1 /*
2 * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1BarrierSet.hpp"
33 #include "gc/g1/g1CollectedHeap.inline.hpp"
34 #include "gc/g1/g1CollectionSet.hpp"
35 #include "gc/g1/g1CollectorPolicy.hpp"
36 #include "gc/g1/g1CollectorState.hpp"
37 #include "gc/g1/g1ConcurrentRefine.hpp"
38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1MemoryPool.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1StringDedup.hpp"
56 #include "gc/g1/g1ThreadLocalData.hpp"
57 #include "gc/g1/g1YCTypes.hpp"
58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
59 #include "gc/g1/heapRegion.inline.hpp"
60 #include "gc/g1/heapRegionRemSet.hpp"
61 #include "gc/g1/heapRegionSet.inline.hpp"
62 #include "gc/g1/vm_operations_g1.hpp"
63 #include "gc/shared/adaptiveSizePolicy.hpp"
64 #include "gc/shared/gcHeapSummary.hpp"
65 #include "gc/shared/gcId.hpp"
66 #include "gc/shared/gcLocker.hpp"
67 #include "gc/shared/gcTimer.hpp"
68 #include "gc/shared/gcTrace.hpp"
69 #include "gc/shared/gcTraceTime.inline.hpp"
70 #include "gc/shared/generationSpec.hpp"
71 #include "gc/shared/isGCActiveMark.hpp"
72 #include "gc/shared/oopStorageParState.hpp"
73 #include "gc/shared/preservedMarks.inline.hpp"
74 #include "gc/shared/suspendibleThreadSet.hpp"
75 #include "gc/shared/referenceProcessor.inline.hpp"
76 #include "gc/shared/taskqueue.inline.hpp"
77 #include "gc/shared/weakProcessor.hpp"
78 #include "logging/log.hpp"
79 #include "memory/allocation.hpp"
80 #include "memory/iterator.hpp"
81 #include "memory/metaspaceShared.hpp"
82 #include "memory/resourceArea.hpp"
83 #include "oops/access.inline.hpp"
84 #include "oops/compressedOops.inline.hpp"
85 #include "oops/oop.inline.hpp"
86 #include "prims/resolvedMethodTable.hpp"
87 #include "runtime/atomic.hpp"
88 #include "runtime/flags/flagSetting.hpp"
89 #include "runtime/handles.inline.hpp"
90 #include "runtime/init.hpp"
91 #include "runtime/orderAccess.hpp"
92 #include "runtime/threadSMR.hpp"
93 #include "runtime/vmThread.hpp"
94 #include "utilities/align.hpp"
95 #include "utilities/globalDefinitions.hpp"
96 #include "utilities/stack.inline.hpp"
97
98 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
99
100 // INVARIANTS/NOTES
101 //
102 // All allocation activity covered by the G1CollectedHeap interface is
103 // serialized by acquiring the HeapLock. This happens in mem_allocate
104 // and allocate_new_tlab, which are the "entry" points to the
105 // allocation code from the rest of the JVM. (Note that this does not
106 // apply to TLAB allocation, which is not part of this interface: it
107 // is done by clients of this interface.)
108
109 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
110 private:
111 size_t _num_dirtied;
112 G1CollectedHeap* _g1h;
113 G1CardTable* _g1_ct;
114
region_for_card(jbyte * card_ptr) const115 HeapRegion* region_for_card(jbyte* card_ptr) const {
116 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
117 }
118
will_become_free(HeapRegion * hr) const119 bool will_become_free(HeapRegion* hr) const {
120 // A region will be freed by free_collection_set if the region is in the
121 // collection set and has not had an evacuation failure.
122 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
123 }
124
125 public:
RedirtyLoggedCardTableEntryClosure(G1CollectedHeap * g1h)126 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
127 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
128
do_card_ptr(jbyte * card_ptr,uint worker_i)129 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
130 HeapRegion* hr = region_for_card(card_ptr);
131
132 // Should only dirty cards in regions that won't be freed.
133 if (!will_become_free(hr)) {
134 *card_ptr = G1CardTable::dirty_card_val();
135 _num_dirtied++;
136 }
137
138 return true;
139 }
140
num_dirtied() const141 size_t num_dirtied() const { return _num_dirtied; }
142 };
143
144
reset_from_card_cache(uint start_idx,size_t num_regions)145 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
146 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
147 }
148
on_commit(uint start_idx,size_t num_regions,bool zero_filled)149 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
150 // The from card cache is not the memory that is actually committed. So we cannot
151 // take advantage of the zero_filled parameter.
152 reset_from_card_cache(start_idx, num_regions);
153 }
154
155
new_heap_region(uint hrs_index,MemRegion mr)156 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
157 MemRegion mr) {
158 return new HeapRegion(hrs_index, bot(), mr);
159 }
160
161 // Private methods.
162
new_region(size_t word_size,bool is_old,bool do_expand)163 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
164 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
165 "the only time we use this to allocate a humongous region is "
166 "when we are allocating a single humongous region");
167
168 HeapRegion* res = _hrm.allocate_free_region(is_old);
169
170 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
171 // Currently, only attempts to allocate GC alloc regions set
172 // do_expand to true. So, we should only reach here during a
173 // safepoint. If this assumption changes we might have to
174 // reconsider the use of _expand_heap_after_alloc_failure.
175 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
176
177 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
178 word_size * HeapWordSize);
179
180 if (expand(word_size * HeapWordSize)) {
181 // Given that expand() succeeded in expanding the heap, and we
182 // always expand the heap by an amount aligned to the heap
183 // region size, the free list should in theory not be empty.
184 // In either case allocate_free_region() will check for NULL.
185 res = _hrm.allocate_free_region(is_old);
186 } else {
187 _expand_heap_after_alloc_failure = false;
188 }
189 }
190 return res;
191 }
192
193 HeapWord*
humongous_obj_allocate_initialize_regions(uint first,uint num_regions,size_t word_size)194 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
195 uint num_regions,
196 size_t word_size) {
197 assert(first != G1_NO_HRM_INDEX, "pre-condition");
198 assert(is_humongous(word_size), "word_size should be humongous");
199 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
200
201 // Index of last region in the series.
202 uint last = first + num_regions - 1;
203
204 // We need to initialize the region(s) we just discovered. This is
205 // a bit tricky given that it can happen concurrently with
206 // refinement threads refining cards on these regions and
207 // potentially wanting to refine the BOT as they are scanning
208 // those cards (this can happen shortly after a cleanup; see CR
209 // 6991377). So we have to set up the region(s) carefully and in
210 // a specific order.
211
212 // The word size sum of all the regions we will allocate.
213 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
214 assert(word_size <= word_size_sum, "sanity");
215
216 // This will be the "starts humongous" region.
217 HeapRegion* first_hr = region_at(first);
218 // The header of the new object will be placed at the bottom of
219 // the first region.
220 HeapWord* new_obj = first_hr->bottom();
221 // This will be the new top of the new object.
222 HeapWord* obj_top = new_obj + word_size;
223
224 // First, we need to zero the header of the space that we will be
225 // allocating. When we update top further down, some refinement
226 // threads might try to scan the region. By zeroing the header we
227 // ensure that any thread that will try to scan the region will
228 // come across the zero klass word and bail out.
229 //
230 // NOTE: It would not have been correct to have used
231 // CollectedHeap::fill_with_object() and make the space look like
232 // an int array. The thread that is doing the allocation will
233 // later update the object header to a potentially different array
234 // type and, for a very short period of time, the klass and length
235 // fields will be inconsistent. This could cause a refinement
236 // thread to calculate the object size incorrectly.
237 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
238
239 // Next, pad out the unused tail of the last region with filler
240 // objects, for improved usage accounting.
241 // How many words we use for filler objects.
242 size_t word_fill_size = word_size_sum - word_size;
243
244 // How many words memory we "waste" which cannot hold a filler object.
245 size_t words_not_fillable = 0;
246
247 if (word_fill_size >= min_fill_size()) {
248 fill_with_objects(obj_top, word_fill_size);
249 } else if (word_fill_size > 0) {
250 // We have space to fill, but we cannot fit an object there.
251 words_not_fillable = word_fill_size;
252 word_fill_size = 0;
253 }
254
255 // We will set up the first region as "starts humongous". This
256 // will also update the BOT covering all the regions to reflect
257 // that there is a single object that starts at the bottom of the
258 // first region.
259 first_hr->set_starts_humongous(obj_top, word_fill_size);
260 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
261 // Then, if there are any, we will set up the "continues
262 // humongous" regions.
263 HeapRegion* hr = NULL;
264 for (uint i = first + 1; i <= last; ++i) {
265 hr = region_at(i);
266 hr->set_continues_humongous(first_hr);
267 _g1_policy->remset_tracker()->update_at_allocate(hr);
268 }
269
270 // Up to this point no concurrent thread would have been able to
271 // do any scanning on any region in this series. All the top
272 // fields still point to bottom, so the intersection between
273 // [bottom,top] and [card_start,card_end] will be empty. Before we
274 // update the top fields, we'll do a storestore to make sure that
275 // no thread sees the update to top before the zeroing of the
276 // object header and the BOT initialization.
277 OrderAccess::storestore();
278
279 // Now, we will update the top fields of the "continues humongous"
280 // regions except the last one.
281 for (uint i = first; i < last; ++i) {
282 hr = region_at(i);
283 hr->set_top(hr->end());
284 }
285
286 hr = region_at(last);
287 // If we cannot fit a filler object, we must set top to the end
288 // of the humongous object, otherwise we cannot iterate the heap
289 // and the BOT will not be complete.
290 hr->set_top(hr->end() - words_not_fillable);
291
292 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
293 "obj_top should be in last region");
294
295 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
296
297 assert(words_not_fillable == 0 ||
298 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
299 "Miscalculation in humongous allocation");
300
301 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
302
303 for (uint i = first; i <= last; ++i) {
304 hr = region_at(i);
305 _humongous_set.add(hr);
306 _hr_printer.alloc(hr);
307 }
308
309 return new_obj;
310 }
311
humongous_obj_size_in_regions(size_t word_size)312 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
313 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
314 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
315 }
316
317 // If could fit into free regions w/o expansion, try.
318 // Otherwise, if can expand, do so.
319 // Otherwise, if using ex regions might help, try with ex given back.
humongous_obj_allocate(size_t word_size)320 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
321 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
322
323 _verifier->verify_region_sets_optional();
324
325 uint first = G1_NO_HRM_INDEX;
326 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
327
328 if (obj_regions == 1) {
329 // Only one region to allocate, try to use a fast path by directly allocating
330 // from the free lists. Do not try to expand here, we will potentially do that
331 // later.
332 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
333 if (hr != NULL) {
334 first = hr->hrm_index();
335 }
336 } else {
337 // Policy: Try only empty regions (i.e. already committed first). Maybe we
338 // are lucky enough to find some.
339 first = _hrm.find_contiguous_only_empty(obj_regions);
340 if (first != G1_NO_HRM_INDEX) {
341 _hrm.allocate_free_regions_starting_at(first, obj_regions);
342 }
343 }
344
345 if (first == G1_NO_HRM_INDEX) {
346 // Policy: We could not find enough regions for the humongous object in the
347 // free list. Look through the heap to find a mix of free and uncommitted regions.
348 // If so, try expansion.
349 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
350 if (first != G1_NO_HRM_INDEX) {
351 // We found something. Make sure these regions are committed, i.e. expand
352 // the heap. Alternatively we could do a defragmentation GC.
353 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
354 word_size * HeapWordSize);
355
356 _hrm.expand_at(first, obj_regions, workers());
357 g1_policy()->record_new_heap_size(num_regions());
358
359 #ifdef ASSERT
360 for (uint i = first; i < first + obj_regions; ++i) {
361 HeapRegion* hr = region_at(i);
362 assert(hr->is_free(), "sanity");
363 assert(hr->is_empty(), "sanity");
364 assert(is_on_master_free_list(hr), "sanity");
365 }
366 #endif
367 _hrm.allocate_free_regions_starting_at(first, obj_regions);
368 } else {
369 // Policy: Potentially trigger a defragmentation GC.
370 }
371 }
372
373 HeapWord* result = NULL;
374 if (first != G1_NO_HRM_INDEX) {
375 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
376 assert(result != NULL, "it should always return a valid result");
377
378 // A successful humongous object allocation changes the used space
379 // information of the old generation so we need to recalculate the
380 // sizes and update the jstat counters here.
381 g1mm()->update_sizes();
382 }
383
384 _verifier->verify_region_sets_optional();
385
386 return result;
387 }
388
allocate_new_tlab(size_t min_size,size_t requested_size,size_t * actual_size)389 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
390 size_t requested_size,
391 size_t* actual_size) {
392 assert_heap_not_locked_and_not_at_safepoint();
393 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
394
395 return attempt_allocation(min_size, requested_size, actual_size);
396 }
397
398 HeapWord*
mem_allocate(size_t word_size,bool * gc_overhead_limit_was_exceeded)399 G1CollectedHeap::mem_allocate(size_t word_size,
400 bool* gc_overhead_limit_was_exceeded) {
401 assert_heap_not_locked_and_not_at_safepoint();
402
403 if (is_humongous(word_size)) {
404 return attempt_allocation_humongous(word_size);
405 }
406 size_t dummy = 0;
407 return attempt_allocation(word_size, word_size, &dummy);
408 }
409
attempt_allocation_slow(size_t word_size)410 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
411 ResourceMark rm; // For retrieving the thread names in log messages.
412
413 // Make sure you read the note in attempt_allocation_humongous().
414
415 assert_heap_not_locked_and_not_at_safepoint();
416 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
417 "be called for humongous allocation requests");
418
419 // We should only get here after the first-level allocation attempt
420 // (attempt_allocation()) failed to allocate.
421
422 // We will loop until a) we manage to successfully perform the
423 // allocation or b) we successfully schedule a collection which
424 // fails to perform the allocation. b) is the only case when we'll
425 // return NULL.
426 HeapWord* result = NULL;
427 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
428 bool should_try_gc;
429 uint gc_count_before;
430
431 {
432 MutexLockerEx x(Heap_lock);
433 result = _allocator->attempt_allocation_locked(word_size);
434 if (result != NULL) {
435 return result;
436 }
437
438 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
439 // This is different to when only GCLocker::needs_gc() is set: try to avoid
440 // waiting because the GCLocker is active to not wait too long.
441 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
442 // No need for an ergo message here, can_expand_young_list() does this when
443 // it returns true.
444 result = _allocator->attempt_allocation_force(word_size);
445 if (result != NULL) {
446 return result;
447 }
448 }
449 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
450 // the GCLocker initiated GC has been performed and then retry. This includes
451 // the case when the GC Locker is not active but has not been performed.
452 should_try_gc = !GCLocker::needs_gc();
453 // Read the GC count while still holding the Heap_lock.
454 gc_count_before = total_collections();
455 }
456
457 if (should_try_gc) {
458 bool succeeded;
459 result = do_collection_pause(word_size, gc_count_before, &succeeded,
460 GCCause::_g1_inc_collection_pause);
461 if (result != NULL) {
462 assert(succeeded, "only way to get back a non-NULL result");
463 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
464 Thread::current()->name(), p2i(result));
465 return result;
466 }
467
468 if (succeeded) {
469 // We successfully scheduled a collection which failed to allocate. No
470 // point in trying to allocate further. We'll just return NULL.
