1 /*
2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentMarkThread.inline.hpp"
33 #include "gc/g1/g1Allocator.inline.hpp"
34 #include "gc/g1/g1CollectedHeap.inline.hpp"
35 #include "gc/g1/g1CollectionSet.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1DefaultPolicy.hpp"
41 #include "gc/g1/g1EvacStats.inline.hpp"
42 #include "gc/g1/g1FullCollector.hpp"
43 #include "gc/g1/g1GCPhaseTimes.hpp"
44 #include "gc/g1/g1HeapSizingPolicy.hpp"
45 #include "gc/g1/g1HeapTransition.hpp"
46 #include "gc/g1/g1HeapVerifier.hpp"
47 #include "gc/g1/g1HotCardCache.hpp"
48 #include "gc/g1/g1MemoryPool.hpp"
49 #include "gc/g1/g1OopClosures.inline.hpp"
50 #include "gc/g1/g1ParScanThreadState.inline.hpp"
51 #include "gc/g1/g1Policy.hpp"
52 #include "gc/g1/g1RegionToSpaceMapper.hpp"
53 #include "gc/g1/g1RemSet.hpp"
54 #include "gc/g1/g1RootClosures.hpp"
55 #include "gc/g1/g1RootProcessor.hpp"
56 #include "gc/g1/g1StringDedup.hpp"
57 #include "gc/g1/g1YCTypes.hpp"
58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
59 #include "gc/g1/heapRegion.inline.hpp"
60 #include "gc/g1/heapRegionRemSet.hpp"
61 #include "gc/g1/heapRegionSet.inline.hpp"
62 #include "gc/g1/vm_operations_g1.hpp"
63 #include "gc/shared/adaptiveSizePolicy.hpp"
64 #include "gc/shared/gcHeapSummary.hpp"
65 #include "gc/shared/gcId.hpp"
66 #include "gc/shared/gcLocker.inline.hpp"
67 #include "gc/shared/gcTimer.hpp"
68 #include "gc/shared/gcTrace.hpp"
69 #include "gc/shared/gcTraceTime.inline.hpp"
70 #include "gc/shared/generationSpec.hpp"
71 #include "gc/shared/isGCActiveMark.hpp"
72 #include "gc/shared/preservedMarks.inline.hpp"
73 #include "gc/shared/suspendibleThreadSet.hpp"
74 #include "gc/shared/referenceProcessor.inline.hpp"
75 #include "gc/shared/taskqueue.inline.hpp"
76 #include "gc/shared/weakProcessor.hpp"
77 #include "logging/log.hpp"
78 #include "memory/allocation.hpp"
79 #include "memory/iterator.hpp"
80 #include "memory/resourceArea.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*
159 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
160 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
161 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
162 if (!_secondary_free_list.is_empty()) {
163 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
164 "secondary_free_list has %u entries",
165 _secondary_free_list.length());
166 // It looks as if there are free regions available on the
167 // secondary_free_list. Let's move them to the free_list and try
168 // again to allocate from it.
169 append_secondary_free_list();
170
171 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
172 "empty we should have moved at least one entry to the free_list");
173 HeapRegion* res = _hrm.allocate_free_region(is_old);
174 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
175 "allocated " HR_FORMAT " from secondary_free_list",
176 HR_FORMAT_PARAMS(res));
177 return res;
178 }
179
180 // Wait here until we get notified either when (a) there are no
181 // more free regions coming or (b) some regions have been moved on
182 // the secondary_free_list.
183 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
184 }
185
186 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
187 "could not allocate from secondary_free_list");
188 return NULL;
189 }
190
191 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
192 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
193 "the only time we use this to allocate a humongous region is "
194 "when we are allocating a single humongous region");
195
196 HeapRegion* res;
197 if (G1StressConcRegionFreeing) {
198 if (!_secondary_free_list.is_empty()) {
199 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
200 "forced to look at the secondary_free_list");
201 res = new_region_try_secondary_free_list(is_old);
202 if (res != NULL) {
203 return res;
204 }
205 }
206 }
207
208 res = _hrm.allocate_free_region(is_old);
209
210 if (res == NULL) {
211 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
212 "res == NULL, trying the secondary_free_list");
213 res = new_region_try_secondary_free_list(is_old);
214 }
215 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
216 // Currently, only attempts to allocate GC alloc regions set
217 // do_expand to true. So, we should only reach here during a
218 // safepoint. If this assumption changes we might have to
219 // reconsider the use of _expand_heap_after_alloc_failure.
220 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
221
222 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
223 word_size * HeapWordSize);
224
225 if (expand(word_size * HeapWordSize)) {
226 // Given that expand() succeeded in expanding the heap, and we
227 // always expand the heap by an amount aligned to the heap
228 // region size, the free list should in theory not be empty.
229 // In either case allocate_free_region() will check for NULL.
230 res = _hrm.allocate_free_region(is_old);
231 } else {
232 _expand_heap_after_alloc_failure = false;
233 }
234 }
235 return res;
236 }
237
238 HeapWord*
239 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
240 uint num_regions,
241 size_t word_size) {
242 assert(first != G1_NO_HRM_INDEX, "pre-condition");
243 assert(is_humongous(word_size), "word_size should be humongous");
244 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
245
246 // Index of last region in the series.
247 uint last = first + num_regions - 1;
248
249 // We need to initialize the region(s) we just discovered. This is
250 // a bit tricky given that it can happen concurrently with
251 // refinement threads refining cards on these regions and
252 // potentially wanting to refine the BOT as they are scanning
253 // those cards (this can happen shortly after a cleanup; see CR
254 // 6991377). So we have to set up the region(s) carefully and in
255 // a specific order.
256
257 // The word size sum of all the regions we will allocate.
258 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
259 assert(word_size <= word_size_sum, "sanity");
260
261 // This will be the "starts humongous" region.
262 HeapRegion* first_hr = region_at(first);
263 // The header of the new object will be placed at the bottom of
264 // the first region.
265 HeapWord* new_obj = first_hr->bottom();
266 // This will be the new top of the new object.
267 HeapWord* obj_top = new_obj + word_size;
268
269 // First, we need to zero the header of the space that we will be
270 // allocating. When we update top further down, some refinement
271 // threads might try to scan the region. By zeroing the header we
272 // ensure that any thread that will try to scan the region will
273 // come across the zero klass word and bail out.
274 //
275 // NOTE: It would not have been correct to have used
276 // CollectedHeap::fill_with_object() and make the space look like
277 // an int array. The thread that is doing the allocation will
278 // later update the object header to a potentially different array
279 // type and, for a very short period of time, the klass and length
280 // fields will be inconsistent. This could cause a refinement
281 // thread to calculate the object size incorrectly.
282 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
283
284 // Next, pad out the unused tail of the last region with filler
285 // objects, for improved usage accounting.
286 // How many words we use for filler objects.
287 size_t word_fill_size = word_size_sum - word_size;
288
289 // How many words memory we "waste" which cannot hold a filler object.
290 size_t words_not_fillable = 0;
291
292 if (word_fill_size >= min_fill_size()) {
293 fill_with_objects(obj_top, word_fill_size);
294 } else if (word_fill_size > 0) {
295 // We have space to fill, but we cannot fit an object there.
296 words_not_fillable = word_fill_size;
297 word_fill_size = 0;
298 }
299
300 // We will set up the first region as "starts humongous". This
301 // will also update the BOT covering all the regions to reflect
302 // that there is a single object that starts at the bottom of the
303 // first region.
304 first_hr->set_starts_humongous(obj_top, word_fill_size);
305 // Then, if there are any, we will set up the "continues
306 // humongous" regions.
307 HeapRegion* hr = NULL;
308 for (uint i = first + 1; i <= last; ++i) {
309 hr = region_at(i);
310 hr->set_continues_humongous(first_hr);
311 }
312
313 // Up to this point no concurrent thread would have been able to
314 // do any scanning on any region in this series. All the top
315 // fields still point to bottom, so the intersection between
316 // [bottom,top] and [card_start,card_end] will be empty. Before we
317 // update the top fields, we'll do a storestore to make sure that
318 // no thread sees the update to top before the zeroing of the
319 // object header and the BOT initialization.
320 OrderAccess::storestore();
321
322 // Now, we will update the top fields of the "continues humongous"
323 // regions except the last one.
324 for (uint i = first; i < last; ++i) {
325 hr = region_at(i);
326 hr->set_top(hr->end());
327 }
328
329 hr = region_at(last);
330 // If we cannot fit a filler object, we must set top to the end
331 // of the humongous object, otherwise we cannot iterate the heap
332 // and the BOT will not be complete.
333 hr->set_top(hr->end() - words_not_fillable);
334
335 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
336 "obj_top should be in last region");
337
338 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
339
340 assert(words_not_fillable == 0 ||
341 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
342 "Miscalculation in humongous allocation");
343
344 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
345
346 for (uint i = first; i <= last; ++i) {
347 hr = region_at(i);
348 _humongous_set.add(hr);
349 _hr_printer.alloc(hr);
350 }
351
352 return new_obj;
353 }
354
355 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
356 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
357 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
358 }
359
360 // If could fit into free regions w/o expansion, try.
361 // Otherwise, if can expand, do so.
362 // Otherwise, if using ex regions might help, try with ex given back.
363 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
364 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
365
366 _verifier->verify_region_sets_optional();
367
368 uint first = G1_NO_HRM_INDEX;
369 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
370
371 if (obj_regions == 1) {
372 // Only one region to allocate, try to use a fast path by directly allocating
373 // from the free lists. Do not try to expand here, we will potentially do that
374 // later.
375 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
376 if (hr != NULL) {
377 first = hr->hrm_index();
378 }
379 } else {
380 // We can't allocate humongous regions spanning more than one region while
381 // cleanupComplete() is running, since some of the regions we find to be
382 // empty might not yet be added to the free list. It is not straightforward
383 // to know in which list they are on so that we can remove them. We only
384 // need to do this if we need to allocate more than one region to satisfy the
385 // current humongous allocation request. If we are only allocating one region
386 // we use the one-region region allocation code (see above), that already
387 // potentially waits for regions from the secondary free list.
388 wait_while_free_regions_coming();
389 append_secondary_free_list_if_not_empty_with_lock();
390
391 // Policy: Try only empty regions (i.e. already committed first). Maybe we
392 // are lucky enough to find some.
393 first = _hrm.find_contiguous_only_empty(obj_regions);
394 if (first != G1_NO_HRM_INDEX) {
395 _hrm.allocate_free_regions_starting_at(first, obj_regions);
396 }
397 }
398
399 if (first == G1_NO_HRM_INDEX) {
400 // Policy: We could not find enough regions for the humongous object in the
401 // free list. Look through the heap to find a mix of free and uncommitted regions.
402 // If so, try expansion.
403 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
404 if (first != G1_NO_HRM_INDEX) {
405 // We found something. Make sure these regions are committed, i.e. expand
406 // the heap. Alternatively we could do a defragmentation GC.
407 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
408 word_size * HeapWordSize);
409
410 _hrm.expand_at(first, obj_regions, workers());
411 g1_policy()->record_new_heap_size(num_regions());
412
413 #ifdef ASSERT
414 for (uint i = first; i < first + obj_regions; ++i) {
415 HeapRegion* hr = region_at(i);
416 assert(hr->is_free(), "sanity");
417 assert(hr->is_empty(), "sanity");
418 assert(is_on_master_free_list(hr), "sanity");
419 }
420 #endif
421 _hrm.allocate_free_regions_starting_at(first, obj_regions);
422 } else {
423 // Policy: Potentially trigger a defragmentation GC.
424 }
425 }
426
427 HeapWord* result = NULL;
428 if (first != G1_NO_HRM_INDEX) {
429 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
430 assert(result != NULL, "it should always return a valid result");
431
432 // A successful humongous object allocation changes the used space
433 // information of the old generation so we need to recalculate the
434 // sizes and update the jstat counters here.
435 g1mm()->update_sizes();
436 }
437
438 _verifier->verify_region_sets_optional();
439
440 return result;
441 }
442
443 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
444 assert_heap_not_locked_and_not_at_safepoint();
445 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
446
447 return attempt_allocation(word_size);
448 }
449
450 HeapWord*
451 G1CollectedHeap::mem_allocate(size_t word_size,
452 bool* gc_overhead_limit_was_exceeded) {
453 assert_heap_not_locked_and_not_at_safepoint();
454
455 if (is_humongous(word_size)) {
456 return attempt_allocation_humongous(word_size);
457 }
458 return attempt_allocation(word_size);
459 }
460
461 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
462 ResourceMark rm; // For retrieving the thread names in log messages.
463
464 // Make sure you read the note in attempt_allocation_humongous().
465
466 assert_heap_not_locked_and_not_at_safepoint();
467 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
468 "be called for humongous allocation requests");
469
470 // We should only get here after the first-level allocation attempt
471 // (attempt_allocation()) failed to allocate.
472
473 // We will loop until a) we manage to successfully perform the
474 // allocation or b) we successfully schedule a collection which
475 // fails to perform the allocation. b) is the only case when we'll
476 // return NULL.
477 HeapWord* result = NULL;
478 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
479 bool should_try_gc;
480 uint gc_count_before;
481
482 {
483 MutexLockerEx x(Heap_lock);
484 result = _allocator->attempt_allocation_locked(word_size);
485 if (result != NULL) {
486 return result;
487 }
488
489 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
490 // This is different to when only GCLocker::needs_gc() is set: try to avoid
491 // waiting because the GCLocker is active to not wait too long.
492 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
493 // No need for an ergo message here, can_expand_young_list() does this when
494 // it returns true.
495 result = _allocator->attempt_allocation_force(word_size);
496 if (result != NULL) {
497 return result;
498 }
499 }
500 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
501 // the GCLocker initiated GC has been performed and then retry. This includes
502 // the case when the GC Locker is not active but has not been performed.
503 should_try_gc = !GCLocker::needs_gc();
504 // Read the GC count while still holding the Heap_lock.
505 gc_count_before = total_collections();
506 }
507
508 if (should_try_gc) {
509 bool succeeded;
510 result = do_collection_pause(word_size, gc_count_before, &succeeded,
511 GCCause::_g1_inc_collection_pause);
512 if (result != NULL) {
513 assert(succeeded, "only way to get back a non-NULL result");
514 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
515 Thread::current()->name(), p2i(result));
516 return result;
517 }
518
519 if (succeeded) {
520 // We successfully scheduled a collection which failed to allocate. No
521 // point in trying to allocate further. We'll just return NULL.
522 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
523 SIZE_FORMAT " words", Thread::current()->name(), word_size);
524 return NULL;
525 }
526 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
527 Thread::current()->name(), word_size);
528 } else {
529 // Failed to schedule a collection.
530 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
531 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
532 SIZE_FORMAT " words", Thread::current()->name(), word_size);
533 return NULL;
534 }
535 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
536 // The GCLocker is either active or the GCLocker initiated
537 // GC has not yet been performed. Stall until it is and
538 // then retry the allocation.
539 GCLocker::stall_until_clear();
540 gclocker_retry_count += 1;
541 }
542
543 // We can reach here if we were unsuccessful in scheduling a
544 // collection (because another thread beat us to it) or if we were
545 // stalled due to the GC locker. In either can we should retry the
546 // allocation attempt in case another thread successfully
547 // performed a collection and reclaimed enough space. We do the
548 // first attempt (without holding the Heap_lock) here and the
549 // follow-on attempt will be at the start of the next loop
550 // iteration (after taking the Heap_lock).
551
552 result = _allocator->attempt_allocation(word_size);
553 if (result != NULL) {
554 return result;
555 }
556
557 // Give a warning if we seem to be looping forever.
558 if ((QueuedAllocationWarningCount > 0) &&
559 (try_count % QueuedAllocationWarningCount == 0)) {
560 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
561 Thread::current()->name(), try_count, word_size);
562 }
563 }
564
565 ShouldNotReachHere();
566 return NULL;
567 }
568
569 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
570 assert_at_safepoint_on_vm_thread();
571 if (_archive_allocator == NULL) {
572 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
573 }
574 }
575
576 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
577 // Allocations in archive regions cannot be of a size that would be considered
578 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
579 // may be different at archive-restore time.
580 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
581 }
582
583 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
584 assert_at_safepoint_on_vm_thread();
585 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
586 if (is_archive_alloc_too_large(word_size)) {
587 return NULL;
588 }
589 return _archive_allocator->archive_mem_allocate(word_size);
590 }
591
592 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
593 size_t end_alignment_in_bytes) {
594 assert_at_safepoint_on_vm_thread();
595 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
596
597 // Call complete_archive to do the real work, filling in the MemRegion
598 // array with the archive regions.
599 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
600 delete _archive_allocator;
601 _archive_allocator = NULL;
602 }
603
604 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
605 assert(ranges != NULL, "MemRegion array NULL");
606 assert(count != 0, "No MemRegions provided");
607 MemRegion reserved = _hrm.reserved();
608 for (size_t i = 0; i < count; i++) {
609 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
610 return false;
611 }
612 }
613 return true;
614 }
615
616 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
617 size_t count,
618 bool open) {
619 assert(!is_init_completed(), "Expect to be called at JVM init time");
620 assert(ranges != NULL, "MemRegion array NULL");
621 assert(count != 0, "No MemRegions provided");
622 MutexLockerEx x(Heap_lock);
623
624 MemRegion reserved = _hrm.reserved();
625 HeapWord* prev_last_addr = NULL;
626 HeapRegion* prev_last_region = NULL;
627
628 // Temporarily disable pretouching of heap pages. This interface is used
629 // when mmap'ing archived heap data in, so pre-touching is wasted.
630 FlagSetting fs(AlwaysPreTouch, false);
631
632 // Enable archive object checking used by G1MarkSweep. We have to let it know
633 // about each archive range, so that objects in those ranges aren't marked.
634 G1ArchiveAllocator::enable_archive_object_check();
635
636 // For each specified MemRegion range, allocate the corresponding G1
637 // regions and mark them as archive regions. We expect the ranges
638 // in ascending starting address order, without overlap.
639 for (size_t i = 0; i < count; i++) {
640 MemRegion curr_range = ranges[i];
641 HeapWord* start_address = curr_range.start();
642 size_t word_size = curr_range.word_size();
643 HeapWord* last_address = curr_range.last();
644 size_t commits = 0;
645
646 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
647 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
648 p2i(start_address), p2i(last_address));
649 guarantee(start_address > prev_last_addr,
650 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
651 p2i(start_address), p2i(prev_last_addr));
652 prev_last_addr = last_address;
653
654 // Check for ranges that start in the same G1 region in which the previous
655 // range ended, and adjust the start address so we don't try to allocate
656 // the same region again. If the current range is entirely within that
657 // region, skip it, just adjusting the recorded top.
658 HeapRegion* start_region = _hrm.addr_to_region(start_address);
659 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
660 start_address = start_region->end();
661 if (start_address > last_address) {
662 increase_used(word_size * HeapWordSize);
663 start_region->set_top(last_address + 1);
664 continue;
665 }
666 start_region->set_top(start_address);
667 curr_range = MemRegion(start_address, last_address + 1);
668 start_region = _hrm.addr_to_region(start_address);
669 }
670
671 // Perform the actual region allocation, exiting if it fails.
672 // Then note how much new space we have allocated.
673 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
674 return false;
675 }
676 increase_used(word_size * HeapWordSize);
677 if (commits != 0) {
678 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
679 HeapRegion::GrainWords * HeapWordSize * commits);
680
681 }
682
683 // Mark each G1 region touched by the range as archive, add it to
684 // the old set, and set top.
