1 /*
2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/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/g1StringDedup.hpp"
56 #include "gc/g1/g1ThreadLocalData.hpp"
57 #include "gc/g1/g1YCTypes.hpp"
58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
59 #include "gc/g1/heapRegion.inline.hpp"
60 #include "gc/g1/heapRegionRemSet.hpp"
61 #include "gc/g1/heapRegionSet.inline.hpp"
62 #include "gc/g1/vm_operations_g1.hpp"
63 #include "gc/shared/adaptiveSizePolicy.hpp"
64 #include "gc/shared/gcHeapSummary.hpp"
65 #include "gc/shared/gcId.hpp"
66 #include "gc/shared/gcLocker.hpp"
67 #include "gc/shared/gcTimer.hpp"
68 #include "gc/shared/gcTrace.hpp"
69 #include "gc/shared/gcTraceTime.inline.hpp"
70 #include "gc/shared/generationSpec.hpp"
71 #include "gc/shared/isGCActiveMark.hpp"
72 #include "gc/shared/oopStorageParState.hpp"
73 #include "gc/shared/preservedMarks.inline.hpp"
74 #include "gc/shared/suspendibleThreadSet.hpp"
75 #include "gc/shared/referenceProcessor.inline.hpp"
76 #include "gc/shared/taskqueue.inline.hpp"
77 #include "gc/shared/weakProcessor.hpp"
78 #include "logging/log.hpp"
79 #include "memory/allocation.hpp"
80 #include "memory/iterator.hpp"
81 #include "memory/resourceArea.hpp"
82 #include "oops/access.inline.hpp"
83 #include "oops/compressedOops.inline.hpp"
84 #include "oops/oop.inline.hpp"
85 #include "prims/resolvedMethodTable.hpp"
86 #include "runtime/atomic.hpp"
87 #include "runtime/flags/flagSetting.hpp"
88 #include "runtime/handles.inline.hpp"
89 #include "runtime/init.hpp"
90 #include "runtime/orderAccess.hpp"
91 #include "runtime/threadSMR.hpp"
92 #include "runtime/vmThread.hpp"
93 #include "utilities/align.hpp"
94 #include "utilities/globalDefinitions.hpp"
95 #include "utilities/stack.inline.hpp"
96
97 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
98
99 // INVARIANTS/NOTES
100 //
101 // All allocation activity covered by the G1CollectedHeap interface is
102 // serialized by acquiring the HeapLock. This happens in mem_allocate
103 // and allocate_new_tlab, which are the "entry" points to the
104 // allocation code from the rest of the JVM. (Note that this does not
105 // apply to TLAB allocation, which is not part of this interface: it
106 // is done by clients of this interface.)
107
108 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
109 private:
110 size_t _num_dirtied;
111 G1CollectedHeap* _g1h;
112 G1CardTable* _g1_ct;
113
114 HeapRegion* region_for_card(jbyte* card_ptr) const {
115 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
116 }
117
118 bool will_become_free(HeapRegion* hr) const {
119 // A region will be freed by free_collection_set if the region is in the
120 // collection set and has not had an evacuation failure.
121 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
122 }
123
124 public:
125 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
126 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
127
128 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
129 HeapRegion* hr = region_for_card(card_ptr);
130
131 // Should only dirty cards in regions that won't be freed.
132 if (!will_become_free(hr)) {
133 *card_ptr = G1CardTable::dirty_card_val();
134 _num_dirtied++;
135 }
136
137 return true;
138 }
139
140 size_t num_dirtied() const { return _num_dirtied; }
141 };
142
143
144 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
145 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
146 }
147
148 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
149 // The from card cache is not the memory that is actually committed. So we cannot
150 // take advantage of the zero_filled parameter.
151 reset_from_card_cache(start_idx, num_regions);
152 }
153
154
155 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
156 MemRegion mr) {
157 return new HeapRegion(hrs_index, bot(), mr);
158 }
159
160 // Private methods.
161
162 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
163 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
164 "the only time we use this to allocate a humongous region is "
165 "when we are allocating a single humongous region");
166
167 HeapRegion* res = _hrm.allocate_free_region(is_old);
168
169 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
170 // Currently, only attempts to allocate GC alloc regions set
171 // do_expand to true. So, we should only reach here during a
172 // safepoint. If this assumption changes we might have to
173 // reconsider the use of _expand_heap_after_alloc_failure.
174 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
175
176 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
177 word_size * HeapWordSize);
178
179 if (expand(word_size * HeapWordSize)) {
180 // Given that expand() succeeded in expanding the heap, and we
181 // always expand the heap by an amount aligned to the heap
182 // region size, the free list should in theory not be empty.
183 // In either case allocate_free_region() will check for NULL.
184 res = _hrm.allocate_free_region(is_old);
185 } else {
186 _expand_heap_after_alloc_failure = false;
187 }
188 }
189 return res;
190 }
191
192 HeapWord*
193 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
194 uint num_regions,
195 size_t word_size) {
196 assert(first != G1_NO_HRM_INDEX, "pre-condition");
197 assert(is_humongous(word_size), "word_size should be humongous");
198 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
199
200 // Index of last region in the series.
201 uint last = first + num_regions - 1;
202
203 // We need to initialize the region(s) we just discovered. This is
204 // a bit tricky given that it can happen concurrently with
205 // refinement threads refining cards on these regions and
206 // potentially wanting to refine the BOT as they are scanning
207 // those cards (this can happen shortly after a cleanup; see CR
208 // 6991377). So we have to set up the region(s) carefully and in
209 // a specific order.
210
211 // The word size sum of all the regions we will allocate.
212 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
213 assert(word_size <= word_size_sum, "sanity");
214
215 // This will be the "starts humongous" region.
216 HeapRegion* first_hr = region_at(first);
217 // The header of the new object will be placed at the bottom of
218 // the first region.
219 HeapWord* new_obj = first_hr->bottom();
220 // This will be the new top of the new object.
221 HeapWord* obj_top = new_obj + word_size;
222
223 // First, we need to zero the header of the space that we will be
224 // allocating. When we update top further down, some refinement
225 // threads might try to scan the region. By zeroing the header we
226 // ensure that any thread that will try to scan the region will
227 // come across the zero klass word and bail out.
228 //
229 // NOTE: It would not have been correct to have used
230 // CollectedHeap::fill_with_object() and make the space look like
231 // an int array. The thread that is doing the allocation will
232 // later update the object header to a potentially different array
233 // type and, for a very short period of time, the klass and length
234 // fields will be inconsistent. This could cause a refinement
235 // thread to calculate the object size incorrectly.
236 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
237
238 // Next, pad out the unused tail of the last region with filler
239 // objects, for improved usage accounting.
240 // How many words we use for filler objects.
241 size_t word_fill_size = word_size_sum - word_size;
242
243 // How many words memory we "waste" which cannot hold a filler object.
244 size_t words_not_fillable = 0;
245
246 if (word_fill_size >= min_fill_size()) {
247 fill_with_objects(obj_top, word_fill_size);
248 } else if (word_fill_size > 0) {
249 // We have space to fill, but we cannot fit an object there.
250 words_not_fillable = word_fill_size;
251 word_fill_size = 0;
252 }
253
254 // We will set up the first region as "starts humongous". This
255 // will also update the BOT covering all the regions to reflect
256 // that there is a single object that starts at the bottom of the
257 // first region.
258 first_hr->set_starts_humongous(obj_top, word_fill_size);
259 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
260 // Then, if there are any, we will set up the "continues
261 // humongous" regions.
262 HeapRegion* hr = NULL;
263 for (uint i = first + 1; i <= last; ++i) {
264 hr = region_at(i);
265 hr->set_continues_humongous(first_hr);
266 _g1_policy->remset_tracker()->update_at_allocate(hr);
267 }
268
269 // Up to this point no concurrent thread would have been able to
270 // do any scanning on any region in this series. All the top
271 // fields still point to bottom, so the intersection between
272 // [bottom,top] and [card_start,card_end] will be empty. Before we
273 // update the top fields, we'll do a storestore to make sure that
274 // no thread sees the update to top before the zeroing of the
275 // object header and the BOT initialization.
276 OrderAccess::storestore();
277
278 // Now, we will update the top fields of the "continues humongous"
279 // regions except the last one.
280 for (uint i = first; i < last; ++i) {
281 hr = region_at(i);
282 hr->set_top(hr->end());
283 }
284
285 hr = region_at(last);
286 // If we cannot fit a filler object, we must set top to the end
287 // of the humongous object, otherwise we cannot iterate the heap
288 // and the BOT will not be complete.
289 hr->set_top(hr->end() - words_not_fillable);
290
291 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
292 "obj_top should be in last region");
293
294 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
295
296 assert(words_not_fillable == 0 ||
297 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
298 "Miscalculation in humongous allocation");
299
300 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
301
302 for (uint i = first; i <= last; ++i) {
303 hr = region_at(i);
304 _humongous_set.add(hr);
305 _hr_printer.alloc(hr);
306 }
307
308 return new_obj;
309 }
310
311 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
312 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
313 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
314 }
315
316 // If could fit into free regions w/o expansion, try.
317 // Otherwise, if can expand, do so.
318 // Otherwise, if using ex regions might help, try with ex given back.
319 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
320 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
321
322 _verifier->verify_region_sets_optional();
323
324 uint first = G1_NO_HRM_INDEX;
325 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
326
327 if (obj_regions == 1) {
328 // Only one region to allocate, try to use a fast path by directly allocating
329 // from the free lists. Do not try to expand here, we will potentially do that
330 // later.
331 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
332 if (hr != NULL) {
333 first = hr->hrm_index();
334 }
335 } else {
336 // Policy: Try only empty regions (i.e. already committed first). Maybe we
337 // are lucky enough to find some.
338 first = _hrm.find_contiguous_only_empty(obj_regions);
339 if (first != G1_NO_HRM_INDEX) {
340 _hrm.allocate_free_regions_starting_at(first, obj_regions);
341 }
342 }
343
344 if (first == G1_NO_HRM_INDEX) {
345 // Policy: We could not find enough regions for the humongous object in the
346 // free list. Look through the heap to find a mix of free and uncommitted regions.
347 // If so, try expansion.
348 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
349 if (first != G1_NO_HRM_INDEX) {
350 // We found something. Make sure these regions are committed, i.e. expand
351 // the heap. Alternatively we could do a defragmentation GC.
352 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
353 word_size * HeapWordSize);
354
355 _hrm.expand_at(first, obj_regions, workers());
356 g1_policy()->record_new_heap_size(num_regions());
357
358 #ifdef ASSERT
359 for (uint i = first; i < first + obj_regions; ++i) {
360 HeapRegion* hr = region_at(i);
361 assert(hr->is_free(), "sanity");
362 assert(hr->is_empty(), "sanity");
363 assert(is_on_master_free_list(hr), "sanity");
364 }
365 #endif
366 _hrm.allocate_free_regions_starting_at(first, obj_regions);
367 } else {
368 // Policy: Potentially trigger a defragmentation GC.
369 }
370 }
371
372 HeapWord* result = NULL;
373 if (first != G1_NO_HRM_INDEX) {
374 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
375 assert(result != NULL, "it should always return a valid result");
376
377 // A successful humongous object allocation changes the used space
378 // information of the old generation so we need to recalculate the
379 // sizes and update the jstat counters here.
380 g1mm()->update_sizes();
381 }
382
383 _verifier->verify_region_sets_optional();
384
385 return result;
386 }
387
388 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
389 size_t requested_size,
390 size_t* actual_size) {
391 assert_heap_not_locked_and_not_at_safepoint();
392 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
393
394 return attempt_allocation(min_size, requested_size, actual_size);
395 }
396
397 HeapWord*
398 G1CollectedHeap::mem_allocate(size_t word_size,
399 bool* gc_overhead_limit_was_exceeded) {
400 assert_heap_not_locked_and_not_at_safepoint();
401
402 if (is_humongous(word_size)) {
403 return attempt_allocation_humongous(word_size);
404 }
405 size_t dummy = 0;
406 return attempt_allocation(word_size, word_size, &dummy);
407 }
408
409 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
410 ResourceMark rm; // For retrieving the thread names in log messages.
411
412 // Make sure you read the note in attempt_allocation_humongous().
413
414 assert_heap_not_locked_and_not_at_safepoint();
415 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
416 "be called for humongous allocation requests");
417
418 // We should only get here after the first-level allocation attempt
419 // (attempt_allocation()) failed to allocate.
420
421 // We will loop until a) we manage to successfully perform the
422 // allocation or b) we successfully schedule a collection which
423 // fails to perform the allocation. b) is the only case when we'll
424 // return NULL.
425 HeapWord* result = NULL;
426 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
427 bool should_try_gc;
428 uint gc_count_before;
429
430 {
431 MutexLockerEx x(Heap_lock);
432 result = _allocator->attempt_allocation_locked(word_size);
433 if (result != NULL) {
434 return result;
435 }
436
437 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
438 // This is different to when only GCLocker::needs_gc() is set: try to avoid
439 // waiting because the GCLocker is active to not wait too long.
440 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
441 // No need for an ergo message here, can_expand_young_list() does this when
442 // it returns true.
443 result = _allocator->attempt_allocation_force(word_size);
444 if (result != NULL) {
445 return result;
446 }
447 }
448 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
449 // the GCLocker initiated GC has been performed and then retry. This includes
450 // the case when the GC Locker is not active but has not been performed.
451 should_try_gc = !GCLocker::needs_gc();
452 // Read the GC count while still holding the Heap_lock.
453 gc_count_before = total_collections();
454 }
455
456 if (should_try_gc) {
457 bool succeeded;
458 result = do_collection_pause(word_size, gc_count_before, &succeeded,
459 GCCause::_g1_inc_collection_pause);
460 if (result != NULL) {
461 assert(succeeded, "only way to get back a non-NULL result");
462 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
463 Thread::current()->name(), p2i(result));
464 return result;
465 }
466
467 if (succeeded) {
468 // We successfully scheduled a collection which failed to allocate. No
469 // point in trying to allocate further. We'll just return NULL.
470 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
471 SIZE_FORMAT " words", Thread::current()->name(), word_size);
472 return NULL;
473 }
474 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
475 Thread::current()->name(), word_size);
476 } else {
477 // Failed to schedule a collection.
478 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
479 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
480 SIZE_FORMAT " words", Thread::current()->name(), word_size);
481 return NULL;
482 }
483 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
484 // The GCLocker is either active or the GCLocker initiated
485 // GC has not yet been performed. Stall until it is and
486 // then retry the allocation.
487 GCLocker::stall_until_clear();
488 gclocker_retry_count += 1;
489 }
490
491 // We can reach here if we were unsuccessful in scheduling a
492 // collection (because another thread beat us to it) or if we were
493 // stalled due to the GC locker. In either can we should retry the
494 // allocation attempt in case another thread successfully
495 // performed a collection and reclaimed enough space. We do the
496 // first attempt (without holding the Heap_lock) here and the
497 // follow-on attempt will be at the start of the next loop
498 // iteration (after taking the Heap_lock).
499 size_t dummy = 0;
500 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
501 if (result != NULL) {
502 return result;
503 }
504
505 // Give a warning if we seem to be looping forever.
506 if ((QueuedAllocationWarningCount > 0) &&
507 (try_count % QueuedAllocationWarningCount == 0)) {
508 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
509 Thread::current()->name(), try_count, word_size);
510 }
511 }
512
513 ShouldNotReachHere();
514 return NULL;
515 }
516
517 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
518 assert_at_safepoint_on_vm_thread();
519 if (_archive_allocator == NULL) {
520 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
521 }
522 }
523
524 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
525 // Allocations in archive regions cannot be of a size that would be considered
526 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
527 // may be different at archive-restore time.
528 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
529 }
530
531 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
532 assert_at_safepoint_on_vm_thread();
533 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
534 if (is_archive_alloc_too_large(word_size)) {
535 return NULL;
536 }
537 return _archive_allocator->archive_mem_allocate(word_size);
538 }
539
540 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
541 size_t end_alignment_in_bytes) {
542 assert_at_safepoint_on_vm_thread();
543 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
544
545 // Call complete_archive to do the real work, filling in the MemRegion
546 // array with the archive regions.
547 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
548 delete _archive_allocator;
549 _archive_allocator = NULL;
550 }
551
552 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
553 assert(ranges != NULL, "MemRegion array NULL");
554 assert(count != 0, "No MemRegions provided");
555 MemRegion reserved = _hrm.reserved();
556 for (size_t i = 0; i < count; i++) {
557 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
558 return false;
559 }
560 }
561 return true;
562 }
563
564 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
565 size_t count,
566 bool open) {
567 assert(!is_init_completed(), "Expect to be called at JVM init time");
568 assert(ranges != NULL, "MemRegion array NULL");
569 assert(count != 0, "No MemRegions provided");
570 MutexLockerEx x(Heap_lock);
571
572 MemRegion reserved = _hrm.reserved();
573 HeapWord* prev_last_addr = NULL;
574 HeapRegion* prev_last_region = NULL;
575
576 // Temporarily disable pretouching of heap pages. This interface is used
577 // when mmap'ing archived heap data in, so pre-touching is wasted.
578 FlagSetting fs(AlwaysPreTouch, false);
579
580 // Enable archive object checking used by G1MarkSweep. We have to let it know
581 // about each archive range, so that objects in those ranges aren't marked.
582 G1ArchiveAllocator::enable_archive_object_check();
583
584 // For each specified MemRegion range, allocate the corresponding G1
585 // regions and mark them as archive regions. We expect the ranges
586 // in ascending starting address order, without overlap.
587 for (size_t i = 0; i < count; i++) {
588 MemRegion curr_range = ranges[i];
589 HeapWord* start_address = curr_range.start();
590 size_t word_size = curr_range.word_size();
591 HeapWord* last_address = curr_range.last();
592 size_t commits = 0;
593
594 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
595 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
596 p2i(start_address), p2i(last_address));
597 guarantee(start_address > prev_last_addr,
598 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
599 p2i(start_address), p2i(prev_last_addr));
600 prev_last_addr = last_address;
601
602 // Check for ranges that start in the same G1 region in which the previous
603 // range ended, and adjust the start address so we don't try to allocate
604 // the same region again. If the current range is entirely within that
605 // region, skip it, just adjusting the recorded top.
606 HeapRegion* start_region = _hrm.addr_to_region(start_address);
607 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
608 start_address = start_region->end();
609 if (start_address > last_address) {
610 increase_used(word_size * HeapWordSize);
611 start_region->set_top(last_address + 1);
612 continue;
613 }
614 start_region->set_top(start_address);
615 curr_range = MemRegion(start_address, last_address + 1);
616 start_region = _hrm.addr_to_region(start_address);
617 }
618
619 // Perform the actual region allocation, exiting if it fails.
620 // Then note how much new space we have allocated.
621 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
622 return false;
623 }
624 increase_used(word_size * HeapWordSize);
625 if (commits != 0) {
626 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
627 HeapRegion::GrainWords * HeapWordSize * commits);
628
629 }
630
631 // Mark each G1 region touched by the range as archive, add it to
632 // the old set, and set top.