471 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
472 SIZE_FORMAT " words", Thread::current()->name(), word_size);
473 return NULL;
474 }
475 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
476 Thread::current()->name(), word_size);
477 } else {
478 // Failed to schedule a collection.
479 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
480 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
481 SIZE_FORMAT " words", Thread::current()->name(), word_size);
482 return NULL;
483 }
484 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
485 // The GCLocker is either active or the GCLocker initiated
486 // GC has not yet been performed. Stall until it is and
487 // then retry the allocation.
488 GCLocker::stall_until_clear();
489 gclocker_retry_count += 1;
490 }
491
492 // We can reach here if we were unsuccessful in scheduling a
493 // collection (because another thread beat us to it) or if we were
494 // stalled due to the GC locker. In either can we should retry the
495 // allocation attempt in case another thread successfully
496 // performed a collection and reclaimed enough space. We do the
497 // first attempt (without holding the Heap_lock) here and the
498 // follow-on attempt will be at the start of the next loop
499 // iteration (after taking the Heap_lock).
500 size_t dummy = 0;
501 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
502 if (result != NULL) {
503 return result;
504 }
505
506 // Give a warning if we seem to be looping forever.
507 if ((QueuedAllocationWarningCount > 0) &&
508 (try_count % QueuedAllocationWarningCount == 0)) {
509 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
510 Thread::current()->name(), try_count, word_size);
511 }
512 }
513
514 ShouldNotReachHere();
515 return NULL;
516 }
517
begin_archive_alloc_range(bool open)518 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
519 assert_at_safepoint_on_vm_thread();
520 if (_archive_allocator == NULL) {
521 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
522 }
523 }
524
is_archive_alloc_too_large(size_t word_size)525 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
526 // Allocations in archive regions cannot be of a size that would be considered
527 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
528 // may be different at archive-restore time.
529 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
530 }
531
archive_mem_allocate(size_t word_size)532 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
533 assert_at_safepoint_on_vm_thread();
534 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
535 if (is_archive_alloc_too_large(word_size)) {
536 return NULL;
537 }
538 return _archive_allocator->archive_mem_allocate(word_size);
539 }
540
end_archive_alloc_range(GrowableArray<MemRegion> * ranges,size_t end_alignment_in_bytes)541 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
542 size_t end_alignment_in_bytes) {
543 assert_at_safepoint_on_vm_thread();
544 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
545
546 // Call complete_archive to do the real work, filling in the MemRegion
547 // array with the archive regions.
548 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
549 delete _archive_allocator;
550 _archive_allocator = NULL;
551 }
552
check_archive_addresses(MemRegion * ranges,size_t count)553 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
554 assert(ranges != NULL, "MemRegion array NULL");
555 assert(count != 0, "No MemRegions provided");
556 MemRegion reserved = _hrm.reserved();
557 for (size_t i = 0; i < count; i++) {
558 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
559 return false;
560 }
561 }
562 return true;
563 }
564
alloc_archive_regions(MemRegion * ranges,size_t count,bool open)565 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
566 size_t count,
567 bool open) {
568 assert(!is_init_completed(), "Expect to be called at JVM init time");
569 assert(ranges != NULL, "MemRegion array NULL");
570 assert(count != 0, "No MemRegions provided");
571 MutexLockerEx x(Heap_lock);
572
573 MemRegion reserved = _hrm.reserved();
574 HeapWord* prev_last_addr = NULL;
575 HeapRegion* prev_last_region = NULL;
576
577 // Temporarily disable pretouching of heap pages. This interface is used
578 // when mmap'ing archived heap data in, so pre-touching is wasted.
579 FlagSetting fs(AlwaysPreTouch, false);
580
581 // Enable archive object checking used by G1MarkSweep. We have to let it know
582 // about each archive range, so that objects in those ranges aren't marked.
583 G1ArchiveAllocator::enable_archive_object_check();
584
585 // For each specified MemRegion range, allocate the corresponding G1
586 // regions and mark them as archive regions. We expect the ranges
587 // in ascending starting address order, without overlap.
588 for (size_t i = 0; i < count; i++) {
589 MemRegion curr_range = ranges[i];
590 HeapWord* start_address = curr_range.start();
591 size_t word_size = curr_range.word_size();
592 HeapWord* last_address = curr_range.last();
593 size_t commits = 0;
594
595 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
596 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
597 p2i(start_address), p2i(last_address));
598 guarantee(start_address > prev_last_addr,
599 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
600 p2i(start_address), p2i(prev_last_addr));
601 prev_last_addr = last_address;
602
603 // Check for ranges that start in the same G1 region in which the previous
604 // range ended, and adjust the start address so we don't try to allocate
605 // the same region again. If the current range is entirely within that
606 // region, skip it, just adjusting the recorded top.
607 HeapRegion* start_region = _hrm.addr_to_region(start_address);
608 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
609 start_address = start_region->end();
610 if (start_address > last_address) {
611 increase_used(word_size * HeapWordSize);
612 start_region->set_top(last_address + 1);
613 continue;
614 }
615 start_region->set_top(start_address);
616 curr_range = MemRegion(start_address, last_address + 1);
617 start_region = _hrm.addr_to_region(start_address);
618 }
619
620 // Perform the actual region allocation, exiting if it fails.
621 // Then note how much new space we have allocated.
622 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
623 return false;
624 }
625 increase_used(word_size * HeapWordSize);
626 if (commits != 0) {
627 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
628 HeapRegion::GrainWords * HeapWordSize * commits);
629
630 }
631
632 // Mark each G1 region touched by the range as archive, add it to
633 // the old set, and set top.
634 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
635 HeapRegion* last_region = _hrm.addr_to_region(last_address);
636 prev_last_region = last_region;
637
638 while (curr_region != NULL) {
639 assert(curr_region->is_empty() && !curr_region->is_pinned(),
640 "Region already in use (index %u)", curr_region->hrm_index());
641 if (open) {
642 curr_region->set_open_archive();
643 } else {
644 curr_region->set_closed_archive();
645 }
646 _hr_printer.alloc(curr_region);
647 _old_set.add(curr_region);
648 HeapWord* top;
649 HeapRegion* next_region;
650 if (curr_region != last_region) {
651 top = curr_region->end();
652 next_region = _hrm.next_region_in_heap(curr_region);
653 } else {
654 top = last_address + 1;
655 next_region = NULL;
656 }
657 curr_region->set_top(top);
658 curr_region->set_first_dead(top);
659 curr_region->set_end_of_live(top);
660 curr_region = next_region;
661 }
662
663 // Notify mark-sweep of the archive
664 G1ArchiveAllocator::set_range_archive(curr_range, open);
665 }
666 return true;
667 }
668
fill_archive_regions(MemRegion * ranges,size_t count)669 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
670 assert(!is_init_completed(), "Expect to be called at JVM init time");
671 assert(ranges != NULL, "MemRegion array NULL");
672 assert(count != 0, "No MemRegions provided");
673 MemRegion reserved = _hrm.reserved();
674 HeapWord *prev_last_addr = NULL;
675 HeapRegion* prev_last_region = NULL;
676
677 // For each MemRegion, create filler objects, if needed, in the G1 regions
678 // that contain the address range. The address range actually within the
679 // MemRegion will not be modified. That is assumed to have been initialized
680 // elsewhere, probably via an mmap of archived heap data.
681 MutexLockerEx x(Heap_lock);
682 for (size_t i = 0; i < count; i++) {
683 HeapWord* start_address = ranges[i].start();
684 HeapWord* last_address = ranges[i].last();
685
686 assert(reserved.contains(start_address) && reserved.contains(last_address),
687 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
688 p2i(start_address), p2i(last_address));
689 assert(start_address > prev_last_addr,
690 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
691 p2i(start_address), p2i(prev_last_addr));
692
693 HeapRegion* start_region = _hrm.addr_to_region(start_address);
694 HeapRegion* last_region = _hrm.addr_to_region(last_address);
695 HeapWord* bottom_address = start_region->bottom();
696
697 // Check for a range beginning in the same region in which the
698 // previous one ended.
699 if (start_region == prev_last_region) {
700 bottom_address = prev_last_addr + 1;
701 }
702
703 // Verify that the regions were all marked as archive regions by
704 // alloc_archive_regions.
705 HeapRegion* curr_region = start_region;
706 while (curr_region != NULL) {
707 guarantee(curr_region->is_archive(),
708 "Expected archive region at index %u", curr_region->hrm_index());
709 if (curr_region != last_region) {
710 curr_region = _hrm.next_region_in_heap(curr_region);
711 } else {
712 curr_region = NULL;
713 }
714 }
715
716 prev_last_addr = last_address;
717 prev_last_region = last_region;
718
719 // Fill the memory below the allocated range with dummy object(s),
720 // if the region bottom does not match the range start, or if the previous
721 // range ended within the same G1 region, and there is a gap.
722 if (start_address != bottom_address) {
723 size_t fill_size = pointer_delta(start_address, bottom_address);
724 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
725 increase_used(fill_size * HeapWordSize);
726 }
727 }
728 }
729
attempt_allocation(size_t min_word_size,size_t desired_word_size,size_t * actual_word_size)730 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
731 size_t desired_word_size,
732 size_t* actual_word_size) {
733 assert_heap_not_locked_and_not_at_safepoint();
734 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
735 "be called for humongous allocation requests");
736
737 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
738
739 if (result == NULL) {
740 *actual_word_size = desired_word_size;
741 result = attempt_allocation_slow(desired_word_size);
742 }
743
744 assert_heap_not_locked();
745 if (result != NULL) {
746 assert(*actual_word_size != 0, "Actual size must have been set here");
747 dirty_young_block(result, *actual_word_size);
748 } else {
749 *actual_word_size = 0;
750 }
751
752 return result;
753 }
754
dealloc_archive_regions(MemRegion * ranges,size_t count,bool is_open)755 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
756 assert(!is_init_completed(), "Expect to be called at JVM init time");
757 assert(ranges != NULL, "MemRegion array NULL");
758 assert(count != 0, "No MemRegions provided");
759 MemRegion reserved = _hrm.reserved();
760 HeapWord* prev_last_addr = NULL;
761 HeapRegion* prev_last_region = NULL;
762 size_t size_used = 0;
763 size_t uncommitted_regions = 0;
764
765 // For each Memregion, free the G1 regions that constitute it, and
766 // notify mark-sweep that the range is no longer to be considered 'archive.'
767 MutexLockerEx x(Heap_lock);
768 for (size_t i = 0; i < count; i++) {
769 HeapWord* start_address = ranges[i].start();
770 HeapWord* last_address = ranges[i].last();
771
772 assert(reserved.contains(start_address) && reserved.contains(last_address),
773 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
774 p2i(start_address), p2i(last_address));
775 assert(start_address > prev_last_addr,
776 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
777 p2i(start_address), p2i(prev_last_addr));
778 size_used += ranges[i].byte_size();
779 prev_last_addr = last_address;
780
781 HeapRegion* start_region = _hrm.addr_to_region(start_address);
782 HeapRegion* last_region = _hrm.addr_to_region(last_address);
783
784 // Check for ranges that start in the same G1 region in which the previous
785 // range ended, and adjust the start address so we don't try to free
786 // the same region again. If the current range is entirely within that
787 // region, skip it.
788 if (start_region == prev_last_region) {
789 start_address = start_region->end();
790 if (start_address > last_address) {
791 continue;
792 }
793 start_region = _hrm.addr_to_region(start_address);
794 }
795 prev_last_region = last_region;
796
797 // After verifying that each region was marked as an archive region by
798 // alloc_archive_regions, set it free and empty and uncommit it.
799 HeapRegion* curr_region = start_region;
800 while (curr_region != NULL) {
801 guarantee(curr_region->is_archive(),
802 "Expected archive region at index %u", curr_region->hrm_index());
803 uint curr_index = curr_region->hrm_index();
804 _old_set.remove(curr_region);
805 curr_region->set_free();
806 curr_region->set_top(curr_region->bottom());
807 if (curr_region != last_region) {
808 curr_region = _hrm.next_region_in_heap(curr_region);
809 } else {
810 curr_region = NULL;
811 }
812 _hrm.shrink_at(curr_index, 1);
813 uncommitted_regions++;
814 }
815
816 // Notify mark-sweep that this is no longer an archive range.
817 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
818 }
819
820 if (uncommitted_regions != 0) {
821 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
822 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
823 }
824 decrease_used(size_used);
825 }
826
materialize_archived_object(oop obj)827 oop G1CollectedHeap::materialize_archived_object(oop obj) {
828 assert(obj != NULL, "archived obj is NULL");
829 assert(MetaspaceShared::is_archive_object(obj), "must be archived object");
830
831 // Loading an archived object makes it strongly reachable. If it is
832 // loaded during concurrent marking, it must be enqueued to the SATB
833 // queue, shading the previously white object gray.
834 G1BarrierSet::enqueue(obj);
835
836 return obj;
837 }
838
attempt_allocation_humongous(size_t word_size)839 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
840 ResourceMark rm; // For retrieving the thread names in log messages.
841
842 // The structure of this method has a lot of similarities to
843 // attempt_allocation_slow(). The reason these two were not merged
844 // into a single one is that such a method would require several "if
845 // allocation is not humongous do this, otherwise do that"
846 // conditional paths which would obscure its flow. In fact, an early
847 // version of this code did use a unified method which was harder to
848 // follow and, as a result, it had subtle bugs that were hard to
849 // track down. So keeping these two methods separate allows each to
850 // be more readable. It will be good to keep these two in sync as
851 // much as possible.
852
853 assert_heap_not_locked_and_not_at_safepoint();
854 assert(is_humongous(word_size), "attempt_allocation_humongous() "
855 "should only be called for humongous allocations");
856
857 // Humongous objects can exhaust the heap quickly, so we should check if we
858 // need to start a marking cycle at each humongous object allocation. We do
859 // the check before we do the actual allocation. The reason for doing it
860 // before the allocation is that we avoid having to keep track of the newly
861 // allocated memory while we do a GC.
862 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
863 word_size)) {
864 collect(GCCause::_g1_humongous_allocation);
865 }
866
867 // We will loop until a) we manage to successfully perform the
868 // allocation or b) we successfully schedule a collection which
869 // fails to perform the allocation. b) is the only case when we'll
870 // return NULL.
871 HeapWord* result = NULL;
872 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
873 bool should_try_gc;
874 uint gc_count_before;
875
876
877 {
878 MutexLockerEx x(Heap_lock);
879
880 // Given that humongous objects are not allocated in young
881 // regions, we'll first try to do the allocation without doing a
882 // collection hoping that there's enough space in the heap.
883 result = humongous_obj_allocate(word_size);
884 if (result != NULL) {
885 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
886 g1_policy()->old_gen_alloc_tracker()->
887 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
888 return result;
889 }
890
891 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
892 // the GCLocker initiated GC has been performed and then retry. This includes
893 // the case when the GC Locker is not active but has not been performed.
894 should_try_gc = !GCLocker::needs_gc();
895 // Read the GC count while still holding the Heap_lock.
896 gc_count_before = total_collections();
897 }
898
899 if (should_try_gc) {
900 bool succeeded;
901 result = do_collection_pause(word_size, gc_count_before, &succeeded,
902 GCCause::_g1_humongous_allocation);
903 if (result != NULL) {
904 assert(succeeded, "only way to get back a non-NULL result");
905 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
906 Thread::current()->name(), p2i(result));
907 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
908 g1_policy()->old_gen_alloc_tracker()->
909 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
910 return result;
911 }
912
913 if (succeeded) {
914 // We successfully scheduled a collection which failed to allocate. No
915 // point in trying to allocate further. We'll just return NULL.
