1 /*
2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentMarkThread.inline.hpp"
33 #include "gc/g1/g1Allocator.inline.hpp"
34 #include "gc/g1/g1CollectedHeap.inline.hpp"
35 #include "gc/g1/g1CollectionSet.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1MemoryPool.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1StringDedup.hpp"
56 #include "gc/g1/g1YCTypes.hpp"
57 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
58 #include "gc/g1/heapRegion.inline.hpp"
59 #include "gc/g1/heapRegionRemSet.hpp"
60 #include "gc/g1/heapRegionSet.inline.hpp"
61 #include "gc/g1/vm_operations_g1.hpp"
62 #include "gc/shared/adaptiveSizePolicy.hpp"
63 #include "gc/shared/gcHeapSummary.hpp"
64 #include "gc/shared/gcId.hpp"
65 #include "gc/shared/gcLocker.inline.hpp"
66 #include "gc/shared/gcTimer.hpp"
67 #include "gc/shared/gcTrace.hpp"
68 #include "gc/shared/gcTraceTime.inline.hpp"
69 #include "gc/shared/generationSpec.hpp"
70 #include "gc/shared/isGCActiveMark.hpp"
71 #include "gc/shared/preservedMarks.inline.hpp"
72 #include "gc/shared/suspendibleThreadSet.hpp"
73 #include "gc/shared/referenceProcessor.inline.hpp"
74 #include "gc/shared/taskqueue.inline.hpp"
75 #include "gc/shared/weakProcessor.hpp"
76 #include "logging/log.hpp"
77 #include "memory/allocation.hpp"
78 #include "memory/iterator.hpp"
79 #include "memory/resourceArea.hpp"
80 #include "oops/access.inline.hpp"
81 #include "oops/compressedOops.inline.hpp"
82 #include "oops/oop.inline.hpp"
83 #include "prims/resolvedMethodTable.hpp"
84 #include "runtime/atomic.hpp"
85 #include "runtime/handles.inline.hpp"
86 #include "runtime/init.hpp"
87 #include "runtime/orderAccess.inline.hpp"
88 #include "runtime/threadSMR.hpp"
89 #include "runtime/vmThread.hpp"
90 #include "utilities/align.hpp"
91 #include "utilities/globalDefinitions.hpp"
92 #include "utilities/stack.inline.hpp"
93
94 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
95
96 // INVARIANTS/NOTES
97 //
98 // All allocation activity covered by the G1CollectedHeap interface is
99 // serialized by acquiring the HeapLock. This happens in mem_allocate
100 // and allocate_new_tlab, which are the "entry" points to the
101 // allocation code from the rest of the JVM. (Note that this does not
102 // apply to TLAB allocation, which is not part of this interface: it
103 // is done by clients of this interface.)
104
105 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
106 private:
107 size_t _num_dirtied;
108 G1CollectedHeap* _g1h;
109 G1CardTable* _g1_ct;
110
111 HeapRegion* region_for_card(jbyte* card_ptr) const {
112 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
113 }
114
115 bool will_become_free(HeapRegion* hr) const {
116 // A region will be freed by free_collection_set if the region is in the
117 // collection set and has not had an evacuation failure.
118 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
119 }
120
121 public:
122 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
123 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
124
125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
126 HeapRegion* hr = region_for_card(card_ptr);
127
128 // Should only dirty cards in regions that won't be freed.
129 if (!will_become_free(hr)) {
130 *card_ptr = G1CardTable::dirty_card_val();
131 _num_dirtied++;
132 }
133
134 return true;
135 }
136
137 size_t num_dirtied() const { return _num_dirtied; }
138 };
139
140
141 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
142 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
143 }
144
145 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
146 // The from card cache is not the memory that is actually committed. So we cannot
147 // take advantage of the zero_filled parameter.
148 reset_from_card_cache(start_idx, num_regions);
149 }
150
151
152 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
153 MemRegion mr) {
154 return new HeapRegion(hrs_index, bot(), mr);
155 }
156
157 // Private methods.
158
159 HeapRegion*
160 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
161 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
162 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
163 if (!_secondary_free_list.is_empty()) {
164 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
165 "secondary_free_list has %u entries",
166 _secondary_free_list.length());
167 // It looks as if there are free regions available on the
168 // secondary_free_list. Let's move them to the free_list and try
169 // again to allocate from it.
170 append_secondary_free_list();
171
172 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
173 "empty we should have moved at least one entry to the free_list");
174 HeapRegion* res = _hrm.allocate_free_region(is_old);
175 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
176 "allocated " HR_FORMAT " from secondary_free_list",
177 HR_FORMAT_PARAMS(res));
178 return res;
179 }
180
181 // Wait here until we get notified either when (a) there are no
182 // more free regions coming or (b) some regions have been moved on
183 // the secondary_free_list.
184 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
185 }
186
187 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
188 "could not allocate from secondary_free_list");
189 return NULL;
190 }
191
192 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
193 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
194 "the only time we use this to allocate a humongous region is "
195 "when we are allocating a single humongous region");
196
197 HeapRegion* res;
198 if (G1StressConcRegionFreeing) {
199 if (!_secondary_free_list.is_empty()) {
200 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
201 "forced to look at the secondary_free_list");
202 res = new_region_try_secondary_free_list(is_old);
203 if (res != NULL) {
204 return res;
205 }
206 }
207 }
208
209 res = _hrm.allocate_free_region(is_old);
210
211 if (res == NULL) {
212 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
213 "res == NULL, trying the secondary_free_list");
214 res = new_region_try_secondary_free_list(is_old);
215 }
216 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
217 // Currently, only attempts to allocate GC alloc regions set
218 // do_expand to true. So, we should only reach here during a
219 // safepoint. If this assumption changes we might have to
220 // reconsider the use of _expand_heap_after_alloc_failure.
221 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
222
223 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
224 word_size * HeapWordSize);
225
226 if (expand(word_size * HeapWordSize)) {
227 // Given that expand() succeeded in expanding the heap, and we
228 // always expand the heap by an amount aligned to the heap
229 // region size, the free list should in theory not be empty.
230 // In either case allocate_free_region() will check for NULL.
231 res = _hrm.allocate_free_region(is_old);
232 } else {
233 _expand_heap_after_alloc_failure = false;
234 }
235 }
236 return res;
237 }
238
239 HeapWord*
240 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
241 uint num_regions,
242 size_t word_size) {
243 assert(first != G1_NO_HRM_INDEX, "pre-condition");
244 assert(is_humongous(word_size), "word_size should be humongous");
245 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
246
247 // Index of last region in the series.
248 uint last = first + num_regions - 1;
249
250 // We need to initialize the region(s) we just discovered. This is
251 // a bit tricky given that it can happen concurrently with
252 // refinement threads refining cards on these regions and
253 // potentially wanting to refine the BOT as they are scanning
254 // those cards (this can happen shortly after a cleanup; see CR
255 // 6991377). So we have to set up the region(s) carefully and in
256 // a specific order.
257
258 // The word size sum of all the regions we will allocate.
259 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
260 assert(word_size <= word_size_sum, "sanity");
261
262 // This will be the "starts humongous" region.
263 HeapRegion* first_hr = region_at(first);
264 // The header of the new object will be placed at the bottom of
265 // the first region.
266 HeapWord* new_obj = first_hr->bottom();
267 // This will be the new top of the new object.
268 HeapWord* obj_top = new_obj + word_size;
269
270 // First, we need to zero the header of the space that we will be
271 // allocating. When we update top further down, some refinement
272 // threads might try to scan the region. By zeroing the header we
273 // ensure that any thread that will try to scan the region will
274 // come across the zero klass word and bail out.
275 //
276 // NOTE: It would not have been correct to have used
277 // CollectedHeap::fill_with_object() and make the space look like
278 // an int array. The thread that is doing the allocation will
279 // later update the object header to a potentially different array
280 // type and, for a very short period of time, the klass and length
281 // fields will be inconsistent. This could cause a refinement
282 // thread to calculate the object size incorrectly.
283 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
284
285 // Next, pad out the unused tail of the last region with filler
286 // objects, for improved usage accounting.
287 // How many words we use for filler objects.
288 size_t word_fill_size = word_size_sum - word_size;
289
290 // How many words memory we "waste" which cannot hold a filler object.
291 size_t words_not_fillable = 0;
292
293 if (word_fill_size >= min_fill_size()) {
294 fill_with_objects(obj_top, word_fill_size);
295 } else if (word_fill_size > 0) {
296 // We have space to fill, but we cannot fit an object there.
297 words_not_fillable = word_fill_size;
298 word_fill_size = 0;
299 }
300
301 // We will set up the first region as "starts humongous". This
302 // will also update the BOT covering all the regions to reflect
303 // that there is a single object that starts at the bottom of the
304 // first region.
305 first_hr->set_starts_humongous(obj_top, word_fill_size);
306 // Then, if there are any, we will set up the "continues
307 // humongous" regions.
308 HeapRegion* hr = NULL;
309 for (uint i = first + 1; i <= last; ++i) {
310 hr = region_at(i);
311 hr->set_continues_humongous(first_hr);
312 }
313
314 // Up to this point no concurrent thread would have been able to
315 // do any scanning on any region in this series. All the top
316 // fields still point to bottom, so the intersection between
317 // [bottom,top] and [card_start,card_end] will be empty. Before we
318 // update the top fields, we'll do a storestore to make sure that
319 // no thread sees the update to top before the zeroing of the
320 // object header and the BOT initialization.
321 OrderAccess::storestore();
322
323 // Now, we will update the top fields of the "continues humongous"
324 // regions except the last one.
325 for (uint i = first; i < last; ++i) {
326 hr = region_at(i);
327 hr->set_top(hr->end());
328 }
329
330 hr = region_at(last);
331 // If we cannot fit a filler object, we must set top to the end
332 // of the humongous object, otherwise we cannot iterate the heap
333 // and the BOT will not be complete.
334 hr->set_top(hr->end() - words_not_fillable);
335
336 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
337 "obj_top should be in last region");
338
339 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
340
341 assert(words_not_fillable == 0 ||
342 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
343 "Miscalculation in humongous allocation");
344
345 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
346
347 for (uint i = first; i <= last; ++i) {
348 hr = region_at(i);
349 _humongous_set.add(hr);
350 _hr_printer.alloc(hr);
351 }
352
353 return new_obj;
354 }
355
356 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
357 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
358 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
359 }
360
361 // If could fit into free regions w/o expansion, try.
362 // Otherwise, if can expand, do so.
363 // Otherwise, if using ex regions might help, try with ex given back.
364 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
365 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
366
367 _verifier->verify_region_sets_optional();
368
369 uint first = G1_NO_HRM_INDEX;
370 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
371
372 if (obj_regions == 1) {
373 // Only one region to allocate, try to use a fast path by directly allocating
374 // from the free lists. Do not try to expand here, we will potentially do that
375 // later.
376 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
377 if (hr != NULL) {
378 first = hr->hrm_index();
379 }
380 } else {
381 // We can't allocate humongous regions spanning more than one region while
382 // cleanupComplete() is running, since some of the regions we find to be
383 // empty might not yet be added to the free list. It is not straightforward
384 // to know in which list they are on so that we can remove them. We only
385 // need to do this if we need to allocate more than one region to satisfy the
386 // current humongous allocation request. If we are only allocating one region
387 // we use the one-region region allocation code (see above), that already
388 // potentially waits for regions from the secondary free list.
389 wait_while_free_regions_coming();
390 append_secondary_free_list_if_not_empty_with_lock();
391
392 // Policy: Try only empty regions (i.e. already committed first). Maybe we
393 // are lucky enough to find some.
394 first = _hrm.find_contiguous_only_empty(obj_regions);
395 if (first != G1_NO_HRM_INDEX) {
396 _hrm.allocate_free_regions_starting_at(first, obj_regions);
397 }
398 }
399
400 if (first == G1_NO_HRM_INDEX) {
401 // Policy: We could not find enough regions for the humongous object in the
402 // free list. Look through the heap to find a mix of free and uncommitted regions.
403 // If so, try expansion.
404 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
405 if (first != G1_NO_HRM_INDEX) {
406 // We found something. Make sure these regions are committed, i.e. expand
407 // the heap. Alternatively we could do a defragmentation GC.
408 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
409 word_size * HeapWordSize);
410
411 _hrm.expand_at(first, obj_regions, workers());
412 g1_policy()->record_new_heap_size(num_regions());
413
414 #ifdef ASSERT
415 for (uint i = first; i < first + obj_regions; ++i) {
416 HeapRegion* hr = region_at(i);
417 assert(hr->is_free(), "sanity");
418 assert(hr->is_empty(), "sanity");
419 assert(is_on_master_free_list(hr), "sanity");
420 }
421 #endif
422 _hrm.allocate_free_regions_starting_at(first, obj_regions);
423 } else {
424 // Policy: Potentially trigger a defragmentation GC.
425 }
426 }
427
428 HeapWord* result = NULL;
429 if (first != G1_NO_HRM_INDEX) {
430 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
431 assert(result != NULL, "it should always return a valid result");
432
433 // A successful humongous object allocation changes the used space
434 // information of the old generation so we need to recalculate the
435 // sizes and update the jstat counters here.
436 g1mm()->update_sizes();
437 }
438
439 _verifier->verify_region_sets_optional();
440
441 return result;
442 }
443
444 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
445 assert_heap_not_locked_and_not_at_safepoint();
446 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
447
448 return attempt_allocation(word_size);
449 }
450
451 HeapWord*
452 G1CollectedHeap::mem_allocate(size_t word_size,
453 bool* gc_overhead_limit_was_exceeded) {
454 assert_heap_not_locked_and_not_at_safepoint();
455
456 if (is_humongous(word_size)) {
457 return attempt_allocation_humongous(word_size);
458 }
459 return attempt_allocation(word_size);
460 }
461
462 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
463 ResourceMark rm; // For retrieving the thread names in log messages.
464
465 // Make sure you read the note in attempt_allocation_humongous().
466
467 assert_heap_not_locked_and_not_at_safepoint();
468 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
469 "be called for humongous allocation requests");
470
471 // We should only get here after the first-level allocation attempt
472 // (attempt_allocation()) failed to allocate.
473
474 // We will loop until a) we manage to successfully perform the
475 // allocation or b) we successfully schedule a collection which
476 // fails to perform the allocation. b) is the only case when we'll
477 // return NULL.
478 HeapWord* result = NULL;
479 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
480 bool should_try_gc;
481 uint gc_count_before;
482
483 {
484 MutexLockerEx x(Heap_lock);
485 result = _allocator->attempt_allocation_locked(word_size);
486 if (result != NULL) {
487 return result;
488 }
489
490 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
491 // This is different to when only GCLocker::needs_gc() is set: try to avoid
492 // waiting because the GCLocker is active to not wait too long.
493 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
494 // No need for an ergo message here, can_expand_young_list() does this when
495 // it returns true.
496 result = _allocator->attempt_allocation_force(word_size);
497 if (result != NULL) {
498 return result;
499 }
500 }
501 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
502 // the GCLocker initiated GC has been performed and then retry. This includes
503 // the case when the GC Locker is not active but has not been performed.
504 should_try_gc = !GCLocker::needs_gc();
505 // Read the GC count while still holding the Heap_lock.
506 gc_count_before = total_collections();
507 }
508
509 if (should_try_gc) {
510 bool succeeded;
511 result = do_collection_pause(word_size, gc_count_before, &succeeded,
512 GCCause::_g1_inc_collection_pause);
513 if (result != NULL) {
514 assert(succeeded, "only way to get back a non-NULL result");
515 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
516 Thread::current()->name(), p2i(result));
517 return result;
518 }
519
520 if (succeeded) {
521 // We successfully scheduled a collection which failed to allocate. No
522 // point in trying to allocate further. We'll just return NULL.
523 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
524 SIZE_FORMAT " words", Thread::current()->name(), word_size);
525 return NULL;
526 }
527 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
528 Thread::current()->name(), word_size);
529 } else {
530 // Failed to schedule a collection.
531 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
532 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
533 SIZE_FORMAT " words", Thread::current()->name(), word_size);
534 return NULL;
535 }
536 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
537 // The GCLocker is either active or the GCLocker initiated
538 // GC has not yet been performed. Stall until it is and
539 // then retry the allocation.
540 GCLocker::stall_until_clear();
541 gclocker_retry_count += 1;
542 }
543
544 // We can reach here if we were unsuccessful in scheduling a
545 // collection (because another thread beat us to it) or if we were
546 // stalled due to the GC locker. In either can we should retry the
547 // allocation attempt in case another thread successfully
548 // performed a collection and reclaimed enough space. We do the
549 // first attempt (without holding the Heap_lock) here and the
550 // follow-on attempt will be at the start of the next loop
551 // iteration (after taking the Heap_lock).
552
553 result = _allocator->attempt_allocation(word_size);
554 if (result != NULL) {
555 return result;
556 }
557
558 // Give a warning if we seem to be looping forever.
559 if ((QueuedAllocationWarningCount > 0) &&
560 (try_count % QueuedAllocationWarningCount == 0)) {
561 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
562 Thread::current()->name(), try_count, word_size);
563 }
564 }
565
566 ShouldNotReachHere();
567 return NULL;
568 }
569
570 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
571 assert_at_safepoint_on_vm_thread();
572 if (_archive_allocator == NULL) {
573 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
574 }
575 }
576
577 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
578 // Allocations in archive regions cannot be of a size that would be considered
579 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
580 // may be different at archive-restore time.
581 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
582 }
583
584 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
585 assert_at_safepoint_on_vm_thread();
586 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
587 if (is_archive_alloc_too_large(word_size)) {
588 return NULL;
589 }
590 return _archive_allocator->archive_mem_allocate(word_size);
591 }
592
593 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
594 size_t end_alignment_in_bytes) {
595 assert_at_safepoint_on_vm_thread();
596 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
597
598 // Call complete_archive to do the real work, filling in the MemRegion
599 // array with the archive regions.
600 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
601 delete _archive_allocator;
602 _archive_allocator = NULL;
603 }
604
605 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
606 assert(ranges != NULL, "MemRegion array NULL");
607 assert(count != 0, "No MemRegions provided");
608 MemRegion reserved = _hrm.reserved();
609 for (size_t i = 0; i < count; i++) {
610 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
611 return false;
612 }
613 }
614 return true;
615 }
616
617 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
618 size_t count,
619 bool open) {
620 assert(!is_init_completed(), "Expect to be called at JVM init time");
621 assert(ranges != NULL, "MemRegion array NULL");
622 assert(count != 0, "No MemRegions provided");
623 MutexLockerEx x(Heap_lock);
624
625 MemRegion reserved = _hrm.reserved();
626 HeapWord* prev_last_addr = NULL;
627 HeapRegion* prev_last_region = NULL;
628
629 // Temporarily disable pretouching of heap pages. This interface is used
630 // when mmap'ing archived heap data in, so pre-touching is wasted.
631 FlagSetting fs(AlwaysPreTouch, false);
632
633 // Enable archive object checking used by G1MarkSweep. We have to let it know
634 // about each archive range, so that objects in those ranges aren't marked.
635 G1ArchiveAllocator::enable_archive_object_check();
636
637 // For each specified MemRegion range, allocate the corresponding G1
638 // regions and mark them as archive regions. We expect the ranges
639 // in ascending starting address order, without overlap.
640 for (size_t i = 0; i < count; i++) {
641 MemRegion curr_range = ranges[i];
642 HeapWord* start_address = curr_range.start();
643 size_t word_size = curr_range.word_size();
644 HeapWord* last_address = curr_range.last();
645 size_t commits = 0;
646
647 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
648 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
649 p2i(start_address), p2i(last_address));
650 guarantee(start_address > prev_last_addr,
651 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
652 p2i(start_address), p2i(prev_last_addr));
653 prev_last_addr = last_address;
654
655 // Check for ranges that start in the same G1 region in which the previous
656 // range ended, and adjust the start address so we don't try to allocate
657 // the same region again. If the current range is entirely within that
658 // region, skip it, just adjusting the recorded top.
659 HeapRegion* start_region = _hrm.addr_to_region(start_address);
660 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
661 start_address = start_region->end();
662 if (start_address > last_address) {
663 increase_used(word_size * HeapWordSize);
664 start_region->set_top(last_address + 1);
665 continue;
666 }
667 start_region->set_top(start_address);
668 curr_range = MemRegion(start_address, last_address + 1);
669 start_region = _hrm.addr_to_region(start_address);
670 }
671
672 // Perform the actual region allocation, exiting if it fails.