685 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
686 HeapRegion* last_region = _hrm.addr_to_region(last_address);
687 prev_last_region = last_region;
688
689 while (curr_region != NULL) {
690 assert(curr_region->is_empty() && !curr_region->is_pinned(),
691 "Region already in use (index %u)", curr_region->hrm_index());
692 if (open) {
693 curr_region->set_open_archive();
694 } else {
695 curr_region->set_closed_archive();
696 }
697 _hr_printer.alloc(curr_region);
698 _old_set.add(curr_region);
699 HeapWord* top;
700 HeapRegion* next_region;
701 if (curr_region != last_region) {
702 top = curr_region->end();
703 next_region = _hrm.next_region_in_heap(curr_region);
704 } else {
705 top = last_address + 1;
706 next_region = NULL;
707 }
708 curr_region->set_top(top);
709 curr_region->set_first_dead(top);
710 curr_region->set_end_of_live(top);
711 curr_region = next_region;
712 }
713
714 // Notify mark-sweep of the archive
715 G1ArchiveAllocator::set_range_archive(curr_range, open);
716 }
717 return true;
718 }
719
720 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
721 assert(!is_init_completed(), "Expect to be called at JVM init time");
722 assert(ranges != NULL, "MemRegion array NULL");
723 assert(count != 0, "No MemRegions provided");
724 MemRegion reserved = _hrm.reserved();
725 HeapWord *prev_last_addr = NULL;
726 HeapRegion* prev_last_region = NULL;
727
728 // For each MemRegion, create filler objects, if needed, in the G1 regions
729 // that contain the address range. The address range actually within the
730 // MemRegion will not be modified. That is assumed to have been initialized
731 // elsewhere, probably via an mmap of archived heap data.
732 MutexLockerEx x(Heap_lock);
733 for (size_t i = 0; i < count; i++) {
734 HeapWord* start_address = ranges[i].start();
735 HeapWord* last_address = ranges[i].last();
736
737 assert(reserved.contains(start_address) && reserved.contains(last_address),
738 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
739 p2i(start_address), p2i(last_address));
740 assert(start_address > prev_last_addr,
741 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
742 p2i(start_address), p2i(prev_last_addr));
743
744 HeapRegion* start_region = _hrm.addr_to_region(start_address);
745 HeapRegion* last_region = _hrm.addr_to_region(last_address);
746 HeapWord* bottom_address = start_region->bottom();
747
748 // Check for a range beginning in the same region in which the
749 // previous one ended.
750 if (start_region == prev_last_region) {
751 bottom_address = prev_last_addr + 1;
752 }
753
754 // Verify that the regions were all marked as archive regions by
755 // alloc_archive_regions.
756 HeapRegion* curr_region = start_region;
757 while (curr_region != NULL) {
758 guarantee(curr_region->is_archive(),
759 "Expected archive region at index %u", curr_region->hrm_index());
760 if (curr_region != last_region) {
761 curr_region = _hrm.next_region_in_heap(curr_region);
762 } else {
763 curr_region = NULL;
764 }
765 }
766
767 prev_last_addr = last_address;
768 prev_last_region = last_region;
769
770 // Fill the memory below the allocated range with dummy object(s),
771 // if the region bottom does not match the range start, or if the previous
772 // range ended within the same G1 region, and there is a gap.
773 if (start_address != bottom_address) {
774 size_t fill_size = pointer_delta(start_address, bottom_address);
775 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
776 increase_used(fill_size * HeapWordSize);
777 }
778 }
779 }
780
781 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
782 assert_heap_not_locked_and_not_at_safepoint();
783 assert(!is_humongous(word_size), "attempt_allocation() should not "
784 "be called for humongous allocation requests");
785
786 HeapWord* result = _allocator->attempt_allocation(word_size);
787
788 if (result == NULL) {
789 result = attempt_allocation_slow(word_size);
790 }
791 assert_heap_not_locked();
792 if (result != NULL) {
793 dirty_young_block(result, word_size);
794 }
795 return result;
796 }
797
798 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
799 assert(!is_init_completed(), "Expect to be called at JVM init time");
800 assert(ranges != NULL, "MemRegion array NULL");
801 assert(count != 0, "No MemRegions provided");
802 MemRegion reserved = _hrm.reserved();
803 HeapWord* prev_last_addr = NULL;
804 HeapRegion* prev_last_region = NULL;
805 size_t size_used = 0;
806 size_t uncommitted_regions = 0;
807
808 // For each Memregion, free the G1 regions that constitute it, and
809 // notify mark-sweep that the range is no longer to be considered 'archive.'
810 MutexLockerEx x(Heap_lock);
811 for (size_t i = 0; i < count; i++) {
812 HeapWord* start_address = ranges[i].start();
813 HeapWord* last_address = ranges[i].last();
814
815 assert(reserved.contains(start_address) && reserved.contains(last_address),
816 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
817 p2i(start_address), p2i(last_address));
818 assert(start_address > prev_last_addr,
819 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
820 p2i(start_address), p2i(prev_last_addr));
821 size_used += ranges[i].byte_size();
822 prev_last_addr = last_address;
823
824 HeapRegion* start_region = _hrm.addr_to_region(start_address);
825 HeapRegion* last_region = _hrm.addr_to_region(last_address);
826
827 // Check for ranges that start in the same G1 region in which the previous
828 // range ended, and adjust the start address so we don't try to free
829 // the same region again. If the current range is entirely within that
830 // region, skip it.
831 if (start_region == prev_last_region) {
832 start_address = start_region->end();
833 if (start_address > last_address) {
834 continue;
835 }
836 start_region = _hrm.addr_to_region(start_address);
837 }
838 prev_last_region = last_region;
839
840 // After verifying that each region was marked as an archive region by
841 // alloc_archive_regions, set it free and empty and uncommit it.
842 HeapRegion* curr_region = start_region;
843 while (curr_region != NULL) {
844 guarantee(curr_region->is_archive(),
845 "Expected archive region at index %u", curr_region->hrm_index());
846 uint curr_index = curr_region->hrm_index();
847 _old_set.remove(curr_region);
848 curr_region->set_free();
849 curr_region->set_top(curr_region->bottom());
850 if (curr_region != last_region) {
851 curr_region = _hrm.next_region_in_heap(curr_region);
852 } else {
853 curr_region = NULL;
854 }
855 _hrm.shrink_at(curr_index, 1);
856 uncommitted_regions++;
857 }
858
859 // Notify mark-sweep that this is no longer an archive range.
860 G1ArchiveAllocator::set_range_archive(ranges[i], false);
861 }
862
863 if (uncommitted_regions != 0) {
864 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
865 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
866 }
867 decrease_used(size_used);
868 }
869
870 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
871 ResourceMark rm; // For retrieving the thread names in log messages.
872
873 // The structure of this method has a lot of similarities to
874 // attempt_allocation_slow(). The reason these two were not merged
875 // into a single one is that such a method would require several "if
876 // allocation is not humongous do this, otherwise do that"
877 // conditional paths which would obscure its flow. In fact, an early
878 // version of this code did use a unified method which was harder to
879 // follow and, as a result, it had subtle bugs that were hard to
880 // track down. So keeping these two methods separate allows each to
881 // be more readable. It will be good to keep these two in sync as
882 // much as possible.
883
884 assert_heap_not_locked_and_not_at_safepoint();
885 assert(is_humongous(word_size), "attempt_allocation_humongous() "
886 "should only be called for humongous allocations");
887
888 // Humongous objects can exhaust the heap quickly, so we should check if we
889 // need to start a marking cycle at each humongous object allocation. We do
890 // the check before we do the actual allocation. The reason for doing it
891 // before the allocation is that we avoid having to keep track of the newly
892 // allocated memory while we do a GC.
893 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
894 word_size)) {
895 collect(GCCause::_g1_humongous_allocation);
896 }
897
898 // We will loop until a) we manage to successfully perform the
899 // allocation or b) we successfully schedule a collection which
900 // fails to perform the allocation. b) is the only case when we'll
901 // return NULL.
902 HeapWord* result = NULL;
903 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
904 bool should_try_gc;
905 uint gc_count_before;
906
907
908 {
909 MutexLockerEx x(Heap_lock);
910
911 // Given that humongous objects are not allocated in young
912 // regions, we'll first try to do the allocation without doing a
913 // collection hoping that there's enough space in the heap.
914 result = humongous_obj_allocate(word_size);
915 if (result != NULL) {
916 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
917 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
918 return result;
919 }
920
921 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
922 // the GCLocker initiated GC has been performed and then retry. This includes
923 // the case when the GC Locker is not active but has not been performed.
924 should_try_gc = !GCLocker::needs_gc();
925 // Read the GC count while still holding the Heap_lock.
926 gc_count_before = total_collections();
927 }
928
929 if (should_try_gc) {
930 bool succeeded;
931 result = do_collection_pause(word_size, gc_count_before, &succeeded,
932 GCCause::_g1_humongous_allocation);
933 if (result != NULL) {
934 assert(succeeded, "only way to get back a non-NULL result");
935 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
936 Thread::current()->name(), p2i(result));
937 return result;
938 }
939
940 if (succeeded) {
941 // We successfully scheduled a collection which failed to allocate. No
942 // point in trying to allocate further. We'll just return NULL.
943 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
944 SIZE_FORMAT " words", Thread::current()->name(), word_size);
945 return NULL;
946 }
947 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
948 Thread::current()->name(), word_size);
949 } else {
950 // Failed to schedule a collection.
951 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
952 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
953 SIZE_FORMAT " words", Thread::current()->name(), word_size);
954 return NULL;
955 }
956 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
957 // The GCLocker is either active or the GCLocker initiated
958 // GC has not yet been performed. Stall until it is and
959 // then retry the allocation.
960 GCLocker::stall_until_clear();
961 gclocker_retry_count += 1;
962 }
963
964
965 // We can reach here if we were unsuccessful in scheduling a
966 // collection (because another thread beat us to it) or if we were
967 // stalled due to the GC locker. In either can we should retry the
968 // allocation attempt in case another thread successfully
969 // performed a collection and reclaimed enough space.
970 // Humongous object allocation always needs a lock, so we wait for the retry
971 // in the next iteration of the loop, unlike for the regular iteration case.
972 // Give a warning if we seem to be looping forever.
973
974 if ((QueuedAllocationWarningCount > 0) &&
975 (try_count % QueuedAllocationWarningCount == 0)) {
976 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
977 Thread::current()->name(), try_count, word_size);
978 }
979 }
980
981 ShouldNotReachHere();
982 return NULL;
983 }
984
985 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
986 bool expect_null_mutator_alloc_region) {
987 assert_at_safepoint_on_vm_thread();
988 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
989 "the current alloc region was unexpectedly found to be non-NULL");
990
991 if (!is_humongous(word_size)) {
992 return _allocator->attempt_allocation_locked(word_size);
993 } else {
994 HeapWord* result = humongous_obj_allocate(word_size);
995 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
996 collector_state()->set_initiate_conc_mark_if_possible(true);
997 }
998 return result;
999 }
1000
1001 ShouldNotReachHere();
1002 }
1003
1004 class PostCompactionPrinterClosure: public HeapRegionClosure {
1005 private:
1006 G1HRPrinter* _hr_printer;
1007 public:
1008 bool do_heap_region(HeapRegion* hr) {
1009 assert(!hr->is_young(), "not expecting to find young regions");
1010 _hr_printer->post_compaction(hr);
1011 return false;
1012 }
1013
1014 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1015 : _hr_printer(hr_printer) { }
1016 };
1017
1018 void G1CollectedHeap::print_hrm_post_compaction() {
1019 if (_hr_printer.is_active()) {
1020 PostCompactionPrinterClosure cl(hr_printer());
1021 heap_region_iterate(&cl);
1022 }
1023 }
1024
1025 void G1CollectedHeap::abort_concurrent_cycle() {
1026 // Note: When we have a more flexible GC logging framework that
1027 // allows us to add optional attributes to a GC log record we
1028 // could consider timing and reporting how long we wait in the
1029 // following two methods.
1030 wait_while_free_regions_coming();
1031 // If we start the compaction before the CM threads finish
1032 // scanning the root regions we might trip them over as we'll
1033 // be moving objects / updating references. So let's wait until
1034 // they are done. By telling them to abort, they should complete
1035 // early.
1036 _cm->root_regions()->abort();
1037 _cm->root_regions()->wait_until_scan_finished();
1038 append_secondary_free_list_if_not_empty_with_lock();
1039
1040 // Disable discovery and empty the discovered lists
1041 // for the CM ref processor.
1042 ref_processor_cm()->disable_discovery();
1043 ref_processor_cm()->abandon_partial_discovery();
1044 ref_processor_cm()->verify_no_references_recorded();
1045
1046 // Abandon current iterations of concurrent marking and concurrent
1047 // refinement, if any are in progress.
1048 concurrent_mark()->abort();
1049 }
1050
1051 void G1CollectedHeap::prepare_heap_for_full_collection() {
1052 // Make sure we'll choose a new allocation region afterwards.
1053 _allocator->release_mutator_alloc_region();
1054 _allocator->abandon_gc_alloc_regions();
1055 g1_rem_set()->cleanupHRRS();
1056
1057 // We may have added regions to the current incremental collection
1058 // set between the last GC or pause and now. We need to clear the
1059 // incremental collection set and then start rebuilding it afresh
1060 // after this full GC.
1061 abandon_collection_set(collection_set());
1062
1063 tear_down_region_sets(false /* free_list_only */);
1064 collector_state()->set_gcs_are_young(true);
1065 }
1066
1067 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1068 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1069 assert(used() == recalculate_used(), "Should be equal");
1070 _verifier->verify_region_sets_optional();
1071 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1072 _verifier->check_bitmaps("Full GC Start");
1073 }
1074
1075 void G1CollectedHeap::prepare_heap_for_mutators() {
1076 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1077 ClassLoaderDataGraph::purge();
1078 MetaspaceAux::verify_metrics();
1079
1080 // Prepare heap for normal collections.
1081 assert(num_free_regions() == 0, "we should not have added any free regions");
1082 rebuild_region_sets(false /* free_list_only */);
1083 abort_refinement();
1084 resize_if_necessary_after_full_collection();
1085
1086 // Rebuild the strong code root lists for each region
1087 rebuild_strong_code_roots();
1088
1089 // Start a new incremental collection set for the next pause
1090 start_new_collection_set();
1091
1092 _allocator->init_mutator_alloc_region();
1093
1094 // Post collection state updates.
1095 MetaspaceGC::compute_new_size();
1096 }
1097
1098 void G1CollectedHeap::abort_refinement() {
1099 if (_hot_card_cache->use_cache()) {
1100 _hot_card_cache->reset_hot_cache();
1101 }
1102
1103 // Discard all remembered set updates.
1104 JavaThread::dirty_card_queue_set().abandon_logs();
1105 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1106 }
1107
1108 void G1CollectedHeap::verify_after_full_collection() {
1109 check_gc_time_stamps();
1110 _hrm.verify_optional();
1111 _verifier->verify_region_sets_optional();
1112 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1113 // Clear the previous marking bitmap, if needed for bitmap verification.
1114 // Note we cannot do this when we clear the next marking bitmap in
1115 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1116 // objects marked during a full GC against the previous bitmap.
1117 // But we need to clear it before calling check_bitmaps below since
1118 // the full GC has compacted objects and updated TAMS but not updated
1119 // the prev bitmap.
1120 if (G1VerifyBitmaps) {
1121 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1122 _cm->clear_prev_bitmap(workers());
1123 }
1124 _verifier->check_bitmaps("Full GC End");
1125
1126 // At this point there should be no regions in the
1127 // entire heap tagged as young.
1128 assert(check_young_list_empty(), "young list should be empty at this point");
1129
1130 // Note: since we've just done a full GC, concurrent
1131 // marking is no longer active. Therefore we need not
1132 // re-enable reference discovery for the CM ref processor.
1133 // That will be done at the start of the next marking cycle.
1134 // We also know that the STW processor should no longer
1135 // discover any new references.
1136 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1137 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1138 ref_processor_stw()->verify_no_references_recorded();
1139 ref_processor_cm()->verify_no_references_recorded();
1140 }
1141
1142 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1143 // Post collection logging.
1144 // We should do this after we potentially resize the heap so
1145 // that all the COMMIT / UNCOMMIT events are generated before
1146 // the compaction events.
1147 print_hrm_post_compaction();
1148 heap_transition->print();
1149 print_heap_after_gc();
1150 print_heap_regions();
1151 #ifdef TRACESPINNING
1152 ParallelTaskTerminator::print_termination_counts();
1153 #endif
1154 }
1155
1156 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1157 bool clear_all_soft_refs) {
1158 assert_at_safepoint_on_vm_thread();
1159
1160 if (GCLocker::check_active_before_gc()) {
1161 // Full GC was not completed.
1162 return false;
1163 }
1164
1165 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1166 soft_ref_policy()->should_clear_all_soft_refs();
1167
1168 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1169 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1170
1171 collector.prepare_collection();
1172 collector.collect();
1173 collector.complete_collection();
1174
1175 // Full collection was successfully completed.
1176 return true;
1177 }
1178
1179 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1180 // Currently, there is no facility in the do_full_collection(bool) API to notify
1181 // the caller that the collection did not succeed (e.g., because it was locked
1182 // out by the GC locker). So, right now, we'll ignore the return value.
1183 bool dummy = do_full_collection(true, /* explicit_gc */
1184 clear_all_soft_refs);
1185 }
1186
1187 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1188 // Capacity, free and used after the GC counted as full regions to
1189 // include the waste in the following calculations.
1190 const size_t capacity_after_gc = capacity();
1191 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1192
1193 // This is enforced in arguments.cpp.
1194 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1195 "otherwise the code below doesn't make sense");
1196
1197 // We don't have floating point command-line arguments
1198 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1199 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1200 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1201 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1202
1203 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1204 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1205
1206 // We have to be careful here as these two calculations can overflow
1207 // 32-bit size_t's.
1208 double used_after_gc_d = (double) used_after_gc;
1209 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1210 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1211
1212 // Let's make sure that they are both under the max heap size, which
1213 // by default will make them fit into a size_t.
1214 double desired_capacity_upper_bound = (double) max_heap_size;
1215 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1216 desired_capacity_upper_bound);
1217 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1218 desired_capacity_upper_bound);
1219
1220 // We can now safely turn them into size_t's.
1221 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1222 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1223
1224 // This assert only makes sense here, before we adjust them
1225 // with respect to the min and max heap size.
1226 assert(minimum_desired_capacity <= maximum_desired_capacity,
1227 "minimum_desired_capacity = " SIZE_FORMAT ", "
1228 "maximum_desired_capacity = " SIZE_FORMAT,
1229 minimum_desired_capacity, maximum_desired_capacity);
1230
1231 // Should not be greater than the heap max size. No need to adjust
1232 // it with respect to the heap min size as it's a lower bound (i.e.,
1233 // we'll try to make the capacity larger than it, not smaller).
1234 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1235 // Should not be less than the heap min size. No need to adjust it
1236 // with respect to the heap max size as it's an upper bound (i.e.,
1237 // we'll try to make the capacity smaller than it, not greater).
1238 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1239
1240 if (capacity_after_gc < minimum_desired_capacity) {
1241 // Don't expand unless it's significant
1242 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1243
1244 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1245 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1246 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1247 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1248
1249 expand(expand_bytes, _workers);
1250
1251 // No expansion, now see if we want to shrink
1252 } else if (capacity_after_gc > maximum_desired_capacity) {
1253 // Capacity too large, compute shrinking size
1254 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1255
1256 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1257 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1258 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1259 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1260
1261 shrink(shrink_bytes);
1262 }
1263 }
1264
1265 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1266 bool do_gc,
1267 bool clear_all_soft_refs,
1268 bool expect_null_mutator_alloc_region,
1269 bool* gc_succeeded) {
1270 *gc_succeeded = true;
1271 // Let's attempt the allocation first.
1272 HeapWord* result =
1273 attempt_allocation_at_safepoint(word_size,
1274 expect_null_mutator_alloc_region);
1275 if (result != NULL) {
1276 return result;
1277 }
1278
1279 // In a G1 heap, we're supposed to keep allocation from failing by
1280 // incremental pauses. Therefore, at least for now, we'll favor
1281 // expansion over collection. (This might change in the future if we can
1282 // do something smarter than full collection to satisfy a failed alloc.)
1283 result = expand_and_allocate(word_size);
1284 if (result != NULL) {
1285 return result;
1286 }
1287
1288 if (do_gc) {
1289 // Expansion didn't work, we'll try to do a Full GC.
1290 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1291 clear_all_soft_refs);
1292 }
1293
1294 return NULL;
1295 }
1296
1297 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1298 bool* succeeded) {
1299 assert_at_safepoint_on_vm_thread();
1300
1301 // Attempts to allocate followed by Full GC.
