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/g1BarrierSet.hpp"
34 #include "gc/g1/g1CollectedHeap.inline.hpp"
35 #include "gc/g1/g1CollectionSet.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1EvacStats.inline.hpp"
42 #include "gc/g1/g1FullCollector.hpp"
43 #include "gc/g1/g1GCPhaseTimes.hpp"
44 #include "gc/g1/g1HeapSizingPolicy.hpp"
45 #include "gc/g1/g1HeapTransition.hpp"
46 #include "gc/g1/g1HeapVerifier.hpp"
47 #include "gc/g1/g1HotCardCache.hpp"
48 #include "gc/g1/g1MemoryPool.hpp"
49 #include "gc/g1/g1OopClosures.inline.hpp"
50 #include "gc/g1/g1ParScanThreadState.inline.hpp"
51 #include "gc/g1/g1Policy.hpp"
52 #include "gc/g1/g1RegionToSpaceMapper.hpp"
53 #include "gc/g1/g1RemSet.hpp"
54 #include "gc/g1/g1RootClosures.hpp"
55 #include "gc/g1/g1RootProcessor.hpp"
56 #include "gc/g1/g1StringDedup.hpp"
57 #include "gc/g1/g1ThreadLocalData.hpp"
58 #include "gc/g1/g1YCTypes.hpp"
59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
60 #include "gc/g1/heapRegion.inline.hpp"
61 #include "gc/g1/heapRegionRemSet.hpp"
62 #include "gc/g1/heapRegionSet.inline.hpp"
63 #include "gc/g1/vm_operations_g1.hpp"
64 #include "gc/shared/adaptiveSizePolicy.hpp"
65 #include "gc/shared/gcHeapSummary.hpp"
66 #include "gc/shared/gcId.hpp"
67 #include "gc/shared/gcLocker.hpp"
68 #include "gc/shared/gcTimer.hpp"
69 #include "gc/shared/gcTrace.hpp"
70 #include "gc/shared/gcTraceTime.inline.hpp"
71 #include "gc/shared/generationSpec.hpp"
72 #include "gc/shared/isGCActiveMark.hpp"
73 #include "gc/shared/preservedMarks.inline.hpp"
74 #include "gc/shared/suspendibleThreadSet.hpp"
75 #include "gc/shared/referenceProcessor.inline.hpp"
76 #include "gc/shared/taskqueue.inline.hpp"
77 #include "gc/shared/weakProcessor.hpp"
78 #include "logging/log.hpp"
79 #include "memory/allocation.hpp"
80 #include "memory/iterator.hpp"
81 #include "memory/resourceArea.hpp"
82 #include "oops/access.inline.hpp"
83 #include "oops/compressedOops.inline.hpp"
84 #include "oops/oop.inline.hpp"
85 #include "prims/resolvedMethodTable.hpp"
86 #include "runtime/atomic.hpp"
87 #include "runtime/handles.inline.hpp"
88 #include "runtime/init.hpp"
89 #include "runtime/orderAccess.inline.hpp"
90 #include "runtime/threadSMR.hpp"
91 #include "runtime/vmThread.hpp"
92 #include "utilities/align.hpp"
93 #include "utilities/globalDefinitions.hpp"
94 #include "utilities/stack.inline.hpp"
95
96 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
97
98 // INVARIANTS/NOTES
99 //
100 // All allocation activity covered by the G1CollectedHeap interface is
101 // serialized by acquiring the HeapLock. This happens in mem_allocate
102 // and allocate_new_tlab, which are the "entry" points to the
103 // allocation code from the rest of the JVM. (Note that this does not
104 // apply to TLAB allocation, which is not part of this interface: it
105 // is done by clients of this interface.)
106
107 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
108 private:
109 size_t _num_dirtied;
110 G1CollectedHeap* _g1h;
111 G1CardTable* _g1_ct;
112
113 HeapRegion* region_for_card(jbyte* card_ptr) const {
114 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
115 }
116
117 bool will_become_free(HeapRegion* hr) const {
118 // A region will be freed by free_collection_set if the region is in the
119 // collection set and has not had an evacuation failure.
120 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
121 }
122
123 public:
124 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
125 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
126
127 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
128 HeapRegion* hr = region_for_card(card_ptr);
129
130 // Should only dirty cards in regions that won't be freed.
131 if (!will_become_free(hr)) {
132 *card_ptr = G1CardTable::dirty_card_val();
133 _num_dirtied++;
134 }
135
136 return true;
137 }
138
139 size_t num_dirtied() const { return _num_dirtied; }
140 };
141
142
143 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
144 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
145 }
146
147 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
148 // The from card cache is not the memory that is actually committed. So we cannot
149 // take advantage of the zero_filled parameter.
150 reset_from_card_cache(start_idx, num_regions);
151 }
152
153
154 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
155 MemRegion mr) {
156 return new HeapRegion(hrs_index, bot(), mr);
157 }
158
159 // Private methods.
160
161 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
162 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
163 "the only time we use this to allocate a humongous region is "
164 "when we are allocating a single humongous region");
165
166 HeapRegion* res = _hrm.allocate_free_region(is_old);
167
168 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
169 // Currently, only attempts to allocate GC alloc regions set
170 // do_expand to true. So, we should only reach here during a
171 // safepoint. If this assumption changes we might have to
172 // reconsider the use of _expand_heap_after_alloc_failure.
173 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
174
175 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
176 word_size * HeapWordSize);
177
178 if (expand(word_size * HeapWordSize)) {
179 // Given that expand() succeeded in expanding the heap, and we
180 // always expand the heap by an amount aligned to the heap
181 // region size, the free list should in theory not be empty.
182 // In either case allocate_free_region() will check for NULL.
183 res = _hrm.allocate_free_region(is_old);
184 } else {
185 _expand_heap_after_alloc_failure = false;
186 }
187 }
188 return res;
189 }
190
191 HeapWord*
192 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
193 uint num_regions,
194 size_t word_size) {
195 assert(first != G1_NO_HRM_INDEX, "pre-condition");
196 assert(is_humongous(word_size), "word_size should be humongous");
197 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
198
199 // Index of last region in the series.
200 uint last = first + num_regions - 1;
201
202 // We need to initialize the region(s) we just discovered. This is
203 // a bit tricky given that it can happen concurrently with
204 // refinement threads refining cards on these regions and
205 // potentially wanting to refine the BOT as they are scanning
206 // those cards (this can happen shortly after a cleanup; see CR
207 // 6991377). So we have to set up the region(s) carefully and in
208 // a specific order.
209
210 // The word size sum of all the regions we will allocate.
211 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
212 assert(word_size <= word_size_sum, "sanity");
213
214 // This will be the "starts humongous" region.
215 HeapRegion* first_hr = region_at(first);
216 // The header of the new object will be placed at the bottom of
217 // the first region.
218 HeapWord* new_obj = first_hr->bottom();
219 // This will be the new top of the new object.
220 HeapWord* obj_top = new_obj + word_size;
221
222 // First, we need to zero the header of the space that we will be
223 // allocating. When we update top further down, some refinement
224 // threads might try to scan the region. By zeroing the header we
225 // ensure that any thread that will try to scan the region will
226 // come across the zero klass word and bail out.
227 //
228 // NOTE: It would not have been correct to have used
229 // CollectedHeap::fill_with_object() and make the space look like
230 // an int array. The thread that is doing the allocation will
231 // later update the object header to a potentially different array
232 // type and, for a very short period of time, the klass and length
233 // fields will be inconsistent. This could cause a refinement
234 // thread to calculate the object size incorrectly.
235 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
236
237 // Next, pad out the unused tail of the last region with filler
238 // objects, for improved usage accounting.
239 // How many words we use for filler objects.
240 size_t word_fill_size = word_size_sum - word_size;
241
242 // How many words memory we "waste" which cannot hold a filler object.
243 size_t words_not_fillable = 0;
244
245 if (word_fill_size >= min_fill_size()) {
246 fill_with_objects(obj_top, word_fill_size);
247 } else if (word_fill_size > 0) {
248 // We have space to fill, but we cannot fit an object there.
249 words_not_fillable = word_fill_size;
250 word_fill_size = 0;
251 }
252
253 // We will set up the first region as "starts humongous". This
254 // will also update the BOT covering all the regions to reflect
255 // that there is a single object that starts at the bottom of the
256 // first region.
257 first_hr->set_starts_humongous(obj_top, word_fill_size);
258 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
259 // Then, if there are any, we will set up the "continues
260 // humongous" regions.
261 HeapRegion* hr = NULL;
262 for (uint i = first + 1; i <= last; ++i) {
263 hr = region_at(i);
264 hr->set_continues_humongous(first_hr);
265 _g1_policy->remset_tracker()->update_at_allocate(hr);
266 }
267
268 // Up to this point no concurrent thread would have been able to
269 // do any scanning on any region in this series. All the top
270 // fields still point to bottom, so the intersection between
271 // [bottom,top] and [card_start,card_end] will be empty. Before we
272 // update the top fields, we'll do a storestore to make sure that
273 // no thread sees the update to top before the zeroing of the
274 // object header and the BOT initialization.
275 OrderAccess::storestore();
276
277 // Now, we will update the top fields of the "continues humongous"
278 // regions except the last one.
279 for (uint i = first; i < last; ++i) {
280 hr = region_at(i);
281 hr->set_top(hr->end());
282 }
283
284 hr = region_at(last);
285 // If we cannot fit a filler object, we must set top to the end
286 // of the humongous object, otherwise we cannot iterate the heap
287 // and the BOT will not be complete.
288 hr->set_top(hr->end() - words_not_fillable);
289
290 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
291 "obj_top should be in last region");
292
293 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
294
295 assert(words_not_fillable == 0 ||
296 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
297 "Miscalculation in humongous allocation");
298
299 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
300
301 for (uint i = first; i <= last; ++i) {
302 hr = region_at(i);
303 _humongous_set.add(hr);
304 _hr_printer.alloc(hr);
305 }
306
307 return new_obj;
308 }
309
310 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
311 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
312 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
313 }
314
315 // If could fit into free regions w/o expansion, try.
316 // Otherwise, if can expand, do so.
317 // Otherwise, if using ex regions might help, try with ex given back.
318 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
319 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
320
321 _verifier->verify_region_sets_optional();
322
323 uint first = G1_NO_HRM_INDEX;
324 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
325
326 if (obj_regions == 1) {
327 // Only one region to allocate, try to use a fast path by directly allocating
328 // from the free lists. Do not try to expand here, we will potentially do that
329 // later.
330 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
331 if (hr != NULL) {
332 first = hr->hrm_index();
333 }
334 } else {
335 // Policy: Try only empty regions (i.e. already committed first). Maybe we
336 // are lucky enough to find some.
337 first = _hrm.find_contiguous_only_empty(obj_regions);
338 if (first != G1_NO_HRM_INDEX) {
339 _hrm.allocate_free_regions_starting_at(first, obj_regions);
340 }
341 }
342
343 if (first == G1_NO_HRM_INDEX) {
344 // Policy: We could not find enough regions for the humongous object in the
345 // free list. Look through the heap to find a mix of free and uncommitted regions.
346 // If so, try expansion.
347 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
348 if (first != G1_NO_HRM_INDEX) {
349 // We found something. Make sure these regions are committed, i.e. expand
350 // the heap. Alternatively we could do a defragmentation GC.
351 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
352 word_size * HeapWordSize);
353
354 _hrm.expand_at(first, obj_regions, workers());
355 g1_policy()->record_new_heap_size(num_regions());
356
357 #ifdef ASSERT
358 for (uint i = first; i < first + obj_regions; ++i) {
359 HeapRegion* hr = region_at(i);
360 assert(hr->is_free(), "sanity");
361 assert(hr->is_empty(), "sanity");
362 assert(is_on_master_free_list(hr), "sanity");
363 }
364 #endif
365 _hrm.allocate_free_regions_starting_at(first, obj_regions);
366 } else {
367 // Policy: Potentially trigger a defragmentation GC.
368 }
369 }
370
371 HeapWord* result = NULL;
372 if (first != G1_NO_HRM_INDEX) {
373 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
374 assert(result != NULL, "it should always return a valid result");
375
376 // A successful humongous object allocation changes the used space
377 // information of the old generation so we need to recalculate the
378 // sizes and update the jstat counters here.
379 g1mm()->update_sizes();
380 }
381
382 _verifier->verify_region_sets_optional();
383
384 return result;
385 }
386
387 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_word_size,
388 size_t desired_word_size,
389 size_t* actual_word_size) {
390 assert_heap_not_locked_and_not_at_safepoint();
391 assert(!is_humongous(desired_word_size), "we do not allow humongous TLABs");
392
393 return attempt_allocation(min_word_size, desired_word_size, actual_word_size);
394 }
395
396 HeapWord*
397 G1CollectedHeap::mem_allocate(size_t word_size,
398 bool* gc_overhead_limit_was_exceeded) {
399 assert_heap_not_locked_and_not_at_safepoint();
400
401 if (is_humongous(word_size)) {
402 return attempt_allocation_humongous(word_size);
403 }
404 size_t dummy = 0;
405 return attempt_allocation(word_size, word_size, &dummy);
406 }
407
408 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
409 ResourceMark rm; // For retrieving the thread names in log messages.
410
411 // Make sure you read the note in attempt_allocation_humongous().
412
413 assert_heap_not_locked_and_not_at_safepoint();
414 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
415 "be called for humongous allocation requests");
416
417 // We should only get here after the first-level allocation attempt
418 // (attempt_allocation()) failed to allocate.
419
420 // We will loop until a) we manage to successfully perform the
421 // allocation or b) we successfully schedule a collection which
422 // fails to perform the allocation. b) is the only case when we'll
423 // return NULL.
424 HeapWord* result = NULL;
425 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
426 bool should_try_gc;
427 uint gc_count_before;
428
429 {
430 MutexLockerEx x(Heap_lock);
431 result = _allocator->attempt_allocation_locked(word_size);
432 if (result != NULL) {
433 return result;
434 }
435
436 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
437 // This is different to when only GCLocker::needs_gc() is set: try to avoid
438 // waiting because the GCLocker is active to not wait too long.
439 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
440 // No need for an ergo message here, can_expand_young_list() does this when
441 // it returns true.
442 result = _allocator->attempt_allocation_force(word_size);
443 if (result != NULL) {
444 return result;
445 }
446 }
447 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
448 // the GCLocker initiated GC has been performed and then retry. This includes
449 // the case when the GC Locker is not active but has not been performed.
450 should_try_gc = !GCLocker::needs_gc();
451 // Read the GC count while still holding the Heap_lock.
452 gc_count_before = total_collections();
453 }
454
455 if (should_try_gc) {
456 bool succeeded;
457 result = do_collection_pause(word_size, gc_count_before, &succeeded,
458 GCCause::_g1_inc_collection_pause);
459 if (result != NULL) {
460 assert(succeeded, "only way to get back a non-NULL result");
461 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
462 Thread::current()->name(), p2i(result));
463 return result;
464 }
465
466 if (succeeded) {
467 // We successfully scheduled a collection which failed to allocate. No
468 // point in trying to allocate further. We'll just return NULL.
469 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
470 SIZE_FORMAT " words", Thread::current()->name(), word_size);
471 return NULL;
472 }
473 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
474 Thread::current()->name(), word_size);
475 } else {
476 // Failed to schedule a collection.
477 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
478 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
479 SIZE_FORMAT " words", Thread::current()->name(), word_size);
480 return NULL;
481 }
482 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
483 // The GCLocker is either active or the GCLocker initiated
484 // GC has not yet been performed. Stall until it is and
485 // then retry the allocation.
486 GCLocker::stall_until_clear();
487 gclocker_retry_count += 1;
488 }
489
490 // We can reach here if we were unsuccessful in scheduling a
491 // collection (because another thread beat us to it) or if we were
492 // stalled due to the GC locker. In either can we should retry the
493 // allocation attempt in case another thread successfully
494 // performed a collection and reclaimed enough space. We do the
495 // first attempt (without holding the Heap_lock) here and the
496 // follow-on attempt will be at the start of the next loop
497 // iteration (after taking the Heap_lock).
498 size_t dummy = 0;
499 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
500 if (result != NULL) {
501 return result;
502 }
503
504 // Give a warning if we seem to be looping forever.
505 if ((QueuedAllocationWarningCount > 0) &&
506 (try_count % QueuedAllocationWarningCount == 0)) {
507 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
508 Thread::current()->name(), try_count, word_size);
509 }
510 }
511
512 ShouldNotReachHere();
513 return NULL;
514 }
515
516 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
517 assert_at_safepoint_on_vm_thread();
518 if (_archive_allocator == NULL) {
519 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
520 }
521 }
522
523 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
524 // Allocations in archive regions cannot be of a size that would be considered
525 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
526 // may be different at archive-restore time.
527 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
528 }
529
530 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
531 assert_at_safepoint_on_vm_thread();
532 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
533 if (is_archive_alloc_too_large(word_size)) {
534 return NULL;
535 }
536 return _archive_allocator->archive_mem_allocate(word_size);
537 }
538
539 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
540 size_t end_alignment_in_bytes) {
541 assert_at_safepoint_on_vm_thread();
542 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
543
544 // Call complete_archive to do the real work, filling in the MemRegion
545 // array with the archive regions.
546 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
547 delete _archive_allocator;
548 _archive_allocator = NULL;
549 }
550
551 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
552 assert(ranges != NULL, "MemRegion array NULL");
553 assert(count != 0, "No MemRegions provided");
554 MemRegion reserved = _hrm.reserved();
555 for (size_t i = 0; i < count; i++) {
556 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
557 return false;
558 }
559 }
560 return true;
561 }
562
563 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
564 size_t count,
565 bool open) {
566 assert(!is_init_completed(), "Expect to be called at JVM init time");
567 assert(ranges != NULL, "MemRegion array NULL");
568 assert(count != 0, "No MemRegions provided");
569 MutexLockerEx x(Heap_lock);
570
571 MemRegion reserved = _hrm.reserved();
572 HeapWord* prev_last_addr = NULL;
573 HeapRegion* prev_last_region = NULL;
574
575 // Temporarily disable pretouching of heap pages. This interface is used
576 // when mmap'ing archived heap data in, so pre-touching is wasted.
