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/oop.inline.hpp"
81 #include "prims/resolvedMethodTable.hpp"
82 #include "runtime/atomic.hpp"
83 #include "runtime/init.hpp"
84 #include "runtime/orderAccess.inline.hpp"
85 #include "runtime/threadSMR.hpp"
86 #include "runtime/vmThread.hpp"
87 #include "utilities/align.hpp"
88 #include "utilities/globalDefinitions.hpp"
89 #include "utilities/stack.inline.hpp"
90
91 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
92
93 // INVARIANTS/NOTES
94 //
95 // All allocation activity covered by the G1CollectedHeap interface is
96 // serialized by acquiring the HeapLock. This happens in mem_allocate
97 // and allocate_new_tlab, which are the "entry" points to the
98 // allocation code from the rest of the JVM. (Note that this does not
99 // apply to TLAB allocation, which is not part of this interface: it
100 // is done by clients of this interface.)
101
102 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
103 private:
104 size_t _num_dirtied;
105 G1CollectedHeap* _g1h;
106 G1SATBCardTableLoggingModRefBS* _g1_bs;
107
108 HeapRegion* region_for_card(jbyte* card_ptr) const {
109 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
110 }
111
112 bool will_become_free(HeapRegion* hr) const {
113 // A region will be freed by free_collection_set if the region is in the
114 // collection set and has not had an evacuation failure.
115 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
116 }
117
118 public:
119 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
120 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
121
122 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
123 HeapRegion* hr = region_for_card(card_ptr);
124
125 // Should only dirty cards in regions that won't be freed.
126 if (!will_become_free(hr)) {
127 *card_ptr = CardTableModRefBS::dirty_card_val();
128 _num_dirtied++;
129 }
130
131 return true;
132 }
133
134 size_t num_dirtied() const { return _num_dirtied; }
135 };
136
137
138 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
139 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
140 }
141
142 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
143 // The from card cache is not the memory that is actually committed. So we cannot
144 // take advantage of the zero_filled parameter.
145 reset_from_card_cache(start_idx, num_regions);
146 }
147
148
149 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
150 MemRegion mr) {
151 return new HeapRegion(hrs_index, bot(), mr);
152 }
153
154 // Private methods.
155
156 HeapRegion*
157 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
158 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
159 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
160 if (!_secondary_free_list.is_empty()) {
161 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
162 "secondary_free_list has %u entries",
163 _secondary_free_list.length());
164 // It looks as if there are free regions available on the
165 // secondary_free_list. Let's move them to the free_list and try
166 // again to allocate from it.
167 append_secondary_free_list();
168
169 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
170 "empty we should have moved at least one entry to the free_list");
171 HeapRegion* res = _hrm.allocate_free_region(is_old);
172 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
173 "allocated " HR_FORMAT " from secondary_free_list",
174 HR_FORMAT_PARAMS(res));
175 return res;
176 }
177
178 // Wait here until we get notified either when (a) there are no
179 // more free regions coming or (b) some regions have been moved on
180 // the secondary_free_list.
181 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
182 }
183
184 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
185 "could not allocate from secondary_free_list");
186 return NULL;
187 }
188
189 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
190 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
191 "the only time we use this to allocate a humongous region is "
192 "when we are allocating a single humongous region");
193
194 HeapRegion* res;
195 if (G1StressConcRegionFreeing) {
196 if (!_secondary_free_list.is_empty()) {
197 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
198 "forced to look at the secondary_free_list");
199 res = new_region_try_secondary_free_list(is_old);
200 if (res != NULL) {
201 return res;
202 }
203 }
204 }
205
206 res = _hrm.allocate_free_region(is_old);
207
208 if (res == NULL) {
209 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
210 "res == NULL, trying the secondary_free_list");
211 res = new_region_try_secondary_free_list(is_old);
212 }
213 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
214 // Currently, only attempts to allocate GC alloc regions set
215 // do_expand to true. So, we should only reach here during a
216 // safepoint. If this assumption changes we might have to
217 // reconsider the use of _expand_heap_after_alloc_failure.
218 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
219
220 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
221 word_size * HeapWordSize);
222
223 if (expand(word_size * HeapWordSize)) {
224 // Given that expand() succeeded in expanding the heap, and we
225 // always expand the heap by an amount aligned to the heap
226 // region size, the free list should in theory not be empty.
227 // In either case allocate_free_region() will check for NULL.
228 res = _hrm.allocate_free_region(is_old);
229 } else {
230 _expand_heap_after_alloc_failure = false;
231 }
232 }
233 return res;
234 }
235
236 HeapWord*
237 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
238 uint num_regions,
239 size_t word_size) {
240 assert(first != G1_NO_HRM_INDEX, "pre-condition");
241 assert(is_humongous(word_size), "word_size should be humongous");
242 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
243
244 // Index of last region in the series.
245 uint last = first + num_regions - 1;
246
247 // We need to initialize the region(s) we just discovered. This is
248 // a bit tricky given that it can happen concurrently with
249 // refinement threads refining cards on these regions and
250 // potentially wanting to refine the BOT as they are scanning
251 // those cards (this can happen shortly after a cleanup; see CR
252 // 6991377). So we have to set up the region(s) carefully and in
253 // a specific order.
254
255 // The word size sum of all the regions we will allocate.
256 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
257 assert(word_size <= word_size_sum, "sanity");
258
259 // This will be the "starts humongous" region.
260 HeapRegion* first_hr = region_at(first);
261 // The header of the new object will be placed at the bottom of
262 // the first region.
263 HeapWord* new_obj = first_hr->bottom();
264 // This will be the new top of the new object.
265 HeapWord* obj_top = new_obj + word_size;
266
267 // First, we need to zero the header of the space that we will be
268 // allocating. When we update top further down, some refinement
269 // threads might try to scan the region. By zeroing the header we
270 // ensure that any thread that will try to scan the region will
271 // come across the zero klass word and bail out.
272 //
273 // NOTE: It would not have been correct to have used
274 // CollectedHeap::fill_with_object() and make the space look like
275 // an int array. The thread that is doing the allocation will
276 // later update the object header to a potentially different array
277 // type and, for a very short period of time, the klass and length
278 // fields will be inconsistent. This could cause a refinement
279 // thread to calculate the object size incorrectly.
280 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
281
282 // Next, pad out the unused tail of the last region with filler
283 // objects, for improved usage accounting.
284 // How many words we use for filler objects.
285 size_t word_fill_size = word_size_sum - word_size;
286
287 // How many words memory we "waste" which cannot hold a filler object.
288 size_t words_not_fillable = 0;
289
290 if (word_fill_size >= min_fill_size()) {
291 fill_with_objects(obj_top, word_fill_size);
292 } else if (word_fill_size > 0) {
293 // We have space to fill, but we cannot fit an object there.
294 words_not_fillable = word_fill_size;
295 word_fill_size = 0;
296 }
297
298 // We will set up the first region as "starts humongous". This
299 // will also update the BOT covering all the regions to reflect
300 // that there is a single object that starts at the bottom of the
301 // first region.
302 first_hr->set_starts_humongous(obj_top, word_fill_size);
303 // Then, if there are any, we will set up the "continues
304 // humongous" regions.
305 HeapRegion* hr = NULL;
306 for (uint i = first + 1; i <= last; ++i) {
307 hr = region_at(i);
308 hr->set_continues_humongous(first_hr);
309 }
310
311 // Up to this point no concurrent thread would have been able to
312 // do any scanning on any region in this series. All the top
313 // fields still point to bottom, so the intersection between
314 // [bottom,top] and [card_start,card_end] will be empty. Before we
315 // update the top fields, we'll do a storestore to make sure that
316 // no thread sees the update to top before the zeroing of the
317 // object header and the BOT initialization.
318 OrderAccess::storestore();
319
320 // Now, we will update the top fields of the "continues humongous"
321 // regions except the last one.
322 for (uint i = first; i < last; ++i) {
323 hr = region_at(i);
324 hr->set_top(hr->end());
325 }
326
327 hr = region_at(last);
328 // If we cannot fit a filler object, we must set top to the end
329 // of the humongous object, otherwise we cannot iterate the heap
330 // and the BOT will not be complete.
331 hr->set_top(hr->end() - words_not_fillable);
332
333 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
334 "obj_top should be in last region");
335
336 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
337
338 assert(words_not_fillable == 0 ||
339 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
340 "Miscalculation in humongous allocation");
341
342 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
343
344 for (uint i = first; i <= last; ++i) {
345 hr = region_at(i);
346 _humongous_set.add(hr);
347 _hr_printer.alloc(hr);
348 }
349
350 return new_obj;
351 }
352
353 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
354 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
355 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
356 }
357
358 // If could fit into free regions w/o expansion, try.
359 // Otherwise, if can expand, do so.
360 // Otherwise, if using ex regions might help, try with ex given back.
361 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
362 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
363
364 _verifier->verify_region_sets_optional();
365
366 uint first = G1_NO_HRM_INDEX;
367 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
368
369 if (obj_regions == 1) {
370 // Only one region to allocate, try to use a fast path by directly allocating
371 // from the free lists. Do not try to expand here, we will potentially do that
372 // later.
373 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
374 if (hr != NULL) {
375 first = hr->hrm_index();
376 }
377 } else {
378 // We can't allocate humongous regions spanning more than one region while
379 // cleanupComplete() is running, since some of the regions we find to be
380 // empty might not yet be added to the free list. It is not straightforward
381 // to know in which list they are on so that we can remove them. We only
382 // need to do this if we need to allocate more than one region to satisfy the
383 // current humongous allocation request. If we are only allocating one region
384 // we use the one-region region allocation code (see above), that already
385 // potentially waits for regions from the secondary free list.
386 wait_while_free_regions_coming();
387 append_secondary_free_list_if_not_empty_with_lock();
388
389 // Policy: Try only empty regions (i.e. already committed first). Maybe we
390 // are lucky enough to find some.
391 first = _hrm.find_contiguous_only_empty(obj_regions);
392 if (first != G1_NO_HRM_INDEX) {
393 _hrm.allocate_free_regions_starting_at(first, obj_regions);
394 }
395 }
396
397 if (first == G1_NO_HRM_INDEX) {
398 // Policy: We could not find enough regions for the humongous object in the
399 // free list. Look through the heap to find a mix of free and uncommitted regions.
400 // If so, try expansion.
401 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
402 if (first != G1_NO_HRM_INDEX) {
403 // We found something. Make sure these regions are committed, i.e. expand
404 // the heap. Alternatively we could do a defragmentation GC.
405 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
406 word_size * HeapWordSize);
407
408 _hrm.expand_at(first, obj_regions, workers());
409 g1_policy()->record_new_heap_size(num_regions());
410
411 #ifdef ASSERT
412 for (uint i = first; i < first + obj_regions; ++i) {
413 HeapRegion* hr = region_at(i);
414 assert(hr->is_free(), "sanity");
415 assert(hr->is_empty(), "sanity");
416 assert(is_on_master_free_list(hr), "sanity");
417 }
418 #endif
419 _hrm.allocate_free_regions_starting_at(first, obj_regions);
420 } else {
421 // Policy: Potentially trigger a defragmentation GC.
422 }
423 }
424
425 HeapWord* result = NULL;
426 if (first != G1_NO_HRM_INDEX) {
427 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
428 assert(result != NULL, "it should always return a valid result");
429
430 // A successful humongous object allocation changes the used space
431 // information of the old generation so we need to recalculate the
432 // sizes and update the jstat counters here.
433 g1mm()->update_sizes();
434 }
435
436 _verifier->verify_region_sets_optional();
437
438 return result;
439 }
440
441 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
442 assert_heap_not_locked_and_not_at_safepoint();
443 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
444
445 return attempt_allocation(word_size);
446 }
447
448 HeapWord*
449 G1CollectedHeap::mem_allocate(size_t word_size,
450 bool* gc_overhead_limit_was_exceeded) {
451 assert_heap_not_locked_and_not_at_safepoint();
452
453 if (is_humongous(word_size)) {
454 return attempt_allocation_humongous(word_size);
455 }
456 return attempt_allocation(word_size);
457 }
458
459 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
460 ResourceMark rm; // For retrieving the thread names in log messages.
461
462 // Make sure you read the note in attempt_allocation_humongous().
463
464 assert_heap_not_locked_and_not_at_safepoint();
465 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
466 "be called for humongous allocation requests");
467
468 // We should only get here after the first-level allocation attempt
469 // (attempt_allocation()) failed to allocate.
470
471 // We will loop until a) we manage to successfully perform the
472 // allocation or b) we successfully schedule a collection which
473 // fails to perform the allocation. b) is the only case when we'll
474 // return NULL.
475 HeapWord* result = NULL;
476 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
477 bool should_try_gc;
478 uint gc_count_before;
479
480 {
481 MutexLockerEx x(Heap_lock);
482 result = _allocator->attempt_allocation_locked(word_size);
483 if (result != NULL) {
484 return result;
485 }
486
487 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
488 // This is different to when only GCLocker::needs_gc() is set: try to avoid
489 // waiting because the GCLocker is active to not wait too long.
490 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
491 // No need for an ergo message here, can_expand_young_list() does this when
492 // it returns true.
493 result = _allocator->attempt_allocation_force(word_size);
494 if (result != NULL) {
495 return result;
496 }
497 }
498 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
499 // the GCLocker initiated GC has been performed and then retry. This includes
500 // the case when the GC Locker is not active but has not been performed.
501 should_try_gc = !GCLocker::needs_gc();
502 // Read the GC count while still holding the Heap_lock.
503 gc_count_before = total_collections();
504 }
505
506 if (should_try_gc) {
507 bool succeeded;
508 result = do_collection_pause(word_size, gc_count_before, &succeeded,
509 GCCause::_g1_inc_collection_pause);
510 if (result != NULL) {
511 assert(succeeded, "only way to get back a non-NULL result");
512 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
513 Thread::current()->name(), p2i(result));
514 return result;
515 }
516
517 if (succeeded) {
518 // We successfully scheduled a collection which failed to allocate. No
519 // point in trying to allocate further. We'll just return NULL.
520 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
521 SIZE_FORMAT " words", Thread::current()->name(), word_size);
522 return NULL;
523 }
524 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
525 Thread::current()->name(), word_size);
526 } else {
527 // Failed to schedule a collection.
528 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
529 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
530 SIZE_FORMAT " words", Thread::current()->name(), word_size);
531 return NULL;
532 }
533 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
534 // The GCLocker is either active or the GCLocker initiated
535 // GC has not yet been performed. Stall until it is and
536 // then retry the allocation.
537 GCLocker::stall_until_clear();
538 gclocker_retry_count += 1;
539 }
540
541 // We can reach here if we were unsuccessful in scheduling a
542 // collection (because another thread beat us to it) or if we were
543 // stalled due to the GC locker. In either can we should retry the
544 // allocation attempt in case another thread successfully
545 // performed a collection and reclaimed enough space. We do the
546 // first attempt (without holding the Heap_lock) here and the
547 // follow-on attempt will be at the start of the next loop
548 // iteration (after taking the Heap_lock).
549
550 result = _allocator->attempt_allocation(word_size);
551 if (result != NULL) {
552 return result;
553 }
554
555 // Give a warning if we seem to be looping forever.
556 if ((QueuedAllocationWarningCount > 0) &&
557 (try_count % QueuedAllocationWarningCount == 0)) {
558 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
559 Thread::current()->name(), try_count, word_size);
560 }
561 }
562
563 ShouldNotReachHere();
564 return NULL;
565 }
566
567 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
568 assert_at_safepoint(true /* should_be_vm_thread */);
569 if (_archive_allocator == NULL) {
570 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
571 }
572 }
573
574 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
575 // Allocations in archive regions cannot be of a size that would be considered
576 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
577 // may be different at archive-restore time.
578 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
579 }
580
581 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
582 assert_at_safepoint(true /* should_be_vm_thread */);
583 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
584 if (is_archive_alloc_too_large(word_size)) {
585 return NULL;
586 }
587 return _archive_allocator->archive_mem_allocate(word_size);
588 }
589
590 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
591 size_t end_alignment_in_bytes) {
592 assert_at_safepoint(true /* should_be_vm_thread */);
593 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
594
595 // Call complete_archive to do the real work, filling in the MemRegion
596 // array with the archive regions.
597 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
598 delete _archive_allocator;
599 _archive_allocator = NULL;
600 }
601
602 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
603 assert(ranges != NULL, "MemRegion array NULL");
604 assert(count != 0, "No MemRegions provided");
605 MemRegion reserved = _hrm.reserved();
606 for (size_t i = 0; i < count; i++) {
607 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
608 return false;
609 }
610 }
611 return true;
612 }
613
614 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
615 size_t count,
616 bool open) {
617 assert(!is_init_completed(), "Expect to be called at JVM init time");
618 assert(ranges != NULL, "MemRegion array NULL");
619 assert(count != 0, "No MemRegions provided");
620 MutexLockerEx x(Heap_lock);
621
622 MemRegion reserved = _hrm.reserved();
623 HeapWord* prev_last_addr = NULL;
624 HeapRegion* prev_last_region = NULL;
625
626 // Temporarily disable pretouching of heap pages. This interface is used
627 // when mmap'ing archived heap data in, so pre-touching is wasted.
628 FlagSetting fs(AlwaysPreTouch, false);
629
630 // Enable archive object checking used by G1MarkSweep. We have to let it know
631 // about each archive range, so that objects in those ranges aren't marked.
632 G1ArchiveAllocator::enable_archive_object_check();
633
634 // For each specified MemRegion range, allocate the corresponding G1
635 // regions and mark them as archive regions. We expect the ranges
636 // in ascending starting address order, without overlap.
637 for (size_t i = 0; i < count; i++) {
638 MemRegion curr_range = ranges[i];
639 HeapWord* start_address = curr_range.start();
640 size_t word_size = curr_range.word_size();
641 HeapWord* last_address = curr_range.last();
642 size_t commits = 0;
643
644 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
645 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
646 p2i(start_address), p2i(last_address));
647 guarantee(start_address > prev_last_addr,
648 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
649 p2i(start_address), p2i(prev_last_addr));
650 prev_last_addr = last_address;
651
652 // Check for ranges that start in the same G1 region in which the previous
653 // range ended, and adjust the start address so we don't try to allocate
654 // the same region again. If the current range is entirely within that
655 // region, skip it, just adjusting the recorded top.
656 HeapRegion* start_region = _hrm.addr_to_region(start_address);
657 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
658 start_address = start_region->end();
659 if (start_address > last_address) {
660 increase_used(word_size * HeapWordSize);
661 start_region->set_top(last_address + 1);
662 continue;
663 }
664 start_region->set_top(start_address);
665 curr_range = MemRegion(start_address, last_address + 1);
666 start_region = _hrm.addr_to_region(start_address);
667 }
668
669 // Perform the actual region allocation, exiting if it fails.
670 // Then note how much new space we have allocated.
671 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
672 return false;
673 }
674 increase_used(word_size * HeapWordSize);
675 if (commits != 0) {
676 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
677 HeapRegion::GrainWords * HeapWordSize * commits);
678
679 }
680
681 // Mark each G1 region touched by the range as archive, add it to
682 // the old set, and set top.
683 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
684 HeapRegion* last_region = _hrm.addr_to_region(last_address);
685 prev_last_region = last_region;
686
687 while (curr_region != NULL) {
688 assert(curr_region->is_empty() && !curr_region->is_pinned(),
689 "Region already in use (index %u)", curr_region->hrm_index());
690 if (open) {
691 curr_region->set_open_archive();
692 } else {
693 curr_region->set_closed_archive();
694 }
695 _hr_printer.alloc(curr_region);
696 _old_set.add(curr_region);
697 HeapWord* top;
698 HeapRegion* next_region;
699 if (curr_region != last_region) {
700 top = curr_region->end();
701 next_region = _hrm.next_region_in_heap(curr_region);
702 } else {
703 top = last_address + 1;
704 next_region = NULL;
705 }
706 curr_region->set_top(top);
707 curr_region->set_first_dead(top);
708 curr_region->set_end_of_live(top);
709 curr_region = next_region;
710 }
711
712 // Notify mark-sweep of the archive
713 G1ArchiveAllocator::set_range_archive(curr_range, open);
714 }
715 return true;
716 }
717
718 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
719 assert(!is_init_completed(), "Expect to be called at JVM init time");
720 assert(ranges != NULL, "MemRegion array NULL");
721 assert(count != 0, "No MemRegions provided");
722 MemRegion reserved = _hrm.reserved();
723 HeapWord *prev_last_addr = NULL;
724 HeapRegion* prev_last_region = NULL;
725
726 // For each MemRegion, create filler objects, if needed, in the G1 regions
727 // that contain the address range. The address range actually within the
728 // MemRegion will not be modified. That is assumed to have been initialized
729 // elsewhere, probably via an mmap of archived heap data.
