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/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1BarrierSet.hpp"
33 #include "gc/g1/g1CollectedHeap.inline.hpp"
34 #include "gc/g1/g1CollectionSet.hpp"
35 #include "gc/g1/g1CollectorPolicy.hpp"
36 #include "gc/g1/g1CollectorState.hpp"
37 #include "gc/g1/g1ConcurrentRefine.hpp"
38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1MemoryPool.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1SATBMarkQueueSet.hpp"
56 #include "gc/g1/g1StringDedup.hpp"
57 #include "gc/g1/g1ThreadLocalData.hpp"
58 #include "gc/g1/g1YCTypes.hpp"
59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
60 #include "gc/g1/heapRegion.inline.hpp"
61 #include "gc/g1/heapRegionRemSet.hpp"
62 #include "gc/g1/heapRegionSet.inline.hpp"
63 #include "gc/g1/vm_operations_g1.hpp"
64 #include "gc/shared/adaptiveSizePolicy.hpp"
65 #include "gc/shared/gcHeapSummary.hpp"
66 #include "gc/shared/gcId.hpp"
67 #include "gc/shared/gcLocker.hpp"
68 #include "gc/shared/gcTimer.hpp"
69 #include "gc/shared/gcTrace.hpp"
70 #include "gc/shared/gcTraceTime.inline.hpp"
71 #include "gc/shared/generationSpec.hpp"
72 #include "gc/shared/isGCActiveMark.hpp"
73 #include "gc/shared/oopStorageParState.hpp"
74 #include "gc/shared/parallelCleaning.hpp"
75 #include "gc/shared/preservedMarks.inline.hpp"
76 #include "gc/shared/suspendibleThreadSet.hpp"
77 #include "gc/shared/referenceProcessor.inline.hpp"
78 #include "gc/shared/taskqueue.inline.hpp"
79 #include "gc/shared/weakProcessor.inline.hpp"
80 #include "logging/log.hpp"
81 #include "memory/allocation.hpp"
82 #include "memory/iterator.hpp"
83 #include "memory/resourceArea.hpp"
84 #include "oops/access.inline.hpp"
85 #include "oops/compressedOops.inline.hpp"
86 #include "oops/oop.inline.hpp"
87 #include "runtime/atomic.hpp"
88 #include "runtime/flags/flagSetting.hpp"
89 #include "runtime/handles.inline.hpp"
90 #include "runtime/init.hpp"
91 #include "runtime/orderAccess.hpp"
92 #include "runtime/threadSMR.hpp"
93 #include "runtime/vmThread.hpp"
94 #include "utilities/align.hpp"
95 #include "utilities/globalDefinitions.hpp"
96 #include "utilities/stack.inline.hpp"
97
98 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
99
100 // INVARIANTS/NOTES
101 //
102 // All allocation activity covered by the G1CollectedHeap interface is
103 // serialized by acquiring the HeapLock. This happens in mem_allocate
104 // and allocate_new_tlab, which are the "entry" points to the
105 // allocation code from the rest of the JVM. (Note that this does not
106 // apply to TLAB allocation, which is not part of this interface: it
107 // is done by clients of this interface.)
108
109 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
110 private:
111 size_t _num_dirtied;
112 G1CollectedHeap* _g1h;
113 G1CardTable* _g1_ct;
114
115 HeapRegion* region_for_card(jbyte* card_ptr) const {
116 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
117 }
118
119 bool will_become_free(HeapRegion* hr) const {
120 // A region will be freed by free_collection_set if the region is in the
121 // collection set and has not had an evacuation failure.
122 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
123 }
124
125 public:
126 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
127 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
128
129 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
130 HeapRegion* hr = region_for_card(card_ptr);
131
132 // Should only dirty cards in regions that won't be freed.
133 if (!will_become_free(hr)) {
134 *card_ptr = G1CardTable::dirty_card_val();
135 _num_dirtied++;
136 }
137
138 return true;
139 }
140
141 size_t num_dirtied() const { return _num_dirtied; }
142 };
143
144
145 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
146 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
147 }
148
149 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
150 // The from card cache is not the memory that is actually committed. So we cannot
151 // take advantage of the zero_filled parameter.
152 reset_from_card_cache(start_idx, num_regions);
153 }
154
155
156 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
157 MemRegion mr) {
158 return new HeapRegion(hrs_index, bot(), mr);
159 }
160
161 // Private methods.
162
163 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
164 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
165 "the only time we use this to allocate a humongous region is "
166 "when we are allocating a single humongous region");
167
168 HeapRegion* res = _hrm.allocate_free_region(is_old);
169
170 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
171 // Currently, only attempts to allocate GC alloc regions set
172 // do_expand to true. So, we should only reach here during a
173 // safepoint. If this assumption changes we might have to
174 // reconsider the use of _expand_heap_after_alloc_failure.
175 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
176
177 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
178 word_size * HeapWordSize);
179
180 if (expand(word_size * HeapWordSize)) {
181 // Given that expand() succeeded in expanding the heap, and we
182 // always expand the heap by an amount aligned to the heap
183 // region size, the free list should in theory not be empty.
184 // In either case allocate_free_region() will check for NULL.
185 res = _hrm.allocate_free_region(is_old);
186 } else {
187 _expand_heap_after_alloc_failure = false;
188 }
189 }
190 return res;
191 }
192
193 HeapWord*
194 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
195 uint num_regions,
196 size_t word_size) {
197 assert(first != G1_NO_HRM_INDEX, "pre-condition");
198 assert(is_humongous(word_size), "word_size should be humongous");
199 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
200
201 // Index of last region in the series.
202 uint last = first + num_regions - 1;
203
204 // We need to initialize the region(s) we just discovered. This is
205 // a bit tricky given that it can happen concurrently with
206 // refinement threads refining cards on these regions and
207 // potentially wanting to refine the BOT as they are scanning
208 // those cards (this can happen shortly after a cleanup; see CR
209 // 6991377). So we have to set up the region(s) carefully and in
210 // a specific order.
211
212 // The word size sum of all the regions we will allocate.
213 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
214 assert(word_size <= word_size_sum, "sanity");
215
216 // This will be the "starts humongous" region.
217 HeapRegion* first_hr = region_at(first);
218 // The header of the new object will be placed at the bottom of
219 // the first region.
220 HeapWord* new_obj = first_hr->bottom();
221 // This will be the new top of the new object.
222 HeapWord* obj_top = new_obj + word_size;
223
224 // First, we need to zero the header of the space that we will be
225 // allocating. When we update top further down, some refinement
226 // threads might try to scan the region. By zeroing the header we
227 // ensure that any thread that will try to scan the region will
228 // come across the zero klass word and bail out.
229 //
230 // NOTE: It would not have been correct to have used
231 // CollectedHeap::fill_with_object() and make the space look like
232 // an int array. The thread that is doing the allocation will
233 // later update the object header to a potentially different array
234 // type and, for a very short period of time, the klass and length
235 // fields will be inconsistent. This could cause a refinement
236 // thread to calculate the object size incorrectly.
237 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
238
239 // Next, pad out the unused tail of the last region with filler
240 // objects, for improved usage accounting.
241 // How many words we use for filler objects.
242 size_t word_fill_size = word_size_sum - word_size;
243
244 // How many words memory we "waste" which cannot hold a filler object.
245 size_t words_not_fillable = 0;
246
247 if (word_fill_size >= min_fill_size()) {
248 fill_with_objects(obj_top, word_fill_size);
249 } else if (word_fill_size > 0) {
250 // We have space to fill, but we cannot fit an object there.
251 words_not_fillable = word_fill_size;
252 word_fill_size = 0;
253 }
254
255 // We will set up the first region as "starts humongous". This
256 // will also update the BOT covering all the regions to reflect
257 // that there is a single object that starts at the bottom of the
258 // first region.
259 first_hr->set_starts_humongous(obj_top, word_fill_size);
260 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
261 // Then, if there are any, we will set up the "continues
262 // humongous" regions.
263 HeapRegion* hr = NULL;
264 for (uint i = first + 1; i <= last; ++i) {
265 hr = region_at(i);
266 hr->set_continues_humongous(first_hr);
267 _g1_policy->remset_tracker()->update_at_allocate(hr);
268 }
269
270 // Up to this point no concurrent thread would have been able to
271 // do any scanning on any region in this series. All the top
272 // fields still point to bottom, so the intersection between
273 // [bottom,top] and [card_start,card_end] will be empty. Before we
274 // update the top fields, we'll do a storestore to make sure that
275 // no thread sees the update to top before the zeroing of the
276 // object header and the BOT initialization.
277 OrderAccess::storestore();
278
279 // Now, we will update the top fields of the "continues humongous"
280 // regions except the last one.
281 for (uint i = first; i < last; ++i) {
282 hr = region_at(i);
283 hr->set_top(hr->end());
284 }
285
286 hr = region_at(last);
287 // If we cannot fit a filler object, we must set top to the end
288 // of the humongous object, otherwise we cannot iterate the heap
289 // and the BOT will not be complete.
290 hr->set_top(hr->end() - words_not_fillable);
291
292 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
293 "obj_top should be in last region");
294
295 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
296
297 assert(words_not_fillable == 0 ||
298 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
299 "Miscalculation in humongous allocation");
300
301 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
302
303 for (uint i = first; i <= last; ++i) {
304 hr = region_at(i);
305 _humongous_set.add(hr);
306 _hr_printer.alloc(hr);
307 }
308
309 return new_obj;
310 }
311
312 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
313 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
314 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
315 }
316
317 // If could fit into free regions w/o expansion, try.
318 // Otherwise, if can expand, do so.
319 // Otherwise, if using ex regions might help, try with ex given back.
320 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
321 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
322
323 _verifier->verify_region_sets_optional();
324
325 uint first = G1_NO_HRM_INDEX;
326 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
327
328 if (obj_regions == 1) {
329 // Only one region to allocate, try to use a fast path by directly allocating
330 // from the free lists. Do not try to expand here, we will potentially do that
331 // later.
332 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
333 if (hr != NULL) {
334 first = hr->hrm_index();
335 }
336 } else {
337 // Policy: Try only empty regions (i.e. already committed first). Maybe we
338 // are lucky enough to find some.
339 first = _hrm.find_contiguous_only_empty(obj_regions);
340 if (first != G1_NO_HRM_INDEX) {
341 _hrm.allocate_free_regions_starting_at(first, obj_regions);
342 }
343 }
344
345 if (first == G1_NO_HRM_INDEX) {
346 // Policy: We could not find enough regions for the humongous object in the
347 // free list. Look through the heap to find a mix of free and uncommitted regions.
348 // If so, try expansion.
349 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
350 if (first != G1_NO_HRM_INDEX) {
351 // We found something. Make sure these regions are committed, i.e. expand
352 // the heap. Alternatively we could do a defragmentation GC.
353 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
354 word_size * HeapWordSize);
355
356 _hrm.expand_at(first, obj_regions, workers());
357 g1_policy()->record_new_heap_size(num_regions());
358
359 #ifdef ASSERT
360 for (uint i = first; i < first + obj_regions; ++i) {
361 HeapRegion* hr = region_at(i);
362 assert(hr->is_free(), "sanity");
363 assert(hr->is_empty(), "sanity");
364 assert(is_on_master_free_list(hr), "sanity");
365 }
366 #endif
367 _hrm.allocate_free_regions_starting_at(first, obj_regions);
368 } else {
369 // Policy: Potentially trigger a defragmentation GC.
370 }
371 }
372
373 HeapWord* result = NULL;
374 if (first != G1_NO_HRM_INDEX) {
375 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
376 assert(result != NULL, "it should always return a valid result");
377
378 // A successful humongous object allocation changes the used space
379 // information of the old generation so we need to recalculate the
380 // sizes and update the jstat counters here.
381 g1mm()->update_sizes();
382 }
383
384 _verifier->verify_region_sets_optional();
385
386 return result;
387 }
388
389 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
390 size_t requested_size,
391 size_t* actual_size) {
392 assert_heap_not_locked_and_not_at_safepoint();
393 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
394
395 return attempt_allocation(min_size, requested_size, actual_size);
396 }
397
398 HeapWord*
399 G1CollectedHeap::mem_allocate(size_t word_size,
400 bool* gc_overhead_limit_was_exceeded) {
401 assert_heap_not_locked_and_not_at_safepoint();
402
403 if (is_humongous(word_size)) {
404 return attempt_allocation_humongous(word_size);
405 }
406 size_t dummy = 0;
407 return attempt_allocation(word_size, word_size, &dummy);
408 }
409
410 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
411 ResourceMark rm; // For retrieving the thread names in log messages.
412
413 // Make sure you read the note in attempt_allocation_humongous().
414
415 assert_heap_not_locked_and_not_at_safepoint();
416 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
417 "be called for humongous allocation requests");
418
419 // We should only get here after the first-level allocation attempt
420 // (attempt_allocation()) failed to allocate.
421
422 // We will loop until a) we manage to successfully perform the
423 // allocation or b) we successfully schedule a collection which
424 // fails to perform the allocation. b) is the only case when we'll
425 // return NULL.
426 HeapWord* result = NULL;
427 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
428 bool should_try_gc;
429 uint gc_count_before;
430
431 {
432 MutexLockerEx x(Heap_lock);
433 result = _allocator->attempt_allocation_locked(word_size);
434 if (result != NULL) {
435 return result;
436 }
437
438 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
439 // This is different to when only GCLocker::needs_gc() is set: try to avoid
440 // waiting because the GCLocker is active to not wait too long.
441 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
442 // No need for an ergo message here, can_expand_young_list() does this when
443 // it returns true.
444 result = _allocator->attempt_allocation_force(word_size);
445 if (result != NULL) {
446 return result;
447 }
448 }
449 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
450 // the GCLocker initiated GC has been performed and then retry. This includes
451 // the case when the GC Locker is not active but has not been performed.
452 should_try_gc = !GCLocker::needs_gc();
453 // Read the GC count while still holding the Heap_lock.
454 gc_count_before = total_collections();
455 }
456
457 if (should_try_gc) {
458 bool succeeded;
459 result = do_collection_pause(word_size, gc_count_before, &succeeded,
460 GCCause::_g1_inc_collection_pause);
461 if (result != NULL) {
462 assert(succeeded, "only way to get back a non-NULL result");
463 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
464 Thread::current()->name(), p2i(result));
465 return result;
466 }
467
468 if (succeeded) {
469 // We successfully scheduled a collection which failed to allocate. No
470 // point in trying to allocate further. We'll just return NULL.
471 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
472 SIZE_FORMAT " words", Thread::current()->name(), word_size);
473 return NULL;
474 }
475 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
476 Thread::current()->name(), word_size);
477 } else {
478 // Failed to schedule a collection.
479 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
480 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
481 SIZE_FORMAT " words", Thread::current()->name(), word_size);
482 return NULL;
483 }
484 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
485 // The GCLocker is either active or the GCLocker initiated
486 // GC has not yet been performed. Stall until it is and
487 // then retry the allocation.
488 GCLocker::stall_until_clear();
489 gclocker_retry_count += 1;
490 }
491
492 // We can reach here if we were unsuccessful in scheduling a
493 // collection (because another thread beat us to it) or if we were
494 // stalled due to the GC locker. In either can we should retry the
495 // allocation attempt in case another thread successfully
496 // performed a collection and reclaimed enough space. We do the
497 // first attempt (without holding the Heap_lock) here and the
498 // follow-on attempt will be at the start of the next loop
499 // iteration (after taking the Heap_lock).
500 size_t dummy = 0;
501 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
502 if (result != NULL) {
503 return result;
504 }
505
506 // Give a warning if we seem to be looping forever.
507 if ((QueuedAllocationWarningCount > 0) &&
508 (try_count % QueuedAllocationWarningCount == 0)) {
509 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
510 Thread::current()->name(), try_count, word_size);
511 }
512 }
513
514 ShouldNotReachHere();
515 return NULL;
516 }
517
518 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
519 assert_at_safepoint_on_vm_thread();
520 if (_archive_allocator == NULL) {
521 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
522 }
523 }
524
525 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
526 // Allocations in archive regions cannot be of a size that would be considered
527 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
528 // may be different at archive-restore time.
529 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
530 }
531
532 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
533 assert_at_safepoint_on_vm_thread();
534 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
535 if (is_archive_alloc_too_large(word_size)) {
536 return NULL;
537 }
538 return _archive_allocator->archive_mem_allocate(word_size);
539 }
540
541 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
542 size_t end_alignment_in_bytes) {
543 assert_at_safepoint_on_vm_thread();
544 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
545
546 // Call complete_archive to do the real work, filling in the MemRegion
547 // array with the archive regions.
548 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
549 delete _archive_allocator;
550 _archive_allocator = NULL;
551 }
552
553 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
554 assert(ranges != NULL, "MemRegion array NULL");
555 assert(count != 0, "No MemRegions provided");
556 MemRegion reserved = _hrm.reserved();
557 for (size_t i = 0; i < count; i++) {
558 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
559 return false;
560 }
561 }
562 return true;
563 }
564
565 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
566 size_t count,
567 bool open) {
568 assert(!is_init_completed(), "Expect to be called at JVM init time");
569 assert(ranges != NULL, "MemRegion array NULL");
570 assert(count != 0, "No MemRegions provided");
571 MutexLockerEx x(Heap_lock);
572
573 MemRegion reserved = _hrm.reserved();
574 HeapWord* prev_last_addr = NULL;
575 HeapRegion* prev_last_region = NULL;
576
577 // Temporarily disable pretouching of heap pages. This interface is used
578 // when mmap'ing archived heap data in, so pre-touching is wasted.
579 FlagSetting fs(AlwaysPreTouch, false);
580
581 // Enable archive object checking used by G1MarkSweep. We have to let it know
582 // about each archive range, so that objects in those ranges aren't marked.
583 G1ArchiveAllocator::enable_archive_object_check();
584
585 // For each specified MemRegion range, allocate the corresponding G1
586 // regions and mark them as archive regions. We expect the ranges
587 // in ascending starting address order, without overlap.
