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/concurrentMarkThread.inline.hpp"
33 #include "gc/g1/g1Allocator.inline.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/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1MemoryPool.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1StringDedup.hpp"
56 #include "gc/g1/g1YCTypes.hpp"
57 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
58 #include "gc/g1/heapRegion.inline.hpp"
59 #include "gc/g1/heapRegionRemSet.hpp"
60 #include "gc/g1/heapRegionSet.inline.hpp"
61 #include "gc/g1/vm_operations_g1.hpp"
62 #include "gc/shared/gcHeapSummary.hpp"
63 #include "gc/shared/gcId.hpp"
64 #include "gc/shared/gcLocker.inline.hpp"
65 #include "gc/shared/gcTimer.hpp"
66 #include "gc/shared/gcTrace.hpp"
67 #include "gc/shared/gcTraceTime.inline.hpp"
68 #include "gc/shared/generationSpec.hpp"
69 #include "gc/shared/isGCActiveMark.hpp"
70 #include "gc/shared/preservedMarks.inline.hpp"
71 #include "gc/shared/suspendibleThreadSet.hpp"
72 #include "gc/shared/referenceProcessor.inline.hpp"
73 #include "gc/shared/taskqueue.inline.hpp"
74 #include "gc/shared/weakProcessor.hpp"
75 #include "logging/log.hpp"
76 #include "memory/allocation.hpp"
77 #include "memory/iterator.hpp"
78 #include "memory/resourceArea.hpp"
79 #include "oops/oop.inline.hpp"
80 #include "prims/resolvedMethodTable.hpp"
81 #include "runtime/atomic.hpp"
82 #include "runtime/init.hpp"
83 #include "runtime/orderAccess.inline.hpp"
84 #include "runtime/threadSMR.hpp"
85 #include "runtime/vmThread.hpp"
86 #include "utilities/align.hpp"
87 #include "utilities/globalDefinitions.hpp"
88 #include "utilities/stack.inline.hpp"
89
90 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
91
92 // INVARIANTS/NOTES
93 //
94 // All allocation activity covered by the G1CollectedHeap interface is
95 // serialized by acquiring the HeapLock. This happens in mem_allocate
96 // and allocate_new_tlab, which are the "entry" points to the
97 // allocation code from the rest of the JVM. (Note that this does not
98 // apply to TLAB allocation, which is not part of this interface: it
99 // is done by clients of this interface.)
100
101 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
102 private:
103 size_t _num_dirtied;
104 G1CollectedHeap* _g1h;
105 G1SATBCardTableLoggingModRefBS* _g1_bs;
106
107 HeapRegion* region_for_card(jbyte* card_ptr) const {
108 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
109 }
110
111 bool will_become_free(HeapRegion* hr) const {
112 // A region will be freed by free_collection_set if the region is in the
113 // collection set and has not had an evacuation failure.
114 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
115 }
116
117 public:
118 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
119 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
120
121 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
122 HeapRegion* hr = region_for_card(card_ptr);
123
124 // Should only dirty cards in regions that won't be freed.
125 if (!will_become_free(hr)) {
126 *card_ptr = CardTableModRefBS::dirty_card_val();
127 _num_dirtied++;
128 }
129
130 return true;
131 }
132
133 size_t num_dirtied() const { return _num_dirtied; }
134 };
135
136
137 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
138 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
139 }
140
141 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
142 // The from card cache is not the memory that is actually committed. So we cannot
143 // take advantage of the zero_filled parameter.
144 reset_from_card_cache(start_idx, num_regions);
145 }
146
147
148 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
149 MemRegion mr) {
150 return new HeapRegion(hrs_index, bot(), mr);
151 }
152
153 // Private methods.
154
155 HeapRegion*
156 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
157 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
158 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
159 if (!_secondary_free_list.is_empty()) {
160 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
161 "secondary_free_list has %u entries",
162 _secondary_free_list.length());
163 // It looks as if there are free regions available on the
164 // secondary_free_list. Let's move them to the free_list and try
165 // again to allocate from it.
166 append_secondary_free_list();
167
168 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
169 "empty we should have moved at least one entry to the free_list");
170 HeapRegion* res = _hrm.allocate_free_region(is_old);
171 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
172 "allocated " HR_FORMAT " from secondary_free_list",
173 HR_FORMAT_PARAMS(res));
174 return res;
175 }
176
177 // Wait here until we get notified either when (a) there are no
178 // more free regions coming or (b) some regions have been moved on
179 // the secondary_free_list.
180 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
181 }
182
183 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
184 "could not allocate from secondary_free_list");
185 return NULL;
186 }
187
188 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
189 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
190 "the only time we use this to allocate a humongous region is "
191 "when we are allocating a single humongous region");
192
193 HeapRegion* res;
194 if (G1StressConcRegionFreeing) {
195 if (!_secondary_free_list.is_empty()) {
196 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
197 "forced to look at the secondary_free_list");
198 res = new_region_try_secondary_free_list(is_old);
199 if (res != NULL) {
200 return res;
201 }
202 }
203 }
204
205 res = _hrm.allocate_free_region(is_old);
206
207 if (res == NULL) {
208 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
209 "res == NULL, trying the secondary_free_list");
210 res = new_region_try_secondary_free_list(is_old);
211 }
212 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
213 // Currently, only attempts to allocate GC alloc regions set
214 // do_expand to true. So, we should only reach here during a
215 // safepoint. If this assumption changes we might have to
216 // reconsider the use of _expand_heap_after_alloc_failure.
217 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
218
219 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
220 word_size * HeapWordSize);
221
222 if (expand(word_size * HeapWordSize)) {
223 // Given that expand() succeeded in expanding the heap, and we
224 // always expand the heap by an amount aligned to the heap
225 // region size, the free list should in theory not be empty.
226 // In either case allocate_free_region() will check for NULL.
227 res = _hrm.allocate_free_region(is_old);
228 } else {
229 _expand_heap_after_alloc_failure = false;
230 }
231 }
232 return res;
233 }
234
235 HeapWord*
236 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
237 uint num_regions,
238 size_t word_size,
239 AllocationContext_t context) {
240 assert(first != G1_NO_HRM_INDEX, "pre-condition");
241 assert(is_humongous(word_size), "word_size should be humongous");
242 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
243
244 // Index of last region in the series.
245 uint last = first + num_regions - 1;
246
247 // We need to initialize the region(s) we just discovered. This is
248 // a bit tricky given that it can happen concurrently with
249 // refinement threads refining cards on these regions and
250 // potentially wanting to refine the BOT as they are scanning
251 // those cards (this can happen shortly after a cleanup; see CR
252 // 6991377). So we have to set up the region(s) carefully and in
253 // a specific order.
254
255 // The word size sum of all the regions we will allocate.
256 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
257 assert(word_size <= word_size_sum, "sanity");
258
259 // This will be the "starts humongous" region.
260 HeapRegion* first_hr = region_at(first);
261 // The header of the new object will be placed at the bottom of
262 // the first region.
263 HeapWord* new_obj = first_hr->bottom();
264 // This will be the new top of the new object.
265 HeapWord* obj_top = new_obj + word_size;
266
267 // First, we need to zero the header of the space that we will be
268 // allocating. When we update top further down, some refinement
269 // threads might try to scan the region. By zeroing the header we
270 // ensure that any thread that will try to scan the region will
271 // come across the zero klass word and bail out.
272 //
273 // NOTE: It would not have been correct to have used
274 // CollectedHeap::fill_with_object() and make the space look like
275 // an int array. The thread that is doing the allocation will
276 // later update the object header to a potentially different array
277 // type and, for a very short period of time, the klass and length
278 // fields will be inconsistent. This could cause a refinement
279 // thread to calculate the object size incorrectly.
280 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
281
282 // Next, pad out the unused tail of the last region with filler
283 // objects, for improved usage accounting.
284 // How many words we use for filler objects.
285 size_t word_fill_size = word_size_sum - word_size;
286
287 // How many words memory we "waste" which cannot hold a filler object.
288 size_t words_not_fillable = 0;
289
290 if (word_fill_size >= min_fill_size()) {
291 fill_with_objects(obj_top, word_fill_size);
292 } else if (word_fill_size > 0) {
293 // We have space to fill, but we cannot fit an object there.
294 words_not_fillable = word_fill_size;
295 word_fill_size = 0;
296 }
297
298 // We will set up the first region as "starts humongous". This
299 // will also update the BOT covering all the regions to reflect
300 // that there is a single object that starts at the bottom of the
301 // first region.
302 first_hr->set_starts_humongous(obj_top, word_fill_size);
303 first_hr->set_allocation_context(context);
304 // Then, if there are any, we will set up the "continues
305 // humongous" regions.
306 HeapRegion* hr = NULL;
307 for (uint i = first + 1; i <= last; ++i) {
308 hr = region_at(i);
309 hr->set_continues_humongous(first_hr);
310 hr->set_allocation_context(context);
311 }
312
313 // Up to this point no concurrent thread would have been able to
314 // do any scanning on any region in this series. All the top
315 // fields still point to bottom, so the intersection between
316 // [bottom,top] and [card_start,card_end] will be empty. Before we
317 // update the top fields, we'll do a storestore to make sure that
318 // no thread sees the update to top before the zeroing of the
319 // object header and the BOT initialization.
320 OrderAccess::storestore();
321
322 // Now, we will update the top fields of the "continues humongous"
323 // regions except the last one.
324 for (uint i = first; i < last; ++i) {
325 hr = region_at(i);
326 hr->set_top(hr->end());
327 }
328
329 hr = region_at(last);
330 // If we cannot fit a filler object, we must set top to the end
331 // of the humongous object, otherwise we cannot iterate the heap
332 // and the BOT will not be complete.
333 hr->set_top(hr->end() - words_not_fillable);
334
335 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
336 "obj_top should be in last region");
337
338 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
339
340 assert(words_not_fillable == 0 ||
341 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
342 "Miscalculation in humongous allocation");
343
344 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
345
346 for (uint i = first; i <= last; ++i) {
347 hr = region_at(i);
348 _humongous_set.add(hr);
349 _hr_printer.alloc(hr);
350 }
351
352 return new_obj;
353 }
354
355 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
356 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
357 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
358 }
359
360 // If could fit into free regions w/o expansion, try.
361 // Otherwise, if can expand, do so.
362 // Otherwise, if using ex regions might help, try with ex given back.
363 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
364 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
365
366 _verifier->verify_region_sets_optional();
367
368 uint first = G1_NO_HRM_INDEX;
369 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
370
371 if (obj_regions == 1) {
372 // Only one region to allocate, try to use a fast path by directly allocating
373 // from the free lists. Do not try to expand here, we will potentially do that
374 // later.
375 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
376 if (hr != NULL) {
377 first = hr->hrm_index();
378 }
379 } else {
380 // We can't allocate humongous regions spanning more than one region while
381 // cleanupComplete() is running, since some of the regions we find to be
382 // empty might not yet be added to the free list. It is not straightforward
383 // to know in which list they are on so that we can remove them. We only
384 // need to do this if we need to allocate more than one region to satisfy the
385 // current humongous allocation request. If we are only allocating one region
386 // we use the one-region region allocation code (see above), that already
387 // potentially waits for regions from the secondary free list.
388 wait_while_free_regions_coming();
389 append_secondary_free_list_if_not_empty_with_lock();
390
391 // Policy: Try only empty regions (i.e. already committed first). Maybe we
392 // are lucky enough to find some.
393 first = _hrm.find_contiguous_only_empty(obj_regions);
394 if (first != G1_NO_HRM_INDEX) {
395 _hrm.allocate_free_regions_starting_at(first, obj_regions);
396 }
397 }
398
399 if (first == G1_NO_HRM_INDEX) {
400 // Policy: We could not find enough regions for the humongous object in the
401 // free list. Look through the heap to find a mix of free and uncommitted regions.
402 // If so, try expansion.
403 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
404 if (first != G1_NO_HRM_INDEX) {
405 // We found something. Make sure these regions are committed, i.e. expand
406 // the heap. Alternatively we could do a defragmentation GC.
407 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
408 word_size * HeapWordSize);
409
410 _hrm.expand_at(first, obj_regions, workers());
411 g1_policy()->record_new_heap_size(num_regions());
412
413 #ifdef ASSERT
414 for (uint i = first; i < first + obj_regions; ++i) {
415 HeapRegion* hr = region_at(i);
416 assert(hr->is_free(), "sanity");
417 assert(hr->is_empty(), "sanity");
418 assert(is_on_master_free_list(hr), "sanity");
419 }
420 #endif
421 _hrm.allocate_free_regions_starting_at(first, obj_regions);
422 } else {
423 // Policy: Potentially trigger a defragmentation GC.
424 }
425 }
426
427 HeapWord* result = NULL;
428 if (first != G1_NO_HRM_INDEX) {
429 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
430 word_size, context);
431 assert(result != NULL, "it should always return a valid result");
432
433 // A successful humongous object allocation changes the used space
434 // information of the old generation so we need to recalculate the
435 // sizes and update the jstat counters here.
436 g1mm()->update_sizes();
437 }
438
439 _verifier->verify_region_sets_optional();
440
441 return result;
442 }
443
444 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
445 assert_heap_not_locked_and_not_at_safepoint();
446 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
447
448 return attempt_allocation(word_size);
449 }
450
451 HeapWord*
452 G1CollectedHeap::mem_allocate(size_t word_size,
453 bool* gc_overhead_limit_was_exceeded) {
454 assert_heap_not_locked_and_not_at_safepoint();
455
456 if (is_humongous(word_size)) {
457 return attempt_allocation_humongous(word_size);
458 }
459 return attempt_allocation(word_size);
460 }
461
462 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
463 AllocationContext_t context) {
464 ResourceMark rm; // For retrieving the thread names in log messages.
465
466 // Make sure you read the note in attempt_allocation_humongous().
467
468 assert_heap_not_locked_and_not_at_safepoint();
469 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
470 "be called for humongous allocation requests");
471
472 // We should only get here after the first-level allocation attempt
473 // (attempt_allocation()) failed to allocate.
474
475 // We will loop until a) we manage to successfully perform the
476 // allocation or b) we successfully schedule a collection which
477 // fails to perform the allocation. b) is the only case when we'll
478 // return NULL.
479 HeapWord* result = NULL;
480 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
481 bool should_try_gc;
482 uint gc_count_before;
483
484 {
485 MutexLockerEx x(Heap_lock);
486 result = _allocator->attempt_allocation_locked(word_size, context);
487 if (result != NULL) {
488 return result;
489 }
490
491 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
492 // This is different to when only GCLocker::needs_gc() is set: try to avoid
493 // waiting because the GCLocker is active to not wait too long.
494 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
495 // No need for an ergo message here, can_expand_young_list() does this when
496 // it returns true.
497 result = _allocator->attempt_allocation_force(word_size, context);
498 if (result != NULL) {
499 return result;
500 }
501 }
502 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
503 // the GCLocker initiated GC has been performed and then retry. This includes
504 // the case when the GC Locker is not active but has not been performed.
505 should_try_gc = !GCLocker::needs_gc();
506 // Read the GC count while still holding the Heap_lock.
507 gc_count_before = total_collections();
508 }
509
510 if (should_try_gc) {
511 bool succeeded;
512 result = do_collection_pause(word_size, gc_count_before, &succeeded,
513 GCCause::_g1_inc_collection_pause);
514 if (result != NULL) {
515 assert(succeeded, "only way to get back a non-NULL result");
516 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
517 Thread::current()->name(), p2i(result));
518 return result;
519 }
520
521 if (succeeded) {
522 // We successfully scheduled a collection which failed to allocate. No
523 // point in trying to allocate further. We'll just return NULL.
524 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
525 SIZE_FORMAT " words", Thread::current()->name(), word_size);
526 return NULL;
527 }
528 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
529 Thread::current()->name(), word_size);
530 } else {
531 // Failed to schedule a collection.
532 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
533 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
534 SIZE_FORMAT " words", Thread::current()->name(), word_size);
535 return NULL;
536 }
537 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
538 // The GCLocker is either active or the GCLocker initiated
539 // GC has not yet been performed. Stall until it is and
540 // then retry the allocation.
541 GCLocker::stall_until_clear();
542 gclocker_retry_count += 1;
543 }
544
545 // We can reach here if we were unsuccessful in scheduling a
546 // collection (because another thread beat us to it) or if we were
547 // stalled due to the GC locker. In either can we should retry the
548 // allocation attempt in case another thread successfully
549 // performed a collection and reclaimed enough space. We do the
550 // first attempt (without holding the Heap_lock) here and the
551 // follow-on attempt will be at the start of the next loop
552 // iteration (after taking the Heap_lock).
553
554 result = _allocator->attempt_allocation(word_size, context);
555 if (result != NULL) {
556 return result;
557 }
558
559 // Give a warning if we seem to be looping forever.
560 if ((QueuedAllocationWarningCount > 0) &&
561 (try_count % QueuedAllocationWarningCount == 0)) {
562 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
563 Thread::current()->name(), try_count, word_size);
564 }
565 }
566
567 ShouldNotReachHere();
568 return NULL;
569 }
570
571 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
572 assert_at_safepoint(true /* should_be_vm_thread */);
573 if (_archive_allocator == NULL) {
574 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
575 }
576 }
577
578 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
579 // Allocations in archive regions cannot be of a size that would be considered
580 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
581 // may be different at archive-restore time.
582 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
583 }
584
585 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
586 assert_at_safepoint(true /* should_be_vm_thread */);
587 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
588 if (is_archive_alloc_too_large(word_size)) {
589 return NULL;
590 }
591 return _archive_allocator->archive_mem_allocate(word_size);
592 }
593
594 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
595 size_t end_alignment_in_bytes) {
596 assert_at_safepoint(true /* should_be_vm_thread */);
597 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
598
599 // Call complete_archive to do the real work, filling in the MemRegion
600 // array with the archive regions.
601 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
602 delete _archive_allocator;
603 _archive_allocator = NULL;
604 }
605
606 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
607 assert(ranges != NULL, "MemRegion array NULL");
608 assert(count != 0, "No MemRegions provided");
609 MemRegion reserved = _hrm.reserved();
610 for (size_t i = 0; i < count; i++) {
611 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
612 return false;
613 }
614 }
615 return true;
616 }
617
618 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
619 size_t count,
620 bool open) {
621 assert(!is_init_completed(), "Expect to be called at JVM init time");
622 assert(ranges != NULL, "MemRegion array NULL");
623 assert(count != 0, "No MemRegions provided");
624 MutexLockerEx x(Heap_lock);
625
626 MemRegion reserved = _hrm.reserved();
627 HeapWord* prev_last_addr = NULL;
628 HeapRegion* prev_last_region = NULL;
629
630 // Temporarily disable pretouching of heap pages. This interface is used
631 // when mmap'ing archived heap data in, so pre-touching is wasted.
632 FlagSetting fs(AlwaysPreTouch, false);
633
634 // Enable archive object checking used by G1MarkSweep. We have to let it know
635 // about each archive range, so that objects in those ranges aren't marked.
636 G1ArchiveAllocator::enable_archive_object_check();
637
638 // For each specified MemRegion range, allocate the corresponding G1
639 // regions and mark them as archive regions. We expect the ranges
640 // in ascending starting address order, without overlap.
641 for (size_t i = 0; i < count; i++) {
642 MemRegion curr_range = ranges[i];
643 HeapWord* start_address = curr_range.start();
644 size_t word_size = curr_range.word_size();
645 HeapWord* last_address = curr_range.last();
646 size_t commits = 0;
647
648 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
649 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
650 p2i(start_address), p2i(last_address));
651 guarantee(start_address > prev_last_addr,
652 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
653 p2i(start_address), p2i(prev_last_addr));
654 prev_last_addr = last_address;
655
656 // Check for ranges that start in the same G1 region in which the previous
657 // range ended, and adjust the start address so we don't try to allocate
658 // the same region again. If the current range is entirely within that
659 // region, skip it, just adjusting the recorded top.
660 HeapRegion* start_region = _hrm.addr_to_region(start_address);
661 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
662 start_address = start_region->end();
663 if (start_address > last_address) {
664 increase_used(word_size * HeapWordSize);
665 start_region->set_top(last_address + 1);
666 continue;
667 }
668 start_region->set_top(start_address);
669 curr_range = MemRegion(start_address, last_address + 1);
670 start_region = _hrm.addr_to_region(start_address);
671 }
672
673 // Perform the actual region allocation, exiting if it fails.