730 MutexLockerEx x(Heap_lock);
731 for (size_t i = 0; i < count; i++) {
732 HeapWord* start_address = ranges[i].start();
733 HeapWord* last_address = ranges[i].last();
734
735 assert(reserved.contains(start_address) && reserved.contains(last_address),
736 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
737 p2i(start_address), p2i(last_address));
738 assert(start_address > prev_last_addr,
739 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
740 p2i(start_address), p2i(prev_last_addr));
741
742 HeapRegion* start_region = _hrm.addr_to_region(start_address);
743 HeapRegion* last_region = _hrm.addr_to_region(last_address);
744 HeapWord* bottom_address = start_region->bottom();
745
746 // Check for a range beginning in the same region in which the
747 // previous one ended.
748 if (start_region == prev_last_region) {
749 bottom_address = prev_last_addr + 1;
750 }
751
752 // Verify that the regions were all marked as archive regions by
753 // alloc_archive_regions.
754 HeapRegion* curr_region = start_region;
755 while (curr_region != NULL) {
756 guarantee(curr_region->is_archive(),
757 "Expected archive region at index %u", curr_region->hrm_index());
758 if (curr_region != last_region) {
759 curr_region = _hrm.next_region_in_heap(curr_region);
760 } else {
761 curr_region = NULL;
762 }
763 }
764
765 prev_last_addr = last_address;
766 prev_last_region = last_region;
767
768 // Fill the memory below the allocated range with dummy object(s),
769 // if the region bottom does not match the range start, or if the previous
770 // range ended within the same G1 region, and there is a gap.
771 if (start_address != bottom_address) {
772 size_t fill_size = pointer_delta(start_address, bottom_address);
773 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
774 increase_used(fill_size * HeapWordSize);
775 }
776 }
777 }
778
779 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
780 assert_heap_not_locked_and_not_at_safepoint();
781 assert(!is_humongous(word_size), "attempt_allocation() should not "
782 "be called for humongous allocation requests");
783
784 HeapWord* result = _allocator->attempt_allocation(word_size);
785
786 if (result == NULL) {
787 result = attempt_allocation_slow(word_size);
788 }
789 assert_heap_not_locked();
790 if (result != NULL) {
791 dirty_young_block(result, word_size);
792 }
793 return result;
794 }
795
796 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
797 assert(!is_init_completed(), "Expect to be called at JVM init time");
798 assert(ranges != NULL, "MemRegion array NULL");
799 assert(count != 0, "No MemRegions provided");
800 MemRegion reserved = _hrm.reserved();
801 HeapWord* prev_last_addr = NULL;
802 HeapRegion* prev_last_region = NULL;
803 size_t size_used = 0;
804 size_t uncommitted_regions = 0;
805
806 // For each Memregion, free the G1 regions that constitute it, and
807 // notify mark-sweep that the range is no longer to be considered 'archive.'
808 MutexLockerEx x(Heap_lock);
809 for (size_t i = 0; i < count; i++) {
810 HeapWord* start_address = ranges[i].start();
811 HeapWord* last_address = ranges[i].last();
812
813 assert(reserved.contains(start_address) && reserved.contains(last_address),
814 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
815 p2i(start_address), p2i(last_address));
816 assert(start_address > prev_last_addr,
817 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
818 p2i(start_address), p2i(prev_last_addr));
819 size_used += ranges[i].byte_size();
820 prev_last_addr = last_address;
821
822 HeapRegion* start_region = _hrm.addr_to_region(start_address);
823 HeapRegion* last_region = _hrm.addr_to_region(last_address);
824
825 // Check for ranges that start in the same G1 region in which the previous
826 // range ended, and adjust the start address so we don't try to free
827 // the same region again. If the current range is entirely within that
828 // region, skip it.
829 if (start_region == prev_last_region) {
830 start_address = start_region->end();
831 if (start_address > last_address) {
832 continue;
833 }
834 start_region = _hrm.addr_to_region(start_address);
835 }
836 prev_last_region = last_region;
837
838 // After verifying that each region was marked as an archive region by
839 // alloc_archive_regions, set it free and empty and uncommit it.
840 HeapRegion* curr_region = start_region;
841 while (curr_region != NULL) {
842 guarantee(curr_region->is_archive(),
843 "Expected archive region at index %u", curr_region->hrm_index());
844 uint curr_index = curr_region->hrm_index();
845 _old_set.remove(curr_region);
846 curr_region->set_free();
847 curr_region->set_top(curr_region->bottom());
848 if (curr_region != last_region) {
849 curr_region = _hrm.next_region_in_heap(curr_region);
850 } else {
851 curr_region = NULL;
852 }
853 _hrm.shrink_at(curr_index, 1);
854 uncommitted_regions++;
855 }
856
857 // Notify mark-sweep that this is no longer an archive range.
858 G1ArchiveAllocator::set_range_archive(ranges[i], false);
859 }
860
861 if (uncommitted_regions != 0) {
862 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
863 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
864 }
865 decrease_used(size_used);
866 }
867
868 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
869 ResourceMark rm; // For retrieving the thread names in log messages.
870
871 // The structure of this method has a lot of similarities to
872 // attempt_allocation_slow(). The reason these two were not merged
873 // into a single one is that such a method would require several "if
874 // allocation is not humongous do this, otherwise do that"
875 // conditional paths which would obscure its flow. In fact, an early
876 // version of this code did use a unified method which was harder to
877 // follow and, as a result, it had subtle bugs that were hard to
878 // track down. So keeping these two methods separate allows each to
879 // be more readable. It will be good to keep these two in sync as
880 // much as possible.
881
882 assert_heap_not_locked_and_not_at_safepoint();
883 assert(is_humongous(word_size), "attempt_allocation_humongous() "
884 "should only be called for humongous allocations");
885
886 // Humongous objects can exhaust the heap quickly, so we should check if we
887 // need to start a marking cycle at each humongous object allocation. We do
888 // the check before we do the actual allocation. The reason for doing it
889 // before the allocation is that we avoid having to keep track of the newly
890 // allocated memory while we do a GC.
891 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
892 word_size)) {
893 collect(GCCause::_g1_humongous_allocation);
894 }
895
896 // We will loop until a) we manage to successfully perform the
897 // allocation or b) we successfully schedule a collection which
898 // fails to perform the allocation. b) is the only case when we'll
899 // return NULL.
900 HeapWord* result = NULL;
901 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
902 bool should_try_gc;
903 uint gc_count_before;
904
905
906 {
907 MutexLockerEx x(Heap_lock);
908
909 // Given that humongous objects are not allocated in young
910 // regions, we'll first try to do the allocation without doing a
911 // collection hoping that there's enough space in the heap.
912 result = humongous_obj_allocate(word_size);
913 if (result != NULL) {
914 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
915 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
916 return result;
917 }
918
919 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
920 // the GCLocker initiated GC has been performed and then retry. This includes
921 // the case when the GC Locker is not active but has not been performed.
922 should_try_gc = !GCLocker::needs_gc();
923 // Read the GC count while still holding the Heap_lock.
924 gc_count_before = total_collections();
925 }
926
927 if (should_try_gc) {
928 bool succeeded;
929 result = do_collection_pause(word_size, gc_count_before, &succeeded,
930 GCCause::_g1_humongous_allocation);
931 if (result != NULL) {
932 assert(succeeded, "only way to get back a non-NULL result");
933 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
934 Thread::current()->name(), p2i(result));
935 return result;
936 }
937
938 if (succeeded) {
939 // We successfully scheduled a collection which failed to allocate. No
940 // point in trying to allocate further. We'll just return NULL.
941 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
942 SIZE_FORMAT " words", Thread::current()->name(), word_size);
943 return NULL;
944 }
945 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
946 Thread::current()->name(), word_size);
947 } else {
948 // Failed to schedule a collection.
949 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
950 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
951 SIZE_FORMAT " words", Thread::current()->name(), word_size);
952 return NULL;
953 }
954 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
955 // The GCLocker is either active or the GCLocker initiated
956 // GC has not yet been performed. Stall until it is and
957 // then retry the allocation.
958 GCLocker::stall_until_clear();
959 gclocker_retry_count += 1;
960 }
961
962
963 // We can reach here if we were unsuccessful in scheduling a
964 // collection (because another thread beat us to it) or if we were
965 // stalled due to the GC locker. In either can we should retry the
966 // allocation attempt in case another thread successfully
967 // performed a collection and reclaimed enough space.
968 // Humongous object allocation always needs a lock, so we wait for the retry
969 // in the next iteration of the loop, unlike for the regular iteration case.
970 // Give a warning if we seem to be looping forever.
971
972 if ((QueuedAllocationWarningCount > 0) &&
973 (try_count % QueuedAllocationWarningCount == 0)) {
974 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
975 Thread::current()->name(), try_count, word_size);
976 }
977 }
978
979 ShouldNotReachHere();
980 return NULL;
981 }
982
983 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
984 bool expect_null_mutator_alloc_region) {
985 assert_at_safepoint(true /* should_be_vm_thread */);
986 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
987 "the current alloc region was unexpectedly found to be non-NULL");
988
989 if (!is_humongous(word_size)) {
990 return _allocator->attempt_allocation_locked(word_size);
991 } else {
992 HeapWord* result = humongous_obj_allocate(word_size);
993 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
994 collector_state()->set_initiate_conc_mark_if_possible(true);
995 }
996 return result;
997 }
998
999 ShouldNotReachHere();
1000 }
1001
1002 class PostCompactionPrinterClosure: public HeapRegionClosure {
1003 private:
1004 G1HRPrinter* _hr_printer;
1005 public:
1006 bool do_heap_region(HeapRegion* hr) {
1007 assert(!hr->is_young(), "not expecting to find young regions");
1008 _hr_printer->post_compaction(hr);
1009 return false;
1010 }
1011
1012 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1013 : _hr_printer(hr_printer) { }
1014 };
1015
1016 void G1CollectedHeap::print_hrm_post_compaction() {
1017 if (_hr_printer.is_active()) {
1018 PostCompactionPrinterClosure cl(hr_printer());
1019 heap_region_iterate(&cl);
1020 }
1021 }
1022
1023 void G1CollectedHeap::abort_concurrent_cycle() {
1024 // Note: When we have a more flexible GC logging framework that
1025 // allows us to add optional attributes to a GC log record we
1026 // could consider timing and reporting how long we wait in the
1027 // following two methods.
1028 wait_while_free_regions_coming();
1029 // If we start the compaction before the CM threads finish
1030 // scanning the root regions we might trip them over as we'll
1031 // be moving objects / updating references. So let's wait until
1032 // they are done. By telling them to abort, they should complete
1033 // early.
1034 _cm->root_regions()->abort();
1035 _cm->root_regions()->wait_until_scan_finished();
1036 append_secondary_free_list_if_not_empty_with_lock();
1037
1038 // Disable discovery and empty the discovered lists
1039 // for the CM ref processor.
1040 ref_processor_cm()->disable_discovery();
1041 ref_processor_cm()->abandon_partial_discovery();
1042 ref_processor_cm()->verify_no_references_recorded();
1043
1044 // Abandon current iterations of concurrent marking and concurrent
1045 // refinement, if any are in progress.
1046 concurrent_mark()->abort();
1047 }
1048
1049 void G1CollectedHeap::prepare_heap_for_full_collection() {
1050 // Make sure we'll choose a new allocation region afterwards.
1051 _allocator->release_mutator_alloc_region();
1052 _allocator->abandon_gc_alloc_regions();
1053 g1_rem_set()->cleanupHRRS();
1054
1055 // We may have added regions to the current incremental collection
1056 // set between the last GC or pause and now. We need to clear the
1057 // incremental collection set and then start rebuilding it afresh
1058 // after this full GC.
1059 abandon_collection_set(collection_set());
1060
1061 tear_down_region_sets(false /* free_list_only */);
1062 collector_state()->set_gcs_are_young(true);
1063 }
1064
1065 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1066 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1067 assert(used() == recalculate_used(), "Should be equal");
1068 _verifier->verify_region_sets_optional();
1069 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1070 _verifier->check_bitmaps("Full GC Start");
1071 }
1072
1073 void G1CollectedHeap::prepare_heap_for_mutators() {
1074 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1075 ClassLoaderDataGraph::purge();
1076 MetaspaceAux::verify_metrics();
1077
1078 // Prepare heap for normal collections.
1079 assert(num_free_regions() == 0, "we should not have added any free regions");
1080 rebuild_region_sets(false /* free_list_only */);
1081 abort_refinement();
1082 resize_if_necessary_after_full_collection();
1083
1084 // Rebuild the strong code root lists for each region
1085 rebuild_strong_code_roots();
1086
1087 // Start a new incremental collection set for the next pause
1088 start_new_collection_set();
1089
1090 _allocator->init_mutator_alloc_region();
1091
1092 // Post collection state updates.
1093 MetaspaceGC::compute_new_size();
1094 }
1095
1096 void G1CollectedHeap::abort_refinement() {
1097 if (_hot_card_cache->use_cache()) {
1098 _hot_card_cache->reset_hot_cache();
1099 }
1100
1101 // Discard all remembered set updates.
1102 JavaThread::dirty_card_queue_set().abandon_logs();
1103 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1104 }
1105
1106 void G1CollectedHeap::verify_after_full_collection() {
1107 check_gc_time_stamps();
1108 _hrm.verify_optional();
1109 _verifier->verify_region_sets_optional();
1110 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1111 // Clear the previous marking bitmap, if needed for bitmap verification.
1112 // Note we cannot do this when we clear the next marking bitmap in
1113 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1114 // objects marked during a full GC against the previous bitmap.
1115 // But we need to clear it before calling check_bitmaps below since
1116 // the full GC has compacted objects and updated TAMS but not updated
1117 // the prev bitmap.
1118 if (G1VerifyBitmaps) {
1119 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1120 _cm->clear_prev_bitmap(workers());
1121 }
1122 _verifier->check_bitmaps("Full GC End");
1123
1124 // At this point there should be no regions in the
1125 // entire heap tagged as young.
1126 assert(check_young_list_empty(), "young list should be empty at this point");
1127
1128 // Note: since we've just done a full GC, concurrent
1129 // marking is no longer active. Therefore we need not
1130 // re-enable reference discovery for the CM ref processor.
1131 // That will be done at the start of the next marking cycle.
1132 // We also know that the STW processor should no longer
1133 // discover any new references.
1134 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1135 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1136 ref_processor_stw()->verify_no_references_recorded();
1137 ref_processor_cm()->verify_no_references_recorded();
1138 }
1139
1140 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1141 // Post collection logging.
1142 // We should do this after we potentially resize the heap so
1143 // that all the COMMIT / UNCOMMIT events are generated before
1144 // the compaction events.
1145 print_hrm_post_compaction();
1146 heap_transition->print();
1147 print_heap_after_gc();
1148 print_heap_regions();
1149 #ifdef TRACESPINNING
1150 ParallelTaskTerminator::print_termination_counts();
1151 #endif
1152 }
1153
1154 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1155 bool clear_all_soft_refs) {
1156 assert_at_safepoint(true /* should_be_vm_thread */);
1157
1158 if (GCLocker::check_active_before_gc()) {
1159 // Full GC was not completed.
1160 return false;
1161 }
1162
1163 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1164 soft_ref_policy()->should_clear_all_soft_refs();
1165
1166 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1167 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1168
1169 collector.prepare_collection();
1170 collector.collect();
1171 collector.complete_collection();
1172
1173 // Full collection was successfully completed.
1174 return true;
1175 }
1176
1177 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1178 // Currently, there is no facility in the do_full_collection(bool) API to notify
1179 // the caller that the collection did not succeed (e.g., because it was locked
1180 // out by the GC locker). So, right now, we'll ignore the return value.
1181 bool dummy = do_full_collection(true, /* explicit_gc */
1182 clear_all_soft_refs);
1183 }
1184
1185 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1186 // Capacity, free and used after the GC counted as full regions to
1187 // include the waste in the following calculations.
1188 const size_t capacity_after_gc = capacity();
1189 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1190
1191 // This is enforced in arguments.cpp.
1192 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1193 "otherwise the code below doesn't make sense");
1194
1195 // We don't have floating point command-line arguments
1196 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1197 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1198 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1199 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1200
1201 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1202 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1203
1204 // We have to be careful here as these two calculations can overflow
1205 // 32-bit size_t's.
1206 double used_after_gc_d = (double) used_after_gc;
1207 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1208 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1209
1210 // Let's make sure that they are both under the max heap size, which
1211 // by default will make them fit into a size_t.
1212 double desired_capacity_upper_bound = (double) max_heap_size;
1213 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1214 desired_capacity_upper_bound);
1215 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1216 desired_capacity_upper_bound);
1217
1218 // We can now safely turn them into size_t's.
1219 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1220 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1221
1222 // This assert only makes sense here, before we adjust them
1223 // with respect to the min and max heap size.
1224 assert(minimum_desired_capacity <= maximum_desired_capacity,
1225 "minimum_desired_capacity = " SIZE_FORMAT ", "
1226 "maximum_desired_capacity = " SIZE_FORMAT,
1227 minimum_desired_capacity, maximum_desired_capacity);
1228
1229 // Should not be greater than the heap max size. No need to adjust
1230 // it with respect to the heap min size as it's a lower bound (i.e.,
1231 // we'll try to make the capacity larger than it, not smaller).
1232 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1233 // Should not be less than the heap min size. No need to adjust it
1234 // with respect to the heap max size as it's an upper bound (i.e.,
1235 // we'll try to make the capacity smaller than it, not greater).
1236 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1237
1238 if (capacity_after_gc < minimum_desired_capacity) {
1239 // Don't expand unless it's significant
1240 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1241
1242 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1243 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1244 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1245 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1246
1247 expand(expand_bytes, _workers);
1248
1249 // No expansion, now see if we want to shrink
1250 } else if (capacity_after_gc > maximum_desired_capacity) {
1251 // Capacity too large, compute shrinking size
1252 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1253
1254 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1255 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1256 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1257 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1258
1259 shrink(shrink_bytes);
1260 }
1261 }
1262
1263 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1264 bool do_gc,
1265 bool clear_all_soft_refs,
1266 bool expect_null_mutator_alloc_region,
1267 bool* gc_succeeded) {
1268 *gc_succeeded = true;
1269 // Let's attempt the allocation first.
1270 HeapWord* result =
1271 attempt_allocation_at_safepoint(word_size,
1272 expect_null_mutator_alloc_region);
1273 if (result != NULL) {
1274 return result;
1275 }
1276
1277 // In a G1 heap, we're supposed to keep allocation from failing by
1278 // incremental pauses. Therefore, at least for now, we'll favor
1279 // expansion over collection. (This might change in the future if we can
1280 // do something smarter than full collection to satisfy a failed alloc.)
1281 result = expand_and_allocate(word_size);
1282 if (result != NULL) {
1283 return result;
1284 }
1285
1286 if (do_gc) {
1287 // Expansion didn't work, we'll try to do a Full GC.
1288 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1289 clear_all_soft_refs);
1290 }
1291
1292 return NULL;
1293 }
1294
1295 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1296 bool* succeeded) {
1297 assert_at_safepoint(true /* should_be_vm_thread */);
1298
1299 // Attempts to allocate followed by Full GC.
1300 HeapWord* result =
1301 satisfy_failed_allocation_helper(word_size,
1302 true, /* do_gc */
1303 false, /* clear_all_soft_refs */
1304 false, /* expect_null_mutator_alloc_region */
1305 succeeded);
1306
1307 if (result != NULL || !*succeeded) {
1308 return result;
1309 }
1310
1311 // Attempts to allocate followed by Full GC that will collect all soft references.
