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 // Capacity, free and used after the GC counted as full regions to
1154 // include the waste in the following calculations.
1155 const size_t capacity_after_gc = capacity();
1156 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1157
1158 // This is enforced in arguments.cpp.
1159 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1160 "otherwise the code below doesn't make sense");
1161
1162 // We don't have floating point command-line arguments
1163 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1164 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1165 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1166 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1167
1168 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1169 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1170
1171 // We have to be careful here as these two calculations can overflow
1172 // 32-bit size_t's.
1173 double used_after_gc_d = (double) used_after_gc;
1174 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1175 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1176
1177 // Let's make sure that they are both under the max heap size, which
1178 // by default will make them fit into a size_t.
1179 double desired_capacity_upper_bound = (double) max_heap_size;
1180 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1181 desired_capacity_upper_bound);
1182 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1183 desired_capacity_upper_bound);
1184
1185 // We can now safely turn them into size_t's.
1186 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1187 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1188
1189 // This assert only makes sense here, before we adjust them
1190 // with respect to the min and max heap size.
1191 assert(minimum_desired_capacity <= maximum_desired_capacity,
1192 "minimum_desired_capacity = " SIZE_FORMAT ", "
1193 "maximum_desired_capacity = " SIZE_FORMAT,
1194 minimum_desired_capacity, maximum_desired_capacity);
1195
1196 // Should not be greater than the heap max size. No need to adjust
1197 // it with respect to the heap min size as it's a lower bound (i.e.,
1198 // we'll try to make the capacity larger than it, not smaller).
1199 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1200 // Should not be less than the heap min size. No need to adjust it
1201 // with respect to the heap max size as it's an upper bound (i.e.,
1202 // we'll try to make the capacity smaller than it, not greater).
1203 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1204
1205 if (capacity_after_gc < minimum_desired_capacity) {
1206 // Don't expand unless it's significant
1207 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1208
1209 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1210 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1211 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1212 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1213
1214 expand(expand_bytes, _workers);
1215
1216 // No expansion, now see if we want to shrink
1217 } else if (capacity_after_gc > maximum_desired_capacity) {
1218 // Capacity too large, compute shrinking size
1219 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1220
1221 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1222 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1223 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1224 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1225
1226 shrink(shrink_bytes);
1227 }
1228 }
1229
1230 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1231 bool do_gc,
1232 bool clear_all_soft_refs,
1233 bool expect_null_mutator_alloc_region,
1234 bool* gc_succeeded) {
1235 *gc_succeeded = true;
1236 // Let's attempt the allocation first.
1237 HeapWord* result =
1238 attempt_allocation_at_safepoint(word_size,
1239 expect_null_mutator_alloc_region);
1240 if (result != NULL) {
1241 return result;
1242 }
1243
1244 // In a G1 heap, we're supposed to keep allocation from failing by
1245 // incremental pauses. Therefore, at least for now, we'll favor
1246 // expansion over collection. (This might change in the future if we can
1247 // do something smarter than full collection to satisfy a failed alloc.)
1248 result = expand_and_allocate(word_size);
1249 if (result != NULL) {
1250 return result;
1251 }
1252
1253 if (do_gc) {
1254 // Expansion didn't work, we'll try to do a Full GC.
1255 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1256 clear_all_soft_refs);
1257 }
1258
1259 return NULL;
1260 }
1261
1262 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1263 bool* succeeded) {
1264 assert_at_safepoint_on_vm_thread();
1265
1266 // Attempts to allocate followed by Full GC.
1267 HeapWord* result =
1268 satisfy_failed_allocation_helper(word_size,
1269 true, /* do_gc */
1270 false, /* clear_all_soft_refs */
1271 false, /* expect_null_mutator_alloc_region */
1272 succeeded);
1273
1274 if (result != NULL || !*succeeded) {
1275 return result;
1276 }
1277
1278 // Attempts to allocate followed by Full GC that will collect all soft references.
1279 result = satisfy_failed_allocation_helper(word_size,
1280 true, /* do_gc */
1281 true, /* clear_all_soft_refs */
1282 true, /* expect_null_mutator_alloc_region */
1283 succeeded);
1284
1285 if (result != NULL || !*succeeded) {
1286 return result;
1287 }
1288
1289 // Attempts to allocate, no GC
1290 result = satisfy_failed_allocation_helper(word_size,
1291 false, /* do_gc */
1292 false, /* clear_all_soft_refs */
1293 true, /* expect_null_mutator_alloc_region */
1294 succeeded);
1295
1296 if (result != NULL) {
1297 return result;
1298 }
1299
1300 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1301 "Flag should have been handled and cleared prior to this point");
1302
1303 // What else? We might try synchronous finalization later. If the total
1304 // space available is large enough for the allocation, then a more
1305 // complete compaction phase than we've tried so far might be
1306 // appropriate.
1307 return NULL;
1308 }
1309
1310 // Attempting to expand the heap sufficiently
1311 // to support an allocation of the given "word_size". If
1312 // successful, perform the allocation and return the address of the
1313 // allocated block, or else "NULL".
1314
1315 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1316 assert_at_safepoint_on_vm_thread();
1317
1318 _verifier->verify_region_sets_optional();
1319
1320 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1321 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1322 word_size * HeapWordSize);
1323
1324
1325 if (expand(expand_bytes, _workers)) {
1326 _hrm.verify_optional();
1327 _verifier->verify_region_sets_optional();
1328 return attempt_allocation_at_safepoint(word_size,
1329 false /* expect_null_mutator_alloc_region */);
1330 }
1331 return NULL;
1332 }
1333
1334 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1335 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1336 aligned_expand_bytes = align_up(aligned_expand_bytes,
1337 HeapRegion::GrainBytes);
1338
1339 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1340 expand_bytes, aligned_expand_bytes);
1341
1342 if (is_maximal_no_gc()) {
1343 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1344 return false;
1345 }
1346
1347 double expand_heap_start_time_sec = os::elapsedTime();
1348 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1349 assert(regions_to_expand > 0, "Must expand by at least one region");
1350
1351 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1352 if (expand_time_ms != NULL) {
1353 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1354 }
1355
1356 if (expanded_by > 0) {
1357 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1358 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1359 g1_policy()->record_new_heap_size(num_regions());
1360 } else {
1361 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1362
1363 // The expansion of the virtual storage space was unsuccessful.
1364 // Let's see if it was because we ran out of swap.
1365 if (G1ExitOnExpansionFailure &&
1366 _hrm.available() >= regions_to_expand) {
1367 // We had head room...
1368 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1369 }
1370 }
1371 return regions_to_expand > 0;
1372 }
1373
1374 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1375 size_t aligned_shrink_bytes =
1376 ReservedSpace::page_align_size_down(shrink_bytes);
1377 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1378 HeapRegion::GrainBytes);
1379 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1380
1381 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1382 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1383
1384
1385 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",
1386 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1387 if (num_regions_removed > 0) {
1388 g1_policy()->record_new_heap_size(num_regions());
1389 } else {
1390 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1391 }
1392 }
1393
1394 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1395 _verifier->verify_region_sets_optional();
1396
1397 // We should only reach here at the end of a Full GC or during Remark which
1398 // means we should not not be holding to any GC alloc regions. The method
1399 // below will make sure of that and do any remaining clean up.
1400 _allocator->abandon_gc_alloc_regions();
1401
1402 // Instead of tearing down / rebuilding the free lists here, we
1403 // could instead use the remove_all_pending() method on free_list to
1404 // remove only the ones that we need to remove.
1405 tear_down_region_sets(true /* free_list_only */);
1406 shrink_helper(shrink_bytes);
1407 rebuild_region_sets(true /* free_list_only */);
1408
1409 _hrm.verify_optional();
1410 _verifier->verify_region_sets_optional();
1411 }
1412
1413 class OldRegionSetChecker : public HeapRegionSetChecker {
1414 public:
1415 void check_mt_safety() {
1416 // Master Old Set MT safety protocol:
1417 // (a) If we're at a safepoint, operations on the master old set
1418 // should be invoked:
1419 // - by the VM thread (which will serialize them), or
1420 // - by the GC workers while holding the FreeList_lock, if we're
1421 // at a safepoint for an evacuation pause (this lock is taken
1422 // anyway when an GC alloc region is retired so that a new one
1423 // is allocated from the free list), or
1424 // - by the GC workers while holding the OldSets_lock, if we're at a
1425 // safepoint for a cleanup pause.
1426 // (b) If we're not at a safepoint, operations on the master old set
1427 // should be invoked while holding the Heap_lock.
1428
1429 if (SafepointSynchronize::is_at_safepoint()) {
1430 guarantee(Thread::current()->is_VM_thread() ||
1431 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1432 "master old set MT safety protocol at a safepoint");
1433 } else {
1434 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1435 }
1436 }
1437 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1438 const char* get_description() { return "Old Regions"; }
1439 };
1440
1441 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1442 public:
1443 void check_mt_safety() {
1444 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1445 "May only change archive regions during initialization or safepoint.");
1446 }
1447 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1448 const char* get_description() { return "Archive Regions"; }
1449 };
1450
1451 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1452 public:
1453 void check_mt_safety() {
1454 // Humongous Set MT safety protocol:
1455 // (a) If we're at a safepoint, operations on the master humongous
1456 // set should be invoked by either the VM thread (which will
1457 // serialize them) or by the GC workers while holding the
1458 // OldSets_lock.
1459 // (b) If we're not at a safepoint, operations on the master
1460 // humongous set should be invoked while holding the Heap_lock.
1461
1462 if (SafepointSynchronize::is_at_safepoint()) {
1463 guarantee(Thread::current()->is_VM_thread() ||
1464 OldSets_lock->owned_by_self(),
1465 "master humongous set MT safety protocol at a safepoint");
1466 } else {
1467 guarantee(Heap_lock->owned_by_self(),
1468 "master humongous set MT safety protocol outside a safepoint");
1469 }
1470 }
1471 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1472 const char* get_description() { return "Humongous Regions"; }
1473 };
1474
1475 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1476 CollectedHeap(),
1477 _young_gen_sampling_thread(NULL),
1478 _workers(NULL),
1479 _collector_policy(collector_policy),
1480 _card_table(NULL),
1481 _soft_ref_policy(),
1482 _old_set("Old Region Set", new OldRegionSetChecker()),
1483 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1484 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1485 _bot(NULL),
1486 _listener(),
1487 _hrm(),
1488 _allocator(NULL),
1489 _verifier(NULL),
1490 _summary_bytes_used(0),
1491 _archive_allocator(NULL),
1492 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1493 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1494 _expand_heap_after_alloc_failure(true),
1495 _g1mm(NULL),
1496 _humongous_reclaim_candidates(),
1497 _has_humongous_reclaim_candidates(false),
1498 _hr_printer(),
1499 _collector_state(),
1500 _old_marking_cycles_started(0),
1501 _old_marking_cycles_completed(0),
1502 _eden(),
1503 _survivor(),
1504 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1505 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1506 _g1_policy(new G1Policy(_gc_timer_stw)),
1507 _heap_sizing_policy(NULL),
1508 _collection_set(this, _g1_policy),
1509 _hot_card_cache(NULL),
1510 _g1_rem_set(NULL),
1511 _dirty_card_queue_set(false),
1512 _cm(NULL),
1513 _cm_thread(NULL),
1514 _cr(NULL),
1515 _task_queues(NULL),
1516 _evacuation_failed(false),
1517 _evacuation_failed_info_array(NULL),
1518 _preserved_marks_set(true /* in_c_heap */),
1519 #ifndef PRODUCT
1520 _evacuation_failure_alot_for_current_gc(false),
1521 _evacuation_failure_alot_gc_number(0),
1522 _evacuation_failure_alot_count(0),
1523 #endif
1524 _ref_processor_stw(NULL),
1525 _is_alive_closure_stw(this),
1526 _is_subject_to_discovery_stw(this),
1527 _ref_processor_cm(NULL),
1528 _is_alive_closure_cm(this),
1529 _is_subject_to_discovery_cm(this),
1530 _in_cset_fast_test() {
1531
1532 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1533 true /* are_GC_task_threads */,
1534 false /* are_ConcurrentGC_threads */);
1535 _workers->initialize_workers();
1536 _verifier = new G1HeapVerifier(this);
1537
1538 _allocator = new G1Allocator(this);
1539
1540 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1541
1542 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1543
1544 // Override the default _filler_array_max_size so that no humongous filler
1545 // objects are created.
1546 _filler_array_max_size = _humongous_object_threshold_in_words;
1547
1548 uint n_queues = ParallelGCThreads;
1549 _task_queues = new RefToScanQueueSet(n_queues);
1550
1551 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1552
1553 for (uint i = 0; i < n_queues; i++) {
1554 RefToScanQueue* q = new RefToScanQueue();
1555 q->initialize();
1556 _task_queues->register_queue(i, q);
1557 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1558 }
1559
1560 // Initialize the G1EvacuationFailureALot counters and flags.
1561 NOT_PRODUCT(reset_evacuation_should_fail();)
1562
1563 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1564 }
1565
1566 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1567 size_t size,
1568 size_t translation_factor) {
1569 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1570 // Allocate a new reserved space, preferring to use large pages.
