
4377 g1h->collection_set()->young_region_length());
4378 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4379 r->record_surv_words_in_group(words_survived);
4380 }
4381
4382 if (!r->evacuation_failed()) {
4383 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4384 _before_used_bytes += r->used();
4385 g1h->free_region(r,
4386 &_local_free_list,
4387 true, /* skip_remset */
4388 true, /* skip_hot_card_cache */
4389 true /* locked */);
4390 } else {
4391 r->uninstall_surv_rate_group();
4392 r->set_young_index_in_cset(-1);
4393 r->set_evacuation_failed(false);
4394 // When moving a young gen region to old gen, we "allocate" that whole region
4395 // there. This is in addition to any already evacuated objects. Notify the
4396 // policy about that.
4397 // Old gen regions do not cause an additional allocation: both the objects
4398 // still in the region and the ones already moved are accounted for elsewhere.
4399 if (r->is_young()) {
4400 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4401 }
4402 // The region is now considered to be old.
4403 r->set_old();
4404 // Do some allocation statistics accounting. Regions that failed evacuation
4405 // are always made old, so there is no need to update anything in the young
4406 // gen statistics, but we need to update old gen statistics.
4407 size_t used_words = r->marked_bytes() / HeapWordSize;
4408
4409 _failure_used_words += used_words;
4410 _failure_waste_words += HeapRegion::GrainWords - used_words;
4411
4412 g1h->old_set_add(r);
4413 _after_used_bytes += r->used();
4414 }
4415 return false;
4416 }
4417
4418 void complete_work() {
4419 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4420
4421 _evacuation_info->set_regions_freed(_local_free_list.length());
4422 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4423
4424 g1h->prepend_to_freelist(&_local_free_list);
4425 g1h->decrement_summary_bytes(_before_used_bytes);
4426
4427 G1Policy* policy = g1h->g1_policy();
4428 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4429
4430 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4431 }
4432 };
4433
4434 G1CollectionSet* _collection_set;
4435 G1SerialFreeCollectionSetClosure _cl;
4436 const size_t* _surviving_young_words;
4437
4438 size_t _rs_lengths;
4439
4440 volatile jint _serial_work_claim;
4441
4442 struct WorkItem {
4443 uint region_idx;
4444 bool is_young;
4445 bool evacuation_failed;
4446
4447 WorkItem(HeapRegion* r) {
4448 region_idx = r->hrm_index();
4449 is_young = r->is_young();
4450 evacuation_failed = r->evacuation_failed();
4451 }
4452 };
4453
4454 volatile size_t _parallel_work_claim;
4455 size_t _num_work_items;
4456 WorkItem* _work_items;
4457
4458 void do_serial_work() {
4459 // Need to grab the lock to be allowed to modify the old region list.
4460 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4461 _collection_set->iterate(&_cl);
4462 }
4463
4464 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4465 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4466
4467 HeapRegion* r = g1h->region_at(region_idx);
4468 assert(!g1h->is_on_master_free_list(r), "sanity");
4469
4470 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4471
4472 if (!is_young) {
4473 g1h->_hot_card_cache->reset_card_counts(r);
4474 }
4475
4476 if (!evacuation_failed) {
4477 r->rem_set()->clear_locked();
4478 }
4479 }
4480
4481 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4482 private:
4483 size_t _cur_idx;
4484 WorkItem* _work_items;
4485 public:
4486 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4487
4488 virtual bool do_heap_region(HeapRegion* r) {
4489 _work_items[_cur_idx++] = WorkItem(r);
4490 return false;
4491 }
4492 };
4493
4494 void prepare_work() {
4495 G1PrepareFreeCollectionSetClosure cl(_work_items);
4496 _collection_set->iterate(&cl);
4497 }
4498
4499 void complete_work() {
4500 _cl.complete_work();
4501
4502 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4503 policy->record_max_rs_lengths(_rs_lengths);
4504 policy->cset_regions_freed();
4505 }
4506 public:
4507 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4508 AbstractGangTask("G1 Free Collection Set"),
4509 _cl(evacuation_info, surviving_young_words),
4510 _collection_set(collection_set),
4511 _surviving_young_words(surviving_young_words),
4512 _serial_work_claim(0),
4513 _rs_lengths(0),
4514 _parallel_work_claim(0),
4515 _num_work_items(collection_set->region_length()),
4516 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4517 prepare_work();
4518 }
4519
4520 ~G1FreeCollectionSetTask() {
4521 complete_work();
4522 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4523 }
4524
4525 // Chunk size for work distribution. The chosen value has been determined experimentally
4526 // to be a good tradeoff between overhead and achievable parallelism.
