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 soft_ref_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(!soft_ref_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 _soft_ref_policy(),
1467 _memory_manager("G1 Young Generation", "end of minor GC"),
1468 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1469 _eden_pool(NULL),
1470 _survivor_pool(NULL),
1471 _old_pool(NULL),
1472 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1473 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1474 _g1_policy(create_g1_policy(_gc_timer_stw)),
1475 _collection_set(this, _g1_policy),
1476 _dirty_card_queue_set(false),
1477 _is_alive_closure_cm(this),
1478 _is_alive_closure_stw(this),
1479 _ref_processor_cm(NULL),
1480 _ref_processor_stw(NULL),
1481 _bot(NULL),
1482 _hot_card_cache(NULL),
1483 _g1_rem_set(NULL),
1484 _cr(NULL),
1485 _g1mm(NULL),
1486 _preserved_marks_set(true /* in_c_heap */),
1487 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1488 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1489 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1490 _humongous_reclaim_candidates(),
1491 _has_humongous_reclaim_candidates(false),
1492 _archive_allocator(NULL),
1493 _free_regions_coming(false),
1494 _gc_time_stamp(0),
1495 _summary_bytes_used(0),
1496 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1497 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1498 _expand_heap_after_alloc_failure(true),
1499 _old_marking_cycles_started(0),
1500 _old_marking_cycles_completed(0),
1501 _in_cset_fast_test() {
1502
1503 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1504 /* are_GC_task_threads */true,
1505 /* are_ConcurrentGC_threads */false);
1506 _workers->initialize_workers();
1507 _verifier = new G1HeapVerifier(this);
1508
1509 _allocator = G1Allocator::create_allocator(this);
1510
1511 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1512
1513 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1514
1515 // Override the default _filler_array_max_size so that no humongous filler
1516 // objects are created.
1517 _filler_array_max_size = _humongous_object_threshold_in_words;
1518
1519 uint n_queues = ParallelGCThreads;
1520 _task_queues = new RefToScanQueueSet(n_queues);
1521
1522 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1523
1524 for (uint i = 0; i < n_queues; i++) {
1525 RefToScanQueue* q = new RefToScanQueue();
1526 q->initialize();
1527 _task_queues->register_queue(i, q);
1528 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1529 }
1530
1531 // Initialize the G1EvacuationFailureALot counters and flags.
1532 NOT_PRODUCT(reset_evacuation_should_fail();)
1533
1534 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1535 }
1536
1537 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1538 size_t size,
1539 size_t translation_factor) {
1540 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1541 // Allocate a new reserved space, preferring to use large pages.
1542 ReservedSpace rs(size, preferred_page_size);
1543 G1RegionToSpaceMapper* result =
1544 G1RegionToSpaceMapper::create_mapper(rs,
1545 size,
1546 rs.alignment(),
1547 HeapRegion::GrainBytes,
1548 translation_factor,
1549 mtGC);
1550
1551 os::trace_page_sizes_for_requested_size(description,
1552 size,
1553 preferred_page_size,
1554 rs.alignment(),
1555 rs.base(),
1556 rs.size());
1557
1558 return result;
1559 }
1560
1561 jint G1CollectedHeap::initialize_concurrent_refinement() {
1562 jint ecode = JNI_OK;
1563 _cr = G1ConcurrentRefine::create(&ecode);
1564 return ecode;
1565 }
1566
1567 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1568 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1569 if (_young_gen_sampling_thread->osthread() == NULL) {
1570 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1571 return JNI_ENOMEM;
1572 }
1573 return JNI_OK;
1574 }
1575
1576 jint G1CollectedHeap::initialize() {
1577 os::enable_vtime();
1578
1579 // Necessary to satisfy locking discipline assertions.
1580
1581 MutexLocker x(Heap_lock);
1582
1583 // While there are no constraints in the GC code that HeapWordSize
1584 // be any particular value, there are multiple other areas in the
1585 // system which believe this to be true (e.g. oop->object_size in some
1586 // cases incorrectly returns the size in wordSize units rather than
1587 // HeapWordSize).
1588 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1589
1590 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1591 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1592 size_t heap_alignment = collector_policy()->heap_alignment();
1593
1594 // Ensure that the sizes are properly aligned.
1595 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1596 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1597 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1598
1599 // Reserve the maximum.
1600
1601 // When compressed oops are enabled, the preferred heap base
1602 // is calculated by subtracting the requested size from the
1603 // 32Gb boundary and using the result as the base address for
1604 // heap reservation. If the requested size is not aligned to
1605 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1606 // into the ReservedHeapSpace constructor) then the actual
1607 // base of the reserved heap may end up differing from the
1608 // address that was requested (i.e. the preferred heap base).
1609 // If this happens then we could end up using a non-optimal
1610 // compressed oops mode.
1611
1612 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1613 heap_alignment);
1614
1615 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1616
1617 // Create the barrier set for the entire reserved region.
1618 G1SATBCardTableLoggingModRefBS* bs
1619 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1620 bs->initialize();
1621 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1622 set_barrier_set(bs);
1623
1624 // Create the hot card cache.
1625 _hot_card_cache = new G1HotCardCache(this);
1626
1627 // Carve out the G1 part of the heap.
1628 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1629 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1630 G1RegionToSpaceMapper* heap_storage =
1631 G1RegionToSpaceMapper::create_mapper(g1_rs,
1632 g1_rs.size(),
1633 page_size,
1634 HeapRegion::GrainBytes,
1635 1,
1636 mtJavaHeap);
1637 os::trace_page_sizes("Heap",
1638 collector_policy()->min_heap_byte_size(),
1639 max_byte_size,
1640 page_size,
1641 heap_rs.base(),
1642 heap_rs.size());
1643 heap_storage->set_mapping_changed_listener(&_listener);
1644
1645 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1646 G1RegionToSpaceMapper* bot_storage =
1647 create_aux_memory_mapper("Block Offset Table",
1648 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1649 G1BlockOffsetTable::heap_map_factor());
1650
1651 G1RegionToSpaceMapper* cardtable_storage =
1652 create_aux_memory_mapper("Card Table",
1653 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1654 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1655
1656 G1RegionToSpaceMapper* card_counts_storage =
1657 create_aux_memory_mapper("Card Counts Table",
1658 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1659 G1CardCounts::heap_map_factor());
1660
1661 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1662 G1RegionToSpaceMapper* prev_bitmap_storage =
1663 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1664 G1RegionToSpaceMapper* next_bitmap_storage =
1665 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1666
1667 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1668 g1_barrier_set()->initialize(cardtable_storage);
1669 // Do later initialization work for concurrent refinement.
1670 _hot_card_cache->initialize(card_counts_storage);
1671
1672 // 6843694 - ensure that the maximum region index can fit
1673 // in the remembered set structures.
1674 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1675 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1676
1677 // Also create a G1 rem set.
1678 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1679 _g1_rem_set->initialize(max_capacity(), max_regions());
1680
1681 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1682 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1683 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1684 "too many cards per region");
1685
1686 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1687
1688 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1689
1690 {
1691 HeapWord* start = _hrm.reserved().start();
1692 HeapWord* end = _hrm.reserved().end();
1693 size_t granularity = HeapRegion::GrainBytes;
1694
1695 _in_cset_fast_test.initialize(start, end, granularity);
1696 _humongous_reclaim_candidates.initialize(start, end, granularity);
1697 }
1698
1699 // Create the G1ConcurrentMark data structure and thread.
1700 // (Must do this late, so that "max_regions" is defined.)
1701 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1702 if (_cm == NULL || !_cm->completed_initialization()) {
1703 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1704 return JNI_ENOMEM;
1705 }
1706 _cmThread = _cm->cm_thread();
1707
1708 // Now expand into the initial heap size.
1709 if (!expand(init_byte_size, _workers)) {
1710 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1711 return JNI_ENOMEM;
1712 }
1713
1714 // Perform any initialization actions delegated to the policy.
1715 g1_policy()->init(this, &_collection_set);
1716
1717 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1718 SATB_Q_FL_lock,
1719 G1SATBProcessCompletedThreshold,
1720 Shared_SATB_Q_lock);
1721
1722 jint ecode = initialize_concurrent_refinement();
1723 if (ecode != JNI_OK) {
1724 return ecode;
1725 }
1726
1727 ecode = initialize_young_gen_sampling_thread();
1728 if (ecode != JNI_OK) {
1729 return ecode;
1730 }
1731
1732 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1733 DirtyCardQ_FL_lock,
1734 (int)concurrent_refine()->yellow_zone(),
1735 (int)concurrent_refine()->red_zone(),
1736 Shared_DirtyCardQ_lock,
1737 NULL, // fl_owner
1738 true); // init_free_ids
1739
1740 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1741 DirtyCardQ_FL_lock,
1742 -1, // never trigger processing
1743 -1, // no limit on length
1744 Shared_DirtyCardQ_lock,
1745 &JavaThread::dirty_card_queue_set());
1746
1747 // Here we allocate the dummy HeapRegion that is required by the
1748 // G1AllocRegion class.
1749 HeapRegion* dummy_region = _hrm.get_dummy_region();
1750
1751 // We'll re-use the same region whether the alloc region will
1752 // require BOT updates or not and, if it doesn't, then a non-young
1753 // region will complain that it cannot support allocations without
1754 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1755 dummy_region->set_eden();
1756 // Make sure it's full.
1757 dummy_region->set_top(dummy_region->end());
1758 G1AllocRegion::setup(this, dummy_region);
1759
1760 _allocator->init_mutator_alloc_region();
1761
1762 // Do create of the monitoring and management support so that
1763 // values in the heap have been properly initialized.
1764 _g1mm = new G1MonitoringSupport(this);
1765
1766 G1StringDedup::initialize();
1767
1768 _preserved_marks_set.init(ParallelGCThreads);
1769
1770 _collection_set.initialize(max_regions());
1771
1772 return JNI_OK;
1773 }
1774
1775 void G1CollectedHeap::initialize_serviceability() {
1776 _eden_pool = new G1EdenPool(this);
1777 _survivor_pool = new G1SurvivorPool(this);
1778 _old_pool = new G1OldGenPool(this);
1779
1780 _full_gc_memory_manager.add_pool(_eden_pool);
1781 _full_gc_memory_manager.add_pool(_survivor_pool);
1782 _full_gc_memory_manager.add_pool(_old_pool);
1783
1784 _memory_manager.add_pool(_eden_pool);
1785 _memory_manager.add_pool(_survivor_pool);
1786
1787 }
1788
1789 void G1CollectedHeap::stop() {
1790 // Stop all concurrent threads. We do this to make sure these threads
1791 // do not continue to execute and access resources (e.g. logging)
1792 // that are destroyed during shutdown.
1793 _cr->stop();
1794 _young_gen_sampling_thread->stop();
1795 _cmThread->stop();
1796 if (G1StringDedup::is_enabled()) {
1797 G1StringDedup::stop();
1798 }
1799 }
1800
1801 void G1CollectedHeap::safepoint_synchronize_begin() {
1802 SuspendibleThreadSet::synchronize();
1803 }
1804
1805 void G1CollectedHeap::safepoint_synchronize_end() {
1806 SuspendibleThreadSet::desynchronize();
1807 }
1808
1809 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1810 return HeapRegion::max_region_size();
1811 }
1812
1813 void G1CollectedHeap::post_initialize() {
1814 CollectedHeap::post_initialize();
1815 ref_processing_init();
1816 }
1817
1818 void G1CollectedHeap::ref_processing_init() {
1819 // Reference processing in G1 currently works as follows:
1820 //
1821 // * There are two reference processor instances. One is
1822 // used to record and process discovered references
1823 // during concurrent marking; the other is used to
1824 // record and process references during STW pauses
1825 // (both full and incremental).
1826 // * Both ref processors need to 'span' the entire heap as
1827 // the regions in the collection set may be dotted around.
1828 //
1829 // * For the concurrent marking ref processor:
1830 // * Reference discovery is enabled at initial marking.
1831 // * Reference discovery is disabled and the discovered
1832 // references processed etc during remarking.
1833 // * Reference discovery is MT (see below).
1834 // * Reference discovery requires a barrier (see below).
1835 // * Reference processing may or may not be MT
1836 // (depending on the value of ParallelRefProcEnabled
1837 // and ParallelGCThreads).
1838 // * A full GC disables reference discovery by the CM
1839 // ref processor and abandons any entries on it's
1840 // discovered lists.
1841 //
1842 // * For the STW processor:
1843 // * Non MT discovery is enabled at the start of a full GC.
1844 // * Processing and enqueueing during a full GC is non-MT.
1845 // * During a full GC, references are processed after marking.
1846 //
1847 // * Discovery (may or may not be MT) is enabled at the start
1848 // of an incremental evacuation pause.
1849 // * References are processed near the end of a STW evacuation pause.
1850 // * For both types of GC:
1851 // * Discovery is atomic - i.e. not concurrent.
1852 // * Reference discovery will not need a barrier.
1853
1854 MemRegion mr = reserved_region();
1855
1856 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1857
1858 // Concurrent Mark ref processor
1859 _ref_processor_cm =
1860 new ReferenceProcessor(mr, // span
1861 mt_processing,
1862 // mt processing
1863 ParallelGCThreads,
1864 // degree of mt processing
1865 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1866 // mt discovery
1867 MAX2(ParallelGCThreads, ConcGCThreads),
1868 // degree of mt discovery
1869 false,
1870 // Reference discovery is not atomic
1871 &_is_alive_closure_cm);
1872 // is alive closure
1873 // (for efficiency/performance)
1874
1875 // STW ref processor
1876 _ref_processor_stw =
1877 new ReferenceProcessor(mr, // span
1878 mt_processing,
1879 // mt processing
1880 ParallelGCThreads,
1881 // degree of mt processing
1882 (ParallelGCThreads > 1),
1883 // mt discovery
1884 ParallelGCThreads,
1885 // degree of mt discovery
1886 true,
1887 // Reference discovery is atomic
1888 &_is_alive_closure_stw);
1889 // is alive closure
1890 // (for efficiency/performance)
1891 }
1892
1893 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1894 return _collector_policy;
1895 }
1896
1897 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1898 return &_soft_ref_policy;
1899 }
1900
1901 size_t G1CollectedHeap::capacity() const {
1902 return _hrm.length() * HeapRegion::GrainBytes;
1903 }
1904
1905 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1906 return _hrm.total_free_bytes();
1907 }
1908
1909 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1910 hr->reset_gc_time_stamp();
1911 }
1912
1913 #ifndef PRODUCT
1914
1915 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1916 private:
1917 unsigned _gc_time_stamp;
1918 bool _failures;
1919
1920 public:
1921 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1922 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1923
1924 virtual bool do_heap_region(HeapRegion* hr) {
1925 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1926 if (_gc_time_stamp != region_gc_time_stamp) {
1927 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1928 region_gc_time_stamp, _gc_time_stamp);
1929 _failures = true;
1930 }
1931 return false;
1932 }
1933
1934 bool failures() { return _failures; }
1935 };
1936
1937 void G1CollectedHeap::check_gc_time_stamps() {
1938 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1939 heap_region_iterate(&cl);
1940 guarantee(!cl.failures(), "all GC time stamps should have been reset");
1941 }
1942 #endif // PRODUCT
1943
1944 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1945 _hot_card_cache->drain(cl, worker_i);
1946 }
1947
1948 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1949 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1950 size_t n_completed_buffers = 0;
1951 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1952 n_completed_buffers++;
1953 }
1954 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1955 dcqs.clear_n_completed_buffers();
1956 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1957 }
1958
1959 // Computes the sum of the storage used by the various regions.