577 FlagSetting fs(AlwaysPreTouch, false);
578
579 // Enable archive object checking used by G1MarkSweep. We have to let it know
580 // about each archive range, so that objects in those ranges aren't marked.
581 G1ArchiveAllocator::enable_archive_object_check();
582
583 // For each specified MemRegion range, allocate the corresponding G1
584 // regions and mark them as archive regions. We expect the ranges
585 // in ascending starting address order, without overlap.
586 for (size_t i = 0; i < count; i++) {
587 MemRegion curr_range = ranges[i];
588 HeapWord* start_address = curr_range.start();
589 size_t word_size = curr_range.word_size();
590 HeapWord* last_address = curr_range.last();
591 size_t commits = 0;
592
593 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
594 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
595 p2i(start_address), p2i(last_address));
596 guarantee(start_address > prev_last_addr,
597 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
598 p2i(start_address), p2i(prev_last_addr));
599 prev_last_addr = last_address;
600
601 // Check for ranges that start in the same G1 region in which the previous
602 // range ended, and adjust the start address so we don't try to allocate
603 // the same region again. If the current range is entirely within that
604 // region, skip it, just adjusting the recorded top.
605 HeapRegion* start_region = _hrm.addr_to_region(start_address);
606 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
607 start_address = start_region->end();
608 if (start_address > last_address) {
609 increase_used(word_size * HeapWordSize);
610 start_region->set_top(last_address + 1);
611 continue;
612 }
613 start_region->set_top(start_address);
614 curr_range = MemRegion(start_address, last_address + 1);
615 start_region = _hrm.addr_to_region(start_address);
616 }
617
618 // Perform the actual region allocation, exiting if it fails.
619 // Then note how much new space we have allocated.
620 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
621 return false;
622 }
623 increase_used(word_size * HeapWordSize);
624 if (commits != 0) {
625 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
626 HeapRegion::GrainWords * HeapWordSize * commits);
627
628 }
629
630 // Mark each G1 region touched by the range as archive, add it to
631 // the old set, and set top.
632 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
633 HeapRegion* last_region = _hrm.addr_to_region(last_address);
634 prev_last_region = last_region;
635
636 while (curr_region != NULL) {
637 assert(curr_region->is_empty() && !curr_region->is_pinned(),
638 "Region already in use (index %u)", curr_region->hrm_index());
639 if (open) {
640 curr_region->set_open_archive();
641 } else {
642 curr_region->set_closed_archive();
643 }
644 _hr_printer.alloc(curr_region);
645 _old_set.add(curr_region);
646 HeapWord* top;
647 HeapRegion* next_region;
648 if (curr_region != last_region) {
649 top = curr_region->end();
650 next_region = _hrm.next_region_in_heap(curr_region);
651 } else {
652 top = last_address + 1;
653 next_region = NULL;
654 }
655 curr_region->set_top(top);
656 curr_region->set_first_dead(top);
657 curr_region->set_end_of_live(top);
658 curr_region = next_region;
659 }
660
661 // Notify mark-sweep of the archive
662 G1ArchiveAllocator::set_range_archive(curr_range, open);
663 }
664 return true;
665 }
666
667 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
668 assert(!is_init_completed(), "Expect to be called at JVM init time");
669 assert(ranges != NULL, "MemRegion array NULL");
670 assert(count != 0, "No MemRegions provided");
671 MemRegion reserved = _hrm.reserved();
672 HeapWord *prev_last_addr = NULL;
673 HeapRegion* prev_last_region = NULL;
674
675 // For each MemRegion, create filler objects, if needed, in the G1 regions
676 // that contain the address range. The address range actually within the
677 // MemRegion will not be modified. That is assumed to have been initialized
678 // elsewhere, probably via an mmap of archived heap data.
679 MutexLockerEx x(Heap_lock);
680 for (size_t i = 0; i < count; i++) {
681 HeapWord* start_address = ranges[i].start();
682 HeapWord* last_address = ranges[i].last();
683
684 assert(reserved.contains(start_address) && reserved.contains(last_address),
685 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
686 p2i(start_address), p2i(last_address));
687 assert(start_address > prev_last_addr,
688 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
689 p2i(start_address), p2i(prev_last_addr));
690
691 HeapRegion* start_region = _hrm.addr_to_region(start_address);
692 HeapRegion* last_region = _hrm.addr_to_region(last_address);
693 HeapWord* bottom_address = start_region->bottom();
694
695 // Check for a range beginning in the same region in which the
696 // previous one ended.
697 if (start_region == prev_last_region) {
698 bottom_address = prev_last_addr + 1;
699 }
700
701 // Verify that the regions were all marked as archive regions by
702 // alloc_archive_regions.
703 HeapRegion* curr_region = start_region;
704 while (curr_region != NULL) {
705 guarantee(curr_region->is_archive(),
706 "Expected archive region at index %u", curr_region->hrm_index());
707 if (curr_region != last_region) {
708 curr_region = _hrm.next_region_in_heap(curr_region);
709 } else {
710 curr_region = NULL;
711 }
712 }
713
714 prev_last_addr = last_address;
715 prev_last_region = last_region;
716
717 // Fill the memory below the allocated range with dummy object(s),
718 // if the region bottom does not match the range start, or if the previous
719 // range ended within the same G1 region, and there is a gap.
720 if (start_address != bottom_address) {
721 size_t fill_size = pointer_delta(start_address, bottom_address);
722 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
723 increase_used(fill_size * HeapWordSize);
724 }
725 }
726 }
727
728 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
729 size_t desired_word_size,
730 size_t* actual_word_size) {
731 assert_heap_not_locked_and_not_at_safepoint();
732 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
733 "be called for humongous allocation requests");
734
735 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
736
737 if (result == NULL) {
738 *actual_word_size = desired_word_size;
739 result = attempt_allocation_slow(desired_word_size);
740 }
741
742 assert_heap_not_locked();
743 if (result != NULL) {
744 assert(*actual_word_size != 0, "Actual size must have been set here");
745 dirty_young_block(result, *actual_word_size);
746 }
747 return result;
748 }
749
750 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
751 assert(!is_init_completed(), "Expect to be called at JVM init time");
752 assert(ranges != NULL, "MemRegion array NULL");
753 assert(count != 0, "No MemRegions provided");
754 MemRegion reserved = _hrm.reserved();
755 HeapWord* prev_last_addr = NULL;
756 HeapRegion* prev_last_region = NULL;
757 size_t size_used = 0;
758 size_t uncommitted_regions = 0;
759
760 // For each Memregion, free the G1 regions that constitute it, and
761 // notify mark-sweep that the range is no longer to be considered 'archive.'
762 MutexLockerEx x(Heap_lock);
763 for (size_t i = 0; i < count; i++) {
764 HeapWord* start_address = ranges[i].start();
765 HeapWord* last_address = ranges[i].last();
766
767 assert(reserved.contains(start_address) && reserved.contains(last_address),
768 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
769 p2i(start_address), p2i(last_address));
770 assert(start_address > prev_last_addr,
771 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
772 p2i(start_address), p2i(prev_last_addr));
773 size_used += ranges[i].byte_size();
774 prev_last_addr = last_address;
775
776 HeapRegion* start_region = _hrm.addr_to_region(start_address);
777 HeapRegion* last_region = _hrm.addr_to_region(last_address);
778
779 // Check for ranges that start in the same G1 region in which the previous
780 // range ended, and adjust the start address so we don't try to free
781 // the same region again. If the current range is entirely within that
782 // region, skip it.
783 if (start_region == prev_last_region) {
784 start_address = start_region->end();
785 if (start_address > last_address) {
786 continue;
787 }
788 start_region = _hrm.addr_to_region(start_address);
789 }
790 prev_last_region = last_region;
791
792 // After verifying that each region was marked as an archive region by
793 // alloc_archive_regions, set it free and empty and uncommit it.
794 HeapRegion* curr_region = start_region;
795 while (curr_region != NULL) {
796 guarantee(curr_region->is_archive(),
797 "Expected archive region at index %u", curr_region->hrm_index());
798 uint curr_index = curr_region->hrm_index();
799 _old_set.remove(curr_region);
800 curr_region->set_free();
801 curr_region->set_top(curr_region->bottom());
802 if (curr_region != last_region) {
803 curr_region = _hrm.next_region_in_heap(curr_region);
804 } else {
805 curr_region = NULL;
806 }
807 _hrm.shrink_at(curr_index, 1);
808 uncommitted_regions++;
809 }
810
811 // Notify mark-sweep that this is no longer an archive range.
812 G1ArchiveAllocator::set_range_archive(ranges[i], false);
813 }
814
815 if (uncommitted_regions != 0) {
816 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
817 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
818 }
819 decrease_used(size_used);
820 }
821
822 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
823 ResourceMark rm; // For retrieving the thread names in log messages.
824
825 // The structure of this method has a lot of similarities to
826 // attempt_allocation_slow(). The reason these two were not merged
827 // into a single one is that such a method would require several "if
828 // allocation is not humongous do this, otherwise do that"
829 // conditional paths which would obscure its flow. In fact, an early
830 // version of this code did use a unified method which was harder to
831 // follow and, as a result, it had subtle bugs that were hard to
832 // track down. So keeping these two methods separate allows each to
833 // be more readable. It will be good to keep these two in sync as
834 // much as possible.
835
836 assert_heap_not_locked_and_not_at_safepoint();
837 assert(is_humongous(word_size), "attempt_allocation_humongous() "
838 "should only be called for humongous allocations");
839
840 // Humongous objects can exhaust the heap quickly, so we should check if we
841 // need to start a marking cycle at each humongous object allocation. We do
842 // the check before we do the actual allocation. The reason for doing it
843 // before the allocation is that we avoid having to keep track of the newly
844 // allocated memory while we do a GC.
845 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
846 word_size)) {
847 collect(GCCause::_g1_humongous_allocation);
848 }
849
850 // We will loop until a) we manage to successfully perform the
851 // allocation or b) we successfully schedule a collection which
852 // fails to perform the allocation. b) is the only case when we'll
853 // return NULL.
854 HeapWord* result = NULL;
855 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
856 bool should_try_gc;
857 uint gc_count_before;
858
859
860 {
861 MutexLockerEx x(Heap_lock);
862
863 // Given that humongous objects are not allocated in young
864 // regions, we'll first try to do the allocation without doing a
865 // collection hoping that there's enough space in the heap.
866 result = humongous_obj_allocate(word_size);
867 if (result != NULL) {
868 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
869 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
870 return result;
871 }
872
873 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
874 // the GCLocker initiated GC has been performed and then retry. This includes
875 // the case when the GC Locker is not active but has not been performed.
876 should_try_gc = !GCLocker::needs_gc();
877 // Read the GC count while still holding the Heap_lock.
878 gc_count_before = total_collections();
879 }
880
881 if (should_try_gc) {
882 bool succeeded;
883 result = do_collection_pause(word_size, gc_count_before, &succeeded,
884 GCCause::_g1_humongous_allocation);
885 if (result != NULL) {
886 assert(succeeded, "only way to get back a non-NULL result");
887 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
888 Thread::current()->name(), p2i(result));
889 return result;
890 }
891
892 if (succeeded) {
893 // We successfully scheduled a collection which failed to allocate. No
894 // point in trying to allocate further. We'll just return NULL.
895 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
896 SIZE_FORMAT " words", Thread::current()->name(), word_size);
897 return NULL;
898 }
899 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
900 Thread::current()->name(), word_size);
901 } else {
902 // Failed to schedule a collection.
903 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
904 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
905 SIZE_FORMAT " words", Thread::current()->name(), word_size);
906 return NULL;
907 }
908 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
909 // The GCLocker is either active or the GCLocker initiated
910 // GC has not yet been performed. Stall until it is and
911 // then retry the allocation.
912 GCLocker::stall_until_clear();
913 gclocker_retry_count += 1;
914 }
915
916
917 // We can reach here if we were unsuccessful in scheduling a
918 // collection (because another thread beat us to it) or if we were
919 // stalled due to the GC locker. In either can we should retry the
920 // allocation attempt in case another thread successfully
921 // performed a collection and reclaimed enough space.
922 // Humongous object allocation always needs a lock, so we wait for the retry
923 // in the next iteration of the loop, unlike for the regular iteration case.
924 // Give a warning if we seem to be looping forever.
925
926 if ((QueuedAllocationWarningCount > 0) &&
927 (try_count % QueuedAllocationWarningCount == 0)) {
928 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
929 Thread::current()->name(), try_count, word_size);
930 }
931 }
932
933 ShouldNotReachHere();
934 return NULL;
935 }
936
937 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
938 bool expect_null_mutator_alloc_region) {
939 assert_at_safepoint_on_vm_thread();
940 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
941 "the current alloc region was unexpectedly found to be non-NULL");
942
943 if (!is_humongous(word_size)) {
944 return _allocator->attempt_allocation_locked(word_size);
945 } else {
946 HeapWord* result = humongous_obj_allocate(word_size);
947 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
948 collector_state()->set_initiate_conc_mark_if_possible(true);
949 }
950 return result;
951 }
952
953 ShouldNotReachHere();
954 }
955
956 class PostCompactionPrinterClosure: public HeapRegionClosure {
957 private:
958 G1HRPrinter* _hr_printer;
959 public:
960 bool do_heap_region(HeapRegion* hr) {
961 assert(!hr->is_young(), "not expecting to find young regions");
962 _hr_printer->post_compaction(hr);
963 return false;
964 }
965
966 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
967 : _hr_printer(hr_printer) { }
968 };
969
970 void G1CollectedHeap::print_hrm_post_compaction() {
971 if (_hr_printer.is_active()) {
972 PostCompactionPrinterClosure cl(hr_printer());
973 heap_region_iterate(&cl);
974 }
975 }
976
977 void G1CollectedHeap::abort_concurrent_cycle() {
978 // If we start the compaction before the CM threads finish
979 // scanning the root regions we might trip them over as we'll
980 // be moving objects / updating references. So let's wait until
981 // they are done. By telling them to abort, they should complete
982 // early.
983 _cm->root_regions()->abort();
984 _cm->root_regions()->wait_until_scan_finished();
985
986 // Disable discovery and empty the discovered lists
987 // for the CM ref processor.
988 ref_processor_cm()->disable_discovery();
989 ref_processor_cm()->abandon_partial_discovery();
990 ref_processor_cm()->verify_no_references_recorded();
991
992 // Abandon current iterations of concurrent marking and concurrent
993 // refinement, if any are in progress.
994 concurrent_mark()->concurrent_cycle_abort();
995 }
996
997 void G1CollectedHeap::prepare_heap_for_full_collection() {
998 // Make sure we'll choose a new allocation region afterwards.
999 _allocator->release_mutator_alloc_region();
1000 _allocator->abandon_gc_alloc_regions();
1001 g1_rem_set()->cleanupHRRS();
1002
1003 // We may have added regions to the current incremental collection
1004 // set between the last GC or pause and now. We need to clear the
1005 // incremental collection set and then start rebuilding it afresh
1006 // after this full GC.
1007 abandon_collection_set(collection_set());
1008
1009 tear_down_region_sets(false /* free_list_only */);
1010 }
1011
1012 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1013 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1014 assert(used() == recalculate_used(), "Should be equal");
1015 _verifier->verify_region_sets_optional();
1016 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1017 _verifier->check_bitmaps("Full GC Start");
1018 }
1019
1020 void G1CollectedHeap::prepare_heap_for_mutators() {
1021 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1022 ClassLoaderDataGraph::purge();
1023 MetaspaceUtils::verify_metrics();
1024
1025 // Prepare heap for normal collections.
1026 assert(num_free_regions() == 0, "we should not have added any free regions");
1027 rebuild_region_sets(false /* free_list_only */);
1028 abort_refinement();
1029 resize_if_necessary_after_full_collection();
1030
1031 // Rebuild the strong code root lists for each region
1032 rebuild_strong_code_roots();
1033
1034 // Start a new incremental collection set for the next pause
1035 start_new_collection_set();
1036
1037 _allocator->init_mutator_alloc_region();
1038
1039 // Post collection state updates.
1040 MetaspaceGC::compute_new_size();
1041 }
1042
1043 void G1CollectedHeap::abort_refinement() {
1044 if (_hot_card_cache->use_cache()) {
1045 _hot_card_cache->reset_hot_cache();
1046 }
1047
1048 // Discard all remembered set updates.
1049 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1050 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1051 }
1052
1053 void G1CollectedHeap::verify_after_full_collection() {
1054 _hrm.verify_optional();
1055 _verifier->verify_region_sets_optional();
1056 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1057 // Clear the previous marking bitmap, if needed for bitmap verification.
1058 // Note we cannot do this when we clear the next marking bitmap in
1059 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1060 // objects marked during a full GC against the previous bitmap.
1061 // But we need to clear it before calling check_bitmaps below since
1062 // the full GC has compacted objects and updated TAMS but not updated
1063 // the prev bitmap.
1064 if (G1VerifyBitmaps) {
1065 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1066 _cm->clear_prev_bitmap(workers());
1067 }
1068 _verifier->check_bitmaps("Full GC End");
1069
1070 // At this point there should be no regions in the
1071 // entire heap tagged as young.
1072 assert(check_young_list_empty(), "young list should be empty at this point");
1073
1074 // Note: since we've just done a full GC, concurrent
1075 // marking is no longer active. Therefore we need not
1076 // re-enable reference discovery for the CM ref processor.
1077 // That will be done at the start of the next marking cycle.
1078 // We also know that the STW processor should no longer
1079 // discover any new references.