916 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
917 SIZE_FORMAT " words", Thread::current()->name(), word_size);
918 return NULL;
919 }
920 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
921 Thread::current()->name(), word_size);
922 } else {
923 // Failed to schedule a collection.
924 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
925 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
926 SIZE_FORMAT " words", Thread::current()->name(), word_size);
927 return NULL;
928 }
929 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
930 // The GCLocker is either active or the GCLocker initiated
931 // GC has not yet been performed. Stall until it is and
932 // then retry the allocation.
933 GCLocker::stall_until_clear();
934 gclocker_retry_count += 1;
935 }
936
937
938 // We can reach here if we were unsuccessful in scheduling a
939 // collection (because another thread beat us to it) or if we were
940 // stalled due to the GC locker. In either can we should retry the
941 // allocation attempt in case another thread successfully
942 // performed a collection and reclaimed enough space.
943 // Humongous object allocation always needs a lock, so we wait for the retry
944 // in the next iteration of the loop, unlike for the regular iteration case.
945 // Give a warning if we seem to be looping forever.
946
947 if ((QueuedAllocationWarningCount > 0) &&
948 (try_count % QueuedAllocationWarningCount == 0)) {
949 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
950 Thread::current()->name(), try_count, word_size);
951 }
952 }
953
954 ShouldNotReachHere();
955 return NULL;
956 }
957
attempt_allocation_at_safepoint(size_t word_size,bool expect_null_mutator_alloc_region)958 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
959 bool expect_null_mutator_alloc_region) {
960 assert_at_safepoint_on_vm_thread();
961 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
962 "the current alloc region was unexpectedly found to be non-NULL");
963
964 if (!is_humongous(word_size)) {
965 return _allocator->attempt_allocation_locked(word_size);
966 } else {
967 HeapWord* result = humongous_obj_allocate(word_size);
968 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
969 collector_state()->set_initiate_conc_mark_if_possible(true);
970 }
971 return result;
972 }
973
974 ShouldNotReachHere();
975 }
976
977 class PostCompactionPrinterClosure: public HeapRegionClosure {
978 private:
979 G1HRPrinter* _hr_printer;
980 public:
do_heap_region(HeapRegion * hr)981 bool do_heap_region(HeapRegion* hr) {
982 assert(!hr->is_young(), "not expecting to find young regions");
983 _hr_printer->post_compaction(hr);
984 return false;
985 }
986
PostCompactionPrinterClosure(G1HRPrinter * hr_printer)987 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
988 : _hr_printer(hr_printer) { }
989 };
990
print_hrm_post_compaction()991 void G1CollectedHeap::print_hrm_post_compaction() {
992 if (_hr_printer.is_active()) {
993 PostCompactionPrinterClosure cl(hr_printer());
994 heap_region_iterate(&cl);
995 }
996 }
997
abort_concurrent_cycle()998 void G1CollectedHeap::abort_concurrent_cycle() {
999 // If we start the compaction before the CM threads finish
1000 // scanning the root regions we might trip them over as we'll
1001 // be moving objects / updating references. So let's wait until
1002 // they are done. By telling them to abort, they should complete
1003 // early.
1004 _cm->root_regions()->abort();
1005 _cm->root_regions()->wait_until_scan_finished();
1006
1007 // Disable discovery and empty the discovered lists
1008 // for the CM ref processor.
1009 _ref_processor_cm->disable_discovery();
1010 _ref_processor_cm->abandon_partial_discovery();
1011 _ref_processor_cm->verify_no_references_recorded();
1012
1013 // Abandon current iterations of concurrent marking and concurrent
1014 // refinement, if any are in progress.
1015 concurrent_mark()->concurrent_cycle_abort();
1016 }
1017
prepare_heap_for_full_collection()1018 void G1CollectedHeap::prepare_heap_for_full_collection() {
1019 // Make sure we'll choose a new allocation region afterwards.
1020 _allocator->release_mutator_alloc_region();
1021 _allocator->abandon_gc_alloc_regions();
1022 g1_rem_set()->cleanupHRRS();
1023
1024 // We may have added regions to the current incremental collection
1025 // set between the last GC or pause and now. We need to clear the
1026 // incremental collection set and then start rebuilding it afresh
1027 // after this full GC.
1028 abandon_collection_set(collection_set());
1029
1030 tear_down_region_sets(false /* free_list_only */);
1031 }
1032
verify_before_full_collection(bool explicit_gc)1033 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1034 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1035 assert(used() == recalculate_used(), "Should be equal");
1036 _verifier->verify_region_sets_optional();
1037 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1038 _verifier->check_bitmaps("Full GC Start");
1039 }
1040
prepare_heap_for_mutators()1041 void G1CollectedHeap::prepare_heap_for_mutators() {
1042 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1043 ClassLoaderDataGraph::purge();
1044 MetaspaceUtils::verify_metrics();
1045
1046 // Prepare heap for normal collections.
1047 assert(num_free_regions() == 0, "we should not have added any free regions");
1048 rebuild_region_sets(false /* free_list_only */);
1049 abort_refinement();
1050 resize_if_necessary_after_full_collection();
1051
1052 // Rebuild the strong code root lists for each region
1053 rebuild_strong_code_roots();
1054
1055 // Purge code root memory
1056 purge_code_root_memory();
1057
1058 // Start a new incremental collection set for the next pause
1059 start_new_collection_set();
1060
1061 _allocator->init_mutator_alloc_region();
1062
1063 // Post collection state updates.
1064 MetaspaceGC::compute_new_size();
1065 }
1066
abort_refinement()1067 void G1CollectedHeap::abort_refinement() {
1068 if (_hot_card_cache->use_cache()) {
1069 _hot_card_cache->reset_hot_cache();
1070 }
1071
1072 // Discard all remembered set updates.
1073 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1074 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1075 }
1076
verify_after_full_collection()1077 void G1CollectedHeap::verify_after_full_collection() {
1078 _hrm.verify_optional();
1079 _verifier->verify_region_sets_optional();
1080 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1081 // Clear the previous marking bitmap, if needed for bitmap verification.
1082 // Note we cannot do this when we clear the next marking bitmap in
1083 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1084 // objects marked during a full GC against the previous bitmap.
1085 // But we need to clear it before calling check_bitmaps below since
1086 // the full GC has compacted objects and updated TAMS but not updated
1087 // the prev bitmap.
1088 if (G1VerifyBitmaps) {
1089 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1090 _cm->clear_prev_bitmap(workers());
1091 }
1092 _verifier->check_bitmaps("Full GC End");
1093
1094 // At this point there should be no regions in the
1095 // entire heap tagged as young.
1096 assert(check_young_list_empty(), "young list should be empty at this point");
1097
1098 // Note: since we've just done a full GC, concurrent
1099 // marking is no longer active. Therefore we need not
1100 // re-enable reference discovery for the CM ref processor.
1101 // That will be done at the start of the next marking cycle.
1102 // We also know that the STW processor should no longer
1103 // discover any new references.
1104 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1105 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1106 _ref_processor_stw->verify_no_references_recorded();
1107 _ref_processor_cm->verify_no_references_recorded();
1108 }
1109
print_heap_after_full_collection(G1HeapTransition * heap_transition)1110 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1111 // Post collection logging.
1112 // We should do this after we potentially resize the heap so
1113 // that all the COMMIT / UNCOMMIT events are generated before
1114 // the compaction events.
1115 print_hrm_post_compaction();
1116 heap_transition->print();
1117 print_heap_after_gc();
1118 print_heap_regions();
1119 #ifdef TRACESPINNING
1120 ParallelTaskTerminator::print_termination_counts();
1121 #endif
1122 }
1123
do_full_collection(bool explicit_gc,bool clear_all_soft_refs)1124 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1125 bool clear_all_soft_refs) {
1126 assert_at_safepoint_on_vm_thread();
1127
1128 if (GCLocker::check_active_before_gc()) {
1129 // Full GC was not completed.
1130 return false;
1131 }
1132
1133 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1134 soft_ref_policy()->should_clear_all_soft_refs();
1135
1136 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1137 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1138
1139 collector.prepare_collection();
1140 collector.collect();
1141 collector.complete_collection();
1142
1143 // Full collection was successfully completed.
1144 return true;
1145 }
1146
do_full_collection(bool clear_all_soft_refs)1147 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1148 // Currently, there is no facility in the do_full_collection(bool) API to notify
1149 // the caller that the collection did not succeed (e.g., because it was locked
1150 // out by the GC locker). So, right now, we'll ignore the return value.
1151 bool dummy = do_full_collection(true, /* explicit_gc */
1152 clear_all_soft_refs);
1153 }
1154
resize_if_necessary_after_full_collection()1155 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1156 // Capacity, free and used after the GC counted as full regions to
1157 // include the waste in the following calculations.
1158 const size_t capacity_after_gc = capacity();
1159 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1160
1161 // This is enforced in arguments.cpp.
1162 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1163 "otherwise the code below doesn't make sense");
1164
1165 // We don't have floating point command-line arguments
1166 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1167 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1168 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1169 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1170
1171 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1172 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1173
1174 // We have to be careful here as these two calculations can overflow
1175 // 32-bit size_t's.
1176 double used_after_gc_d = (double) used_after_gc;
1177 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1178 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1179
1180 // Let's make sure that they are both under the max heap size, which
1181 // by default will make them fit into a size_t.
1182 double desired_capacity_upper_bound = (double) max_heap_size;
1183 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1184 desired_capacity_upper_bound);
1185 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1186 desired_capacity_upper_bound);
1187
1188 // We can now safely turn them into size_t's.
1189 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1190 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1191
1192 // This assert only makes sense here, before we adjust them
1193 // with respect to the min and max heap size.
1194 assert(minimum_desired_capacity <= maximum_desired_capacity,
1195 "minimum_desired_capacity = " SIZE_FORMAT ", "
1196 "maximum_desired_capacity = " SIZE_FORMAT,
1197 minimum_desired_capacity, maximum_desired_capacity);
1198
1199 // Should not be greater than the heap max size. No need to adjust
1200 // it with respect to the heap min size as it's a lower bound (i.e.,
1201 // we'll try to make the capacity larger than it, not smaller).
1202 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1203 // Should not be less than the heap min size. No need to adjust it
1204 // with respect to the heap max size as it's an upper bound (i.e.,
1205 // we'll try to make the capacity smaller than it, not greater).
1206 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1207
1208 if (capacity_after_gc < minimum_desired_capacity) {
1209 // Don't expand unless it's significant
1210 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1211
1212 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1213 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1214 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1215 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1216
1217 expand(expand_bytes, _workers);
1218
1219 // No expansion, now see if we want to shrink
1220 } else if (capacity_after_gc > maximum_desired_capacity) {
1221 // Capacity too large, compute shrinking size
1222 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1223
1224 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1225 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1226 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1227 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1228
1229 shrink(shrink_bytes);
1230 }
1231 }
1232
satisfy_failed_allocation_helper(size_t word_size,bool do_gc,bool clear_all_soft_refs,bool expect_null_mutator_alloc_region,bool * gc_succeeded)1233 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1234 bool do_gc,
1235 bool clear_all_soft_refs,
1236 bool expect_null_mutator_alloc_region,
1237 bool* gc_succeeded) {
1238 *gc_succeeded = true;
1239 // Let's attempt the allocation first.
1240 HeapWord* result =
1241 attempt_allocation_at_safepoint(word_size,
1242 expect_null_mutator_alloc_region);
1243 if (result != NULL) {
1244 return result;
1245 }
1246
1247 // In a G1 heap, we're supposed to keep allocation from failing by
1248 // incremental pauses. Therefore, at least for now, we'll favor
1249 // expansion over collection. (This might change in the future if we can
1250 // do something smarter than full collection to satisfy a failed alloc.)
1251 result = expand_and_allocate(word_size);
1252 if (result != NULL) {
1253 return result;
1254 }
1255
1256 if (do_gc) {
1257 // Expansion didn't work, we'll try to do a Full GC.
1258 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1259 clear_all_soft_refs);
1260 }
1261
1262 return NULL;
1263 }
1264
satisfy_failed_allocation(size_t word_size,bool * succeeded)1265 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1266 bool* succeeded) {
1267 assert_at_safepoint_on_vm_thread();
1268
1269 // Attempts to allocate followed by Full GC.
1270 HeapWord* result =
1271 satisfy_failed_allocation_helper(word_size,
1272 true, /* do_gc */
1273 false, /* clear_all_soft_refs */
1274 false, /* expect_null_mutator_alloc_region */
1275 succeeded);
1276
1277 if (result != NULL || !*succeeded) {
1278 return result;
1279 }
1280
1281 // Attempts to allocate followed by Full GC that will collect all soft references.
1282 result = satisfy_failed_allocation_helper(word_size,
1283 true, /* do_gc */
1284 true, /* clear_all_soft_refs */
1285 true, /* expect_null_mutator_alloc_region */
1286 succeeded);
1287
1288 if (result != NULL || !*succeeded) {
1289 return result;
1290 }
1291
1292 // Attempts to allocate, no GC
1293 result = satisfy_failed_allocation_helper(word_size,
1294 false, /* do_gc */
1295 false, /* clear_all_soft_refs */
1296 true, /* expect_null_mutator_alloc_region */
1297 succeeded);
1298
1299 if (result != NULL) {
1300 return result;
1301 }
1302
1303 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1304 "Flag should have been handled and cleared prior to this point");
1305
1306 // What else? We might try synchronous finalization later. If the total
1307 // space available is large enough for the allocation, then a more
1308 // complete compaction phase than we've tried so far might be
1309 // appropriate.
1310 return NULL;
1311 }
1312
1313 // Attempting to expand the heap sufficiently
1314 // to support an allocation of the given "word_size". If
1315 // successful, perform the allocation and return the address of the
1316 // allocated block, or else "NULL".
1317
expand_and_allocate(size_t word_size)1318 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1319 assert_at_safepoint_on_vm_thread();
1320
1321 _verifier->verify_region_sets_optional();
1322
1323 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1324 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1325 word_size * HeapWordSize);
1326
1327
1328 if (expand(expand_bytes, _workers)) {
1329 _hrm.verify_optional();
1330 _verifier->verify_region_sets_optional();
1331 return attempt_allocation_at_safepoint(word_size,
1332 false /* expect_null_mutator_alloc_region */);
1333 }
1334 return NULL;
1335 }
1336
expand(size_t expand_bytes,WorkGang * pretouch_workers,double * expand_time_ms)1337 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1338 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1339 aligned_expand_bytes = align_up(aligned_expand_bytes,
1340 HeapRegion::GrainBytes);
1341
1342 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1343 expand_bytes, aligned_expand_bytes);
1344
1345 if (is_maximal_no_gc()) {
1346 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1347 return false;
1348 }
1349
1350 double expand_heap_start_time_sec = os::elapsedTime();
1351 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1352 assert(regions_to_expand > 0, "Must expand by at least one region");
1353
1354 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1355 if (expand_time_ms != NULL) {
1356 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1357 }
1358
1359 if (expanded_by > 0) {
1360 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1361 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1362 g1_policy()->record_new_heap_size(num_regions());
1363 } else {
1364 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1365
1366 // The expansion of the virtual storage space was unsuccessful.
1367 // Let's see if it was because we ran out of swap.
1368 if (G1ExitOnExpansionFailure &&
1369 _hrm.available() >= regions_to_expand) {
1370 // We had head room...