1960 size_t G1CollectedHeap::used() const {
1961 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1962 if (_archive_allocator != NULL) {
1963 result += _archive_allocator->used();
1964 }
1965 return result;
1966 }
1967
1968 size_t G1CollectedHeap::used_unlocked() const {
1969 return _summary_bytes_used;
1970 }
1971
1972 class SumUsedClosure: public HeapRegionClosure {
1973 size_t _used;
1974 public:
1975 SumUsedClosure() : _used(0) {}
1976 bool do_heap_region(HeapRegion* r) {
1977 _used += r->used();
1978 return false;
1979 }
1980 size_t result() { return _used; }
1981 };
1982
1983 size_t G1CollectedHeap::recalculate_used() const {
1984 double recalculate_used_start = os::elapsedTime();
1985
1986 SumUsedClosure blk;
1987 heap_region_iterate(&blk);
1988
1989 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1990 return blk.result();
1991 }
1992
1993 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1994 switch (cause) {
1995 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1996 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1997 case GCCause::_update_allocation_context_stats_inc: return true;
1998 case GCCause::_wb_conc_mark: return true;
1999 default : return false;
2000 }
2001 }
2002
2003 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2004 switch (cause) {
2005 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2006 case GCCause::_g1_humongous_allocation: return true;
2007 default: return is_user_requested_concurrent_full_gc(cause);
2008 }
2009 }
2010
2011 #ifndef PRODUCT
2012 void G1CollectedHeap::allocate_dummy_regions() {
2013 // Let's fill up most of the region
2014 size_t word_size = HeapRegion::GrainWords - 1024;
2015 // And as a result the region we'll allocate will be humongous.
2016 guarantee(is_humongous(word_size), "sanity");
2017
2018 // _filler_array_max_size is set to humongous object threshold
2019 // but temporarily change it to use CollectedHeap::fill_with_object().
2020 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2021
2022 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2023 // Let's use the existing mechanism for the allocation
2024 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2025 AllocationContext::system());
2026 if (dummy_obj != NULL) {
2027 MemRegion mr(dummy_obj, word_size);
2028 CollectedHeap::fill_with_object(mr);
2029 } else {
2030 // If we can't allocate once, we probably cannot allocate
2031 // again. Let's get out of the loop.
2032 break;
2033 }
2034 }
2035 }
2036 #endif // !PRODUCT
2037
2038 void G1CollectedHeap::increment_old_marking_cycles_started() {
2039 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2040 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2041 "Wrong marking cycle count (started: %d, completed: %d)",
2042 _old_marking_cycles_started, _old_marking_cycles_completed);
2043
2044 _old_marking_cycles_started++;
2045 }
2046
2047 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2048 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2049
2050 // We assume that if concurrent == true, then the caller is a
2051 // concurrent thread that was joined the Suspendible Thread
2052 // Set. If there's ever a cheap way to check this, we should add an
2053 // assert here.
2054
2055 // Given that this method is called at the end of a Full GC or of a
2056 // concurrent cycle, and those can be nested (i.e., a Full GC can
2057 // interrupt a concurrent cycle), the number of full collections
2058 // completed should be either one (in the case where there was no
2059 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2060 // behind the number of full collections started.
2061
2062 // This is the case for the inner caller, i.e. a Full GC.
2063 assert(concurrent ||
2064 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2065 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2066 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2067 "is inconsistent with _old_marking_cycles_completed = %u",
2068 _old_marking_cycles_started, _old_marking_cycles_completed);
2069
2070 // This is the case for the outer caller, i.e. the concurrent cycle.
2071 assert(!concurrent ||
2072 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2073 "for outer caller (concurrent cycle): "
2074 "_old_marking_cycles_started = %u "
2075 "is inconsistent with _old_marking_cycles_completed = %u",
2076 _old_marking_cycles_started, _old_marking_cycles_completed);
2077
2078 _old_marking_cycles_completed += 1;
2079
2080 // We need to clear the "in_progress" flag in the CM thread before
2081 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2082 // is set) so that if a waiter requests another System.gc() it doesn't
2083 // incorrectly see that a marking cycle is still in progress.
2084 if (concurrent) {
2085 _cmThread->set_idle();
2086 }
2087
2088 // This notify_all() will ensure that a thread that called
2089 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2090 // and it's waiting for a full GC to finish will be woken up. It is
2091 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2092 FullGCCount_lock->notify_all();
2093 }
2094
2095 void G1CollectedHeap::collect(GCCause::Cause cause) {
2096 assert_heap_not_locked();
2097
2098 uint gc_count_before;
2099 uint old_marking_count_before;
2100 uint full_gc_count_before;
2101 bool retry_gc;
2102
2103 do {
2104 retry_gc = false;
2105
2106 {
2107 MutexLocker ml(Heap_lock);
2108
2109 // Read the GC count while holding the Heap_lock
2110 gc_count_before = total_collections();
2111 full_gc_count_before = total_full_collections();
2112 old_marking_count_before = _old_marking_cycles_started;
2113 }
2114
2115 if (should_do_concurrent_full_gc(cause)) {
2116 // Schedule an initial-mark evacuation pause that will start a
2117 // concurrent cycle. We're setting word_size to 0 which means that
2118 // we are not requesting a post-GC allocation.
2119 VM_G1CollectForAllocation op(0, /* word_size */
2120 gc_count_before,
2121 cause,
2122 true, /* should_initiate_conc_mark */
2123 g1_policy()->max_pause_time_ms(),
2124 AllocationContext::current());
2125 VMThread::execute(&op);
2126 if (!op.pause_succeeded()) {
2127 if (old_marking_count_before == _old_marking_cycles_started) {
2128 retry_gc = op.should_retry_gc();
2129 } else {
2130 // A Full GC happened while we were trying to schedule the
2131 // initial-mark GC. No point in starting a new cycle given
2132 // that the whole heap was collected anyway.
2133 }
2134
2135 if (retry_gc) {
2136 if (GCLocker::is_active_and_needs_gc()) {
2137 GCLocker::stall_until_clear();
2138 }
2139 }
2140 }
2141 } else {
2142 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2143 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2144
2145 // Schedule a standard evacuation pause. We're setting word_size
2146 // to 0 which means that we are not requesting a post-GC allocation.
2147 VM_G1CollectForAllocation op(0, /* word_size */
2148 gc_count_before,
2149 cause,
2150 false, /* should_initiate_conc_mark */
2151 g1_policy()->max_pause_time_ms(),
2152 AllocationContext::current());
2153 VMThread::execute(&op);
2154 } else {
2155 // Schedule a Full GC.
2156 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2157 VMThread::execute(&op);
2158 }
2159 }
2160 } while (retry_gc);
2161 }
2162
2163 bool G1CollectedHeap::is_in(const void* p) const {
2164 if (_hrm.reserved().contains(p)) {
2165 // Given that we know that p is in the reserved space,
2166 // heap_region_containing() should successfully
2167 // return the containing region.
2168 HeapRegion* hr = heap_region_containing(p);
2169 return hr->is_in(p);
2170 } else {
2171 return false;
2172 }
2173 }
2174
2175 #ifdef ASSERT
2176 bool G1CollectedHeap::is_in_exact(const void* p) const {
2177 bool contains = reserved_region().contains(p);
2178 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2179 if (contains && available) {
2180 return true;
2181 } else {
2182 return false;
2183 }
2184 }
2185 #endif
2186
2187 // Iteration functions.
2188
2189 // Iterates an ObjectClosure over all objects within a HeapRegion.
2190
2191 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2192 ObjectClosure* _cl;
2193 public:
2194 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2195 bool do_heap_region(HeapRegion* r) {
2196 if (!r->is_continues_humongous()) {
2197 r->object_iterate(_cl);
2198 }
2199 return false;
2200 }
2201 };
2202
2203 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2204 IterateObjectClosureRegionClosure blk(cl);
2205 heap_region_iterate(&blk);
2206 }
2207
2208 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2209 _hrm.iterate(cl);
2210 }
2211
2212 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2213 HeapRegionClaimer *hrclaimer,
2214 uint worker_id) const {
2215 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2216 }
2217
2218 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2219 HeapRegionClaimer *hrclaimer) const {
2220 _hrm.par_iterate(cl, hrclaimer, 0);
2221 }
2222
2223 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2224 _collection_set.iterate(cl);
2225 }
2226
2227 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2228 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2229 }
2230
2231 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2232 HeapRegion* hr = heap_region_containing(addr);
2233 return hr->block_start(addr);
2234 }
2235
2236 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2237 HeapRegion* hr = heap_region_containing(addr);
2238 return hr->block_size(addr);
2239 }
2240
2241 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2242 HeapRegion* hr = heap_region_containing(addr);
2243 return hr->block_is_obj(addr);
2244 }
2245
2246 bool G1CollectedHeap::supports_tlab_allocation() const {
2247 return true;
2248 }
2249
2250 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2251 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2252 }
2253
2254 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2255 return _eden.length() * HeapRegion::GrainBytes;
2256 }
2257
2258 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2259 // must be equal to the humongous object limit.
2260 size_t G1CollectedHeap::max_tlab_size() const {
2261 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2262 }
2263
2264 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2265 AllocationContext_t context = AllocationContext::current();
2266 return _allocator->unsafe_max_tlab_alloc(context);
2267 }
2268
2269 size_t G1CollectedHeap::max_capacity() const {
2270 return _hrm.reserved().byte_size();
2271 }
2272
2273 jlong G1CollectedHeap::millis_since_last_gc() {
2274 // See the notes in GenCollectedHeap::millis_since_last_gc()
2275 // for more information about the implementation.
2276 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2277 _g1_policy->collection_pause_end_millis();
2278 if (ret_val < 0) {
2279 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2280 ". returning zero instead.", ret_val);
2281 return 0;
2282 }
2283 return ret_val;
2284 }
2285
2286 void G1CollectedHeap::prepare_for_verify() {
2287 _verifier->prepare_for_verify();
2288 }
2289
2290 void G1CollectedHeap::verify(VerifyOption vo) {
2291 _verifier->verify(vo);
2292 }
2293
2294 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2295 return true;
2296 }
2297
2298 const char* const* G1CollectedHeap::concurrent_phases() const {
2299 return _cmThread->concurrent_phases();
2300 }
2301
2302 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2303 return _cmThread->request_concurrent_phase(phase);
2304 }
2305
2306 class PrintRegionClosure: public HeapRegionClosure {
2307 outputStream* _st;
2308 public:
2309 PrintRegionClosure(outputStream* st) : _st(st) {}
2310 bool do_heap_region(HeapRegion* r) {
2311 r->print_on(_st);
2312 return false;
2313 }
2314 };
2315
2316 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2317 const HeapRegion* hr,
2318 const VerifyOption vo) const {
2319 switch (vo) {
2320 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2321 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2322 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2323 default: ShouldNotReachHere();
2324 }
2325 return false; // keep some compilers happy
2326 }
2327
2328 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2329 const VerifyOption vo) const {
2330 switch (vo) {
2331 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2332 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2333 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2334 default: ShouldNotReachHere();
2335 }
2336 return false; // keep some compilers happy
2337 }
2338
2339 void G1CollectedHeap::print_heap_regions() const {
2340 LogTarget(Trace, gc, heap, region) lt;
2341 if (lt.is_enabled()) {
2342 LogStream ls(lt);
2343 print_regions_on(&ls);
2344 }
2345 }
2346
2347 void G1CollectedHeap::print_on(outputStream* st) const {
2348 st->print(" %-20s", "garbage-first heap");
2349 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2350 capacity()/K, used_unlocked()/K);
2351 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2352 p2i(_hrm.reserved().start()),
2353 p2i(_hrm.reserved().end()));
2354 st->cr();
2355 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2356 uint young_regions = young_regions_count();
2357 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2358 (size_t) young_regions * HeapRegion::GrainBytes / K);
2359 uint survivor_regions = survivor_regions_count();
2360 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2361 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2362 st->cr();
2363 MetaspaceAux::print_on(st);
2364 }
2365
2366 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2367 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2368 "HS=humongous(starts), HC=humongous(continues), "
2369 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2370 "AC=allocation context, "
2371 "TAMS=top-at-mark-start (previous, next)");
2372 PrintRegionClosure blk(st);
2373 heap_region_iterate(&blk);
2374 }
2375
2376 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2377 print_on(st);
2378
2379 // Print the per-region information.
2380 print_regions_on(st);
2381 }
2382
2383 void G1CollectedHeap::print_on_error(outputStream* st) const {
2384 this->CollectedHeap::print_on_error(st);
2385
2386 if (_cm != NULL) {
2387 st->cr();
2388 _cm->print_on_error(st);
2389 }
2390 }
2391
2392 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2393 workers()->print_worker_threads_on(st);
2394 _cmThread->print_on(st);
2395 st->cr();
2396 _cm->print_worker_threads_on(st);
2397 _cr->print_threads_on(st);
2398 _young_gen_sampling_thread->print_on(st);
2399 if (G1StringDedup::is_enabled()) {
2400 G1StringDedup::print_worker_threads_on(st);
2401 }
2402 }
2403
2404 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2405 workers()->threads_do(tc);
2406 tc->do_thread(_cmThread);
2407 _cm->threads_do(tc);
2408 _cr->threads_do(tc);
2409 tc->do_thread(_young_gen_sampling_thread);
2410 if (G1StringDedup::is_enabled()) {
2411 G1StringDedup::threads_do(tc);
2412 }
2413 }
2414
2415 void G1CollectedHeap::print_tracing_info() const {
2416 g1_rem_set()->print_summary_info();
2417 concurrent_mark()->print_summary_info();
2418 }
2419
2420 #ifndef PRODUCT
2421 // Helpful for debugging RSet issues.