673 // Then note how much new space we have allocated.
674 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
675 return false;
676 }
677 increase_used(word_size * HeapWordSize);
678 if (commits != 0) {
679 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
680 HeapRegion::GrainWords * HeapWordSize * commits);
681
682 }
683
684 // Mark each G1 region touched by the range as archive, add it to
685 // the old set, and set top.
686 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
687 HeapRegion* last_region = _hrm.addr_to_region(last_address);
688 prev_last_region = last_region;
689
690 while (curr_region != NULL) {
691 assert(curr_region->is_empty() && !curr_region->is_pinned(),
692 "Region already in use (index %u)", curr_region->hrm_index());
693 if (open) {
694 curr_region->set_open_archive();
695 } else {
696 curr_region->set_closed_archive();
697 }
698 _hr_printer.alloc(curr_region);
699 _old_set.add(curr_region);
700 HeapWord* top;
701 HeapRegion* next_region;
702 if (curr_region != last_region) {
703 top = curr_region->end();
704 next_region = _hrm.next_region_in_heap(curr_region);
705 } else {
706 top = last_address + 1;
707 next_region = NULL;
708 }
709 curr_region->set_top(top);
710 curr_region->set_first_dead(top);
711 curr_region->set_end_of_live(top);
712 curr_region = next_region;
713 }
714
715 // Notify mark-sweep of the archive
716 G1ArchiveAllocator::set_range_archive(curr_range, open);
717 }
718 return true;
719 }
720
721 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
722 assert(!is_init_completed(), "Expect to be called at JVM init time");
723 assert(ranges != NULL, "MemRegion array NULL");
724 assert(count != 0, "No MemRegions provided");
725 MemRegion reserved = _hrm.reserved();
726 HeapWord *prev_last_addr = NULL;
727 HeapRegion* prev_last_region = NULL;
728
729 // For each MemRegion, create filler objects, if needed, in the G1 regions
730 // that contain the address range. The address range actually within the
731 // MemRegion will not be modified. That is assumed to have been initialized
732 // elsewhere, probably via an mmap of archived heap data.
733 MutexLockerEx x(Heap_lock);
734 for (size_t i = 0; i < count; i++) {
735 HeapWord* start_address = ranges[i].start();
736 HeapWord* last_address = ranges[i].last();
737
738 assert(reserved.contains(start_address) && reserved.contains(last_address),
739 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
740 p2i(start_address), p2i(last_address));
741 assert(start_address > prev_last_addr,
742 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
743 p2i(start_address), p2i(prev_last_addr));
744
745 HeapRegion* start_region = _hrm.addr_to_region(start_address);
746 HeapRegion* last_region = _hrm.addr_to_region(last_address);
747 HeapWord* bottom_address = start_region->bottom();
748
749 // Check for a range beginning in the same region in which the
750 // previous one ended.
751 if (start_region == prev_last_region) {
752 bottom_address = prev_last_addr + 1;
753 }
754
755 // Verify that the regions were all marked as archive regions by
756 // alloc_archive_regions.
757 HeapRegion* curr_region = start_region;
758 while (curr_region != NULL) {
759 guarantee(curr_region->is_archive(),
760 "Expected archive region at index %u", curr_region->hrm_index());
761 if (curr_region != last_region) {
762 curr_region = _hrm.next_region_in_heap(curr_region);
763 } else {
764 curr_region = NULL;
765 }
766 }
767
768 prev_last_addr = last_address;
769 prev_last_region = last_region;
770
771 // Fill the memory below the allocated range with dummy object(s),
772 // if the region bottom does not match the range start, or if the previous
773 // range ended within the same G1 region, and there is a gap.
774 if (start_address != bottom_address) {
775 size_t fill_size = pointer_delta(start_address, bottom_address);
776 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
777 increase_used(fill_size * HeapWordSize);
778 }
779 }
780 }
781
782 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
783 assert_heap_not_locked_and_not_at_safepoint();
784 assert(!is_humongous(word_size), "attempt_allocation() should not "
785 "be called for humongous allocation requests");
786
787 HeapWord* result = _allocator->attempt_allocation(word_size);
788
789 if (result == NULL) {
790 result = attempt_allocation_slow(word_size);
791 }
792 assert_heap_not_locked();
793 if (result != NULL) {
794 dirty_young_block(result, word_size);
795 }
796 return result;
797 }
798
799 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
800 assert(!is_init_completed(), "Expect to be called at JVM init time");
801 assert(ranges != NULL, "MemRegion array NULL");
802 assert(count != 0, "No MemRegions provided");
803 MemRegion reserved = _hrm.reserved();
804 HeapWord* prev_last_addr = NULL;
805 HeapRegion* prev_last_region = NULL;
806 size_t size_used = 0;
807 size_t uncommitted_regions = 0;
808
809 // For each Memregion, free the G1 regions that constitute it, and
810 // notify mark-sweep that the range is no longer to be considered 'archive.'
811 MutexLockerEx x(Heap_lock);
812 for (size_t i = 0; i < count; i++) {
813 HeapWord* start_address = ranges[i].start();
814 HeapWord* last_address = ranges[i].last();
815
816 assert(reserved.contains(start_address) && reserved.contains(last_address),
817 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
818 p2i(start_address), p2i(last_address));
819 assert(start_address > prev_last_addr,
820 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
821 p2i(start_address), p2i(prev_last_addr));
822 size_used += ranges[i].byte_size();
823 prev_last_addr = last_address;
824
825 HeapRegion* start_region = _hrm.addr_to_region(start_address);
826 HeapRegion* last_region = _hrm.addr_to_region(last_address);
827
828 // Check for ranges that start in the same G1 region in which the previous
829 // range ended, and adjust the start address so we don't try to free
830 // the same region again. If the current range is entirely within that
831 // region, skip it.
832 if (start_region == prev_last_region) {
833 start_address = start_region->end();
834 if (start_address > last_address) {
835 continue;
836 }
837 start_region = _hrm.addr_to_region(start_address);
838 }
839 prev_last_region = last_region;
840
841 // After verifying that each region was marked as an archive region by
842 // alloc_archive_regions, set it free and empty and uncommit it.
843 HeapRegion* curr_region = start_region;
844 while (curr_region != NULL) {
845 guarantee(curr_region->is_archive(),
846 "Expected archive region at index %u", curr_region->hrm_index());
847 uint curr_index = curr_region->hrm_index();
848 _old_set.remove(curr_region);
849 curr_region->set_free();
850 curr_region->set_top(curr_region->bottom());
851 if (curr_region != last_region) {
852 curr_region = _hrm.next_region_in_heap(curr_region);
853 } else {
854 curr_region = NULL;
855 }
856 _hrm.shrink_at(curr_index, 1);
857 uncommitted_regions++;
858 }
859
860 // Notify mark-sweep that this is no longer an archive range.
861 G1ArchiveAllocator::set_range_archive(ranges[i], false);
862 }
863
864 if (uncommitted_regions != 0) {
865 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
866 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
867 }
868 decrease_used(size_used);
869 }
870
871 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
872 ResourceMark rm; // For retrieving the thread names in log messages.
873
874 // The structure of this method has a lot of similarities to
875 // attempt_allocation_slow(). The reason these two were not merged
876 // into a single one is that such a method would require several "if
877 // allocation is not humongous do this, otherwise do that"
878 // conditional paths which would obscure its flow. In fact, an early
879 // version of this code did use a unified method which was harder to
880 // follow and, as a result, it had subtle bugs that were hard to
881 // track down. So keeping these two methods separate allows each to
882 // be more readable. It will be good to keep these two in sync as
883 // much as possible.
884
885 assert_heap_not_locked_and_not_at_safepoint();
886 assert(is_humongous(word_size), "attempt_allocation_humongous() "
887 "should only be called for humongous allocations");
888
889 // Humongous objects can exhaust the heap quickly, so we should check if we
890 // need to start a marking cycle at each humongous object allocation. We do
891 // the check before we do the actual allocation. The reason for doing it
892 // before the allocation is that we avoid having to keep track of the newly
893 // allocated memory while we do a GC.
894 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
895 word_size)) {
896 collect(GCCause::_g1_humongous_allocation);
897 }
898
899 // We will loop until a) we manage to successfully perform the
900 // allocation or b) we successfully schedule a collection which
901 // fails to perform the allocation. b) is the only case when we'll
902 // return NULL.
903 HeapWord* result = NULL;
904 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
905 bool should_try_gc;
906 uint gc_count_before;
907
908
909 {
910 MutexLockerEx x(Heap_lock);
911
912 // Given that humongous objects are not allocated in young
913 // regions, we'll first try to do the allocation without doing a
914 // collection hoping that there's enough space in the heap.
915 result = humongous_obj_allocate(word_size);
916 if (result != NULL) {
917 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
918 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
919 return result;
920 }
921
922 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
923 // the GCLocker initiated GC has been performed and then retry. This includes
924 // the case when the GC Locker is not active but has not been performed.
925 should_try_gc = !GCLocker::needs_gc();
926 // Read the GC count while still holding the Heap_lock.
927 gc_count_before = total_collections();
928 }
929
930 if (should_try_gc) {
931 bool succeeded;
932 result = do_collection_pause(word_size, gc_count_before, &succeeded,
933 GCCause::_g1_humongous_allocation);
934 if (result != NULL) {
935 assert(succeeded, "only way to get back a non-NULL result");
936 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
937 Thread::current()->name(), p2i(result));
938 return result;
939 }
940
941 if (succeeded) {
942 // We successfully scheduled a collection which failed to allocate. No
943 // point in trying to allocate further. We'll just return NULL.
944 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
945 SIZE_FORMAT " words", Thread::current()->name(), word_size);
946 return NULL;
947 }
948 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
949 Thread::current()->name(), word_size);
950 } else {
951 // Failed to schedule a collection.
952 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
953 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
954 SIZE_FORMAT " words", Thread::current()->name(), word_size);
955 return NULL;
956 }
957 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
958 // The GCLocker is either active or the GCLocker initiated
959 // GC has not yet been performed. Stall until it is and
960 // then retry the allocation.
961 GCLocker::stall_until_clear();
962 gclocker_retry_count += 1;
963 }
964
965
966 // We can reach here if we were unsuccessful in scheduling a
967 // collection (because another thread beat us to it) or if we were
968 // stalled due to the GC locker. In either can we should retry the
969 // allocation attempt in case another thread successfully
970 // performed a collection and reclaimed enough space.
971 // Humongous object allocation always needs a lock, so we wait for the retry
972 // in the next iteration of the loop, unlike for the regular iteration case.
973 // Give a warning if we seem to be looping forever.
974
975 if ((QueuedAllocationWarningCount > 0) &&
976 (try_count % QueuedAllocationWarningCount == 0)) {
977 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
978 Thread::current()->name(), try_count, word_size);
979 }
980 }
981
982 ShouldNotReachHere();
983 return NULL;
984 }
985
986 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
987 bool expect_null_mutator_alloc_region) {
988 assert_at_safepoint_on_vm_thread();
989 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
990 "the current alloc region was unexpectedly found to be non-NULL");
991
992 if (!is_humongous(word_size)) {
993 return _allocator->attempt_allocation_locked(word_size);
994 } else {
995 HeapWord* result = humongous_obj_allocate(word_size);
996 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
997 collector_state()->set_initiate_conc_mark_if_possible(true);
998 }
999 return result;
1000 }
1001
1002 ShouldNotReachHere();
1003 }
1004
1005 class PostCompactionPrinterClosure: public HeapRegionClosure {
1006 private:
1007 G1HRPrinter* _hr_printer;
1008 public:
1009 bool do_heap_region(HeapRegion* hr) {
1010 assert(!hr->is_young(), "not expecting to find young regions");
1011 _hr_printer->post_compaction(hr);
1012 return false;
1013 }
1014
1015 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1016 : _hr_printer(hr_printer) { }
1017 };
1018
1019 void G1CollectedHeap::print_hrm_post_compaction() {
1020 if (_hr_printer.is_active()) {
1021 PostCompactionPrinterClosure cl(hr_printer());
1022 heap_region_iterate(&cl);
1023 }
1024 }
1025
1026 void G1CollectedHeap::abort_concurrent_cycle() {
1027 // Note: When we have a more flexible GC logging framework that
1028 // allows us to add optional attributes to a GC log record we
1029 // could consider timing and reporting how long we wait in the
1030 // following two methods.
1031 wait_while_free_regions_coming();
1032 // If we start the compaction before the CM threads finish
1033 // scanning the root regions we might trip them over as we'll
1034 // be moving objects / updating references. So let's wait until
1035 // they are done. By telling them to abort, they should complete
1036 // early.
1037 _cm->root_regions()->abort();
1038 _cm->root_regions()->wait_until_scan_finished();
1039 append_secondary_free_list_if_not_empty_with_lock();
1040
1041 // Disable discovery and empty the discovered lists
1042 // for the CM ref processor.
1043 ref_processor_cm()->disable_discovery();
1044 ref_processor_cm()->abandon_partial_discovery();
1045 ref_processor_cm()->verify_no_references_recorded();
1046
1047 // Abandon current iterations of concurrent marking and concurrent
1048 // refinement, if any are in progress.
1049 concurrent_mark()->abort();
1050 }
1051
1052 void G1CollectedHeap::prepare_heap_for_full_collection() {
1053 // Make sure we'll choose a new allocation region afterwards.
1054 _allocator->release_mutator_alloc_region();
1055 _allocator->abandon_gc_alloc_regions();
1056 g1_rem_set()->cleanupHRRS();
1057
1058 // We may have added regions to the current incremental collection
1059 // set between the last GC or pause and now. We need to clear the
1060 // incremental collection set and then start rebuilding it afresh
1061 // after this full GC.
1062 abandon_collection_set(collection_set());
1063
1064 tear_down_region_sets(false /* free_list_only */);
1065 collector_state()->set_gcs_are_young(true);
1066 }
1067
1068 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1069 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1070 assert(used() == recalculate_used(), "Should be equal");
1071 _verifier->verify_region_sets_optional();
1072 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1073 _verifier->check_bitmaps("Full GC Start");
1074 }
1075
1076 void G1CollectedHeap::prepare_heap_for_mutators() {
1077 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1078 ClassLoaderDataGraph::purge();
1079 MetaspaceUtils::verify_metrics();
1080
1081 // Prepare heap for normal collections.
1082 assert(num_free_regions() == 0, "we should not have added any free regions");
1083 rebuild_region_sets(false /* free_list_only */);
1084 abort_refinement();
1085 resize_if_necessary_after_full_collection();
1086
1087 // Rebuild the strong code root lists for each region
1088 rebuild_strong_code_roots();
1089
1090 // Start a new incremental collection set for the next pause
1091 start_new_collection_set();
1092
1093 _allocator->init_mutator_alloc_region();
1094
1095 // Post collection state updates.
1096 MetaspaceGC::compute_new_size();
1097 }
1098
1099 void G1CollectedHeap::abort_refinement() {
1100 if (_hot_card_cache->use_cache()) {
1101 _hot_card_cache->reset_hot_cache();
1102 }
1103
1104 // Discard all remembered set updates.
1105 JavaThread::dirty_card_queue_set().abandon_logs();
1106 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1107 }
1108
1109 void G1CollectedHeap::verify_after_full_collection() {
1110 check_gc_time_stamps();
1111 _hrm.verify_optional();
1112 _verifier->verify_region_sets_optional();
1113 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1114 // Clear the previous marking bitmap, if needed for bitmap verification.
1115 // Note we cannot do this when we clear the next marking bitmap in
1116 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1117 // objects marked during a full GC against the previous bitmap.
1118 // But we need to clear it before calling check_bitmaps below since
1119 // the full GC has compacted objects and updated TAMS but not updated
1120 // the prev bitmap.
1121 if (G1VerifyBitmaps) {
1122 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1123 _cm->clear_prev_bitmap(workers());
1124 }
1125 _verifier->check_bitmaps("Full GC End");
1126
1127 // At this point there should be no regions in the
1128 // entire heap tagged as young.
1129 assert(check_young_list_empty(), "young list should be empty at this point");
1130
1131 // Note: since we've just done a full GC, concurrent
1132 // marking is no longer active. Therefore we need not
1133 // re-enable reference discovery for the CM ref processor.
1134 // That will be done at the start of the next marking cycle.
1135 // We also know that the STW processor should no longer
1136 // discover any new references.
1137 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1138 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1139 ref_processor_stw()->verify_no_references_recorded();
1140 ref_processor_cm()->verify_no_references_recorded();
1141 }
1142
1143 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1144 // Post collection logging.
1145 // We should do this after we potentially resize the heap so
1146 // that all the COMMIT / UNCOMMIT events are generated before
1147 // the compaction events.
1148 print_hrm_post_compaction();
1149 heap_transition->print();
1150 print_heap_after_gc();
1151 print_heap_regions();
1152 #ifdef TRACESPINNING
1153 ParallelTaskTerminator::print_termination_counts();
1154 #endif
1155 }
1156
1157 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1158 bool clear_all_soft_refs) {
1159 assert_at_safepoint_on_vm_thread();
1160
1161 if (GCLocker::check_active_before_gc()) {
1162 // Full GC was not completed.
1163 return false;
1164 }
1165
1166 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1167 soft_ref_policy()->should_clear_all_soft_refs();
1168
1169 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1170 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1171
1172 collector.prepare_collection();
1173 collector.collect();
1174 collector.complete_collection();
1175
1176 // Full collection was successfully completed.
1177 return true;
1178 }
1179
1180 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1181 // Currently, there is no facility in the do_full_collection(bool) API to notify
1182 // the caller that the collection did not succeed (e.g., because it was locked
1183 // out by the GC locker). So, right now, we'll ignore the return value.
1184 bool dummy = do_full_collection(true, /* explicit_gc */
1185 clear_all_soft_refs);
1186 }
1187
1188 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1189 // Capacity, free and used after the GC counted as full regions to
1190 // include the waste in the following calculations.
1191 const size_t capacity_after_gc = capacity();
1192 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1193
1194 // This is enforced in arguments.cpp.
1195 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1196 "otherwise the code below doesn't make sense");
1197
1198 // We don't have floating point command-line arguments
1199 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1200 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1201 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1202 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1203
1204 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1205 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1206
1207 // We have to be careful here as these two calculations can overflow
1208 // 32-bit size_t's.
1209 double used_after_gc_d = (double) used_after_gc;
1210 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1211 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1212
1213 // Let's make sure that they are both under the max heap size, which
1214 // by default will make them fit into a size_t.
1215 double desired_capacity_upper_bound = (double) max_heap_size;
1216 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1217 desired_capacity_upper_bound);
1218 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1219 desired_capacity_upper_bound);
1220
1221 // We can now safely turn them into size_t's.
1222 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1223 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1224
1225 // This assert only makes sense here, before we adjust them
1226 // with respect to the min and max heap size.
1227 assert(minimum_desired_capacity <= maximum_desired_capacity,
1228 "minimum_desired_capacity = " SIZE_FORMAT ", "
1229 "maximum_desired_capacity = " SIZE_FORMAT,
1230 minimum_desired_capacity, maximum_desired_capacity);
1231
1232 // Should not be greater than the heap max size. No need to adjust
1233 // it with respect to the heap min size as it's a lower bound (i.e.,
1234 // we'll try to make the capacity larger than it, not smaller).
1235 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1236 // Should not be less than the heap min size. No need to adjust it
1237 // with respect to the heap max size as it's an upper bound (i.e.,
1238 // we'll try to make the capacity smaller than it, not greater).
1239 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1240
1241 if (capacity_after_gc < minimum_desired_capacity) {
1242 // Don't expand unless it's significant
1243 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1244
1245 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1246 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1247 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1248 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1249
1250 expand(expand_bytes, _workers);
1251
1252 // No expansion, now see if we want to shrink
1253 } else if (capacity_after_gc > maximum_desired_capacity) {
1254 // Capacity too large, compute shrinking size
1255 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1256
1257 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1258 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1259 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1260 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1261
1262 shrink(shrink_bytes);
1263 }
1264 }
1265
1266 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1267 bool do_gc,
1268 bool clear_all_soft_refs,
1269 bool expect_null_mutator_alloc_region,
1270 bool* gc_succeeded) {
1271 *gc_succeeded = true;
1272 // Let's attempt the allocation first.