1080 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1081 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1082 ref_processor_stw()->verify_no_references_recorded();
1083 ref_processor_cm()->verify_no_references_recorded();
1084 }
1085
1086 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1087 // Post collection logging.
1088 // We should do this after we potentially resize the heap so
1089 // that all the COMMIT / UNCOMMIT events are generated before
1090 // the compaction events.
1091 print_hrm_post_compaction();
1092 heap_transition->print();
1093 print_heap_after_gc();
1094 print_heap_regions();
1095 #ifdef TRACESPINNING
1096 ParallelTaskTerminator::print_termination_counts();
1097 #endif
1098 }
1099
1100 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1101 bool clear_all_soft_refs) {
1102 assert_at_safepoint_on_vm_thread();
1103
1104 if (GCLocker::check_active_before_gc()) {
1105 // Full GC was not completed.
1106 return false;
1107 }
1108
1109 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1110 soft_ref_policy()->should_clear_all_soft_refs();
1111
1112 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1113 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1114
1115 collector.prepare_collection();
1116 collector.collect();
1117 collector.complete_collection();
1118
1119 // Full collection was successfully completed.
1120 return true;
1121 }
1122
1123 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1124 // Currently, there is no facility in the do_full_collection(bool) API to notify
1125 // the caller that the collection did not succeed (e.g., because it was locked
1126 // out by the GC locker). So, right now, we'll ignore the return value.
1127 bool dummy = do_full_collection(true, /* explicit_gc */
1128 clear_all_soft_refs);
1129 }
1130
1131 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1132 // Capacity, free and used after the GC counted as full regions to
1133 // include the waste in the following calculations.
1134 const size_t capacity_after_gc = capacity();
1135 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1136
1137 // This is enforced in arguments.cpp.
1138 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1139 "otherwise the code below doesn't make sense");
1140
1141 // We don't have floating point command-line arguments
1142 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1143 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1144 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1145 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1146
1147 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1148 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1149
1150 // We have to be careful here as these two calculations can overflow
1151 // 32-bit size_t's.
1152 double used_after_gc_d = (double) used_after_gc;
1153 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1154 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1155
1156 // Let's make sure that they are both under the max heap size, which
1157 // by default will make them fit into a size_t.
1158 double desired_capacity_upper_bound = (double) max_heap_size;
1159 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1160 desired_capacity_upper_bound);
1161 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1162 desired_capacity_upper_bound);
1163
1164 // We can now safely turn them into size_t's.
1165 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1166 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1167
1168 // This assert only makes sense here, before we adjust them
1169 // with respect to the min and max heap size.
1170 assert(minimum_desired_capacity <= maximum_desired_capacity,
1171 "minimum_desired_capacity = " SIZE_FORMAT ", "
1172 "maximum_desired_capacity = " SIZE_FORMAT,
1173 minimum_desired_capacity, maximum_desired_capacity);
1174
1175 // Should not be greater than the heap max size. No need to adjust
1176 // it with respect to the heap min size as it's a lower bound (i.e.,
1177 // we'll try to make the capacity larger than it, not smaller).
1178 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1179 // Should not be less than the heap min size. No need to adjust it
1180 // with respect to the heap max size as it's an upper bound (i.e.,
1181 // we'll try to make the capacity smaller than it, not greater).
1182 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1183
1184 if (capacity_after_gc < minimum_desired_capacity) {
1185 // Don't expand unless it's significant
1186 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1187
1188 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1189 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1190 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1191 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1192
1193 expand(expand_bytes, _workers);
1194
1195 // No expansion, now see if we want to shrink
1196 } else if (capacity_after_gc > maximum_desired_capacity) {
1197 // Capacity too large, compute shrinking size
1198 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1199
1200 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1201 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1202 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1203 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1204
1205 shrink(shrink_bytes);
1206 }
1207 }
1208
1209 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1210 bool do_gc,
1211 bool clear_all_soft_refs,
1212 bool expect_null_mutator_alloc_region,
1213 bool* gc_succeeded) {
1214 *gc_succeeded = true;
1215 // Let's attempt the allocation first.
1216 HeapWord* result =
1217 attempt_allocation_at_safepoint(word_size,
1218 expect_null_mutator_alloc_region);
1219 if (result != NULL) {
1220 return result;
1221 }
1222
1223 // In a G1 heap, we're supposed to keep allocation from failing by
1224 // incremental pauses. Therefore, at least for now, we'll favor
1225 // expansion over collection. (This might change in the future if we can
1226 // do something smarter than full collection to satisfy a failed alloc.)
1227 result = expand_and_allocate(word_size);
1228 if (result != NULL) {
1229 return result;
1230 }
1231
1232 if (do_gc) {
1233 // Expansion didn't work, we'll try to do a Full GC.
1234 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1235 clear_all_soft_refs);
1236 }
1237
1238 return NULL;
1239 }
1240
1241 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1242 bool* succeeded) {
1243 assert_at_safepoint_on_vm_thread();
1244
1245 // Attempts to allocate followed by Full GC.
1246 HeapWord* result =
1247 satisfy_failed_allocation_helper(word_size,
1248 true, /* do_gc */
1249 false, /* clear_all_soft_refs */
1250 false, /* expect_null_mutator_alloc_region */
1251 succeeded);
1252
1253 if (result != NULL || !*succeeded) {
1254 return result;
1255 }
1256
1257 // Attempts to allocate followed by Full GC that will collect all soft references.
1258 result = satisfy_failed_allocation_helper(word_size,
1259 true, /* do_gc */
1260 true, /* clear_all_soft_refs */
1261 true, /* expect_null_mutator_alloc_region */
1262 succeeded);
1263
1264 if (result != NULL || !*succeeded) {
1265 return result;
1266 }
1267
1268 // Attempts to allocate, no GC
1269 result = satisfy_failed_allocation_helper(word_size,
1270 false, /* do_gc */
1271 false, /* clear_all_soft_refs */
1272 true, /* expect_null_mutator_alloc_region */
1273 succeeded);
1274
1275 if (result != NULL) {
1276 return result;
1277 }
1278
1279 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1280 "Flag should have been handled and cleared prior to this point");
1281
1282 // What else? We might try synchronous finalization later. If the total
1283 // space available is large enough for the allocation, then a more
1284 // complete compaction phase than we've tried so far might be
1285 // appropriate.
1286 return NULL;
1287 }
1288
1289 // Attempting to expand the heap sufficiently
1290 // to support an allocation of the given "word_size". If
1291 // successful, perform the allocation and return the address of the
1292 // allocated block, or else "NULL".
1293
1294 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1295 assert_at_safepoint_on_vm_thread();
1296
1297 _verifier->verify_region_sets_optional();
1298
1299 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1300 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1301 word_size * HeapWordSize);
1302
1303
1304 if (expand(expand_bytes, _workers)) {
1305 _hrm.verify_optional();
1306 _verifier->verify_region_sets_optional();
1307 return attempt_allocation_at_safepoint(word_size,
1308 false /* expect_null_mutator_alloc_region */);
1309 }
1310 return NULL;
1311 }
1312
1313 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1314 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1315 aligned_expand_bytes = align_up(aligned_expand_bytes,
1316 HeapRegion::GrainBytes);
1317
1318 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1319 expand_bytes, aligned_expand_bytes);
1320
1321 if (is_maximal_no_gc()) {
1322 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1323 return false;
1324 }
1325
1326 double expand_heap_start_time_sec = os::elapsedTime();
1327 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1328 assert(regions_to_expand > 0, "Must expand by at least one region");
1329
1330 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1331 if (expand_time_ms != NULL) {
1332 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1333 }
1334
1335 if (expanded_by > 0) {
1336 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1337 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1338 g1_policy()->record_new_heap_size(num_regions());
1339 } else {
1340 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1341
1342 // The expansion of the virtual storage space was unsuccessful.
1343 // Let's see if it was because we ran out of swap.
1344 if (G1ExitOnExpansionFailure &&
1345 _hrm.available() >= regions_to_expand) {
1346 // We had head room...
1347 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1348 }
1349 }
1350 return regions_to_expand > 0;
1351 }
1352
1353 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1354 size_t aligned_shrink_bytes =
1355 ReservedSpace::page_align_size_down(shrink_bytes);
1356 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1357 HeapRegion::GrainBytes);
1358 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1359
1360 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1361 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1362
1363
1364 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",
1365 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1366 if (num_regions_removed > 0) {
1367 g1_policy()->record_new_heap_size(num_regions());
1368 } else {
1369 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1370 }
1371 }
1372
1373 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1374 _verifier->verify_region_sets_optional();
1375
1376 // We should only reach here at the end of a Full GC which means we
1377 // should not not be holding to any GC alloc regions. The method
1378 // below will make sure of that and do any remaining clean up.
1379 _allocator->abandon_gc_alloc_regions();
1380
1381 // Instead of tearing down / rebuilding the free lists here, we
1382 // could instead use the remove_all_pending() method on free_list to
1383 // remove only the ones that we need to remove.
1384 tear_down_region_sets(true /* free_list_only */);
1385 shrink_helper(shrink_bytes);
1386 rebuild_region_sets(true /* free_list_only */);
1387
1388 _hrm.verify_optional();
1389 _verifier->verify_region_sets_optional();
1390 }
1391
1392 // Public methods.
1393
1394 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1395 CollectedHeap(),
1396 _young_gen_sampling_thread(NULL),
1397 _collector_policy(collector_policy),
1398 _soft_ref_policy(),
1399 _card_table(NULL),
1400 _memory_manager("G1 Young Generation", "end of minor GC"),
1401 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1402 _eden_pool(NULL),
1403 _survivor_pool(NULL),
1404 _old_pool(NULL),
1405 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1406 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1407 _g1_policy(new G1Policy(_gc_timer_stw)),
1408 _collection_set(this, _g1_policy),
1409 _dirty_card_queue_set(false),
1410 _is_alive_closure_cm(this),
1411 _is_alive_closure_stw(this),
1412 _ref_processor_cm(NULL),
1413 _ref_processor_stw(NULL),
1414 _bot(NULL),
1415 _hot_card_cache(NULL),
1416 _g1_rem_set(NULL),
1417 _cr(NULL),
1418 _g1mm(NULL),
1419 _preserved_marks_set(true /* in_c_heap */),
1420 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1421 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1422 _humongous_reclaim_candidates(),
1423 _has_humongous_reclaim_candidates(false),
1424 _archive_allocator(NULL),
1425 _summary_bytes_used(0),
1426 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1427 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1428 _expand_heap_after_alloc_failure(true),
1429 _old_marking_cycles_started(0),
1430 _old_marking_cycles_completed(0),
1431 _in_cset_fast_test() {
1432
1433 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1434 /* are_GC_task_threads */true,
1435 /* are_ConcurrentGC_threads */false);
1436 _workers->initialize_workers();
1437 _verifier = new G1HeapVerifier(this);
1438
1439 _allocator = new G1Allocator(this);
1440
1441 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1442
1443 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1444
1445 // Override the default _filler_array_max_size so that no humongous filler
1446 // objects are created.
1447 _filler_array_max_size = _humongous_object_threshold_in_words;
1448
1449 uint n_queues = ParallelGCThreads;
1450 _task_queues = new RefToScanQueueSet(n_queues);
1451
1452 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1453
1454 for (uint i = 0; i < n_queues; i++) {
1455 RefToScanQueue* q = new RefToScanQueue();
1456 q->initialize();
1457 _task_queues->register_queue(i, q);
1458 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1459 }
1460
1461 // Initialize the G1EvacuationFailureALot counters and flags.
1462 NOT_PRODUCT(reset_evacuation_should_fail();)
1463
1464 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1465 }
1466
1467 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1468 size_t size,
1469 size_t translation_factor) {
1470 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1471 // Allocate a new reserved space, preferring to use large pages.
1472 ReservedSpace rs(size, preferred_page_size);
1473 G1RegionToSpaceMapper* result =
1474 G1RegionToSpaceMapper::create_mapper(rs,
1475 size,
1476 rs.alignment(),
1477 HeapRegion::GrainBytes,
1478 translation_factor,
1479 mtGC);
1480
1481 os::trace_page_sizes_for_requested_size(description,
1482 size,
1483 preferred_page_size,
1484 rs.alignment(),
1485 rs.base(),
1486 rs.size());
1487
1488 return result;
1489 }
1490
1491 jint G1CollectedHeap::initialize_concurrent_refinement() {
1492 jint ecode = JNI_OK;
1493 _cr = G1ConcurrentRefine::create(&ecode);
1494 return ecode;
1495 }
1496
1497 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1498 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1499 if (_young_gen_sampling_thread->osthread() == NULL) {
1500 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1501 return JNI_ENOMEM;
1502 }
1503 return JNI_OK;
1504 }
1505
1506 jint G1CollectedHeap::initialize() {
1507 os::enable_vtime();
1508
1509 // Necessary to satisfy locking discipline assertions.
1510
1511 MutexLocker x(Heap_lock);
1512
1513 // While there are no constraints in the GC code that HeapWordSize
1514 // be any particular value, there are multiple other areas in the
1515 // system which believe this to be true (e.g. oop->object_size in some
1516 // cases incorrectly returns the size in wordSize units rather than
1517 // HeapWordSize).
1518 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1519
1520 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1521 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1522 size_t heap_alignment = collector_policy()->heap_alignment();
1523
1524 // Ensure that the sizes are properly aligned.
1525 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1526 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1527 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1528
1529 // Reserve the maximum.
1530
1531 // When compressed oops are enabled, the preferred heap base
1532 // is calculated by subtracting the requested size from the
1533 // 32Gb boundary and using the result as the base address for
1534 // heap reservation. If the requested size is not aligned to
1535 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1536 // into the ReservedHeapSpace constructor) then the actual
1537 // base of the reserved heap may end up differing from the
1538 // address that was requested (i.e. the preferred heap base).
1539 // If this happens then we could end up using a non-optimal
1540 // compressed oops mode.
1541
1542 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1543 heap_alignment);
1544
1545 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1546
1547 // Create the barrier set for the entire reserved region.
1548 G1CardTable* ct = new G1CardTable(reserved_region());
1549 ct->initialize();
1550 G1BarrierSet* bs = new G1BarrierSet(ct);
1551 bs->initialize();
1552 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1553 BarrierSet::set_barrier_set(bs);
1554 _card_table = ct;
1555
1556 // Create the hot card cache.
1557 _hot_card_cache = new G1HotCardCache(this);
1558
1559 // Carve out the G1 part of the heap.
1560 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1561 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1562 G1RegionToSpaceMapper* heap_storage =
1563 G1RegionToSpaceMapper::create_mapper(g1_rs,
1564 g1_rs.size(),
1565 page_size,
1566 HeapRegion::GrainBytes,
1567 1,
1568 mtJavaHeap);
1569 os::trace_page_sizes("Heap",
1570 collector_policy()->min_heap_byte_size(),
1571 max_byte_size,
1572 page_size,
1573 heap_rs.base(),
1574 heap_rs.size());
1575 heap_storage->set_mapping_changed_listener(&_listener);
1576
1577 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1578 G1RegionToSpaceMapper* bot_storage =
1579 create_aux_memory_mapper("Block Offset Table",
1580 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1581 G1BlockOffsetTable::heap_map_factor());
1582
1583 G1RegionToSpaceMapper* cardtable_storage =
1584 create_aux_memory_mapper("Card Table",
1585 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1586 G1CardTable::heap_map_factor());
1587
1588 G1RegionToSpaceMapper* card_counts_storage =
1589 create_aux_memory_mapper("Card Counts Table",
1590 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1591 G1CardCounts::heap_map_factor());
1592
1593 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1594 G1RegionToSpaceMapper* prev_bitmap_storage =
1595 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1596 G1RegionToSpaceMapper* next_bitmap_storage =
1597 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1598
1599 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1600 _card_table->initialize(cardtable_storage);
1601 // Do later initialization work for concurrent refinement.
1602 _hot_card_cache->initialize(card_counts_storage);
1603
1604 // 6843694 - ensure that the maximum region index can fit
1605 // in the remembered set structures.
1606 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1607 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1608
1609 // Also create a G1 rem set.
1610 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1611 _g1_rem_set->initialize(max_capacity(), max_regions());
1612
1613 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1614 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1615 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1616 "too many cards per region");
1617
1618 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1619
1620 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1621
1622 {
1623 HeapWord* start = _hrm.reserved().start();
1624 HeapWord* end = _hrm.reserved().end();
1625 size_t granularity = HeapRegion::GrainBytes;
1626
1627 _in_cset_fast_test.initialize(start, end, granularity);
1628 _humongous_reclaim_candidates.initialize(start, end, granularity);
1629 }
1630
1631 // Create the G1ConcurrentMark data structure and thread.
1632 // (Must do this late, so that "max_regions" is defined.)
1633 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1634 if (_cm == NULL || !_cm->completed_initialization()) {
1635 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1636 return JNI_ENOMEM;
1637 }
1638 _cm_thread = _cm->cm_thread();
1639
1640 // Now expand into the initial heap size.
1641 if (!expand(init_byte_size, _workers)) {
1642 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1643 return JNI_ENOMEM;
1644 }
1645
1646 // Perform any initialization actions delegated to the policy.
1647 g1_policy()->init(this, &_collection_set);
1648
1649 G1BarrierSet::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1650 SATB_Q_FL_lock,
1651 G1SATBProcessCompletedThreshold,
1652 Shared_SATB_Q_lock);
1653
1654 jint ecode = initialize_concurrent_refinement();
1655 if (ecode != JNI_OK) {
1656 return ecode;
1657 }
1658
1659 ecode = initialize_young_gen_sampling_thread();
1660 if (ecode != JNI_OK) {
1661 return ecode;
1662 }
1663
1664 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1665 DirtyCardQ_FL_lock,
1666 (int)concurrent_refine()->yellow_zone(),
1667 (int)concurrent_refine()->red_zone(),
1668 Shared_DirtyCardQ_lock,
1669 NULL, // fl_owner
1670 true); // init_free_ids
1671
1672 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1673 DirtyCardQ_FL_lock,
1674 -1, // never trigger processing
1675 -1, // no limit on length
1676 Shared_DirtyCardQ_lock,
1677 &G1BarrierSet::dirty_card_queue_set());
1678
1679 // Here we allocate the dummy HeapRegion that is required by the
1680 // G1AllocRegion class.