633 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
634 HeapRegion* last_region = _hrm.addr_to_region(last_address);
635 prev_last_region = last_region;
636
637 while (curr_region != NULL) {
638 assert(curr_region->is_empty() && !curr_region->is_pinned(),
639 "Region already in use (index %u)", curr_region->hrm_index());
640 if (open) {
641 curr_region->set_open_archive();
642 } else {
643 curr_region->set_closed_archive();
644 }
645 _hr_printer.alloc(curr_region);
646 _old_set.add(curr_region);
647 HeapWord* top;
648 HeapRegion* next_region;
649 if (curr_region != last_region) {
650 top = curr_region->end();
651 next_region = _hrm.next_region_in_heap(curr_region);
652 } else {
653 top = last_address + 1;
654 next_region = NULL;
655 }
656 curr_region->set_top(top);
657 curr_region->set_first_dead(top);
658 curr_region->set_end_of_live(top);
659 curr_region = next_region;
660 }
661
662 // Notify mark-sweep of the archive
663 G1ArchiveAllocator::set_range_archive(curr_range, open);
664 }
665 return true;
666 }
667
668 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
669 assert(!is_init_completed(), "Expect to be called at JVM init time");
670 assert(ranges != NULL, "MemRegion array NULL");
671 assert(count != 0, "No MemRegions provided");
672 MemRegion reserved = _hrm.reserved();
673 HeapWord *prev_last_addr = NULL;
674 HeapRegion* prev_last_region = NULL;
675
676 // For each MemRegion, create filler objects, if needed, in the G1 regions
677 // that contain the address range. The address range actually within the
678 // MemRegion will not be modified. That is assumed to have been initialized
679 // elsewhere, probably via an mmap of archived heap data.
680 MutexLockerEx x(Heap_lock);
681 for (size_t i = 0; i < count; i++) {
682 HeapWord* start_address = ranges[i].start();
683 HeapWord* last_address = ranges[i].last();
684
685 assert(reserved.contains(start_address) && reserved.contains(last_address),
686 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
687 p2i(start_address), p2i(last_address));
688 assert(start_address > prev_last_addr,
689 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
690 p2i(start_address), p2i(prev_last_addr));
691
692 HeapRegion* start_region = _hrm.addr_to_region(start_address);
693 HeapRegion* last_region = _hrm.addr_to_region(last_address);
694 HeapWord* bottom_address = start_region->bottom();
695
696 // Check for a range beginning in the same region in which the
697 // previous one ended.
698 if (start_region == prev_last_region) {
699 bottom_address = prev_last_addr + 1;
700 }
701
702 // Verify that the regions were all marked as archive regions by
703 // alloc_archive_regions.
704 HeapRegion* curr_region = start_region;
705 while (curr_region != NULL) {
706 guarantee(curr_region->is_archive(),
707 "Expected archive region at index %u", curr_region->hrm_index());
708 if (curr_region != last_region) {
709 curr_region = _hrm.next_region_in_heap(curr_region);
710 } else {
711 curr_region = NULL;
712 }
713 }
714
715 prev_last_addr = last_address;
716 prev_last_region = last_region;
717
718 // Fill the memory below the allocated range with dummy object(s),
719 // if the region bottom does not match the range start, or if the previous
720 // range ended within the same G1 region, and there is a gap.
721 if (start_address != bottom_address) {
722 size_t fill_size = pointer_delta(start_address, bottom_address);
723 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
724 increase_used(fill_size * HeapWordSize);
725 }
726 }
727 }
728
729 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
730 size_t desired_word_size,
731 size_t* actual_word_size) {
732 assert_heap_not_locked_and_not_at_safepoint();
733 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
734 "be called for humongous allocation requests");
735
736 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
737
738 if (result == NULL) {
739 *actual_word_size = desired_word_size;
740 result = attempt_allocation_slow(desired_word_size);
741 }
742
743 assert_heap_not_locked();
744 if (result != NULL) {
745 assert(*actual_word_size != 0, "Actual size must have been set here");
746 dirty_young_block(result, *actual_word_size);
747 } else {
748 *actual_word_size = 0;
749 }
750
751 return result;
752 }
753
754 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
755 assert(!is_init_completed(), "Expect to be called at JVM init time");
756 assert(ranges != NULL, "MemRegion array NULL");
757 assert(count != 0, "No MemRegions provided");
758 MemRegion reserved = _hrm.reserved();
759 HeapWord* prev_last_addr = NULL;
760 HeapRegion* prev_last_region = NULL;
761 size_t size_used = 0;
762 size_t uncommitted_regions = 0;
763
764 // For each Memregion, free the G1 regions that constitute it, and
765 // notify mark-sweep that the range is no longer to be considered 'archive.'
766 MutexLockerEx x(Heap_lock);
767 for (size_t i = 0; i < count; i++) {
768 HeapWord* start_address = ranges[i].start();
769 HeapWord* last_address = ranges[i].last();
770
771 assert(reserved.contains(start_address) && reserved.contains(last_address),
772 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
773 p2i(start_address), p2i(last_address));
774 assert(start_address > prev_last_addr,
775 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
776 p2i(start_address), p2i(prev_last_addr));
777 size_used += ranges[i].byte_size();
778 prev_last_addr = last_address;
779
780 HeapRegion* start_region = _hrm.addr_to_region(start_address);
781 HeapRegion* last_region = _hrm.addr_to_region(last_address);
782
783 // Check for ranges that start in the same G1 region in which the previous
784 // range ended, and adjust the start address so we don't try to free
785 // the same region again. If the current range is entirely within that
786 // region, skip it.
787 if (start_region == prev_last_region) {
788 start_address = start_region->end();
789 if (start_address > last_address) {
790 continue;
791 }
792 start_region = _hrm.addr_to_region(start_address);
793 }
794 prev_last_region = last_region;
795
796 // After verifying that each region was marked as an archive region by
797 // alloc_archive_regions, set it free and empty and uncommit it.
798 HeapRegion* curr_region = start_region;
799 while (curr_region != NULL) {
800 guarantee(curr_region->is_archive(),
801 "Expected archive region at index %u", curr_region->hrm_index());
802 uint curr_index = curr_region->hrm_index();
803 _old_set.remove(curr_region);
804 curr_region->set_free();
805 curr_region->set_top(curr_region->bottom());
806 if (curr_region != last_region) {
807 curr_region = _hrm.next_region_in_heap(curr_region);
808 } else {
809 curr_region = NULL;
810 }
811 _hrm.shrink_at(curr_index, 1);
812 uncommitted_regions++;
813 }
814
815 // Notify mark-sweep that this is no longer an archive range.
816 G1ArchiveAllocator::set_range_archive(ranges[i], false);
817 }
818
819 if (uncommitted_regions != 0) {
820 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
821 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
822 }
823 decrease_used(size_used);
824 }
825
826 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
827 ResourceMark rm; // For retrieving the thread names in log messages.
828
829 // The structure of this method has a lot of similarities to
830 // attempt_allocation_slow(). The reason these two were not merged
831 // into a single one is that such a method would require several "if
832 // allocation is not humongous do this, otherwise do that"
833 // conditional paths which would obscure its flow. In fact, an early
834 // version of this code did use a unified method which was harder to
835 // follow and, as a result, it had subtle bugs that were hard to
836 // track down. So keeping these two methods separate allows each to
837 // be more readable. It will be good to keep these two in sync as
838 // much as possible.
839
840 assert_heap_not_locked_and_not_at_safepoint();
841 assert(is_humongous(word_size), "attempt_allocation_humongous() "
842 "should only be called for humongous allocations");
843
844 // Humongous objects can exhaust the heap quickly, so we should check if we
845 // need to start a marking cycle at each humongous object allocation. We do
846 // the check before we do the actual allocation. The reason for doing it
847 // before the allocation is that we avoid having to keep track of the newly
848 // allocated memory while we do a GC.
849 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
850 word_size)) {
851 collect(GCCause::_g1_humongous_allocation);
852 }
853
854 // We will loop until a) we manage to successfully perform the
855 // allocation or b) we successfully schedule a collection which
856 // fails to perform the allocation. b) is the only case when we'll
857 // return NULL.
858 HeapWord* result = NULL;
859 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
860 bool should_try_gc;
861 uint gc_count_before;
862
863
864 {
865 MutexLockerEx x(Heap_lock);
866
867 // Given that humongous objects are not allocated in young
868 // regions, we'll first try to do the allocation without doing a
869 // collection hoping that there's enough space in the heap.
870 result = humongous_obj_allocate(word_size);
871 if (result != NULL) {
872 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
873 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
874 return result;
875 }
876
877 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
878 // the GCLocker initiated GC has been performed and then retry. This includes
879 // the case when the GC Locker is not active but has not been performed.
880 should_try_gc = !GCLocker::needs_gc();
881 // Read the GC count while still holding the Heap_lock.
882 gc_count_before = total_collections();
883 }
884
885 if (should_try_gc) {
886 bool succeeded;
887 result = do_collection_pause(word_size, gc_count_before, &succeeded,
888 GCCause::_g1_humongous_allocation);
889 if (result != NULL) {
890 assert(succeeded, "only way to get back a non-NULL result");
891 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
892 Thread::current()->name(), p2i(result));
893 return result;
894 }
895
896 if (succeeded) {
897 // We successfully scheduled a collection which failed to allocate. No
898 // point in trying to allocate further. We'll just return NULL.
899 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
900 SIZE_FORMAT " words", Thread::current()->name(), word_size);
901 return NULL;
902 }
903 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
904 Thread::current()->name(), word_size);
905 } else {
906 // Failed to schedule a collection.
907 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
908 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
909 SIZE_FORMAT " words", Thread::current()->name(), word_size);
910 return NULL;
911 }
912 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
913 // The GCLocker is either active or the GCLocker initiated
914 // GC has not yet been performed. Stall until it is and
915 // then retry the allocation.
916 GCLocker::stall_until_clear();
917 gclocker_retry_count += 1;
918 }
919
920
921 // We can reach here if we were unsuccessful in scheduling a
922 // collection (because another thread beat us to it) or if we were
923 // stalled due to the GC locker. In either can we should retry the
924 // allocation attempt in case another thread successfully
925 // performed a collection and reclaimed enough space.
926 // Humongous object allocation always needs a lock, so we wait for the retry
927 // in the next iteration of the loop, unlike for the regular iteration case.
928 // Give a warning if we seem to be looping forever.
929
930 if ((QueuedAllocationWarningCount > 0) &&
931 (try_count % QueuedAllocationWarningCount == 0)) {
932 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
933 Thread::current()->name(), try_count, word_size);
934 }
935 }
936
937 ShouldNotReachHere();
938 return NULL;
939 }
940
941 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
942 bool expect_null_mutator_alloc_region) {
943 assert_at_safepoint_on_vm_thread();
944 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
945 "the current alloc region was unexpectedly found to be non-NULL");
946
947 if (!is_humongous(word_size)) {
948 return _allocator->attempt_allocation_locked(word_size);
949 } else {
950 HeapWord* result = humongous_obj_allocate(word_size);
951 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
952 collector_state()->set_initiate_conc_mark_if_possible(true);
953 }
954 return result;
955 }
956
957 ShouldNotReachHere();
958 }
959
960 class PostCompactionPrinterClosure: public HeapRegionClosure {
961 private:
962 G1HRPrinter* _hr_printer;
963 public:
964 bool do_heap_region(HeapRegion* hr) {
965 assert(!hr->is_young(), "not expecting to find young regions");
966 _hr_printer->post_compaction(hr);
967 return false;
968 }
969
970 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
971 : _hr_printer(hr_printer) { }
972 };
973
974 void G1CollectedHeap::print_hrm_post_compaction() {
975 if (_hr_printer.is_active()) {
976 PostCompactionPrinterClosure cl(hr_printer());
977 heap_region_iterate(&cl);
978 }
979 }
980
981 void G1CollectedHeap::abort_concurrent_cycle() {
982 // If we start the compaction before the CM threads finish
983 // scanning the root regions we might trip them over as we'll
984 // be moving objects / updating references. So let's wait until
985 // they are done. By telling them to abort, they should complete
986 // early.
987 _cm->root_regions()->abort();
988 _cm->root_regions()->wait_until_scan_finished();
989
990 // Disable discovery and empty the discovered lists
991 // for the CM ref processor.
992 _ref_processor_cm->disable_discovery();
993 _ref_processor_cm->abandon_partial_discovery();
994 _ref_processor_cm->verify_no_references_recorded();
995
996 // Abandon current iterations of concurrent marking and concurrent
997 // refinement, if any are in progress.
998 concurrent_mark()->concurrent_cycle_abort();
999 }
1000
1001 void G1CollectedHeap::prepare_heap_for_full_collection() {
1002 // Make sure we'll choose a new allocation region afterwards.
1003 _allocator->release_mutator_alloc_region();
1004 _allocator->abandon_gc_alloc_regions();
1005 g1_rem_set()->cleanupHRRS();
1006
1007 // We may have added regions to the current incremental collection
1008 // set between the last GC or pause and now. We need to clear the
1009 // incremental collection set and then start rebuilding it afresh
1010 // after this full GC.
1011 abandon_collection_set(collection_set());
1012
1013 tear_down_region_sets(false /* free_list_only */);
1014 }
1015
1016 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1017 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1018 assert(used() == recalculate_used(), "Should be equal");
1019 _verifier->verify_region_sets_optional();
1020 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1021 _verifier->check_bitmaps("Full GC Start");
1022 }
1023
1024 void G1CollectedHeap::prepare_heap_for_mutators() {
1025 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1026 ClassLoaderDataGraph::purge();
1027 MetaspaceUtils::verify_metrics();
1028
1029 // Prepare heap for normal collections.
1030 assert(num_free_regions() == 0, "we should not have added any free regions");
1031 rebuild_region_sets(false /* free_list_only */);
1032 abort_refinement();
1033 resize_if_necessary_after_full_collection();
1034
1035 // Rebuild the strong code root lists for each region
1036 rebuild_strong_code_roots();
1037
1038 // Start a new incremental collection set for the next pause
1039 start_new_collection_set();
1040
1041 _allocator->init_mutator_alloc_region();
1042
1043 // Post collection state updates.
1044 MetaspaceGC::compute_new_size();
1045 }
1046
1047 void G1CollectedHeap::abort_refinement() {
1048 if (_hot_card_cache->use_cache()) {
1049 _hot_card_cache->reset_hot_cache();
1050 }
1051
1052 // Discard all remembered set updates.
1053 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1054 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1055 }
1056
1057 void G1CollectedHeap::verify_after_full_collection() {
1058 _hrm.verify_optional();
1059 _verifier->verify_region_sets_optional();
1060 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1061 // Clear the previous marking bitmap, if needed for bitmap verification.
1062 // Note we cannot do this when we clear the next marking bitmap in
1063 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1064 // objects marked during a full GC against the previous bitmap.
1065 // But we need to clear it before calling check_bitmaps below since
1066 // the full GC has compacted objects and updated TAMS but not updated
1067 // the prev bitmap.
1068 if (G1VerifyBitmaps) {
1069 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1070 _cm->clear_prev_bitmap(workers());
1071 }
1072 _verifier->check_bitmaps("Full GC End");
1073
1074 // At this point there should be no regions in the
1075 // entire heap tagged as young.
1076 assert(check_young_list_empty(), "young list should be empty at this point");
1077
1078 // Note: since we've just done a full GC, concurrent
1079 // marking is no longer active. Therefore we need not
1080 // re-enable reference discovery for the CM ref processor.
1081 // That will be done at the start of the next marking cycle.
1082 // We also know that the STW processor should no longer
1083 // discover any new references.
1084 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1085 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1086 _ref_processor_stw->verify_no_references_recorded();
1087 _ref_processor_cm->verify_no_references_recorded();
1088 }
1089
1090 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1091 // Post collection logging.
1092 // We should do this after we potentially resize the heap so
1093 // that all the COMMIT / UNCOMMIT events are generated before
1094 // the compaction events.
1095 print_hrm_post_compaction();
1096 heap_transition->print();
1097 print_heap_after_gc();
1098 print_heap_regions();
1099 #ifdef TRACESPINNING
1100 ParallelTaskTerminator::print_termination_counts();
1101 #endif
1102 }
1103
1104 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1105 bool clear_all_soft_refs) {
1106 assert_at_safepoint_on_vm_thread();
1107
1108 if (GCLocker::check_active_before_gc()) {
1109 // Full GC was not completed.
1110 return false;
1111 }
1112
1113 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1114 soft_ref_policy()->should_clear_all_soft_refs();
1115
1116 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1117 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1118
1119 collector.prepare_collection();
1120 collector.collect();
1121 collector.complete_collection();
1122
1123 // Full collection was successfully completed.
1124 return true;
1125 }
1126
1127 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1128 // Currently, there is no facility in the do_full_collection(bool) API to notify
1129 // the caller that the collection did not succeed (e.g., because it was locked
1130 // out by the GC locker). So, right now, we'll ignore the return value.
1131 bool dummy = do_full_collection(true, /* explicit_gc */
1132 clear_all_soft_refs);
1133 }
1134
1135 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1136 // Capacity, free and used after the GC counted as full regions to
1137 // include the waste in the following calculations.
1138 const size_t capacity_after_gc = capacity();
1139 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1140
1141 // This is enforced in arguments.cpp.
1142 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1143 "otherwise the code below doesn't make sense");
1144
1145 // We don't have floating point command-line arguments
1146 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1147 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1148 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1149 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1150
1151 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1152 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1153
1154 // We have to be careful here as these two calculations can overflow
1155 // 32-bit size_t's.
1156 double used_after_gc_d = (double) used_after_gc;
1157 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1158 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1159
1160 // Let's make sure that they are both under the max heap size, which
1161 // by default will make them fit into a size_t.
1162 double desired_capacity_upper_bound = (double) max_heap_size;
1163 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1164 desired_capacity_upper_bound);
1165 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1166 desired_capacity_upper_bound);
1167
1168 // We can now safely turn them into size_t's.
1169 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1170 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1171
1172 // This assert only makes sense here, before we adjust them
1173 // with respect to the min and max heap size.
1174 assert(minimum_desired_capacity <= maximum_desired_capacity,
1175 "minimum_desired_capacity = " SIZE_FORMAT ", "
1176 "maximum_desired_capacity = " SIZE_FORMAT,
1177 minimum_desired_capacity, maximum_desired_capacity);
1178
1179 // Should not be greater than the heap max size. No need to adjust
1180 // it with respect to the heap min size as it's a lower bound (i.e.,
1181 // we'll try to make the capacity larger than it, not smaller).
1182 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1183 // Should not be less than the heap min size. No need to adjust it
1184 // with respect to the heap max size as it's an upper bound (i.e.,
1185 // we'll try to make the capacity smaller than it, not greater).
1186 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1187
1188 if (capacity_after_gc < minimum_desired_capacity) {
1189 // Don't expand unless it's significant
1190 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1191
1192 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1193 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1194 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1195 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1196
1197 expand(expand_bytes, _workers);
1198
1199 // No expansion, now see if we want to shrink
1200 } else if (capacity_after_gc > maximum_desired_capacity) {
1201 // Capacity too large, compute shrinking size
1202 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1203
1204 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1205 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1206 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1207 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1208
1209 shrink(shrink_bytes);
1210 }
1211 }
1212
1213 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1214 bool do_gc,
1215 bool clear_all_soft_refs,
1216 bool expect_null_mutator_alloc_region,
1217 bool* gc_succeeded) {
1218 *gc_succeeded = true;
1219 // Let's attempt the allocation first.