1302 HeapWord* result =
1303 satisfy_failed_allocation_helper(word_size,
1304 true, /* do_gc */
1305 false, /* clear_all_soft_refs */
1306 false, /* expect_null_mutator_alloc_region */
1307 succeeded);
1308
1309 if (result != NULL || !*succeeded) {
1310 return result;
1311 }
1312
1313 // Attempts to allocate followed by Full GC that will collect all soft references.
1314 result = satisfy_failed_allocation_helper(word_size,
1315 true, /* do_gc */
1316 true, /* clear_all_soft_refs */
1317 true, /* expect_null_mutator_alloc_region */
1318 succeeded);
1319
1320 if (result != NULL || !*succeeded) {
1321 return result;
1322 }
1323
1324 // Attempts to allocate, no GC
1325 result = satisfy_failed_allocation_helper(word_size,
1326 false, /* do_gc */
1327 false, /* clear_all_soft_refs */
1328 true, /* expect_null_mutator_alloc_region */
1329 succeeded);
1330
1331 if (result != NULL) {
1332 return result;
1333 }
1334
1335 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1336 "Flag should have been handled and cleared prior to this point");
1337
1338 // What else? We might try synchronous finalization later. If the total
1339 // space available is large enough for the allocation, then a more
1340 // complete compaction phase than we've tried so far might be
1341 // appropriate.
1342 return NULL;
1343 }
1344
1345 // Attempting to expand the heap sufficiently
1346 // to support an allocation of the given "word_size". If
1347 // successful, perform the allocation and return the address of the
1348 // allocated block, or else "NULL".
1349
1350 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1351 assert_at_safepoint_on_vm_thread();
1352
1353 _verifier->verify_region_sets_optional();
1354
1355 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1356 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1357 word_size * HeapWordSize);
1358
1359
1360 if (expand(expand_bytes, _workers)) {
1361 _hrm.verify_optional();
1362 _verifier->verify_region_sets_optional();
1363 return attempt_allocation_at_safepoint(word_size,
1364 false /* expect_null_mutator_alloc_region */);
1365 }
1366 return NULL;
1367 }
1368
1369 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1370 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1371 aligned_expand_bytes = align_up(aligned_expand_bytes,
1372 HeapRegion::GrainBytes);
1373
1374 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1375 expand_bytes, aligned_expand_bytes);
1376
1377 if (is_maximal_no_gc()) {
1378 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1379 return false;
1380 }
1381
1382 double expand_heap_start_time_sec = os::elapsedTime();
1383 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1384 assert(regions_to_expand > 0, "Must expand by at least one region");
1385
1386 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1387 if (expand_time_ms != NULL) {
1388 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1389 }
1390
1391 if (expanded_by > 0) {
1392 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1393 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1394 g1_policy()->record_new_heap_size(num_regions());
1395 } else {
1396 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1397
1398 // The expansion of the virtual storage space was unsuccessful.
1399 // Let's see if it was because we ran out of swap.
1400 if (G1ExitOnExpansionFailure &&
1401 _hrm.available() >= regions_to_expand) {
1402 // We had head room...
1403 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1404 }
1405 }
1406 return regions_to_expand > 0;
1407 }
1408
1409 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1410 size_t aligned_shrink_bytes =
1411 ReservedSpace::page_align_size_down(shrink_bytes);
1412 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1413 HeapRegion::GrainBytes);
1414 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1415
1416 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1417 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1418
1419
1420 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",
1421 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1422 if (num_regions_removed > 0) {
1423 g1_policy()->record_new_heap_size(num_regions());
1424 } else {
1425 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1426 }
1427 }
1428
1429 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1430 _verifier->verify_region_sets_optional();
1431
1432 // We should only reach here at the end of a Full GC which means we
1433 // should not not be holding to any GC alloc regions. The method
1434 // below will make sure of that and do any remaining clean up.
1435 _allocator->abandon_gc_alloc_regions();
1436
1437 // Instead of tearing down / rebuilding the free lists here, we
1438 // could instead use the remove_all_pending() method on free_list to
1439 // remove only the ones that we need to remove.
1440 tear_down_region_sets(true /* free_list_only */);
1441 shrink_helper(shrink_bytes);
1442 rebuild_region_sets(true /* free_list_only */);
1443
1444 _hrm.verify_optional();
1445 _verifier->verify_region_sets_optional();
1446 }
1447
1448 // Public methods.
1449
1450 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1451 CollectedHeap(),
1452 _young_gen_sampling_thread(NULL),
1453 _collector_policy(collector_policy),
1454 _soft_ref_policy(),
1455 _card_table(NULL),
1456 _memory_manager("G1 Young Generation", "end of minor GC"),
1457 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1458 _eden_pool(NULL),
1459 _survivor_pool(NULL),
1460 _old_pool(NULL),
1461 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1462 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1463 _g1_policy(new G1DefaultPolicy(_gc_timer_stw)),
1464 _collection_set(this, _g1_policy),
1465 _dirty_card_queue_set(false),
1466 _is_alive_closure_cm(this),
1467 _is_alive_closure_stw(this),
1468 _ref_processor_cm(NULL),
1469 _ref_processor_stw(NULL),
1470 _bot(NULL),
1471 _hot_card_cache(NULL),
1472 _g1_rem_set(NULL),
1473 _cr(NULL),
1474 _g1mm(NULL),
1475 _preserved_marks_set(true /* in_c_heap */),
1476 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1477 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1478 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1479 _humongous_reclaim_candidates(),
1480 _has_humongous_reclaim_candidates(false),
1481 _archive_allocator(NULL),
1482 _free_regions_coming(false),
1483 _gc_time_stamp(0),
1484 _summary_bytes_used(0),
1485 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1486 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1487 _expand_heap_after_alloc_failure(true),
1488 _old_marking_cycles_started(0),
1489 _old_marking_cycles_completed(0),
1490 _in_cset_fast_test() {
1491
1492 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1493 /* are_GC_task_threads */true,
1494 /* are_ConcurrentGC_threads */false);
1495 _workers->initialize_workers();
1496 _verifier = new G1HeapVerifier(this);
1497
1498 _allocator = new G1DefaultAllocator(this);
1499
1500 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1501
1502 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1503
1504 // Override the default _filler_array_max_size so that no humongous filler
1505 // objects are created.
1506 _filler_array_max_size = _humongous_object_threshold_in_words;
1507
1508 uint n_queues = ParallelGCThreads;
1509 _task_queues = new RefToScanQueueSet(n_queues);
1510
1511 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1512
1513 for (uint i = 0; i < n_queues; i++) {
1514 RefToScanQueue* q = new RefToScanQueue();
1515 q->initialize();
1516 _task_queues->register_queue(i, q);
1517 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1518 }
1519
1520 // Initialize the G1EvacuationFailureALot counters and flags.
1521 NOT_PRODUCT(reset_evacuation_should_fail();)
1522
1523 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1524 }
1525
1526 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1527 size_t size,
1528 size_t translation_factor) {
1529 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1530 // Allocate a new reserved space, preferring to use large pages.
1531 ReservedSpace rs(size, preferred_page_size);
1532 G1RegionToSpaceMapper* result =
1533 G1RegionToSpaceMapper::create_mapper(rs,
1534 size,
1535 rs.alignment(),
1536 HeapRegion::GrainBytes,
1537 translation_factor,
1538 mtGC);
1539
1540 os::trace_page_sizes_for_requested_size(description,
1541 size,
1542 preferred_page_size,
1543 rs.alignment(),
1544 rs.base(),
1545 rs.size());
1546
1547 return result;
1548 }
1549
1550 jint G1CollectedHeap::initialize_concurrent_refinement() {
1551 jint ecode = JNI_OK;
1552 _cr = G1ConcurrentRefine::create(&ecode);
1553 return ecode;
1554 }
1555
1556 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1557 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1558 if (_young_gen_sampling_thread->osthread() == NULL) {
1559 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1560 return JNI_ENOMEM;
1561 }
1562 return JNI_OK;
1563 }
1564
1565 jint G1CollectedHeap::initialize() {
1566 os::enable_vtime();
1567
1568 // Necessary to satisfy locking discipline assertions.
1569
1570 MutexLocker x(Heap_lock);
1571
1572 // While there are no constraints in the GC code that HeapWordSize
1573 // be any particular value, there are multiple other areas in the
1574 // system which believe this to be true (e.g. oop->object_size in some
1575 // cases incorrectly returns the size in wordSize units rather than
1576 // HeapWordSize).
1577 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1578
1579 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1580 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1581 size_t heap_alignment = collector_policy()->heap_alignment();
1582
1583 // Ensure that the sizes are properly aligned.
1584 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1585 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1586 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1587
1588 // Reserve the maximum.
1589
1590 // When compressed oops are enabled, the preferred heap base
1591 // is calculated by subtracting the requested size from the
1592 // 32Gb boundary and using the result as the base address for
1593 // heap reservation. If the requested size is not aligned to
1594 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1595 // into the ReservedHeapSpace constructor) then the actual
1596 // base of the reserved heap may end up differing from the
1597 // address that was requested (i.e. the preferred heap base).
1598 // If this happens then we could end up using a non-optimal
1599 // compressed oops mode.
1600
1601 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1602 heap_alignment);
1603
1604 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1605
1606 // Create the barrier set for the entire reserved region.
1607 G1CardTable* ct = new G1CardTable(reserved_region());
1608 ct->initialize();
1609 G1BarrierSet* bs = new G1BarrierSet(ct);
1610 bs->initialize();
1611 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1612 set_barrier_set(bs);
1613 _card_table = ct;
1614
1615 // Create the hot card cache.
1616 _hot_card_cache = new G1HotCardCache(this);
1617
1618 // Carve out the G1 part of the heap.
1619 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1620 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1621 G1RegionToSpaceMapper* heap_storage =
1622 G1RegionToSpaceMapper::create_mapper(g1_rs,
1623 g1_rs.size(),
1624 page_size,
1625 HeapRegion::GrainBytes,
1626 1,
1627 mtJavaHeap);
1628 os::trace_page_sizes("Heap",
1629 collector_policy()->min_heap_byte_size(),
1630 max_byte_size,
1631 page_size,
1632 heap_rs.base(),
1633 heap_rs.size());
1634 heap_storage->set_mapping_changed_listener(&_listener);
1635
1636 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1637 G1RegionToSpaceMapper* bot_storage =
1638 create_aux_memory_mapper("Block Offset Table",
1639 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1640 G1BlockOffsetTable::heap_map_factor());
1641
1642 G1RegionToSpaceMapper* cardtable_storage =
1643 create_aux_memory_mapper("Card Table",
1644 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1645 G1CardTable::heap_map_factor());
1646
1647 G1RegionToSpaceMapper* card_counts_storage =
1648 create_aux_memory_mapper("Card Counts Table",
1649 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1650 G1CardCounts::heap_map_factor());
1651
1652 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1653 G1RegionToSpaceMapper* prev_bitmap_storage =
1654 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1655 G1RegionToSpaceMapper* next_bitmap_storage =
1656 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1657
1658 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1659 _card_table->initialize(cardtable_storage);
1660 // Do later initialization work for concurrent refinement.
1661 _hot_card_cache->initialize(card_counts_storage);
1662
1663 // 6843694 - ensure that the maximum region index can fit
1664 // in the remembered set structures.
1665 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1666 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1667
1668 // Also create a G1 rem set.
1669 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1670 _g1_rem_set->initialize(max_capacity(), max_regions());
1671
1672 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1673 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1674 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1675 "too many cards per region");
1676
1677 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1678
1679 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1680
1681 {
1682 HeapWord* start = _hrm.reserved().start();
1683 HeapWord* end = _hrm.reserved().end();
1684 size_t granularity = HeapRegion::GrainBytes;
1685
1686 _in_cset_fast_test.initialize(start, end, granularity);
1687 _humongous_reclaim_candidates.initialize(start, end, granularity);
1688 }
1689
1690 // Create the G1ConcurrentMark data structure and thread.
1691 // (Must do this late, so that "max_regions" is defined.)
1692 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1693 if (_cm == NULL || !_cm->completed_initialization()) {
1694 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1695 return JNI_ENOMEM;
1696 }
1697 _cmThread = _cm->cm_thread();
1698
1699 // Now expand into the initial heap size.
1700 if (!expand(init_byte_size, _workers)) {
1701 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1702 return JNI_ENOMEM;
1703 }
1704
1705 // Perform any initialization actions delegated to the policy.
1706 g1_policy()->init(this, &_collection_set);
1707
1708 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1709 SATB_Q_FL_lock,
1710 G1SATBProcessCompletedThreshold,
1711 Shared_SATB_Q_lock);
1712
1713 jint ecode = initialize_concurrent_refinement();
1714 if (ecode != JNI_OK) {
1715 return ecode;
1716 }
1717
1718 ecode = initialize_young_gen_sampling_thread();
1719 if (ecode != JNI_OK) {
1720 return ecode;
1721 }
1722
1723 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1724 DirtyCardQ_FL_lock,
1725 (int)concurrent_refine()->yellow_zone(),
1726 (int)concurrent_refine()->red_zone(),
1727 Shared_DirtyCardQ_lock,
1728 NULL, // fl_owner
1729 true); // init_free_ids
1730
1731 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1732 DirtyCardQ_FL_lock,
1733 -1, // never trigger processing
1734 -1, // no limit on length
1735 Shared_DirtyCardQ_lock,
1736 &JavaThread::dirty_card_queue_set());
1737
1738 // Here we allocate the dummy HeapRegion that is required by the
1739 // G1AllocRegion class.
1740 HeapRegion* dummy_region = _hrm.get_dummy_region();
1741
1742 // We'll re-use the same region whether the alloc region will
1743 // require BOT updates or not and, if it doesn't, then a non-young
1744 // region will complain that it cannot support allocations without
1745 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1746 dummy_region->set_eden();
1747 // Make sure it's full.
1748 dummy_region->set_top(dummy_region->end());
1749 G1AllocRegion::setup(this, dummy_region);
1750
1751 _allocator->init_mutator_alloc_region();
1752
1753 // Do create of the monitoring and management support so that
1754 // values in the heap have been properly initialized.
1755 _g1mm = new G1MonitoringSupport(this);
1756
1757 G1StringDedup::initialize();
1758
1759 _preserved_marks_set.init(ParallelGCThreads);
1760
1761 _collection_set.initialize(max_regions());
1762
1763 return JNI_OK;
1764 }
1765
1766 void G1CollectedHeap::initialize_serviceability() {
1767 _eden_pool = new G1EdenPool(this);
1768 _survivor_pool = new G1SurvivorPool(this);
1769 _old_pool = new G1OldGenPool(this);
1770
1771 _full_gc_memory_manager.add_pool(_eden_pool);
1772 _full_gc_memory_manager.add_pool(_survivor_pool);
1773 _full_gc_memory_manager.add_pool(_old_pool);
1774
1775 _memory_manager.add_pool(_eden_pool);
1776 _memory_manager.add_pool(_survivor_pool);
1777
1778 }
1779
1780 void G1CollectedHeap::stop() {
1781 // Stop all concurrent threads. We do this to make sure these threads
1782 // do not continue to execute and access resources (e.g. logging)
1783 // that are destroyed during shutdown.
1784 _cr->stop();
1785 _young_gen_sampling_thread->stop();
1786 _cmThread->stop();
1787 if (G1StringDedup::is_enabled()) {
1788 G1StringDedup::stop();
1789 }
1790 }
1791
1792 void G1CollectedHeap::safepoint_synchronize_begin() {
1793 SuspendibleThreadSet::synchronize();
1794 }
1795
1796 void G1CollectedHeap::safepoint_synchronize_end() {
1797 SuspendibleThreadSet::desynchronize();
1798 }
1799
1800 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1801 return HeapRegion::max_region_size();
1802 }
1803
1804 void G1CollectedHeap::post_initialize() {
1805 CollectedHeap::post_initialize();
1806 ref_processing_init();
1807 }
1808
1809 void G1CollectedHeap::ref_processing_init() {
1810 // Reference processing in G1 currently works as follows:
1811 //
1812 // * There are two reference processor instances. One is
1813 // used to record and process discovered references
1814 // during concurrent marking; the other is used to
1815 // record and process references during STW pauses
1816 // (both full and incremental).
1817 // * Both ref processors need to 'span' the entire heap as
1818 // the regions in the collection set may be dotted around.
1819 //
1820 // * For the concurrent marking ref processor:
1821 // * Reference discovery is enabled at initial marking.
1822 // * Reference discovery is disabled and the discovered
1823 // references processed etc during remarking.
1824 // * Reference discovery is MT (see below).
1825 // * Reference discovery requires a barrier (see below).
1826 // * Reference processing may or may not be MT
1827 // (depending on the value of ParallelRefProcEnabled
1828 // and ParallelGCThreads).
1829 // * A full GC disables reference discovery by the CM
1830 // ref processor and abandons any entries on it's
1831 // discovered lists.
1832 //
1833 // * For the STW processor:
1834 // * Non MT discovery is enabled at the start of a full GC.
1835 // * Processing and enqueueing during a full GC is non-MT.
1836 // * During a full GC, references are processed after marking.
1837 //
1838 // * Discovery (may or may not be MT) is enabled at the start
1839 // of an incremental evacuation pause.
1840 // * References are processed near the end of a STW evacuation pause.
1841 // * For both types of GC:
1842 // * Discovery is atomic - i.e. not concurrent.
1843 // * Reference discovery will not need a barrier.
1844
1845 MemRegion mr = reserved_region();
1846
1847 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1848
1849 // Concurrent Mark ref processor
1850 _ref_processor_cm =
1851 new ReferenceProcessor(mr, // span
1852 mt_processing,
1853 // mt processing
1854 ParallelGCThreads,
1855 // degree of mt processing
1856 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1857 // mt discovery
1858 MAX2(ParallelGCThreads, ConcGCThreads),
1859 // degree of mt discovery
1860 false,
1861 // Reference discovery is not atomic
1862 &_is_alive_closure_cm);
1863 // is alive closure
1864 // (for efficiency/performance)
1865
1866 // STW ref processor
1867 _ref_processor_stw =
1868 new ReferenceProcessor(mr, // span
1869 mt_processing,
1870 // mt processing
1871 ParallelGCThreads,
1872 // degree of mt processing
1873 (ParallelGCThreads > 1),
1874 // mt discovery
1875 ParallelGCThreads,
1876 // degree of mt discovery
1877 true,
1878 // Reference discovery is atomic
1879 &_is_alive_closure_stw);
1880 // is alive closure
1881 // (for efficiency/performance)
1882 }
1883
1884 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1885 return _collector_policy;
1886 }
1887
1888 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1889 return &_soft_ref_policy;
1890 }
1891
1892 size_t G1CollectedHeap::capacity() const {
1893 return _hrm.length() * HeapRegion::GrainBytes;
1894 }
1895
1896 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1897 return _hrm.total_free_bytes();
1898 }
1899
1900 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1901 hr->reset_gc_time_stamp();
1902 }
1903
1904 #ifndef PRODUCT
1905
1906 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1907 private:
1908 unsigned _gc_time_stamp;
1909 bool _failures;
1910
1911 public:
1912 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1913 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1914
1915 virtual bool do_heap_region(HeapRegion* hr) {
1916 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1917 if (_gc_time_stamp != region_gc_time_stamp) {
1918 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1919 region_gc_time_stamp, _gc_time_stamp);
1920 _failures = true;
1921 }
1922 return false;
1923 }
1924
1925 bool failures() { return _failures; }
1926 };
1927
1928 void G1CollectedHeap::check_gc_time_stamps() {
1929 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1930 heap_region_iterate(&cl);
1931 guarantee(!cl.failures(), "all GC time stamps should have been reset");
1932 }
1933 #endif // PRODUCT
1934
1935 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1936 _hot_card_cache->drain(cl, worker_i);
1937 }
1938
1939 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1940 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1941 size_t n_completed_buffers = 0;
1942 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1943 n_completed_buffers++;
1944 }
1945 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1946 dcqs.clear_n_completed_buffers();
1947 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1948 }
1949
1950 // Computes the sum of the storage used by the various regions.