1273 HeapWord* result =
1274 attempt_allocation_at_safepoint(word_size,
1275 expect_null_mutator_alloc_region);
1276 if (result != NULL) {
1277 return result;
1278 }
1279
1280 // In a G1 heap, we're supposed to keep allocation from failing by
1281 // incremental pauses. Therefore, at least for now, we'll favor
1282 // expansion over collection. (This might change in the future if we can
1283 // do something smarter than full collection to satisfy a failed alloc.)
1284 result = expand_and_allocate(word_size);
1285 if (result != NULL) {
1286 return result;
1287 }
1288
1289 if (do_gc) {
1290 // Expansion didn't work, we'll try to do a Full GC.
1291 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1292 clear_all_soft_refs);
1293 }
1294
1295 return NULL;
1296 }
1297
1298 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1299 bool* succeeded) {
1300 assert_at_safepoint_on_vm_thread();
1301
1302 // Attempts to allocate followed by Full GC.
1303 HeapWord* result =
1304 satisfy_failed_allocation_helper(word_size,
1305 true, /* do_gc */
1306 false, /* clear_all_soft_refs */
1307 false, /* expect_null_mutator_alloc_region */
1308 succeeded);
1309
1310 if (result != NULL || !*succeeded) {
1311 return result;
1312 }
1313
1314 // Attempts to allocate followed by Full GC that will collect all soft references.
1315 result = satisfy_failed_allocation_helper(word_size,
1316 true, /* do_gc */
1317 true, /* clear_all_soft_refs */
1318 true, /* expect_null_mutator_alloc_region */
1319 succeeded);
1320
1321 if (result != NULL || !*succeeded) {
1322 return result;
1323 }
1324
1325 // Attempts to allocate, no GC
1326 result = satisfy_failed_allocation_helper(word_size,
1327 false, /* do_gc */
1328 false, /* clear_all_soft_refs */
1329 true, /* expect_null_mutator_alloc_region */
1330 succeeded);
1331
1332 if (result != NULL) {
1333 return result;
1334 }
1335
1336 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1337 "Flag should have been handled and cleared prior to this point");
1338
1339 // What else? We might try synchronous finalization later. If the total
1340 // space available is large enough for the allocation, then a more
1341 // complete compaction phase than we've tried so far might be
1342 // appropriate.
1343 return NULL;
1344 }
1345
1346 // Attempting to expand the heap sufficiently
1347 // to support an allocation of the given "word_size". If
1348 // successful, perform the allocation and return the address of the
1349 // allocated block, or else "NULL".
1350
1351 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1352 assert_at_safepoint_on_vm_thread();
1353
1354 _verifier->verify_region_sets_optional();
1355
1356 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1357 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1358 word_size * HeapWordSize);
1359
1360
1361 if (expand(expand_bytes, _workers)) {
1362 _hrm.verify_optional();
1363 _verifier->verify_region_sets_optional();
1364 return attempt_allocation_at_safepoint(word_size,
1365 false /* expect_null_mutator_alloc_region */);
1366 }
1367 return NULL;
1368 }
1369
1370 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1371 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1372 aligned_expand_bytes = align_up(aligned_expand_bytes,
1373 HeapRegion::GrainBytes);
1374
1375 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1376 expand_bytes, aligned_expand_bytes);
1377
1378 if (is_maximal_no_gc()) {
1379 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1380 return false;
1381 }
1382
1383 double expand_heap_start_time_sec = os::elapsedTime();
1384 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1385 assert(regions_to_expand > 0, "Must expand by at least one region");
1386
1387 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1388 if (expand_time_ms != NULL) {
1389 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1390 }
1391
1392 if (expanded_by > 0) {
1393 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1394 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1395 g1_policy()->record_new_heap_size(num_regions());
1396 } else {
1397 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1398
1399 // The expansion of the virtual storage space was unsuccessful.
1400 // Let's see if it was because we ran out of swap.
1401 if (G1ExitOnExpansionFailure &&
1402 _hrm.available() >= regions_to_expand) {
1403 // We had head room...
1404 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1405 }
1406 }
1407 return regions_to_expand > 0;
1408 }
1409
1410 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1411 size_t aligned_shrink_bytes =
1412 ReservedSpace::page_align_size_down(shrink_bytes);
1413 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1414 HeapRegion::GrainBytes);
1415 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1416
1417 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1418 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1419
1420
1421 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",
1422 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1423 if (num_regions_removed > 0) {
1424 g1_policy()->record_new_heap_size(num_regions());
1425 } else {
1426 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1427 }
1428 }
1429
1430 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1431 _verifier->verify_region_sets_optional();
1432
1433 // We should only reach here at the end of a Full GC which means we
1434 // should not not be holding to any GC alloc regions. The method
1435 // below will make sure of that and do any remaining clean up.
1436 _allocator->abandon_gc_alloc_regions();
1437
1438 // Instead of tearing down / rebuilding the free lists here, we
1439 // could instead use the remove_all_pending() method on free_list to
1440 // remove only the ones that we need to remove.
1441 tear_down_region_sets(true /* free_list_only */);
1442 shrink_helper(shrink_bytes);
1443 rebuild_region_sets(true /* free_list_only */);
1444
1445 _hrm.verify_optional();
1446 _verifier->verify_region_sets_optional();
1447 }
1448
1449 // Public methods.
1450
1451 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1452 CollectedHeap(),
1453 _young_gen_sampling_thread(NULL),
1454 _collector_policy(collector_policy),
1455 _soft_ref_policy(),
1456 _card_table(NULL),
1457 _memory_manager("G1 Young Generation", "end of minor GC"),
1458 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1459 _eden_pool(NULL),
1460 _survivor_pool(NULL),
1461 _old_pool(NULL),
1462 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1463 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1464 _g1_policy(new G1Policy(_gc_timer_stw)),
1465 _collection_set(this, _g1_policy),
1466 _dirty_card_queue_set(false),
1467 _is_alive_closure_cm(this),
1468 _is_alive_closure_stw(this),
1469 _ref_processor_cm(NULL),
1470 _ref_processor_stw(NULL),
1471 _bot(NULL),
1472 _hot_card_cache(NULL),
1473 _g1_rem_set(NULL),
1474 _cr(NULL),
1475 _g1mm(NULL),
1476 _preserved_marks_set(true /* in_c_heap */),
1477 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1478 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1479 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1480 _humongous_reclaim_candidates(),
1481 _has_humongous_reclaim_candidates(false),
1482 _archive_allocator(NULL),
1483 _free_regions_coming(false),
1484 _gc_time_stamp(0),
1485 _summary_bytes_used(0),
1486 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1487 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1488 _expand_heap_after_alloc_failure(true),
1489 _old_marking_cycles_started(0),
1490 _old_marking_cycles_completed(0),
1491 _in_cset_fast_test() {
1492
1493 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1494 /* are_GC_task_threads */true,
1495 /* are_ConcurrentGC_threads */false);
1496 _workers->initialize_workers();
1497 _verifier = new G1HeapVerifier(this);
1498
1499 _allocator = new G1DefaultAllocator(this);
1500
1501 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1502
1503 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1504
1505 // Override the default _filler_array_max_size so that no humongous filler
1506 // objects are created.
1507 _filler_array_max_size = _humongous_object_threshold_in_words;
1508
1509 uint n_queues = ParallelGCThreads;
1510 _task_queues = new RefToScanQueueSet(n_queues);
1511
1512 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1513
1514 for (uint i = 0; i < n_queues; i++) {
1515 RefToScanQueue* q = new RefToScanQueue();
1516 q->initialize();
1517 _task_queues->register_queue(i, q);
1518 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1519 }
1520
1521 // Initialize the G1EvacuationFailureALot counters and flags.
1522 NOT_PRODUCT(reset_evacuation_should_fail();)
1523
1524 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1525 }
1526
1527 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1528 size_t size,
1529 size_t translation_factor) {
1530 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1531 // Allocate a new reserved space, preferring to use large pages.
1532 ReservedSpace rs(size, preferred_page_size);
1533 G1RegionToSpaceMapper* result =
1534 G1RegionToSpaceMapper::create_mapper(rs,
1535 size,
1536 rs.alignment(),
1537 HeapRegion::GrainBytes,
1538 translation_factor,
1539 mtGC);
1540
1541 os::trace_page_sizes_for_requested_size(description,
1542 size,
1543 preferred_page_size,
1544 rs.alignment(),
1545 rs.base(),
1546 rs.size());
1547
1548 return result;
1549 }
1550
1551 jint G1CollectedHeap::initialize_concurrent_refinement() {
1552 jint ecode = JNI_OK;
1553 _cr = G1ConcurrentRefine::create(&ecode);
1554 return ecode;
1555 }
1556
1557 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1558 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1559 if (_young_gen_sampling_thread->osthread() == NULL) {
1560 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1561 return JNI_ENOMEM;
1562 }
1563 return JNI_OK;
1564 }
1565
1566 jint G1CollectedHeap::initialize() {
1567 os::enable_vtime();
1568
1569 // Necessary to satisfy locking discipline assertions.
1570
1571 MutexLocker x(Heap_lock);
1572
1573 // While there are no constraints in the GC code that HeapWordSize
1574 // be any particular value, there are multiple other areas in the
1575 // system which believe this to be true (e.g. oop->object_size in some
1576 // cases incorrectly returns the size in wordSize units rather than
1577 // HeapWordSize).
1578 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1579
1580 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1581 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1582 size_t heap_alignment = collector_policy()->heap_alignment();
1583
1584 // Ensure that the sizes are properly aligned.
1585 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1586 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1587 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1588
1589 // Reserve the maximum.
1590
1591 // When compressed oops are enabled, the preferred heap base
1592 // is calculated by subtracting the requested size from the
1593 // 32Gb boundary and using the result as the base address for
1594 // heap reservation. If the requested size is not aligned to
1595 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1596 // into the ReservedHeapSpace constructor) then the actual
1597 // base of the reserved heap may end up differing from the
1598 // address that was requested (i.e. the preferred heap base).
1599 // If this happens then we could end up using a non-optimal
1600 // compressed oops mode.
1601
1602 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1603 heap_alignment);
1604
1605 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1606
1607 // Create the barrier set for the entire reserved region.
1608 G1CardTable* ct = new G1CardTable(reserved_region());
1609 ct->initialize();
1610 G1BarrierSet* bs = new G1BarrierSet(ct);
1611 bs->initialize();
1612 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1613 set_barrier_set(bs);
1614 _card_table = ct;
1615
1616 // Create the hot card cache.
1617 _hot_card_cache = new G1HotCardCache(this);
1618
1619 // Carve out the G1 part of the heap.
1620 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1621 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1622 G1RegionToSpaceMapper* heap_storage =
1623 G1RegionToSpaceMapper::create_mapper(g1_rs,
1624 g1_rs.size(),
1625 page_size,
1626 HeapRegion::GrainBytes,
1627 1,
1628 mtJavaHeap);
1629 os::trace_page_sizes("Heap",
1630 collector_policy()->min_heap_byte_size(),
1631 max_byte_size,
1632 page_size,
1633 heap_rs.base(),
1634 heap_rs.size());
1635 heap_storage->set_mapping_changed_listener(&_listener);
1636
1637 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1638 G1RegionToSpaceMapper* bot_storage =
1639 create_aux_memory_mapper("Block Offset Table",
1640 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1641 G1BlockOffsetTable::heap_map_factor());
1642
1643 G1RegionToSpaceMapper* cardtable_storage =
1644 create_aux_memory_mapper("Card Table",
1645 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1646 G1CardTable::heap_map_factor());
1647
1648 G1RegionToSpaceMapper* card_counts_storage =
1649 create_aux_memory_mapper("Card Counts Table",
1650 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1651 G1CardCounts::heap_map_factor());
1652
1653 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1654 G1RegionToSpaceMapper* prev_bitmap_storage =
1655 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1656 G1RegionToSpaceMapper* next_bitmap_storage =
1657 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1658
1659 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1660 _card_table->initialize(cardtable_storage);
1661 // Do later initialization work for concurrent refinement.
1662 _hot_card_cache->initialize(card_counts_storage);
1663
1664 // 6843694 - ensure that the maximum region index can fit
1665 // in the remembered set structures.
1666 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1667 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1668
1669 // Also create a G1 rem set.
1670 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1671 _g1_rem_set->initialize(max_capacity(), max_regions());
1672
1673 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1674 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1675 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1676 "too many cards per region");
1677
1678 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1679
1680 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1681
1682 {
1683 HeapWord* start = _hrm.reserved().start();
1684 HeapWord* end = _hrm.reserved().end();
1685 size_t granularity = HeapRegion::GrainBytes;
1686
1687 _in_cset_fast_test.initialize(start, end, granularity);
1688 _humongous_reclaim_candidates.initialize(start, end, granularity);
1689 }
1690
1691 // Create the G1ConcurrentMark data structure and thread.
1692 // (Must do this late, so that "max_regions" is defined.)
1693 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1694 if (_cm == NULL || !_cm->completed_initialization()) {
1695 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1696 return JNI_ENOMEM;
1697 }
1698 _cmThread = _cm->cm_thread();
1699
1700 // Now expand into the initial heap size.
1701 if (!expand(init_byte_size, _workers)) {
1702 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1703 return JNI_ENOMEM;
1704 }
1705
1706 // Perform any initialization actions delegated to the policy.
1707 g1_policy()->init(this, &_collection_set);
1708
1709 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1710 SATB_Q_FL_lock,
1711 G1SATBProcessCompletedThreshold,
1712 Shared_SATB_Q_lock);
1713
1714 jint ecode = initialize_concurrent_refinement();
1715 if (ecode != JNI_OK) {
1716 return ecode;
1717 }
1718
1719 ecode = initialize_young_gen_sampling_thread();
1720 if (ecode != JNI_OK) {
1721 return ecode;
1722 }
1723
1724 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1725 DirtyCardQ_FL_lock,
1726 (int)concurrent_refine()->yellow_zone(),
1727 (int)concurrent_refine()->red_zone(),
1728 Shared_DirtyCardQ_lock,
1729 NULL, // fl_owner
1730 true); // init_free_ids
1731
1732 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1733 DirtyCardQ_FL_lock,
1734 -1, // never trigger processing
1735 -1, // no limit on length
1736 Shared_DirtyCardQ_lock,
1737 &JavaThread::dirty_card_queue_set());
1738
1739 // Here we allocate the dummy HeapRegion that is required by the
1740 // G1AllocRegion class.
1741 HeapRegion* dummy_region = _hrm.get_dummy_region();
1742
1743 // We'll re-use the same region whether the alloc region will
1744 // require BOT updates or not and, if it doesn't, then a non-young
1745 // region will complain that it cannot support allocations without
1746 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1747 dummy_region->set_eden();
1748 // Make sure it's full.
1749 dummy_region->set_top(dummy_region->end());
1750 G1AllocRegion::setup(this, dummy_region);
1751
1752 _allocator->init_mutator_alloc_region();
1753
1754 // Do create of the monitoring and management support so that
1755 // values in the heap have been properly initialized.
1756 _g1mm = new G1MonitoringSupport(this);
1757
1758 G1StringDedup::initialize();
1759
1760 _preserved_marks_set.init(ParallelGCThreads);
1761
1762 _collection_set.initialize(max_regions());
1763
1764 return JNI_OK;
1765 }
1766
1767 void G1CollectedHeap::initialize_serviceability() {
1768 _eden_pool = new G1EdenPool(this);
1769 _survivor_pool = new G1SurvivorPool(this);
1770 _old_pool = new G1OldGenPool(this);
1771
1772 _full_gc_memory_manager.add_pool(_eden_pool);
1773 _full_gc_memory_manager.add_pool(_survivor_pool);
1774 _full_gc_memory_manager.add_pool(_old_pool);
1775
1776 _memory_manager.add_pool(_eden_pool);
1777 _memory_manager.add_pool(_survivor_pool);
1778
1779 }
1780
1781 void G1CollectedHeap::stop() {
1782 // Stop all concurrent threads. We do this to make sure these threads
1783 // do not continue to execute and access resources (e.g. logging)
1784 // that are destroyed during shutdown.
1785 _cr->stop();
1786 _young_gen_sampling_thread->stop();
1787 _cmThread->stop();
1788 if (G1StringDedup::is_enabled()) {
1789 G1StringDedup::stop();
1790 }
1791 }
1792
1793 void G1CollectedHeap::safepoint_synchronize_begin() {
1794 SuspendibleThreadSet::synchronize();
1795 }
1796
1797 void G1CollectedHeap::safepoint_synchronize_end() {
1798 SuspendibleThreadSet::desynchronize();
1799 }
1800
1801 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1802 return HeapRegion::max_region_size();
1803 }
1804
1805 void G1CollectedHeap::post_initialize() {
1806 CollectedHeap::post_initialize();
1807 ref_processing_init();
1808 }
1809
1810 void G1CollectedHeap::ref_processing_init() {
1811 // Reference processing in G1 currently works as follows:
1812 //
1813 // * There are two reference processor instances. One is
1814 // used to record and process discovered references
1815 // during concurrent marking; the other is used to
1816 // record and process references during STW pauses
1817 // (both full and incremental).
1818 // * Both ref processors need to 'span' the entire heap as
1819 // the regions in the collection set may be dotted around.
1820 //
1821 // * For the concurrent marking ref processor:
1822 // * Reference discovery is enabled at initial marking.
1823 // * Reference discovery is disabled and the discovered
1824 // references processed etc during remarking.
1825 // * Reference discovery is MT (see below).
1826 // * Reference discovery requires a barrier (see below).
1827 // * Reference processing may or may not be MT
1828 // (depending on the value of ParallelRefProcEnabled
1829 // and ParallelGCThreads).
1830 // * A full GC disables reference discovery by the CM
1831 // ref processor and abandons any entries on it's
1832 // discovered lists.
1833 //
1834 // * For the STW processor:
1835 // * Non MT discovery is enabled at the start of a full GC.
1836 // * Processing and enqueueing during a full GC is non-MT.
1837 // * During a full GC, references are processed after marking.
1838 //
1839 // * Discovery (may or may not be MT) is enabled at the start
1840 // of an incremental evacuation pause.
1841 // * References are processed near the end of a STW evacuation pause.
1842 // * For both types of GC:
1843 // * Discovery is atomic - i.e. not concurrent.
1844 // * Reference discovery will not need a barrier.
1845
1846 MemRegion mr = reserved_region();
1847
1848 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1849
1850 // Concurrent Mark ref processor
1851 _ref_processor_cm =
1852 new ReferenceProcessor(mr, // span
1853 mt_processing,
1854 // mt processing
1855 ParallelGCThreads,
1856 // degree of mt processing
1857 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1858 // mt discovery
1859 MAX2(ParallelGCThreads, ConcGCThreads),
1860 // degree of mt discovery
1861 false,
1862 // Reference discovery is not atomic
1863 &_is_alive_closure_cm);
1864 // is alive closure
1865 // (for efficiency/performance)
1866
1867 // STW ref processor
1868 _ref_processor_stw =
1869 new ReferenceProcessor(mr, // span
1870 mt_processing,
1871 // mt processing
1872 ParallelGCThreads,
1873 // degree of mt processing
1874 (ParallelGCThreads > 1),
1875 // mt discovery
1876 ParallelGCThreads,
1877 // degree of mt discovery
1878 true,
1879 // Reference discovery is atomic
1880 &_is_alive_closure_stw);
1881 // is alive closure
1882 // (for efficiency/performance)
1883 }
1884
1885 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1886 return _collector_policy;
1887 }
1888
1889 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1890 return &_soft_ref_policy;
1891 }
1892
1893 size_t G1CollectedHeap::capacity() const {
1894 return _hrm.length() * HeapRegion::GrainBytes;
1895 }
1896
1897 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1898 return _hrm.total_free_bytes();
1899 }
1900
1901 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1902 hr->reset_gc_time_stamp();
1903 }
1904
1905 #ifndef PRODUCT
1906
1907 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1908 private:
1909 unsigned _gc_time_stamp;
1910 bool _failures;
1911
1912 public:
1913 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1914 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1915
1916 virtual bool do_heap_region(HeapRegion* hr) {
1917 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1918 if (_gc_time_stamp != region_gc_time_stamp) {
1919 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1920 region_gc_time_stamp, _gc_time_stamp);
1921 _failures = true;
1922 }
1923 return false;
1924 }
1925
1926 bool failures() { return _failures; }
1927 };
1928
1929 void G1CollectedHeap::check_gc_time_stamps() {
1930 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1931 heap_region_iterate(&cl);
1932 guarantee(!cl.failures(), "all GC time stamps should have been reset");
1933 }
1934 #endif // PRODUCT
1935
1936 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1937 _hot_card_cache->drain(cl, worker_i);
1938 }
1939
1940 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1941 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1942 size_t n_completed_buffers = 0;
1943 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1944 n_completed_buffers++;
1945 }
1946 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1947 dcqs.clear_n_completed_buffers();
1948 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1949 }
1950
1951 // Computes the sum of the storage used by the various regions.