2422
2423 class PrintRSetsClosure : public HeapRegionClosure {
2424 private:
2425 const char* _msg;
2426 size_t _occupied_sum;
2427
2428 public:
2429 bool do_heap_region(HeapRegion* r) {
2430 HeapRegionRemSet* hrrs = r->rem_set();
2431 size_t occupied = hrrs->occupied();
2432 _occupied_sum += occupied;
2433
2434 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2435 if (occupied == 0) {
2436 tty->print_cr(" RSet is empty");
2437 } else {
2438 hrrs->print();
2439 }
2440 tty->print_cr("----------");
2441 return false;
2442 }
2443
2444 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2445 tty->cr();
2446 tty->print_cr("========================================");
2447 tty->print_cr("%s", msg);
2448 tty->cr();
2449 }
2450
2451 ~PrintRSetsClosure() {
2452 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2453 tty->print_cr("========================================");
2454 tty->cr();
2455 }
2456 };
2457
2458 void G1CollectedHeap::print_cset_rsets() {
2459 PrintRSetsClosure cl("Printing CSet RSets");
2460 collection_set_iterate(&cl);
2461 }
2462
2463 void G1CollectedHeap::print_all_rsets() {
2464 PrintRSetsClosure cl("Printing All RSets");;
2465 heap_region_iterate(&cl);
2466 }
2467 #endif // PRODUCT
2468
2469 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2470
2471 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2472 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2473 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2474
2475 size_t eden_capacity_bytes =
2476 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2477
2478 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2479 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2480 eden_capacity_bytes, survivor_used_bytes, num_regions());
2481 }
2482
2483 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2484 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2485 stats->unused(), stats->used(), stats->region_end_waste(),
2486 stats->regions_filled(), stats->direct_allocated(),
2487 stats->failure_used(), stats->failure_waste());
2488 }
2489
2490 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2491 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2492 gc_tracer->report_gc_heap_summary(when, heap_summary);
2493
2494 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2495 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2496 }
2497
2498 G1CollectedHeap* G1CollectedHeap::heap() {
2499 CollectedHeap* heap = Universe::heap();
2500 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2501 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2502 return (G1CollectedHeap*)heap;
2503 }
2504
2505 void G1CollectedHeap::gc_prologue(bool full) {
2506 // always_do_update_barrier = false;
2507 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2508
2509 // This summary needs to be printed before incrementing total collections.
2510 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2511
2512 // Update common counters.
2513 increment_total_collections(full /* full gc */);
2514 if (full) {
2515 increment_old_marking_cycles_started();
2516 reset_gc_time_stamp();
2517 } else {
2518 increment_gc_time_stamp();
2519 }
2520
2521 // Fill TLAB's and such
2522 double start = os::elapsedTime();
2523 accumulate_statistics_all_tlabs();
2524 ensure_parsability(true);
2525 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2526 }
2527
2528 void G1CollectedHeap::gc_epilogue(bool full) {
2529 // Update common counters.
2530 if (full) {
2531 // Update the number of full collections that have been completed.
2532 increment_old_marking_cycles_completed(false /* concurrent */);
2533 }
2534
2535 // We are at the end of the GC. Total collections has already been increased.
2536 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2537
2538 // FIXME: what is this about?
2539 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2540 // is set.
2541 #if COMPILER2_OR_JVMCI
2542 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2543 #endif
2544 // always_do_update_barrier = true;
2545
2546 double start = os::elapsedTime();
2547 resize_all_tlabs();
2548 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2549
2550 allocation_context_stats().update(full);
2551
2552 MemoryService::track_memory_usage();
2553 // We have just completed a GC. Update the soft reference
2554 // policy with the new heap occupancy
2555 Universe::update_heap_info_at_gc();
2556 }
2557
2558 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2559 uint gc_count_before,
2560 bool* succeeded,
2561 GCCause::Cause gc_cause) {
2562 assert_heap_not_locked_and_not_at_safepoint();
2563 VM_G1CollectForAllocation op(word_size,
2564 gc_count_before,
2565 gc_cause,
2566 false, /* should_initiate_conc_mark */
2567 g1_policy()->max_pause_time_ms(),
2568 AllocationContext::current());
2569 VMThread::execute(&op);
2570
2571 HeapWord* result = op.result();
2572 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2573 assert(result == NULL || ret_succeeded,
2574 "the result should be NULL if the VM did not succeed");
2575 *succeeded = ret_succeeded;
2576
2577 assert_heap_not_locked();
2578 return result;
2579 }
2580
2581 void
2582 G1CollectedHeap::doConcurrentMark() {
2583 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2584 if (!_cmThread->in_progress()) {
2585 _cmThread->set_started();
2586 CGC_lock->notify();
2587 }
2588 }
2589
2590 size_t G1CollectedHeap::pending_card_num() {
2591 size_t extra_cards = 0;
2592 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2593 DirtyCardQueue& dcq = curr->dirty_card_queue();
2594 extra_cards += dcq.size();
2595 }
2596 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2597 size_t buffer_size = dcqs.buffer_size();
2598 size_t buffer_num = dcqs.completed_buffers_num();
2599
2600 return buffer_size * buffer_num + extra_cards;
2601 }
2602
2603 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2604 private:
2605 size_t _total_humongous;
2606 size_t _candidate_humongous;
2607
2608 DirtyCardQueue _dcq;
2609
2610 // We don't nominate objects with many remembered set entries, on
2611 // the assumption that such objects are likely still live.
2612 bool is_remset_small(HeapRegion* region) const {
2613 HeapRegionRemSet* const rset = region->rem_set();
2614 return G1EagerReclaimHumongousObjectsWithStaleRefs
2615 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2616 : rset->is_empty();
2617 }
2618
2619 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2620 assert(region->is_starts_humongous(), "Must start a humongous object");
2621
2622 oop obj = oop(region->bottom());
2623
2624 // Dead objects cannot be eager reclaim candidates. Due to class
2625 // unloading it is unsafe to query their classes so we return early.
2626 if (heap->is_obj_dead(obj, region)) {
2627 return false;
2628 }
2629
2630 // Candidate selection must satisfy the following constraints
2631 // while concurrent marking is in progress:
2632 //
2633 // * In order to maintain SATB invariants, an object must not be
2634 // reclaimed if it was allocated before the start of marking and
2635 // has not had its references scanned. Such an object must have
2636 // its references (including type metadata) scanned to ensure no
2637 // live objects are missed by the marking process. Objects
2638 // allocated after the start of concurrent marking don't need to
2639 // be scanned.
2640 //
2641 // * An object must not be reclaimed if it is on the concurrent
2642 // mark stack. Objects allocated after the start of concurrent
2643 // marking are never pushed on the mark stack.
2644 //
2645 // Nominating only objects allocated after the start of concurrent
2646 // marking is sufficient to meet both constraints. This may miss
2647 // some objects that satisfy the constraints, but the marking data
2648 // structures don't support efficiently performing the needed
2649 // additional tests or scrubbing of the mark stack.
2650 //
2651 // However, we presently only nominate is_typeArray() objects.
2652 // A humongous object containing references induces remembered
2653 // set entries on other regions. In order to reclaim such an
2654 // object, those remembered sets would need to be cleaned up.
2655 //
2656 // We also treat is_typeArray() objects specially, allowing them
2657 // to be reclaimed even if allocated before the start of
2658 // concurrent mark. For this we rely on mark stack insertion to
2659 // exclude is_typeArray() objects, preventing reclaiming an object
2660 // that is in the mark stack. We also rely on the metadata for
2661 // such objects to be built-in and so ensured to be kept live.
2662 // Frequent allocation and drop of large binary blobs is an
2663 // important use case for eager reclaim, and this special handling
2664 // may reduce needed headroom.
2665
2666 return obj->is_typeArray() && is_remset_small(region);
2667 }
2668
2669 public:
2670 RegisterHumongousWithInCSetFastTestClosure()
2671 : _total_humongous(0),
2672 _candidate_humongous(0),
2673 _dcq(&JavaThread::dirty_card_queue_set()) {
2674 }
2675
2676 virtual bool do_heap_region(HeapRegion* r) {
2677 if (!r->is_starts_humongous()) {
2678 return false;
2679 }
2680 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2681
2682 bool is_candidate = humongous_region_is_candidate(g1h, r);
2683 uint rindex = r->hrm_index();
2684 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2685 if (is_candidate) {
2686 _candidate_humongous++;
2687 g1h->register_humongous_region_with_cset(rindex);
2688 // Is_candidate already filters out humongous object with large remembered sets.
2689 // If we have a humongous object with a few remembered sets, we simply flush these
2690 // remembered set entries into the DCQS. That will result in automatic
2691 // re-evaluation of their remembered set entries during the following evacuation
2692 // phase.
2693 if (!r->rem_set()->is_empty()) {
2694 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2695 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2696 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2697 HeapRegionRemSetIterator hrrs(r->rem_set());
2698 size_t card_index;
2699 while (hrrs.has_next(card_index)) {
2700 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2701 // The remembered set might contain references to already freed
2702 // regions. Filter out such entries to avoid failing card table
2703 // verification.
2704 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2705 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2706 *card_ptr = CardTableModRefBS::dirty_card_val();
2707 _dcq.enqueue(card_ptr);
2708 }
2709 }
2710 }
2711 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2712 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2713 hrrs.n_yielded(), r->rem_set()->occupied());
2714 r->rem_set()->clear_locked();
2715 }
2716 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2717 }
2718 _total_humongous++;
2719
2720 return false;
2721 }
2722
2723 size_t total_humongous() const { return _total_humongous; }
2724 size_t candidate_humongous() const { return _candidate_humongous; }
2725
2726 void flush_rem_set_entries() { _dcq.flush(); }
2727 };
2728
2729 void G1CollectedHeap::register_humongous_regions_with_cset() {
2730 if (!G1EagerReclaimHumongousObjects) {
2731 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2732 return;
2733 }
2734 double time = os::elapsed_counter();
2735
2736 // Collect reclaim candidate information and register candidates with cset.
2737 RegisterHumongousWithInCSetFastTestClosure cl;
2738 heap_region_iterate(&cl);
2739
2740 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2741 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2742 cl.total_humongous(),
2743 cl.candidate_humongous());
2744 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2745
2746 // Finally flush all remembered set entries to re-check into the global DCQS.
2747 cl.flush_rem_set_entries();
2748 }
2749
2750 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2751 public:
2752 bool do_heap_region(HeapRegion* hr) {
2753 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2754 hr->verify_rem_set();
2755 }
2756 return false;
2757 }
2758 };
2759
2760 uint G1CollectedHeap::num_task_queues() const {
2761 return _task_queues->size();
2762 }
2763
2764 #if TASKQUEUE_STATS
2765 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2766 st->print_raw_cr("GC Task Stats");
2767 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2768 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2769 }
2770
2771 void G1CollectedHeap::print_taskqueue_stats() const {
2772 if (!log_is_enabled(Trace, gc, task, stats)) {
2773 return;
2774 }
2775 Log(gc, task, stats) log;
2776 ResourceMark rm;
2777 LogStream ls(log.trace());
2778 outputStream* st = &ls;
2779
2780 print_taskqueue_stats_hdr(st);
2781
2782 TaskQueueStats totals;
2783 const uint n = num_task_queues();
2784 for (uint i = 0; i < n; ++i) {
2785 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2786 totals += task_queue(i)->stats;
2787 }
2788 st->print_raw("tot "); totals.print(st); st->cr();
2789
2790 DEBUG_ONLY(totals.verify());
2791 }
2792
2793 void G1CollectedHeap::reset_taskqueue_stats() {
2794 const uint n = num_task_queues();
2795 for (uint i = 0; i < n; ++i) {
2796 task_queue(i)->stats.reset();
2797 }
2798 }
2799 #endif // TASKQUEUE_STATS
2800
2801 void G1CollectedHeap::wait_for_root_region_scanning() {
2802 double scan_wait_start = os::elapsedTime();
2803 // We have to wait until the CM threads finish scanning the
2804 // root regions as it's the only way to ensure that all the
2805 // objects on them have been correctly scanned before we start
2806 // moving them during the GC.
2807 bool waited = _cm->root_regions()->wait_until_scan_finished();
2808 double wait_time_ms = 0.0;
2809 if (waited) {
2810 double scan_wait_end = os::elapsedTime();
2811 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2812 }
2813 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2814 }
2815
2816 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2817 private:
2818 G1HRPrinter* _hr_printer;
2819 public:
2820 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2821
2822 virtual bool do_heap_region(HeapRegion* r) {
2823 _hr_printer->cset(r);
2824 return false;
2825 }
2826 };
2827
2828 void G1CollectedHeap::start_new_collection_set() {
2829 collection_set()->start_incremental_building();
2830
2831 clear_cset_fast_test();
2832
2833 guarantee(_eden.length() == 0, "eden should have been cleared");
2834 g1_policy()->transfer_survivors_to_cset(survivor());
2835 }
2836
2837 bool
2838 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2839 assert_at_safepoint(true /* should_be_vm_thread */);
2840 guarantee(!is_gc_active(), "collection is not reentrant");
2841
2842 if (GCLocker::check_active_before_gc()) {
2843 return false;
2844 }
2845
2846 _gc_timer_stw->register_gc_start();
2847
2848 GCIdMark gc_id_mark;
2849 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2850
2851 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2852 ResourceMark rm;
2853
2854 g1_policy()->note_gc_start();
2855
2856 wait_for_root_region_scanning();
2857
2858 print_heap_before_gc();
2859 print_heap_regions();
2860 trace_heap_before_gc(_gc_tracer_stw);
2861
2862 _verifier->verify_region_sets_optional();
2863 _verifier->verify_dirty_young_regions();
2864
2865 // We should not be doing initial mark unless the conc mark thread is running
2866 if (!_cmThread->should_terminate()) {
2867 // This call will decide whether this pause is an initial-mark
2868 // pause. If it is, during_initial_mark_pause() will return true
2869 // for the duration of this pause.
2870 g1_policy()->decide_on_conc_mark_initiation();
2871 }
2872
2873 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2874 assert(!collector_state()->during_initial_mark_pause() ||
2875 collector_state()->gcs_are_young(), "sanity");
2876
2877 // We also do not allow mixed GCs during marking.
2878 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2879
2880 // Record whether this pause is an initial mark. When the current
2881 // thread has completed its logging output and it's safe to signal
2882 // the CM thread, the flag's value in the policy has been reset.
2883 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2884
2885 // Inner scope for scope based logging, timers, and stats collection
2886 {
2887 EvacuationInfo evacuation_info;
2888
2889 if (collector_state()->during_initial_mark_pause()) {
2890 // We are about to start a marking cycle, so we increment the
2891 // full collection counter.