1312 result = satisfy_failed_allocation_helper(word_size,
1313 true, /* do_gc */
1314 true, /* clear_all_soft_refs */
1315 true, /* expect_null_mutator_alloc_region */
1316 succeeded);
1317
1318 if (result != NULL || !*succeeded) {
1319 return result;
1320 }
1321
1322 // Attempts to allocate, no GC
1323 result = satisfy_failed_allocation_helper(word_size,
1324 false, /* do_gc */
1325 false, /* clear_all_soft_refs */
1326 true, /* expect_null_mutator_alloc_region */
1327 succeeded);
1328
1329 if (result != NULL) {
1330 return result;
1331 }
1332
1333 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1334 "Flag should have been handled and cleared prior to this point");
1335
1336 // What else? We might try synchronous finalization later. If the total
1337 // space available is large enough for the allocation, then a more
1338 // complete compaction phase than we've tried so far might be
1339 // appropriate.
1340 return NULL;
1341 }
1342
1343 // Attempting to expand the heap sufficiently
1344 // to support an allocation of the given "word_size". If
1345 // successful, perform the allocation and return the address of the
1346 // allocated block, or else "NULL".
1347
1348 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1349 assert_at_safepoint(true /* should_be_vm_thread */);
1350
1351 _verifier->verify_region_sets_optional();
1352
1353 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1354 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1355 word_size * HeapWordSize);
1356
1357
1358 if (expand(expand_bytes, _workers)) {
1359 _hrm.verify_optional();
1360 _verifier->verify_region_sets_optional();
1361 return attempt_allocation_at_safepoint(word_size,
1362 false /* expect_null_mutator_alloc_region */);
1363 }
1364 return NULL;
1365 }
1366
1367 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1368 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1369 aligned_expand_bytes = align_up(aligned_expand_bytes,
1370 HeapRegion::GrainBytes);
1371
1372 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1373 expand_bytes, aligned_expand_bytes);
1374
1375 if (is_maximal_no_gc()) {
1376 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1377 return false;
1378 }
1379
1380 double expand_heap_start_time_sec = os::elapsedTime();
1381 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1382 assert(regions_to_expand > 0, "Must expand by at least one region");
1383
1384 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1385 if (expand_time_ms != NULL) {
1386 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1387 }
1388
1389 if (expanded_by > 0) {
1390 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1391 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1392 g1_policy()->record_new_heap_size(num_regions());
1393 } else {
1394 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1395
1396 // The expansion of the virtual storage space was unsuccessful.
1397 // Let's see if it was because we ran out of swap.
1398 if (G1ExitOnExpansionFailure &&
1399 _hrm.available() >= regions_to_expand) {
1400 // We had head room...
1401 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1402 }
1403 }
1404 return regions_to_expand > 0;
1405 }
1406
1407 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1408 size_t aligned_shrink_bytes =
1409 ReservedSpace::page_align_size_down(shrink_bytes);
1410 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1411 HeapRegion::GrainBytes);
1412 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1413
1414 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1415 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1416
1417
1418 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",
1419 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1420 if (num_regions_removed > 0) {
1421 g1_policy()->record_new_heap_size(num_regions());
1422 } else {
1423 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1424 }
1425 }
1426
1427 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1428 _verifier->verify_region_sets_optional();
1429
1430 // We should only reach here at the end of a Full GC which means we
1431 // should not not be holding to any GC alloc regions. The method
1432 // below will make sure of that and do any remaining clean up.
1433 _allocator->abandon_gc_alloc_regions();
1434
1435 // Instead of tearing down / rebuilding the free lists here, we
1436 // could instead use the remove_all_pending() method on free_list to
1437 // remove only the ones that we need to remove.
1438 tear_down_region_sets(true /* free_list_only */);
1439 shrink_helper(shrink_bytes);
1440 rebuild_region_sets(true /* free_list_only */);
1441
1442 _hrm.verify_optional();
1443 _verifier->verify_region_sets_optional();
1444 }
1445
1446 // Public methods.
1447
1448 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1449 CollectedHeap(),
1450 _young_gen_sampling_thread(NULL),
1451 _collector_policy(collector_policy),
1452 _soft_ref_policy(),
1453 _memory_manager("G1 Young Generation", "end of minor GC"),
1454 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1455 _eden_pool(NULL),
1456 _survivor_pool(NULL),
1457 _old_pool(NULL),
1458 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1459 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1460 _g1_policy(create_g1_policy(_gc_timer_stw)),
1461 _collection_set(this, _g1_policy),
1462 _dirty_card_queue_set(false),
1463 _is_alive_closure_cm(this),
1464 _is_alive_closure_stw(this),
1465 _ref_processor_cm(NULL),
1466 _ref_processor_stw(NULL),
1467 _bot(NULL),
1468 _hot_card_cache(NULL),
1469 _g1_rem_set(NULL),
1470 _cr(NULL),
1471 _g1mm(NULL),
1472 _preserved_marks_set(true /* in_c_heap */),
1473 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1474 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1475 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1476 _humongous_reclaim_candidates(),
1477 _has_humongous_reclaim_candidates(false),
1478 _archive_allocator(NULL),
1479 _free_regions_coming(false),
1480 _gc_time_stamp(0),
1481 _summary_bytes_used(0),
1482 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1483 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1484 _expand_heap_after_alloc_failure(true),
1485 _old_marking_cycles_started(0),
1486 _old_marking_cycles_completed(0),
1487 _in_cset_fast_test() {
1488
1489 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1490 /* are_GC_task_threads */true,
1491 /* are_ConcurrentGC_threads */false);
1492 _workers->initialize_workers();
1493 _verifier = new G1HeapVerifier(this);
1494
1495 _allocator = new G1DefaultAllocator(this);
1496
1497 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1498
1499 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1500
1501 // Override the default _filler_array_max_size so that no humongous filler
1502 // objects are created.
1503 _filler_array_max_size = _humongous_object_threshold_in_words;
1504
1505 uint n_queues = ParallelGCThreads;
1506 _task_queues = new RefToScanQueueSet(n_queues);
1507
1508 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1509
1510 for (uint i = 0; i < n_queues; i++) {
1511 RefToScanQueue* q = new RefToScanQueue();
1512 q->initialize();
1513 _task_queues->register_queue(i, q);
1514 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1515 }
1516
1517 // Initialize the G1EvacuationFailureALot counters and flags.
1518 NOT_PRODUCT(reset_evacuation_should_fail();)
1519
1520 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1521 }
1522
1523 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1524 size_t size,
1525 size_t translation_factor) {
1526 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1527 // Allocate a new reserved space, preferring to use large pages.
1528 ReservedSpace rs(size, preferred_page_size);
1529 G1RegionToSpaceMapper* result =
1530 G1RegionToSpaceMapper::create_mapper(rs,
1531 size,
1532 rs.alignment(),
1533 HeapRegion::GrainBytes,
1534 translation_factor,
1535 mtGC);
1536
1537 os::trace_page_sizes_for_requested_size(description,
1538 size,
1539 preferred_page_size,
1540 rs.alignment(),
1541 rs.base(),
1542 rs.size());
1543
1544 return result;
1545 }
1546
1547 jint G1CollectedHeap::initialize_concurrent_refinement() {
1548 jint ecode = JNI_OK;
1549 _cr = G1ConcurrentRefine::create(&ecode);
1550 return ecode;
1551 }
1552
1553 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1554 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1555 if (_young_gen_sampling_thread->osthread() == NULL) {
1556 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1557 return JNI_ENOMEM;
1558 }
1559 return JNI_OK;
1560 }
1561
1562 jint G1CollectedHeap::initialize() {
1563 os::enable_vtime();
1564
1565 // Necessary to satisfy locking discipline assertions.
1566
1567 MutexLocker x(Heap_lock);
1568
1569 // While there are no constraints in the GC code that HeapWordSize
1570 // be any particular value, there are multiple other areas in the
1571 // system which believe this to be true (e.g. oop->object_size in some
1572 // cases incorrectly returns the size in wordSize units rather than
1573 // HeapWordSize).
1574 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1575
1576 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1577 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1578 size_t heap_alignment = collector_policy()->heap_alignment();
1579
1580 // Ensure that the sizes are properly aligned.
1581 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1582 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1583 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1584
1585 // Reserve the maximum.
1586
1587 // When compressed oops are enabled, the preferred heap base
1588 // is calculated by subtracting the requested size from the
1589 // 32Gb boundary and using the result as the base address for
1590 // heap reservation. If the requested size is not aligned to
1591 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1592 // into the ReservedHeapSpace constructor) then the actual
1593 // base of the reserved heap may end up differing from the
1594 // address that was requested (i.e. the preferred heap base).
1595 // If this happens then we could end up using a non-optimal
1596 // compressed oops mode.
1597
1598 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1599 heap_alignment);
1600
1601 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1602
1603 // Create the barrier set for the entire reserved region.
1604 G1SATBCardTableLoggingModRefBS* bs
1605 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1606 bs->initialize();
1607 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1608 set_barrier_set(bs);
1609
1610 // Create the hot card cache.
1611 _hot_card_cache = new G1HotCardCache(this);
1612
1613 // Carve out the G1 part of the heap.
1614 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1615 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1616 G1RegionToSpaceMapper* heap_storage =
1617 G1RegionToSpaceMapper::create_mapper(g1_rs,
1618 g1_rs.size(),
1619 page_size,
1620 HeapRegion::GrainBytes,
1621 1,
1622 mtJavaHeap);
1623 os::trace_page_sizes("Heap",
1624 collector_policy()->min_heap_byte_size(),
1625 max_byte_size,
1626 page_size,
1627 heap_rs.base(),
1628 heap_rs.size());
1629 heap_storage->set_mapping_changed_listener(&_listener);
1630
1631 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1632 G1RegionToSpaceMapper* bot_storage =
1633 create_aux_memory_mapper("Block Offset Table",
1634 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1635 G1BlockOffsetTable::heap_map_factor());
1636
1637 G1RegionToSpaceMapper* cardtable_storage =
1638 create_aux_memory_mapper("Card Table",
1639 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1640 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1641
1642 G1RegionToSpaceMapper* card_counts_storage =
1643 create_aux_memory_mapper("Card Counts Table",
1644 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1645 G1CardCounts::heap_map_factor());
1646
1647 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1648 G1RegionToSpaceMapper* prev_bitmap_storage =
1649 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1650 G1RegionToSpaceMapper* next_bitmap_storage =
1651 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1652
1653 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1654 g1_barrier_set()->initialize(cardtable_storage);
1655 // Do later initialization work for concurrent refinement.
1656 _hot_card_cache->initialize(card_counts_storage);
1657
1658 // 6843694 - ensure that the maximum region index can fit
1659 // in the remembered set structures.
1660 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1661 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1662
1663 // Also create a G1 rem set.
1664 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1665 _g1_rem_set->initialize(max_capacity(), max_regions());
1666
1667 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1668 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1669 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1670 "too many cards per region");
1671
1672 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1673
1674 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1675
1676 {
1677 HeapWord* start = _hrm.reserved().start();
1678 HeapWord* end = _hrm.reserved().end();
1679 size_t granularity = HeapRegion::GrainBytes;
1680
1681 _in_cset_fast_test.initialize(start, end, granularity);
1682 _humongous_reclaim_candidates.initialize(start, end, granularity);
1683 }
1684
1685 // Create the G1ConcurrentMark data structure and thread.
1686 // (Must do this late, so that "max_regions" is defined.)
1687 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1688 if (_cm == NULL || !_cm->completed_initialization()) {
1689 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1690 return JNI_ENOMEM;
1691 }
1692 _cmThread = _cm->cm_thread();
1693
1694 // Now expand into the initial heap size.
1695 if (!expand(init_byte_size, _workers)) {
1696 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1697 return JNI_ENOMEM;
1698 }
1699
1700 // Perform any initialization actions delegated to the policy.
1701 g1_policy()->init(this, &_collection_set);
1702
1703 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1704 SATB_Q_FL_lock,
1705 G1SATBProcessCompletedThreshold,
1706 Shared_SATB_Q_lock);
1707
1708 jint ecode = initialize_concurrent_refinement();
1709 if (ecode != JNI_OK) {
1710 return ecode;
1711 }
1712
1713 ecode = initialize_young_gen_sampling_thread();
1714 if (ecode != JNI_OK) {
1715 return ecode;
1716 }
1717
1718 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1719 DirtyCardQ_FL_lock,
1720 (int)concurrent_refine()->yellow_zone(),
1721 (int)concurrent_refine()->red_zone(),
1722 Shared_DirtyCardQ_lock,
1723 NULL, // fl_owner
1724 true); // init_free_ids
1725
1726 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1727 DirtyCardQ_FL_lock,
1728 -1, // never trigger processing
1729 -1, // no limit on length
1730 Shared_DirtyCardQ_lock,
1731 &JavaThread::dirty_card_queue_set());
1732
1733 // Here we allocate the dummy HeapRegion that is required by the
1734 // G1AllocRegion class.
1735 HeapRegion* dummy_region = _hrm.get_dummy_region();
1736
1737 // We'll re-use the same region whether the alloc region will
1738 // require BOT updates or not and, if it doesn't, then a non-young
1739 // region will complain that it cannot support allocations without
1740 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1741 dummy_region->set_eden();
1742 // Make sure it's full.
1743 dummy_region->set_top(dummy_region->end());
1744 G1AllocRegion::setup(this, dummy_region);
1745
1746 _allocator->init_mutator_alloc_region();
1747
1748 // Do create of the monitoring and management support so that
1749 // values in the heap have been properly initialized.
1750 _g1mm = new G1MonitoringSupport(this);
1751
1752 G1StringDedup::initialize();
1753
1754 _preserved_marks_set.init(ParallelGCThreads);
1755
1756 _collection_set.initialize(max_regions());
1757
1758 return JNI_OK;
1759 }
1760
1761 void G1CollectedHeap::initialize_serviceability() {
1762 _eden_pool = new G1EdenPool(this);
1763 _survivor_pool = new G1SurvivorPool(this);
1764 _old_pool = new G1OldGenPool(this);
1765
1766 _full_gc_memory_manager.add_pool(_eden_pool);
1767 _full_gc_memory_manager.add_pool(_survivor_pool);
1768 _full_gc_memory_manager.add_pool(_old_pool);
1769
1770 _memory_manager.add_pool(_eden_pool);
1771 _memory_manager.add_pool(_survivor_pool);
1772
1773 }
1774
1775 void G1CollectedHeap::stop() {
1776 // Stop all concurrent threads. We do this to make sure these threads
1777 // do not continue to execute and access resources (e.g. logging)
1778 // that are destroyed during shutdown.
1779 _cr->stop();
1780 _young_gen_sampling_thread->stop();
1781 _cmThread->stop();
1782 if (G1StringDedup::is_enabled()) {
1783 G1StringDedup::stop();
1784 }
1785 }
1786
1787 void G1CollectedHeap::safepoint_synchronize_begin() {
1788 SuspendibleThreadSet::synchronize();
1789 }
1790
1791 void G1CollectedHeap::safepoint_synchronize_end() {
1792 SuspendibleThreadSet::desynchronize();
1793 }
1794
1795 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1796 return HeapRegion::max_region_size();
1797 }
1798
1799 void G1CollectedHeap::post_initialize() {
1800 CollectedHeap::post_initialize();
1801 ref_processing_init();
1802 }
1803
1804 void G1CollectedHeap::ref_processing_init() {
1805 // Reference processing in G1 currently works as follows:
1806 //
1807 // * There are two reference processor instances. One is
1808 // used to record and process discovered references
1809 // during concurrent marking; the other is used to
1810 // record and process references during STW pauses
1811 // (both full and incremental).
1812 // * Both ref processors need to 'span' the entire heap as
1813 // the regions in the collection set may be dotted around.
1814 //
1815 // * For the concurrent marking ref processor:
1816 // * Reference discovery is enabled at initial marking.
1817 // * Reference discovery is disabled and the discovered
1818 // references processed etc during remarking.
1819 // * Reference discovery is MT (see below).
1820 // * Reference discovery requires a barrier (see below).
1821 // * Reference processing may or may not be MT
1822 // (depending on the value of ParallelRefProcEnabled
1823 // and ParallelGCThreads).
1824 // * A full GC disables reference discovery by the CM
1825 // ref processor and abandons any entries on it's
1826 // discovered lists.
1827 //
1828 // * For the STW processor:
1829 // * Non MT discovery is enabled at the start of a full GC.
1830 // * Processing and enqueueing during a full GC is non-MT.
1831 // * During a full GC, references are processed after marking.
1832 //
1833 // * Discovery (may or may not be MT) is enabled at the start
1834 // of an incremental evacuation pause.
1835 // * References are processed near the end of a STW evacuation pause.
1836 // * For both types of GC:
1837 // * Discovery is atomic - i.e. not concurrent.
1838 // * Reference discovery will not need a barrier.
1839
1840 MemRegion mr = reserved_region();
1841
1842 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1843
1844 // Concurrent Mark ref processor
1845 _ref_processor_cm =
1846 new ReferenceProcessor(mr, // span
1847 mt_processing,
1848 // mt processing
1849 ParallelGCThreads,
1850 // degree of mt processing
1851 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1852 // mt discovery
1853 MAX2(ParallelGCThreads, ConcGCThreads),
1854 // degree of mt discovery
1855 false,
1856 // Reference discovery is not atomic
1857 &_is_alive_closure_cm);
1858 // is alive closure
1859 // (for efficiency/performance)
1860
1861 // STW ref processor
1862 _ref_processor_stw =
1863 new ReferenceProcessor(mr, // span
1864 mt_processing,
1865 // mt processing
1866 ParallelGCThreads,
1867 // degree of mt processing
1868 (ParallelGCThreads > 1),
1869 // mt discovery
1870 ParallelGCThreads,
1871 // degree of mt discovery
1872 true,
1873 // Reference discovery is atomic
1874 &_is_alive_closure_stw);
1875 // is alive closure
1876 // (for efficiency/performance)
1877 }
1878
1879 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1880 return _collector_policy;
1881 }
1882
1883 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1884 return &_soft_ref_policy;
1885 }
1886
1887 size_t G1CollectedHeap::capacity() const {
1888 return _hrm.length() * HeapRegion::GrainBytes;
1889 }
1890
1891 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1892 return _hrm.total_free_bytes();
1893 }
1894
1895 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1896 hr->reset_gc_time_stamp();
1897 }
1898
1899 #ifndef PRODUCT
1900
1901 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1902 private:
1903 unsigned _gc_time_stamp;
1904 bool _failures;
1905
1906 public:
1907 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1908 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1909
1910 virtual bool do_heap_region(HeapRegion* hr) {
1911 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1912 if (_gc_time_stamp != region_gc_time_stamp) {
1913 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1914 region_gc_time_stamp, _gc_time_stamp);
1915 _failures = true;
1916 }
1917 return false;
1918 }
1919
1920 bool failures() { return _failures; }
1921 };
1922
1923 void G1CollectedHeap::check_gc_time_stamps() {
1924 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1925 heap_region_iterate(&cl);
1926 guarantee(!cl.failures(), "all GC time stamps should have been reset");
1927 }
1928 #endif // PRODUCT
1929
1930 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1931 _hot_card_cache->drain(cl, worker_i);
1932 }
1933
1934 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1935 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1936 size_t n_completed_buffers = 0;
1937 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1938 n_completed_buffers++;
1939 }
1940 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1941 dcqs.clear_n_completed_buffers();
1942 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1943 }
1944
1945 // Computes the sum of the storage used by the various regions.