1220 HeapWord* result =
1221 attempt_allocation_at_safepoint(word_size,
1222 expect_null_mutator_alloc_region);
1223 if (result != NULL) {
1224 return result;
1225 }
1226
1227 // In a G1 heap, we're supposed to keep allocation from failing by
1228 // incremental pauses. Therefore, at least for now, we'll favor
1229 // expansion over collection. (This might change in the future if we can
1230 // do something smarter than full collection to satisfy a failed alloc.)
1231 result = expand_and_allocate(word_size);
1232 if (result != NULL) {
1233 return result;
1234 }
1235
1236 if (do_gc) {
1237 // Expansion didn't work, we'll try to do a Full GC.
1238 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1239 clear_all_soft_refs);
1240 }
1241
1242 return NULL;
1243 }
1244
1245 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1246 bool* succeeded) {
1247 assert_at_safepoint_on_vm_thread();
1248
1249 // Attempts to allocate followed by Full GC.
1250 HeapWord* result =
1251 satisfy_failed_allocation_helper(word_size,
1252 true, /* do_gc */
1253 false, /* clear_all_soft_refs */
1254 false, /* expect_null_mutator_alloc_region */
1255 succeeded);
1256
1257 if (result != NULL || !*succeeded) {
1258 return result;
1259 }
1260
1261 // Attempts to allocate followed by Full GC that will collect all soft references.
1262 result = satisfy_failed_allocation_helper(word_size,
1263 true, /* do_gc */
1264 true, /* clear_all_soft_refs */
1265 true, /* expect_null_mutator_alloc_region */
1266 succeeded);
1267
1268 if (result != NULL || !*succeeded) {
1269 return result;
1270 }
1271
1272 // Attempts to allocate, no GC
1273 result = satisfy_failed_allocation_helper(word_size,
1274 false, /* do_gc */
1275 false, /* clear_all_soft_refs */
1276 true, /* expect_null_mutator_alloc_region */
1277 succeeded);
1278
1279 if (result != NULL) {
1280 return result;
1281 }
1282
1283 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1284 "Flag should have been handled and cleared prior to this point");
1285
1286 // What else? We might try synchronous finalization later. If the total
1287 // space available is large enough for the allocation, then a more
1288 // complete compaction phase than we've tried so far might be
1289 // appropriate.
1290 return NULL;
1291 }
1292
1293 // Attempting to expand the heap sufficiently
1294 // to support an allocation of the given "word_size". If
1295 // successful, perform the allocation and return the address of the
1296 // allocated block, or else "NULL".
1297
1298 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1299 assert_at_safepoint_on_vm_thread();
1300
1301 _verifier->verify_region_sets_optional();
1302
1303 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1304 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1305 word_size * HeapWordSize);
1306
1307
1308 if (expand(expand_bytes, _workers)) {
1309 _hrm.verify_optional();
1310 _verifier->verify_region_sets_optional();
1311 return attempt_allocation_at_safepoint(word_size,
1312 false /* expect_null_mutator_alloc_region */);
1313 }
1314 return NULL;
1315 }
1316
1317 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1318 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1319 aligned_expand_bytes = align_up(aligned_expand_bytes, HeapRegion::GrainBytes);
1320
1321 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1322 expand_bytes, aligned_expand_bytes);
1323
1324 if (is_maximal_no_gc()) {
1325 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1326 return false;
1327 }
1328
1329 double expand_heap_start_time_sec = os::elapsedTime();
1330 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1331 assert(regions_to_expand > 0, "Must expand by at least one region");
1332
1333 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1334 if (expand_time_ms != NULL) {
1335 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1336 }
1337
1338 if (expanded_by > 0) {
1339 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1340 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1341 g1_policy()->record_new_heap_size(num_regions());
1342 } else {
1343 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1344
1345 // The expansion of the virtual storage space was unsuccessful.
1346 // Let's see if it was because we ran out of swap.
1347 if (G1ExitOnExpansionFailure &&
1348 _hrm.available() >= regions_to_expand) {
1349 // We had head room...
1350 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1351 }
1352 }
1353 return regions_to_expand > 0;
1354 }
1355
1356 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1357 size_t aligned_shrink_bytes =
1358 ReservedSpace::page_align_size_down(shrink_bytes);
1359 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1360 HeapRegion::GrainBytes);
1361 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1362
1363 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1364 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1365
1366
1367 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",
1368 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1369 if (num_regions_removed > 0) {
1370 g1_policy()->record_new_heap_size(num_regions());
1371 } else {
1372 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1373 }
1374 }
1375
1376 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1377 _verifier->verify_region_sets_optional();
1378
1379 // We should only reach here at the end of a Full GC which means we
1380 // should not not be holding to any GC alloc regions. The method
1381 // below will make sure of that and do any remaining clean up.
1382 _allocator->abandon_gc_alloc_regions();
1383
1384 // Instead of tearing down / rebuilding the free lists here, we
1385 // could instead use the remove_all_pending() method on free_list to
1386 // remove only the ones that we need to remove.
1387 tear_down_region_sets(true /* free_list_only */);
1388 shrink_helper(shrink_bytes);
1389 rebuild_region_sets(true /* free_list_only */);
1390
1391 _hrm.verify_optional();
1392 _verifier->verify_region_sets_optional();
1393 }
1394
1395 // Public methods.
1396
1397 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1398 CollectedHeap(),
1399 _young_gen_sampling_thread(NULL),
1400 _collector_policy(collector_policy),
1401 _soft_ref_policy(),
1402 _card_table(NULL),
1403 _memory_manager("G1 Young Generation", "end of minor GC"),
1404 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1405 _eden_pool(NULL),
1406 _survivor_pool(NULL),
1407 _old_pool(NULL),
1408 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1409 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1410 _g1_policy(new G1Policy(_gc_timer_stw)),
1411 _collection_set(this, _g1_policy),
1412 _dirty_card_queue_set(false),
1413 _ref_processor_stw(NULL),
1414 _is_alive_closure_stw(this),
1415 _is_subject_to_discovery_stw(this),
1416 _ref_processor_cm(NULL),
1417 _is_alive_closure_cm(this),
1418 _is_subject_to_discovery_cm(this),
1419 _bot(NULL),
1420 _hot_card_cache(NULL),
1421 _g1_rem_set(NULL),
1422 _cr(NULL),
1423 _g1mm(NULL),
1424 _preserved_marks_set(true /* in_c_heap */),
1425 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1426 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1427 _humongous_reclaim_candidates(),
1428 _has_humongous_reclaim_candidates(false),
1429 _archive_allocator(NULL),
1430 _summary_bytes_used(0),
1431 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1432 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1433 _expand_heap_after_alloc_failure(true),
1434 _old_marking_cycles_started(0),
1435 _old_marking_cycles_completed(0),
1436 _in_cset_fast_test() {
1437
1438 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1439 /* are_GC_task_threads */true,
1440 /* are_ConcurrentGC_threads */false);
1441 _workers->initialize_workers();
1442 _verifier = new G1HeapVerifier(this);
1443
1444 _allocator = new G1Allocator(this);
1445
1446 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1447
1448 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1449
1450 // Override the default _filler_array_max_size so that no humongous filler
1451 // objects are created.
1452 _filler_array_max_size = _humongous_object_threshold_in_words;
1453
1454 uint n_queues = ParallelGCThreads;
1455 _task_queues = new RefToScanQueueSet(n_queues);
1456
1457 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1458
1459 for (uint i = 0; i < n_queues; i++) {
1460 RefToScanQueue* q = new RefToScanQueue();
1461 q->initialize();
1462 _task_queues->register_queue(i, q);
1463 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1464 }
1465
1466 // Initialize the G1EvacuationFailureALot counters and flags.
1467 NOT_PRODUCT(reset_evacuation_should_fail();)
1468
1469 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1470 }
1471
1472 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1473 size_t size,
1474 size_t translation_factor) {
1475 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1476 // Allocate a new reserved space, preferring to use large pages.
1477 ReservedSpace rs(size, preferred_page_size);
1478 G1RegionToSpaceMapper* result =
1479 G1RegionToSpaceMapper::create_mapper(rs,
1480 size,
1481 rs.alignment(),
1482 HeapRegion::GrainBytes,
1483 translation_factor,
1484 mtGC);
1485
1486 os::trace_page_sizes_for_requested_size(description,
1487 size,
1488 preferred_page_size,
1489 rs.alignment(),
1490 rs.base(),
1491 rs.size());
1492
1493 return result;
1494 }
1495
1496 jint G1CollectedHeap::initialize_concurrent_refinement() {
1497 jint ecode = JNI_OK;
1498 _cr = G1ConcurrentRefine::create(&ecode);
1499 return ecode;
1500 }
1501
1502 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1503 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1504 if (_young_gen_sampling_thread->osthread() == NULL) {
1505 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1506 return JNI_ENOMEM;
1507 }
1508 return JNI_OK;
1509 }
1510
1511 jint G1CollectedHeap::initialize() {
1512 os::enable_vtime();
1513
1514 // Necessary to satisfy locking discipline assertions.
1515
1516 MutexLocker x(Heap_lock);
1517
1518 // While there are no constraints in the GC code that HeapWordSize
1519 // be any particular value, there are multiple other areas in the
1520 // system which believe this to be true (e.g. oop->object_size in some
1521 // cases incorrectly returns the size in wordSize units rather than
1522 // HeapWordSize).
1523 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1524
1525 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1526 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1527 size_t heap_alignment = collector_policy()->heap_alignment();
1528
1529 // Ensure that the sizes are properly aligned.
1530 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1531 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1532 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1533
1534 // Reserve the maximum.
1535
1536 // When compressed oops are enabled, the preferred heap base
1537 // is calculated by subtracting the requested size from the
1538 // 32Gb boundary and using the result as the base address for
1539 // heap reservation. If the requested size is not aligned to
1540 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1541 // into the ReservedHeapSpace constructor) then the actual
1542 // base of the reserved heap may end up differing from the
1543 // address that was requested (i.e. the preferred heap base).
1544 // If this happens then we could end up using a non-optimal
1545 // compressed oops mode.
1546
1547 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1548 heap_alignment);
1549
1550 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1551
1552 // Create the barrier set for the entire reserved region.
1553 G1CardTable* ct = new G1CardTable(reserved_region());
1554 ct->initialize();
1555 G1BarrierSet* bs = new G1BarrierSet(ct);
1556 bs->initialize();
1557 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1558 BarrierSet::set_barrier_set(bs);
1559 _card_table = ct;
1560
1561 // Create the hot card cache.
1562 _hot_card_cache = new G1HotCardCache(this);
1563
1564 // Carve out the G1 part of the heap.
1565 ReservedSpace g1_rs = heap_rs.first_part(heap_rs.size());
1566 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1567 G1RegionToSpaceMapper* heap_storage =
1568 G1RegionToSpaceMapper::create_mapper(g1_rs,
1569 g1_rs.size(),
1570 page_size,
1571 HeapRegion::GrainBytes,
1572 1,
1573 mtJavaHeap);
1574 os::trace_page_sizes("Heap",
1575 collector_policy()->min_heap_byte_size(),
1576 max_byte_size,
1577 page_size,
1578 heap_rs.base(),
1579 heap_rs.size());
1580 heap_storage->set_mapping_changed_listener(&_listener);
1581
1582 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1583 G1RegionToSpaceMapper* bot_storage =
1584 create_aux_memory_mapper("Block Offset Table",
1585 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1586 G1BlockOffsetTable::heap_map_factor());
1587
1588 G1RegionToSpaceMapper* cardtable_storage =
1589 create_aux_memory_mapper("Card Table",
1590 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1591 G1CardTable::heap_map_factor());
1592
1593 G1RegionToSpaceMapper* card_counts_storage =
1594 create_aux_memory_mapper("Card Counts Table",
1595 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1596 G1CardCounts::heap_map_factor());
1597
1598 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1599 G1RegionToSpaceMapper* prev_bitmap_storage =
1600 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1601 G1RegionToSpaceMapper* next_bitmap_storage =
1602 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1603
1604 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1605 _card_table->initialize(cardtable_storage);
1606 // Do later initialization work for concurrent refinement.
1607 _hot_card_cache->initialize(card_counts_storage);
1608
1609 // 6843694 - ensure that the maximum region index can fit
1610 // in the remembered set structures.
1611 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1612 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1613
1614 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1615 // start within the first card.
1616 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1617 // Also create a G1 rem set.
1618 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1619 _g1_rem_set->initialize(max_capacity(), max_regions());
1620
1621 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1622 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1623 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1624 "too many cards per region");
1625
1626 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1627
1628 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1629
1630 {
1631 HeapWord* start = _hrm.reserved().start();
1632 HeapWord* end = _hrm.reserved().end();
1633 size_t granularity = HeapRegion::GrainBytes;
1634
1635 _in_cset_fast_test.initialize(start, end, granularity);
1636 _humongous_reclaim_candidates.initialize(start, end, granularity);
1637 }
1638
1639 // Create the G1ConcurrentMark data structure and thread.
1640 // (Must do this late, so that "max_regions" is defined.)
1641 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1642 if (_cm == NULL || !_cm->completed_initialization()) {
1643 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1644 return JNI_ENOMEM;
1645 }
1646 _cm_thread = _cm->cm_thread();
1647
1648 // Expand NVDIMM to maximum old gen size.
1649 if (AllocateOldGenAt != NULL) {
1650 int fd_for_heap = -1;
1651 fd_for_heap = os::create_file_for_heap(AllocateOldGenAt);
1652 if (fd_for_heap== -1) {
1653 vm_exit_during_initialization(
1654 err_msg("Could not create file for Heap at location %s", AllocateOldGenAt));
1655 }
1656 // Allocate space on device.
1657 os::allocate_file(fd_for_heap, MaxHeapSize);
1658 os::set_nvdimm_fd(fd_for_heap);
1659 os::set_nvdimm_present(true);
1660 os::set_nvdimm_heapbase((address)(heap_rs.base()));
1661 }
1662 size_t aligned_expand_bytes = 0;
1663 if (os::has_nvdimm()) {
1664 aligned_expand_bytes = expand_old_gen_on_nvdimm(max_byte_size);
1665 }
1666 // Now expand into the initial heap size.
1667 if (!expand(init_byte_size, _workers)) {
1668 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1669 return JNI_ENOMEM;
1670 }
1671
1672 if (os::has_nvdimm()) {
1673 // Show how much memory was committed on NVDIMM and DRAM.
1674 log_info(gc, heap)("NVDIMM Reserved Bytes : %ld DRAM Reserved Bytes : %ld \n", aligned_expand_bytes, init_byte_size);
1675 log_info(gc, heap)("When NVDIMM is present, we always reserve and commit Maximum OldGen Size on NVDIMM");
1676 log_info(gc, heap)("JVM will have more size reserved and committed than specified by Xmn or Xms options (but never more than Xmx).");
1677 }
1678 // Perform any initialization actions delegated to the policy.
1679 g1_policy()->init(this, &_collection_set);
1680
1681 G1BarrierSet::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1682 SATB_Q_FL_lock,
1683 G1SATBProcessCompletedThreshold,
1684 Shared_SATB_Q_lock);
1685
1686 jint ecode = initialize_concurrent_refinement();
1687 if (ecode != JNI_OK) {
1688 return ecode;
1689 }
1690
1691 ecode = initialize_young_gen_sampling_thread();
1692 if (ecode != JNI_OK) {
1693 return ecode;
1694 }
1695
1696 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1697 DirtyCardQ_FL_lock,
1698 (int)concurrent_refine()->yellow_zone(),
1699 (int)concurrent_refine()->red_zone(),
1700 Shared_DirtyCardQ_lock,
1701 NULL, // fl_owner
1702 true); // init_free_ids
1703
1704 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1705 DirtyCardQ_FL_lock,
1706 -1, // never trigger processing
1707 -1, // no limit on length
1708 Shared_DirtyCardQ_lock,
1709 &G1BarrierSet::dirty_card_queue_set());
1710
1711 // Here we allocate the dummy HeapRegion that is required by the
1712 // G1AllocRegion class.
1713 HeapRegion* dummy_region = _hrm.get_dummy_region();
1714
1715 // We'll re-use the same region whether the alloc region will
1716 // require BOT updates or not and, if it doesn't, then a non-young
1717 // region will complain that it cannot support allocations without
1718 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1719 dummy_region->set_eden();
1720 // Make sure it's full.
1721 dummy_region->set_top(dummy_region->end());
1722 G1AllocRegion::setup(this, dummy_region);
1723
1724 _allocator->init_mutator_alloc_region();
1725
1726 // Do create of the monitoring and management support so that
1727 // values in the heap have been properly initialized.
1728 _g1mm = new G1MonitoringSupport(this);
1729
1730 G1StringDedup::initialize();
1731
1732 _preserved_marks_set.init(ParallelGCThreads);
1733
1734 _collection_set.initialize(max_regions());
1735
1736 return JNI_OK;
1737 }
1738
1739 size_t G1CollectedHeap::expand_old_gen_on_nvdimm(size_t max_byte_size) {
1740 size_t nvdimm_bytes = max_byte_size - (size_t)(max_byte_size * G1MaxNewSizePercent)/100;
1741 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(nvdimm_bytes);
1742 aligned_expand_bytes = align_up(aligned_expand_bytes, HeapRegion::GrainBytes);
1743 uint nvdimm_regions = (uint)(aligned_expand_bytes/HeapRegion::GrainBytes);
1744 os::set_nvdimm_regionlength(nvdimm_regions);
1745 expand(aligned_expand_bytes, _workers);
1746 return aligned_expand_bytes;
1747 }
1748
1749 void G1CollectedHeap::initialize_serviceability() {
1750 _eden_pool = new G1EdenPool(this);
1751 _survivor_pool = new G1SurvivorPool(this);
1752 _old_pool = new G1OldGenPool(this);
1753
1754 _full_gc_memory_manager.add_pool(_eden_pool);
1755 _full_gc_memory_manager.add_pool(_survivor_pool);
1756 _full_gc_memory_manager.add_pool(_old_pool);
1757
1758 _memory_manager.add_pool(_eden_pool);
1759 _memory_manager.add_pool(_survivor_pool);
1760
1761 }
1762
1763 void G1CollectedHeap::stop() {
1764 // Stop all concurrent threads. We do this to make sure these threads
1765 // do not continue to execute and access resources (e.g. logging)
1766 // that are destroyed during shutdown.
1767 _cr->stop();
1768 _young_gen_sampling_thread->stop();
1769 _cm_thread->stop();
1770 if (G1StringDedup::is_enabled()) {
1771 G1StringDedup::stop();
1772 }
1773 }
1774
1775 void G1CollectedHeap::safepoint_synchronize_begin() {
1776 SuspendibleThreadSet::synchronize();
1777 }
1778
1779 void G1CollectedHeap::safepoint_synchronize_end() {
1780 SuspendibleThreadSet::desynchronize();
1781 }
1782
1783 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1784 return HeapRegion::max_region_size();
1785 }
1786
1787 void G1CollectedHeap::post_initialize() {
1788 CollectedHeap::post_initialize();
1789 ref_processing_init();
1790 }
1791
1792 void G1CollectedHeap::ref_processing_init() {
1793 // Reference processing in G1 currently works as follows:
1794 //
1795 // * There are two reference processor instances. One is
1796 // used to record and process discovered references
1797 // during concurrent marking; the other is used to
1798 // record and process references during STW pauses
1799 // (both full and incremental).