2892 increment_old_marking_cycles_started();
2893 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2894 }
2895
2896 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2897
2898 GCTraceCPUTime tcpu;
2899
2900 G1HeapVerifier::G1VerifyType verify_type;
2901 FormatBuffer<> gc_string("Pause ");
2902 if (collector_state()->during_initial_mark_pause()) {
2903 gc_string.append("Initial Mark");
2904 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2905 } else if (collector_state()->gcs_are_young()) {
2906 gc_string.append("Young");
2907 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2908 } else {
2909 gc_string.append("Mixed");
2910 verify_type = G1HeapVerifier::G1VerifyMixed;
2911 }
2912 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2913
2914 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2915 workers()->active_workers(),
2916 Threads::number_of_non_daemon_threads());
2917 workers()->update_active_workers(active_workers);
2918 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2919
2920 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2921 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2922
2923 // If the secondary_free_list is not empty, append it to the
2924 // free_list. No need to wait for the cleanup operation to finish;
2925 // the region allocation code will check the secondary_free_list
2926 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2927 // set, skip this step so that the region allocation code has to
2928 // get entries from the secondary_free_list.
2929 if (!G1StressConcRegionFreeing) {
2930 append_secondary_free_list_if_not_empty_with_lock();
2931 }
2932
2933 G1HeapTransition heap_transition(this);
2934 size_t heap_used_bytes_before_gc = used();
2935
2936 // Don't dynamically change the number of GC threads this early. A value of
2937 // 0 is used to indicate serial work. When parallel work is done,
2938 // it will be set.
2939
2940 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2941 IsGCActiveMark x;
2942
2943 gc_prologue(false);
2944
2945 if (VerifyRememberedSets) {
2946 log_info(gc, verify)("[Verifying RemSets before GC]");
2947 VerifyRegionRemSetClosure v_cl;
2948 heap_region_iterate(&v_cl);
2949 }
2950
2951 _verifier->verify_before_gc(verify_type);
2952
2953 _verifier->check_bitmaps("GC Start");
2954
2955 #if COMPILER2_OR_JVMCI
2956 DerivedPointerTable::clear();
2957 #endif
2958
2959 // Please see comment in g1CollectedHeap.hpp and
2960 // G1CollectedHeap::ref_processing_init() to see how
2961 // reference processing currently works in G1.
2962
2963 // Enable discovery in the STW reference processor
2964 if (g1_policy()->should_process_references()) {
2965 ref_processor_stw()->enable_discovery();
2966 } else {
2967 ref_processor_stw()->disable_discovery();
2968 }
2969
2970 {
2971 // We want to temporarily turn off discovery by the
2972 // CM ref processor, if necessary, and turn it back on
2973 // on again later if we do. Using a scoped
2974 // NoRefDiscovery object will do this.
2975 NoRefDiscovery no_cm_discovery(ref_processor_cm());
2976
2977 // Forget the current alloc region (we might even choose it to be part
2978 // of the collection set!).
2979 _allocator->release_mutator_alloc_region();
2980
2981 // This timing is only used by the ergonomics to handle our pause target.
2982 // It is unclear why this should not include the full pause. We will
2983 // investigate this in CR 7178365.
2984 //
2985 // Preserving the old comment here if that helps the investigation:
2986 //
2987 // The elapsed time induced by the start time below deliberately elides
2988 // the possible verification above.
2989 double sample_start_time_sec = os::elapsedTime();
2990
2991 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2992
2993 if (collector_state()->during_initial_mark_pause()) {
2994 concurrent_mark()->checkpoint_roots_initial_pre();
2995 }
2996
2997 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2998
2999 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3000
3001 // Make sure the remembered sets are up to date. This needs to be
3002 // done before register_humongous_regions_with_cset(), because the
3003 // remembered sets are used there to choose eager reclaim candidates.
3004 // If the remembered sets are not up to date we might miss some
3005 // entries that need to be handled.
3006 g1_rem_set()->cleanupHRRS();
3007
3008 register_humongous_regions_with_cset();
3009
3010 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3011
3012 // We call this after finalize_cset() to
3013 // ensure that the CSet has been finalized.
3014 _cm->verify_no_cset_oops();
3015
3016 if (_hr_printer.is_active()) {
3017 G1PrintCollectionSetClosure cl(&_hr_printer);
3018 _collection_set.iterate(&cl);
3019 }
3020
3021 // Initialize the GC alloc regions.
3022 _allocator->init_gc_alloc_regions(evacuation_info);
3023
3024 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3025 pre_evacuate_collection_set();
3026
3027 // Actually do the work...
3028 evacuate_collection_set(evacuation_info, &per_thread_states);
3029
3030 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3031
3032 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3033 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3034
3035 eagerly_reclaim_humongous_regions();
3036
3037 record_obj_copy_mem_stats();
3038 _survivor_evac_stats.adjust_desired_plab_sz();
3039 _old_evac_stats.adjust_desired_plab_sz();
3040
3041 double start = os::elapsedTime();
3042 start_new_collection_set();
3043 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3044
3045 if (evacuation_failed()) {
3046 set_used(recalculate_used());
3047 if (_archive_allocator != NULL) {
3048 _archive_allocator->clear_used();
3049 }
3050 for (uint i = 0; i < ParallelGCThreads; i++) {
3051 if (_evacuation_failed_info_array[i].has_failed()) {
3052 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3053 }
3054 }
3055 } else {
3056 // The "used" of the the collection set have already been subtracted
3057 // when they were freed. Add in the bytes evacuated.
3058 increase_used(g1_policy()->bytes_copied_during_gc());
3059 }
3060
3061 if (collector_state()->during_initial_mark_pause()) {
3062 // We have to do this before we notify the CM threads that
3063 // they can start working to make sure that all the
3064 // appropriate initialization is done on the CM object.
3065 concurrent_mark()->checkpoint_roots_initial_post();
3066 collector_state()->set_mark_in_progress(true);
3067 // Note that we don't actually trigger the CM thread at
3068 // this point. We do that later when we're sure that
3069 // the current thread has completed its logging output.
3070 }
3071
3072 allocate_dummy_regions();
3073
3074 _allocator->init_mutator_alloc_region();
3075
3076 {
3077 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3078 if (expand_bytes > 0) {
3079 size_t bytes_before = capacity();
3080 // No need for an ergo logging here,
3081 // expansion_amount() does this when it returns a value > 0.
3082 double expand_ms;
3083 if (!expand(expand_bytes, _workers, &expand_ms)) {
3084 // We failed to expand the heap. Cannot do anything about it.
3085 }
3086 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3087 }
3088 }
3089
3090 // We redo the verification but now wrt to the new CSet which
3091 // has just got initialized after the previous CSet was freed.
3092 _cm->verify_no_cset_oops();
3093
3094 // This timing is only used by the ergonomics to handle our pause target.
3095 // It is unclear why this should not include the full pause. We will
3096 // investigate this in CR 7178365.
3097 double sample_end_time_sec = os::elapsedTime();
3098 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3099 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3100 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3101
3102 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3103 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3104
3105 if (VerifyRememberedSets) {
3106 log_info(gc, verify)("[Verifying RemSets after GC]");
3107 VerifyRegionRemSetClosure v_cl;
3108 heap_region_iterate(&v_cl);
3109 }
3110
3111 _verifier->verify_after_gc(verify_type);
3112 _verifier->check_bitmaps("GC End");
3113
3114 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3115 ref_processor_stw()->verify_no_references_recorded();
3116
3117 // CM reference discovery will be re-enabled if necessary.
3118 }
3119
3120 #ifdef TRACESPINNING
3121 ParallelTaskTerminator::print_termination_counts();
3122 #endif
3123
3124 gc_epilogue(false);
3125 }
3126
3127 // Print the remainder of the GC log output.
3128 if (evacuation_failed()) {
3129 log_info(gc)("To-space exhausted");
3130 }
3131
3132 g1_policy()->print_phases();
3133 heap_transition.print();
3134
3135 // It is not yet to safe to tell the concurrent mark to
3136 // start as we have some optional output below. We don't want the
3137 // output from the concurrent mark thread interfering with this
3138 // logging output either.
3139
3140 _hrm.verify_optional();
3141 _verifier->verify_region_sets_optional();
3142
3143 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3144 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3145
3146 print_heap_after_gc();
3147 print_heap_regions();
3148 trace_heap_after_gc(_gc_tracer_stw);
3149
3150 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3151 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3152 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3153 // before any GC notifications are raised.
3154 g1mm()->update_sizes();
3155
3156 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3157 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3158 _gc_timer_stw->register_gc_end();
3159 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3160 }
3161 // It should now be safe to tell the concurrent mark thread to start
3162 // without its logging output interfering with the logging output
3163 // that came from the pause.
3164
3165 if (should_start_conc_mark) {
3166 // CAUTION: after the doConcurrentMark() call below,
3167 // the concurrent marking thread(s) could be running
3168 // concurrently with us. Make sure that anything after
3169 // this point does not assume that we are the only GC thread
3170 // running. Note: of course, the actual marking work will
3171 // not start until the safepoint itself is released in
3172 // SuspendibleThreadSet::desynchronize().
3173 doConcurrentMark();
3174 }
3175
3176 return true;
3177 }
3178
3179 void G1CollectedHeap::remove_self_forwarding_pointers() {
3180 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3181 workers()->run_task(&rsfp_task);
3182 }
3183
3184 void G1CollectedHeap::restore_after_evac_failure() {
3185 double remove_self_forwards_start = os::elapsedTime();
3186
3187 remove_self_forwarding_pointers();
3188 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3189 _preserved_marks_set.restore(&task_executor);
3190
3191 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3192 }
3193
3194 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3195 if (!_evacuation_failed) {
3196 _evacuation_failed = true;
3197 }
3198
3199 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3200 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3201 }
3202
3203 bool G1ParEvacuateFollowersClosure::offer_termination() {
3204 G1ParScanThreadState* const pss = par_scan_state();
3205 start_term_time();
3206 const bool res = terminator()->offer_termination();
3207 end_term_time();
3208 return res;
3209 }
3210
3211 void G1ParEvacuateFollowersClosure::do_void() {
3212 G1ParScanThreadState* const pss = par_scan_state();
3213 pss->trim_queue();
3214 do {
3215 pss->steal_and_trim_queue(queues());
3216 } while (!offer_termination());
3217 }
3218
3219 class G1ParTask : public AbstractGangTask {
3220 protected:
3221 G1CollectedHeap* _g1h;
3222 G1ParScanThreadStateSet* _pss;
3223 RefToScanQueueSet* _queues;
3224 G1RootProcessor* _root_processor;
3225 ParallelTaskTerminator _terminator;
3226 uint _n_workers;
3227
3228 public:
3229 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3230 : AbstractGangTask("G1 collection"),
3231 _g1h(g1h),
3232 _pss(per_thread_states),
3233 _queues(task_queues),
3234 _root_processor(root_processor),
3235 _terminator(n_workers, _queues),
3236 _n_workers(n_workers)
3237 {}
3238
3239 void work(uint worker_id) {
3240 if (worker_id >= _n_workers) return; // no work needed this round
3241
3242 double start_sec = os::elapsedTime();
3243 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3244
3245 {
3246 ResourceMark rm;
3247 HandleMark hm;
3248
3249 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3250
3251 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3252 pss->set_ref_processor(rp);
3253
3254 double start_strong_roots_sec = os::elapsedTime();
3255
3256 _root_processor->evacuate_roots(pss->closures(), worker_id);
3257
3258 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3259 // treating the nmethods visited to act as roots for concurrent marking.
3260 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3261 // objects copied by the current evacuation.
3262 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3263 pss->closures()->weak_codeblobs(),
3264 worker_id);
3265
3266 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3267
3268 double term_sec = 0.0;
3269 size_t evac_term_attempts = 0;
3270 {
3271 double start = os::elapsedTime();
3272 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3273 evac.do_void();
3274
3275 evac_term_attempts = evac.term_attempts();
3276 term_sec = evac.term_time();
3277 double elapsed_sec = os::elapsedTime() - start;
3278 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3279 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3280 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3281 }
3282
3283 assert(pss->queue_is_empty(), "should be empty");
3284
3285 if (log_is_enabled(Debug, gc, task, stats)) {
3286 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3287 size_t lab_waste;
3288 size_t lab_undo_waste;
3289 pss->waste(lab_waste, lab_undo_waste);
3290 _g1h->print_termination_stats(worker_id,
3291 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3292 strong_roots_sec * 1000.0, /* strong roots time */
3293 term_sec * 1000.0, /* evac term time */
3294 evac_term_attempts, /* evac term attempts */
3295 lab_waste, /* alloc buffer waste */
3296 lab_undo_waste /* undo waste */
3297 );
3298 }
3299
3300 // Close the inner scope so that the ResourceMark and HandleMark
3301 // destructors are executed here and are included as part of the
3302 // "GC Worker Time".
3303 }
3304 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3305 }
3306 };
3307
3308 void G1CollectedHeap::print_termination_stats_hdr() {
3309 log_debug(gc, task, stats)("GC Termination Stats");
3310 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3311 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3312 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3313 }
3314
3315 void G1CollectedHeap::print_termination_stats(uint worker_id,
3316 double elapsed_ms,
3317 double strong_roots_ms,
3318 double term_ms,
3319 size_t term_attempts,
3320 size_t alloc_buffer_waste,
3321 size_t undo_waste) const {
3322 log_debug(gc, task, stats)
3323 ("%3d %9.2f %9.2f %6.2f "
3324 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3325 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3326 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3327 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3328 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3329 alloc_buffer_waste * HeapWordSize / K,
3330 undo_waste * HeapWordSize / K);
3331 }
3332
3333 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3334 private:
3335 BoolObjectClosure* _is_alive;
3336 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3337
3338 int _initial_string_table_size;
3339 int _initial_symbol_table_size;
3340
3341 bool _process_strings;
3342 int _strings_processed;
3343 int _strings_removed;
3344
3345 bool _process_symbols;
3346 int _symbols_processed;
3347 int _symbols_removed;
3348
3349 bool _process_string_dedup;
3350
3351 public:
3352 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3353 AbstractGangTask("String/Symbol Unlinking"),
3354 _is_alive(is_alive),
3355 _dedup_closure(is_alive, NULL, false),
3356 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3357 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3358 _process_string_dedup(process_string_dedup) {
3359
3360 _initial_string_table_size = StringTable::the_table()->table_size();
3361 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3362 if (process_strings) {
3363 StringTable::clear_parallel_claimed_index();
3364 }
3365 if (process_symbols) {
3366 SymbolTable::clear_parallel_claimed_index();
3367 }
3368 }
3369
3370 ~G1StringAndSymbolCleaningTask() {
3371 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3372 "claim value %d after unlink less than initial string table size %d",
3373 StringTable::parallel_claimed_index(), _initial_string_table_size);
3374 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3375 "claim value %d after unlink less than initial symbol table size %d",
3376 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3377
3378 log_info(gc, stringtable)(
3379 "Cleaned string and symbol table, "
3380 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3381 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3382 strings_processed(), strings_removed(),
3383 symbols_processed(), symbols_removed());
3384 }
3385
3386 void work(uint worker_id) {
3387 int strings_processed = 0;
3388 int strings_removed = 0;
3389 int symbols_processed = 0;
3390 int symbols_removed = 0;
3391 if (_process_strings) {
3392 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3393 Atomic::add(strings_processed, &_strings_processed);
3394 Atomic::add(strings_removed, &_strings_removed);
3395 }
3396 if (_process_symbols) {
3397 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3398 Atomic::add(symbols_processed, &_symbols_processed);
3399 Atomic::add(symbols_removed, &_symbols_removed);
3400 }
3401 if (_process_string_dedup) {
3402 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3403 }
3404 }
3405
3406 size_t strings_processed() const { return (size_t)_strings_processed; }
3407 size_t strings_removed() const { return (size_t)_strings_removed; }
3408
3409 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3410 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3411 };
3412
3413 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3414 private:
3415 static Monitor* _lock;
3416
3417 BoolObjectClosure* const _is_alive;
3418 const bool _unloading_occurred;
3419 const uint _num_workers;
3420
3421 // Variables used to claim nmethods.