1952 size_t G1CollectedHeap::used() const {
1953 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1954 if (_archive_allocator != NULL) {
1955 result += _archive_allocator->used();
1956 }
1957 return result;
1958 }
1959
1960 size_t G1CollectedHeap::used_unlocked() const {
1961 return _summary_bytes_used;
1962 }
1963
1964 class SumUsedClosure: public HeapRegionClosure {
1965 size_t _used;
1966 public:
1967 SumUsedClosure() : _used(0) {}
1968 bool do_heap_region(HeapRegion* r) {
1969 _used += r->used();
1970 return false;
1971 }
1972 size_t result() { return _used; }
1973 };
1974
1975 size_t G1CollectedHeap::recalculate_used() const {
1976 double recalculate_used_start = os::elapsedTime();
1977
1978 SumUsedClosure blk;
1979 heap_region_iterate(&blk);
1980
1981 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1982 return blk.result();
1983 }
1984
1985 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1986 switch (cause) {
1987 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1988 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1989 case GCCause::_wb_conc_mark: return true;
1990 default : return false;
1991 }
1992 }
1993
1994 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1995 switch (cause) {
1996 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1997 case GCCause::_g1_humongous_allocation: return true;
1998 default: return is_user_requested_concurrent_full_gc(cause);
1999 }
2000 }
2001
2002 #ifndef PRODUCT
2003 void G1CollectedHeap::allocate_dummy_regions() {
2004 // Let's fill up most of the region
2005 size_t word_size = HeapRegion::GrainWords - 1024;
2006 // And as a result the region we'll allocate will be humongous.
2007 guarantee(is_humongous(word_size), "sanity");
2008
2009 // _filler_array_max_size is set to humongous object threshold
2010 // but temporarily change it to use CollectedHeap::fill_with_object().
2011 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2012
2013 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2014 // Let's use the existing mechanism for the allocation
2015 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2016 if (dummy_obj != NULL) {
2017 MemRegion mr(dummy_obj, word_size);
2018 CollectedHeap::fill_with_object(mr);
2019 } else {
2020 // If we can't allocate once, we probably cannot allocate
2021 // again. Let's get out of the loop.
2022 break;
2023 }
2024 }
2025 }
2026 #endif // !PRODUCT
2027
2028 void G1CollectedHeap::increment_old_marking_cycles_started() {
2029 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2030 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2031 "Wrong marking cycle count (started: %d, completed: %d)",
2032 _old_marking_cycles_started, _old_marking_cycles_completed);
2033
2034 _old_marking_cycles_started++;
2035 }
2036
2037 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2038 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2039
2040 // We assume that if concurrent == true, then the caller is a
2041 // concurrent thread that was joined the Suspendible Thread
2042 // Set. If there's ever a cheap way to check this, we should add an
2043 // assert here.
2044
2045 // Given that this method is called at the end of a Full GC or of a
2046 // concurrent cycle, and those can be nested (i.e., a Full GC can
2047 // interrupt a concurrent cycle), the number of full collections
2048 // completed should be either one (in the case where there was no
2049 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2050 // behind the number of full collections started.
2051
2052 // This is the case for the inner caller, i.e. a Full GC.
2053 assert(concurrent ||
2054 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2055 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2056 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2057 "is inconsistent with _old_marking_cycles_completed = %u",
2058 _old_marking_cycles_started, _old_marking_cycles_completed);
2059
2060 // This is the case for the outer caller, i.e. the concurrent cycle.
2061 assert(!concurrent ||
2062 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2063 "for outer caller (concurrent cycle): "
2064 "_old_marking_cycles_started = %u "
2065 "is inconsistent with _old_marking_cycles_completed = %u",
2066 _old_marking_cycles_started, _old_marking_cycles_completed);
2067
2068 _old_marking_cycles_completed += 1;
2069
2070 // We need to clear the "in_progress" flag in the CM thread before
2071 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2072 // is set) so that if a waiter requests another System.gc() it doesn't
2073 // incorrectly see that a marking cycle is still in progress.
2074 if (concurrent) {
2075 _cmThread->set_idle();
2076 }
2077
2078 // This notify_all() will ensure that a thread that called
2079 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2080 // and it's waiting for a full GC to finish will be woken up. It is
2081 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2082 FullGCCount_lock->notify_all();
2083 }
2084
2085 void G1CollectedHeap::collect(GCCause::Cause cause) {
2086 assert_heap_not_locked();
2087
2088 uint gc_count_before;
2089 uint old_marking_count_before;
2090 uint full_gc_count_before;
2091 bool retry_gc;
2092
2093 do {
2094 retry_gc = false;
2095
2096 {
2097 MutexLocker ml(Heap_lock);
2098
2099 // Read the GC count while holding the Heap_lock
2100 gc_count_before = total_collections();
2101 full_gc_count_before = total_full_collections();
2102 old_marking_count_before = _old_marking_cycles_started;
2103 }
2104
2105 if (should_do_concurrent_full_gc(cause)) {
2106 // Schedule an initial-mark evacuation pause that will start a
2107 // concurrent cycle. We're setting word_size to 0 which means that
2108 // we are not requesting a post-GC allocation.
2109 VM_G1CollectForAllocation op(0, /* word_size */
2110 gc_count_before,
2111 cause,
2112 true, /* should_initiate_conc_mark */
2113 g1_policy()->max_pause_time_ms());
2114 VMThread::execute(&op);
2115 if (!op.pause_succeeded()) {
2116 if (old_marking_count_before == _old_marking_cycles_started) {
2117 retry_gc = op.should_retry_gc();
2118 } else {
2119 // A Full GC happened while we were trying to schedule the
2120 // initial-mark GC. No point in starting a new cycle given
2121 // that the whole heap was collected anyway.
2122 }
2123
2124 if (retry_gc) {
2125 if (GCLocker::is_active_and_needs_gc()) {
2126 GCLocker::stall_until_clear();
2127 }
2128 }
2129 }
2130 } else {
2131 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2132 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2133
2134 // Schedule a standard evacuation pause. We're setting word_size
2135 // to 0 which means that we are not requesting a post-GC allocation.
2136 VM_G1CollectForAllocation op(0, /* word_size */
2137 gc_count_before,
2138 cause,
2139 false, /* should_initiate_conc_mark */
2140 g1_policy()->max_pause_time_ms());
2141 VMThread::execute(&op);
2142 } else {
2143 // Schedule a Full GC.
2144 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2145 VMThread::execute(&op);
2146 }
2147 }
2148 } while (retry_gc);
2149 }
2150
2151 bool G1CollectedHeap::is_in(const void* p) const {
2152 if (_hrm.reserved().contains(p)) {
2153 // Given that we know that p is in the reserved space,
2154 // heap_region_containing() should successfully
2155 // return the containing region.
2156 HeapRegion* hr = heap_region_containing(p);
2157 return hr->is_in(p);
2158 } else {
2159 return false;
2160 }
2161 }
2162
2163 #ifdef ASSERT
2164 bool G1CollectedHeap::is_in_exact(const void* p) const {
2165 bool contains = reserved_region().contains(p);
2166 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2167 if (contains && available) {
2168 return true;
2169 } else {
2170 return false;
2171 }
2172 }
2173 #endif
2174
2175 // Iteration functions.
2176
2177 // Iterates an ObjectClosure over all objects within a HeapRegion.
2178
2179 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2180 ObjectClosure* _cl;
2181 public:
2182 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2183 bool do_heap_region(HeapRegion* r) {
2184 if (!r->is_continues_humongous()) {
2185 r->object_iterate(_cl);
2186 }
2187 return false;
2188 }
2189 };
2190
2191 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2192 IterateObjectClosureRegionClosure blk(cl);
2193 heap_region_iterate(&blk);
2194 }
2195
2196 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2197 _hrm.iterate(cl);
2198 }
2199
2200 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2201 HeapRegionClaimer *hrclaimer,
2202 uint worker_id) const {
2203 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2204 }
2205
2206 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2207 HeapRegionClaimer *hrclaimer) const {
2208 _hrm.par_iterate(cl, hrclaimer, 0);
2209 }
2210
2211 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2212 _collection_set.iterate(cl);
2213 }
2214
2215 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2216 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2217 }
2218
2219 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2220 HeapRegion* hr = heap_region_containing(addr);
2221 return hr->block_start(addr);
2222 }
2223
2224 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2225 HeapRegion* hr = heap_region_containing(addr);
2226 return hr->block_size(addr);
2227 }
2228
2229 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2230 HeapRegion* hr = heap_region_containing(addr);
2231 return hr->block_is_obj(addr);
2232 }
2233
2234 bool G1CollectedHeap::supports_tlab_allocation() const {
2235 return true;
2236 }
2237
2238 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2239 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2240 }
2241
2242 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2243 return _eden.length() * HeapRegion::GrainBytes;
2244 }
2245
2246 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2247 // must be equal to the humongous object limit.
2248 size_t G1CollectedHeap::max_tlab_size() const {
2249 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2250 }
2251
2252 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2253 return _allocator->unsafe_max_tlab_alloc();
2254 }
2255
2256 size_t G1CollectedHeap::max_capacity() const {
2257 return _hrm.reserved().byte_size();
2258 }
2259
2260 jlong G1CollectedHeap::millis_since_last_gc() {
2261 // See the notes in GenCollectedHeap::millis_since_last_gc()
2262 // for more information about the implementation.
2263 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2264 _g1_policy->collection_pause_end_millis();
2265 if (ret_val < 0) {
2266 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2267 ". returning zero instead.", ret_val);
2268 return 0;
2269 }
2270 return ret_val;
2271 }
2272
2273 void G1CollectedHeap::prepare_for_verify() {
2274 _verifier->prepare_for_verify();
2275 }
2276
2277 void G1CollectedHeap::verify(VerifyOption vo) {
2278 _verifier->verify(vo);
2279 }
2280
2281 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2282 return true;
2283 }
2284
2285 const char* const* G1CollectedHeap::concurrent_phases() const {
2286 return _cmThread->concurrent_phases();
2287 }
2288
2289 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2290 return _cmThread->request_concurrent_phase(phase);
2291 }
2292
2293 class PrintRegionClosure: public HeapRegionClosure {
2294 outputStream* _st;
2295 public:
2296 PrintRegionClosure(outputStream* st) : _st(st) {}
2297 bool do_heap_region(HeapRegion* r) {
2298 r->print_on(_st);
2299 return false;
2300 }
2301 };
2302
2303 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2304 const HeapRegion* hr,
2305 const VerifyOption vo) const {
2306 switch (vo) {
2307 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2308 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2309 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2310 default: ShouldNotReachHere();
2311 }
2312 return false; // keep some compilers happy
2313 }
2314
2315 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2316 const VerifyOption vo) const {
2317 switch (vo) {
2318 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2319 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2320 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2321 default: ShouldNotReachHere();
2322 }
2323 return false; // keep some compilers happy
2324 }
2325
2326 void G1CollectedHeap::print_heap_regions() const {
2327 LogTarget(Trace, gc, heap, region) lt;
2328 if (lt.is_enabled()) {
2329 LogStream ls(lt);
2330 print_regions_on(&ls);
2331 }
2332 }
2333
2334 void G1CollectedHeap::print_on(outputStream* st) const {
2335 st->print(" %-20s", "garbage-first heap");
2336 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2337 capacity()/K, used_unlocked()/K);
2338 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2339 p2i(_hrm.reserved().start()),
2340 p2i(_hrm.reserved().end()));
2341 st->cr();
2342 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2343 uint young_regions = young_regions_count();
2344 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2345 (size_t) young_regions * HeapRegion::GrainBytes / K);
2346 uint survivor_regions = survivor_regions_count();
2347 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2348 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2349 st->cr();
2350 MetaspaceUtils::print_on(st);
2351 }
2352
2353 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2354 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2355 "HS=humongous(starts), HC=humongous(continues), "
2356 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2357 "TAMS=top-at-mark-start (previous, next)");
2358 PrintRegionClosure blk(st);
2359 heap_region_iterate(&blk);
2360 }
2361
2362 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2363 print_on(st);
2364
2365 // Print the per-region information.
2366 print_regions_on(st);
2367 }
2368
2369 void G1CollectedHeap::print_on_error(outputStream* st) const {
2370 this->CollectedHeap::print_on_error(st);
2371
2372 if (_cm != NULL) {
2373 st->cr();
2374 _cm->print_on_error(st);
2375 }
2376 }
2377
2378 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2379 workers()->print_worker_threads_on(st);
2380 _cmThread->print_on(st);
2381 st->cr();
2382 _cm->print_worker_threads_on(st);
2383 _cr->print_threads_on(st);
2384 _young_gen_sampling_thread->print_on(st);
2385 if (G1StringDedup::is_enabled()) {
2386 G1StringDedup::print_worker_threads_on(st);
2387 }
2388 }
2389
2390 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2391 workers()->threads_do(tc);
2392 tc->do_thread(_cmThread);
2393 _cm->threads_do(tc);
2394 _cr->threads_do(tc);
2395 tc->do_thread(_young_gen_sampling_thread);
2396 if (G1StringDedup::is_enabled()) {
2397 G1StringDedup::threads_do(tc);
2398 }
2399 }
2400
2401 void G1CollectedHeap::print_tracing_info() const {
2402 g1_rem_set()->print_summary_info();
2403 concurrent_mark()->print_summary_info();
2404 }
2405
2406 #ifndef PRODUCT
2407 // Helpful for debugging RSet issues.
2408
2409 class PrintRSetsClosure : public HeapRegionClosure {
2410 private:
2411 const char* _msg;
2412 size_t _occupied_sum;
2413
2414 public:
2415 bool do_heap_region(HeapRegion* r) {
2416 HeapRegionRemSet* hrrs = r->rem_set();
2417 size_t occupied = hrrs->occupied();
2418 _occupied_sum += occupied;
2419
2420 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2421 if (occupied == 0) {
2422 tty->print_cr(" RSet is empty");
2423 } else {
2424 hrrs->print();
2425 }
2426 tty->print_cr("----------");
2427 return false;
2428 }
2429
2430 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2431 tty->cr();
2432 tty->print_cr("========================================");
2433 tty->print_cr("%s", msg);
2434 tty->cr();
2435 }
2436
2437 ~PrintRSetsClosure() {
2438 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2439 tty->print_cr("========================================");
2440 tty->cr();
2441 }
2442 };
2443
2444 void G1CollectedHeap::print_cset_rsets() {
2445 PrintRSetsClosure cl("Printing CSet RSets");
2446 collection_set_iterate(&cl);
2447 }
2448
2449 void G1CollectedHeap::print_all_rsets() {
2450 PrintRSetsClosure cl("Printing All RSets");;
2451 heap_region_iterate(&cl);
2452 }
2453 #endif // PRODUCT
2454
2455 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2456
2457 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2458 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2459 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2460
2461 size_t eden_capacity_bytes =
2462 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2463
2464 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2465 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2466 eden_capacity_bytes, survivor_used_bytes, num_regions());
2467 }
2468
2469 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2470 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2471 stats->unused(), stats->used(), stats->region_end_waste(),
2472 stats->regions_filled(), stats->direct_allocated(),
2473 stats->failure_used(), stats->failure_waste());
2474 }
2475
2476 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2477 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2478 gc_tracer->report_gc_heap_summary(when, heap_summary);
2479
2480 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2481 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2482 }
2483
2484 G1CollectedHeap* G1CollectedHeap::heap() {
2485 CollectedHeap* heap = Universe::heap();
2486 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2487 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2488 return (G1CollectedHeap*)heap;
2489 }
2490
2491 void G1CollectedHeap::gc_prologue(bool full) {
2492 // always_do_update_barrier = false;
2493 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2494
2495 // This summary needs to be printed before incrementing total collections.
2496 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2497
2498 // Update common counters.
2499 increment_total_collections(full /* full gc */);
2500 if (full) {
2501 increment_old_marking_cycles_started();
2502 reset_gc_time_stamp();
2503 } else {
2504 increment_gc_time_stamp();
2505 }
2506
2507 // Fill TLAB's and such
2508 double start = os::elapsedTime();
2509 accumulate_statistics_all_tlabs();
2510 ensure_parsability(true);
2511 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2512 }
2513
2514 void G1CollectedHeap::gc_epilogue(bool full) {
2515 // Update common counters.
2516 if (full) {
2517 // Update the number of full collections that have been completed.
2518 increment_old_marking_cycles_completed(false /* concurrent */);
2519 }
2520
2521 // We are at the end of the GC. Total collections has already been increased.
2522 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2523
2524 // FIXME: what is this about?
2525 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2526 // is set.
2527 #if COMPILER2_OR_JVMCI
2528 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2529 #endif
2530 // always_do_update_barrier = true;
2531
2532 double start = os::elapsedTime();
2533 resize_all_tlabs();
2534 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2535
2536 MemoryService::track_memory_usage();
2537 // We have just completed a GC. Update the soft reference
2538 // policy with the new heap occupancy
2539 Universe::update_heap_info_at_gc();
2540 }
2541
2542 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2543 uint gc_count_before,
2544 bool* succeeded,
2545 GCCause::Cause gc_cause) {
2546 assert_heap_not_locked_and_not_at_safepoint();
2547 VM_G1CollectForAllocation op(word_size,
2548 gc_count_before,
2549 gc_cause,
2550 false, /* should_initiate_conc_mark */
2551 g1_policy()->max_pause_time_ms());
2552 VMThread::execute(&op);
2553
2554 HeapWord* result = op.result();
2555 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2556 assert(result == NULL || ret_succeeded,
2557 "the result should be NULL if the VM did not succeed");
2558 *succeeded = ret_succeeded;
2559
2560 assert_heap_not_locked();
2561 return result;
2562 }
2563
2564 void
2565 G1CollectedHeap::doConcurrentMark() {
2566 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2567 if (!_cmThread->in_progress()) {
2568 _cmThread->set_started();
2569 CGC_lock->notify();
2570 }
2571 }
2572
2573 size_t G1CollectedHeap::pending_card_num() {
2574 size_t extra_cards = 0;
2575 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2576 DirtyCardQueue& dcq = curr->dirty_card_queue();
2577 extra_cards += dcq.size();
2578 }
2579 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2580 size_t buffer_size = dcqs.buffer_size();
2581 size_t buffer_num = dcqs.completed_buffers_num();
2582
2583 return buffer_size * buffer_num + extra_cards;
2584 }
2585
2586 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2587 private:
2588 size_t _total_humongous;
2589 size_t _candidate_humongous;
2590
2591 DirtyCardQueue _dcq;
2592
2593 // We don't nominate objects with many remembered set entries, on
2594 // the assumption that such objects are likely still live.
2595 bool is_remset_small(HeapRegion* region) const {
2596 HeapRegionRemSet* const rset = region->rem_set();
2597 return G1EagerReclaimHumongousObjectsWithStaleRefs
2598 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2599 : rset->is_empty();
2600 }
2601
2602 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2603 assert(region->is_starts_humongous(), "Must start a humongous object");
2604
2605 oop obj = oop(region->bottom());
2606
2607 // Dead objects cannot be eager reclaim candidates. Due to class
2608 // unloading it is unsafe to query their classes so we return early.
2609 if (heap->is_obj_dead(obj, region)) {
2610 return false;
2611 }
2612
2613 // Candidate selection must satisfy the following constraints
2614 // while concurrent marking is in progress:
2615 //
2616 // * In order to maintain SATB invariants, an object must not be
2617 // reclaimed if it was allocated before the start of marking and
2618 // has not had its references scanned. Such an object must have
2619 // its references (including type metadata) scanned to ensure no
2620 // live objects are missed by the marking process. Objects
2621 // allocated after the start of concurrent marking don't need to
2622 // be scanned.