1800 // * Both ref processors need to 'span' the entire heap as
1801 // the regions in the collection set may be dotted around.
1802 //
1803 // * For the concurrent marking ref processor:
1804 // * Reference discovery is enabled at initial marking.
1805 // * Reference discovery is disabled and the discovered
1806 // references processed etc during remarking.
1807 // * Reference discovery is MT (see below).
1808 // * Reference discovery requires a barrier (see below).
1809 // * Reference processing may or may not be MT
1810 // (depending on the value of ParallelRefProcEnabled
1811 // and ParallelGCThreads).
1812 // * A full GC disables reference discovery by the CM
1813 // ref processor and abandons any entries on it's
1814 // discovered lists.
1815 //
1816 // * For the STW processor:
1817 // * Non MT discovery is enabled at the start of a full GC.
1818 // * Processing and enqueueing during a full GC is non-MT.
1819 // * During a full GC, references are processed after marking.
1820 //
1821 // * Discovery (may or may not be MT) is enabled at the start
1822 // of an incremental evacuation pause.
1823 // * References are processed near the end of a STW evacuation pause.
1824 // * For both types of GC:
1825 // * Discovery is atomic - i.e. not concurrent.
1826 // * Reference discovery will not need a barrier.
1827
1828 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1829
1830 // Concurrent Mark ref processor
1831 _ref_processor_cm =
1832 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1833 mt_processing, // mt processing
1834 ParallelGCThreads, // degree of mt processing
1835 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1836 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1837 false, // Reference discovery is not atomic
1838 &_is_alive_closure_cm); // is alive closure
1839
1840 // STW ref processor
1841 _ref_processor_stw =
1842 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1843 mt_processing, // mt processing
1844 ParallelGCThreads, // degree of mt processing
1845 (ParallelGCThreads > 1), // mt discovery
1846 ParallelGCThreads, // degree of mt discovery
1847 true, // Reference discovery is atomic
1848 &_is_alive_closure_stw); // is alive closure
1849 }
1850
1851 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1852 return _collector_policy;
1853 }
1854
1855 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1856 return &_soft_ref_policy;
1857 }
1858
1859 size_t G1CollectedHeap::capacity() const {
1860 return _hrm.length() * HeapRegion::GrainBytes;
1861 }
1862
1863 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1864 return _hrm.total_free_bytes();
1865 }
1866
1867 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1868 _hot_card_cache->drain(cl, worker_i);
1869 }
1870
1871 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1872 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1873 size_t n_completed_buffers = 0;
1874 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1875 n_completed_buffers++;
1876 }
1877 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1878 dcqs.clear_n_completed_buffers();
1879 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1880 }
1881
1882 // Computes the sum of the storage used by the various regions.
1883 size_t G1CollectedHeap::used() const {
1884 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1885 if (_archive_allocator != NULL) {
1886 result += _archive_allocator->used();
1887 }
1888 return result;
1889 }
1890
1891 size_t G1CollectedHeap::used_unlocked() const {
1892 return _summary_bytes_used;
1893 }
1894
1895 class SumUsedClosure: public HeapRegionClosure {
1896 size_t _used;
1897 public:
1898 SumUsedClosure() : _used(0) {}
1899 bool do_heap_region(HeapRegion* r) {
1900 _used += r->used();
1901 return false;
1902 }
1903 size_t result() { return _used; }
1904 };
1905
1906 size_t G1CollectedHeap::recalculate_used() const {
1907 double recalculate_used_start = os::elapsedTime();
1908
1909 SumUsedClosure blk;
1910 heap_region_iterate(&blk);
1911
1912 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1913 return blk.result();
1914 }
1915
1916 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1917 switch (cause) {
1918 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1919 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1920 case GCCause::_wb_conc_mark: return true;
1921 default : return false;
1922 }
1923 }
1924
1925 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1926 switch (cause) {
1927 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1928 case GCCause::_g1_humongous_allocation: return true;
1929 default: return is_user_requested_concurrent_full_gc(cause);
1930 }
1931 }
1932
1933 #ifndef PRODUCT
1934 void G1CollectedHeap::allocate_dummy_regions() {
1935 // Let's fill up most of the region
1936 size_t word_size = HeapRegion::GrainWords - 1024;
1937 // And as a result the region we'll allocate will be humongous.
1938 guarantee(is_humongous(word_size), "sanity");
1939
1940 // _filler_array_max_size is set to humongous object threshold
1941 // but temporarily change it to use CollectedHeap::fill_with_object().
1942 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1943
1944 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1945 // Let's use the existing mechanism for the allocation
1946 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1947 if (dummy_obj != NULL) {
1948 MemRegion mr(dummy_obj, word_size);
1949 CollectedHeap::fill_with_object(mr);
1950 } else {
1951 // If we can't allocate once, we probably cannot allocate
1952 // again. Let's get out of the loop.
1953 break;
1954 }
1955 }
1956 }
1957 #endif // !PRODUCT
1958
1959 void G1CollectedHeap::increment_old_marking_cycles_started() {
1960 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1961 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1962 "Wrong marking cycle count (started: %d, completed: %d)",
1963 _old_marking_cycles_started, _old_marking_cycles_completed);
1964
1965 _old_marking_cycles_started++;
1966 }
1967
1968 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
1969 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1970
1971 // We assume that if concurrent == true, then the caller is a
1972 // concurrent thread that was joined the Suspendible Thread
1973 // Set. If there's ever a cheap way to check this, we should add an
1974 // assert here.
1975
1976 // Given that this method is called at the end of a Full GC or of a
1977 // concurrent cycle, and those can be nested (i.e., a Full GC can
1978 // interrupt a concurrent cycle), the number of full collections
1979 // completed should be either one (in the case where there was no
1980 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1981 // behind the number of full collections started.
1982
1983 // This is the case for the inner caller, i.e. a Full GC.
1984 assert(concurrent ||
1985 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1986 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1987 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1988 "is inconsistent with _old_marking_cycles_completed = %u",
1989 _old_marking_cycles_started, _old_marking_cycles_completed);
1990
1991 // This is the case for the outer caller, i.e. the concurrent cycle.
1992 assert(!concurrent ||
1993 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1994 "for outer caller (concurrent cycle): "
1995 "_old_marking_cycles_started = %u "
1996 "is inconsistent with _old_marking_cycles_completed = %u",
1997 _old_marking_cycles_started, _old_marking_cycles_completed);
1998
1999 _old_marking_cycles_completed += 1;
2000
2001 // We need to clear the "in_progress" flag in the CM thread before
2002 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2003 // is set) so that if a waiter requests another System.gc() it doesn't
2004 // incorrectly see that a marking cycle is still in progress.
2005 if (concurrent) {
2006 _cm_thread->set_idle();
2007 }
2008
2009 // This notify_all() will ensure that a thread that called
2010 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2011 // and it's waiting for a full GC to finish will be woken up. It is
2012 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2013 FullGCCount_lock->notify_all();
2014 }
2015
2016 void G1CollectedHeap::collect(GCCause::Cause cause) {
2017 assert_heap_not_locked();
2018
2019 uint gc_count_before;
2020 uint old_marking_count_before;
2021 uint full_gc_count_before;
2022 bool retry_gc;
2023
2024 do {
2025 retry_gc = false;
2026
2027 {
2028 MutexLocker ml(Heap_lock);
2029
2030 // Read the GC count while holding the Heap_lock
2031 gc_count_before = total_collections();
2032 full_gc_count_before = total_full_collections();
2033 old_marking_count_before = _old_marking_cycles_started;
2034 }
2035
2036 if (should_do_concurrent_full_gc(cause)) {
2037 // Schedule an initial-mark evacuation pause that will start a
2038 // concurrent cycle. We're setting word_size to 0 which means that
2039 // we are not requesting a post-GC allocation.
2040 VM_G1CollectForAllocation op(0, /* word_size */
2041 gc_count_before,
2042 cause,
2043 true, /* should_initiate_conc_mark */
2044 g1_policy()->max_pause_time_ms());
2045 VMThread::execute(&op);
2046 if (!op.pause_succeeded()) {
2047 if (old_marking_count_before == _old_marking_cycles_started) {
2048 retry_gc = op.should_retry_gc();
2049 } else {
2050 // A Full GC happened while we were trying to schedule the
2051 // initial-mark GC. No point in starting a new cycle given
2052 // that the whole heap was collected anyway.
2053 }
2054
2055 if (retry_gc) {
2056 if (GCLocker::is_active_and_needs_gc()) {
2057 GCLocker::stall_until_clear();
2058 }
2059 }
2060 }
2061 } else {
2062 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2063 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2064
2065 // Schedule a standard evacuation pause. We're setting word_size
2066 // to 0 which means that we are not requesting a post-GC allocation.
2067 VM_G1CollectForAllocation op(0, /* word_size */
2068 gc_count_before,
2069 cause,
2070 false, /* should_initiate_conc_mark */
2071 g1_policy()->max_pause_time_ms());
2072 VMThread::execute(&op);
2073 } else {
2074 // Schedule a Full GC.
2075 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2076 VMThread::execute(&op);
2077 }
2078 }
2079 } while (retry_gc);
2080 }
2081
2082 bool G1CollectedHeap::is_in(const void* p) const {
2083 if (_hrm.reserved().contains(p)) {
2084 // Given that we know that p is in the reserved space,
2085 // heap_region_containing() should successfully
2086 // return the containing region.
2087 HeapRegion* hr = heap_region_containing(p);
2088 return hr->is_in(p);
2089 } else {
2090 return false;
2091 }
2092 }
2093
2094 #ifdef ASSERT
2095 bool G1CollectedHeap::is_in_exact(const void* p) const {
2096 bool contains = reserved_region().contains(p);
2097 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2098 if (contains && available) {
2099 return true;
2100 } else {
2101 return false;
2102 }
2103 }
2104 #endif
2105
2106 // Iteration functions.
2107
2108 // Iterates an ObjectClosure over all objects within a HeapRegion.
2109
2110 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2111 ObjectClosure* _cl;
2112 public:
2113 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2114 bool do_heap_region(HeapRegion* r) {
2115 if (!r->is_continues_humongous()) {
2116 r->object_iterate(_cl);
2117 }
2118 return false;
2119 }
2120 };
2121
2122 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2123 IterateObjectClosureRegionClosure blk(cl);
2124 heap_region_iterate(&blk);
2125 }
2126
2127 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2128 _hrm.iterate(cl);
2129 }
2130
2131 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2132 HeapRegionClaimer *hrclaimer,
2133 uint worker_id) const {
2134 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2135 }
2136
2137 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2138 HeapRegionClaimer *hrclaimer) const {
2139 _hrm.par_iterate(cl, hrclaimer, 0);
2140 }
2141
2142 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2143 _collection_set.iterate(cl);
2144 }
2145
2146 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2147 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2148 }
2149
2150 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2151 HeapRegion* hr = heap_region_containing(addr);
2152 return hr->block_start(addr);
2153 }
2154
2155 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2156 HeapRegion* hr = heap_region_containing(addr);
2157 return hr->block_size(addr);
2158 }
2159
2160 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2161 HeapRegion* hr = heap_region_containing(addr);
2162 return hr->block_is_obj(addr);
2163 }
2164
2165 bool G1CollectedHeap::supports_tlab_allocation() const {
2166 return true;
2167 }
2168
2169 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2170 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2171 }
2172
2173 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2174 return _eden.length() * HeapRegion::GrainBytes;
2175 }
2176
2177 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2178 // must be equal to the humongous object limit.
2179 size_t G1CollectedHeap::max_tlab_size() const {
2180 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2181 }
2182
2183 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2184 return _allocator->unsafe_max_tlab_alloc();
2185 }
2186
2187 size_t G1CollectedHeap::max_capacity() const {
2188 return _hrm.reserved().byte_size();
2189 }
2190
2191 jlong G1CollectedHeap::millis_since_last_gc() {
2192 // See the notes in GenCollectedHeap::millis_since_last_gc()
2193 // for more information about the implementation.
2194 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2195 _g1_policy->collection_pause_end_millis();
2196 if (ret_val < 0) {
2197 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2198 ". returning zero instead.", ret_val);
2199 return 0;
2200 }
2201 return ret_val;
2202 }
2203
2204 void G1CollectedHeap::deduplicate_string(oop str) {
2205 assert(java_lang_String::is_instance(str), "invariant");
2206
2207 if (G1StringDedup::is_enabled()) {
2208 G1StringDedup::deduplicate(str);
2209 }
2210 }
2211
2212 void G1CollectedHeap::prepare_for_verify() {
2213 _verifier->prepare_for_verify();
2214 }
2215
2216 void G1CollectedHeap::verify(VerifyOption vo) {
2217 _verifier->verify(vo);
2218 }
2219
2220 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2221 return true;
2222 }
2223
2224 const char* const* G1CollectedHeap::concurrent_phases() const {
2225 return _cm_thread->concurrent_phases();
2226 }
2227
2228 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2229 return _cm_thread->request_concurrent_phase(phase);
2230 }
2231
2232 class PrintRegionClosure: public HeapRegionClosure {
2233 outputStream* _st;
2234 public:
2235 PrintRegionClosure(outputStream* st) : _st(st) {}
2236 bool do_heap_region(HeapRegion* r) {
2237 r->print_on(_st);
2238 return false;
2239 }
2240 };
2241
2242 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2243 const HeapRegion* hr,
2244 const VerifyOption vo) const {
2245 switch (vo) {
2246 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2247 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2248 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2249 default: ShouldNotReachHere();
2250 }
2251 return false; // keep some compilers happy
2252 }
2253
2254 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2255 const VerifyOption vo) const {
2256 switch (vo) {
2257 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2258 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2259 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2260 default: ShouldNotReachHere();
2261 }
2262 return false; // keep some compilers happy
2263 }
2264
2265 void G1CollectedHeap::print_heap_regions() const {
2266 LogTarget(Trace, gc, heap, region) lt;
2267 if (lt.is_enabled()) {
2268 LogStream ls(lt);
2269 print_regions_on(&ls);
2270 }
2271 }
2272
2273 void G1CollectedHeap::print_on(outputStream* st) const {
2274 st->print(" %-20s", "garbage-first heap");
2275 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2276 capacity()/K, used_unlocked()/K);
2277 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2278 p2i(_hrm.reserved().start()),
2279 p2i(_hrm.reserved().end()));
2280 st->cr();
2281 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2282 uint young_regions = young_regions_count();
2283 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2284 (size_t) young_regions * HeapRegion::GrainBytes / K);
2285 uint survivor_regions = survivor_regions_count();
2286 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2287 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2288 st->cr();
2289 MetaspaceUtils::print_on(st);
2290 }
2291
2292 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2293 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2294 "HS=humongous(starts), HC=humongous(continues), "
2295 "CS=collection set, F=free, A=archive, "
2296 "TAMS=top-at-mark-start (previous, next)");
2297 PrintRegionClosure blk(st);
2298 heap_region_iterate(&blk);
2299 }
2300
2301 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2302 print_on(st);
2303
2304 // Print the per-region information.
2305 print_regions_on(st);
2306 }
2307
2308 void G1CollectedHeap::print_on_error(outputStream* st) const {
2309 this->CollectedHeap::print_on_error(st);
2310
2311 if (_cm != NULL) {
2312 st->cr();
2313 _cm->print_on_error(st);
2314 }
2315 }
2316
2317 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2318 workers()->print_worker_threads_on(st);
2319 _cm_thread->print_on(st);
2320 st->cr();
2321 _cm->print_worker_threads_on(st);
2322 _cr->print_threads_on(st);
2323 _young_gen_sampling_thread->print_on(st);
2324 if (G1StringDedup::is_enabled()) {
2325 G1StringDedup::print_worker_threads_on(st);
2326 }
2327 }
2328
2329 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2330 workers()->threads_do(tc);
2331 tc->do_thread(_cm_thread);
2332 _cm->threads_do(tc);
2333 _cr->threads_do(tc);
2334 tc->do_thread(_young_gen_sampling_thread);
2335 if (G1StringDedup::is_enabled()) {
2336 G1StringDedup::threads_do(tc);
2337 }
2338 }
2339
2340 void G1CollectedHeap::print_tracing_info() const {
2341 g1_rem_set()->print_summary_info();
2342 concurrent_mark()->print_summary_info();
2343 }
2344
2345 #ifndef PRODUCT
2346 // Helpful for debugging RSet issues.
2347
2348 class PrintRSetsClosure : public HeapRegionClosure {
2349 private:
2350 const char* _msg;
2351 size_t _occupied_sum;
2352
2353 public:
2354 bool do_heap_region(HeapRegion* r) {
2355 HeapRegionRemSet* hrrs = r->rem_set();
2356 size_t occupied = hrrs->occupied();
2357 _occupied_sum += occupied;
2358
2359 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2360 if (occupied == 0) {
2361 tty->print_cr(" RSet is empty");
2362 } else {
2363 hrrs->print();
2364 }
2365 tty->print_cr("----------");
2366 return false;
2367 }
2368
2369 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2370 tty->cr();
2371 tty->print_cr("========================================");
2372 tty->print_cr("%s", msg);
2373 tty->cr();
2374 }
2375
2376 ~PrintRSetsClosure() {
2377 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2378 tty->print_cr("========================================");
2379 tty->cr();
2380 }
2381 };
2382
2383 void G1CollectedHeap::print_cset_rsets() {
2384 PrintRSetsClosure cl("Printing CSet RSets");
2385 collection_set_iterate(&cl);
2386 }
2387
2388 void G1CollectedHeap::print_all_rsets() {
2389 PrintRSetsClosure cl("Printing All RSets");;
2390 heap_region_iterate(&cl);
2391 }
2392 #endif // PRODUCT
2393
2394 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2395
2396 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2397 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2398 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2399
2400 size_t eden_capacity_bytes =
2401 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2402
2403 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2404 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2405 eden_capacity_bytes, survivor_used_bytes, num_regions());
2406 }
2407
2408 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2409 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2410 stats->unused(), stats->used(), stats->region_end_waste(),
2411 stats->regions_filled(), stats->direct_allocated(),
2412 stats->failure_used(), stats->failure_waste());
2413 }
2414
2415 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2416 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2417 gc_tracer->report_gc_heap_summary(when, heap_summary);
2418
2419 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2420 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2421 }
2422
2423 G1CollectedHeap* G1CollectedHeap::heap() {
2424 CollectedHeap* heap = Universe::heap();
2425 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2426 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2427 return (G1CollectedHeap*)heap;
2428 }
2429
2430 void G1CollectedHeap::gc_prologue(bool full) {
2431 // always_do_update_barrier = false;
2432 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2433
2434 // This summary needs to be printed before incrementing total collections.
2435 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2436
2437 // Update common counters.
2438 increment_total_collections(full /* full gc */);
2439 if (full) {
2440 increment_old_marking_cycles_started();
2441 }
2442
2443 // Fill TLAB's and such
2444 double start = os::elapsedTime();
2445 accumulate_statistics_all_tlabs();
2446 ensure_parsability(true);
2447 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2448 }
2449
2450 void G1CollectedHeap::gc_epilogue(bool full) {
2451 // Update common counters.