3422 CompiledMethod* _first_nmethod;
3423 CompiledMethod* volatile _claimed_nmethod;
3424
3425 // The list of nmethods that need to be processed by the second pass.
3426 CompiledMethod* volatile _postponed_list;
3427 volatile uint _num_entered_barrier;
3428
3429 public:
3430 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3431 _is_alive(is_alive),
3432 _unloading_occurred(unloading_occurred),
3433 _num_workers(num_workers),
3434 _first_nmethod(NULL),
3435 _claimed_nmethod(NULL),
3436 _postponed_list(NULL),
3437 _num_entered_barrier(0)
3438 {
3439 CompiledMethod::increase_unloading_clock();
3440 // Get first alive nmethod
3441 CompiledMethodIterator iter = CompiledMethodIterator();
3442 if(iter.next_alive()) {
3443 _first_nmethod = iter.method();
3444 }
3445 _claimed_nmethod = _first_nmethod;
3446 }
3447
3448 ~G1CodeCacheUnloadingTask() {
3449 CodeCache::verify_clean_inline_caches();
3450
3451 CodeCache::set_needs_cache_clean(false);
3452 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3453
3454 CodeCache::verify_icholder_relocations();
3455 }
3456
3457 private:
3458 void add_to_postponed_list(CompiledMethod* nm) {
3459 CompiledMethod* old;
3460 do {
3461 old = _postponed_list;
3462 nm->set_unloading_next(old);
3463 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3464 }
3465
3466 void clean_nmethod(CompiledMethod* nm) {
3467 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3468
3469 if (postponed) {
3470 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3471 add_to_postponed_list(nm);
3472 }
3473
3474 // Mark that this thread has been cleaned/unloaded.
3475 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3476 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3477 }
3478
3479 void clean_nmethod_postponed(CompiledMethod* nm) {
3480 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3481 }
3482
3483 static const int MaxClaimNmethods = 16;
3484
3485 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3486 CompiledMethod* first;
3487 CompiledMethodIterator last;
3488
3489 do {
3490 *num_claimed_nmethods = 0;
3491
3492 first = _claimed_nmethod;
3493 last = CompiledMethodIterator(first);
3494
3495 if (first != NULL) {
3496
3497 for (int i = 0; i < MaxClaimNmethods; i++) {
3498 if (!last.next_alive()) {
3499 break;
3500 }
3501 claimed_nmethods[i] = last.method();
3502 (*num_claimed_nmethods)++;
3503 }
3504 }
3505
3506 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3507 }
3508
3509 CompiledMethod* claim_postponed_nmethod() {
3510 CompiledMethod* claim;
3511 CompiledMethod* next;
3512
3513 do {
3514 claim = _postponed_list;
3515 if (claim == NULL) {
3516 return NULL;
3517 }
3518
3519 next = claim->unloading_next();
3520
3521 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3522
3523 return claim;
3524 }
3525
3526 public:
3527 // Mark that we're done with the first pass of nmethod cleaning.
3528 void barrier_mark(uint worker_id) {
3529 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3530 _num_entered_barrier++;
3531 if (_num_entered_barrier == _num_workers) {
3532 ml.notify_all();
3533 }
3534 }
3535
3536 // See if we have to wait for the other workers to
3537 // finish their first-pass nmethod cleaning work.
3538 void barrier_wait(uint worker_id) {
3539 if (_num_entered_barrier < _num_workers) {
3540 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3541 while (_num_entered_barrier < _num_workers) {
3542 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3543 }
3544 }
3545 }
3546
3547 // Cleaning and unloading of nmethods. Some work has to be postponed
3548 // to the second pass, when we know which nmethods survive.
3549 void work_first_pass(uint worker_id) {
3550 // The first nmethods is claimed by the first worker.
3551 if (worker_id == 0 && _first_nmethod != NULL) {
3552 clean_nmethod(_first_nmethod);
3553 _first_nmethod = NULL;
3554 }
3555
3556 int num_claimed_nmethods;
3557 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3558
3559 while (true) {
3560 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3561
3562 if (num_claimed_nmethods == 0) {
3563 break;
3564 }
3565
3566 for (int i = 0; i < num_claimed_nmethods; i++) {
3567 clean_nmethod(claimed_nmethods[i]);
3568 }
3569 }
3570 }
3571
3572 void work_second_pass(uint worker_id) {
3573 CompiledMethod* nm;
3574 // Take care of postponed nmethods.
3575 while ((nm = claim_postponed_nmethod()) != NULL) {
3576 clean_nmethod_postponed(nm);
3577 }
3578 }
3579 };
3580
3581 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3582
3583 class G1KlassCleaningTask : public StackObj {
3584 BoolObjectClosure* _is_alive;
3585 volatile int _clean_klass_tree_claimed;
3586 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3587
3588 public:
3589 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3590 _is_alive(is_alive),
3591 _clean_klass_tree_claimed(0),
3592 _klass_iterator() {
3593 }
3594
3595 private:
3596 bool claim_clean_klass_tree_task() {
3597 if (_clean_klass_tree_claimed) {
3598 return false;
3599 }
3600
3601 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3602 }
3603
3604 InstanceKlass* claim_next_klass() {
3605 Klass* klass;
3606 do {
3607 klass =_klass_iterator.next_klass();
3608 } while (klass != NULL && !klass->is_instance_klass());
3609
3610 // this can be null so don't call InstanceKlass::cast
3611 return static_cast<InstanceKlass*>(klass);
3612 }
3613
3614 public:
3615
3616 void clean_klass(InstanceKlass* ik) {
3617 ik->clean_weak_instanceklass_links(_is_alive);
3618 }
3619
3620 void work() {
3621 ResourceMark rm;
3622
3623 // One worker will clean the subklass/sibling klass tree.
3624 if (claim_clean_klass_tree_task()) {
3625 Klass::clean_subklass_tree(_is_alive);
3626 }
3627
3628 // All workers will help cleaning the classes,
3629 InstanceKlass* klass;
3630 while ((klass = claim_next_klass()) != NULL) {
3631 clean_klass(klass);
3632 }
3633 }
3634 };
3635
3636 class G1ResolvedMethodCleaningTask : public StackObj {
3637 BoolObjectClosure* _is_alive;
3638 volatile int _resolved_method_task_claimed;
3639 public:
3640 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3641 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3642
3643 bool claim_resolved_method_task() {
3644 if (_resolved_method_task_claimed) {
3645 return false;
3646 }
3647 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3648 }
3649
3650 // These aren't big, one thread can do it all.
3651 void work() {
3652 if (claim_resolved_method_task()) {
3653 ResolvedMethodTable::unlink(_is_alive);
3654 }
3655 }
3656 };
3657
3658
3659 // To minimize the remark pause times, the tasks below are done in parallel.
3660 class G1ParallelCleaningTask : public AbstractGangTask {
3661 private:
3662 G1StringAndSymbolCleaningTask _string_symbol_task;
3663 G1CodeCacheUnloadingTask _code_cache_task;
3664 G1KlassCleaningTask _klass_cleaning_task;
3665 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3666
3667 public:
3668 // The constructor is run in the VMThread.
3669 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3670 AbstractGangTask("Parallel Cleaning"),
3671 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3672 _code_cache_task(num_workers, is_alive, unloading_occurred),
3673 _klass_cleaning_task(is_alive),
3674 _resolved_method_cleaning_task(is_alive) {
3675 }
3676
3677 // The parallel work done by all worker threads.
3678 void work(uint worker_id) {
3679 // Do first pass of code cache cleaning.
3680 _code_cache_task.work_first_pass(worker_id);
3681
3682 // Let the threads mark that the first pass is done.
3683 _code_cache_task.barrier_mark(worker_id);
3684
3685 // Clean the Strings and Symbols.
3686 _string_symbol_task.work(worker_id);
3687
3688 // Clean unreferenced things in the ResolvedMethodTable
3689 _resolved_method_cleaning_task.work();
3690
3691 // Wait for all workers to finish the first code cache cleaning pass.
3692 _code_cache_task.barrier_wait(worker_id);
3693
3694 // Do the second code cache cleaning work, which realize on
3695 // the liveness information gathered during the first pass.
3696 _code_cache_task.work_second_pass(worker_id);
3697
3698 // Clean all klasses that were not unloaded.
3699 _klass_cleaning_task.work();
3700 }
3701 };
3702
3703
3704 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3705 bool class_unloading_occurred) {
3706 uint n_workers = workers()->active_workers();
3707
3708 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3709 workers()->run_task(&g1_unlink_task);
3710 }
3711
3712 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3713 bool process_strings,
3714 bool process_symbols,
3715 bool process_string_dedup) {
3716 if (!process_strings && !process_symbols && !process_string_dedup) {
3717 // Nothing to clean.
3718 return;
3719 }
3720
3721 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3722 workers()->run_task(&g1_unlink_task);
3723
3724 }
3725
3726 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3727 private:
3728 DirtyCardQueueSet* _queue;
3729 G1CollectedHeap* _g1h;
3730 public:
3731 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3732 _queue(queue), _g1h(g1h) { }
3733
3734 virtual void work(uint worker_id) {
3735 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3736 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3737
3738 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3739 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3740
3741 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3742 }
3743 };
3744
3745 void G1CollectedHeap::redirty_logged_cards() {
3746 double redirty_logged_cards_start = os::elapsedTime();
3747
3748 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3749 dirty_card_queue_set().reset_for_par_iteration();
3750 workers()->run_task(&redirty_task);
3751
3752 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3753 dcq.merge_bufferlists(&dirty_card_queue_set());
3754 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3755
3756 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3757 }
3758
3759 // Weak Reference Processing support
3760
3761 // An always "is_alive" closure that is used to preserve referents.
3762 // If the object is non-null then it's alive. Used in the preservation
3763 // of referent objects that are pointed to by reference objects
3764 // discovered by the CM ref processor.
3765 class G1AlwaysAliveClosure: public BoolObjectClosure {
3766 G1CollectedHeap* _g1;
3767 public:
3768 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3769 bool do_object_b(oop p) {
3770 if (p != NULL) {
3771 return true;
3772 }
3773 return false;
3774 }
3775 };
3776
3777 bool G1STWIsAliveClosure::do_object_b(oop p) {
3778 // An object is reachable if it is outside the collection set,
3779 // or is inside and copied.
3780 return !_g1->is_in_cset(p) || p->is_forwarded();
3781 }
3782
3783 // Non Copying Keep Alive closure
3784 class G1KeepAliveClosure: public OopClosure {
3785 G1CollectedHeap* _g1;
3786 public:
3787 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3788 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3789 void do_oop(oop* p) {
3790 oop obj = *p;
3791 assert(obj != NULL, "the caller should have filtered out NULL values");
3792
3793 const InCSetState cset_state = _g1->in_cset_state(obj);
3794 if (!cset_state.is_in_cset_or_humongous()) {
3795 return;
3796 }
3797 if (cset_state.is_in_cset()) {
3798 assert( obj->is_forwarded(), "invariant" );
3799 *p = obj->forwardee();
3800 } else {
3801 assert(!obj->is_forwarded(), "invariant" );
3802 assert(cset_state.is_humongous(),
3803 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3804 _g1->set_humongous_is_live(obj);
3805 }
3806 }
3807 };
3808
3809 // Copying Keep Alive closure - can be called from both
3810 // serial and parallel code as long as different worker
3811 // threads utilize different G1ParScanThreadState instances
3812 // and different queues.
3813
3814 class G1CopyingKeepAliveClosure: public OopClosure {
3815 G1CollectedHeap* _g1h;
3816 OopClosure* _copy_non_heap_obj_cl;
3817 G1ParScanThreadState* _par_scan_state;
3818
3819 public:
3820 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3821 OopClosure* non_heap_obj_cl,
3822 G1ParScanThreadState* pss):
3823 _g1h(g1h),
3824 _copy_non_heap_obj_cl(non_heap_obj_cl),
3825 _par_scan_state(pss)
3826 {}
3827
3828 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3829 virtual void do_oop( oop* p) { do_oop_work(p); }
3830
3831 template <class T> void do_oop_work(T* p) {
3832 oop obj = oopDesc::load_decode_heap_oop(p);
3833
3834 if (_g1h->is_in_cset_or_humongous(obj)) {
3835 // If the referent object has been forwarded (either copied
3836 // to a new location or to itself in the event of an
3837 // evacuation failure) then we need to update the reference
3838 // field and, if both reference and referent are in the G1
3839 // heap, update the RSet for the referent.
3840 //
3841 // If the referent has not been forwarded then we have to keep
3842 // it alive by policy. Therefore we have copy the referent.
3843 //
3844 // If the reference field is in the G1 heap then we can push
3845 // on the PSS queue. When the queue is drained (after each
3846 // phase of reference processing) the object and it's followers
3847 // will be copied, the reference field set to point to the
3848 // new location, and the RSet updated. Otherwise we need to
3849 // use the the non-heap or metadata closures directly to copy
3850 // the referent object and update the pointer, while avoiding
3851 // updating the RSet.
3852
3853 if (_g1h->is_in_g1_reserved(p)) {
3854 _par_scan_state->push_on_queue(p);
3855 } else {
3856 assert(!Metaspace::contains((const void*)p),
3857 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3858 _copy_non_heap_obj_cl->do_oop(p);
3859 }
3860 }
3861 }
3862 };
3863
3864 // Serial drain queue closure. Called as the 'complete_gc'
3865 // closure for each discovered list in some of the
3866 // reference processing phases.