588 for (size_t i = 0; i < count; i++) {
589 MemRegion curr_range = ranges[i];
590 HeapWord* start_address = curr_range.start();
591 size_t word_size = curr_range.word_size();
592 HeapWord* last_address = curr_range.last();
593 size_t commits = 0;
594
595 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
596 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
597 p2i(start_address), p2i(last_address));
598 guarantee(start_address > prev_last_addr,
599 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
600 p2i(start_address), p2i(prev_last_addr));
601 prev_last_addr = last_address;
602
603 // Check for ranges that start in the same G1 region in which the previous
604 // range ended, and adjust the start address so we don't try to allocate
605 // the same region again. If the current range is entirely within that
606 // region, skip it, just adjusting the recorded top.
607 HeapRegion* start_region = _hrm.addr_to_region(start_address);
608 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
609 start_address = start_region->end();
610 if (start_address > last_address) {
611 increase_used(word_size * HeapWordSize);
612 start_region->set_top(last_address + 1);
613 continue;
614 }
615 start_region->set_top(start_address);
616 curr_range = MemRegion(start_address, last_address + 1);
617 start_region = _hrm.addr_to_region(start_address);
618 }
619
620 // Perform the actual region allocation, exiting if it fails.
621 // Then note how much new space we have allocated.
622 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
623 return false;
624 }
625 increase_used(word_size * HeapWordSize);
626 if (commits != 0) {
627 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
628 HeapRegion::GrainWords * HeapWordSize * commits);
629
630 }
631
632 // Mark each G1 region touched by the range as archive, add it to
633 // the old set, and set top.
634 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
635 HeapRegion* last_region = _hrm.addr_to_region(last_address);
636 prev_last_region = last_region;
637
638 while (curr_region != NULL) {
639 assert(curr_region->is_empty() && !curr_region->is_pinned(),
640 "Region already in use (index %u)", curr_region->hrm_index());
641 if (open) {
642 curr_region->set_open_archive();
643 } else {
644 curr_region->set_closed_archive();
645 }
646 _hr_printer.alloc(curr_region);
647 _archive_set.add(curr_region);
648 HeapWord* top;
649 HeapRegion* next_region;
650 if (curr_region != last_region) {
651 top = curr_region->end();
652 next_region = _hrm.next_region_in_heap(curr_region);
653 } else {
654 top = last_address + 1;
655 next_region = NULL;
656 }
657 curr_region->set_top(top);
658 curr_region->set_first_dead(top);
659 curr_region->set_end_of_live(top);
660 curr_region = next_region;
661 }
662
663 // Notify mark-sweep of the archive
664 G1ArchiveAllocator::set_range_archive(curr_range, open);
665 }
666 return true;
667 }
668
669 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
670 assert(!is_init_completed(), "Expect to be called at JVM init time");
671 assert(ranges != NULL, "MemRegion array NULL");
672 assert(count != 0, "No MemRegions provided");
673 MemRegion reserved = _hrm.reserved();
674 HeapWord *prev_last_addr = NULL;
675 HeapRegion* prev_last_region = NULL;
676
677 // For each MemRegion, create filler objects, if needed, in the G1 regions
678 // that contain the address range. The address range actually within the
679 // MemRegion will not be modified. That is assumed to have been initialized
680 // elsewhere, probably via an mmap of archived heap data.
681 MutexLockerEx x(Heap_lock);
682 for (size_t i = 0; i < count; i++) {
683 HeapWord* start_address = ranges[i].start();
684 HeapWord* last_address = ranges[i].last();
685
686 assert(reserved.contains(start_address) && reserved.contains(last_address),
687 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
688 p2i(start_address), p2i(last_address));
689 assert(start_address > prev_last_addr,
690 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
691 p2i(start_address), p2i(prev_last_addr));
692
693 HeapRegion* start_region = _hrm.addr_to_region(start_address);
694 HeapRegion* last_region = _hrm.addr_to_region(last_address);
695 HeapWord* bottom_address = start_region->bottom();
696
697 // Check for a range beginning in the same region in which the
698 // previous one ended.
699 if (start_region == prev_last_region) {
700 bottom_address = prev_last_addr + 1;
701 }
702
703 // Verify that the regions were all marked as archive regions by
704 // alloc_archive_regions.
705 HeapRegion* curr_region = start_region;
706 while (curr_region != NULL) {
707 guarantee(curr_region->is_archive(),
708 "Expected archive region at index %u", curr_region->hrm_index());
709 if (curr_region != last_region) {
710 curr_region = _hrm.next_region_in_heap(curr_region);
711 } else {
712 curr_region = NULL;
713 }
714 }
715
716 prev_last_addr = last_address;
717 prev_last_region = last_region;
718
719 // Fill the memory below the allocated range with dummy object(s),
720 // if the region bottom does not match the range start, or if the previous
721 // range ended within the same G1 region, and there is a gap.
722 if (start_address != bottom_address) {
723 size_t fill_size = pointer_delta(start_address, bottom_address);
724 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
725 increase_used(fill_size * HeapWordSize);
726 }
727 }
728 }
729
730 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
731 size_t desired_word_size,
732 size_t* actual_word_size) {
733 assert_heap_not_locked_and_not_at_safepoint();
734 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
735 "be called for humongous allocation requests");
736
737 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
738
739 if (result == NULL) {
740 *actual_word_size = desired_word_size;
741 result = attempt_allocation_slow(desired_word_size);
742 }
743
744 assert_heap_not_locked();
745 if (result != NULL) {
746 assert(*actual_word_size != 0, "Actual size must have been set here");
747 dirty_young_block(result, *actual_word_size);
748 } else {
749 *actual_word_size = 0;
750 }
751
752 return result;
753 }
754
755 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
756 assert(!is_init_completed(), "Expect to be called at JVM init time");
757 assert(ranges != NULL, "MemRegion array NULL");
758 assert(count != 0, "No MemRegions provided");
759 MemRegion reserved = _hrm.reserved();
760 HeapWord* prev_last_addr = NULL;
761 HeapRegion* prev_last_region = NULL;
762 size_t size_used = 0;
763 size_t uncommitted_regions = 0;
764
765 // For each Memregion, free the G1 regions that constitute it, and
766 // notify mark-sweep that the range is no longer to be considered 'archive.'
767 MutexLockerEx x(Heap_lock);
768 for (size_t i = 0; i < count; i++) {
769 HeapWord* start_address = ranges[i].start();
770 HeapWord* last_address = ranges[i].last();
771
772 assert(reserved.contains(start_address) && reserved.contains(last_address),
773 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
774 p2i(start_address), p2i(last_address));
775 assert(start_address > prev_last_addr,
776 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
777 p2i(start_address), p2i(prev_last_addr));
778 size_used += ranges[i].byte_size();
779 prev_last_addr = last_address;
780
781 HeapRegion* start_region = _hrm.addr_to_region(start_address);
782 HeapRegion* last_region = _hrm.addr_to_region(last_address);
783
784 // Check for ranges that start in the same G1 region in which the previous
785 // range ended, and adjust the start address so we don't try to free
786 // the same region again. If the current range is entirely within that
787 // region, skip it.
788 if (start_region == prev_last_region) {
789 start_address = start_region->end();
790 if (start_address > last_address) {
791 continue;
792 }
793 start_region = _hrm.addr_to_region(start_address);
794 }
795 prev_last_region = last_region;
796
797 // After verifying that each region was marked as an archive region by
798 // alloc_archive_regions, set it free and empty and uncommit it.
799 HeapRegion* curr_region = start_region;
800 while (curr_region != NULL) {
801 guarantee(curr_region->is_archive(),
802 "Expected archive region at index %u", curr_region->hrm_index());
803 uint curr_index = curr_region->hrm_index();
804 _archive_set.remove(curr_region);
805 curr_region->set_free();
806 curr_region->set_top(curr_region->bottom());
807 if (curr_region != last_region) {
808 curr_region = _hrm.next_region_in_heap(curr_region);
809 } else {
810 curr_region = NULL;
811 }
812 _hrm.shrink_at(curr_index, 1);
813 uncommitted_regions++;
814 }
815
816 // Notify mark-sweep that this is no longer an archive range.
817 G1ArchiveAllocator::set_range_archive(ranges[i], false);
818 }
819
820 if (uncommitted_regions != 0) {
821 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
822 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
823 }
824 decrease_used(size_used);
825 }
826
827 oop G1CollectedHeap::materialize_archived_object(oop obj) {
828 assert(obj != NULL, "archived obj is NULL");
829 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
830
831 // Loading an archived object makes it strongly reachable. If it is
832 // loaded during concurrent marking, it must be enqueued to the SATB
833 // queue, shading the previously white object gray.
834 G1BarrierSet::enqueue(obj);
835
836 return obj;
837 }
838
839 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
840 ResourceMark rm; // For retrieving the thread names in log messages.
841
842 // The structure of this method has a lot of similarities to
843 // attempt_allocation_slow(). The reason these two were not merged
844 // into a single one is that such a method would require several "if
845 // allocation is not humongous do this, otherwise do that"
846 // conditional paths which would obscure its flow. In fact, an early
847 // version of this code did use a unified method which was harder to
848 // follow and, as a result, it had subtle bugs that were hard to
849 // track down. So keeping these two methods separate allows each to
850 // be more readable. It will be good to keep these two in sync as
851 // much as possible.
852
853 assert_heap_not_locked_and_not_at_safepoint();
854 assert(is_humongous(word_size), "attempt_allocation_humongous() "
855 "should only be called for humongous allocations");
856
857 // Humongous objects can exhaust the heap quickly, so we should check if we
858 // need to start a marking cycle at each humongous object allocation. We do
859 // the check before we do the actual allocation. The reason for doing it
860 // before the allocation is that we avoid having to keep track of the newly
861 // allocated memory while we do a GC.
862 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
863 word_size)) {
864 collect(GCCause::_g1_humongous_allocation);
865 }
866
867 // We will loop until a) we manage to successfully perform the
868 // allocation or b) we successfully schedule a collection which
869 // fails to perform the allocation. b) is the only case when we'll
870 // return NULL.
871 HeapWord* result = NULL;
872 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
873 bool should_try_gc;
874 uint gc_count_before;
875
876
877 {
878 MutexLockerEx x(Heap_lock);
879
880 // Given that humongous objects are not allocated in young
881 // regions, we'll first try to do the allocation without doing a
882 // collection hoping that there's enough space in the heap.
883 result = humongous_obj_allocate(word_size);
884 if (result != NULL) {
885 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
886 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
887 return result;
888 }
889
890 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
891 // the GCLocker initiated GC has been performed and then retry. This includes
892 // the case when the GC Locker is not active but has not been performed.
893 should_try_gc = !GCLocker::needs_gc();
894 // Read the GC count while still holding the Heap_lock.
895 gc_count_before = total_collections();
896 }
897
898 if (should_try_gc) {
899 bool succeeded;
900 result = do_collection_pause(word_size, gc_count_before, &succeeded,
901 GCCause::_g1_humongous_allocation);
902 if (result != NULL) {
903 assert(succeeded, "only way to get back a non-NULL result");
904 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
905 Thread::current()->name(), p2i(result));
906 return result;
907 }
908
909 if (succeeded) {
910 // We successfully scheduled a collection which failed to allocate. No
911 // point in trying to allocate further. We'll just return NULL.
912 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
913 SIZE_FORMAT " words", Thread::current()->name(), word_size);
914 return NULL;
915 }
916 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
917 Thread::current()->name(), word_size);
918 } else {
919 // Failed to schedule a collection.
920 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
921 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
922 SIZE_FORMAT " words", Thread::current()->name(), word_size);
923 return NULL;
924 }
925 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
926 // The GCLocker is either active or the GCLocker initiated
927 // GC has not yet been performed. Stall until it is and
928 // then retry the allocation.
929 GCLocker::stall_until_clear();
930 gclocker_retry_count += 1;
931 }
932
933
934 // We can reach here if we were unsuccessful in scheduling a
935 // collection (because another thread beat us to it) or if we were
936 // stalled due to the GC locker. In either can we should retry the
937 // allocation attempt in case another thread successfully
938 // performed a collection and reclaimed enough space.
939 // Humongous object allocation always needs a lock, so we wait for the retry
940 // in the next iteration of the loop, unlike for the regular iteration case.
941 // Give a warning if we seem to be looping forever.
942
943 if ((QueuedAllocationWarningCount > 0) &&
944 (try_count % QueuedAllocationWarningCount == 0)) {
945 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
946 Thread::current()->name(), try_count, word_size);
947 }
948 }
949
950 ShouldNotReachHere();
951 return NULL;
952 }
953
954 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
955 bool expect_null_mutator_alloc_region) {
956 assert_at_safepoint_on_vm_thread();
957 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
958 "the current alloc region was unexpectedly found to be non-NULL");
959
960 if (!is_humongous(word_size)) {
961 return _allocator->attempt_allocation_locked(word_size);
962 } else {
963 HeapWord* result = humongous_obj_allocate(word_size);
964 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
965 collector_state()->set_initiate_conc_mark_if_possible(true);
966 }
967 return result;
968 }
969
970 ShouldNotReachHere();
971 }
972
973 class PostCompactionPrinterClosure: public HeapRegionClosure {
974 private:
975 G1HRPrinter* _hr_printer;
976 public:
977 bool do_heap_region(HeapRegion* hr) {
978 assert(!hr->is_young(), "not expecting to find young regions");
979 _hr_printer->post_compaction(hr);
980 return false;
981 }
982
983 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
984 : _hr_printer(hr_printer) { }
985 };
986
987 void G1CollectedHeap::print_hrm_post_compaction() {
988 if (_hr_printer.is_active()) {
989 PostCompactionPrinterClosure cl(hr_printer());
990 heap_region_iterate(&cl);
991 }
992 }
993
994 void G1CollectedHeap::abort_concurrent_cycle() {
995 // If we start the compaction before the CM threads finish
996 // scanning the root regions we might trip them over as we'll
997 // be moving objects / updating references. So let's wait until
998 // they are done. By telling them to abort, they should complete
999 // early.
1000 _cm->root_regions()->abort();
1001 _cm->root_regions()->wait_until_scan_finished();
1002
1003 // Disable discovery and empty the discovered lists
1004 // for the CM ref processor.
1005 _ref_processor_cm->disable_discovery();
1006 _ref_processor_cm->abandon_partial_discovery();
1007 _ref_processor_cm->verify_no_references_recorded();
1008
1009 // Abandon current iterations of concurrent marking and concurrent
1010 // refinement, if any are in progress.
1011 concurrent_mark()->concurrent_cycle_abort();
1012 }
1013
1014 void G1CollectedHeap::prepare_heap_for_full_collection() {
1015 // Make sure we'll choose a new allocation region afterwards.
1016 _allocator->release_mutator_alloc_region();
1017 _allocator->abandon_gc_alloc_regions();
1018 g1_rem_set()->cleanupHRRS();
1019
1020 // We may have added regions to the current incremental collection
1021 // set between the last GC or pause and now. We need to clear the
1022 // incremental collection set and then start rebuilding it afresh
1023 // after this full GC.
1024 abandon_collection_set(collection_set());
1025
1026 tear_down_region_sets(false /* free_list_only */);
1027 }
1028
1029 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1030 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1031 assert(used() == recalculate_used(), "Should be equal");
1032 _verifier->verify_region_sets_optional();
1033 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1034 _verifier->check_bitmaps("Full GC Start");
1035 }
1036
1037 void G1CollectedHeap::prepare_heap_for_mutators() {
1038 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1039 ClassLoaderDataGraph::purge();
1040 MetaspaceUtils::verify_metrics();
1041
1042 // Prepare heap for normal collections.
1043 assert(num_free_regions() == 0, "we should not have added any free regions");
1044 rebuild_region_sets(false /* free_list_only */);
1045 abort_refinement();
1046 resize_heap_if_necessary();
1047
1048 // Rebuild the strong code root lists for each region
1049 rebuild_strong_code_roots();
1050
1051 // Purge code root memory
1052 purge_code_root_memory();
1053
1054 // Start a new incremental collection set for the next pause
1055 start_new_collection_set();
1056
1057 _allocator->init_mutator_alloc_region();
1058
1059 // Post collection state updates.
1060 MetaspaceGC::compute_new_size();
1061 }
1062
1063 void G1CollectedHeap::abort_refinement() {
1064 if (_hot_card_cache->use_cache()) {
1065 _hot_card_cache->reset_hot_cache();
1066 }
1067
1068 // Discard all remembered set updates.
1069 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1070 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1071 }
1072
1073 void G1CollectedHeap::verify_after_full_collection() {
1074 _hrm.verify_optional();
1075 _verifier->verify_region_sets_optional();
1076 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1077 // Clear the previous marking bitmap, if needed for bitmap verification.
1078 // Note we cannot do this when we clear the next marking bitmap in
1079 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1080 // objects marked during a full GC against the previous bitmap.
1081 // But we need to clear it before calling check_bitmaps below since
1082 // the full GC has compacted objects and updated TAMS but not updated
1083 // the prev bitmap.
1084 if (G1VerifyBitmaps) {
1085 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1086 _cm->clear_prev_bitmap(workers());
1087 }
1088 // This call implicitly verifies that the next bitmap is clear after Full GC.
1089 _verifier->check_bitmaps("Full GC End");
1090
1091 // At this point there should be no regions in the
1092 // entire heap tagged as young.
1093 assert(check_young_list_empty(), "young list should be empty at this point");
1094
1095 // Note: since we've just done a full GC, concurrent
1096 // marking is no longer active. Therefore we need not
1097 // re-enable reference discovery for the CM ref processor.
1098 // That will be done at the start of the next marking cycle.
1099 // We also know that the STW processor should no longer
1100 // discover any new references.
1101 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1102 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1103 _ref_processor_stw->verify_no_references_recorded();
1104 _ref_processor_cm->verify_no_references_recorded();
1105 }
1106
1107 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1108 // Post collection logging.
1109 // We should do this after we potentially resize the heap so
1110 // that all the COMMIT / UNCOMMIT events are generated before
1111 // the compaction events.