2623 //
2624 // * An object must not be reclaimed if it is on the concurrent
2625 // mark stack. Objects allocated after the start of concurrent
2626 // marking are never pushed on the mark stack.
2627 //
2628 // Nominating only objects allocated after the start of concurrent
2629 // marking is sufficient to meet both constraints. This may miss
2630 // some objects that satisfy the constraints, but the marking data
2631 // structures don't support efficiently performing the needed
2632 // additional tests or scrubbing of the mark stack.
2633 //
2634 // However, we presently only nominate is_typeArray() objects.
2635 // A humongous object containing references induces remembered
2636 // set entries on other regions. In order to reclaim such an
2637 // object, those remembered sets would need to be cleaned up.
2638 //
2639 // We also treat is_typeArray() objects specially, allowing them
2640 // to be reclaimed even if allocated before the start of
2641 // concurrent mark. For this we rely on mark stack insertion to
2642 // exclude is_typeArray() objects, preventing reclaiming an object
2643 // that is in the mark stack. We also rely on the metadata for
2644 // such objects to be built-in and so ensured to be kept live.
2645 // Frequent allocation and drop of large binary blobs is an
2646 // important use case for eager reclaim, and this special handling
2647 // may reduce needed headroom.
2648
2649 return obj->is_typeArray() && is_remset_small(region);
2650 }
2651
2652 public:
2653 RegisterHumongousWithInCSetFastTestClosure()
2654 : _total_humongous(0),
2655 _candidate_humongous(0),
2656 _dcq(&JavaThread::dirty_card_queue_set()) {
2657 }
2658
2659 virtual bool do_heap_region(HeapRegion* r) {
2660 if (!r->is_starts_humongous()) {
2661 return false;
2662 }
2663 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2664
2665 bool is_candidate = humongous_region_is_candidate(g1h, r);
2666 uint rindex = r->hrm_index();
2667 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2668 if (is_candidate) {
2669 _candidate_humongous++;
2670 g1h->register_humongous_region_with_cset(rindex);
2671 // Is_candidate already filters out humongous object with large remembered sets.
2672 // If we have a humongous object with a few remembered sets, we simply flush these
2673 // remembered set entries into the DCQS. That will result in automatic
2674 // re-evaluation of their remembered set entries during the following evacuation
2675 // phase.
2676 if (!r->rem_set()->is_empty()) {
2677 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2678 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2679 G1CardTable* ct = g1h->card_table();
2680 HeapRegionRemSetIterator hrrs(r->rem_set());
2681 size_t card_index;
2682 while (hrrs.has_next(card_index)) {
2683 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2684 // The remembered set might contain references to already freed
2685 // regions. Filter out such entries to avoid failing card table
2686 // verification.
2687 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2688 if (*card_ptr != G1CardTable::dirty_card_val()) {
2689 *card_ptr = G1CardTable::dirty_card_val();
2690 _dcq.enqueue(card_ptr);
2691 }
2692 }
2693 }
2694 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2695 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2696 hrrs.n_yielded(), r->rem_set()->occupied());
2697 r->rem_set()->clear_locked();
2698 }
2699 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2700 }
2701 _total_humongous++;
2702
2703 return false;
2704 }
2705
2706 size_t total_humongous() const { return _total_humongous; }
2707 size_t candidate_humongous() const { return _candidate_humongous; }
2708
2709 void flush_rem_set_entries() { _dcq.flush(); }
2710 };
2711
2712 void G1CollectedHeap::register_humongous_regions_with_cset() {
2713 if (!G1EagerReclaimHumongousObjects) {
2714 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2715 return;
2716 }
2717 double time = os::elapsed_counter();
2718
2719 // Collect reclaim candidate information and register candidates with cset.
2720 RegisterHumongousWithInCSetFastTestClosure cl;
2721 heap_region_iterate(&cl);
2722
2723 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2724 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2725 cl.total_humongous(),
2726 cl.candidate_humongous());
2727 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2728
2729 // Finally flush all remembered set entries to re-check into the global DCQS.
2730 cl.flush_rem_set_entries();
2731 }
2732
2733 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2734 public:
2735 bool do_heap_region(HeapRegion* hr) {
2736 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2737 hr->verify_rem_set();
2738 }
2739 return false;
2740 }
2741 };
2742
2743 uint G1CollectedHeap::num_task_queues() const {
2744 return _task_queues->size();
2745 }
2746
2747 #if TASKQUEUE_STATS
2748 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2749 st->print_raw_cr("GC Task Stats");
2750 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2751 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2752 }
2753
2754 void G1CollectedHeap::print_taskqueue_stats() const {
2755 if (!log_is_enabled(Trace, gc, task, stats)) {
2756 return;
2757 }
2758 Log(gc, task, stats) log;
2759 ResourceMark rm;
2760 LogStream ls(log.trace());
2761 outputStream* st = &ls;
2762
2763 print_taskqueue_stats_hdr(st);
2764
2765 TaskQueueStats totals;
2766 const uint n = num_task_queues();
2767 for (uint i = 0; i < n; ++i) {
2768 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2769 totals += task_queue(i)->stats;
2770 }
2771 st->print_raw("tot "); totals.print(st); st->cr();
2772
2773 DEBUG_ONLY(totals.verify());
2774 }
2775
2776 void G1CollectedHeap::reset_taskqueue_stats() {
2777 const uint n = num_task_queues();
2778 for (uint i = 0; i < n; ++i) {
2779 task_queue(i)->stats.reset();
2780 }
2781 }
2782 #endif // TASKQUEUE_STATS
2783
2784 void G1CollectedHeap::wait_for_root_region_scanning() {
2785 double scan_wait_start = os::elapsedTime();
2786 // We have to wait until the CM threads finish scanning the
2787 // root regions as it's the only way to ensure that all the
2788 // objects on them have been correctly scanned before we start
2789 // moving them during the GC.
2790 bool waited = _cm->root_regions()->wait_until_scan_finished();
2791 double wait_time_ms = 0.0;
2792 if (waited) {
2793 double scan_wait_end = os::elapsedTime();
2794 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2795 }
2796 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2797 }
2798
2799 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2800 private:
2801 G1HRPrinter* _hr_printer;
2802 public:
2803 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2804
2805 virtual bool do_heap_region(HeapRegion* r) {
2806 _hr_printer->cset(r);
2807 return false;
2808 }
2809 };
2810
2811 void G1CollectedHeap::start_new_collection_set() {
2812 collection_set()->start_incremental_building();
2813
2814 clear_cset_fast_test();
2815
2816 guarantee(_eden.length() == 0, "eden should have been cleared");
2817 g1_policy()->transfer_survivors_to_cset(survivor());
2818 }
2819
2820 bool
2821 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2822 assert_at_safepoint_on_vm_thread();
2823 guarantee(!is_gc_active(), "collection is not reentrant");
2824
2825 if (GCLocker::check_active_before_gc()) {
2826 return false;
2827 }
2828
2829 _gc_timer_stw->register_gc_start();
2830
2831 GCIdMark gc_id_mark;
2832 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2833
2834 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2835 ResourceMark rm;
2836
2837 g1_policy()->note_gc_start();
2838
2839 wait_for_root_region_scanning();
2840
2841 print_heap_before_gc();
2842 print_heap_regions();
2843 trace_heap_before_gc(_gc_tracer_stw);
2844
2845 _verifier->verify_region_sets_optional();
2846 _verifier->verify_dirty_young_regions();
2847
2848 // We should not be doing initial mark unless the conc mark thread is running
2849 if (!_cmThread->should_terminate()) {
2850 // This call will decide whether this pause is an initial-mark
2851 // pause. If it is, during_initial_mark_pause() will return true
2852 // for the duration of this pause.
2853 g1_policy()->decide_on_conc_mark_initiation();
2854 }
2855
2856 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2857 assert(!collector_state()->during_initial_mark_pause() ||
2858 collector_state()->gcs_are_young(), "sanity");
2859
2860 // We also do not allow mixed GCs during marking.
2861 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2862
2863 // Record whether this pause is an initial mark. When the current
2864 // thread has completed its logging output and it's safe to signal
2865 // the CM thread, the flag's value in the policy has been reset.
2866 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2867
2868 // Inner scope for scope based logging, timers, and stats collection
2869 {
2870 EvacuationInfo evacuation_info;
2871
2872 if (collector_state()->during_initial_mark_pause()) {
2873 // We are about to start a marking cycle, so we increment the
2874 // full collection counter.
2875 increment_old_marking_cycles_started();
2876 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2877 }
2878
2879 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2880
2881 GCTraceCPUTime tcpu;
2882
2883 G1HeapVerifier::G1VerifyType verify_type;
2884 FormatBuffer<> gc_string("Pause ");
2885 if (collector_state()->during_initial_mark_pause()) {
2886 gc_string.append("Initial Mark");
2887 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2888 } else if (collector_state()->gcs_are_young()) {
2889 gc_string.append("Young");
2890 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2891 } else {
2892 gc_string.append("Mixed");
2893 verify_type = G1HeapVerifier::G1VerifyMixed;
2894 }
2895 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2896
2897 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2898 workers()->active_workers(),
2899 Threads::number_of_non_daemon_threads());
2900 workers()->update_active_workers(active_workers);
2901 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2902
2903 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2904 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2905
2906 // If the secondary_free_list is not empty, append it to the
2907 // free_list. No need to wait for the cleanup operation to finish;
2908 // the region allocation code will check the secondary_free_list
2909 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2910 // set, skip this step so that the region allocation code has to
2911 // get entries from the secondary_free_list.
2912 if (!G1StressConcRegionFreeing) {
2913 append_secondary_free_list_if_not_empty_with_lock();
2914 }
2915
2916 G1HeapTransition heap_transition(this);
2917 size_t heap_used_bytes_before_gc = used();
2918
2919 // Don't dynamically change the number of GC threads this early. A value of
2920 // 0 is used to indicate serial work. When parallel work is done,
2921 // it will be set.
2922
2923 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2924 IsGCActiveMark x;
2925
2926 gc_prologue(false);
2927
2928 if (VerifyRememberedSets) {
2929 log_info(gc, verify)("[Verifying RemSets before GC]");
2930 VerifyRegionRemSetClosure v_cl;
2931 heap_region_iterate(&v_cl);
2932 }
2933
2934 _verifier->verify_before_gc(verify_type);
2935
2936 _verifier->check_bitmaps("GC Start");
2937
2938 #if COMPILER2_OR_JVMCI
2939 DerivedPointerTable::clear();
2940 #endif
2941
2942 // Please see comment in g1CollectedHeap.hpp and
2943 // G1CollectedHeap::ref_processing_init() to see how
2944 // reference processing currently works in G1.
2945
2946 // Enable discovery in the STW reference processor
2947 if (g1_policy()->should_process_references()) {
2948 ref_processor_stw()->enable_discovery();
2949 } else {
2950 ref_processor_stw()->disable_discovery();
2951 }
2952
2953 {
2954 // We want to temporarily turn off discovery by the
2955 // CM ref processor, if necessary, and turn it back on
2956 // on again later if we do. Using a scoped
2957 // NoRefDiscovery object will do this.
2958 NoRefDiscovery no_cm_discovery(ref_processor_cm());
2959
2960 // Forget the current alloc region (we might even choose it to be part
2961 // of the collection set!).
2962 _allocator->release_mutator_alloc_region();
2963
2964 // This timing is only used by the ergonomics to handle our pause target.
2965 // It is unclear why this should not include the full pause. We will
2966 // investigate this in CR 7178365.
2967 //
2968 // Preserving the old comment here if that helps the investigation:
2969 //
2970 // The elapsed time induced by the start time below deliberately elides
2971 // the possible verification above.
2972 double sample_start_time_sec = os::elapsedTime();
2973
2974 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2975
2976 if (collector_state()->during_initial_mark_pause()) {
2977 concurrent_mark()->checkpoint_roots_initial_pre();
2978 }
2979
2980 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2981
2982 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2983
2984 // Make sure the remembered sets are up to date. This needs to be
2985 // done before register_humongous_regions_with_cset(), because the
2986 // remembered sets are used there to choose eager reclaim candidates.
2987 // If the remembered sets are not up to date we might miss some
2988 // entries that need to be handled.
2989 g1_rem_set()->cleanupHRRS();
2990
2991 register_humongous_regions_with_cset();
2992
2993 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2994
2995 // We call this after finalize_cset() to
2996 // ensure that the CSet has been finalized.
2997 _cm->verify_no_cset_oops();
2998
2999 if (_hr_printer.is_active()) {
3000 G1PrintCollectionSetClosure cl(&_hr_printer);
3001 _collection_set.iterate(&cl);
3002 }
3003
3004 // Initialize the GC alloc regions.
3005 _allocator->init_gc_alloc_regions(evacuation_info);
3006
3007 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3008 pre_evacuate_collection_set();
3009
3010 // Actually do the work...
3011 evacuate_collection_set(&per_thread_states);
3012
3013 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3014
3015 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3016 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3017
3018 eagerly_reclaim_humongous_regions();
3019
3020 record_obj_copy_mem_stats();
3021 _survivor_evac_stats.adjust_desired_plab_sz();
3022 _old_evac_stats.adjust_desired_plab_sz();
3023
3024 double start = os::elapsedTime();
3025 start_new_collection_set();
3026 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3027
3028 if (evacuation_failed()) {
3029 set_used(recalculate_used());
3030 if (_archive_allocator != NULL) {
3031 _archive_allocator->clear_used();
3032 }
3033 for (uint i = 0; i < ParallelGCThreads; i++) {
3034 if (_evacuation_failed_info_array[i].has_failed()) {
3035 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3036 }
3037 }
3038 } else {
3039 // The "used" of the the collection set have already been subtracted
3040 // when they were freed. Add in the bytes evacuated.
3041 increase_used(g1_policy()->bytes_copied_during_gc());
3042 }
3043
3044 if (collector_state()->during_initial_mark_pause()) {
3045 // We have to do this before we notify the CM threads that
3046 // they can start working to make sure that all the
3047 // appropriate initialization is done on the CM object.
3048 concurrent_mark()->checkpoint_roots_initial_post();
3049 collector_state()->set_mark_in_progress(true);
3050 // Note that we don't actually trigger the CM thread at
3051 // this point. We do that later when we're sure that
3052 // the current thread has completed its logging output.
3053 }
3054
3055 allocate_dummy_regions();
3056
3057 _allocator->init_mutator_alloc_region();
3058
3059 {
3060 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3061 if (expand_bytes > 0) {
3062 size_t bytes_before = capacity();
3063 // No need for an ergo logging here,
3064 // expansion_amount() does this when it returns a value > 0.
3065 double expand_ms;
3066 if (!expand(expand_bytes, _workers, &expand_ms)) {
3067 // We failed to expand the heap. Cannot do anything about it.
3068 }
3069 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3070 }
3071 }
3072
3073 // We redo the verification but now wrt to the new CSet which
3074 // has just got initialized after the previous CSet was freed.
3075 _cm->verify_no_cset_oops();
3076
3077 // This timing is only used by the ergonomics to handle our pause target.
3078 // It is unclear why this should not include the full pause. We will
3079 // investigate this in CR 7178365.
3080 double sample_end_time_sec = os::elapsedTime();
3081 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3082 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3083 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3084
3085 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3086 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3087
3088 if (VerifyRememberedSets) {
3089 log_info(gc, verify)("[Verifying RemSets after GC]");
3090 VerifyRegionRemSetClosure v_cl;
3091 heap_region_iterate(&v_cl);
3092 }
3093
3094 _verifier->verify_after_gc(verify_type);
3095 _verifier->check_bitmaps("GC End");
3096
3097 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3098 ref_processor_stw()->verify_no_references_recorded();
3099
3100 // CM reference discovery will be re-enabled if necessary.
3101 }
3102
3103 #ifdef TRACESPINNING
3104 ParallelTaskTerminator::print_termination_counts();
3105 #endif
3106
3107 gc_epilogue(false);
3108 }
3109
3110 // Print the remainder of the GC log output.
3111 if (evacuation_failed()) {
3112 log_info(gc)("To-space exhausted");
3113 }
3114
3115 g1_policy()->print_phases();
3116 heap_transition.print();
3117
3118 // It is not yet to safe to tell the concurrent mark to
3119 // start as we have some optional output below. We don't want the
3120 // output from the concurrent mark thread interfering with this
3121 // logging output either.
3122
3123 _hrm.verify_optional();
3124 _verifier->verify_region_sets_optional();
3125
3126 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3127 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3128
3129 print_heap_after_gc();
3130 print_heap_regions();
3131 trace_heap_after_gc(_gc_tracer_stw);
3132
3133 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3134 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3135 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3136 // before any GC notifications are raised.
3137 g1mm()->update_sizes();
3138
3139 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3140 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3141 _gc_timer_stw->register_gc_end();
3142 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3143 }
3144 // It should now be safe to tell the concurrent mark thread to start
3145 // without its logging output interfering with the logging output
3146 // that came from the pause.
3147
3148 if (should_start_conc_mark) {
3149 // CAUTION: after the doConcurrentMark() call below,
3150 // the concurrent marking thread(s) could be running
3151 // concurrently with us. Make sure that anything after
3152 // this point does not assume that we are the only GC thread
3153 // running. Note: of course, the actual marking work will
3154 // not start until the safepoint itself is released in
3155 // SuspendibleThreadSet::desynchronize().
3156 doConcurrentMark();
3157 }
3158
3159 return true;
3160 }
3161
3162 void G1CollectedHeap::remove_self_forwarding_pointers() {
3163 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3164 workers()->run_task(&rsfp_task);
3165 }
3166
3167 void G1CollectedHeap::restore_after_evac_failure() {
3168 double remove_self_forwards_start = os::elapsedTime();
3169
3170 remove_self_forwarding_pointers();
3171 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3172 _preserved_marks_set.restore(&task_executor);
3173
3174 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3175 }
3176
3177 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3178 if (!_evacuation_failed) {
3179 _evacuation_failed = true;
3180 }
3181
3182 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3183 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3184 }
3185
3186 bool G1ParEvacuateFollowersClosure::offer_termination() {
3187 G1ParScanThreadState* const pss = par_scan_state();
3188 start_term_time();
3189 const bool res = terminator()->offer_termination();
3190 end_term_time();
3191 return res;
3192 }
3193
3194 void G1ParEvacuateFollowersClosure::do_void() {
3195 G1ParScanThreadState* const pss = par_scan_state();
3196 pss->trim_queue();
3197 do {
3198 pss->steal_and_trim_queue(queues());
3199 } while (!offer_termination());
3200 }
3201
3202 class G1ParTask : public AbstractGangTask {
3203 protected:
3204 G1CollectedHeap* _g1h;
3205 G1ParScanThreadStateSet* _pss;
3206 RefToScanQueueSet* _queues;
3207 G1RootProcessor* _root_processor;
3208 ParallelTaskTerminator _terminator;
3209 uint _n_workers;
3210
3211 public:
3212 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3213 : AbstractGangTask("G1 collection"),
3214 _g1h(g1h),
3215 _pss(per_thread_states),
3216 _queues(task_queues),
3217 _root_processor(root_processor),
3218 _terminator(n_workers, _queues),
3219 _n_workers(n_workers)
3220 {}
3221
3222 void work(uint worker_id) {
3223 if (worker_id >= _n_workers) return; // no work needed this round
3224
3225 double start_sec = os::elapsedTime();
3226 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3227
3228 {
3229 ResourceMark rm;
3230 HandleMark hm;
3231
3232 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3233
3234 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3235 pss->set_ref_processor(rp);
3236
3237 double start_strong_roots_sec = os::elapsedTime();
3238
3239 _root_processor->evacuate_roots(pss->closures(), worker_id);
3240
3241 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3242 // treating the nmethods visited to act as roots for concurrent marking.
3243 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3244 // objects copied by the current evacuation.