3867
3868 class G1STWDrainQueueClosure: public VoidClosure {
3869 protected:
3870 G1CollectedHeap* _g1h;
3871 G1ParScanThreadState* _par_scan_state;
3872
3873 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3874
3875 public:
3876 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3877 _g1h(g1h),
3878 _par_scan_state(pss)
3879 { }
3880
3881 void do_void() {
3882 G1ParScanThreadState* const pss = par_scan_state();
3883 pss->trim_queue();
3884 }
3885 };
3886
3887 // Parallel Reference Processing closures
3888
3889 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3890 // processing during G1 evacuation pauses.
3891
3892 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3893 private:
3894 G1CollectedHeap* _g1h;
3895 G1ParScanThreadStateSet* _pss;
3896 RefToScanQueueSet* _queues;
3897 WorkGang* _workers;
3898 uint _active_workers;
3899
3900 public:
3901 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3902 G1ParScanThreadStateSet* per_thread_states,
3903 WorkGang* workers,
3904 RefToScanQueueSet *task_queues,
3905 uint n_workers) :
3906 _g1h(g1h),
3907 _pss(per_thread_states),
3908 _queues(task_queues),
3909 _workers(workers),
3910 _active_workers(n_workers)
3911 {
3912 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3913 }
3914
3915 // Executes the given task using concurrent marking worker threads.
3916 virtual void execute(ProcessTask& task);
3917 virtual void execute(EnqueueTask& task);
3918 };
3919
3920 // Gang task for possibly parallel reference processing
3921
3922 class G1STWRefProcTaskProxy: public AbstractGangTask {
3923 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3924 ProcessTask& _proc_task;
3925 G1CollectedHeap* _g1h;
3926 G1ParScanThreadStateSet* _pss;
3927 RefToScanQueueSet* _task_queues;
3928 ParallelTaskTerminator* _terminator;
3929
3930 public:
3931 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3932 G1CollectedHeap* g1h,
3933 G1ParScanThreadStateSet* per_thread_states,
3934 RefToScanQueueSet *task_queues,
3935 ParallelTaskTerminator* terminator) :
3936 AbstractGangTask("Process reference objects in parallel"),
3937 _proc_task(proc_task),
3938 _g1h(g1h),
3939 _pss(per_thread_states),
3940 _task_queues(task_queues),
3941 _terminator(terminator)
3942 {}
3943
3944 virtual void work(uint worker_id) {
3945 // The reference processing task executed by a single worker.
3946 ResourceMark rm;
3947 HandleMark hm;
3948
3949 G1STWIsAliveClosure is_alive(_g1h);
3950
3951 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3952 pss->set_ref_processor(NULL);
3953
3954 // Keep alive closure.
3955 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3956
3957 // Complete GC closure
3958 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3959
3960 // Call the reference processing task's work routine.
3961 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3962
3963 // Note we cannot assert that the refs array is empty here as not all
3964 // of the processing tasks (specifically phase2 - pp2_work) execute
3965 // the complete_gc closure (which ordinarily would drain the queue) so
3966 // the queue may not be empty.
3967 }
3968 };
3969
3970 // Driver routine for parallel reference processing.
3971 // Creates an instance of the ref processing gang
3972 // task and has the worker threads execute it.
3973 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3974 assert(_workers != NULL, "Need parallel worker threads.");
3975
3976 ParallelTaskTerminator terminator(_active_workers, _queues);
3977 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3978
3979 _workers->run_task(&proc_task_proxy);
3980 }
3981
3982 // Gang task for parallel reference enqueueing.
3983
3984 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3985 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3986 EnqueueTask& _enq_task;
3987
3988 public:
3989 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3990 AbstractGangTask("Enqueue reference objects in parallel"),
3991 _enq_task(enq_task)
3992 { }
3993
3994 virtual void work(uint worker_id) {
3995 _enq_task.work(worker_id);
3996 }
3997 };
3998
3999 // Driver routine for parallel reference enqueueing.
4000 // Creates an instance of the ref enqueueing gang
4001 // task and has the worker threads execute it.
4002
4003 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4004 assert(_workers != NULL, "Need parallel worker threads.");
4005
4006 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4007
4008 _workers->run_task(&enq_task_proxy);
4009 }
4010
4011 // End of weak reference support closures
4012
4013 // Abstract task used to preserve (i.e. copy) any referent objects
4014 // that are in the collection set and are pointed to by reference
4015 // objects discovered by the CM ref processor.
4016
4017 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4018 protected:
4019 G1CollectedHeap* _g1h;
4020 G1ParScanThreadStateSet* _pss;
4021 RefToScanQueueSet* _queues;
4022 ParallelTaskTerminator _terminator;
4023 uint _n_workers;
4024
4025 public:
4026 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4027 AbstractGangTask("ParPreserveCMReferents"),
4028 _g1h(g1h),
4029 _pss(per_thread_states),
4030 _queues(task_queues),
4031 _terminator(workers, _queues),
4032 _n_workers(workers)
4033 {
4034 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4035 }
4036
4037 void work(uint worker_id) {
4038 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4039
4040 ResourceMark rm;
4041 HandleMark hm;
4042
4043 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4044 pss->set_ref_processor(NULL);
4045 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4046
4047 // Is alive closure
4048 G1AlwaysAliveClosure always_alive(_g1h);
4049
4050 // Copying keep alive closure. Applied to referent objects that need
4051 // to be copied.
4052 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4053
4054 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4055
4056 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4057 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4058
4059 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4060 // So this must be true - but assert just in case someone decides to
4061 // change the worker ids.
4062 assert(worker_id < limit, "sanity");
4063 assert(!rp->discovery_is_atomic(), "check this code");
4064
4065 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4066 for (uint idx = worker_id; idx < limit; idx += stride) {
4067 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4068
4069 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4070 while (iter.has_next()) {
4071 // Since discovery is not atomic for the CM ref processor, we
4072 // can see some null referent objects.
4073 iter.load_ptrs(DEBUG_ONLY(true));
4074 oop ref = iter.obj();
4075
4076 // This will filter nulls.
4077 if (iter.is_referent_alive()) {
4078 iter.make_referent_alive();
4079 }
4080 iter.move_to_next();
4081 }
4082 }
4083
4084 // Drain the queue - which may cause stealing
4085 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4086 drain_queue.do_void();
4087 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4088 assert(pss->queue_is_empty(), "should be");
4089 }
4090 };
4091
4092 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4093 // Any reference objects, in the collection set, that were 'discovered'
4094 // by the CM ref processor should have already been copied (either by
4095 // applying the external root copy closure to the discovered lists, or
4096 // by following an RSet entry).
4097 //
4098 // But some of the referents, that are in the collection set, that these
4099 // reference objects point to may not have been copied: the STW ref
4100 // processor would have seen that the reference object had already
4101 // been 'discovered' and would have skipped discovering the reference,
4102 // but would not have treated the reference object as a regular oop.
4103 // As a result the copy closure would not have been applied to the
4104 // referent object.
4105 //
4106 // We need to explicitly copy these referent objects - the references
4107 // will be processed at the end of remarking.
4108 //
4109 // We also need to do this copying before we process the reference
4110 // objects discovered by the STW ref processor in case one of these
4111 // referents points to another object which is also referenced by an
4112 // object discovered by the STW ref processor.
4113 double preserve_cm_referents_time = 0.0;
4114
4115 // To avoid spawning task when there is no work to do, check that
4116 // a concurrent cycle is active and that some references have been
4117 // discovered.
4118 if (concurrent_mark()->cm_thread()->during_cycle() &&
4119 ref_processor_cm()->has_discovered_references()) {
4120 double preserve_cm_referents_start = os::elapsedTime();
4121 uint no_of_gc_workers = workers()->active_workers();
4122 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4123 per_thread_states,
4124 no_of_gc_workers,
4125 _task_queues);
4126 workers()->run_task(&keep_cm_referents);
4127 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4128 }
4129
4130 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4131 }
4132
4133 // Weak Reference processing during an evacuation pause (part 1).
4134 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4135 double ref_proc_start = os::elapsedTime();
4136
4137 ReferenceProcessor* rp = _ref_processor_stw;
4138 assert(rp->discovery_enabled(), "should have been enabled");
4139
4140 // Closure to test whether a referent is alive.
4141 G1STWIsAliveClosure is_alive(this);
4142
4143 // Even when parallel reference processing is enabled, the processing
4144 // of JNI refs is serial and performed serially by the current thread
4145 // rather than by a worker. The following PSS will be used for processing
4146 // JNI refs.
4147
4148 // Use only a single queue for this PSS.
4149 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4150 pss->set_ref_processor(NULL);
4151 assert(pss->queue_is_empty(), "pre-condition");
4152
4153 // Keep alive closure.
4154 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4155
4156 // Serial Complete GC closure
4157 G1STWDrainQueueClosure drain_queue(this, pss);
4158
4159 // Setup the soft refs policy...
4160 rp->setup_policy(false);
4161
4162 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4163
4164 ReferenceProcessorStats stats;
4165 if (!rp->processing_is_mt()) {
4166 // Serial reference processing...
4167 stats = rp->process_discovered_references(&is_alive,
4168 &keep_alive,
4169 &drain_queue,
4170 NULL,
4171 pt);
4172 } else {
4173 uint no_of_gc_workers = workers()->active_workers();
4174
4175 // Parallel reference processing
4176 assert(no_of_gc_workers <= rp->max_num_q(),
4177 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4178 no_of_gc_workers, rp->max_num_q());
4179
4180 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4181 stats = rp->process_discovered_references(&is_alive,
4182 &keep_alive,
4183 &drain_queue,
4184 &par_task_executor,
4185 pt);
4186 }
4187
4188 _gc_tracer_stw->report_gc_reference_stats(stats);
4189
4190 // We have completed copying any necessary live referent objects.
4191 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4192
4193 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4194 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4195 }
4196
4197 // Weak Reference processing during an evacuation pause (part 2).
4198 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4199 double ref_enq_start = os::elapsedTime();
4200
4201 ReferenceProcessor* rp = _ref_processor_stw;
4202 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4203
4204 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4205
4206 // Now enqueue any remaining on the discovered lists on to
4207 // the pending list.
4208 if (!rp->processing_is_mt()) {
4209 // Serial reference processing...
4210 rp->enqueue_discovered_references(NULL, pt);
4211 } else {
4212 // Parallel reference enqueueing
4213
4214 uint n_workers = workers()->active_workers();
4215
4216 assert(n_workers <= rp->max_num_q(),
4217 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4218 n_workers, rp->max_num_q());
4219
4220 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4221 rp->enqueue_discovered_references(&par_task_executor, pt);
4222 }
4223
4224 rp->verify_no_references_recorded();
4225 assert(!rp->discovery_enabled(), "should have been disabled");
4226
4227 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4228 // ensure that it is marked in the bitmap for concurrent marking to discover.
4229 if (collector_state()->during_initial_mark_pause()) {
4230 oop pll_head = Universe::reference_pending_list();
4231 if (pll_head != NULL) {
4232 _cm->mark_in_next_bitmap(pll_head);
4233 }
4234 }
4235
4236 // FIXME
4237 // CM's reference processing also cleans up the string and symbol tables.
4238 // Should we do that here also? We could, but it is a serial operation
4239 // and could significantly increase the pause time.
4240
4241 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4242 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4243 }
4244
4245 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4246 double merge_pss_time_start = os::elapsedTime();
4247 per_thread_states->flush();
4248 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4249 }
4250
4251 void G1CollectedHeap::pre_evacuate_collection_set() {
4252 _expand_heap_after_alloc_failure = true;
4253 _evacuation_failed = false;
4254
4255 // Disable the hot card cache.
4256 _hot_card_cache->reset_hot_cache_claimed_index();
4257 _hot_card_cache->set_use_cache(false);
4258
4259 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4260 _preserved_marks_set.assert_empty();
4261
4262 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4263
4264 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4265 if (collector_state()->during_initial_mark_pause()) {
4266 double start_clear_claimed_marks = os::elapsedTime();
4267
4268 ClassLoaderDataGraph::clear_claimed_marks();
4269
4270 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4271 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4272 }
4273 }
4274
4275 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4276 // Should G1EvacuationFailureALot be in effect for this GC?
4277 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4278
4279 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4280
4281 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4282
4283 double start_par_time_sec = os::elapsedTime();
4284 double end_par_time_sec;
4285
4286 {
4287 const uint n_workers = workers()->active_workers();
4288 G1RootProcessor root_processor(this, n_workers);
4289 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4290
4291 print_termination_stats_hdr();
4292
4293 workers()->run_task(&g1_par_task);
4294 end_par_time_sec = os::elapsedTime();
4295
4296 // Closing the inner scope will execute the destructor
4297 // for the G1RootProcessor object. We record the current
4298 // elapsed time before closing the scope so that time
4299 // taken for the destructor is NOT included in the
4300 // reported parallel time.
4301 }
4302
4303 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4304 phase_times->record_par_time(par_time_ms);
4305
4306 double code_root_fixup_time_ms =
4307 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4308 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4309 }
4310
4311 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4312 // Process any discovered reference objects - we have
4313 // to do this _before_ we retire the GC alloc regions
4314 // as we may have to copy some 'reachable' referent
4315 // objects (and their reachable sub-graphs) that were
4316 // not copied during the pause.
4317 if (g1_policy()->should_process_references()) {
4318 preserve_cm_referents(per_thread_states);
4319 process_discovered_references(per_thread_states);
4320 } else {
4321 ref_processor_stw()->verify_no_references_recorded();
4322 }
4323
4324 G1STWIsAliveClosure is_alive(this);
4325 G1KeepAliveClosure keep_alive(this);
4326
4327 {
4328 double start = os::elapsedTime();
4329
4330 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4331
4332 double time_ms = (os::elapsedTime() - start) * 1000.0;
4333 g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4334 }
4335
4336 if (G1StringDedup::is_enabled()) {
4337 double fixup_start = os::elapsedTime();
4338
4339 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4340
4341 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4342 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4343 }
4344
4345 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4346
4347 if (evacuation_failed()) {
4348 restore_after_evac_failure();
4349
4350 // Reset the G1EvacuationFailureALot counters and flags
4351 // Note: the values are reset only when an actual
4352 // evacuation failure occurs.
4353 NOT_PRODUCT(reset_evacuation_should_fail();)
4354 }
4355
4356 _preserved_marks_set.assert_empty();
4357
4358 // Enqueue any remaining references remaining on the STW
4359 // reference processor's discovered lists. We need to do
4360 // this after the card table is cleaned (and verified) as
4361 // the act of enqueueing entries on to the pending list
4362 // will log these updates (and dirty their associated
4363 // cards). We need these updates logged to update any
4364 // RSets.