1951 size_t G1CollectedHeap::used() const {
1952 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1953 if (_archive_allocator != NULL) {
1954 result += _archive_allocator->used();
1955 }
1956 return result;
1957 }
1958
1959 size_t G1CollectedHeap::used_unlocked() const {
1960 return _summary_bytes_used;
1961 }
1962
1963 class SumUsedClosure: public HeapRegionClosure {
1964 size_t _used;
1965 public:
1966 SumUsedClosure() : _used(0) {}
1967 bool do_heap_region(HeapRegion* r) {
1968 _used += r->used();
1969 return false;
1970 }
1971 size_t result() { return _used; }
1972 };
1973
1974 size_t G1CollectedHeap::recalculate_used() const {
1975 double recalculate_used_start = os::elapsedTime();
1976
1977 SumUsedClosure blk;
1978 heap_region_iterate(&blk);
1979
1980 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1981 return blk.result();
1982 }
1983
1984 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1985 switch (cause) {
1986 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1987 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1988 case GCCause::_wb_conc_mark: return true;
1989 default : return false;
1990 }
1991 }
1992
1993 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1994 switch (cause) {
1995 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1996 case GCCause::_g1_humongous_allocation: return true;
1997 default: return is_user_requested_concurrent_full_gc(cause);
1998 }
1999 }
2000
2001 #ifndef PRODUCT
2002 void G1CollectedHeap::allocate_dummy_regions() {
2003 // Let's fill up most of the region
2004 size_t word_size = HeapRegion::GrainWords - 1024;
2005 // And as a result the region we'll allocate will be humongous.
2006 guarantee(is_humongous(word_size), "sanity");
2007
2008 // _filler_array_max_size is set to humongous object threshold
2009 // but temporarily change it to use CollectedHeap::fill_with_object().
2010 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2011
2012 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2013 // Let's use the existing mechanism for the allocation
2014 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2015 if (dummy_obj != NULL) {
2016 MemRegion mr(dummy_obj, word_size);
2017 CollectedHeap::fill_with_object(mr);
2018 } else {
2019 // If we can't allocate once, we probably cannot allocate
2020 // again. Let's get out of the loop.
2021 break;
2022 }
2023 }
2024 }
2025 #endif // !PRODUCT
2026
2027 void G1CollectedHeap::increment_old_marking_cycles_started() {
2028 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2029 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2030 "Wrong marking cycle count (started: %d, completed: %d)",
2031 _old_marking_cycles_started, _old_marking_cycles_completed);
2032
2033 _old_marking_cycles_started++;
2034 }
2035
2036 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2037 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2038
2039 // We assume that if concurrent == true, then the caller is a
2040 // concurrent thread that was joined the Suspendible Thread
2041 // Set. If there's ever a cheap way to check this, we should add an
2042 // assert here.
2043
2044 // Given that this method is called at the end of a Full GC or of a
2045 // concurrent cycle, and those can be nested (i.e., a Full GC can
2046 // interrupt a concurrent cycle), the number of full collections
2047 // completed should be either one (in the case where there was no
2048 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2049 // behind the number of full collections started.
2050
2051 // This is the case for the inner caller, i.e. a Full GC.
2052 assert(concurrent ||
2053 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2054 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2055 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2056 "is inconsistent with _old_marking_cycles_completed = %u",
2057 _old_marking_cycles_started, _old_marking_cycles_completed);
2058
2059 // This is the case for the outer caller, i.e. the concurrent cycle.
2060 assert(!concurrent ||
2061 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2062 "for outer caller (concurrent cycle): "
2063 "_old_marking_cycles_started = %u "
2064 "is inconsistent with _old_marking_cycles_completed = %u",
2065 _old_marking_cycles_started, _old_marking_cycles_completed);
2066
2067 _old_marking_cycles_completed += 1;
2068
2069 // We need to clear the "in_progress" flag in the CM thread before
2070 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2071 // is set) so that if a waiter requests another System.gc() it doesn't
2072 // incorrectly see that a marking cycle is still in progress.
2073 if (concurrent) {
2074 _cmThread->set_idle();
2075 }
2076
2077 // This notify_all() will ensure that a thread that called
2078 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2079 // and it's waiting for a full GC to finish will be woken up. It is
2080 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2081 FullGCCount_lock->notify_all();
2082 }
2083
2084 void G1CollectedHeap::collect(GCCause::Cause cause) {
2085 assert_heap_not_locked();
2086
2087 uint gc_count_before;
2088 uint old_marking_count_before;
2089 uint full_gc_count_before;
2090 bool retry_gc;
2091
2092 do {
2093 retry_gc = false;
2094
2095 {
2096 MutexLocker ml(Heap_lock);
2097
2098 // Read the GC count while holding the Heap_lock
2099 gc_count_before = total_collections();
2100 full_gc_count_before = total_full_collections();
2101 old_marking_count_before = _old_marking_cycles_started;
2102 }
2103
2104 if (should_do_concurrent_full_gc(cause)) {
2105 // Schedule an initial-mark evacuation pause that will start a
2106 // concurrent cycle. We're setting word_size to 0 which means that
2107 // we are not requesting a post-GC allocation.
2108 VM_G1CollectForAllocation op(0, /* word_size */
2109 gc_count_before,
2110 cause,
2111 true, /* should_initiate_conc_mark */
2112 g1_policy()->max_pause_time_ms());
2113 VMThread::execute(&op);
2114 if (!op.pause_succeeded()) {
2115 if (old_marking_count_before == _old_marking_cycles_started) {
2116 retry_gc = op.should_retry_gc();
2117 } else {
2118 // A Full GC happened while we were trying to schedule the
2119 // initial-mark GC. No point in starting a new cycle given
2120 // that the whole heap was collected anyway.
2121 }
2122
2123 if (retry_gc) {
2124 if (GCLocker::is_active_and_needs_gc()) {
2125 GCLocker::stall_until_clear();
2126 }
2127 }
2128 }
2129 } else {
2130 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2131 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2132
2133 // Schedule a standard evacuation pause. We're setting word_size
2134 // to 0 which means that we are not requesting a post-GC allocation.
2135 VM_G1CollectForAllocation op(0, /* word_size */
2136 gc_count_before,
2137 cause,
2138 false, /* should_initiate_conc_mark */
2139 g1_policy()->max_pause_time_ms());
2140 VMThread::execute(&op);
2141 } else {
2142 // Schedule a Full GC.
2143 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2144 VMThread::execute(&op);
2145 }
2146 }
2147 } while (retry_gc);
2148 }
2149
2150 bool G1CollectedHeap::is_in(const void* p) const {
2151 if (_hrm.reserved().contains(p)) {
2152 // Given that we know that p is in the reserved space,
2153 // heap_region_containing() should successfully
2154 // return the containing region.
2155 HeapRegion* hr = heap_region_containing(p);
2156 return hr->is_in(p);
2157 } else {
2158 return false;
2159 }
2160 }
2161
2162 #ifdef ASSERT
2163 bool G1CollectedHeap::is_in_exact(const void* p) const {
2164 bool contains = reserved_region().contains(p);
2165 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2166 if (contains && available) {
2167 return true;
2168 } else {
2169 return false;
2170 }
2171 }
2172 #endif
2173
2174 // Iteration functions.
2175
2176 // Iterates an ObjectClosure over all objects within a HeapRegion.
2177
2178 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2179 ObjectClosure* _cl;
2180 public:
2181 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2182 bool do_heap_region(HeapRegion* r) {
2183 if (!r->is_continues_humongous()) {
2184 r->object_iterate(_cl);
2185 }
2186 return false;
2187 }
2188 };
2189
2190 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2191 IterateObjectClosureRegionClosure blk(cl);
2192 heap_region_iterate(&blk);
2193 }
2194
2195 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2196 _hrm.iterate(cl);
2197 }
2198
2199 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2200 HeapRegionClaimer *hrclaimer,
2201 uint worker_id) const {
2202 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2203 }
2204
2205 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2206 HeapRegionClaimer *hrclaimer) const {
2207 _hrm.par_iterate(cl, hrclaimer, 0);
2208 }
2209
2210 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2211 _collection_set.iterate(cl);
2212 }
2213
2214 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2215 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2216 }
2217
2218 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2219 HeapRegion* hr = heap_region_containing(addr);
2220 return hr->block_start(addr);
2221 }
2222
2223 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2224 HeapRegion* hr = heap_region_containing(addr);
2225 return hr->block_size(addr);
2226 }
2227
2228 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2229 HeapRegion* hr = heap_region_containing(addr);
2230 return hr->block_is_obj(addr);
2231 }
2232
2233 bool G1CollectedHeap::supports_tlab_allocation() const {
2234 return true;
2235 }
2236
2237 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2238 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2239 }
2240
2241 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2242 return _eden.length() * HeapRegion::GrainBytes;
2243 }
2244
2245 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2246 // must be equal to the humongous object limit.
2247 size_t G1CollectedHeap::max_tlab_size() const {
2248 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2249 }
2250
2251 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2252 return _allocator->unsafe_max_tlab_alloc();
2253 }
2254
2255 size_t G1CollectedHeap::max_capacity() const {
2256 return _hrm.reserved().byte_size();
2257 }
2258
2259 jlong G1CollectedHeap::millis_since_last_gc() {
2260 // See the notes in GenCollectedHeap::millis_since_last_gc()
2261 // for more information about the implementation.
2262 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2263 _g1_policy->collection_pause_end_millis();
2264 if (ret_val < 0) {
2265 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2266 ". returning zero instead.", ret_val);
2267 return 0;
2268 }
2269 return ret_val;
2270 }
2271
2272 void G1CollectedHeap::prepare_for_verify() {
2273 _verifier->prepare_for_verify();
2274 }
2275
2276 void G1CollectedHeap::verify(VerifyOption vo) {
2277 _verifier->verify(vo);
2278 }
2279
2280 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2281 return true;
2282 }
2283
2284 const char* const* G1CollectedHeap::concurrent_phases() const {
2285 return _cmThread->concurrent_phases();
2286 }
2287
2288 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2289 return _cmThread->request_concurrent_phase(phase);
2290 }
2291
2292 class PrintRegionClosure: public HeapRegionClosure {
2293 outputStream* _st;
2294 public:
2295 PrintRegionClosure(outputStream* st) : _st(st) {}
2296 bool do_heap_region(HeapRegion* r) {
2297 r->print_on(_st);
2298 return false;
2299 }
2300 };
2301
2302 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2303 const HeapRegion* hr,
2304 const VerifyOption vo) const {
2305 switch (vo) {
2306 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2307 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2308 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2309 default: ShouldNotReachHere();
2310 }
2311 return false; // keep some compilers happy
2312 }
2313
2314 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2315 const VerifyOption vo) const {
2316 switch (vo) {
2317 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2318 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2319 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2320 default: ShouldNotReachHere();
2321 }
2322 return false; // keep some compilers happy
2323 }
2324
2325 void G1CollectedHeap::print_heap_regions() const {
2326 LogTarget(Trace, gc, heap, region) lt;
2327 if (lt.is_enabled()) {
2328 LogStream ls(lt);
2329 print_regions_on(&ls);
2330 }
2331 }
2332
2333 void G1CollectedHeap::print_on(outputStream* st) const {
2334 st->print(" %-20s", "garbage-first heap");
2335 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2336 capacity()/K, used_unlocked()/K);
2337 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2338 p2i(_hrm.reserved().start()),
2339 p2i(_hrm.reserved().end()));
2340 st->cr();
2341 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2342 uint young_regions = young_regions_count();
2343 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2344 (size_t) young_regions * HeapRegion::GrainBytes / K);
2345 uint survivor_regions = survivor_regions_count();
2346 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2347 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2348 st->cr();
2349 MetaspaceAux::print_on(st);
2350 }
2351
2352 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2353 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2354 "HS=humongous(starts), HC=humongous(continues), "
2355 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2356 "TAMS=top-at-mark-start (previous, next)");
2357 PrintRegionClosure blk(st);
2358 heap_region_iterate(&blk);
2359 }
2360
2361 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2362 print_on(st);
2363
2364 // Print the per-region information.
2365 print_regions_on(st);
2366 }
2367
2368 void G1CollectedHeap::print_on_error(outputStream* st) const {
2369 this->CollectedHeap::print_on_error(st);
2370
2371 if (_cm != NULL) {
2372 st->cr();
2373 _cm->print_on_error(st);
2374 }
2375 }
2376
2377 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2378 workers()->print_worker_threads_on(st);
2379 _cmThread->print_on(st);
2380 st->cr();
2381 _cm->print_worker_threads_on(st);
2382 _cr->print_threads_on(st);
2383 _young_gen_sampling_thread->print_on(st);
2384 if (G1StringDedup::is_enabled()) {
2385 G1StringDedup::print_worker_threads_on(st);
2386 }
2387 }
2388
2389 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2390 workers()->threads_do(tc);
2391 tc->do_thread(_cmThread);
2392 _cm->threads_do(tc);
2393 _cr->threads_do(tc);
2394 tc->do_thread(_young_gen_sampling_thread);
2395 if (G1StringDedup::is_enabled()) {
2396 G1StringDedup::threads_do(tc);
2397 }
2398 }
2399
2400 void G1CollectedHeap::print_tracing_info() const {
2401 g1_rem_set()->print_summary_info();
2402 concurrent_mark()->print_summary_info();
2403 }
2404
2405 #ifndef PRODUCT
2406 // Helpful for debugging RSet issues.
2407
2408 class PrintRSetsClosure : public HeapRegionClosure {
2409 private:
2410 const char* _msg;
2411 size_t _occupied_sum;
2412
2413 public:
2414 bool do_heap_region(HeapRegion* r) {
2415 HeapRegionRemSet* hrrs = r->rem_set();
2416 size_t occupied = hrrs->occupied();
2417 _occupied_sum += occupied;
2418
2419 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2420 if (occupied == 0) {
2421 tty->print_cr(" RSet is empty");
2422 } else {
2423 hrrs->print();
2424 }
2425 tty->print_cr("----------");
2426 return false;
2427 }
2428
2429 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2430 tty->cr();
2431 tty->print_cr("========================================");
2432 tty->print_cr("%s", msg);
2433 tty->cr();
2434 }
2435
2436 ~PrintRSetsClosure() {
2437 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2438 tty->print_cr("========================================");
2439 tty->cr();
2440 }
2441 };
2442
2443 void G1CollectedHeap::print_cset_rsets() {
2444 PrintRSetsClosure cl("Printing CSet RSets");
2445 collection_set_iterate(&cl);
2446 }
2447
2448 void G1CollectedHeap::print_all_rsets() {
2449 PrintRSetsClosure cl("Printing All RSets");;
2450 heap_region_iterate(&cl);
2451 }
2452 #endif // PRODUCT
2453
2454 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2455
2456 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2457 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2458 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2459
2460 size_t eden_capacity_bytes =
2461 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2462
2463 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2464 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2465 eden_capacity_bytes, survivor_used_bytes, num_regions());
2466 }
2467
2468 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2469 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2470 stats->unused(), stats->used(), stats->region_end_waste(),
2471 stats->regions_filled(), stats->direct_allocated(),
2472 stats->failure_used(), stats->failure_waste());
2473 }
2474
2475 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2476 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2477 gc_tracer->report_gc_heap_summary(when, heap_summary);
2478
2479 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2480 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2481 }
2482
2483 G1CollectedHeap* G1CollectedHeap::heap() {
2484 CollectedHeap* heap = Universe::heap();
2485 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2486 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2487 return (G1CollectedHeap*)heap;
2488 }
2489
2490 void G1CollectedHeap::gc_prologue(bool full) {
2491 // always_do_update_barrier = false;
2492 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2493
2494 // This summary needs to be printed before incrementing total collections.
2495 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2496
2497 // Update common counters.
2498 increment_total_collections(full /* full gc */);
2499 if (full) {
2500 increment_old_marking_cycles_started();
2501 reset_gc_time_stamp();
2502 } else {
2503 increment_gc_time_stamp();
2504 }
2505
2506 // Fill TLAB's and such
2507 double start = os::elapsedTime();
2508 accumulate_statistics_all_tlabs();
2509 ensure_parsability(true);
2510 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2511 }
2512
2513 void G1CollectedHeap::gc_epilogue(bool full) {
2514 // Update common counters.
2515 if (full) {
2516 // Update the number of full collections that have been completed.
2517 increment_old_marking_cycles_completed(false /* concurrent */);
2518 }
2519
2520 // We are at the end of the GC. Total collections has already been increased.
2521 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2522
2523 // FIXME: what is this about?
2524 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2525 // is set.
2526 #if COMPILER2_OR_JVMCI
2527 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2528 #endif
2529 // always_do_update_barrier = true;
2530
2531 double start = os::elapsedTime();
2532 resize_all_tlabs();
2533 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2534
2535 MemoryService::track_memory_usage();
2536 // We have just completed a GC. Update the soft reference
2537 // policy with the new heap occupancy
2538 Universe::update_heap_info_at_gc();
2539 }
2540
2541 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2542 uint gc_count_before,
2543 bool* succeeded,
2544 GCCause::Cause gc_cause) {
2545 assert_heap_not_locked_and_not_at_safepoint();
2546 VM_G1CollectForAllocation op(word_size,
2547 gc_count_before,
2548 gc_cause,
2549 false, /* should_initiate_conc_mark */
2550 g1_policy()->max_pause_time_ms());
2551 VMThread::execute(&op);
2552
2553 HeapWord* result = op.result();
2554 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2555 assert(result == NULL || ret_succeeded,
2556 "the result should be NULL if the VM did not succeed");
2557 *succeeded = ret_succeeded;
2558
2559 assert_heap_not_locked();
2560 return result;
2561 }
2562
2563 void
2564 G1CollectedHeap::doConcurrentMark() {
2565 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2566 if (!_cmThread->in_progress()) {
2567 _cmThread->set_started();
2568 CGC_lock->notify();
2569 }
2570 }
2571
2572 size_t G1CollectedHeap::pending_card_num() {
2573 size_t extra_cards = 0;
2574 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2575 DirtyCardQueue& dcq = curr->dirty_card_queue();
2576 extra_cards += dcq.size();
2577 }
2578 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2579 size_t buffer_size = dcqs.buffer_size();
2580 size_t buffer_num = dcqs.completed_buffers_num();
2581
2582 return buffer_size * buffer_num + extra_cards;
2583 }
2584
2585 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2586 private:
2587 size_t _total_humongous;
2588 size_t _candidate_humongous;
2589
2590 DirtyCardQueue _dcq;
2591
2592 // We don't nominate objects with many remembered set entries, on
2593 // the assumption that such objects are likely still live.
2594 bool is_remset_small(HeapRegion* region) const {
2595 HeapRegionRemSet* const rset = region->rem_set();
2596 return G1EagerReclaimHumongousObjectsWithStaleRefs
2597 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2598 : rset->is_empty();
2599 }
2600
2601 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2602 assert(region->is_starts_humongous(), "Must start a humongous object");
2603
2604 oop obj = oop(region->bottom());
2605
2606 // Dead objects cannot be eager reclaim candidates. Due to class
2607 // unloading it is unsafe to query their classes so we return early.
2608 if (heap->is_obj_dead(obj, region)) {
2609 return false;
2610 }
2611
2612 // Candidate selection must satisfy the following constraints
2613 // while concurrent marking is in progress:
2614 //
2615 // * In order to maintain SATB invariants, an object must not be
2616 // reclaimed if it was allocated before the start of marking and
2617 // has not had its references scanned. Such an object must have
2618 // its references (including type metadata) scanned to ensure no
2619 // live objects are missed by the marking process. Objects
2620 // allocated after the start of concurrent marking don't need to
2621 // be scanned.
2622 //
2623 // * An object must not be reclaimed if it is on the concurrent
2624 // mark stack. Objects allocated after the start of concurrent
2625 // marking are never pushed on the mark stack.
2626 //
2627 // Nominating only objects allocated after the start of concurrent
2628 // marking is sufficient to meet both constraints. This may miss
2629 // some objects that satisfy the constraints, but the marking data
2630 // structures don't support efficiently performing the needed
2631 // additional tests or scrubbing of the mark stack.
2632 //
2633 // However, we presently only nominate is_typeArray() objects.
2634 // A humongous object containing references induces remembered
2635 // set entries on other regions. In order to reclaim such an
2636 // object, those remembered sets would need to be cleaned up.