4527 static uint chunk_size() { return 32; }
4528
4529 virtual void work(uint worker_id) {
4530 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4531
4532 // Claim serial work.
4533 if (_serial_work_claim == 0) {
4534 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4535 if (value == 0) {
4536 double serial_time = os::elapsedTime();
4537 do_serial_work();
4538 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4539 }
4540 }
4541
4542 // Start parallel work.
4543 double young_time = 0.0;
4544 bool has_young_time = false;
4545 double non_young_time = 0.0;
4546 bool has_non_young_time = false;
4547
4548 while (true) {
4549 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4550 size_t cur = end - chunk_size();
4551
4552 if (cur >= _num_work_items) {
4553 break;
4554 }
4555
4556 double start_time = os::elapsedTime();
4557
4558 end = MIN2(end, _num_work_items);
4559
4560 for (; cur < end; cur++) {
4561 bool is_young = _work_items[cur].is_young;
4562
4563 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4564
4565 double end_time = os::elapsedTime();
4566 double time_taken = end_time - start_time;
4567 if (is_young) {
4568 young_time += time_taken;
4569 has_young_time = true;
4570 } else {
4571 non_young_time += time_taken;
4572 has_non_young_time = true;
4573 }
4574 start_time = end_time;
4575 }
4576 }
4577
4578 if (has_young_time) {
4579 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4580 }
4581 if (has_non_young_time) {
4582 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4583 }
4584 }
4585 };
4586
4587 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4588 _eden.clear();
4589
4590 double free_cset_start_time = os::elapsedTime();
4591
4592 {
4593 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4594 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4595
4596 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4597
4598 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4599 cl.name(),
4600 num_workers,
4601 _collection_set.region_length());
4602 workers()->run_task(&cl, num_workers);
4603 }
4604 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4605
4606 collection_set->clear();
4607 }
4608
4609 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4610 private:
4611 FreeRegionList* _free_region_list;
4612 HeapRegionSet* _proxy_set;
4613 uint _humongous_objects_reclaimed;
4614 uint _humongous_regions_reclaimed;
4615 size_t _freed_bytes;
4616 public:
4617
4618 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4619 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4620 }
4621
4622 virtual bool do_heap_region(HeapRegion* r) {
4623 if (!r->is_starts_humongous()) {
4624 return false;
4625 }
4626
4627 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4628
4629 oop obj = (oop)r->bottom();
4630 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4631
4632 // The following checks whether the humongous object is live are sufficient.
4633 // The main additional check (in addition to having a reference from the roots
4634 // or the young gen) is whether the humongous object has a remembered set entry.
4635 //
4636 // A humongous object cannot be live if there is no remembered set for it
4637 // because:
4638 // - there can be no references from within humongous starts regions referencing
4639 // the object because we never allocate other objects into them.
4640 // (I.e. there are no intra-region references that may be missed by the
4641 // remembered set)
4642 // - as soon there is a remembered set entry to the humongous starts region
4643 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4644 // until the end of a concurrent mark.
4645 //
4646 // It is not required to check whether the object has been found dead by marking
4647 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4648 // all objects allocated during that time are considered live.
4649 // SATB marking is even more conservative than the remembered set.
4650 // So if at this point in the collection there is no remembered set entry,
4651 // nobody has a reference to it.
