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