674 // Then note how much new space we have allocated.
675 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
676 return false;
677 }
678 increase_used(word_size * HeapWordSize);
679 if (commits != 0) {
680 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
681 HeapRegion::GrainWords * HeapWordSize * commits);
682
683 }
684
685 // Mark each G1 region touched by the range as archive, add it to
686 // the old set, and set the allocation context and top.
687 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
688 HeapRegion* last_region = _hrm.addr_to_region(last_address);
689 prev_last_region = last_region;
690
691 while (curr_region != NULL) {
692 assert(curr_region->is_empty() && !curr_region->is_pinned(),
693 "Region already in use (index %u)", curr_region->hrm_index());
694 curr_region->set_allocation_context(AllocationContext::system());
695 if (open) {
696 curr_region->set_open_archive();
697 } else {
698 curr_region->set_closed_archive();
699 }
700 _hr_printer.alloc(curr_region);
701 _old_set.add(curr_region);
702 HeapWord* top;
703 HeapRegion* next_region;
704 if (curr_region != last_region) {
705 top = curr_region->end();
706 next_region = _hrm.next_region_in_heap(curr_region);
707 } else {
708 top = last_address + 1;
709 next_region = NULL;
710 }
711 curr_region->set_top(top);
712 curr_region->set_first_dead(top);
713 curr_region->set_end_of_live(top);
714 curr_region = next_region;
715 }
716
717 // Notify mark-sweep of the archive
718 G1ArchiveAllocator::set_range_archive(curr_range, open);
719 }
720 return true;
721 }
722
723 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
724 assert(!is_init_completed(), "Expect to be called at JVM init time");
725 assert(ranges != NULL, "MemRegion array NULL");
726 assert(count != 0, "No MemRegions provided");
727 MemRegion reserved = _hrm.reserved();
728 HeapWord *prev_last_addr = NULL;
729 HeapRegion* prev_last_region = NULL;
730
731 // For each MemRegion, create filler objects, if needed, in the G1 regions
732 // that contain the address range. The address range actually within the
733 // MemRegion will not be modified. That is assumed to have been initialized
734 // elsewhere, probably via an mmap of archived heap data.
735 MutexLockerEx x(Heap_lock);
736 for (size_t i = 0; i < count; i++) {
737 HeapWord* start_address = ranges[i].start();
738 HeapWord* last_address = ranges[i].last();
739
740 assert(reserved.contains(start_address) && reserved.contains(last_address),
741 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
742 p2i(start_address), p2i(last_address));
743 assert(start_address > prev_last_addr,
744 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
745 p2i(start_address), p2i(prev_last_addr));
746
747 HeapRegion* start_region = _hrm.addr_to_region(start_address);
748 HeapRegion* last_region = _hrm.addr_to_region(last_address);
749 HeapWord* bottom_address = start_region->bottom();
750
751 // Check for a range beginning in the same region in which the
752 // previous one ended.
753 if (start_region == prev_last_region) {
754 bottom_address = prev_last_addr + 1;
755 }
756
757 // Verify that the regions were all marked as archive regions by
758 // alloc_archive_regions.
759 HeapRegion* curr_region = start_region;
760 while (curr_region != NULL) {
761 guarantee(curr_region->is_archive(),
762 "Expected archive region at index %u", curr_region->hrm_index());
763 if (curr_region != last_region) {
764 curr_region = _hrm.next_region_in_heap(curr_region);
765 } else {
766 curr_region = NULL;
767 }
768 }
769
770 prev_last_addr = last_address;
771 prev_last_region = last_region;
772
773 // Fill the memory below the allocated range with dummy object(s),
774 // if the region bottom does not match the range start, or if the previous
775 // range ended within the same G1 region, and there is a gap.
776 if (start_address != bottom_address) {
777 size_t fill_size = pointer_delta(start_address, bottom_address);
778 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
779 increase_used(fill_size * HeapWordSize);
780 }
781 }
782 }
783
784 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
785 assert_heap_not_locked_and_not_at_safepoint();
786 assert(!is_humongous(word_size), "attempt_allocation() should not "
787 "be called for humongous allocation requests");
788
789 AllocationContext_t context = AllocationContext::current();
790 HeapWord* result = _allocator->attempt_allocation(word_size, context);
791
792 if (result == NULL) {
793 result = attempt_allocation_slow(word_size, context);
794 }
795 assert_heap_not_locked();
796 if (result != NULL) {
797 dirty_young_block(result, word_size);
798 }
799 return result;
800 }
801
802 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
803 assert(!is_init_completed(), "Expect to be called at JVM init time");
804 assert(ranges != NULL, "MemRegion array NULL");
805 assert(count != 0, "No MemRegions provided");
806 MemRegion reserved = _hrm.reserved();
807 HeapWord* prev_last_addr = NULL;
808 HeapRegion* prev_last_region = NULL;
809 size_t size_used = 0;
810 size_t uncommitted_regions = 0;
811
812 // For each Memregion, free the G1 regions that constitute it, and
813 // notify mark-sweep that the range is no longer to be considered 'archive.'
814 MutexLockerEx x(Heap_lock);
815 for (size_t i = 0; i < count; i++) {
816 HeapWord* start_address = ranges[i].start();
817 HeapWord* last_address = ranges[i].last();
818
819 assert(reserved.contains(start_address) && reserved.contains(last_address),
820 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
821 p2i(start_address), p2i(last_address));
822 assert(start_address > prev_last_addr,
823 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
824 p2i(start_address), p2i(prev_last_addr));
825 size_used += ranges[i].byte_size();
826 prev_last_addr = last_address;
827
828 HeapRegion* start_region = _hrm.addr_to_region(start_address);
829 HeapRegion* last_region = _hrm.addr_to_region(last_address);
830
831 // Check for ranges that start in the same G1 region in which the previous
832 // range ended, and adjust the start address so we don't try to free
833 // the same region again. If the current range is entirely within that
834 // region, skip it.
835 if (start_region == prev_last_region) {
836 start_address = start_region->end();
837 if (start_address > last_address) {
838 continue;
839 }
840 start_region = _hrm.addr_to_region(start_address);
841 }
842 prev_last_region = last_region;
843
844 // After verifying that each region was marked as an archive region by
845 // alloc_archive_regions, set it free and empty and uncommit it.
846 HeapRegion* curr_region = start_region;
847 while (curr_region != NULL) {
848 guarantee(curr_region->is_archive(),
849 "Expected archive region at index %u", curr_region->hrm_index());
850 uint curr_index = curr_region->hrm_index();
851 _old_set.remove(curr_region);
852 curr_region->set_free();
853 curr_region->set_top(curr_region->bottom());
854 if (curr_region != last_region) {
855 curr_region = _hrm.next_region_in_heap(curr_region);
856 } else {
857 curr_region = NULL;
858 }
859 _hrm.shrink_at(curr_index, 1);
860 uncommitted_regions++;
861 }
862
863 // Notify mark-sweep that this is no longer an archive range.
864 G1ArchiveAllocator::set_range_archive(ranges[i], false);
865 }
866
867 if (uncommitted_regions != 0) {
868 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
869 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
870 }
871 decrease_used(size_used);
872 }
873
874 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
875 ResourceMark rm; // For retrieving the thread names in log messages.
876
877 // The structure of this method has a lot of similarities to
878 // attempt_allocation_slow(). The reason these two were not merged
879 // into a single one is that such a method would require several "if
880 // allocation is not humongous do this, otherwise do that"
881 // conditional paths which would obscure its flow. In fact, an early
882 // version of this code did use a unified method which was harder to
883 // follow and, as a result, it had subtle bugs that were hard to
884 // track down. So keeping these two methods separate allows each to
885 // be more readable. It will be good to keep these two in sync as
886 // much as possible.
887
888 assert_heap_not_locked_and_not_at_safepoint();
889 assert(is_humongous(word_size), "attempt_allocation_humongous() "
890 "should only be called for humongous allocations");
891
892 // Humongous objects can exhaust the heap quickly, so we should check if we
893 // need to start a marking cycle at each humongous object allocation. We do
894 // the check before we do the actual allocation. The reason for doing it
895 // before the allocation is that we avoid having to keep track of the newly
896 // allocated memory while we do a GC.
897 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
898 word_size)) {
899 collect(GCCause::_g1_humongous_allocation);
900 }
901
902 // We will loop until a) we manage to successfully perform the
903 // allocation or b) we successfully schedule a collection which
904 // fails to perform the allocation. b) is the only case when we'll
905 // return NULL.
906 HeapWord* result = NULL;
907 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
908 bool should_try_gc;
909 uint gc_count_before;
910
911
912 {
913 MutexLockerEx x(Heap_lock);
914
915 // Given that humongous objects are not allocated in young
916 // regions, we'll first try to do the allocation without doing a
917 // collection hoping that there's enough space in the heap.
918 result = humongous_obj_allocate(word_size, AllocationContext::current());
919 if (result != NULL) {
920 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
921 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
922 return result;
923 }
924
925 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
926 // the GCLocker initiated GC has been performed and then retry. This includes
927 // the case when the GC Locker is not active but has not been performed.
928 should_try_gc = !GCLocker::needs_gc();
929 // Read the GC count while still holding the Heap_lock.
930 gc_count_before = total_collections();
931 }
932
933 if (should_try_gc) {
934 bool succeeded;
935 result = do_collection_pause(word_size, gc_count_before, &succeeded,
936 GCCause::_g1_humongous_allocation);
937 if (result != NULL) {
938 assert(succeeded, "only way to get back a non-NULL result");
939 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
940 Thread::current()->name(), p2i(result));
941 return result;
942 }
943
944 if (succeeded) {
945 // We successfully scheduled a collection which failed to allocate. No
946 // point in trying to allocate further. We'll just return NULL.
947 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
948 SIZE_FORMAT " words", Thread::current()->name(), word_size);
949 return NULL;
950 }
951 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
952 Thread::current()->name(), word_size);
953 } else {
954 // Failed to schedule a collection.
955 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
956 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
957 SIZE_FORMAT " words", Thread::current()->name(), word_size);
958 return NULL;
959 }
960 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
961 // The GCLocker is either active or the GCLocker initiated
962 // GC has not yet been performed. Stall until it is and
963 // then retry the allocation.
964 GCLocker::stall_until_clear();
965 gclocker_retry_count += 1;
966 }
967
968
969 // We can reach here if we were unsuccessful in scheduling a
970 // collection (because another thread beat us to it) or if we were
971 // stalled due to the GC locker. In either can we should retry the
972 // allocation attempt in case another thread successfully
973 // performed a collection and reclaimed enough space.
974 // Humongous object allocation always needs a lock, so we wait for the retry
975 // in the next iteration of the loop, unlike for the regular iteration case.
976 // Give a warning if we seem to be looping forever.
977
978 if ((QueuedAllocationWarningCount > 0) &&
979 (try_count % QueuedAllocationWarningCount == 0)) {
980 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
981 Thread::current()->name(), try_count, word_size);
982 }
983 }
984
985 ShouldNotReachHere();
986 return NULL;
987 }
988
989 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
990 AllocationContext_t context,
991 bool expect_null_mutator_alloc_region) {
992 assert_at_safepoint(true /* should_be_vm_thread */);
993 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
994 "the current alloc region was unexpectedly found to be non-NULL");
995
996 if (!is_humongous(word_size)) {
997 return _allocator->attempt_allocation_locked(word_size, context);
998 } else {
999 HeapWord* result = humongous_obj_allocate(word_size, context);
1000 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1001 collector_state()->set_initiate_conc_mark_if_possible(true);
1002 }
1003 return result;
1004 }
1005
1006 ShouldNotReachHere();
1007 }
1008
1009 class PostCompactionPrinterClosure: public HeapRegionClosure {
1010 private:
1011 G1HRPrinter* _hr_printer;
1012 public:
1013 bool do_heap_region(HeapRegion* hr) {
1014 assert(!hr->is_young(), "not expecting to find young regions");
1015 _hr_printer->post_compaction(hr);
1016 return false;
1017 }
1018
1019 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1020 : _hr_printer(hr_printer) { }
1021 };
1022
1023 void G1CollectedHeap::print_hrm_post_compaction() {
1024 if (_hr_printer.is_active()) {
1025 PostCompactionPrinterClosure cl(hr_printer());
1026 heap_region_iterate(&cl);
1027 }
1028 }
1029
1030 void G1CollectedHeap::abort_concurrent_cycle() {
1031 // Note: When we have a more flexible GC logging framework that
1032 // allows us to add optional attributes to a GC log record we
1033 // could consider timing and reporting how long we wait in the
1034 // following two methods.
1035 wait_while_free_regions_coming();
1036 // If we start the compaction before the CM threads finish
1037 // scanning the root regions we might trip them over as we'll
1038 // be moving objects / updating references. So let's wait until
1039 // they are done. By telling them to abort, they should complete
1040 // early.
1041 _cm->root_regions()->abort();
1042 _cm->root_regions()->wait_until_scan_finished();
1043 append_secondary_free_list_if_not_empty_with_lock();
1044
1045 // Disable discovery and empty the discovered lists
1046 // for the CM ref processor.
1047 ref_processor_cm()->disable_discovery();
1048 ref_processor_cm()->abandon_partial_discovery();
1049 ref_processor_cm()->verify_no_references_recorded();
1050
1051 // Abandon current iterations of concurrent marking and concurrent
1052 // refinement, if any are in progress.
1053 concurrent_mark()->abort();
1054 }
1055
1056 void G1CollectedHeap::prepare_heap_for_full_collection() {
1057 // Make sure we'll choose a new allocation region afterwards.
1058 _allocator->release_mutator_alloc_region();
1059 _allocator->abandon_gc_alloc_regions();
1060 g1_rem_set()->cleanupHRRS();
1061
1062 // We may have added regions to the current incremental collection
1063 // set between the last GC or pause and now. We need to clear the
1064 // incremental collection set and then start rebuilding it afresh
1065 // after this full GC.
1066 abandon_collection_set(collection_set());
1067
1068 tear_down_region_sets(false /* free_list_only */);
1069 collector_state()->set_gcs_are_young(true);
1070 }
1071
1072 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1073 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1074 assert(used() == recalculate_used(), "Should be equal");
1075 _verifier->verify_region_sets_optional();
1076 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1077 _verifier->check_bitmaps("Full GC Start");
1078 }
1079
1080 void G1CollectedHeap::prepare_heap_for_mutators() {
1081 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1082 ClassLoaderDataGraph::purge();
1083 MetaspaceAux::verify_metrics();
1084
1085 // Prepare heap for normal collections.
1086 assert(num_free_regions() == 0, "we should not have added any free regions");
1087 rebuild_region_sets(false /* free_list_only */);
1088 abort_refinement();
1089 resize_if_necessary_after_full_collection();
1090
1091 // Rebuild the strong code root lists for each region
1092 rebuild_strong_code_roots();
1093
1094 // Start a new incremental collection set for the next pause
1095 start_new_collection_set();
1096
1097 _allocator->init_mutator_alloc_region();
1098
1099 // Post collection state updates.
1100 MetaspaceGC::compute_new_size();
1101 }
1102
1103 void G1CollectedHeap::abort_refinement() {
1104 if (_hot_card_cache->use_cache()) {
1105 _hot_card_cache->reset_hot_cache();
1106 }
1107
1108 // Discard all remembered set updates.
1109 JavaThread::dirty_card_queue_set().abandon_logs();
1110 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1111 }
1112
1113 void G1CollectedHeap::verify_after_full_collection() {
1114 check_gc_time_stamps();
1115 _hrm.verify_optional();
1116 _verifier->verify_region_sets_optional();
1117 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1118 // Clear the previous marking bitmap, if needed for bitmap verification.
1119 // Note we cannot do this when we clear the next marking bitmap in
1120 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1121 // objects marked during a full GC against the previous bitmap.
1122 // But we need to clear it before calling check_bitmaps below since
1123 // the full GC has compacted objects and updated TAMS but not updated
1124 // the prev bitmap.
1125 if (G1VerifyBitmaps) {
1126 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1127 _cm->clear_prev_bitmap(workers());
1128 }
1129 _verifier->check_bitmaps("Full GC End");
1130
1131 // At this point there should be no regions in the
1132 // entire heap tagged as young.
1133 assert(check_young_list_empty(), "young list should be empty at this point");
1134
1135 // Note: since we've just done a full GC, concurrent
1136 // marking is no longer active. Therefore we need not
1137 // re-enable reference discovery for the CM ref processor.
1138 // That will be done at the start of the next marking cycle.
1139 // We also know that the STW processor should no longer
1140 // discover any new references.
1141 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1142 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1143 ref_processor_stw()->verify_no_references_recorded();
1144 ref_processor_cm()->verify_no_references_recorded();
1145 }
1146
1147 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1148 // Post collection logging.
1149 // We should do this after we potentially resize the heap so
1150 // that all the COMMIT / UNCOMMIT events are generated before
1151 // the compaction events.
1152 print_hrm_post_compaction();
1153 heap_transition->print();
1154 print_heap_after_gc();
1155 print_heap_regions();
1156 #ifdef TRACESPINNING
1157 ParallelTaskTerminator::print_termination_counts();
1158 #endif
1159 }
1160
1161 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1162 bool clear_all_soft_refs) {
1163 assert_at_safepoint(true /* should_be_vm_thread */);
1164
1165 if (GCLocker::check_active_before_gc()) {
1166 // Full GC was not completed.
1167 return false;
1168 }
1169
1170 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1171 collector_policy()->should_clear_all_soft_refs();
1172
1173 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1174 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1175
1176 collector.prepare_collection();
1177 collector.collect();
1178 collector.complete_collection();
1179
1180 // Full collection was successfully completed.
1181 return true;
1182 }
1183
1184 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1185 // Currently, there is no facility in the do_full_collection(bool) API to notify
1186 // the caller that the collection did not succeed (e.g., because it was locked
1187 // out by the GC locker). So, right now, we'll ignore the return value.
1188 bool dummy = do_full_collection(true, /* explicit_gc */
1189 clear_all_soft_refs);
1190 }
1191
1192 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1193 // Capacity, free and used after the GC counted as full regions to
1194 // include the waste in the following calculations.
1195 const size_t capacity_after_gc = capacity();
1196 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1197
1198 // This is enforced in arguments.cpp.
1199 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1200 "otherwise the code below doesn't make sense");
1201
1202 // We don't have floating point command-line arguments
1203 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1204 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1205 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1206 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1207
1208 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1209 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1210
1211 // We have to be careful here as these two calculations can overflow
1212 // 32-bit size_t's.
1213 double used_after_gc_d = (double) used_after_gc;
1214 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1215 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1216
1217 // Let's make sure that they are both under the max heap size, which
1218 // by default will make them fit into a size_t.
1219 double desired_capacity_upper_bound = (double) max_heap_size;
1220 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1221 desired_capacity_upper_bound);
1222 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1223 desired_capacity_upper_bound);
1224
1225 // We can now safely turn them into size_t's.
1226 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1227 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1228
1229 // This assert only makes sense here, before we adjust them
1230 // with respect to the min and max heap size.
1231 assert(minimum_desired_capacity <= maximum_desired_capacity,
1232 "minimum_desired_capacity = " SIZE_FORMAT ", "
1233 "maximum_desired_capacity = " SIZE_FORMAT,
1234 minimum_desired_capacity, maximum_desired_capacity);
1235
1236 // Should not be greater than the heap max size. No need to adjust
1237 // it with respect to the heap min size as it's a lower bound (i.e.,
1238 // we'll try to make the capacity larger than it, not smaller).
1239 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1240 // Should not be less than the heap min size. No need to adjust it
1241 // with respect to the heap max size as it's an upper bound (i.e.,
1242 // we'll try to make the capacity smaller than it, not greater).
1243 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1244
1245 if (capacity_after_gc < minimum_desired_capacity) {
1246 // Don't expand unless it's significant
1247 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1248
1249 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1250 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1251 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1252 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1253
1254 expand(expand_bytes, _workers);
1255
1256 // No expansion, now see if we want to shrink
1257 } else if (capacity_after_gc > maximum_desired_capacity) {
1258 // Capacity too large, compute shrinking size
1259 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1260
1261 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1262 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1263 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1264 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1265
1266 shrink(shrink_bytes);
1267 }
1268 }
1269
1270 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1271 AllocationContext_t context,
1272 bool do_gc,
1273 bool clear_all_soft_refs,
1274 bool expect_null_mutator_alloc_region,
1275 bool* gc_succeeded) {
1276 *gc_succeeded = true;
1277 // Let's attempt the allocation first.