4652 // At the start of collection we flush all refinement logs, and remembered sets
4653 // are completely up-to-date wrt to references to the humongous object.
4654 //
4655 // Other implementation considerations:
4656 // - never consider object arrays at this time because they would pose
4657 // considerable effort for cleaning up the the remembered sets. This is
4658 // required because stale remembered sets might reference locations that
4659 // are currently allocated into.
4660 uint region_idx = r->hrm_index();
4661 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4662 !r->rem_set()->is_empty()) {
4663 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",
4664 region_idx,
4665 (size_t)obj->size() * HeapWordSize,
4666 p2i(r->bottom()),
4667 r->rem_set()->occupied(),
4668 r->rem_set()->strong_code_roots_list_length(),
4669 next_bitmap->is_marked(r->bottom()),
4670 g1h->is_humongous_reclaim_candidate(region_idx),
4671 obj->is_typeArray()
4672 );
4673 return false;
4674 }
4675
4676 guarantee(obj->is_typeArray(),
4677 "Only eagerly reclaiming type arrays is supported, but the object "
4678 PTR_FORMAT " is not.", p2i(r->bottom()));
4679
4680 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",
4681 region_idx,
4682 (size_t)obj->size() * HeapWordSize,
4683 p2i(r->bottom()),
4684 r->rem_set()->occupied(),
4685 r->rem_set()->strong_code_roots_list_length(),
4686 next_bitmap->is_marked(r->bottom()),
4687 g1h->is_humongous_reclaim_candidate(region_idx),
4688 obj->is_typeArray()
4689 );
4690
4691 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4692 cm->humongous_object_eagerly_reclaimed(r);
4693 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4694 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4695 region_idx,
4696 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4697 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4698 _humongous_objects_reclaimed++;
4699 do {
4700 HeapRegion* next = g1h->next_region_in_humongous(r);
4701 _freed_bytes += r->used();
4702 r->set_containing_set(NULL);
4703 _humongous_regions_reclaimed++;
4704 g1h->free_humongous_region(r, _free_region_list);
4705 r = next;
4706 } while (r != NULL);
4707
4708 return false;
4709 }
4710
4711 uint humongous_objects_reclaimed() {
4712 return _humongous_objects_reclaimed;
4713 }
4714
4715 uint humongous_regions_reclaimed() {
4716 return _humongous_regions_reclaimed;
4717 }
4718
4719 size_t bytes_freed() const {
4720 return _freed_bytes;
4721 }
4722 };
4723
4724 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4725 assert_at_safepoint_on_vm_thread();
4726
4727 if (!G1EagerReclaimHumongousObjects ||
4728 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4729 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4730 return;
4731 }
4732
4733 double start_time = os::elapsedTime();
4734
4735 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4736
4737 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4738 heap_region_iterate(&cl);
4739
4740 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4741
4742 G1HRPrinter* hrp = hr_printer();
4743 if (hrp->is_active()) {
4744 FreeRegionListIterator iter(&local_cleanup_list);
4745 while (iter.more_available()) {
4746 HeapRegion* hr = iter.get_next();
4747 hrp->cleanup(hr);
4748 }
4749 }
4750
4751 prepend_to_freelist(&local_cleanup_list);
4752 decrement_summary_bytes(cl.bytes_freed());
4753
4754 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4755 cl.humongous_objects_reclaimed());
4756 }
4757
4758 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4759 public:
4760 virtual bool do_heap_region(HeapRegion* r) {
4761 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4762 G1CollectedHeap::heap()->clear_in_cset(r);
4763 r->set_young_index_in_cset(-1);
4764 return false;
4765 }
4766 };
4767
4768 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4769 G1AbandonCollectionSetClosure cl;