1571 ReservedSpace rs(size, preferred_page_size);
1572 G1RegionToSpaceMapper* result =
1573 G1RegionToSpaceMapper::create_mapper(rs,
1574 size,
1575 rs.alignment(),
1576 HeapRegion::GrainBytes,
1577 translation_factor,
1578 mtGC);
1579
1580 os::trace_page_sizes_for_requested_size(description,
1581 size,
1582 preferred_page_size,
1583 rs.alignment(),
1584 rs.base(),
1585 rs.size());
1586
1587 return result;
1588 }
1589
1590 jint G1CollectedHeap::initialize_concurrent_refinement() {
1591 jint ecode = JNI_OK;
1592 _cr = G1ConcurrentRefine::create(&ecode);
1593 return ecode;
1594 }
1595
1596 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1597 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1598 if (_young_gen_sampling_thread->osthread() == NULL) {
1599 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1600 return JNI_ENOMEM;
1601 }
1602 return JNI_OK;
1603 }
1604
1605 jint G1CollectedHeap::initialize() {
1606 os::enable_vtime();
1607
1608 // Necessary to satisfy locking discipline assertions.
1609
1610 MutexLocker x(Heap_lock);
1611
1612 // While there are no constraints in the GC code that HeapWordSize
1613 // be any particular value, there are multiple other areas in the
1614 // system which believe this to be true (e.g. oop->object_size in some
1615 // cases incorrectly returns the size in wordSize units rather than
1616 // HeapWordSize).
1617 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1618
1619 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1620 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1621 size_t heap_alignment = collector_policy()->heap_alignment();
1622
1623 // Ensure that the sizes are properly aligned.
1624 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1625 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1626 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1627
1628 // Reserve the maximum.
1629
1630 // When compressed oops are enabled, the preferred heap base
1631 // is calculated by subtracting the requested size from the
1632 // 32Gb boundary and using the result as the base address for
1633 // heap reservation. If the requested size is not aligned to
1634 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1635 // into the ReservedHeapSpace constructor) then the actual
1636 // base of the reserved heap may end up differing from the
1637 // address that was requested (i.e. the preferred heap base).
1638 // If this happens then we could end up using a non-optimal
1639 // compressed oops mode.
1640
1641 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1642 heap_alignment);
1643
1644 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1645
1646 // Create the barrier set for the entire reserved region.
1647 G1CardTable* ct = new G1CardTable(reserved_region());
1648 ct->initialize();
1649 G1BarrierSet* bs = new G1BarrierSet(ct);
1650 bs->initialize();
1651 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1652 BarrierSet::set_barrier_set(bs);
1653 _card_table = ct;
1654
1655 // Create the hot card cache.
1656 _hot_card_cache = new G1HotCardCache(this);
1657
1658 // Carve out the G1 part of the heap.
1659 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1660 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1661 G1RegionToSpaceMapper* heap_storage =
1662 G1RegionToSpaceMapper::create_mapper(g1_rs,
1663 g1_rs.size(),
1664 page_size,
1665 HeapRegion::GrainBytes,
1666 1,
1667 mtJavaHeap);
1668 os::trace_page_sizes("Heap",
1669 collector_policy()->min_heap_byte_size(),
1670 max_byte_size,
1671 page_size,
1672 heap_rs.base(),
1673 heap_rs.size());
1674 heap_storage->set_mapping_changed_listener(&_listener);
1675
1676 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1677 G1RegionToSpaceMapper* bot_storage =
1678 create_aux_memory_mapper("Block Offset Table",
1679 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1680 G1BlockOffsetTable::heap_map_factor());
1681
1682 G1RegionToSpaceMapper* cardtable_storage =
1683 create_aux_memory_mapper("Card Table",
1684 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1685 G1CardTable::heap_map_factor());
1686
1687 G1RegionToSpaceMapper* card_counts_storage =
1688 create_aux_memory_mapper("Card Counts Table",
1689 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1690 G1CardCounts::heap_map_factor());
1691
1692 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1693 G1RegionToSpaceMapper* prev_bitmap_storage =
1694 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1695 G1RegionToSpaceMapper* next_bitmap_storage =
1696 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1697
1698 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1699 _card_table->initialize(cardtable_storage);
1700 // Do later initialization work for concurrent refinement.
1701 _hot_card_cache->initialize(card_counts_storage);
1702
1703 // 6843694 - ensure that the maximum region index can fit
1704 // in the remembered set structures.
1705 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1706 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1707
1708 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1709 // start within the first card.
1710 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1711 // Also create a G1 rem set.
1712 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1713 _g1_rem_set->initialize(max_capacity(), max_regions());
1714
1715 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1716 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1717 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1718 "too many cards per region");
1719
1720 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1721
1722 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1723
1724 {
1725 HeapWord* start = _hrm.reserved().start();
1726 HeapWord* end = _hrm.reserved().end();
1727 size_t granularity = HeapRegion::GrainBytes;
1728
1729 _in_cset_fast_test.initialize(start, end, granularity);
1730 _humongous_reclaim_candidates.initialize(start, end, granularity);
1731 }
1732
1733 // Create the G1ConcurrentMark data structure and thread.
1734 // (Must do this late, so that "max_regions" is defined.)
1735 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1736 if (_cm == NULL || !_cm->completed_initialization()) {
1737 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1738 return JNI_ENOMEM;
1739 }
1740 _cm_thread = _cm->cm_thread();
1741
1742 // Now expand into the initial heap size.
1743 if (!expand(init_byte_size, _workers)) {
1744 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1745 return JNI_ENOMEM;
1746 }
1747
1748 // Perform any initialization actions delegated to the policy.
1749 g1_policy()->init(this, &_collection_set);
1750
1751 G1BarrierSet::satb_mark_queue_set().initialize(this,
1752 SATB_Q_CBL_mon,
1753 SATB_Q_FL_lock,
1754 G1SATBProcessCompletedThreshold,
1755 G1SATBBufferEnqueueingThresholdPercent,
1756 Shared_SATB_Q_lock);
1757
1758 jint ecode = initialize_concurrent_refinement();
1759 if (ecode != JNI_OK) {
1760 return ecode;
1761 }
1762
1763 ecode = initialize_young_gen_sampling_thread();
1764 if (ecode != JNI_OK) {
1765 return ecode;
1766 }
1767
1768 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1769 DirtyCardQ_FL_lock,
1770 (int)concurrent_refine()->yellow_zone(),
1771 (int)concurrent_refine()->red_zone(),
1772 Shared_DirtyCardQ_lock,
1773 NULL, // fl_owner
1774 true); // init_free_ids
1775
1776 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1777 DirtyCardQ_FL_lock,
1778 -1, // never trigger processing
1779 -1, // no limit on length
1780 Shared_DirtyCardQ_lock,
1781 &G1BarrierSet::dirty_card_queue_set());
1782
1783 // Here we allocate the dummy HeapRegion that is required by the
1784 // G1AllocRegion class.
1785 HeapRegion* dummy_region = _hrm.get_dummy_region();
1786
1787 // We'll re-use the same region whether the alloc region will
1788 // require BOT updates or not and, if it doesn't, then a non-young
1789 // region will complain that it cannot support allocations without
1790 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1791 dummy_region->set_eden();
1792 // Make sure it's full.
1793 dummy_region->set_top(dummy_region->end());
1794 G1AllocRegion::setup(this, dummy_region);
1795
1796 _allocator->init_mutator_alloc_region();
1797
1798 // Do create of the monitoring and management support so that
1799 // values in the heap have been properly initialized.
1800 _g1mm = new G1MonitoringSupport(this);
1801
1802 G1StringDedup::initialize();
1803
1804 _preserved_marks_set.init(ParallelGCThreads);
1805
1806 _collection_set.initialize(max_regions());
1807
1808 return JNI_OK;
1809 }
1810
1811 void G1CollectedHeap::stop() {
1812 // Stop all concurrent threads. We do this to make sure these threads
1813 // do not continue to execute and access resources (e.g. logging)
1814 // that are destroyed during shutdown.
1815 _cr->stop();
1816 _young_gen_sampling_thread->stop();
1817 _cm_thread->stop();
1818 if (G1StringDedup::is_enabled()) {
1819 G1StringDedup::stop();
1820 }
1821 }
1822
1823 void G1CollectedHeap::safepoint_synchronize_begin() {
1824 SuspendibleThreadSet::synchronize();
1825 }
1826
1827 void G1CollectedHeap::safepoint_synchronize_end() {
1828 SuspendibleThreadSet::desynchronize();
1829 }
1830
1831 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1832 return HeapRegion::max_region_size();
1833 }
1834
1835 void G1CollectedHeap::post_initialize() {
1836 CollectedHeap::post_initialize();
1837 ref_processing_init();
1838 }
1839
1840 void G1CollectedHeap::ref_processing_init() {
1841 // Reference processing in G1 currently works as follows:
1842 //
1843 // * There are two reference processor instances. One is
1844 // used to record and process discovered references
1845 // during concurrent marking; the other is used to
1846 // record and process references during STW pauses
1847 // (both full and incremental).
1848 // * Both ref processors need to 'span' the entire heap as
1849 // the regions in the collection set may be dotted around.
1850 //
1851 // * For the concurrent marking ref processor:
1852 // * Reference discovery is enabled at initial marking.
1853 // * Reference discovery is disabled and the discovered
1854 // references processed etc during remarking.
1855 // * Reference discovery is MT (see below).
1856 // * Reference discovery requires a barrier (see below).
1857 // * Reference processing may or may not be MT
1858 // (depending on the value of ParallelRefProcEnabled
1859 // and ParallelGCThreads).
1860 // * A full GC disables reference discovery by the CM
1861 // ref processor and abandons any entries on it's
1862 // discovered lists.
1863 //
1864 // * For the STW processor:
1865 // * Non MT discovery is enabled at the start of a full GC.
1866 // * Processing and enqueueing during a full GC is non-MT.
1867 // * During a full GC, references are processed after marking.
1868 //
1869 // * Discovery (may or may not be MT) is enabled at the start
1870 // of an incremental evacuation pause.
1871 // * References are processed near the end of a STW evacuation pause.
1872 // * For both types of GC:
1873 // * Discovery is atomic - i.e. not concurrent.
1874 // * Reference discovery will not need a barrier.
1875
1876 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1877
1878 // Concurrent Mark ref processor
1879 _ref_processor_cm =
1880 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1881 mt_processing, // mt processing
1882 ParallelGCThreads, // degree of mt processing
1883 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1884 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1885 false, // Reference discovery is not atomic
1886 &_is_alive_closure_cm, // is alive closure
1887 true); // allow changes to number of processing threads
1888
1889 // STW ref processor
1890 _ref_processor_stw =
1891 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1892 mt_processing, // mt processing
1893 ParallelGCThreads, // degree of mt processing
1894 (ParallelGCThreads > 1), // mt discovery
1895 ParallelGCThreads, // degree of mt discovery
1896 true, // Reference discovery is atomic
1897 &_is_alive_closure_stw, // is alive closure
1898 true); // allow changes to number of processing threads
1899 }
1900
1901 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1902 return _collector_policy;
1903 }
1904
1905 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1906 return &_soft_ref_policy;
1907 }
1908
1909 size_t G1CollectedHeap::capacity() const {
1910 return _hrm.length() * HeapRegion::GrainBytes;
1911 }
1912
1913 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1914 return _hrm.total_free_bytes();
1915 }
1916
1917 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1918 _hot_card_cache->drain(cl, worker_i);
1919 }
1920
1921 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1922 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1923 size_t n_completed_buffers = 0;
1924 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1925 n_completed_buffers++;
1926 }
1927 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1928 dcqs.clear_n_completed_buffers();
1929 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1930 }
1931
1932 // Computes the sum of the storage used by the various regions.
1933 size_t G1CollectedHeap::used() const {
1934 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1935 if (_archive_allocator != NULL) {
1936 result += _archive_allocator->used();
1937 }
1938 return result;
1939 }
1940
1941 size_t G1CollectedHeap::used_unlocked() const {
1942 return _summary_bytes_used;
1943 }
1944
1945 class SumUsedClosure: public HeapRegionClosure {
1946 size_t _used;
1947 public:
1948 SumUsedClosure() : _used(0) {}
1949 bool do_heap_region(HeapRegion* r) {
1950 _used += r->used();
1951 return false;
1952 }
1953 size_t result() { return _used; }
1954 };
1955
1956 size_t G1CollectedHeap::recalculate_used() const {
1957 SumUsedClosure blk;
1958 heap_region_iterate(&blk);
1959 return blk.result();
1960 }
1961
1962 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1963 switch (cause) {
1964 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1965 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1966 case GCCause::_wb_conc_mark: return true;
1967 default : return false;
1968 }
1969 }
1970
1971 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1972 switch (cause) {
1973 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1974 case GCCause::_g1_humongous_allocation: return true;
1975 default: return is_user_requested_concurrent_full_gc(cause);
1976 }
1977 }
1978
1979 #ifndef PRODUCT
1980 void G1CollectedHeap::allocate_dummy_regions() {
1981 // Let's fill up most of the region
1982 size_t word_size = HeapRegion::GrainWords - 1024;
1983 // And as a result the region we'll allocate will be humongous.
1984 guarantee(is_humongous(word_size), "sanity");
1985
1986 // _filler_array_max_size is set to humongous object threshold
1987 // but temporarily change it to use CollectedHeap::fill_with_object().
1988 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1989
1990 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1991 // Let's use the existing mechanism for the allocation
1992 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1993 if (dummy_obj != NULL) {
1994 MemRegion mr(dummy_obj, word_size);
1995 CollectedHeap::fill_with_object(mr);
1996 } else {
1997 // If we can't allocate once, we probably cannot allocate
1998 // again. Let's get out of the loop.