1112 print_hrm_post_compaction();
1113 heap_transition->print();
1114 print_heap_after_gc();
1115 print_heap_regions();
1116 #ifdef TRACESPINNING
1117 ParallelTaskTerminator::print_termination_counts();
1118 #endif
1119 }
1120
1121 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1122 bool clear_all_soft_refs) {
1123 assert_at_safepoint_on_vm_thread();
1124
1125 if (GCLocker::check_active_before_gc()) {
1126 // Full GC was not completed.
1127 return false;
1128 }
1129
1130 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1131 soft_ref_policy()->should_clear_all_soft_refs();
1132
1133 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1134 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1135
1136 collector.prepare_collection();
1137 collector.collect();
1138 collector.complete_collection();
1139
1140 // Full collection was successfully completed.
1141 return true;
1142 }
1143
1144 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1145 // Currently, there is no facility in the do_full_collection(bool) API to notify
1146 // the caller that the collection did not succeed (e.g., because it was locked
1147 // out by the GC locker). So, right now, we'll ignore the return value.
1148 bool dummy = do_full_collection(true, /* explicit_gc */
1149 clear_all_soft_refs);
1150 }
1151
1152 void G1CollectedHeap::resize_heap_if_necessary() {
1153 assert_at_safepoint_on_vm_thread();
1154
1155 // Capacity, free and used after the GC counted as full regions to
1156 // include the waste in the following calculations.
1157 const size_t capacity_after_gc = capacity();
1158 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1159
1160 // This is enforced in arguments.cpp.
1161 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1162 "otherwise the code below doesn't make sense");
1163
1164 // We don't have floating point command-line arguments
1165 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1166 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1167 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1168 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1169
1170 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1171 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1172
1173 // We have to be careful here as these two calculations can overflow
1174 // 32-bit size_t's.
1175 double used_after_gc_d = (double) used_after_gc;
1176 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1177 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1178
1179 // Let's make sure that they are both under the max heap size, which
1180 // by default will make them fit into a size_t.
1181 double desired_capacity_upper_bound = (double) max_heap_size;
1182 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1183 desired_capacity_upper_bound);
1184 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1185 desired_capacity_upper_bound);
1186
1187 // We can now safely turn them into size_t's.
1188 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1189 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1190
1191 // This assert only makes sense here, before we adjust them
1192 // with respect to the min and max heap size.
1193 assert(minimum_desired_capacity <= maximum_desired_capacity,
1194 "minimum_desired_capacity = " SIZE_FORMAT ", "
1195 "maximum_desired_capacity = " SIZE_FORMAT,
1196 minimum_desired_capacity, maximum_desired_capacity);
1197
1198 // Should not be greater than the heap max size. No need to adjust
1199 // it with respect to the heap min size as it's a lower bound (i.e.,
1200 // we'll try to make the capacity larger than it, not smaller).
1201 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1202 // Should not be less than the heap min size. No need to adjust it
1203 // with respect to the heap max size as it's an upper bound (i.e.,
1204 // we'll try to make the capacity smaller than it, not greater).
1205 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1206
1207 if (capacity_after_gc < minimum_desired_capacity) {
1208 // Don't expand unless it's significant
1209 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1210
1211 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1212 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1213 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1214 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1215
1216 expand(expand_bytes, _workers);
1217
1218 // No expansion, now see if we want to shrink
1219 } else if (capacity_after_gc > maximum_desired_capacity) {
1220 // Capacity too large, compute shrinking size
1221 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1222
1223 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1224 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1225 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1226 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1227
1228 shrink(shrink_bytes);
1229 }
1230 }
1231
1232 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1233 bool do_gc,
1234 bool clear_all_soft_refs,
1235 bool expect_null_mutator_alloc_region,
1236 bool* gc_succeeded) {
1237 *gc_succeeded = true;
1238 // Let's attempt the allocation first.
1239 HeapWord* result =
1240 attempt_allocation_at_safepoint(word_size,
1241 expect_null_mutator_alloc_region);
1242 if (result != NULL) {
1243 return result;
1244 }
1245
1246 // In a G1 heap, we're supposed to keep allocation from failing by
1247 // incremental pauses. Therefore, at least for now, we'll favor
1248 // expansion over collection. (This might change in the future if we can
1249 // do something smarter than full collection to satisfy a failed alloc.)
1250 result = expand_and_allocate(word_size);
1251 if (result != NULL) {
1252 return result;
1253 }
1254
1255 if (do_gc) {
1256 // Expansion didn't work, we'll try to do a Full GC.
1257 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1258 clear_all_soft_refs);
1259 }
1260
1261 return NULL;
1262 }
1263
1264 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1265 bool* succeeded) {
1266 assert_at_safepoint_on_vm_thread();
1267
1268 // Attempts to allocate followed by Full GC.
1269 HeapWord* result =
1270 satisfy_failed_allocation_helper(word_size,
1271 true, /* do_gc */
1272 false, /* clear_all_soft_refs */
1273 false, /* expect_null_mutator_alloc_region */
1274 succeeded);
1275
1276 if (result != NULL || !*succeeded) {
1277 return result;
1278 }
1279
1280 // Attempts to allocate followed by Full GC that will collect all soft references.
1281 result = satisfy_failed_allocation_helper(word_size,
1282 true, /* do_gc */
1283 true, /* clear_all_soft_refs */
1284 true, /* expect_null_mutator_alloc_region */
1285 succeeded);
1286
1287 if (result != NULL || !*succeeded) {
1288 return result;
1289 }
1290
1291 // Attempts to allocate, no GC
1292 result = satisfy_failed_allocation_helper(word_size,
1293 false, /* do_gc */
1294 false, /* clear_all_soft_refs */
1295 true, /* expect_null_mutator_alloc_region */
1296 succeeded);
1297
1298 if (result != NULL) {
1299 return result;
1300 }
1301
1302 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1303 "Flag should have been handled and cleared prior to this point");
1304
1305 // What else? We might try synchronous finalization later. If the total
1306 // space available is large enough for the allocation, then a more
1307 // complete compaction phase than we've tried so far might be
1308 // appropriate.
1309 return NULL;
1310 }
1311
1312 // Attempting to expand the heap sufficiently
1313 // to support an allocation of the given "word_size". If
1314 // successful, perform the allocation and return the address of the
1315 // allocated block, or else "NULL".
1316
1317 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1318 assert_at_safepoint_on_vm_thread();
1319
1320 _verifier->verify_region_sets_optional();
1321
1322 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1323 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1324 word_size * HeapWordSize);
1325
1326
1327 if (expand(expand_bytes, _workers)) {
1328 _hrm.verify_optional();
1329 _verifier->verify_region_sets_optional();
1330 return attempt_allocation_at_safepoint(word_size,
1331 false /* expect_null_mutator_alloc_region */);
1332 }
1333 return NULL;
1334 }
1335
1336 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1337 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1338 aligned_expand_bytes = align_up(aligned_expand_bytes,
1339 HeapRegion::GrainBytes);
1340
1341 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1342 expand_bytes, aligned_expand_bytes);
1343
1344 if (is_maximal_no_gc()) {
1345 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1346 return false;
1347 }
1348
1349 double expand_heap_start_time_sec = os::elapsedTime();
1350 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1351 assert(regions_to_expand > 0, "Must expand by at least one region");
1352
1353 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1354 if (expand_time_ms != NULL) {
1355 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1356 }
1357
1358 if (expanded_by > 0) {
1359 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1360 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1361 g1_policy()->record_new_heap_size(num_regions());
1362 } else {
1363 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1364
1365 // The expansion of the virtual storage space was unsuccessful.
1366 // Let's see if it was because we ran out of swap.
1367 if (G1ExitOnExpansionFailure &&
1368 _hrm.available() >= regions_to_expand) {
1369 // We had head room...
1370 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1371 }
1372 }
1373 return regions_to_expand > 0;
1374 }
1375
1376 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1377 size_t aligned_shrink_bytes =
1378 ReservedSpace::page_align_size_down(shrink_bytes);
1379 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1380 HeapRegion::GrainBytes);
1381 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1382
1383 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1384 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1385
1386
1387 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",
1388 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1389 if (num_regions_removed > 0) {
1390 g1_policy()->record_new_heap_size(num_regions());
1391 } else {
1392 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1393 }
1394 }
1395
1396 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1397 _verifier->verify_region_sets_optional();
1398
1399 // We should only reach here at the end of a Full GC or during Remark which
1400 // means we should not not be holding to any GC alloc regions. The method
1401 // below will make sure of that and do any remaining clean up.
1402 _allocator->abandon_gc_alloc_regions();
1403
1404 // Instead of tearing down / rebuilding the free lists here, we
1405 // could instead use the remove_all_pending() method on free_list to
1406 // remove only the ones that we need to remove.
1407 tear_down_region_sets(true /* free_list_only */);
1408 shrink_helper(shrink_bytes);
1409 rebuild_region_sets(true /* free_list_only */);
1410
1411 _hrm.verify_optional();
1412 _verifier->verify_region_sets_optional();
1413 }
1414
1415 class OldRegionSetChecker : public HeapRegionSetChecker {
1416 public:
1417 void check_mt_safety() {
1418 // Master Old Set MT safety protocol:
1419 // (a) If we're at a safepoint, operations on the master old set
1420 // should be invoked:
1421 // - by the VM thread (which will serialize them), or
1422 // - by the GC workers while holding the FreeList_lock, if we're
1423 // at a safepoint for an evacuation pause (this lock is taken
1424 // anyway when an GC alloc region is retired so that a new one
1425 // is allocated from the free list), or
1426 // - by the GC workers while holding the OldSets_lock, if we're at a
1427 // safepoint for a cleanup pause.
1428 // (b) If we're not at a safepoint, operations on the master old set
1429 // should be invoked while holding the Heap_lock.
1430
1431 if (SafepointSynchronize::is_at_safepoint()) {
1432 guarantee(Thread::current()->is_VM_thread() ||
1433 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1434 "master old set MT safety protocol at a safepoint");
1435 } else {
1436 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1437 }
1438 }
1439 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1440 const char* get_description() { return "Old Regions"; }
1441 };
1442
1443 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1444 public:
1445 void check_mt_safety() {
1446 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1447 "May only change archive regions during initialization or safepoint.");
1448 }
1449 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1450 const char* get_description() { return "Archive Regions"; }
1451 };
1452
1453 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1454 public:
1455 void check_mt_safety() {
1456 // Humongous Set MT safety protocol:
1457 // (a) If we're at a safepoint, operations on the master humongous
1458 // set should be invoked by either the VM thread (which will
1459 // serialize them) or by the GC workers while holding the
1460 // OldSets_lock.
1461 // (b) If we're not at a safepoint, operations on the master
1462 // humongous set should be invoked while holding the Heap_lock.
1463
1464 if (SafepointSynchronize::is_at_safepoint()) {
1465 guarantee(Thread::current()->is_VM_thread() ||
1466 OldSets_lock->owned_by_self(),
1467 "master humongous set MT safety protocol at a safepoint");
1468 } else {
1469 guarantee(Heap_lock->owned_by_self(),
1470 "master humongous set MT safety protocol outside a safepoint");
1471 }
1472 }
1473 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1474 const char* get_description() { return "Humongous Regions"; }
1475 };
1476
1477 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1478 CollectedHeap(),
1479 _young_gen_sampling_thread(NULL),
1480 _workers(NULL),
1481 _collector_policy(collector_policy),
1482 _card_table(NULL),
1483 _soft_ref_policy(),
1484 _old_set("Old Region Set", new OldRegionSetChecker()),
1485 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1486 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1487 _bot(NULL),
1488 _listener(),
1489 _hrm(),
1490 _allocator(NULL),
1491 _verifier(NULL),
1492 _summary_bytes_used(0),
1493 _archive_allocator(NULL),
1494 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1495 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1496 _expand_heap_after_alloc_failure(true),
1497 _g1mm(NULL),
1498 _humongous_reclaim_candidates(),
1499 _has_humongous_reclaim_candidates(false),
1500 _hr_printer(),
1501 _collector_state(),
1502 _old_marking_cycles_started(0),
1503 _old_marking_cycles_completed(0),
1504 _eden(),
1505 _survivor(),
1506 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1507 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1508 _g1_policy(new G1Policy(_gc_timer_stw)),
1509 _heap_sizing_policy(NULL),
1510 _collection_set(this, _g1_policy),
1511 _hot_card_cache(NULL),
1512 _g1_rem_set(NULL),
1513 _dirty_card_queue_set(false),
1514 _cm(NULL),
1515 _cm_thread(NULL),
1516 _cr(NULL),
1517 _task_queues(NULL),
1518 _evacuation_failed(false),
1519 _evacuation_failed_info_array(NULL),
1520 _preserved_marks_set(true /* in_c_heap */),
1521 #ifndef PRODUCT
1522 _evacuation_failure_alot_for_current_gc(false),
1523 _evacuation_failure_alot_gc_number(0),
1524 _evacuation_failure_alot_count(0),
1525 #endif
1526 _ref_processor_stw(NULL),
1527 _is_alive_closure_stw(this),
1528 _is_subject_to_discovery_stw(this),
1529 _ref_processor_cm(NULL),
1530 _is_alive_closure_cm(this),
1531 _is_subject_to_discovery_cm(this),
1532 _in_cset_fast_test() {
1533
1534 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1535 true /* are_GC_task_threads */,
1536 false /* are_ConcurrentGC_threads */);
1537 _workers->initialize_workers();
1538 _verifier = new G1HeapVerifier(this);
1539
1540 _allocator = new G1Allocator(this);
1541
1542 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1543
1544 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1545
1546 // Override the default _filler_array_max_size so that no humongous filler
1547 // objects are created.
1548 _filler_array_max_size = _humongous_object_threshold_in_words;
1549
1550 uint n_queues = ParallelGCThreads;
1551 _task_queues = new RefToScanQueueSet(n_queues);
1552
1553 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1554
1555 for (uint i = 0; i < n_queues; i++) {
1556 RefToScanQueue* q = new RefToScanQueue();
1557 q->initialize();
1558 _task_queues->register_queue(i, q);
1559 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1560 }
1561
1562 // Initialize the G1EvacuationFailureALot counters and flags.
1563 NOT_PRODUCT(reset_evacuation_should_fail();)
1564
1565 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1566 }
1567
1568 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1569 size_t size,
1570 size_t translation_factor) {
1571 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1572 // Allocate a new reserved space, preferring to use large pages.
1573 ReservedSpace rs(size, preferred_page_size);
1574 G1RegionToSpaceMapper* result =
1575 G1RegionToSpaceMapper::create_mapper(rs,
1576 size,
1577 rs.alignment(),
1578 HeapRegion::GrainBytes,
1579 translation_factor,
1580 mtGC);
1581
1582 os::trace_page_sizes_for_requested_size(description,
1583 size,
1584 preferred_page_size,
1585 rs.alignment(),
1586 rs.base(),
1587 rs.size());
1588
1589 return result;
1590 }
1591
1592 jint G1CollectedHeap::initialize_concurrent_refinement() {
1593 jint ecode = JNI_OK;
1594 _cr = G1ConcurrentRefine::create(&ecode);
1595 return ecode;
1596 }
1597
1598 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1599 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1600 if (_young_gen_sampling_thread->osthread() == NULL) {
1601 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1602 return JNI_ENOMEM;
1603 }
1604 return JNI_OK;
1605 }
1606
1607 jint G1CollectedHeap::initialize() {
1608 os::enable_vtime();
1609
1610 // Necessary to satisfy locking discipline assertions.
1611
1612 MutexLocker x(Heap_lock);
1613
1614 // While there are no constraints in the GC code that HeapWordSize
1615 // be any particular value, there are multiple other areas in the
1616 // system which believe this to be true (e.g. oop->object_size in some
1617 // cases incorrectly returns the size in wordSize units rather than
1618 // HeapWordSize).
1619 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1620
1621 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1622 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1623 size_t heap_alignment = collector_policy()->heap_alignment();
1624
1625 // Ensure that the sizes are properly aligned.
1626 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1627 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1628 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1629
1630 // Reserve the maximum.
1631
1632 // When compressed oops are enabled, the preferred heap base
1633 // is calculated by subtracting the requested size from the
1634 // 32Gb boundary and using the result as the base address for
1635 // heap reservation. If the requested size is not aligned to
1636 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1637 // into the ReservedHeapSpace constructor) then the actual
1638 // base of the reserved heap may end up differing from the
1639 // address that was requested (i.e. the preferred heap base).
1640 // If this happens then we could end up using a non-optimal
1641 // compressed oops mode.
1642
1643 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1644 heap_alignment);
1645
1646 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1647
1648 // Create the barrier set for the entire reserved region.
1649 G1CardTable* ct = new G1CardTable(reserved_region());
1650 ct->initialize();
1651 G1BarrierSet* bs = new G1BarrierSet(ct);
1652 bs->initialize();
1653 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1654 BarrierSet::set_barrier_set(bs);
1655 _card_table = ct;
1656
1657 // Create the hot card cache.
1658 _hot_card_cache = new G1HotCardCache(this);
1659
1660 // Carve out the G1 part of the heap.
1661 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1662 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1663 G1RegionToSpaceMapper* heap_storage =
1664 G1RegionToSpaceMapper::create_mapper(g1_rs,
1665 g1_rs.size(),
1666 page_size,
1667 HeapRegion::GrainBytes,
1668 1,
1669 mtJavaHeap);
1670 os::trace_page_sizes("Heap",
1671 collector_policy()->min_heap_byte_size(),
1672 max_byte_size,
1673 page_size,
1674 heap_rs.base(),
1675 heap_rs.size());
1676 heap_storage->set_mapping_changed_listener(&_listener);
1677
1678 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1679 G1RegionToSpaceMapper* bot_storage =
1680 create_aux_memory_mapper("Block Offset Table",
1681 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1682 G1BlockOffsetTable::heap_map_factor());
1683
1684 G1RegionToSpaceMapper* cardtable_storage =
1685 create_aux_memory_mapper("Card Table",
1686 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1687 G1CardTable::heap_map_factor());
1688
1689 G1RegionToSpaceMapper* card_counts_storage =
1690 create_aux_memory_mapper("Card Counts Table",
1691 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1692 G1CardCounts::heap_map_factor());
1693
1694 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1695 G1RegionToSpaceMapper* prev_bitmap_storage =
1696 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1697 G1RegionToSpaceMapper* next_bitmap_storage =
1698 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1699
1700 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1701 _card_table->initialize(cardtable_storage);
1702 // Do later initialization work for concurrent refinement.