4770 collection_set->iterate(&cl);
4771
4772 collection_set->clear();
4773 collection_set->stop_incremental_building();
4774 }
4775
4776 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4777 return _allocator->is_retained_old_region(hr);
4778 }
4779
4780 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4781 _eden.add(hr);
4782 _g1_policy->set_region_eden(hr);
4783 }
4784
4785 #ifdef ASSERT
4786
4787 class NoYoungRegionsClosure: public HeapRegionClosure {
4788 private:
4789 bool _success;
4790 public:
4791 NoYoungRegionsClosure() : _success(true) { }
4792 bool do_heap_region(HeapRegion* r) {
4793 if (r->is_young()) {
4794 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4795 p2i(r->bottom()), p2i(r->end()));
4796 _success = false;
4797 }
4798 return false;
4799 }
4800 bool success() { return _success; }
4801 };
4802
4803 bool G1CollectedHeap::check_young_list_empty() {
4804 bool ret = (young_regions_count() == 0);
4805
4806 NoYoungRegionsClosure closure;
4807 heap_region_iterate(&closure);
4808 ret = ret && closure.success();
4809
4810 return ret;
4811 }
4812
4813 #endif // ASSERT
4814
4815 class TearDownRegionSetsClosure : public HeapRegionClosure {
4816 private:
4817 HeapRegionSet *_old_set;
4818
4819 public:
4820 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4821
4822 bool do_heap_region(HeapRegion* r) {
4823 if (r->is_old()) {
4824 _old_set->remove(r);
4825 } else if(r->is_young()) {
4826 r->uninstall_surv_rate_group();
4827 } else {
4828 // We ignore free regions, we'll empty the free list afterwards.
4829 // We ignore humongous regions, we're not tearing down the
4830 // humongous regions set.
4831 assert(r->is_free() || r->is_humongous(),
4832 "it cannot be another type");
4833 }
4834 return false;
4835 }
4836
4837 ~TearDownRegionSetsClosure() {
4838 assert(_old_set->is_empty(), "post-condition");
4839 }
4840 };
4841
4842 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4843 assert_at_safepoint_on_vm_thread();
4844
4845 if (!free_list_only) {
4846 TearDownRegionSetsClosure cl(&_old_set);
4847 heap_region_iterate(&cl);
4848
4849 // Note that emptying the _young_list is postponed and instead done as
4850 // the first step when rebuilding the regions sets again. The reason for
4851 // this is that during a full GC string deduplication needs to know if
4852 // a collected region was young or old when the full GC was initiated.
4853 }
4854 _hrm.remove_all_free_regions();
4855 }
4856
4857 void G1CollectedHeap::increase_used(size_t bytes) {
4858 _summary_bytes_used += bytes;
4859 }
4860
4861 void G1CollectedHeap::decrease_used(size_t bytes) {
4862 assert(_summary_bytes_used >= bytes,
4863 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4864 _summary_bytes_used, bytes);
4865 _summary_bytes_used -= bytes;
4866 }
4867
4868 void G1CollectedHeap::set_used(size_t bytes) {
4869 _summary_bytes_used = bytes;
4870 }
4871
4872 class RebuildRegionSetsClosure : public HeapRegionClosure {
4873 private:
4874 bool _free_list_only;
4875 HeapRegionSet* _old_set;
4876 HeapRegionManager* _hrm;
4877 size_t _total_used;
4878
4879 public:
4880 RebuildRegionSetsClosure(bool free_list_only,
4881 HeapRegionSet* old_set, HeapRegionManager* hrm) :
4882 _free_list_only(free_list_only),
4883 _old_set(old_set), _hrm(hrm), _total_used(0) {
4884 assert(_hrm->num_free_regions() == 0, "pre-condition");
4885 if (!free_list_only) {
4886 assert(_old_set->is_empty(), "pre-condition");
4887 }
4888 }
4889
4890 bool do_heap_region(HeapRegion* r) {
4891 // After full GC, no region should have a remembered set.
4892 r->rem_set()->clear(true);
4893 if (r->is_empty()) {
4894 // Add free regions to the free list
4895 r->set_free();
4896 _hrm->insert_into_free_list(r);
4897 } else if (!_free_list_only) {
4898
4899 if (r->is_humongous()) {
4900 // We ignore humongous regions. We left the humongous set unchanged.