2452 if (full) {
2453 // Update the number of full collections that have been completed.
2454 increment_old_marking_cycles_completed(false /* concurrent */);
2455 }
2456
2457 // We are at the end of the GC. Total collections has already been increased.
2458 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2459
2460 // FIXME: what is this about?
2461 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2462 // is set.
2463 #if COMPILER2_OR_JVMCI
2464 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2465 #endif
2466 // always_do_update_barrier = true;
2467
2468 double start = os::elapsedTime();
2469 resize_all_tlabs();
2470 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2471
2472 MemoryService::track_memory_usage();
2473 // We have just completed a GC. Update the soft reference
2474 // policy with the new heap occupancy
2475 Universe::update_heap_info_at_gc();
2476 }
2477
2478 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2479 uint gc_count_before,
2480 bool* succeeded,
2481 GCCause::Cause gc_cause) {
2482 assert_heap_not_locked_and_not_at_safepoint();
2483 VM_G1CollectForAllocation op(word_size,
2484 gc_count_before,
2485 gc_cause,
2486 false, /* should_initiate_conc_mark */
2487 g1_policy()->max_pause_time_ms());
2488 VMThread::execute(&op);
2489
2490 HeapWord* result = op.result();
2491 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2492 assert(result == NULL || ret_succeeded,
2493 "the result should be NULL if the VM did not succeed");
2494 *succeeded = ret_succeeded;
2495
2496 assert_heap_not_locked();
2497 return result;
2498 }
2499
2500 void G1CollectedHeap::do_concurrent_mark() {
2501 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2502 if (!_cm_thread->in_progress()) {
2503 _cm_thread->set_started();
2504 CGC_lock->notify();
2505 }
2506 }
2507
2508 size_t G1CollectedHeap::pending_card_num() {
2509 size_t extra_cards = 0;
2510 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2511 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2512 extra_cards += dcq.size();
2513 }
2514 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2515 size_t buffer_size = dcqs.buffer_size();
2516 size_t buffer_num = dcqs.completed_buffers_num();
2517
2518 return buffer_size * buffer_num + extra_cards;
2519 }
2520
2521 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2522 // We don't nominate objects with many remembered set entries, on
2523 // the assumption that such objects are likely still live.
2524 HeapRegionRemSet* rem_set = r->rem_set();
2525
2526 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2527 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2528 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2529 }
2530
2531 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2532 private:
2533 size_t _total_humongous;
2534 size_t _candidate_humongous;
2535
2536 DirtyCardQueue _dcq;
2537
2538 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2539 assert(region->is_starts_humongous(), "Must start a humongous object");
2540
2541 oop obj = oop(region->bottom());
2542
2543 // Dead objects cannot be eager reclaim candidates. Due to class
2544 // unloading it is unsafe to query their classes so we return early.
2545 if (g1h->is_obj_dead(obj, region)) {
2546 return false;
2547 }
2548
2549 // If we do not have a complete remembered set for the region, then we can
2550 // not be sure that we have all references to it.
2551 if (!region->rem_set()->is_complete()) {
2552 return false;
2553 }
2554 // Candidate selection must satisfy the following constraints
2555 // while concurrent marking is in progress:
2556 //
2557 // * In order to maintain SATB invariants, an object must not be
2558 // reclaimed if it was allocated before the start of marking and
2559 // has not had its references scanned. Such an object must have
2560 // its references (including type metadata) scanned to ensure no
2561 // live objects are missed by the marking process. Objects
2562 // allocated after the start of concurrent marking don't need to
2563 // be scanned.
2564 //
2565 // * An object must not be reclaimed if it is on the concurrent
2566 // mark stack. Objects allocated after the start of concurrent
2567 // marking are never pushed on the mark stack.
2568 //
2569 // Nominating only objects allocated after the start of concurrent
2570 // marking is sufficient to meet both constraints. This may miss
2571 // some objects that satisfy the constraints, but the marking data
2572 // structures don't support efficiently performing the needed
2573 // additional tests or scrubbing of the mark stack.
2574 //
2575 // However, we presently only nominate is_typeArray() objects.
2576 // A humongous object containing references induces remembered
2577 // set entries on other regions. In order to reclaim such an
2578 // object, those remembered sets would need to be cleaned up.
2579 //
2580 // We also treat is_typeArray() objects specially, allowing them
2581 // to be reclaimed even if allocated before the start of
2582 // concurrent mark. For this we rely on mark stack insertion to
2583 // exclude is_typeArray() objects, preventing reclaiming an object
2584 // that is in the mark stack. We also rely on the metadata for
2585 // such objects to be built-in and so ensured to be kept live.
2586 // Frequent allocation and drop of large binary blobs is an
2587 // important use case for eager reclaim, and this special handling
2588 // may reduce needed headroom.
2589
2590 return obj->is_typeArray() &&
2591 g1h->is_potential_eager_reclaim_candidate(region);
2592 }
2593
2594 public:
2595 RegisterHumongousWithInCSetFastTestClosure()
2596 : _total_humongous(0),
2597 _candidate_humongous(0),
2598 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2599 }
2600
2601 virtual bool do_heap_region(HeapRegion* r) {
2602 if (!r->is_starts_humongous()) {
2603 return false;
2604 }
2605 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2606
2607 bool is_candidate = humongous_region_is_candidate(g1h, r);
2608 uint rindex = r->hrm_index();
2609 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2610 if (is_candidate) {
2611 _candidate_humongous++;
2612 g1h->register_humongous_region_with_cset(rindex);
2613 // Is_candidate already filters out humongous object with large remembered sets.
2614 // If we have a humongous object with a few remembered sets, we simply flush these
2615 // remembered set entries into the DCQS. That will result in automatic
2616 // re-evaluation of their remembered set entries during the following evacuation
2617 // phase.
2618 if (!r->rem_set()->is_empty()) {
2619 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2620 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2621 G1CardTable* ct = g1h->card_table();
2622 HeapRegionRemSetIterator hrrs(r->rem_set());
2623 size_t card_index;
2624 while (hrrs.has_next(card_index)) {
2625 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2626 // The remembered set might contain references to already freed
2627 // regions. Filter out such entries to avoid failing card table
2628 // verification.
2629 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2630 if (*card_ptr != G1CardTable::dirty_card_val()) {
2631 *card_ptr = G1CardTable::dirty_card_val();
2632 _dcq.enqueue(card_ptr);
2633 }
2634 }
2635 }
2636 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2637 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2638 hrrs.n_yielded(), r->rem_set()->occupied());
2639 // We should only clear the card based remembered set here as we will not
2640 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2641 // (and probably never) we do not enter this path if there are other kind of
2642 // remembered sets for this region.
2643 r->rem_set()->clear_locked(true /* only_cardset */);
2644 // Clear_locked() above sets the state to Empty. However we want to continue
2645 // collecting remembered set entries for humongous regions that were not
2646 // reclaimed.
2647 r->rem_set()->set_state_complete();
2648 }
2649 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2650 }
2651 _total_humongous++;
2652
2653 return false;
2654 }
2655
2656 size_t total_humongous() const { return _total_humongous; }
2657 size_t candidate_humongous() const { return _candidate_humongous; }
2658
2659 void flush_rem_set_entries() { _dcq.flush(); }
2660 };
2661
2662 void G1CollectedHeap::register_humongous_regions_with_cset() {
2663 if (!G1EagerReclaimHumongousObjects) {
2664 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2665 return;
2666 }
2667 double time = os::elapsed_counter();
2668
2669 // Collect reclaim candidate information and register candidates with cset.
2670 RegisterHumongousWithInCSetFastTestClosure cl;
2671 heap_region_iterate(&cl);
2672
2673 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2674 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2675 cl.total_humongous(),
2676 cl.candidate_humongous());
2677 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2678
2679 // Finally flush all remembered set entries to re-check into the global DCQS.
2680 cl.flush_rem_set_entries();
2681 }
2682
2683 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2684 public:
2685 bool do_heap_region(HeapRegion* hr) {
2686 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2687 hr->verify_rem_set();
2688 }
2689 return false;
2690 }
2691 };
2692
2693 uint G1CollectedHeap::num_task_queues() const {
2694 return _task_queues->size();
2695 }
2696
2697 #if TASKQUEUE_STATS
2698 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2699 st->print_raw_cr("GC Task Stats");
2700 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2701 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2702 }
2703
2704 void G1CollectedHeap::print_taskqueue_stats() const {
2705 if (!log_is_enabled(Trace, gc, task, stats)) {
2706 return;
2707 }
2708 Log(gc, task, stats) log;
2709 ResourceMark rm;
2710 LogStream ls(log.trace());
2711 outputStream* st = &ls;
2712
2713 print_taskqueue_stats_hdr(st);
2714
2715 TaskQueueStats totals;
2716 const uint n = num_task_queues();
2717 for (uint i = 0; i < n; ++i) {
2718 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2719 totals += task_queue(i)->stats;
2720 }
2721 st->print_raw("tot "); totals.print(st); st->cr();
2722
2723 DEBUG_ONLY(totals.verify());
2724 }
2725
2726 void G1CollectedHeap::reset_taskqueue_stats() {
2727 const uint n = num_task_queues();
2728 for (uint i = 0; i < n; ++i) {
2729 task_queue(i)->stats.reset();
2730 }
2731 }
2732 #endif // TASKQUEUE_STATS
2733
2734 void G1CollectedHeap::wait_for_root_region_scanning() {
2735 double scan_wait_start = os::elapsedTime();
2736 // We have to wait until the CM threads finish scanning the
2737 // root regions as it's the only way to ensure that all the
2738 // objects on them have been correctly scanned before we start
2739 // moving them during the GC.
2740 bool waited = _cm->root_regions()->wait_until_scan_finished();
2741 double wait_time_ms = 0.0;
2742 if (waited) {
2743 double scan_wait_end = os::elapsedTime();
2744 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2745 }
2746 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2747 }
2748
2749 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2750 private:
2751 G1HRPrinter* _hr_printer;
2752 public:
2753 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2754
2755 virtual bool do_heap_region(HeapRegion* r) {
2756 _hr_printer->cset(r);
2757 return false;
2758 }
2759 };
2760
2761 void G1CollectedHeap::start_new_collection_set() {
2762 collection_set()->start_incremental_building();
2763
2764 clear_cset_fast_test();
2765
2766 guarantee(_eden.length() == 0, "eden should have been cleared");
2767 g1_policy()->transfer_survivors_to_cset(survivor());
2768 }
2769
2770 bool
2771 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2772 assert_at_safepoint_on_vm_thread();
2773 guarantee(!is_gc_active(), "collection is not reentrant");
2774
2775 if (GCLocker::check_active_before_gc()) {
2776 return false;
2777 }
2778
2779 _gc_timer_stw->register_gc_start();
2780
2781 GCIdMark gc_id_mark;
2782 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2783
2784 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2785 ResourceMark rm;
2786
2787 g1_policy()->note_gc_start();
2788
2789 wait_for_root_region_scanning();
2790
2791 print_heap_before_gc();
2792 print_heap_regions();
2793 trace_heap_before_gc(_gc_tracer_stw);
2794
2795 _verifier->verify_region_sets_optional();
2796 _verifier->verify_dirty_young_regions();
2797
2798 // We should not be doing initial mark unless the conc mark thread is running
2799 if (!_cm_thread->should_terminate()) {
2800 // This call will decide whether this pause is an initial-mark
2801 // pause. If it is, in_initial_mark_gc() will return true
2802 // for the duration of this pause.
2803 g1_policy()->decide_on_conc_mark_initiation();
2804 }
2805
2806 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2807 assert(!collector_state()->in_initial_mark_gc() ||
2808 collector_state()->in_young_only_phase(), "sanity");
2809
2810 // We also do not allow mixed GCs during marking.
2811 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2812
2813 // Record whether this pause is an initial mark. When the current
2814 // thread has completed its logging output and it's safe to signal
2815 // the CM thread, the flag's value in the policy has been reset.
2816 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2817
2818 // Inner scope for scope based logging, timers, and stats collection
2819 {
2820 EvacuationInfo evacuation_info;
2821
2822 if (collector_state()->in_initial_mark_gc()) {
2823 // We are about to start a marking cycle, so we increment the
2824 // full collection counter.
2825 increment_old_marking_cycles_started();
2826 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2827 }
2828
2829 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2830
2831 GCTraceCPUTime tcpu;
2832
2833 G1HeapVerifier::G1VerifyType verify_type;
2834 FormatBuffer<> gc_string("Pause ");
2835 if (collector_state()->in_initial_mark_gc()) {
2836 gc_string.append("Initial Mark");
2837 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2838 } else if (collector_state()->in_young_only_phase()) {
2839 gc_string.append("Young");
2840 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2841 } else {
2842 gc_string.append("Mixed");
2843 verify_type = G1HeapVerifier::G1VerifyMixed;
2844 }
2845 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2846
2847 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2848 workers()->active_workers(),
2849 Threads::number_of_non_daemon_threads());
2850 active_workers = workers()->update_active_workers(active_workers);
2851 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2852
2853 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2854 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2855
2856 G1HeapTransition heap_transition(this);
2857 size_t heap_used_bytes_before_gc = used();
2858
2859 // Don't dynamically change the number of GC threads this early. A value of
2860 // 0 is used to indicate serial work. When parallel work is done,
2861 // it will be set.
2862
2863 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2864 IsGCActiveMark x;
2865
2866 gc_prologue(false);
2867
2868 if (VerifyRememberedSets) {
2869 log_info(gc, verify)("[Verifying RemSets before GC]");
2870 VerifyRegionRemSetClosure v_cl;
2871 heap_region_iterate(&v_cl);
2872 }
2873
2874 _verifier->verify_before_gc(verify_type);
2875
2876 _verifier->check_bitmaps("GC Start");
2877
2878 #if COMPILER2_OR_JVMCI
2879 DerivedPointerTable::clear();
2880 #endif
2881
2882 // Please see comment in g1CollectedHeap.hpp and
2883 // G1CollectedHeap::ref_processing_init() to see how
2884 // reference processing currently works in G1.
2885
2886 // Enable discovery in the STW reference processor
2887 _ref_processor_stw->enable_discovery();
2888
2889 {
2890 // We want to temporarily turn off discovery by the
2891 // CM ref processor, if necessary, and turn it back on
2892 // on again later if we do. Using a scoped
2893 // NoRefDiscovery object will do this.
2894 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2895
2896 // Forget the current alloc region (we might even choose it to be part
2897 // of the collection set!).
2898 _allocator->release_mutator_alloc_region();
2899
2900 // This timing is only used by the ergonomics to handle our pause target.
2901 // It is unclear why this should not include the full pause. We will
2902 // investigate this in CR 7178365.
2903 //
2904 // Preserving the old comment here if that helps the investigation:
2905 //
2906 // The elapsed time induced by the start time below deliberately elides
2907 // the possible verification above.
2908 double sample_start_time_sec = os::elapsedTime();
2909
2910 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2911
2912 if (collector_state()->in_initial_mark_gc()) {
2913 concurrent_mark()->pre_initial_mark();
2914 }
2915
2916 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2917
2918 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2919
2920 // Make sure the remembered sets are up to date. This needs to be
2921 // done before register_humongous_regions_with_cset(), because the
2922 // remembered sets are used there to choose eager reclaim candidates.
2923 // If the remembered sets are not up to date we might miss some
2924 // entries that need to be handled.
2925 g1_rem_set()->cleanupHRRS();
2926
2927 register_humongous_regions_with_cset();
2928
2929 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2930
2931 // We call this after finalize_cset() to
2932 // ensure that the CSet has been finalized.
2933 _cm->verify_no_cset_oops();
2934
2935 if (_hr_printer.is_active()) {
2936 G1PrintCollectionSetClosure cl(&_hr_printer);
2937 _collection_set.iterate(&cl);
2938 }
2939
2940 // Initialize the GC alloc regions.
2941 _allocator->init_gc_alloc_regions(evacuation_info);
2942
2943 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2944 pre_evacuate_collection_set();
2945
2946 // Actually do the work...
2947 evacuate_collection_set(&per_thread_states);
2948
2949 post_evacuate_collection_set(evacuation_info, &per_thread_states);
2950
2951 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2952 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2953
2954 eagerly_reclaim_humongous_regions();
2955
2956 record_obj_copy_mem_stats();
2957 _survivor_evac_stats.adjust_desired_plab_sz();
2958 _old_evac_stats.adjust_desired_plab_sz();
2959
2960 double start = os::elapsedTime();
2961 start_new_collection_set();
2962 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2963
2964 if (evacuation_failed()) {
2965 set_used(recalculate_used());
2966 if (_archive_allocator != NULL) {
2967 _archive_allocator->clear_used();
2968 }
2969 for (uint i = 0; i < ParallelGCThreads; i++) {
2970 if (_evacuation_failed_info_array[i].has_failed()) {
2971 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
2972 }
2973 }
2974 } else {
2975 // The "used" of the the collection set have already been subtracted
2976 // when they were freed. Add in the bytes evacuated.
2977 increase_used(g1_policy()->bytes_copied_during_gc());
2978 }
2979
2980 if (collector_state()->in_initial_mark_gc()) {
2981 // We have to do this before we notify the CM threads that
2982 // they can start working to make sure that all the
2983 // appropriate initialization is done on the CM object.
2984 concurrent_mark()->post_initial_mark();
2985 // Note that we don't actually trigger the CM thread at
2986 // this point. We do that later when we're sure that
2987 // the current thread has completed its logging output.
2988 }
2989
2990 allocate_dummy_regions();
2991
2992 _allocator->init_mutator_alloc_region();
2993
2994 {
2995 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2996 if (expand_bytes > 0) {
2997 size_t bytes_before = capacity();
2998 // No need for an ergo logging here,
2999 // expansion_amount() does this when it returns a value > 0.
3000 double expand_ms;
3001 if (!expand(expand_bytes, _workers, &expand_ms)) {
3002 // We failed to expand the heap. Cannot do anything about it.
3003 }
3004 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3005 }
3006 }
3007
3008 // We redo the verification but now wrt to the new CSet which
3009 // has just got initialized after the previous CSet was freed.
3010 _cm->verify_no_cset_oops();
3011
3012 // This timing is only used by the ergonomics to handle our pause target.
3013 // It is unclear why this should not include the full pause. We will
3014 // investigate this in CR 7178365.
3015 double sample_end_time_sec = os::elapsedTime();
3016 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3017 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3018 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3019
3020 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3021 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3022
3023 if (VerifyRememberedSets) {
3024 log_info(gc, verify)("[Verifying RemSets after GC]");
3025 VerifyRegionRemSetClosure v_cl;
3026 heap_region_iterate(&v_cl);
3027 }
3028
3029 _verifier->verify_after_gc(verify_type);
3030 _verifier->check_bitmaps("GC End");
3031
3032 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3033 _ref_processor_stw->verify_no_references_recorded();
3034
3035 // CM reference discovery will be re-enabled if necessary.
3036 }
3037
3038 #ifdef TRACESPINNING
3039 ParallelTaskTerminator::print_termination_counts();
3040 #endif
3041
3042 gc_epilogue(false);
3043 }
3044
3045 // Print the remainder of the GC log output.