1946 size_t G1CollectedHeap::used() const {
1947 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1948 if (_archive_allocator != NULL) {
1949 result += _archive_allocator->used();
1950 }
1951 return result;
1952 }
1953
1954 size_t G1CollectedHeap::used_unlocked() const {
1955 return _summary_bytes_used;
1956 }
1957
1958 class SumUsedClosure: public HeapRegionClosure {
1959 size_t _used;
1960 public:
1961 SumUsedClosure() : _used(0) {}
1962 bool do_heap_region(HeapRegion* r) {
1963 _used += r->used();
1964 return false;
1965 }
1966 size_t result() { return _used; }
1967 };
1968
1969 size_t G1CollectedHeap::recalculate_used() const {
1970 double recalculate_used_start = os::elapsedTime();
1971
1972 SumUsedClosure blk;
1973 heap_region_iterate(&blk);
1974
1975 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1976 return blk.result();
1977 }
1978
1979 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1980 switch (cause) {
1981 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1982 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1983 case GCCause::_wb_conc_mark: return true;
1984 default : return false;
1985 }
1986 }
1987
1988 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1989 switch (cause) {
1990 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1991 case GCCause::_g1_humongous_allocation: return true;
1992 default: return is_user_requested_concurrent_full_gc(cause);
1993 }
1994 }
1995
1996 #ifndef PRODUCT
1997 void G1CollectedHeap::allocate_dummy_regions() {
1998 // Let's fill up most of the region
1999 size_t word_size = HeapRegion::GrainWords - 1024;
2000 // And as a result the region we'll allocate will be humongous.
2001 guarantee(is_humongous(word_size), "sanity");
2002
2003 // _filler_array_max_size is set to humongous object threshold
2004 // but temporarily change it to use CollectedHeap::fill_with_object().
2005 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2006
2007 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2008 // Let's use the existing mechanism for the allocation
2009 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2010 if (dummy_obj != NULL) {
2011 MemRegion mr(dummy_obj, word_size);
2012 CollectedHeap::fill_with_object(mr);
2013 } else {
2014 // If we can't allocate once, we probably cannot allocate
2015 // again. Let's get out of the loop.
2016 break;
2017 }
2018 }
2019 }
2020 #endif // !PRODUCT
2021
2022 void G1CollectedHeap::increment_old_marking_cycles_started() {
2023 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2024 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2025 "Wrong marking cycle count (started: %d, completed: %d)",
2026 _old_marking_cycles_started, _old_marking_cycles_completed);
2027
2028 _old_marking_cycles_started++;
2029 }
2030
2031 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2032 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2033
2034 // We assume that if concurrent == true, then the caller is a
2035 // concurrent thread that was joined the Suspendible Thread
2036 // Set. If there's ever a cheap way to check this, we should add an
2037 // assert here.
2038
2039 // Given that this method is called at the end of a Full GC or of a
2040 // concurrent cycle, and those can be nested (i.e., a Full GC can
2041 // interrupt a concurrent cycle), the number of full collections
2042 // completed should be either one (in the case where there was no
2043 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2044 // behind the number of full collections started.
2045
2046 // This is the case for the inner caller, i.e. a Full GC.
2047 assert(concurrent ||
2048 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2049 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2050 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2051 "is inconsistent with _old_marking_cycles_completed = %u",
2052 _old_marking_cycles_started, _old_marking_cycles_completed);
2053
2054 // This is the case for the outer caller, i.e. the concurrent cycle.
2055 assert(!concurrent ||
2056 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2057 "for outer caller (concurrent cycle): "
2058 "_old_marking_cycles_started = %u "
2059 "is inconsistent with _old_marking_cycles_completed = %u",
2060 _old_marking_cycles_started, _old_marking_cycles_completed);
2061
2062 _old_marking_cycles_completed += 1;
2063
2064 // We need to clear the "in_progress" flag in the CM thread before
2065 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2066 // is set) so that if a waiter requests another System.gc() it doesn't
2067 // incorrectly see that a marking cycle is still in progress.
2068 if (concurrent) {
2069 _cmThread->set_idle();
2070 }
2071
2072 // This notify_all() will ensure that a thread that called
2073 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2074 // and it's waiting for a full GC to finish will be woken up. It is
2075 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2076 FullGCCount_lock->notify_all();
2077 }
2078
2079 void G1CollectedHeap::collect(GCCause::Cause cause) {
2080 assert_heap_not_locked();
2081
2082 uint gc_count_before;
2083 uint old_marking_count_before;
2084 uint full_gc_count_before;
2085 bool retry_gc;
2086
2087 do {
2088 retry_gc = false;
2089
2090 {
2091 MutexLocker ml(Heap_lock);
2092
2093 // Read the GC count while holding the Heap_lock
2094 gc_count_before = total_collections();
2095 full_gc_count_before = total_full_collections();
2096 old_marking_count_before = _old_marking_cycles_started;
2097 }
2098
2099 if (should_do_concurrent_full_gc(cause)) {
2100 // Schedule an initial-mark evacuation pause that will start a
2101 // concurrent cycle. We're setting word_size to 0 which means that
2102 // we are not requesting a post-GC allocation.
2103 VM_G1CollectForAllocation op(0, /* word_size */
2104 gc_count_before,
2105 cause,
2106 true, /* should_initiate_conc_mark */
2107 g1_policy()->max_pause_time_ms());
2108 VMThread::execute(&op);
2109 if (!op.pause_succeeded()) {
2110 if (old_marking_count_before == _old_marking_cycles_started) {
2111 retry_gc = op.should_retry_gc();
2112 } else {
2113 // A Full GC happened while we were trying to schedule the
2114 // initial-mark GC. No point in starting a new cycle given
2115 // that the whole heap was collected anyway.
2116 }
2117
2118 if (retry_gc) {
2119 if (GCLocker::is_active_and_needs_gc()) {
2120 GCLocker::stall_until_clear();
2121 }
2122 }
2123 }
2124 } else {
2125 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2126 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2127
2128 // Schedule a standard evacuation pause. We're setting word_size
2129 // to 0 which means that we are not requesting a post-GC allocation.
2130 VM_G1CollectForAllocation op(0, /* word_size */
2131 gc_count_before,
2132 cause,
2133 false, /* should_initiate_conc_mark */
2134 g1_policy()->max_pause_time_ms());
2135 VMThread::execute(&op);
2136 } else {
2137 // Schedule a Full GC.
2138 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2139 VMThread::execute(&op);
2140 }
2141 }
2142 } while (retry_gc);
2143 }
2144
2145 bool G1CollectedHeap::is_in(const void* p) const {
2146 if (_hrm.reserved().contains(p)) {
2147 // Given that we know that p is in the reserved space,
2148 // heap_region_containing() should successfully
2149 // return the containing region.
2150 HeapRegion* hr = heap_region_containing(p);
2151 return hr->is_in(p);
2152 } else {
2153 return false;
2154 }
2155 }
2156
2157 #ifdef ASSERT
2158 bool G1CollectedHeap::is_in_exact(const void* p) const {
2159 bool contains = reserved_region().contains(p);
2160 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2161 if (contains && available) {
2162 return true;
2163 } else {
2164 return false;
2165 }
2166 }
2167 #endif
2168
2169 // Iteration functions.
2170
2171 // Iterates an ObjectClosure over all objects within a HeapRegion.
2172
2173 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2174 ObjectClosure* _cl;
2175 public:
2176 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2177 bool do_heap_region(HeapRegion* r) {
2178 if (!r->is_continues_humongous()) {
2179 r->object_iterate(_cl);
2180 }
2181 return false;
2182 }
2183 };
2184
2185 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2186 IterateObjectClosureRegionClosure blk(cl);
2187 heap_region_iterate(&blk);
2188 }
2189
2190 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2191 _hrm.iterate(cl);
2192 }
2193
2194 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2195 HeapRegionClaimer *hrclaimer,
2196 uint worker_id) const {
2197 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2198 }
2199
2200 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2201 HeapRegionClaimer *hrclaimer) const {
2202 _hrm.par_iterate(cl, hrclaimer, 0);
2203 }
2204
2205 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2206 _collection_set.iterate(cl);
2207 }
2208
2209 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2210 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2211 }
2212
2213 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2214 HeapRegion* hr = heap_region_containing(addr);
2215 return hr->block_start(addr);
2216 }
2217
2218 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2219 HeapRegion* hr = heap_region_containing(addr);
2220 return hr->block_size(addr);
2221 }
2222
2223 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2224 HeapRegion* hr = heap_region_containing(addr);
2225 return hr->block_is_obj(addr);
2226 }
2227
2228 bool G1CollectedHeap::supports_tlab_allocation() const {
2229 return true;
2230 }
2231
2232 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2233 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2234 }
2235
2236 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2237 return _eden.length() * HeapRegion::GrainBytes;
2238 }
2239
2240 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2241 // must be equal to the humongous object limit.
2242 size_t G1CollectedHeap::max_tlab_size() const {
2243 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2244 }
2245
2246 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2247 return _allocator->unsafe_max_tlab_alloc();
2248 }
2249
2250 size_t G1CollectedHeap::max_capacity() const {
2251 return _hrm.reserved().byte_size();
2252 }
2253
2254 jlong G1CollectedHeap::millis_since_last_gc() {
2255 // See the notes in GenCollectedHeap::millis_since_last_gc()
2256 // for more information about the implementation.
2257 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2258 _g1_policy->collection_pause_end_millis();
2259 if (ret_val < 0) {
2260 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2261 ". returning zero instead.", ret_val);
2262 return 0;
2263 }
2264 return ret_val;
2265 }
2266
2267 void G1CollectedHeap::prepare_for_verify() {
2268 _verifier->prepare_for_verify();
2269 }
2270
2271 void G1CollectedHeap::verify(VerifyOption vo) {
2272 _verifier->verify(vo);
2273 }
2274
2275 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2276 return true;
2277 }
2278
2279 const char* const* G1CollectedHeap::concurrent_phases() const {
2280 return _cmThread->concurrent_phases();
2281 }
2282
2283 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2284 return _cmThread->request_concurrent_phase(phase);
2285 }
2286
2287 class PrintRegionClosure: public HeapRegionClosure {
2288 outputStream* _st;
2289 public:
2290 PrintRegionClosure(outputStream* st) : _st(st) {}
2291 bool do_heap_region(HeapRegion* r) {
2292 r->print_on(_st);
2293 return false;
2294 }
2295 };
2296
2297 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2298 const HeapRegion* hr,
2299 const VerifyOption vo) const {
2300 switch (vo) {
2301 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2302 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2303 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2304 default: ShouldNotReachHere();
2305 }
2306 return false; // keep some compilers happy
2307 }
2308
2309 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2310 const VerifyOption vo) const {
2311 switch (vo) {
2312 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2313 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2314 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2315 default: ShouldNotReachHere();
2316 }
2317 return false; // keep some compilers happy
2318 }
2319
2320 void G1CollectedHeap::print_heap_regions() const {
2321 LogTarget(Trace, gc, heap, region) lt;
2322 if (lt.is_enabled()) {
2323 LogStream ls(lt);
2324 print_regions_on(&ls);
2325 }
2326 }
2327
2328 void G1CollectedHeap::print_on(outputStream* st) const {
2329 st->print(" %-20s", "garbage-first heap");
2330 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2331 capacity()/K, used_unlocked()/K);
2332 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2333 p2i(_hrm.reserved().start()),
2334 p2i(_hrm.reserved().end()));
2335 st->cr();
2336 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2337 uint young_regions = young_regions_count();
2338 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2339 (size_t) young_regions * HeapRegion::GrainBytes / K);
2340 uint survivor_regions = survivor_regions_count();
2341 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2342 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2343 st->cr();
2344 MetaspaceAux::print_on(st);
2345 }
2346
2347 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2348 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2349 "HS=humongous(starts), HC=humongous(continues), "
2350 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2351 "TAMS=top-at-mark-start (previous, next)");
2352 PrintRegionClosure blk(st);
2353 heap_region_iterate(&blk);
2354 }
2355
2356 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2357 print_on(st);
2358
2359 // Print the per-region information.
2360 print_regions_on(st);
2361 }
2362
2363 void G1CollectedHeap::print_on_error(outputStream* st) const {
2364 this->CollectedHeap::print_on_error(st);
2365
2366 if (_cm != NULL) {
2367 st->cr();
2368 _cm->print_on_error(st);
2369 }
2370 }
2371
2372 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2373 workers()->print_worker_threads_on(st);
2374 _cmThread->print_on(st);
2375 st->cr();
2376 _cm->print_worker_threads_on(st);
2377 _cr->print_threads_on(st);
2378 _young_gen_sampling_thread->print_on(st);
2379 if (G1StringDedup::is_enabled()) {
2380 G1StringDedup::print_worker_threads_on(st);
2381 }
2382 }
2383
2384 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2385 workers()->threads_do(tc);
2386 tc->do_thread(_cmThread);
2387 _cm->threads_do(tc);
2388 _cr->threads_do(tc);
2389 tc->do_thread(_young_gen_sampling_thread);
2390 if (G1StringDedup::is_enabled()) {
2391 G1StringDedup::threads_do(tc);
2392 }
2393 }
2394
2395 void G1CollectedHeap::print_tracing_info() const {
2396 g1_rem_set()->print_summary_info();
2397 concurrent_mark()->print_summary_info();
2398 }
2399
2400 #ifndef PRODUCT
2401 // Helpful for debugging RSet issues.
2402
2403 class PrintRSetsClosure : public HeapRegionClosure {
2404 private:
2405 const char* _msg;
2406 size_t _occupied_sum;
2407
2408 public:
2409 bool do_heap_region(HeapRegion* r) {
2410 HeapRegionRemSet* hrrs = r->rem_set();
2411 size_t occupied = hrrs->occupied();
2412 _occupied_sum += occupied;
2413
2414 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2415 if (occupied == 0) {
2416 tty->print_cr(" RSet is empty");
2417 } else {
2418 hrrs->print();
2419 }
2420 tty->print_cr("----------");
2421 return false;
2422 }
2423
2424 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2425 tty->cr();
2426 tty->print_cr("========================================");
2427 tty->print_cr("%s", msg);
2428 tty->cr();
2429 }
2430
2431 ~PrintRSetsClosure() {
2432 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2433 tty->print_cr("========================================");
2434 tty->cr();
2435 }
2436 };
2437
2438 void G1CollectedHeap::print_cset_rsets() {
2439 PrintRSetsClosure cl("Printing CSet RSets");
2440 collection_set_iterate(&cl);
2441 }
2442
2443 void G1CollectedHeap::print_all_rsets() {
2444 PrintRSetsClosure cl("Printing All RSets");;
2445 heap_region_iterate(&cl);
2446 }
2447 #endif // PRODUCT
2448
2449 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2450
2451 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2452 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2453 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2454
2455 size_t eden_capacity_bytes =
2456 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2457
2458 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2459 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2460 eden_capacity_bytes, survivor_used_bytes, num_regions());
2461 }
2462
2463 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2464 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2465 stats->unused(), stats->used(), stats->region_end_waste(),
2466 stats->regions_filled(), stats->direct_allocated(),
2467 stats->failure_used(), stats->failure_waste());
2468 }
2469
2470 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2471 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2472 gc_tracer->report_gc_heap_summary(when, heap_summary);
2473
2474 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2475 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2476 }
2477
2478 G1CollectedHeap* G1CollectedHeap::heap() {
2479 CollectedHeap* heap = Universe::heap();
2480 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2481 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2482 return (G1CollectedHeap*)heap;
2483 }
2484
2485 void G1CollectedHeap::gc_prologue(bool full) {
2486 // always_do_update_barrier = false;
2487 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2488
2489 // This summary needs to be printed before incrementing total collections.
2490 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2491
2492 // Update common counters.
2493 increment_total_collections(full /* full gc */);
2494 if (full) {
2495 increment_old_marking_cycles_started();
2496 reset_gc_time_stamp();
2497 } else {
2498 increment_gc_time_stamp();
2499 }
2500
2501 // Fill TLAB's and such
2502 double start = os::elapsedTime();
2503 accumulate_statistics_all_tlabs();
2504 ensure_parsability(true);
2505 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2506 }
2507
2508 void G1CollectedHeap::gc_epilogue(bool full) {
2509 // Update common counters.
2510 if (full) {
2511 // Update the number of full collections that have been completed.
2512 increment_old_marking_cycles_completed(false /* concurrent */);
2513 }
2514
2515 // We are at the end of the GC. Total collections has already been increased.
2516 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2517
2518 // FIXME: what is this about?
2519 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2520 // is set.
2521 #if COMPILER2_OR_JVMCI
2522 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2523 #endif
2524 // always_do_update_barrier = true;
2525
2526 double start = os::elapsedTime();
2527 resize_all_tlabs();
2528 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2529
2530 MemoryService::track_memory_usage();
2531 // We have just completed a GC. Update the soft reference
2532 // policy with the new heap occupancy
2533 Universe::update_heap_info_at_gc();
2534 }
2535
2536 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2537 uint gc_count_before,
2538 bool* succeeded,
2539 GCCause::Cause gc_cause) {
2540 assert_heap_not_locked_and_not_at_safepoint();
2541 VM_G1CollectForAllocation op(word_size,
2542 gc_count_before,
2543 gc_cause,
2544 false, /* should_initiate_conc_mark */
2545 g1_policy()->max_pause_time_ms());
2546 VMThread::execute(&op);
2547
2548 HeapWord* result = op.result();
2549 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2550 assert(result == NULL || ret_succeeded,
2551 "the result should be NULL if the VM did not succeed");
2552 *succeeded = ret_succeeded;
2553
2554 assert_heap_not_locked();
2555 return result;
2556 }
2557
2558 void
2559 G1CollectedHeap::doConcurrentMark() {
2560 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2561 if (!_cmThread->in_progress()) {
2562 _cmThread->set_started();
2563 CGC_lock->notify();
2564 }
2565 }
2566
2567 size_t G1CollectedHeap::pending_card_num() {
2568 size_t extra_cards = 0;
2569 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2570 DirtyCardQueue& dcq = curr->dirty_card_queue();
2571 extra_cards += dcq.size();
2572 }
2573 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2574 size_t buffer_size = dcqs.buffer_size();
2575 size_t buffer_num = dcqs.completed_buffers_num();
2576
2577 return buffer_size * buffer_num + extra_cards;
2578 }
2579
2580 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2581 private:
2582 size_t _total_humongous;
2583 size_t _candidate_humongous;
2584
2585 DirtyCardQueue _dcq;
2586
2587 // We don't nominate objects with many remembered set entries, on
2588 // the assumption that such objects are likely still live.
2589 bool is_remset_small(HeapRegion* region) const {
2590 HeapRegionRemSet* const rset = region->rem_set();
2591 return G1EagerReclaimHumongousObjectsWithStaleRefs
2592 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2593 : rset->is_empty();
2594 }
2595
2596 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2597 assert(region->is_starts_humongous(), "Must start a humongous object");
2598
2599 oop obj = oop(region->bottom());
2600
2601 // Dead objects cannot be eager reclaim candidates. Due to class
2602 // unloading it is unsafe to query their classes so we return early.
2603 if (heap->is_obj_dead(obj, region)) {
2604 return false;
2605 }
2606
2607 // Candidate selection must satisfy the following constraints
2608 // while concurrent marking is in progress:
2609 //
2610 // * In order to maintain SATB invariants, an object must not be
2611 // reclaimed if it was allocated before the start of marking and
2612 // has not had its references scanned. Such an object must have
2613 // its references (including type metadata) scanned to ensure no
2614 // live objects are missed by the marking process. Objects
2615 // allocated after the start of concurrent marking don't need to
2616 // be scanned.
2617 //
2618 // * An object must not be reclaimed if it is on the concurrent
2619 // mark stack. Objects allocated after the start of concurrent
2620 // marking are never pushed on the mark stack.
2621 //
2622 // Nominating only objects allocated after the start of concurrent
2623 // marking is sufficient to meet both constraints. This may miss
2624 // some objects that satisfy the constraints, but the marking data
2625 // structures don't support efficiently performing the needed
2626 // additional tests or scrubbing of the mark stack.
2627 //
2628 // However, we presently only nominate is_typeArray() objects.
2629 // A humongous object containing references induces remembered
2630 // set entries on other regions. In order to reclaim such an
2631 // object, those remembered sets would need to be cleaned up.