1681 HeapRegion* dummy_region = _hrm.get_dummy_region();
1682
1683 // We'll re-use the same region whether the alloc region will
1684 // require BOT updates or not and, if it doesn't, then a non-young
1685 // region will complain that it cannot support allocations without
1686 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1687 dummy_region->set_eden();
1688 // Make sure it's full.
1689 dummy_region->set_top(dummy_region->end());
1690 G1AllocRegion::setup(this, dummy_region);
1691
1692 _allocator->init_mutator_alloc_region();
1693
1694 // Do create of the monitoring and management support so that
1695 // values in the heap have been properly initialized.
1696 _g1mm = new G1MonitoringSupport(this);
1697
1698 G1StringDedup::initialize();
1699
1700 _preserved_marks_set.init(ParallelGCThreads);
1701
1702 _collection_set.initialize(max_regions());
1703
1704 return JNI_OK;
1705 }
1706
1707 void G1CollectedHeap::initialize_serviceability() {
1708 _eden_pool = new G1EdenPool(this);
1709 _survivor_pool = new G1SurvivorPool(this);
1710 _old_pool = new G1OldGenPool(this);
1711
1712 _full_gc_memory_manager.add_pool(_eden_pool);
1713 _full_gc_memory_manager.add_pool(_survivor_pool);
1714 _full_gc_memory_manager.add_pool(_old_pool);
1715
1716 _memory_manager.add_pool(_eden_pool);
1717 _memory_manager.add_pool(_survivor_pool);
1718
1719 }
1720
1721 void G1CollectedHeap::stop() {
1722 // Stop all concurrent threads. We do this to make sure these threads
1723 // do not continue to execute and access resources (e.g. logging)
1724 // that are destroyed during shutdown.
1725 _cr->stop();
1726 _young_gen_sampling_thread->stop();
1727 _cm_thread->stop();
1728 if (G1StringDedup::is_enabled()) {
1729 G1StringDedup::stop();
1730 }
1731 }
1732
1733 void G1CollectedHeap::safepoint_synchronize_begin() {
1734 SuspendibleThreadSet::synchronize();
1735 }
1736
1737 void G1CollectedHeap::safepoint_synchronize_end() {
1738 SuspendibleThreadSet::desynchronize();
1739 }
1740
1741 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1742 return HeapRegion::max_region_size();
1743 }
1744
1745 void G1CollectedHeap::post_initialize() {
1746 CollectedHeap::post_initialize();
1747 ref_processing_init();
1748 }
1749
1750 void G1CollectedHeap::ref_processing_init() {
1751 // Reference processing in G1 currently works as follows:
1752 //
1753 // * There are two reference processor instances. One is
1754 // used to record and process discovered references
1755 // during concurrent marking; the other is used to
1756 // record and process references during STW pauses
1757 // (both full and incremental).
1758 // * Both ref processors need to 'span' the entire heap as
1759 // the regions in the collection set may be dotted around.
1760 //
1761 // * For the concurrent marking ref processor:
1762 // * Reference discovery is enabled at initial marking.
1763 // * Reference discovery is disabled and the discovered
1764 // references processed etc during remarking.
1765 // * Reference discovery is MT (see below).
1766 // * Reference discovery requires a barrier (see below).
1767 // * Reference processing may or may not be MT
1768 // (depending on the value of ParallelRefProcEnabled
1769 // and ParallelGCThreads).
1770 // * A full GC disables reference discovery by the CM
1771 // ref processor and abandons any entries on it's
1772 // discovered lists.
1773 //
1774 // * For the STW processor:
1775 // * Non MT discovery is enabled at the start of a full GC.
1776 // * Processing and enqueueing during a full GC is non-MT.
1777 // * During a full GC, references are processed after marking.
1778 //
1779 // * Discovery (may or may not be MT) is enabled at the start
1780 // of an incremental evacuation pause.
1781 // * References are processed near the end of a STW evacuation pause.
1782 // * For both types of GC:
1783 // * Discovery is atomic - i.e. not concurrent.
1784 // * Reference discovery will not need a barrier.
1785
1786 MemRegion mr = reserved_region();
1787
1788 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1789
1790 // Concurrent Mark ref processor
1791 _ref_processor_cm =
1792 new ReferenceProcessor(mr, // span
1793 mt_processing,
1794 // mt processing
1795 ParallelGCThreads,
1796 // degree of mt processing
1797 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1798 // mt discovery
1799 MAX2(ParallelGCThreads, ConcGCThreads),
1800 // degree of mt discovery
1801 false,
1802 // Reference discovery is not atomic
1803 &_is_alive_closure_cm);
1804 // is alive closure
1805 // (for efficiency/performance)
1806
1807 // STW ref processor
1808 _ref_processor_stw =
1809 new ReferenceProcessor(mr, // span
1810 mt_processing,
1811 // mt processing
1812 ParallelGCThreads,
1813 // degree of mt processing
1814 (ParallelGCThreads > 1),
1815 // mt discovery
1816 ParallelGCThreads,
1817 // degree of mt discovery
1818 true,
1819 // Reference discovery is atomic
1820 &_is_alive_closure_stw);
1821 // is alive closure
1822 // (for efficiency/performance)
1823 }
1824
1825 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1826 return _collector_policy;
1827 }
1828
1829 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1830 return &_soft_ref_policy;
1831 }
1832
1833 size_t G1CollectedHeap::capacity() const {
1834 return _hrm.length() * HeapRegion::GrainBytes;
1835 }
1836
1837 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1838 return _hrm.total_free_bytes();
1839 }
1840
1841 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1842 _hot_card_cache->drain(cl, worker_i);
1843 }
1844
1845 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1846 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1847 size_t n_completed_buffers = 0;
1848 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1849 n_completed_buffers++;
1850 }
1851 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1852 dcqs.clear_n_completed_buffers();
1853 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1854 }
1855
1856 // Computes the sum of the storage used by the various regions.
1857 size_t G1CollectedHeap::used() const {
1858 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1859 if (_archive_allocator != NULL) {
1860 result += _archive_allocator->used();
1861 }
1862 return result;
1863 }
1864
1865 size_t G1CollectedHeap::used_unlocked() const {
1866 return _summary_bytes_used;
1867 }
1868
1869 class SumUsedClosure: public HeapRegionClosure {
1870 size_t _used;
1871 public:
1872 SumUsedClosure() : _used(0) {}
1873 bool do_heap_region(HeapRegion* r) {
1874 _used += r->used();
1875 return false;
1876 }
1877 size_t result() { return _used; }
1878 };
1879
1880 size_t G1CollectedHeap::recalculate_used() const {
1881 double recalculate_used_start = os::elapsedTime();
1882
1883 SumUsedClosure blk;
1884 heap_region_iterate(&blk);
1885
1886 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1887 return blk.result();
1888 }
1889
1890 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1891 switch (cause) {
1892 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1893 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1894 case GCCause::_wb_conc_mark: return true;
1895 default : return false;
1896 }
1897 }
1898
1899 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1900 switch (cause) {
1901 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1902 case GCCause::_g1_humongous_allocation: return true;
1903 default: return is_user_requested_concurrent_full_gc(cause);
1904 }
1905 }
1906
1907 #ifndef PRODUCT
1908 void G1CollectedHeap::allocate_dummy_regions() {
1909 // Let's fill up most of the region
1910 size_t word_size = HeapRegion::GrainWords - 1024;
1911 // And as a result the region we'll allocate will be humongous.
1912 guarantee(is_humongous(word_size), "sanity");
1913
1914 // _filler_array_max_size is set to humongous object threshold
1915 // but temporarily change it to use CollectedHeap::fill_with_object().
1916 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1917
1918 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1919 // Let's use the existing mechanism for the allocation
1920 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1921 if (dummy_obj != NULL) {
1922 MemRegion mr(dummy_obj, word_size);
1923 CollectedHeap::fill_with_object(mr);
1924 } else {
1925 // If we can't allocate once, we probably cannot allocate
1926 // again. Let's get out of the loop.
1927 break;
1928 }
1929 }
1930 }
1931 #endif // !PRODUCT
1932
1933 void G1CollectedHeap::increment_old_marking_cycles_started() {
1934 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1935 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1936 "Wrong marking cycle count (started: %d, completed: %d)",
1937 _old_marking_cycles_started, _old_marking_cycles_completed);
1938
1939 _old_marking_cycles_started++;
1940 }
1941
1942 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
1943 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1944
1945 // We assume that if concurrent == true, then the caller is a
1946 // concurrent thread that was joined the Suspendible Thread
1947 // Set. If there's ever a cheap way to check this, we should add an
1948 // assert here.
1949
1950 // Given that this method is called at the end of a Full GC or of a
1951 // concurrent cycle, and those can be nested (i.e., a Full GC can
1952 // interrupt a concurrent cycle), the number of full collections
1953 // completed should be either one (in the case where there was no
1954 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1955 // behind the number of full collections started.
1956
1957 // This is the case for the inner caller, i.e. a Full GC.
1958 assert(concurrent ||
1959 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1960 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1961 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1962 "is inconsistent with _old_marking_cycles_completed = %u",
1963 _old_marking_cycles_started, _old_marking_cycles_completed);
1964
1965 // This is the case for the outer caller, i.e. the concurrent cycle.
1966 assert(!concurrent ||
1967 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1968 "for outer caller (concurrent cycle): "
1969 "_old_marking_cycles_started = %u "
1970 "is inconsistent with _old_marking_cycles_completed = %u",
1971 _old_marking_cycles_started, _old_marking_cycles_completed);
1972
1973 _old_marking_cycles_completed += 1;
1974
1975 // We need to clear the "in_progress" flag in the CM thread before
1976 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1977 // is set) so that if a waiter requests another System.gc() it doesn't
1978 // incorrectly see that a marking cycle is still in progress.
1979 if (concurrent) {
1980 _cm_thread->set_idle();
1981 }
1982
1983 // This notify_all() will ensure that a thread that called
1984 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
1985 // and it's waiting for a full GC to finish will be woken up. It is
1986 // waiting in VM_G1CollectForAllocation::doit_epilogue().
1987 FullGCCount_lock->notify_all();
1988 }
1989
1990 void G1CollectedHeap::collect(GCCause::Cause cause) {
1991 assert_heap_not_locked();
1992
1993 uint gc_count_before;
1994 uint old_marking_count_before;
1995 uint full_gc_count_before;
1996 bool retry_gc;
1997
1998 do {
1999 retry_gc = false;
2000
2001 {
2002 MutexLocker ml(Heap_lock);
2003
2004 // Read the GC count while holding the Heap_lock
2005 gc_count_before = total_collections();
2006 full_gc_count_before = total_full_collections();
2007 old_marking_count_before = _old_marking_cycles_started;
2008 }
2009
2010 if (should_do_concurrent_full_gc(cause)) {
2011 // Schedule an initial-mark evacuation pause that will start a
2012 // concurrent cycle. We're setting word_size to 0 which means that
2013 // we are not requesting a post-GC allocation.
2014 VM_G1CollectForAllocation op(0, /* word_size */
2015 gc_count_before,
2016 cause,
2017 true, /* should_initiate_conc_mark */
2018 g1_policy()->max_pause_time_ms());
2019 VMThread::execute(&op);
2020 if (!op.pause_succeeded()) {
2021 if (old_marking_count_before == _old_marking_cycles_started) {
2022 retry_gc = op.should_retry_gc();
2023 } else {
2024 // A Full GC happened while we were trying to schedule the
2025 // initial-mark GC. No point in starting a new cycle given
2026 // that the whole heap was collected anyway.
2027 }
2028
2029 if (retry_gc) {
2030 if (GCLocker::is_active_and_needs_gc()) {
2031 GCLocker::stall_until_clear();
2032 }
2033 }
2034 }
2035 } else {
2036 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2037 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2038
2039 // Schedule a standard evacuation pause. We're setting word_size
2040 // to 0 which means that we are not requesting a post-GC allocation.
2041 VM_G1CollectForAllocation op(0, /* word_size */
2042 gc_count_before,
2043 cause,
2044 false, /* should_initiate_conc_mark */
2045 g1_policy()->max_pause_time_ms());
2046 VMThread::execute(&op);
2047 } else {
2048 // Schedule a Full GC.
2049 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2050 VMThread::execute(&op);
2051 }
2052 }
2053 } while (retry_gc);
2054 }
2055
2056 bool G1CollectedHeap::is_in(const void* p) const {
2057 if (_hrm.reserved().contains(p)) {
2058 // Given that we know that p is in the reserved space,
2059 // heap_region_containing() should successfully
2060 // return the containing region.
2061 HeapRegion* hr = heap_region_containing(p);
2062 return hr->is_in(p);
2063 } else {
2064 return false;
2065 }
2066 }
2067
2068 #ifdef ASSERT
2069 bool G1CollectedHeap::is_in_exact(const void* p) const {
2070 bool contains = reserved_region().contains(p);
2071 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2072 if (contains && available) {
2073 return true;
2074 } else {
2075 return false;
2076 }
2077 }
2078 #endif
2079
2080 // Iteration functions.
2081
2082 // Iterates an ObjectClosure over all objects within a HeapRegion.
2083
2084 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2085 ObjectClosure* _cl;
2086 public:
2087 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2088 bool do_heap_region(HeapRegion* r) {
2089 if (!r->is_continues_humongous()) {
2090 r->object_iterate(_cl);
2091 }
2092 return false;
2093 }
2094 };
2095
2096 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2097 IterateObjectClosureRegionClosure blk(cl);
2098 heap_region_iterate(&blk);
2099 }
2100
2101 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2102 _hrm.iterate(cl);
2103 }
2104
2105 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2106 HeapRegionClaimer *hrclaimer,
2107 uint worker_id) const {
2108 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2109 }
2110
2111 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2112 HeapRegionClaimer *hrclaimer) const {
2113 _hrm.par_iterate(cl, hrclaimer, 0);
2114 }
2115
2116 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2117 _collection_set.iterate(cl);
2118 }
2119
2120 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2121 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2122 }
2123
2124 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2125 HeapRegion* hr = heap_region_containing(addr);
2126 return hr->block_start(addr);
2127 }
2128
2129 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2130 HeapRegion* hr = heap_region_containing(addr);
2131 return hr->block_size(addr);
2132 }
2133
2134 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2135 HeapRegion* hr = heap_region_containing(addr);
2136 return hr->block_is_obj(addr);
2137 }
2138
2139 bool G1CollectedHeap::supports_tlab_allocation() const {
2140 return true;
2141 }
2142
2143 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2144 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2145 }
2146
2147 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2148 return _eden.length() * HeapRegion::GrainBytes;
2149 }
2150
2151 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2152 // must be equal to the humongous object limit.
2153 size_t G1CollectedHeap::max_tlab_size() const {
2154 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2155 }
2156
2157 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2158 return _allocator->unsafe_max_tlab_alloc();
2159 }
2160
2161 size_t G1CollectedHeap::max_capacity() const {
2162 return _hrm.reserved().byte_size();
2163 }
2164
2165 jlong G1CollectedHeap::millis_since_last_gc() {
2166 // See the notes in GenCollectedHeap::millis_since_last_gc()
2167 // for more information about the implementation.
2168 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2169 _g1_policy->collection_pause_end_millis();
2170 if (ret_val < 0) {
2171 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2172 ". returning zero instead.", ret_val);
2173 return 0;
2174 }
2175 return ret_val;
2176 }
2177
2178 void G1CollectedHeap::prepare_for_verify() {
2179 _verifier->prepare_for_verify();
2180 }
2181
2182 void G1CollectedHeap::verify(VerifyOption vo) {
2183 _verifier->verify(vo);
2184 }
2185
2186 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2187 return true;
2188 }
2189
2190 const char* const* G1CollectedHeap::concurrent_phases() const {
2191 return _cm_thread->concurrent_phases();
2192 }
2193
2194 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2195 return _cm_thread->request_concurrent_phase(phase);
2196 }
2197
2198 class PrintRegionClosure: public HeapRegionClosure {
2199 outputStream* _st;
2200 public:
2201 PrintRegionClosure(outputStream* st) : _st(st) {}
2202 bool do_heap_region(HeapRegion* r) {
2203 r->print_on(_st);
2204 return false;
2205 }
2206 };
2207
2208 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2209 const HeapRegion* hr,
2210 const VerifyOption vo) const {
2211 switch (vo) {
2212 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2213 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2214 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2215 default: ShouldNotReachHere();
2216 }
2217 return false; // keep some compilers happy
2218 }
2219
2220 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2221 const VerifyOption vo) const {
2222 switch (vo) {
2223 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2224 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2225 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2226 default: ShouldNotReachHere();
2227 }
2228 return false; // keep some compilers happy
2229 }
2230
2231 void G1CollectedHeap::print_heap_regions() const {
2232 LogTarget(Trace, gc, heap, region) lt;
2233 if (lt.is_enabled()) {
2234 LogStream ls(lt);
2235 print_regions_on(&ls);
2236 }
2237 }
2238
2239 void G1CollectedHeap::print_on(outputStream* st) const {
2240 st->print(" %-20s", "garbage-first heap");
2241 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2242 capacity()/K, used_unlocked()/K);
2243 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2244 p2i(_hrm.reserved().start()),
2245 p2i(_hrm.reserved().end()));
2246 st->cr();
2247 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2248 uint young_regions = young_regions_count();
2249 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2250 (size_t) young_regions * HeapRegion::GrainBytes / K);
2251 uint survivor_regions = survivor_regions_count();
2252 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2253 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2254 st->cr();
2255 MetaspaceUtils::print_on(st);
2256 }
2257
2258 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2259 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2260 "HS=humongous(starts), HC=humongous(continues), "
2261 "CS=collection set, F=free, A=archive, "
2262 "TAMS=top-at-mark-start (previous, next)");
2263 PrintRegionClosure blk(st);
2264 heap_region_iterate(&blk);
2265 }
2266
2267 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2268 print_on(st);
2269
2270 // Print the per-region information.