1278 HeapWord* result =
1279 attempt_allocation_at_safepoint(word_size,
1280 context,
1281 expect_null_mutator_alloc_region);
1282 if (result != NULL) {
1283 return result;
1284 }
1285
1286 // In a G1 heap, we're supposed to keep allocation from failing by
1287 // incremental pauses. Therefore, at least for now, we'll favor
1288 // expansion over collection. (This might change in the future if we can
1289 // do something smarter than full collection to satisfy a failed alloc.)
1290 result = expand_and_allocate(word_size, context);
1291 if (result != NULL) {
1292 return result;
1293 }
1294
1295 if (do_gc) {
1296 // Expansion didn't work, we'll try to do a Full GC.
1297 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1298 clear_all_soft_refs);
1299 }
1300
1301 return NULL;
1302 }
1303
1304 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1305 AllocationContext_t context,
1306 bool* succeeded) {
1307 assert_at_safepoint(true /* should_be_vm_thread */);
1308
1309 // Attempts to allocate followed by Full GC.
1310 HeapWord* result =
1311 satisfy_failed_allocation_helper(word_size,
1312 context,
1313 true, /* do_gc */
1314 false, /* clear_all_soft_refs */
1315 false, /* expect_null_mutator_alloc_region */
1316 succeeded);
1317
1318 if (result != NULL || !*succeeded) {
1319 return result;
1320 }
1321
1322 // Attempts to allocate followed by Full GC that will collect all soft references.
1323 result = satisfy_failed_allocation_helper(word_size,
1324 context,
1325 true, /* do_gc */
1326 true, /* clear_all_soft_refs */
1327 true, /* expect_null_mutator_alloc_region */
1328 succeeded);
1329
1330 if (result != NULL || !*succeeded) {
1331 return result;
1332 }
1333
1334 // Attempts to allocate, no GC
1335 result = satisfy_failed_allocation_helper(word_size,
1336 context,
1337 false, /* do_gc */
1338 false, /* clear_all_soft_refs */
1339 true, /* expect_null_mutator_alloc_region */
1340 succeeded);
1341
1342 if (result != NULL) {
1343 return result;
1344 }
1345
1346 assert(!collector_policy()->should_clear_all_soft_refs(),
1347 "Flag should have been handled and cleared prior to this point");
1348
1349 // What else? We might try synchronous finalization later. If the total
1350 // space available is large enough for the allocation, then a more
1351 // complete compaction phase than we've tried so far might be
1352 // appropriate.
1353 return NULL;
1354 }
1355
1356 // Attempting to expand the heap sufficiently
1357 // to support an allocation of the given "word_size". If
1358 // successful, perform the allocation and return the address of the
1359 // allocated block, or else "NULL".
1360
1361 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1362 assert_at_safepoint(true /* should_be_vm_thread */);
1363
1364 _verifier->verify_region_sets_optional();
1365
1366 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1367 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1368 word_size * HeapWordSize);
1369
1370
1371 if (expand(expand_bytes, _workers)) {
1372 _hrm.verify_optional();
1373 _verifier->verify_region_sets_optional();
1374 return attempt_allocation_at_safepoint(word_size,
1375 context,
1376 false /* expect_null_mutator_alloc_region */);
1377 }
1378 return NULL;
1379 }
1380
1381 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1382 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1383 aligned_expand_bytes = align_up(aligned_expand_bytes,
1384 HeapRegion::GrainBytes);
1385
1386 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1387 expand_bytes, aligned_expand_bytes);
1388
1389 if (is_maximal_no_gc()) {
1390 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1391 return false;
1392 }
1393
1394 double expand_heap_start_time_sec = os::elapsedTime();
1395 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1396 assert(regions_to_expand > 0, "Must expand by at least one region");
1397
1398 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1399 if (expand_time_ms != NULL) {
1400 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1401 }
1402
1403 if (expanded_by > 0) {
1404 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1405 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1406 g1_policy()->record_new_heap_size(num_regions());
1407 } else {
1408 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1409
1410 // The expansion of the virtual storage space was unsuccessful.
1411 // Let's see if it was because we ran out of swap.
1412 if (G1ExitOnExpansionFailure &&
1413 _hrm.available() >= regions_to_expand) {
1414 // We had head room...
1415 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1416 }
1417 }
1418 return regions_to_expand > 0;
1419 }
1420
1421 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1422 size_t aligned_shrink_bytes =
1423 ReservedSpace::page_align_size_down(shrink_bytes);
1424 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1425 HeapRegion::GrainBytes);
1426 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1427
1428 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1429 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1430
1431
1432 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",
1433 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1434 if (num_regions_removed > 0) {
1435 g1_policy()->record_new_heap_size(num_regions());
1436 } else {
1437 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1438 }
1439 }
1440
1441 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1442 _verifier->verify_region_sets_optional();
1443
1444 // We should only reach here at the end of a Full GC which means we
1445 // should not not be holding to any GC alloc regions. The method
1446 // below will make sure of that and do any remaining clean up.
1447 _allocator->abandon_gc_alloc_regions();
1448
1449 // Instead of tearing down / rebuilding the free lists here, we
1450 // could instead use the remove_all_pending() method on free_list to
1451 // remove only the ones that we need to remove.
1452 tear_down_region_sets(true /* free_list_only */);
1453 shrink_helper(shrink_bytes);
1454 rebuild_region_sets(true /* free_list_only */);
1455
1456 _hrm.verify_optional();
1457 _verifier->verify_region_sets_optional();
1458 }
1459
1460 // Public methods.
1461
1462 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1463 CollectedHeap(),
1464 _young_gen_sampling_thread(NULL),
1465 _collector_policy(collector_policy),
1466 _memory_manager("G1 Young Generation", "end of minor GC"),
1467 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1468 _eden_pool(NULL),
1469 _survivor_pool(NULL),
1470 _old_pool(NULL),
1471 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1472 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1473 _g1_policy(create_g1_policy(_gc_timer_stw)),
1474 _collection_set(this, _g1_policy),
1475 _dirty_card_queue_set(false),
1476 _is_alive_closure_cm(this),
1477 _is_alive_closure_stw(this),
1478 _ref_processor_cm(NULL),
1479 _ref_processor_stw(NULL),
1480 _bot(NULL),
1481 _hot_card_cache(NULL),
1482 _g1_rem_set(NULL),
1483 _cr(NULL),
1484 _g1mm(NULL),
1485 _preserved_marks_set(true /* in_c_heap */),
1486 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1487 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1488 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1489 _humongous_reclaim_candidates(),
1490 _has_humongous_reclaim_candidates(false),
1491 _archive_allocator(NULL),
1492 _free_regions_coming(false),
1493 _gc_time_stamp(0),
1494 _summary_bytes_used(0),
1495 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1496 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1497 _expand_heap_after_alloc_failure(true),
1498 _old_marking_cycles_started(0),
1499 _old_marking_cycles_completed(0),
1500 _in_cset_fast_test() {
1501
1502 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1503 /* are_GC_task_threads */true,
1504 /* are_ConcurrentGC_threads */false);
1505 _workers->initialize_workers();
1506 _verifier = new G1HeapVerifier(this);
1507
1508 _allocator = G1Allocator::create_allocator(this);
1509
1510 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1511
1512 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1513
1514 // Override the default _filler_array_max_size so that no humongous filler
1515 // objects are created.
1516 _filler_array_max_size = _humongous_object_threshold_in_words;
1517
1518 uint n_queues = ParallelGCThreads;
1519 _task_queues = new RefToScanQueueSet(n_queues);
1520
1521 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1522
1523 for (uint i = 0; i < n_queues; i++) {
1524 RefToScanQueue* q = new RefToScanQueue();
1525 q->initialize();
1526 _task_queues->register_queue(i, q);
1527 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1528 }
1529
1530 // Initialize the G1EvacuationFailureALot counters and flags.
1531 NOT_PRODUCT(reset_evacuation_should_fail();)
1532
1533 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1534 }
1535
1536 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1537 size_t size,
1538 size_t translation_factor) {
1539 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1540 // Allocate a new reserved space, preferring to use large pages.
1541 ReservedSpace rs(size, preferred_page_size);
1542 G1RegionToSpaceMapper* result =
1543 G1RegionToSpaceMapper::create_mapper(rs,
1544 size,
1545 rs.alignment(),
1546 HeapRegion::GrainBytes,
1547 translation_factor,
1548 mtGC);
1549
1550 os::trace_page_sizes_for_requested_size(description,
1551 size,
1552 preferred_page_size,
1553 rs.alignment(),
1554 rs.base(),
1555 rs.size());
1556
1557 return result;
1558 }
1559
1560 jint G1CollectedHeap::initialize_concurrent_refinement() {
1561 jint ecode = JNI_OK;
1562 _cr = G1ConcurrentRefine::create(&ecode);
1563 return ecode;
1564 }
1565
1566 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1567 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1568 if (_young_gen_sampling_thread->osthread() == NULL) {
1569 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1570 return JNI_ENOMEM;
1571 }
1572 return JNI_OK;
1573 }
1574
1575 jint G1CollectedHeap::initialize() {
1576 os::enable_vtime();
1577
1578 // Necessary to satisfy locking discipline assertions.
1579
1580 MutexLocker x(Heap_lock);
1581
1582 // While there are no constraints in the GC code that HeapWordSize
1583 // be any particular value, there are multiple other areas in the
1584 // system which believe this to be true (e.g. oop->object_size in some
1585 // cases incorrectly returns the size in wordSize units rather than
1586 // HeapWordSize).
1587 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1588
1589 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1590 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1591 size_t heap_alignment = collector_policy()->heap_alignment();
1592
1593 // Ensure that the sizes are properly aligned.
1594 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1595 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1596 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1597
1598 // Reserve the maximum.
1599
1600 // When compressed oops are enabled, the preferred heap base
1601 // is calculated by subtracting the requested size from the
1602 // 32Gb boundary and using the result as the base address for
1603 // heap reservation. If the requested size is not aligned to
1604 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1605 // into the ReservedHeapSpace constructor) then the actual
1606 // base of the reserved heap may end up differing from the
1607 // address that was requested (i.e. the preferred heap base).
1608 // If this happens then we could end up using a non-optimal
1609 // compressed oops mode.
1610
1611 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1612 heap_alignment);
1613
1614 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1615
1616 // Create the barrier set for the entire reserved region.
1617 G1SATBCardTableLoggingModRefBS* bs
1618 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1619 bs->initialize();
1620 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1621 set_barrier_set(bs);
1622
1623 // Create the hot card cache.
1624 _hot_card_cache = new G1HotCardCache(this);
1625
1626 // Carve out the G1 part of the heap.
1627 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1628 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1629 G1RegionToSpaceMapper* heap_storage =
1630 G1RegionToSpaceMapper::create_mapper(g1_rs,
1631 g1_rs.size(),
1632 page_size,
1633 HeapRegion::GrainBytes,
1634 1,
1635 mtJavaHeap);
1636 os::trace_page_sizes("Heap",
1637 collector_policy()->min_heap_byte_size(),
1638 max_byte_size,
1639 page_size,
1640 heap_rs.base(),
1641 heap_rs.size());
1642 heap_storage->set_mapping_changed_listener(&_listener);
1643
1644 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1645 G1RegionToSpaceMapper* bot_storage =
1646 create_aux_memory_mapper("Block Offset Table",
1647 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1648 G1BlockOffsetTable::heap_map_factor());
1649
1650 G1RegionToSpaceMapper* cardtable_storage =
1651 create_aux_memory_mapper("Card Table",
1652 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1653 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1654
1655 G1RegionToSpaceMapper* card_counts_storage =
1656 create_aux_memory_mapper("Card Counts Table",
1657 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1658 G1CardCounts::heap_map_factor());
1659
1660 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1661 G1RegionToSpaceMapper* prev_bitmap_storage =
1662 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1663 G1RegionToSpaceMapper* next_bitmap_storage =
1664 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1665
1666 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1667 g1_barrier_set()->initialize(cardtable_storage);
1668 // Do later initialization work for concurrent refinement.
1669 _hot_card_cache->initialize(card_counts_storage);
1670
1671 // 6843694 - ensure that the maximum region index can fit
1672 // in the remembered set structures.
1673 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1674 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1675
1676 // Also create a G1 rem set.
1677 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1678 _g1_rem_set->initialize(max_capacity(), max_regions());
1679
1680 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1681 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1682 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1683 "too many cards per region");
1684
1685 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1686
1687 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1688
1689 {
1690 HeapWord* start = _hrm.reserved().start();
1691 HeapWord* end = _hrm.reserved().end();
1692 size_t granularity = HeapRegion::GrainBytes;
1693
1694 _in_cset_fast_test.initialize(start, end, granularity);
1695 _humongous_reclaim_candidates.initialize(start, end, granularity);
1696 }
1697
1698 // Create the G1ConcurrentMark data structure and thread.
1699 // (Must do this late, so that "max_regions" is defined.)
1700 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1701 if (_cm == NULL || !_cm->completed_initialization()) {
1702 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1703 return JNI_ENOMEM;
1704 }
1705 _cmThread = _cm->cm_thread();
1706
1707 // Now expand into the initial heap size.
1708 if (!expand(init_byte_size, _workers)) {
1709 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1710 return JNI_ENOMEM;
1711 }
1712
1713 // Perform any initialization actions delegated to the policy.
1714 g1_policy()->init(this, &_collection_set);
1715
1716 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1717 SATB_Q_FL_lock,
1718 G1SATBProcessCompletedThreshold,
1719 Shared_SATB_Q_lock);
1720
1721 jint ecode = initialize_concurrent_refinement();
1722 if (ecode != JNI_OK) {
1723 return ecode;
1724 }
1725
1726 ecode = initialize_young_gen_sampling_thread();
1727 if (ecode != JNI_OK) {
1728 return ecode;
1729 }
1730
1731 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1732 DirtyCardQ_FL_lock,
1733 (int)concurrent_refine()->yellow_zone(),
1734 (int)concurrent_refine()->red_zone(),
1735 Shared_DirtyCardQ_lock,
1736 NULL, // fl_owner
1737 true); // init_free_ids
1738
1739 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1740 DirtyCardQ_FL_lock,
1741 -1, // never trigger processing
1742 -1, // no limit on length
1743 Shared_DirtyCardQ_lock,
1744 &JavaThread::dirty_card_queue_set());
1745
1746 // Here we allocate the dummy HeapRegion that is required by the
1747 // G1AllocRegion class.
1748 HeapRegion* dummy_region = _hrm.get_dummy_region();
1749
1750 // We'll re-use the same region whether the alloc region will
1751 // require BOT updates or not and, if it doesn't, then a non-young
1752 // region will complain that it cannot support allocations without
1753 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1754 dummy_region->set_eden();
1755 // Make sure it's full.
1756 dummy_region->set_top(dummy_region->end());
1757 G1AllocRegion::setup(this, dummy_region);
1758
1759 _allocator->init_mutator_alloc_region();
1760
1761 // Do create of the monitoring and management support so that
1762 // values in the heap have been properly initialized.
1763 _g1mm = new G1MonitoringSupport(this);
1764
1765 G1StringDedup::initialize();
1766
1767 _preserved_marks_set.init(ParallelGCThreads);
1768
1769 _collection_set.initialize(max_regions());
1770
1771 return JNI_OK;
1772 }
1773
1774 void G1CollectedHeap::initialize_serviceability() {
1775 _eden_pool = new G1EdenPool(this);
1776 _survivor_pool = new G1SurvivorPool(this);
1777 _old_pool = new G1OldGenPool(this);
1778
1779 _full_gc_memory_manager.add_pool(_eden_pool);
1780 _full_gc_memory_manager.add_pool(_survivor_pool);
1781 _full_gc_memory_manager.add_pool(_old_pool);
1782
1783 _memory_manager.add_pool(_eden_pool);
1784 _memory_manager.add_pool(_survivor_pool);
1785
1786 }
1787
1788 void G1CollectedHeap::stop() {
1789 // Stop all concurrent threads. We do this to make sure these threads
1790 // do not continue to execute and access resources (e.g. logging)
1791 // that are destroyed during shutdown.
1792 _cr->stop();
1793 _young_gen_sampling_thread->stop();
1794 _cmThread->stop();
1795 if (G1StringDedup::is_enabled()) {
1796 G1StringDedup::stop();
1797 }
1798 }
1799
1800 void G1CollectedHeap::safepoint_synchronize_begin() {
1801 SuspendibleThreadSet::synchronize();
1802 }
1803
1804 void G1CollectedHeap::safepoint_synchronize_end() {
1805 SuspendibleThreadSet::desynchronize();
1806 }
1807
1808 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1809 return HeapRegion::max_region_size();
1810 }
1811
1812 void G1CollectedHeap::post_initialize() {
1813 CollectedHeap::post_initialize();
1814 ref_processing_init();
1815 }
1816
1817 void G1CollectedHeap::ref_processing_init() {
1818 // Reference processing in G1 currently works as follows:
1819 //
1820 // * There are two reference processor instances. One is
1821 // used to record and process discovered references
1822 // during concurrent marking; the other is used to
1823 // record and process references during STW pauses
1824 // (both full and incremental).
1825 // * Both ref processors need to 'span' the entire heap as
1826 // the regions in the collection set may be dotted around.
1827 //
1828 // * For the concurrent marking ref processor:
1829 // * Reference discovery is enabled at initial marking.
1830 // * Reference discovery is disabled and the discovered
1831 // references processed etc during remarking.
1832 // * Reference discovery is MT (see below).
1833 // * Reference discovery requires a barrier (see below).
1834 // * Reference processing may or may not be MT
1835 // (depending on the value of ParallelRefProcEnabled
1836 // and ParallelGCThreads).
1837 // * A full GC disables reference discovery by the CM
1838 // ref processor and abandons any entries on it's
1839 // discovered lists.
1840 //
1841 // * For the STW processor:
1842 // * Non MT discovery is enabled at the start of a full GC.
1843 // * Processing and enqueueing during a full GC is non-MT.
1844 // * During a full GC, references are processed after marking.
1845 //
1846 // * Discovery (may or may not be MT) is enabled at the start
1847 // of an incremental evacuation pause.
1848 // * References are processed near the end of a STW evacuation pause.
1849 // * For both types of GC:
1850 // * Discovery is atomic - i.e. not concurrent.
1851 // * Reference discovery will not need a barrier.
1852
1853 MemRegion mr = reserved_region();
1854
1855 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1856
1857 // Concurrent Mark ref processor
1858 _ref_processor_cm =
1859 new ReferenceProcessor(mr, // span
1860 mt_processing,
1861 // mt processing
1862 ParallelGCThreads,
1863 // degree of mt processing
1864 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1865 // mt discovery
1866 MAX2(ParallelGCThreads, ConcGCThreads),
1867 // degree of mt discovery
1868 false,
1869 // Reference discovery is not atomic
1870 &_is_alive_closure_cm);
1871 // is alive closure
1872 // (for efficiency/performance)
1873
1874 // STW ref processor
1875 _ref_processor_stw =
1876 new ReferenceProcessor(mr, // span
1877 mt_processing,
1878 // mt processing
1879 ParallelGCThreads,
1880 // degree of mt processing
1881 (ParallelGCThreads > 1),
1882 // mt discovery
1883 ParallelGCThreads,
1884 // degree of mt discovery
1885 true,
1886 // Reference discovery is atomic
1887 &_is_alive_closure_stw);
1888 // is alive closure
1889 // (for efficiency/performance)
1890 }
1891
1892 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1893 return _collector_policy;
1894 }
1895
1896 size_t G1CollectedHeap::capacity() const {
1897 return _hrm.length() * HeapRegion::GrainBytes;
1898 }
1899
1900 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1901 return _hrm.total_free_bytes();
1902 }
1903
1904 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1905 hr->reset_gc_time_stamp();
1906 }
1907
1908 #ifndef PRODUCT
1909
1910 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1911 private:
1912 unsigned _gc_time_stamp;
1913 bool _failures;
1914
1915 public:
1916 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1917 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1918
1919 virtual bool do_heap_region(HeapRegion* hr) {
1920 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1921 if (_gc_time_stamp != region_gc_time_stamp) {
1922 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1923 region_gc_time_stamp, _gc_time_stamp);
1924 _failures = true;
1925 }
1926 return false;
1927 }
1928
1929 bool failures() { return _failures; }
1930 };
1931
1932 void G1CollectedHeap::check_gc_time_stamps() {
1933 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1934 heap_region_iterate(&cl);
1935 guarantee(!cl.failures(), "all GC time stamps should have been reset");
1936 }
1937 #endif // PRODUCT
1938
1939 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1940 _hot_card_cache->drain(cl, worker_i);
1941 }
1942
1943 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1944 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1945 size_t n_completed_buffers = 0;
1946 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1947 n_completed_buffers++;
1948 }
1949 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1950 dcqs.clear_n_completed_buffers();
1951 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1952 }
1953
1954 // Computes the sum of the storage used by the various regions.