2637 //
2638 // We also treat is_typeArray() objects specially, allowing them
2639 // to be reclaimed even if allocated before the start of
2640 // concurrent mark. For this we rely on mark stack insertion to
2641 // exclude is_typeArray() objects, preventing reclaiming an object
2642 // that is in the mark stack. We also rely on the metadata for
2643 // such objects to be built-in and so ensured to be kept live.
2644 // Frequent allocation and drop of large binary blobs is an
2645 // important use case for eager reclaim, and this special handling
2646 // may reduce needed headroom.
2647
2648 return obj->is_typeArray() && is_remset_small(region);
2649 }
2650
2651 public:
2652 RegisterHumongousWithInCSetFastTestClosure()
2653 : _total_humongous(0),
2654 _candidate_humongous(0),
2655 _dcq(&JavaThread::dirty_card_queue_set()) {
2656 }
2657
2658 virtual bool do_heap_region(HeapRegion* r) {
2659 if (!r->is_starts_humongous()) {
2660 return false;
2661 }
2662 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2663
2664 bool is_candidate = humongous_region_is_candidate(g1h, r);
2665 uint rindex = r->hrm_index();
2666 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2667 if (is_candidate) {
2668 _candidate_humongous++;
2669 g1h->register_humongous_region_with_cset(rindex);
2670 // Is_candidate already filters out humongous object with large remembered sets.
2671 // If we have a humongous object with a few remembered sets, we simply flush these
2672 // remembered set entries into the DCQS. That will result in automatic
2673 // re-evaluation of their remembered set entries during the following evacuation
2674 // phase.
2675 if (!r->rem_set()->is_empty()) {
2676 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2677 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2678 G1CardTable* ct = g1h->card_table();
2679 HeapRegionRemSetIterator hrrs(r->rem_set());
2680 size_t card_index;
2681 while (hrrs.has_next(card_index)) {
2682 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2683 // The remembered set might contain references to already freed
2684 // regions. Filter out such entries to avoid failing card table
2685 // verification.
2686 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2687 if (*card_ptr != G1CardTable::dirty_card_val()) {
2688 *card_ptr = G1CardTable::dirty_card_val();
2689 _dcq.enqueue(card_ptr);
2690 }
2691 }
2692 }
2693 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2694 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2695 hrrs.n_yielded(), r->rem_set()->occupied());
2696 r->rem_set()->clear_locked();
2697 }
2698 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2699 }
2700 _total_humongous++;
2701
2702 return false;
2703 }
2704
2705 size_t total_humongous() const { return _total_humongous; }
2706 size_t candidate_humongous() const { return _candidate_humongous; }
2707
2708 void flush_rem_set_entries() { _dcq.flush(); }
2709 };
2710
2711 void G1CollectedHeap::register_humongous_regions_with_cset() {
2712 if (!G1EagerReclaimHumongousObjects) {
2713 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2714 return;
2715 }
2716 double time = os::elapsed_counter();
2717
2718 // Collect reclaim candidate information and register candidates with cset.
2719 RegisterHumongousWithInCSetFastTestClosure cl;
2720 heap_region_iterate(&cl);
2721
2722 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2723 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2724 cl.total_humongous(),
2725 cl.candidate_humongous());
2726 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2727
2728 // Finally flush all remembered set entries to re-check into the global DCQS.
2729 cl.flush_rem_set_entries();
2730 }
2731
2732 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2733 public:
2734 bool do_heap_region(HeapRegion* hr) {
2735 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2736 hr->verify_rem_set();
2737 }
2738 return false;
2739 }
2740 };
2741
2742 uint G1CollectedHeap::num_task_queues() const {
2743 return _task_queues->size();
2744 }
2745
2746 #if TASKQUEUE_STATS
2747 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2748 st->print_raw_cr("GC Task Stats");
2749 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2750 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2751 }
2752
2753 void G1CollectedHeap::print_taskqueue_stats() const {
2754 if (!log_is_enabled(Trace, gc, task, stats)) {
2755 return;
2756 }
2757 Log(gc, task, stats) log;
2758 ResourceMark rm;
2759 LogStream ls(log.trace());
2760 outputStream* st = &ls;
2761
2762 print_taskqueue_stats_hdr(st);
2763
2764 TaskQueueStats totals;
2765 const uint n = num_task_queues();
2766 for (uint i = 0; i < n; ++i) {
2767 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2768 totals += task_queue(i)->stats;
2769 }
2770 st->print_raw("tot "); totals.print(st); st->cr();
2771
2772 DEBUG_ONLY(totals.verify());
2773 }
2774
2775 void G1CollectedHeap::reset_taskqueue_stats() {
2776 const uint n = num_task_queues();
2777 for (uint i = 0; i < n; ++i) {
2778 task_queue(i)->stats.reset();
2779 }
2780 }
2781 #endif // TASKQUEUE_STATS
2782
2783 void G1CollectedHeap::wait_for_root_region_scanning() {
2784 double scan_wait_start = os::elapsedTime();
2785 // We have to wait until the CM threads finish scanning the
2786 // root regions as it's the only way to ensure that all the
2787 // objects on them have been correctly scanned before we start
2788 // moving them during the GC.
2789 bool waited = _cm->root_regions()->wait_until_scan_finished();
2790 double wait_time_ms = 0.0;
2791 if (waited) {
2792 double scan_wait_end = os::elapsedTime();
2793 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2794 }
2795 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2796 }
2797
2798 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2799 private:
2800 G1HRPrinter* _hr_printer;
2801 public:
2802 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2803
2804 virtual bool do_heap_region(HeapRegion* r) {
2805 _hr_printer->cset(r);
2806 return false;
2807 }
2808 };
2809
2810 void G1CollectedHeap::start_new_collection_set() {
2811 collection_set()->start_incremental_building();
2812
2813 clear_cset_fast_test();
2814
2815 guarantee(_eden.length() == 0, "eden should have been cleared");
2816 g1_policy()->transfer_survivors_to_cset(survivor());
2817 }
2818
2819 bool
2820 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2821 assert_at_safepoint_on_vm_thread();
2822 guarantee(!is_gc_active(), "collection is not reentrant");
2823
2824 if (GCLocker::check_active_before_gc()) {
2825 return false;
2826 }
2827
2828 _gc_timer_stw->register_gc_start();
2829
2830 GCIdMark gc_id_mark;
2831 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2832
2833 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2834 ResourceMark rm;
2835
2836 g1_policy()->note_gc_start();
2837
2838 wait_for_root_region_scanning();
2839
2840 print_heap_before_gc();
2841 print_heap_regions();
2842 trace_heap_before_gc(_gc_tracer_stw);
2843
2844 _verifier->verify_region_sets_optional();
2845 _verifier->verify_dirty_young_regions();
2846
2847 // We should not be doing initial mark unless the conc mark thread is running
2848 if (!_cmThread->should_terminate()) {
2849 // This call will decide whether this pause is an initial-mark
2850 // pause. If it is, during_initial_mark_pause() will return true
2851 // for the duration of this pause.
2852 g1_policy()->decide_on_conc_mark_initiation();
2853 }
2854
2855 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2856 assert(!collector_state()->during_initial_mark_pause() ||
2857 collector_state()->gcs_are_young(), "sanity");
2858
2859 // We also do not allow mixed GCs during marking.
2860 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2861
2862 // Record whether this pause is an initial mark. When the current
2863 // thread has completed its logging output and it's safe to signal
2864 // the CM thread, the flag's value in the policy has been reset.
2865 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2866
2867 // Inner scope for scope based logging, timers, and stats collection
2868 {
2869 EvacuationInfo evacuation_info;
2870
2871 if (collector_state()->during_initial_mark_pause()) {
2872 // We are about to start a marking cycle, so we increment the
2873 // full collection counter.
2874 increment_old_marking_cycles_started();
2875 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2876 }
2877
2878 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2879
2880 GCTraceCPUTime tcpu;
2881
2882 G1HeapVerifier::G1VerifyType verify_type;
2883 FormatBuffer<> gc_string("Pause ");
2884 if (collector_state()->during_initial_mark_pause()) {
2885 gc_string.append("Initial Mark");
2886 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2887 } else if (collector_state()->gcs_are_young()) {
2888 gc_string.append("Young");
2889 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2890 } else {
2891 gc_string.append("Mixed");
2892 verify_type = G1HeapVerifier::G1VerifyMixed;
2893 }
2894 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2895
2896 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2897 workers()->active_workers(),
2898 Threads::number_of_non_daemon_threads());
2899 workers()->update_active_workers(active_workers);
2900 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2901
2902 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2903 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2904
2905 // If the secondary_free_list is not empty, append it to the
2906 // free_list. No need to wait for the cleanup operation to finish;
2907 // the region allocation code will check the secondary_free_list
2908 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2909 // set, skip this step so that the region allocation code has to
2910 // get entries from the secondary_free_list.
2911 if (!G1StressConcRegionFreeing) {
2912 append_secondary_free_list_if_not_empty_with_lock();
2913 }
2914
2915 G1HeapTransition heap_transition(this);
2916 size_t heap_used_bytes_before_gc = used();
2917
2918 // Don't dynamically change the number of GC threads this early. A value of
2919 // 0 is used to indicate serial work. When parallel work is done,
2920 // it will be set.
2921
2922 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2923 IsGCActiveMark x;
2924
2925 gc_prologue(false);
2926
2927 if (VerifyRememberedSets) {
2928 log_info(gc, verify)("[Verifying RemSets before GC]");
2929 VerifyRegionRemSetClosure v_cl;
2930 heap_region_iterate(&v_cl);
2931 }
2932
2933 _verifier->verify_before_gc(verify_type);
2934
2935 _verifier->check_bitmaps("GC Start");
2936
2937 #if COMPILER2_OR_JVMCI
2938 DerivedPointerTable::clear();
2939 #endif
2940
2941 // Please see comment in g1CollectedHeap.hpp and
2942 // G1CollectedHeap::ref_processing_init() to see how
2943 // reference processing currently works in G1.
2944
2945 // Enable discovery in the STW reference processor
2946 if (g1_policy()->should_process_references()) {
2947 ref_processor_stw()->enable_discovery();
2948 } else {
2949 ref_processor_stw()->disable_discovery();
2950 }
2951
2952 {
2953 // We want to temporarily turn off discovery by the
2954 // CM ref processor, if necessary, and turn it back on
2955 // on again later if we do. Using a scoped
2956 // NoRefDiscovery object will do this.
2957 NoRefDiscovery no_cm_discovery(ref_processor_cm());
2958
2959 // Forget the current alloc region (we might even choose it to be part
2960 // of the collection set!).
2961 _allocator->release_mutator_alloc_region();
2962
2963 // This timing is only used by the ergonomics to handle our pause target.
2964 // It is unclear why this should not include the full pause. We will
2965 // investigate this in CR 7178365.
2966 //
2967 // Preserving the old comment here if that helps the investigation:
2968 //
2969 // The elapsed time induced by the start time below deliberately elides
2970 // the possible verification above.
2971 double sample_start_time_sec = os::elapsedTime();
2972
2973 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2974
2975 if (collector_state()->during_initial_mark_pause()) {
2976 concurrent_mark()->checkpoint_roots_initial_pre();
2977 }
2978
2979 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2980
2981 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2982
2983 // Make sure the remembered sets are up to date. This needs to be
2984 // done before register_humongous_regions_with_cset(), because the
2985 // remembered sets are used there to choose eager reclaim candidates.
2986 // If the remembered sets are not up to date we might miss some
2987 // entries that need to be handled.
2988 g1_rem_set()->cleanupHRRS();
2989
2990 register_humongous_regions_with_cset();
2991
2992 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2993
2994 // We call this after finalize_cset() to
2995 // ensure that the CSet has been finalized.
2996 _cm->verify_no_cset_oops();
2997
2998 if (_hr_printer.is_active()) {
2999 G1PrintCollectionSetClosure cl(&_hr_printer);
3000 _collection_set.iterate(&cl);
3001 }
3002
3003 // Initialize the GC alloc regions.
3004 _allocator->init_gc_alloc_regions(evacuation_info);
3005
3006 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3007 pre_evacuate_collection_set();
3008
3009 // Actually do the work...
3010 evacuate_collection_set(&per_thread_states);
3011
3012 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3013
3014 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3015 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3016
3017 eagerly_reclaim_humongous_regions();
3018
3019 record_obj_copy_mem_stats();
3020 _survivor_evac_stats.adjust_desired_plab_sz();
3021 _old_evac_stats.adjust_desired_plab_sz();
3022
3023 double start = os::elapsedTime();
3024 start_new_collection_set();
3025 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3026
3027 if (evacuation_failed()) {
3028 set_used(recalculate_used());
3029 if (_archive_allocator != NULL) {
3030 _archive_allocator->clear_used();
3031 }
3032 for (uint i = 0; i < ParallelGCThreads; i++) {
3033 if (_evacuation_failed_info_array[i].has_failed()) {
3034 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3035 }
3036 }
3037 } else {
3038 // The "used" of the the collection set have already been subtracted
3039 // when they were freed. Add in the bytes evacuated.
3040 increase_used(g1_policy()->bytes_copied_during_gc());
3041 }
3042
3043 if (collector_state()->during_initial_mark_pause()) {
3044 // We have to do this before we notify the CM threads that
3045 // they can start working to make sure that all the
3046 // appropriate initialization is done on the CM object.
3047 concurrent_mark()->checkpoint_roots_initial_post();
3048 collector_state()->set_mark_in_progress(true);
3049 // Note that we don't actually trigger the CM thread at
3050 // this point. We do that later when we're sure that
3051 // the current thread has completed its logging output.
3052 }
3053
3054 allocate_dummy_regions();
3055
3056 _allocator->init_mutator_alloc_region();
3057
3058 {
3059 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3060 if (expand_bytes > 0) {
3061 size_t bytes_before = capacity();
3062 // No need for an ergo logging here,
3063 // expansion_amount() does this when it returns a value > 0.
3064 double expand_ms;
3065 if (!expand(expand_bytes, _workers, &expand_ms)) {
3066 // We failed to expand the heap. Cannot do anything about it.
3067 }
3068 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3069 }
3070 }
3071
3072 // We redo the verification but now wrt to the new CSet which
3073 // has just got initialized after the previous CSet was freed.
3074 _cm->verify_no_cset_oops();
3075
3076 // This timing is only used by the ergonomics to handle our pause target.
3077 // It is unclear why this should not include the full pause. We will
3078 // investigate this in CR 7178365.
3079 double sample_end_time_sec = os::elapsedTime();
3080 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3081 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3082 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3083
3084 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3085 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3086
3087 if (VerifyRememberedSets) {
3088 log_info(gc, verify)("[Verifying RemSets after GC]");
3089 VerifyRegionRemSetClosure v_cl;
3090 heap_region_iterate(&v_cl);
3091 }
3092
3093 _verifier->verify_after_gc(verify_type);
3094 _verifier->check_bitmaps("GC End");
3095
3096 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3097 ref_processor_stw()->verify_no_references_recorded();
3098
3099 // CM reference discovery will be re-enabled if necessary.
3100 }
3101
3102 #ifdef TRACESPINNING
3103 ParallelTaskTerminator::print_termination_counts();
3104 #endif
3105
3106 gc_epilogue(false);
3107 }
3108
3109 // Print the remainder of the GC log output.
3110 if (evacuation_failed()) {
3111 log_info(gc)("To-space exhausted");
3112 }
3113
3114 g1_policy()->print_phases();
3115 heap_transition.print();
3116
3117 // It is not yet to safe to tell the concurrent mark to
3118 // start as we have some optional output below. We don't want the
3119 // output from the concurrent mark thread interfering with this
3120 // logging output either.
3121
3122 _hrm.verify_optional();
3123 _verifier->verify_region_sets_optional();
3124
3125 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3126 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3127
3128 print_heap_after_gc();
3129 print_heap_regions();
3130 trace_heap_after_gc(_gc_tracer_stw);
3131
3132 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3133 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3134 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3135 // before any GC notifications are raised.
3136 g1mm()->update_sizes();
3137
3138 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3139 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3140 _gc_timer_stw->register_gc_end();
3141 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3142 }
3143 // It should now be safe to tell the concurrent mark thread to start
3144 // without its logging output interfering with the logging output
3145 // that came from the pause.
3146
3147 if (should_start_conc_mark) {
3148 // CAUTION: after the doConcurrentMark() call below,
3149 // the concurrent marking thread(s) could be running
3150 // concurrently with us. Make sure that anything after
3151 // this point does not assume that we are the only GC thread
3152 // running. Note: of course, the actual marking work will
3153 // not start until the safepoint itself is released in
3154 // SuspendibleThreadSet::desynchronize().
3155 doConcurrentMark();
3156 }
3157
3158 return true;
3159 }
3160
3161 void G1CollectedHeap::remove_self_forwarding_pointers() {
3162 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3163 workers()->run_task(&rsfp_task);
3164 }
3165
3166 void G1CollectedHeap::restore_after_evac_failure() {
3167 double remove_self_forwards_start = os::elapsedTime();
3168
3169 remove_self_forwarding_pointers();
3170 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3171 _preserved_marks_set.restore(&task_executor);
3172
3173 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3174 }
3175
3176 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3177 if (!_evacuation_failed) {
3178 _evacuation_failed = true;
3179 }
3180
3181 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3182 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3183 }
3184
3185 bool G1ParEvacuateFollowersClosure::offer_termination() {
3186 G1ParScanThreadState* const pss = par_scan_state();
3187 start_term_time();
3188 const bool res = terminator()->offer_termination();
3189 end_term_time();
3190 return res;
3191 }
3192
3193 void G1ParEvacuateFollowersClosure::do_void() {
3194 G1ParScanThreadState* const pss = par_scan_state();
3195 pss->trim_queue();
3196 do {
3197 pss->steal_and_trim_queue(queues());
3198 } while (!offer_termination());
3199 }
3200
3201 class G1ParTask : public AbstractGangTask {
3202 protected:
3203 G1CollectedHeap* _g1h;
3204 G1ParScanThreadStateSet* _pss;
3205 RefToScanQueueSet* _queues;
3206 G1RootProcessor* _root_processor;
3207 ParallelTaskTerminator _terminator;
3208 uint _n_workers;
3209
3210 public:
3211 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3212 : AbstractGangTask("G1 collection"),
3213 _g1h(g1h),
3214 _pss(per_thread_states),
3215 _queues(task_queues),
3216 _root_processor(root_processor),
3217 _terminator(n_workers, _queues),
3218 _n_workers(n_workers)
3219 {}
3220
3221 void work(uint worker_id) {
3222 if (worker_id >= _n_workers) return; // no work needed this round
3223
3224 double start_sec = os::elapsedTime();
3225 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3226
3227 {
3228 ResourceMark rm;
3229 HandleMark hm;
3230
3231 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3232
3233 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3234 pss->set_ref_processor(rp);
3235
3236 double start_strong_roots_sec = os::elapsedTime();
3237
3238 _root_processor->evacuate_roots(pss->closures(), worker_id);
3239
3240 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3241 // treating the nmethods visited to act as roots for concurrent marking.
3242 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3243 // objects copied by the current evacuation.
3244 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3245 pss->closures()->weak_codeblobs(),
3246 worker_id);
3247
3248 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3249
3250 double term_sec = 0.0;
3251 size_t evac_term_attempts = 0;
3252 {
3253 double start = os::elapsedTime();
3254 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3255 evac.do_void();
3256
3257 evac_term_attempts = evac.term_attempts();
3258 term_sec = evac.term_time();
3259 double elapsed_sec = os::elapsedTime() - start;
3260 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3261 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3262 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3263 }
3264
3265 assert(pss->queue_is_empty(), "should be empty");
3266
3267 if (log_is_enabled(Debug, gc, task, stats)) {
3268 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3269 size_t lab_waste;
3270 size_t lab_undo_waste;
3271 pss->waste(lab_waste, lab_undo_waste);
3272 _g1h->print_termination_stats(worker_id,
3273 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3274 strong_roots_sec * 1000.0, /* strong roots time */
3275 term_sec * 1000.0, /* evac term time */
3276 evac_term_attempts, /* evac term attempts */
3277 lab_waste, /* alloc buffer waste */
3278 lab_undo_waste /* undo waste */
3279 );
3280 }
3281
3282 // Close the inner scope so that the ResourceMark and HandleMark
3283 // destructors are executed here and are included as part of the
3284 // "GC Worker Time".