2271 print_regions_on(st);
2272 }
2273
2274 void G1CollectedHeap::print_on_error(outputStream* st) const {
2275 this->CollectedHeap::print_on_error(st);
2276
2277 if (_cm != NULL) {
2278 st->cr();
2279 _cm->print_on_error(st);
2280 }
2281 }
2282
2283 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2284 workers()->print_worker_threads_on(st);
2285 _cm_thread->print_on(st);
2286 st->cr();
2287 _cm->print_worker_threads_on(st);
2288 _cr->print_threads_on(st);
2289 _young_gen_sampling_thread->print_on(st);
2290 if (G1StringDedup::is_enabled()) {
2291 G1StringDedup::print_worker_threads_on(st);
2292 }
2293 }
2294
2295 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2296 workers()->threads_do(tc);
2297 tc->do_thread(_cm_thread);
2298 _cm->threads_do(tc);
2299 _cr->threads_do(tc);
2300 tc->do_thread(_young_gen_sampling_thread);
2301 if (G1StringDedup::is_enabled()) {
2302 G1StringDedup::threads_do(tc);
2303 }
2304 }
2305
2306 void G1CollectedHeap::print_tracing_info() const {
2307 g1_rem_set()->print_summary_info();
2308 concurrent_mark()->print_summary_info();
2309 }
2310
2311 #ifndef PRODUCT
2312 // Helpful for debugging RSet issues.
2313
2314 class PrintRSetsClosure : public HeapRegionClosure {
2315 private:
2316 const char* _msg;
2317 size_t _occupied_sum;
2318
2319 public:
2320 bool do_heap_region(HeapRegion* r) {
2321 HeapRegionRemSet* hrrs = r->rem_set();
2322 size_t occupied = hrrs->occupied();
2323 _occupied_sum += occupied;
2324
2325 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2326 if (occupied == 0) {
2327 tty->print_cr(" RSet is empty");
2328 } else {
2329 hrrs->print();
2330 }
2331 tty->print_cr("----------");
2332 return false;
2333 }
2334
2335 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2336 tty->cr();
2337 tty->print_cr("========================================");
2338 tty->print_cr("%s", msg);
2339 tty->cr();
2340 }
2341
2342 ~PrintRSetsClosure() {
2343 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2344 tty->print_cr("========================================");
2345 tty->cr();
2346 }
2347 };
2348
2349 void G1CollectedHeap::print_cset_rsets() {
2350 PrintRSetsClosure cl("Printing CSet RSets");
2351 collection_set_iterate(&cl);
2352 }
2353
2354 void G1CollectedHeap::print_all_rsets() {
2355 PrintRSetsClosure cl("Printing All RSets");;
2356 heap_region_iterate(&cl);
2357 }
2358 #endif // PRODUCT
2359
2360 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2361
2362 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2363 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2364 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2365
2366 size_t eden_capacity_bytes =
2367 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2368
2369 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2370 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2371 eden_capacity_bytes, survivor_used_bytes, num_regions());
2372 }
2373
2374 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2375 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2376 stats->unused(), stats->used(), stats->region_end_waste(),
2377 stats->regions_filled(), stats->direct_allocated(),
2378 stats->failure_used(), stats->failure_waste());
2379 }
2380
2381 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2382 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2383 gc_tracer->report_gc_heap_summary(when, heap_summary);
2384
2385 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2386 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2387 }
2388
2389 G1CollectedHeap* G1CollectedHeap::heap() {
2390 CollectedHeap* heap = Universe::heap();
2391 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2392 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2393 return (G1CollectedHeap*)heap;
2394 }
2395
2396 void G1CollectedHeap::gc_prologue(bool full) {
2397 // always_do_update_barrier = false;
2398 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2399
2400 // This summary needs to be printed before incrementing total collections.
2401 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2402
2403 // Update common counters.
2404 increment_total_collections(full /* full gc */);
2405 if (full) {
2406 increment_old_marking_cycles_started();
2407 }
2408
2409 // Fill TLAB's and such
2410 double start = os::elapsedTime();
2411 accumulate_statistics_all_tlabs();
2412 ensure_parsability(true);
2413 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2414 }
2415
2416 void G1CollectedHeap::gc_epilogue(bool full) {
2417 // Update common counters.
2418 if (full) {
2419 // Update the number of full collections that have been completed.
2420 increment_old_marking_cycles_completed(false /* concurrent */);
2421 }
2422
2423 // We are at the end of the GC. Total collections has already been increased.
2424 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2425
2426 // FIXME: what is this about?
2427 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2428 // is set.
2429 #if COMPILER2_OR_JVMCI
2430 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2431 #endif
2432 // always_do_update_barrier = true;
2433
2434 double start = os::elapsedTime();
2435 resize_all_tlabs();
2436 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2437
2438 MemoryService::track_memory_usage();
2439 // We have just completed a GC. Update the soft reference
2440 // policy with the new heap occupancy
2441 Universe::update_heap_info_at_gc();
2442 }
2443
2444 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2445 uint gc_count_before,
2446 bool* succeeded,
2447 GCCause::Cause gc_cause) {
2448 assert_heap_not_locked_and_not_at_safepoint();
2449 VM_G1CollectForAllocation op(word_size,
2450 gc_count_before,
2451 gc_cause,
2452 false, /* should_initiate_conc_mark */
2453 g1_policy()->max_pause_time_ms());
2454 VMThread::execute(&op);
2455
2456 HeapWord* result = op.result();
2457 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2458 assert(result == NULL || ret_succeeded,
2459 "the result should be NULL if the VM did not succeed");
2460 *succeeded = ret_succeeded;
2461
2462 assert_heap_not_locked();
2463 return result;
2464 }
2465
2466 void G1CollectedHeap::do_concurrent_mark() {
2467 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2468 if (!_cm_thread->in_progress()) {
2469 _cm_thread->set_started();
2470 CGC_lock->notify();
2471 }
2472 }
2473
2474 size_t G1CollectedHeap::pending_card_num() {
2475 size_t extra_cards = 0;
2476 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2477 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2478 extra_cards += dcq.size();
2479 }
2480 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2481 size_t buffer_size = dcqs.buffer_size();
2482 size_t buffer_num = dcqs.completed_buffers_num();
2483
2484 return buffer_size * buffer_num + extra_cards;
2485 }
2486
2487 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2488 // We don't nominate objects with many remembered set entries, on
2489 // the assumption that such objects are likely still live.
2490 HeapRegionRemSet* rem_set = r->rem_set();
2491
2492 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2493 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2494 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2495 }
2496
2497 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2498 private:
2499 size_t _total_humongous;
2500 size_t _candidate_humongous;
2501
2502 DirtyCardQueue _dcq;
2503
2504 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2505 assert(region->is_starts_humongous(), "Must start a humongous object");
2506
2507 oop obj = oop(region->bottom());
2508
2509 // Dead objects cannot be eager reclaim candidates. Due to class
2510 // unloading it is unsafe to query their classes so we return early.
2511 if (g1h->is_obj_dead(obj, region)) {
2512 return false;
2513 }
2514
2515 // If we do not have a complete remembered set for the region, then we can
2516 // not be sure that we have all references to it.
2517 if (!region->rem_set()->is_complete()) {
2518 return false;
2519 }
2520 // Candidate selection must satisfy the following constraints
2521 // while concurrent marking is in progress:
2522 //
2523 // * In order to maintain SATB invariants, an object must not be
2524 // reclaimed if it was allocated before the start of marking and
2525 // has not had its references scanned. Such an object must have
2526 // its references (including type metadata) scanned to ensure no
2527 // live objects are missed by the marking process. Objects
2528 // allocated after the start of concurrent marking don't need to
2529 // be scanned.
2530 //
2531 // * An object must not be reclaimed if it is on the concurrent
2532 // mark stack. Objects allocated after the start of concurrent
2533 // marking are never pushed on the mark stack.
2534 //
2535 // Nominating only objects allocated after the start of concurrent
2536 // marking is sufficient to meet both constraints. This may miss
2537 // some objects that satisfy the constraints, but the marking data
2538 // structures don't support efficiently performing the needed
2539 // additional tests or scrubbing of the mark stack.
2540 //
2541 // However, we presently only nominate is_typeArray() objects.
2542 // A humongous object containing references induces remembered
2543 // set entries on other regions. In order to reclaim such an
2544 // object, those remembered sets would need to be cleaned up.
2545 //
2546 // We also treat is_typeArray() objects specially, allowing them
2547 // to be reclaimed even if allocated before the start of
2548 // concurrent mark. For this we rely on mark stack insertion to
2549 // exclude is_typeArray() objects, preventing reclaiming an object
2550 // that is in the mark stack. We also rely on the metadata for
2551 // such objects to be built-in and so ensured to be kept live.
2552 // Frequent allocation and drop of large binary blobs is an
2553 // important use case for eager reclaim, and this special handling
2554 // may reduce needed headroom.
2555
2556 return obj->is_typeArray() &&
2557 g1h->is_potential_eager_reclaim_candidate(region);
2558 }
2559
2560 public:
2561 RegisterHumongousWithInCSetFastTestClosure()
2562 : _total_humongous(0),
2563 _candidate_humongous(0),
2564 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2565 }
2566
2567 virtual bool do_heap_region(HeapRegion* r) {
2568 if (!r->is_starts_humongous()) {
2569 return false;
2570 }
2571 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2572
2573 bool is_candidate = humongous_region_is_candidate(g1h, r);
2574 uint rindex = r->hrm_index();
2575 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2576 if (is_candidate) {
2577 _candidate_humongous++;
2578 g1h->register_humongous_region_with_cset(rindex);
2579 // Is_candidate already filters out humongous object with large remembered sets.
2580 // If we have a humongous object with a few remembered sets, we simply flush these
2581 // remembered set entries into the DCQS. That will result in automatic
2582 // re-evaluation of their remembered set entries during the following evacuation
2583 // phase.
2584 if (!r->rem_set()->is_empty()) {
2585 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2586 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2587 G1CardTable* ct = g1h->card_table();
2588 HeapRegionRemSetIterator hrrs(r->rem_set());
2589 size_t card_index;
2590 while (hrrs.has_next(card_index)) {
2591 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2592 // The remembered set might contain references to already freed
2593 // regions. Filter out such entries to avoid failing card table
2594 // verification.
2595 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2596 if (*card_ptr != G1CardTable::dirty_card_val()) {
2597 *card_ptr = G1CardTable::dirty_card_val();
2598 _dcq.enqueue(card_ptr);
2599 }
2600 }
2601 }
2602 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2603 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2604 hrrs.n_yielded(), r->rem_set()->occupied());
2605 // We should only clear the card based remembered set here as we will not
2606 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2607 // (and probably never) we do not enter this path if there are other kind of
2608 // remembered sets for this region.
2609 r->rem_set()->clear_locked(true /* only_cardset */);
2610 // Clear_locked() above sets the state to Empty. However we want to continue
2611 // collecting remembered set entries for humongous regions that were not
2612 // reclaimed.
2613 r->rem_set()->set_state_complete();
2614 }
2615 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2616 }
2617 _total_humongous++;
2618
2619 return false;
2620 }
2621
2622 size_t total_humongous() const { return _total_humongous; }
2623 size_t candidate_humongous() const { return _candidate_humongous; }
2624
2625 void flush_rem_set_entries() { _dcq.flush(); }
2626 };
2627
2628 void G1CollectedHeap::register_humongous_regions_with_cset() {
2629 if (!G1EagerReclaimHumongousObjects) {
2630 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2631 return;
2632 }
2633 double time = os::elapsed_counter();
2634
2635 // Collect reclaim candidate information and register candidates with cset.
2636 RegisterHumongousWithInCSetFastTestClosure cl;
2637 heap_region_iterate(&cl);
2638
2639 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2640 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2641 cl.total_humongous(),
2642 cl.candidate_humongous());
2643 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2644
2645 // Finally flush all remembered set entries to re-check into the global DCQS.
2646 cl.flush_rem_set_entries();
2647 }
2648
2649 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2650 public:
2651 bool do_heap_region(HeapRegion* hr) {
2652 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2653 hr->verify_rem_set();
2654 }
2655 return false;
2656 }
2657 };
2658
2659 uint G1CollectedHeap::num_task_queues() const {
2660 return _task_queues->size();
2661 }
2662
2663 #if TASKQUEUE_STATS
2664 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2665 st->print_raw_cr("GC Task Stats");
2666 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2667 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2668 }
2669
2670 void G1CollectedHeap::print_taskqueue_stats() const {
2671 if (!log_is_enabled(Trace, gc, task, stats)) {
2672 return;
2673 }
2674 Log(gc, task, stats) log;
2675 ResourceMark rm;
2676 LogStream ls(log.trace());
2677 outputStream* st = &ls;
2678
2679 print_taskqueue_stats_hdr(st);
2680
2681 TaskQueueStats totals;
2682 const uint n = num_task_queues();
2683 for (uint i = 0; i < n; ++i) {
2684 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2685 totals += task_queue(i)->stats;
2686 }
2687 st->print_raw("tot "); totals.print(st); st->cr();
2688
2689 DEBUG_ONLY(totals.verify());
2690 }
2691
2692 void G1CollectedHeap::reset_taskqueue_stats() {
2693 const uint n = num_task_queues();
2694 for (uint i = 0; i < n; ++i) {
2695 task_queue(i)->stats.reset();
2696 }
2697 }
2698 #endif // TASKQUEUE_STATS
2699
2700 void G1CollectedHeap::wait_for_root_region_scanning() {
2701 double scan_wait_start = os::elapsedTime();
2702 // We have to wait until the CM threads finish scanning the
2703 // root regions as it's the only way to ensure that all the
2704 // objects on them have been correctly scanned before we start
2705 // moving them during the GC.
2706 bool waited = _cm->root_regions()->wait_until_scan_finished();
2707 double wait_time_ms = 0.0;
2708 if (waited) {
2709 double scan_wait_end = os::elapsedTime();
2710 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2711 }
2712 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2713 }
2714
2715 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2716 private:
2717 G1HRPrinter* _hr_printer;
2718 public:
2719 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2720
2721 virtual bool do_heap_region(HeapRegion* r) {
2722 _hr_printer->cset(r);
2723 return false;
2724 }
2725 };
2726
2727 void G1CollectedHeap::start_new_collection_set() {
2728 collection_set()->start_incremental_building();
2729
2730 clear_cset_fast_test();
2731
2732 guarantee(_eden.length() == 0, "eden should have been cleared");
2733 g1_policy()->transfer_survivors_to_cset(survivor());
2734 }
2735
2736 bool
2737 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2738 assert_at_safepoint_on_vm_thread();
2739 guarantee(!is_gc_active(), "collection is not reentrant");
2740
2741 if (GCLocker::check_active_before_gc()) {
2742 return false;
2743 }
2744
2745 _gc_timer_stw->register_gc_start();
2746
2747 GCIdMark gc_id_mark;
2748 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2749
2750 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2751 ResourceMark rm;
2752
2753 g1_policy()->note_gc_start();
2754
2755 wait_for_root_region_scanning();
2756
2757 print_heap_before_gc();
2758 print_heap_regions();
2759 trace_heap_before_gc(_gc_tracer_stw);
2760
2761 _verifier->verify_region_sets_optional();
2762 _verifier->verify_dirty_young_regions();
2763
2764 // We should not be doing initial mark unless the conc mark thread is running
2765 if (!_cm_thread->should_terminate()) {
2766 // This call will decide whether this pause is an initial-mark
2767 // pause. If it is, in_initial_mark_gc() will return true
2768 // for the duration of this pause.
2769 g1_policy()->decide_on_conc_mark_initiation();
2770 }
2771
2772 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2773 assert(!collector_state()->in_initial_mark_gc() ||
2774 collector_state()->in_young_only_phase(), "sanity");
2775
2776 // We also do not allow mixed GCs during marking.
2777 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2778
2779 // Record whether this pause is an initial mark. When the current
2780 // thread has completed its logging output and it's safe to signal
2781 // the CM thread, the flag's value in the policy has been reset.
2782 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2783
2784 // Inner scope for scope based logging, timers, and stats collection
2785 {
2786 EvacuationInfo evacuation_info;
2787
2788 if (collector_state()->in_initial_mark_gc()) {
2789 // We are about to start a marking cycle, so we increment the
2790 // full collection counter.
2791 increment_old_marking_cycles_started();
2792 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2793 }
2794
2795 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2796
2797 GCTraceCPUTime tcpu;
2798
2799 G1HeapVerifier::G1VerifyType verify_type;
2800 FormatBuffer<> gc_string("Pause ");
2801 if (collector_state()->in_initial_mark_gc()) {
2802 gc_string.append("Initial Mark");
2803 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2804 } else if (collector_state()->in_young_only_phase()) {
2805 gc_string.append("Young");
2806 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2807 } else {
2808 gc_string.append("Mixed");
2809 verify_type = G1HeapVerifier::G1VerifyMixed;
2810 }
2811 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2812
2813 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2814 workers()->active_workers(),
2815 Threads::number_of_non_daemon_threads());
2816 active_workers = workers()->update_active_workers(active_workers);
2817 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2818
2819 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2820 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2821
2822 G1HeapTransition heap_transition(this);
2823 size_t heap_used_bytes_before_gc = used();
2824
2825 // Don't dynamically change the number of GC threads this early. A value of
2826 // 0 is used to indicate serial work. When parallel work is done,
2827 // it will be set.