1955 size_t G1CollectedHeap::used() const {
1956 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1957 if (_archive_allocator != NULL) {
1958 result += _archive_allocator->used();
1959 }
1960 return result;
1961 }
1962
1963 size_t G1CollectedHeap::used_unlocked() const {
1964 return _summary_bytes_used;
1965 }
1966
1967 class SumUsedClosure: public HeapRegionClosure {
1968 size_t _used;
1969 public:
1970 SumUsedClosure() : _used(0) {}
1971 bool do_heap_region(HeapRegion* r) {
1972 _used += r->used();
1973 return false;
1974 }
1975 size_t result() { return _used; }
1976 };
1977
1978 size_t G1CollectedHeap::recalculate_used() const {
1979 double recalculate_used_start = os::elapsedTime();
1980
1981 SumUsedClosure blk;
1982 heap_region_iterate(&blk);
1983
1984 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1985 return blk.result();
1986 }
1987
1988 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1989 switch (cause) {
1990 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1991 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1992 case GCCause::_wb_conc_mark: return true;
1993 default : return false;
1994 }
1995 }
1996
1997 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1998 switch (cause) {
1999 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2000 case GCCause::_g1_humongous_allocation: return true;
2001 default: return is_user_requested_concurrent_full_gc(cause);
2002 }
2003 }
2004
2005 #ifndef PRODUCT
2006 void G1CollectedHeap::allocate_dummy_regions() {
2007 // Let's fill up most of the region
2008 size_t word_size = HeapRegion::GrainWords - 1024;
2009 // And as a result the region we'll allocate will be humongous.
2010 guarantee(is_humongous(word_size), "sanity");
2011
2012 // _filler_array_max_size is set to humongous object threshold
2013 // but temporarily change it to use CollectedHeap::fill_with_object().
2014 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2015
2016 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2017 // Let's use the existing mechanism for the allocation
2018 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2019 AllocationContext::system());
2020 if (dummy_obj != NULL) {
2021 MemRegion mr(dummy_obj, word_size);
2022 CollectedHeap::fill_with_object(mr);
2023 } else {
2024 // If we can't allocate once, we probably cannot allocate
2025 // again. Let's get out of the loop.
2026 break;
2027 }
2028 }
2029 }
2030 #endif // !PRODUCT
2031
2032 void G1CollectedHeap::increment_old_marking_cycles_started() {
2033 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2034 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2035 "Wrong marking cycle count (started: %d, completed: %d)",
2036 _old_marking_cycles_started, _old_marking_cycles_completed);
2037
2038 _old_marking_cycles_started++;
2039 }
2040
2041 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2042 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2043
2044 // We assume that if concurrent == true, then the caller is a
2045 // concurrent thread that was joined the Suspendible Thread
2046 // Set. If there's ever a cheap way to check this, we should add an
2047 // assert here.
2048
2049 // Given that this method is called at the end of a Full GC or of a
2050 // concurrent cycle, and those can be nested (i.e., a Full GC can
2051 // interrupt a concurrent cycle), the number of full collections
2052 // completed should be either one (in the case where there was no
2053 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2054 // behind the number of full collections started.
2055
2056 // This is the case for the inner caller, i.e. a Full GC.
2057 assert(concurrent ||
2058 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2059 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2060 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2061 "is inconsistent with _old_marking_cycles_completed = %u",
2062 _old_marking_cycles_started, _old_marking_cycles_completed);
2063
2064 // This is the case for the outer caller, i.e. the concurrent cycle.
2065 assert(!concurrent ||
2066 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2067 "for outer caller (concurrent cycle): "
2068 "_old_marking_cycles_started = %u "
2069 "is inconsistent with _old_marking_cycles_completed = %u",
2070 _old_marking_cycles_started, _old_marking_cycles_completed);
2071
2072 _old_marking_cycles_completed += 1;
2073
2074 // We need to clear the "in_progress" flag in the CM thread before
2075 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2076 // is set) so that if a waiter requests another System.gc() it doesn't
2077 // incorrectly see that a marking cycle is still in progress.
2078 if (concurrent) {
2079 _cmThread->set_idle();
2080 }
2081
2082 // This notify_all() will ensure that a thread that called
2083 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2084 // and it's waiting for a full GC to finish will be woken up. It is
2085 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2086 FullGCCount_lock->notify_all();
2087 }
2088
2089 void G1CollectedHeap::collect(GCCause::Cause cause) {
2090 assert_heap_not_locked();
2091
2092 uint gc_count_before;
2093 uint old_marking_count_before;
2094 uint full_gc_count_before;
2095 bool retry_gc;
2096
2097 do {
2098 retry_gc = false;
2099
2100 {
2101 MutexLocker ml(Heap_lock);
2102
2103 // Read the GC count while holding the Heap_lock
2104 gc_count_before = total_collections();
2105 full_gc_count_before = total_full_collections();
2106 old_marking_count_before = _old_marking_cycles_started;
2107 }
2108
2109 if (should_do_concurrent_full_gc(cause)) {
2110 // Schedule an initial-mark evacuation pause that will start a
2111 // concurrent cycle. We're setting word_size to 0 which means that
2112 // we are not requesting a post-GC allocation.
2113 VM_G1CollectForAllocation op(0, /* word_size */
2114 gc_count_before,
2115 cause,
2116 true, /* should_initiate_conc_mark */
2117 g1_policy()->max_pause_time_ms(),
2118 AllocationContext::current());
2119 VMThread::execute(&op);
2120 if (!op.pause_succeeded()) {
2121 if (old_marking_count_before == _old_marking_cycles_started) {
2122 retry_gc = op.should_retry_gc();
2123 } else {
2124 // A Full GC happened while we were trying to schedule the
2125 // initial-mark GC. No point in starting a new cycle given
2126 // that the whole heap was collected anyway.
2127 }
2128
2129 if (retry_gc) {
2130 if (GCLocker::is_active_and_needs_gc()) {
2131 GCLocker::stall_until_clear();
2132 }
2133 }
2134 }
2135 } else {
2136 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2137 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2138
2139 // Schedule a standard evacuation pause. We're setting word_size
2140 // to 0 which means that we are not requesting a post-GC allocation.
2141 VM_G1CollectForAllocation op(0, /* word_size */
2142 gc_count_before,
2143 cause,
2144 false, /* should_initiate_conc_mark */
2145 g1_policy()->max_pause_time_ms(),
2146 AllocationContext::current());
2147 VMThread::execute(&op);
2148 } else {
2149 // Schedule a Full GC.
2150 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2151 VMThread::execute(&op);
2152 }
2153 }
2154 } while (retry_gc);
2155 }
2156
2157 bool G1CollectedHeap::is_in(const void* p) const {
2158 if (_hrm.reserved().contains(p)) {
2159 // Given that we know that p is in the reserved space,
2160 // heap_region_containing() should successfully
2161 // return the containing region.
2162 HeapRegion* hr = heap_region_containing(p);
2163 return hr->is_in(p);
2164 } else {
2165 return false;
2166 }
2167 }
2168
2169 #ifdef ASSERT
2170 bool G1CollectedHeap::is_in_exact(const void* p) const {
2171 bool contains = reserved_region().contains(p);
2172 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2173 if (contains && available) {
2174 return true;
2175 } else {
2176 return false;
2177 }
2178 }
2179 #endif
2180
2181 // Iteration functions.
2182
2183 // Iterates an ObjectClosure over all objects within a HeapRegion.
2184
2185 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2186 ObjectClosure* _cl;
2187 public:
2188 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2189 bool do_heap_region(HeapRegion* r) {
2190 if (!r->is_continues_humongous()) {
2191 r->object_iterate(_cl);
2192 }
2193 return false;
2194 }
2195 };
2196
2197 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2198 IterateObjectClosureRegionClosure blk(cl);
2199 heap_region_iterate(&blk);
2200 }
2201
2202 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2203 _hrm.iterate(cl);
2204 }
2205
2206 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2207 HeapRegionClaimer *hrclaimer,
2208 uint worker_id) const {
2209 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2210 }
2211
2212 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2213 HeapRegionClaimer *hrclaimer) const {
2214 _hrm.par_iterate(cl, hrclaimer, 0);
2215 }
2216
2217 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2218 _collection_set.iterate(cl);
2219 }
2220
2221 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2222 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2223 }
2224
2225 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2226 HeapRegion* hr = heap_region_containing(addr);
2227 return hr->block_start(addr);
2228 }
2229
2230 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2231 HeapRegion* hr = heap_region_containing(addr);
2232 return hr->block_size(addr);
2233 }
2234
2235 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2236 HeapRegion* hr = heap_region_containing(addr);
2237 return hr->block_is_obj(addr);
2238 }
2239
2240 bool G1CollectedHeap::supports_tlab_allocation() const {
2241 return true;
2242 }
2243
2244 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2245 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2246 }
2247
2248 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2249 return _eden.length() * HeapRegion::GrainBytes;
2250 }
2251
2252 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2253 // must be equal to the humongous object limit.
2254 size_t G1CollectedHeap::max_tlab_size() const {
2255 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2256 }
2257
2258 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2259 AllocationContext_t context = AllocationContext::current();
2260 return _allocator->unsafe_max_tlab_alloc(context);
2261 }
2262
2263 size_t G1CollectedHeap::max_capacity() const {
2264 return _hrm.reserved().byte_size();
2265 }
2266
2267 jlong G1CollectedHeap::millis_since_last_gc() {
2268 // See the notes in GenCollectedHeap::millis_since_last_gc()
2269 // for more information about the implementation.
2270 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2271 _g1_policy->collection_pause_end_millis();
2272 if (ret_val < 0) {
2273 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2274 ". returning zero instead.", ret_val);
2275 return 0;
2276 }
2277 return ret_val;
2278 }
2279
2280 void G1CollectedHeap::prepare_for_verify() {
2281 _verifier->prepare_for_verify();
2282 }
2283
2284 void G1CollectedHeap::verify(VerifyOption vo) {
2285 _verifier->verify(vo);
2286 }
2287
2288 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2289 return true;
2290 }
2291
2292 const char* const* G1CollectedHeap::concurrent_phases() const {
2293 return _cmThread->concurrent_phases();
2294 }
2295
2296 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2297 return _cmThread->request_concurrent_phase(phase);
2298 }
2299
2300 class PrintRegionClosure: public HeapRegionClosure {
2301 outputStream* _st;
2302 public:
2303 PrintRegionClosure(outputStream* st) : _st(st) {}
2304 bool do_heap_region(HeapRegion* r) {
2305 r->print_on(_st);
2306 return false;
2307 }
2308 };
2309
2310 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2311 const HeapRegion* hr,
2312 const VerifyOption vo) const {
2313 switch (vo) {
2314 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2315 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2316 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2317 default: ShouldNotReachHere();
2318 }
2319 return false; // keep some compilers happy
2320 }
2321
2322 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2323 const VerifyOption vo) const {
2324 switch (vo) {
2325 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2326 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2327 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2328 default: ShouldNotReachHere();
2329 }
2330 return false; // keep some compilers happy
2331 }
2332
2333 void G1CollectedHeap::print_heap_regions() const {
2334 LogTarget(Trace, gc, heap, region) lt;
2335 if (lt.is_enabled()) {
2336 LogStream ls(lt);
2337 print_regions_on(&ls);
2338 }
2339 }
2340
2341 void G1CollectedHeap::print_on(outputStream* st) const {
2342 st->print(" %-20s", "garbage-first heap");
2343 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2344 capacity()/K, used_unlocked()/K);
2345 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2346 p2i(_hrm.reserved().start()),
2347 p2i(_hrm.reserved().end()));
2348 st->cr();
2349 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2350 uint young_regions = young_regions_count();
2351 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2352 (size_t) young_regions * HeapRegion::GrainBytes / K);
2353 uint survivor_regions = survivor_regions_count();
2354 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2355 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2356 st->cr();
2357 MetaspaceAux::print_on(st);
2358 }
2359
2360 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2361 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2362 "HS=humongous(starts), HC=humongous(continues), "
2363 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2364 "AC=allocation context, "
2365 "TAMS=top-at-mark-start (previous, next)");
2366 PrintRegionClosure blk(st);
2367 heap_region_iterate(&blk);
2368 }
2369
2370 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2371 print_on(st);
2372
2373 // Print the per-region information.
2374 print_regions_on(st);
2375 }
2376
2377 void G1CollectedHeap::print_on_error(outputStream* st) const {
2378 this->CollectedHeap::print_on_error(st);
2379
2380 if (_cm != NULL) {
2381 st->cr();
2382 _cm->print_on_error(st);
2383 }
2384 }
2385
2386 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2387 workers()->print_worker_threads_on(st);
2388 _cmThread->print_on(st);
2389 st->cr();
2390 _cm->print_worker_threads_on(st);
2391 _cr->print_threads_on(st);
2392 _young_gen_sampling_thread->print_on(st);
2393 if (G1StringDedup::is_enabled()) {
2394 G1StringDedup::print_worker_threads_on(st);
2395 }
2396 }
2397
2398 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2399 workers()->threads_do(tc);
2400 tc->do_thread(_cmThread);
2401 _cm->threads_do(tc);
2402 _cr->threads_do(tc);
2403 tc->do_thread(_young_gen_sampling_thread);
2404 if (G1StringDedup::is_enabled()) {
2405 G1StringDedup::threads_do(tc);
2406 }
2407 }
2408
2409 void G1CollectedHeap::print_tracing_info() const {
2410 g1_rem_set()->print_summary_info();
2411 concurrent_mark()->print_summary_info();
2412 }
2413
2414 #ifndef PRODUCT
2415 // Helpful for debugging RSet issues.
2416
2417 class PrintRSetsClosure : public HeapRegionClosure {
2418 private:
2419 const char* _msg;
2420 size_t _occupied_sum;
2421
2422 public:
2423 bool do_heap_region(HeapRegion* r) {
2424 HeapRegionRemSet* hrrs = r->rem_set();
2425 size_t occupied = hrrs->occupied();
2426 _occupied_sum += occupied;
2427
2428 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2429 if (occupied == 0) {
2430 tty->print_cr(" RSet is empty");
2431 } else {
2432 hrrs->print();
2433 }
2434 tty->print_cr("----------");
2435 return false;
2436 }
2437
2438 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2439 tty->cr();
2440 tty->print_cr("========================================");
2441 tty->print_cr("%s", msg);
2442 tty->cr();
2443 }
2444
2445 ~PrintRSetsClosure() {
2446 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2447 tty->print_cr("========================================");
2448 tty->cr();
2449 }
2450 };
2451
2452 void G1CollectedHeap::print_cset_rsets() {
2453 PrintRSetsClosure cl("Printing CSet RSets");
2454 collection_set_iterate(&cl);
2455 }
2456
2457 void G1CollectedHeap::print_all_rsets() {
2458 PrintRSetsClosure cl("Printing All RSets");;
2459 heap_region_iterate(&cl);
2460 }
2461 #endif // PRODUCT
2462
2463 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2464
2465 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2466 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2467 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2468
2469 size_t eden_capacity_bytes =
2470 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2471
2472 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2473 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2474 eden_capacity_bytes, survivor_used_bytes, num_regions());
2475 }
2476
2477 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2478 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2479 stats->unused(), stats->used(), stats->region_end_waste(),
2480 stats->regions_filled(), stats->direct_allocated(),
2481 stats->failure_used(), stats->failure_waste());
2482 }
2483
2484 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2485 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2486 gc_tracer->report_gc_heap_summary(when, heap_summary);
2487
2488 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2489 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2490 }
2491
2492 G1CollectedHeap* G1CollectedHeap::heap() {
2493 CollectedHeap* heap = Universe::heap();
2494 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2495 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2496 return (G1CollectedHeap*)heap;
2497 }
2498
2499 void G1CollectedHeap::gc_prologue(bool full) {
2500 // always_do_update_barrier = false;
2501 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2502
2503 // This summary needs to be printed before incrementing total collections.
2504 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2505
2506 // Update common counters.
2507 increment_total_collections(full /* full gc */);
2508 if (full) {
2509 increment_old_marking_cycles_started();
2510 reset_gc_time_stamp();
2511 } else {
2512 increment_gc_time_stamp();
2513 }
2514
2515 // Fill TLAB's and such
2516 double start = os::elapsedTime();
2517 accumulate_statistics_all_tlabs();
2518 ensure_parsability(true);
2519 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2520 }
2521
2522 void G1CollectedHeap::gc_epilogue(bool full) {
2523 // Update common counters.
2524 if (full) {
2525 // Update the number of full collections that have been completed.
2526 increment_old_marking_cycles_completed(false /* concurrent */);
2527 }
2528
2529 // We are at the end of the GC. Total collections has already been increased.
2530 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2531
2532 // FIXME: what is this about?
2533 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2534 // is set.
2535 #if COMPILER2_OR_JVMCI
2536 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2537 #endif
2538 // always_do_update_barrier = true;
2539
2540 double start = os::elapsedTime();
2541 resize_all_tlabs();
2542 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2543
2544 MemoryService::track_memory_usage();
2545 // We have just completed a GC. Update the soft reference
2546 // policy with the new heap occupancy
2547 Universe::update_heap_info_at_gc();
2548 }
2549
2550 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2551 uint gc_count_before,
2552 bool* succeeded,
2553 GCCause::Cause gc_cause) {
2554 assert_heap_not_locked_and_not_at_safepoint();
2555 VM_G1CollectForAllocation op(word_size,
2556 gc_count_before,
2557 gc_cause,
2558 false, /* should_initiate_conc_mark */
2559 g1_policy()->max_pause_time_ms(),
2560 AllocationContext::current());
2561 VMThread::execute(&op);
2562
2563 HeapWord* result = op.result();
2564 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2565 assert(result == NULL || ret_succeeded,
2566 "the result should be NULL if the VM did not succeed");
2567 *succeeded = ret_succeeded;
2568
2569 assert_heap_not_locked();
2570 return result;
2571 }
2572
2573 void
2574 G1CollectedHeap::doConcurrentMark() {
2575 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2576 if (!_cmThread->in_progress()) {
2577 _cmThread->set_started();
2578 CGC_lock->notify();
2579 }
2580 }
2581
2582 size_t G1CollectedHeap::pending_card_num() {
2583 size_t extra_cards = 0;
2584 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2585 DirtyCardQueue& dcq = curr->dirty_card_queue();
2586 extra_cards += dcq.size();
2587 }
2588 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2589 size_t buffer_size = dcqs.buffer_size();
2590 size_t buffer_num = dcqs.completed_buffers_num();
2591
2592 return buffer_size * buffer_num + extra_cards;
2593 }
2594
2595 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2596 private:
2597 size_t _total_humongous;
2598 size_t _candidate_humongous;
2599
2600 DirtyCardQueue _dcq;
2601
2602 // We don't nominate objects with many remembered set entries, on
2603 // the assumption that such objects are likely still live.
2604 bool is_remset_small(HeapRegion* region) const {
2605 HeapRegionRemSet* const rset = region->rem_set();
2606 return G1EagerReclaimHumongousObjectsWithStaleRefs
2607 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2608 : rset->is_empty();
2609 }
2610
2611 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2612 assert(region->is_starts_humongous(), "Must start a humongous object");
2613
2614 oop obj = oop(region->bottom());
2615
2616 // Dead objects cannot be eager reclaim candidates. Due to class
2617 // unloading it is unsafe to query their classes so we return early.
2618 if (heap->is_obj_dead(obj, region)) {
2619 return false;
2620 }
2621
2622 // Candidate selection must satisfy the following constraints
2623 // while concurrent marking is in progress:
2624 //
2625 // * In order to maintain SATB invariants, an object must not be
2626 // reclaimed if it was allocated before the start of marking and
2627 // has not had its references scanned. Such an object must have
2628 // its references (including type metadata) scanned to ensure no
2629 // live objects are missed by the marking process. Objects
2630 // allocated after the start of concurrent marking don't need to
2631 // be scanned.