3046 if (evacuation_failed()) {
3047 log_info(gc)("To-space exhausted");
3048 }
3049
3050 g1_policy()->print_phases();
3051 heap_transition.print();
3052
3053 // It is not yet to safe to tell the concurrent mark to
3054 // start as we have some optional output below. We don't want the
3055 // output from the concurrent mark thread interfering with this
3056 // logging output either.
3057
3058 _hrm.verify_optional();
3059 _verifier->verify_region_sets_optional();
3060
3061 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3062 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3063
3064 print_heap_after_gc();
3065 print_heap_regions();
3066 trace_heap_after_gc(_gc_tracer_stw);
3067
3068 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3069 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3070 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3071 // before any GC notifications are raised.
3072 g1mm()->update_sizes();
3073
3074 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3075 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3076 _gc_timer_stw->register_gc_end();
3077 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3078 }
3079 // It should now be safe to tell the concurrent mark thread to start
3080 // without its logging output interfering with the logging output
3081 // that came from the pause.
3082
3083 if (should_start_conc_mark) {
3084 // CAUTION: after the doConcurrentMark() call below,
3085 // the concurrent marking thread(s) could be running
3086 // concurrently with us. Make sure that anything after
3087 // this point does not assume that we are the only GC thread
3088 // running. Note: of course, the actual marking work will
3089 // not start until the safepoint itself is released in
3090 // SuspendibleThreadSet::desynchronize().
3091 do_concurrent_mark();
3092 }
3093
3094 return true;
3095 }
3096
3097 void G1CollectedHeap::remove_self_forwarding_pointers() {
3098 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3099 workers()->run_task(&rsfp_task);
3100 }
3101
3102 void G1CollectedHeap::restore_after_evac_failure() {
3103 double remove_self_forwards_start = os::elapsedTime();
3104
3105 remove_self_forwarding_pointers();
3106 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3107 _preserved_marks_set.restore(&task_executor);
3108
3109 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3110 }
3111
3112 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3113 if (!_evacuation_failed) {
3114 _evacuation_failed = true;
3115 }
3116
3117 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3118 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3119 }
3120
3121 bool G1ParEvacuateFollowersClosure::offer_termination() {
3122 G1ParScanThreadState* const pss = par_scan_state();
3123 start_term_time();
3124 const bool res = terminator()->offer_termination();
3125 end_term_time();
3126 return res;
3127 }
3128
3129 void G1ParEvacuateFollowersClosure::do_void() {
3130 G1ParScanThreadState* const pss = par_scan_state();
3131 pss->trim_queue();
3132 do {
3133 pss->steal_and_trim_queue(queues());
3134 } while (!offer_termination());
3135 }
3136
3137 class G1ParTask : public AbstractGangTask {
3138 protected:
3139 G1CollectedHeap* _g1h;
3140 G1ParScanThreadStateSet* _pss;
3141 RefToScanQueueSet* _queues;
3142 G1RootProcessor* _root_processor;
3143 ParallelTaskTerminator _terminator;
3144 uint _n_workers;
3145
3146 public:
3147 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3148 : AbstractGangTask("G1 collection"),
3149 _g1h(g1h),
3150 _pss(per_thread_states),
3151 _queues(task_queues),
3152 _root_processor(root_processor),
3153 _terminator(n_workers, _queues),
3154 _n_workers(n_workers)
3155 {}
3156
3157 void work(uint worker_id) {
3158 if (worker_id >= _n_workers) return; // no work needed this round
3159
3160 double start_sec = os::elapsedTime();
3161 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3162
3163 {
3164 ResourceMark rm;
3165 HandleMark hm;
3166
3167 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3168
3169 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3170 pss->set_ref_discoverer(rp);
3171
3172 double start_strong_roots_sec = os::elapsedTime();
3173
3174 _root_processor->evacuate_roots(pss, worker_id);
3175
3176 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3177 // treating the nmethods visited to act as roots for concurrent marking.
3178 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3179 // objects copied by the current evacuation.
3180 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3181
3182 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3183
3184 double term_sec = 0.0;
3185 size_t evac_term_attempts = 0;
3186 {
3187 double start = os::elapsedTime();
3188 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3189 evac.do_void();
3190
3191 evac_term_attempts = evac.term_attempts();
3192 term_sec = evac.term_time();
3193 double elapsed_sec = os::elapsedTime() - start;
3194
3195 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3196 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3197 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3198 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3199 }
3200
3201 assert(pss->queue_is_empty(), "should be empty");
3202
3203 if (log_is_enabled(Debug, gc, task, stats)) {
3204 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3205 size_t lab_waste;
3206 size_t lab_undo_waste;
3207 pss->waste(lab_waste, lab_undo_waste);
3208 _g1h->print_termination_stats(worker_id,
3209 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3210 strong_roots_sec * 1000.0, /* strong roots time */
3211 term_sec * 1000.0, /* evac term time */
3212 evac_term_attempts, /* evac term attempts */
3213 lab_waste, /* alloc buffer waste */
3214 lab_undo_waste /* undo waste */
3215 );
3216 }
3217
3218 // Close the inner scope so that the ResourceMark and HandleMark
3219 // destructors are executed here and are included as part of the
3220 // "GC Worker Time".
3221 }
3222 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3223 }
3224 };
3225
3226 void G1CollectedHeap::print_termination_stats_hdr() {
3227 log_debug(gc, task, stats)("GC Termination Stats");
3228 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3229 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3230 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3231 }
3232
3233 void G1CollectedHeap::print_termination_stats(uint worker_id,
3234 double elapsed_ms,
3235 double strong_roots_ms,
3236 double term_ms,
3237 size_t term_attempts,
3238 size_t alloc_buffer_waste,
3239 size_t undo_waste) const {
3240 log_debug(gc, task, stats)
3241 ("%3d %9.2f %9.2f %6.2f "
3242 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3243 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3244 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3245 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3246 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3247 alloc_buffer_waste * HeapWordSize / K,
3248 undo_waste * HeapWordSize / K);
3249 }
3250
3251 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3252 private:
3253 BoolObjectClosure* _is_alive;
3254 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3255 OopStorage::ParState<false /* concurrent */, false /* const */> _par_state_string;
3256
3257 int _initial_string_table_size;
3258 int _initial_symbol_table_size;
3259
3260 bool _process_strings;
3261 int _strings_processed;
3262 int _strings_removed;
3263
3264 bool _process_symbols;
3265 int _symbols_processed;
3266 int _symbols_removed;
3267
3268 bool _process_string_dedup;
3269
3270 public:
3271 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3272 AbstractGangTask("String/Symbol Unlinking"),
3273 _is_alive(is_alive),
3274 _dedup_closure(is_alive, NULL, false),
3275 _par_state_string(StringTable::weak_storage()),
3276 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3277 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3278 _process_string_dedup(process_string_dedup) {
3279
3280 _initial_string_table_size = (int) StringTable::the_table()->table_size();
3281 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3282 if (process_symbols) {
3283 SymbolTable::clear_parallel_claimed_index();
3284 }
3285 }
3286
3287 ~G1StringAndSymbolCleaningTask() {
3288 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3289 "claim value %d after unlink less than initial symbol table size %d",
3290 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3291
3292 log_info(gc, stringtable)(
3293 "Cleaned string and symbol table, "
3294 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3295 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3296 strings_processed(), strings_removed(),
3297 symbols_processed(), symbols_removed());
3298 }
3299
3300 void work(uint worker_id) {
3301 int strings_processed = 0;
3302 int strings_removed = 0;
3303 int symbols_processed = 0;
3304 int symbols_removed = 0;
3305 if (_process_strings) {
3306 StringTable::possibly_parallel_unlink(&_par_state_string, _is_alive, &strings_processed, &strings_removed);
3307 Atomic::add(strings_processed, &_strings_processed);
3308 Atomic::add(strings_removed, &_strings_removed);
3309 }
3310 if (_process_symbols) {
3311 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3312 Atomic::add(symbols_processed, &_symbols_processed);
3313 Atomic::add(symbols_removed, &_symbols_removed);
3314 }
3315 if (_process_string_dedup) {
3316 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3317 }
3318 }
3319
3320 size_t strings_processed() const { return (size_t)_strings_processed; }
3321 size_t strings_removed() const { return (size_t)_strings_removed; }
3322
3323 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3324 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3325 };
3326
3327 class G1CodeCacheUnloadingTask {
3328 private:
3329 static Monitor* _lock;
3330
3331 BoolObjectClosure* const _is_alive;
3332 const bool _unloading_occurred;
3333 const uint _num_workers;
3334
3335 // Variables used to claim nmethods.
3336 CompiledMethod* _first_nmethod;
3337 CompiledMethod* volatile _claimed_nmethod;
3338
3339 // The list of nmethods that need to be processed by the second pass.
3340 CompiledMethod* volatile _postponed_list;
3341 volatile uint _num_entered_barrier;
3342
3343 public:
3344 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3345 _is_alive(is_alive),
3346 _unloading_occurred(unloading_occurred),
3347 _num_workers(num_workers),
3348 _first_nmethod(NULL),
3349 _claimed_nmethod(NULL),
3350 _postponed_list(NULL),
3351 _num_entered_barrier(0)
3352 {
3353 CompiledMethod::increase_unloading_clock();
3354 // Get first alive nmethod
3355 CompiledMethodIterator iter = CompiledMethodIterator();
3356 if(iter.next_alive()) {
3357 _first_nmethod = iter.method();
3358 }
3359 _claimed_nmethod = _first_nmethod;
3360 }
3361
3362 ~G1CodeCacheUnloadingTask() {
3363 CodeCache::verify_clean_inline_caches();
3364
3365 CodeCache::set_needs_cache_clean(false);
3366 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3367
3368 CodeCache::verify_icholder_relocations();
3369 }
3370
3371 private:
3372 void add_to_postponed_list(CompiledMethod* nm) {
3373 CompiledMethod* old;
3374 do {
3375 old = _postponed_list;
3376 nm->set_unloading_next(old);
3377 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3378 }
3379
3380 void clean_nmethod(CompiledMethod* nm) {
3381 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3382
3383 if (postponed) {
3384 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3385 add_to_postponed_list(nm);
3386 }
3387
3388 // Mark that this nmethod has been cleaned/unloaded.
3389 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3390 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3391 }
3392
3393 void clean_nmethod_postponed(CompiledMethod* nm) {
3394 nm->do_unloading_parallel_postponed();
3395 }
3396
3397 static const int MaxClaimNmethods = 16;
3398
3399 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3400 CompiledMethod* first;
3401 CompiledMethodIterator last;
3402
3403 do {
3404 *num_claimed_nmethods = 0;
3405
3406 first = _claimed_nmethod;
3407 last = CompiledMethodIterator(first);
3408
3409 if (first != NULL) {
3410
3411 for (int i = 0; i < MaxClaimNmethods; i++) {
3412 if (!last.next_alive()) {
3413 break;
3414 }
3415 claimed_nmethods[i] = last.method();
3416 (*num_claimed_nmethods)++;
3417 }
3418 }
3419
3420 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3421 }
3422
3423 CompiledMethod* claim_postponed_nmethod() {
3424 CompiledMethod* claim;
3425 CompiledMethod* next;
3426
3427 do {
3428 claim = _postponed_list;
3429 if (claim == NULL) {
3430 return NULL;
3431 }
3432
3433 next = claim->unloading_next();
3434
3435 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3436
3437 return claim;
3438 }
3439
3440 public:
3441 // Mark that we're done with the first pass of nmethod cleaning.
3442 void barrier_mark(uint worker_id) {
3443 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3444 _num_entered_barrier++;
3445 if (_num_entered_barrier == _num_workers) {
3446 ml.notify_all();
3447 }
3448 }
3449
3450 // See if we have to wait for the other workers to
3451 // finish their first-pass nmethod cleaning work.
3452 void barrier_wait(uint worker_id) {
3453 if (_num_entered_barrier < _num_workers) {
3454 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3455 while (_num_entered_barrier < _num_workers) {
3456 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3457 }
3458 }
3459 }
3460
3461 // Cleaning and unloading of nmethods. Some work has to be postponed
3462 // to the second pass, when we know which nmethods survive.
3463 void work_first_pass(uint worker_id) {
3464 // The first nmethods is claimed by the first worker.
3465 if (worker_id == 0 && _first_nmethod != NULL) {
3466 clean_nmethod(_first_nmethod);
3467 _first_nmethod = NULL;
3468 }
3469
3470 int num_claimed_nmethods;
3471 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3472
3473 while (true) {
3474 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3475
3476 if (num_claimed_nmethods == 0) {
3477 break;
3478 }
3479
3480 for (int i = 0; i < num_claimed_nmethods; i++) {
3481 clean_nmethod(claimed_nmethods[i]);
3482 }
3483 }
3484 }
3485
3486 void work_second_pass(uint worker_id) {
3487 CompiledMethod* nm;
3488 // Take care of postponed nmethods.
3489 while ((nm = claim_postponed_nmethod()) != NULL) {
3490 clean_nmethod_postponed(nm);
3491 }
3492 }
3493 };
3494
3495 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3496
3497 class G1KlassCleaningTask : public StackObj {
3498 volatile int _clean_klass_tree_claimed;
3499 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3500
3501 public:
3502 G1KlassCleaningTask() :
3503 _clean_klass_tree_claimed(0),
3504 _klass_iterator() {
3505 }
3506
3507 private:
3508 bool claim_clean_klass_tree_task() {
3509 if (_clean_klass_tree_claimed) {
3510 return false;
3511 }
3512
3513 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3514 }
3515
3516 InstanceKlass* claim_next_klass() {
3517 Klass* klass;
3518 do {
3519 klass =_klass_iterator.next_klass();
3520 } while (klass != NULL && !klass->is_instance_klass());
3521
3522 // this can be null so don't call InstanceKlass::cast
3523 return static_cast<InstanceKlass*>(klass);
3524 }
3525
3526 public:
3527
3528 void clean_klass(InstanceKlass* ik) {
3529 ik->clean_weak_instanceklass_links();
3530 }
3531
3532 void work() {
3533 ResourceMark rm;
3534
3535 // One worker will clean the subklass/sibling klass tree.
3536 if (claim_clean_klass_tree_task()) {
3537 Klass::clean_subklass_tree();
3538 }
3539
3540 // All workers will help cleaning the classes,
3541 InstanceKlass* klass;
3542 while ((klass = claim_next_klass()) != NULL) {
3543 clean_klass(klass);
3544 }
3545 }
3546 };
3547
3548 class G1ResolvedMethodCleaningTask : public StackObj {
3549 volatile int _resolved_method_task_claimed;
3550 public:
3551 G1ResolvedMethodCleaningTask() :
3552 _resolved_method_task_claimed(0) {}
3553
3554 bool claim_resolved_method_task() {
3555 if (_resolved_method_task_claimed) {
3556 return false;
3557 }
3558 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3559 }
3560
3561 // These aren't big, one thread can do it all.
3562 void work() {
3563 if (claim_resolved_method_task()) {
3564 ResolvedMethodTable::unlink();
3565 }
3566 }
3567 };
3568
3569
3570 // To minimize the remark pause times, the tasks below are done in parallel.
3571 class G1ParallelCleaningTask : public AbstractGangTask {
3572 private:
3573 bool _unloading_occurred;
3574 G1StringAndSymbolCleaningTask _string_symbol_task;
3575 G1CodeCacheUnloadingTask _code_cache_task;
3576 G1KlassCleaningTask _klass_cleaning_task;
3577 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3578
3579 public:
3580 // The constructor is run in the VMThread.
3581 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3582 AbstractGangTask("Parallel Cleaning"),
3583 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3584 _code_cache_task(num_workers, is_alive, unloading_occurred),
3585 _klass_cleaning_task(),
3586 _unloading_occurred(unloading_occurred),
3587 _resolved_method_cleaning_task() {
3588 }
3589
3590 // The parallel work done by all worker threads.
3591 void work(uint worker_id) {
3592 // Do first pass of code cache cleaning.
3593 _code_cache_task.work_first_pass(worker_id);
3594
3595 // Let the threads mark that the first pass is done.
3596 _code_cache_task.barrier_mark(worker_id);
3597
3598 // Clean the Strings and Symbols.
3599 _string_symbol_task.work(worker_id);
3600
3601 // Clean unreferenced things in the ResolvedMethodTable
3602 _resolved_method_cleaning_task.work();
3603
3604 // Wait for all workers to finish the first code cache cleaning pass.
3605 _code_cache_task.barrier_wait(worker_id);
3606
3607 // Do the second code cache cleaning work, which realize on
3608 // the liveness information gathered during the first pass.
3609 _code_cache_task.work_second_pass(worker_id);
3610
3611 // Clean all klasses that were not unloaded.
3612 // The weak metadata in klass doesn't need to be
3613 // processed if there was no unloading.
3614 if (_unloading_occurred) {
3615 _klass_cleaning_task.work();
3616 }
3617 }
3618 };
3619
3620
3621 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3622 bool class_unloading_occurred) {
3623 uint n_workers = workers()->active_workers();
3624
3625 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3626 workers()->run_task(&g1_unlink_task);
3627 }
3628
3629 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3630 bool process_strings,
3631 bool process_symbols,
3632 bool process_string_dedup) {
3633 if (!process_strings && !process_symbols && !process_string_dedup) {
3634 // Nothing to clean.
3635 return;
3636 }
3637
3638 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3639 workers()->run_task(&g1_unlink_task);
3640
3641 }
3642
3643 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3644 private:
3645 DirtyCardQueueSet* _queue;
3646 G1CollectedHeap* _g1h;
3647 public:
3648 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3649 _queue(queue), _g1h(g1h) { }
3650
3651 virtual void work(uint worker_id) {
3652 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3653 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3654
3655 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3656 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3657
3658 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3659 }
3660 };
3661
3662 void G1CollectedHeap::redirty_logged_cards() {
3663 double redirty_logged_cards_start = os::elapsedTime();
3664
3665 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3666 dirty_card_queue_set().reset_for_par_iteration();
3667 workers()->run_task(&redirty_task);
3668
3669 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3670 dcq.merge_bufferlists(&dirty_card_queue_set());
3671 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3672
3673 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3674 }
3675
3676 // Weak Reference Processing support
3677
3678 bool G1STWIsAliveClosure::do_object_b(oop p) {
3679 // An object is reachable if it is outside the collection set,
3680 // or is inside and copied.
3681 return !_g1h->is_in_cset(p) || p->is_forwarded();
3682 }
3683
3684 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3685 assert(obj != NULL, "must not be NULL");
3686 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3687 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3688 // may falsely indicate that this is not the case here: however the collection set only
3689 // contains old regions when concurrent mark is not running.
3690 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3691 }
3692
3693 // Non Copying Keep Alive closure
3694 class G1KeepAliveClosure: public OopClosure {
3695 G1CollectedHeap*_g1h;
3696 public:
3697 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3698 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3699 void do_oop(oop* p) {
3700 oop obj = *p;
3701 assert(obj != NULL, "the caller should have filtered out NULL values");
3702
3703 const InCSetState cset_state =_g1h->in_cset_state(obj);
3704 if (!cset_state.is_in_cset_or_humongous()) {
3705 return;
3706 }
3707 if (cset_state.is_in_cset()) {
3708 assert( obj->is_forwarded(), "invariant" );
3709 *p = obj->forwardee();
3710 } else {
3711 assert(!obj->is_forwarded(), "invariant" );
3712 assert(cset_state.is_humongous(),
3713 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3714 _g1h->set_humongous_is_live(obj);
3715 }
3716 }
3717 };
3718
3719 // Copying Keep Alive closure - can be called from both
3720 // serial and parallel code as long as different worker
3721 // threads utilize different G1ParScanThreadState instances
3722 // and different queues.