1371 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1372 }
1373 }
1374 return regions_to_expand > 0;
1375 }
1376
shrink_helper(size_t shrink_bytes)1377 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1378 size_t aligned_shrink_bytes =
1379 ReservedSpace::page_align_size_down(shrink_bytes);
1380 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1381 HeapRegion::GrainBytes);
1382 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1383
1384 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1385 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1386
1387
1388 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",
1389 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1390 if (num_regions_removed > 0) {
1391 g1_policy()->record_new_heap_size(num_regions());
1392 } else {
1393 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1394 }
1395 }
1396
shrink(size_t shrink_bytes)1397 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1398 _verifier->verify_region_sets_optional();
1399
1400 // We should only reach here at the end of a Full GC which means we
1401 // should not not be holding to any GC alloc regions. The method
1402 // below will make sure of that and do any remaining clean up.
1403 _allocator->abandon_gc_alloc_regions();
1404
1405 // Instead of tearing down / rebuilding the free lists here, we
1406 // could instead use the remove_all_pending() method on free_list to
1407 // remove only the ones that we need to remove.
1408 tear_down_region_sets(true /* free_list_only */);
1409 shrink_helper(shrink_bytes);
1410 rebuild_region_sets(true /* free_list_only */);
1411
1412 _hrm.verify_optional();
1413 _verifier->verify_region_sets_optional();
1414 }
1415
1416 // Public methods.
1417
G1CollectedHeap(G1CollectorPolicy * collector_policy)1418 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1419 CollectedHeap(),
1420 _young_gen_sampling_thread(NULL),
1421 _collector_policy(collector_policy),
1422 _soft_ref_policy(),
1423 _card_table(NULL),
1424 _memory_manager("G1 Young Generation", "end of minor GC"),
1425 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1426 _eden_pool(NULL),
1427 _survivor_pool(NULL),
1428 _old_pool(NULL),
1429 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1430 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1431 _g1_policy(new G1Policy(_gc_timer_stw)),
1432 _collection_set(this, _g1_policy),
1433 _dirty_card_queue_set(false),
1434 _ref_processor_stw(NULL),
1435 _is_alive_closure_stw(this),
1436 _is_subject_to_discovery_stw(this),
1437 _ref_processor_cm(NULL),
1438 _is_alive_closure_cm(this),
1439 _is_subject_to_discovery_cm(this),
1440 _bot(NULL),
1441 _hot_card_cache(NULL),
1442 _g1_rem_set(NULL),
1443 _cr(NULL),
1444 _g1mm(NULL),
1445 _preserved_marks_set(true /* in_c_heap */),
1446 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1447 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1448 _humongous_reclaim_candidates(),
1449 _has_humongous_reclaim_candidates(false),
1450 _archive_allocator(NULL),
1451 _summary_bytes_used(0),
1452 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1453 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1454 _expand_heap_after_alloc_failure(true),
1455 _old_marking_cycles_started(0),
1456 _old_marking_cycles_completed(0),
1457 _in_cset_fast_test() {
1458
1459 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1460 /* are_GC_task_threads */true,
1461 /* are_ConcurrentGC_threads */false);
1462 _workers->initialize_workers();
1463 _verifier = new G1HeapVerifier(this);
1464
1465 _allocator = new G1Allocator(this);
1466
1467 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1468
1469 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1470
1471 // Override the default _filler_array_max_size so that no humongous filler
1472 // objects are created.
1473 _filler_array_max_size = _humongous_object_threshold_in_words;
1474
1475 uint n_queues = ParallelGCThreads;
1476 _task_queues = new RefToScanQueueSet(n_queues);
1477
1478 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1479
1480 for (uint i = 0; i < n_queues; i++) {
1481 RefToScanQueue* q = new RefToScanQueue();
1482 q->initialize();
1483 _task_queues->register_queue(i, q);
1484 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1485 }
1486
1487 // Initialize the G1EvacuationFailureALot counters and flags.
1488 NOT_PRODUCT(reset_evacuation_should_fail();)
1489 _gc_tracer_stw->initialize();
1490
1491 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1492 }
1493
create_aux_memory_mapper(const char * description,size_t size,size_t translation_factor)1494 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1495 size_t size,
1496 size_t translation_factor) {
1497 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1498 // Allocate a new reserved space, preferring to use large pages.
1499 ReservedSpace rs(size, preferred_page_size);
1500 G1RegionToSpaceMapper* result =
1501 G1RegionToSpaceMapper::create_mapper(rs,
1502 size,
1503 rs.alignment(),
1504 HeapRegion::GrainBytes,
1505 translation_factor,
1506 mtGC);
1507
1508 os::trace_page_sizes_for_requested_size(description,
1509 size,
1510 preferred_page_size,
1511 rs.alignment(),
1512 rs.base(),
1513 rs.size());
1514
1515 return result;
1516 }
1517
initialize_concurrent_refinement()1518 jint G1CollectedHeap::initialize_concurrent_refinement() {
1519 jint ecode = JNI_OK;
1520 _cr = G1ConcurrentRefine::create(&ecode);
1521 return ecode;
1522 }
1523
initialize_young_gen_sampling_thread()1524 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1525 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1526 if (_young_gen_sampling_thread->osthread() == NULL) {
1527 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1528 return JNI_ENOMEM;
1529 }
1530 return JNI_OK;
1531 }
1532
initialize()1533 jint G1CollectedHeap::initialize() {
1534 os::enable_vtime();
1535
1536 // Necessary to satisfy locking discipline assertions.
1537
1538 MutexLocker x(Heap_lock);
1539
1540 // While there are no constraints in the GC code that HeapWordSize
1541 // be any particular value, there are multiple other areas in the
1542 // system which believe this to be true (e.g. oop->object_size in some
1543 // cases incorrectly returns the size in wordSize units rather than
1544 // HeapWordSize).
1545 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1546
1547 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1548 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1549 size_t heap_alignment = collector_policy()->heap_alignment();
1550
1551 // Ensure that the sizes are properly aligned.
1552 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1553 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1554 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1555
1556 // Reserve the maximum.
1557
1558 // When compressed oops are enabled, the preferred heap base
1559 // is calculated by subtracting the requested size from the
1560 // 32Gb boundary and using the result as the base address for
1561 // heap reservation. If the requested size is not aligned to
1562 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1563 // into the ReservedHeapSpace constructor) then the actual
1564 // base of the reserved heap may end up differing from the
1565 // address that was requested (i.e. the preferred heap base).
1566 // If this happens then we could end up using a non-optimal
1567 // compressed oops mode.
1568
1569 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1570 heap_alignment);
1571
1572 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1573
1574 // Create the barrier set for the entire reserved region.
1575 G1CardTable* ct = new G1CardTable(reserved_region());
1576 ct->initialize();
1577 G1BarrierSet* bs = new G1BarrierSet(ct);
1578 bs->initialize();
1579 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1580 BarrierSet::set_barrier_set(bs);
1581 _card_table = ct;
1582
1583 // Create the hot card cache.
1584 _hot_card_cache = new G1HotCardCache(this);
1585
1586 // Carve out the G1 part of the heap.
1587 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1588 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1589 G1RegionToSpaceMapper* heap_storage =
1590 G1RegionToSpaceMapper::create_mapper(g1_rs,
1591 g1_rs.size(),
1592 page_size,
1593 HeapRegion::GrainBytes,
1594 1,
1595 mtJavaHeap);
1596 os::trace_page_sizes("Heap",
1597 collector_policy()->min_heap_byte_size(),
1598 max_byte_size,
1599 page_size,
1600 heap_rs.base(),
1601 heap_rs.size());
1602 heap_storage->set_mapping_changed_listener(&_listener);
1603
1604 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1605 G1RegionToSpaceMapper* bot_storage =
1606 create_aux_memory_mapper("Block Offset Table",
1607 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1608 G1BlockOffsetTable::heap_map_factor());
1609
1610 G1RegionToSpaceMapper* cardtable_storage =
1611 create_aux_memory_mapper("Card Table",
1612 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1613 G1CardTable::heap_map_factor());
1614
1615 G1RegionToSpaceMapper* card_counts_storage =
1616 create_aux_memory_mapper("Card Counts Table",
1617 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1618 G1CardCounts::heap_map_factor());
1619
1620 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1621 G1RegionToSpaceMapper* prev_bitmap_storage =
1622 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1623 G1RegionToSpaceMapper* next_bitmap_storage =
1624 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1625
1626 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1627 _card_table->initialize(cardtable_storage);
1628 // Do later initialization work for concurrent refinement.
1629 _hot_card_cache->initialize(card_counts_storage);
1630
1631 // 6843694 - ensure that the maximum region index can fit
1632 // in the remembered set structures.
1633 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1634 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1635
1636 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1637 // start within the first card.
1638 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1639 // Also create a G1 rem set.
1640 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1641 _g1_rem_set->initialize(max_capacity(), max_regions());
1642
1643 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1644 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1645 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1646 "too many cards per region");
1647
1648 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1649
1650 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1651
1652 {
1653 HeapWord* start = _hrm.reserved().start();
1654 HeapWord* end = _hrm.reserved().end();
1655 size_t granularity = HeapRegion::GrainBytes;
1656
1657 _in_cset_fast_test.initialize(start, end, granularity);
1658 _humongous_reclaim_candidates.initialize(start, end, granularity);
1659 }
1660
1661 // Create the G1ConcurrentMark data structure and thread.
1662 // (Must do this late, so that "max_regions" is defined.)
1663 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1664 if (_cm == NULL || !_cm->completed_initialization()) {
1665 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1666 return JNI_ENOMEM;
1667 }
1668 _cm_thread = _cm->cm_thread();
1669
1670 // Now expand into the initial heap size.
1671 if (!expand(init_byte_size, _workers)) {
1672 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1673 return JNI_ENOMEM;
1674 }
1675
1676 // Perform any initialization actions delegated to the policy.
1677 g1_policy()->init(this, &_collection_set);
1678
1679 G1BarrierSet::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1680 SATB_Q_FL_lock,
1681 G1SATBProcessCompletedThreshold,
1682 Shared_SATB_Q_lock);
1683
1684 jint ecode = initialize_concurrent_refinement();
1685 if (ecode != JNI_OK) {
1686 return ecode;
1687 }
1688
1689 ecode = initialize_young_gen_sampling_thread();
1690 if (ecode != JNI_OK) {
1691 return ecode;
1692 }
1693
1694 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1695 DirtyCardQ_FL_lock,
1696 (int)concurrent_refine()->yellow_zone(),
1697 (int)concurrent_refine()->red_zone(),
1698 Shared_DirtyCardQ_lock,
1699 NULL, // fl_owner
1700 true); // init_free_ids
1701
1702 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1703 DirtyCardQ_FL_lock,
1704 -1, // never trigger processing
1705 -1, // no limit on length
1706 Shared_DirtyCardQ_lock,
1707 &G1BarrierSet::dirty_card_queue_set());
1708
1709 // Here we allocate the dummy HeapRegion that is required by the
1710 // G1AllocRegion class.
1711 HeapRegion* dummy_region = _hrm.get_dummy_region();
1712
1713 // We'll re-use the same region whether the alloc region will
1714 // require BOT updates or not and, if it doesn't, then a non-young
1715 // region will complain that it cannot support allocations without
1716 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1717 dummy_region->set_eden();
1718 // Make sure it's full.
1719 dummy_region->set_top(dummy_region->end());
1720 G1AllocRegion::setup(this, dummy_region);
1721
1722 _allocator->init_mutator_alloc_region();
1723
1724 // Do create of the monitoring and management support so that
1725 // values in the heap have been properly initialized.
1726 _g1mm = new G1MonitoringSupport(this);
1727
1728 G1StringDedup::initialize();
1729
1730 _preserved_marks_set.init(ParallelGCThreads);
1731
1732 _collection_set.initialize(max_regions());
1733
1734 return JNI_OK;
1735 }
1736
initialize_serviceability()1737 void G1CollectedHeap::initialize_serviceability() {
1738 _eden_pool = new G1EdenPool(this);
1739 _survivor_pool = new G1SurvivorPool(this);
1740 _old_pool = new G1OldGenPool(this);
1741
1742 _full_gc_memory_manager.add_pool(_eden_pool);
1743 _full_gc_memory_manager.add_pool(_survivor_pool);
1744 _full_gc_memory_manager.add_pool(_old_pool);
1745
1746 _memory_manager.add_pool(_eden_pool);
1747 _memory_manager.add_pool(_survivor_pool);
1748 _memory_manager.add_pool(_old_pool, false /* always_affected_by_gc */);
1749 }
1750
stop()1751 void G1CollectedHeap::stop() {
1752 // Stop all concurrent threads. We do this to make sure these threads
1753 // do not continue to execute and access resources (e.g. logging)
1754 // that are destroyed during shutdown.
1755 _cr->stop();
1756 _young_gen_sampling_thread->stop();
1757 _cm_thread->stop();
1758 if (G1StringDedup::is_enabled()) {
1759 G1StringDedup::stop();
1760 }
1761 }
1762
safepoint_synchronize_begin()1763 void G1CollectedHeap::safepoint_synchronize_begin() {
1764 SuspendibleThreadSet::synchronize();
1765 }
1766
safepoint_synchronize_end()1767 void G1CollectedHeap::safepoint_synchronize_end() {
1768 SuspendibleThreadSet::desynchronize();
1769 }
1770
conservative_max_heap_alignment()1771 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1772 return HeapRegion::max_region_size();
1773 }
1774
post_initialize()1775 void G1CollectedHeap::post_initialize() {
1776 CollectedHeap::post_initialize();
1777 ref_processing_init();
1778 }
1779
ref_processing_init()1780 void G1CollectedHeap::ref_processing_init() {
1781 // Reference processing in G1 currently works as follows:
1782 //
1783 // * There are two reference processor instances. One is
1784 // used to record and process discovered references
1785 // during concurrent marking; the other is used to
1786 // record and process references during STW pauses
1787 // (both full and incremental).
1788 // * Both ref processors need to 'span' the entire heap as
1789 // the regions in the collection set may be dotted around.
1790 //
1791 // * For the concurrent marking ref processor:
1792 // * Reference discovery is enabled at initial marking.
1793 // * Reference discovery is disabled and the discovered
1794 // references processed etc during remarking.
1795 // * Reference discovery is MT (see below).
1796 // * Reference discovery requires a barrier (see below).
1797 // * Reference processing may or may not be MT
1798 // (depending on the value of ParallelRefProcEnabled
1799 // and ParallelGCThreads).
1800 // * A full GC disables reference discovery by the CM
1801 // ref processor and abandons any entries on it's
1802 // discovered lists.
1803 //
1804 // * For the STW processor:
1805 // * Non MT discovery is enabled at the start of a full GC.
1806 // * Processing and enqueueing during a full GC is non-MT.
1807 // * During a full GC, references are processed after marking.
1808 //
1809 // * Discovery (may or may not be MT) is enabled at the start
1810 // of an incremental evacuation pause.
1811 // * References are processed near the end of a STW evacuation pause.
1812 // * For both types of GC:
1813 // * Discovery is atomic - i.e. not concurrent.
1814 // * Reference discovery will not need a barrier.