2632 //
2633 // * An object must not be reclaimed if it is on the concurrent
2634 // mark stack. Objects allocated after the start of concurrent
2635 // marking are never pushed on the mark stack.
2636 //
2637 // Nominating only objects allocated after the start of concurrent
2638 // marking is sufficient to meet both constraints. This may miss
2639 // some objects that satisfy the constraints, but the marking data
2640 // structures don't support efficiently performing the needed
2641 // additional tests or scrubbing of the mark stack.
2642 //
2643 // However, we presently only nominate is_typeArray() objects.
2644 // A humongous object containing references induces remembered
2645 // set entries on other regions. In order to reclaim such an
2646 // object, those remembered sets would need to be cleaned up.
2647 //
2648 // We also treat is_typeArray() objects specially, allowing them
2649 // to be reclaimed even if allocated before the start of
2650 // concurrent mark. For this we rely on mark stack insertion to
2651 // exclude is_typeArray() objects, preventing reclaiming an object
2652 // that is in the mark stack. We also rely on the metadata for
2653 // such objects to be built-in and so ensured to be kept live.
2654 // Frequent allocation and drop of large binary blobs is an
2655 // important use case for eager reclaim, and this special handling
2656 // may reduce needed headroom.
2657
2658 return obj->is_typeArray() && is_remset_small(region);
2659 }
2660
2661 public:
2662 RegisterHumongousWithInCSetFastTestClosure()
2663 : _total_humongous(0),
2664 _candidate_humongous(0),
2665 _dcq(&JavaThread::dirty_card_queue_set()) {
2666 }
2667
2668 virtual bool do_heap_region(HeapRegion* r) {
2669 if (!r->is_starts_humongous()) {
2670 return false;
2671 }
2672 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2673
2674 bool is_candidate = humongous_region_is_candidate(g1h, r);
2675 uint rindex = r->hrm_index();
2676 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2677 if (is_candidate) {
2678 _candidate_humongous++;
2679 g1h->register_humongous_region_with_cset(rindex);
2680 // Is_candidate already filters out humongous object with large remembered sets.
2681 // If we have a humongous object with a few remembered sets, we simply flush these
2682 // remembered set entries into the DCQS. That will result in automatic
2683 // re-evaluation of their remembered set entries during the following evacuation
2684 // phase.
2685 if (!r->rem_set()->is_empty()) {
2686 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2687 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2688 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2689 HeapRegionRemSetIterator hrrs(r->rem_set());
2690 size_t card_index;
2691 while (hrrs.has_next(card_index)) {
2692 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2693 // The remembered set might contain references to already freed
2694 // regions. Filter out such entries to avoid failing card table
2695 // verification.
2696 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2697 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2698 *card_ptr = CardTableModRefBS::dirty_card_val();
2699 _dcq.enqueue(card_ptr);
2700 }
2701 }
2702 }
2703 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2704 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2705 hrrs.n_yielded(), r->rem_set()->occupied());
2706 r->rem_set()->clear_locked();
2707 }
2708 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2709 }
2710 _total_humongous++;
2711
2712 return false;
2713 }
2714
2715 size_t total_humongous() const { return _total_humongous; }
2716 size_t candidate_humongous() const { return _candidate_humongous; }
2717
2718 void flush_rem_set_entries() { _dcq.flush(); }
2719 };
2720
2721 void G1CollectedHeap::register_humongous_regions_with_cset() {
2722 if (!G1EagerReclaimHumongousObjects) {
2723 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2724 return;
2725 }
2726 double time = os::elapsed_counter();
2727
2728 // Collect reclaim candidate information and register candidates with cset.
2729 RegisterHumongousWithInCSetFastTestClosure cl;
2730 heap_region_iterate(&cl);
2731
2732 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2733 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2734 cl.total_humongous(),
2735 cl.candidate_humongous());
2736 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2737
2738 // Finally flush all remembered set entries to re-check into the global DCQS.
2739 cl.flush_rem_set_entries();
2740 }
2741
2742 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2743 public:
2744 bool do_heap_region(HeapRegion* hr) {
2745 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2746 hr->verify_rem_set();
2747 }
2748 return false;
2749 }
2750 };
2751
2752 uint G1CollectedHeap::num_task_queues() const {
2753 return _task_queues->size();
2754 }
2755
2756 #if TASKQUEUE_STATS
2757 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2758 st->print_raw_cr("GC Task Stats");
2759 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2760 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2761 }
2762
2763 void G1CollectedHeap::print_taskqueue_stats() const {
2764 if (!log_is_enabled(Trace, gc, task, stats)) {
2765 return;
2766 }
2767 Log(gc, task, stats) log;
2768 ResourceMark rm;
2769 LogStream ls(log.trace());
2770 outputStream* st = &ls;
2771
2772 print_taskqueue_stats_hdr(st);
2773
2774 TaskQueueStats totals;
2775 const uint n = num_task_queues();
2776 for (uint i = 0; i < n; ++i) {
2777 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2778 totals += task_queue(i)->stats;
2779 }
2780 st->print_raw("tot "); totals.print(st); st->cr();
2781
2782 DEBUG_ONLY(totals.verify());
2783 }
2784
2785 void G1CollectedHeap::reset_taskqueue_stats() {
2786 const uint n = num_task_queues();
2787 for (uint i = 0; i < n; ++i) {
2788 task_queue(i)->stats.reset();
2789 }
2790 }
2791 #endif // TASKQUEUE_STATS
2792
2793 void G1CollectedHeap::wait_for_root_region_scanning() {
2794 double scan_wait_start = os::elapsedTime();
2795 // We have to wait until the CM threads finish scanning the
2796 // root regions as it's the only way to ensure that all the
2797 // objects on them have been correctly scanned before we start
2798 // moving them during the GC.
2799 bool waited = _cm->root_regions()->wait_until_scan_finished();
2800 double wait_time_ms = 0.0;
2801 if (waited) {
2802 double scan_wait_end = os::elapsedTime();
2803 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2804 }
2805 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2806 }
2807
2808 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2809 private:
2810 G1HRPrinter* _hr_printer;
2811 public:
2812 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2813
2814 virtual bool do_heap_region(HeapRegion* r) {
2815 _hr_printer->cset(r);
2816 return false;
2817 }
2818 };
2819
2820 void G1CollectedHeap::start_new_collection_set() {
2821 collection_set()->start_incremental_building();
2822
2823 clear_cset_fast_test();
2824
2825 guarantee(_eden.length() == 0, "eden should have been cleared");
2826 g1_policy()->transfer_survivors_to_cset(survivor());
2827 }
2828
2829 bool
2830 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2831 assert_at_safepoint(true /* should_be_vm_thread */);
2832 guarantee(!is_gc_active(), "collection is not reentrant");
2833
2834 if (GCLocker::check_active_before_gc()) {
2835 return false;
2836 }
2837
2838 _gc_timer_stw->register_gc_start();
2839
2840 GCIdMark gc_id_mark;
2841 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2842
2843 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2844 ResourceMark rm;
2845
2846 g1_policy()->note_gc_start();
2847
2848 wait_for_root_region_scanning();
2849
2850 print_heap_before_gc();
2851 print_heap_regions();
2852 trace_heap_before_gc(_gc_tracer_stw);
2853
2854 _verifier->verify_region_sets_optional();
2855 _verifier->verify_dirty_young_regions();
2856
2857 // We should not be doing initial mark unless the conc mark thread is running
2858 if (!_cmThread->should_terminate()) {
2859 // This call will decide whether this pause is an initial-mark
2860 // pause. If it is, during_initial_mark_pause() will return true
2861 // for the duration of this pause.
2862 g1_policy()->decide_on_conc_mark_initiation();
2863 }
2864
2865 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2866 assert(!collector_state()->during_initial_mark_pause() ||
2867 collector_state()->gcs_are_young(), "sanity");
2868
2869 // We also do not allow mixed GCs during marking.
2870 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2871
2872 // Record whether this pause is an initial mark. When the current
2873 // thread has completed its logging output and it's safe to signal
2874 // the CM thread, the flag's value in the policy has been reset.
2875 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2876
2877 // Inner scope for scope based logging, timers, and stats collection
2878 {
2879 EvacuationInfo evacuation_info;
2880
2881 if (collector_state()->during_initial_mark_pause()) {
2882 // We are about to start a marking cycle, so we increment the
2883 // full collection counter.
2884 increment_old_marking_cycles_started();
2885 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2886 }
2887
2888 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2889
2890 GCTraceCPUTime tcpu;
2891
2892 G1HeapVerifier::G1VerifyType verify_type;
2893 FormatBuffer<> gc_string("Pause ");
2894 if (collector_state()->during_initial_mark_pause()) {
2895 gc_string.append("Initial Mark");
2896 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2897 } else if (collector_state()->gcs_are_young()) {
2898 gc_string.append("Young");
2899 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2900 } else {
2901 gc_string.append("Mixed");
2902 verify_type = G1HeapVerifier::G1VerifyMixed;
2903 }
2904 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2905
2906 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2907 workers()->active_workers(),
2908 Threads::number_of_non_daemon_threads());
2909 workers()->update_active_workers(active_workers);
2910 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2911
2912 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2913 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2914
2915 // If the secondary_free_list is not empty, append it to the
2916 // free_list. No need to wait for the cleanup operation to finish;
2917 // the region allocation code will check the secondary_free_list
2918 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2919 // set, skip this step so that the region allocation code has to
2920 // get entries from the secondary_free_list.
2921 if (!G1StressConcRegionFreeing) {
2922 append_secondary_free_list_if_not_empty_with_lock();
2923 }
2924
2925 G1HeapTransition heap_transition(this);
2926 size_t heap_used_bytes_before_gc = used();
2927
2928 // Don't dynamically change the number of GC threads this early. A value of
2929 // 0 is used to indicate serial work. When parallel work is done,
2930 // it will be set.
2931
2932 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2933 IsGCActiveMark x;
2934
2935 gc_prologue(false);
2936
2937 if (VerifyRememberedSets) {
2938 log_info(gc, verify)("[Verifying RemSets before GC]");
2939 VerifyRegionRemSetClosure v_cl;
2940 heap_region_iterate(&v_cl);
2941 }
2942
2943 _verifier->verify_before_gc(verify_type);
2944
2945 _verifier->check_bitmaps("GC Start");
2946
2947 #if COMPILER2_OR_JVMCI
2948 DerivedPointerTable::clear();
2949 #endif
2950
2951 // Please see comment in g1CollectedHeap.hpp and
2952 // G1CollectedHeap::ref_processing_init() to see how
2953 // reference processing currently works in G1.
2954
2955 // Enable discovery in the STW reference processor
2956 if (g1_policy()->should_process_references()) {
2957 ref_processor_stw()->enable_discovery();
2958 } else {
2959 ref_processor_stw()->disable_discovery();
2960 }
2961
2962 {
2963 // We want to temporarily turn off discovery by the
2964 // CM ref processor, if necessary, and turn it back on
2965 // on again later if we do. Using a scoped
2966 // NoRefDiscovery object will do this.
2967 NoRefDiscovery no_cm_discovery(ref_processor_cm());
2968
2969 // Forget the current alloc region (we might even choose it to be part
2970 // of the collection set!).
2971 _allocator->release_mutator_alloc_region();
2972
2973 // This timing is only used by the ergonomics to handle our pause target.
2974 // It is unclear why this should not include the full pause. We will
2975 // investigate this in CR 7178365.
2976 //
2977 // Preserving the old comment here if that helps the investigation:
2978 //
2979 // The elapsed time induced by the start time below deliberately elides
2980 // the possible verification above.
2981 double sample_start_time_sec = os::elapsedTime();
2982
2983 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2984
2985 if (collector_state()->during_initial_mark_pause()) {
2986 concurrent_mark()->checkpoint_roots_initial_pre();
2987 }
2988
2989 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2990
2991 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2992
2993 // Make sure the remembered sets are up to date. This needs to be
2994 // done before register_humongous_regions_with_cset(), because the
2995 // remembered sets are used there to choose eager reclaim candidates.
2996 // If the remembered sets are not up to date we might miss some
2997 // entries that need to be handled.
2998 g1_rem_set()->cleanupHRRS();
2999
3000 register_humongous_regions_with_cset();
3001
3002 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3003
3004 // We call this after finalize_cset() to
3005 // ensure that the CSet has been finalized.
3006 _cm->verify_no_cset_oops();
3007
3008 if (_hr_printer.is_active()) {
3009 G1PrintCollectionSetClosure cl(&_hr_printer);
3010 _collection_set.iterate(&cl);
3011 }
3012
3013 // Initialize the GC alloc regions.
3014 _allocator->init_gc_alloc_regions(evacuation_info);
3015
3016 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3017 pre_evacuate_collection_set();
3018
3019 // Actually do the work...
3020 evacuate_collection_set(evacuation_info, &per_thread_states);
3021
3022 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3023
3024 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3025 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3026
3027 eagerly_reclaim_humongous_regions();
3028
3029 record_obj_copy_mem_stats();
3030 _survivor_evac_stats.adjust_desired_plab_sz();
3031 _old_evac_stats.adjust_desired_plab_sz();
3032
3033 double start = os::elapsedTime();
3034 start_new_collection_set();
3035 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3036
3037 if (evacuation_failed()) {
3038 set_used(recalculate_used());
3039 if (_archive_allocator != NULL) {
3040 _archive_allocator->clear_used();
3041 }
3042 for (uint i = 0; i < ParallelGCThreads; i++) {
3043 if (_evacuation_failed_info_array[i].has_failed()) {
3044 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3045 }
3046 }
3047 } else {
3048 // The "used" of the the collection set have already been subtracted
3049 // when they were freed. Add in the bytes evacuated.
3050 increase_used(g1_policy()->bytes_copied_during_gc());
3051 }
3052
3053 if (collector_state()->during_initial_mark_pause()) {
3054 // We have to do this before we notify the CM threads that
3055 // they can start working to make sure that all the
3056 // appropriate initialization is done on the CM object.
3057 concurrent_mark()->checkpoint_roots_initial_post();
3058 collector_state()->set_mark_in_progress(true);
3059 // Note that we don't actually trigger the CM thread at
3060 // this point. We do that later when we're sure that
3061 // the current thread has completed its logging output.
3062 }
3063
3064 allocate_dummy_regions();
3065
3066 _allocator->init_mutator_alloc_region();
3067
3068 {
3069 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3070 if (expand_bytes > 0) {
3071 size_t bytes_before = capacity();
3072 // No need for an ergo logging here,
3073 // expansion_amount() does this when it returns a value > 0.
3074 double expand_ms;
3075 if (!expand(expand_bytes, _workers, &expand_ms)) {
3076 // We failed to expand the heap. Cannot do anything about it.
3077 }
3078 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3079 }
3080 }
3081
3082 // We redo the verification but now wrt to the new CSet which
3083 // has just got initialized after the previous CSet was freed.
3084 _cm->verify_no_cset_oops();
3085
3086 // This timing is only used by the ergonomics to handle our pause target.
3087 // It is unclear why this should not include the full pause. We will
3088 // investigate this in CR 7178365.
3089 double sample_end_time_sec = os::elapsedTime();
3090 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3091 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3092 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3093
3094 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3095 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3096
3097 if (VerifyRememberedSets) {
3098 log_info(gc, verify)("[Verifying RemSets after GC]");
3099 VerifyRegionRemSetClosure v_cl;
3100 heap_region_iterate(&v_cl);
3101 }
3102
3103 _verifier->verify_after_gc(verify_type);
3104 _verifier->check_bitmaps("GC End");
3105
3106 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3107 ref_processor_stw()->verify_no_references_recorded();
3108
3109 // CM reference discovery will be re-enabled if necessary.
3110 }
3111
3112 #ifdef TRACESPINNING
3113 ParallelTaskTerminator::print_termination_counts();
3114 #endif
3115
3116 gc_epilogue(false);
3117 }
3118
3119 // Print the remainder of the GC log output.
3120 if (evacuation_failed()) {
3121 log_info(gc)("To-space exhausted");
3122 }
3123
3124 g1_policy()->print_phases();
3125 heap_transition.print();
3126
3127 // It is not yet to safe to tell the concurrent mark to
3128 // start as we have some optional output below. We don't want the
3129 // output from the concurrent mark thread interfering with this
3130 // logging output either.
3131
3132 _hrm.verify_optional();
3133 _verifier->verify_region_sets_optional();
3134
3135 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3136 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3137
3138 print_heap_after_gc();
3139 print_heap_regions();
3140 trace_heap_after_gc(_gc_tracer_stw);
3141
3142 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3143 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3144 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3145 // before any GC notifications are raised.
3146 g1mm()->update_sizes();
3147
3148 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3149 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3150 _gc_timer_stw->register_gc_end();
3151 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3152 }
3153 // It should now be safe to tell the concurrent mark thread to start
3154 // without its logging output interfering with the logging output
3155 // that came from the pause.
3156
3157 if (should_start_conc_mark) {
3158 // CAUTION: after the doConcurrentMark() call below,
3159 // the concurrent marking thread(s) could be running
3160 // concurrently with us. Make sure that anything after
3161 // this point does not assume that we are the only GC thread
3162 // running. Note: of course, the actual marking work will
3163 // not start until the safepoint itself is released in
3164 // SuspendibleThreadSet::desynchronize().
3165 doConcurrentMark();
3166 }
3167
3168 return true;
3169 }
3170
3171 void G1CollectedHeap::remove_self_forwarding_pointers() {
3172 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3173 workers()->run_task(&rsfp_task);
3174 }
3175
3176 void G1CollectedHeap::restore_after_evac_failure() {
3177 double remove_self_forwards_start = os::elapsedTime();
3178
3179 remove_self_forwarding_pointers();
3180 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3181 _preserved_marks_set.restore(&task_executor);
3182
3183 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3184 }
3185
3186 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3187 if (!_evacuation_failed) {
3188 _evacuation_failed = true;
3189 }
3190
3191 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3192 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3193 }
3194
3195 bool G1ParEvacuateFollowersClosure::offer_termination() {
3196 G1ParScanThreadState* const pss = par_scan_state();
3197 start_term_time();
3198 const bool res = terminator()->offer_termination();
3199 end_term_time();
3200 return res;
3201 }
3202
3203 void G1ParEvacuateFollowersClosure::do_void() {
3204 G1ParScanThreadState* const pss = par_scan_state();
3205 pss->trim_queue();
3206 do {
3207 pss->steal_and_trim_queue(queues());
3208 } while (!offer_termination());
3209 }
3210
3211 class G1ParTask : public AbstractGangTask {
3212 protected:
3213 G1CollectedHeap* _g1h;
3214 G1ParScanThreadStateSet* _pss;
3215 RefToScanQueueSet* _queues;
3216 G1RootProcessor* _root_processor;
3217 ParallelTaskTerminator _terminator;
3218 uint _n_workers;
3219
3220 public:
3221 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3222 : AbstractGangTask("G1 collection"),
3223 _g1h(g1h),
3224 _pss(per_thread_states),
3225 _queues(task_queues),
3226 _root_processor(root_processor),
3227 _terminator(n_workers, _queues),
3228 _n_workers(n_workers)
3229 {}
3230
3231 void work(uint worker_id) {
3232 if (worker_id >= _n_workers) return; // no work needed this round
3233
3234 double start_sec = os::elapsedTime();
3235 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3236
3237 {
3238 ResourceMark rm;
3239 HandleMark hm;
3240
3241 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3242
3243 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3244 pss->set_ref_processor(rp);
3245
3246 double start_strong_roots_sec = os::elapsedTime();
3247
3248 _root_processor->evacuate_roots(pss->closures(), worker_id);
3249
3250 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3251 // treating the nmethods visited to act as roots for concurrent marking.
3252 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3253 // objects copied by the current evacuation.