1999 break;
2000 }
2001 }
2002 }
2003 #endif // !PRODUCT
2004
2005 void G1CollectedHeap::increment_old_marking_cycles_started() {
2006 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2007 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2008 "Wrong marking cycle count (started: %d, completed: %d)",
2009 _old_marking_cycles_started, _old_marking_cycles_completed);
2010
2011 _old_marking_cycles_started++;
2012 }
2013
2014 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2015 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2016
2017 // We assume that if concurrent == true, then the caller is a
2018 // concurrent thread that was joined the Suspendible Thread
2019 // Set. If there's ever a cheap way to check this, we should add an
2020 // assert here.
2021
2022 // Given that this method is called at the end of a Full GC or of a
2023 // concurrent cycle, and those can be nested (i.e., a Full GC can
2024 // interrupt a concurrent cycle), the number of full collections
2025 // completed should be either one (in the case where there was no
2026 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2027 // behind the number of full collections started.
2028
2029 // This is the case for the inner caller, i.e. a Full GC.
2030 assert(concurrent ||
2031 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2032 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2033 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2034 "is inconsistent with _old_marking_cycles_completed = %u",
2035 _old_marking_cycles_started, _old_marking_cycles_completed);
2036
2037 // This is the case for the outer caller, i.e. the concurrent cycle.
2038 assert(!concurrent ||
2039 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2040 "for outer caller (concurrent cycle): "
2041 "_old_marking_cycles_started = %u "
2042 "is inconsistent with _old_marking_cycles_completed = %u",
2043 _old_marking_cycles_started, _old_marking_cycles_completed);
2044
2045 _old_marking_cycles_completed += 1;
2046
2047 // We need to clear the "in_progress" flag in the CM thread before
2048 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2049 // is set) so that if a waiter requests another System.gc() it doesn't
2050 // incorrectly see that a marking cycle is still in progress.
2051 if (concurrent) {
2052 _cm_thread->set_idle();
2053 }
2054
2055 // This notify_all() will ensure that a thread that called
2056 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2057 // and it's waiting for a full GC to finish will be woken up. It is
2058 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2059 FullGCCount_lock->notify_all();
2060 }
2061
2062 void G1CollectedHeap::collect(GCCause::Cause cause) {
2063 assert_heap_not_locked();
2064
2065 uint gc_count_before;
2066 uint old_marking_count_before;
2067 uint full_gc_count_before;
2068 bool retry_gc;
2069
2070 do {
2071 retry_gc = false;
2072
2073 {
2074 MutexLocker ml(Heap_lock);
2075
2076 // Read the GC count while holding the Heap_lock
2077 gc_count_before = total_collections();
2078 full_gc_count_before = total_full_collections();
2079 old_marking_count_before = _old_marking_cycles_started;
2080 }
2081
2082 if (should_do_concurrent_full_gc(cause)) {
2083 // Schedule an initial-mark evacuation pause that will start a
2084 // concurrent cycle. We're setting word_size to 0 which means that
2085 // we are not requesting a post-GC allocation.
2086 VM_G1CollectForAllocation op(0, /* word_size */
2087 gc_count_before,
2088 cause,
2089 true, /* should_initiate_conc_mark */
2090 g1_policy()->max_pause_time_ms());
2091 VMThread::execute(&op);
2092 if (!op.pause_succeeded()) {
2093 if (old_marking_count_before == _old_marking_cycles_started) {
2094 retry_gc = op.should_retry_gc();
2095 } else {
2096 // A Full GC happened while we were trying to schedule the
2097 // initial-mark GC. No point in starting a new cycle given
2098 // that the whole heap was collected anyway.
2099 }
2100
2101 if (retry_gc) {
2102 if (GCLocker::is_active_and_needs_gc()) {
2103 GCLocker::stall_until_clear();
2104 }
2105 }
2106 }
2107 } else {
2108 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2109 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2110
2111 // Schedule a standard evacuation pause. We're setting word_size
2112 // to 0 which means that we are not requesting a post-GC allocation.
2113 VM_G1CollectForAllocation op(0, /* word_size */
2114 gc_count_before,
2115 cause,
2116 false, /* should_initiate_conc_mark */
2117 g1_policy()->max_pause_time_ms());
2118 VMThread::execute(&op);
2119 } else {
2120 // Schedule a Full GC.
2121 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2122 VMThread::execute(&op);
2123 }
2124 }
2125 } while (retry_gc);
2126 }
2127
2128 bool G1CollectedHeap::is_in(const void* p) const {
2129 if (_hrm.reserved().contains(p)) {
2130 // Given that we know that p is in the reserved space,
2131 // heap_region_containing() should successfully
2132 // return the containing region.
2133 HeapRegion* hr = heap_region_containing(p);
2134 return hr->is_in(p);
2135 } else {
2136 return false;
2137 }
2138 }
2139
2140 #ifdef ASSERT
2141 bool G1CollectedHeap::is_in_exact(const void* p) const {
2142 bool contains = reserved_region().contains(p);
2143 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2144 if (contains && available) {
2145 return true;
2146 } else {
2147 return false;
2148 }
2149 }
2150 #endif
2151
2152 // Iteration functions.
2153
2154 // Iterates an ObjectClosure over all objects within a HeapRegion.
2155
2156 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2157 ObjectClosure* _cl;
2158 public:
2159 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2160 bool do_heap_region(HeapRegion* r) {
2161 if (!r->is_continues_humongous()) {
2162 r->object_iterate(_cl);
2163 }
2164 return false;
2165 }
2166 };
2167
2168 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2169 IterateObjectClosureRegionClosure blk(cl);
2170 heap_region_iterate(&blk);
2171 }
2172
2173 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2174 _hrm.iterate(cl);
2175 }
2176
2177 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2178 HeapRegionClaimer *hrclaimer,
2179 uint worker_id) const {
2180 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2181 }
2182
2183 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2184 HeapRegionClaimer *hrclaimer) const {
2185 _hrm.par_iterate(cl, hrclaimer, 0);
2186 }
2187
2188 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2189 _collection_set.iterate(cl);
2190 }
2191
2192 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2193 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2194 }
2195
2196 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2197 HeapRegion* hr = heap_region_containing(addr);
2198 return hr->block_start(addr);
2199 }
2200
2201 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2202 HeapRegion* hr = heap_region_containing(addr);
2203 return hr->block_size(addr);
2204 }
2205
2206 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2207 HeapRegion* hr = heap_region_containing(addr);
2208 return hr->block_is_obj(addr);
2209 }
2210
2211 bool G1CollectedHeap::supports_tlab_allocation() const {
2212 return true;
2213 }
2214
2215 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2216 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2217 }
2218
2219 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2220 return _eden.length() * HeapRegion::GrainBytes;
2221 }
2222
2223 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2224 // must be equal to the humongous object limit.
2225 size_t G1CollectedHeap::max_tlab_size() const {
2226 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2227 }
2228
2229 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2230 return _allocator->unsafe_max_tlab_alloc();
2231 }
2232
2233 size_t G1CollectedHeap::max_capacity() const {
2234 return _hrm.reserved().byte_size();
2235 }
2236
2237 jlong G1CollectedHeap::millis_since_last_gc() {
2238 // See the notes in GenCollectedHeap::millis_since_last_gc()
2239 // for more information about the implementation.
2240 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2241 _g1_policy->collection_pause_end_millis();
2242 if (ret_val < 0) {
2243 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2244 ". returning zero instead.", ret_val);
2245 return 0;
2246 }
2247 return ret_val;
2248 }
2249
2250 void G1CollectedHeap::deduplicate_string(oop str) {
2251 assert(java_lang_String::is_instance(str), "invariant");
2252
2253 if (G1StringDedup::is_enabled()) {
2254 G1StringDedup::deduplicate(str);
2255 }
2256 }
2257
2258 void G1CollectedHeap::prepare_for_verify() {
2259 _verifier->prepare_for_verify();
2260 }
2261
2262 void G1CollectedHeap::verify(VerifyOption vo) {
2263 _verifier->verify(vo);
2264 }
2265
2266 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2267 return true;
2268 }
2269
2270 const char* const* G1CollectedHeap::concurrent_phases() const {
2271 return _cm_thread->concurrent_phases();
2272 }
2273
2274 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2275 return _cm_thread->request_concurrent_phase(phase);
2276 }
2277
2278 class PrintRegionClosure: public HeapRegionClosure {
2279 outputStream* _st;
2280 public:
2281 PrintRegionClosure(outputStream* st) : _st(st) {}
2282 bool do_heap_region(HeapRegion* r) {
2283 r->print_on(_st);
2284 return false;
2285 }
2286 };
2287
2288 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2289 const HeapRegion* hr,
2290 const VerifyOption vo) const {
2291 switch (vo) {
2292 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2293 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2294 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2295 default: ShouldNotReachHere();
2296 }
2297 return false; // keep some compilers happy
2298 }
2299
2300 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2301 const VerifyOption vo) const {
2302 switch (vo) {
2303 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2304 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2305 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2306 default: ShouldNotReachHere();
2307 }
2308 return false; // keep some compilers happy
2309 }
2310
2311 void G1CollectedHeap::print_heap_regions() const {
2312 LogTarget(Trace, gc, heap, region) lt;
2313 if (lt.is_enabled()) {
2314 LogStream ls(lt);
2315 print_regions_on(&ls);
2316 }
2317 }
2318
2319 void G1CollectedHeap::print_on(outputStream* st) const {
2320 st->print(" %-20s", "garbage-first heap");
2321 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2322 capacity()/K, used_unlocked()/K);
2323 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2324 p2i(_hrm.reserved().start()),
2325 p2i(_hrm.reserved().end()));
2326 st->cr();
2327 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2328 uint young_regions = young_regions_count();
2329 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2330 (size_t) young_regions * HeapRegion::GrainBytes / K);
2331 uint survivor_regions = survivor_regions_count();
2332 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2333 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2334 st->cr();
2335 MetaspaceUtils::print_on(st);
2336 }
2337
2338 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2339 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2340 "HS=humongous(starts), HC=humongous(continues), "
2341 "CS=collection set, F=free, A=archive, "
2342 "TAMS=top-at-mark-start (previous, next)");
2343 PrintRegionClosure blk(st);
2344 heap_region_iterate(&blk);
2345 }
2346
2347 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2348 print_on(st);
2349
2350 // Print the per-region information.
2351 print_regions_on(st);
2352 }
2353
2354 void G1CollectedHeap::print_on_error(outputStream* st) const {
2355 this->CollectedHeap::print_on_error(st);
2356
2357 if (_cm != NULL) {
2358 st->cr();
2359 _cm->print_on_error(st);
2360 }
2361 }
2362
2363 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2364 workers()->print_worker_threads_on(st);
2365 _cm_thread->print_on(st);
2366 st->cr();
2367 _cm->print_worker_threads_on(st);
2368 _cr->print_threads_on(st);
2369 _young_gen_sampling_thread->print_on(st);
2370 if (G1StringDedup::is_enabled()) {
2371 G1StringDedup::print_worker_threads_on(st);
2372 }
2373 }
2374
2375 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2376 workers()->threads_do(tc);
2377 tc->do_thread(_cm_thread);
2378 _cm->threads_do(tc);
2379 _cr->threads_do(tc);
2380 tc->do_thread(_young_gen_sampling_thread);
2381 if (G1StringDedup::is_enabled()) {
2382 G1StringDedup::threads_do(tc);
2383 }
2384 }
2385
2386 void G1CollectedHeap::print_tracing_info() const {
2387 g1_rem_set()->print_summary_info();
2388 concurrent_mark()->print_summary_info();
2389 }
2390
2391 #ifndef PRODUCT
2392 // Helpful for debugging RSet issues.
2393
2394 class PrintRSetsClosure : public HeapRegionClosure {
2395 private:
2396 const char* _msg;
2397 size_t _occupied_sum;
2398
2399 public:
2400 bool do_heap_region(HeapRegion* r) {
2401 HeapRegionRemSet* hrrs = r->rem_set();
2402 size_t occupied = hrrs->occupied();
2403 _occupied_sum += occupied;
2404
2405 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2406 if (occupied == 0) {
2407 tty->print_cr(" RSet is empty");
2408 } else {
2409 hrrs->print();
2410 }
2411 tty->print_cr("----------");
2412 return false;
2413 }
2414
2415 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2416 tty->cr();
2417 tty->print_cr("========================================");
2418 tty->print_cr("%s", msg);
2419 tty->cr();
2420 }
2421
2422 ~PrintRSetsClosure() {
2423 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2424 tty->print_cr("========================================");
2425 tty->cr();
2426 }
2427 };
2428
2429 void G1CollectedHeap::print_cset_rsets() {
2430 PrintRSetsClosure cl("Printing CSet RSets");
2431 collection_set_iterate(&cl);
2432 }
2433
2434 void G1CollectedHeap::print_all_rsets() {
2435 PrintRSetsClosure cl("Printing All RSets");;
2436 heap_region_iterate(&cl);
2437 }
2438 #endif // PRODUCT
2439
2440 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2441
2442 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2443 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2444 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2445
2446 size_t eden_capacity_bytes =
2447 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2448
2449 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2450 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2451 eden_capacity_bytes, survivor_used_bytes, num_regions());
2452 }
2453
2454 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2455 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2456 stats->unused(), stats->used(), stats->region_end_waste(),
2457 stats->regions_filled(), stats->direct_allocated(),
2458 stats->failure_used(), stats->failure_waste());
2459 }
2460
2461 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2462 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2463 gc_tracer->report_gc_heap_summary(when, heap_summary);
2464
2465 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2466 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2467 }
2468
2469 G1CollectedHeap* G1CollectedHeap::heap() {
2470 CollectedHeap* heap = Universe::heap();
2471 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2472 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2473 return (G1CollectedHeap*)heap;
2474 }
2475
2476 void G1CollectedHeap::gc_prologue(bool full) {
2477 // always_do_update_barrier = false;
2478 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2479
2480 // This summary needs to be printed before incrementing total collections.