1815
1816 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1817
1818 // Concurrent Mark ref processor
1819 _ref_processor_cm =
1820 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1821 mt_processing, // mt processing
1822 ParallelGCThreads, // degree of mt processing
1823 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1824 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1825 false, // Reference discovery is not atomic
1826 &_is_alive_closure_cm, // is alive closure
1827 true); // allow changes to number of processing threads
1828
1829 // STW ref processor
1830 _ref_processor_stw =
1831 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1832 mt_processing, // mt processing
1833 ParallelGCThreads, // degree of mt processing
1834 (ParallelGCThreads > 1), // mt discovery
1835 ParallelGCThreads, // degree of mt discovery
1836 true, // Reference discovery is atomic
1837 &_is_alive_closure_stw, // is alive closure
1838 true); // allow changes to number of processing threads
1839 }
1840
collector_policy() const1841 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1842 return _collector_policy;
1843 }
1844
soft_ref_policy()1845 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1846 return &_soft_ref_policy;
1847 }
1848
capacity() const1849 size_t G1CollectedHeap::capacity() const {
1850 return _hrm.length() * HeapRegion::GrainBytes;
1851 }
1852
unused_committed_regions_in_bytes() const1853 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1854 return _hrm.total_free_bytes();
1855 }
1856
iterate_hcc_closure(CardTableEntryClosure * cl,uint worker_i)1857 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1858 _hot_card_cache->drain(cl, worker_i);
1859 }
1860
iterate_dirty_card_closure(CardTableEntryClosure * cl,uint worker_i)1861 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1862 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1863 size_t n_completed_buffers = 0;
1864 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1865 n_completed_buffers++;
1866 }
1867 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1868 dcqs.clear_n_completed_buffers();
1869 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1870 }
1871
1872 // Computes the sum of the storage used by the various regions.
used() const1873 size_t G1CollectedHeap::used() const {
1874 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1875 if (_archive_allocator != NULL) {
1876 result += _archive_allocator->used();
1877 }
1878 return result;
1879 }
1880
used_unlocked() const1881 size_t G1CollectedHeap::used_unlocked() const {
1882 return _summary_bytes_used;
1883 }
1884
1885 class SumUsedClosure: public HeapRegionClosure {
1886 size_t _used;
1887 public:
SumUsedClosure()1888 SumUsedClosure() : _used(0) {}
do_heap_region(HeapRegion * r)1889 bool do_heap_region(HeapRegion* r) {
1890 _used += r->used();
1891 return false;
1892 }
result()1893 size_t result() { return _used; }
1894 };
1895
recalculate_used() const1896 size_t G1CollectedHeap::recalculate_used() const {
1897 double recalculate_used_start = os::elapsedTime();
1898
1899 SumUsedClosure blk;
1900 heap_region_iterate(&blk);
1901
1902 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1903 return blk.result();
1904 }
1905
is_user_requested_concurrent_full_gc(GCCause::Cause cause)1906 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1907 switch (cause) {
1908 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1909 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1910 case GCCause::_wb_conc_mark: return true;
1911 default : return false;
1912 }
1913 }
1914
should_do_concurrent_full_gc(GCCause::Cause cause)1915 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1916 switch (cause) {
1917 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1918 case GCCause::_g1_humongous_allocation: return true;
1919 default: return is_user_requested_concurrent_full_gc(cause);
1920 }
1921 }
1922
1923 #ifndef PRODUCT
allocate_dummy_regions()1924 void G1CollectedHeap::allocate_dummy_regions() {
1925 // Let's fill up most of the region
1926 size_t word_size = HeapRegion::GrainWords - 1024;
1927 // And as a result the region we'll allocate will be humongous.
1928 guarantee(is_humongous(word_size), "sanity");
1929
1930 // _filler_array_max_size is set to humongous object threshold
1931 // but temporarily change it to use CollectedHeap::fill_with_object().
1932 SizeTFlagSetting fs(_filler_array_max_size, word_size);
1933
1934 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1935 // Let's use the existing mechanism for the allocation
1936 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1937 if (dummy_obj != NULL) {
1938 MemRegion mr(dummy_obj, word_size);
1939 CollectedHeap::fill_with_object(mr);
1940 } else {
1941 // If we can't allocate once, we probably cannot allocate
1942 // again. Let's get out of the loop.
1943 break;
1944 }
1945 }
1946 }
1947 #endif // !PRODUCT
1948
increment_old_marking_cycles_started()1949 void G1CollectedHeap::increment_old_marking_cycles_started() {
1950 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1951 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1952 "Wrong marking cycle count (started: %d, completed: %d)",
1953 _old_marking_cycles_started, _old_marking_cycles_completed);
1954
1955 _old_marking_cycles_started++;
1956 }
1957
increment_old_marking_cycles_completed(bool concurrent)1958 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
1959 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
1960
1961 // We assume that if concurrent == true, then the caller is a
1962 // concurrent thread that was joined the Suspendible Thread
1963 // Set. If there's ever a cheap way to check this, we should add an
1964 // assert here.
1965
1966 // Given that this method is called at the end of a Full GC or of a
1967 // concurrent cycle, and those can be nested (i.e., a Full GC can
1968 // interrupt a concurrent cycle), the number of full collections
1969 // completed should be either one (in the case where there was no
1970 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1971 // behind the number of full collections started.
1972
1973 // This is the case for the inner caller, i.e. a Full GC.
1974 assert(concurrent ||
1975 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1976 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1977 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1978 "is inconsistent with _old_marking_cycles_completed = %u",
1979 _old_marking_cycles_started, _old_marking_cycles_completed);
1980
1981 // This is the case for the outer caller, i.e. the concurrent cycle.
1982 assert(!concurrent ||
1983 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1984 "for outer caller (concurrent cycle): "
1985 "_old_marking_cycles_started = %u "
1986 "is inconsistent with _old_marking_cycles_completed = %u",
1987 _old_marking_cycles_started, _old_marking_cycles_completed);
1988
1989 _old_marking_cycles_completed += 1;
1990
1991 // We need to clear the "in_progress" flag in the CM thread before
1992 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1993 // is set) so that if a waiter requests another System.gc() it doesn't
1994 // incorrectly see that a marking cycle is still in progress.
1995 if (concurrent) {
1996 _cm_thread->set_idle();
1997 }
1998
1999 // This notify_all() will ensure that a thread that called
2000 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2001 // and it's waiting for a full GC to finish will be woken up. It is
2002 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2003 FullGCCount_lock->notify_all();
2004 }
2005
collect(GCCause::Cause cause)2006 void G1CollectedHeap::collect(GCCause::Cause cause) {
2007 assert_heap_not_locked();
2008
2009 uint gc_count_before;
2010 uint old_marking_count_before;
2011 uint full_gc_count_before;
2012 bool retry_gc;
2013
2014 do {
2015 retry_gc = false;
2016
2017 {
2018 MutexLocker ml(Heap_lock);
2019
2020 // Read the GC count while holding the Heap_lock
2021 gc_count_before = total_collections();
2022 full_gc_count_before = total_full_collections();
2023 old_marking_count_before = _old_marking_cycles_started;
2024 }
2025
2026 if (should_do_concurrent_full_gc(cause)) {
2027 // Schedule an initial-mark evacuation pause that will start a
2028 // concurrent cycle. We're setting word_size to 0 which means that
2029 // we are not requesting a post-GC allocation.
2030 VM_G1CollectForAllocation op(0, /* word_size */
2031 gc_count_before,
2032 cause,
2033 true, /* should_initiate_conc_mark */
2034 g1_policy()->max_pause_time_ms());
2035 VMThread::execute(&op);
2036 if (!op.pause_succeeded()) {
2037 if (old_marking_count_before == _old_marking_cycles_started) {
2038 retry_gc = op.should_retry_gc();
2039 } else {
2040 // A Full GC happened while we were trying to schedule the
2041 // initial-mark GC. No point in starting a new cycle given
2042 // that the whole heap was collected anyway.
2043 }
2044
2045 if (retry_gc) {
2046 if (GCLocker::is_active_and_needs_gc()) {
2047 GCLocker::stall_until_clear();
2048 }
2049 }
2050 }
2051 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2052 // Return false to be consistent with VMOp failure due to
2053 // another collection slipping in after our gc_count but before
2054 // our request is processed. _gc_locker collections upgraded by
2055 // GCLockerInvokesConcurrent are handled above and never discarded.
2056 return;
2057 } else {
2058 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2059 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2060
2061 // Schedule a standard evacuation pause. We're setting word_size
2062 // to 0 which means that we are not requesting a post-GC allocation.
2063 VM_G1CollectForAllocation op(0, /* word_size */
2064 gc_count_before,
2065 cause,
2066 false, /* should_initiate_conc_mark */
2067 g1_policy()->max_pause_time_ms());
2068 VMThread::execute(&op);
2069 } else {
2070 // Schedule a Full GC.
2071 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2072 VMThread::execute(&op);
2073 }
2074 }
2075 } while (retry_gc);
2076 }
2077
is_in(const void * p) const2078 bool G1CollectedHeap::is_in(const void* p) const {
2079 if (_hrm.reserved().contains(p)) {
2080 // Given that we know that p is in the reserved space,
2081 // heap_region_containing() should successfully
2082 // return the containing region.
2083 HeapRegion* hr = heap_region_containing(p);
2084 return hr->is_in(p);
2085 } else {
2086 return false;
2087 }
2088 }
2089
2090 #ifdef ASSERT
is_in_exact(const void * p) const2091 bool G1CollectedHeap::is_in_exact(const void* p) const {
2092 bool contains = reserved_region().contains(p);
2093 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2094 if (contains && available) {
2095 return true;
2096 } else {
2097 return false;
2098 }
2099 }
2100 #endif
2101
2102 // Iteration functions.
2103
2104 // Iterates an ObjectClosure over all objects within a HeapRegion.
2105
2106 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2107 ObjectClosure* _cl;
2108 public:
IterateObjectClosureRegionClosure(ObjectClosure * cl)2109 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
do_heap_region(HeapRegion * r)2110 bool do_heap_region(HeapRegion* r) {
2111 if (!r->is_continues_humongous()) {
2112 r->object_iterate(_cl);
2113 }
2114 return false;
2115 }
2116 };
2117
object_iterate(ObjectClosure * cl)2118 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2119 IterateObjectClosureRegionClosure blk(cl);
2120 heap_region_iterate(&blk);
2121 }
2122
keep_alive(oop obj)2123 void G1CollectedHeap::keep_alive(oop obj) {
2124 G1BarrierSet::enqueue(obj);
2125 }
2126
heap_region_iterate(HeapRegionClosure * cl) const2127 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2128 _hrm.iterate(cl);
2129 }
2130
heap_region_par_iterate_from_worker_offset(HeapRegionClosure * cl,HeapRegionClaimer * hrclaimer,uint worker_id) const2131 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2132 HeapRegionClaimer *hrclaimer,
2133 uint worker_id) const {
2134 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2135 }
2136
heap_region_par_iterate_from_start(HeapRegionClosure * cl,HeapRegionClaimer * hrclaimer) const2137 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2138 HeapRegionClaimer *hrclaimer) const {
2139 _hrm.par_iterate(cl, hrclaimer, 0);
2140 }
2141
collection_set_iterate(HeapRegionClosure * cl)2142 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2143 _collection_set.iterate(cl);
2144 }
2145
collection_set_iterate_from(HeapRegionClosure * cl,uint worker_id)2146 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2147 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2148 }
2149
block_start(const void * addr) const2150 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2151 HeapRegion* hr = heap_region_containing(addr);
2152 return hr->block_start(addr);
2153 }
2154
block_size(const HeapWord * addr) const2155 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2156 HeapRegion* hr = heap_region_containing(addr);
2157 return hr->block_size(addr);
2158 }
2159
block_is_obj(const HeapWord * addr) const2160 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2161 HeapRegion* hr = heap_region_containing(addr);
2162 return hr->block_is_obj(addr);
2163 }
2164
supports_tlab_allocation() const2165 bool G1CollectedHeap::supports_tlab_allocation() const {
2166 return true;
2167 }
2168
tlab_capacity(Thread * ignored) const2169 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2170 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2171 }
2172
tlab_used(Thread * ignored) const2173 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2174 return _eden.length() * HeapRegion::GrainBytes;
2175 }
2176
2177 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2178 // must be equal to the humongous object limit.
max_tlab_size() const2179 size_t G1CollectedHeap::max_tlab_size() const {
2180 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2181 }
2182
unsafe_max_tlab_alloc(Thread * ignored) const2183 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2184 return _allocator->unsafe_max_tlab_alloc();
2185 }
2186
max_capacity() const2187 size_t G1CollectedHeap::max_capacity() const {
2188 return _hrm.reserved().byte_size();
2189 }
2190
millis_since_last_gc()2191 jlong G1CollectedHeap::millis_since_last_gc() {
2192 // See the notes in GenCollectedHeap::millis_since_last_gc()
2193 // for more information about the implementation.
2194 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2195 _g1_policy->collection_pause_end_millis();
2196 if (ret_val < 0) {
2197 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2198 ". returning zero instead.", ret_val);
2199 return 0;
2200 }
2201 return ret_val;
2202 }
2203
deduplicate_string(oop str)2204 void G1CollectedHeap::deduplicate_string(oop str) {
2205 assert(java_lang_String::is_instance(str), "invariant");
2206
2207 if (G1StringDedup::is_enabled()) {
2208 G1StringDedup::deduplicate(str);
2209 }
2210 }
2211
prepare_for_verify()2212 void G1CollectedHeap::prepare_for_verify() {
2213 _verifier->prepare_for_verify();
2214 }
2215
verify(VerifyOption vo)2216 void G1CollectedHeap::verify(VerifyOption vo) {
2217 _verifier->verify(vo);
2218 }
2219
supports_concurrent_phase_control() const2220 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2221 return true;
2222 }
2223
concurrent_phases() const2224 const char* const* G1CollectedHeap::concurrent_phases() const {
2225 return _cm_thread->concurrent_phases();
2226 }
2227
request_concurrent_phase(const char * phase)2228 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2229 return _cm_thread->request_concurrent_phase(phase);
2230 }
2231
2232 class PrintRegionClosure: public HeapRegionClosure {
2233 outputStream* _st;
2234 public:
PrintRegionClosure(outputStream * st)2235 PrintRegionClosure(outputStream* st) : _st(st) {}
do_heap_region(HeapRegion * r)2236 bool do_heap_region(HeapRegion* r) {
2237 r->print_on(_st);
2238 return false;
2239 }
2240 };
2241
is_obj_dead_cond(const oop obj,const HeapRegion * hr,const VerifyOption vo) const2242 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2243 const HeapRegion* hr,
2244 const VerifyOption vo) const {
2245 switch (vo) {
2246 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2247 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2248 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2249 default: ShouldNotReachHere();
2250 }
2251 return false; // keep some compilers happy
2252 }
2253
is_obj_dead_cond(const oop obj,const VerifyOption vo) const2254 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2255 const VerifyOption vo) const {
2256 switch (vo) {
2257 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2258 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2259 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2260 default: ShouldNotReachHere();
2261 }
2262 return false; // keep some compilers happy
2263 }
2264
print_heap_regions() const2265 void G1CollectedHeap::print_heap_regions() const {
2266 LogTarget(Trace, gc, heap, region) lt;
2267 if (lt.is_enabled()) {
2268 LogStream ls(lt);
2269 print_regions_on(&ls);
2270 }
2271 }
2272
print_on(outputStream * st) const2273 void G1CollectedHeap::print_on(outputStream* st) const {
2274 st->print(" %-20s", "garbage-first heap");
2275 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2276 capacity()/K, used_unlocked()/K);
2277 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2278 p2i(_hrm.reserved().start()),
2279 p2i(_hrm.reserved().end()));
2280 st->cr();
2281 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2282 uint young_regions = young_regions_count();
2283 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2284 (size_t) young_regions * HeapRegion::GrainBytes / K);
2285 uint survivor_regions = survivor_regions_count();
2286 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2287 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2288 st->cr();
2289 MetaspaceUtils::print_on(st);
2290 }
2291
print_regions_on(outputStream * st) const2292 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2293 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2294 "HS=humongous(starts), HC=humongous(continues), "
2295 "CS=collection set, F=free, A=archive, "
2296 "TAMS=top-at-mark-start (previous, next)");
2297 PrintRegionClosure blk(st);
2298 heap_region_iterate(&blk);
2299 }
2300
print_extended_on(outputStream * st) const2301 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2302 print_on(st);
2303
2304 // Print the per-region information.