2828
2829 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2830 IsGCActiveMark x;
2831
2832 gc_prologue(false);
2833
2834 if (VerifyRememberedSets) {
2835 log_info(gc, verify)("[Verifying RemSets before GC]");
2836 VerifyRegionRemSetClosure v_cl;
2837 heap_region_iterate(&v_cl);
2838 }
2839
2840 _verifier->verify_before_gc(verify_type);
2841
2842 _verifier->check_bitmaps("GC Start");
2843
2844 #if COMPILER2_OR_JVMCI
2845 DerivedPointerTable::clear();
2846 #endif
2847
2848 // Please see comment in g1CollectedHeap.hpp and
2849 // G1CollectedHeap::ref_processing_init() to see how
2850 // reference processing currently works in G1.
2851
2852 // Enable discovery in the STW reference processor
2853 ref_processor_stw()->enable_discovery();
2854
2855 {
2856 // We want to temporarily turn off discovery by the
2857 // CM ref processor, if necessary, and turn it back on
2858 // on again later if we do. Using a scoped
2859 // NoRefDiscovery object will do this.
2860 NoRefDiscovery no_cm_discovery(ref_processor_cm());
2861
2862 // Forget the current alloc region (we might even choose it to be part
2863 // of the collection set!).
2864 _allocator->release_mutator_alloc_region();
2865
2866 // This timing is only used by the ergonomics to handle our pause target.
2867 // It is unclear why this should not include the full pause. We will
2868 // investigate this in CR 7178365.
2869 //
2870 // Preserving the old comment here if that helps the investigation:
2871 //
2872 // The elapsed time induced by the start time below deliberately elides
2873 // the possible verification above.
2874 double sample_start_time_sec = os::elapsedTime();
2875
2876 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2877
2878 if (collector_state()->in_initial_mark_gc()) {
2879 concurrent_mark()->pre_initial_mark();
2880 }
2881
2882 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2883
2884 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2885
2886 // Make sure the remembered sets are up to date. This needs to be
2887 // done before register_humongous_regions_with_cset(), because the
2888 // remembered sets are used there to choose eager reclaim candidates.
2889 // If the remembered sets are not up to date we might miss some
2890 // entries that need to be handled.
2891 g1_rem_set()->cleanupHRRS();
2892
2893 register_humongous_regions_with_cset();
2894
2895 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2896
2897 // We call this after finalize_cset() to
2898 // ensure that the CSet has been finalized.
2899 _cm->verify_no_cset_oops();
2900
2901 if (_hr_printer.is_active()) {
2902 G1PrintCollectionSetClosure cl(&_hr_printer);
2903 _collection_set.iterate(&cl);
2904 }
2905
2906 // Initialize the GC alloc regions.
2907 _allocator->init_gc_alloc_regions(evacuation_info);
2908
2909 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2910 pre_evacuate_collection_set();
2911
2912 // Actually do the work...
2913 evacuate_collection_set(&per_thread_states);
2914
2915 post_evacuate_collection_set(evacuation_info, &per_thread_states);
2916
2917 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2918 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2919
2920 eagerly_reclaim_humongous_regions();
2921
2922 record_obj_copy_mem_stats();
2923 _survivor_evac_stats.adjust_desired_plab_sz();
2924 _old_evac_stats.adjust_desired_plab_sz();
2925
2926 double start = os::elapsedTime();
2927 start_new_collection_set();
2928 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2929
2930 if (evacuation_failed()) {
2931 set_used(recalculate_used());
2932 if (_archive_allocator != NULL) {
2933 _archive_allocator->clear_used();
2934 }
2935 for (uint i = 0; i < ParallelGCThreads; i++) {
2936 if (_evacuation_failed_info_array[i].has_failed()) {
2937 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
2938 }
2939 }
2940 } else {
2941 // The "used" of the the collection set have already been subtracted
2942 // when they were freed. Add in the bytes evacuated.
2943 increase_used(g1_policy()->bytes_copied_during_gc());
2944 }
2945
2946 if (collector_state()->in_initial_mark_gc()) {
2947 // We have to do this before we notify the CM threads that
2948 // they can start working to make sure that all the
2949 // appropriate initialization is done on the CM object.
2950 concurrent_mark()->post_initial_mark();
2951 // Note that we don't actually trigger the CM thread at
2952 // this point. We do that later when we're sure that
2953 // the current thread has completed its logging output.
2954 }
2955
2956 allocate_dummy_regions();
2957
2958 _allocator->init_mutator_alloc_region();
2959
2960 {
2961 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2962 if (expand_bytes > 0) {
2963 size_t bytes_before = capacity();
2964 // No need for an ergo logging here,
2965 // expansion_amount() does this when it returns a value > 0.
2966 double expand_ms;
2967 if (!expand(expand_bytes, _workers, &expand_ms)) {
2968 // We failed to expand the heap. Cannot do anything about it.
2969 }
2970 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
2971 }
2972 }
2973
2974 // We redo the verification but now wrt to the new CSet which
2975 // has just got initialized after the previous CSet was freed.
2976 _cm->verify_no_cset_oops();
2977
2978 // This timing is only used by the ergonomics to handle our pause target.
2979 // It is unclear why this should not include the full pause. We will
2980 // investigate this in CR 7178365.
2981 double sample_end_time_sec = os::elapsedTime();
2982 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
2983 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
2984 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
2985
2986 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
2987 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
2988
2989 if (VerifyRememberedSets) {
2990 log_info(gc, verify)("[Verifying RemSets after GC]");
2991 VerifyRegionRemSetClosure v_cl;
2992 heap_region_iterate(&v_cl);
2993 }
2994
2995 _verifier->verify_after_gc(verify_type);
2996 _verifier->check_bitmaps("GC End");
2997
2998 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
2999 ref_processor_stw()->verify_no_references_recorded();
3000
3001 // CM reference discovery will be re-enabled if necessary.
3002 }
3003
3004 #ifdef TRACESPINNING
3005 ParallelTaskTerminator::print_termination_counts();
3006 #endif
3007
3008 gc_epilogue(false);
3009 }
3010
3011 // Print the remainder of the GC log output.
3012 if (evacuation_failed()) {
3013 log_info(gc)("To-space exhausted");
3014 }
3015
3016 g1_policy()->print_phases();
3017 heap_transition.print();
3018
3019 // It is not yet to safe to tell the concurrent mark to
3020 // start as we have some optional output below. We don't want the
3021 // output from the concurrent mark thread interfering with this
3022 // logging output either.
3023
3024 _hrm.verify_optional();
3025 _verifier->verify_region_sets_optional();
3026
3027 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3028 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3029
3030 print_heap_after_gc();
3031 print_heap_regions();
3032 trace_heap_after_gc(_gc_tracer_stw);
3033
3034 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3035 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3036 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3037 // before any GC notifications are raised.
3038 g1mm()->update_sizes();
3039
3040 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3041 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3042 _gc_timer_stw->register_gc_end();
3043 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3044 }
3045 // It should now be safe to tell the concurrent mark thread to start
3046 // without its logging output interfering with the logging output
3047 // that came from the pause.
3048
3049 if (should_start_conc_mark) {
3050 // CAUTION: after the doConcurrentMark() call below,
3051 // the concurrent marking thread(s) could be running
3052 // concurrently with us. Make sure that anything after
3053 // this point does not assume that we are the only GC thread
3054 // running. Note: of course, the actual marking work will
3055 // not start until the safepoint itself is released in
3056 // SuspendibleThreadSet::desynchronize().
3057 do_concurrent_mark();
3058 }
3059
3060 return true;
3061 }
3062
3063 void G1CollectedHeap::remove_self_forwarding_pointers() {
3064 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3065 workers()->run_task(&rsfp_task);
3066 }
3067
3068 void G1CollectedHeap::restore_after_evac_failure() {
3069 double remove_self_forwards_start = os::elapsedTime();
3070
3071 remove_self_forwarding_pointers();
3072 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3073 _preserved_marks_set.restore(&task_executor);
3074
3075 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3076 }
3077
3078 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3079 if (!_evacuation_failed) {
3080 _evacuation_failed = true;
3081 }
3082
3083 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3084 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3085 }
3086
3087 bool G1ParEvacuateFollowersClosure::offer_termination() {
3088 G1ParScanThreadState* const pss = par_scan_state();
3089 start_term_time();
3090 const bool res = terminator()->offer_termination();
3091 end_term_time();
3092 return res;
3093 }
3094
3095 void G1ParEvacuateFollowersClosure::do_void() {
3096 G1ParScanThreadState* const pss = par_scan_state();
3097 pss->trim_queue();
3098 do {
3099 pss->steal_and_trim_queue(queues());
3100 } while (!offer_termination());
3101 }
3102
3103 class G1ParTask : public AbstractGangTask {
3104 protected:
3105 G1CollectedHeap* _g1h;
3106 G1ParScanThreadStateSet* _pss;
3107 RefToScanQueueSet* _queues;
3108 G1RootProcessor* _root_processor;
3109 ParallelTaskTerminator _terminator;
3110 uint _n_workers;
3111
3112 public:
3113 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3114 : AbstractGangTask("G1 collection"),
3115 _g1h(g1h),
3116 _pss(per_thread_states),
3117 _queues(task_queues),
3118 _root_processor(root_processor),
3119 _terminator(n_workers, _queues),
3120 _n_workers(n_workers)
3121 {}
3122
3123 void work(uint worker_id) {
3124 if (worker_id >= _n_workers) return; // no work needed this round
3125
3126 double start_sec = os::elapsedTime();
3127 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3128
3129 {
3130 ResourceMark rm;
3131 HandleMark hm;
3132
3133 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3134
3135 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3136 pss->set_ref_discoverer(rp);
3137
3138 double start_strong_roots_sec = os::elapsedTime();
3139
3140 _root_processor->evacuate_roots(pss->closures(), worker_id);
3141
3142 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3143 // treating the nmethods visited to act as roots for concurrent marking.
3144 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3145 // objects copied by the current evacuation.
3146 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3147 pss->closures()->weak_codeblobs(),
3148 worker_id);
3149
3150 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3151
3152 double term_sec = 0.0;
3153 size_t evac_term_attempts = 0;
3154 {
3155 double start = os::elapsedTime();
3156 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3157 evac.do_void();
3158
3159 evac_term_attempts = evac.term_attempts();
3160 term_sec = evac.term_time();
3161 double elapsed_sec = os::elapsedTime() - start;
3162 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3163 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3164 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3165 }
3166
3167 assert(pss->queue_is_empty(), "should be empty");
3168
3169 if (log_is_enabled(Debug, gc, task, stats)) {
3170 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3171 size_t lab_waste;
3172 size_t lab_undo_waste;
3173 pss->waste(lab_waste, lab_undo_waste);
3174 _g1h->print_termination_stats(worker_id,
3175 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3176 strong_roots_sec * 1000.0, /* strong roots time */
3177 term_sec * 1000.0, /* evac term time */
3178 evac_term_attempts, /* evac term attempts */
3179 lab_waste, /* alloc buffer waste */
3180 lab_undo_waste /* undo waste */
3181 );
3182 }
3183
3184 // Close the inner scope so that the ResourceMark and HandleMark
3185 // destructors are executed here and are included as part of the
3186 // "GC Worker Time".
3187 }
3188 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3189 }
3190 };
3191
3192 void G1CollectedHeap::print_termination_stats_hdr() {
3193 log_debug(gc, task, stats)("GC Termination Stats");
3194 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3195 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3196 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3197 }
3198
3199 void G1CollectedHeap::print_termination_stats(uint worker_id,
3200 double elapsed_ms,
3201 double strong_roots_ms,
3202 double term_ms,
3203 size_t term_attempts,
3204 size_t alloc_buffer_waste,
3205 size_t undo_waste) const {
3206 log_debug(gc, task, stats)
3207 ("%3d %9.2f %9.2f %6.2f "
3208 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3209 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3210 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3211 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3212 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3213 alloc_buffer_waste * HeapWordSize / K,
3214 undo_waste * HeapWordSize / K);
3215 }
3216
3217 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3218 private:
3219 BoolObjectClosure* _is_alive;
3220 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3221
3222 int _initial_string_table_size;
3223 int _initial_symbol_table_size;
3224
3225 bool _process_strings;
3226 int _strings_processed;
3227 int _strings_removed;
3228
3229 bool _process_symbols;
3230 int _symbols_processed;
3231 int _symbols_removed;
3232
3233 bool _process_string_dedup;
3234
3235 public:
3236 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3237 AbstractGangTask("String/Symbol Unlinking"),
3238 _is_alive(is_alive),
3239 _dedup_closure(is_alive, NULL, false),
3240 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3241 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3242 _process_string_dedup(process_string_dedup) {
3243
3244 _initial_string_table_size = StringTable::the_table()->table_size();
3245 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3246 if (process_strings) {
3247 StringTable::clear_parallel_claimed_index();
3248 }
3249 if (process_symbols) {
3250 SymbolTable::clear_parallel_claimed_index();
3251 }
3252 }
3253
3254 ~G1StringAndSymbolCleaningTask() {
3255 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3256 "claim value %d after unlink less than initial string table size %d",
3257 StringTable::parallel_claimed_index(), _initial_string_table_size);
3258 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3259 "claim value %d after unlink less than initial symbol table size %d",
3260 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3261
3262 log_info(gc, stringtable)(
3263 "Cleaned string and symbol table, "
3264 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3265 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3266 strings_processed(), strings_removed(),
3267 symbols_processed(), symbols_removed());
3268 }
3269
3270 void work(uint worker_id) {
3271 int strings_processed = 0;
3272 int strings_removed = 0;
3273 int symbols_processed = 0;
3274 int symbols_removed = 0;
3275 if (_process_strings) {
3276 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3277 Atomic::add(strings_processed, &_strings_processed);
3278 Atomic::add(strings_removed, &_strings_removed);
3279 }
3280 if (_process_symbols) {
3281 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3282 Atomic::add(symbols_processed, &_symbols_processed);
3283 Atomic::add(symbols_removed, &_symbols_removed);
3284 }
3285 if (_process_string_dedup) {
3286 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3287 }
3288 }
3289
3290 size_t strings_processed() const { return (size_t)_strings_processed; }
3291 size_t strings_removed() const { return (size_t)_strings_removed; }
3292
3293 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3294 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3295 };
3296
3297 class G1CodeCacheUnloadingTask {
3298 private:
3299 static Monitor* _lock;
3300
3301 BoolObjectClosure* const _is_alive;
3302 const bool _unloading_occurred;
3303 const uint _num_workers;
3304
3305 // Variables used to claim nmethods.
3306 CompiledMethod* _first_nmethod;
3307 CompiledMethod* volatile _claimed_nmethod;
3308
3309 // The list of nmethods that need to be processed by the second pass.
3310 CompiledMethod* volatile _postponed_list;
3311 volatile uint _num_entered_barrier;
3312
3313 public:
3314 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3315 _is_alive(is_alive),
3316 _unloading_occurred(unloading_occurred),
3317 _num_workers(num_workers),
3318 _first_nmethod(NULL),
3319 _claimed_nmethod(NULL),
3320 _postponed_list(NULL),
3321 _num_entered_barrier(0)
3322 {
3323 CompiledMethod::increase_unloading_clock();
3324 // Get first alive nmethod
3325 CompiledMethodIterator iter = CompiledMethodIterator();
3326 if(iter.next_alive()) {
3327 _first_nmethod = iter.method();
3328 }
3329 _claimed_nmethod = _first_nmethod;
3330 }
3331
3332 ~G1CodeCacheUnloadingTask() {
3333 CodeCache::verify_clean_inline_caches();
3334
3335 CodeCache::set_needs_cache_clean(false);
3336 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3337
3338 CodeCache::verify_icholder_relocations();
3339 }
3340
3341 private:
3342 void add_to_postponed_list(CompiledMethod* nm) {
3343 CompiledMethod* old;
3344 do {
3345 old = _postponed_list;
3346 nm->set_unloading_next(old);
3347 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3348 }
3349
3350 void clean_nmethod(CompiledMethod* nm) {
3351 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3352
3353 if (postponed) {
3354 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3355 add_to_postponed_list(nm);
3356 }
3357
3358 // Mark that this thread has been cleaned/unloaded.
3359 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3360 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3361 }
3362
3363 void clean_nmethod_postponed(CompiledMethod* nm) {
3364 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3365 }
3366
3367 static const int MaxClaimNmethods = 16;
3368
3369 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3370 CompiledMethod* first;
3371 CompiledMethodIterator last;
3372
3373 do {
3374 *num_claimed_nmethods = 0;
3375
3376 first = _claimed_nmethod;
3377 last = CompiledMethodIterator(first);
3378
3379 if (first != NULL) {
3380
3381 for (int i = 0; i < MaxClaimNmethods; i++) {
3382 if (!last.next_alive()) {
3383 break;
3384 }
3385 claimed_nmethods[i] = last.method();
3386 (*num_claimed_nmethods)++;
3387 }
3388 }
3389
3390 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3391 }
3392
3393 CompiledMethod* claim_postponed_nmethod() {
3394 CompiledMethod* claim;
3395 CompiledMethod* next;
3396
3397 do {
3398 claim = _postponed_list;
3399 if (claim == NULL) {
3400 return NULL;
3401 }
3402
3403 next = claim->unloading_next();
3404
3405 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3406
3407 return claim;
3408 }
3409
3410 public:
3411 // Mark that we're done with the first pass of nmethod cleaning.
3412 void barrier_mark(uint worker_id) {
3413 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3414 _num_entered_barrier++;
3415 if (_num_entered_barrier == _num_workers) {
3416 ml.notify_all();
3417 }
3418 }
3419
3420 // See if we have to wait for the other workers to
3421 // finish their first-pass nmethod cleaning work.