1703 _hot_card_cache->initialize(card_counts_storage);
1704
1705 // 6843694 - ensure that the maximum region index can fit
1706 // in the remembered set structures.
1707 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1708 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1709
1710 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1711 // start within the first card.
1712 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1713 // Also create a G1 rem set.
1714 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1715 _g1_rem_set->initialize(max_capacity(), max_regions());
1716
1717 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1718 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1719 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1720 "too many cards per region");
1721
1722 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1723
1724 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1725
1726 {
1727 HeapWord* start = _hrm.reserved().start();
1728 HeapWord* end = _hrm.reserved().end();
1729 size_t granularity = HeapRegion::GrainBytes;
1730
1731 _in_cset_fast_test.initialize(start, end, granularity);
1732 _humongous_reclaim_candidates.initialize(start, end, granularity);
1733 }
1734
1735 // Create the G1ConcurrentMark data structure and thread.
1736 // (Must do this late, so that "max_regions" is defined.)
1737 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1738 if (_cm == NULL || !_cm->completed_initialization()) {
1739 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1740 return JNI_ENOMEM;
1741 }
1742 _cm_thread = _cm->cm_thread();
1743
1744 // Now expand into the initial heap size.
1745 if (!expand(init_byte_size, _workers)) {
1746 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1747 return JNI_ENOMEM;
1748 }
1749
1750 // Perform any initialization actions delegated to the policy.
1751 g1_policy()->init(this, &_collection_set);
1752
1753 G1BarrierSet::satb_mark_queue_set().initialize(this,
1754 SATB_Q_CBL_mon,
1755 SATB_Q_FL_lock,
1756 G1SATBProcessCompletedThreshold,
1757 G1SATBBufferEnqueueingThresholdPercent,
1758 Shared_SATB_Q_lock);
1759
1760 jint ecode = initialize_concurrent_refinement();
1761 if (ecode != JNI_OK) {
1762 return ecode;
1763 }
1764
1765 ecode = initialize_young_gen_sampling_thread();
1766 if (ecode != JNI_OK) {
1767 return ecode;
1768 }
1769
1770 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1771 DirtyCardQ_FL_lock,
1772 (int)concurrent_refine()->yellow_zone(),
1773 (int)concurrent_refine()->red_zone(),
1774 Shared_DirtyCardQ_lock,
1775 NULL, // fl_owner
1776 true); // init_free_ids
1777
1778 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1779 DirtyCardQ_FL_lock,
1780 -1, // never trigger processing
1781 -1, // no limit on length
1782 Shared_DirtyCardQ_lock,
1783 &G1BarrierSet::dirty_card_queue_set());
1784
1785 // Here we allocate the dummy HeapRegion that is required by the
1786 // G1AllocRegion class.
1787 HeapRegion* dummy_region = _hrm.get_dummy_region();
1788
1789 // We'll re-use the same region whether the alloc region will
1790 // require BOT updates or not and, if it doesn't, then a non-young
1791 // region will complain that it cannot support allocations without
1792 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1793 dummy_region->set_eden();
1794 // Make sure it's full.
1795 dummy_region->set_top(dummy_region->end());
1796 G1AllocRegion::setup(this, dummy_region);
1797
1798 _allocator->init_mutator_alloc_region();
1799
1800 // Do create of the monitoring and management support so that
1801 // values in the heap have been properly initialized.
1802 _g1mm = new G1MonitoringSupport(this);
1803
1804 G1StringDedup::initialize();
1805
1806 _preserved_marks_set.init(ParallelGCThreads);
1807
1808 _collection_set.initialize(max_regions());
1809
1810 return JNI_OK;
1811 }
1812
1813 void G1CollectedHeap::stop() {
1814 // Stop all concurrent threads. We do this to make sure these threads
1815 // do not continue to execute and access resources (e.g. logging)
1816 // that are destroyed during shutdown.
1817 _cr->stop();
1818 _young_gen_sampling_thread->stop();
1819 _cm_thread->stop();
1820 if (G1StringDedup::is_enabled()) {
1821 G1StringDedup::stop();
1822 }
1823 }
1824
1825 void G1CollectedHeap::safepoint_synchronize_begin() {
1826 SuspendibleThreadSet::synchronize();
1827 }
1828
1829 void G1CollectedHeap::safepoint_synchronize_end() {
1830 SuspendibleThreadSet::desynchronize();
1831 }
1832
1833 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1834 return HeapRegion::max_region_size();
1835 }
1836
1837 void G1CollectedHeap::post_initialize() {
1838 CollectedHeap::post_initialize();
1839 ref_processing_init();
1840 }
1841
1842 void G1CollectedHeap::ref_processing_init() {
1843 // Reference processing in G1 currently works as follows:
1844 //
1845 // * There are two reference processor instances. One is
1846 // used to record and process discovered references
1847 // during concurrent marking; the other is used to
1848 // record and process references during STW pauses
1849 // (both full and incremental).
1850 // * Both ref processors need to 'span' the entire heap as
1851 // the regions in the collection set may be dotted around.
1852 //
1853 // * For the concurrent marking ref processor:
1854 // * Reference discovery is enabled at initial marking.
1855 // * Reference discovery is disabled and the discovered
1856 // references processed etc during remarking.
1857 // * Reference discovery is MT (see below).
1858 // * Reference discovery requires a barrier (see below).
1859 // * Reference processing may or may not be MT
1860 // (depending on the value of ParallelRefProcEnabled
1861 // and ParallelGCThreads).
1862 // * A full GC disables reference discovery by the CM
1863 // ref processor and abandons any entries on it's
1864 // discovered lists.
1865 //
1866 // * For the STW processor:
1867 // * Non MT discovery is enabled at the start of a full GC.
1868 // * Processing and enqueueing during a full GC is non-MT.
1869 // * During a full GC, references are processed after marking.
1870 //
1871 // * Discovery (may or may not be MT) is enabled at the start
1872 // of an incremental evacuation pause.
1873 // * References are processed near the end of a STW evacuation pause.
1874 // * For both types of GC:
1875 // * Discovery is atomic - i.e. not concurrent.
1876 // * Reference discovery will not need a barrier.
1877
1878 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1879
1880 // Concurrent Mark ref processor
1881 _ref_processor_cm =
1882 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1883 mt_processing, // mt processing
1884 ParallelGCThreads, // degree of mt processing
1885 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1886 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1887 false, // Reference discovery is not atomic
1888 &_is_alive_closure_cm, // is alive closure
1889 true); // allow changes to number of processing threads
1890
1891 // STW ref processor
1892 _ref_processor_stw =
1893 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1894 mt_processing, // mt processing
1895 ParallelGCThreads, // degree of mt processing
1896 (ParallelGCThreads > 1), // mt discovery
1897 ParallelGCThreads, // degree of mt discovery
1898 true, // Reference discovery is atomic
1899 &_is_alive_closure_stw, // is alive closure
1900 true); // allow changes to number of processing threads
1901 }
1902
1903 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1904 return _collector_policy;
1905 }
1906
1907 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1908 return &_soft_ref_policy;
1909 }
1910
1911 size_t G1CollectedHeap::capacity() const {
1912 return _hrm.length() * HeapRegion::GrainBytes;
1913 }
1914
1915 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1916 return _hrm.total_free_bytes();
1917 }
1918
1919 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1920 _hot_card_cache->drain(cl, worker_i);
1921 }
1922
1923 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1924 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1925 size_t n_completed_buffers = 0;
1926 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1927 n_completed_buffers++;
1928 }
1929 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1930 dcqs.clear_n_completed_buffers();
1931 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1932 }
1933
1934 // Computes the sum of the storage used by the various regions.
1935 size_t G1CollectedHeap::used() const {
1936 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1937 if (_archive_allocator != NULL) {
1938 result += _archive_allocator->used();
1939 }
1940 return result;
1941 }
1942
1943 size_t G1CollectedHeap::used_unlocked() const {
1944 return _summary_bytes_used;
1945 }
1946
1947 class SumUsedClosure: public HeapRegionClosure {
1948 size_t _used;
1949 public:
1950 SumUsedClosure() : _used(0) {}
1951 bool do_heap_region(HeapRegion* r) {
1952 _used += r->used();
1953 return false;
1954 }
1955 size_t result() { return _used; }
1956 };
1957
1958 size_t G1CollectedHeap::recalculate_used() const {
1959 SumUsedClosure blk;
1960 heap_region_iterate(&blk);
1961 return blk.result();
1962 }
1963
1964 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1965 switch (cause) {
1966 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1967 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1968 case GCCause::_wb_conc_mark: return true;
1969 default : return false;
1970 }
1971 }
1972
1973 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1974 switch (cause) {
1975 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1976 case GCCause::_g1_humongous_allocation: return true;
1977 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1978 default: return is_user_requested_concurrent_full_gc(cause);
1979 }
1980 }
1981
1982 #ifndef PRODUCT
1983 void G1CollectedHeap::allocate_dummy_regions() {
1984 // Let's fill up most of the region
1985 size_t word_size = HeapRegion::GrainWords - 1024;
1986 // And as a result the region we'll allocate will be humongous.
1987 guarantee(is_humongous(word_size), "sanity");
1988
1989 // _filler_array_max_size is set to humongous object threshold
1990 // but temporarily change it to use CollectedHeap::fill_with_object().
1991 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1992
1993 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1994 // Let's use the existing mechanism for the allocation
1995 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1996 if (dummy_obj != NULL) {
1997 MemRegion mr(dummy_obj, word_size);
1998 CollectedHeap::fill_with_object(mr);
1999 } else {
2000 // If we can't allocate once, we probably cannot allocate
2001 // again. Let's get out of the loop.
2002 break;
2003 }
2004 }
2005 }
2006 #endif // !PRODUCT
2007
2008 void G1CollectedHeap::increment_old_marking_cycles_started() {
2009 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2010 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2011 "Wrong marking cycle count (started: %d, completed: %d)",
2012 _old_marking_cycles_started, _old_marking_cycles_completed);
2013
2014 _old_marking_cycles_started++;
2015 }
2016
2017 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2018 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2019
2020 // We assume that if concurrent == true, then the caller is a
2021 // concurrent thread that was joined the Suspendible Thread
2022 // Set. If there's ever a cheap way to check this, we should add an
2023 // assert here.
2024
2025 // Given that this method is called at the end of a Full GC or of a
2026 // concurrent cycle, and those can be nested (i.e., a Full GC can
2027 // interrupt a concurrent cycle), the number of full collections
2028 // completed should be either one (in the case where there was no
2029 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2030 // behind the number of full collections started.
2031
2032 // This is the case for the inner caller, i.e. a Full GC.
2033 assert(concurrent ||
2034 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2035 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2036 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2037 "is inconsistent with _old_marking_cycles_completed = %u",
2038 _old_marking_cycles_started, _old_marking_cycles_completed);
2039
2040 // This is the case for the outer caller, i.e. the concurrent cycle.
2041 assert(!concurrent ||
2042 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2043 "for outer caller (concurrent cycle): "
2044 "_old_marking_cycles_started = %u "
2045 "is inconsistent with _old_marking_cycles_completed = %u",
2046 _old_marking_cycles_started, _old_marking_cycles_completed);
2047
2048 _old_marking_cycles_completed += 1;
2049
2050 // We need to clear the "in_progress" flag in the CM thread before
2051 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2052 // is set) so that if a waiter requests another System.gc() it doesn't
2053 // incorrectly see that a marking cycle is still in progress.
2054 if (concurrent) {
2055 _cm_thread->set_idle();
2056 }
2057
2058 // This notify_all() will ensure that a thread that called
2059 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2060 // and it's waiting for a full GC to finish will be woken up. It is
2061 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2062 FullGCCount_lock->notify_all();
2063 }
2064
2065 void G1CollectedHeap::collect(GCCause::Cause cause) {
2066 assert_heap_not_locked();
2067
2068 uint gc_count_before;
2069 uint old_marking_count_before;
2070 uint full_gc_count_before;
2071 bool retry_gc;
2072
2073 do {
2074 retry_gc = false;
2075
2076 {
2077 MutexLocker ml(Heap_lock);
2078
2079 // Read the GC count while holding the Heap_lock
2080 gc_count_before = total_collections();
2081 full_gc_count_before = total_full_collections();
2082 old_marking_count_before = _old_marking_cycles_started;
2083 }
2084
2085 if (should_do_concurrent_full_gc(cause)) {
2086 // Schedule an initial-mark evacuation pause that will start a
2087 // concurrent cycle. We're setting word_size to 0 which means that
2088 // we are not requesting a post-GC allocation.
2089 VM_G1CollectForAllocation op(0, /* word_size */
2090 gc_count_before,
2091 cause,
2092 true, /* should_initiate_conc_mark */
2093 g1_policy()->max_pause_time_ms());
2094 VMThread::execute(&op);
2095 if (!op.pause_succeeded()) {
2096 if (old_marking_count_before == _old_marking_cycles_started) {
2097 retry_gc = op.should_retry_gc();
2098 } else {
2099 // A Full GC happened while we were trying to schedule the
2100 // initial-mark GC. No point in starting a new cycle given
2101 // that the whole heap was collected anyway.
2102 }
2103
2104 if (retry_gc) {
2105 if (GCLocker::is_active_and_needs_gc()) {
2106 GCLocker::stall_until_clear();
2107 }
2108 }
2109 }
2110 } else {
2111 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2112 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2113
2114 // Schedule a standard evacuation pause. We're setting word_size
2115 // to 0 which means that we are not requesting a post-GC allocation.
2116 VM_G1CollectForAllocation op(0, /* word_size */
2117 gc_count_before,
2118 cause,
2119 false, /* should_initiate_conc_mark */
2120 g1_policy()->max_pause_time_ms());
2121 VMThread::execute(&op);
2122 } else {
2123 // Schedule a Full GC.
2124 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2125 VMThread::execute(&op);
2126 }
2127 }
2128 } while (retry_gc);
2129 }
2130
2131 bool G1CollectedHeap::is_in(const void* p) const {
2132 if (_hrm.reserved().contains(p)) {
2133 // Given that we know that p is in the reserved space,
2134 // heap_region_containing() should successfully
2135 // return the containing region.
2136 HeapRegion* hr = heap_region_containing(p);
2137 return hr->is_in(p);
2138 } else {
2139 return false;
2140 }
2141 }
2142
2143 #ifdef ASSERT
2144 bool G1CollectedHeap::is_in_exact(const void* p) const {
2145 bool contains = reserved_region().contains(p);
2146 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2147 if (contains && available) {
2148 return true;
2149 } else {
2150 return false;
2151 }
2152 }
2153 #endif
2154
2155 // Iteration functions.
2156
2157 // Iterates an ObjectClosure over all objects within a HeapRegion.
2158
2159 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2160 ObjectClosure* _cl;
2161 public:
2162 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2163 bool do_heap_region(HeapRegion* r) {
2164 if (!r->is_continues_humongous()) {
2165 r->object_iterate(_cl);
2166 }
2167 return false;
2168 }
2169 };
2170
2171 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2172 IterateObjectClosureRegionClosure blk(cl);
2173 heap_region_iterate(&blk);
2174 }
2175
2176 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2177 _hrm.iterate(cl);
2178 }
2179
2180 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2181 HeapRegionClaimer *hrclaimer,
2182 uint worker_id) const {
2183 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2184 }
2185
2186 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2187 HeapRegionClaimer *hrclaimer) const {
2188 _hrm.par_iterate(cl, hrclaimer, 0);
2189 }
2190
2191 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2192 _collection_set.iterate(cl);
2193 }
2194
2195 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2196 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2197 }
2198
2199 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2200 HeapRegion* hr = heap_region_containing(addr);
2201 return hr->block_start(addr);
2202 }
2203
2204 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2205 HeapRegion* hr = heap_region_containing(addr);
2206 return hr->block_size(addr);
2207 }
2208
2209 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2210 HeapRegion* hr = heap_region_containing(addr);
2211 return hr->block_is_obj(addr);
2212 }
2213
2214 bool G1CollectedHeap::supports_tlab_allocation() const {
2215 return true;
2216 }
2217
2218 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2219 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2220 }
2221
2222 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2223 return _eden.length() * HeapRegion::GrainBytes;
2224 }
2225
2226 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2227 // must be equal to the humongous object limit.
2228 size_t G1CollectedHeap::max_tlab_size() const {
2229 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2230 }
2231
2232 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2233 return _allocator->unsafe_max_tlab_alloc();
2234 }
2235
2236 size_t G1CollectedHeap::max_capacity() const {
2237 return _hrm.reserved().byte_size();
2238 }
2239
2240 jlong G1CollectedHeap::millis_since_last_gc() {
2241 // See the notes in GenCollectedHeap::millis_since_last_gc()
2242 // for more information about the implementation.