2305 print_regions_on(st);
2306 }
2307
print_on_error(outputStream * st) const2308 void G1CollectedHeap::print_on_error(outputStream* st) const {
2309 this->CollectedHeap::print_on_error(st);
2310
2311 if (_cm != NULL) {
2312 st->cr();
2313 _cm->print_on_error(st);
2314 }
2315 }
2316
print_gc_threads_on(outputStream * st) const2317 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2318 workers()->print_worker_threads_on(st);
2319 _cm_thread->print_on(st);
2320 st->cr();
2321 _cm->print_worker_threads_on(st);
2322 _cr->print_threads_on(st);
2323 _young_gen_sampling_thread->print_on(st);
2324 if (G1StringDedup::is_enabled()) {
2325 G1StringDedup::print_worker_threads_on(st);
2326 }
2327 }
2328
gc_threads_do(ThreadClosure * tc) const2329 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2330 workers()->threads_do(tc);
2331 tc->do_thread(_cm_thread);
2332 _cm->threads_do(tc);
2333 _cr->threads_do(tc);
2334 tc->do_thread(_young_gen_sampling_thread);
2335 if (G1StringDedup::is_enabled()) {
2336 G1StringDedup::threads_do(tc);
2337 }
2338 }
2339
print_tracing_info() const2340 void G1CollectedHeap::print_tracing_info() const {
2341 g1_rem_set()->print_summary_info();
2342 concurrent_mark()->print_summary_info();
2343 }
2344
2345 #ifndef PRODUCT
2346 // Helpful for debugging RSet issues.
2347
2348 class PrintRSetsClosure : public HeapRegionClosure {
2349 private:
2350 const char* _msg;
2351 size_t _occupied_sum;
2352
2353 public:
do_heap_region(HeapRegion * r)2354 bool do_heap_region(HeapRegion* r) {
2355 HeapRegionRemSet* hrrs = r->rem_set();
2356 size_t occupied = hrrs->occupied();
2357 _occupied_sum += occupied;
2358
2359 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2360 if (occupied == 0) {
2361 tty->print_cr(" RSet is empty");
2362 } else {
2363 hrrs->print();
2364 }
2365 tty->print_cr("----------");
2366 return false;
2367 }
2368
PrintRSetsClosure(const char * msg)2369 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2370 tty->cr();
2371 tty->print_cr("========================================");
2372 tty->print_cr("%s", msg);
2373 tty->cr();
2374 }
2375
~PrintRSetsClosure()2376 ~PrintRSetsClosure() {
2377 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2378 tty->print_cr("========================================");
2379 tty->cr();
2380 }
2381 };
2382
print_cset_rsets()2383 void G1CollectedHeap::print_cset_rsets() {
2384 PrintRSetsClosure cl("Printing CSet RSets");
2385 collection_set_iterate(&cl);
2386 }
2387
print_all_rsets()2388 void G1CollectedHeap::print_all_rsets() {
2389 PrintRSetsClosure cl("Printing All RSets");;
2390 heap_region_iterate(&cl);
2391 }
2392 #endif // PRODUCT
2393
create_g1_heap_summary()2394 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2395
2396 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2397 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2398 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2399
2400 size_t eden_capacity_bytes =
2401 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2402
2403 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2404 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2405 eden_capacity_bytes, survivor_used_bytes, num_regions());
2406 }
2407
create_g1_evac_summary(G1EvacStats * stats)2408 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2409 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2410 stats->unused(), stats->used(), stats->region_end_waste(),
2411 stats->regions_filled(), stats->direct_allocated(),
2412 stats->failure_used(), stats->failure_waste());
2413 }
2414
trace_heap(GCWhen::Type when,const GCTracer * gc_tracer)2415 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2416 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2417 gc_tracer->report_gc_heap_summary(when, heap_summary);
2418
2419 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2420 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2421 }
2422
heap()2423 G1CollectedHeap* G1CollectedHeap::heap() {
2424 CollectedHeap* heap = Universe::heap();
2425 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2426 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2427 return (G1CollectedHeap*)heap;
2428 }
2429
gc_prologue(bool full)2430 void G1CollectedHeap::gc_prologue(bool full) {
2431 // always_do_update_barrier = false;
2432 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2433
2434 // This summary needs to be printed before incrementing total collections.
2435 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2436
2437 // Update common counters.
2438 increment_total_collections(full /* full gc */);
2439 if (full) {
2440 increment_old_marking_cycles_started();
2441 }
2442
2443 // Fill TLAB's and such
2444 double start = os::elapsedTime();
2445 accumulate_statistics_all_tlabs();
2446 ensure_parsability(true);
2447 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2448 }
2449
gc_epilogue(bool full)2450 void G1CollectedHeap::gc_epilogue(bool full) {
2451 // Update common counters.
2452 if (full) {
2453 // Update the number of full collections that have been completed.
2454 increment_old_marking_cycles_completed(false /* concurrent */);
2455 }
2456
2457 // We are at the end of the GC. Total collections has already been increased.
2458 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2459
2460 // FIXME: what is this about?
2461 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2462 // is set.
2463 #if COMPILER2_OR_JVMCI
2464 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2465 #endif
2466 // always_do_update_barrier = true;
2467
2468 double start = os::elapsedTime();
2469 resize_all_tlabs();
2470 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2471
2472 MemoryService::track_memory_usage();
2473 // We have just completed a GC. Update the soft reference
2474 // policy with the new heap occupancy
2475 Universe::update_heap_info_at_gc();
2476 }
2477
do_collection_pause(size_t word_size,uint gc_count_before,bool * succeeded,GCCause::Cause gc_cause)2478 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2479 uint gc_count_before,
2480 bool* succeeded,
2481 GCCause::Cause gc_cause) {
2482 assert_heap_not_locked_and_not_at_safepoint();
2483 VM_G1CollectForAllocation op(word_size,
2484 gc_count_before,
2485 gc_cause,
2486 false, /* should_initiate_conc_mark */
2487 g1_policy()->max_pause_time_ms());
2488 VMThread::execute(&op);
2489
2490 HeapWord* result = op.result();
2491 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2492 assert(result == NULL || ret_succeeded,
2493 "the result should be NULL if the VM did not succeed");
2494 *succeeded = ret_succeeded;
2495
2496 assert_heap_not_locked();
2497 return result;
2498 }
2499
do_concurrent_mark()2500 void G1CollectedHeap::do_concurrent_mark() {
2501 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2502 if (!_cm_thread->in_progress()) {
2503 _cm_thread->set_started();
2504 CGC_lock->notify();
2505 }
2506 }
2507
pending_card_num()2508 size_t G1CollectedHeap::pending_card_num() {
2509 size_t extra_cards = 0;
2510 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2511 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2512 extra_cards += dcq.size();
2513 }
2514 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2515 size_t buffer_size = dcqs.buffer_size();
2516 size_t buffer_num = dcqs.completed_buffers_num();
2517
2518 return buffer_size * buffer_num + extra_cards;
2519 }
2520
is_potential_eager_reclaim_candidate(HeapRegion * r) const2521 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2522 // We don't nominate objects with many remembered set entries, on
2523 // the assumption that such objects are likely still live.
2524 HeapRegionRemSet* rem_set = r->rem_set();
2525
2526 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2527 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2528 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2529 }
2530
2531 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2532 private:
2533 size_t _total_humongous;
2534 size_t _candidate_humongous;
2535
2536 DirtyCardQueue _dcq;
2537
humongous_region_is_candidate(G1CollectedHeap * g1h,HeapRegion * region) const2538 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2539 assert(region->is_starts_humongous(), "Must start a humongous object");
2540
2541 oop obj = oop(region->bottom());
2542
2543 // Dead objects cannot be eager reclaim candidates. Due to class
2544 // unloading it is unsafe to query their classes so we return early.
2545 if (g1h->is_obj_dead(obj, region)) {
2546 return false;
2547 }
2548
2549 // If we do not have a complete remembered set for the region, then we can
2550 // not be sure that we have all references to it.
2551 if (!region->rem_set()->is_complete()) {
2552 return false;
2553 }
2554 // Candidate selection must satisfy the following constraints
2555 // while concurrent marking is in progress:
2556 //
2557 // * In order to maintain SATB invariants, an object must not be
2558 // reclaimed if it was allocated before the start of marking and
2559 // has not had its references scanned. Such an object must have
2560 // its references (including type metadata) scanned to ensure no
2561 // live objects are missed by the marking process. Objects
2562 // allocated after the start of concurrent marking don't need to
2563 // be scanned.
2564 //
2565 // * An object must not be reclaimed if it is on the concurrent
2566 // mark stack. Objects allocated after the start of concurrent
2567 // marking are never pushed on the mark stack.
2568 //
2569 // Nominating only objects allocated after the start of concurrent
2570 // marking is sufficient to meet both constraints. This may miss
2571 // some objects that satisfy the constraints, but the marking data
2572 // structures don't support efficiently performing the needed
2573 // additional tests or scrubbing of the mark stack.
2574 //
2575 // However, we presently only nominate is_typeArray() objects.
2576 // A humongous object containing references induces remembered
2577 // set entries on other regions. In order to reclaim such an
2578 // object, those remembered sets would need to be cleaned up.
2579 //
2580 // We also treat is_typeArray() objects specially, allowing them
2581 // to be reclaimed even if allocated before the start of
2582 // concurrent mark. For this we rely on mark stack insertion to
2583 // exclude is_typeArray() objects, preventing reclaiming an object
2584 // that is in the mark stack. We also rely on the metadata for
2585 // such objects to be built-in and so ensured to be kept live.
2586 // Frequent allocation and drop of large binary blobs is an
2587 // important use case for eager reclaim, and this special handling
2588 // may reduce needed headroom.
2589
2590 return obj->is_typeArray() &&
2591 g1h->is_potential_eager_reclaim_candidate(region);
2592 }
2593
2594 public:
RegisterHumongousWithInCSetFastTestClosure()2595 RegisterHumongousWithInCSetFastTestClosure()
2596 : _total_humongous(0),
2597 _candidate_humongous(0),
2598 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2599 }
2600
do_heap_region(HeapRegion * r)2601 virtual bool do_heap_region(HeapRegion* r) {
2602 if (!r->is_starts_humongous()) {
2603 return false;
2604 }
2605 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2606
2607 bool is_candidate = humongous_region_is_candidate(g1h, r);
2608 uint rindex = r->hrm_index();
2609 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2610 if (is_candidate) {
2611 _candidate_humongous++;
2612 g1h->register_humongous_region_with_cset(rindex);
2613 // Is_candidate already filters out humongous object with large remembered sets.
2614 // If we have a humongous object with a few remembered sets, we simply flush these
2615 // remembered set entries into the DCQS. That will result in automatic
2616 // re-evaluation of their remembered set entries during the following evacuation
2617 // phase.
2618 if (!r->rem_set()->is_empty()) {
2619 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2620 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2621 G1CardTable* ct = g1h->card_table();
2622 HeapRegionRemSetIterator hrrs(r->rem_set());
2623 size_t card_index;
2624 while (hrrs.has_next(card_index)) {
2625 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2626 // The remembered set might contain references to already freed
2627 // regions. Filter out such entries to avoid failing card table
2628 // verification.
2629 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2630 if (*card_ptr != G1CardTable::dirty_card_val()) {
2631 *card_ptr = G1CardTable::dirty_card_val();
2632 _dcq.enqueue(card_ptr);
2633 }
2634 }
2635 }
2636 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2637 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2638 hrrs.n_yielded(), r->rem_set()->occupied());
2639 // We should only clear the card based remembered set here as we will not
2640 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2641 // (and probably never) we do not enter this path if there are other kind of
2642 // remembered sets for this region.
2643 r->rem_set()->clear_locked(true /* only_cardset */);
2644 // Clear_locked() above sets the state to Empty. However we want to continue
2645 // collecting remembered set entries for humongous regions that were not
2646 // reclaimed.
2647 r->rem_set()->set_state_complete();
2648 }
2649 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2650 }
2651 _total_humongous++;
2652
2653 return false;
2654 }
2655
total_humongous() const2656 size_t total_humongous() const { return _total_humongous; }
candidate_humongous() const2657 size_t candidate_humongous() const { return _candidate_humongous; }
2658
flush_rem_set_entries()2659 void flush_rem_set_entries() { _dcq.flush(); }
2660 };
2661
register_humongous_regions_with_cset()2662 void G1CollectedHeap::register_humongous_regions_with_cset() {
2663 if (!G1EagerReclaimHumongousObjects) {
2664 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2665 return;
2666 }
2667 double time = os::elapsed_counter();
2668
2669 // Collect reclaim candidate information and register candidates with cset.
2670 RegisterHumongousWithInCSetFastTestClosure cl;
2671 heap_region_iterate(&cl);
2672
2673 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2674 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2675 cl.total_humongous(),
2676 cl.candidate_humongous());
2677 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2678
2679 // Finally flush all remembered set entries to re-check into the global DCQS.
2680 cl.flush_rem_set_entries();
2681 }
2682
2683 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2684 public:
do_heap_region(HeapRegion * hr)2685 bool do_heap_region(HeapRegion* hr) {
2686 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2687 hr->verify_rem_set();
2688 }
2689 return false;
2690 }
2691 };
2692
num_task_queues() const2693 uint G1CollectedHeap::num_task_queues() const {
2694 return _task_queues->size();
2695 }
2696
2697 #if TASKQUEUE_STATS
print_taskqueue_stats_hdr(outputStream * const st)2698 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2699 st->print_raw_cr("GC Task Stats");
2700 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2701 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2702 }
2703
print_taskqueue_stats() const2704 void G1CollectedHeap::print_taskqueue_stats() const {
2705 if (!log_is_enabled(Trace, gc, task, stats)) {
2706 return;
2707 }
2708 Log(gc, task, stats) log;
2709 ResourceMark rm;
2710 LogStream ls(log.trace());
2711 outputStream* st = &ls;
2712
2713 print_taskqueue_stats_hdr(st);
2714
2715 TaskQueueStats totals;
2716 const uint n = num_task_queues();
2717 for (uint i = 0; i < n; ++i) {
2718 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2719 totals += task_queue(i)->stats;
2720 }
2721 st->print_raw("tot "); totals.print(st); st->cr();
2722
2723 DEBUG_ONLY(totals.verify());
2724 }
2725
reset_taskqueue_stats()2726 void G1CollectedHeap::reset_taskqueue_stats() {
2727 const uint n = num_task_queues();
2728 for (uint i = 0; i < n; ++i) {
2729 task_queue(i)->stats.reset();
2730 }
2731 }
2732 #endif // TASKQUEUE_STATS
2733
wait_for_root_region_scanning()2734 void G1CollectedHeap::wait_for_root_region_scanning() {
2735 double scan_wait_start = os::elapsedTime();
2736 // We have to wait until the CM threads finish scanning the
2737 // root regions as it's the only way to ensure that all the
2738 // objects on them have been correctly scanned before we start
2739 // moving them during the GC.