4365 if (g1_policy()->should_process_references()) {
4366 enqueue_discovered_references(per_thread_states);
4367 } else {
4368 g1_policy()->phase_times()->record_ref_enq_time(0);
4369 }
4370
4371 _allocator->release_gc_alloc_regions(evacuation_info);
4372
4373 merge_per_thread_state_info(per_thread_states);
4374
4375 // Reset and re-enable the hot card cache.
4376 // Note the counts for the cards in the regions in the
4377 // collection set are reset when the collection set is freed.
4378 _hot_card_cache->reset_hot_cache();
4379 _hot_card_cache->set_use_cache(true);
4380
4381 purge_code_root_memory();
4382
4383 redirty_logged_cards();
4384 #if COMPILER2_OR_JVMCI
4385 double start = os::elapsedTime();
4386 DerivedPointerTable::update_pointers();
4387 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4388 #endif
4389 g1_policy()->print_age_table();
4390 }
4391
4392 void G1CollectedHeap::record_obj_copy_mem_stats() {
4393 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4394
4395 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4396 create_g1_evac_summary(&_old_evac_stats));
4397 }
4398
4399 void G1CollectedHeap::free_region(HeapRegion* hr,
4400 FreeRegionList* free_list,
4401 bool skip_remset,
4402 bool skip_hot_card_cache,
4403 bool locked) {
4404 assert(!hr->is_free(), "the region should not be free");
4405 assert(!hr->is_empty(), "the region should not be empty");
4406 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4407 assert(free_list != NULL, "pre-condition");
4408
4409 if (G1VerifyBitmaps) {
4410 MemRegion mr(hr->bottom(), hr->end());
4411 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4412 }
4413
4414 // Clear the card counts for this region.
4415 // Note: we only need to do this if the region is not young
4416 // (since we don't refine cards in young regions).
4417 if (!skip_hot_card_cache && !hr->is_young()) {
4418 _hot_card_cache->reset_card_counts(hr);
4419 }
4420 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4421 free_list->add_ordered(hr);
4422 }
4423
4424 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4425 FreeRegionList* free_list,
4426 bool skip_remset) {
4427 assert(hr->is_humongous(), "this is only for humongous regions");
4428 assert(free_list != NULL, "pre-condition");
4429 hr->clear_humongous();
4430 free_region(hr, free_list, skip_remset);
4431 }
4432
4433 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4434 const uint humongous_regions_removed) {
4435 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4436 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4437 _old_set.bulk_remove(old_regions_removed);
4438 _humongous_set.bulk_remove(humongous_regions_removed);
4439 }
4440
4441 }
4442
4443 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4444 assert(list != NULL, "list can't be null");
4445 if (!list->is_empty()) {
4446 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4447 _hrm.insert_list_into_free_list(list);
4448 }
4449 }
4450
4451 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4452 decrease_used(bytes);
4453 }
4454
4455 class G1ParScrubRemSetTask: public AbstractGangTask {
4456 protected:
4457 G1RemSet* _g1rs;
4458 HeapRegionClaimer _hrclaimer;
4459
4460 public:
4461 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4462 AbstractGangTask("G1 ScrubRS"),
4463 _g1rs(g1_rs),
4464 _hrclaimer(num_workers) {
4465 }
4466
4467 void work(uint worker_id) {
4468 _g1rs->scrub(worker_id, &_hrclaimer);
4469 }
4470 };
4471
4472 void G1CollectedHeap::scrub_rem_set() {
4473 uint num_workers = workers()->active_workers();
4474 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4475 workers()->run_task(&g1_par_scrub_rs_task);
4476 }
4477
4478 class G1FreeCollectionSetTask : public AbstractGangTask {
4479 private:
4480
4481 // Closure applied to all regions in the collection set to do work that needs to
4482 // be done serially in a single thread.
4483 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4484 private:
4485 EvacuationInfo* _evacuation_info;
4486 const size_t* _surviving_young_words;
4487
4488 // Bytes used in successfully evacuated regions before the evacuation.
4489 size_t _before_used_bytes;
4490 // Bytes used in unsucessfully evacuated regions before the evacuation
4491 size_t _after_used_bytes;
4492
4493 size_t _bytes_allocated_in_old_since_last_gc;
4494
4495 size_t _failure_used_words;
4496 size_t _failure_waste_words;
4497
4498 FreeRegionList _local_free_list;
4499 public:
4500 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4501 HeapRegionClosure(),
4502 _evacuation_info(evacuation_info),
4503 _surviving_young_words(surviving_young_words),
4504 _before_used_bytes(0),
4505 _after_used_bytes(0),
4506 _bytes_allocated_in_old_since_last_gc(0),
4507 _failure_used_words(0),
4508 _failure_waste_words(0),
4509 _local_free_list("Local Region List for CSet Freeing") {
4510 }
4511
4512 virtual bool do_heap_region(HeapRegion* r) {
4513 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4514
4515 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4516 g1h->clear_in_cset(r);
4517
4518 if (r->is_young()) {
4519 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4520 "Young index %d is wrong for region %u of type %s with %u young regions",
4521 r->young_index_in_cset(),
4522 r->hrm_index(),
4523 r->get_type_str(),
4524 g1h->collection_set()->young_region_length());
4525 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4526 r->record_surv_words_in_group(words_survived);
4527 }
4528
4529 if (!r->evacuation_failed()) {
4530 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4531 _before_used_bytes += r->used();
4532 g1h->free_region(r,
4533 &_local_free_list,
4534 true, /* skip_remset */
4535 true, /* skip_hot_card_cache */
4536 true /* locked */);
4537 } else {
4538 r->uninstall_surv_rate_group();
4539 r->set_young_index_in_cset(-1);
4540 r->set_evacuation_failed(false);
4541 // When moving a young gen region to old gen, we "allocate" that whole region
4542 // there. This is in addition to any already evacuated objects. Notify the
4543 // policy about that.
4544 // Old gen regions do not cause an additional allocation: both the objects
4545 // still in the region and the ones already moved are accounted for elsewhere.
4546 if (r->is_young()) {
4547 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4548 }
4549 // The region is now considered to be old.
4550 r->set_old();
4551 // Do some allocation statistics accounting. Regions that failed evacuation
4552 // are always made old, so there is no need to update anything in the young
4553 // gen statistics, but we need to update old gen statistics.
4554 size_t used_words = r->marked_bytes() / HeapWordSize;
4555
4556 _failure_used_words += used_words;
4557 _failure_waste_words += HeapRegion::GrainWords - used_words;
4558
4559 g1h->old_set_add(r);
4560 _after_used_bytes += r->used();
4561 }
4562 return false;
4563 }
4564
4565 void complete_work() {
4566 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4567
4568 _evacuation_info->set_regions_freed(_local_free_list.length());
4569 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4570
4571 g1h->prepend_to_freelist(&_local_free_list);
4572 g1h->decrement_summary_bytes(_before_used_bytes);
4573
4574 G1Policy* policy = g1h->g1_policy();
4575 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4576
4577 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4578 }
4579 };
4580
4581 G1CollectionSet* _collection_set;
4582 G1SerialFreeCollectionSetClosure _cl;
4583 const size_t* _surviving_young_words;
4584
4585 size_t _rs_lengths;
4586
4587 volatile jint _serial_work_claim;
4588
4589 struct WorkItem {
4590 uint region_idx;
4591 bool is_young;
4592 bool evacuation_failed;
4593
4594 WorkItem(HeapRegion* r) {
4595 region_idx = r->hrm_index();
4596 is_young = r->is_young();
4597 evacuation_failed = r->evacuation_failed();
4598 }
4599 };
4600
4601 volatile size_t _parallel_work_claim;
4602 size_t _num_work_items;
4603 WorkItem* _work_items;
4604
4605 void do_serial_work() {
4606 // Need to grab the lock to be allowed to modify the old region list.
4607 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4608 _collection_set->iterate(&_cl);
4609 }
4610
4611 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4612 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4613
4614 HeapRegion* r = g1h->region_at(region_idx);
4615 assert(!g1h->is_on_master_free_list(r), "sanity");
4616
4617 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4618
4619 if (!is_young) {
4620 g1h->_hot_card_cache->reset_card_counts(r);
4621 }
4622
4623 if (!evacuation_failed) {
4624 r->rem_set()->clear_locked();
4625 }
4626 }
4627
4628 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4629 private:
4630 size_t _cur_idx;
4631 WorkItem* _work_items;
4632 public:
4633 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4634
4635 virtual bool do_heap_region(HeapRegion* r) {
4636 _work_items[_cur_idx++] = WorkItem(r);
4637 return false;
4638 }
4639 };
4640
4641 void prepare_work() {
4642 G1PrepareFreeCollectionSetClosure cl(_work_items);
4643 _collection_set->iterate(&cl);
4644 }
4645
4646 void complete_work() {
4647 _cl.complete_work();
4648
4649 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4650 policy->record_max_rs_lengths(_rs_lengths);
4651 policy->cset_regions_freed();
4652 }
4653 public:
4654 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4655 AbstractGangTask("G1 Free Collection Set"),
4656 _cl(evacuation_info, surviving_young_words),
4657 _collection_set(collection_set),
4658 _surviving_young_words(surviving_young_words),
4659 _serial_work_claim(0),
4660 _rs_lengths(0),
4661 _parallel_work_claim(0),
4662 _num_work_items(collection_set->region_length()),
4663 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4664 prepare_work();
4665 }
4666
4667 ~G1FreeCollectionSetTask() {
4668 complete_work();
4669 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4670 }
4671
4672 // Chunk size for work distribution. The chosen value has been determined experimentally
4673 // to be a good tradeoff between overhead and achievable parallelism.
4674 static uint chunk_size() { return 32; }
4675
4676 virtual void work(uint worker_id) {
4677 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4678
4679 // Claim serial work.
4680 if (_serial_work_claim == 0) {
4681 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4682 if (value == 0) {
4683 double serial_time = os::elapsedTime();
4684 do_serial_work();
4685 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4686 }
4687 }
4688
4689 // Start parallel work.
4690 double young_time = 0.0;
4691 bool has_young_time = false;
4692 double non_young_time = 0.0;
4693 bool has_non_young_time = false;
4694
4695 while (true) {
4696 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4697 size_t cur = end - chunk_size();
4698
4699 if (cur >= _num_work_items) {
4700 break;
4701 }
4702
4703 double start_time = os::elapsedTime();
4704
4705 end = MIN2(end, _num_work_items);
4706
4707 for (; cur < end; cur++) {
4708 bool is_young = _work_items[cur].is_young;
4709
4710 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4711
4712 double end_time = os::elapsedTime();
4713 double time_taken = end_time - start_time;
4714 if (is_young) {
4715 young_time += time_taken;
4716 has_young_time = true;
4717 } else {
4718 non_young_time += time_taken;
4719 has_non_young_time = true;
4720 }
4721 start_time = end_time;
4722 }
4723 }
4724
4725 if (has_young_time) {
4726 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4727 }
4728 if (has_non_young_time) {
4729 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4730 }
4731 }
4732 };
4733
4734 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4735 _eden.clear();
4736
4737 double free_cset_start_time = os::elapsedTime();
4738
4739 {
4740 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4741 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4742
4743 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4744
4745 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4746 cl.name(),
4747 num_workers,
4748 _collection_set.region_length());
4749 workers()->run_task(&cl, num_workers);
4750 }
4751 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4752
4753 collection_set->clear();
4754 }
4755
4756 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4757 private:
4758 FreeRegionList* _free_region_list;
4759 HeapRegionSet* _proxy_set;
4760 uint _humongous_objects_reclaimed;
4761 uint _humongous_regions_reclaimed;
4762 size_t _freed_bytes;
4763 public:
4764
4765 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4766 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4767 }
4768
4769 virtual bool do_heap_region(HeapRegion* r) {
4770 if (!r->is_starts_humongous()) {
4771 return false;
4772 }
4773
4774 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4775
4776 oop obj = (oop)r->bottom();
4777 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4778
4779 // The following checks whether the humongous object is live are sufficient.
4780 // The main additional check (in addition to having a reference from the roots
4781 // or the young gen) is whether the humongous object has a remembered set entry.
4782 //
4783 // A humongous object cannot be live if there is no remembered set for it
4784 // because:
4785 // - there can be no references from within humongous starts regions referencing
4786 // the object because we never allocate other objects into them.
4787 // (I.e. there are no intra-region references that may be missed by the
4788 // remembered set)
4789 // - as soon there is a remembered set entry to the humongous starts region
4790 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4791 // until the end of a concurrent mark.
4792 //
4793 // It is not required to check whether the object has been found dead by marking
4794 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4795 // all objects allocated during that time are considered live.
4796 // SATB marking is even more conservative than the remembered set.
4797 // So if at this point in the collection there is no remembered set entry,
4798 // nobody has a reference to it.
4799 // At the start of collection we flush all refinement logs, and remembered sets
4800 // are completely up-to-date wrt to references to the humongous object.
4801 //
4802 // Other implementation considerations:
4803 // - never consider object arrays at this time because they would pose
4804 // considerable effort for cleaning up the the remembered sets. This is
4805 // required because stale remembered sets might reference locations that
4806 // are currently allocated into.
4807 uint region_idx = r->hrm_index();
4808 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4809 !r->rem_set()->is_empty()) {
4810 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",
4811 region_idx,
4812 (size_t)obj->size() * HeapWordSize,
4813 p2i(r->bottom()),
4814 r->rem_set()->occupied(),
4815 r->rem_set()->strong_code_roots_list_length(),
4816 next_bitmap->is_marked(r->bottom()),
4817 g1h->is_humongous_reclaim_candidate(region_idx),
4818 obj->is_typeArray()
4819 );
4820 return false;
4821 }
4822
4823 guarantee(obj->is_typeArray(),
4824 "Only eagerly reclaiming type arrays is supported, but the object "
4825 PTR_FORMAT " is not.", p2i(r->bottom()));
4826
4827 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",
4828 region_idx,
4829 (size_t)obj->size() * HeapWordSize,
4830 p2i(r->bottom()),
4831 r->rem_set()->occupied(),
4832 r->rem_set()->strong_code_roots_list_length(),
4833 next_bitmap->is_marked(r->bottom()),
4834 g1h->is_humongous_reclaim_candidate(region_idx),
4835 obj->is_typeArray()
4836 );
4837
4838 // Need to clear mark bit of the humongous object if already set.