2632 //
2633 // We also treat is_typeArray() objects specially, allowing them
2634 // to be reclaimed even if allocated before the start of
2635 // concurrent mark. For this we rely on mark stack insertion to
2636 // exclude is_typeArray() objects, preventing reclaiming an object
2637 // that is in the mark stack. We also rely on the metadata for
2638 // such objects to be built-in and so ensured to be kept live.
2639 // Frequent allocation and drop of large binary blobs is an
2640 // important use case for eager reclaim, and this special handling
2641 // may reduce needed headroom.
2642
2643 return obj->is_typeArray() && is_remset_small(region);
2644 }
2645
2646 public:
2647 RegisterHumongousWithInCSetFastTestClosure()
2648 : _total_humongous(0),
2649 _candidate_humongous(0),
2650 _dcq(&JavaThread::dirty_card_queue_set()) {
2651 }
2652
2653 virtual bool do_heap_region(HeapRegion* r) {
2654 if (!r->is_starts_humongous()) {
2655 return false;
2656 }
2657 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2658
2659 bool is_candidate = humongous_region_is_candidate(g1h, r);
2660 uint rindex = r->hrm_index();
2661 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2662 if (is_candidate) {
2663 _candidate_humongous++;
2664 g1h->register_humongous_region_with_cset(rindex);
2665 // Is_candidate already filters out humongous object with large remembered sets.
2666 // If we have a humongous object with a few remembered sets, we simply flush these
2667 // remembered set entries into the DCQS. That will result in automatic
2668 // re-evaluation of their remembered set entries during the following evacuation
2669 // phase.
2670 if (!r->rem_set()->is_empty()) {
2671 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2672 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2673 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2674 HeapRegionRemSetIterator hrrs(r->rem_set());
2675 size_t card_index;
2676 while (hrrs.has_next(card_index)) {
2677 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2678 // The remembered set might contain references to already freed
2679 // regions. Filter out such entries to avoid failing card table
2680 // verification.
2681 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2682 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2683 *card_ptr = CardTableModRefBS::dirty_card_val();
2684 _dcq.enqueue(card_ptr);
2685 }
2686 }
2687 }
2688 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2689 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2690 hrrs.n_yielded(), r->rem_set()->occupied());
2691 r->rem_set()->clear_locked();
2692 }
2693 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2694 }
2695 _total_humongous++;
2696
2697 return false;
2698 }
2699
2700 size_t total_humongous() const { return _total_humongous; }
2701 size_t candidate_humongous() const { return _candidate_humongous; }
2702
2703 void flush_rem_set_entries() { _dcq.flush(); }
2704 };
2705
2706 void G1CollectedHeap::register_humongous_regions_with_cset() {
2707 if (!G1EagerReclaimHumongousObjects) {
2708 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2709 return;
2710 }
2711 double time = os::elapsed_counter();
2712
2713 // Collect reclaim candidate information and register candidates with cset.
2714 RegisterHumongousWithInCSetFastTestClosure cl;
2715 heap_region_iterate(&cl);
2716
2717 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2718 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2719 cl.total_humongous(),
2720 cl.candidate_humongous());
2721 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2722
2723 // Finally flush all remembered set entries to re-check into the global DCQS.
2724 cl.flush_rem_set_entries();
2725 }
2726
2727 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2728 public:
2729 bool do_heap_region(HeapRegion* hr) {
2730 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2731 hr->verify_rem_set();
2732 }
2733 return false;
2734 }
2735 };
2736
2737 uint G1CollectedHeap::num_task_queues() const {
2738 return _task_queues->size();
2739 }
2740
2741 #if TASKQUEUE_STATS
2742 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2743 st->print_raw_cr("GC Task Stats");
2744 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2745 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2746 }
2747
2748 void G1CollectedHeap::print_taskqueue_stats() const {
2749 if (!log_is_enabled(Trace, gc, task, stats)) {
2750 return;
2751 }
2752 Log(gc, task, stats) log;
2753 ResourceMark rm;
2754 LogStream ls(log.trace());
2755 outputStream* st = &ls;
2756
2757 print_taskqueue_stats_hdr(st);
2758
2759 TaskQueueStats totals;
2760 const uint n = num_task_queues();
2761 for (uint i = 0; i < n; ++i) {
2762 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2763 totals += task_queue(i)->stats;
2764 }
2765 st->print_raw("tot "); totals.print(st); st->cr();
2766
2767 DEBUG_ONLY(totals.verify());
2768 }
2769
2770 void G1CollectedHeap::reset_taskqueue_stats() {
2771 const uint n = num_task_queues();
2772 for (uint i = 0; i < n; ++i) {
2773 task_queue(i)->stats.reset();
2774 }
2775 }
2776 #endif // TASKQUEUE_STATS
2777
2778 void G1CollectedHeap::wait_for_root_region_scanning() {
2779 double scan_wait_start = os::elapsedTime();
2780 // We have to wait until the CM threads finish scanning the
2781 // root regions as it's the only way to ensure that all the
2782 // objects on them have been correctly scanned before we start
2783 // moving them during the GC.
2784 bool waited = _cm->root_regions()->wait_until_scan_finished();
2785 double wait_time_ms = 0.0;
2786 if (waited) {
2787 double scan_wait_end = os::elapsedTime();
2788 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2789 }
2790 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2791 }
2792
2793 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2794 private:
2795 G1HRPrinter* _hr_printer;
2796 public:
2797 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2798
2799 virtual bool do_heap_region(HeapRegion* r) {
2800 _hr_printer->cset(r);
2801 return false;
2802 }
2803 };
2804
2805 void G1CollectedHeap::start_new_collection_set() {
2806 collection_set()->start_incremental_building();
2807
2808 clear_cset_fast_test();
2809
2810 guarantee(_eden.length() == 0, "eden should have been cleared");
2811 g1_policy()->transfer_survivors_to_cset(survivor());
2812 }
2813
2814 bool
2815 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2816 assert_at_safepoint(true /* should_be_vm_thread */);
2817 guarantee(!is_gc_active(), "collection is not reentrant");
2818
2819 if (GCLocker::check_active_before_gc()) {
2820 return false;
2821 }
2822
2823 _gc_timer_stw->register_gc_start();
2824
2825 GCIdMark gc_id_mark;
2826 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2827
2828 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2829 ResourceMark rm;
2830
2831 g1_policy()->note_gc_start();
2832
2833 wait_for_root_region_scanning();
2834
2835 print_heap_before_gc();
2836 print_heap_regions();
2837 trace_heap_before_gc(_gc_tracer_stw);
2838
2839 _verifier->verify_region_sets_optional();
2840 _verifier->verify_dirty_young_regions();
2841
2842 // We should not be doing initial mark unless the conc mark thread is running
2843 if (!_cmThread->should_terminate()) {
2844 // This call will decide whether this pause is an initial-mark
2845 // pause. If it is, during_initial_mark_pause() will return true
2846 // for the duration of this pause.
2847 g1_policy()->decide_on_conc_mark_initiation();
2848 }
2849
2850 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2851 assert(!collector_state()->during_initial_mark_pause() ||
2852 collector_state()->gcs_are_young(), "sanity");
2853
2854 // We also do not allow mixed GCs during marking.
2855 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2856
2857 // Record whether this pause is an initial mark. When the current
2858 // thread has completed its logging output and it's safe to signal
2859 // the CM thread, the flag's value in the policy has been reset.
2860 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2861
2862 // Inner scope for scope based logging, timers, and stats collection
2863 {
2864 EvacuationInfo evacuation_info;
2865
2866 if (collector_state()->during_initial_mark_pause()) {
2867 // We are about to start a marking cycle, so we increment the
2868 // full collection counter.
2869 increment_old_marking_cycles_started();
2870 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2871 }
2872
2873 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2874
2875 GCTraceCPUTime tcpu;
2876
2877 G1HeapVerifier::G1VerifyType verify_type;
2878 FormatBuffer<> gc_string("Pause ");
2879 if (collector_state()->during_initial_mark_pause()) {
2880 gc_string.append("Initial Mark");
2881 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2882 } else if (collector_state()->gcs_are_young()) {
2883 gc_string.append("Young");
2884 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2885 } else {
2886 gc_string.append("Mixed");
2887 verify_type = G1HeapVerifier::G1VerifyMixed;
2888 }
2889 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2890
2891 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2892 workers()->active_workers(),
2893 Threads::number_of_non_daemon_threads());
2894 workers()->update_active_workers(active_workers);
2895 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2896
2897 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2898 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2899
2900 // If the secondary_free_list is not empty, append it to the
2901 // free_list. No need to wait for the cleanup operation to finish;
2902 // the region allocation code will check the secondary_free_list
2903 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2904 // set, skip this step so that the region allocation code has to
2905 // get entries from the secondary_free_list.
2906 if (!G1StressConcRegionFreeing) {
2907 append_secondary_free_list_if_not_empty_with_lock();
2908 }
2909
2910 G1HeapTransition heap_transition(this);
2911 size_t heap_used_bytes_before_gc = used();
2912
2913 // Don't dynamically change the number of GC threads this early. A value of
2914 // 0 is used to indicate serial work. When parallel work is done,
2915 // it will be set.
2916
2917 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2918 IsGCActiveMark x;
2919
2920 gc_prologue(false);
2921
2922 if (VerifyRememberedSets) {
2923 log_info(gc, verify)("[Verifying RemSets before GC]");
2924 VerifyRegionRemSetClosure v_cl;
2925 heap_region_iterate(&v_cl);
2926 }
2927
2928 _verifier->verify_before_gc(verify_type);
2929
2930 _verifier->check_bitmaps("GC Start");
2931
2932 #if COMPILER2_OR_JVMCI
2933 DerivedPointerTable::clear();
2934 #endif
2935
2936 // Please see comment in g1CollectedHeap.hpp and
2937 // G1CollectedHeap::ref_processing_init() to see how
2938 // reference processing currently works in G1.
2939
2940 // Enable discovery in the STW reference processor
2941 if (g1_policy()->should_process_references()) {
2942 ref_processor_stw()->enable_discovery();
2943 } else {
2944 ref_processor_stw()->disable_discovery();
2945 }
2946
2947 {
2948 // We want to temporarily turn off discovery by the
2949 // CM ref processor, if necessary, and turn it back on
2950 // on again later if we do. Using a scoped
2951 // NoRefDiscovery object will do this.
2952 NoRefDiscovery no_cm_discovery(ref_processor_cm());
2953
2954 // Forget the current alloc region (we might even choose it to be part
2955 // of the collection set!).
2956 _allocator->release_mutator_alloc_region();
2957
2958 // This timing is only used by the ergonomics to handle our pause target.
2959 // It is unclear why this should not include the full pause. We will
2960 // investigate this in CR 7178365.
2961 //
2962 // Preserving the old comment here if that helps the investigation:
2963 //
2964 // The elapsed time induced by the start time below deliberately elides
2965 // the possible verification above.
2966 double sample_start_time_sec = os::elapsedTime();
2967
2968 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2969
2970 if (collector_state()->during_initial_mark_pause()) {
2971 concurrent_mark()->checkpoint_roots_initial_pre();
2972 }
2973
2974 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2975
2976 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2977
2978 // Make sure the remembered sets are up to date. This needs to be
2979 // done before register_humongous_regions_with_cset(), because the
2980 // remembered sets are used there to choose eager reclaim candidates.
2981 // If the remembered sets are not up to date we might miss some
2982 // entries that need to be handled.
2983 g1_rem_set()->cleanupHRRS();
2984
2985 register_humongous_regions_with_cset();
2986
2987 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2988
2989 // We call this after finalize_cset() to
2990 // ensure that the CSet has been finalized.
2991 _cm->verify_no_cset_oops();
2992
2993 if (_hr_printer.is_active()) {
2994 G1PrintCollectionSetClosure cl(&_hr_printer);
2995 _collection_set.iterate(&cl);
2996 }
2997
2998 // Initialize the GC alloc regions.
2999 _allocator->init_gc_alloc_regions(evacuation_info);
3000
3001 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3002 pre_evacuate_collection_set();
3003
3004 // Actually do the work...
3005 evacuate_collection_set(evacuation_info, &per_thread_states);
3006
3007 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3008
3009 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3010 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3011
3012 eagerly_reclaim_humongous_regions();
3013
3014 record_obj_copy_mem_stats();
3015 _survivor_evac_stats.adjust_desired_plab_sz();
3016 _old_evac_stats.adjust_desired_plab_sz();
3017
3018 double start = os::elapsedTime();
3019 start_new_collection_set();
3020 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3021
3022 if (evacuation_failed()) {
3023 set_used(recalculate_used());
3024 if (_archive_allocator != NULL) {
3025 _archive_allocator->clear_used();
3026 }
3027 for (uint i = 0; i < ParallelGCThreads; i++) {
3028 if (_evacuation_failed_info_array[i].has_failed()) {
3029 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3030 }
3031 }
3032 } else {
3033 // The "used" of the the collection set have already been subtracted
3034 // when they were freed. Add in the bytes evacuated.
3035 increase_used(g1_policy()->bytes_copied_during_gc());
3036 }
3037
3038 if (collector_state()->during_initial_mark_pause()) {
3039 // We have to do this before we notify the CM threads that
3040 // they can start working to make sure that all the
3041 // appropriate initialization is done on the CM object.
3042 concurrent_mark()->checkpoint_roots_initial_post();
3043 collector_state()->set_mark_in_progress(true);
3044 // Note that we don't actually trigger the CM thread at
3045 // this point. We do that later when we're sure that
3046 // the current thread has completed its logging output.
3047 }
3048
3049 allocate_dummy_regions();
3050
3051 _allocator->init_mutator_alloc_region();
3052
3053 {
3054 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3055 if (expand_bytes > 0) {
3056 size_t bytes_before = capacity();
3057 // No need for an ergo logging here,
3058 // expansion_amount() does this when it returns a value > 0.
3059 double expand_ms;
3060 if (!expand(expand_bytes, _workers, &expand_ms)) {
3061 // We failed to expand the heap. Cannot do anything about it.
3062 }
3063 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3064 }
3065 }
3066
3067 // We redo the verification but now wrt to the new CSet which
3068 // has just got initialized after the previous CSet was freed.
3069 _cm->verify_no_cset_oops();
3070
3071 // This timing is only used by the ergonomics to handle our pause target.
3072 // It is unclear why this should not include the full pause. We will
3073 // investigate this in CR 7178365.
3074 double sample_end_time_sec = os::elapsedTime();
3075 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3076 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3077 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3078
3079 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3080 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3081
3082 if (VerifyRememberedSets) {
3083 log_info(gc, verify)("[Verifying RemSets after GC]");
3084 VerifyRegionRemSetClosure v_cl;
3085 heap_region_iterate(&v_cl);
3086 }
3087
3088 _verifier->verify_after_gc(verify_type);
3089 _verifier->check_bitmaps("GC End");
3090
3091 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3092 ref_processor_stw()->verify_no_references_recorded();
3093
3094 // CM reference discovery will be re-enabled if necessary.
3095 }
3096
3097 #ifdef TRACESPINNING
3098 ParallelTaskTerminator::print_termination_counts();
3099 #endif
3100
3101 gc_epilogue(false);
3102 }
3103
3104 // Print the remainder of the GC log output.
3105 if (evacuation_failed()) {
3106 log_info(gc)("To-space exhausted");
3107 }
3108
3109 g1_policy()->print_phases();
3110 heap_transition.print();
3111
3112 // It is not yet to safe to tell the concurrent mark to
3113 // start as we have some optional output below. We don't want the
3114 // output from the concurrent mark thread interfering with this
3115 // logging output either.
3116
3117 _hrm.verify_optional();
3118 _verifier->verify_region_sets_optional();
3119
3120 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3121 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3122
3123 print_heap_after_gc();
3124 print_heap_regions();
3125 trace_heap_after_gc(_gc_tracer_stw);
3126
3127 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3128 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3129 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3130 // before any GC notifications are raised.
3131 g1mm()->update_sizes();
3132
3133 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3134 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3135 _gc_timer_stw->register_gc_end();
3136 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3137 }
3138 // It should now be safe to tell the concurrent mark thread to start
3139 // without its logging output interfering with the logging output
3140 // that came from the pause.
3141
3142 if (should_start_conc_mark) {
3143 // CAUTION: after the doConcurrentMark() call below,
3144 // the concurrent marking thread(s) could be running
3145 // concurrently with us. Make sure that anything after
3146 // this point does not assume that we are the only GC thread
3147 // running. Note: of course, the actual marking work will
3148 // not start until the safepoint itself is released in
3149 // SuspendibleThreadSet::desynchronize().
3150 doConcurrentMark();
3151 }
3152
3153 return true;
3154 }
3155
3156 void G1CollectedHeap::remove_self_forwarding_pointers() {
3157 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3158 workers()->run_task(&rsfp_task);
3159 }
3160
3161 void G1CollectedHeap::restore_after_evac_failure() {
3162 double remove_self_forwards_start = os::elapsedTime();
3163
3164 remove_self_forwarding_pointers();
3165 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3166 _preserved_marks_set.restore(&task_executor);
3167
3168 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3169 }
3170
3171 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3172 if (!_evacuation_failed) {
3173 _evacuation_failed = true;
3174 }
3175
3176 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3177 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3178 }
3179
3180 bool G1ParEvacuateFollowersClosure::offer_termination() {
3181 G1ParScanThreadState* const pss = par_scan_state();
3182 start_term_time();
3183 const bool res = terminator()->offer_termination();
3184 end_term_time();
3185 return res;
3186 }
3187
3188 void G1ParEvacuateFollowersClosure::do_void() {
3189 G1ParScanThreadState* const pss = par_scan_state();
3190 pss->trim_queue();
3191 do {
3192 pss->steal_and_trim_queue(queues());
3193 } while (!offer_termination());
3194 }
3195
3196 class G1ParTask : public AbstractGangTask {
3197 protected:
3198 G1CollectedHeap* _g1h;
3199 G1ParScanThreadStateSet* _pss;
3200 RefToScanQueueSet* _queues;
3201 G1RootProcessor* _root_processor;
3202 ParallelTaskTerminator _terminator;
3203 uint _n_workers;
3204
3205 public:
3206 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3207 : AbstractGangTask("G1 collection"),
3208 _g1h(g1h),
3209 _pss(per_thread_states),
3210 _queues(task_queues),
3211 _root_processor(root_processor),
3212 _terminator(n_workers, _queues),
3213 _n_workers(n_workers)
3214 {}
3215
3216 void work(uint worker_id) {
3217 if (worker_id >= _n_workers) return; // no work needed this round
3218
3219 double start_sec = os::elapsedTime();
3220 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3221
3222 {
3223 ResourceMark rm;
3224 HandleMark hm;
3225
3226 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3227
3228 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3229 pss->set_ref_processor(rp);
3230
3231 double start_strong_roots_sec = os::elapsedTime();
3232
3233 _root_processor->evacuate_roots(pss->closures(), worker_id);
3234
3235 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3236 // treating the nmethods visited to act as roots for concurrent marking.
3237 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3238 // objects copied by the current evacuation.
3239 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3240 pss->closures()->weak_codeblobs(),
3241 worker_id);
3242
3243 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3244
3245 double term_sec = 0.0;
3246 size_t evac_term_attempts = 0;
3247 {
3248 double start = os::elapsedTime();
3249 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3250 evac.do_void();
3251
3252 evac_term_attempts = evac.term_attempts();
3253 term_sec = evac.term_time();
3254 double elapsed_sec = os::elapsedTime() - start;
3255 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3256 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3257 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3258 }
3259
3260 assert(pss->queue_is_empty(), "should be empty");
3261
3262 if (log_is_enabled(Debug, gc, task, stats)) {
3263 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3264 size_t lab_waste;
3265 size_t lab_undo_waste;
3266 pss->waste(lab_waste, lab_undo_waste);
3267 _g1h->print_termination_stats(worker_id,
3268 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3269 strong_roots_sec * 1000.0, /* strong roots time */
3270 term_sec * 1000.0, /* evac term time */
3271 evac_term_attempts, /* evac term attempts */
3272 lab_waste, /* alloc buffer waste */
3273 lab_undo_waste /* undo waste */
3274 );
3275 }
3276
3277 // Close the inner scope so that the ResourceMark and HandleMark
3278 // destructors are executed here and are included as part of the
3279 // "GC Worker Time".