3422 void barrier_wait(uint worker_id) {
3423 if (_num_entered_barrier < _num_workers) {
3424 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3425 while (_num_entered_barrier < _num_workers) {
3426 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3427 }
3428 }
3429 }
3430
3431 // Cleaning and unloading of nmethods. Some work has to be postponed
3432 // to the second pass, when we know which nmethods survive.
3433 void work_first_pass(uint worker_id) {
3434 // The first nmethods is claimed by the first worker.
3435 if (worker_id == 0 && _first_nmethod != NULL) {
3436 clean_nmethod(_first_nmethod);
3437 _first_nmethod = NULL;
3438 }
3439
3440 int num_claimed_nmethods;
3441 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3442
3443 while (true) {
3444 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3445
3446 if (num_claimed_nmethods == 0) {
3447 break;
3448 }
3449
3450 for (int i = 0; i < num_claimed_nmethods; i++) {
3451 clean_nmethod(claimed_nmethods[i]);
3452 }
3453 }
3454 }
3455
3456 void work_second_pass(uint worker_id) {
3457 CompiledMethod* nm;
3458 // Take care of postponed nmethods.
3459 while ((nm = claim_postponed_nmethod()) != NULL) {
3460 clean_nmethod_postponed(nm);
3461 }
3462 }
3463 };
3464
3465 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3466
3467 class G1KlassCleaningTask : public StackObj {
3468 volatile int _clean_klass_tree_claimed;
3469 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3470
3471 public:
3472 G1KlassCleaningTask() :
3473 _clean_klass_tree_claimed(0),
3474 _klass_iterator() {
3475 }
3476
3477 private:
3478 bool claim_clean_klass_tree_task() {
3479 if (_clean_klass_tree_claimed) {
3480 return false;
3481 }
3482
3483 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3484 }
3485
3486 InstanceKlass* claim_next_klass() {
3487 Klass* klass;
3488 do {
3489 klass =_klass_iterator.next_klass();
3490 } while (klass != NULL && !klass->is_instance_klass());
3491
3492 // this can be null so don't call InstanceKlass::cast
3493 return static_cast<InstanceKlass*>(klass);
3494 }
3495
3496 public:
3497
3498 void clean_klass(InstanceKlass* ik) {
3499 ik->clean_weak_instanceklass_links();
3500 }
3501
3502 void work() {
3503 ResourceMark rm;
3504
3505 // One worker will clean the subklass/sibling klass tree.
3506 if (claim_clean_klass_tree_task()) {
3507 Klass::clean_subklass_tree();
3508 }
3509
3510 // All workers will help cleaning the classes,
3511 InstanceKlass* klass;
3512 while ((klass = claim_next_klass()) != NULL) {
3513 clean_klass(klass);
3514 }
3515 }
3516 };
3517
3518 class G1ResolvedMethodCleaningTask : public StackObj {
3519 volatile int _resolved_method_task_claimed;
3520 public:
3521 G1ResolvedMethodCleaningTask() :
3522 _resolved_method_task_claimed(0) {}
3523
3524 bool claim_resolved_method_task() {
3525 if (_resolved_method_task_claimed) {
3526 return false;
3527 }
3528 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3529 }
3530
3531 // These aren't big, one thread can do it all.
3532 void work() {
3533 if (claim_resolved_method_task()) {
3534 ResolvedMethodTable::unlink();
3535 }
3536 }
3537 };
3538
3539
3540 // To minimize the remark pause times, the tasks below are done in parallel.
3541 class G1ParallelCleaningTask : public AbstractGangTask {
3542 private:
3543 G1StringAndSymbolCleaningTask _string_symbol_task;
3544 G1CodeCacheUnloadingTask _code_cache_task;
3545 G1KlassCleaningTask _klass_cleaning_task;
3546 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3547
3548 public:
3549 // The constructor is run in the VMThread.
3550 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3551 AbstractGangTask("Parallel Cleaning"),
3552 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3553 _code_cache_task(num_workers, is_alive, unloading_occurred),
3554 _klass_cleaning_task(),
3555 _resolved_method_cleaning_task() {
3556 }
3557
3558 // The parallel work done by all worker threads.
3559 void work(uint worker_id) {
3560 // Do first pass of code cache cleaning.
3561 _code_cache_task.work_first_pass(worker_id);
3562
3563 // Let the threads mark that the first pass is done.
3564 _code_cache_task.barrier_mark(worker_id);
3565
3566 // Clean the Strings and Symbols.
3567 _string_symbol_task.work(worker_id);
3568
3569 // Clean unreferenced things in the ResolvedMethodTable
3570 _resolved_method_cleaning_task.work();
3571
3572 // Wait for all workers to finish the first code cache cleaning pass.
3573 _code_cache_task.barrier_wait(worker_id);
3574
3575 // Do the second code cache cleaning work, which realize on
3576 // the liveness information gathered during the first pass.
3577 _code_cache_task.work_second_pass(worker_id);
3578
3579 // Clean all klasses that were not unloaded.
3580 _klass_cleaning_task.work();
3581 }
3582 };
3583
3584
3585 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3586 bool class_unloading_occurred) {
3587 uint n_workers = workers()->active_workers();
3588
3589 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3590 workers()->run_task(&g1_unlink_task);
3591 }
3592
3593 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3594 bool process_strings,
3595 bool process_symbols,
3596 bool process_string_dedup) {
3597 if (!process_strings && !process_symbols && !process_string_dedup) {
3598 // Nothing to clean.
3599 return;
3600 }
3601
3602 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3603 workers()->run_task(&g1_unlink_task);
3604
3605 }
3606
3607 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3608 private:
3609 DirtyCardQueueSet* _queue;
3610 G1CollectedHeap* _g1h;
3611 public:
3612 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3613 _queue(queue), _g1h(g1h) { }
3614
3615 virtual void work(uint worker_id) {
3616 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3617 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3618
3619 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3620 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3621
3622 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3623 }
3624 };
3625
3626 void G1CollectedHeap::redirty_logged_cards() {
3627 double redirty_logged_cards_start = os::elapsedTime();
3628
3629 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3630 dirty_card_queue_set().reset_for_par_iteration();
3631 workers()->run_task(&redirty_task);
3632
3633 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3634 dcq.merge_bufferlists(&dirty_card_queue_set());
3635 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3636
3637 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3638 }
3639
3640 // Weak Reference Processing support
3641
3642 // An always "is_alive" closure that is used to preserve referents.
3643 // If the object is non-null then it's alive. Used in the preservation
3644 // of referent objects that are pointed to by reference objects
3645 // discovered by the CM ref processor.
3646 class G1AlwaysAliveClosure: public BoolObjectClosure {
3647 public:
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 !_g1h->is_in_cset(p) || p->is_forwarded();
3660 }
3661
3662 // Non Copying Keep Alive closure
3663 class G1KeepAliveClosure: public OopClosure {
3664 G1CollectedHeap*_g1h;
3665 public:
3666 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
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 =_g1h->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 _g1h->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_discoverer(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_discoverer(NULL);
3924 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3925
3926 // Is alive closure
3927 G1AlwaysAliveClosure always_alive;
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_discoverer(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 preserve_cm_referents(per_thread_states);
4198 process_discovered_references(per_thread_states);
4199
4200 G1STWIsAliveClosure is_alive(this);
4201 G1KeepAliveClosure keep_alive(this);
4202
4203 {
4204 double start = os::elapsedTime();
4205
4206 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4207
4208 double time_ms = (os::elapsedTime() - start) * 1000.0;
4209 g1_policy()->phase_times()->record_weak_ref_proc_time(time_ms);
4210 }
4211
4212 if (G1StringDedup::is_enabled()) {
4213 double fixup_start = os::elapsedTime();
4214
4215 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4216
4217 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4218 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4219 }
4220
4221 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4222
4223 if (evacuation_failed()) {
4224 restore_after_evac_failure();
4225
4226 // Reset the G1EvacuationFailureALot counters and flags
4227 // Note: the values are reset only when an actual
4228 // evacuation failure occurs.
4229 NOT_PRODUCT(reset_evacuation_should_fail();)
4230 }
4231
4232 _preserved_marks_set.assert_empty();
4233
4234 // Enqueue any remaining references remaining on the STW
4235 // reference processor's discovered lists. We need to do
4236 // this after the card table is cleaned (and verified) as
4237 // the act of enqueueing entries on to the pending list
4238 // will log these updates (and dirty their associated
4239 // cards). We need these updates logged to update any
4240 // RSets.
4241 enqueue_discovered_references(per_thread_states);
4242
4243 _allocator->release_gc_alloc_regions(evacuation_info);
4244
4245 merge_per_thread_state_info(per_thread_states);
4246
4247 // Reset and re-enable the hot card cache.
4248 // Note the counts for the cards in the regions in the
4249 // collection set are reset when the collection set is freed.
4250 _hot_card_cache->reset_hot_cache();
4251 _hot_card_cache->set_use_cache(true);
4252
4253 purge_code_root_memory();
4254
4255 redirty_logged_cards();
4256 #if COMPILER2_OR_JVMCI
4257 double start = os::elapsedTime();
4258 DerivedPointerTable::update_pointers();
4259 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4260 #endif
4261 g1_policy()->print_age_table();
4262 }
4263
4264 void G1CollectedHeap::record_obj_copy_mem_stats() {
4265 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4266
4267 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4268 create_g1_evac_summary(&_old_evac_stats));
4269 }
4270
4271 void G1CollectedHeap::free_region(HeapRegion* hr,
4272 FreeRegionList* free_list,
4273 bool skip_remset,
4274 bool skip_hot_card_cache,
4275 bool locked) {
4276 assert(!hr->is_free(), "the region should not be free");
4277 assert(!hr->is_empty(), "the region should not be empty");
4278 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4279 assert(free_list != NULL, "pre-condition");
4280
4281 if (G1VerifyBitmaps) {
4282 MemRegion mr(hr->bottom(), hr->end());
4283 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4284 }
4285
4286 // Clear the card counts for this region.
4287 // Note: we only need to do this if the region is not young
4288 // (since we don't refine cards in young regions).
4289 if (!skip_hot_card_cache && !hr->is_young()) {
4290 _hot_card_cache->reset_card_counts(hr);
4291 }
4292 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4293 _g1_policy->remset_tracker()->update_at_free(hr);
4294 free_list->add_ordered(hr);
4295 }
4296
4297 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4298 FreeRegionList* free_list) {
4299 assert(hr->is_humongous(), "this is only for humongous regions");
4300 assert(free_list != NULL, "pre-condition");
4301 hr->clear_humongous();
4302 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4303 }
4304
4305 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4306 const uint humongous_regions_removed) {
4307 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4308 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4309 _old_set.bulk_remove(old_regions_removed);
4310 _humongous_set.bulk_remove(humongous_regions_removed);
4311 }
4312
4313 }
4314
4315 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4316 assert(list != NULL, "list can't be null");
4317 if (!list->is_empty()) {
4318 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4319 _hrm.insert_list_into_free_list(list);
4320 }
4321 }
4322
4323 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4324 decrease_used(bytes);
4325 }
4326
4327 class G1FreeCollectionSetTask : public AbstractGangTask {
4328 private:
4329
4330 // Closure applied to all regions in the collection set to do work that needs to
4331 // be done serially in a single thread.
4332 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4333 private:
4334 EvacuationInfo* _evacuation_info;
4335 const size_t* _surviving_young_words;
4336
4337 // Bytes used in successfully evacuated regions before the evacuation.
4338 size_t _before_used_bytes;
4339 // Bytes used in unsucessfully evacuated regions before the evacuation
4340 size_t _after_used_bytes;
4341
4342 size_t _bytes_allocated_in_old_since_last_gc;
4343
4344 size_t _failure_used_words;
4345 size_t _failure_waste_words;
4346
4347 FreeRegionList _local_free_list;
4348 public:
4349 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4350 HeapRegionClosure(),
4351 _evacuation_info(evacuation_info),
4352 _surviving_young_words(surviving_young_words),
4353 _before_used_bytes(0),
4354 _after_used_bytes(0),
4355 _bytes_allocated_in_old_since_last_gc(0),
4356 _failure_used_words(0),
4357 _failure_waste_words(0),
4358 _local_free_list("Local Region List for CSet Freeing") {
4359 }
4360
4361 virtual bool do_heap_region(HeapRegion* r) {
4362 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4363
4364 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4365 g1h->clear_in_cset(r);
4366
4367 if (r->is_young()) {
4368 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4369 "Young index %d is wrong for region %u of type %s with %u young regions",
4370 r->young_index_in_cset(),
4371 r->hrm_index(),
4372 r->get_type_str(),
4373 g1h->collection_set()->young_region_length());
4374 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4375 r->record_surv_words_in_group(words_survived);
4376 }
4377
4378 if (!r->evacuation_failed()) {
4379 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4380 _before_used_bytes += r->used();
4381 g1h->free_region(r,
4382 &_local_free_list,
4383 true, /* skip_remset */
4384 true, /* skip_hot_card_cache */
4385 true /* locked */);
4386 } else {
4387 r->uninstall_surv_rate_group();
4388 r->set_young_index_in_cset(-1);
4389 r->set_evacuation_failed(false);
4390 // When moving a young gen region to old gen, we "allocate" that whole region
4391 // there. This is in addition to any already evacuated objects. Notify the
4392 // policy about that.
4393 // Old gen regions do not cause an additional allocation: both the objects
4394 // still in the region and the ones already moved are accounted for elsewhere.
4395 if (r->is_young()) {
4396 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4397 }
4398 // The region is now considered to be old.
4399 r->set_old();
4400 // Do some allocation statistics accounting. Regions that failed evacuation
4401 // are always made old, so there is no need to update anything in the young
4402 // gen statistics, but we need to update old gen statistics.
4403 size_t used_words = r->marked_bytes() / HeapWordSize;
4404
4405 _failure_used_words += used_words;
4406 _failure_waste_words += HeapRegion::GrainWords - used_words;
4407
4408 g1h->old_set_add(r);
4409 _after_used_bytes += r->used();
4410 }
4411 return false;
4412 }
4413
4414 void complete_work() {
4415 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4416
4417 _evacuation_info->set_regions_freed(_local_free_list.length());
4418 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4419
4420 g1h->prepend_to_freelist(&_local_free_list);
4421 g1h->decrement_summary_bytes(_before_used_bytes);
4422
4423 G1Policy* policy = g1h->g1_policy();
4424 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4425
4426 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4427 }
4428 };
4429
4430 G1CollectionSet* _collection_set;
4431 G1SerialFreeCollectionSetClosure _cl;
4432 const size_t* _surviving_young_words;
4433
4434 size_t _rs_lengths;
4435
4436 volatile jint _serial_work_claim;
4437
4438 struct WorkItem {
4439 uint region_idx;
4440 bool is_young;
4441 bool evacuation_failed;
4442
4443 WorkItem(HeapRegion* r) {
4444 region_idx = r->hrm_index();
4445 is_young = r->is_young();
4446 evacuation_failed = r->evacuation_failed();
4447 }
4448 };
4449
4450 volatile size_t _parallel_work_claim;
4451 size_t _num_work_items;
4452 WorkItem* _work_items;
4453
4454 void do_serial_work() {
4455 // Need to grab the lock to be allowed to modify the old region list.
4456 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4457 _collection_set->iterate(&_cl);
4458 }
4459
4460 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4461 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4462
4463 HeapRegion* r = g1h->region_at(region_idx);
4464 assert(!g1h->is_on_master_free_list(r), "sanity");
4465
4466 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4467
4468 if (!is_young) {
4469 g1h->_hot_card_cache->reset_card_counts(r);
4470 }
4471
4472 if (!evacuation_failed) {
4473 r->rem_set()->clear_locked();
4474 }
4475 }
4476
4477 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4478 private:
4479 size_t _cur_idx;
4480 WorkItem* _work_items;
4481 public:
4482 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4483
4484 virtual bool do_heap_region(HeapRegion* r) {
4485 _work_items[_cur_idx++] = WorkItem(r);
4486 return false;
4487 }
4488 };
4489
4490 void prepare_work() {
4491 G1PrepareFreeCollectionSetClosure cl(_work_items);
4492 _collection_set->iterate(&cl);
4493 }
4494
4495 void complete_work() {
4496 _cl.complete_work();
4497
4498 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4499 policy->record_max_rs_lengths(_rs_lengths);
4500 policy->cset_regions_freed();
4501 }
4502 public:
4503 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4504 AbstractGangTask("G1 Free Collection Set"),
4505 _cl(evacuation_info, surviving_young_words),
4506 _collection_set(collection_set),
4507 _surviving_young_words(surviving_young_words),
4508 _serial_work_claim(0),
4509 _rs_lengths(0),
4510 _parallel_work_claim(0),
4511 _num_work_items(collection_set->region_length()),
4512 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4513 prepare_work();
4514 }
4515
4516 ~G1FreeCollectionSetTask() {
4517 complete_work();
4518 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4519 }
4520
4521 // Chunk size for work distribution. The chosen value has been determined experimentally
4522 // to be a good tradeoff between overhead and achievable parallelism.
4523 static uint chunk_size() { return 32; }
4524
4525 virtual void work(uint worker_id) {
4526 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4527
4528 // Claim serial work.
4529 if (_serial_work_claim == 0) {
4530 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4531 if (value == 0) {
4532 double serial_time = os::elapsedTime();
4533 do_serial_work();
4534 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4535 }
4536 }
4537
4538 // Start parallel work.