3285 }
3286 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3287 }
3288 };
3289
3290 void G1CollectedHeap::print_termination_stats_hdr() {
3291 log_debug(gc, task, stats)("GC Termination Stats");
3292 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3293 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3294 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3295 }
3296
3297 void G1CollectedHeap::print_termination_stats(uint worker_id,
3298 double elapsed_ms,
3299 double strong_roots_ms,
3300 double term_ms,
3301 size_t term_attempts,
3302 size_t alloc_buffer_waste,
3303 size_t undo_waste) const {
3304 log_debug(gc, task, stats)
3305 ("%3d %9.2f %9.2f %6.2f "
3306 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3307 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3308 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3309 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3310 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3311 alloc_buffer_waste * HeapWordSize / K,
3312 undo_waste * HeapWordSize / K);
3313 }
3314
3315 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3316 private:
3317 BoolObjectClosure* _is_alive;
3318 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3319
3320 int _initial_string_table_size;
3321 int _initial_symbol_table_size;
3322
3323 bool _process_strings;
3324 int _strings_processed;
3325 int _strings_removed;
3326
3327 bool _process_symbols;
3328 int _symbols_processed;
3329 int _symbols_removed;
3330
3331 bool _process_string_dedup;
3332
3333 public:
3334 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3335 AbstractGangTask("String/Symbol Unlinking"),
3336 _is_alive(is_alive),
3337 _dedup_closure(is_alive, NULL, false),
3338 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3339 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3340 _process_string_dedup(process_string_dedup) {
3341
3342 _initial_string_table_size = StringTable::the_table()->table_size();
3343 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3344 if (process_strings) {
3345 StringTable::clear_parallel_claimed_index();
3346 }
3347 if (process_symbols) {
3348 SymbolTable::clear_parallel_claimed_index();
3349 }
3350 }
3351
3352 ~G1StringAndSymbolCleaningTask() {
3353 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3354 "claim value %d after unlink less than initial string table size %d",
3355 StringTable::parallel_claimed_index(), _initial_string_table_size);
3356 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3357 "claim value %d after unlink less than initial symbol table size %d",
3358 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3359
3360 log_info(gc, stringtable)(
3361 "Cleaned string and symbol table, "
3362 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3363 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3364 strings_processed(), strings_removed(),
3365 symbols_processed(), symbols_removed());
3366 }
3367
3368 void work(uint worker_id) {
3369 int strings_processed = 0;
3370 int strings_removed = 0;
3371 int symbols_processed = 0;
3372 int symbols_removed = 0;
3373 if (_process_strings) {
3374 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3375 Atomic::add(strings_processed, &_strings_processed);
3376 Atomic::add(strings_removed, &_strings_removed);
3377 }
3378 if (_process_symbols) {
3379 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3380 Atomic::add(symbols_processed, &_symbols_processed);
3381 Atomic::add(symbols_removed, &_symbols_removed);
3382 }
3383 if (_process_string_dedup) {
3384 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3385 }
3386 }
3387
3388 size_t strings_processed() const { return (size_t)_strings_processed; }
3389 size_t strings_removed() const { return (size_t)_strings_removed; }
3390
3391 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3392 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3393 };
3394
3395 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3396 private:
3397 static Monitor* _lock;
3398
3399 BoolObjectClosure* const _is_alive;
3400 const bool _unloading_occurred;
3401 const uint _num_workers;
3402
3403 // Variables used to claim nmethods.
3404 CompiledMethod* _first_nmethod;
3405 CompiledMethod* volatile _claimed_nmethod;
3406
3407 // The list of nmethods that need to be processed by the second pass.
3408 CompiledMethod* volatile _postponed_list;
3409 volatile uint _num_entered_barrier;
3410
3411 public:
3412 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3413 _is_alive(is_alive),
3414 _unloading_occurred(unloading_occurred),
3415 _num_workers(num_workers),
3416 _first_nmethod(NULL),
3417 _claimed_nmethod(NULL),
3418 _postponed_list(NULL),
3419 _num_entered_barrier(0)
3420 {
3421 CompiledMethod::increase_unloading_clock();
3422 // Get first alive nmethod
3423 CompiledMethodIterator iter = CompiledMethodIterator();
3424 if(iter.next_alive()) {
3425 _first_nmethod = iter.method();
3426 }
3427 _claimed_nmethod = _first_nmethod;
3428 }
3429
3430 ~G1CodeCacheUnloadingTask() {
3431 CodeCache::verify_clean_inline_caches();
3432
3433 CodeCache::set_needs_cache_clean(false);
3434 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3435
3436 CodeCache::verify_icholder_relocations();
3437 }
3438
3439 private:
3440 void add_to_postponed_list(CompiledMethod* nm) {
3441 CompiledMethod* old;
3442 do {
3443 old = _postponed_list;
3444 nm->set_unloading_next(old);
3445 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3446 }
3447
3448 void clean_nmethod(CompiledMethod* nm) {
3449 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3450
3451 if (postponed) {
3452 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3453 add_to_postponed_list(nm);
3454 }
3455
3456 // Mark that this thread has been cleaned/unloaded.
3457 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3458 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3459 }
3460
3461 void clean_nmethod_postponed(CompiledMethod* nm) {
3462 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3463 }
3464
3465 static const int MaxClaimNmethods = 16;
3466
3467 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3468 CompiledMethod* first;
3469 CompiledMethodIterator last;
3470
3471 do {
3472 *num_claimed_nmethods = 0;
3473
3474 first = _claimed_nmethod;
3475 last = CompiledMethodIterator(first);
3476
3477 if (first != NULL) {
3478
3479 for (int i = 0; i < MaxClaimNmethods; i++) {
3480 if (!last.next_alive()) {
3481 break;
3482 }
3483 claimed_nmethods[i] = last.method();
3484 (*num_claimed_nmethods)++;
3485 }
3486 }
3487
3488 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3489 }
3490
3491 CompiledMethod* claim_postponed_nmethod() {
3492 CompiledMethod* claim;
3493 CompiledMethod* next;
3494
3495 do {
3496 claim = _postponed_list;
3497 if (claim == NULL) {
3498 return NULL;
3499 }
3500
3501 next = claim->unloading_next();
3502
3503 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3504
3505 return claim;
3506 }
3507
3508 public:
3509 // Mark that we're done with the first pass of nmethod cleaning.
3510 void barrier_mark(uint worker_id) {
3511 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3512 _num_entered_barrier++;
3513 if (_num_entered_barrier == _num_workers) {
3514 ml.notify_all();
3515 }
3516 }
3517
3518 // See if we have to wait for the other workers to
3519 // finish their first-pass nmethod cleaning work.
3520 void barrier_wait(uint worker_id) {
3521 if (_num_entered_barrier < _num_workers) {
3522 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3523 while (_num_entered_barrier < _num_workers) {
3524 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3525 }
3526 }
3527 }
3528
3529 // Cleaning and unloading of nmethods. Some work has to be postponed
3530 // to the second pass, when we know which nmethods survive.
3531 void work_first_pass(uint worker_id) {
3532 // The first nmethods is claimed by the first worker.
3533 if (worker_id == 0 && _first_nmethod != NULL) {
3534 clean_nmethod(_first_nmethod);
3535 _first_nmethod = NULL;
3536 }
3537
3538 int num_claimed_nmethods;
3539 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3540
3541 while (true) {
3542 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3543
3544 if (num_claimed_nmethods == 0) {
3545 break;
3546 }
3547
3548 for (int i = 0; i < num_claimed_nmethods; i++) {
3549 clean_nmethod(claimed_nmethods[i]);
3550 }
3551 }
3552 }
3553
3554 void work_second_pass(uint worker_id) {
3555 CompiledMethod* nm;
3556 // Take care of postponed nmethods.
3557 while ((nm = claim_postponed_nmethod()) != NULL) {
3558 clean_nmethod_postponed(nm);
3559 }
3560 }
3561 };
3562
3563 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3564
3565 class G1KlassCleaningTask : public StackObj {
3566 BoolObjectClosure* _is_alive;
3567 volatile int _clean_klass_tree_claimed;
3568 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3569
3570 public:
3571 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3572 _is_alive(is_alive),
3573 _clean_klass_tree_claimed(0),
3574 _klass_iterator() {
3575 }
3576
3577 private:
3578 bool claim_clean_klass_tree_task() {
3579 if (_clean_klass_tree_claimed) {
3580 return false;
3581 }
3582
3583 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3584 }
3585
3586 InstanceKlass* claim_next_klass() {
3587 Klass* klass;
3588 do {
3589 klass =_klass_iterator.next_klass();
3590 } while (klass != NULL && !klass->is_instance_klass());
3591
3592 // this can be null so don't call InstanceKlass::cast
3593 return static_cast<InstanceKlass*>(klass);
3594 }
3595
3596 public:
3597
3598 void clean_klass(InstanceKlass* ik) {
3599 ik->clean_weak_instanceklass_links(_is_alive);
3600 }
3601
3602 void work() {
3603 ResourceMark rm;
3604
3605 // One worker will clean the subklass/sibling klass tree.
3606 if (claim_clean_klass_tree_task()) {
3607 Klass::clean_subklass_tree(_is_alive);
3608 }
3609
3610 // All workers will help cleaning the classes,
3611 InstanceKlass* klass;
3612 while ((klass = claim_next_klass()) != NULL) {
3613 clean_klass(klass);
3614 }
3615 }
3616 };
3617
3618 class G1ResolvedMethodCleaningTask : public StackObj {
3619 BoolObjectClosure* _is_alive;
3620 volatile int _resolved_method_task_claimed;
3621 public:
3622 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3623 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3624
3625 bool claim_resolved_method_task() {
3626 if (_resolved_method_task_claimed) {
3627 return false;
3628 }
3629 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3630 }
3631
3632 // These aren't big, one thread can do it all.
3633 void work() {
3634 if (claim_resolved_method_task()) {
3635 ResolvedMethodTable::unlink(_is_alive);
3636 }
3637 }
3638 };
3639
3640
3641 // To minimize the remark pause times, the tasks below are done in parallel.
3642 class G1ParallelCleaningTask : public AbstractGangTask {
3643 private:
3644 G1StringAndSymbolCleaningTask _string_symbol_task;
3645 G1CodeCacheUnloadingTask _code_cache_task;
3646 G1KlassCleaningTask _klass_cleaning_task;
3647 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3648
3649 public:
3650 // The constructor is run in the VMThread.
3651 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3652 AbstractGangTask("Parallel Cleaning"),
3653 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3654 _code_cache_task(num_workers, is_alive, unloading_occurred),
3655 _klass_cleaning_task(is_alive),
3656 _resolved_method_cleaning_task(is_alive) {
3657 }
3658
3659 // The parallel work done by all worker threads.
3660 void work(uint worker_id) {
3661 // Do first pass of code cache cleaning.
3662 _code_cache_task.work_first_pass(worker_id);
3663
3664 // Let the threads mark that the first pass is done.
3665 _code_cache_task.barrier_mark(worker_id);
3666
3667 // Clean the Strings and Symbols.
3668 _string_symbol_task.work(worker_id);
3669
3670 // Clean unreferenced things in the ResolvedMethodTable
3671 _resolved_method_cleaning_task.work();
3672
3673 // Wait for all workers to finish the first code cache cleaning pass.
3674 _code_cache_task.barrier_wait(worker_id);
3675
3676 // Do the second code cache cleaning work, which realize on
3677 // the liveness information gathered during the first pass.
3678 _code_cache_task.work_second_pass(worker_id);
3679
3680 // Clean all klasses that were not unloaded.
3681 _klass_cleaning_task.work();
3682 }
3683 };
3684
3685
3686 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3687 bool class_unloading_occurred) {
3688 uint n_workers = workers()->active_workers();
3689
3690 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3691 workers()->run_task(&g1_unlink_task);
3692 }
3693
3694 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3695 bool process_strings,
3696 bool process_symbols,
3697 bool process_string_dedup) {
3698 if (!process_strings && !process_symbols && !process_string_dedup) {
3699 // Nothing to clean.
3700 return;
3701 }
3702
3703 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3704 workers()->run_task(&g1_unlink_task);
3705
3706 }
3707
3708 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3709 private:
3710 DirtyCardQueueSet* _queue;
3711 G1CollectedHeap* _g1h;
3712 public:
3713 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3714 _queue(queue), _g1h(g1h) { }
3715
3716 virtual void work(uint worker_id) {
3717 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3718 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3719
3720 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3721 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3722
3723 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3724 }
3725 };
3726
3727 void G1CollectedHeap::redirty_logged_cards() {
3728 double redirty_logged_cards_start = os::elapsedTime();
3729
3730 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3731 dirty_card_queue_set().reset_for_par_iteration();
3732 workers()->run_task(&redirty_task);
3733
3734 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3735 dcq.merge_bufferlists(&dirty_card_queue_set());
3736 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3737
3738 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3739 }
3740
3741 // Weak Reference Processing support
3742
3743 // An always "is_alive" closure that is used to preserve referents.
3744 // If the object is non-null then it's alive. Used in the preservation
3745 // of referent objects that are pointed to by reference objects
3746 // discovered by the CM ref processor.
3747 class G1AlwaysAliveClosure: public BoolObjectClosure {
3748 G1CollectedHeap* _g1;
3749 public:
3750 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3751 bool do_object_b(oop p) {
3752 if (p != NULL) {
3753 return true;
3754 }
3755 return false;
3756 }
3757 };
3758
3759 bool G1STWIsAliveClosure::do_object_b(oop p) {
3760 // An object is reachable if it is outside the collection set,
3761 // or is inside and copied.
3762 return !_g1->is_in_cset(p) || p->is_forwarded();
3763 }
3764
3765 // Non Copying Keep Alive closure
3766 class G1KeepAliveClosure: public OopClosure {
3767 G1CollectedHeap* _g1;
3768 public:
3769 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3770 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3771 void do_oop(oop* p) {
3772 oop obj = *p;
3773 assert(obj != NULL, "the caller should have filtered out NULL values");
3774
3775 const InCSetState cset_state = _g1->in_cset_state(obj);
3776 if (!cset_state.is_in_cset_or_humongous()) {
3777 return;
3778 }
3779 if (cset_state.is_in_cset()) {
3780 assert( obj->is_forwarded(), "invariant" );
3781 *p = obj->forwardee();
3782 } else {
3783 assert(!obj->is_forwarded(), "invariant" );
3784 assert(cset_state.is_humongous(),
3785 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3786 _g1->set_humongous_is_live(obj);
3787 }
3788 }
3789 };
3790
3791 // Copying Keep Alive closure - can be called from both
3792 // serial and parallel code as long as different worker
3793 // threads utilize different G1ParScanThreadState instances
3794 // and different queues.
3795
3796 class G1CopyingKeepAliveClosure: public OopClosure {
3797 G1CollectedHeap* _g1h;
3798 OopClosure* _copy_non_heap_obj_cl;
3799 G1ParScanThreadState* _par_scan_state;
3800
3801 public:
3802 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3803 OopClosure* non_heap_obj_cl,
3804 G1ParScanThreadState* pss):
3805 _g1h(g1h),
3806 _copy_non_heap_obj_cl(non_heap_obj_cl),
3807 _par_scan_state(pss)
3808 {}
3809
3810 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3811 virtual void do_oop( oop* p) { do_oop_work(p); }
3812
3813 template <class T> void do_oop_work(T* p) {
3814 oop obj = oopDesc::load_decode_heap_oop(p);
3815
3816 if (_g1h->is_in_cset_or_humongous(obj)) {
3817 // If the referent object has been forwarded (either copied
3818 // to a new location or to itself in the event of an
3819 // evacuation failure) then we need to update the reference
3820 // field and, if both reference and referent are in the G1
3821 // heap, update the RSet for the referent.
3822 //
3823 // If the referent has not been forwarded then we have to keep
3824 // it alive by policy. Therefore we have copy the referent.
3825 //
3826 // If the reference field is in the G1 heap then we can push
3827 // on the PSS queue. When the queue is drained (after each
3828 // phase of reference processing) the object and it's followers
3829 // will be copied, the reference field set to point to the
3830 // new location, and the RSet updated. Otherwise we need to
3831 // use the the non-heap or metadata closures directly to copy
3832 // the referent object and update the pointer, while avoiding
3833 // updating the RSet.
3834
3835 if (_g1h->is_in_g1_reserved(p)) {
3836 _par_scan_state->push_on_queue(p);
3837 } else {
3838 assert(!Metaspace::contains((const void*)p),
3839 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3840 _copy_non_heap_obj_cl->do_oop(p);
3841 }
3842 }
3843 }
3844 };
3845
3846 // Serial drain queue closure. Called as the 'complete_gc'
3847 // closure for each discovered list in some of the
3848 // reference processing phases.
3849
3850 class G1STWDrainQueueClosure: public VoidClosure {
3851 protected:
3852 G1CollectedHeap* _g1h;
3853 G1ParScanThreadState* _par_scan_state;
3854
3855 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3856
3857 public:
3858 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3859 _g1h(g1h),
3860 _par_scan_state(pss)
3861 { }
3862
3863 void do_void() {
3864 G1ParScanThreadState* const pss = par_scan_state();
3865 pss->trim_queue();
3866 }
3867 };
3868
3869 // Parallel Reference Processing closures
3870
3871 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3872 // processing during G1 evacuation pauses.
3873
3874 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3875 private:
3876 G1CollectedHeap* _g1h;
3877 G1ParScanThreadStateSet* _pss;
3878 RefToScanQueueSet* _queues;
3879 WorkGang* _workers;
3880 uint _active_workers;
3881
3882 public:
3883 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3884 G1ParScanThreadStateSet* per_thread_states,
3885 WorkGang* workers,
3886 RefToScanQueueSet *task_queues,
3887 uint n_workers) :
3888 _g1h(g1h),
3889 _pss(per_thread_states),
3890 _queues(task_queues),
3891 _workers(workers),
3892 _active_workers(n_workers)
3893 {
3894 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3895 }
3896
3897 // Executes the given task using concurrent marking worker threads.
3898 virtual void execute(ProcessTask& task);
3899 virtual void execute(EnqueueTask& task);
3900 };
3901
3902 // Gang task for possibly parallel reference processing
3903
3904 class G1STWRefProcTaskProxy: public AbstractGangTask {
3905 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3906 ProcessTask& _proc_task;
3907 G1CollectedHeap* _g1h;
3908 G1ParScanThreadStateSet* _pss;
3909 RefToScanQueueSet* _task_queues;
3910 ParallelTaskTerminator* _terminator;
3911
3912 public:
3913 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3914 G1CollectedHeap* g1h,
3915 G1ParScanThreadStateSet* per_thread_states,
3916 RefToScanQueueSet *task_queues,
3917 ParallelTaskTerminator* terminator) :
3918 AbstractGangTask("Process reference objects in parallel"),
3919 _proc_task(proc_task),
3920 _g1h(g1h),
3921 _pss(per_thread_states),
3922 _task_queues(task_queues),
3923 _terminator(terminator)
3924 {}
3925
3926 virtual void work(uint worker_id) {
3927 // The reference processing task executed by a single worker.
3928 ResourceMark rm;
3929 HandleMark hm;
3930
3931 G1STWIsAliveClosure is_alive(_g1h);
3932
3933 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3934 pss->set_ref_processor(NULL);
3935
3936 // Keep alive closure.
3937 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3938
3939 // Complete GC closure
3940 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3941
3942 // Call the reference processing task's work routine.
3943 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3944
3945 // Note we cannot assert that the refs array is empty here as not all
3946 // of the processing tasks (specifically phase2 - pp2_work) execute
3947 // the complete_gc closure (which ordinarily would drain the queue) so
3948 // the queue may not be empty.
3949 }
3950 };
3951
3952 // Driver routine for parallel reference processing.
3953 // Creates an instance of the ref processing gang
3954 // task and has the worker threads execute it.