3245 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3246 pss->closures()->weak_codeblobs(),
3247 worker_id);
3248
3249 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3250
3251 double term_sec = 0.0;
3252 size_t evac_term_attempts = 0;
3253 {
3254 double start = os::elapsedTime();
3255 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3256 evac.do_void();
3257
3258 evac_term_attempts = evac.term_attempts();
3259 term_sec = evac.term_time();
3260 double elapsed_sec = os::elapsedTime() - start;
3261 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3262 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3263 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3264 }
3265
3266 assert(pss->queue_is_empty(), "should be empty");
3267
3268 if (log_is_enabled(Debug, gc, task, stats)) {
3269 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3270 size_t lab_waste;
3271 size_t lab_undo_waste;
3272 pss->waste(lab_waste, lab_undo_waste);
3273 _g1h->print_termination_stats(worker_id,
3274 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3275 strong_roots_sec * 1000.0, /* strong roots time */
3276 term_sec * 1000.0, /* evac term time */
3277 evac_term_attempts, /* evac term attempts */
3278 lab_waste, /* alloc buffer waste */
3279 lab_undo_waste /* undo waste */
3280 );
3281 }
3282
3283 // Close the inner scope so that the ResourceMark and HandleMark
3284 // destructors are executed here and are included as part of the
3285 // "GC Worker Time".
3286 }
3287 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3288 }
3289 };
3290
3291 void G1CollectedHeap::print_termination_stats_hdr() {
3292 log_debug(gc, task, stats)("GC Termination Stats");
3293 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3294 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3295 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3296 }
3297
3298 void G1CollectedHeap::print_termination_stats(uint worker_id,
3299 double elapsed_ms,
3300 double strong_roots_ms,
3301 double term_ms,
3302 size_t term_attempts,
3303 size_t alloc_buffer_waste,
3304 size_t undo_waste) const {
3305 log_debug(gc, task, stats)
3306 ("%3d %9.2f %9.2f %6.2f "
3307 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3308 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3309 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3310 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3311 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3312 alloc_buffer_waste * HeapWordSize / K,
3313 undo_waste * HeapWordSize / K);
3314 }
3315
3316 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3317 private:
3318 BoolObjectClosure* _is_alive;
3319 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3320
3321 int _initial_string_table_size;
3322 int _initial_symbol_table_size;
3323
3324 bool _process_strings;
3325 int _strings_processed;
3326 int _strings_removed;
3327
3328 bool _process_symbols;
3329 int _symbols_processed;
3330 int _symbols_removed;
3331
3332 bool _process_string_dedup;
3333
3334 public:
3335 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3336 AbstractGangTask("String/Symbol Unlinking"),
3337 _is_alive(is_alive),
3338 _dedup_closure(is_alive, NULL, false),
3339 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3340 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3341 _process_string_dedup(process_string_dedup) {
3342
3343 _initial_string_table_size = StringTable::the_table()->table_size();
3344 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3345 if (process_strings) {
3346 StringTable::clear_parallel_claimed_index();
3347 }
3348 if (process_symbols) {
3349 SymbolTable::clear_parallel_claimed_index();
3350 }
3351 }
3352
3353 ~G1StringAndSymbolCleaningTask() {
3354 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3355 "claim value %d after unlink less than initial string table size %d",
3356 StringTable::parallel_claimed_index(), _initial_string_table_size);
3357 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3358 "claim value %d after unlink less than initial symbol table size %d",
3359 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3360
3361 log_info(gc, stringtable)(
3362 "Cleaned string and symbol table, "
3363 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3364 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3365 strings_processed(), strings_removed(),
3366 symbols_processed(), symbols_removed());
3367 }
3368
3369 void work(uint worker_id) {
3370 int strings_processed = 0;
3371 int strings_removed = 0;
3372 int symbols_processed = 0;
3373 int symbols_removed = 0;
3374 if (_process_strings) {
3375 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3376 Atomic::add(strings_processed, &_strings_processed);
3377 Atomic::add(strings_removed, &_strings_removed);
3378 }
3379 if (_process_symbols) {
3380 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3381 Atomic::add(symbols_processed, &_symbols_processed);
3382 Atomic::add(symbols_removed, &_symbols_removed);
3383 }
3384 if (_process_string_dedup) {
3385 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3386 }
3387 }
3388
3389 size_t strings_processed() const { return (size_t)_strings_processed; }
3390 size_t strings_removed() const { return (size_t)_strings_removed; }
3391
3392 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3393 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3394 };
3395
3396 class G1CodeCacheUnloadingTask {
3397 private:
3398 static Monitor* _lock;
3399
3400 BoolObjectClosure* const _is_alive;
3401 const bool _unloading_occurred;
3402 const uint _num_workers;
3403
3404 // Variables used to claim nmethods.
3405 CompiledMethod* _first_nmethod;
3406 CompiledMethod* volatile _claimed_nmethod;
3407
3408 // The list of nmethods that need to be processed by the second pass.
3409 CompiledMethod* volatile _postponed_list;
3410 volatile uint _num_entered_barrier;
3411
3412 public:
3413 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3414 _is_alive(is_alive),
3415 _unloading_occurred(unloading_occurred),
3416 _num_workers(num_workers),
3417 _first_nmethod(NULL),
3418 _claimed_nmethod(NULL),
3419 _postponed_list(NULL),
3420 _num_entered_barrier(0)
3421 {
3422 CompiledMethod::increase_unloading_clock();
3423 // Get first alive nmethod
3424 CompiledMethodIterator iter = CompiledMethodIterator();
3425 if(iter.next_alive()) {
3426 _first_nmethod = iter.method();
3427 }
3428 _claimed_nmethod = _first_nmethod;
3429 }
3430
3431 ~G1CodeCacheUnloadingTask() {
3432 CodeCache::verify_clean_inline_caches();
3433
3434 CodeCache::set_needs_cache_clean(false);
3435 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3436
3437 CodeCache::verify_icholder_relocations();
3438 }
3439
3440 private:
3441 void add_to_postponed_list(CompiledMethod* nm) {
3442 CompiledMethod* old;
3443 do {
3444 old = _postponed_list;
3445 nm->set_unloading_next(old);
3446 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3447 }
3448
3449 void clean_nmethod(CompiledMethod* nm) {
3450 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3451
3452 if (postponed) {
3453 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3454 add_to_postponed_list(nm);
3455 }
3456
3457 // Mark that this thread has been cleaned/unloaded.
3458 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3459 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3460 }
3461
3462 void clean_nmethod_postponed(CompiledMethod* nm) {
3463 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3464 }
3465
3466 static const int MaxClaimNmethods = 16;
3467
3468 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3469 CompiledMethod* first;
3470 CompiledMethodIterator last;
3471
3472 do {
3473 *num_claimed_nmethods = 0;
3474
3475 first = _claimed_nmethod;
3476 last = CompiledMethodIterator(first);
3477
3478 if (first != NULL) {
3479
3480 for (int i = 0; i < MaxClaimNmethods; i++) {
3481 if (!last.next_alive()) {
3482 break;
3483 }
3484 claimed_nmethods[i] = last.method();
3485 (*num_claimed_nmethods)++;
3486 }
3487 }
3488
3489 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3490 }
3491
3492 CompiledMethod* claim_postponed_nmethod() {
3493 CompiledMethod* claim;
3494 CompiledMethod* next;
3495
3496 do {
3497 claim = _postponed_list;
3498 if (claim == NULL) {
3499 return NULL;
3500 }
3501
3502 next = claim->unloading_next();
3503
3504 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3505
3506 return claim;
3507 }
3508
3509 public:
3510 // Mark that we're done with the first pass of nmethod cleaning.
3511 void barrier_mark(uint worker_id) {
3512 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3513 _num_entered_barrier++;
3514 if (_num_entered_barrier == _num_workers) {
3515 ml.notify_all();
3516 }
3517 }
3518
3519 // See if we have to wait for the other workers to
3520 // finish their first-pass nmethod cleaning work.
3521 void barrier_wait(uint worker_id) {
3522 if (_num_entered_barrier < _num_workers) {
3523 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3524 while (_num_entered_barrier < _num_workers) {
3525 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3526 }
3527 }
3528 }
3529
3530 // Cleaning and unloading of nmethods. Some work has to be postponed
3531 // to the second pass, when we know which nmethods survive.
3532 void work_first_pass(uint worker_id) {
3533 // The first nmethods is claimed by the first worker.
3534 if (worker_id == 0 && _first_nmethod != NULL) {
3535 clean_nmethod(_first_nmethod);
3536 _first_nmethod = NULL;
3537 }
3538
3539 int num_claimed_nmethods;
3540 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3541
3542 while (true) {
3543 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3544
3545 if (num_claimed_nmethods == 0) {
3546 break;
3547 }
3548
3549 for (int i = 0; i < num_claimed_nmethods; i++) {
3550 clean_nmethod(claimed_nmethods[i]);
3551 }
3552 }
3553 }
3554
3555 void work_second_pass(uint worker_id) {
3556 CompiledMethod* nm;
3557 // Take care of postponed nmethods.
3558 while ((nm = claim_postponed_nmethod()) != NULL) {
3559 clean_nmethod_postponed(nm);
3560 }
3561 }
3562 };
3563
3564 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3565
3566 class G1KlassCleaningTask : public StackObj {
3567 BoolObjectClosure* _is_alive;
3568 volatile int _clean_klass_tree_claimed;
3569 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3570
3571 public:
3572 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3573 _is_alive(is_alive),
3574 _clean_klass_tree_claimed(0),
3575 _klass_iterator() {
3576 }
3577
3578 private:
3579 bool claim_clean_klass_tree_task() {
3580 if (_clean_klass_tree_claimed) {
3581 return false;
3582 }
3583
3584 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3585 }
3586
3587 InstanceKlass* claim_next_klass() {
3588 Klass* klass;
3589 do {
3590 klass =_klass_iterator.next_klass();
3591 } while (klass != NULL && !klass->is_instance_klass());
3592
3593 // this can be null so don't call InstanceKlass::cast
3594 return static_cast<InstanceKlass*>(klass);
3595 }
3596
3597 public:
3598
3599 void clean_klass(InstanceKlass* ik) {
3600 ik->clean_weak_instanceklass_links(_is_alive);
3601 }
3602
3603 void work() {
3604 ResourceMark rm;
3605
3606 // One worker will clean the subklass/sibling klass tree.
3607 if (claim_clean_klass_tree_task()) {
3608 Klass::clean_subklass_tree(_is_alive);
3609 }
3610
3611 // All workers will help cleaning the classes,
3612 InstanceKlass* klass;
3613 while ((klass = claim_next_klass()) != NULL) {
3614 clean_klass(klass);
3615 }
3616 }
3617 };
3618
3619 class G1ResolvedMethodCleaningTask : public StackObj {
3620 BoolObjectClosure* _is_alive;
3621 volatile int _resolved_method_task_claimed;
3622 public:
3623 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3624 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3625
3626 bool claim_resolved_method_task() {
3627 if (_resolved_method_task_claimed) {
3628 return false;
3629 }
3630 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3631 }
3632
3633 // These aren't big, one thread can do it all.
3634 void work() {
3635 if (claim_resolved_method_task()) {
3636 ResolvedMethodTable::unlink(_is_alive);
3637 }
3638 }
3639 };
3640
3641
3642 // To minimize the remark pause times, the tasks below are done in parallel.
3643 class G1ParallelCleaningTask : public AbstractGangTask {
3644 private:
3645 G1StringAndSymbolCleaningTask _string_symbol_task;
3646 G1CodeCacheUnloadingTask _code_cache_task;
3647 G1KlassCleaningTask _klass_cleaning_task;
3648 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3649
3650 public:
3651 // The constructor is run in the VMThread.
3652 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3653 AbstractGangTask("Parallel Cleaning"),
3654 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3655 _code_cache_task(num_workers, is_alive, unloading_occurred),
3656 _klass_cleaning_task(is_alive),
3657 _resolved_method_cleaning_task(is_alive) {
3658 }
3659
3660 // The parallel work done by all worker threads.
3661 void work(uint worker_id) {
3662 // Do first pass of code cache cleaning.
3663 _code_cache_task.work_first_pass(worker_id);
3664
3665 // Let the threads mark that the first pass is done.
3666 _code_cache_task.barrier_mark(worker_id);
3667
3668 // Clean the Strings and Symbols.
3669 _string_symbol_task.work(worker_id);
3670
3671 // Clean unreferenced things in the ResolvedMethodTable
3672 _resolved_method_cleaning_task.work();
3673
3674 // Wait for all workers to finish the first code cache cleaning pass.
3675 _code_cache_task.barrier_wait(worker_id);
3676
3677 // Do the second code cache cleaning work, which realize on
3678 // the liveness information gathered during the first pass.
3679 _code_cache_task.work_second_pass(worker_id);
3680
3681 // Clean all klasses that were not unloaded.
3682 _klass_cleaning_task.work();
3683 }
3684 };
3685
3686
3687 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3688 bool class_unloading_occurred) {
3689 uint n_workers = workers()->active_workers();
3690
3691 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3692 workers()->run_task(&g1_unlink_task);
3693 }
3694
3695 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3696 bool process_strings,
3697 bool process_symbols,
3698 bool process_string_dedup) {
3699 if (!process_strings && !process_symbols && !process_string_dedup) {
3700 // Nothing to clean.
3701 return;
3702 }
3703
3704 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3705 workers()->run_task(&g1_unlink_task);
3706
3707 }
3708
3709 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3710 private:
3711 DirtyCardQueueSet* _queue;
3712 G1CollectedHeap* _g1h;
3713 public:
3714 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3715 _queue(queue), _g1h(g1h) { }
3716
3717 virtual void work(uint worker_id) {
3718 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3719 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3720
3721 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3722 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3723
3724 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3725 }
3726 };
3727
3728 void G1CollectedHeap::redirty_logged_cards() {
3729 double redirty_logged_cards_start = os::elapsedTime();
3730
3731 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3732 dirty_card_queue_set().reset_for_par_iteration();
3733 workers()->run_task(&redirty_task);
3734
3735 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3736 dcq.merge_bufferlists(&dirty_card_queue_set());
3737 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3738
3739 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3740 }
3741
3742 // Weak Reference Processing support
3743
3744 // An always "is_alive" closure that is used to preserve referents.
3745 // If the object is non-null then it's alive. Used in the preservation
3746 // of referent objects that are pointed to by reference objects
3747 // discovered by the CM ref processor.
3748 class G1AlwaysAliveClosure: public BoolObjectClosure {
3749 G1CollectedHeap* _g1;
3750 public:
3751 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3752 bool do_object_b(oop p) {
3753 if (p != NULL) {
3754 return true;
3755 }
3756 return false;
3757 }
3758 };
3759
3760 bool G1STWIsAliveClosure::do_object_b(oop p) {
3761 // An object is reachable if it is outside the collection set,
3762 // or is inside and copied.
3763 return !_g1->is_in_cset(p) || p->is_forwarded();
3764 }
3765
3766 // Non Copying Keep Alive closure
3767 class G1KeepAliveClosure: public OopClosure {
3768 G1CollectedHeap* _g1;
3769 public:
3770 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3771 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3772 void do_oop(oop* p) {
3773 oop obj = *p;
3774 assert(obj != NULL, "the caller should have filtered out NULL values");
3775
3776 const InCSetState cset_state = _g1->in_cset_state(obj);
3777 if (!cset_state.is_in_cset_or_humongous()) {
3778 return;
3779 }
3780 if (cset_state.is_in_cset()) {
3781 assert( obj->is_forwarded(), "invariant" );
3782 *p = obj->forwardee();
3783 } else {
3784 assert(!obj->is_forwarded(), "invariant" );
3785 assert(cset_state.is_humongous(),
3786 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3787 _g1->set_humongous_is_live(obj);
3788 }
3789 }
3790 };
3791
3792 // Copying Keep Alive closure - can be called from both
3793 // serial and parallel code as long as different worker
3794 // threads utilize different G1ParScanThreadState instances
3795 // and different queues.
3796
3797 class G1CopyingKeepAliveClosure: public OopClosure {
3798 G1CollectedHeap* _g1h;
3799 OopClosure* _copy_non_heap_obj_cl;
3800 G1ParScanThreadState* _par_scan_state;
3801
3802 public:
3803 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3804 OopClosure* non_heap_obj_cl,
3805 G1ParScanThreadState* pss):
3806 _g1h(g1h),
3807 _copy_non_heap_obj_cl(non_heap_obj_cl),
3808 _par_scan_state(pss)
3809 {}
3810
3811 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3812 virtual void do_oop( oop* p) { do_oop_work(p); }
3813
3814 template <class T> void do_oop_work(T* p) {
3815 oop obj = RawAccess<>::oop_load(p);
3816
3817 if (_g1h->is_in_cset_or_humongous(obj)) {
3818 // If the referent object has been forwarded (either copied
3819 // to a new location or to itself in the event of an
3820 // evacuation failure) then we need to update the reference
3821 // field and, if both reference and referent are in the G1
3822 // heap, update the RSet for the referent.
3823 //
3824 // If the referent has not been forwarded then we have to keep
3825 // it alive by policy. Therefore we have copy the referent.
3826 //
3827 // If the reference field is in the G1 heap then we can push
3828 // on the PSS queue. When the queue is drained (after each
3829 // phase of reference processing) the object and it's followers
3830 // will be copied, the reference field set to point to the
3831 // new location, and the RSet updated. Otherwise we need to
3832 // use the the non-heap or metadata closures directly to copy
3833 // the referent object and update the pointer, while avoiding
3834 // updating the RSet.
3835
3836 if (_g1h->is_in_g1_reserved(p)) {
3837 _par_scan_state->push_on_queue(p);
3838 } else {
3839 assert(!Metaspace::contains((const void*)p),
3840 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3841 _copy_non_heap_obj_cl->do_oop(p);
3842 }
3843 }
3844 }
3845 };
3846
3847 // Serial drain queue closure. Called as the 'complete_gc'
3848 // closure for each discovered list in some of the
3849 // reference processing phases.
3850
3851 class G1STWDrainQueueClosure: public VoidClosure {
3852 protected:
3853 G1CollectedHeap* _g1h;
3854 G1ParScanThreadState* _par_scan_state;
3855
3856 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3857
3858 public:
3859 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3860 _g1h(g1h),
3861 _par_scan_state(pss)
3862 { }
3863
3864 void do_void() {
3865 G1ParScanThreadState* const pss = par_scan_state();
3866 pss->trim_queue();
3867 }
3868 };
3869
3870 // Parallel Reference Processing closures
3871
3872 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3873 // processing during G1 evacuation pauses.
3874
3875 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3876 private:
3877 G1CollectedHeap* _g1h;
3878 G1ParScanThreadStateSet* _pss;
3879 RefToScanQueueSet* _queues;
3880 WorkGang* _workers;
3881 uint _active_workers;
3882
3883 public:
3884 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3885 G1ParScanThreadStateSet* per_thread_states,
3886 WorkGang* workers,
3887 RefToScanQueueSet *task_queues,
3888 uint n_workers) :
3889 _g1h(g1h),
3890 _pss(per_thread_states),
3891 _queues(task_queues),
3892 _workers(workers),
3893 _active_workers(n_workers)
3894 {
3895 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3896 }
3897
3898 // Executes the given task using concurrent marking worker threads.
3899 virtual void execute(ProcessTask& task);
3900 virtual void execute(EnqueueTask& task);
3901 };
3902
3903 // Gang task for possibly parallel reference processing
3904
3905 class G1STWRefProcTaskProxy: public AbstractGangTask {
3906 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3907 ProcessTask& _proc_task;
3908 G1CollectedHeap* _g1h;
3909 G1ParScanThreadStateSet* _pss;
3910 RefToScanQueueSet* _task_queues;
3911 ParallelTaskTerminator* _terminator;
3912
3913 public:
3914 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3915 G1CollectedHeap* g1h,
3916 G1ParScanThreadStateSet* per_thread_states,
3917 RefToScanQueueSet *task_queues,
3918 ParallelTaskTerminator* terminator) :
3919 AbstractGangTask("Process reference objects in parallel"),
3920 _proc_task(proc_task),
3921 _g1h(g1h),
3922 _pss(per_thread_states),
3923 _task_queues(task_queues),
3924 _terminator(terminator)
3925 {}
3926
3927 virtual void work(uint worker_id) {
3928 // The reference processing task executed by a single worker.
3929 ResourceMark rm;
3930 HandleMark hm;
3931
3932 G1STWIsAliveClosure is_alive(_g1h);
3933
3934 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3935 pss->set_ref_processor(NULL);
3936
3937 // Keep alive closure.
3938 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3939
3940 // Complete GC closure
3941 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3942
3943 // Call the reference processing task's work routine.
3944 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3945
3946 // Note we cannot assert that the refs array is empty here as not all
3947 // of the processing tasks (specifically phase2 - pp2_work) execute
3948 // the complete_gc closure (which ordinarily would drain the queue) so
3949 // the queue may not be empty.