4901 } else {
4902 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4903 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
4904 r->move_to_old();
4905 _old_set->add(r);
4906 }
4907 _total_used += r->used();
4908 }
4909
4910 return false;
4911 }
4912
4913 size_t total_used() {
4914 return _total_used;
4915 }
4916 };
4917
4918 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4919 assert_at_safepoint_on_vm_thread();
4920
4921 if (!free_list_only) {
4922 _eden.clear();
4923 _survivor.clear();
4924 }
4925
4926 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4927 heap_region_iterate(&cl);
4928
4929 if (!free_list_only) {
4930 set_used(cl.total_used());
4931 if (_archive_allocator != NULL) {
4932 _archive_allocator->clear_used();
4933 }
4934 }
4935 assert(used_unlocked() == recalculate_used(),
4936 "inconsistent used_unlocked(), "
4937 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4938 used_unlocked(), recalculate_used());
4939 }
4940
4941 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4942 HeapRegion* hr = heap_region_containing(p);
4943 return hr->is_in(p);
4944 }
4945
4946 // Methods for the mutator alloc region
4947
4948 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4949 bool force) {
4950 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4951 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4952 if (force || should_allocate) {
4953 HeapRegion* new_alloc_region = new_region(word_size,
4954 false /* is_old */,
4955 false /* do_expand */);
4956 if (new_alloc_region != NULL) {
4957 set_region_short_lived_locked(new_alloc_region);
4958 _hr_printer.alloc(new_alloc_region, !should_allocate);
4959 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4960 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4961 return new_alloc_region;
4962 }
4963 }
4964 return NULL;
4965 }
4966
4967 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4968 size_t allocated_bytes) {
4969 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4970 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4971
4972 collection_set()->add_eden_region(alloc_region);
4973 increase_used(allocated_bytes);
4974 _hr_printer.retire(alloc_region);
4975 // We update the eden sizes here, when the region is retired,
4976 // instead of when it's allocated, since this is the point that its
4977 // used space has been recored in _summary_bytes_used.
4978 g1mm()->update_eden_size();
4979 }
4980
4981 // Methods for the GC alloc regions
4982
4983 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4984 if (dest.is_old()) {
4985 return true;
4986 } else {
4987 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4988 }
4989 }
4990
4991 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4992 assert(FreeList_lock->owned_by_self(), "pre-condition");
4993
4994 if (!has_more_regions(dest)) {
4995 return NULL;
4996 }
4997
4998 const bool is_survivor = dest.is_young();
4999
5000 HeapRegion* new_alloc_region = new_region(word_size,
5001 !is_survivor,
5002 true /* do_expand */);
5003 if (new_alloc_region != NULL) {
5004 if (is_survivor) {
5005 new_alloc_region->set_survivor();
5006 _survivor.add(new_alloc_region);
5007 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5008 } else {
5009 new_alloc_region->set_old();
5010 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5011 }
5012 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
5013 _hr_printer.alloc(new_alloc_region);
5014 bool during_im = collector_state()->in_initial_mark_gc();
5015 new_alloc_region->note_start_of_copying(during_im);
5016 return new_alloc_region;
5017 }
5018 return NULL;
5019 }
5020
5021 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5022 size_t allocated_bytes,
5023 InCSetState dest) {
5024 bool during_im = collector_state()->in_initial_mark_gc();
5025 alloc_region->note_end_of_copying(during_im);
5026 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5027 if (dest.is_old()) {
5028 _old_set.add(alloc_region);
5029 }
5030 _hr_printer.retire(alloc_region);
5031 }
5032
5033 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5034 bool expanded = false;