3955 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3956 assert(_workers != NULL, "Need parallel worker threads.");
3957
3958 ParallelTaskTerminator terminator(_active_workers, _queues);
3959 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3960
3961 _workers->run_task(&proc_task_proxy);
3962 }
3963
3964 // Gang task for parallel reference enqueueing.
3965
3966 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3967 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3968 EnqueueTask& _enq_task;
3969
3970 public:
3971 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3972 AbstractGangTask("Enqueue reference objects in parallel"),
3973 _enq_task(enq_task)
3974 { }
3975
3976 virtual void work(uint worker_id) {
3977 _enq_task.work(worker_id);
3978 }
3979 };
3980
3981 // Driver routine for parallel reference enqueueing.
3982 // Creates an instance of the ref enqueueing gang
3983 // task and has the worker threads execute it.
3984
3985 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
3986 assert(_workers != NULL, "Need parallel worker threads.");
3987
3988 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
3989
3990 _workers->run_task(&enq_task_proxy);
3991 }
3992
3993 // End of weak reference support closures
3994
3995 // Abstract task used to preserve (i.e. copy) any referent objects
3996 // that are in the collection set and are pointed to by reference
3997 // objects discovered by the CM ref processor.
3998
3999 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4000 protected:
4001 G1CollectedHeap* _g1h;
4002 G1ParScanThreadStateSet* _pss;
4003 RefToScanQueueSet* _queues;
4004 ParallelTaskTerminator _terminator;
4005 uint _n_workers;
4006
4007 public:
4008 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4009 AbstractGangTask("ParPreserveCMReferents"),
4010 _g1h(g1h),
4011 _pss(per_thread_states),
4012 _queues(task_queues),
4013 _terminator(workers, _queues),
4014 _n_workers(workers)
4015 {
4016 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4017 }
4018
4019 void work(uint worker_id) {
4020 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4021
4022 ResourceMark rm;
4023 HandleMark hm;
4024
4025 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4026 pss->set_ref_processor(NULL);
4027 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4028
4029 // Is alive closure
4030 G1AlwaysAliveClosure always_alive(_g1h);
4031
4032 // Copying keep alive closure. Applied to referent objects that need
4033 // to be copied.
4034 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4035
4036 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4037
4038 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4039 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4040
4041 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4042 // So this must be true - but assert just in case someone decides to
4043 // change the worker ids.
4044 assert(worker_id < limit, "sanity");
4045 assert(!rp->discovery_is_atomic(), "check this code");
4046
4047 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4048 for (uint idx = worker_id; idx < limit; idx += stride) {
4049 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4050
4051 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4052 while (iter.has_next()) {
4053 // Since discovery is not atomic for the CM ref processor, we
4054 // can see some null referent objects.
4055 iter.load_ptrs(DEBUG_ONLY(true));
4056 oop ref = iter.obj();
4057
4058 // This will filter nulls.
4059 if (iter.is_referent_alive()) {
4060 iter.make_referent_alive();
4061 }
4062 iter.move_to_next();
4063 }
4064 }
4065
4066 // Drain the queue - which may cause stealing
4067 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4068 drain_queue.do_void();
4069 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4070 assert(pss->queue_is_empty(), "should be");
4071 }
4072 };
4073
4074 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4075 // Any reference objects, in the collection set, that were 'discovered'
4076 // by the CM ref processor should have already been copied (either by
4077 // applying the external root copy closure to the discovered lists, or
4078 // by following an RSet entry).
4079 //
4080 // But some of the referents, that are in the collection set, that these
4081 // reference objects point to may not have been copied: the STW ref
4082 // processor would have seen that the reference object had already
4083 // been 'discovered' and would have skipped discovering the reference,
4084 // but would not have treated the reference object as a regular oop.
4085 // As a result the copy closure would not have been applied to the
4086 // referent object.
4087 //
4088 // We need to explicitly copy these referent objects - the references
4089 // will be processed at the end of remarking.
4090 //
4091 // We also need to do this copying before we process the reference
4092 // objects discovered by the STW ref processor in case one of these
4093 // referents points to another object which is also referenced by an
4094 // object discovered by the STW ref processor.
4095 double preserve_cm_referents_time = 0.0;
4096
4097 // To avoid spawning task when there is no work to do, check that
4098 // a concurrent cycle is active and that some references have been
4099 // discovered.
4100 if (concurrent_mark()->cm_thread()->during_cycle() &&
4101 ref_processor_cm()->has_discovered_references()) {
4102 double preserve_cm_referents_start = os::elapsedTime();
4103 uint no_of_gc_workers = workers()->active_workers();
4104 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4105 per_thread_states,
4106 no_of_gc_workers,
4107 _task_queues);
4108 workers()->run_task(&keep_cm_referents);
4109 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4110 }
4111
4112 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4113 }
4114
4115 // Weak Reference processing during an evacuation pause (part 1).
4116 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4117 double ref_proc_start = os::elapsedTime();
4118
4119 ReferenceProcessor* rp = _ref_processor_stw;
4120 assert(rp->discovery_enabled(), "should have been enabled");
4121
4122 // Closure to test whether a referent is alive.
4123 G1STWIsAliveClosure is_alive(this);
4124
4125 // Even when parallel reference processing is enabled, the processing
4126 // of JNI refs is serial and performed serially by the current thread
4127 // rather than by a worker. The following PSS will be used for processing
4128 // JNI refs.
4129
4130 // Use only a single queue for this PSS.
4131 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4132 pss->set_ref_processor(NULL);
4133 assert(pss->queue_is_empty(), "pre-condition");
4134
4135 // Keep alive closure.
4136 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4137
4138 // Serial Complete GC closure
4139 G1STWDrainQueueClosure drain_queue(this, pss);
4140
4141 // Setup the soft refs policy...
4142 rp->setup_policy(false);
4143
4144 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4145
4146 ReferenceProcessorStats stats;
4147 if (!rp->processing_is_mt()) {
4148 // Serial reference processing...
4149 stats = rp->process_discovered_references(&is_alive,
4150 &keep_alive,
4151 &drain_queue,
4152 NULL,
4153 pt);
4154 } else {
4155 uint no_of_gc_workers = workers()->active_workers();
4156
4157 // Parallel reference processing
4158 assert(no_of_gc_workers <= rp->max_num_q(),
4159 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4160 no_of_gc_workers, rp->max_num_q());
4161
4162 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4163 stats = rp->process_discovered_references(&is_alive,
4164 &keep_alive,
4165 &drain_queue,
4166 &par_task_executor,
4167 pt);
4168 }
4169
4170 _gc_tracer_stw->report_gc_reference_stats(stats);
4171
4172 // We have completed copying any necessary live referent objects.
4173 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4174
4175 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4176 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4177 }
4178
4179 // Weak Reference processing during an evacuation pause (part 2).
4180 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4181 double ref_enq_start = os::elapsedTime();
4182
4183 ReferenceProcessor* rp = _ref_processor_stw;
4184 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4185
4186 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4187
4188 // Now enqueue any remaining on the discovered lists on to
4189 // the pending list.
4190 if (!rp->processing_is_mt()) {
4191 // Serial reference processing...
4192 rp->enqueue_discovered_references(NULL, pt);
4193 } else {
4194 // Parallel reference enqueueing
4195
4196 uint n_workers = workers()->active_workers();
4197
4198 assert(n_workers <= rp->max_num_q(),
4199 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4200 n_workers, rp->max_num_q());
4201
4202 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4203 rp->enqueue_discovered_references(&par_task_executor, pt);
4204 }
4205
4206 rp->verify_no_references_recorded();
4207 assert(!rp->discovery_enabled(), "should have been disabled");
4208
4209 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4210 // ensure that it is marked in the bitmap for concurrent marking to discover.
4211 if (collector_state()->during_initial_mark_pause()) {
4212 oop pll_head = Universe::reference_pending_list();
4213 if (pll_head != NULL) {
4214 _cm->mark_in_next_bitmap(pll_head);
4215 }
4216 }
4217
4218 // FIXME
4219 // CM's reference processing also cleans up the string and symbol tables.
4220 // Should we do that here also? We could, but it is a serial operation
4221 // and could significantly increase the pause time.
4222
4223 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4224 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4225 }
4226
4227 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4228 double merge_pss_time_start = os::elapsedTime();
4229 per_thread_states->flush();
4230 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4231 }
4232
4233 void G1CollectedHeap::pre_evacuate_collection_set() {
4234 _expand_heap_after_alloc_failure = true;
4235 _evacuation_failed = false;
4236
4237 // Disable the hot card cache.
4238 _hot_card_cache->reset_hot_cache_claimed_index();
4239 _hot_card_cache->set_use_cache(false);
4240
4241 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4242 _preserved_marks_set.assert_empty();
4243
4244 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4245
4246 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4247 if (collector_state()->during_initial_mark_pause()) {
4248 double start_clear_claimed_marks = os::elapsedTime();
4249
4250 ClassLoaderDataGraph::clear_claimed_marks();
4251
4252 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4253 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4254 }
4255 }
4256
4257 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
4258 // Should G1EvacuationFailureALot be in effect for this GC?
4259 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4260
4261 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4262
4263 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4264
4265 double start_par_time_sec = os::elapsedTime();
4266 double end_par_time_sec;
4267
4268 {
4269 const uint n_workers = workers()->active_workers();
4270 G1RootProcessor root_processor(this, n_workers);
4271 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4272
4273 print_termination_stats_hdr();
4274
4275 workers()->run_task(&g1_par_task);
4276 end_par_time_sec = os::elapsedTime();
4277
4278 // Closing the inner scope will execute the destructor
4279 // for the G1RootProcessor object. We record the current
4280 // elapsed time before closing the scope so that time
4281 // taken for the destructor is NOT included in the
4282 // reported parallel time.
4283 }
4284
4285 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4286 phase_times->record_par_time(par_time_ms);
4287
4288 double code_root_fixup_time_ms =
4289 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4290 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4291 }
4292
4293 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4294 // Process any discovered reference objects - we have
4295 // to do this _before_ we retire the GC alloc regions
4296 // as we may have to copy some 'reachable' referent
4297 // objects (and their reachable sub-graphs) that were
4298 // not copied during the pause.
4299 if (g1_policy()->should_process_references()) {
4300 preserve_cm_referents(per_thread_states);
4301 process_discovered_references(per_thread_states);
4302 } else {
4303 ref_processor_stw()->verify_no_references_recorded();
4304 }
4305
4306 G1STWIsAliveClosure is_alive(this);
4307 G1KeepAliveClosure keep_alive(this);
4308
4309 {
4310 double start = os::elapsedTime();
4311
4312 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4313
4314 double time_ms = (os::elapsedTime() - start) * 1000.0;
4315 g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4316 }
4317
4318 if (G1StringDedup::is_enabled()) {
4319 double fixup_start = os::elapsedTime();
4320
4321 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4322
4323 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4324 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4325 }
4326
4327 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4328
4329 if (evacuation_failed()) {
4330 restore_after_evac_failure();
4331
4332 // Reset the G1EvacuationFailureALot counters and flags
4333 // Note: the values are reset only when an actual
4334 // evacuation failure occurs.
4335 NOT_PRODUCT(reset_evacuation_should_fail();)
4336 }
4337
4338 _preserved_marks_set.assert_empty();
4339
4340 // Enqueue any remaining references remaining on the STW
4341 // reference processor's discovered lists. We need to do
4342 // this after the card table is cleaned (and verified) as
4343 // the act of enqueueing entries on to the pending list
4344 // will log these updates (and dirty their associated
4345 // cards). We need these updates logged to update any
4346 // RSets.
4347 if (g1_policy()->should_process_references()) {
4348 enqueue_discovered_references(per_thread_states);
4349 } else {
4350 g1_policy()->phase_times()->record_ref_enq_time(0);
4351 }
4352
4353 _allocator->release_gc_alloc_regions(evacuation_info);
4354
4355 merge_per_thread_state_info(per_thread_states);
4356
4357 // Reset and re-enable the hot card cache.
4358 // Note the counts for the cards in the regions in the
4359 // collection set are reset when the collection set is freed.
4360 _hot_card_cache->reset_hot_cache();
4361 _hot_card_cache->set_use_cache(true);
4362
4363 purge_code_root_memory();
4364
4365 redirty_logged_cards();
4366 #if COMPILER2_OR_JVMCI
4367 double start = os::elapsedTime();
4368 DerivedPointerTable::update_pointers();
4369 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4370 #endif
4371 g1_policy()->print_age_table();
4372 }
4373
4374 void G1CollectedHeap::record_obj_copy_mem_stats() {
4375 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4376
4377 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4378 create_g1_evac_summary(&_old_evac_stats));
4379 }
4380
4381 void G1CollectedHeap::free_region(HeapRegion* hr,
4382 FreeRegionList* free_list,
4383 bool skip_remset,
4384 bool skip_hot_card_cache,
4385 bool locked) {
4386 assert(!hr->is_free(), "the region should not be free");
4387 assert(!hr->is_empty(), "the region should not be empty");
4388 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4389 assert(free_list != NULL, "pre-condition");
4390
4391 if (G1VerifyBitmaps) {
4392 MemRegion mr(hr->bottom(), hr->end());
4393 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4394 }
4395
4396 // Clear the card counts for this region.
4397 // Note: we only need to do this if the region is not young
4398 // (since we don't refine cards in young regions).
4399 if (!skip_hot_card_cache && !hr->is_young()) {
4400 _hot_card_cache->reset_card_counts(hr);
4401 }
4402 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4403 free_list->add_ordered(hr);
4404 }
4405
4406 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4407 FreeRegionList* free_list,
4408 bool skip_remset) {
4409 assert(hr->is_humongous(), "this is only for humongous regions");
4410 assert(free_list != NULL, "pre-condition");
4411 hr->clear_humongous();
4412 free_region(hr, free_list, skip_remset);
4413 }
4414
4415 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4416 const uint humongous_regions_removed) {
4417 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4418 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4419 _old_set.bulk_remove(old_regions_removed);
4420 _humongous_set.bulk_remove(humongous_regions_removed);
4421 }
4422
4423 }
4424
4425 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4426 assert(list != NULL, "list can't be null");
4427 if (!list->is_empty()) {
4428 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4429 _hrm.insert_list_into_free_list(list);
4430 }
4431 }
4432
4433 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4434 decrease_used(bytes);
4435 }
4436
4437 class G1ParScrubRemSetTask: public AbstractGangTask {
4438 protected:
4439 G1RemSet* _g1rs;
4440 HeapRegionClaimer _hrclaimer;
4441
4442 public:
4443 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4444 AbstractGangTask("G1 ScrubRS"),
4445 _g1rs(g1_rs),
4446 _hrclaimer(num_workers) {
4447 }
4448
4449 void work(uint worker_id) {
4450 _g1rs->scrub(worker_id, &_hrclaimer);
4451 }
4452 };
4453
4454 void G1CollectedHeap::scrub_rem_set() {
4455 uint num_workers = workers()->active_workers();
4456 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4457 workers()->run_task(&g1_par_scrub_rs_task);
4458 }
4459
4460 class G1FreeCollectionSetTask : public AbstractGangTask {
4461 private:
4462
4463 // Closure applied to all regions in the collection set to do work that needs to
4464 // be done serially in a single thread.
4465 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4466 private:
4467 EvacuationInfo* _evacuation_info;
4468 const size_t* _surviving_young_words;
4469
4470 // Bytes used in successfully evacuated regions before the evacuation.
4471 size_t _before_used_bytes;
4472 // Bytes used in unsucessfully evacuated regions before the evacuation
4473 size_t _after_used_bytes;
4474
4475 size_t _bytes_allocated_in_old_since_last_gc;
4476
4477 size_t _failure_used_words;
4478 size_t _failure_waste_words;
4479
4480 FreeRegionList _local_free_list;
4481 public:
4482 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4483 HeapRegionClosure(),
4484 _evacuation_info(evacuation_info),
4485 _surviving_young_words(surviving_young_words),
4486 _before_used_bytes(0),
4487 _after_used_bytes(0),
4488 _bytes_allocated_in_old_since_last_gc(0),
4489 _failure_used_words(0),
4490 _failure_waste_words(0),
4491 _local_free_list("Local Region List for CSet Freeing") {
4492 }
4493
4494 virtual bool do_heap_region(HeapRegion* r) {
4495 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4496
4497 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4498 g1h->clear_in_cset(r);
4499
4500 if (r->is_young()) {
4501 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4502 "Young index %d is wrong for region %u of type %s with %u young regions",
4503 r->young_index_in_cset(),
4504 r->hrm_index(),
4505 r->get_type_str(),
4506 g1h->collection_set()->young_region_length());
4507 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4508 r->record_surv_words_in_group(words_survived);
4509 }
4510
4511 if (!r->evacuation_failed()) {
4512 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4513 _before_used_bytes += r->used();
4514 g1h->free_region(r,
4515 &_local_free_list,
4516 true, /* skip_remset */
4517 true, /* skip_hot_card_cache */
4518 true /* locked */);
4519 } else {
4520 r->uninstall_surv_rate_group();
4521 r->set_young_index_in_cset(-1);
4522 r->set_evacuation_failed(false);
4523 // When moving a young gen region to old gen, we "allocate" that whole region
4524 // there. This is in addition to any already evacuated objects. Notify the
4525 // policy about that.
4526 // Old gen regions do not cause an additional allocation: both the objects
4527 // still in the region and the ones already moved are accounted for elsewhere.
4528 if (r->is_young()) {
4529 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4530 }
4531 // The region is now considered to be old.
4532 r->set_old();
4533 // Do some allocation statistics accounting. Regions that failed evacuation
4534 // are always made old, so there is no need to update anything in the young
4535 // gen statistics, but we need to update old gen statistics.
4536 size_t used_words = r->marked_bytes() / HeapWordSize;
4537
4538 _failure_used_words += used_words;
4539 _failure_waste_words += HeapRegion::GrainWords - used_words;
4540
4541 g1h->old_set_add(r);
4542 _after_used_bytes += r->used();
4543 }
4544 return false;
4545 }
4546
4547 void complete_work() {
4548 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4549
4550 _evacuation_info->set_regions_freed(_local_free_list.length());
4551 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4552
4553 g1h->prepend_to_freelist(&_local_free_list);
4554 g1h->decrement_summary_bytes(_before_used_bytes);
4555
4556 G1Policy* policy = g1h->g1_policy();
4557 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4558
4559 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4560 }
4561 };
4562
4563 G1CollectionSet* _collection_set;
4564 G1SerialFreeCollectionSetClosure _cl;
4565 const size_t* _surviving_young_words;
4566
4567 size_t _rs_lengths;
4568
4569 volatile jint _serial_work_claim;
4570
4571 struct WorkItem {
4572 uint region_idx;
4573 bool is_young;
4574 bool evacuation_failed;
4575
4576 WorkItem(HeapRegion* r) {
4577 region_idx = r->hrm_index();
4578 is_young = r->is_young();
4579 evacuation_failed = r->evacuation_failed();
4580 }
4581 };
4582
4583 volatile size_t _parallel_work_claim;
4584 size_t _num_work_items;
4585 WorkItem* _work_items;
4586
4587 void do_serial_work() {
4588 // Need to grab the lock to be allowed to modify the old region list.
4589 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4590 _collection_set->iterate(&_cl);
4591 }
4592
4593 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4594 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4595
4596 HeapRegion* r = g1h->region_at(region_idx);
4597 assert(!g1h->is_on_master_free_list(r), "sanity");
4598
4599 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4600
4601 if (!is_young) {
4602 g1h->_hot_card_cache->reset_card_counts(r);
4603 }
4604
4605 if (!evacuation_failed) {
4606 r->rem_set()->clear_locked();
4607 }
4608 }
4609
4610 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4611 private:
4612 size_t _cur_idx;
4613 WorkItem* _work_items;
4614 public:
4615 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4616
4617 virtual bool do_heap_region(HeapRegion* r) {
4618 _work_items[_cur_idx++] = WorkItem(r);
4619 return false;
4620 }
4621 };
4622
4623 void prepare_work() {
4624 G1PrepareFreeCollectionSetClosure cl(_work_items);
4625 _collection_set->iterate(&cl);
4626 }
4627
4628 void complete_work() {
4629 _cl.complete_work();
4630
4631 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4632 policy->record_max_rs_lengths(_rs_lengths);
4633 policy->cset_regions_freed();
4634 }
4635 public:
4636 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4637 AbstractGangTask("G1 Free Collection Set"),
4638 _cl(evacuation_info, surviving_young_words),
4639 _collection_set(collection_set),
4640 _surviving_young_words(surviving_young_words),
4641 _serial_work_claim(0),
4642 _rs_lengths(0),
4643 _parallel_work_claim(0),
4644 _num_work_items(collection_set->region_length()),
4645 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4646 prepare_work();
4647 }
4648
4649 ~G1FreeCollectionSetTask() {
4650 complete_work();
4651 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4652 }
4653
4654 // Chunk size for work distribution. The chosen value has been determined experimentally
4655 // to be a good tradeoff between overhead and achievable parallelism.