4839 if (next_bitmap->is_marked(r->bottom())) {
4840 next_bitmap->clear(r->bottom());
4841 }
4842 _humongous_objects_reclaimed++;
4843 do {
4844 HeapRegion* next = g1h->next_region_in_humongous(r);
4845 _freed_bytes += r->used();
4846 r->set_containing_set(NULL);
4847 _humongous_regions_reclaimed++;
4848 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4849 r = next;
4850 } while (r != NULL);
4851
4852 return false;
4853 }
4854
4855 uint humongous_objects_reclaimed() {
4856 return _humongous_objects_reclaimed;
4857 }
4858
4859 uint humongous_regions_reclaimed() {
4860 return _humongous_regions_reclaimed;
4861 }
4862
4863 size_t bytes_freed() const {
4864 return _freed_bytes;
4865 }
4866 };
4867
4868 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4869 assert_at_safepoint(true);
4870
4871 if (!G1EagerReclaimHumongousObjects ||
4872 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4873 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4874 return;
4875 }
4876
4877 double start_time = os::elapsedTime();
4878
4879 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4880
4881 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4882 heap_region_iterate(&cl);
4883
4884 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4885
4886 G1HRPrinter* hrp = hr_printer();
4887 if (hrp->is_active()) {
4888 FreeRegionListIterator iter(&local_cleanup_list);
4889 while (iter.more_available()) {
4890 HeapRegion* hr = iter.get_next();
4891 hrp->cleanup(hr);
4892 }
4893 }
4894
4895 prepend_to_freelist(&local_cleanup_list);
4896 decrement_summary_bytes(cl.bytes_freed());
4897
4898 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4899 cl.humongous_objects_reclaimed());
4900 }
4901
4902 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4903 public:
4904 virtual bool do_heap_region(HeapRegion* r) {
4905 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4906 G1CollectedHeap::heap()->clear_in_cset(r);
4907 r->set_young_index_in_cset(-1);
4908 return false;
4909 }
4910 };
4911
4912 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4913 G1AbandonCollectionSetClosure cl;
4914 collection_set->iterate(&cl);
4915
4916 collection_set->clear();
4917 collection_set->stop_incremental_building();
4918 }
4919
4920 void G1CollectedHeap::set_free_regions_coming() {
4921 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4922
4923 assert(!free_regions_coming(), "pre-condition");
4924 _free_regions_coming = true;
4925 }
4926
4927 void G1CollectedHeap::reset_free_regions_coming() {
4928 assert(free_regions_coming(), "pre-condition");
4929
4930 {
4931 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4932 _free_regions_coming = false;
4933 SecondaryFreeList_lock->notify_all();
4934 }
4935
4936 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4937 }
4938
4939 void G1CollectedHeap::wait_while_free_regions_coming() {
4940 // Most of the time we won't have to wait, so let's do a quick test
4941 // first before we take the lock.
4942 if (!free_regions_coming()) {
4943 return;
4944 }
4945
4946 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4947
4948 {
4949 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4950 while (free_regions_coming()) {
4951 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4952 }
4953 }
4954
4955 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4956 }
4957
4958 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4959 return _allocator->is_retained_old_region(hr);
4960 }
4961
4962 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4963 _eden.add(hr);
4964 _g1_policy->set_region_eden(hr);
4965 }
4966
4967 #ifdef ASSERT
4968
4969 class NoYoungRegionsClosure: public HeapRegionClosure {
4970 private:
4971 bool _success;
4972 public:
4973 NoYoungRegionsClosure() : _success(true) { }
4974 bool do_heap_region(HeapRegion* r) {
4975 if (r->is_young()) {
4976 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4977 p2i(r->bottom()), p2i(r->end()));
4978 _success = false;
4979 }
4980 return false;
4981 }
4982 bool success() { return _success; }
4983 };
4984
4985 bool G1CollectedHeap::check_young_list_empty() {
4986 bool ret = (young_regions_count() == 0);
4987
4988 NoYoungRegionsClosure closure;
4989 heap_region_iterate(&closure);
4990 ret = ret && closure.success();
4991
4992 return ret;
4993 }
4994
4995 #endif // ASSERT
4996
4997 class TearDownRegionSetsClosure : public HeapRegionClosure {
4998 private:
4999 HeapRegionSet *_old_set;
5000
5001 public:
5002 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5003
5004 bool do_heap_region(HeapRegion* r) {
5005 if (r->is_old()) {
5006 _old_set->remove(r);
5007 } else if(r->is_young()) {
5008 r->uninstall_surv_rate_group();
5009 } else {
5010 // We ignore free regions, we'll empty the free list afterwards.
5011 // We ignore humongous regions, we're not tearing down the
5012 // humongous regions set.
5013 assert(r->is_free() || r->is_humongous(),
5014 "it cannot be another type");
5015 }
5016 return false;
5017 }
5018
5019 ~TearDownRegionSetsClosure() {
5020 assert(_old_set->is_empty(), "post-condition");
5021 }
5022 };
5023
5024 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5025 assert_at_safepoint(true /* should_be_vm_thread */);
5026
5027 if (!free_list_only) {
5028 TearDownRegionSetsClosure cl(&_old_set);
5029 heap_region_iterate(&cl);
5030
5031 // Note that emptying the _young_list is postponed and instead done as
5032 // the first step when rebuilding the regions sets again. The reason for
5033 // this is that during a full GC string deduplication needs to know if
5034 // a collected region was young or old when the full GC was initiated.
5035 }
5036 _hrm.remove_all_free_regions();
5037 }
5038
5039 void G1CollectedHeap::increase_used(size_t bytes) {
5040 _summary_bytes_used += bytes;
5041 }
5042
5043 void G1CollectedHeap::decrease_used(size_t bytes) {
5044 assert(_summary_bytes_used >= bytes,
5045 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5046 _summary_bytes_used, bytes);
5047 _summary_bytes_used -= bytes;
5048 }
5049
5050 void G1CollectedHeap::set_used(size_t bytes) {
5051 _summary_bytes_used = bytes;
5052 }
5053
5054 class RebuildRegionSetsClosure : public HeapRegionClosure {
5055 private:
5056 bool _free_list_only;
5057 HeapRegionSet* _old_set;
5058 HeapRegionManager* _hrm;
5059 size_t _total_used;
5060
5061 public:
5062 RebuildRegionSetsClosure(bool free_list_only,
5063 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5064 _free_list_only(free_list_only),
5065 _old_set(old_set), _hrm(hrm), _total_used(0) {
5066 assert(_hrm->num_free_regions() == 0, "pre-condition");
5067 if (!free_list_only) {
5068 assert(_old_set->is_empty(), "pre-condition");
5069 }
5070 }
5071
5072 bool do_heap_region(HeapRegion* r) {
5073 if (r->is_empty()) {
5074 // Add free regions to the free list
5075 r->set_free();
5076 r->set_allocation_context(AllocationContext::system());
5077 _hrm->insert_into_free_list(r);
5078 } else if (!_free_list_only) {
5079
5080 if (r->is_humongous()) {
5081 // We ignore humongous regions. We left the humongous set unchanged.
5082 } else {
5083 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5084 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5085 r->move_to_old();
5086 _old_set->add(r);
5087 }
5088 _total_used += r->used();
5089 }
5090
5091 return false;
5092 }
5093
5094 size_t total_used() {
5095 return _total_used;
5096 }
5097 };
5098
5099 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5100 assert_at_safepoint(true /* should_be_vm_thread */);
5101
5102 if (!free_list_only) {
5103 _eden.clear();
5104 _survivor.clear();
5105 }
5106
5107 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5108 heap_region_iterate(&cl);
5109
5110 if (!free_list_only) {
5111 set_used(cl.total_used());
5112 if (_archive_allocator != NULL) {
5113 _archive_allocator->clear_used();
5114 }
5115 }
5116 assert(used_unlocked() == recalculate_used(),
5117 "inconsistent used_unlocked(), "
5118 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5119 used_unlocked(), recalculate_used());
5120 }
5121
5122 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5123 HeapRegion* hr = heap_region_containing(p);
5124 return hr->is_in(p);
5125 }
5126
5127 // Methods for the mutator alloc region
5128
5129 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5130 bool force) {
5131 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5132 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5133 if (force || should_allocate) {
5134 HeapRegion* new_alloc_region = new_region(word_size,
5135 false /* is_old */,
5136 false /* do_expand */);
5137 if (new_alloc_region != NULL) {
5138 set_region_short_lived_locked(new_alloc_region);
5139 _hr_printer.alloc(new_alloc_region, !should_allocate);
5140 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5141 return new_alloc_region;
5142 }
5143 }
5144 return NULL;
5145 }
5146
5147 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5148 size_t allocated_bytes) {
5149 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5150 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5151
5152 collection_set()->add_eden_region(alloc_region);
5153 increase_used(allocated_bytes);
5154 _hr_printer.retire(alloc_region);
5155 // We update the eden sizes here, when the region is retired,
5156 // instead of when it's allocated, since this is the point that its
5157 // used space has been recored in _summary_bytes_used.
5158 g1mm()->update_eden_size();
5159 }
5160
5161 // Methods for the GC alloc regions
5162
5163 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5164 if (dest.is_old()) {
5165 return true;
5166 } else {
5167 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5168 }
5169 }
5170
5171 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5172 assert(FreeList_lock->owned_by_self(), "pre-condition");
5173
5174 if (!has_more_regions(dest)) {
5175 return NULL;
5176 }
5177
5178 const bool is_survivor = dest.is_young();
5179
5180 HeapRegion* new_alloc_region = new_region(word_size,
5181 !is_survivor,
5182 true /* do_expand */);
5183 if (new_alloc_region != NULL) {
5184 // We really only need to do this for old regions given that we
5185 // should never scan survivors. But it doesn't hurt to do it
5186 // for survivors too.
5187 new_alloc_region->record_timestamp();
5188 if (is_survivor) {
5189 new_alloc_region->set_survivor();
5190 _survivor.add(new_alloc_region);
5191 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5192 } else {
5193 new_alloc_region->set_old();
5194 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5195 }
5196 _hr_printer.alloc(new_alloc_region);
5197 bool during_im = collector_state()->during_initial_mark_pause();
5198 new_alloc_region->note_start_of_copying(during_im);
5199 return new_alloc_region;
5200 }
5201 return NULL;
5202 }
5203
5204 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5205 size_t allocated_bytes,
5206 InCSetState dest) {
5207 bool during_im = collector_state()->during_initial_mark_pause();
5208 alloc_region->note_end_of_copying(during_im);
5209 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5210 if (dest.is_old()) {
5211 _old_set.add(alloc_region);
5212 }
5213 _hr_printer.retire(alloc_region);
5214 }
5215
5216 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5217 bool expanded = false;
5218 uint index = _hrm.find_highest_free(&expanded);
5219
5220 if (index != G1_NO_HRM_INDEX) {
5221 if (expanded) {
5222 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5223 HeapRegion::GrainWords * HeapWordSize);
5224 }
5225 _hrm.allocate_free_regions_starting_at(index, 1);
5226 return region_at(index);
5227 }
5228 return NULL;
5229 }
5230
5231 // Optimized nmethod scanning
5232
5233 class RegisterNMethodOopClosure: public OopClosure {
5234 G1CollectedHeap* _g1h;
5235 nmethod* _nm;
5236
5237 template <class T> void do_oop_work(T* p) {
5238 T heap_oop = oopDesc::load_heap_oop(p);
5239 if (!oopDesc::is_null(heap_oop)) {
5240 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5241 HeapRegion* hr = _g1h->heap_region_containing(obj);
5242 assert(!hr->is_continues_humongous(),
5243 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5244 " starting at " HR_FORMAT,
5245 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5246
5247 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5248 hr->add_strong_code_root_locked(_nm);
5249 }
5250 }
5251
5252 public:
5253 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5254 _g1h(g1h), _nm(nm) {}
5255
5256 void do_oop(oop* p) { do_oop_work(p); }
5257 void do_oop(narrowOop* p) { do_oop_work(p); }
5258 };
5259
5260 class UnregisterNMethodOopClosure: public OopClosure {
5261 G1CollectedHeap* _g1h;
5262 nmethod* _nm;
5263
5264 template <class T> void do_oop_work(T* p) {
5265 T heap_oop = oopDesc::load_heap_oop(p);
5266 if (!oopDesc::is_null(heap_oop)) {
5267 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5268 HeapRegion* hr = _g1h->heap_region_containing(obj);
5269 assert(!hr->is_continues_humongous(),
5270 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5271 " starting at " HR_FORMAT,
5272 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5273
5274 hr->remove_strong_code_root(_nm);
5275 }
5276 }
5277
5278 public:
5279 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5280 _g1h(g1h), _nm(nm) {}
5281
5282 void do_oop(oop* p) { do_oop_work(p); }
5283 void do_oop(narrowOop* p) { do_oop_work(p); }
5284 };
5285
5286 // Returns true if the reference points to an object that
5287 // can move in an incremental collection.
5288 bool G1CollectedHeap::is_scavengable(oop obj) {
5289 HeapRegion* hr = heap_region_containing(obj);
5290 return !hr->is_pinned();
5291 }
5292
5293 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5294 guarantee(nm != NULL, "sanity");
5295 RegisterNMethodOopClosure reg_cl(this, nm);
5296 nm->oops_do(®_cl);
5297 }
5298
5299 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5300 guarantee(nm != NULL, "sanity");
5301 UnregisterNMethodOopClosure reg_cl(this, nm);
5302 nm->oops_do(®_cl, true);
5303 }
5304
5305 void G1CollectedHeap::purge_code_root_memory() {
5306 double purge_start = os::elapsedTime();
5307 G1CodeRootSet::purge();
5308 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5309 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5310 }
5311
5312 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5313 G1CollectedHeap* _g1h;
5314
5315 public:
5316 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5317 _g1h(g1h) {}
5318
5319 void do_code_blob(CodeBlob* cb) {
5320 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5321 if (nm == NULL) {
5322 return;
5323 }
5324
5325 if (ScavengeRootsInCode) {
5326 _g1h->register_nmethod(nm);
5327 }
5328 }
5329 };
5330
5331 void G1CollectedHeap::rebuild_strong_code_roots() {
5332 RebuildStrongCodeRootClosure blob_cl(this);
5333 CodeCache::blobs_do(&blob_cl);
5334 }
5335
5336 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5337 GrowableArray<GCMemoryManager*> memory_managers(2);
5338 memory_managers.append(&_memory_manager);
5339 memory_managers.append(&_full_gc_memory_manager);
5340 return memory_managers;
5341 }
5342
5343 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5344 GrowableArray<MemoryPool*> memory_pools(3);
5345 memory_pools.append(_eden_pool);
5346 memory_pools.append(_survivor_pool);
5347 memory_pools.append(_old_pool);
5348 return memory_pools;
5349 }