4539 double young_time = 0.0;
4540 bool has_young_time = false;
4541 double non_young_time = 0.0;
4542 bool has_non_young_time = false;
4543
4544 while (true) {
4545 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4546 size_t cur = end - chunk_size();
4547
4548 if (cur >= _num_work_items) {
4549 break;
4550 }
4551
4552 double start_time = os::elapsedTime();
4553
4554 end = MIN2(end, _num_work_items);
4555
4556 for (; cur < end; cur++) {
4557 bool is_young = _work_items[cur].is_young;
4558
4559 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4560
4561 double end_time = os::elapsedTime();
4562 double time_taken = end_time - start_time;
4563 if (is_young) {
4564 young_time += time_taken;
4565 has_young_time = true;
4566 } else {
4567 non_young_time += time_taken;
4568 has_non_young_time = true;
4569 }
4570 start_time = end_time;
4571 }
4572 }
4573
4574 if (has_young_time) {
4575 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4576 }
4577 if (has_non_young_time) {
4578 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4579 }
4580 }
4581 };
4582
4583 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4584 _eden.clear();
4585
4586 double free_cset_start_time = os::elapsedTime();
4587
4588 {
4589 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4590 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4591
4592 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4593
4594 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4595 cl.name(),
4596 num_workers,
4597 _collection_set.region_length());
4598 workers()->run_task(&cl, num_workers);
4599 }
4600 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4601
4602 collection_set->clear();
4603 }
4604
4605 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4606 private:
4607 FreeRegionList* _free_region_list;
4608 HeapRegionSet* _proxy_set;
4609 uint _humongous_objects_reclaimed;
4610 uint _humongous_regions_reclaimed;
4611 size_t _freed_bytes;
4612 public:
4613
4614 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4615 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4616 }
4617
4618 virtual bool do_heap_region(HeapRegion* r) {
4619 if (!r->is_starts_humongous()) {
4620 return false;
4621 }
4622
4623 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4624
4625 oop obj = (oop)r->bottom();
4626 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4627
4628 // The following checks whether the humongous object is live are sufficient.
4629 // The main additional check (in addition to having a reference from the roots
4630 // or the young gen) is whether the humongous object has a remembered set entry.
4631 //
4632 // A humongous object cannot be live if there is no remembered set for it
4633 // because:
4634 // - there can be no references from within humongous starts regions referencing
4635 // the object because we never allocate other objects into them.
4636 // (I.e. there are no intra-region references that may be missed by the
4637 // remembered set)
4638 // - as soon there is a remembered set entry to the humongous starts region
4639 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4640 // until the end of a concurrent mark.
4641 //
4642 // It is not required to check whether the object has been found dead by marking
4643 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4644 // all objects allocated during that time are considered live.
4645 // SATB marking is even more conservative than the remembered set.
4646 // So if at this point in the collection there is no remembered set entry,
4647 // nobody has a reference to it.
4648 // At the start of collection we flush all refinement logs, and remembered sets
4649 // are completely up-to-date wrt to references to the humongous object.
4650 //
4651 // Other implementation considerations:
4652 // - never consider object arrays at this time because they would pose
4653 // considerable effort for cleaning up the the remembered sets. This is
4654 // required because stale remembered sets might reference locations that
4655 // are currently allocated into.
4656 uint region_idx = r->hrm_index();
4657 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4658 !r->rem_set()->is_empty()) {
4659 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",
4660 region_idx,
4661 (size_t)obj->size() * HeapWordSize,
4662 p2i(r->bottom()),
4663 r->rem_set()->occupied(),
4664 r->rem_set()->strong_code_roots_list_length(),
4665 next_bitmap->is_marked(r->bottom()),
4666 g1h->is_humongous_reclaim_candidate(region_idx),
4667 obj->is_typeArray()
4668 );
4669 return false;
4670 }
4671
4672 guarantee(obj->is_typeArray(),
4673 "Only eagerly reclaiming type arrays is supported, but the object "
4674 PTR_FORMAT " is not.", p2i(r->bottom()));
4675
4676 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",
4677 region_idx,
4678 (size_t)obj->size() * HeapWordSize,
4679 p2i(r->bottom()),
4680 r->rem_set()->occupied(),
4681 r->rem_set()->strong_code_roots_list_length(),
4682 next_bitmap->is_marked(r->bottom()),
4683 g1h->is_humongous_reclaim_candidate(region_idx),
4684 obj->is_typeArray()
4685 );
4686
4687 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4688 cm->humongous_object_eagerly_reclaimed(r);
4689 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4690 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4691 region_idx,
4692 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4693 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4694 _humongous_objects_reclaimed++;
4695 do {
4696 HeapRegion* next = g1h->next_region_in_humongous(r);
4697 _freed_bytes += r->used();
4698 r->set_containing_set(NULL);
4699 _humongous_regions_reclaimed++;
4700 g1h->free_humongous_region(r, _free_region_list);
4701 r = next;
4702 } while (r != NULL);
4703
4704 return false;
4705 }
4706
4707 uint humongous_objects_reclaimed() {
4708 return _humongous_objects_reclaimed;
4709 }
4710
4711 uint humongous_regions_reclaimed() {
4712 return _humongous_regions_reclaimed;
4713 }
4714
4715 size_t bytes_freed() const {
4716 return _freed_bytes;
4717 }
4718 };
4719
4720 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4721 assert_at_safepoint_on_vm_thread();
4722
4723 if (!G1EagerReclaimHumongousObjects ||
4724 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4725 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4726 return;
4727 }
4728
4729 double start_time = os::elapsedTime();
4730
4731 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4732
4733 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4734 heap_region_iterate(&cl);
4735
4736 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4737
4738 G1HRPrinter* hrp = hr_printer();
4739 if (hrp->is_active()) {
4740 FreeRegionListIterator iter(&local_cleanup_list);
4741 while (iter.more_available()) {
4742 HeapRegion* hr = iter.get_next();
4743 hrp->cleanup(hr);
4744 }
4745 }
4746
4747 prepend_to_freelist(&local_cleanup_list);
4748 decrement_summary_bytes(cl.bytes_freed());
4749
4750 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4751 cl.humongous_objects_reclaimed());
4752 }
4753
4754 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4755 public:
4756 virtual bool do_heap_region(HeapRegion* r) {
4757 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4758 G1CollectedHeap::heap()->clear_in_cset(r);
4759 r->set_young_index_in_cset(-1);
4760 return false;
4761 }
4762 };
4763
4764 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4765 G1AbandonCollectionSetClosure cl;
4766 collection_set->iterate(&cl);
4767
4768 collection_set->clear();
4769 collection_set->stop_incremental_building();
4770 }
4771
4772 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4773 return _allocator->is_retained_old_region(hr);
4774 }
4775
4776 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4777 _eden.add(hr);
4778 _g1_policy->set_region_eden(hr);
4779 }
4780
4781 #ifdef ASSERT
4782
4783 class NoYoungRegionsClosure: public HeapRegionClosure {
4784 private:
4785 bool _success;
4786 public:
4787 NoYoungRegionsClosure() : _success(true) { }
4788 bool do_heap_region(HeapRegion* r) {
4789 if (r->is_young()) {
4790 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4791 p2i(r->bottom()), p2i(r->end()));
4792 _success = false;
4793 }
4794 return false;
4795 }
4796 bool success() { return _success; }
4797 };
4798
4799 bool G1CollectedHeap::check_young_list_empty() {
4800 bool ret = (young_regions_count() == 0);
4801
4802 NoYoungRegionsClosure closure;
4803 heap_region_iterate(&closure);
4804 ret = ret && closure.success();
4805
4806 return ret;
4807 }
4808
4809 #endif // ASSERT
4810
4811 class TearDownRegionSetsClosure : public HeapRegionClosure {
4812 private:
4813 HeapRegionSet *_old_set;
4814
4815 public:
4816 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4817
4818 bool do_heap_region(HeapRegion* r) {
4819 if (r->is_old()) {
4820 _old_set->remove(r);
4821 } else if(r->is_young()) {
4822 r->uninstall_surv_rate_group();
4823 } else {
4824 // We ignore free regions, we'll empty the free list afterwards.
4825 // We ignore humongous regions, we're not tearing down the
4826 // humongous regions set.
4827 assert(r->is_free() || r->is_humongous(),
4828 "it cannot be another type");
4829 }
4830 return false;
4831 }
4832
4833 ~TearDownRegionSetsClosure() {
4834 assert(_old_set->is_empty(), "post-condition");
4835 }
4836 };
4837
4838 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4839 assert_at_safepoint_on_vm_thread();
4840
4841 if (!free_list_only) {
4842 TearDownRegionSetsClosure cl(&_old_set);
4843 heap_region_iterate(&cl);
4844
4845 // Note that emptying the _young_list is postponed and instead done as
4846 // the first step when rebuilding the regions sets again. The reason for
4847 // this is that during a full GC string deduplication needs to know if
4848 // a collected region was young or old when the full GC was initiated.
4849 }
4850 _hrm.remove_all_free_regions();
4851 }
4852
4853 void G1CollectedHeap::increase_used(size_t bytes) {
4854 _summary_bytes_used += bytes;
4855 }
4856
4857 void G1CollectedHeap::decrease_used(size_t bytes) {
4858 assert(_summary_bytes_used >= bytes,
4859 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4860 _summary_bytes_used, bytes);
4861 _summary_bytes_used -= bytes;
4862 }
4863
4864 void G1CollectedHeap::set_used(size_t bytes) {
4865 _summary_bytes_used = bytes;
4866 }
4867
4868 class RebuildRegionSetsClosure : public HeapRegionClosure {
4869 private:
4870 bool _free_list_only;
4871 HeapRegionSet* _old_set;
4872 HeapRegionManager* _hrm;
4873 size_t _total_used;
4874
4875 public:
4876 RebuildRegionSetsClosure(bool free_list_only,
4877 HeapRegionSet* old_set, HeapRegionManager* hrm) :
4878 _free_list_only(free_list_only),
4879 _old_set(old_set), _hrm(hrm), _total_used(0) {
4880 assert(_hrm->num_free_regions() == 0, "pre-condition");
4881 if (!free_list_only) {
4882 assert(_old_set->is_empty(), "pre-condition");
4883 }
4884 }
4885
4886 bool do_heap_region(HeapRegion* r) {
4887 // After full GC, no region should have a remembered set.
4888 r->rem_set()->clear(true);
4889 if (r->is_empty()) {
4890 // Add free regions to the free list
4891 r->set_free();
4892 _hrm->insert_into_free_list(r);
4893 } else if (!_free_list_only) {
4894
4895 if (r->is_humongous()) {
4896 // We ignore humongous regions. We left the humongous set unchanged.
4897 } else {
4898 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4899 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
4900 r->move_to_old();
4901 _old_set->add(r);
4902 }
4903 _total_used += r->used();
4904 }
4905
4906 return false;
4907 }
4908
4909 size_t total_used() {
4910 return _total_used;
4911 }
4912 };
4913
4914 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4915 assert_at_safepoint_on_vm_thread();
4916
4917 if (!free_list_only) {
4918 _eden.clear();
4919 _survivor.clear();
4920 }
4921
4922 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4923 heap_region_iterate(&cl);
4924
4925 if (!free_list_only) {
4926 set_used(cl.total_used());
4927 if (_archive_allocator != NULL) {
4928 _archive_allocator->clear_used();
4929 }
4930 }
4931 assert(used_unlocked() == recalculate_used(),
4932 "inconsistent used_unlocked(), "
4933 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4934 used_unlocked(), recalculate_used());
4935 }
4936
4937 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4938 HeapRegion* hr = heap_region_containing(p);
4939 return hr->is_in(p);
4940 }
4941
4942 // Methods for the mutator alloc region
4943
4944 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4945 bool force) {
4946 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4947 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4948 if (force || should_allocate) {
4949 HeapRegion* new_alloc_region = new_region(word_size,
4950 false /* is_old */,
4951 false /* do_expand */);
4952 if (new_alloc_region != NULL) {
4953 set_region_short_lived_locked(new_alloc_region);
4954 _hr_printer.alloc(new_alloc_region, !should_allocate);
4955 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4956 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4957 return new_alloc_region;
4958 }
4959 }
4960 return NULL;
4961 }
4962
4963 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4964 size_t allocated_bytes) {
4965 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4966 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4967
4968 collection_set()->add_eden_region(alloc_region);
4969 increase_used(allocated_bytes);
4970 _hr_printer.retire(alloc_region);
4971 // We update the eden sizes here, when the region is retired,
4972 // instead of when it's allocated, since this is the point that its
4973 // used space has been recored in _summary_bytes_used.
4974 g1mm()->update_eden_size();
4975 }
4976
4977 // Methods for the GC alloc regions
4978
4979 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4980 if (dest.is_old()) {
4981 return true;
4982 } else {
4983 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4984 }
4985 }
4986
4987 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4988 assert(FreeList_lock->owned_by_self(), "pre-condition");
4989
4990 if (!has_more_regions(dest)) {
4991 return NULL;
4992 }
4993
4994 const bool is_survivor = dest.is_young();
4995
4996 HeapRegion* new_alloc_region = new_region(word_size,
4997 !is_survivor,
4998 true /* do_expand */);
4999 if (new_alloc_region != NULL) {
5000 if (is_survivor) {
5001 new_alloc_region->set_survivor();
5002 _survivor.add(new_alloc_region);
5003 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5004 } else {
5005 new_alloc_region->set_old();
5006 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5007 }
5008 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
5009 _hr_printer.alloc(new_alloc_region);
5010 bool during_im = collector_state()->in_initial_mark_gc();
5011 new_alloc_region->note_start_of_copying(during_im);
5012 return new_alloc_region;
5013 }
5014 return NULL;
5015 }
5016
5017 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5018 size_t allocated_bytes,
5019 InCSetState dest) {
5020 bool during_im = collector_state()->in_initial_mark_gc();
5021 alloc_region->note_end_of_copying(during_im);
5022 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5023 if (dest.is_old()) {
5024 _old_set.add(alloc_region);
5025 }
5026 _hr_printer.retire(alloc_region);
5027 }
5028
5029 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5030 bool expanded = false;
5031 uint index = _hrm.find_highest_free(&expanded);
5032
5033 if (index != G1_NO_HRM_INDEX) {
5034 if (expanded) {
5035 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5036 HeapRegion::GrainWords * HeapWordSize);
5037 }
5038 _hrm.allocate_free_regions_starting_at(index, 1);
5039 return region_at(index);
5040 }
5041 return NULL;
5042 }
5043
5044 // Optimized nmethod scanning
5045
5046 class RegisterNMethodOopClosure: public OopClosure {
5047 G1CollectedHeap* _g1h;
5048 nmethod* _nm;
5049
5050 template <class T> void do_oop_work(T* p) {
5051 T heap_oop = RawAccess<>::oop_load(p);
5052 if (!CompressedOops::is_null(heap_oop)) {
5053 oop obj = CompressedOops::decode_not_null(heap_oop);
5054 HeapRegion* hr = _g1h->heap_region_containing(obj);
5055 assert(!hr->is_continues_humongous(),
5056 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5057 " starting at " HR_FORMAT,
5058 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5059
5060 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5061 hr->add_strong_code_root_locked(_nm);
5062 }
5063 }
5064
5065 public:
5066 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5067 _g1h(g1h), _nm(nm) {}
5068
5069 void do_oop(oop* p) { do_oop_work(p); }
5070 void do_oop(narrowOop* p) { do_oop_work(p); }
5071 };
5072
5073 class UnregisterNMethodOopClosure: public OopClosure {
5074 G1CollectedHeap* _g1h;
5075 nmethod* _nm;
5076
5077 template <class T> void do_oop_work(T* p) {
5078 T heap_oop = RawAccess<>::oop_load(p);
5079 if (!CompressedOops::is_null(heap_oop)) {
5080 oop obj = CompressedOops::decode_not_null(heap_oop);
5081 HeapRegion* hr = _g1h->heap_region_containing(obj);
5082 assert(!hr->is_continues_humongous(),
5083 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5084 " starting at " HR_FORMAT,
5085 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5086
5087 hr->remove_strong_code_root(_nm);
5088 }
5089 }
5090
5091 public:
5092 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5093 _g1h(g1h), _nm(nm) {}
5094
5095 void do_oop(oop* p) { do_oop_work(p); }
5096 void do_oop(narrowOop* p) { do_oop_work(p); }
5097 };
5098
5099 // Returns true if the reference points to an object that
5100 // can move in an incremental collection.
5101 bool G1CollectedHeap::is_scavengable(oop obj) {
5102 HeapRegion* hr = heap_region_containing(obj);
5103 return !hr->is_pinned();
5104 }
5105
5106 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5107 guarantee(nm != NULL, "sanity");
5108 RegisterNMethodOopClosure reg_cl(this, nm);
5109 nm->oops_do(®_cl);
5110 }
5111
5112 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5113 guarantee(nm != NULL, "sanity");
5114 UnregisterNMethodOopClosure reg_cl(this, nm);
5115 nm->oops_do(®_cl, true);
5116 }
5117
5118 void G1CollectedHeap::purge_code_root_memory() {
5119 double purge_start = os::elapsedTime();
5120 G1CodeRootSet::purge();
5121 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5122 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5123 }
5124
5125 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5126 G1CollectedHeap* _g1h;
5127
5128 public:
5129 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5130 _g1h(g1h) {}
5131
5132 void do_code_blob(CodeBlob* cb) {
5133 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5134 if (nm == NULL) {
5135 return;
5136 }
5137
5138 if (ScavengeRootsInCode) {
5139 _g1h->register_nmethod(nm);
5140 }
5141 }
5142 };
5143
5144 void G1CollectedHeap::rebuild_strong_code_roots() {
5145 RebuildStrongCodeRootClosure blob_cl(this);
5146 CodeCache::blobs_do(&blob_cl);
5147 }
5148
5149 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5150 GrowableArray<GCMemoryManager*> memory_managers(2);
5151 memory_managers.append(&_memory_manager);
5152 memory_managers.append(&_full_gc_memory_manager);
5153 return memory_managers;
5154 }
5155
5156 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5157 GrowableArray<MemoryPool*> memory_pools(3);
5158 memory_pools.append(_eden_pool);
5159 memory_pools.append(_survivor_pool);
5160 memory_pools.append(_old_pool);
5161 return memory_pools;
5162 }