3280 }
3281 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3282 }
3283 };
3284
3285 void G1CollectedHeap::print_termination_stats_hdr() {
3286 log_debug(gc, task, stats)("GC Termination Stats");
3287 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3288 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3289 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3290 }
3291
3292 void G1CollectedHeap::print_termination_stats(uint worker_id,
3293 double elapsed_ms,
3294 double strong_roots_ms,
3295 double term_ms,
3296 size_t term_attempts,
3297 size_t alloc_buffer_waste,
3298 size_t undo_waste) const {
3299 log_debug(gc, task, stats)
3300 ("%3d %9.2f %9.2f %6.2f "
3301 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3302 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3303 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3304 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3305 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3306 alloc_buffer_waste * HeapWordSize / K,
3307 undo_waste * HeapWordSize / K);
3308 }
3309
3310 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3311 private:
3312 BoolObjectClosure* _is_alive;
3313 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3314
3315 int _initial_string_table_size;
3316 int _initial_symbol_table_size;
3317
3318 bool _process_strings;
3319 int _strings_processed;
3320 int _strings_removed;
3321
3322 bool _process_symbols;
3323 int _symbols_processed;
3324 int _symbols_removed;
3325
3326 bool _process_string_dedup;
3327
3328 public:
3329 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3330 AbstractGangTask("String/Symbol Unlinking"),
3331 _is_alive(is_alive),
3332 _dedup_closure(is_alive, NULL, false),
3333 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3334 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3335 _process_string_dedup(process_string_dedup) {
3336
3337 _initial_string_table_size = StringTable::the_table()->table_size();
3338 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3339 if (process_strings) {
3340 StringTable::clear_parallel_claimed_index();
3341 }
3342 if (process_symbols) {
3343 SymbolTable::clear_parallel_claimed_index();
3344 }
3345 }
3346
3347 ~G1StringAndSymbolCleaningTask() {
3348 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3349 "claim value %d after unlink less than initial string table size %d",
3350 StringTable::parallel_claimed_index(), _initial_string_table_size);
3351 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3352 "claim value %d after unlink less than initial symbol table size %d",
3353 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3354
3355 log_info(gc, stringtable)(
3356 "Cleaned string and symbol table, "
3357 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3358 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3359 strings_processed(), strings_removed(),
3360 symbols_processed(), symbols_removed());
3361 }
3362
3363 void work(uint worker_id) {
3364 int strings_processed = 0;
3365 int strings_removed = 0;
3366 int symbols_processed = 0;
3367 int symbols_removed = 0;
3368 if (_process_strings) {
3369 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3370 Atomic::add(strings_processed, &_strings_processed);
3371 Atomic::add(strings_removed, &_strings_removed);
3372 }
3373 if (_process_symbols) {
3374 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3375 Atomic::add(symbols_processed, &_symbols_processed);
3376 Atomic::add(symbols_removed, &_symbols_removed);
3377 }
3378 if (_process_string_dedup) {
3379 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3380 }
3381 }
3382
3383 size_t strings_processed() const { return (size_t)_strings_processed; }
3384 size_t strings_removed() const { return (size_t)_strings_removed; }
3385
3386 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3387 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3388 };
3389
3390 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3391 private:
3392 static Monitor* _lock;
3393
3394 BoolObjectClosure* const _is_alive;
3395 const bool _unloading_occurred;
3396 const uint _num_workers;
3397
3398 // Variables used to claim nmethods.
3399 CompiledMethod* _first_nmethod;
3400 CompiledMethod* volatile _claimed_nmethod;
3401
3402 // The list of nmethods that need to be processed by the second pass.
3403 CompiledMethod* volatile _postponed_list;
3404 volatile uint _num_entered_barrier;
3405
3406 public:
3407 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3408 _is_alive(is_alive),
3409 _unloading_occurred(unloading_occurred),
3410 _num_workers(num_workers),
3411 _first_nmethod(NULL),
3412 _claimed_nmethod(NULL),
3413 _postponed_list(NULL),
3414 _num_entered_barrier(0)
3415 {
3416 CompiledMethod::increase_unloading_clock();
3417 // Get first alive nmethod
3418 CompiledMethodIterator iter = CompiledMethodIterator();
3419 if(iter.next_alive()) {
3420 _first_nmethod = iter.method();
3421 }
3422 _claimed_nmethod = _first_nmethod;
3423 }
3424
3425 ~G1CodeCacheUnloadingTask() {
3426 CodeCache::verify_clean_inline_caches();
3427
3428 CodeCache::set_needs_cache_clean(false);
3429 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3430
3431 CodeCache::verify_icholder_relocations();
3432 }
3433
3434 private:
3435 void add_to_postponed_list(CompiledMethod* nm) {
3436 CompiledMethod* old;
3437 do {
3438 old = _postponed_list;
3439 nm->set_unloading_next(old);
3440 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3441 }
3442
3443 void clean_nmethod(CompiledMethod* nm) {
3444 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3445
3446 if (postponed) {
3447 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3448 add_to_postponed_list(nm);
3449 }
3450
3451 // Mark that this thread has been cleaned/unloaded.
3452 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3453 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3454 }
3455
3456 void clean_nmethod_postponed(CompiledMethod* nm) {
3457 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3458 }
3459
3460 static const int MaxClaimNmethods = 16;
3461
3462 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3463 CompiledMethod* first;
3464 CompiledMethodIterator last;
3465
3466 do {
3467 *num_claimed_nmethods = 0;
3468
3469 first = _claimed_nmethod;
3470 last = CompiledMethodIterator(first);
3471
3472 if (first != NULL) {
3473
3474 for (int i = 0; i < MaxClaimNmethods; i++) {
3475 if (!last.next_alive()) {
3476 break;
3477 }
3478 claimed_nmethods[i] = last.method();
3479 (*num_claimed_nmethods)++;
3480 }
3481 }
3482
3483 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3484 }
3485
3486 CompiledMethod* claim_postponed_nmethod() {
3487 CompiledMethod* claim;
3488 CompiledMethod* next;
3489
3490 do {
3491 claim = _postponed_list;
3492 if (claim == NULL) {
3493 return NULL;
3494 }
3495
3496 next = claim->unloading_next();
3497
3498 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3499
3500 return claim;
3501 }
3502
3503 public:
3504 // Mark that we're done with the first pass of nmethod cleaning.
3505 void barrier_mark(uint worker_id) {
3506 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3507 _num_entered_barrier++;
3508 if (_num_entered_barrier == _num_workers) {
3509 ml.notify_all();
3510 }
3511 }
3512
3513 // See if we have to wait for the other workers to
3514 // finish their first-pass nmethod cleaning work.
3515 void barrier_wait(uint worker_id) {
3516 if (_num_entered_barrier < _num_workers) {
3517 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3518 while (_num_entered_barrier < _num_workers) {
3519 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3520 }
3521 }
3522 }
3523
3524 // Cleaning and unloading of nmethods. Some work has to be postponed
3525 // to the second pass, when we know which nmethods survive.
3526 void work_first_pass(uint worker_id) {
3527 // The first nmethods is claimed by the first worker.
3528 if (worker_id == 0 && _first_nmethod != NULL) {
3529 clean_nmethod(_first_nmethod);
3530 _first_nmethod = NULL;
3531 }
3532
3533 int num_claimed_nmethods;
3534 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3535
3536 while (true) {
3537 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3538
3539 if (num_claimed_nmethods == 0) {
3540 break;
3541 }
3542
3543 for (int i = 0; i < num_claimed_nmethods; i++) {
3544 clean_nmethod(claimed_nmethods[i]);
3545 }
3546 }
3547 }
3548
3549 void work_second_pass(uint worker_id) {
3550 CompiledMethod* nm;
3551 // Take care of postponed nmethods.
3552 while ((nm = claim_postponed_nmethod()) != NULL) {
3553 clean_nmethod_postponed(nm);
3554 }
3555 }
3556 };
3557
3558 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3559
3560 class G1KlassCleaningTask : public StackObj {
3561 BoolObjectClosure* _is_alive;
3562 volatile int _clean_klass_tree_claimed;
3563 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3564
3565 public:
3566 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3567 _is_alive(is_alive),
3568 _clean_klass_tree_claimed(0),
3569 _klass_iterator() {
3570 }
3571
3572 private:
3573 bool claim_clean_klass_tree_task() {
3574 if (_clean_klass_tree_claimed) {
3575 return false;
3576 }
3577
3578 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3579 }
3580
3581 InstanceKlass* claim_next_klass() {
3582 Klass* klass;
3583 do {
3584 klass =_klass_iterator.next_klass();
3585 } while (klass != NULL && !klass->is_instance_klass());
3586
3587 // this can be null so don't call InstanceKlass::cast
3588 return static_cast<InstanceKlass*>(klass);
3589 }
3590
3591 public:
3592
3593 void clean_klass(InstanceKlass* ik) {
3594 ik->clean_weak_instanceklass_links(_is_alive);
3595 }
3596
3597 void work() {
3598 ResourceMark rm;
3599
3600 // One worker will clean the subklass/sibling klass tree.
3601 if (claim_clean_klass_tree_task()) {
3602 Klass::clean_subklass_tree(_is_alive);
3603 }
3604
3605 // All workers will help cleaning the classes,
3606 InstanceKlass* klass;
3607 while ((klass = claim_next_klass()) != NULL) {
3608 clean_klass(klass);
3609 }
3610 }
3611 };
3612
3613 class G1ResolvedMethodCleaningTask : public StackObj {
3614 BoolObjectClosure* _is_alive;
3615 volatile int _resolved_method_task_claimed;
3616 public:
3617 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3618 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3619
3620 bool claim_resolved_method_task() {
3621 if (_resolved_method_task_claimed) {
3622 return false;
3623 }
3624 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3625 }
3626
3627 // These aren't big, one thread can do it all.
3628 void work() {
3629 if (claim_resolved_method_task()) {
3630 ResolvedMethodTable::unlink(_is_alive);
3631 }
3632 }
3633 };
3634
3635
3636 // To minimize the remark pause times, the tasks below are done in parallel.
3637 class G1ParallelCleaningTask : public AbstractGangTask {
3638 private:
3639 G1StringAndSymbolCleaningTask _string_symbol_task;
3640 G1CodeCacheUnloadingTask _code_cache_task;
3641 G1KlassCleaningTask _klass_cleaning_task;
3642 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3643
3644 public:
3645 // The constructor is run in the VMThread.
3646 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3647 AbstractGangTask("Parallel Cleaning"),
3648 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3649 _code_cache_task(num_workers, is_alive, unloading_occurred),
3650 _klass_cleaning_task(is_alive),
3651 _resolved_method_cleaning_task(is_alive) {
3652 }
3653
3654 // The parallel work done by all worker threads.
3655 void work(uint worker_id) {
3656 // Do first pass of code cache cleaning.
3657 _code_cache_task.work_first_pass(worker_id);
3658
3659 // Let the threads mark that the first pass is done.
3660 _code_cache_task.barrier_mark(worker_id);
3661
3662 // Clean the Strings and Symbols.
3663 _string_symbol_task.work(worker_id);
3664
3665 // Clean unreferenced things in the ResolvedMethodTable
3666 _resolved_method_cleaning_task.work();
3667
3668 // Wait for all workers to finish the first code cache cleaning pass.
3669 _code_cache_task.barrier_wait(worker_id);
3670
3671 // Do the second code cache cleaning work, which realize on
3672 // the liveness information gathered during the first pass.
3673 _code_cache_task.work_second_pass(worker_id);
3674
3675 // Clean all klasses that were not unloaded.
3676 _klass_cleaning_task.work();
3677 }
3678 };
3679
3680
3681 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3682 bool class_unloading_occurred) {
3683 uint n_workers = workers()->active_workers();
3684
3685 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3686 workers()->run_task(&g1_unlink_task);
3687 }
3688
3689 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3690 bool process_strings,
3691 bool process_symbols,
3692 bool process_string_dedup) {
3693 if (!process_strings && !process_symbols && !process_string_dedup) {
3694 // Nothing to clean.
3695 return;
3696 }
3697
3698 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3699 workers()->run_task(&g1_unlink_task);
3700
3701 }
3702
3703 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3704 private:
3705 DirtyCardQueueSet* _queue;
3706 G1CollectedHeap* _g1h;
3707 public:
3708 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3709 _queue(queue), _g1h(g1h) { }
3710
3711 virtual void work(uint worker_id) {
3712 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3713 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3714
3715 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3716 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3717
3718 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3719 }
3720 };
3721
3722 void G1CollectedHeap::redirty_logged_cards() {
3723 double redirty_logged_cards_start = os::elapsedTime();
3724
3725 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3726 dirty_card_queue_set().reset_for_par_iteration();
3727 workers()->run_task(&redirty_task);
3728
3729 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3730 dcq.merge_bufferlists(&dirty_card_queue_set());
3731 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3732
3733 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3734 }
3735
3736 // Weak Reference Processing support
3737
3738 // An always "is_alive" closure that is used to preserve referents.
3739 // If the object is non-null then it's alive. Used in the preservation
3740 // of referent objects that are pointed to by reference objects
3741 // discovered by the CM ref processor.
3742 class G1AlwaysAliveClosure: public BoolObjectClosure {
3743 G1CollectedHeap* _g1;
3744 public:
3745 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3746 bool do_object_b(oop p) {
3747 if (p != NULL) {
3748 return true;
3749 }
3750 return false;
3751 }
3752 };
3753
3754 bool G1STWIsAliveClosure::do_object_b(oop p) {
3755 // An object is reachable if it is outside the collection set,
3756 // or is inside and copied.
3757 return !_g1->is_in_cset(p) || p->is_forwarded();
3758 }
3759
3760 // Non Copying Keep Alive closure
3761 class G1KeepAliveClosure: public OopClosure {
3762 G1CollectedHeap* _g1;
3763 public:
3764 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3765 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3766 void do_oop(oop* p) {
3767 oop obj = *p;
3768 assert(obj != NULL, "the caller should have filtered out NULL values");
3769
3770 const InCSetState cset_state = _g1->in_cset_state(obj);
3771 if (!cset_state.is_in_cset_or_humongous()) {
3772 return;
3773 }
3774 if (cset_state.is_in_cset()) {
3775 assert( obj->is_forwarded(), "invariant" );
3776 *p = obj->forwardee();
3777 } else {
3778 assert(!obj->is_forwarded(), "invariant" );
3779 assert(cset_state.is_humongous(),
3780 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3781 _g1->set_humongous_is_live(obj);
3782 }
3783 }
3784 };
3785
3786 // Copying Keep Alive closure - can be called from both
3787 // serial and parallel code as long as different worker
3788 // threads utilize different G1ParScanThreadState instances
3789 // and different queues.
3790
3791 class G1CopyingKeepAliveClosure: public OopClosure {
3792 G1CollectedHeap* _g1h;
3793 OopClosure* _copy_non_heap_obj_cl;
3794 G1ParScanThreadState* _par_scan_state;
3795
3796 public:
3797 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3798 OopClosure* non_heap_obj_cl,
3799 G1ParScanThreadState* pss):
3800 _g1h(g1h),
3801 _copy_non_heap_obj_cl(non_heap_obj_cl),
3802 _par_scan_state(pss)
3803 {}
3804
3805 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3806 virtual void do_oop( oop* p) { do_oop_work(p); }
3807
3808 template <class T> void do_oop_work(T* p) {
3809 oop obj = oopDesc::load_decode_heap_oop(p);
3810
3811 if (_g1h->is_in_cset_or_humongous(obj)) {
3812 // If the referent object has been forwarded (either copied
3813 // to a new location or to itself in the event of an
3814 // evacuation failure) then we need to update the reference
3815 // field and, if both reference and referent are in the G1
3816 // heap, update the RSet for the referent.
3817 //
3818 // If the referent has not been forwarded then we have to keep
3819 // it alive by policy. Therefore we have copy the referent.
3820 //
3821 // If the reference field is in the G1 heap then we can push
3822 // on the PSS queue. When the queue is drained (after each
3823 // phase of reference processing) the object and it's followers
3824 // will be copied, the reference field set to point to the
3825 // new location, and the RSet updated. Otherwise we need to
3826 // use the the non-heap or metadata closures directly to copy
3827 // the referent object and update the pointer, while avoiding
3828 // updating the RSet.
3829
3830 if (_g1h->is_in_g1_reserved(p)) {
3831 _par_scan_state->push_on_queue(p);
3832 } else {
3833 assert(!Metaspace::contains((const void*)p),
3834 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3835 _copy_non_heap_obj_cl->do_oop(p);
3836 }
3837 }
3838 }
3839 };
3840
3841 // Serial drain queue closure. Called as the 'complete_gc'
3842 // closure for each discovered list in some of the
3843 // reference processing phases.
3844
3845 class G1STWDrainQueueClosure: public VoidClosure {
3846 protected:
3847 G1CollectedHeap* _g1h;
3848 G1ParScanThreadState* _par_scan_state;
3849
3850 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3851
3852 public:
3853 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3854 _g1h(g1h),
3855 _par_scan_state(pss)
3856 { }
3857
3858 void do_void() {
3859 G1ParScanThreadState* const pss = par_scan_state();
3860 pss->trim_queue();
3861 }
3862 };
3863
3864 // Parallel Reference Processing closures
3865
3866 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3867 // processing during G1 evacuation pauses.
3868
3869 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3870 private:
3871 G1CollectedHeap* _g1h;
3872 G1ParScanThreadStateSet* _pss;
3873 RefToScanQueueSet* _queues;
3874 WorkGang* _workers;
3875 uint _active_workers;
3876
3877 public:
3878 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3879 G1ParScanThreadStateSet* per_thread_states,
3880 WorkGang* workers,
3881 RefToScanQueueSet *task_queues,
3882 uint n_workers) :
3883 _g1h(g1h),
3884 _pss(per_thread_states),
3885 _queues(task_queues),
3886 _workers(workers),
3887 _active_workers(n_workers)
3888 {
3889 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3890 }
3891
3892 // Executes the given task using concurrent marking worker threads.
3893 virtual void execute(ProcessTask& task);
3894 virtual void execute(EnqueueTask& task);
3895 };
3896
3897 // Gang task for possibly parallel reference processing
3898
3899 class G1STWRefProcTaskProxy: public AbstractGangTask {
3900 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3901 ProcessTask& _proc_task;
3902 G1CollectedHeap* _g1h;
3903 G1ParScanThreadStateSet* _pss;
3904 RefToScanQueueSet* _task_queues;
3905 ParallelTaskTerminator* _terminator;
3906
3907 public:
3908 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3909 G1CollectedHeap* g1h,
3910 G1ParScanThreadStateSet* per_thread_states,
3911 RefToScanQueueSet *task_queues,
3912 ParallelTaskTerminator* terminator) :
3913 AbstractGangTask("Process reference objects in parallel"),
3914 _proc_task(proc_task),
3915 _g1h(g1h),
3916 _pss(per_thread_states),
3917 _task_queues(task_queues),
3918 _terminator(terminator)
3919 {}
3920
3921 virtual void work(uint worker_id) {
3922 // The reference processing task executed by a single worker.
3923 ResourceMark rm;
3924 HandleMark hm;
3925
3926 G1STWIsAliveClosure is_alive(_g1h);
3927
3928 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3929 pss->set_ref_processor(NULL);
3930
3931 // Keep alive closure.
3932 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3933
3934 // Complete GC closure
3935 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3936
3937 // Call the reference processing task's work routine.
3938 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3939
3940 // Note we cannot assert that the refs array is empty here as not all
3941 // of the processing tasks (specifically phase2 - pp2_work) execute
3942 // the complete_gc closure (which ordinarily would drain the queue) so
3943 // the queue may not be empty.
3944 }
3945 };
3946
3947 // Driver routine for parallel reference processing.
3948 // Creates an instance of the ref processing gang
3949 // task and has the worker threads execute it.
3950 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3951 assert(_workers != NULL, "Need parallel worker threads.");
3952
3953 ParallelTaskTerminator terminator(_active_workers, _queues);
3954 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3955
3956 _workers->run_task(&proc_task_proxy);
3957 }
3958
3959 // Gang task for parallel reference enqueueing.