3723
3724 class G1CopyingKeepAliveClosure: public OopClosure {
3725 G1CollectedHeap* _g1h;
3726 OopClosure* _copy_non_heap_obj_cl;
3727 G1ParScanThreadState* _par_scan_state;
3728
3729 public:
3730 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3731 OopClosure* non_heap_obj_cl,
3732 G1ParScanThreadState* pss):
3733 _g1h(g1h),
3734 _copy_non_heap_obj_cl(non_heap_obj_cl),
3735 _par_scan_state(pss)
3736 {}
3737
3738 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3739 virtual void do_oop( oop* p) { do_oop_work(p); }
3740
3741 template <class T> void do_oop_work(T* p) {
3742 oop obj = RawAccess<>::oop_load(p);
3743
3744 if (_g1h->is_in_cset_or_humongous(obj)) {
3745 // If the referent object has been forwarded (either copied
3746 // to a new location or to itself in the event of an
3747 // evacuation failure) then we need to update the reference
3748 // field and, if both reference and referent are in the G1
3749 // heap, update the RSet for the referent.
3750 //
3751 // If the referent has not been forwarded then we have to keep
3752 // it alive by policy. Therefore we have copy the referent.
3753 //
3754 // If the reference field is in the G1 heap then we can push
3755 // on the PSS queue. When the queue is drained (after each
3756 // phase of reference processing) the object and it's followers
3757 // will be copied, the reference field set to point to the
3758 // new location, and the RSet updated. Otherwise we need to
3759 // use the the non-heap or metadata closures directly to copy
3760 // the referent object and update the pointer, while avoiding
3761 // updating the RSet.
3762
3763 if (_g1h->is_in_g1_reserved(p)) {
3764 _par_scan_state->push_on_queue(p);
3765 } else {
3766 assert(!Metaspace::contains((const void*)p),
3767 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3768 _copy_non_heap_obj_cl->do_oop(p);
3769 }
3770 }
3771 }
3772 };
3773
3774 // Serial drain queue closure. Called as the 'complete_gc'
3775 // closure for each discovered list in some of the
3776 // reference processing phases.
3777
3778 class G1STWDrainQueueClosure: public VoidClosure {
3779 protected:
3780 G1CollectedHeap* _g1h;
3781 G1ParScanThreadState* _par_scan_state;
3782
3783 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3784
3785 public:
3786 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3787 _g1h(g1h),
3788 _par_scan_state(pss)
3789 { }
3790
3791 void do_void() {
3792 G1ParScanThreadState* const pss = par_scan_state();
3793 pss->trim_queue();
3794 }
3795 };
3796
3797 // Parallel Reference Processing closures
3798
3799 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3800 // processing during G1 evacuation pauses.
3801
3802 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3803 private:
3804 G1CollectedHeap* _g1h;
3805 G1ParScanThreadStateSet* _pss;
3806 RefToScanQueueSet* _queues;
3807 WorkGang* _workers;
3808 uint _active_workers;
3809
3810 public:
3811 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3812 G1ParScanThreadStateSet* per_thread_states,
3813 WorkGang* workers,
3814 RefToScanQueueSet *task_queues,
3815 uint n_workers) :
3816 _g1h(g1h),
3817 _pss(per_thread_states),
3818 _queues(task_queues),
3819 _workers(workers),
3820 _active_workers(n_workers)
3821 {
3822 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3823 }
3824
3825 // Executes the given task using concurrent marking worker threads.
3826 virtual void execute(ProcessTask& task);
3827 };
3828
3829 // Gang task for possibly parallel reference processing
3830
3831 class G1STWRefProcTaskProxy: public AbstractGangTask {
3832 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3833 ProcessTask& _proc_task;
3834 G1CollectedHeap* _g1h;
3835 G1ParScanThreadStateSet* _pss;
3836 RefToScanQueueSet* _task_queues;
3837 ParallelTaskTerminator* _terminator;
3838
3839 public:
3840 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3841 G1CollectedHeap* g1h,
3842 G1ParScanThreadStateSet* per_thread_states,
3843 RefToScanQueueSet *task_queues,
3844 ParallelTaskTerminator* terminator) :
3845 AbstractGangTask("Process reference objects in parallel"),
3846 _proc_task(proc_task),
3847 _g1h(g1h),
3848 _pss(per_thread_states),
3849 _task_queues(task_queues),
3850 _terminator(terminator)
3851 {}
3852
3853 virtual void work(uint worker_id) {
3854 // The reference processing task executed by a single worker.
3855 ResourceMark rm;
3856 HandleMark hm;
3857
3858 G1STWIsAliveClosure is_alive(_g1h);
3859
3860 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3861 pss->set_ref_discoverer(NULL);
3862
3863 // Keep alive closure.
3864 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3865
3866 // Complete GC closure
3867 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3868
3869 // Call the reference processing task's work routine.
3870 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3871
3872 // Note we cannot assert that the refs array is empty here as not all
3873 // of the processing tasks (specifically phase2 - pp2_work) execute
3874 // the complete_gc closure (which ordinarily would drain the queue) so
3875 // the queue may not be empty.
3876 }
3877 };
3878
3879 // Driver routine for parallel reference processing.
3880 // Creates an instance of the ref processing gang
3881 // task and has the worker threads execute it.
3882 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3883 assert(_workers != NULL, "Need parallel worker threads.");
3884
3885 ParallelTaskTerminator terminator(_active_workers, _queues);
3886 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3887
3888 _workers->run_task(&proc_task_proxy);
3889 }
3890
3891 // End of weak reference support closures
3892
3893 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3894 double ref_proc_start = os::elapsedTime();
3895
3896 ReferenceProcessor* rp = _ref_processor_stw;
3897 assert(rp->discovery_enabled(), "should have been enabled");
3898
3899 // Closure to test whether a referent is alive.
3900 G1STWIsAliveClosure is_alive(this);
3901
3902 // Even when parallel reference processing is enabled, the processing
3903 // of JNI refs is serial and performed serially by the current thread
3904 // rather than by a worker. The following PSS will be used for processing
3905 // JNI refs.
3906
3907 // Use only a single queue for this PSS.
3908 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3909 pss->set_ref_discoverer(NULL);
3910 assert(pss->queue_is_empty(), "pre-condition");
3911
3912 // Keep alive closure.
3913 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
3914
3915 // Serial Complete GC closure
3916 G1STWDrainQueueClosure drain_queue(this, pss);
3917
3918 // Setup the soft refs policy...
3919 rp->setup_policy(false);
3920
3921 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3922
3923 ReferenceProcessorStats stats;
3924 if (!rp->processing_is_mt()) {
3925 // Serial reference processing...
3926 stats = rp->process_discovered_references(&is_alive,
3927 &keep_alive,
3928 &drain_queue,
3929 NULL,
3930 pt);
3931 } else {
3932 uint no_of_gc_workers = workers()->active_workers();
3933
3934 // Parallel reference processing
3935 assert(no_of_gc_workers <= rp->max_num_queues(),
3936 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3937 no_of_gc_workers, rp->max_num_queues());
3938
3939 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
3940 stats = rp->process_discovered_references(&is_alive,
3941 &keep_alive,
3942 &drain_queue,
3943 &par_task_executor,
3944 pt);
3945 }
3946
3947 _gc_tracer_stw->report_gc_reference_stats(stats);
3948
3949 // We have completed copying any necessary live referent objects.
3950 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3951
3952 make_pending_list_reachable();
3953
3954 rp->verify_no_references_recorded();
3955
3956 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3957 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3958 }
3959
3960 void G1CollectedHeap::make_pending_list_reachable() {
3961 if (collector_state()->in_initial_mark_gc()) {
3962 oop pll_head = Universe::reference_pending_list();
3963 if (pll_head != NULL) {
3964 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3965 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3966 }
3967 }
3968 }
3969
3970 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3971 double merge_pss_time_start = os::elapsedTime();
3972 per_thread_states->flush();
3973 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3974 }
3975
3976 void G1CollectedHeap::pre_evacuate_collection_set() {
3977 _expand_heap_after_alloc_failure = true;
3978 _evacuation_failed = false;
3979
3980 // Disable the hot card cache.
3981 _hot_card_cache->reset_hot_cache_claimed_index();
3982 _hot_card_cache->set_use_cache(false);
3983
3984 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3985 _preserved_marks_set.assert_empty();
3986
3987 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3988
3989 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3990 if (collector_state()->in_initial_mark_gc()) {
3991 double start_clear_claimed_marks = os::elapsedTime();
3992
3993 ClassLoaderDataGraph::clear_claimed_marks();
3994
3995 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3996 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3997 }
3998 }
3999
4000 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
4001 // Should G1EvacuationFailureALot be in effect for this GC?
4002 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4003
4004 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4005
4006 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4007
4008 double start_par_time_sec = os::elapsedTime();
4009 double end_par_time_sec;
4010
4011 {
4012 const uint n_workers = workers()->active_workers();
4013 G1RootProcessor root_processor(this, n_workers);
4014 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4015
4016 print_termination_stats_hdr();
4017
4018 workers()->run_task(&g1_par_task);
4019 end_par_time_sec = os::elapsedTime();
4020
4021 // Closing the inner scope will execute the destructor
4022 // for the G1RootProcessor object. We record the current
4023 // elapsed time before closing the scope so that time
4024 // taken for the destructor is NOT included in the
4025 // reported parallel time.
4026 }
4027
4028 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4029 phase_times->record_par_time(par_time_ms);
4030
4031 double code_root_fixup_time_ms =
4032 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4033 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4034 }
4035
4036 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4037 // Also cleans the card table from temporary duplicate detection information used
4038 // during UpdateRS/ScanRS.
4039 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4040
4041 // Process any discovered reference objects - we have
4042 // to do this _before_ we retire the GC alloc regions
4043 // as we may have to copy some 'reachable' referent
4044 // objects (and their reachable sub-graphs) that were
4045 // not copied during the pause.
4046 process_discovered_references(per_thread_states);
4047
4048 // FIXME
4049 // CM's reference processing also cleans up the string and symbol tables.
4050 // Should we do that here also? We could, but it is a serial operation
4051 // and could significantly increase the pause time.
4052
4053 G1STWIsAliveClosure is_alive(this);
4054 G1KeepAliveClosure keep_alive(this);
4055
4056 {
4057 double start = os::elapsedTime();
4058
4059 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4060
4061 double time_ms = (os::elapsedTime() - start) * 1000.0;
4062 g1_policy()->phase_times()->record_weak_ref_proc_time(time_ms);
4063 }
4064
4065 if (G1StringDedup::is_enabled()) {
4066 double fixup_start = os::elapsedTime();
4067
4068 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4069
4070 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4071 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4072 }
4073
4074 if (evacuation_failed()) {
4075 restore_after_evac_failure();
4076
4077 // Reset the G1EvacuationFailureALot counters and flags
4078 // Note: the values are reset only when an actual
4079 // evacuation failure occurs.
4080 NOT_PRODUCT(reset_evacuation_should_fail();)
4081 }
4082
4083 _preserved_marks_set.assert_empty();
4084
4085 _allocator->release_gc_alloc_regions(evacuation_info);
4086
4087 merge_per_thread_state_info(per_thread_states);
4088
4089 // Reset and re-enable the hot card cache.
4090 // Note the counts for the cards in the regions in the
4091 // collection set are reset when the collection set is freed.
4092 _hot_card_cache->reset_hot_cache();
4093 _hot_card_cache->set_use_cache(true);
4094
4095 purge_code_root_memory();
4096
4097 redirty_logged_cards();
4098 #if COMPILER2_OR_JVMCI
4099 double start = os::elapsedTime();
4100 DerivedPointerTable::update_pointers();
4101 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4102 #endif
4103 g1_policy()->print_age_table();
4104 }
4105
4106 void G1CollectedHeap::record_obj_copy_mem_stats() {
4107 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4108
4109 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4110 create_g1_evac_summary(&_old_evac_stats));
4111 }
4112
4113 void G1CollectedHeap::free_region(HeapRegion* hr,
4114 FreeRegionList* free_list,
4115 bool skip_remset,
4116 bool skip_hot_card_cache,
4117 bool locked) {
4118 assert(!hr->is_free(), "the region should not be free");
4119 assert(!hr->is_empty(), "the region should not be empty");
4120 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4121 assert(free_list != NULL, "pre-condition");
4122
4123 if (G1VerifyBitmaps) {
4124 MemRegion mr(hr->bottom(), hr->end());
4125 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4126 }
4127
4128 // Clear the card counts for this region.
4129 // Note: we only need to do this if the region is not young
4130 // (since we don't refine cards in young regions).
4131 if (!skip_hot_card_cache && !hr->is_young()) {
4132 _hot_card_cache->reset_card_counts(hr);
4133 }
4134 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4135 _g1_policy->remset_tracker()->update_at_free(hr);
4136 free_list->add_ordered(hr);
4137 }
4138
4139 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4140 FreeRegionList* free_list) {
4141 assert(hr->is_humongous(), "this is only for humongous regions");
4142 assert(free_list != NULL, "pre-condition");
4143 hr->clear_humongous();
4144 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4145 }
4146
4147 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4148 const uint humongous_regions_removed) {
4149 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4150 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4151 _old_set.bulk_remove(old_regions_removed);
4152 _humongous_set.bulk_remove(humongous_regions_removed);
4153 }
4154
4155 }
4156
4157 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4158 assert(list != NULL, "list can't be null");
4159 if (!list->is_empty()) {
4160 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4161 _hrm.insert_list_into_free_list(list);
4162 }
4163 }
4164
4165 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4166 decrease_used(bytes);
4167 }
4168
4169 class G1FreeCollectionSetTask : public AbstractGangTask {
4170 private:
4171
4172 // Closure applied to all regions in the collection set to do work that needs to
4173 // be done serially in a single thread.
4174 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4175 private:
4176 EvacuationInfo* _evacuation_info;
4177 const size_t* _surviving_young_words;
4178
4179 // Bytes used in successfully evacuated regions before the evacuation.
4180 size_t _before_used_bytes;
4181 // Bytes used in unsucessfully evacuated regions before the evacuation
4182 size_t _after_used_bytes;
4183
4184 size_t _bytes_allocated_in_old_since_last_gc;
4185
4186 size_t _failure_used_words;
4187 size_t _failure_waste_words;
4188
4189 FreeRegionList _local_free_list;
4190 public:
4191 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4192 HeapRegionClosure(),
4193 _evacuation_info(evacuation_info),
4194 _surviving_young_words(surviving_young_words),
4195 _before_used_bytes(0),
4196 _after_used_bytes(0),
4197 _bytes_allocated_in_old_since_last_gc(0),
4198 _failure_used_words(0),
4199 _failure_waste_words(0),
4200 _local_free_list("Local Region List for CSet Freeing") {
4201 }
4202
4203 virtual bool do_heap_region(HeapRegion* r) {
4204 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4205
4206 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4207 g1h->clear_in_cset(r);
4208
4209 if (r->is_young()) {
4210 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4211 "Young index %d is wrong for region %u of type %s with %u young regions",
4212 r->young_index_in_cset(),
4213 r->hrm_index(),
4214 r->get_type_str(),
4215 g1h->collection_set()->young_region_length());
4216 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4217 r->record_surv_words_in_group(words_survived);
4218 }
4219
4220 if (!r->evacuation_failed()) {
4221 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4222 _before_used_bytes += r->used();
4223 g1h->free_region(r,
4224 &_local_free_list,
4225 true, /* skip_remset */
4226 true, /* skip_hot_card_cache */
4227 true /* locked */);
4228 } else {
4229 r->uninstall_surv_rate_group();
4230 r->set_young_index_in_cset(-1);
4231 r->set_evacuation_failed(false);
4232 // When moving a young gen region to old gen, we "allocate" that whole region
4233 // there. This is in addition to any already evacuated objects. Notify the
4234 // policy about that.
4235 // Old gen regions do not cause an additional allocation: both the objects
4236 // still in the region and the ones already moved are accounted for elsewhere.
4237 if (r->is_young()) {
4238 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4239 }
4240 // The region is now considered to be old.
4241 r->set_old();
4242 // Do some allocation statistics accounting. Regions that failed evacuation
4243 // are always made old, so there is no need to update anything in the young
4244 // gen statistics, but we need to update old gen statistics.
4245 size_t used_words = r->marked_bytes() / HeapWordSize;
4246
4247 _failure_used_words += used_words;
4248 _failure_waste_words += HeapRegion::GrainWords - used_words;
4249
4250 g1h->old_set_add(r);
4251 _after_used_bytes += r->used();
4252 }
4253 return false;
4254 }
4255
4256 void complete_work() {
4257 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4258
4259 _evacuation_info->set_regions_freed(_local_free_list.length());
4260 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4261
4262 g1h->prepend_to_freelist(&_local_free_list);
4263 g1h->decrement_summary_bytes(_before_used_bytes);
4264
4265 G1Policy* policy = g1h->g1_policy();
4266 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4267
4268 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4269 }
4270 };
4271
4272 G1CollectionSet* _collection_set;
4273 G1SerialFreeCollectionSetClosure _cl;
4274 const size_t* _surviving_young_words;
4275
4276 size_t _rs_lengths;
4277
4278 volatile jint _serial_work_claim;
4279
4280 struct WorkItem {
4281 uint region_idx;
4282 bool is_young;
4283 bool evacuation_failed;
4284
4285 WorkItem(HeapRegion* r) {
4286 region_idx = r->hrm_index();
4287 is_young = r->is_young();
4288 evacuation_failed = r->evacuation_failed();
4289 }
4290 };
4291
4292 volatile size_t _parallel_work_claim;
4293 size_t _num_work_items;
4294 WorkItem* _work_items;
4295
4296 void do_serial_work() {
4297 // Need to grab the lock to be allowed to modify the old region list.
4298 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4299 _collection_set->iterate(&_cl);
4300 }
4301
4302 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4303 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4304
4305 HeapRegion* r = g1h->region_at(region_idx);
4306 assert(!g1h->is_on_master_free_list(r), "sanity");
4307
4308 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4309
4310 if (!is_young) {
4311 g1h->_hot_card_cache->reset_card_counts(r);
4312 }
4313
4314 if (!evacuation_failed) {
4315 r->rem_set()->clear_locked();
4316 }
4317 }
4318
4319 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4320 private:
4321 size_t _cur_idx;
4322 WorkItem* _work_items;
4323 public:
4324 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4325
4326 virtual bool do_heap_region(HeapRegion* r) {
4327 _work_items[_cur_idx++] = WorkItem(r);
4328 return false;
4329 }
4330 };
4331
4332 void prepare_work() {
4333 G1PrepareFreeCollectionSetClosure cl(_work_items);
4334 _collection_set->iterate(&cl);
4335 }
4336
4337 void complete_work() {
4338 _cl.complete_work();
4339
4340 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4341 policy->record_max_rs_lengths(_rs_lengths);
4342 policy->cset_regions_freed();
4343 }
4344 public:
4345 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4346 AbstractGangTask("G1 Free Collection Set"),
4347 _cl(evacuation_info, surviving_young_words),
4348 _collection_set(collection_set),
4349 _surviving_young_words(surviving_young_words),
4350 _serial_work_claim(0),
4351 _rs_lengths(0),
4352 _parallel_work_claim(0),
4353 _num_work_items(collection_set->region_length()),
4354 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4355 prepare_work();
4356 }
4357
4358 ~G1FreeCollectionSetTask() {
4359 complete_work();
4360 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4361 }
4362
4363 // Chunk size for work distribution. The chosen value has been determined experimentally
4364 // to be a good tradeoff between overhead and achievable parallelism.