5035 uint index = _hrm.find_highest_free(&expanded);
5036
5037 if (index != G1_NO_HRM_INDEX) {
5038 if (expanded) {
5039 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5040 HeapRegion::GrainWords * HeapWordSize);
5041 }
5042 _hrm.allocate_free_regions_starting_at(index, 1);
5043 return region_at(index);
5044 }
5045 return NULL;
5046 }
5047
5048 // Optimized nmethod scanning
5049
5050 class RegisterNMethodOopClosure: public OopClosure {
5051 G1CollectedHeap* _g1h;
5052 nmethod* _nm;
5053
5054 template <class T> void do_oop_work(T* p) {
5055 T heap_oop = RawAccess<>::oop_load(p);
5056 if (!CompressedOops::is_null(heap_oop)) {
5057 oop obj = CompressedOops::decode_not_null(heap_oop);
5058 HeapRegion* hr = _g1h->heap_region_containing(obj);
5059 assert(!hr->is_continues_humongous(),
5060 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5061 " starting at " HR_FORMAT,
5062 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5063
5064 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5065 hr->add_strong_code_root_locked(_nm);
5066 }
5067 }
5068
5069 public:
5070 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5071 _g1h(g1h), _nm(nm) {}
5072
5073 void do_oop(oop* p) { do_oop_work(p); }
5074 void do_oop(narrowOop* p) { do_oop_work(p); }
5075 };
5076
5077 class UnregisterNMethodOopClosure: public OopClosure {
5078 G1CollectedHeap* _g1h;
5079 nmethod* _nm;
5080
5081 template <class T> void do_oop_work(T* p) {
5082 T heap_oop = RawAccess<>::oop_load(p);
5083 if (!CompressedOops::is_null(heap_oop)) {
5084 oop obj = CompressedOops::decode_not_null(heap_oop);
5085 HeapRegion* hr = _g1h->heap_region_containing(obj);
5086 assert(!hr->is_continues_humongous(),
5087 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5088 " starting at " HR_FORMAT,
5089 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5090
5091 hr->remove_strong_code_root(_nm);
5092 }
5093 }
5094
5095 public:
5096 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5097 _g1h(g1h), _nm(nm) {}
5098
5099 void do_oop(oop* p) { do_oop_work(p); }
5100 void do_oop(narrowOop* p) { do_oop_work(p); }
5101 };
5102
5103 // Returns true if the reference points to an object that
5104 // can move in an incremental collection.
5105 bool G1CollectedHeap::is_scavengable(oop obj) {
5106 HeapRegion* hr = heap_region_containing(obj);
5107 return !hr->is_pinned();
5108 }
5109
5110 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5111 guarantee(nm != NULL, "sanity");
5112 RegisterNMethodOopClosure reg_cl(this, nm);
5113 nm->oops_do(®_cl);
5114 }
5115
5116 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5117 guarantee(nm != NULL, "sanity");
5118 UnregisterNMethodOopClosure reg_cl(this, nm);
5119 nm->oops_do(®_cl, true);
5120 }
5121
5122 void G1CollectedHeap::purge_code_root_memory() {
5123 double purge_start = os::elapsedTime();
5124 G1CodeRootSet::purge();
5125 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5126 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5127 }
5128
5129 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5130 G1CollectedHeap* _g1h;
5131
5132 public:
5133 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5134 _g1h(g1h) {}
5135
5136 void do_code_blob(CodeBlob* cb) {
5137 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5138 if (nm == NULL) {
5139 return;
5140 }
5141
5142 if (ScavengeRootsInCode) {
5143 _g1h->register_nmethod(nm);
5144 }
5145 }
5146 };
5147
5148 void G1CollectedHeap::rebuild_strong_code_roots() {
5149 RebuildStrongCodeRootClosure blob_cl(this);
5150 CodeCache::blobs_do(&blob_cl);
5151 }
5152
5153 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5154 GrowableArray<GCMemoryManager*> memory_managers(2);
5155 memory_managers.append(&_memory_manager);
5156 memory_managers.append(&_full_gc_memory_manager);
5157 return memory_managers;
5158 }
5159
5160 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5161 GrowableArray<MemoryPool*> memory_pools(3);
5162 memory_pools.append(_eden_pool);
5163 memory_pools.append(_survivor_pool);
5164 memory_pools.append(_old_pool);
5165 return memory_pools;
5166 }