3960
3961 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3962 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3963 EnqueueTask& _enq_task;
3964
3965 public:
3966 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3967 AbstractGangTask("Enqueue reference objects in parallel"),
3968 _enq_task(enq_task)
3969 { }
3970
3971 virtual void work(uint worker_id) {
3972 _enq_task.work(worker_id);
3973 }
3974 };
3975
3976 // Driver routine for parallel reference enqueueing.
3977 // Creates an instance of the ref enqueueing gang
3978 // task and has the worker threads execute it.
3979
3980 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
3981 assert(_workers != NULL, "Need parallel worker threads.");
3982
3983 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
3984
3985 _workers->run_task(&enq_task_proxy);
3986 }
3987
3988 // End of weak reference support closures
3989
3990 // Abstract task used to preserve (i.e. copy) any referent objects
3991 // that are in the collection set and are pointed to by reference
3992 // objects discovered by the CM ref processor.
3993
3994 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
3995 protected:
3996 G1CollectedHeap* _g1h;
3997 G1ParScanThreadStateSet* _pss;
3998 RefToScanQueueSet* _queues;
3999 ParallelTaskTerminator _terminator;
4000 uint _n_workers;
4001
4002 public:
4003 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4004 AbstractGangTask("ParPreserveCMReferents"),
4005 _g1h(g1h),
4006 _pss(per_thread_states),
4007 _queues(task_queues),
4008 _terminator(workers, _queues),
4009 _n_workers(workers)
4010 {
4011 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4012 }
4013
4014 void work(uint worker_id) {
4015 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4016
4017 ResourceMark rm;
4018 HandleMark hm;
4019
4020 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4021 pss->set_ref_processor(NULL);
4022 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4023
4024 // Is alive closure
4025 G1AlwaysAliveClosure always_alive(_g1h);
4026
4027 // Copying keep alive closure. Applied to referent objects that need
4028 // to be copied.
4029 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4030
4031 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4032
4033 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4034 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4035
4036 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4037 // So this must be true - but assert just in case someone decides to
4038 // change the worker ids.
4039 assert(worker_id < limit, "sanity");
4040 assert(!rp->discovery_is_atomic(), "check this code");
4041
4042 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4043 for (uint idx = worker_id; idx < limit; idx += stride) {
4044 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4045
4046 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4047 while (iter.has_next()) {
4048 // Since discovery is not atomic for the CM ref processor, we
4049 // can see some null referent objects.
4050 iter.load_ptrs(DEBUG_ONLY(true));
4051 oop ref = iter.obj();
4052
4053 // This will filter nulls.
4054 if (iter.is_referent_alive()) {
4055 iter.make_referent_alive();
4056 }
4057 iter.move_to_next();
4058 }
4059 }
4060
4061 // Drain the queue - which may cause stealing
4062 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4063 drain_queue.do_void();
4064 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4065 assert(pss->queue_is_empty(), "should be");
4066 }
4067 };
4068
4069 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4070 // Any reference objects, in the collection set, that were 'discovered'
4071 // by the CM ref processor should have already been copied (either by
4072 // applying the external root copy closure to the discovered lists, or
4073 // by following an RSet entry).
4074 //
4075 // But some of the referents, that are in the collection set, that these
4076 // reference objects point to may not have been copied: the STW ref
4077 // processor would have seen that the reference object had already
4078 // been 'discovered' and would have skipped discovering the reference,
4079 // but would not have treated the reference object as a regular oop.
4080 // As a result the copy closure would not have been applied to the
4081 // referent object.
4082 //
4083 // We need to explicitly copy these referent objects - the references
4084 // will be processed at the end of remarking.
4085 //
4086 // We also need to do this copying before we process the reference
4087 // objects discovered by the STW ref processor in case one of these
4088 // referents points to another object which is also referenced by an
4089 // object discovered by the STW ref processor.
4090 double preserve_cm_referents_time = 0.0;
4091
4092 // To avoid spawning task when there is no work to do, check that
4093 // a concurrent cycle is active and that some references have been
4094 // discovered.
4095 if (concurrent_mark()->cm_thread()->during_cycle() &&
4096 ref_processor_cm()->has_discovered_references()) {
4097 double preserve_cm_referents_start = os::elapsedTime();
4098 uint no_of_gc_workers = workers()->active_workers();
4099 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4100 per_thread_states,
4101 no_of_gc_workers,
4102 _task_queues);
4103 workers()->run_task(&keep_cm_referents);
4104 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4105 }
4106
4107 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4108 }
4109
4110 // Weak Reference processing during an evacuation pause (part 1).
4111 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4112 double ref_proc_start = os::elapsedTime();
4113
4114 ReferenceProcessor* rp = _ref_processor_stw;
4115 assert(rp->discovery_enabled(), "should have been enabled");
4116
4117 // Closure to test whether a referent is alive.
4118 G1STWIsAliveClosure is_alive(this);
4119
4120 // Even when parallel reference processing is enabled, the processing
4121 // of JNI refs is serial and performed serially by the current thread
4122 // rather than by a worker. The following PSS will be used for processing
4123 // JNI refs.
4124
4125 // Use only a single queue for this PSS.
4126 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4127 pss->set_ref_processor(NULL);
4128 assert(pss->queue_is_empty(), "pre-condition");
4129
4130 // Keep alive closure.
4131 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4132
4133 // Serial Complete GC closure
4134 G1STWDrainQueueClosure drain_queue(this, pss);
4135
4136 // Setup the soft refs policy...
4137 rp->setup_policy(false);
4138
4139 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4140
4141 ReferenceProcessorStats stats;
4142 if (!rp->processing_is_mt()) {
4143 // Serial reference processing...
4144 stats = rp->process_discovered_references(&is_alive,
4145 &keep_alive,
4146 &drain_queue,
4147 NULL,
4148 pt);
4149 } else {
4150 uint no_of_gc_workers = workers()->active_workers();
4151
4152 // Parallel reference processing
4153 assert(no_of_gc_workers <= rp->max_num_q(),
4154 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4155 no_of_gc_workers, rp->max_num_q());
4156
4157 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4158 stats = rp->process_discovered_references(&is_alive,
4159 &keep_alive,
4160 &drain_queue,
4161 &par_task_executor,
4162 pt);
4163 }
4164
4165 _gc_tracer_stw->report_gc_reference_stats(stats);
4166
4167 // We have completed copying any necessary live referent objects.
4168 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4169
4170 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4171 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4172 }
4173
4174 // Weak Reference processing during an evacuation pause (part 2).
4175 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4176 double ref_enq_start = os::elapsedTime();
4177
4178 ReferenceProcessor* rp = _ref_processor_stw;
4179 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4180
4181 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4182
4183 // Now enqueue any remaining on the discovered lists on to
4184 // the pending list.
4185 if (!rp->processing_is_mt()) {
4186 // Serial reference processing...
4187 rp->enqueue_discovered_references(NULL, pt);
4188 } else {
4189 // Parallel reference enqueueing
4190
4191 uint n_workers = workers()->active_workers();
4192
4193 assert(n_workers <= rp->max_num_q(),
4194 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4195 n_workers, rp->max_num_q());
4196
4197 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4198 rp->enqueue_discovered_references(&par_task_executor, pt);
4199 }
4200
4201 rp->verify_no_references_recorded();
4202 assert(!rp->discovery_enabled(), "should have been disabled");
4203
4204 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4205 // ensure that it is marked in the bitmap for concurrent marking to discover.
4206 if (collector_state()->during_initial_mark_pause()) {
4207 oop pll_head = Universe::reference_pending_list();
4208 if (pll_head != NULL) {
4209 _cm->mark_in_next_bitmap(pll_head);
4210 }
4211 }
4212
4213 // FIXME
4214 // CM's reference processing also cleans up the string and symbol tables.
4215 // Should we do that here also? We could, but it is a serial operation
4216 // and could significantly increase the pause time.
4217
4218 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4219 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4220 }
4221
4222 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4223 double merge_pss_time_start = os::elapsedTime();
4224 per_thread_states->flush();
4225 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4226 }
4227
4228 void G1CollectedHeap::pre_evacuate_collection_set() {
4229 _expand_heap_after_alloc_failure = true;
4230 _evacuation_failed = false;
4231
4232 // Disable the hot card cache.
4233 _hot_card_cache->reset_hot_cache_claimed_index();
4234 _hot_card_cache->set_use_cache(false);
4235
4236 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4237 _preserved_marks_set.assert_empty();
4238
4239 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4240
4241 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4242 if (collector_state()->during_initial_mark_pause()) {
4243 double start_clear_claimed_marks = os::elapsedTime();
4244
4245 ClassLoaderDataGraph::clear_claimed_marks();
4246
4247 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4248 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4249 }
4250 }
4251
4252 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4253 // Should G1EvacuationFailureALot be in effect for this GC?
4254 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4255
4256 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4257
4258 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4259
4260 double start_par_time_sec = os::elapsedTime();
4261 double end_par_time_sec;
4262
4263 {
4264 const uint n_workers = workers()->active_workers();
4265 G1RootProcessor root_processor(this, n_workers);
4266 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4267
4268 print_termination_stats_hdr();
4269
4270 workers()->run_task(&g1_par_task);
4271 end_par_time_sec = os::elapsedTime();
4272
4273 // Closing the inner scope will execute the destructor
4274 // for the G1RootProcessor object. We record the current
4275 // elapsed time before closing the scope so that time
4276 // taken for the destructor is NOT included in the
4277 // reported parallel time.
4278 }
4279
4280 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4281 phase_times->record_par_time(par_time_ms);
4282
4283 double code_root_fixup_time_ms =
4284 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4285 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4286 }
4287
4288 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4289 // Process any discovered reference objects - we have
4290 // to do this _before_ we retire the GC alloc regions
4291 // as we may have to copy some 'reachable' referent
4292 // objects (and their reachable sub-graphs) that were
4293 // not copied during the pause.
4294 if (g1_policy()->should_process_references()) {
4295 preserve_cm_referents(per_thread_states);
4296 process_discovered_references(per_thread_states);
4297 } else {
4298 ref_processor_stw()->verify_no_references_recorded();
4299 }
4300
4301 G1STWIsAliveClosure is_alive(this);
4302 G1KeepAliveClosure keep_alive(this);
4303
4304 {
4305 double start = os::elapsedTime();
4306
4307 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4308
4309 double time_ms = (os::elapsedTime() - start) * 1000.0;
4310 g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4311 }
4312
4313 if (G1StringDedup::is_enabled()) {
4314 double fixup_start = os::elapsedTime();
4315
4316 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4317
4318 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4319 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4320 }
4321
4322 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4323
4324 if (evacuation_failed()) {
4325 restore_after_evac_failure();
4326
4327 // Reset the G1EvacuationFailureALot counters and flags
4328 // Note: the values are reset only when an actual
4329 // evacuation failure occurs.
4330 NOT_PRODUCT(reset_evacuation_should_fail();)
4331 }
4332
4333 _preserved_marks_set.assert_empty();
4334
4335 // Enqueue any remaining references remaining on the STW
4336 // reference processor's discovered lists. We need to do
4337 // this after the card table is cleaned (and verified) as
4338 // the act of enqueueing entries on to the pending list
4339 // will log these updates (and dirty their associated
4340 // cards). We need these updates logged to update any
4341 // RSets.
4342 if (g1_policy()->should_process_references()) {
4343 enqueue_discovered_references(per_thread_states);
4344 } else {
4345 g1_policy()->phase_times()->record_ref_enq_time(0);
4346 }
4347
4348 _allocator->release_gc_alloc_regions(evacuation_info);
4349
4350 merge_per_thread_state_info(per_thread_states);
4351
4352 // Reset and re-enable the hot card cache.
4353 // Note the counts for the cards in the regions in the
4354 // collection set are reset when the collection set is freed.
4355 _hot_card_cache->reset_hot_cache();
4356 _hot_card_cache->set_use_cache(true);
4357
4358 purge_code_root_memory();
4359
4360 redirty_logged_cards();
4361 #if COMPILER2_OR_JVMCI
4362 double start = os::elapsedTime();
4363 DerivedPointerTable::update_pointers();
4364 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4365 #endif
4366 g1_policy()->print_age_table();
4367 }
4368
4369 void G1CollectedHeap::record_obj_copy_mem_stats() {
4370 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4371
4372 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4373 create_g1_evac_summary(&_old_evac_stats));
4374 }
4375
4376 void G1CollectedHeap::free_region(HeapRegion* hr,
4377 FreeRegionList* free_list,
4378 bool skip_remset,
4379 bool skip_hot_card_cache,
4380 bool locked) {
4381 assert(!hr->is_free(), "the region should not be free");
4382 assert(!hr->is_empty(), "the region should not be empty");
4383 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4384 assert(free_list != NULL, "pre-condition");
4385
4386 if (G1VerifyBitmaps) {
4387 MemRegion mr(hr->bottom(), hr->end());
4388 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4389 }
4390
4391 // Clear the card counts for this region.
4392 // Note: we only need to do this if the region is not young
4393 // (since we don't refine cards in young regions).
4394 if (!skip_hot_card_cache && !hr->is_young()) {
4395 _hot_card_cache->reset_card_counts(hr);
4396 }
4397 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4398 free_list->add_ordered(hr);
4399 }
4400
4401 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4402 FreeRegionList* free_list,
4403 bool skip_remset) {
4404 assert(hr->is_humongous(), "this is only for humongous regions");
4405 assert(free_list != NULL, "pre-condition");
4406 hr->clear_humongous();
4407 free_region(hr, free_list, skip_remset);
4408 }
4409
4410 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4411 const uint humongous_regions_removed) {
4412 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4413 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4414 _old_set.bulk_remove(old_regions_removed);
4415 _humongous_set.bulk_remove(humongous_regions_removed);
4416 }
4417
4418 }
4419
4420 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4421 assert(list != NULL, "list can't be null");
4422 if (!list->is_empty()) {
4423 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4424 _hrm.insert_list_into_free_list(list);
4425 }
4426 }
4427
4428 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4429 decrease_used(bytes);
4430 }
4431
4432 class G1ParScrubRemSetTask: public AbstractGangTask {
4433 protected:
4434 G1RemSet* _g1rs;
4435 HeapRegionClaimer _hrclaimer;
4436
4437 public:
4438 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4439 AbstractGangTask("G1 ScrubRS"),
4440 _g1rs(g1_rs),
4441 _hrclaimer(num_workers) {
4442 }
4443
4444 void work(uint worker_id) {
4445 _g1rs->scrub(worker_id, &_hrclaimer);
4446 }
4447 };
4448
4449 void G1CollectedHeap::scrub_rem_set() {
4450 uint num_workers = workers()->active_workers();
4451 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4452 workers()->run_task(&g1_par_scrub_rs_task);
4453 }
4454
4455 class G1FreeCollectionSetTask : public AbstractGangTask {
4456 private:
4457
4458 // Closure applied to all regions in the collection set to do work that needs to
4459 // be done serially in a single thread.
4460 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4461 private:
4462 EvacuationInfo* _evacuation_info;
4463 const size_t* _surviving_young_words;
4464
4465 // Bytes used in successfully evacuated regions before the evacuation.
4466 size_t _before_used_bytes;
4467 // Bytes used in unsucessfully evacuated regions before the evacuation
4468 size_t _after_used_bytes;
4469
4470 size_t _bytes_allocated_in_old_since_last_gc;
4471
4472 size_t _failure_used_words;
4473 size_t _failure_waste_words;
4474
4475 FreeRegionList _local_free_list;
4476 public:
4477 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4478 HeapRegionClosure(),
4479 _evacuation_info(evacuation_info),
4480 _surviving_young_words(surviving_young_words),
4481 _before_used_bytes(0),
4482 _after_used_bytes(0),
4483 _bytes_allocated_in_old_since_last_gc(0),
4484 _failure_used_words(0),
4485 _failure_waste_words(0),
4486 _local_free_list("Local Region List for CSet Freeing") {
4487 }
4488
4489 virtual bool do_heap_region(HeapRegion* r) {
4490 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4491
4492 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4493 g1h->clear_in_cset(r);
4494
4495 if (r->is_young()) {
4496 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4497 "Young index %d is wrong for region %u of type %s with %u young regions",
4498 r->young_index_in_cset(),
4499 r->hrm_index(),
4500 r->get_type_str(),
4501 g1h->collection_set()->young_region_length());
4502 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4503 r->record_surv_words_in_group(words_survived);
4504 }
4505
4506 if (!r->evacuation_failed()) {
4507 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4508 _before_used_bytes += r->used();
4509 g1h->free_region(r,
4510 &_local_free_list,
4511 true, /* skip_remset */
4512 true, /* skip_hot_card_cache */
4513 true /* locked */);
4514 } else {
4515 r->uninstall_surv_rate_group();
4516 r->set_young_index_in_cset(-1);
4517 r->set_evacuation_failed(false);
4518 // When moving a young gen region to old gen, we "allocate" that whole region
4519 // there. This is in addition to any already evacuated objects. Notify the
4520 // policy about that.
4521 // Old gen regions do not cause an additional allocation: both the objects
4522 // still in the region and the ones already moved are accounted for elsewhere.
4523 if (r->is_young()) {
4524 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4525 }
4526 // The region is now considered to be old.
4527 r->set_old();
4528 // Do some allocation statistics accounting. Regions that failed evacuation
4529 // are always made old, so there is no need to update anything in the young
4530 // gen statistics, but we need to update old gen statistics.
4531 size_t used_words = r->marked_bytes() / HeapWordSize;
4532
4533 _failure_used_words += used_words;
4534 _failure_waste_words += HeapRegion::GrainWords - used_words;
4535
4536 g1h->old_set_add(r);
4537 _after_used_bytes += r->used();
4538 }
4539 return false;
4540 }
4541
4542 void complete_work() {
4543 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4544
4545 _evacuation_info->set_regions_freed(_local_free_list.length());
4546 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4547
4548 g1h->prepend_to_freelist(&_local_free_list);
4549 g1h->decrement_summary_bytes(_before_used_bytes);
4550
4551 G1Policy* policy = g1h->g1_policy();
4552 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4553
4554 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4555 }
4556 };
4557
4558 G1CollectionSet* _collection_set;
4559 G1SerialFreeCollectionSetClosure _cl;
4560 const size_t* _surviving_young_words;
4561
4562 size_t _rs_lengths;
4563
4564 volatile jint _serial_work_claim;
4565
4566 struct WorkItem {
4567 uint region_idx;
4568 bool is_young;
4569 bool evacuation_failed;
4570
4571 WorkItem(HeapRegion* r) {
4572 region_idx = r->hrm_index();
4573 is_young = r->is_young();
4574 evacuation_failed = r->evacuation_failed();
4575 }
4576 };
4577
4578 volatile size_t _parallel_work_claim;
4579 size_t _num_work_items;
4580 WorkItem* _work_items;
4581
4582 void do_serial_work() {
4583 // Need to grab the lock to be allowed to modify the old region list.
4584 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4585 _collection_set->iterate(&_cl);
4586 }
4587
4588 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4589 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4590
4591 HeapRegion* r = g1h->region_at(region_idx);
4592 assert(!g1h->is_on_master_free_list(r), "sanity");
4593
4594 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4595
4596 if (!is_young) {
4597 g1h->_hot_card_cache->reset_card_counts(r);
4598 }
4599
4600 if (!evacuation_failed) {
4601 r->rem_set()->clear_locked();
4602 }
4603 }
4604
4605 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4606 private:
4607 size_t _cur_idx;
4608 WorkItem* _work_items;
4609 public:
4610 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4611
4612 virtual bool do_heap_region(HeapRegion* r) {
4613 _work_items[_cur_idx++] = WorkItem(r);
4614 return false;
4615 }
4616 };
4617
4618 void prepare_work() {
4619 G1PrepareFreeCollectionSetClosure cl(_work_items);
4620 _collection_set->iterate(&cl);
4621 }
4622
4623 void complete_work() {
4624 _cl.complete_work();
4625
4626 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4627 policy->record_max_rs_lengths(_rs_lengths);
4628 policy->cset_regions_freed();
4629 }
4630 public:
4631 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4632 AbstractGangTask("G1 Free Collection Set"),
4633 _cl(evacuation_info, surviving_young_words),
4634 _collection_set(collection_set),
4635 _surviving_young_words(surviving_young_words),
4636 _serial_work_claim(0),
4637 _rs_lengths(0),
4638 _parallel_work_claim(0),
4639 _num_work_items(collection_set->region_length()),
4640 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4641 prepare_work();
4642 }
4643
4644 ~G1FreeCollectionSetTask() {
4645 complete_work();
4646 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4647 }
4648
4649 // Chunk size for work distribution. The chosen value has been determined experimentally
4650 // to be a good tradeoff between overhead and achievable parallelism.