2740 bool waited = _cm->root_regions()->wait_until_scan_finished();
2741 double wait_time_ms = 0.0;
2742 if (waited) {
2743 double scan_wait_end = os::elapsedTime();
2744 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2745 }
2746 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2747 }
2748
2749 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2750 private:
2751 G1HRPrinter* _hr_printer;
2752 public:
G1PrintCollectionSetClosure(G1HRPrinter * hr_printer)2753 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2754
do_heap_region(HeapRegion * r)2755 virtual bool do_heap_region(HeapRegion* r) {
2756 _hr_printer->cset(r);
2757 return false;
2758 }
2759 };
2760
start_new_collection_set()2761 void G1CollectedHeap::start_new_collection_set() {
2762 collection_set()->start_incremental_building();
2763
2764 clear_cset_fast_test();
2765
2766 guarantee(_eden.length() == 0, "eden should have been cleared");
2767 g1_policy()->transfer_survivors_to_cset(survivor());
2768 }
2769
2770 bool
do_collection_pause_at_safepoint(double target_pause_time_ms)2771 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2772 assert_at_safepoint_on_vm_thread();
2773 guarantee(!is_gc_active(), "collection is not reentrant");
2774
2775 if (GCLocker::check_active_before_gc()) {
2776 return false;
2777 }
2778
2779 _gc_timer_stw->register_gc_start();
2780
2781 GCIdMark gc_id_mark;
2782 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2783
2784 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2785 ResourceMark rm;
2786
2787 g1_policy()->note_gc_start();
2788
2789 wait_for_root_region_scanning();
2790
2791 print_heap_before_gc();
2792 print_heap_regions();
2793 trace_heap_before_gc(_gc_tracer_stw);
2794
2795 _verifier->verify_region_sets_optional();
2796 _verifier->verify_dirty_young_regions();
2797
2798 // We should not be doing initial mark unless the conc mark thread is running
2799 if (!_cm_thread->should_terminate()) {
2800 // This call will decide whether this pause is an initial-mark
2801 // pause. If it is, in_initial_mark_gc() will return true
2802 // for the duration of this pause.
2803 g1_policy()->decide_on_conc_mark_initiation();
2804 }
2805
2806 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2807 assert(!collector_state()->in_initial_mark_gc() ||
2808 collector_state()->in_young_only_phase(), "sanity");
2809
2810 // We also do not allow mixed GCs during marking.
2811 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2812
2813 // Record whether this pause is an initial mark. When the current
2814 // thread has completed its logging output and it's safe to signal
2815 // the CM thread, the flag's value in the policy has been reset.
2816 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2817
2818 // Inner scope for scope based logging, timers, and stats collection
2819 {
2820 EvacuationInfo evacuation_info;
2821
2822 if (collector_state()->in_initial_mark_gc()) {
2823 // We are about to start a marking cycle, so we increment the
2824 // full collection counter.
2825 increment_old_marking_cycles_started();
2826 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2827 }
2828
2829 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2830
2831 GCTraceCPUTime tcpu;
2832
2833 G1HeapVerifier::G1VerifyType verify_type;
2834 FormatBuffer<> gc_string("Pause Young ");
2835 if (collector_state()->in_initial_mark_gc()) {
2836 gc_string.append("(Concurrent Start)");
2837 verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2838 } else if (collector_state()->in_young_only_phase()) {
2839 if (collector_state()->in_young_gc_before_mixed()) {
2840 gc_string.append("(Prepare Mixed)");
2841 } else {
2842 gc_string.append("(Normal)");
2843 }
2844 verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2845 } else {
2846 gc_string.append("(Mixed)");
2847 verify_type = G1HeapVerifier::G1VerifyMixed;
2848 }
2849 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2850
2851 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2852 workers()->active_workers(),
2853 Threads::number_of_non_daemon_threads());
2854 active_workers = workers()->update_active_workers(active_workers);
2855 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2856
2857 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2858 TraceMemoryManagerStats tms(&_memory_manager, gc_cause(),
2859 collector_state()->yc_type() == Mixed /* allMemoryPoolsAffected */);
2860
2861 G1HeapTransition heap_transition(this);
2862 size_t heap_used_bytes_before_gc = used();
2863
2864 // Don't dynamically change the number of GC threads this early. A value of
2865 // 0 is used to indicate serial work. When parallel work is done,
2866 // it will be set.
2867
2868 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2869 IsGCActiveMark x;
2870
2871 gc_prologue(false);
2872
2873 if (VerifyRememberedSets) {
2874 log_info(gc, verify)("[Verifying RemSets before GC]");
2875 VerifyRegionRemSetClosure v_cl;
2876 heap_region_iterate(&v_cl);
2877 }
2878
2879 _verifier->verify_before_gc(verify_type);
2880
2881 _verifier->check_bitmaps("GC Start");
2882
2883 #if COMPILER2_OR_JVMCI
2884 DerivedPointerTable::clear();
2885 #endif
2886
2887 // Please see comment in g1CollectedHeap.hpp and
2888 // G1CollectedHeap::ref_processing_init() to see how
2889 // reference processing currently works in G1.
2890
2891 // Enable discovery in the STW reference processor
2892 _ref_processor_stw->enable_discovery();
2893
2894 {
2895 // We want to temporarily turn off discovery by the
2896 // CM ref processor, if necessary, and turn it back on
2897 // on again later if we do. Using a scoped
2898 // NoRefDiscovery object will do this.
2899 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2900
2901 // Forget the current alloc region (we might even choose it to be part
2902 // of the collection set!).
2903 _allocator->release_mutator_alloc_region();
2904
2905 // This timing is only used by the ergonomics to handle our pause target.
2906 // It is unclear why this should not include the full pause. We will
2907 // investigate this in CR 7178365.
2908 //
2909 // Preserving the old comment here if that helps the investigation:
2910 //
2911 // The elapsed time induced by the start time below deliberately elides
2912 // the possible verification above.
2913 double sample_start_time_sec = os::elapsedTime();
2914
2915 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2916
2917 if (collector_state()->in_initial_mark_gc()) {
2918 concurrent_mark()->pre_initial_mark();
2919 }
2920
2921 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2922
2923 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2924
2925 // Make sure the remembered sets are up to date. This needs to be
2926 // done before register_humongous_regions_with_cset(), because the
2927 // remembered sets are used there to choose eager reclaim candidates.
2928 // If the remembered sets are not up to date we might miss some
2929 // entries that need to be handled.
2930 g1_rem_set()->cleanupHRRS();
2931
2932 register_humongous_regions_with_cset();
2933
2934 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2935
2936 // We call this after finalize_cset() to
2937 // ensure that the CSet has been finalized.
2938 _cm->verify_no_cset_oops();
2939
2940 if (_hr_printer.is_active()) {
2941 G1PrintCollectionSetClosure cl(&_hr_printer);
2942 _collection_set.iterate(&cl);
2943 }
2944
2945 // Initialize the GC alloc regions.
2946 _allocator->init_gc_alloc_regions(evacuation_info);
2947
2948 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
2949 pre_evacuate_collection_set();
2950
2951 // Actually do the work...
2952 evacuate_collection_set(&per_thread_states);
2953
2954 post_evacuate_collection_set(evacuation_info, &per_thread_states);
2955
2956 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
2957 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
2958
2959 eagerly_reclaim_humongous_regions();
2960
2961 record_obj_copy_mem_stats();
2962 _survivor_evac_stats.adjust_desired_plab_sz();
2963 _old_evac_stats.adjust_desired_plab_sz();
2964
2965 double start = os::elapsedTime();
2966 start_new_collection_set();
2967 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2968
2969 if (evacuation_failed()) {
2970 set_used(recalculate_used());
2971 if (_archive_allocator != NULL) {
2972 _archive_allocator->clear_used();
2973 }
2974 for (uint i = 0; i < ParallelGCThreads; i++) {
2975 if (_evacuation_failed_info_array[i].has_failed()) {
2976 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
2977 }
2978 }
2979 } else {
2980 // The "used" of the the collection set have already been subtracted
2981 // when they were freed. Add in the bytes evacuated.
2982 increase_used(g1_policy()->bytes_copied_during_gc());
2983 }
2984
2985 if (collector_state()->in_initial_mark_gc()) {
2986 // We have to do this before we notify the CM threads that
2987 // they can start working to make sure that all the
2988 // appropriate initialization is done on the CM object.
2989 concurrent_mark()->post_initial_mark();
2990 // Note that we don't actually trigger the CM thread at
2991 // this point. We do that later when we're sure that
2992 // the current thread has completed its logging output.
2993 }
2994
2995 allocate_dummy_regions();
2996
2997 _allocator->init_mutator_alloc_region();
2998
2999 {
3000 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3001 if (expand_bytes > 0) {
3002 size_t bytes_before = capacity();
3003 // No need for an ergo logging here,
3004 // expansion_amount() does this when it returns a value > 0.
3005 double expand_ms = 0.0;
3006 if (!expand(expand_bytes, _workers, &expand_ms)) {
3007 // We failed to expand the heap. Cannot do anything about it.
3008 }
3009 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3010 }
3011 }
3012
3013 // We redo the verification but now wrt to the new CSet which
3014 // has just got initialized after the previous CSet was freed.
3015 _cm->verify_no_cset_oops();
3016
3017 // This timing is only used by the ergonomics to handle our pause target.
3018 // It is unclear why this should not include the full pause. We will
3019 // investigate this in CR 7178365.
3020 double sample_end_time_sec = os::elapsedTime();
3021 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3022 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3023 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3024
3025 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3026 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3027
3028 if (VerifyRememberedSets) {
3029 log_info(gc, verify)("[Verifying RemSets after GC]");
3030 VerifyRegionRemSetClosure v_cl;
3031 heap_region_iterate(&v_cl);
3032 }
3033
3034 _verifier->verify_after_gc(verify_type);
3035 _verifier->check_bitmaps("GC End");
3036
3037 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3038 _ref_processor_stw->verify_no_references_recorded();
3039
3040 // CM reference discovery will be re-enabled if necessary.
3041 }
3042
3043 #ifdef TRACESPINNING
3044 ParallelTaskTerminator::print_termination_counts();
3045 #endif
3046
3047 gc_epilogue(false);
3048 }
3049
3050 // Print the remainder of the GC log output.
3051 if (evacuation_failed()) {
3052 log_info(gc)("To-space exhausted");
3053 }
3054
3055 g1_policy()->print_phases();
3056 heap_transition.print();
3057
3058 // It is not yet to safe to tell the concurrent mark to
3059 // start as we have some optional output below. We don't want the
3060 // output from the concurrent mark thread interfering with this
3061 // logging output either.
3062
3063 _hrm.verify_optional();
3064 _verifier->verify_region_sets_optional();
3065
3066 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3067 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3068
3069 print_heap_after_gc();
3070 print_heap_regions();
3071 trace_heap_after_gc(_gc_tracer_stw);
3072
3073 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3074 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3075 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3076 // before any GC notifications are raised.
3077 g1mm()->update_sizes();
3078
3079 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3080 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3081 _gc_timer_stw->register_gc_end();
3082 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3083 }
3084 // It should now be safe to tell the concurrent mark thread to start
3085 // without its logging output interfering with the logging output
3086 // that came from the pause.
3087
3088 if (should_start_conc_mark) {
3089 // CAUTION: after the doConcurrentMark() call below,
3090 // the concurrent marking thread(s) could be running
3091 // concurrently with us. Make sure that anything after
3092 // this point does not assume that we are the only GC thread
3093 // running. Note: of course, the actual marking work will
3094 // not start until the safepoint itself is released in
3095 // SuspendibleThreadSet::desynchronize().
3096 do_concurrent_mark();
3097 }
3098
3099 return true;
3100 }
3101
remove_self_forwarding_pointers()3102 void G1CollectedHeap::remove_self_forwarding_pointers() {
3103 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3104 workers()->run_task(&rsfp_task);
3105 }
3106
restore_after_evac_failure()3107 void G1CollectedHeap::restore_after_evac_failure() {
3108 double remove_self_forwards_start = os::elapsedTime();
3109
3110 remove_self_forwarding_pointers();
3111 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3112 _preserved_marks_set.restore(&task_executor);
3113
3114 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3115 }
3116
preserve_mark_during_evac_failure(uint worker_id,oop obj,markOop m)3117 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3118 if (!_evacuation_failed) {
3119 _evacuation_failed = true;
3120 }
3121
3122 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3123 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3124 }
3125
offer_termination()3126 bool G1ParEvacuateFollowersClosure::offer_termination() {
3127 G1ParScanThreadState* const pss = par_scan_state();
3128 start_term_time();
3129 const bool res = terminator()->offer_termination();
3130 end_term_time();
3131 return res;
3132 }
3133
do_void()3134 void G1ParEvacuateFollowersClosure::do_void() {
3135 G1ParScanThreadState* const pss = par_scan_state();
3136 pss->trim_queue();
3137 do {
3138 pss->steal_and_trim_queue(queues());
3139 } while (!offer_termination());
3140 }
3141
3142 class G1ParTask : public AbstractGangTask {
3143 protected:
3144 G1CollectedHeap* _g1h;
3145 G1ParScanThreadStateSet* _pss;
3146 RefToScanQueueSet* _queues;
3147 G1RootProcessor* _root_processor;
3148 ParallelTaskTerminator _terminator;
3149 uint _n_workers;
3150
3151 public:
G1ParTask(G1CollectedHeap * g1h,G1ParScanThreadStateSet * per_thread_states,RefToScanQueueSet * task_queues,G1RootProcessor * root_processor,uint n_workers)3152 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3153 : AbstractGangTask("G1 collection"),
3154 _g1h(g1h),
3155 _pss(per_thread_states),
3156 _queues(task_queues),
3157 _root_processor(root_processor),
3158 _terminator(n_workers, _queues),
3159 _n_workers(n_workers)
3160 {}
3161
work(uint worker_id)3162 void work(uint worker_id) {
3163 if (worker_id >= _n_workers) return; // no work needed this round
3164
3165 double start_sec = os::elapsedTime();
3166 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3167
3168 {
3169 ResourceMark rm;
3170 HandleMark hm;
3171
3172 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3173
3174 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3175 pss->set_ref_discoverer(rp);
3176
3177 double start_strong_roots_sec = os::elapsedTime();
3178
3179 _root_processor->evacuate_roots(pss, worker_id);
3180
3181 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3182 // treating the nmethods visited to act as roots for concurrent marking.
3183 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3184 // objects copied by the current evacuation.