2481 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2482
2483 // Update common counters.
2484 increment_total_collections(full /* full gc */);
2485 if (full) {
2486 increment_old_marking_cycles_started();
2487 }
2488
2489 // Fill TLAB's and such
2490 double start = os::elapsedTime();
2491 ensure_parsability(true);
2492 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2493 }
2494
2495 void G1CollectedHeap::gc_epilogue(bool full) {
2496 // Update common counters.
2497 if (full) {
2498 // Update the number of full collections that have been completed.
2499 increment_old_marking_cycles_completed(false /* concurrent */);
2500 }
2501
2502 // We are at the end of the GC. Total collections has already been increased.
2503 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2504
2505 // FIXME: what is this about?
2506 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2507 // is set.
2508 #if COMPILER2_OR_JVMCI
2509 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2510 #endif
2511 // always_do_update_barrier = true;
2512
2513 double start = os::elapsedTime();
2514 resize_all_tlabs();
2515 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2516
2517 MemoryService::track_memory_usage();
2518 // We have just completed a GC. Update the soft reference
2519 // policy with the new heap occupancy
2520 Universe::update_heap_info_at_gc();
2521 }
2522
2523 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2524 uint gc_count_before,
2525 bool* succeeded,
2526 GCCause::Cause gc_cause) {
2527 assert_heap_not_locked_and_not_at_safepoint();
2528 VM_G1CollectForAllocation op(word_size,
2529 gc_count_before,
2530 gc_cause,
2531 false, /* should_initiate_conc_mark */
2532 g1_policy()->max_pause_time_ms());
2533 VMThread::execute(&op);
2534
2535 HeapWord* result = op.result();
2536 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2537 assert(result == NULL || ret_succeeded,
2538 "the result should be NULL if the VM did not succeed");
2539 *succeeded = ret_succeeded;
2540
2541 assert_heap_not_locked();
2542 return result;
2543 }
2544
2545 void G1CollectedHeap::do_concurrent_mark() {
2546 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2547 if (!_cm_thread->in_progress()) {
2548 _cm_thread->set_started();
2549 CGC_lock->notify();
2550 }
2551 }
2552
2553 size_t G1CollectedHeap::pending_card_num() {
2554 size_t extra_cards = 0;
2555 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2556 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2557 extra_cards += dcq.size();
2558 }
2559 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2560 size_t buffer_size = dcqs.buffer_size();
2561 size_t buffer_num = dcqs.completed_buffers_num();
2562
2563 return buffer_size * buffer_num + extra_cards;
2564 }
2565
2566 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2567 // We don't nominate objects with many remembered set entries, on
2568 // the assumption that such objects are likely still live.
2569 HeapRegionRemSet* rem_set = r->rem_set();
2570
2571 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2572 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2573 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2574 }
2575
2576 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2577 private:
2578 size_t _total_humongous;
2579 size_t _candidate_humongous;
2580
2581 DirtyCardQueue _dcq;
2582
2583 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2584 assert(region->is_starts_humongous(), "Must start a humongous object");
2585
2586 oop obj = oop(region->bottom());
2587
2588 // Dead objects cannot be eager reclaim candidates. Due to class
2589 // unloading it is unsafe to query their classes so we return early.
2590 if (g1h->is_obj_dead(obj, region)) {
2591 return false;
2592 }
2593
2594 // If we do not have a complete remembered set for the region, then we can
2595 // not be sure that we have all references to it.
2596 if (!region->rem_set()->is_complete()) {
2597 return false;
2598 }
2599 // Candidate selection must satisfy the following constraints
2600 // while concurrent marking is in progress:
2601 //
2602 // * In order to maintain SATB invariants, an object must not be
2603 // reclaimed if it was allocated before the start of marking and
2604 // has not had its references scanned. Such an object must have
2605 // its references (including type metadata) scanned to ensure no
2606 // live objects are missed by the marking process. Objects
2607 // allocated after the start of concurrent marking don't need to
2608 // be scanned.
2609 //
2610 // * An object must not be reclaimed if it is on the concurrent
2611 // mark stack. Objects allocated after the start of concurrent
2612 // marking are never pushed on the mark stack.
2613 //
2614 // Nominating only objects allocated after the start of concurrent
2615 // marking is sufficient to meet both constraints. This may miss
2616 // some objects that satisfy the constraints, but the marking data
2617 // structures don't support efficiently performing the needed
2618 // additional tests or scrubbing of the mark stack.
2619 //
2620 // However, we presently only nominate is_typeArray() objects.
2621 // A humongous object containing references induces remembered
2622 // set entries on other regions. In order to reclaim such an
2623 // object, those remembered sets would need to be cleaned up.
2624 //
2625 // We also treat is_typeArray() objects specially, allowing them
2626 // to be reclaimed even if allocated before the start of
2627 // concurrent mark. For this we rely on mark stack insertion to
2628 // exclude is_typeArray() objects, preventing reclaiming an object
2629 // that is in the mark stack. We also rely on the metadata for
2630 // such objects to be built-in and so ensured to be kept live.
2631 // Frequent allocation and drop of large binary blobs is an
2632 // important use case for eager reclaim, and this special handling
2633 // may reduce needed headroom.
2634
2635 return obj->is_typeArray() &&
2636 g1h->is_potential_eager_reclaim_candidate(region);
2637 }
2638
2639 public:
2640 RegisterHumongousWithInCSetFastTestClosure()
2641 : _total_humongous(0),
2642 _candidate_humongous(0),
2643 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2644 }
2645
2646 virtual bool do_heap_region(HeapRegion* r) {
2647 if (!r->is_starts_humongous()) {
2648 return false;
2649 }
2650 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2651
2652 bool is_candidate = humongous_region_is_candidate(g1h, r);
2653 uint rindex = r->hrm_index();
2654 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2655 if (is_candidate) {
2656 _candidate_humongous++;
2657 g1h->register_humongous_region_with_cset(rindex);
2658 // Is_candidate already filters out humongous object with large remembered sets.
2659 // If we have a humongous object with a few remembered sets, we simply flush these
2660 // remembered set entries into the DCQS. That will result in automatic
2661 // re-evaluation of their remembered set entries during the following evacuation
2662 // phase.
2663 if (!r->rem_set()->is_empty()) {
2664 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2665 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2666 G1CardTable* ct = g1h->card_table();
2667 HeapRegionRemSetIterator hrrs(r->rem_set());
2668 size_t card_index;
2669 while (hrrs.has_next(card_index)) {
2670 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2671 // The remembered set might contain references to already freed
2672 // regions. Filter out such entries to avoid failing card table
2673 // verification.
2674 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2675 if (*card_ptr != G1CardTable::dirty_card_val()) {
2676 *card_ptr = G1CardTable::dirty_card_val();
2677 _dcq.enqueue(card_ptr);
2678 }
2679 }
2680 }
2681 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2682 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2683 hrrs.n_yielded(), r->rem_set()->occupied());
2684 // We should only clear the card based remembered set here as we will not
2685 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2686 // (and probably never) we do not enter this path if there are other kind of
2687 // remembered sets for this region.
2688 r->rem_set()->clear_locked(true /* only_cardset */);
2689 // Clear_locked() above sets the state to Empty. However we want to continue
2690 // collecting remembered set entries for humongous regions that were not
2691 // reclaimed.
2692 r->rem_set()->set_state_complete();
2693 }
2694 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2695 }
2696 _total_humongous++;
2697
2698 return false;
2699 }
2700
2701 size_t total_humongous() const { return _total_humongous; }
2702 size_t candidate_humongous() const { return _candidate_humongous; }
2703
2704 void flush_rem_set_entries() { _dcq.flush(); }
2705 };
2706
2707 void G1CollectedHeap::register_humongous_regions_with_cset() {
2708 if (!G1EagerReclaimHumongousObjects) {
2709 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2710 return;
2711 }
2712 double time = os::elapsed_counter();
2713
2714 // Collect reclaim candidate information and register candidates with cset.
2715 RegisterHumongousWithInCSetFastTestClosure cl;
2716 heap_region_iterate(&cl);
2717
2718 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2719 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2720 cl.total_humongous(),
2721 cl.candidate_humongous());
2722 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2723
2724 // Finally flush all remembered set entries to re-check into the global DCQS.
2725 cl.flush_rem_set_entries();
2726 }
2727
2728 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2729 public:
2730 bool do_heap_region(HeapRegion* hr) {
2731 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2732 hr->verify_rem_set();
2733 }
2734 return false;
2735 }
2736 };
2737
2738 uint G1CollectedHeap::num_task_queues() const {
2739 return _task_queues->size();
2740 }
2741
2742 #if TASKQUEUE_STATS
2743 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2744 st->print_raw_cr("GC Task Stats");
2745 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2746 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2747 }
2748
2749 void G1CollectedHeap::print_taskqueue_stats() const {
2750 if (!log_is_enabled(Trace, gc, task, stats)) {
2751 return;
2752 }
2753 Log(gc, task, stats) log;
2754 ResourceMark rm;
2755 LogStream ls(log.trace());
2756 outputStream* st = &ls;
2757
2758 print_taskqueue_stats_hdr(st);
2759
2760 TaskQueueStats totals;
2761 const uint n = num_task_queues();
2762 for (uint i = 0; i < n; ++i) {
2763 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2764 totals += task_queue(i)->stats;
2765 }
2766 st->print_raw("tot "); totals.print(st); st->cr();
2767
2768 DEBUG_ONLY(totals.verify());
2769 }
2770
2771 void G1CollectedHeap::reset_taskqueue_stats() {
2772 const uint n = num_task_queues();
2773 for (uint i = 0; i < n; ++i) {
2774 task_queue(i)->stats.reset();
2775 }
2776 }
2777 #endif // TASKQUEUE_STATS
2778
2779 void G1CollectedHeap::wait_for_root_region_scanning() {
2780 double scan_wait_start = os::elapsedTime();
2781 // We have to wait until the CM threads finish scanning the
2782 // root regions as it's the only way to ensure that all the
2783 // objects on them have been correctly scanned before we start
2784 // moving them during the GC.
2785 bool waited = _cm->root_regions()->wait_until_scan_finished();
2786 double wait_time_ms = 0.0;
2787 if (waited) {
2788 double scan_wait_end = os::elapsedTime();
2789 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2790 }
2791 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2792 }
2793
2794 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2795 private:
2796 G1HRPrinter* _hr_printer;
2797 public:
2798 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2799
2800 virtual bool do_heap_region(HeapRegion* r) {
2801 _hr_printer->cset(r);
2802 return false;
2803 }
2804 };
2805
2806 void G1CollectedHeap::start_new_collection_set() {
2807 collection_set()->start_incremental_building();
2808
2809 clear_cset_fast_test();
2810
2811 guarantee(_eden.length() == 0, "eden should have been cleared");
2812 g1_policy()->transfer_survivors_to_cset(survivor());
2813 }
2814
2815 bool
2816 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2817 assert_at_safepoint_on_vm_thread();
2818 guarantee(!is_gc_active(), "collection is not reentrant");
2819
2820 if (GCLocker::check_active_before_gc()) {
2821 return false;
2822 }
2823
2824 _gc_timer_stw->register_gc_start();
2825
2826 GCIdMark gc_id_mark;
2827 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2828
2829 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2830 ResourceMark rm;
2831
2832 g1_policy()->note_gc_start();
2833
2834 wait_for_root_region_scanning();
2835
2836 print_heap_before_gc();
2837 print_heap_regions();
2838 trace_heap_before_gc(_gc_tracer_stw);
2839
2840 _verifier->verify_region_sets_optional();
2841 _verifier->verify_dirty_young_regions();
2842
2843 // We should not be doing initial mark unless the conc mark thread is running
2844 if (!_cm_thread->should_terminate()) {
2845 // This call will decide whether this pause is an initial-mark
2846 // pause. If it is, in_initial_mark_gc() will return true
2847 // for the duration of this pause.
2848 g1_policy()->decide_on_conc_mark_initiation();
2849 }
2850
2851 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2852 assert(!collector_state()->in_initial_mark_gc() ||
2853 collector_state()->in_young_only_phase(), "sanity");
2854
2855 // We also do not allow mixed GCs during marking.
2856 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2857
2858 // Record whether this pause is an initial mark. When the current
2859 // thread has completed its logging output and it's safe to signal
2860 // the CM thread, the flag's value in the policy has been reset.
2861 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2862
2863 // Inner scope for scope based logging, timers, and stats collection
2864 {
2865 EvacuationInfo evacuation_info;
2866
2867 if (collector_state()->in_initial_mark_gc()) {
2868 // We are about to start a marking cycle, so we increment the
2869 // full collection counter.