2243 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2244 _g1_policy->collection_pause_end_millis();
2245 if (ret_val < 0) {
2246 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2247 ". returning zero instead.", ret_val);
2248 return 0;
2249 }
2250 return ret_val;
2251 }
2252
2253 void G1CollectedHeap::deduplicate_string(oop str) {
2254 assert(java_lang_String::is_instance(str), "invariant");
2255
2256 if (G1StringDedup::is_enabled()) {
2257 G1StringDedup::deduplicate(str);
2258 }
2259 }
2260
2261 void G1CollectedHeap::prepare_for_verify() {
2262 _verifier->prepare_for_verify();
2263 }
2264
2265 void G1CollectedHeap::verify(VerifyOption vo) {
2266 _verifier->verify(vo);
2267 }
2268
2269 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2270 return true;
2271 }
2272
2273 const char* const* G1CollectedHeap::concurrent_phases() const {
2274 return _cm_thread->concurrent_phases();
2275 }
2276
2277 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2278 return _cm_thread->request_concurrent_phase(phase);
2279 }
2280
2281 class PrintRegionClosure: public HeapRegionClosure {
2282 outputStream* _st;
2283 public:
2284 PrintRegionClosure(outputStream* st) : _st(st) {}
2285 bool do_heap_region(HeapRegion* r) {
2286 r->print_on(_st);
2287 return false;
2288 }
2289 };
2290
2291 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2292 const HeapRegion* hr,
2293 const VerifyOption vo) const {
2294 switch (vo) {
2295 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2296 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2297 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2298 default: ShouldNotReachHere();
2299 }
2300 return false; // keep some compilers happy
2301 }
2302
2303 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2304 const VerifyOption vo) const {
2305 switch (vo) {
2306 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2307 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2308 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2309 default: ShouldNotReachHere();
2310 }
2311 return false; // keep some compilers happy
2312 }
2313
2314 void G1CollectedHeap::print_heap_regions() const {
2315 LogTarget(Trace, gc, heap, region) lt;
2316 if (lt.is_enabled()) {
2317 LogStream ls(lt);
2318 print_regions_on(&ls);
2319 }
2320 }
2321
2322 void G1CollectedHeap::print_on(outputStream* st) const {
2323 st->print(" %-20s", "garbage-first heap");
2324 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2325 capacity()/K, used_unlocked()/K);
2326 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2327 p2i(_hrm.reserved().start()),
2328 p2i(_hrm.reserved().end()));
2329 st->cr();
2330 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2331 uint young_regions = young_regions_count();
2332 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2333 (size_t) young_regions * HeapRegion::GrainBytes / K);
2334 uint survivor_regions = survivor_regions_count();
2335 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2336 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2337 st->cr();
2338 MetaspaceUtils::print_on(st);
2339 }
2340
2341 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2342 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2343 "HS=humongous(starts), HC=humongous(continues), "
2344 "CS=collection set, F=free, A=archive, "
2345 "TAMS=top-at-mark-start (previous, next)");
2346 PrintRegionClosure blk(st);
2347 heap_region_iterate(&blk);
2348 }
2349
2350 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2351 print_on(st);
2352
2353 // Print the per-region information.
2354 print_regions_on(st);
2355 }
2356
2357 void G1CollectedHeap::print_on_error(outputStream* st) const {
2358 this->CollectedHeap::print_on_error(st);
2359
2360 if (_cm != NULL) {
2361 st->cr();
2362 _cm->print_on_error(st);
2363 }
2364 }
2365
2366 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2367 workers()->print_worker_threads_on(st);
2368 _cm_thread->print_on(st);
2369 st->cr();
2370 _cm->print_worker_threads_on(st);
2371 _cr->print_threads_on(st);
2372 _young_gen_sampling_thread->print_on(st);
2373 if (G1StringDedup::is_enabled()) {
2374 G1StringDedup::print_worker_threads_on(st);
2375 }
2376 }
2377
2378 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2379 workers()->threads_do(tc);
2380 tc->do_thread(_cm_thread);
2381 _cm->threads_do(tc);
2382 _cr->threads_do(tc);
2383 tc->do_thread(_young_gen_sampling_thread);
2384 if (G1StringDedup::is_enabled()) {
2385 G1StringDedup::threads_do(tc);
2386 }
2387 }
2388
2389 void G1CollectedHeap::print_tracing_info() const {
2390 g1_rem_set()->print_summary_info();
2391 concurrent_mark()->print_summary_info();
2392 }
2393
2394 #ifndef PRODUCT
2395 // Helpful for debugging RSet issues.
2396
2397 class PrintRSetsClosure : public HeapRegionClosure {
2398 private:
2399 const char* _msg;
2400 size_t _occupied_sum;
2401
2402 public:
2403 bool do_heap_region(HeapRegion* r) {
2404 HeapRegionRemSet* hrrs = r->rem_set();
2405 size_t occupied = hrrs->occupied();
2406 _occupied_sum += occupied;
2407
2408 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2409 if (occupied == 0) {
2410 tty->print_cr(" RSet is empty");
2411 } else {
2412 hrrs->print();
2413 }
2414 tty->print_cr("----------");
2415 return false;
2416 }
2417
2418 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2419 tty->cr();
2420 tty->print_cr("========================================");
2421 tty->print_cr("%s", msg);
2422 tty->cr();
2423 }
2424
2425 ~PrintRSetsClosure() {
2426 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2427 tty->print_cr("========================================");
2428 tty->cr();
2429 }
2430 };
2431
2432 void G1CollectedHeap::print_cset_rsets() {
2433 PrintRSetsClosure cl("Printing CSet RSets");
2434 collection_set_iterate(&cl);
2435 }
2436
2437 void G1CollectedHeap::print_all_rsets() {
2438 PrintRSetsClosure cl("Printing All RSets");;
2439 heap_region_iterate(&cl);
2440 }
2441 #endif // PRODUCT
2442
2443 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2444
2445 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2446 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2447 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2448
2449 size_t eden_capacity_bytes =
2450 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2451
2452 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2453 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2454 eden_capacity_bytes, survivor_used_bytes, num_regions());
2455 }
2456
2457 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2458 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2459 stats->unused(), stats->used(), stats->region_end_waste(),
2460 stats->regions_filled(), stats->direct_allocated(),
2461 stats->failure_used(), stats->failure_waste());
2462 }
2463
2464 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2465 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2466 gc_tracer->report_gc_heap_summary(when, heap_summary);
2467
2468 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2469 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2470 }
2471
2472 G1CollectedHeap* G1CollectedHeap::heap() {
2473 CollectedHeap* heap = Universe::heap();
2474 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2475 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2476 return (G1CollectedHeap*)heap;
2477 }
2478
2479 void G1CollectedHeap::gc_prologue(bool full) {
2480 // always_do_update_barrier = false;
2481 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2482
2483 // This summary needs to be printed before incrementing total collections.
2484 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2485
2486 // Update common counters.
2487 increment_total_collections(full /* full gc */);
2488 if (full) {
2489 increment_old_marking_cycles_started();
2490 }
2491
2492 // Fill TLAB's and such
2493 double start = os::elapsedTime();
2494 ensure_parsability(true);
2495 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2496 }
2497
2498 void G1CollectedHeap::gc_epilogue(bool full) {
2499 // Update common counters.
2500 if (full) {
2501 // Update the number of full collections that have been completed.
2502 increment_old_marking_cycles_completed(false /* concurrent */);
2503 }
2504
2505 // We are at the end of the GC. Total collections has already been increased.
2506 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2507
2508 // FIXME: what is this about?
2509 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2510 // is set.
2511 #if COMPILER2_OR_JVMCI
2512 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2513 #endif
2514 // always_do_update_barrier = true;
2515
2516 double start = os::elapsedTime();
2517 resize_all_tlabs();
2518 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2519
2520 MemoryService::track_memory_usage();
2521 // We have just completed a GC. Update the soft reference
2522 // policy with the new heap occupancy
2523 Universe::update_heap_info_at_gc();
2524 }
2525
2526 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2527 uint gc_count_before,
2528 bool* succeeded,
2529 GCCause::Cause gc_cause) {
2530 assert_heap_not_locked_and_not_at_safepoint();
2531 VM_G1CollectForAllocation op(word_size,
2532 gc_count_before,
2533 gc_cause,
2534 false, /* should_initiate_conc_mark */
2535 g1_policy()->max_pause_time_ms());
2536 VMThread::execute(&op);
2537
2538 HeapWord* result = op.result();
2539 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2540 assert(result == NULL || ret_succeeded,
2541 "the result should be NULL if the VM did not succeed");
2542 *succeeded = ret_succeeded;
2543
2544 assert_heap_not_locked();
2545 return result;
2546 }
2547
2548 void G1CollectedHeap::do_concurrent_mark() {
2549 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2550 if (!_cm_thread->in_progress()) {
2551 _cm_thread->set_started();
2552 CGC_lock->notify();
2553 }
2554 }
2555
2556 size_t G1CollectedHeap::pending_card_num() {
2557 size_t extra_cards = 0;
2558 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2559 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2560 extra_cards += dcq.size();
2561 }
2562 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2563 size_t buffer_size = dcqs.buffer_size();
2564 size_t buffer_num = dcqs.completed_buffers_num();
2565
2566 return buffer_size * buffer_num + extra_cards;
2567 }
2568
2569 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2570 // We don't nominate objects with many remembered set entries, on
2571 // the assumption that such objects are likely still live.
2572 HeapRegionRemSet* rem_set = r->rem_set();
2573
2574 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2575 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2576 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2577 }
2578
2579 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2580 private:
2581 size_t _total_humongous;
2582 size_t _candidate_humongous;
2583
2584 DirtyCardQueue _dcq;
2585
2586 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2587 assert(region->is_starts_humongous(), "Must start a humongous object");
2588
2589 oop obj = oop(region->bottom());
2590
2591 // Dead objects cannot be eager reclaim candidates. Due to class
2592 // unloading it is unsafe to query their classes so we return early.
2593 if (g1h->is_obj_dead(obj, region)) {
2594 return false;
2595 }
2596
2597 // If we do not have a complete remembered set for the region, then we can
2598 // not be sure that we have all references to it.
2599 if (!region->rem_set()->is_complete()) {
2600 return false;
2601 }
2602 // Candidate selection must satisfy the following constraints
2603 // while concurrent marking is in progress:
2604 //
2605 // * In order to maintain SATB invariants, an object must not be
2606 // reclaimed if it was allocated before the start of marking and
2607 // has not had its references scanned. Such an object must have
2608 // its references (including type metadata) scanned to ensure no
2609 // live objects are missed by the marking process. Objects
2610 // allocated after the start of concurrent marking don't need to
2611 // be scanned.
2612 //
2613 // * An object must not be reclaimed if it is on the concurrent
2614 // mark stack. Objects allocated after the start of concurrent
2615 // marking are never pushed on the mark stack.
2616 //
2617 // Nominating only objects allocated after the start of concurrent
2618 // marking is sufficient to meet both constraints. This may miss
2619 // some objects that satisfy the constraints, but the marking data
2620 // structures don't support efficiently performing the needed
2621 // additional tests or scrubbing of the mark stack.
2622 //
2623 // However, we presently only nominate is_typeArray() objects.
2624 // A humongous object containing references induces remembered
2625 // set entries on other regions. In order to reclaim such an
2626 // object, those remembered sets would need to be cleaned up.
2627 //
2628 // We also treat is_typeArray() objects specially, allowing them
2629 // to be reclaimed even if allocated before the start of
2630 // concurrent mark. For this we rely on mark stack insertion to
2631 // exclude is_typeArray() objects, preventing reclaiming an object
2632 // that is in the mark stack. We also rely on the metadata for
2633 // such objects to be built-in and so ensured to be kept live.
2634 // Frequent allocation and drop of large binary blobs is an
2635 // important use case for eager reclaim, and this special handling
2636 // may reduce needed headroom.
2637
2638 return obj->is_typeArray() &&
2639 g1h->is_potential_eager_reclaim_candidate(region);
2640 }
2641
2642 public:
2643 RegisterHumongousWithInCSetFastTestClosure()
2644 : _total_humongous(0),
2645 _candidate_humongous(0),
2646 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2647 }
2648
2649 virtual bool do_heap_region(HeapRegion* r) {
2650 if (!r->is_starts_humongous()) {
2651 return false;
2652 }
2653 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2654
2655 bool is_candidate = humongous_region_is_candidate(g1h, r);
2656 uint rindex = r->hrm_index();
2657 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2658 if (is_candidate) {
2659 _candidate_humongous++;
2660 g1h->register_humongous_region_with_cset(rindex);
2661 // Is_candidate already filters out humongous object with large remembered sets.
2662 // If we have a humongous object with a few remembered sets, we simply flush these
2663 // remembered set entries into the DCQS. That will result in automatic
2664 // re-evaluation of their remembered set entries during the following evacuation
2665 // phase.
2666 if (!r->rem_set()->is_empty()) {
2667 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2668 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2669 G1CardTable* ct = g1h->card_table();
2670 HeapRegionRemSetIterator hrrs(r->rem_set());
2671 size_t card_index;
2672 while (hrrs.has_next(card_index)) {
2673 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2674 // The remembered set might contain references to already freed
2675 // regions. Filter out such entries to avoid failing card table
2676 // verification.
2677 if (!g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2678 continue;
2679 }
2680 if (*card_ptr != G1CardTable::dirty_card_val()) {
2681 *card_ptr = G1CardTable::dirty_card_val();
2682 _dcq.enqueue(card_ptr);
2683 }
2684 }
2685 // We should only clear the card based remembered set here as we will not
2686 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2687 // (and probably never) we do not enter this path if there are other kind of
2688 // remembered sets for this region.
2689 r->rem_set()->clear_locked(true /* only_cardset */);
2690 // Clear_locked() above sets the state to Empty. However we want to continue
2691 // collecting remembered set entries for humongous regions that were not
2692 // reclaimed.
2693 r->rem_set()->set_state_complete();
2694 }
2695 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2696 }
2697 _total_humongous++;
2698
2699 return false;
2700 }
2701
2702 size_t total_humongous() const { return _total_humongous; }
2703 size_t candidate_humongous() const { return _candidate_humongous; }
2704
2705 void flush_rem_set_entries() { _dcq.flush(); }
2706 };
2707
2708 void G1CollectedHeap::register_humongous_regions_with_cset() {
2709 if (!G1EagerReclaimHumongousObjects) {
2710 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2711 return;
2712 }
2713 double time = os::elapsed_counter();
2714
2715 // Collect reclaim candidate information and register candidates with cset.
2716 RegisterHumongousWithInCSetFastTestClosure cl;
2717 heap_region_iterate(&cl);
2718
2719 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2720 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2721 cl.total_humongous(),
2722 cl.candidate_humongous());
2723 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2724
2725 // Finally flush all remembered set entries to re-check into the global DCQS.
2726 cl.flush_rem_set_entries();
2727 }
2728
2729 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2730 public:
2731 bool do_heap_region(HeapRegion* hr) {
2732 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2733 hr->verify_rem_set();
2734 }
2735 return false;
2736 }
2737 };
2738
2739 uint G1CollectedHeap::num_task_queues() const {
2740 return _task_queues->size();
2741 }
2742
2743 #if TASKQUEUE_STATS
2744 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2745 st->print_raw_cr("GC Task Stats");
2746 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2747 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2748 }
2749
2750 void G1CollectedHeap::print_taskqueue_stats() const {
2751 if (!log_is_enabled(Trace, gc, task, stats)) {
2752 return;
2753 }
2754 Log(gc, task, stats) log;
2755 ResourceMark rm;
2756 LogStream ls(log.trace());
2757 outputStream* st = &ls;
2758
2759 print_taskqueue_stats_hdr(st);
2760
2761 TaskQueueStats totals;
2762 const uint n = num_task_queues();
2763 for (uint i = 0; i < n; ++i) {
2764 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2765 totals += task_queue(i)->stats;
2766 }
2767 st->print_raw("tot "); totals.print(st); st->cr();
2768
2769 DEBUG_ONLY(totals.verify());
2770 }
2771
2772 void G1CollectedHeap::reset_taskqueue_stats() {
2773 const uint n = num_task_queues();
2774 for (uint i = 0; i < n; ++i) {
2775 task_queue(i)->stats.reset();
2776 }
2777 }
2778 #endif // TASKQUEUE_STATS
2779
2780 void G1CollectedHeap::wait_for_root_region_scanning() {
2781 double scan_wait_start = os::elapsedTime();
2782 // We have to wait until the CM threads finish scanning the
2783 // root regions as it's the only way to ensure that all the
2784 // objects on them have been correctly scanned before we start
2785 // moving them during the GC.
2786 bool waited = _cm->root_regions()->wait_until_scan_finished();
2787 double wait_time_ms = 0.0;
2788 if (waited) {
2789 double scan_wait_end = os::elapsedTime();
2790 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2791 }
2792 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2793 }
2794
2795 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2796 private:
2797 G1HRPrinter* _hr_printer;
2798 public:
2799 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2800
2801 virtual bool do_heap_region(HeapRegion* r) {
2802 _hr_printer->cset(r);
2803 return false;
2804 }
2805 };
2806
2807 void G1CollectedHeap::start_new_collection_set() {
2808 collection_set()->start_incremental_building();
2809
2810 clear_cset_fast_test();
2811
2812 guarantee(_eden.length() == 0, "eden should have been cleared");
2813 g1_policy()->transfer_survivors_to_cset(survivor());
2814 }
2815
2816 bool
2817 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2818 assert_at_safepoint_on_vm_thread();
2819 guarantee(!is_gc_active(), "collection is not reentrant");
2820
2821 if (GCLocker::check_active_before_gc()) {
2822 return false;
2823 }
2824
2825 _gc_timer_stw->register_gc_start();
2826
2827 GCIdMark gc_id_mark;
2828 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2829
2830 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2831 ResourceMark rm;
2832
2833 g1_policy()->note_gc_start();
2834
2835 wait_for_root_region_scanning();
2836
2837 print_heap_before_gc();
2838 print_heap_regions();
2839 trace_heap_before_gc(_gc_tracer_stw);
2840
2841 _verifier->verify_region_sets_optional();
2842 _verifier->verify_dirty_young_regions();
2843
2844 // We should not be doing initial mark unless the conc mark thread is running
2845 if (!_cm_thread->should_terminate()) {
2846 // This call will decide whether this pause is an initial-mark
2847 // pause. If it is, in_initial_mark_gc() will return true
2848 // for the duration of this pause.
2849 g1_policy()->decide_on_conc_mark_initiation();
2850 }
2851
2852 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2853 assert(!collector_state()->in_initial_mark_gc() ||
2854 collector_state()->in_young_only_phase(), "sanity");
2855
2856 // We also do not allow mixed GCs during marking.