4651 static uint chunk_size() { return 32; }
4652
4653 virtual void work(uint worker_id) {
4654 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4655
4656 // Claim serial work.
4657 if (_serial_work_claim == 0) {
4658 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4659 if (value == 0) {
4660 double serial_time = os::elapsedTime();
4661 do_serial_work();
4662 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4663 }
4664 }
4665
4666 // Start parallel work.
4667 double young_time = 0.0;
4668 bool has_young_time = false;
4669 double non_young_time = 0.0;
4670 bool has_non_young_time = false;
4671
4672 while (true) {
4673 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4674 size_t cur = end - chunk_size();
4675
4676 if (cur >= _num_work_items) {
4677 break;
4678 }
4679
4680 double start_time = os::elapsedTime();
4681
4682 end = MIN2(end, _num_work_items);
4683
4684 for (; cur < end; cur++) {
4685 bool is_young = _work_items[cur].is_young;
4686
4687 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4688
4689 double end_time = os::elapsedTime();
4690 double time_taken = end_time - start_time;
4691 if (is_young) {
4692 young_time += time_taken;
4693 has_young_time = true;
4694 } else {
4695 non_young_time += time_taken;
4696 has_non_young_time = true;
4697 }
4698 start_time = end_time;
4699 }
4700 }
4701
4702 if (has_young_time) {
4703 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4704 }
4705 if (has_non_young_time) {
4706 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4707 }
4708 }
4709 };
4710
4711 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4712 _eden.clear();
4713
4714 double free_cset_start_time = os::elapsedTime();
4715
4716 {
4717 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4718 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4719
4720 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4721
4722 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4723 cl.name(),
4724 num_workers,
4725 _collection_set.region_length());
4726 workers()->run_task(&cl, num_workers);
4727 }
4728 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4729
4730 collection_set->clear();
4731 }
4732
4733 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4734 private:
4735 FreeRegionList* _free_region_list;
4736 HeapRegionSet* _proxy_set;
4737 uint _humongous_objects_reclaimed;
4738 uint _humongous_regions_reclaimed;
4739 size_t _freed_bytes;
4740 public:
4741
4742 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4743 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4744 }
4745
4746 virtual bool do_heap_region(HeapRegion* r) {
4747 if (!r->is_starts_humongous()) {
4748 return false;
4749 }
4750
4751 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4752
4753 oop obj = (oop)r->bottom();
4754 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4755
4756 // The following checks whether the humongous object is live are sufficient.
4757 // The main additional check (in addition to having a reference from the roots
4758 // or the young gen) is whether the humongous object has a remembered set entry.
4759 //
4760 // A humongous object cannot be live if there is no remembered set for it
4761 // because:
4762 // - there can be no references from within humongous starts regions referencing
4763 // the object because we never allocate other objects into them.
4764 // (I.e. there are no intra-region references that may be missed by the
4765 // remembered set)
4766 // - as soon there is a remembered set entry to the humongous starts region
4767 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4768 // until the end of a concurrent mark.
4769 //
4770 // It is not required to check whether the object has been found dead by marking
4771 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4772 // all objects allocated during that time are considered live.
4773 // SATB marking is even more conservative than the remembered set.
4774 // So if at this point in the collection there is no remembered set entry,
4775 // nobody has a reference to it.
4776 // At the start of collection we flush all refinement logs, and remembered sets
4777 // are completely up-to-date wrt to references to the humongous object.
4778 //
4779 // Other implementation considerations:
4780 // - never consider object arrays at this time because they would pose
4781 // considerable effort for cleaning up the the remembered sets. This is
4782 // required because stale remembered sets might reference locations that
4783 // are currently allocated into.
4784 uint region_idx = r->hrm_index();
4785 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4786 !r->rem_set()->is_empty()) {
4787 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",
4788 region_idx,
4789 (size_t)obj->size() * HeapWordSize,
4790 p2i(r->bottom()),
4791 r->rem_set()->occupied(),
4792 r->rem_set()->strong_code_roots_list_length(),
4793 next_bitmap->is_marked(r->bottom()),
4794 g1h->is_humongous_reclaim_candidate(region_idx),
4795 obj->is_typeArray()
4796 );
4797 return false;
4798 }
4799
4800 guarantee(obj->is_typeArray(),
4801 "Only eagerly reclaiming type arrays is supported, but the object "
4802 PTR_FORMAT " is not.", p2i(r->bottom()));
4803
4804 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",
4805 region_idx,
4806 (size_t)obj->size() * HeapWordSize,
4807 p2i(r->bottom()),
4808 r->rem_set()->occupied(),
4809 r->rem_set()->strong_code_roots_list_length(),
4810 next_bitmap->is_marked(r->bottom()),
4811 g1h->is_humongous_reclaim_candidate(region_idx),
4812 obj->is_typeArray()
4813 );
4814
4815 // Need to clear mark bit of the humongous object if already set.
4816 if (next_bitmap->is_marked(r->bottom())) {
4817 next_bitmap->clear(r->bottom());
4818 }
4819 _humongous_objects_reclaimed++;
4820 do {
4821 HeapRegion* next = g1h->next_region_in_humongous(r);
4822 _freed_bytes += r->used();
4823 r->set_containing_set(NULL);
4824 _humongous_regions_reclaimed++;
4825 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4826 r = next;
4827 } while (r != NULL);
4828
4829 return false;
4830 }
4831
4832 uint humongous_objects_reclaimed() {
4833 return _humongous_objects_reclaimed;
4834 }
4835
4836 uint humongous_regions_reclaimed() {
4837 return _humongous_regions_reclaimed;
4838 }
4839
4840 size_t bytes_freed() const {
4841 return _freed_bytes;
4842 }
4843 };
4844
4845 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4846 assert_at_safepoint(true);
4847
4848 if (!G1EagerReclaimHumongousObjects ||
4849 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4850 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4851 return;
4852 }
4853
4854 double start_time = os::elapsedTime();
4855
4856 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4857
4858 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4859 heap_region_iterate(&cl);
4860
4861 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4862
4863 G1HRPrinter* hrp = hr_printer();
4864 if (hrp->is_active()) {
4865 FreeRegionListIterator iter(&local_cleanup_list);
4866 while (iter.more_available()) {
4867 HeapRegion* hr = iter.get_next();
4868 hrp->cleanup(hr);
4869 }
4870 }
4871
4872 prepend_to_freelist(&local_cleanup_list);
4873 decrement_summary_bytes(cl.bytes_freed());
4874
4875 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4876 cl.humongous_objects_reclaimed());
4877 }
4878
4879 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4880 public:
4881 virtual bool do_heap_region(HeapRegion* r) {
4882 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4883 G1CollectedHeap::heap()->clear_in_cset(r);
4884 r->set_young_index_in_cset(-1);
4885 return false;
4886 }
4887 };
4888
4889 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4890 G1AbandonCollectionSetClosure cl;
4891 collection_set->iterate(&cl);
4892
4893 collection_set->clear();
4894 collection_set->stop_incremental_building();
4895 }
4896
4897 void G1CollectedHeap::set_free_regions_coming() {
4898 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4899
4900 assert(!free_regions_coming(), "pre-condition");
4901 _free_regions_coming = true;
4902 }
4903
4904 void G1CollectedHeap::reset_free_regions_coming() {
4905 assert(free_regions_coming(), "pre-condition");
4906
4907 {
4908 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4909 _free_regions_coming = false;
4910 SecondaryFreeList_lock->notify_all();
4911 }
4912
4913 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4914 }
4915
4916 void G1CollectedHeap::wait_while_free_regions_coming() {
4917 // Most of the time we won't have to wait, so let's do a quick test
4918 // first before we take the lock.
4919 if (!free_regions_coming()) {
4920 return;
4921 }
4922
4923 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4924
4925 {
4926 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4927 while (free_regions_coming()) {
4928 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4929 }
4930 }
4931
4932 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4933 }
4934
4935 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4936 return _allocator->is_retained_old_region(hr);
4937 }
4938
4939 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4940 _eden.add(hr);
4941 _g1_policy->set_region_eden(hr);
4942 }
4943
4944 #ifdef ASSERT
4945
4946 class NoYoungRegionsClosure: public HeapRegionClosure {
4947 private:
4948 bool _success;
4949 public:
4950 NoYoungRegionsClosure() : _success(true) { }
4951 bool do_heap_region(HeapRegion* r) {
4952 if (r->is_young()) {
4953 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4954 p2i(r->bottom()), p2i(r->end()));
4955 _success = false;
4956 }
4957 return false;
4958 }
4959 bool success() { return _success; }
4960 };
4961
4962 bool G1CollectedHeap::check_young_list_empty() {
4963 bool ret = (young_regions_count() == 0);
4964
4965 NoYoungRegionsClosure closure;
4966 heap_region_iterate(&closure);
4967 ret = ret && closure.success();
4968
4969 return ret;
4970 }
4971
4972 #endif // ASSERT
4973
4974 class TearDownRegionSetsClosure : public HeapRegionClosure {
4975 private:
4976 HeapRegionSet *_old_set;
4977
4978 public:
4979 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4980
4981 bool do_heap_region(HeapRegion* r) {
4982 if (r->is_old()) {
4983 _old_set->remove(r);
4984 } else if(r->is_young()) {
4985 r->uninstall_surv_rate_group();
4986 } else {
4987 // We ignore free regions, we'll empty the free list afterwards.
4988 // We ignore humongous regions, we're not tearing down the
4989 // humongous regions set.
4990 assert(r->is_free() || r->is_humongous(),
4991 "it cannot be another type");
4992 }
4993 return false;
4994 }
4995
4996 ~TearDownRegionSetsClosure() {
4997 assert(_old_set->is_empty(), "post-condition");
4998 }
4999 };
5000
5001 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5002 assert_at_safepoint(true /* should_be_vm_thread */);
5003
5004 if (!free_list_only) {
5005 TearDownRegionSetsClosure cl(&_old_set);
5006 heap_region_iterate(&cl);
5007
5008 // Note that emptying the _young_list is postponed and instead done as
5009 // the first step when rebuilding the regions sets again. The reason for
5010 // this is that during a full GC string deduplication needs to know if
5011 // a collected region was young or old when the full GC was initiated.
5012 }
5013 _hrm.remove_all_free_regions();
5014 }
5015
5016 void G1CollectedHeap::increase_used(size_t bytes) {
5017 _summary_bytes_used += bytes;
5018 }
5019
5020 void G1CollectedHeap::decrease_used(size_t bytes) {
5021 assert(_summary_bytes_used >= bytes,
5022 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5023 _summary_bytes_used, bytes);
5024 _summary_bytes_used -= bytes;
5025 }
5026
5027 void G1CollectedHeap::set_used(size_t bytes) {
5028 _summary_bytes_used = bytes;
5029 }
5030
5031 class RebuildRegionSetsClosure : public HeapRegionClosure {
5032 private:
5033 bool _free_list_only;
5034 HeapRegionSet* _old_set;
5035 HeapRegionManager* _hrm;
5036 size_t _total_used;
5037
5038 public:
5039 RebuildRegionSetsClosure(bool free_list_only,
5040 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5041 _free_list_only(free_list_only),
5042 _old_set(old_set), _hrm(hrm), _total_used(0) {
5043 assert(_hrm->num_free_regions() == 0, "pre-condition");
5044 if (!free_list_only) {
5045 assert(_old_set->is_empty(), "pre-condition");
5046 }
5047 }
5048
5049 bool do_heap_region(HeapRegion* r) {
5050 if (r->is_empty()) {
5051 // Add free regions to the free list
5052 r->set_free();
5053 _hrm->insert_into_free_list(r);
5054 } else if (!_free_list_only) {
5055
5056 if (r->is_humongous()) {
5057 // We ignore humongous regions. We left the humongous set unchanged.
5058 } else {
5059 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5060 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5061 r->move_to_old();
5062 _old_set->add(r);
5063 }
5064 _total_used += r->used();
5065 }
5066
5067 return false;
5068 }
5069
5070 size_t total_used() {
5071 return _total_used;
5072 }
5073 };
5074
5075 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5076 assert_at_safepoint(true /* should_be_vm_thread */);
5077
5078 if (!free_list_only) {
5079 _eden.clear();
5080 _survivor.clear();
5081 }
5082
5083 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5084 heap_region_iterate(&cl);
5085
5086 if (!free_list_only) {
5087 set_used(cl.total_used());
5088 if (_archive_allocator != NULL) {
5089 _archive_allocator->clear_used();
5090 }
5091 }
5092 assert(used_unlocked() == recalculate_used(),
5093 "inconsistent used_unlocked(), "
5094 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5095 used_unlocked(), recalculate_used());
5096 }
5097
5098 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5099 HeapRegion* hr = heap_region_containing(p);
5100 return hr->is_in(p);
5101 }
5102
5103 // Methods for the mutator alloc region
5104
5105 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5106 bool force) {
5107 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5108 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5109 if (force || should_allocate) {
5110 HeapRegion* new_alloc_region = new_region(word_size,
5111 false /* is_old */,
5112 false /* do_expand */);
5113 if (new_alloc_region != NULL) {
5114 set_region_short_lived_locked(new_alloc_region);
5115 _hr_printer.alloc(new_alloc_region, !should_allocate);
5116 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5117 return new_alloc_region;
5118 }
5119 }
5120 return NULL;
5121 }
5122
5123 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5124 size_t allocated_bytes) {
5125 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5126 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5127
5128 collection_set()->add_eden_region(alloc_region);
5129 increase_used(allocated_bytes);
5130 _hr_printer.retire(alloc_region);
5131 // We update the eden sizes here, when the region is retired,
5132 // instead of when it's allocated, since this is the point that its
5133 // used space has been recored in _summary_bytes_used.
5134 g1mm()->update_eden_size();
5135 }
5136
5137 // Methods for the GC alloc regions
5138
5139 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5140 if (dest.is_old()) {
5141 return true;
5142 } else {
5143 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5144 }
5145 }
5146
5147 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5148 assert(FreeList_lock->owned_by_self(), "pre-condition");
5149
5150 if (!has_more_regions(dest)) {
5151 return NULL;
5152 }
5153
5154 const bool is_survivor = dest.is_young();
5155
5156 HeapRegion* new_alloc_region = new_region(word_size,
5157 !is_survivor,
5158 true /* do_expand */);
5159 if (new_alloc_region != NULL) {
5160 // We really only need to do this for old regions given that we
5161 // should never scan survivors. But it doesn't hurt to do it
5162 // for survivors too.
5163 new_alloc_region->record_timestamp();
5164 if (is_survivor) {
5165 new_alloc_region->set_survivor();
5166 _survivor.add(new_alloc_region);
5167 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5168 } else {
5169 new_alloc_region->set_old();
5170 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5171 }
5172 _hr_printer.alloc(new_alloc_region);
5173 bool during_im = collector_state()->during_initial_mark_pause();
5174 new_alloc_region->note_start_of_copying(during_im);
5175 return new_alloc_region;
5176 }
5177 return NULL;
5178 }
5179
5180 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5181 size_t allocated_bytes,
5182 InCSetState dest) {
5183 bool during_im = collector_state()->during_initial_mark_pause();
5184 alloc_region->note_end_of_copying(during_im);
5185 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5186 if (dest.is_old()) {
5187 _old_set.add(alloc_region);
5188 }
5189 _hr_printer.retire(alloc_region);
5190 }
5191
5192 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5193 bool expanded = false;
5194 uint index = _hrm.find_highest_free(&expanded);
5195
5196 if (index != G1_NO_HRM_INDEX) {
5197 if (expanded) {
5198 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5199 HeapRegion::GrainWords * HeapWordSize);
5200 }
5201 _hrm.allocate_free_regions_starting_at(index, 1);
5202 return region_at(index);
5203 }
5204 return NULL;
5205 }
5206
5207 // Optimized nmethod scanning
5208
5209 class RegisterNMethodOopClosure: public OopClosure {
5210 G1CollectedHeap* _g1h;
5211 nmethod* _nm;
5212
5213 template <class T> void do_oop_work(T* p) {
5214 T heap_oop = oopDesc::load_heap_oop(p);
5215 if (!oopDesc::is_null(heap_oop)) {
5216 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5217 HeapRegion* hr = _g1h->heap_region_containing(obj);
5218 assert(!hr->is_continues_humongous(),
5219 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5220 " starting at " HR_FORMAT,
5221 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5222
5223 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5224 hr->add_strong_code_root_locked(_nm);
5225 }
5226 }
5227
5228 public:
5229 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5230 _g1h(g1h), _nm(nm) {}
5231
5232 void do_oop(oop* p) { do_oop_work(p); }
5233 void do_oop(narrowOop* p) { do_oop_work(p); }
5234 };
5235
5236 class UnregisterNMethodOopClosure: public OopClosure {
5237 G1CollectedHeap* _g1h;
5238 nmethod* _nm;
5239
5240 template <class T> void do_oop_work(T* p) {
5241 T heap_oop = oopDesc::load_heap_oop(p);
5242 if (!oopDesc::is_null(heap_oop)) {
5243 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5244 HeapRegion* hr = _g1h->heap_region_containing(obj);
5245 assert(!hr->is_continues_humongous(),
5246 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5247 " starting at " HR_FORMAT,
5248 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5249
5250 hr->remove_strong_code_root(_nm);
5251 }
5252 }
5253
5254 public:
5255 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5256 _g1h(g1h), _nm(nm) {}
5257
5258 void do_oop(oop* p) { do_oop_work(p); }
5259 void do_oop(narrowOop* p) { do_oop_work(p); }
5260 };
5261
5262 // Returns true if the reference points to an object that
5263 // can move in an incremental collection.
5264 bool G1CollectedHeap::is_scavengable(oop obj) {
5265 HeapRegion* hr = heap_region_containing(obj);
5266 return !hr->is_pinned();
5267 }
5268
5269 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5270 guarantee(nm != NULL, "sanity");
5271 RegisterNMethodOopClosure reg_cl(this, nm);
5272 nm->oops_do(®_cl);
5273 }
5274
5275 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5276 guarantee(nm != NULL, "sanity");
5277 UnregisterNMethodOopClosure reg_cl(this, nm);
5278 nm->oops_do(®_cl, true);
5279 }
5280
5281 void G1CollectedHeap::purge_code_root_memory() {
5282 double purge_start = os::elapsedTime();
5283 G1CodeRootSet::purge();
5284 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5285 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5286 }
5287
5288 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5289 G1CollectedHeap* _g1h;
5290
5291 public:
5292 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5293 _g1h(g1h) {}
5294
5295 void do_code_blob(CodeBlob* cb) {
5296 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5297 if (nm == NULL) {
5298 return;
5299 }
5300
5301 if (ScavengeRootsInCode) {
5302 _g1h->register_nmethod(nm);
5303 }
5304 }
5305 };
5306
5307 void G1CollectedHeap::rebuild_strong_code_roots() {
5308 RebuildStrongCodeRootClosure blob_cl(this);
5309 CodeCache::blobs_do(&blob_cl);
5310 }
5311
5312 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5313 GrowableArray<GCMemoryManager*> memory_managers(2);
5314 memory_managers.append(&_memory_manager);
5315 memory_managers.append(&_full_gc_memory_manager);
5316 return memory_managers;
5317 }
5318
5319 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5320 GrowableArray<MemoryPool*> memory_pools(3);
5321 memory_pools.append(_eden_pool);
5322 memory_pools.append(_survivor_pool);
5323 memory_pools.append(_old_pool);
5324 return memory_pools;
5325 }