4656 static uint chunk_size() { return 32; }
4657
4658 virtual void work(uint worker_id) {
4659 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4660
4661 // Claim serial work.
4662 if (_serial_work_claim == 0) {
4663 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4664 if (value == 0) {
4665 double serial_time = os::elapsedTime();
4666 do_serial_work();
4667 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4668 }
4669 }
4670
4671 // Start parallel work.
4672 double young_time = 0.0;
4673 bool has_young_time = false;
4674 double non_young_time = 0.0;
4675 bool has_non_young_time = false;
4676
4677 while (true) {
4678 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4679 size_t cur = end - chunk_size();
4680
4681 if (cur >= _num_work_items) {
4682 break;
4683 }
4684
4685 double start_time = os::elapsedTime();
4686
4687 end = MIN2(end, _num_work_items);
4688
4689 for (; cur < end; cur++) {
4690 bool is_young = _work_items[cur].is_young;
4691
4692 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4693
4694 double end_time = os::elapsedTime();
4695 double time_taken = end_time - start_time;
4696 if (is_young) {
4697 young_time += time_taken;
4698 has_young_time = true;
4699 } else {
4700 non_young_time += time_taken;
4701 has_non_young_time = true;
4702 }
4703 start_time = end_time;
4704 }
4705 }
4706
4707 if (has_young_time) {
4708 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4709 }
4710 if (has_non_young_time) {
4711 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4712 }
4713 }
4714 };
4715
4716 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4717 _eden.clear();
4718
4719 double free_cset_start_time = os::elapsedTime();
4720
4721 {
4722 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4723 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4724
4725 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4726
4727 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4728 cl.name(),
4729 num_workers,
4730 _collection_set.region_length());
4731 workers()->run_task(&cl, num_workers);
4732 }
4733 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4734
4735 collection_set->clear();
4736 }
4737
4738 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4739 private:
4740 FreeRegionList* _free_region_list;
4741 HeapRegionSet* _proxy_set;
4742 uint _humongous_objects_reclaimed;
4743 uint _humongous_regions_reclaimed;
4744 size_t _freed_bytes;
4745 public:
4746
4747 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4748 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4749 }
4750
4751 virtual bool do_heap_region(HeapRegion* r) {
4752 if (!r->is_starts_humongous()) {
4753 return false;
4754 }
4755
4756 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4757
4758 oop obj = (oop)r->bottom();
4759 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4760
4761 // The following checks whether the humongous object is live are sufficient.
4762 // The main additional check (in addition to having a reference from the roots
4763 // or the young gen) is whether the humongous object has a remembered set entry.
4764 //
4765 // A humongous object cannot be live if there is no remembered set for it
4766 // because:
4767 // - there can be no references from within humongous starts regions referencing
4768 // the object because we never allocate other objects into them.
4769 // (I.e. there are no intra-region references that may be missed by the
4770 // remembered set)
4771 // - as soon there is a remembered set entry to the humongous starts region
4772 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4773 // until the end of a concurrent mark.
4774 //
4775 // It is not required to check whether the object has been found dead by marking
4776 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4777 // all objects allocated during that time are considered live.
4778 // SATB marking is even more conservative than the remembered set.
4779 // So if at this point in the collection there is no remembered set entry,
4780 // nobody has a reference to it.
4781 // At the start of collection we flush all refinement logs, and remembered sets
4782 // are completely up-to-date wrt to references to the humongous object.
4783 //
4784 // Other implementation considerations:
4785 // - never consider object arrays at this time because they would pose
4786 // considerable effort for cleaning up the the remembered sets. This is
4787 // required because stale remembered sets might reference locations that
4788 // are currently allocated into.
4789 uint region_idx = r->hrm_index();
4790 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4791 !r->rem_set()->is_empty()) {
4792 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",
4793 region_idx,
4794 (size_t)obj->size() * HeapWordSize,
4795 p2i(r->bottom()),
4796 r->rem_set()->occupied(),
4797 r->rem_set()->strong_code_roots_list_length(),
4798 next_bitmap->is_marked(r->bottom()),
4799 g1h->is_humongous_reclaim_candidate(region_idx),
4800 obj->is_typeArray()
4801 );
4802 return false;
4803 }
4804
4805 guarantee(obj->is_typeArray(),
4806 "Only eagerly reclaiming type arrays is supported, but the object "
4807 PTR_FORMAT " is not.", p2i(r->bottom()));
4808
4809 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",
4810 region_idx,
4811 (size_t)obj->size() * HeapWordSize,
4812 p2i(r->bottom()),
4813 r->rem_set()->occupied(),
4814 r->rem_set()->strong_code_roots_list_length(),
4815 next_bitmap->is_marked(r->bottom()),
4816 g1h->is_humongous_reclaim_candidate(region_idx),
4817 obj->is_typeArray()
4818 );
4819
4820 // Need to clear mark bit of the humongous object if already set.
4821 if (next_bitmap->is_marked(r->bottom())) {
4822 next_bitmap->clear(r->bottom());
4823 }
4824 _humongous_objects_reclaimed++;
4825 do {
4826 HeapRegion* next = g1h->next_region_in_humongous(r);
4827 _freed_bytes += r->used();
4828 r->set_containing_set(NULL);
4829 _humongous_regions_reclaimed++;
4830 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4831 r = next;
4832 } while (r != NULL);
4833
4834 return false;
4835 }
4836
4837 uint humongous_objects_reclaimed() {
4838 return _humongous_objects_reclaimed;
4839 }
4840
4841 uint humongous_regions_reclaimed() {
4842 return _humongous_regions_reclaimed;
4843 }
4844
4845 size_t bytes_freed() const {
4846 return _freed_bytes;
4847 }
4848 };
4849
4850 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4851 assert_at_safepoint_on_vm_thread();
4852
4853 if (!G1EagerReclaimHumongousObjects ||
4854 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4855 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4856 return;
4857 }
4858
4859 double start_time = os::elapsedTime();
4860
4861 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4862
4863 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4864 heap_region_iterate(&cl);
4865
4866 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4867
4868 G1HRPrinter* hrp = hr_printer();
4869 if (hrp->is_active()) {
4870 FreeRegionListIterator iter(&local_cleanup_list);
4871 while (iter.more_available()) {
4872 HeapRegion* hr = iter.get_next();
4873 hrp->cleanup(hr);
4874 }
4875 }
4876
4877 prepend_to_freelist(&local_cleanup_list);
4878 decrement_summary_bytes(cl.bytes_freed());
4879
4880 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4881 cl.humongous_objects_reclaimed());
4882 }
4883
4884 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4885 public:
4886 virtual bool do_heap_region(HeapRegion* r) {
4887 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4888 G1CollectedHeap::heap()->clear_in_cset(r);
4889 r->set_young_index_in_cset(-1);
4890 return false;
4891 }
4892 };
4893
4894 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4895 G1AbandonCollectionSetClosure cl;
4896 collection_set->iterate(&cl);
4897
4898 collection_set->clear();
4899 collection_set->stop_incremental_building();
4900 }
4901
4902 void G1CollectedHeap::set_free_regions_coming() {
4903 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4904
4905 assert(!free_regions_coming(), "pre-condition");
4906 _free_regions_coming = true;
4907 }
4908
4909 void G1CollectedHeap::reset_free_regions_coming() {
4910 assert(free_regions_coming(), "pre-condition");
4911
4912 {
4913 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4914 _free_regions_coming = false;
4915 SecondaryFreeList_lock->notify_all();
4916 }
4917
4918 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4919 }
4920
4921 void G1CollectedHeap::wait_while_free_regions_coming() {
4922 // Most of the time we won't have to wait, so let's do a quick test
4923 // first before we take the lock.
4924 if (!free_regions_coming()) {
4925 return;
4926 }
4927
4928 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4929
4930 {
4931 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4932 while (free_regions_coming()) {
4933 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4934 }
4935 }
4936
4937 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4938 }
4939
4940 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4941 return _allocator->is_retained_old_region(hr);
4942 }
4943
4944 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4945 _eden.add(hr);
4946 _g1_policy->set_region_eden(hr);
4947 }
4948
4949 #ifdef ASSERT
4950
4951 class NoYoungRegionsClosure: public HeapRegionClosure {
4952 private:
4953 bool _success;
4954 public:
4955 NoYoungRegionsClosure() : _success(true) { }
4956 bool do_heap_region(HeapRegion* r) {
4957 if (r->is_young()) {
4958 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4959 p2i(r->bottom()), p2i(r->end()));
4960 _success = false;
4961 }
4962 return false;
4963 }
4964 bool success() { return _success; }
4965 };
4966
4967 bool G1CollectedHeap::check_young_list_empty() {
4968 bool ret = (young_regions_count() == 0);
4969
4970 NoYoungRegionsClosure closure;
4971 heap_region_iterate(&closure);
4972 ret = ret && closure.success();
4973
4974 return ret;
4975 }
4976
4977 #endif // ASSERT
4978
4979 class TearDownRegionSetsClosure : public HeapRegionClosure {
4980 private:
4981 HeapRegionSet *_old_set;
4982
4983 public:
4984 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4985
4986 bool do_heap_region(HeapRegion* r) {
4987 if (r->is_old()) {
4988 _old_set->remove(r);
4989 } else if(r->is_young()) {
4990 r->uninstall_surv_rate_group();
4991 } else {
4992 // We ignore free regions, we'll empty the free list afterwards.
4993 // We ignore humongous regions, we're not tearing down the
4994 // humongous regions set.
4995 assert(r->is_free() || r->is_humongous(),
4996 "it cannot be another type");
4997 }
4998 return false;
4999 }
5000
5001 ~TearDownRegionSetsClosure() {
5002 assert(_old_set->is_empty(), "post-condition");
5003 }
5004 };
5005
5006 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5007 assert_at_safepoint_on_vm_thread();
5008
5009 if (!free_list_only) {
5010 TearDownRegionSetsClosure cl(&_old_set);
5011 heap_region_iterate(&cl);
5012
5013 // Note that emptying the _young_list is postponed and instead done as
5014 // the first step when rebuilding the regions sets again. The reason for
5015 // this is that during a full GC string deduplication needs to know if
5016 // a collected region was young or old when the full GC was initiated.
5017 }
5018 _hrm.remove_all_free_regions();
5019 }
5020
5021 void G1CollectedHeap::increase_used(size_t bytes) {
5022 _summary_bytes_used += bytes;
5023 }
5024
5025 void G1CollectedHeap::decrease_used(size_t bytes) {
5026 assert(_summary_bytes_used >= bytes,
5027 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5028 _summary_bytes_used, bytes);
5029 _summary_bytes_used -= bytes;
5030 }
5031
5032 void G1CollectedHeap::set_used(size_t bytes) {
5033 _summary_bytes_used = bytes;
5034 }
5035
5036 class RebuildRegionSetsClosure : public HeapRegionClosure {
5037 private:
5038 bool _free_list_only;
5039 HeapRegionSet* _old_set;
5040 HeapRegionManager* _hrm;
5041 size_t _total_used;
5042
5043 public:
5044 RebuildRegionSetsClosure(bool free_list_only,
5045 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5046 _free_list_only(free_list_only),
5047 _old_set(old_set), _hrm(hrm), _total_used(0) {
5048 assert(_hrm->num_free_regions() == 0, "pre-condition");
5049 if (!free_list_only) {
5050 assert(_old_set->is_empty(), "pre-condition");
5051 }
5052 }
5053
5054 bool do_heap_region(HeapRegion* r) {
5055 if (r->is_empty()) {
5056 // Add free regions to the free list
5057 r->set_free();
5058 _hrm->insert_into_free_list(r);
5059 } else if (!_free_list_only) {
5060
5061 if (r->is_humongous()) {
5062 // We ignore humongous regions. We left the humongous set unchanged.
5063 } else {
5064 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5065 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5066 r->move_to_old();
5067 _old_set->add(r);
5068 }
5069 _total_used += r->used();
5070 }
5071
5072 return false;
5073 }
5074
5075 size_t total_used() {
5076 return _total_used;
5077 }
5078 };
5079
5080 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5081 assert_at_safepoint_on_vm_thread();
5082
5083 if (!free_list_only) {
5084 _eden.clear();
5085 _survivor.clear();
5086 }
5087
5088 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5089 heap_region_iterate(&cl);
5090
5091 if (!free_list_only) {
5092 set_used(cl.total_used());
5093 if (_archive_allocator != NULL) {
5094 _archive_allocator->clear_used();
5095 }
5096 }
5097 assert(used_unlocked() == recalculate_used(),
5098 "inconsistent used_unlocked(), "
5099 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5100 used_unlocked(), recalculate_used());
5101 }
5102
5103 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5104 HeapRegion* hr = heap_region_containing(p);
5105 return hr->is_in(p);
5106 }
5107
5108 // Methods for the mutator alloc region
5109
5110 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5111 bool force) {
5112 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5113 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5114 if (force || should_allocate) {
5115 HeapRegion* new_alloc_region = new_region(word_size,
5116 false /* is_old */,
5117 false /* do_expand */);
5118 if (new_alloc_region != NULL) {
5119 set_region_short_lived_locked(new_alloc_region);
5120 _hr_printer.alloc(new_alloc_region, !should_allocate);
5121 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5122 return new_alloc_region;
5123 }
5124 }
5125 return NULL;
5126 }
5127
5128 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5129 size_t allocated_bytes) {
5130 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5131 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5132
5133 collection_set()->add_eden_region(alloc_region);
5134 increase_used(allocated_bytes);
5135 _hr_printer.retire(alloc_region);
5136 // We update the eden sizes here, when the region is retired,
5137 // instead of when it's allocated, since this is the point that its
5138 // used space has been recored in _summary_bytes_used.
5139 g1mm()->update_eden_size();
5140 }
5141
5142 // Methods for the GC alloc regions
5143
5144 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5145 if (dest.is_old()) {
5146 return true;
5147 } else {
5148 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5149 }
5150 }
5151
5152 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5153 assert(FreeList_lock->owned_by_self(), "pre-condition");
5154
5155 if (!has_more_regions(dest)) {
5156 return NULL;
5157 }
5158
5159 const bool is_survivor = dest.is_young();
5160
5161 HeapRegion* new_alloc_region = new_region(word_size,
5162 !is_survivor,
5163 true /* do_expand */);
5164 if (new_alloc_region != NULL) {
5165 // We really only need to do this for old regions given that we
5166 // should never scan survivors. But it doesn't hurt to do it
5167 // for survivors too.
5168 new_alloc_region->record_timestamp();
5169 if (is_survivor) {
5170 new_alloc_region->set_survivor();
5171 _survivor.add(new_alloc_region);
5172 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5173 } else {
5174 new_alloc_region->set_old();
5175 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5176 }
5177 _hr_printer.alloc(new_alloc_region);
5178 bool during_im = collector_state()->during_initial_mark_pause();
5179 new_alloc_region->note_start_of_copying(during_im);
5180 return new_alloc_region;
5181 }
5182 return NULL;
5183 }
5184
5185 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5186 size_t allocated_bytes,
5187 InCSetState dest) {
5188 bool during_im = collector_state()->during_initial_mark_pause();
5189 alloc_region->note_end_of_copying(during_im);
5190 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5191 if (dest.is_old()) {
5192 _old_set.add(alloc_region);
5193 }
5194 _hr_printer.retire(alloc_region);
5195 }
5196
5197 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5198 bool expanded = false;
5199 uint index = _hrm.find_highest_free(&expanded);
5200
5201 if (index != G1_NO_HRM_INDEX) {
5202 if (expanded) {
5203 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5204 HeapRegion::GrainWords * HeapWordSize);
5205 }
5206 _hrm.allocate_free_regions_starting_at(index, 1);
5207 return region_at(index);
5208 }
5209 return NULL;
5210 }
5211
5212 // Optimized nmethod scanning
5213
5214 class RegisterNMethodOopClosure: public OopClosure {
5215 G1CollectedHeap* _g1h;
5216 nmethod* _nm;
5217
5218 template <class T> void do_oop_work(T* p) {
5219 T heap_oop = oopDesc::load_heap_oop(p);
5220 if (!oopDesc::is_null(heap_oop)) {
5221 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5222 HeapRegion* hr = _g1h->heap_region_containing(obj);
5223 assert(!hr->is_continues_humongous(),
5224 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5225 " starting at " HR_FORMAT,
5226 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5227
5228 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5229 hr->add_strong_code_root_locked(_nm);
5230 }
5231 }
5232
5233 public:
5234 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5235 _g1h(g1h), _nm(nm) {}
5236
5237 void do_oop(oop* p) { do_oop_work(p); }
5238 void do_oop(narrowOop* p) { do_oop_work(p); }
5239 };
5240
5241 class UnregisterNMethodOopClosure: public OopClosure {
5242 G1CollectedHeap* _g1h;
5243 nmethod* _nm;
5244
5245 template <class T> void do_oop_work(T* p) {
5246 T heap_oop = oopDesc::load_heap_oop(p);
5247 if (!oopDesc::is_null(heap_oop)) {
5248 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5249 HeapRegion* hr = _g1h->heap_region_containing(obj);
5250 assert(!hr->is_continues_humongous(),
5251 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5252 " starting at " HR_FORMAT,
5253 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5254
5255 hr->remove_strong_code_root(_nm);
5256 }
5257 }
5258
5259 public:
5260 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5261 _g1h(g1h), _nm(nm) {}
5262
5263 void do_oop(oop* p) { do_oop_work(p); }
5264 void do_oop(narrowOop* p) { do_oop_work(p); }
5265 };
5266
5267 // Returns true if the reference points to an object that
5268 // can move in an incremental collection.
5269 bool G1CollectedHeap::is_scavengable(oop obj) {
5270 HeapRegion* hr = heap_region_containing(obj);
5271 return !hr->is_pinned();
5272 }
5273
5274 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5275 guarantee(nm != NULL, "sanity");
5276 RegisterNMethodOopClosure reg_cl(this, nm);
5277 nm->oops_do(®_cl);
5278 }
5279
5280 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5281 guarantee(nm != NULL, "sanity");
5282 UnregisterNMethodOopClosure reg_cl(this, nm);
5283 nm->oops_do(®_cl, true);
5284 }
5285
5286 void G1CollectedHeap::purge_code_root_memory() {
5287 double purge_start = os::elapsedTime();
5288 G1CodeRootSet::purge();
5289 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5290 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5291 }
5292
5293 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5294 G1CollectedHeap* _g1h;
5295
5296 public:
5297 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5298 _g1h(g1h) {}
5299
5300 void do_code_blob(CodeBlob* cb) {
5301 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5302 if (nm == NULL) {
5303 return;
5304 }
5305
5306 if (ScavengeRootsInCode) {
5307 _g1h->register_nmethod(nm);
5308 }
5309 }
5310 };
5311
5312 void G1CollectedHeap::rebuild_strong_code_roots() {
5313 RebuildStrongCodeRootClosure blob_cl(this);
5314 CodeCache::blobs_do(&blob_cl);
5315 }
5316
5317 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5318 GrowableArray<GCMemoryManager*> memory_managers(2);
5319 memory_managers.append(&_memory_manager);
5320 memory_managers.append(&_full_gc_memory_manager);
5321 return memory_managers;
5322 }
5323
5324 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5325 GrowableArray<MemoryPool*> memory_pools(3);
5326 memory_pools.append(_eden_pool);
5327 memory_pools.append(_survivor_pool);
5328 memory_pools.append(_old_pool);
5329 return memory_pools;
5330 }