3950 }
3951 };
3952
3953 // Driver routine for parallel reference processing.
3954 // Creates an instance of the ref processing gang
3955 // task and has the worker threads execute it.
3956 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3957 assert(_workers != NULL, "Need parallel worker threads.");
3958
3959 ParallelTaskTerminator terminator(_active_workers, _queues);
3960 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3961
3962 _workers->run_task(&proc_task_proxy);
3963 }
3964
3965 // Gang task for parallel reference enqueueing.
3966
3967 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3968 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3969 EnqueueTask& _enq_task;
3970
3971 public:
3972 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3973 AbstractGangTask("Enqueue reference objects in parallel"),
3974 _enq_task(enq_task)
3975 { }
3976
3977 virtual void work(uint worker_id) {
3978 _enq_task.work(worker_id);
3979 }
3980 };
3981
3982 // Driver routine for parallel reference enqueueing.
3983 // Creates an instance of the ref enqueueing gang
3984 // task and has the worker threads execute it.
3985
3986 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
3987 assert(_workers != NULL, "Need parallel worker threads.");
3988
3989 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
3990
3991 _workers->run_task(&enq_task_proxy);
3992 }
3993
3994 // End of weak reference support closures
3995
3996 // Abstract task used to preserve (i.e. copy) any referent objects
3997 // that are in the collection set and are pointed to by reference
3998 // objects discovered by the CM ref processor.
3999
4000 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4001 protected:
4002 G1CollectedHeap* _g1h;
4003 G1ParScanThreadStateSet* _pss;
4004 RefToScanQueueSet* _queues;
4005 ParallelTaskTerminator _terminator;
4006 uint _n_workers;
4007
4008 public:
4009 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4010 AbstractGangTask("ParPreserveCMReferents"),
4011 _g1h(g1h),
4012 _pss(per_thread_states),
4013 _queues(task_queues),
4014 _terminator(workers, _queues),
4015 _n_workers(workers)
4016 {
4017 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4018 }
4019
4020 void work(uint worker_id) {
4021 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4022
4023 ResourceMark rm;
4024 HandleMark hm;
4025
4026 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4027 pss->set_ref_processor(NULL);
4028 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4029
4030 // Is alive closure
4031 G1AlwaysAliveClosure always_alive(_g1h);
4032
4033 // Copying keep alive closure. Applied to referent objects that need
4034 // to be copied.
4035 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4036
4037 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4038
4039 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4040 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4041
4042 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4043 // So this must be true - but assert just in case someone decides to
4044 // change the worker ids.
4045 assert(worker_id < limit, "sanity");
4046 assert(!rp->discovery_is_atomic(), "check this code");
4047
4048 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4049 for (uint idx = worker_id; idx < limit; idx += stride) {
4050 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4051
4052 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4053 while (iter.has_next()) {
4054 // Since discovery is not atomic for the CM ref processor, we
4055 // can see some null referent objects.
4056 iter.load_ptrs(DEBUG_ONLY(true));
4057 oop ref = iter.obj();
4058
4059 // This will filter nulls.
4060 if (iter.is_referent_alive()) {
4061 iter.make_referent_alive();
4062 }
4063 iter.move_to_next();
4064 }
4065 }
4066
4067 // Drain the queue - which may cause stealing
4068 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4069 drain_queue.do_void();
4070 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4071 assert(pss->queue_is_empty(), "should be");
4072 }
4073 };
4074
4075 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4076 // Any reference objects, in the collection set, that were 'discovered'
4077 // by the CM ref processor should have already been copied (either by
4078 // applying the external root copy closure to the discovered lists, or
4079 // by following an RSet entry).
4080 //
4081 // But some of the referents, that are in the collection set, that these
4082 // reference objects point to may not have been copied: the STW ref
4083 // processor would have seen that the reference object had already
4084 // been 'discovered' and would have skipped discovering the reference,
4085 // but would not have treated the reference object as a regular oop.
4086 // As a result the copy closure would not have been applied to the
4087 // referent object.
4088 //
4089 // We need to explicitly copy these referent objects - the references
4090 // will be processed at the end of remarking.
4091 //
4092 // We also need to do this copying before we process the reference
4093 // objects discovered by the STW ref processor in case one of these
4094 // referents points to another object which is also referenced by an
4095 // object discovered by the STW ref processor.
4096 double preserve_cm_referents_time = 0.0;
4097
4098 // To avoid spawning task when there is no work to do, check that
4099 // a concurrent cycle is active and that some references have been
4100 // discovered.
4101 if (concurrent_mark()->cm_thread()->during_cycle() &&
4102 ref_processor_cm()->has_discovered_references()) {
4103 double preserve_cm_referents_start = os::elapsedTime();
4104 uint no_of_gc_workers = workers()->active_workers();
4105 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4106 per_thread_states,
4107 no_of_gc_workers,
4108 _task_queues);
4109 workers()->run_task(&keep_cm_referents);
4110 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4111 }
4112
4113 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4114 }
4115
4116 // Weak Reference processing during an evacuation pause (part 1).
4117 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4118 double ref_proc_start = os::elapsedTime();
4119
4120 ReferenceProcessor* rp = _ref_processor_stw;
4121 assert(rp->discovery_enabled(), "should have been enabled");
4122
4123 // Closure to test whether a referent is alive.
4124 G1STWIsAliveClosure is_alive(this);
4125
4126 // Even when parallel reference processing is enabled, the processing
4127 // of JNI refs is serial and performed serially by the current thread
4128 // rather than by a worker. The following PSS will be used for processing
4129 // JNI refs.
4130
4131 // Use only a single queue for this PSS.
4132 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4133 pss->set_ref_processor(NULL);
4134 assert(pss->queue_is_empty(), "pre-condition");
4135
4136 // Keep alive closure.
4137 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4138
4139 // Serial Complete GC closure
4140 G1STWDrainQueueClosure drain_queue(this, pss);
4141
4142 // Setup the soft refs policy...
4143 rp->setup_policy(false);
4144
4145 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4146
4147 ReferenceProcessorStats stats;
4148 if (!rp->processing_is_mt()) {
4149 // Serial reference processing...
4150 stats = rp->process_discovered_references(&is_alive,
4151 &keep_alive,
4152 &drain_queue,
4153 NULL,
4154 pt);
4155 } else {
4156 uint no_of_gc_workers = workers()->active_workers();
4157
4158 // Parallel reference processing
4159 assert(no_of_gc_workers <= rp->max_num_q(),
4160 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4161 no_of_gc_workers, rp->max_num_q());
4162
4163 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4164 stats = rp->process_discovered_references(&is_alive,
4165 &keep_alive,
4166 &drain_queue,
4167 &par_task_executor,
4168 pt);
4169 }
4170
4171 _gc_tracer_stw->report_gc_reference_stats(stats);
4172
4173 // We have completed copying any necessary live referent objects.
4174 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4175
4176 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4177 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4178 }
4179
4180 // Weak Reference processing during an evacuation pause (part 2).
4181 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4182 double ref_enq_start = os::elapsedTime();
4183
4184 ReferenceProcessor* rp = _ref_processor_stw;
4185 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4186
4187 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4188
4189 // Now enqueue any remaining on the discovered lists on to
4190 // the pending list.
4191 if (!rp->processing_is_mt()) {
4192 // Serial reference processing...
4193 rp->enqueue_discovered_references(NULL, pt);
4194 } else {
4195 // Parallel reference enqueueing
4196
4197 uint n_workers = workers()->active_workers();
4198
4199 assert(n_workers <= rp->max_num_q(),
4200 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4201 n_workers, rp->max_num_q());
4202
4203 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4204 rp->enqueue_discovered_references(&par_task_executor, pt);
4205 }
4206
4207 rp->verify_no_references_recorded();
4208 assert(!rp->discovery_enabled(), "should have been disabled");
4209
4210 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4211 // ensure that it is marked in the bitmap for concurrent marking to discover.
4212 if (collector_state()->during_initial_mark_pause()) {
4213 oop pll_head = Universe::reference_pending_list();
4214 if (pll_head != NULL) {
4215 _cm->mark_in_next_bitmap(pll_head);
4216 }
4217 }
4218
4219 // FIXME
4220 // CM's reference processing also cleans up the string and symbol tables.
4221 // Should we do that here also? We could, but it is a serial operation
4222 // and could significantly increase the pause time.
4223
4224 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4225 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4226 }
4227
4228 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4229 double merge_pss_time_start = os::elapsedTime();
4230 per_thread_states->flush();
4231 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4232 }
4233
4234 void G1CollectedHeap::pre_evacuate_collection_set() {
4235 _expand_heap_after_alloc_failure = true;
4236 _evacuation_failed = false;
4237
4238 // Disable the hot card cache.
4239 _hot_card_cache->reset_hot_cache_claimed_index();
4240 _hot_card_cache->set_use_cache(false);
4241
4242 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4243 _preserved_marks_set.assert_empty();
4244
4245 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4246
4247 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4248 if (collector_state()->during_initial_mark_pause()) {
4249 double start_clear_claimed_marks = os::elapsedTime();
4250
4251 ClassLoaderDataGraph::clear_claimed_marks();
4252
4253 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4254 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4255 }
4256 }
4257
4258 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
4259 // Should G1EvacuationFailureALot be in effect for this GC?
4260 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4261
4262 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4263
4264 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4265
4266 double start_par_time_sec = os::elapsedTime();
4267 double end_par_time_sec;
4268
4269 {
4270 const uint n_workers = workers()->active_workers();
4271 G1RootProcessor root_processor(this, n_workers);
4272 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4273
4274 print_termination_stats_hdr();
4275
4276 workers()->run_task(&g1_par_task);
4277 end_par_time_sec = os::elapsedTime();
4278
4279 // Closing the inner scope will execute the destructor
4280 // for the G1RootProcessor object. We record the current
4281 // elapsed time before closing the scope so that time
4282 // taken for the destructor is NOT included in the
4283 // reported parallel time.
4284 }
4285
4286 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4287 phase_times->record_par_time(par_time_ms);
4288
4289 double code_root_fixup_time_ms =
4290 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4291 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4292 }
4293
4294 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4295 // Process any discovered reference objects - we have
4296 // to do this _before_ we retire the GC alloc regions
4297 // as we may have to copy some 'reachable' referent
4298 // objects (and their reachable sub-graphs) that were
4299 // not copied during the pause.
4300 if (g1_policy()->should_process_references()) {
4301 preserve_cm_referents(per_thread_states);
4302 process_discovered_references(per_thread_states);
4303 } else {
4304 ref_processor_stw()->verify_no_references_recorded();
4305 }
4306
4307 G1STWIsAliveClosure is_alive(this);
4308 G1KeepAliveClosure keep_alive(this);
4309
4310 {
4311 double start = os::elapsedTime();
4312
4313 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4314
4315 double time_ms = (os::elapsedTime() - start) * 1000.0;
4316 g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4317 }
4318
4319 if (G1StringDedup::is_enabled()) {
4320 double fixup_start = os::elapsedTime();
4321
4322 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4323
4324 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4325 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4326 }
4327
4328 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4329
4330 if (evacuation_failed()) {
4331 restore_after_evac_failure();
4332
4333 // Reset the G1EvacuationFailureALot counters and flags
4334 // Note: the values are reset only when an actual
4335 // evacuation failure occurs.
4336 NOT_PRODUCT(reset_evacuation_should_fail();)
4337 }
4338
4339 _preserved_marks_set.assert_empty();
4340
4341 // Enqueue any remaining references remaining on the STW
4342 // reference processor's discovered lists. We need to do
4343 // this after the card table is cleaned (and verified) as
4344 // the act of enqueueing entries on to the pending list
4345 // will log these updates (and dirty their associated
4346 // cards). We need these updates logged to update any
4347 // RSets.
4348 if (g1_policy()->should_process_references()) {
4349 enqueue_discovered_references(per_thread_states);
4350 } else {
4351 g1_policy()->phase_times()->record_ref_enq_time(0);
4352 }
4353
4354 _allocator->release_gc_alloc_regions(evacuation_info);
4355
4356 merge_per_thread_state_info(per_thread_states);
4357
4358 // Reset and re-enable the hot card cache.
4359 // Note the counts for the cards in the regions in the
4360 // collection set are reset when the collection set is freed.
4361 _hot_card_cache->reset_hot_cache();
4362 _hot_card_cache->set_use_cache(true);
4363
4364 purge_code_root_memory();
4365
4366 redirty_logged_cards();
4367 #if COMPILER2_OR_JVMCI
4368 double start = os::elapsedTime();
4369 DerivedPointerTable::update_pointers();
4370 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4371 #endif
4372 g1_policy()->print_age_table();
4373 }
4374
4375 void G1CollectedHeap::record_obj_copy_mem_stats() {
4376 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4377
4378 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4379 create_g1_evac_summary(&_old_evac_stats));
4380 }
4381
4382 void G1CollectedHeap::free_region(HeapRegion* hr,
4383 FreeRegionList* free_list,
4384 bool skip_remset,
4385 bool skip_hot_card_cache,
4386 bool locked) {
4387 assert(!hr->is_free(), "the region should not be free");
4388 assert(!hr->is_empty(), "the region should not be empty");
4389 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4390 assert(free_list != NULL, "pre-condition");
4391
4392 if (G1VerifyBitmaps) {
4393 MemRegion mr(hr->bottom(), hr->end());
4394 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4395 }
4396
4397 // Clear the card counts for this region.
4398 // Note: we only need to do this if the region is not young
4399 // (since we don't refine cards in young regions).
4400 if (!skip_hot_card_cache && !hr->is_young()) {
4401 _hot_card_cache->reset_card_counts(hr);
4402 }
4403 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4404 free_list->add_ordered(hr);
4405 }
4406
4407 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4408 FreeRegionList* free_list,
4409 bool skip_remset) {
4410 assert(hr->is_humongous(), "this is only for humongous regions");
4411 assert(free_list != NULL, "pre-condition");
4412 hr->clear_humongous();
4413 free_region(hr, free_list, skip_remset);
4414 }
4415
4416 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4417 const uint humongous_regions_removed) {
4418 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4419 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4420 _old_set.bulk_remove(old_regions_removed);
4421 _humongous_set.bulk_remove(humongous_regions_removed);
4422 }
4423
4424 }
4425
4426 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4427 assert(list != NULL, "list can't be null");
4428 if (!list->is_empty()) {
4429 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4430 _hrm.insert_list_into_free_list(list);
4431 }
4432 }
4433
4434 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4435 decrease_used(bytes);
4436 }
4437
4438 class G1ParScrubRemSetTask: public AbstractGangTask {
4439 protected:
4440 G1RemSet* _g1rs;
4441 HeapRegionClaimer _hrclaimer;
4442
4443 public:
4444 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4445 AbstractGangTask("G1 ScrubRS"),
4446 _g1rs(g1_rs),
4447 _hrclaimer(num_workers) {
4448 }
4449
4450 void work(uint worker_id) {
4451 _g1rs->scrub(worker_id, &_hrclaimer);
4452 }
4453 };
4454
4455 void G1CollectedHeap::scrub_rem_set() {
4456 uint num_workers = workers()->active_workers();
4457 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4458 workers()->run_task(&g1_par_scrub_rs_task);
4459 }
4460
4461 class G1FreeCollectionSetTask : public AbstractGangTask {
4462 private:
4463
4464 // Closure applied to all regions in the collection set to do work that needs to
4465 // be done serially in a single thread.
4466 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4467 private:
4468 EvacuationInfo* _evacuation_info;
4469 const size_t* _surviving_young_words;
4470
4471 // Bytes used in successfully evacuated regions before the evacuation.
4472 size_t _before_used_bytes;
4473 // Bytes used in unsucessfully evacuated regions before the evacuation
4474 size_t _after_used_bytes;
4475
4476 size_t _bytes_allocated_in_old_since_last_gc;
4477
4478 size_t _failure_used_words;
4479 size_t _failure_waste_words;
4480
4481 FreeRegionList _local_free_list;
4482 public:
4483 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4484 HeapRegionClosure(),
4485 _evacuation_info(evacuation_info),
4486 _surviving_young_words(surviving_young_words),
4487 _before_used_bytes(0),
4488 _after_used_bytes(0),
4489 _bytes_allocated_in_old_since_last_gc(0),
4490 _failure_used_words(0),
4491 _failure_waste_words(0),
4492 _local_free_list("Local Region List for CSet Freeing") {
4493 }
4494
4495 virtual bool do_heap_region(HeapRegion* r) {
4496 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4497
4498 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4499 g1h->clear_in_cset(r);
4500
4501 if (r->is_young()) {
4502 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4503 "Young index %d is wrong for region %u of type %s with %u young regions",
4504 r->young_index_in_cset(),
4505 r->hrm_index(),
4506 r->get_type_str(),
4507 g1h->collection_set()->young_region_length());
4508 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4509 r->record_surv_words_in_group(words_survived);
4510 }
4511
4512 if (!r->evacuation_failed()) {
4513 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4514 _before_used_bytes += r->used();
4515 g1h->free_region(r,
4516 &_local_free_list,
4517 true, /* skip_remset */
4518 true, /* skip_hot_card_cache */
4519 true /* locked */);
4520 } else {
4521 r->uninstall_surv_rate_group();
4522 r->set_young_index_in_cset(-1);
4523 r->set_evacuation_failed(false);
4524 // When moving a young gen region to old gen, we "allocate" that whole region
4525 // there. This is in addition to any already evacuated objects. Notify the
4526 // policy about that.
4527 // Old gen regions do not cause an additional allocation: both the objects
4528 // still in the region and the ones already moved are accounted for elsewhere.
4529 if (r->is_young()) {
4530 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4531 }
4532 // The region is now considered to be old.
4533 r->set_old();
4534 // Do some allocation statistics accounting. Regions that failed evacuation
4535 // are always made old, so there is no need to update anything in the young
4536 // gen statistics, but we need to update old gen statistics.
4537 size_t used_words = r->marked_bytes() / HeapWordSize;
4538
4539 _failure_used_words += used_words;
4540 _failure_waste_words += HeapRegion::GrainWords - used_words;
4541
4542 g1h->old_set_add(r);
4543 _after_used_bytes += r->used();
4544 }
4545 return false;
4546 }
4547
4548 void complete_work() {
4549 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4550
4551 _evacuation_info->set_regions_freed(_local_free_list.length());
4552 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4553
4554 g1h->prepend_to_freelist(&_local_free_list);
4555 g1h->decrement_summary_bytes(_before_used_bytes);
4556
4557 G1Policy* policy = g1h->g1_policy();
4558 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4559
4560 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4561 }
4562 };
4563
4564 G1CollectionSet* _collection_set;
4565 G1SerialFreeCollectionSetClosure _cl;
4566 const size_t* _surviving_young_words;
4567
4568 size_t _rs_lengths;
4569
4570 volatile jint _serial_work_claim;
4571
4572 struct WorkItem {
4573 uint region_idx;
4574 bool is_young;
4575 bool evacuation_failed;
4576
4577 WorkItem(HeapRegion* r) {
4578 region_idx = r->hrm_index();
4579 is_young = r->is_young();
4580 evacuation_failed = r->evacuation_failed();
4581 }
4582 };
4583
4584 volatile size_t _parallel_work_claim;
4585 size_t _num_work_items;
4586 WorkItem* _work_items;
4587
4588 void do_serial_work() {
4589 // Need to grab the lock to be allowed to modify the old region list.
4590 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4591 _collection_set->iterate(&_cl);
4592 }
4593
4594 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4595 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4596
4597 HeapRegion* r = g1h->region_at(region_idx);
4598 assert(!g1h->is_on_master_free_list(r), "sanity");
4599
4600 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4601
4602 if (!is_young) {
4603 g1h->_hot_card_cache->reset_card_counts(r);
4604 }
4605
4606 if (!evacuation_failed) {
4607 r->rem_set()->clear_locked();
4608 }
4609 }
4610
4611 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4612 private:
4613 size_t _cur_idx;
4614 WorkItem* _work_items;
4615 public:
4616 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4617
4618 virtual bool do_heap_region(HeapRegion* r) {
4619 _work_items[_cur_idx++] = WorkItem(r);
4620 return false;
4621 }
4622 };
4623
4624 void prepare_work() {
4625 G1PrepareFreeCollectionSetClosure cl(_work_items);
4626 _collection_set->iterate(&cl);
4627 }
4628
4629 void complete_work() {
4630 _cl.complete_work();
4631
4632 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4633 policy->record_max_rs_lengths(_rs_lengths);
4634 policy->cset_regions_freed();
4635 }
4636 public:
4637 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4638 AbstractGangTask("G1 Free Collection Set"),
4639 _cl(evacuation_info, surviving_young_words),
4640 _collection_set(collection_set),
4641 _surviving_young_words(surviving_young_words),
4642 _serial_work_claim(0),
4643 _rs_lengths(0),
4644 _parallel_work_claim(0),
4645 _num_work_items(collection_set->region_length()),
4646 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4647 prepare_work();
4648 }
4649
4650 ~G1FreeCollectionSetTask() {
4651 complete_work();
4652 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4653 }
4654
4655 // Chunk size for work distribution. The chosen value has been determined experimentally
4656 // to be a good tradeoff between overhead and achievable parallelism.