2857 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2858
2859 // Record whether this pause is an initial mark. When the current
2860 // thread has completed its logging output and it's safe to signal
2861 // the CM thread, the flag's value in the policy has been reset.
2862 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2863
2864 // Inner scope for scope based logging, timers, and stats collection
2865 {
2866 EvacuationInfo evacuation_info;
2867
2868 if (collector_state()->in_initial_mark_gc()) {
2869 // We are about to start a marking cycle, so we increment the
2870 // full collection counter.
2871 increment_old_marking_cycles_started();
2872 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2873 }
2874
2875 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2876
2877 GCTraceCPUTime tcpu;
2878
2879 G1HeapVerifier::G1VerifyType verify_type;
2880 FormatBuffer<> gc_string("Pause Young ");
2881 if (collector_state()->in_initial_mark_gc()) {
2882 gc_string.append("(Concurrent Start)");
2883 verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2884 } else if (collector_state()->in_young_only_phase()) {
2885 if (collector_state()->in_young_gc_before_mixed()) {
2886 gc_string.append("(Prepare Mixed)");
2887 } else {
2888 gc_string.append("(Normal)");
2889 }
2890 verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2891 } else {
2892 gc_string.append("(Mixed)");
2893 verify_type = G1HeapVerifier::G1VerifyMixed;
2894 }
2895 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2896
2897 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2898 workers()->active_workers(),
2899 Threads::number_of_non_daemon_threads());
2900 active_workers = workers()->update_active_workers(active_workers);
2901 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2902
2903 G1MonitoringScope ms(g1mm(),
2904 false /* full_gc */,
2905 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2906
2907 G1HeapTransition heap_transition(this);
2908 size_t heap_used_bytes_before_gc = used();
2909
2910 // Don't dynamically change the number of GC threads this early. A value of
2911 // 0 is used to indicate serial work. When parallel work is done,
2912 // it will be set.
2913
2914 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2915 IsGCActiveMark x;
2916
2917 gc_prologue(false);
2918
2919 if (VerifyRememberedSets) {
2920 log_info(gc, verify)("[Verifying RemSets before GC]");
2921 VerifyRegionRemSetClosure v_cl;
2922 heap_region_iterate(&v_cl);
2923 }
2924
2925 _verifier->verify_before_gc(verify_type);
2926
2927 _verifier->check_bitmaps("GC Start");
2928
2929 #if COMPILER2_OR_JVMCI
2930 DerivedPointerTable::clear();
2931 #endif
2932
2933 // Please see comment in g1CollectedHeap.hpp and
2934 // G1CollectedHeap::ref_processing_init() to see how
2935 // reference processing currently works in G1.
2936
2937 // Enable discovery in the STW reference processor
2938 _ref_processor_stw->enable_discovery();
2939
2940 {
2941 // We want to temporarily turn off discovery by the
2942 // CM ref processor, if necessary, and turn it back on
2943 // on again later if we do. Using a scoped
2944 // NoRefDiscovery object will do this.
2945 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2946
2947 // Forget the current alloc region (we might even choose it to be part
2948 // of the collection set!).
2949 _allocator->release_mutator_alloc_region();
2950
2951 // This timing is only used by the ergonomics to handle our pause target.
2952 // It is unclear why this should not include the full pause. We will
2953 // investigate this in CR 7178365.
2954 //
2955 // Preserving the old comment here if that helps the investigation:
2956 //
2957 // The elapsed time induced by the start time below deliberately elides
2958 // the possible verification above.
2959 double sample_start_time_sec = os::elapsedTime();
2960
2961 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2962
2963 if (collector_state()->in_initial_mark_gc()) {
2964 concurrent_mark()->pre_initial_mark();
2965 }
2966
2967 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2968
2969 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2970
2971 // Make sure the remembered sets are up to date. This needs to be
2972 // done before register_humongous_regions_with_cset(), because the
2973 // remembered sets are used there to choose eager reclaim candidates.
2974 // If the remembered sets are not up to date we might miss some
2975 // entries that need to be handled.
2976 g1_rem_set()->cleanupHRRS();
2977
2978 register_humongous_regions_with_cset();
2979
2980 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2981
2982 // We call this after finalize_cset() to
2983 // ensure that the CSet has been finalized.
2984 _cm->verify_no_cset_oops();
2985
2986 if (_hr_printer.is_active()) {
2987 G1PrintCollectionSetClosure cl(&_hr_printer);
2988 _collection_set.iterate(&cl);
2989 }
2990
2991 // Initialize the GC alloc regions.
2992 _allocator->init_gc_alloc_regions(evacuation_info);
2993
2994 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2995 pre_evacuate_collection_set();
2996
2997 // Actually do the work...
2998 evacuate_collection_set(&per_thread_states);
2999
3000 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3001
3002 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3003 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3004
3005 eagerly_reclaim_humongous_regions();
3006
3007 record_obj_copy_mem_stats();
3008 _survivor_evac_stats.adjust_desired_plab_sz();
3009 _old_evac_stats.adjust_desired_plab_sz();
3010
3011 double start = os::elapsedTime();
3012 start_new_collection_set();
3013 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3014
3015 if (evacuation_failed()) {
3016 double recalculate_used_start = os::elapsedTime();
3017 set_used(recalculate_used());
3018 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3019
3020 if (_archive_allocator != NULL) {
3021 _archive_allocator->clear_used();
3022 }
3023 for (uint i = 0; i < ParallelGCThreads; i++) {
3024 if (_evacuation_failed_info_array[i].has_failed()) {
3025 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3026 }
3027 }
3028 } else {
3029 // The "used" of the the collection set have already been subtracted
3030 // when they were freed. Add in the bytes evacuated.
3031 increase_used(g1_policy()->bytes_copied_during_gc());
3032 }
3033
3034 if (collector_state()->in_initial_mark_gc()) {
3035 // We have to do this before we notify the CM threads that
3036 // they can start working to make sure that all the
3037 // appropriate initialization is done on the CM object.
3038 concurrent_mark()->post_initial_mark();
3039 // Note that we don't actually trigger the CM thread at
3040 // this point. We do that later when we're sure that
3041 // the current thread has completed its logging output.
3042 }
3043
3044 allocate_dummy_regions();
3045
3046 _allocator->init_mutator_alloc_region();
3047
3048 {
3049 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3050 if (expand_bytes > 0) {
3051 size_t bytes_before = capacity();
3052 // No need for an ergo logging here,
3053 // expansion_amount() does this when it returns a value > 0.
3054 double expand_ms;
3055 if (!expand(expand_bytes, _workers, &expand_ms)) {
3056 // We failed to expand the heap. Cannot do anything about it.
3057 }
3058 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3059 }
3060 }
3061
3062 // We redo the verification but now wrt to the new CSet which
3063 // has just got initialized after the previous CSet was freed.
3064 _cm->verify_no_cset_oops();
3065
3066 // This timing is only used by the ergonomics to handle our pause target.
3067 // It is unclear why this should not include the full pause. We will
3068 // investigate this in CR 7178365.
3069 double sample_end_time_sec = os::elapsedTime();
3070 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3071 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3072 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3073
3074 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3075 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3076
3077 if (VerifyRememberedSets) {
3078 log_info(gc, verify)("[Verifying RemSets after GC]");
3079 VerifyRegionRemSetClosure v_cl;
3080 heap_region_iterate(&v_cl);
3081 }
3082
3083 _verifier->verify_after_gc(verify_type);
3084 _verifier->check_bitmaps("GC End");
3085
3086 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3087 _ref_processor_stw->verify_no_references_recorded();
3088
3089 // CM reference discovery will be re-enabled if necessary.
3090 }
3091
3092 #ifdef TRACESPINNING
3093 ParallelTaskTerminator::print_termination_counts();
3094 #endif
3095
3096 gc_epilogue(false);
3097 }
3098
3099 // Print the remainder of the GC log output.
3100 if (evacuation_failed()) {
3101 log_info(gc)("To-space exhausted");
3102 }
3103
3104 g1_policy()->print_phases();
3105 heap_transition.print();
3106
3107 // It is not yet to safe to tell the concurrent mark to
3108 // start as we have some optional output below. We don't want the
3109 // output from the concurrent mark thread interfering with this
3110 // logging output either.
3111
3112 _hrm.verify_optional();
3113 _verifier->verify_region_sets_optional();
3114
3115 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3116 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3117
3118 print_heap_after_gc();
3119 print_heap_regions();
3120 trace_heap_after_gc(_gc_tracer_stw);
3121
3122 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3123 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3124 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3125 // before any GC notifications are raised.
3126 g1mm()->update_sizes();
3127
3128 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3129 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3130 _gc_timer_stw->register_gc_end();
3131 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3132 }
3133 // It should now be safe to tell the concurrent mark thread to start
3134 // without its logging output interfering with the logging output
3135 // that came from the pause.
3136
3137 if (should_start_conc_mark) {
3138 // CAUTION: after the doConcurrentMark() call below,
3139 // the concurrent marking thread(s) could be running
3140 // concurrently with us. Make sure that anything after
3141 // this point does not assume that we are the only GC thread
3142 // running. Note: of course, the actual marking work will
3143 // not start until the safepoint itself is released in
3144 // SuspendibleThreadSet::desynchronize().
3145 do_concurrent_mark();
3146 }
3147
3148 return true;
3149 }
3150
3151 void G1CollectedHeap::remove_self_forwarding_pointers() {
3152 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3153 workers()->run_task(&rsfp_task);
3154 }
3155
3156 void G1CollectedHeap::restore_after_evac_failure() {
3157 double remove_self_forwards_start = os::elapsedTime();
3158
3159 remove_self_forwarding_pointers();
3160 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3161 _preserved_marks_set.restore(&task_executor);
3162
3163 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3164 }
3165
3166 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3167 if (!_evacuation_failed) {
3168 _evacuation_failed = true;
3169 }
3170
3171 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3172 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3173 }
3174
3175 bool G1ParEvacuateFollowersClosure::offer_termination() {
3176 EventGCPhaseParallel event;
3177 G1ParScanThreadState* const pss = par_scan_state();
3178 start_term_time();
3179 const bool res = terminator()->offer_termination();
3180 end_term_time();
3181 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3182 return res;
3183 }
3184
3185 void G1ParEvacuateFollowersClosure::do_void() {
3186 EventGCPhaseParallel event;
3187 G1ParScanThreadState* const pss = par_scan_state();
3188 pss->trim_queue();
3189 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3190 do {
3191 EventGCPhaseParallel event;
3192 pss->steal_and_trim_queue(queues());
3193 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3194 } while (!offer_termination());
3195 }
3196
3197 class G1ParTask : public AbstractGangTask {
3198 protected:
3199 G1CollectedHeap* _g1h;
3200 G1ParScanThreadStateSet* _pss;
3201 RefToScanQueueSet* _queues;
3202 G1RootProcessor* _root_processor;
3203 ParallelTaskTerminator _terminator;
3204 uint _n_workers;
3205
3206 public:
3207 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3208 : AbstractGangTask("G1 collection"),
3209 _g1h(g1h),
3210 _pss(per_thread_states),
3211 _queues(task_queues),
3212 _root_processor(root_processor),
3213 _terminator(n_workers, _queues),
3214 _n_workers(n_workers)
3215 {}
3216
3217 void work(uint worker_id) {
3218 if (worker_id >= _n_workers) return; // no work needed this round
3219
3220 double start_sec = os::elapsedTime();
3221 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3222
3223 {
3224 ResourceMark rm;
3225 HandleMark hm;
3226
3227 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3228
3229 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3230 pss->set_ref_discoverer(rp);
3231
3232 double start_strong_roots_sec = os::elapsedTime();
3233
3234 _root_processor->evacuate_roots(pss, worker_id);
3235
3236 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3237 // treating the nmethods visited to act as roots for concurrent marking.
3238 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3239 // objects copied by the current evacuation.
3240 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3241
3242 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3243
3244 double term_sec = 0.0;
3245 size_t evac_term_attempts = 0;
3246 {
3247 double start = os::elapsedTime();
3248 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3249 evac.do_void();
3250
3251 evac_term_attempts = evac.term_attempts();
3252 term_sec = evac.term_time();
3253 double elapsed_sec = os::elapsedTime() - start;
3254
3255 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3256 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3257 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3258 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3259 }
3260
3261 assert(pss->queue_is_empty(), "should be empty");
3262
3263 if (log_is_enabled(Debug, gc, task, stats)) {
3264 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3265 size_t lab_waste;
3266 size_t lab_undo_waste;
3267 pss->waste(lab_waste, lab_undo_waste);
3268 _g1h->print_termination_stats(worker_id,
3269 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3270 strong_roots_sec * 1000.0, /* strong roots time */
3271 term_sec * 1000.0, /* evac term time */
3272 evac_term_attempts, /* evac term attempts */
3273 lab_waste, /* alloc buffer waste */
3274 lab_undo_waste /* undo waste */
3275 );
3276 }
3277
3278 // Close the inner scope so that the ResourceMark and HandleMark
3279 // destructors are executed here and are included as part of the
3280 // "GC Worker Time".
3281 }
3282 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3283 }
3284 };
3285
3286 void G1CollectedHeap::print_termination_stats_hdr() {
3287 log_debug(gc, task, stats)("GC Termination Stats");
3288 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3289 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3290 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3291 }
3292
3293 void G1CollectedHeap::print_termination_stats(uint worker_id,
3294 double elapsed_ms,
3295 double strong_roots_ms,
3296 double term_ms,
3297 size_t term_attempts,
3298 size_t alloc_buffer_waste,
3299 size_t undo_waste) const {
3300 log_debug(gc, task, stats)
3301 ("%3d %9.2f %9.2f %6.2f "
3302 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3303 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3304 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3305 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3306 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3307 alloc_buffer_waste * HeapWordSize / K,
3308 undo_waste * HeapWordSize / K);
3309 }
3310
3311 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3312 bool class_unloading_occurred) {
3313 uint n_workers = workers()->active_workers();
3314
3315 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3316 ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
3317 workers()->run_task(&g1_unlink_task);
3318 }
3319
3320 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3321 bool process_strings,
3322 bool process_string_dedup) {
3323 if (!process_strings && !process_string_dedup) {
3324 // Nothing to clean.
3325 return;
3326 }
3327
3328 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3329 StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
3330 workers()->run_task(&g1_unlink_task);
3331 }
3332
3333 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3334 private:
3335 DirtyCardQueueSet* _queue;
3336 G1CollectedHeap* _g1h;
3337 public:
3338 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3339 _queue(queue), _g1h(g1h) { }
3340
3341 virtual void work(uint worker_id) {
3342 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3343 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3344
3345 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3346 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3347
3348 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3349 }
3350 };
3351
3352 void G1CollectedHeap::redirty_logged_cards() {
3353 double redirty_logged_cards_start = os::elapsedTime();
3354
3355 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3356 dirty_card_queue_set().reset_for_par_iteration();
3357 workers()->run_task(&redirty_task);
3358
3359 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3360 dcq.merge_bufferlists(&dirty_card_queue_set());
3361 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3362
3363 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3364 }
3365
3366 // Weak Reference Processing support
3367
3368 bool G1STWIsAliveClosure::do_object_b(oop p) {
3369 // An object is reachable if it is outside the collection set,
3370 // or is inside and copied.
3371 return !_g1h->is_in_cset(p) || p->is_forwarded();
3372 }
3373
3374 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3375 assert(obj != NULL, "must not be NULL");
3376 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3377 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3378 // may falsely indicate that this is not the case here: however the collection set only
3379 // contains old regions when concurrent mark is not running.
3380 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3381 }
3382
3383 // Non Copying Keep Alive closure
3384 class G1KeepAliveClosure: public OopClosure {
3385 G1CollectedHeap*_g1h;
3386 public:
3387 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3388 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3389 void do_oop(oop* p) {
3390 oop obj = *p;
3391 assert(obj != NULL, "the caller should have filtered out NULL values");
3392
3393 const InCSetState cset_state =_g1h->in_cset_state(obj);
3394 if (!cset_state.is_in_cset_or_humongous()) {
3395 return;
3396 }
3397 if (cset_state.is_in_cset()) {
3398 assert( obj->is_forwarded(), "invariant" );
3399 *p = obj->forwardee();
3400 } else {
3401 assert(!obj->is_forwarded(), "invariant" );
3402 assert(cset_state.is_humongous(),
3403 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3404 _g1h->set_humongous_is_live(obj);
3405 }
3406 }
3407 };
3408
3409 // Copying Keep Alive closure - can be called from both
3410 // serial and parallel code as long as different worker
3411 // threads utilize different G1ParScanThreadState instances
3412 // and different queues.
3413
3414 class G1CopyingKeepAliveClosure: public OopClosure {
3415 G1CollectedHeap* _g1h;
3416 G1ParScanThreadState* _par_scan_state;
3417
3418 public:
3419 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3420 G1ParScanThreadState* pss):
3421 _g1h(g1h),
3422 _par_scan_state(pss)
3423 {}
3424
3425 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3426 virtual void do_oop( oop* p) { do_oop_work(p); }
3427
3428 template <class T> void do_oop_work(T* p) {
3429 oop obj = RawAccess<>::oop_load(p);
3430
3431 if (_g1h->is_in_cset_or_humongous(obj)) {
3432 // If the referent object has been forwarded (either copied
3433 // to a new location or to itself in the event of an
3434 // evacuation failure) then we need to update the reference
3435 // field and, if both reference and referent are in the G1
3436 // heap, update the RSet for the referent.
3437 //
3438 // If the referent has not been forwarded then we have to keep
3439 // it alive by policy. Therefore we have copy the referent.
3440 //
3441 // When the queue is drained (after each phase of reference processing)
3442 // the object and it's followers will be copied, the reference field set
3443 // to point to the new location, and the RSet updated.
3444 _par_scan_state->push_on_queue(p);
3445 }
3446 }
3447 };
3448
3449 // Serial drain queue closure. Called as the 'complete_gc'
3450 // closure for each discovered list in some of the
3451 // reference processing phases.