2870 increment_old_marking_cycles_started();
2871 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2872 }
2873
2874 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2875
2876 GCTraceCPUTime tcpu;
2877
2878 G1HeapVerifier::G1VerifyType verify_type;
2879 FormatBuffer<> gc_string("Pause Young ");
2880 if (collector_state()->in_initial_mark_gc()) {
2881 gc_string.append("(Concurrent Start)");
2882 verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2883 } else if (collector_state()->in_young_only_phase()) {
2884 if (collector_state()->in_young_gc_before_mixed()) {
2885 gc_string.append("(Prepare Mixed)");
2886 } else {
2887 gc_string.append("(Normal)");
2888 }
2889 verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2890 } else {
2891 gc_string.append("(Mixed)");
2892 verify_type = G1HeapVerifier::G1VerifyMixed;
2893 }
2894 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2895
2896 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2897 workers()->active_workers(),
2898 Threads::number_of_non_daemon_threads());
2899 active_workers = workers()->update_active_workers(active_workers);
2900 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2901
2902 G1MonitoringScope ms(g1mm(),
2903 false /* full_gc */,
2904 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2905
2906 G1HeapTransition heap_transition(this);
2907 size_t heap_used_bytes_before_gc = used();
2908
2909 // Don't dynamically change the number of GC threads this early. A value of
2910 // 0 is used to indicate serial work. When parallel work is done,
2911 // it will be set.
2912
2913 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2914 IsGCActiveMark x;
2915
2916 gc_prologue(false);
2917
2918 if (VerifyRememberedSets) {
2919 log_info(gc, verify)("[Verifying RemSets before GC]");
2920 VerifyRegionRemSetClosure v_cl;
2921 heap_region_iterate(&v_cl);
2922 }
2923
2924 _verifier->verify_before_gc(verify_type);
2925
2926 _verifier->check_bitmaps("GC Start");
2927
2928 #if COMPILER2_OR_JVMCI
2929 DerivedPointerTable::clear();
2930 #endif
2931
2932 // Please see comment in g1CollectedHeap.hpp and
2933 // G1CollectedHeap::ref_processing_init() to see how
2934 // reference processing currently works in G1.
2935
2936 // Enable discovery in the STW reference processor
2937 _ref_processor_stw->enable_discovery();
2938
2939 {
2940 // We want to temporarily turn off discovery by the
2941 // CM ref processor, if necessary, and turn it back on
2942 // on again later if we do. Using a scoped
2943 // NoRefDiscovery object will do this.
2944 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2945
2946 // Forget the current alloc region (we might even choose it to be part
2947 // of the collection set!).
2948 _allocator->release_mutator_alloc_region();
2949
2950 // This timing is only used by the ergonomics to handle our pause target.
2951 // It is unclear why this should not include the full pause. We will
2952 // investigate this in CR 7178365.
2953 //
2954 // Preserving the old comment here if that helps the investigation:
2955 //
2956 // The elapsed time induced by the start time below deliberately elides
2957 // the possible verification above.
2958 double sample_start_time_sec = os::elapsedTime();
2959
2960 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2961
2962 if (collector_state()->in_initial_mark_gc()) {
2963 concurrent_mark()->pre_initial_mark();
2964 }
2965
2966 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2967
2968 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2969
2970 // Make sure the remembered sets are up to date. This needs to be
2971 // done before register_humongous_regions_with_cset(), because the
2972 // remembered sets are used there to choose eager reclaim candidates.
2973 // If the remembered sets are not up to date we might miss some
2974 // entries that need to be handled.
2975 g1_rem_set()->cleanupHRRS();
2976
2977 register_humongous_regions_with_cset();
2978
2979 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2980
2981 // We call this after finalize_cset() to
2982 // ensure that the CSet has been finalized.
2983 _cm->verify_no_cset_oops();
2984
2985 if (_hr_printer.is_active()) {
2986 G1PrintCollectionSetClosure cl(&_hr_printer);
2987 _collection_set.iterate(&cl);
2988 }
2989
2990 // Initialize the GC alloc regions.
2991 _allocator->init_gc_alloc_regions(evacuation_info);
2992
2993 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2994 pre_evacuate_collection_set();
2995
2996 // Actually do the work...
2997 evacuate_collection_set(&per_thread_states);
2998
2999 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3000
3001 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3002 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3003
3004 eagerly_reclaim_humongous_regions();
3005
3006 record_obj_copy_mem_stats();
3007 _survivor_evac_stats.adjust_desired_plab_sz();
3008 _old_evac_stats.adjust_desired_plab_sz();
3009
3010 double start = os::elapsedTime();
3011 start_new_collection_set();
3012 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3013
3014 if (evacuation_failed()) {
3015 double recalculate_used_start = os::elapsedTime();
3016 set_used(recalculate_used());
3017 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3018
3019 if (_archive_allocator != NULL) {
3020 _archive_allocator->clear_used();
3021 }
3022 for (uint i = 0; i < ParallelGCThreads; i++) {
3023 if (_evacuation_failed_info_array[i].has_failed()) {
3024 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3025 }
3026 }
3027 } else {
3028 // The "used" of the the collection set have already been subtracted
3029 // when they were freed. Add in the bytes evacuated.
3030 increase_used(g1_policy()->bytes_copied_during_gc());
3031 }
3032
3033 if (collector_state()->in_initial_mark_gc()) {
3034 // We have to do this before we notify the CM threads that
3035 // they can start working to make sure that all the
3036 // appropriate initialization is done on the CM object.
3037 concurrent_mark()->post_initial_mark();
3038 // Note that we don't actually trigger the CM thread at
3039 // this point. We do that later when we're sure that
3040 // the current thread has completed its logging output.
3041 }
3042
3043 allocate_dummy_regions();
3044
3045 _allocator->init_mutator_alloc_region();
3046
3047 {
3048 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3049 if (expand_bytes > 0) {
3050 size_t bytes_before = capacity();
3051 // No need for an ergo logging here,
3052 // expansion_amount() does this when it returns a value > 0.
3053 double expand_ms;
3054 if (!expand(expand_bytes, _workers, &expand_ms)) {
3055 // We failed to expand the heap. Cannot do anything about it.
3056 }
3057 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3058 }
3059 }
3060
3061 // We redo the verification but now wrt to the new CSet which
3062 // has just got initialized after the previous CSet was freed.
3063 _cm->verify_no_cset_oops();
3064
3065 // This timing is only used by the ergonomics to handle our pause target.
3066 // It is unclear why this should not include the full pause. We will
3067 // investigate this in CR 7178365.
3068 double sample_end_time_sec = os::elapsedTime();
3069 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3070 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3071 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3072
3073 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3074 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3075
3076 if (VerifyRememberedSets) {
3077 log_info(gc, verify)("[Verifying RemSets after GC]");
3078 VerifyRegionRemSetClosure v_cl;
3079 heap_region_iterate(&v_cl);
3080 }
3081
3082 _verifier->verify_after_gc(verify_type);
3083 _verifier->check_bitmaps("GC End");
3084
3085 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3086 _ref_processor_stw->verify_no_references_recorded();
3087
3088 // CM reference discovery will be re-enabled if necessary.
3089 }
3090
3091 #ifdef TRACESPINNING
3092 ParallelTaskTerminator::print_termination_counts();
3093 #endif
3094
3095 gc_epilogue(false);
3096 }
3097
3098 // Print the remainder of the GC log output.
3099 if (evacuation_failed()) {
3100 log_info(gc)("To-space exhausted");
3101 }
3102
3103 g1_policy()->print_phases();
3104 heap_transition.print();
3105
3106 // It is not yet to safe to tell the concurrent mark to
3107 // start as we have some optional output below. We don't want the
3108 // output from the concurrent mark thread interfering with this
3109 // logging output either.
3110
3111 _hrm.verify_optional();
3112 _verifier->verify_region_sets_optional();
3113
3114 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3115 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3116
3117 print_heap_after_gc();
3118 print_heap_regions();
3119 trace_heap_after_gc(_gc_tracer_stw);
3120
3121 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3122 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3123 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3124 // before any GC notifications are raised.
3125 g1mm()->update_sizes();
3126
3127 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3128 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3129 _gc_timer_stw->register_gc_end();
3130 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3131 }
3132 // It should now be safe to tell the concurrent mark thread to start
3133 // without its logging output interfering with the logging output
3134 // that came from the pause.
3135
3136 if (should_start_conc_mark) {
3137 // CAUTION: after the doConcurrentMark() call below,
3138 // the concurrent marking thread(s) could be running
3139 // concurrently with us. Make sure that anything after
3140 // this point does not assume that we are the only GC thread
3141 // running. Note: of course, the actual marking work will
3142 // not start until the safepoint itself is released in
3143 // SuspendibleThreadSet::desynchronize().
3144 do_concurrent_mark();
3145 }
3146
3147 return true;
3148 }
3149
3150 void G1CollectedHeap::remove_self_forwarding_pointers() {
3151 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3152 workers()->run_task(&rsfp_task);
3153 }
3154
3155 void G1CollectedHeap::restore_after_evac_failure() {
3156 double remove_self_forwards_start = os::elapsedTime();
3157
3158 remove_self_forwarding_pointers();
3159 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3160 _preserved_marks_set.restore(&task_executor);
3161
3162 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3163 }
3164
3165 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3166 if (!_evacuation_failed) {
3167 _evacuation_failed = true;
3168 }
3169
3170 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3171 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3172 }
3173
3174 bool G1ParEvacuateFollowersClosure::offer_termination() {
3175 EventGCPhaseParallel event;
3176 G1ParScanThreadState* const pss = par_scan_state();
3177 start_term_time();
3178 const bool res = terminator()->offer_termination();
3179 end_term_time();
3180 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3181 return res;
3182 }
3183
3184 void G1ParEvacuateFollowersClosure::do_void() {
3185 EventGCPhaseParallel event;
3186 G1ParScanThreadState* const pss = par_scan_state();
3187 pss->trim_queue();
3188 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3189 do {
3190 EventGCPhaseParallel event;
3191 pss->steal_and_trim_queue(queues());
3192 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3193 } while (!offer_termination());
3194 }
3195
3196 class G1ParTask : public AbstractGangTask {
3197 protected:
3198 G1CollectedHeap* _g1h;
3199 G1ParScanThreadStateSet* _pss;
3200 RefToScanQueueSet* _queues;
3201 G1RootProcessor* _root_processor;
3202 ParallelTaskTerminator _terminator;
3203 uint _n_workers;
3204
3205 public:
3206 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3207 : AbstractGangTask("G1 collection"),
3208 _g1h(g1h),
3209 _pss(per_thread_states),
3210 _queues(task_queues),
3211 _root_processor(root_processor),
3212 _terminator(n_workers, _queues),
3213 _n_workers(n_workers)
3214 {}
3215
3216 void work(uint worker_id) {
3217 if (worker_id >= _n_workers) return; // no work needed this round
3218
3219 double start_sec = os::elapsedTime();
3220 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3221
3222 {
3223 ResourceMark rm;
3224 HandleMark hm;
3225
3226 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3227
3228 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3229 pss->set_ref_discoverer(rp);
3230
3231 double start_strong_roots_sec = os::elapsedTime();
3232
3233 _root_processor->evacuate_roots(pss, worker_id);
3234
3235 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3236 // treating the nmethods visited to act as roots for concurrent marking.
3237 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3238 // objects copied by the current evacuation.
3239 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3240
3241 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3242
3243 double term_sec = 0.0;
3244 size_t evac_term_attempts = 0;
3245 {
3246 double start = os::elapsedTime();
3247 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3248 evac.do_void();
3249
3250 evac_term_attempts = evac.term_attempts();
3251 term_sec = evac.term_time();
3252 double elapsed_sec = os::elapsedTime() - start;
3253
3254 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3255 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3256 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3257 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3258 }
3259
3260 assert(pss->queue_is_empty(), "should be empty");
3261
3262 if (log_is_enabled(Debug, gc, task, stats)) {
3263 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3264 size_t lab_waste;
3265 size_t lab_undo_waste;
3266 pss->waste(lab_waste, lab_undo_waste);
3267 _g1h->print_termination_stats(worker_id,
3268 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3269 strong_roots_sec * 1000.0, /* strong roots time */
3270 term_sec * 1000.0, /* evac term time */
3271 evac_term_attempts, /* evac term attempts */
3272 lab_waste, /* alloc buffer waste */
3273 lab_undo_waste /* undo waste */
3274 );
3275 }
3276
3277 // Close the inner scope so that the ResourceMark and HandleMark
3278 // destructors are executed here and are included as part of the
3279 // "GC Worker Time".
3280 }
3281 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3282 }
3283 };
3284
3285 void G1CollectedHeap::print_termination_stats_hdr() {
3286 log_debug(gc, task, stats)("GC Termination Stats");
3287 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3288 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3289 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3290 }
3291
3292 void G1CollectedHeap::print_termination_stats(uint worker_id,
3293 double elapsed_ms,
3294 double strong_roots_ms,
3295 double term_ms,
3296 size_t term_attempts,
3297 size_t alloc_buffer_waste,
3298 size_t undo_waste) const {
3299 log_debug(gc, task, stats)
3300 ("%3d %9.2f %9.2f %6.2f "
3301 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3302 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3303 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3304 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3305 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3306 alloc_buffer_waste * HeapWordSize / K,
3307 undo_waste * HeapWordSize / K);
3308 }
3309
3310 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3311 bool class_unloading_occurred) {
3312 uint n_workers = workers()->active_workers();
3313
3314 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3315 ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
3316 workers()->run_task(&g1_unlink_task);
3317 }
3318
3319 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3320 bool process_strings,
3321 bool process_string_dedup) {
3322 if (!process_strings && !process_string_dedup) {
3323 // Nothing to clean.