3254 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3255 pss->closures()->weak_codeblobs(),
3256 worker_id);
3257
3258 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3259
3260 double term_sec = 0.0;
3261 size_t evac_term_attempts = 0;
3262 {
3263 double start = os::elapsedTime();
3264 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3265 evac.do_void();
3266
3267 evac_term_attempts = evac.term_attempts();
3268 term_sec = evac.term_time();
3269 double elapsed_sec = os::elapsedTime() - start;
3270 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3271 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3272 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3273 }
3274
3275 assert(pss->queue_is_empty(), "should be empty");
3276
3277 if (log_is_enabled(Debug, gc, task, stats)) {
3278 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3279 size_t lab_waste;
3280 size_t lab_undo_waste;
3281 pss->waste(lab_waste, lab_undo_waste);
3282 _g1h->print_termination_stats(worker_id,
3283 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3284 strong_roots_sec * 1000.0, /* strong roots time */
3285 term_sec * 1000.0, /* evac term time */
3286 evac_term_attempts, /* evac term attempts */
3287 lab_waste, /* alloc buffer waste */
3288 lab_undo_waste /* undo waste */
3289 );
3290 }
3291
3292 // Close the inner scope so that the ResourceMark and HandleMark
3293 // destructors are executed here and are included as part of the
3294 // "GC Worker Time".
3295 }
3296 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3297 }
3298 };
3299
3300 void G1CollectedHeap::print_termination_stats_hdr() {
3301 log_debug(gc, task, stats)("GC Termination Stats");
3302 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3303 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3304 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3305 }
3306
3307 void G1CollectedHeap::print_termination_stats(uint worker_id,
3308 double elapsed_ms,
3309 double strong_roots_ms,
3310 double term_ms,
3311 size_t term_attempts,
3312 size_t alloc_buffer_waste,
3313 size_t undo_waste) const {
3314 log_debug(gc, task, stats)
3315 ("%3d %9.2f %9.2f %6.2f "
3316 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3317 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3318 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3319 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3320 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3321 alloc_buffer_waste * HeapWordSize / K,
3322 undo_waste * HeapWordSize / K);
3323 }
3324
3325 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3326 private:
3327 BoolObjectClosure* _is_alive;
3328 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3329
3330 int _initial_string_table_size;
3331 int _initial_symbol_table_size;
3332
3333 bool _process_strings;
3334 int _strings_processed;
3335 int _strings_removed;
3336
3337 bool _process_symbols;
3338 int _symbols_processed;
3339 int _symbols_removed;
3340
3341 bool _process_string_dedup;
3342
3343 public:
3344 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3345 AbstractGangTask("String/Symbol Unlinking"),
3346 _is_alive(is_alive),
3347 _dedup_closure(is_alive, NULL, false),
3348 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3349 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3350 _process_string_dedup(process_string_dedup) {
3351
3352 _initial_string_table_size = StringTable::the_table()->table_size();
3353 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3354 if (process_strings) {
3355 StringTable::clear_parallel_claimed_index();
3356 }
3357 if (process_symbols) {
3358 SymbolTable::clear_parallel_claimed_index();
3359 }
3360 }
3361
3362 ~G1StringAndSymbolCleaningTask() {
3363 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3364 "claim value %d after unlink less than initial string table size %d",
3365 StringTable::parallel_claimed_index(), _initial_string_table_size);
3366 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3367 "claim value %d after unlink less than initial symbol table size %d",
3368 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3369
3370 log_info(gc, stringtable)(
3371 "Cleaned string and symbol table, "
3372 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3373 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3374 strings_processed(), strings_removed(),
3375 symbols_processed(), symbols_removed());
3376 }
3377
3378 void work(uint worker_id) {
3379 int strings_processed = 0;
3380 int strings_removed = 0;
3381 int symbols_processed = 0;
3382 int symbols_removed = 0;
3383 if (_process_strings) {
3384 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3385 Atomic::add(strings_processed, &_strings_processed);
3386 Atomic::add(strings_removed, &_strings_removed);
3387 }
3388 if (_process_symbols) {
3389 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3390 Atomic::add(symbols_processed, &_symbols_processed);
3391 Atomic::add(symbols_removed, &_symbols_removed);
3392 }
3393 if (_process_string_dedup) {
3394 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3395 }
3396 }
3397
3398 size_t strings_processed() const { return (size_t)_strings_processed; }
3399 size_t strings_removed() const { return (size_t)_strings_removed; }
3400
3401 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3402 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3403 };
3404
3405 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3406 private:
3407 static Monitor* _lock;
3408
3409 BoolObjectClosure* const _is_alive;
3410 const bool _unloading_occurred;
3411 const uint _num_workers;
3412
3413 // Variables used to claim nmethods.
3414 CompiledMethod* _first_nmethod;
3415 CompiledMethod* volatile _claimed_nmethod;
3416
3417 // The list of nmethods that need to be processed by the second pass.
3418 CompiledMethod* volatile _postponed_list;
3419 volatile uint _num_entered_barrier;
3420
3421 public:
3422 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3423 _is_alive(is_alive),
3424 _unloading_occurred(unloading_occurred),
3425 _num_workers(num_workers),
3426 _first_nmethod(NULL),
3427 _claimed_nmethod(NULL),
3428 _postponed_list(NULL),
3429 _num_entered_barrier(0)
3430 {
3431 CompiledMethod::increase_unloading_clock();
3432 // Get first alive nmethod
3433 CompiledMethodIterator iter = CompiledMethodIterator();
3434 if(iter.next_alive()) {
3435 _first_nmethod = iter.method();
3436 }
3437 _claimed_nmethod = _first_nmethod;
3438 }
3439
3440 ~G1CodeCacheUnloadingTask() {
3441 CodeCache::verify_clean_inline_caches();
3442
3443 CodeCache::set_needs_cache_clean(false);
3444 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3445
3446 CodeCache::verify_icholder_relocations();
3447 }
3448
3449 private:
3450 void add_to_postponed_list(CompiledMethod* nm) {
3451 CompiledMethod* old;
3452 do {
3453 old = _postponed_list;
3454 nm->set_unloading_next(old);
3455 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3456 }
3457
3458 void clean_nmethod(CompiledMethod* nm) {
3459 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3460
3461 if (postponed) {
3462 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3463 add_to_postponed_list(nm);
3464 }
3465
3466 // Mark that this thread has been cleaned/unloaded.
3467 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3468 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3469 }
3470
3471 void clean_nmethod_postponed(CompiledMethod* nm) {
3472 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3473 }
3474
3475 static const int MaxClaimNmethods = 16;
3476
3477 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3478 CompiledMethod* first;
3479 CompiledMethodIterator last;
3480
3481 do {
3482 *num_claimed_nmethods = 0;
3483
3484 first = _claimed_nmethod;
3485 last = CompiledMethodIterator(first);
3486
3487 if (first != NULL) {
3488
3489 for (int i = 0; i < MaxClaimNmethods; i++) {
3490 if (!last.next_alive()) {
3491 break;
3492 }
3493 claimed_nmethods[i] = last.method();
3494 (*num_claimed_nmethods)++;
3495 }
3496 }
3497
3498 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3499 }
3500
3501 CompiledMethod* claim_postponed_nmethod() {
3502 CompiledMethod* claim;
3503 CompiledMethod* next;
3504
3505 do {
3506 claim = _postponed_list;
3507 if (claim == NULL) {
3508 return NULL;
3509 }
3510
3511 next = claim->unloading_next();
3512
3513 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3514
3515 return claim;
3516 }
3517
3518 public:
3519 // Mark that we're done with the first pass of nmethod cleaning.
3520 void barrier_mark(uint worker_id) {
3521 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3522 _num_entered_barrier++;
3523 if (_num_entered_barrier == _num_workers) {
3524 ml.notify_all();
3525 }
3526 }
3527
3528 // See if we have to wait for the other workers to
3529 // finish their first-pass nmethod cleaning work.
3530 void barrier_wait(uint worker_id) {
3531 if (_num_entered_barrier < _num_workers) {
3532 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3533 while (_num_entered_barrier < _num_workers) {
3534 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3535 }
3536 }
3537 }
3538
3539 // Cleaning and unloading of nmethods. Some work has to be postponed
3540 // to the second pass, when we know which nmethods survive.
3541 void work_first_pass(uint worker_id) {
3542 // The first nmethods is claimed by the first worker.
3543 if (worker_id == 0 && _first_nmethod != NULL) {
3544 clean_nmethod(_first_nmethod);
3545 _first_nmethod = NULL;
3546 }
3547
3548 int num_claimed_nmethods;
3549 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3550
3551 while (true) {
3552 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3553
3554 if (num_claimed_nmethods == 0) {
3555 break;
3556 }
3557
3558 for (int i = 0; i < num_claimed_nmethods; i++) {
3559 clean_nmethod(claimed_nmethods[i]);
3560 }
3561 }
3562 }
3563
3564 void work_second_pass(uint worker_id) {
3565 CompiledMethod* nm;
3566 // Take care of postponed nmethods.
3567 while ((nm = claim_postponed_nmethod()) != NULL) {
3568 clean_nmethod_postponed(nm);
3569 }
3570 }
3571 };
3572
3573 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3574
3575 class G1KlassCleaningTask : public StackObj {
3576 BoolObjectClosure* _is_alive;
3577 volatile int _clean_klass_tree_claimed;
3578 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3579
3580 public:
3581 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3582 _is_alive(is_alive),
3583 _clean_klass_tree_claimed(0),
3584 _klass_iterator() {
3585 }
3586
3587 private:
3588 bool claim_clean_klass_tree_task() {
3589 if (_clean_klass_tree_claimed) {
3590 return false;
3591 }
3592
3593 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3594 }
3595
3596 InstanceKlass* claim_next_klass() {
3597 Klass* klass;
3598 do {
3599 klass =_klass_iterator.next_klass();
3600 } while (klass != NULL && !klass->is_instance_klass());
3601
3602 // this can be null so don't call InstanceKlass::cast
3603 return static_cast<InstanceKlass*>(klass);
3604 }
3605
3606 public:
3607
3608 void clean_klass(InstanceKlass* ik) {
3609 ik->clean_weak_instanceklass_links(_is_alive);
3610 }
3611
3612 void work() {
3613 ResourceMark rm;
3614
3615 // One worker will clean the subklass/sibling klass tree.
3616 if (claim_clean_klass_tree_task()) {
3617 Klass::clean_subklass_tree(_is_alive);
3618 }
3619
3620 // All workers will help cleaning the classes,
3621 InstanceKlass* klass;
3622 while ((klass = claim_next_klass()) != NULL) {
3623 clean_klass(klass);
3624 }
3625 }
3626 };
3627
3628 class G1ResolvedMethodCleaningTask : public StackObj {
3629 BoolObjectClosure* _is_alive;
3630 volatile int _resolved_method_task_claimed;
3631 public:
3632 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3633 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3634
3635 bool claim_resolved_method_task() {
3636 if (_resolved_method_task_claimed) {
3637 return false;
3638 }
3639 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3640 }
3641
3642 // These aren't big, one thread can do it all.
3643 void work() {
3644 if (claim_resolved_method_task()) {
3645 ResolvedMethodTable::unlink(_is_alive);
3646 }
3647 }
3648 };
3649
3650
3651 // To minimize the remark pause times, the tasks below are done in parallel.
3652 class G1ParallelCleaningTask : public AbstractGangTask {
3653 private:
3654 G1StringAndSymbolCleaningTask _string_symbol_task;
3655 G1CodeCacheUnloadingTask _code_cache_task;
3656 G1KlassCleaningTask _klass_cleaning_task;
3657 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3658
3659 public:
3660 // The constructor is run in the VMThread.
3661 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3662 AbstractGangTask("Parallel Cleaning"),
3663 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3664 _code_cache_task(num_workers, is_alive, unloading_occurred),
3665 _klass_cleaning_task(is_alive),
3666 _resolved_method_cleaning_task(is_alive) {
3667 }
3668
3669 // The parallel work done by all worker threads.
3670 void work(uint worker_id) {
3671 // Do first pass of code cache cleaning.
3672 _code_cache_task.work_first_pass(worker_id);
3673
3674 // Let the threads mark that the first pass is done.
3675 _code_cache_task.barrier_mark(worker_id);
3676
3677 // Clean the Strings and Symbols.
3678 _string_symbol_task.work(worker_id);
3679
3680 // Clean unreferenced things in the ResolvedMethodTable
3681 _resolved_method_cleaning_task.work();
3682
3683 // Wait for all workers to finish the first code cache cleaning pass.
3684 _code_cache_task.barrier_wait(worker_id);
3685
3686 // Do the second code cache cleaning work, which realize on
3687 // the liveness information gathered during the first pass.
3688 _code_cache_task.work_second_pass(worker_id);
3689
3690 // Clean all klasses that were not unloaded.
3691 _klass_cleaning_task.work();
3692 }
3693 };
3694
3695
3696 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3697 bool class_unloading_occurred) {
3698 uint n_workers = workers()->active_workers();
3699
3700 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3701 workers()->run_task(&g1_unlink_task);
3702 }
3703
3704 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3705 bool process_strings,
3706 bool process_symbols,
3707 bool process_string_dedup) {
3708 if (!process_strings && !process_symbols && !process_string_dedup) {
3709 // Nothing to clean.
3710 return;
3711 }
3712
3713 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3714 workers()->run_task(&g1_unlink_task);
3715
3716 }
3717
3718 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3719 private:
3720 DirtyCardQueueSet* _queue;
3721 G1CollectedHeap* _g1h;
3722 public:
3723 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3724 _queue(queue), _g1h(g1h) { }
3725
3726 virtual void work(uint worker_id) {
3727 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3728 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3729
3730 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3731 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3732
3733 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3734 }
3735 };
3736
3737 void G1CollectedHeap::redirty_logged_cards() {
3738 double redirty_logged_cards_start = os::elapsedTime();
3739
3740 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3741 dirty_card_queue_set().reset_for_par_iteration();
3742 workers()->run_task(&redirty_task);
3743
3744 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3745 dcq.merge_bufferlists(&dirty_card_queue_set());
3746 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3747
3748 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3749 }
3750
3751 // Weak Reference Processing support
3752
3753 // An always "is_alive" closure that is used to preserve referents.
3754 // If the object is non-null then it's alive. Used in the preservation
3755 // of referent objects that are pointed to by reference objects
3756 // discovered by the CM ref processor.
3757 class G1AlwaysAliveClosure: public BoolObjectClosure {
3758 G1CollectedHeap* _g1;
3759 public:
3760 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3761 bool do_object_b(oop p) {
3762 if (p != NULL) {
3763 return true;
3764 }
3765 return false;
3766 }
3767 };
3768
3769 bool G1STWIsAliveClosure::do_object_b(oop p) {
3770 // An object is reachable if it is outside the collection set,
3771 // or is inside and copied.
3772 return !_g1->is_in_cset(p) || p->is_forwarded();
3773 }
3774
3775 // Non Copying Keep Alive closure
3776 class G1KeepAliveClosure: public OopClosure {
3777 G1CollectedHeap* _g1;
3778 public:
3779 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3780 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3781 void do_oop(oop* p) {
3782 oop obj = *p;
3783 assert(obj != NULL, "the caller should have filtered out NULL values");
3784
3785 const InCSetState cset_state = _g1->in_cset_state(obj);
3786 if (!cset_state.is_in_cset_or_humongous()) {
3787 return;
3788 }
3789 if (cset_state.is_in_cset()) {
3790 assert( obj->is_forwarded(), "invariant" );
3791 *p = obj->forwardee();
3792 } else {
3793 assert(!obj->is_forwarded(), "invariant" );
3794 assert(cset_state.is_humongous(),
3795 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3796 _g1->set_humongous_is_live(obj);
3797 }
3798 }
3799 };
3800
3801 // Copying Keep Alive closure - can be called from both
3802 // serial and parallel code as long as different worker
3803 // threads utilize different G1ParScanThreadState instances
3804 // and different queues.
3805
3806 class G1CopyingKeepAliveClosure: public OopClosure {
3807 G1CollectedHeap* _g1h;
3808 OopClosure* _copy_non_heap_obj_cl;
3809 G1ParScanThreadState* _par_scan_state;
3810
3811 public:
3812 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3813 OopClosure* non_heap_obj_cl,
3814 G1ParScanThreadState* pss):
3815 _g1h(g1h),
3816 _copy_non_heap_obj_cl(non_heap_obj_cl),
3817 _par_scan_state(pss)
3818 {}
3819
3820 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3821 virtual void do_oop( oop* p) { do_oop_work(p); }
3822
3823 template <class T> void do_oop_work(T* p) {
3824 oop obj = oopDesc::load_decode_heap_oop(p);
3825
3826 if (_g1h->is_in_cset_or_humongous(obj)) {
3827 // If the referent object has been forwarded (either copied
3828 // to a new location or to itself in the event of an
3829 // evacuation failure) then we need to update the reference
3830 // field and, if both reference and referent are in the G1
3831 // heap, update the RSet for the referent.
3832 //
3833 // If the referent has not been forwarded then we have to keep
3834 // it alive by policy. Therefore we have copy the referent.
3835 //
3836 // If the reference field is in the G1 heap then we can push
3837 // on the PSS queue. When the queue is drained (after each
3838 // phase of reference processing) the object and it's followers
3839 // will be copied, the reference field set to point to the
3840 // new location, and the RSet updated. Otherwise we need to
3841 // use the the non-heap or metadata closures directly to copy
3842 // the referent object and update the pointer, while avoiding
3843 // updating the RSet.
3844
3845 if (_g1h->is_in_g1_reserved(p)) {
3846 _par_scan_state->push_on_queue(p);
3847 } else {
3848 assert(!Metaspace::contains((const void*)p),
3849 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3850 _copy_non_heap_obj_cl->do_oop(p);
3851 }
3852 }
3853 }
3854 };
3855
3856 // Serial drain queue closure. Called as the 'complete_gc'
3857 // closure for each discovered list in some of the
3858 // reference processing phases.
3859
3860 class G1STWDrainQueueClosure: public VoidClosure {
3861 protected:
3862 G1CollectedHeap* _g1h;
3863 G1ParScanThreadState* _par_scan_state;
3864
3865 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3866
3867 public:
3868 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3869 _g1h(g1h),
3870 _par_scan_state(pss)
3871 { }
3872
3873 void do_void() {
3874 G1ParScanThreadState* const pss = par_scan_state();
3875 pss->trim_queue();
3876 }
3877 };
3878
3879 // Parallel Reference Processing closures
3880
3881 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3882 // processing during G1 evacuation pauses.
3883
3884 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3885 private:
3886 G1CollectedHeap* _g1h;
3887 G1ParScanThreadStateSet* _pss;
3888 RefToScanQueueSet* _queues;
3889 WorkGang* _workers;
3890 uint _active_workers;
3891
3892 public:
3893 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3894 G1ParScanThreadStateSet* per_thread_states,
3895 WorkGang* workers,
3896 RefToScanQueueSet *task_queues,
3897 uint n_workers) :
3898 _g1h(g1h),
3899 _pss(per_thread_states),
3900 _queues(task_queues),
3901 _workers(workers),
3902 _active_workers(n_workers)
3903 {
3904 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3905 }
3906
3907 // Executes the given task using concurrent marking worker threads.
3908 virtual void execute(ProcessTask& task);
3909 virtual void execute(EnqueueTask& task);
3910 };
3911
3912 // Gang task for possibly parallel reference processing
3913
3914 class G1STWRefProcTaskProxy: public AbstractGangTask {
3915 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3916 ProcessTask& _proc_task;
3917 G1CollectedHeap* _g1h;
3918 G1ParScanThreadStateSet* _pss;
3919 RefToScanQueueSet* _task_queues;
3920 ParallelTaskTerminator* _terminator;
3921
3922 public:
3923 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3924 G1CollectedHeap* g1h,
3925 G1ParScanThreadStateSet* per_thread_states,
3926 RefToScanQueueSet *task_queues,
3927 ParallelTaskTerminator* terminator) :
3928 AbstractGangTask("Process reference objects in parallel"),
3929 _proc_task(proc_task),
3930 _g1h(g1h),
3931 _pss(per_thread_states),
3932 _task_queues(task_queues),
3933 _terminator(terminator)
3934 {}
3935
3936 virtual void work(uint worker_id) {
3937 // The reference processing task executed by a single worker.
3938 ResourceMark rm;
3939 HandleMark hm;
3940
3941 G1STWIsAliveClosure is_alive(_g1h);
3942
3943 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3944 pss->set_ref_processor(NULL);
3945
3946 // Keep alive closure.
3947 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3948
3949 // Complete GC closure
3950 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3951
3952 // Call the reference processing task's work routine.
3953 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3954
3955 // Note we cannot assert that the refs array is empty here as not all
3956 // of the processing tasks (specifically phase2 - pp2_work) execute
3957 // the complete_gc closure (which ordinarily would drain the queue) so
3958 // the queue may not be empty.