4657 static uint chunk_size() { return 32; }
4658
4659 virtual void work(uint worker_id) {
4660 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4661
4662 // Claim serial work.
4663 if (_serial_work_claim == 0) {
4664 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4665 if (value == 0) {
4666 double serial_time = os::elapsedTime();
4667 do_serial_work();
4668 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4669 }
4670 }
4671
4672 // Start parallel work.
4673 double young_time = 0.0;
4674 bool has_young_time = false;
4675 double non_young_time = 0.0;
4676 bool has_non_young_time = false;
4677
4678 while (true) {
4679 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4680 size_t cur = end - chunk_size();
4681
4682 if (cur >= _num_work_items) {
4683 break;
4684 }
4685
4686 double start_time = os::elapsedTime();
4687
4688 end = MIN2(end, _num_work_items);
4689
4690 for (; cur < end; cur++) {
4691 bool is_young = _work_items[cur].is_young;
4692
4693 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4694
4695 double end_time = os::elapsedTime();
4696 double time_taken = end_time - start_time;
4697 if (is_young) {
4698 young_time += time_taken;
4699 has_young_time = true;
4700 } else {
4701 non_young_time += time_taken;
4702 has_non_young_time = true;
4703 }
4704 start_time = end_time;
4705 }
4706 }
4707
4708 if (has_young_time) {
4709 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4710 }
4711 if (has_non_young_time) {
4712 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4713 }
4714 }
4715 };
4716
4717 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4718 _eden.clear();
4719
4720 double free_cset_start_time = os::elapsedTime();
4721
4722 {
4723 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4724 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4725
4726 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4727
4728 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4729 cl.name(),
4730 num_workers,
4731 _collection_set.region_length());
4732 workers()->run_task(&cl, num_workers);
4733 }
4734 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4735
4736 collection_set->clear();
4737 }
4738
4739 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4740 private:
4741 FreeRegionList* _free_region_list;
4742 HeapRegionSet* _proxy_set;
4743 uint _humongous_objects_reclaimed;
4744 uint _humongous_regions_reclaimed;
4745 size_t _freed_bytes;
4746 public:
4747
4748 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4749 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4750 }
4751
4752 virtual bool do_heap_region(HeapRegion* r) {
4753 if (!r->is_starts_humongous()) {
4754 return false;
4755 }
4756
4757 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4758
4759 oop obj = (oop)r->bottom();
4760 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4761
4762 // The following checks whether the humongous object is live are sufficient.
4763 // The main additional check (in addition to having a reference from the roots
4764 // or the young gen) is whether the humongous object has a remembered set entry.
4765 //
4766 // A humongous object cannot be live if there is no remembered set for it
4767 // because:
4768 // - there can be no references from within humongous starts regions referencing
4769 // the object because we never allocate other objects into them.
4770 // (I.e. there are no intra-region references that may be missed by the
4771 // remembered set)
4772 // - as soon there is a remembered set entry to the humongous starts region
4773 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4774 // until the end of a concurrent mark.
4775 //
4776 // It is not required to check whether the object has been found dead by marking
4777 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4778 // all objects allocated during that time are considered live.
4779 // SATB marking is even more conservative than the remembered set.
4780 // So if at this point in the collection there is no remembered set entry,
4781 // nobody has a reference to it.
4782 // At the start of collection we flush all refinement logs, and remembered sets
4783 // are completely up-to-date wrt to references to the humongous object.
4784 //
4785 // Other implementation considerations:
4786 // - never consider object arrays at this time because they would pose
4787 // considerable effort for cleaning up the the remembered sets. This is
4788 // required because stale remembered sets might reference locations that
4789 // are currently allocated into.
4790 uint region_idx = r->hrm_index();
4791 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4792 !r->rem_set()->is_empty()) {
4793 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",
4794 region_idx,
4795 (size_t)obj->size() * HeapWordSize,
4796 p2i(r->bottom()),
4797 r->rem_set()->occupied(),
4798 r->rem_set()->strong_code_roots_list_length(),
4799 next_bitmap->is_marked(r->bottom()),
4800 g1h->is_humongous_reclaim_candidate(region_idx),
4801 obj->is_typeArray()
4802 );
4803 return false;
4804 }
4805
4806 guarantee(obj->is_typeArray(),
4807 "Only eagerly reclaiming type arrays is supported, but the object "
4808 PTR_FORMAT " is not.", p2i(r->bottom()));
4809
4810 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",
4811 region_idx,
4812 (size_t)obj->size() * HeapWordSize,
4813 p2i(r->bottom()),
4814 r->rem_set()->occupied(),
4815 r->rem_set()->strong_code_roots_list_length(),
4816 next_bitmap->is_marked(r->bottom()),
4817 g1h->is_humongous_reclaim_candidate(region_idx),
4818 obj->is_typeArray()
4819 );
4820
4821 // Need to clear mark bit of the humongous object if already set.
4822 if (next_bitmap->is_marked(r->bottom())) {
4823 next_bitmap->clear(r->bottom());
4824 }
4825 _humongous_objects_reclaimed++;
4826 do {
4827 HeapRegion* next = g1h->next_region_in_humongous(r);
4828 _freed_bytes += r->used();
4829 r->set_containing_set(NULL);
4830 _humongous_regions_reclaimed++;
4831 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4832 r = next;
4833 } while (r != NULL);
4834
4835 return false;
4836 }
4837
4838 uint humongous_objects_reclaimed() {
4839 return _humongous_objects_reclaimed;
4840 }
4841
4842 uint humongous_regions_reclaimed() {
4843 return _humongous_regions_reclaimed;
4844 }
4845
4846 size_t bytes_freed() const {
4847 return _freed_bytes;
4848 }
4849 };
4850
4851 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4852 assert_at_safepoint_on_vm_thread();
4853
4854 if (!G1EagerReclaimHumongousObjects ||
4855 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4856 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4857 return;
4858 }
4859
4860 double start_time = os::elapsedTime();
4861
4862 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4863
4864 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4865 heap_region_iterate(&cl);
4866
4867 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4868
4869 G1HRPrinter* hrp = hr_printer();
4870 if (hrp->is_active()) {
4871 FreeRegionListIterator iter(&local_cleanup_list);
4872 while (iter.more_available()) {
4873 HeapRegion* hr = iter.get_next();
4874 hrp->cleanup(hr);
4875 }
4876 }
4877
4878 prepend_to_freelist(&local_cleanup_list);
4879 decrement_summary_bytes(cl.bytes_freed());
4880
4881 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4882 cl.humongous_objects_reclaimed());
4883 }
4884
4885 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4886 public:
4887 virtual bool do_heap_region(HeapRegion* r) {
4888 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4889 G1CollectedHeap::heap()->clear_in_cset(r);
4890 r->set_young_index_in_cset(-1);
4891 return false;
4892 }
4893 };
4894
4895 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4896 G1AbandonCollectionSetClosure cl;
4897 collection_set->iterate(&cl);
4898
4899 collection_set->clear();
4900 collection_set->stop_incremental_building();
4901 }
4902
4903 void G1CollectedHeap::set_free_regions_coming() {
4904 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4905
4906 assert(!free_regions_coming(), "pre-condition");
4907 _free_regions_coming = true;
4908 }
4909
4910 void G1CollectedHeap::reset_free_regions_coming() {
4911 assert(free_regions_coming(), "pre-condition");
4912
4913 {
4914 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4915 _free_regions_coming = false;
4916 SecondaryFreeList_lock->notify_all();
4917 }
4918
4919 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4920 }
4921
4922 void G1CollectedHeap::wait_while_free_regions_coming() {
4923 // Most of the time we won't have to wait, so let's do a quick test
4924 // first before we take the lock.
4925 if (!free_regions_coming()) {
4926 return;
4927 }
4928
4929 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4930
4931 {
4932 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4933 while (free_regions_coming()) {
4934 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4935 }
4936 }
4937
4938 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4939 }
4940
4941 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4942 return _allocator->is_retained_old_region(hr);
4943 }
4944
4945 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4946 _eden.add(hr);
4947 _g1_policy->set_region_eden(hr);
4948 }
4949
4950 #ifdef ASSERT
4951
4952 class NoYoungRegionsClosure: public HeapRegionClosure {
4953 private:
4954 bool _success;
4955 public:
4956 NoYoungRegionsClosure() : _success(true) { }
4957 bool do_heap_region(HeapRegion* r) {
4958 if (r->is_young()) {
4959 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4960 p2i(r->bottom()), p2i(r->end()));
4961 _success = false;
4962 }
4963 return false;
4964 }
4965 bool success() { return _success; }
4966 };
4967
4968 bool G1CollectedHeap::check_young_list_empty() {
4969 bool ret = (young_regions_count() == 0);
4970
4971 NoYoungRegionsClosure closure;
4972 heap_region_iterate(&closure);
4973 ret = ret && closure.success();
4974
4975 return ret;
4976 }
4977
4978 #endif // ASSERT
4979
4980 class TearDownRegionSetsClosure : public HeapRegionClosure {
4981 private:
4982 HeapRegionSet *_old_set;
4983
4984 public:
4985 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4986
4987 bool do_heap_region(HeapRegion* r) {
4988 if (r->is_old()) {
4989 _old_set->remove(r);
4990 } else if(r->is_young()) {
4991 r->uninstall_surv_rate_group();
4992 } else {
4993 // We ignore free regions, we'll empty the free list afterwards.
4994 // We ignore humongous regions, we're not tearing down the
4995 // humongous regions set.
4996 assert(r->is_free() || r->is_humongous(),
4997 "it cannot be another type");
4998 }
4999 return false;
5000 }
5001
5002 ~TearDownRegionSetsClosure() {
5003 assert(_old_set->is_empty(), "post-condition");
5004 }
5005 };
5006
5007 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5008 assert_at_safepoint_on_vm_thread();
5009
5010 if (!free_list_only) {
5011 TearDownRegionSetsClosure cl(&_old_set);
5012 heap_region_iterate(&cl);
5013
5014 // Note that emptying the _young_list is postponed and instead done as
5015 // the first step when rebuilding the regions sets again. The reason for
5016 // this is that during a full GC string deduplication needs to know if
5017 // a collected region was young or old when the full GC was initiated.
5018 }
5019 _hrm.remove_all_free_regions();
5020 }
5021
5022 void G1CollectedHeap::increase_used(size_t bytes) {
5023 _summary_bytes_used += bytes;
5024 }
5025
5026 void G1CollectedHeap::decrease_used(size_t bytes) {
5027 assert(_summary_bytes_used >= bytes,
5028 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5029 _summary_bytes_used, bytes);
5030 _summary_bytes_used -= bytes;
5031 }
5032
5033 void G1CollectedHeap::set_used(size_t bytes) {
5034 _summary_bytes_used = bytes;
5035 }
5036
5037 class RebuildRegionSetsClosure : public HeapRegionClosure {
5038 private:
5039 bool _free_list_only;
5040 HeapRegionSet* _old_set;
5041 HeapRegionManager* _hrm;
5042 size_t _total_used;
5043
5044 public:
5045 RebuildRegionSetsClosure(bool free_list_only,
5046 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5047 _free_list_only(free_list_only),
5048 _old_set(old_set), _hrm(hrm), _total_used(0) {
5049 assert(_hrm->num_free_regions() == 0, "pre-condition");
5050 if (!free_list_only) {
5051 assert(_old_set->is_empty(), "pre-condition");
5052 }
5053 }
5054
5055 bool do_heap_region(HeapRegion* r) {
5056 if (r->is_empty()) {
5057 // Add free regions to the free list
5058 r->set_free();
5059 _hrm->insert_into_free_list(r);
5060 } else if (!_free_list_only) {
5061
5062 if (r->is_humongous()) {
5063 // We ignore humongous regions. We left the humongous set unchanged.
5064 } else {
5065 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5066 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5067 r->move_to_old();
5068 _old_set->add(r);
5069 }
5070 _total_used += r->used();
5071 }
5072
5073 return false;
5074 }
5075
5076 size_t total_used() {
5077 return _total_used;
5078 }
5079 };
5080
5081 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5082 assert_at_safepoint_on_vm_thread();
5083
5084 if (!free_list_only) {
5085 _eden.clear();
5086 _survivor.clear();
5087 }
5088
5089 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5090 heap_region_iterate(&cl);
5091
5092 if (!free_list_only) {
5093 set_used(cl.total_used());
5094 if (_archive_allocator != NULL) {
5095 _archive_allocator->clear_used();
5096 }
5097 }
5098 assert(used_unlocked() == recalculate_used(),
5099 "inconsistent used_unlocked(), "
5100 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5101 used_unlocked(), recalculate_used());
5102 }
5103
5104 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5105 HeapRegion* hr = heap_region_containing(p);
5106 return hr->is_in(p);
5107 }
5108
5109 // Methods for the mutator alloc region
5110
5111 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5112 bool force) {
5113 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5114 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5115 if (force || should_allocate) {
5116 HeapRegion* new_alloc_region = new_region(word_size,
5117 false /* is_old */,
5118 false /* do_expand */);
5119 if (new_alloc_region != NULL) {
5120 set_region_short_lived_locked(new_alloc_region);
5121 _hr_printer.alloc(new_alloc_region, !should_allocate);
5122 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5123 return new_alloc_region;
5124 }
5125 }
5126 return NULL;
5127 }
5128
5129 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5130 size_t allocated_bytes) {
5131 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5132 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5133
5134 collection_set()->add_eden_region(alloc_region);
5135 increase_used(allocated_bytes);
5136 _hr_printer.retire(alloc_region);
5137 // We update the eden sizes here, when the region is retired,
5138 // instead of when it's allocated, since this is the point that its
5139 // used space has been recored in _summary_bytes_used.
5140 g1mm()->update_eden_size();
5141 }
5142
5143 // Methods for the GC alloc regions
5144
5145 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5146 if (dest.is_old()) {
5147 return true;
5148 } else {
5149 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5150 }
5151 }
5152
5153 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5154 assert(FreeList_lock->owned_by_self(), "pre-condition");
5155
5156 if (!has_more_regions(dest)) {
5157 return NULL;
5158 }
5159
5160 const bool is_survivor = dest.is_young();
5161
5162 HeapRegion* new_alloc_region = new_region(word_size,
5163 !is_survivor,
5164 true /* do_expand */);
5165 if (new_alloc_region != NULL) {
5166 // We really only need to do this for old regions given that we
5167 // should never scan survivors. But it doesn't hurt to do it
5168 // for survivors too.
5169 new_alloc_region->record_timestamp();
5170 if (is_survivor) {
5171 new_alloc_region->set_survivor();
5172 _survivor.add(new_alloc_region);
5173 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5174 } else {
5175 new_alloc_region->set_old();
5176 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5177 }
5178 _hr_printer.alloc(new_alloc_region);
5179 bool during_im = collector_state()->during_initial_mark_pause();
5180 new_alloc_region->note_start_of_copying(during_im);
5181 return new_alloc_region;
5182 }
5183 return NULL;
5184 }
5185
5186 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5187 size_t allocated_bytes,
5188 InCSetState dest) {
5189 bool during_im = collector_state()->during_initial_mark_pause();
5190 alloc_region->note_end_of_copying(during_im);
5191 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5192 if (dest.is_old()) {
5193 _old_set.add(alloc_region);
5194 }
5195 _hr_printer.retire(alloc_region);
5196 }
5197
5198 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5199 bool expanded = false;
5200 uint index = _hrm.find_highest_free(&expanded);
5201
5202 if (index != G1_NO_HRM_INDEX) {
5203 if (expanded) {
5204 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5205 HeapRegion::GrainWords * HeapWordSize);
5206 }
5207 _hrm.allocate_free_regions_starting_at(index, 1);
5208 return region_at(index);
5209 }
5210 return NULL;
5211 }
5212
5213 // Optimized nmethod scanning
5214
5215 class RegisterNMethodOopClosure: public OopClosure {
5216 G1CollectedHeap* _g1h;
5217 nmethod* _nm;
5218
5219 template <class T> void do_oop_work(T* p) {
5220 T heap_oop = RawAccess<>::oop_load(p);
5221 if (!CompressedOops::is_null(heap_oop)) {
5222 oop obj = CompressedOops::decode_not_null(heap_oop);
5223 HeapRegion* hr = _g1h->heap_region_containing(obj);
5224 assert(!hr->is_continues_humongous(),
5225 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5226 " starting at " HR_FORMAT,
5227 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5228
5229 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5230 hr->add_strong_code_root_locked(_nm);
5231 }
5232 }
5233
5234 public:
5235 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5236 _g1h(g1h), _nm(nm) {}
5237
5238 void do_oop(oop* p) { do_oop_work(p); }
5239 void do_oop(narrowOop* p) { do_oop_work(p); }
5240 };
5241
5242 class UnregisterNMethodOopClosure: public OopClosure {
5243 G1CollectedHeap* _g1h;
5244 nmethod* _nm;
5245
5246 template <class T> void do_oop_work(T* p) {
5247 T heap_oop = RawAccess<>::oop_load(p);
5248 if (!CompressedOops::is_null(heap_oop)) {
5249 oop obj = CompressedOops::decode_not_null(heap_oop);
5250 HeapRegion* hr = _g1h->heap_region_containing(obj);
5251 assert(!hr->is_continues_humongous(),
5252 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5253 " starting at " HR_FORMAT,
5254 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5255
5256 hr->remove_strong_code_root(_nm);
5257 }
5258 }
5259
5260 public:
5261 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5262 _g1h(g1h), _nm(nm) {}
5263
5264 void do_oop(oop* p) { do_oop_work(p); }
5265 void do_oop(narrowOop* p) { do_oop_work(p); }
5266 };
5267
5268 // Returns true if the reference points to an object that
5269 // can move in an incremental collection.
5270 bool G1CollectedHeap::is_scavengable(oop obj) {
5271 HeapRegion* hr = heap_region_containing(obj);
5272 return !hr->is_pinned();
5273 }
5274
5275 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5276 guarantee(nm != NULL, "sanity");
5277 RegisterNMethodOopClosure reg_cl(this, nm);
5278 nm->oops_do(®_cl);
5279 }
5280
5281 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5282 guarantee(nm != NULL, "sanity");
5283 UnregisterNMethodOopClosure reg_cl(this, nm);
5284 nm->oops_do(®_cl, true);
5285 }
5286
5287 void G1CollectedHeap::purge_code_root_memory() {
5288 double purge_start = os::elapsedTime();
5289 G1CodeRootSet::purge();
5290 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5291 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5292 }
5293
5294 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5295 G1CollectedHeap* _g1h;
5296
5297 public:
5298 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5299 _g1h(g1h) {}
5300
5301 void do_code_blob(CodeBlob* cb) {
5302 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5303 if (nm == NULL) {
5304 return;
5305 }
5306
5307 if (ScavengeRootsInCode) {
5308 _g1h->register_nmethod(nm);
5309 }
5310 }
5311 };
5312
5313 void G1CollectedHeap::rebuild_strong_code_roots() {
5314 RebuildStrongCodeRootClosure blob_cl(this);
5315 CodeCache::blobs_do(&blob_cl);
5316 }
5317
5318 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5319 GrowableArray<GCMemoryManager*> memory_managers(2);
5320 memory_managers.append(&_memory_manager);
5321 memory_managers.append(&_full_gc_memory_manager);
5322 return memory_managers;
5323 }
5324
5325 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5326 GrowableArray<MemoryPool*> memory_pools(3);
5327 memory_pools.append(_eden_pool);
5328 memory_pools.append(_survivor_pool);
5329 memory_pools.append(_old_pool);
5330 return memory_pools;
5331 }