3452
3453 class G1STWDrainQueueClosure: public VoidClosure {
3454 protected:
3455 G1CollectedHeap* _g1h;
3456 G1ParScanThreadState* _par_scan_state;
3457
3458 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3459
3460 public:
3461 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3462 _g1h(g1h),
3463 _par_scan_state(pss)
3464 { }
3465
3466 void do_void() {
3467 G1ParScanThreadState* const pss = par_scan_state();
3468 pss->trim_queue();
3469 }
3470 };
3471
3472 // Parallel Reference Processing closures
3473
3474 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3475 // processing during G1 evacuation pauses.
3476
3477 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3478 private:
3479 G1CollectedHeap* _g1h;
3480 G1ParScanThreadStateSet* _pss;
3481 RefToScanQueueSet* _queues;
3482 WorkGang* _workers;
3483
3484 public:
3485 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3486 G1ParScanThreadStateSet* per_thread_states,
3487 WorkGang* workers,
3488 RefToScanQueueSet *task_queues) :
3489 _g1h(g1h),
3490 _pss(per_thread_states),
3491 _queues(task_queues),
3492 _workers(workers)
3493 {
3494 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3495 }
3496
3497 // Executes the given task using concurrent marking worker threads.
3498 virtual void execute(ProcessTask& task, uint ergo_workers);
3499 };
3500
3501 // Gang task for possibly parallel reference processing
3502
3503 class G1STWRefProcTaskProxy: public AbstractGangTask {
3504 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3505 ProcessTask& _proc_task;
3506 G1CollectedHeap* _g1h;
3507 G1ParScanThreadStateSet* _pss;
3508 RefToScanQueueSet* _task_queues;
3509 ParallelTaskTerminator* _terminator;
3510
3511 public:
3512 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3513 G1CollectedHeap* g1h,
3514 G1ParScanThreadStateSet* per_thread_states,
3515 RefToScanQueueSet *task_queues,
3516 ParallelTaskTerminator* terminator) :
3517 AbstractGangTask("Process reference objects in parallel"),
3518 _proc_task(proc_task),
3519 _g1h(g1h),
3520 _pss(per_thread_states),
3521 _task_queues(task_queues),
3522 _terminator(terminator)
3523 {}
3524
3525 virtual void work(uint worker_id) {
3526 // The reference processing task executed by a single worker.
3527 ResourceMark rm;
3528 HandleMark hm;
3529
3530 G1STWIsAliveClosure is_alive(_g1h);
3531
3532 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3533 pss->set_ref_discoverer(NULL);
3534
3535 // Keep alive closure.
3536 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3537
3538 // Complete GC closure
3539 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3540
3541 // Call the reference processing task's work routine.
3542 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3543
3544 // Note we cannot assert that the refs array is empty here as not all
3545 // of the processing tasks (specifically phase2 - pp2_work) execute
3546 // the complete_gc closure (which ordinarily would drain the queue) so
3547 // the queue may not be empty.
3548 }
3549 };
3550
3551 // Driver routine for parallel reference processing.
3552 // Creates an instance of the ref processing gang
3553 // task and has the worker threads execute it.
3554 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3555 assert(_workers != NULL, "Need parallel worker threads.");
3556
3557 assert(_workers->active_workers() >= ergo_workers,
3558 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3559 ergo_workers, _workers->active_workers());
3560 ParallelTaskTerminator terminator(ergo_workers, _queues);
3561 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3562
3563 _workers->run_task(&proc_task_proxy, ergo_workers);
3564 }
3565
3566 // End of weak reference support closures
3567
3568 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3569 double ref_proc_start = os::elapsedTime();
3570
3571 ReferenceProcessor* rp = _ref_processor_stw;
3572 assert(rp->discovery_enabled(), "should have been enabled");
3573
3574 // Closure to test whether a referent is alive.
3575 G1STWIsAliveClosure is_alive(this);
3576
3577 // Even when parallel reference processing is enabled, the processing
3578 // of JNI refs is serial and performed serially by the current thread
3579 // rather than by a worker. The following PSS will be used for processing
3580 // JNI refs.
3581
3582 // Use only a single queue for this PSS.
3583 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3584 pss->set_ref_discoverer(NULL);
3585 assert(pss->queue_is_empty(), "pre-condition");
3586
3587 // Keep alive closure.
3588 G1CopyingKeepAliveClosure keep_alive(this, pss);
3589
3590 // Serial Complete GC closure
3591 G1STWDrainQueueClosure drain_queue(this, pss);
3592
3593 // Setup the soft refs policy...
3594 rp->setup_policy(false);
3595
3596 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3597
3598 ReferenceProcessorStats stats;
3599 if (!rp->processing_is_mt()) {
3600 // Serial reference processing...
3601 stats = rp->process_discovered_references(&is_alive,
3602 &keep_alive,
3603 &drain_queue,
3604 NULL,
3605 pt);
3606 } else {
3607 uint no_of_gc_workers = workers()->active_workers();
3608
3609 // Parallel reference processing
3610 assert(no_of_gc_workers <= rp->max_num_queues(),
3611 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3612 no_of_gc_workers, rp->max_num_queues());
3613
3614 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3615 stats = rp->process_discovered_references(&is_alive,
3616 &keep_alive,
3617 &drain_queue,
3618 &par_task_executor,
3619 pt);
3620 }
3621
3622 _gc_tracer_stw->report_gc_reference_stats(stats);
3623
3624 // We have completed copying any necessary live referent objects.
3625 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3626
3627 make_pending_list_reachable();
3628
3629 rp->verify_no_references_recorded();
3630
3631 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3632 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3633 }
3634
3635 void G1CollectedHeap::make_pending_list_reachable() {
3636 if (collector_state()->in_initial_mark_gc()) {
3637 oop pll_head = Universe::reference_pending_list();
3638 if (pll_head != NULL) {
3639 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3640 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3641 }
3642 }
3643 }
3644
3645 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3646 double merge_pss_time_start = os::elapsedTime();
3647 per_thread_states->flush();
3648 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3649 }
3650
3651 void G1CollectedHeap::pre_evacuate_collection_set() {
3652 _expand_heap_after_alloc_failure = true;
3653 _evacuation_failed = false;
3654
3655 // Disable the hot card cache.
3656 _hot_card_cache->reset_hot_cache_claimed_index();
3657 _hot_card_cache->set_use_cache(false);
3658
3659 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3660 _preserved_marks_set.assert_empty();
3661
3662 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3663
3664 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3665 if (collector_state()->in_initial_mark_gc()) {
3666 double start_clear_claimed_marks = os::elapsedTime();
3667
3668 ClassLoaderDataGraph::clear_claimed_marks();
3669
3670 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3671 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3672 }
3673 }
3674
3675 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3676 // Should G1EvacuationFailureALot be in effect for this GC?
3677 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3678
3679 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3680
3681 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3682
3683 double start_par_time_sec = os::elapsedTime();
3684 double end_par_time_sec;
3685
3686 {
3687 const uint n_workers = workers()->active_workers();
3688 G1RootProcessor root_processor(this, n_workers);
3689 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3690
3691 print_termination_stats_hdr();
3692
3693 workers()->run_task(&g1_par_task);
3694 end_par_time_sec = os::elapsedTime();
3695
3696 // Closing the inner scope will execute the destructor
3697 // for the G1RootProcessor object. We record the current
3698 // elapsed time before closing the scope so that time
3699 // taken for the destructor is NOT included in the
3700 // reported parallel time.
3701 }
3702
3703 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3704 phase_times->record_par_time(par_time_ms);
3705
3706 double code_root_fixup_time_ms =
3707 (os::elapsedTime() - end_par_time_sec) * 1000.0;
3708 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3709 }
3710
3711 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3712 // Also cleans the card table from temporary duplicate detection information used
3713 // during UpdateRS/ScanRS.
3714 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3715
3716 // Process any discovered reference objects - we have
3717 // to do this _before_ we retire the GC alloc regions
3718 // as we may have to copy some 'reachable' referent
3719 // objects (and their reachable sub-graphs) that were
3720 // not copied during the pause.
3721 process_discovered_references(per_thread_states);
3722
3723 // FIXME
3724 // CM's reference processing also cleans up the string table.
3725 // Should we do that here also? We could, but it is a serial operation
3726 // and could significantly increase the pause time.
3727
3728 G1STWIsAliveClosure is_alive(this);
3729 G1KeepAliveClosure keep_alive(this);
3730
3731 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3732 g1_policy()->phase_times()->weak_phase_times());
3733
3734 if (G1StringDedup::is_enabled()) {
3735 double fixup_start = os::elapsedTime();
3736
3737 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
3738
3739 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
3740 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
3741 }
3742
3743 if (evacuation_failed()) {
3744 restore_after_evac_failure();
3745
3746 // Reset the G1EvacuationFailureALot counters and flags
3747 // Note: the values are reset only when an actual
3748 // evacuation failure occurs.
3749 NOT_PRODUCT(reset_evacuation_should_fail();)
3750 }
3751
3752 _preserved_marks_set.assert_empty();
3753
3754 _allocator->release_gc_alloc_regions(evacuation_info);
3755
3756 merge_per_thread_state_info(per_thread_states);
3757
3758 // Reset and re-enable the hot card cache.
3759 // Note the counts for the cards in the regions in the
3760 // collection set are reset when the collection set is freed.
3761 _hot_card_cache->reset_hot_cache();
3762 _hot_card_cache->set_use_cache(true);
3763
3764 purge_code_root_memory();
3765
3766 redirty_logged_cards();
3767 #if COMPILER2_OR_JVMCI
3768 double start = os::elapsedTime();
3769 DerivedPointerTable::update_pointers();
3770 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3771 #endif
3772 g1_policy()->print_age_table();
3773 }
3774
3775 void G1CollectedHeap::record_obj_copy_mem_stats() {
3776 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3777
3778 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3779 create_g1_evac_summary(&_old_evac_stats));
3780 }
3781
3782 void G1CollectedHeap::free_region(HeapRegion* hr,
3783 FreeRegionList* free_list,
3784 bool skip_remset,
3785 bool skip_hot_card_cache,
3786 bool locked) {
3787 assert(!hr->is_free(), "the region should not be free");
3788 assert(!hr->is_empty(), "the region should not be empty");
3789 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
3790 assert(free_list != NULL, "pre-condition");
3791
3792 if (G1VerifyBitmaps) {
3793 MemRegion mr(hr->bottom(), hr->end());
3794 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3795 }
3796
3797 // Clear the card counts for this region.
3798 // Note: we only need to do this if the region is not young
3799 // (since we don't refine cards in young regions).
3800 if (!skip_hot_card_cache && !hr->is_young()) {
3801 _hot_card_cache->reset_card_counts(hr);
3802 }
3803 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3804 _g1_policy->remset_tracker()->update_at_free(hr);
3805 free_list->add_ordered(hr);
3806 }
3807
3808 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3809 FreeRegionList* free_list) {
3810 assert(hr->is_humongous(), "this is only for humongous regions");
3811 assert(free_list != NULL, "pre-condition");
3812 hr->clear_humongous();
3813 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3814 }
3815
3816 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3817 const uint humongous_regions_removed) {
3818 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3819 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3820 _old_set.bulk_remove(old_regions_removed);
3821 _humongous_set.bulk_remove(humongous_regions_removed);
3822 }
3823
3824 }
3825
3826 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3827 assert(list != NULL, "list can't be null");
3828 if (!list->is_empty()) {
3829 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3830 _hrm.insert_list_into_free_list(list);
3831 }
3832 }
3833
3834 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3835 decrease_used(bytes);
3836 }
3837
3838 class G1FreeCollectionSetTask : public AbstractGangTask {
3839 private:
3840
3841 // Closure applied to all regions in the collection set to do work that needs to
3842 // be done serially in a single thread.
3843 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3844 private:
3845 EvacuationInfo* _evacuation_info;
3846 const size_t* _surviving_young_words;
3847
3848 // Bytes used in successfully evacuated regions before the evacuation.
3849 size_t _before_used_bytes;
3850 // Bytes used in unsucessfully evacuated regions before the evacuation
3851 size_t _after_used_bytes;
3852
3853 size_t _bytes_allocated_in_old_since_last_gc;
3854
3855 size_t _failure_used_words;
3856 size_t _failure_waste_words;
3857
3858 FreeRegionList _local_free_list;
3859 public:
3860 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3861 HeapRegionClosure(),
3862 _evacuation_info(evacuation_info),
3863 _surviving_young_words(surviving_young_words),
3864 _before_used_bytes(0),
3865 _after_used_bytes(0),
3866 _bytes_allocated_in_old_since_last_gc(0),
3867 _failure_used_words(0),
3868 _failure_waste_words(0),
3869 _local_free_list("Local Region List for CSet Freeing") {
3870 }
3871
3872 virtual bool do_heap_region(HeapRegion* r) {
3873 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3874
3875 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3876 g1h->clear_in_cset(r);
3877
3878 if (r->is_young()) {
3879 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3880 "Young index %d is wrong for region %u of type %s with %u young regions",
3881 r->young_index_in_cset(),
3882 r->hrm_index(),
3883 r->get_type_str(),
3884 g1h->collection_set()->young_region_length());
3885 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3886 r->record_surv_words_in_group(words_survived);
3887 }
3888
3889 if (!r->evacuation_failed()) {
3890 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
3891 _before_used_bytes += r->used();
3892 g1h->free_region(r,
3893 &_local_free_list,
3894 true, /* skip_remset */
3895 true, /* skip_hot_card_cache */
3896 true /* locked */);
3897 } else {
3898 r->uninstall_surv_rate_group();
3899 r->set_young_index_in_cset(-1);
3900 r->set_evacuation_failed(false);
3901 // When moving a young gen region to old gen, we "allocate" that whole region
3902 // there. This is in addition to any already evacuated objects. Notify the
3903 // policy about that.
3904 // Old gen regions do not cause an additional allocation: both the objects
3905 // still in the region and the ones already moved are accounted for elsewhere.
3906 if (r->is_young()) {
3907 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
3908 }
3909 // The region is now considered to be old.
3910 r->set_old();
3911 // Do some allocation statistics accounting. Regions that failed evacuation
3912 // are always made old, so there is no need to update anything in the young
3913 // gen statistics, but we need to update old gen statistics.
3914 size_t used_words = r->marked_bytes() / HeapWordSize;
3915
3916 _failure_used_words += used_words;
3917 _failure_waste_words += HeapRegion::GrainWords - used_words;
3918
3919 g1h->old_set_add(r);
3920 _after_used_bytes += r->used();
3921 }
3922 return false;
3923 }
3924
3925 void complete_work() {
3926 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3927
3928 _evacuation_info->set_regions_freed(_local_free_list.length());
3929 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
3930
3931 g1h->prepend_to_freelist(&_local_free_list);
3932 g1h->decrement_summary_bytes(_before_used_bytes);
3933
3934 G1Policy* policy = g1h->g1_policy();
3935 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
3936
3937 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
3938 }
3939 };
3940
3941 G1CollectionSet* _collection_set;
3942 G1SerialFreeCollectionSetClosure _cl;
3943 const size_t* _surviving_young_words;
3944
3945 size_t _rs_lengths;
3946
3947 volatile jint _serial_work_claim;
3948
3949 struct WorkItem {
3950 uint region_idx;
3951 bool is_young;
3952 bool evacuation_failed;
3953
3954 WorkItem(HeapRegion* r) {
3955 region_idx = r->hrm_index();
3956 is_young = r->is_young();
3957 evacuation_failed = r->evacuation_failed();
3958 }
3959 };
3960
3961 volatile size_t _parallel_work_claim;
3962 size_t _num_work_items;
3963 WorkItem* _work_items;
3964
3965 void do_serial_work() {
3966 // Need to grab the lock to be allowed to modify the old region list.
3967 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3968 _collection_set->iterate(&_cl);
3969 }
3970
3971 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
3972 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3973
3974 HeapRegion* r = g1h->region_at(region_idx);
3975 assert(!g1h->is_on_master_free_list(r), "sanity");
3976
3977 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
3978
3979 if (!is_young) {
3980 g1h->_hot_card_cache->reset_card_counts(r);
3981 }
3982
3983 if (!evacuation_failed) {
3984 r->rem_set()->clear_locked();
3985 }
3986 }
3987
3988 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
3989 private:
3990 size_t _cur_idx;
3991 WorkItem* _work_items;
3992 public:
3993 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
3994
3995 virtual bool do_heap_region(HeapRegion* r) {
3996 _work_items[_cur_idx++] = WorkItem(r);
3997 return false;
3998 }
3999 };
4000
4001 void prepare_work() {
4002 G1PrepareFreeCollectionSetClosure cl(_work_items);
4003 _collection_set->iterate(&cl);
4004 }
4005
4006 void complete_work() {
4007 _cl.complete_work();
4008
4009 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4010 policy->record_max_rs_lengths(_rs_lengths);
4011 policy->cset_regions_freed();
4012 }
4013 public:
4014 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4015 AbstractGangTask("G1 Free Collection Set"),
4016 _collection_set(collection_set),
4017 _cl(evacuation_info, surviving_young_words),
4018 _surviving_young_words(surviving_young_words),
4019 _rs_lengths(0),
4020 _serial_work_claim(0),
4021 _parallel_work_claim(0),
4022 _num_work_items(collection_set->region_length()),
4023 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4024 prepare_work();
4025 }
4026
4027 ~G1FreeCollectionSetTask() {
4028 complete_work();
4029 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4030 }
4031
4032 // Chunk size for work distribution. The chosen value has been determined experimentally
4033 // to be a good tradeoff between overhead and achievable parallelism.
4034 static uint chunk_size() { return 32; }
4035
4036 virtual void work(uint worker_id) {
4037 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4038
4039 // Claim serial work.
4040 if (_serial_work_claim == 0) {
4041 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4042 if (value == 0) {
4043 double serial_time = os::elapsedTime();
4044 do_serial_work();
4045 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4046 }
4047 }
4048
4049 // Start parallel work.