3959 }
3960 };
3961
3962 // Driver routine for parallel reference processing.
3963 // Creates an instance of the ref processing gang
3964 // task and has the worker threads execute it.
3965 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3966 assert(_workers != NULL, "Need parallel worker threads.");
3967
3968 ParallelTaskTerminator terminator(_active_workers, _queues);
3969 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3970
3971 _workers->run_task(&proc_task_proxy);
3972 }
3973
3974 // Gang task for parallel reference enqueueing.
3975
3976 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3977 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3978 EnqueueTask& _enq_task;
3979
3980 public:
3981 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3982 AbstractGangTask("Enqueue reference objects in parallel"),
3983 _enq_task(enq_task)
3984 { }
3985
3986 virtual void work(uint worker_id) {
3987 _enq_task.work(worker_id);
3988 }
3989 };
3990
3991 // Driver routine for parallel reference enqueueing.
3992 // Creates an instance of the ref enqueueing gang
3993 // task and has the worker threads execute it.
3994
3995 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
3996 assert(_workers != NULL, "Need parallel worker threads.");
3997
3998 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
3999
4000 _workers->run_task(&enq_task_proxy);
4001 }
4002
4003 // End of weak reference support closures
4004
4005 // Abstract task used to preserve (i.e. copy) any referent objects
4006 // that are in the collection set and are pointed to by reference
4007 // objects discovered by the CM ref processor.
4008
4009 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4010 protected:
4011 G1CollectedHeap* _g1h;
4012 G1ParScanThreadStateSet* _pss;
4013 RefToScanQueueSet* _queues;
4014 ParallelTaskTerminator _terminator;
4015 uint _n_workers;
4016
4017 public:
4018 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4019 AbstractGangTask("ParPreserveCMReferents"),
4020 _g1h(g1h),
4021 _pss(per_thread_states),
4022 _queues(task_queues),
4023 _terminator(workers, _queues),
4024 _n_workers(workers)
4025 {
4026 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4027 }
4028
4029 void work(uint worker_id) {
4030 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4031
4032 ResourceMark rm;
4033 HandleMark hm;
4034
4035 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4036 pss->set_ref_processor(NULL);
4037 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4038
4039 // Is alive closure
4040 G1AlwaysAliveClosure always_alive(_g1h);
4041
4042 // Copying keep alive closure. Applied to referent objects that need
4043 // to be copied.
4044 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4045
4046 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4047
4048 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4049 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4050
4051 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4052 // So this must be true - but assert just in case someone decides to
4053 // change the worker ids.
4054 assert(worker_id < limit, "sanity");
4055 assert(!rp->discovery_is_atomic(), "check this code");
4056
4057 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4058 for (uint idx = worker_id; idx < limit; idx += stride) {
4059 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4060
4061 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4062 while (iter.has_next()) {
4063 // Since discovery is not atomic for the CM ref processor, we
4064 // can see some null referent objects.
4065 iter.load_ptrs(DEBUG_ONLY(true));
4066 oop ref = iter.obj();
4067
4068 // This will filter nulls.
4069 if (iter.is_referent_alive()) {
4070 iter.make_referent_alive();
4071 }
4072 iter.move_to_next();
4073 }
4074 }
4075
4076 // Drain the queue - which may cause stealing
4077 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4078 drain_queue.do_void();
4079 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4080 assert(pss->queue_is_empty(), "should be");
4081 }
4082 };
4083
4084 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4085 // Any reference objects, in the collection set, that were 'discovered'
4086 // by the CM ref processor should have already been copied (either by
4087 // applying the external root copy closure to the discovered lists, or
4088 // by following an RSet entry).
4089 //
4090 // But some of the referents, that are in the collection set, that these
4091 // reference objects point to may not have been copied: the STW ref
4092 // processor would have seen that the reference object had already
4093 // been 'discovered' and would have skipped discovering the reference,
4094 // but would not have treated the reference object as a regular oop.
4095 // As a result the copy closure would not have been applied to the
4096 // referent object.
4097 //
4098 // We need to explicitly copy these referent objects - the references
4099 // will be processed at the end of remarking.
4100 //
4101 // We also need to do this copying before we process the reference
4102 // objects discovered by the STW ref processor in case one of these
4103 // referents points to another object which is also referenced by an
4104 // object discovered by the STW ref processor.
4105 double preserve_cm_referents_time = 0.0;
4106
4107 // To avoid spawning task when there is no work to do, check that
4108 // a concurrent cycle is active and that some references have been
4109 // discovered.
4110 if (concurrent_mark()->cm_thread()->during_cycle() &&
4111 ref_processor_cm()->has_discovered_references()) {
4112 double preserve_cm_referents_start = os::elapsedTime();
4113 uint no_of_gc_workers = workers()->active_workers();
4114 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4115 per_thread_states,
4116 no_of_gc_workers,
4117 _task_queues);
4118 workers()->run_task(&keep_cm_referents);
4119 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4120 }
4121
4122 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4123 }
4124
4125 // Weak Reference processing during an evacuation pause (part 1).
4126 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4127 double ref_proc_start = os::elapsedTime();
4128
4129 ReferenceProcessor* rp = _ref_processor_stw;
4130 assert(rp->discovery_enabled(), "should have been enabled");
4131
4132 // Closure to test whether a referent is alive.
4133 G1STWIsAliveClosure is_alive(this);
4134
4135 // Even when parallel reference processing is enabled, the processing
4136 // of JNI refs is serial and performed serially by the current thread
4137 // rather than by a worker. The following PSS will be used for processing
4138 // JNI refs.
4139
4140 // Use only a single queue for this PSS.
4141 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4142 pss->set_ref_processor(NULL);
4143 assert(pss->queue_is_empty(), "pre-condition");
4144
4145 // Keep alive closure.
4146 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4147
4148 // Serial Complete GC closure
4149 G1STWDrainQueueClosure drain_queue(this, pss);
4150
4151 // Setup the soft refs policy...
4152 rp->setup_policy(false);
4153
4154 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4155
4156 ReferenceProcessorStats stats;
4157 if (!rp->processing_is_mt()) {
4158 // Serial reference processing...
4159 stats = rp->process_discovered_references(&is_alive,
4160 &keep_alive,
4161 &drain_queue,
4162 NULL,
4163 pt);
4164 } else {
4165 uint no_of_gc_workers = workers()->active_workers();
4166
4167 // Parallel reference processing
4168 assert(no_of_gc_workers <= rp->max_num_q(),
4169 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4170 no_of_gc_workers, rp->max_num_q());
4171
4172 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4173 stats = rp->process_discovered_references(&is_alive,
4174 &keep_alive,
4175 &drain_queue,
4176 &par_task_executor,
4177 pt);
4178 }
4179
4180 _gc_tracer_stw->report_gc_reference_stats(stats);
4181
4182 // We have completed copying any necessary live referent objects.
4183 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4184
4185 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4186 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4187 }
4188
4189 // Weak Reference processing during an evacuation pause (part 2).
4190 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4191 double ref_enq_start = os::elapsedTime();
4192
4193 ReferenceProcessor* rp = _ref_processor_stw;
4194 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4195
4196 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4197
4198 // Now enqueue any remaining on the discovered lists on to
4199 // the pending list.
4200 if (!rp->processing_is_mt()) {
4201 // Serial reference processing...
4202 rp->enqueue_discovered_references(NULL, pt);
4203 } else {
4204 // Parallel reference enqueueing
4205
4206 uint n_workers = workers()->active_workers();
4207
4208 assert(n_workers <= rp->max_num_q(),
4209 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4210 n_workers, rp->max_num_q());
4211
4212 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4213 rp->enqueue_discovered_references(&par_task_executor, pt);
4214 }
4215
4216 rp->verify_no_references_recorded();
4217 assert(!rp->discovery_enabled(), "should have been disabled");
4218
4219 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4220 // ensure that it is marked in the bitmap for concurrent marking to discover.
4221 if (collector_state()->during_initial_mark_pause()) {
4222 oop pll_head = Universe::reference_pending_list();
4223 if (pll_head != NULL) {
4224 _cm->mark_in_next_bitmap(pll_head);
4225 }
4226 }
4227
4228 // FIXME
4229 // CM's reference processing also cleans up the string and symbol tables.
4230 // Should we do that here also? We could, but it is a serial operation
4231 // and could significantly increase the pause time.
4232
4233 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4234 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4235 }
4236
4237 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4238 double merge_pss_time_start = os::elapsedTime();
4239 per_thread_states->flush();
4240 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4241 }
4242
4243 void G1CollectedHeap::pre_evacuate_collection_set() {
4244 _expand_heap_after_alloc_failure = true;
4245 _evacuation_failed = false;
4246
4247 // Disable the hot card cache.
4248 _hot_card_cache->reset_hot_cache_claimed_index();
4249 _hot_card_cache->set_use_cache(false);
4250
4251 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4252 _preserved_marks_set.assert_empty();
4253
4254 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4255
4256 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4257 if (collector_state()->during_initial_mark_pause()) {
4258 double start_clear_claimed_marks = os::elapsedTime();
4259
4260 ClassLoaderDataGraph::clear_claimed_marks();
4261
4262 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4263 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4264 }
4265 }
4266
4267 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4268 // Should G1EvacuationFailureALot be in effect for this GC?
4269 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4270
4271 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4272
4273 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4274
4275 double start_par_time_sec = os::elapsedTime();
4276 double end_par_time_sec;
4277
4278 {
4279 const uint n_workers = workers()->active_workers();
4280 G1RootProcessor root_processor(this, n_workers);
4281 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4282
4283 print_termination_stats_hdr();
4284
4285 workers()->run_task(&g1_par_task);
4286 end_par_time_sec = os::elapsedTime();
4287
4288 // Closing the inner scope will execute the destructor
4289 // for the G1RootProcessor object. We record the current
4290 // elapsed time before closing the scope so that time
4291 // taken for the destructor is NOT included in the
4292 // reported parallel time.
4293 }
4294
4295 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4296 phase_times->record_par_time(par_time_ms);
4297
4298 double code_root_fixup_time_ms =
4299 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4300 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4301 }
4302
4303 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4304 // Process any discovered reference objects - we have
4305 // to do this _before_ we retire the GC alloc regions
4306 // as we may have to copy some 'reachable' referent
4307 // objects (and their reachable sub-graphs) that were
4308 // not copied during the pause.
4309 if (g1_policy()->should_process_references()) {
4310 preserve_cm_referents(per_thread_states);
4311 process_discovered_references(per_thread_states);
4312 } else {
4313 ref_processor_stw()->verify_no_references_recorded();
4314 }
4315
4316 G1STWIsAliveClosure is_alive(this);
4317 G1KeepAliveClosure keep_alive(this);
4318
4319 {
4320 double start = os::elapsedTime();
4321
4322 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4323
4324 double time_ms = (os::elapsedTime() - start) * 1000.0;
4325 g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4326 }
4327
4328 if (G1StringDedup::is_enabled()) {
4329 double fixup_start = os::elapsedTime();
4330
4331 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4332
4333 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4334 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4335 }
4336
4337 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4338
4339 if (evacuation_failed()) {
4340 restore_after_evac_failure();
4341
4342 // Reset the G1EvacuationFailureALot counters and flags
4343 // Note: the values are reset only when an actual
4344 // evacuation failure occurs.
4345 NOT_PRODUCT(reset_evacuation_should_fail();)
4346 }
4347
4348 _preserved_marks_set.assert_empty();
4349
4350 // Enqueue any remaining references remaining on the STW
4351 // reference processor's discovered lists. We need to do
4352 // this after the card table is cleaned (and verified) as
4353 // the act of enqueueing entries on to the pending list
4354 // will log these updates (and dirty their associated
4355 // cards). We need these updates logged to update any
4356 // RSets.
4357 if (g1_policy()->should_process_references()) {
4358 enqueue_discovered_references(per_thread_states);
4359 } else {
4360 g1_policy()->phase_times()->record_ref_enq_time(0);
4361 }
4362
4363 _allocator->release_gc_alloc_regions(evacuation_info);
4364
4365 merge_per_thread_state_info(per_thread_states);
4366
4367 // Reset and re-enable the hot card cache.
4368 // Note the counts for the cards in the regions in the
4369 // collection set are reset when the collection set is freed.
4370 _hot_card_cache->reset_hot_cache();
4371 _hot_card_cache->set_use_cache(true);
4372
4373 purge_code_root_memory();
4374
4375 redirty_logged_cards();
4376 #if COMPILER2_OR_JVMCI
4377 double start = os::elapsedTime();
4378 DerivedPointerTable::update_pointers();
4379 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4380 #endif
4381 g1_policy()->print_age_table();
4382 }
4383
4384 void G1CollectedHeap::record_obj_copy_mem_stats() {
4385 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4386
4387 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4388 create_g1_evac_summary(&_old_evac_stats));
4389 }
4390
4391 void G1CollectedHeap::free_region(HeapRegion* hr,
4392 FreeRegionList* free_list,
4393 bool skip_remset,
4394 bool skip_hot_card_cache,
4395 bool locked) {
4396 assert(!hr->is_free(), "the region should not be free");
4397 assert(!hr->is_empty(), "the region should not be empty");
4398 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4399 assert(free_list != NULL, "pre-condition");
4400
4401 if (G1VerifyBitmaps) {
4402 MemRegion mr(hr->bottom(), hr->end());
4403 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4404 }
4405
4406 // Clear the card counts for this region.
4407 // Note: we only need to do this if the region is not young
4408 // (since we don't refine cards in young regions).
4409 if (!skip_hot_card_cache && !hr->is_young()) {
4410 _hot_card_cache->reset_card_counts(hr);
4411 }
4412 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4413 free_list->add_ordered(hr);
4414 }
4415
4416 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4417 FreeRegionList* free_list,
4418 bool skip_remset) {
4419 assert(hr->is_humongous(), "this is only for humongous regions");
4420 assert(free_list != NULL, "pre-condition");
4421 hr->clear_humongous();
4422 free_region(hr, free_list, skip_remset);
4423 }
4424
4425 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4426 const uint humongous_regions_removed) {
4427 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4428 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4429 _old_set.bulk_remove(old_regions_removed);
4430 _humongous_set.bulk_remove(humongous_regions_removed);
4431 }
4432
4433 }
4434
4435 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4436 assert(list != NULL, "list can't be null");
4437 if (!list->is_empty()) {
4438 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4439 _hrm.insert_list_into_free_list(list);
4440 }
4441 }
4442
4443 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4444 decrease_used(bytes);
4445 }
4446
4447 class G1ParScrubRemSetTask: public AbstractGangTask {
4448 protected:
4449 G1RemSet* _g1rs;
4450 HeapRegionClaimer _hrclaimer;
4451
4452 public:
4453 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4454 AbstractGangTask("G1 ScrubRS"),
4455 _g1rs(g1_rs),
4456 _hrclaimer(num_workers) {
4457 }
4458
4459 void work(uint worker_id) {
4460 _g1rs->scrub(worker_id, &_hrclaimer);
4461 }
4462 };
4463
4464 void G1CollectedHeap::scrub_rem_set() {
4465 uint num_workers = workers()->active_workers();
4466 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4467 workers()->run_task(&g1_par_scrub_rs_task);
4468 }
4469
4470 class G1FreeCollectionSetTask : public AbstractGangTask {
4471 private:
4472
4473 // Closure applied to all regions in the collection set to do work that needs to
4474 // be done serially in a single thread.
4475 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4476 private:
4477 EvacuationInfo* _evacuation_info;
4478 const size_t* _surviving_young_words;
4479
4480 // Bytes used in successfully evacuated regions before the evacuation.
4481 size_t _before_used_bytes;
4482 // Bytes used in unsucessfully evacuated regions before the evacuation
4483 size_t _after_used_bytes;
4484
4485 size_t _bytes_allocated_in_old_since_last_gc;
4486
4487 size_t _failure_used_words;
4488 size_t _failure_waste_words;
4489
4490 FreeRegionList _local_free_list;
4491 public:
4492 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4493 HeapRegionClosure(),
4494 _evacuation_info(evacuation_info),
4495 _surviving_young_words(surviving_young_words),
4496 _before_used_bytes(0),
4497 _after_used_bytes(0),
4498 _bytes_allocated_in_old_since_last_gc(0),
4499 _failure_used_words(0),
4500 _failure_waste_words(0),
4501 _local_free_list("Local Region List for CSet Freeing") {
4502 }
4503
4504 virtual bool do_heap_region(HeapRegion* r) {
4505 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4506
4507 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4508 g1h->clear_in_cset(r);
4509
4510 if (r->is_young()) {
4511 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4512 "Young index %d is wrong for region %u of type %s with %u young regions",
4513 r->young_index_in_cset(),
4514 r->hrm_index(),
4515 r->get_type_str(),
4516 g1h->collection_set()->young_region_length());
4517 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4518 r->record_surv_words_in_group(words_survived);
4519 }
4520
4521 if (!r->evacuation_failed()) {
4522 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4523 _before_used_bytes += r->used();
4524 g1h->free_region(r,
4525 &_local_free_list,
4526 true, /* skip_remset */
4527 true, /* skip_hot_card_cache */
4528 true /* locked */);
4529 } else {
4530 r->uninstall_surv_rate_group();
4531 r->set_young_index_in_cset(-1);
4532 r->set_evacuation_failed(false);
4533 // When moving a young gen region to old gen, we "allocate" that whole region
4534 // there. This is in addition to any already evacuated objects. Notify the
4535 // policy about that.
4536 // Old gen regions do not cause an additional allocation: both the objects
4537 // still in the region and the ones already moved are accounted for elsewhere.
4538 if (r->is_young()) {
4539 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4540 }
4541 // The region is now considered to be old.
4542 r->set_old();
4543 // Do some allocation statistics accounting. Regions that failed evacuation
4544 // are always made old, so there is no need to update anything in the young
4545 // gen statistics, but we need to update old gen statistics.
4546 size_t used_words = r->marked_bytes() / HeapWordSize;
4547
4548 _failure_used_words += used_words;
4549 _failure_waste_words += HeapRegion::GrainWords - used_words;
4550
4551 g1h->old_set_add(r);
4552 _after_used_bytes += r->used();
4553 }
4554 return false;
4555 }
4556
4557 void complete_work() {
4558 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4559
4560 _evacuation_info->set_regions_freed(_local_free_list.length());
4561 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4562
4563 g1h->prepend_to_freelist(&_local_free_list);
4564 g1h->decrement_summary_bytes(_before_used_bytes);
4565
4566 G1Policy* policy = g1h->g1_policy();
4567 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4568
4569 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4570 }
4571 };
4572
4573 G1CollectionSet* _collection_set;
4574 G1SerialFreeCollectionSetClosure _cl;
4575 const size_t* _surviving_young_words;
4576
4577 size_t _rs_lengths;
4578
4579 volatile jint _serial_work_claim;
4580
4581 struct WorkItem {
4582 uint region_idx;
4583 bool is_young;
4584 bool evacuation_failed;
4585
4586 WorkItem(HeapRegion* r) {
4587 region_idx = r->hrm_index();
4588 is_young = r->is_young();
4589 evacuation_failed = r->evacuation_failed();
4590 }
4591 };
4592
4593 volatile size_t _parallel_work_claim;
4594 size_t _num_work_items;
4595 WorkItem* _work_items;
4596
4597 void do_serial_work() {
4598 // Need to grab the lock to be allowed to modify the old region list.
4599 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4600 _collection_set->iterate(&_cl);
4601 }
4602
4603 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4604 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4605
4606 HeapRegion* r = g1h->region_at(region_idx);
4607 assert(!g1h->is_on_master_free_list(r), "sanity");
4608
4609 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4610
4611 if (!is_young) {
4612 g1h->_hot_card_cache->reset_card_counts(r);
4613 }
4614
4615 if (!evacuation_failed) {
4616 r->rem_set()->clear_locked();
4617 }
4618 }
4619
4620 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4621 private:
4622 size_t _cur_idx;
4623 WorkItem* _work_items;
4624 public:
4625 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4626
4627 virtual bool do_heap_region(HeapRegion* r) {
4628 _work_items[_cur_idx++] = WorkItem(r);
4629 return false;
4630 }
4631 };
4632
4633 void prepare_work() {
4634 G1PrepareFreeCollectionSetClosure cl(_work_items);
4635 _collection_set->iterate(&cl);
4636 }
4637
4638 void complete_work() {
4639 _cl.complete_work();
4640
4641 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4642 policy->record_max_rs_lengths(_rs_lengths);
4643 policy->cset_regions_freed();
4644 }
4645 public:
4646 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4647 AbstractGangTask("G1 Free Collection Set"),
4648 _cl(evacuation_info, surviving_young_words),
4649 _collection_set(collection_set),
4650 _surviving_young_words(surviving_young_words),
4651 _serial_work_claim(0),
4652 _rs_lengths(0),
4653 _parallel_work_claim(0),
4654 _num_work_items(collection_set->region_length()),
4655 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4656 prepare_work();
4657 }
4658
4659 ~G1FreeCollectionSetTask() {
4660 complete_work();
4661 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4662 }
4663
4664 // Chunk size for work distribution. The chosen value has been determined experimentally
4665 // to be a good tradeoff between overhead and achievable parallelism.