4365 static uint chunk_size() { return 32; }
4366
4367 virtual void work(uint worker_id) {
4368 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4369
4370 // Claim serial work.
4371 if (_serial_work_claim == 0) {
4372 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4373 if (value == 0) {
4374 double serial_time = os::elapsedTime();
4375 do_serial_work();
4376 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4377 }
4378 }
4379
4380 // Start parallel work.
4381 double young_time = 0.0;
4382 bool has_young_time = false;
4383 double non_young_time = 0.0;
4384 bool has_non_young_time = false;
4385
4386 while (true) {
4387 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4388 size_t cur = end - chunk_size();
4389
4390 if (cur >= _num_work_items) {
4391 break;
4392 }
4393
4394 double start_time = os::elapsedTime();
4395
4396 end = MIN2(end, _num_work_items);
4397
4398 for (; cur < end; cur++) {
4399 bool is_young = _work_items[cur].is_young;
4400
4401 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4402
4403 double end_time = os::elapsedTime();
4404 double time_taken = end_time - start_time;
4405 if (is_young) {
4406 young_time += time_taken;
4407 has_young_time = true;
4408 } else {
4409 non_young_time += time_taken;
4410 has_non_young_time = true;
4411 }
4412 start_time = end_time;
4413 }
4414 }
4415
4416 if (has_young_time) {
4417 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4418 }
4419 if (has_non_young_time) {
4420 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4421 }
4422 }
4423 };
4424
4425 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4426 _eden.clear();
4427
4428 double free_cset_start_time = os::elapsedTime();
4429
4430 {
4431 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4432 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4433
4434 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4435
4436 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4437 cl.name(),
4438 num_workers,
4439 _collection_set.region_length());
4440 workers()->run_task(&cl, num_workers);
4441 }
4442 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4443
4444 collection_set->clear();
4445 }
4446
4447 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4448 private:
4449 FreeRegionList* _free_region_list;
4450 HeapRegionSet* _proxy_set;
4451 uint _humongous_objects_reclaimed;
4452 uint _humongous_regions_reclaimed;
4453 size_t _freed_bytes;
4454 public:
4455
4456 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4457 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4458 }
4459
4460 virtual bool do_heap_region(HeapRegion* r) {
4461 if (!r->is_starts_humongous()) {
4462 return false;
4463 }
4464
4465 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4466
4467 oop obj = (oop)r->bottom();
4468 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4469
4470 // The following checks whether the humongous object is live are sufficient.
4471 // The main additional check (in addition to having a reference from the roots
4472 // or the young gen) is whether the humongous object has a remembered set entry.
4473 //
4474 // A humongous object cannot be live if there is no remembered set for it
4475 // because:
4476 // - there can be no references from within humongous starts regions referencing
4477 // the object because we never allocate other objects into them.
4478 // (I.e. there are no intra-region references that may be missed by the
4479 // remembered set)
4480 // - as soon there is a remembered set entry to the humongous starts region
4481 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4482 // until the end of a concurrent mark.
4483 //
4484 // It is not required to check whether the object has been found dead by marking
4485 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4486 // all objects allocated during that time are considered live.
4487 // SATB marking is even more conservative than the remembered set.
4488 // So if at this point in the collection there is no remembered set entry,
4489 // nobody has a reference to it.
4490 // At the start of collection we flush all refinement logs, and remembered sets
4491 // are completely up-to-date wrt to references to the humongous object.
4492 //
4493 // Other implementation considerations:
4494 // - never consider object arrays at this time because they would pose
4495 // considerable effort for cleaning up the the remembered sets. This is
4496 // required because stale remembered sets might reference locations that
4497 // are currently allocated into.
4498 uint region_idx = r->hrm_index();
4499 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4500 !r->rem_set()->is_empty()) {
4501 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",
4502 region_idx,
4503 (size_t)obj->size() * HeapWordSize,
4504 p2i(r->bottom()),
4505 r->rem_set()->occupied(),
4506 r->rem_set()->strong_code_roots_list_length(),
4507 next_bitmap->is_marked(r->bottom()),
4508 g1h->is_humongous_reclaim_candidate(region_idx),
4509 obj->is_typeArray()
4510 );
4511 return false;
4512 }
4513
4514 guarantee(obj->is_typeArray(),
4515 "Only eagerly reclaiming type arrays is supported, but the object "
4516 PTR_FORMAT " is not.", p2i(r->bottom()));
4517
4518 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",
4519 region_idx,
4520 (size_t)obj->size() * HeapWordSize,
4521 p2i(r->bottom()),
4522 r->rem_set()->occupied(),
4523 r->rem_set()->strong_code_roots_list_length(),
4524 next_bitmap->is_marked(r->bottom()),
4525 g1h->is_humongous_reclaim_candidate(region_idx),
4526 obj->is_typeArray()
4527 );
4528
4529 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4530 cm->humongous_object_eagerly_reclaimed(r);
4531 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4532 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4533 region_idx,
4534 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4535 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4536 _humongous_objects_reclaimed++;
4537 do {
4538 HeapRegion* next = g1h->next_region_in_humongous(r);
4539 _freed_bytes += r->used();
4540 r->set_containing_set(NULL);
4541 _humongous_regions_reclaimed++;
4542 g1h->free_humongous_region(r, _free_region_list);
4543 r = next;
4544 } while (r != NULL);
4545
4546 return false;
4547 }
4548
4549 uint humongous_objects_reclaimed() {
4550 return _humongous_objects_reclaimed;
4551 }
4552
4553 uint humongous_regions_reclaimed() {
4554 return _humongous_regions_reclaimed;
4555 }
4556
4557 size_t bytes_freed() const {
4558 return _freed_bytes;
4559 }
4560 };
4561
4562 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4563 assert_at_safepoint_on_vm_thread();
4564
4565 if (!G1EagerReclaimHumongousObjects ||
4566 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4567 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4568 return;
4569 }
4570
4571 double start_time = os::elapsedTime();
4572
4573 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4574
4575 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4576 heap_region_iterate(&cl);
4577
4578 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4579
4580 G1HRPrinter* hrp = hr_printer();
4581 if (hrp->is_active()) {
4582 FreeRegionListIterator iter(&local_cleanup_list);
4583 while (iter.more_available()) {
4584 HeapRegion* hr = iter.get_next();
4585 hrp->cleanup(hr);
4586 }
4587 }
4588
4589 prepend_to_freelist(&local_cleanup_list);
4590 decrement_summary_bytes(cl.bytes_freed());
4591
4592 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4593 cl.humongous_objects_reclaimed());
4594 }
4595
4596 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4597 public:
4598 virtual bool do_heap_region(HeapRegion* r) {
4599 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4600 G1CollectedHeap::heap()->clear_in_cset(r);
4601 r->set_young_index_in_cset(-1);
4602 return false;
4603 }
4604 };
4605
4606 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4607 G1AbandonCollectionSetClosure cl;
4608 collection_set->iterate(&cl);
4609
4610 collection_set->clear();
4611 collection_set->stop_incremental_building();
4612 }
4613
4614 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4615 return _allocator->is_retained_old_region(hr);
4616 }
4617
4618 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4619 _eden.add(hr);
4620 _g1_policy->set_region_eden(hr);
4621 }
4622
4623 #ifdef ASSERT
4624
4625 class NoYoungRegionsClosure: public HeapRegionClosure {
4626 private:
4627 bool _success;
4628 public:
4629 NoYoungRegionsClosure() : _success(true) { }
4630 bool do_heap_region(HeapRegion* r) {
4631 if (r->is_young()) {
4632 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4633 p2i(r->bottom()), p2i(r->end()));
4634 _success = false;
4635 }
4636 return false;
4637 }
4638 bool success() { return _success; }
4639 };
4640
4641 bool G1CollectedHeap::check_young_list_empty() {
4642 bool ret = (young_regions_count() == 0);
4643
4644 NoYoungRegionsClosure closure;
4645 heap_region_iterate(&closure);
4646 ret = ret && closure.success();
4647
4648 return ret;
4649 }
4650
4651 #endif // ASSERT
4652
4653 class TearDownRegionSetsClosure : public HeapRegionClosure {
4654 private:
4655 HeapRegionSet *_old_set;
4656
4657 public:
4658 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4659
4660 bool do_heap_region(HeapRegion* r) {
4661 if (r->is_old()) {
4662 _old_set->remove(r);
4663 } else if(r->is_young()) {
4664 r->uninstall_surv_rate_group();
4665 } else {
4666 // We ignore free regions, we'll empty the free list afterwards.
4667 // We ignore humongous regions, we're not tearing down the
4668 // humongous regions set.
4669 assert(r->is_free() || r->is_humongous(),
4670 "it cannot be another type");
4671 }
4672 return false;
4673 }
4674
4675 ~TearDownRegionSetsClosure() {
4676 assert(_old_set->is_empty(), "post-condition");
4677 }
4678 };
4679
4680 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4681 assert_at_safepoint_on_vm_thread();
4682
4683 if (!free_list_only) {
4684 TearDownRegionSetsClosure cl(&_old_set);
4685 heap_region_iterate(&cl);
4686
4687 // Note that emptying the _young_list is postponed and instead done as
4688 // the first step when rebuilding the regions sets again. The reason for
4689 // this is that during a full GC string deduplication needs to know if
4690 // a collected region was young or old when the full GC was initiated.
4691 }
4692 _hrm.remove_all_free_regions();
4693 }
4694
4695 void G1CollectedHeap::increase_used(size_t bytes) {
4696 _summary_bytes_used += bytes;
4697 }
4698
4699 void G1CollectedHeap::decrease_used(size_t bytes) {
4700 assert(_summary_bytes_used >= bytes,
4701 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4702 _summary_bytes_used, bytes);
4703 _summary_bytes_used -= bytes;
4704 }
4705
4706 void G1CollectedHeap::set_used(size_t bytes) {
4707 _summary_bytes_used = bytes;
4708 }
4709
4710 class RebuildRegionSetsClosure : public HeapRegionClosure {
4711 private:
4712 bool _free_list_only;
4713 HeapRegionSet* _old_set;
4714 HeapRegionManager* _hrm;
4715 size_t _total_used;
4716
4717 public:
4718 RebuildRegionSetsClosure(bool free_list_only,
4719 HeapRegionSet* old_set, HeapRegionManager* hrm) :
4720 _free_list_only(free_list_only),
4721 _old_set(old_set), _hrm(hrm), _total_used(0) {
4722 assert(_hrm->num_free_regions() == 0, "pre-condition");
4723 if (!free_list_only) {
4724 assert(_old_set->is_empty(), "pre-condition");
4725 }
4726 }
4727
4728 bool do_heap_region(HeapRegion* r) {
4729 // After full GC, no region should have a remembered set.
4730 r->rem_set()->clear(true);
4731 if (r->is_empty()) {
4732 // Add free regions to the free list
4733 r->set_free();
4734 _hrm->insert_into_free_list(r);
4735 } else if (!_free_list_only) {
4736
4737 if (r->is_humongous()) {
4738 // We ignore humongous regions. We left the humongous set unchanged.
4739 } else {
4740 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4741 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
4742 r->move_to_old();
4743 _old_set->add(r);
4744 }
4745 _total_used += r->used();
4746 }
4747
4748 return false;
4749 }
4750
4751 size_t total_used() {
4752 return _total_used;
4753 }
4754 };
4755
4756 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4757 assert_at_safepoint_on_vm_thread();
4758
4759 if (!free_list_only) {
4760 _eden.clear();
4761 _survivor.clear();
4762 }
4763
4764 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4765 heap_region_iterate(&cl);
4766
4767 if (!free_list_only) {
4768 set_used(cl.total_used());
4769 if (_archive_allocator != NULL) {
4770 _archive_allocator->clear_used();
4771 }
4772 }
4773 assert(used_unlocked() == recalculate_used(),
4774 "inconsistent used_unlocked(), "
4775 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4776 used_unlocked(), recalculate_used());
4777 }
4778
4779 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4780 HeapRegion* hr = heap_region_containing(p);
4781 return hr->is_in(p);
4782 }
4783
4784 // Methods for the mutator alloc region
4785
4786 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4787 bool force) {
4788 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4789 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4790 if (force || should_allocate) {
4791 HeapRegion* new_alloc_region = new_region(word_size,
4792 false /* is_old */,
4793 false /* do_expand */);
4794 if (new_alloc_region != NULL) {
4795 set_region_short_lived_locked(new_alloc_region);
4796 _hr_printer.alloc(new_alloc_region, !should_allocate);
4797 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4798 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4799 return new_alloc_region;
4800 }
4801 }
4802 return NULL;
4803 }
4804
4805 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4806 size_t allocated_bytes) {
4807 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4808 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4809
4810 collection_set()->add_eden_region(alloc_region);
4811 increase_used(allocated_bytes);
4812 _hr_printer.retire(alloc_region);
4813 // We update the eden sizes here, when the region is retired,
4814 // instead of when it's allocated, since this is the point that its
4815 // used space has been recored in _summary_bytes_used.
4816 g1mm()->update_eden_size();
4817 }
4818
4819 // Methods for the GC alloc regions
4820
4821 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4822 if (dest.is_old()) {
4823 return true;
4824 } else {
4825 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4826 }
4827 }
4828
4829 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4830 assert(FreeList_lock->owned_by_self(), "pre-condition");
4831
4832 if (!has_more_regions(dest)) {
4833 return NULL;
4834 }
4835
4836 const bool is_survivor = dest.is_young();
4837
4838 HeapRegion* new_alloc_region = new_region(word_size,
4839 !is_survivor,
4840 true /* do_expand */);
4841 if (new_alloc_region != NULL) {
4842 if (is_survivor) {
4843 new_alloc_region->set_survivor();
4844 _survivor.add(new_alloc_region);
4845 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4846 } else {
4847 new_alloc_region->set_old();
4848 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4849 }
4850 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4851 _hr_printer.alloc(new_alloc_region);
4852 bool during_im = collector_state()->in_initial_mark_gc();
4853 new_alloc_region->note_start_of_copying(during_im);
4854 return new_alloc_region;
4855 }
4856 return NULL;
4857 }
4858
4859 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4860 size_t allocated_bytes,
4861 InCSetState dest) {
4862 bool during_im = collector_state()->in_initial_mark_gc();
4863 alloc_region->note_end_of_copying(during_im);
4864 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4865 if (dest.is_old()) {
4866 _old_set.add(alloc_region);
4867 }
4868 _hr_printer.retire(alloc_region);
4869 }
4870
4871 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4872 bool expanded = false;
4873 uint index = _hrm.find_highest_free(&expanded);
4874
4875 if (index != G1_NO_HRM_INDEX) {
4876 if (expanded) {
4877 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4878 HeapRegion::GrainWords * HeapWordSize);
4879 }
4880 _hrm.allocate_free_regions_starting_at(index, 1);
4881 return region_at(index);
4882 }
4883 return NULL;
4884 }
4885
4886 // Optimized nmethod scanning
4887
4888 class RegisterNMethodOopClosure: public OopClosure {
4889 G1CollectedHeap* _g1h;
4890 nmethod* _nm;
4891
4892 template <class T> void do_oop_work(T* p) {
4893 T heap_oop = RawAccess<>::oop_load(p);
4894 if (!CompressedOops::is_null(heap_oop)) {
4895 oop obj = CompressedOops::decode_not_null(heap_oop);
4896 HeapRegion* hr = _g1h->heap_region_containing(obj);
4897 assert(!hr->is_continues_humongous(),
4898 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4899 " starting at " HR_FORMAT,
4900 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4901
4902 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4903 hr->add_strong_code_root_locked(_nm);
4904 }
4905 }
4906
4907 public:
4908 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4909 _g1h(g1h), _nm(nm) {}
4910
4911 void do_oop(oop* p) { do_oop_work(p); }
4912 void do_oop(narrowOop* p) { do_oop_work(p); }
4913 };
4914
4915 class UnregisterNMethodOopClosure: public OopClosure {
4916 G1CollectedHeap* _g1h;
4917 nmethod* _nm;
4918
4919 template <class T> void do_oop_work(T* p) {
4920 T heap_oop = RawAccess<>::oop_load(p);
4921 if (!CompressedOops::is_null(heap_oop)) {
4922 oop obj = CompressedOops::decode_not_null(heap_oop);
4923 HeapRegion* hr = _g1h->heap_region_containing(obj);
4924 assert(!hr->is_continues_humongous(),
4925 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4926 " starting at " HR_FORMAT,
4927 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4928
4929 hr->remove_strong_code_root(_nm);
4930 }
4931 }
4932
4933 public:
4934 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4935 _g1h(g1h), _nm(nm) {}
4936
4937 void do_oop(oop* p) { do_oop_work(p); }
4938 void do_oop(narrowOop* p) { do_oop_work(p); }
4939 };
4940
4941 // Returns true if the reference points to an object that
4942 // can move in an incremental collection.
4943 bool G1CollectedHeap::is_scavengable(oop obj) {
4944 HeapRegion* hr = heap_region_containing(obj);
4945 return !hr->is_pinned();
4946 }
4947
4948 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4949 guarantee(nm != NULL, "sanity");
4950 RegisterNMethodOopClosure reg_cl(this, nm);
4951 nm->oops_do(®_cl);
4952 }
4953
4954 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4955 guarantee(nm != NULL, "sanity");
4956 UnregisterNMethodOopClosure reg_cl(this, nm);
4957 nm->oops_do(®_cl, true);
4958 }
4959
4960 void G1CollectedHeap::purge_code_root_memory() {
4961 double purge_start = os::elapsedTime();
4962 G1CodeRootSet::purge();
4963 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4964 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4965 }
4966
4967 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4968 G1CollectedHeap* _g1h;
4969
4970 public:
4971 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4972 _g1h(g1h) {}
4973
4974 void do_code_blob(CodeBlob* cb) {
4975 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4976 if (nm == NULL) {
4977 return;
4978 }
4979
4980 if (ScavengeRootsInCode) {
4981 _g1h->register_nmethod(nm);
4982 }
4983 }
4984 };
4985
4986 void G1CollectedHeap::rebuild_strong_code_roots() {
4987 RebuildStrongCodeRootClosure blob_cl(this);
4988 CodeCache::blobs_do(&blob_cl);
4989 }
4990
4991 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4992 GrowableArray<GCMemoryManager*> memory_managers(2);
4993 memory_managers.append(&_memory_manager);
4994 memory_managers.append(&_full_gc_memory_manager);
4995 return memory_managers;
4996 }
4997
4998 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4999 GrowableArray<MemoryPool*> memory_pools(3);
5000 memory_pools.append(_eden_pool);
5001 memory_pools.append(_survivor_pool);
5002 memory_pools.append(_old_pool);
5003 return memory_pools;
5004 }