3324 return;
3325 }
3326
3327 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3328 StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
3329 workers()->run_task(&g1_unlink_task);
3330 }
3331
3332 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3333 private:
3334 DirtyCardQueueSet* _queue;
3335 G1CollectedHeap* _g1h;
3336 public:
3337 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3338 _queue(queue), _g1h(g1h) { }
3339
3340 virtual void work(uint worker_id) {
3341 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3342 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3343
3344 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3345 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3346
3347 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3348 }
3349 };
3350
3351 void G1CollectedHeap::redirty_logged_cards() {
3352 double redirty_logged_cards_start = os::elapsedTime();
3353
3354 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3355 dirty_card_queue_set().reset_for_par_iteration();
3356 workers()->run_task(&redirty_task);
3357
3358 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3359 dcq.merge_bufferlists(&dirty_card_queue_set());
3360 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3361
3362 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3363 }
3364
3365 // Weak Reference Processing support
3366
3367 bool G1STWIsAliveClosure::do_object_b(oop p) {
3368 // An object is reachable if it is outside the collection set,
3369 // or is inside and copied.
3370 return !_g1h->is_in_cset(p) || p->is_forwarded();
3371 }
3372
3373 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3374 assert(obj != NULL, "must not be NULL");
3375 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3376 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3377 // may falsely indicate that this is not the case here: however the collection set only
3378 // contains old regions when concurrent mark is not running.
3379 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3380 }
3381
3382 // Non Copying Keep Alive closure
3383 class G1KeepAliveClosure: public OopClosure {
3384 G1CollectedHeap*_g1h;
3385 public:
3386 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3387 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3388 void do_oop(oop* p) {
3389 oop obj = *p;
3390 assert(obj != NULL, "the caller should have filtered out NULL values");
3391
3392 const InCSetState cset_state =_g1h->in_cset_state(obj);
3393 if (!cset_state.is_in_cset_or_humongous()) {
3394 return;
3395 }
3396 if (cset_state.is_in_cset()) {
3397 assert( obj->is_forwarded(), "invariant" );
3398 *p = obj->forwardee();
3399 } else {
3400 assert(!obj->is_forwarded(), "invariant" );
3401 assert(cset_state.is_humongous(),
3402 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3403 _g1h->set_humongous_is_live(obj);
3404 }
3405 }
3406 };
3407
3408 // Copying Keep Alive closure - can be called from both
3409 // serial and parallel code as long as different worker
3410 // threads utilize different G1ParScanThreadState instances
3411 // and different queues.
3412
3413 class G1CopyingKeepAliveClosure: public OopClosure {
3414 G1CollectedHeap* _g1h;
3415 G1ParScanThreadState* _par_scan_state;
3416
3417 public:
3418 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3419 G1ParScanThreadState* pss):
3420 _g1h(g1h),
3421 _par_scan_state(pss)
3422 {}
3423
3424 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3425 virtual void do_oop( oop* p) { do_oop_work(p); }
3426
3427 template <class T> void do_oop_work(T* p) {
3428 oop obj = RawAccess<>::oop_load(p);
3429
3430 if (_g1h->is_in_cset_or_humongous(obj)) {
3431 // If the referent object has been forwarded (either copied
3432 // to a new location or to itself in the event of an
3433 // evacuation failure) then we need to update the reference
3434 // field and, if both reference and referent are in the G1
3435 // heap, update the RSet for the referent.
3436 //
3437 // If the referent has not been forwarded then we have to keep
3438 // it alive by policy. Therefore we have copy the referent.
3439 //
3440 // When the queue is drained (after each phase of reference processing)
3441 // the object and it's followers will be copied, the reference field set
3442 // to point to the new location, and the RSet updated.
3443 _par_scan_state->push_on_queue(p);
3444 }
3445 }
3446 };
3447
3448 // Serial drain queue closure. Called as the 'complete_gc'
3449 // closure for each discovered list in some of the
3450 // reference processing phases.
3451
3452 class G1STWDrainQueueClosure: public VoidClosure {
3453 protected:
3454 G1CollectedHeap* _g1h;
3455 G1ParScanThreadState* _par_scan_state;
3456
3457 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3458
3459 public:
3460 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3461 _g1h(g1h),
3462 _par_scan_state(pss)
3463 { }
3464
3465 void do_void() {
3466 G1ParScanThreadState* const pss = par_scan_state();
3467 pss->trim_queue();
3468 }
3469 };
3470
3471 // Parallel Reference Processing closures
3472
3473 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3474 // processing during G1 evacuation pauses.
3475
3476 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3477 private:
3478 G1CollectedHeap* _g1h;
3479 G1ParScanThreadStateSet* _pss;
3480 RefToScanQueueSet* _queues;
3481 WorkGang* _workers;
3482
3483 public:
3484 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3485 G1ParScanThreadStateSet* per_thread_states,
3486 WorkGang* workers,
3487 RefToScanQueueSet *task_queues) :
3488 _g1h(g1h),
3489 _pss(per_thread_states),
3490 _queues(task_queues),
3491 _workers(workers)
3492 {
3493 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3494 }
3495
3496 // Executes the given task using concurrent marking worker threads.
3497 virtual void execute(ProcessTask& task, uint ergo_workers);
3498 };
3499
3500 // Gang task for possibly parallel reference processing
3501
3502 class G1STWRefProcTaskProxy: public AbstractGangTask {
3503 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3504 ProcessTask& _proc_task;
3505 G1CollectedHeap* _g1h;
3506 G1ParScanThreadStateSet* _pss;
3507 RefToScanQueueSet* _task_queues;
3508 ParallelTaskTerminator* _terminator;
3509
3510 public:
3511 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3512 G1CollectedHeap* g1h,
3513 G1ParScanThreadStateSet* per_thread_states,
3514 RefToScanQueueSet *task_queues,
3515 ParallelTaskTerminator* terminator) :
3516 AbstractGangTask("Process reference objects in parallel"),
3517 _proc_task(proc_task),
3518 _g1h(g1h),
3519 _pss(per_thread_states),
3520 _task_queues(task_queues),
3521 _terminator(terminator)
3522 {}
3523
3524 virtual void work(uint worker_id) {
3525 // The reference processing task executed by a single worker.
3526 ResourceMark rm;
3527 HandleMark hm;
3528
3529 G1STWIsAliveClosure is_alive(_g1h);
3530
3531 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3532 pss->set_ref_discoverer(NULL);
3533
3534 // Keep alive closure.
3535 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3536
3537 // Complete GC closure
3538 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3539
3540 // Call the reference processing task's work routine.
3541 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3542
3543 // Note we cannot assert that the refs array is empty here as not all
3544 // of the processing tasks (specifically phase2 - pp2_work) execute
3545 // the complete_gc closure (which ordinarily would drain the queue) so
3546 // the queue may not be empty.
3547 }
3548 };
3549
3550 // Driver routine for parallel reference processing.
3551 // Creates an instance of the ref processing gang
3552 // task and has the worker threads execute it.
3553 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3554 assert(_workers != NULL, "Need parallel worker threads.");
3555
3556 assert(_workers->active_workers() >= ergo_workers,
3557 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3558 ergo_workers, _workers->active_workers());
3559 ParallelTaskTerminator terminator(ergo_workers, _queues);
3560 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3561
3562 _workers->run_task(&proc_task_proxy, ergo_workers);
3563 }
3564
3565 // End of weak reference support closures
3566
3567 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3568 double ref_proc_start = os::elapsedTime();
3569
3570 ReferenceProcessor* rp = _ref_processor_stw;
3571 assert(rp->discovery_enabled(), "should have been enabled");
3572
3573 // Closure to test whether a referent is alive.
3574 G1STWIsAliveClosure is_alive(this);
3575
3576 // Even when parallel reference processing is enabled, the processing
3577 // of JNI refs is serial and performed serially by the current thread
3578 // rather than by a worker. The following PSS will be used for processing
3579 // JNI refs.
3580
3581 // Use only a single queue for this PSS.
3582 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3583 pss->set_ref_discoverer(NULL);
3584 assert(pss->queue_is_empty(), "pre-condition");
3585
3586 // Keep alive closure.
3587 G1CopyingKeepAliveClosure keep_alive(this, pss);
3588
3589 // Serial Complete GC closure
3590 G1STWDrainQueueClosure drain_queue(this, pss);
3591
3592 // Setup the soft refs policy...
3593 rp->setup_policy(false);
3594
3595 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3596
3597 ReferenceProcessorStats stats;
3598 if (!rp->processing_is_mt()) {
3599 // Serial reference processing...
3600 stats = rp->process_discovered_references(&is_alive,
3601 &keep_alive,
3602 &drain_queue,
3603 NULL,
3604 pt);
3605 } else {
3606 uint no_of_gc_workers = workers()->active_workers();
3607
3608 // Parallel reference processing
3609 assert(no_of_gc_workers <= rp->max_num_queues(),
3610 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3611 no_of_gc_workers, rp->max_num_queues());
3612
3613 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3614 stats = rp->process_discovered_references(&is_alive,
3615 &keep_alive,
3616 &drain_queue,
3617 &par_task_executor,
3618 pt);
3619 }
3620
3621 _gc_tracer_stw->report_gc_reference_stats(stats);
3622
3623 // We have completed copying any necessary live referent objects.
3624 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3625
3626 make_pending_list_reachable();
3627
3628 rp->verify_no_references_recorded();
3629
3630 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3631 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3632 }
3633
3634 void G1CollectedHeap::make_pending_list_reachable() {
3635 if (collector_state()->in_initial_mark_gc()) {
3636 oop pll_head = Universe::reference_pending_list();
3637 if (pll_head != NULL) {
3638 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3639 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3640 }
3641 }
3642 }
3643
3644 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3645 double merge_pss_time_start = os::elapsedTime();
3646 per_thread_states->flush();
3647 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3648 }
3649
3650 void G1CollectedHeap::pre_evacuate_collection_set() {
3651 _expand_heap_after_alloc_failure = true;
3652 _evacuation_failed = false;
3653
3654 // Disable the hot card cache.
3655 _hot_card_cache->reset_hot_cache_claimed_index();
3656 _hot_card_cache->set_use_cache(false);
3657
3658 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3659 _preserved_marks_set.assert_empty();
3660
3661 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3662
3663 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3664 if (collector_state()->in_initial_mark_gc()) {
3665 double start_clear_claimed_marks = os::elapsedTime();
3666
3667 ClassLoaderDataGraph::clear_claimed_marks();
3668
3669 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3670 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3671 }
3672 }
3673
3674 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3675 // Should G1EvacuationFailureALot be in effect for this GC?
3676 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3677
3678 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3679
3680 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3681
3682 double start_par_time_sec = os::elapsedTime();
3683 double end_par_time_sec;
3684
3685 {
3686 const uint n_workers = workers()->active_workers();
3687 G1RootProcessor root_processor(this, n_workers);
3688 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3689
3690 print_termination_stats_hdr();
3691
3692 workers()->run_task(&g1_par_task);
3693 end_par_time_sec = os::elapsedTime();
3694
3695 // Closing the inner scope will execute the destructor
3696 // for the G1RootProcessor object. We record the current
3697 // elapsed time before closing the scope so that time
3698 // taken for the destructor is NOT included in the
3699 // reported parallel time.
3700 }
3701
3702 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3703 phase_times->record_par_time(par_time_ms);
3704
3705 double code_root_fixup_time_ms =
3706 (os::elapsedTime() - end_par_time_sec) * 1000.0;
3707 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3708 }
3709
3710 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3711 // Also cleans the card table from temporary duplicate detection information used
3712 // during UpdateRS/ScanRS.
3713 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3714
3715 // Process any discovered reference objects - we have
3716 // to do this _before_ we retire the GC alloc regions
3717 // as we may have to copy some 'reachable' referent
3718 // objects (and their reachable sub-graphs) that were
3719 // not copied during the pause.
3720 process_discovered_references(per_thread_states);
3721
3722 // FIXME
3723 // CM's reference processing also cleans up the string table.
3724 // Should we do that here also? We could, but it is a serial operation
3725 // and could significantly increase the pause time.
3726
3727 G1STWIsAliveClosure is_alive(this);
3728 G1KeepAliveClosure keep_alive(this);
3729
3730 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3731 g1_policy()->phase_times()->weak_phase_times());
3732
3733 if (G1StringDedup::is_enabled()) {
3734 double fixup_start = os::elapsedTime();
3735
3736 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
3737
3738 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
3739 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
3740 }
3741
3742 if (evacuation_failed()) {
3743 restore_after_evac_failure();
3744
3745 // Reset the G1EvacuationFailureALot counters and flags
3746 // Note: the values are reset only when an actual
3747 // evacuation failure occurs.
3748 NOT_PRODUCT(reset_evacuation_should_fail();)
3749 }
3750
3751 _preserved_marks_set.assert_empty();
3752
3753 _allocator->release_gc_alloc_regions(evacuation_info);
3754
3755 merge_per_thread_state_info(per_thread_states);
3756
3757 // Reset and re-enable the hot card cache.
3758 // Note the counts for the cards in the regions in the
3759 // collection set are reset when the collection set is freed.