4666 static uint chunk_size() { return 32; }
4667
4668 virtual void work(uint worker_id) {
4669 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4670
4671 // Claim serial work.
4672 if (_serial_work_claim == 0) {
4673 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4674 if (value == 0) {
4675 double serial_time = os::elapsedTime();
4676 do_serial_work();
4677 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4678 }
4679 }
4680
4681 // Start parallel work.
4682 double young_time = 0.0;
4683 bool has_young_time = false;
4684 double non_young_time = 0.0;
4685 bool has_non_young_time = false;
4686
4687 while (true) {
4688 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4689 size_t cur = end - chunk_size();
4690
4691 if (cur >= _num_work_items) {
4692 break;
4693 }
4694
4695 double start_time = os::elapsedTime();
4696
4697 end = MIN2(end, _num_work_items);
4698
4699 for (; cur < end; cur++) {
4700 bool is_young = _work_items[cur].is_young;
4701
4702 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4703
4704 double end_time = os::elapsedTime();
4705 double time_taken = end_time - start_time;
4706 if (is_young) {
4707 young_time += time_taken;
4708 has_young_time = true;
4709 } else {
4710 non_young_time += time_taken;
4711 has_non_young_time = true;
4712 }
4713 start_time = end_time;
4714 }
4715 }
4716
4717 if (has_young_time) {
4718 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4719 }
4720 if (has_non_young_time) {
4721 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4722 }
4723 }
4724 };
4725
4726 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4727 _eden.clear();
4728
4729 double free_cset_start_time = os::elapsedTime();
4730
4731 {
4732 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4733 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4734
4735 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4736
4737 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4738 cl.name(),
4739 num_workers,
4740 _collection_set.region_length());
4741 workers()->run_task(&cl, num_workers);
4742 }
4743 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4744
4745 collection_set->clear();
4746 }
4747
4748 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4749 private:
4750 FreeRegionList* _free_region_list;
4751 HeapRegionSet* _proxy_set;
4752 uint _humongous_objects_reclaimed;
4753 uint _humongous_regions_reclaimed;
4754 size_t _freed_bytes;
4755 public:
4756
4757 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4758 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4759 }
4760
4761 virtual bool do_heap_region(HeapRegion* r) {
4762 if (!r->is_starts_humongous()) {
4763 return false;
4764 }
4765
4766 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4767
4768 oop obj = (oop)r->bottom();
4769 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4770
4771 // The following checks whether the humongous object is live are sufficient.
4772 // The main additional check (in addition to having a reference from the roots
4773 // or the young gen) is whether the humongous object has a remembered set entry.
4774 //
4775 // A humongous object cannot be live if there is no remembered set for it
4776 // because:
4777 // - there can be no references from within humongous starts regions referencing
4778 // the object because we never allocate other objects into them.
4779 // (I.e. there are no intra-region references that may be missed by the
4780 // remembered set)
4781 // - as soon there is a remembered set entry to the humongous starts region
4782 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4783 // until the end of a concurrent mark.
4784 //
4785 // It is not required to check whether the object has been found dead by marking
4786 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4787 // all objects allocated during that time are considered live.
4788 // SATB marking is even more conservative than the remembered set.
4789 // So if at this point in the collection there is no remembered set entry,
4790 // nobody has a reference to it.
4791 // At the start of collection we flush all refinement logs, and remembered sets
4792 // are completely up-to-date wrt to references to the humongous object.
4793 //
4794 // Other implementation considerations:
4795 // - never consider object arrays at this time because they would pose
4796 // considerable effort for cleaning up the the remembered sets. This is
4797 // required because stale remembered sets might reference locations that
4798 // are currently allocated into.
4799 uint region_idx = r->hrm_index();
4800 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4801 !r->rem_set()->is_empty()) {
4802 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",
4803 region_idx,
4804 (size_t)obj->size() * HeapWordSize,
4805 p2i(r->bottom()),
4806 r->rem_set()->occupied(),
4807 r->rem_set()->strong_code_roots_list_length(),
4808 next_bitmap->is_marked(r->bottom()),
4809 g1h->is_humongous_reclaim_candidate(region_idx),
4810 obj->is_typeArray()
4811 );
4812 return false;
4813 }
4814
4815 guarantee(obj->is_typeArray(),
4816 "Only eagerly reclaiming type arrays is supported, but the object "
4817 PTR_FORMAT " is not.", p2i(r->bottom()));
4818
4819 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",
4820 region_idx,
4821 (size_t)obj->size() * HeapWordSize,
4822 p2i(r->bottom()),
4823 r->rem_set()->occupied(),
4824 r->rem_set()->strong_code_roots_list_length(),
4825 next_bitmap->is_marked(r->bottom()),
4826 g1h->is_humongous_reclaim_candidate(region_idx),
4827 obj->is_typeArray()
4828 );
4829
4830 // Need to clear mark bit of the humongous object if already set.
4831 if (next_bitmap->is_marked(r->bottom())) {
4832 next_bitmap->clear(r->bottom());
4833 }
4834 _humongous_objects_reclaimed++;
4835 do {
4836 HeapRegion* next = g1h->next_region_in_humongous(r);
4837 _freed_bytes += r->used();
4838 r->set_containing_set(NULL);
4839 _humongous_regions_reclaimed++;
4840 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4841 r = next;
4842 } while (r != NULL);
4843
4844 return false;
4845 }
4846
4847 uint humongous_objects_reclaimed() {
4848 return _humongous_objects_reclaimed;
4849 }
4850
4851 uint humongous_regions_reclaimed() {
4852 return _humongous_regions_reclaimed;
4853 }
4854
4855 size_t bytes_freed() const {
4856 return _freed_bytes;
4857 }
4858 };
4859
4860 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4861 assert_at_safepoint(true);
4862
4863 if (!G1EagerReclaimHumongousObjects ||
4864 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4865 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4866 return;
4867 }
4868
4869 double start_time = os::elapsedTime();
4870
4871 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4872
4873 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4874 heap_region_iterate(&cl);
4875
4876 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4877
4878 G1HRPrinter* hrp = hr_printer();
4879 if (hrp->is_active()) {
4880 FreeRegionListIterator iter(&local_cleanup_list);
4881 while (iter.more_available()) {
4882 HeapRegion* hr = iter.get_next();
4883 hrp->cleanup(hr);
4884 }
4885 }
4886
4887 prepend_to_freelist(&local_cleanup_list);
4888 decrement_summary_bytes(cl.bytes_freed());
4889
4890 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4891 cl.humongous_objects_reclaimed());
4892 }
4893
4894 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4895 public:
4896 virtual bool do_heap_region(HeapRegion* r) {
4897 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4898 G1CollectedHeap::heap()->clear_in_cset(r);
4899 r->set_young_index_in_cset(-1);
4900 return false;
4901 }
4902 };
4903
4904 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4905 G1AbandonCollectionSetClosure cl;
4906 collection_set->iterate(&cl);
4907
4908 collection_set->clear();
4909 collection_set->stop_incremental_building();
4910 }
4911
4912 void G1CollectedHeap::set_free_regions_coming() {
4913 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4914
4915 assert(!free_regions_coming(), "pre-condition");
4916 _free_regions_coming = true;
4917 }
4918
4919 void G1CollectedHeap::reset_free_regions_coming() {
4920 assert(free_regions_coming(), "pre-condition");
4921
4922 {
4923 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4924 _free_regions_coming = false;
4925 SecondaryFreeList_lock->notify_all();
4926 }
4927
4928 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4929 }
4930
4931 void G1CollectedHeap::wait_while_free_regions_coming() {
4932 // Most of the time we won't have to wait, so let's do a quick test
4933 // first before we take the lock.
4934 if (!free_regions_coming()) {
4935 return;
4936 }
4937
4938 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4939
4940 {
4941 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4942 while (free_regions_coming()) {
4943 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4944 }
4945 }
4946
4947 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4948 }
4949
4950 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4951 return _allocator->is_retained_old_region(hr);
4952 }
4953
4954 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4955 _eden.add(hr);
4956 _g1_policy->set_region_eden(hr);
4957 }
4958
4959 #ifdef ASSERT
4960
4961 class NoYoungRegionsClosure: public HeapRegionClosure {
4962 private:
4963 bool _success;
4964 public:
4965 NoYoungRegionsClosure() : _success(true) { }
4966 bool do_heap_region(HeapRegion* r) {
4967 if (r->is_young()) {
4968 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4969 p2i(r->bottom()), p2i(r->end()));
4970 _success = false;
4971 }
4972 return false;
4973 }
4974 bool success() { return _success; }
4975 };
4976
4977 bool G1CollectedHeap::check_young_list_empty() {
4978 bool ret = (young_regions_count() == 0);
4979
4980 NoYoungRegionsClosure closure;
4981 heap_region_iterate(&closure);
4982 ret = ret && closure.success();
4983
4984 return ret;
4985 }
4986
4987 #endif // ASSERT
4988
4989 class TearDownRegionSetsClosure : public HeapRegionClosure {
4990 private:
4991 HeapRegionSet *_old_set;
4992
4993 public:
4994 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4995
4996 bool do_heap_region(HeapRegion* r) {
4997 if (r->is_old()) {
4998 _old_set->remove(r);
4999 } else if(r->is_young()) {
5000 r->uninstall_surv_rate_group();
5001 } else {
5002 // We ignore free regions, we'll empty the free list afterwards.
5003 // We ignore humongous regions, we're not tearing down the
5004 // humongous regions set.
5005 assert(r->is_free() || r->is_humongous(),
5006 "it cannot be another type");
5007 }
5008 return false;
5009 }
5010
5011 ~TearDownRegionSetsClosure() {
5012 assert(_old_set->is_empty(), "post-condition");
5013 }
5014 };
5015
5016 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5017 assert_at_safepoint(true /* should_be_vm_thread */);
5018
5019 if (!free_list_only) {
5020 TearDownRegionSetsClosure cl(&_old_set);
5021 heap_region_iterate(&cl);
5022
5023 // Note that emptying the _young_list is postponed and instead done as
5024 // the first step when rebuilding the regions sets again. The reason for
5025 // this is that during a full GC string deduplication needs to know if
5026 // a collected region was young or old when the full GC was initiated.
5027 }
5028 _hrm.remove_all_free_regions();
5029 }
5030
5031 void G1CollectedHeap::increase_used(size_t bytes) {
5032 _summary_bytes_used += bytes;
5033 }
5034
5035 void G1CollectedHeap::decrease_used(size_t bytes) {
5036 assert(_summary_bytes_used >= bytes,
5037 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5038 _summary_bytes_used, bytes);
5039 _summary_bytes_used -= bytes;
5040 }
5041
5042 void G1CollectedHeap::set_used(size_t bytes) {
5043 _summary_bytes_used = bytes;
5044 }
5045
5046 class RebuildRegionSetsClosure : public HeapRegionClosure {
5047 private:
5048 bool _free_list_only;
5049 HeapRegionSet* _old_set;
5050 HeapRegionManager* _hrm;
5051 size_t _total_used;
5052
5053 public:
5054 RebuildRegionSetsClosure(bool free_list_only,
5055 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5056 _free_list_only(free_list_only),
5057 _old_set(old_set), _hrm(hrm), _total_used(0) {
5058 assert(_hrm->num_free_regions() == 0, "pre-condition");
5059 if (!free_list_only) {
5060 assert(_old_set->is_empty(), "pre-condition");
5061 }
5062 }
5063
5064 bool do_heap_region(HeapRegion* r) {
5065 if (r->is_empty()) {
5066 // Add free regions to the free list
5067 r->set_free();
5068 r->set_allocation_context(AllocationContext::system());
5069 _hrm->insert_into_free_list(r);
5070 } else if (!_free_list_only) {
5071
5072 if (r->is_humongous()) {
5073 // We ignore humongous regions. We left the humongous set unchanged.
5074 } else {
5075 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5076 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5077 r->move_to_old();
5078 _old_set->add(r);
5079 }
5080 _total_used += r->used();
5081 }
5082
5083 return false;
5084 }
5085
5086 size_t total_used() {
5087 return _total_used;
5088 }
5089 };
5090
5091 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5092 assert_at_safepoint(true /* should_be_vm_thread */);
5093
5094 if (!free_list_only) {
5095 _eden.clear();
5096 _survivor.clear();
5097 }
5098
5099 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5100 heap_region_iterate(&cl);
5101
5102 if (!free_list_only) {
5103 set_used(cl.total_used());
5104 if (_archive_allocator != NULL) {
5105 _archive_allocator->clear_used();
5106 }
5107 }
5108 assert(used_unlocked() == recalculate_used(),
5109 "inconsistent used_unlocked(), "
5110 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5111 used_unlocked(), recalculate_used());
5112 }
5113
5114 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5115 HeapRegion* hr = heap_region_containing(p);
5116 return hr->is_in(p);
5117 }
5118
5119 // Methods for the mutator alloc region
5120
5121 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5122 bool force) {
5123 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5124 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5125 if (force || should_allocate) {
5126 HeapRegion* new_alloc_region = new_region(word_size,
5127 false /* is_old */,
5128 false /* do_expand */);
5129 if (new_alloc_region != NULL) {
5130 set_region_short_lived_locked(new_alloc_region);
5131 _hr_printer.alloc(new_alloc_region, !should_allocate);
5132 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5133 return new_alloc_region;
5134 }
5135 }
5136 return NULL;
5137 }
5138
5139 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5140 size_t allocated_bytes) {
5141 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5142 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5143
5144 collection_set()->add_eden_region(alloc_region);
5145 increase_used(allocated_bytes);
5146 _hr_printer.retire(alloc_region);
5147 // We update the eden sizes here, when the region is retired,
5148 // instead of when it's allocated, since this is the point that its
5149 // used space has been recored in _summary_bytes_used.
5150 g1mm()->update_eden_size();
5151 }
5152
5153 // Methods for the GC alloc regions
5154
5155 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5156 if (dest.is_old()) {
5157 return true;
5158 } else {
5159 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5160 }
5161 }
5162
5163 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5164 assert(FreeList_lock->owned_by_self(), "pre-condition");
5165
5166 if (!has_more_regions(dest)) {
5167 return NULL;
5168 }
5169
5170 const bool is_survivor = dest.is_young();
5171
5172 HeapRegion* new_alloc_region = new_region(word_size,
5173 !is_survivor,
5174 true /* do_expand */);
5175 if (new_alloc_region != NULL) {
5176 // We really only need to do this for old regions given that we
5177 // should never scan survivors. But it doesn't hurt to do it
5178 // for survivors too.
5179 new_alloc_region->record_timestamp();
5180 if (is_survivor) {
5181 new_alloc_region->set_survivor();
5182 _survivor.add(new_alloc_region);
5183 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5184 } else {
5185 new_alloc_region->set_old();
5186 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5187 }
5188 _hr_printer.alloc(new_alloc_region);
5189 bool during_im = collector_state()->during_initial_mark_pause();
5190 new_alloc_region->note_start_of_copying(during_im);
5191 return new_alloc_region;
5192 }
5193 return NULL;
5194 }
5195
5196 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5197 size_t allocated_bytes,
5198 InCSetState dest) {
5199 bool during_im = collector_state()->during_initial_mark_pause();
5200 alloc_region->note_end_of_copying(during_im);
5201 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5202 if (dest.is_old()) {
5203 _old_set.add(alloc_region);
5204 }
5205 _hr_printer.retire(alloc_region);
5206 }
5207
5208 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5209 bool expanded = false;
5210 uint index = _hrm.find_highest_free(&expanded);
5211
5212 if (index != G1_NO_HRM_INDEX) {
5213 if (expanded) {
5214 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5215 HeapRegion::GrainWords * HeapWordSize);
5216 }
5217 _hrm.allocate_free_regions_starting_at(index, 1);
5218 return region_at(index);
5219 }
5220 return NULL;
5221 }
5222
5223 // Optimized nmethod scanning
5224
5225 class RegisterNMethodOopClosure: public OopClosure {
5226 G1CollectedHeap* _g1h;
5227 nmethod* _nm;
5228
5229 template <class T> void do_oop_work(T* p) {
5230 T heap_oop = oopDesc::load_heap_oop(p);
5231 if (!oopDesc::is_null(heap_oop)) {
5232 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5233 HeapRegion* hr = _g1h->heap_region_containing(obj);
5234 assert(!hr->is_continues_humongous(),
5235 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5236 " starting at " HR_FORMAT,
5237 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5238
5239 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5240 hr->add_strong_code_root_locked(_nm);
5241 }
5242 }
5243
5244 public:
5245 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5246 _g1h(g1h), _nm(nm) {}
5247
5248 void do_oop(oop* p) { do_oop_work(p); }
5249 void do_oop(narrowOop* p) { do_oop_work(p); }
5250 };
5251
5252 class UnregisterNMethodOopClosure: public OopClosure {
5253 G1CollectedHeap* _g1h;
5254 nmethod* _nm;
5255
5256 template <class T> void do_oop_work(T* p) {
5257 T heap_oop = oopDesc::load_heap_oop(p);
5258 if (!oopDesc::is_null(heap_oop)) {
5259 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5260 HeapRegion* hr = _g1h->heap_region_containing(obj);
5261 assert(!hr->is_continues_humongous(),
5262 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5263 " starting at " HR_FORMAT,
5264 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5265
5266 hr->remove_strong_code_root(_nm);
5267 }
5268 }
5269
5270 public:
5271 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5272 _g1h(g1h), _nm(nm) {}
5273
5274 void do_oop(oop* p) { do_oop_work(p); }
5275 void do_oop(narrowOop* p) { do_oop_work(p); }
5276 };
5277
5278 // Returns true if the reference points to an object that
5279 // can move in an incremental collection.
5280 bool G1CollectedHeap::is_scavengable(oop obj) {
5281 HeapRegion* hr = heap_region_containing(obj);
5282 return !hr->is_pinned();
5283 }
5284
5285 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5286 guarantee(nm != NULL, "sanity");
5287 RegisterNMethodOopClosure reg_cl(this, nm);
5288 nm->oops_do(®_cl);
5289 }
5290
5291 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5292 guarantee(nm != NULL, "sanity");
5293 UnregisterNMethodOopClosure reg_cl(this, nm);
5294 nm->oops_do(®_cl, true);
5295 }
5296
5297 void G1CollectedHeap::purge_code_root_memory() {
5298 double purge_start = os::elapsedTime();
5299 G1CodeRootSet::purge();
5300 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5301 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5302 }
5303
5304 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5305 G1CollectedHeap* _g1h;
5306
5307 public:
5308 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5309 _g1h(g1h) {}
5310
5311 void do_code_blob(CodeBlob* cb) {
5312 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5313 if (nm == NULL) {
5314 return;
5315 }
5316
5317 if (ScavengeRootsInCode) {
5318 _g1h->register_nmethod(nm);
5319 }
5320 }
5321 };
5322
5323 void G1CollectedHeap::rebuild_strong_code_roots() {
5324 RebuildStrongCodeRootClosure blob_cl(this);
5325 CodeCache::blobs_do(&blob_cl);
5326 }
5327
5328 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5329 GrowableArray<GCMemoryManager*> memory_managers(2);
5330 memory_managers.append(&_memory_manager);
5331 memory_managers.append(&_full_gc_memory_manager);
5332 return memory_managers;
5333 }
5334
5335 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5336 GrowableArray<MemoryPool*> memory_pools(3);
5337 memory_pools.append(_eden_pool);
5338 memory_pools.append(_survivor_pool);
5339 memory_pools.append(_old_pool);
5340 return memory_pools;
5341 }