4050 double young_time = 0.0;
4051 bool has_young_time = false;
4052 double non_young_time = 0.0;
4053 bool has_non_young_time = false;
4054
4055 while (true) {
4056 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4057 size_t cur = end - chunk_size();
4058
4059 if (cur >= _num_work_items) {
4060 break;
4061 }
4062
4063 EventGCPhaseParallel event;
4064 double start_time = os::elapsedTime();
4065
4066 end = MIN2(end, _num_work_items);
4067
4068 for (; cur < end; cur++) {
4069 bool is_young = _work_items[cur].is_young;
4070
4071 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4072
4073 double end_time = os::elapsedTime();
4074 double time_taken = end_time - start_time;
4075 if (is_young) {
4076 young_time += time_taken;
4077 has_young_time = true;
4078 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4079 } else {
4080 non_young_time += time_taken;
4081 has_non_young_time = true;
4082 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4083 }
4084 start_time = end_time;
4085 }
4086 }
4087
4088 if (has_young_time) {
4089 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4090 }
4091 if (has_non_young_time) {
4092 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4093 }
4094 }
4095 };
4096
4097 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4098 _eden.clear();
4099
4100 double free_cset_start_time = os::elapsedTime();
4101
4102 {
4103 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4104 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4105
4106 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4107
4108 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4109 cl.name(),
4110 num_workers,
4111 _collection_set.region_length());
4112 workers()->run_task(&cl, num_workers);
4113 }
4114 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4115
4116 collection_set->clear();
4117 }
4118
4119 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4120 private:
4121 FreeRegionList* _free_region_list;
4122 HeapRegionSet* _proxy_set;
4123 uint _humongous_objects_reclaimed;
4124 uint _humongous_regions_reclaimed;
4125 size_t _freed_bytes;
4126 public:
4127
4128 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4129 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4130 }
4131
4132 virtual bool do_heap_region(HeapRegion* r) {
4133 if (!r->is_starts_humongous()) {
4134 return false;
4135 }
4136
4137 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4138
4139 oop obj = (oop)r->bottom();
4140 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4141
4142 // The following checks whether the humongous object is live are sufficient.
4143 // The main additional check (in addition to having a reference from the roots
4144 // or the young gen) is whether the humongous object has a remembered set entry.
4145 //
4146 // A humongous object cannot be live if there is no remembered set for it
4147 // because:
4148 // - there can be no references from within humongous starts regions referencing
4149 // the object because we never allocate other objects into them.
4150 // (I.e. there are no intra-region references that may be missed by the
4151 // remembered set)
4152 // - as soon there is a remembered set entry to the humongous starts region
4153 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4154 // until the end of a concurrent mark.
4155 //
4156 // It is not required to check whether the object has been found dead by marking
4157 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4158 // all objects allocated during that time are considered live.
4159 // SATB marking is even more conservative than the remembered set.
4160 // So if at this point in the collection there is no remembered set entry,
4161 // nobody has a reference to it.
4162 // At the start of collection we flush all refinement logs, and remembered sets
4163 // are completely up-to-date wrt to references to the humongous object.
4164 //
4165 // Other implementation considerations:
4166 // - never consider object arrays at this time because they would pose
4167 // considerable effort for cleaning up the the remembered sets. This is
4168 // required because stale remembered sets might reference locations that
4169 // are currently allocated into.
4170 uint region_idx = r->hrm_index();
4171 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4172 !r->rem_set()->is_empty()) {
4173 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",
4174 region_idx,
4175 (size_t)obj->size() * HeapWordSize,
4176 p2i(r->bottom()),
4177 r->rem_set()->occupied(),
4178 r->rem_set()->strong_code_roots_list_length(),
4179 next_bitmap->is_marked(r->bottom()),
4180 g1h->is_humongous_reclaim_candidate(region_idx),
4181 obj->is_typeArray()
4182 );
4183 return false;
4184 }
4185
4186 guarantee(obj->is_typeArray(),
4187 "Only eagerly reclaiming type arrays is supported, but the object "
4188 PTR_FORMAT " is not.", p2i(r->bottom()));
4189
4190 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",
4191 region_idx,
4192 (size_t)obj->size() * HeapWordSize,
4193 p2i(r->bottom()),
4194 r->rem_set()->occupied(),
4195 r->rem_set()->strong_code_roots_list_length(),
4196 next_bitmap->is_marked(r->bottom()),
4197 g1h->is_humongous_reclaim_candidate(region_idx),
4198 obj->is_typeArray()
4199 );
4200
4201 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4202 cm->humongous_object_eagerly_reclaimed(r);
4203 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4204 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4205 region_idx,
4206 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4207 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4208 _humongous_objects_reclaimed++;
4209 do {
4210 HeapRegion* next = g1h->next_region_in_humongous(r);
4211 _freed_bytes += r->used();
4212 r->set_containing_set(NULL);
4213 _humongous_regions_reclaimed++;
4214 g1h->free_humongous_region(r, _free_region_list);
4215 r = next;
4216 } while (r != NULL);
4217
4218 return false;
4219 }
4220
4221 uint humongous_objects_reclaimed() {
4222 return _humongous_objects_reclaimed;
4223 }
4224
4225 uint humongous_regions_reclaimed() {
4226 return _humongous_regions_reclaimed;
4227 }
4228
4229 size_t bytes_freed() const {
4230 return _freed_bytes;
4231 }
4232 };
4233
4234 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4235 assert_at_safepoint_on_vm_thread();
4236
4237 if (!G1EagerReclaimHumongousObjects ||
4238 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4239 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4240 return;
4241 }
4242
4243 double start_time = os::elapsedTime();
4244
4245 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4246
4247 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4248 heap_region_iterate(&cl);
4249
4250 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4251
4252 G1HRPrinter* hrp = hr_printer();
4253 if (hrp->is_active()) {
4254 FreeRegionListIterator iter(&local_cleanup_list);
4255 while (iter.more_available()) {
4256 HeapRegion* hr = iter.get_next();
4257 hrp->cleanup(hr);
4258 }
4259 }
4260
4261 prepend_to_freelist(&local_cleanup_list);
4262 decrement_summary_bytes(cl.bytes_freed());
4263
4264 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4265 cl.humongous_objects_reclaimed());
4266 }
4267
4268 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4269 public:
4270 virtual bool do_heap_region(HeapRegion* r) {
4271 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4272 G1CollectedHeap::heap()->clear_in_cset(r);
4273 r->set_young_index_in_cset(-1);
4274 return false;
4275 }
4276 };
4277
4278 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4279 G1AbandonCollectionSetClosure cl;
4280 collection_set->iterate(&cl);
4281
4282 collection_set->clear();
4283 collection_set->stop_incremental_building();
4284 }
4285
4286 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4287 return _allocator->is_retained_old_region(hr);
4288 }
4289
4290 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4291 _eden.add(hr);
4292 _g1_policy->set_region_eden(hr);
4293 }
4294
4295 #ifdef ASSERT
4296
4297 class NoYoungRegionsClosure: public HeapRegionClosure {
4298 private:
4299 bool _success;
4300 public:
4301 NoYoungRegionsClosure() : _success(true) { }
4302 bool do_heap_region(HeapRegion* r) {
4303 if (r->is_young()) {
4304 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4305 p2i(r->bottom()), p2i(r->end()));
4306 _success = false;
4307 }
4308 return false;
4309 }
4310 bool success() { return _success; }
4311 };
4312
4313 bool G1CollectedHeap::check_young_list_empty() {
4314 bool ret = (young_regions_count() == 0);
4315
4316 NoYoungRegionsClosure closure;
4317 heap_region_iterate(&closure);
4318 ret = ret && closure.success();
4319
4320 return ret;
4321 }
4322
4323 #endif // ASSERT
4324
4325 class TearDownRegionSetsClosure : public HeapRegionClosure {
4326 HeapRegionSet *_old_set;
4327
4328 public:
4329 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4330
4331 bool do_heap_region(HeapRegion* r) {
4332 if (r->is_old()) {
4333 _old_set->remove(r);
4334 } else if(r->is_young()) {
4335 r->uninstall_surv_rate_group();
4336 } else {
4337 // We ignore free regions, we'll empty the free list afterwards.
4338 // We ignore humongous and archive regions, we're not tearing down these
4339 // sets.
4340 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4341 "it cannot be another type");
4342 }
4343 return false;
4344 }
4345
4346 ~TearDownRegionSetsClosure() {
4347 assert(_old_set->is_empty(), "post-condition");
4348 }
4349 };
4350
4351 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4352 assert_at_safepoint_on_vm_thread();
4353
4354 if (!free_list_only) {
4355 TearDownRegionSetsClosure cl(&_old_set);
4356 heap_region_iterate(&cl);
4357
4358 // Note that emptying the _young_list is postponed and instead done as
4359 // the first step when rebuilding the regions sets again. The reason for
4360 // this is that during a full GC string deduplication needs to know if
4361 // a collected region was young or old when the full GC was initiated.
4362 }
4363 _hrm.remove_all_free_regions();
4364 }
4365
4366 void G1CollectedHeap::increase_used(size_t bytes) {
4367 _summary_bytes_used += bytes;
4368 }
4369
4370 void G1CollectedHeap::decrease_used(size_t bytes) {
4371 assert(_summary_bytes_used >= bytes,
4372 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4373 _summary_bytes_used, bytes);
4374 _summary_bytes_used -= bytes;
4375 }
4376
4377 void G1CollectedHeap::set_used(size_t bytes) {
4378 _summary_bytes_used = bytes;
4379 }
4380
4381 class RebuildRegionSetsClosure : public HeapRegionClosure {
4382 private:
4383 bool _free_list_only;
4384
4385 HeapRegionSet* _old_set;
4386 HeapRegionManager* _hrm;
4387
4388 size_t _total_used;
4389
4390 public:
4391 RebuildRegionSetsClosure(bool free_list_only,
4392 HeapRegionSet* old_set,
4393 HeapRegionManager* hrm) :
4394 _free_list_only(free_list_only),
4395 _old_set(old_set), _hrm(hrm), _total_used(0) {
4396 assert(_hrm->num_free_regions() == 0, "pre-condition");
4397 if (!free_list_only) {
4398 assert(_old_set->is_empty(), "pre-condition");
4399 }
4400 }
4401
4402 bool do_heap_region(HeapRegion* r) {
4403 if (r->is_empty()) {
4404 // Add free regions to the free list
4405 r->set_free();
4406 _hrm->insert_into_free_list(r);
4407 } else if (!_free_list_only) {
4408 // Only if we rebuild everything, clear remembered sets.
4409 r->rem_set()->clear(true);
4410
4411 if (r->is_archive() || r->is_humongous()) {
4412 // We ignore archive and humongous regions. We left these sets unchanged.
4413 } else {
4414 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4415 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4416 r->move_to_old();
4417 _old_set->add(r);
4418 }
4419 _total_used += r->used();
4420 }
4421
4422 return false;
4423 }
4424
4425 size_t total_used() {
4426 return _total_used;
4427 }
4428 };
4429
4430 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4431 assert_at_safepoint_on_vm_thread();
4432
4433 if (!free_list_only) {
4434 _eden.clear();
4435 _survivor.clear();
4436 }
4437
4438 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4439 heap_region_iterate(&cl);
4440
4441 if (!free_list_only) {
4442 set_used(cl.total_used());
4443 if (_archive_allocator != NULL) {
4444 _archive_allocator->clear_used();
4445 }
4446 }
4447 assert(used() == recalculate_used(),
4448 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4449 used(), recalculate_used());
4450 }
4451
4452 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4453 HeapRegion* hr = heap_region_containing(p);
4454 return hr->is_in(p);
4455 }
4456
4457 // Methods for the mutator alloc region
4458
4459 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4460 bool force) {
4461 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4462 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4463 if (force || should_allocate) {
4464 HeapRegion* new_alloc_region = new_region(word_size,
4465 false /* is_old */,
4466 false /* do_expand */);
4467 if (new_alloc_region != NULL) {
4468 set_region_short_lived_locked(new_alloc_region);
4469 _hr_printer.alloc(new_alloc_region, !should_allocate);
4470 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4471 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4472 return new_alloc_region;
4473 }
4474 }
4475 return NULL;
4476 }
4477
4478 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4479 size_t allocated_bytes) {
4480 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4481 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4482
4483 collection_set()->add_eden_region(alloc_region);
4484 increase_used(allocated_bytes);
4485 _hr_printer.retire(alloc_region);
4486 // We update the eden sizes here, when the region is retired,
4487 // instead of when it's allocated, since this is the point that its
4488 // used space has been recorded in _summary_bytes_used.
4489 g1mm()->update_eden_size();
4490 }
4491
4492 // Methods for the GC alloc regions
4493
4494 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4495 if (dest.is_old()) {
4496 return true;
4497 } else {
4498 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4499 }
4500 }
4501
4502 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4503 assert(FreeList_lock->owned_by_self(), "pre-condition");
4504
4505 if (!has_more_regions(dest)) {
4506 return NULL;
4507 }
4508
4509 const bool is_survivor = dest.is_young();
4510
4511 HeapRegion* new_alloc_region = new_region(word_size,
4512 !is_survivor,
4513 true /* do_expand */);
4514 if (new_alloc_region != NULL) {
4515 if (is_survivor) {
4516 new_alloc_region->set_survivor();
4517 _survivor.add(new_alloc_region);
4518 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4519 } else {
4520 new_alloc_region->set_old();
4521 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4522 }
4523 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4524 _hr_printer.alloc(new_alloc_region);
4525 bool during_im = collector_state()->in_initial_mark_gc();
4526 new_alloc_region->note_start_of_copying(during_im);
4527 return new_alloc_region;
4528 }
4529 return NULL;
4530 }
4531
4532 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4533 size_t allocated_bytes,
4534 InCSetState dest) {
4535 bool during_im = collector_state()->in_initial_mark_gc();
4536 alloc_region->note_end_of_copying(during_im);
4537 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4538 if (dest.is_old()) {
4539 old_set_add(alloc_region);
4540 }
4541 _hr_printer.retire(alloc_region);
4542 }
4543
4544 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4545 bool expanded = false;
4546 uint index = _hrm.find_highest_free(&expanded);
4547
4548 if (index != G1_NO_HRM_INDEX) {
4549 if (expanded) {
4550 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4551 HeapRegion::GrainWords * HeapWordSize);
4552 }
4553 _hrm.allocate_free_regions_starting_at(index, 1);
4554 return region_at(index);
4555 }
4556 return NULL;
4557 }
4558
4559 // Optimized nmethod scanning
4560
4561 class RegisterNMethodOopClosure: public OopClosure {
4562 G1CollectedHeap* _g1h;
4563 nmethod* _nm;
4564
4565 template <class T> void do_oop_work(T* p) {
4566 T heap_oop = RawAccess<>::oop_load(p);
4567 if (!CompressedOops::is_null(heap_oop)) {
4568 oop obj = CompressedOops::decode_not_null(heap_oop);
4569 HeapRegion* hr = _g1h->heap_region_containing(obj);
4570 assert(!hr->is_continues_humongous(),
4571 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4572 " starting at " HR_FORMAT,
4573 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4574
4575 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4576 hr->add_strong_code_root_locked(_nm);
4577 }
4578 }
4579
4580 public:
4581 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4582 _g1h(g1h), _nm(nm) {}
4583
4584 void do_oop(oop* p) { do_oop_work(p); }
4585 void do_oop(narrowOop* p) { do_oop_work(p); }
4586 };
4587
4588 class UnregisterNMethodOopClosure: public OopClosure {
4589 G1CollectedHeap* _g1h;
4590 nmethod* _nm;
4591
4592 template <class T> void do_oop_work(T* p) {
4593 T heap_oop = RawAccess<>::oop_load(p);
4594 if (!CompressedOops::is_null(heap_oop)) {
4595 oop obj = CompressedOops::decode_not_null(heap_oop);
4596 HeapRegion* hr = _g1h->heap_region_containing(obj);
4597 assert(!hr->is_continues_humongous(),
4598 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4599 " starting at " HR_FORMAT,
4600 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4601
4602 hr->remove_strong_code_root(_nm);
4603 }
4604 }
4605
4606 public:
4607 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4608 _g1h(g1h), _nm(nm) {}
4609
4610 void do_oop(oop* p) { do_oop_work(p); }
4611 void do_oop(narrowOop* p) { do_oop_work(p); }
4612 };
4613
4614 // Returns true if the reference points to an object that
4615 // can move in an incremental collection.
4616 bool G1CollectedHeap::is_scavengable(oop obj) {
4617 HeapRegion* hr = heap_region_containing(obj);
4618 return !hr->is_pinned();
4619 }
4620
4621 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4622 guarantee(nm != NULL, "sanity");
4623 RegisterNMethodOopClosure reg_cl(this, nm);
4624 nm->oops_do(®_cl);
4625 }
4626
4627 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4628 guarantee(nm != NULL, "sanity");
4629 UnregisterNMethodOopClosure reg_cl(this, nm);
4630 nm->oops_do(®_cl, true);
4631 }
4632
4633 void G1CollectedHeap::purge_code_root_memory() {
4634 double purge_start = os::elapsedTime();
4635 G1CodeRootSet::purge();
4636 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4637 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4638 }
4639
4640 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4641 G1CollectedHeap* _g1h;
4642
4643 public:
4644 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4645 _g1h(g1h) {}
4646
4647 void do_code_blob(CodeBlob* cb) {
4648 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4649 if (nm == NULL) {
4650 return;
4651 }
4652
4653 if (ScavengeRootsInCode) {
4654 _g1h->register_nmethod(nm);
4655 }
4656 }
4657 };
4658
4659 void G1CollectedHeap::rebuild_strong_code_roots() {
4660 RebuildStrongCodeRootClosure blob_cl(this);
4661 CodeCache::blobs_do(&blob_cl);
4662 }
4663
4664 void G1CollectedHeap::initialize_serviceability() {
4665 _g1mm->initialize_serviceability();
4666 }
4667
4668 MemoryUsage G1CollectedHeap::memory_usage() {
4669 return _g1mm->memory_usage();
4670 }
4671
4672 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4673 return _g1mm->memory_managers();
4674 }
4675
4676 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4677 return _g1mm->memory_pools();
4678 }