3760 _hot_card_cache->reset_hot_cache();
3761 _hot_card_cache->set_use_cache(true);
3762
3763 purge_code_root_memory();
3764
3765 redirty_logged_cards();
3766 #if COMPILER2_OR_JVMCI
3767 double start = os::elapsedTime();
3768 DerivedPointerTable::update_pointers();
3769 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3770 #endif
3771 g1_policy()->print_age_table();
3772 }
3773
3774 void G1CollectedHeap::record_obj_copy_mem_stats() {
3775 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3776
3777 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3778 create_g1_evac_summary(&_old_evac_stats));
3779 }
3780
3781 void G1CollectedHeap::free_region(HeapRegion* hr,
3782 FreeRegionList* free_list,
3783 bool skip_remset,
3784 bool skip_hot_card_cache,
3785 bool locked) {
3786 assert(!hr->is_free(), "the region should not be free");
3787 assert(!hr->is_empty(), "the region should not be empty");
3788 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
3789 assert(free_list != NULL, "pre-condition");
3790
3791 if (G1VerifyBitmaps) {
3792 MemRegion mr(hr->bottom(), hr->end());
3793 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3794 }
3795
3796 // Clear the card counts for this region.
3797 // Note: we only need to do this if the region is not young
3798 // (since we don't refine cards in young regions).
3799 if (!skip_hot_card_cache && !hr->is_young()) {
3800 _hot_card_cache->reset_card_counts(hr);
3801 }
3802 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3803 _g1_policy->remset_tracker()->update_at_free(hr);
3804 free_list->add_ordered(hr);
3805 }
3806
3807 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3808 FreeRegionList* free_list) {
3809 assert(hr->is_humongous(), "this is only for humongous regions");
3810 assert(free_list != NULL, "pre-condition");
3811 hr->clear_humongous();
3812 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3813 }
3814
3815 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3816 const uint humongous_regions_removed) {
3817 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3818 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3819 _old_set.bulk_remove(old_regions_removed);
3820 _humongous_set.bulk_remove(humongous_regions_removed);
3821 }
3822
3823 }
3824
3825 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3826 assert(list != NULL, "list can't be null");
3827 if (!list->is_empty()) {
3828 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3829 _hrm.insert_list_into_free_list(list);
3830 }
3831 }
3832
3833 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3834 decrease_used(bytes);
3835 }
3836
3837 class G1FreeCollectionSetTask : public AbstractGangTask {
3838 private:
3839
3840 // Closure applied to all regions in the collection set to do work that needs to
3841 // be done serially in a single thread.
3842 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3843 private:
3844 EvacuationInfo* _evacuation_info;
3845 const size_t* _surviving_young_words;
3846
3847 // Bytes used in successfully evacuated regions before the evacuation.
3848 size_t _before_used_bytes;
3849 // Bytes used in unsucessfully evacuated regions before the evacuation
3850 size_t _after_used_bytes;
3851
3852 size_t _bytes_allocated_in_old_since_last_gc;
3853
3854 size_t _failure_used_words;
3855 size_t _failure_waste_words;
3856
3857 FreeRegionList _local_free_list;
3858 public:
3859 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3860 HeapRegionClosure(),
3861 _evacuation_info(evacuation_info),
3862 _surviving_young_words(surviving_young_words),
3863 _before_used_bytes(0),
3864 _after_used_bytes(0),
3865 _bytes_allocated_in_old_since_last_gc(0),
3866 _failure_used_words(0),
3867 _failure_waste_words(0),
3868 _local_free_list("Local Region List for CSet Freeing") {
3869 }
3870
3871 virtual bool do_heap_region(HeapRegion* r) {
3872 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3873
3874 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3875 g1h->clear_in_cset(r);
3876
3877 if (r->is_young()) {
3878 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3879 "Young index %d is wrong for region %u of type %s with %u young regions",
3880 r->young_index_in_cset(),
3881 r->hrm_index(),
3882 r->get_type_str(),
3883 g1h->collection_set()->young_region_length());
3884 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3885 r->record_surv_words_in_group(words_survived);
3886 }
3887
3888 if (!r->evacuation_failed()) {
3889 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
3890 _before_used_bytes += r->used();
3891 g1h->free_region(r,
3892 &_local_free_list,
3893 true, /* skip_remset */
3894 true, /* skip_hot_card_cache */
3895 true /* locked */);
3896 } else {
3897 r->uninstall_surv_rate_group();
3898 r->set_young_index_in_cset(-1);
3899 r->set_evacuation_failed(false);
3900 // When moving a young gen region to old gen, we "allocate" that whole region
3901 // there. This is in addition to any already evacuated objects. Notify the
3902 // policy about that.
3903 // Old gen regions do not cause an additional allocation: both the objects
3904 // still in the region and the ones already moved are accounted for elsewhere.
3905 if (r->is_young()) {
3906 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
3907 }
3908 // The region is now considered to be old.
3909 r->set_old();
3910 // Do some allocation statistics accounting. Regions that failed evacuation
3911 // are always made old, so there is no need to update anything in the young
3912 // gen statistics, but we need to update old gen statistics.
3913 size_t used_words = r->marked_bytes() / HeapWordSize;
3914
3915 _failure_used_words += used_words;
3916 _failure_waste_words += HeapRegion::GrainWords - used_words;
3917
3918 g1h->old_set_add(r);
3919 _after_used_bytes += r->used();
3920 }
3921 return false;
3922 }
3923
3924 void complete_work() {
3925 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3926
3927 _evacuation_info->set_regions_freed(_local_free_list.length());
3928 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
3929
3930 g1h->prepend_to_freelist(&_local_free_list);
3931 g1h->decrement_summary_bytes(_before_used_bytes);
3932
3933 G1Policy* policy = g1h->g1_policy();
3934 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
3935
3936 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
3937 }
3938 };
3939
3940 G1CollectionSet* _collection_set;
3941 G1SerialFreeCollectionSetClosure _cl;
3942 const size_t* _surviving_young_words;
3943
3944 size_t _rs_lengths;
3945
3946 volatile jint _serial_work_claim;
3947
3948 struct WorkItem {
3949 uint region_idx;
3950 bool is_young;
3951 bool evacuation_failed;
3952
3953 WorkItem(HeapRegion* r) {
3954 region_idx = r->hrm_index();
3955 is_young = r->is_young();
3956 evacuation_failed = r->evacuation_failed();
3957 }
3958 };
3959
3960 volatile size_t _parallel_work_claim;
3961 size_t _num_work_items;
3962 WorkItem* _work_items;
3963
3964 void do_serial_work() {
3965 // Need to grab the lock to be allowed to modify the old region list.
3966 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3967 _collection_set->iterate(&_cl);
3968 }
3969
3970 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
3971 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3972
3973 HeapRegion* r = g1h->region_at(region_idx);
3974 assert(!g1h->is_on_master_free_list(r), "sanity");
3975
3976 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
3977
3978 if (!is_young) {
3979 g1h->_hot_card_cache->reset_card_counts(r);
3980 }
3981
3982 if (!evacuation_failed) {
3983 r->rem_set()->clear_locked();
3984 }
3985 }
3986
3987 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
3988 private:
3989 size_t _cur_idx;
3990 WorkItem* _work_items;
3991 public:
3992 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
3993
3994 virtual bool do_heap_region(HeapRegion* r) {
3995 _work_items[_cur_idx++] = WorkItem(r);
3996 return false;
3997 }
3998 };
3999
4000 void prepare_work() {
4001 G1PrepareFreeCollectionSetClosure cl(_work_items);
4002 _collection_set->iterate(&cl);
4003 }
4004
4005 void complete_work() {
4006 _cl.complete_work();
4007
4008 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4009 policy->record_max_rs_lengths(_rs_lengths);
4010 policy->cset_regions_freed();
4011 }
4012 public:
4013 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4014 AbstractGangTask("G1 Free Collection Set"),
4015 _collection_set(collection_set),
4016 _cl(evacuation_info, surviving_young_words),
4017 _surviving_young_words(surviving_young_words),
4018 _rs_lengths(0),
4019 _serial_work_claim(0),
4020 _parallel_work_claim(0),
4021 _num_work_items(collection_set->region_length()),
4022 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4023 prepare_work();
4024 }
4025
4026 ~G1FreeCollectionSetTask() {
4027 complete_work();
4028 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4029 }
4030
4031 // Chunk size for work distribution. The chosen value has been determined experimentally
4032 // to be a good tradeoff between overhead and achievable parallelism.
4033 static uint chunk_size() { return 32; }
4034
4035 virtual void work(uint worker_id) {
4036 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4037
4038 // Claim serial work.
4039 if (_serial_work_claim == 0) {
4040 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4041 if (value == 0) {
4042 double serial_time = os::elapsedTime();
4043 do_serial_work();
4044 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4045 }
4046 }
4047
4048 // Start parallel work.
4049 double young_time = 0.0;
4050 bool has_young_time = false;
4051 double non_young_time = 0.0;
4052 bool has_non_young_time = false;
4053
4054 while (true) {
4055 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4056 size_t cur = end - chunk_size();
4057
4058 if (cur >= _num_work_items) {
4059 break;
4060 }
4061
4062 EventGCPhaseParallel event;
4063 double start_time = os::elapsedTime();
4064
4065 end = MIN2(end, _num_work_items);
4066
4067 for (; cur < end; cur++) {
4068 bool is_young = _work_items[cur].is_young;
4069
4070 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4071
4072 double end_time = os::elapsedTime();
4073 double time_taken = end_time - start_time;
4074 if (is_young) {
4075 young_time += time_taken;
4076 has_young_time = true;
4077 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4078 } else {
4079 non_young_time += time_taken;
4080 has_non_young_time = true;
4081 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4082 }
4083 start_time = end_time;
4084 }
4085 }
4086
4087 if (has_young_time) {
4088 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4089 }
4090 if (has_non_young_time) {
4091 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4092 }
4093 }
4094 };
4095
4096 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4097 _eden.clear();
4098
4099 double free_cset_start_time = os::elapsedTime();
4100
4101 {
4102 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4103 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4104
4105 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4106
4107 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4108 cl.name(),
4109 num_workers,
4110 _collection_set.region_length());
4111 workers()->run_task(&cl, num_workers);
4112 }
4113 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4114
4115 collection_set->clear();
4116 }
4117
4118 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4119 private:
4120 FreeRegionList* _free_region_list;
4121 HeapRegionSet* _proxy_set;
4122 uint _humongous_objects_reclaimed;
4123 uint _humongous_regions_reclaimed;
4124 size_t _freed_bytes;
4125 public:
4126
4127 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4128 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4129 }
4130
4131 virtual bool do_heap_region(HeapRegion* r) {
4132 if (!r->is_starts_humongous()) {
4133 return false;
4134 }
4135
4136 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4137
4138 oop obj = (oop)r->bottom();
4139 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4140
4141 // The following checks whether the humongous object is live are sufficient.
4142 // The main additional check (in addition to having a reference from the roots
4143 // or the young gen) is whether the humongous object has a remembered set entry.
4144 //
4145 // A humongous object cannot be live if there is no remembered set for it
4146 // because:
4147 // - there can be no references from within humongous starts regions referencing
4148 // the object because we never allocate other objects into them.
4149 // (I.e. there are no intra-region references that may be missed by the
4150 // remembered set)
4151 // - as soon there is a remembered set entry to the humongous starts region
4152 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4153 // until the end of a concurrent mark.
4154 //
4155 // It is not required to check whether the object has been found dead by marking
4156 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4157 // all objects allocated during that time are considered live.
4158 // SATB marking is even more conservative than the remembered set.
4159 // So if at this point in the collection there is no remembered set entry,
4160 // nobody has a reference to it.
4161 // At the start of collection we flush all refinement logs, and remembered sets
4162 // are completely up-to-date wrt to references to the humongous object.
4163 //
4164 // Other implementation considerations:
4165 // - never consider object arrays at this time because they would pose
4166 // considerable effort for cleaning up the the remembered sets. This is
4167 // required because stale remembered sets might reference locations that
4168 // are currently allocated into.
4169 uint region_idx = r->hrm_index();
4170 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4171 !r->rem_set()->is_empty()) {
4172 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",
4173 region_idx,
4174 (size_t)obj->size() * HeapWordSize,
4175 p2i(r->bottom()),
4176 r->rem_set()->occupied(),
4177 r->rem_set()->strong_code_roots_list_length(),
4178 next_bitmap->is_marked(r->bottom()),
4179 g1h->is_humongous_reclaim_candidate(region_idx),
4180 obj->is_typeArray()
4181 );
4182 return false;
4183 }
4184
4185 guarantee(obj->is_typeArray(),
4186 "Only eagerly reclaiming type arrays is supported, but the object "
4187 PTR_FORMAT " is not.", p2i(r->bottom()));
4188
4189 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",
4190 region_idx,
4191 (size_t)obj->size() * HeapWordSize,
4192 p2i(r->bottom()),
4193 r->rem_set()->occupied(),
4194 r->rem_set()->strong_code_roots_list_length(),
4195 next_bitmap->is_marked(r->bottom()),
4196 g1h->is_humongous_reclaim_candidate(region_idx),
4197 obj->is_typeArray()
4198 );
4199
4200 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4201 cm->humongous_object_eagerly_reclaimed(r);
4202 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4203 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4204 region_idx,
4205 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4206 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4207 _humongous_objects_reclaimed++;
4208 do {
4209 HeapRegion* next = g1h->next_region_in_humongous(r);
4210 _freed_bytes += r->used();
4211 r->set_containing_set(NULL);
4212 _humongous_regions_reclaimed++;
4213 g1h->free_humongous_region(r, _free_region_list);
4214 r = next;
4215 } while (r != NULL);
4216
4217 return false;
4218 }
4219
4220 uint humongous_objects_reclaimed() {
4221 return _humongous_objects_reclaimed;
4222 }
4223
4224 uint humongous_regions_reclaimed() {
4225 return _humongous_regions_reclaimed;
4226 }
4227
4228 size_t bytes_freed() const {
4229 return _freed_bytes;
4230 }
4231 };
4232
4233 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4234 assert_at_safepoint_on_vm_thread();
4235
4236 if (!G1EagerReclaimHumongousObjects ||
4237 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4238 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4239 return;
4240 }
4241
4242 double start_time = os::elapsedTime();
4243
4244 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4245
4246 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4247 heap_region_iterate(&cl);
4248
4249 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4250
4251 G1HRPrinter* hrp = hr_printer();
4252 if (hrp->is_active()) {
4253 FreeRegionListIterator iter(&local_cleanup_list);
4254 while (iter.more_available()) {
4255 HeapRegion* hr = iter.get_next();
4256 hrp->cleanup(hr);
4257 }
4258 }
4259
4260 prepend_to_freelist(&local_cleanup_list);
4261 decrement_summary_bytes(cl.bytes_freed());
4262
4263 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4264 cl.humongous_objects_reclaimed());
4265 }
4266
4267 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4268 public:
4269 virtual bool do_heap_region(HeapRegion* r) {
4270 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4271 G1CollectedHeap::heap()->clear_in_cset(r);
4272 r->set_young_index_in_cset(-1);
4273 return false;
4274 }
4275 };
4276
4277 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4278 G1AbandonCollectionSetClosure cl;
4279 collection_set->iterate(&cl);
4280
4281 collection_set->clear();
4282 collection_set->stop_incremental_building();
4283 }
4284
4285 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4286 return _allocator->is_retained_old_region(hr);
4287 }
4288
4289 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4290 _eden.add(hr);
4291 _g1_policy->set_region_eden(hr);
4292 }
4293
4294 #ifdef ASSERT
4295
4296 class NoYoungRegionsClosure: public HeapRegionClosure {
4297 private:
4298 bool _success;
4299 public:
4300 NoYoungRegionsClosure() : _success(true) { }
4301 bool do_heap_region(HeapRegion* r) {
4302 if (r->is_young()) {
4303 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4304 p2i(r->bottom()), p2i(r->end()));
4305 _success = false;
4306 }
4307 return false;
4308 }
4309 bool success() { return _success; }
4310 };
4311
4312 bool G1CollectedHeap::check_young_list_empty() {
4313 bool ret = (young_regions_count() == 0);
4314
4315 NoYoungRegionsClosure closure;
4316 heap_region_iterate(&closure);
4317 ret = ret && closure.success();
4318
4319 return ret;
4320 }
4321
4322 #endif // ASSERT
4323
4324 class TearDownRegionSetsClosure : public HeapRegionClosure {
4325 HeapRegionSet *_old_set;
4326
4327 public:
4328 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4329
4330 bool do_heap_region(HeapRegion* r) {
4331 if (r->is_old()) {
4332 _old_set->remove(r);
4333 } else if(r->is_young()) {
4334 r->uninstall_surv_rate_group();
4335 } else {
4336 // We ignore free regions, we'll empty the free list afterwards.
4337 // We ignore humongous and archive regions, we're not tearing down these
4338 // sets.
4339 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4340 "it cannot be another type");
4341 }
4342 return false;
4343 }
4344
4345 ~TearDownRegionSetsClosure() {
4346 assert(_old_set->is_empty(), "post-condition");
4347 }
4348 };
4349
4350 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4351 assert_at_safepoint_on_vm_thread();
4352
4353 if (!free_list_only) {
4354 TearDownRegionSetsClosure cl(&_old_set);
4355 heap_region_iterate(&cl);
4356
4357 // Note that emptying the _young_list is postponed and instead done as
4358 // the first step when rebuilding the regions sets again. The reason for
4359 // this is that during a full GC string deduplication needs to know if
4360 // a collected region was young or old when the full GC was initiated.
4361 }
4362 _hrm.remove_all_free_regions();
4363 }
4364
4365 void G1CollectedHeap::increase_used(size_t bytes) {
4366 _summary_bytes_used += bytes;
4367 }
4368
4369 void G1CollectedHeap::decrease_used(size_t bytes) {
4370 assert(_summary_bytes_used >= bytes,
4371 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4372 _summary_bytes_used, bytes);
4373 _summary_bytes_used -= bytes;
4374 }
4375
4376 void G1CollectedHeap::set_used(size_t bytes) {
4377 _summary_bytes_used = bytes;
4378 }
4379
4380 class RebuildRegionSetsClosure : public HeapRegionClosure {
4381 private:
4382 bool _free_list_only;
4383
4384 HeapRegionSet* _old_set;
4385 HeapRegionManager* _hrm;
4386
4387 size_t _total_used;
4388
4389 public:
4390 RebuildRegionSetsClosure(bool free_list_only,
4391 HeapRegionSet* old_set,
4392 HeapRegionManager* hrm) :
4393 _free_list_only(free_list_only),
4394 _old_set(old_set), _hrm(hrm), _total_used(0) {
4395 assert(_hrm->num_free_regions() == 0, "pre-condition");
4396 if (!free_list_only) {
4397 assert(_old_set->is_empty(), "pre-condition");
4398 }
4399 }
4400
4401 bool do_heap_region(HeapRegion* r) {
4402 if (r->is_empty()) {
4403 // Add free regions to the free list
4404 r->set_free();
4405 _hrm->insert_into_free_list(r);
4406 } else if (!_free_list_only) {
4407 // Only if we rebuild everything, clear remembered sets.
4408 r->rem_set()->clear(true);
4409
4410 if (r->is_archive() || r->is_humongous()) {
4411 // We ignore archive and humongous regions. We left these sets unchanged.
4412 } else {
4413 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4414 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4415 r->move_to_old();
4416 _old_set->add(r);
4417 }
4418 _total_used += r->used();
4419 }
4420
4421 return false;
4422 }
4423
4424 size_t total_used() {
4425 return _total_used;
4426 }
4427 };
4428
4429 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4430 assert_at_safepoint_on_vm_thread();
4431
4432 if (!free_list_only) {
4433 _eden.clear();
4434 _survivor.clear();
4435 }
4436
4437 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4438 heap_region_iterate(&cl);
4439
4440 if (!free_list_only) {
4441 set_used(cl.total_used());
4442 if (_archive_allocator != NULL) {
4443 _archive_allocator->clear_used();
4444 }
4445 }
4446 assert(used() == recalculate_used(),
4447 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4448 used(), recalculate_used());
4449 }
4450
4451 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4452 HeapRegion* hr = heap_region_containing(p);
4453 return hr->is_in(p);
4454 }
4455
4456 // Methods for the mutator alloc region
4457
4458 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4459 bool force) {
4460 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4461 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4462 if (force || should_allocate) {
4463 HeapRegion* new_alloc_region = new_region(word_size,
4464 false /* is_old */,
4465 false /* do_expand */);
4466 if (new_alloc_region != NULL) {
4467 set_region_short_lived_locked(new_alloc_region);
4468 _hr_printer.alloc(new_alloc_region, !should_allocate);
4469 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4470 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4471 return new_alloc_region;
4472 }
4473 }
4474 return NULL;
4475 }
4476
4477 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4478 size_t allocated_bytes) {
4479 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4480 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4481
4482 collection_set()->add_eden_region(alloc_region);
4483 increase_used(allocated_bytes);
4484 _hr_printer.retire(alloc_region);
4485 // We update the eden sizes here, when the region is retired,
4486 // instead of when it's allocated, since this is the point that its
4487 // used space has been recorded in _summary_bytes_used.
4488 g1mm()->update_eden_size();
4489 }
4490
4491 // Methods for the GC alloc regions
4492
4493 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4494 if (dest.is_old()) {
4495 return true;
4496 } else {
4497 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4498 }
4499 }
4500
4501 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4502 assert(FreeList_lock->owned_by_self(), "pre-condition");
4503
4504 if (!has_more_regions(dest)) {
4505 return NULL;
4506 }
4507
4508 const bool is_survivor = dest.is_young();
4509
4510 HeapRegion* new_alloc_region = new_region(word_size,
4511 !is_survivor,
4512 true /* do_expand */);
4513 if (new_alloc_region != NULL) {
4514 if (is_survivor) {
4515 new_alloc_region->set_survivor();
4516 _survivor.add(new_alloc_region);
4517 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4518 } else {
4519 new_alloc_region->set_old();
4520 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4521 }
4522 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4523 _hr_printer.alloc(new_alloc_region);
4524 bool during_im = collector_state()->in_initial_mark_gc();
4525 new_alloc_region->note_start_of_copying(during_im);
4526 return new_alloc_region;
4527 }
4528 return NULL;
4529 }
4530
4531 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4532 size_t allocated_bytes,
4533 InCSetState dest) {
4534 bool during_im = collector_state()->in_initial_mark_gc();
4535 alloc_region->note_end_of_copying(during_im);
4536 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4537 if (dest.is_old()) {
4538 old_set_add(alloc_region);
4539 }
4540 _hr_printer.retire(alloc_region);
4541 }
4542
4543 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4544 bool expanded = false;
4545 uint index = _hrm.find_highest_free(&expanded);
4546
4547 if (index != G1_NO_HRM_INDEX) {
4548 if (expanded) {
4549 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4550 HeapRegion::GrainWords * HeapWordSize);
4551 }
4552 _hrm.allocate_free_regions_starting_at(index, 1);
4553 return region_at(index);
4554 }
4555 return NULL;
4556 }
4557
4558 // Optimized nmethod scanning
4559
4560 class RegisterNMethodOopClosure: public OopClosure {
4561 G1CollectedHeap* _g1h;
4562 nmethod* _nm;
4563
4564 template <class T> void do_oop_work(T* p) {
4565 T heap_oop = RawAccess<>::oop_load(p);
4566 if (!CompressedOops::is_null(heap_oop)) {
4567 oop obj = CompressedOops::decode_not_null(heap_oop);
4568 HeapRegion* hr = _g1h->heap_region_containing(obj);
4569 assert(!hr->is_continues_humongous(),
4570 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4571 " starting at " HR_FORMAT,
4572 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4573
4574 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4575 hr->add_strong_code_root_locked(_nm);
4576 }
4577 }
4578
4579 public:
4580 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4581 _g1h(g1h), _nm(nm) {}
4582
4583 void do_oop(oop* p) { do_oop_work(p); }
4584 void do_oop(narrowOop* p) { do_oop_work(p); }
4585 };
4586
4587 class UnregisterNMethodOopClosure: public OopClosure {
4588 G1CollectedHeap* _g1h;
4589 nmethod* _nm;
4590
4591 template <class T> void do_oop_work(T* p) {
4592 T heap_oop = RawAccess<>::oop_load(p);
4593 if (!CompressedOops::is_null(heap_oop)) {
4594 oop obj = CompressedOops::decode_not_null(heap_oop);
4595 HeapRegion* hr = _g1h->heap_region_containing(obj);
4596 assert(!hr->is_continues_humongous(),
4597 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4598 " starting at " HR_FORMAT,
4599 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4600
4601 hr->remove_strong_code_root(_nm);
4602 }
4603 }
4604
4605 public:
4606 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4607 _g1h(g1h), _nm(nm) {}
4608
4609 void do_oop(oop* p) { do_oop_work(p); }
4610 void do_oop(narrowOop* p) { do_oop_work(p); }
4611 };
4612
4613 // Returns true if the reference points to an object that
4614 // can move in an incremental collection.
4615 bool G1CollectedHeap::is_scavengable(oop obj) {
4616 HeapRegion* hr = heap_region_containing(obj);
4617 return !hr->is_pinned();
4618 }
4619
4620 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4621 guarantee(nm != NULL, "sanity");
4622 RegisterNMethodOopClosure reg_cl(this, nm);
4623 nm->oops_do(®_cl);
4624 }
4625
4626 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4627 guarantee(nm != NULL, "sanity");
4628 UnregisterNMethodOopClosure reg_cl(this, nm);
4629 nm->oops_do(®_cl, true);
4630 }
4631
4632 void G1CollectedHeap::purge_code_root_memory() {
4633 double purge_start = os::elapsedTime();
4634 G1CodeRootSet::purge();
4635 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4636 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4637 }
4638
4639 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4640 G1CollectedHeap* _g1h;
4641
4642 public:
4643 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4644 _g1h(g1h) {}
4645
4646 void do_code_blob(CodeBlob* cb) {
4647 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4648 if (nm == NULL) {
4649 return;
4650 }
4651
4652 if (ScavengeRootsInCode) {
4653 _g1h->register_nmethod(nm);
4654 }
4655 }
4656 };
4657
4658 void G1CollectedHeap::rebuild_strong_code_roots() {
4659 RebuildStrongCodeRootClosure blob_cl(this);
4660 CodeCache::blobs_do(&blob_cl);
4661 }
4662
4663 void G1CollectedHeap::initialize_serviceability() {
4664 _g1mm->initialize_serviceability();
4665 }
4666
4667 MemoryUsage G1CollectedHeap::memory_usage() {
4668 return _g1mm->memory_usage();
4669 }
4670
4671 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4672 return _g1mm->memory_managers();
4673 }
4674
4675 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4676 return _g1mm->memory_pools();
4677 }