3185 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3186
3187 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3188
3189 double term_sec = 0.0;
3190 size_t evac_term_attempts = 0;
3191 {
3192 double start = os::elapsedTime();
3193 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3194 evac.do_void();
3195
3196 evac_term_attempts = evac.term_attempts();
3197 term_sec = evac.term_time();
3198 double elapsed_sec = os::elapsedTime() - start;
3199
3200 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3201 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3202 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3203 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3204 }
3205
3206 assert(pss->queue_is_empty(), "should be empty");
3207
3208 if (log_is_enabled(Debug, gc, task, stats)) {
3209 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3210 size_t lab_waste;
3211 size_t lab_undo_waste;
3212 pss->waste(lab_waste, lab_undo_waste);
3213 _g1h->print_termination_stats(worker_id,
3214 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3215 strong_roots_sec * 1000.0, /* strong roots time */
3216 term_sec * 1000.0, /* evac term time */
3217 evac_term_attempts, /* evac term attempts */
3218 lab_waste, /* alloc buffer waste */
3219 lab_undo_waste /* undo waste */
3220 );
3221 }
3222
3223 // Close the inner scope so that the ResourceMark and HandleMark
3224 // destructors are executed here and are included as part of the
3225 // "GC Worker Time".
3226 }
3227 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3228 }
3229 };
3230
print_termination_stats_hdr()3231 void G1CollectedHeap::print_termination_stats_hdr() {
3232 log_debug(gc, task, stats)("GC Termination Stats");
3233 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3234 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3235 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3236 }
3237
print_termination_stats(uint worker_id,double elapsed_ms,double strong_roots_ms,double term_ms,size_t term_attempts,size_t alloc_buffer_waste,size_t undo_waste) const3238 void G1CollectedHeap::print_termination_stats(uint worker_id,
3239 double elapsed_ms,
3240 double strong_roots_ms,
3241 double term_ms,
3242 size_t term_attempts,
3243 size_t alloc_buffer_waste,
3244 size_t undo_waste) const {
3245 log_debug(gc, task, stats)
3246 ("%3d %9.2f %9.2f %6.2f "
3247 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3248 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3249 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3250 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3251 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3252 alloc_buffer_waste * HeapWordSize / K,
3253 undo_waste * HeapWordSize / K);
3254 }
3255
3256 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3257 private:
3258 BoolObjectClosure* _is_alive;
3259 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3260 OopStorage::ParState<false /* concurrent */, false /* const */> _par_state_string;
3261
3262 int _initial_string_table_size;
3263 int _initial_symbol_table_size;
3264
3265 bool _process_strings;
3266 int _strings_processed;
3267 int _strings_removed;
3268
3269 bool _process_symbols;
3270 int _symbols_processed;
3271 int _symbols_removed;
3272
3273 bool _process_string_dedup;
3274
3275 public:
G1StringAndSymbolCleaningTask(BoolObjectClosure * is_alive,bool process_strings,bool process_symbols,bool process_string_dedup)3276 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3277 AbstractGangTask("String/Symbol Unlinking"),
3278 _is_alive(is_alive),
3279 _dedup_closure(is_alive, NULL, false),
3280 _par_state_string(StringTable::weak_storage()),
3281 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3282 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3283 _process_string_dedup(process_string_dedup) {
3284
3285 _initial_string_table_size = (int) StringTable::the_table()->table_size();
3286 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3287 if (process_symbols) {
3288 SymbolTable::clear_parallel_claimed_index();
3289 }
3290 if (process_strings) {
3291 StringTable::reset_dead_counter();
3292 }
3293 }
3294
~G1StringAndSymbolCleaningTask()3295 ~G1StringAndSymbolCleaningTask() {
3296 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3297 "claim value %d after unlink less than initial symbol table size %d",
3298 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3299
3300 log_info(gc, stringtable)(
3301 "Cleaned string and symbol table, "
3302 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3303 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3304 strings_processed(), strings_removed(),
3305 symbols_processed(), symbols_removed());
3306 if (_process_strings) {
3307 StringTable::finish_dead_counter();
3308 }
3309 }
3310
work(uint worker_id)3311 void work(uint worker_id) {
3312 int strings_processed = 0;
3313 int strings_removed = 0;
3314 int symbols_processed = 0;
3315 int symbols_removed = 0;
3316 if (_process_strings) {
3317 StringTable::possibly_parallel_unlink(&_par_state_string, _is_alive, &strings_processed, &strings_removed);
3318 Atomic::add(strings_processed, &_strings_processed);
3319 Atomic::add(strings_removed, &_strings_removed);
3320 }
3321 if (_process_symbols) {
3322 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3323 Atomic::add(symbols_processed, &_symbols_processed);
3324 Atomic::add(symbols_removed, &_symbols_removed);
3325 }
3326 if (_process_string_dedup) {
3327 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3328 }
3329 }
3330
strings_processed() const3331 size_t strings_processed() const { return (size_t)_strings_processed; }
strings_removed() const3332 size_t strings_removed() const { return (size_t)_strings_removed; }
3333
symbols_processed() const3334 size_t symbols_processed() const { return (size_t)_symbols_processed; }
symbols_removed() const3335 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3336 };
3337
3338 class G1CodeCacheUnloadingTask {
3339 private:
3340 static Monitor* _lock;
3341
3342 BoolObjectClosure* const _is_alive;
3343 const bool _unloading_occurred;
3344 const uint _num_workers;
3345
3346 // Variables used to claim nmethods.
3347 CompiledMethod* _first_nmethod;
3348 CompiledMethod* volatile _claimed_nmethod;
3349
3350 // The list of nmethods that need to be processed by the second pass.
3351 CompiledMethod* volatile _postponed_list;
3352 volatile uint _num_entered_barrier;
3353
3354 public:
G1CodeCacheUnloadingTask(uint num_workers,BoolObjectClosure * is_alive,bool unloading_occurred)3355 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3356 _is_alive(is_alive),
3357 _unloading_occurred(unloading_occurred),
3358 _num_workers(num_workers),
3359 _first_nmethod(NULL),
3360 _claimed_nmethod(NULL),
3361 _postponed_list(NULL),
3362 _num_entered_barrier(0)
3363 {
3364 CompiledMethod::increase_unloading_clock();
3365 // Get first alive nmethod
3366 CompiledMethodIterator iter = CompiledMethodIterator();
3367 if(iter.next_alive()) {
3368 _first_nmethod = iter.method();
3369 }
3370 _claimed_nmethod = _first_nmethod;
3371 }
3372
~G1CodeCacheUnloadingTask()3373 ~G1CodeCacheUnloadingTask() {
3374 CodeCache::verify_clean_inline_caches();
3375
3376 CodeCache::set_needs_cache_clean(false);
3377 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3378
3379 CodeCache::verify_icholder_relocations();
3380 }
3381
3382 private:
add_to_postponed_list(CompiledMethod * nm)3383 void add_to_postponed_list(CompiledMethod* nm) {
3384 CompiledMethod* old;
3385 do {
3386 old = _postponed_list;
3387 nm->set_unloading_next(old);
3388 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3389 }
3390
clean_nmethod(CompiledMethod * nm)3391 void clean_nmethod(CompiledMethod* nm) {
3392 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3393
3394 if (postponed) {
3395 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3396 add_to_postponed_list(nm);
3397 }
3398
3399 // Mark that this nmethod has been cleaned/unloaded.
3400 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3401 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3402 }
3403
clean_nmethod_postponed(CompiledMethod * nm)3404 void clean_nmethod_postponed(CompiledMethod* nm) {
3405 nm->do_unloading_parallel_postponed();
3406 }
3407
3408 static const int MaxClaimNmethods = 16;
3409
claim_nmethods(CompiledMethod ** claimed_nmethods,int * num_claimed_nmethods)3410 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3411 CompiledMethod* first;
3412 CompiledMethodIterator last;
3413
3414 do {
3415 *num_claimed_nmethods = 0;
3416
3417 first = _claimed_nmethod;
3418 last = CompiledMethodIterator(first);
3419
3420 if (first != NULL) {
3421
3422 for (int i = 0; i < MaxClaimNmethods; i++) {
3423 if (!last.next_alive()) {
3424 break;
3425 }
3426 claimed_nmethods[i] = last.method();
3427 (*num_claimed_nmethods)++;
3428 }
3429 }
3430
3431 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3432 }
3433
claim_postponed_nmethod()3434 CompiledMethod* claim_postponed_nmethod() {
3435 CompiledMethod* claim;
3436 CompiledMethod* next;
3437
3438 do {
3439 claim = _postponed_list;
3440 if (claim == NULL) {
3441 return NULL;
3442 }
3443
3444 next = claim->unloading_next();
3445
3446 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3447
3448 return claim;
3449 }
3450
3451 public:
3452 // Mark that we're done with the first pass of nmethod cleaning.
barrier_mark(uint worker_id)3453 void barrier_mark(uint worker_id) {
3454 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3455 _num_entered_barrier++;
3456 if (_num_entered_barrier == _num_workers) {
3457 ml.notify_all();
3458 }
3459 }
3460
3461 // See if we have to wait for the other workers to
3462 // finish their first-pass nmethod cleaning work.
barrier_wait(uint worker_id)3463 void barrier_wait(uint worker_id) {
3464 if (_num_entered_barrier < _num_workers) {
3465 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3466 while (_num_entered_barrier < _num_workers) {
3467 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3468 }
3469 }
3470 }
3471
3472 // Cleaning and unloading of nmethods. Some work has to be postponed
3473 // to the second pass, when we know which nmethods survive.
work_first_pass(uint worker_id)3474 void work_first_pass(uint worker_id) {
3475 // The first nmethods is claimed by the first worker.
3476 if (worker_id == 0 && _first_nmethod != NULL) {
3477 clean_nmethod(_first_nmethod);
3478 _first_nmethod = NULL;
3479 }
3480
3481 int num_claimed_nmethods;
3482 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3483
3484 while (true) {
3485 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3486
3487 if (num_claimed_nmethods == 0) {
3488 break;
3489 }
3490
3491 for (int i = 0; i < num_claimed_nmethods; i++) {
3492 clean_nmethod(claimed_nmethods[i]);
3493 }
3494 }
3495 }
3496
work_second_pass(uint worker_id)3497 void work_second_pass(uint worker_id) {
3498 CompiledMethod* nm;
3499 // Take care of postponed nmethods.
3500 while ((nm = claim_postponed_nmethod()) != NULL) {
3501 clean_nmethod_postponed(nm);
3502 }
3503 }
3504 };
3505
3506 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3507
3508 class G1KlassCleaningTask : public StackObj {
3509 volatile int _clean_klass_tree_claimed;
3510 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3511
3512 public:
G1KlassCleaningTask()3513 G1KlassCleaningTask() :
3514 _clean_klass_tree_claimed(0),
3515 _klass_iterator() {
3516 }
3517
3518 private:
claim_clean_klass_tree_task()3519 bool claim_clean_klass_tree_task() {
3520 if (_clean_klass_tree_claimed) {
3521 return false;
3522 }
3523
3524 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3525 }
3526
claim_next_klass()3527 InstanceKlass* claim_next_klass() {
3528 Klass* klass;
3529 do {
3530 klass =_klass_iterator.next_klass();
3531 } while (klass != NULL && !klass->is_instance_klass());
3532
3533 // this can be null so don't call InstanceKlass::cast
3534 return static_cast<InstanceKlass*>(klass);
3535 }
3536
3537 public:
3538
clean_klass(InstanceKlass * ik)3539 void clean_klass(InstanceKlass* ik) {
3540 ik->clean_weak_instanceklass_links();
3541 }
3542
work()3543 void work() {
3544 ResourceMark rm;
3545
3546 // One worker will clean the subklass/sibling klass tree.
3547 if (claim_clean_klass_tree_task()) {
3548 Klass::clean_subklass_tree();
3549 }
3550
3551 // All workers will help cleaning the classes,
3552 InstanceKlass* klass;
3553 while ((klass = claim_next_klass()) != NULL) {
3554 clean_klass(klass);
3555 }
3556 }
3557 };
3558
3559 class G1ResolvedMethodCleaningTask : public StackObj {
3560 volatile int _resolved_method_task_claimed;
3561 public:
G1ResolvedMethodCleaningTask()3562 G1ResolvedMethodCleaningTask() :
3563 _resolved_method_task_claimed(0) {}
3564
claim_resolved_method_task()3565 bool claim_resolved_method_task() {
3566 if (_resolved_method_task_claimed) {
3567 return false;
3568 }
3569 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3570 }
3571
3572 // These aren't big, one thread can do it all.
work()3573 void work() {
3574 if (claim_resolved_method_task()) {
3575 ResolvedMethodTable::unlink();
3576 }
3577 }
3578 };
3579
3580
3581 // To minimize the remark pause times, the tasks below are done in parallel.
3582 class G1ParallelCleaningTask : public AbstractGangTask {
3583 private:
3584 bool _unloading_occurred;
3585 G1StringAndSymbolCleaningTask _string_symbol_task;
3586 G1CodeCacheUnloadingTask _code_cache_task;
3587 G1KlassCleaningTask _klass_cleaning_task;
3588 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3589
3590 public:
3591 // The constructor is run in the VMThread.
G1ParallelCleaningTask(BoolObjectClosure * is_alive,uint num_workers,bool unloading_occurred)3592 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3593 AbstractGangTask("Parallel Cleaning"),
3594 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3595 _code_cache_task(num_workers, is_alive, unloading_occurred),
3596 _klass_cleaning_task(),
3597 _unloading_occurred(unloading_occurred),
3598 _resolved_method_cleaning_task() {
3599 }
3600
3601 // The parallel work done by all worker threads.
work(uint worker_id)3602 void work(uint worker_id) {
3603 // Do first pass of code cache cleaning.
3604 _code_cache_task.work_first_pass(worker_id);
3605
3606 // Let the threads mark that the first pass is done.
3607 _code_cache_task.barrier_mark(worker_id);
3608
3609 // Clean the Strings and Symbols.
3610 _string_symbol_task.work(worker_id);
3611
3612 // Clean unreferenced things in the ResolvedMethodTable
3613 _resolved_method_cleaning_task.work();
3614
3615 // Wait for all workers to finish the first code cache cleaning pass.
3616 _code_cache_task.barrier_wait(worker_id);
3617
3618 // Do the second code cache cleaning work, which realize on
3619 // the liveness information gathered during the first pass.
3620 _code_cache_task.work_second_pass(worker_id);
3621
3622 // Clean all klasses that were not unloaded.
3623 // The weak metadata in klass doesn't need to be
3624 // processed if there was no unloading.
3625 if (_unloading_occurred) {
3626 _klass_cleaning_task.work();
3627 }
3628 }
3629 };
3630
3631
complete_cleaning(BoolObjectClosure * is_alive,bool class_unloading_occurred)3632 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3633 bool class_unloading_occurred) {
3634 uint n_workers = workers()->active_workers();
3635
3636 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3637 workers()->run_task(&g1_unlink_task);
3638 }
3639
partial_cleaning(BoolObjectClosure * is_alive,bool process_strings,bool process_symbols,bool process_string_dedup)3640 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3641 bool process_strings,
3642 bool process_symbols,
3643 bool process_string_dedup) {
3644 if (!process_strings && !process_symbols && !process_string_dedup) {
3645 // Nothing to clean.
3646 return;
3647 }
3648
3649 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3650 workers()->run_task(&g1_unlink_task);
3651
3652 }
3653
3654 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3655 private:
3656 DirtyCardQueueSet* _queue;
3657 G1CollectedHeap* _g1h;
3658 public:
G1RedirtyLoggedCardsTask(DirtyCardQueueSet * queue,G1CollectedHeap * g1h)3659 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3660 _queue(queue), _g1h(g1h) { }
3661
work(uint worker_id)3662 virtual void work(uint worker_id) {
3663 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3664 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3665
3666 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3667 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3668
3669 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3670 }
3671 };
3672
redirty_logged_cards()3673 void G1CollectedHeap::redirty_logged_cards() {
3674 double redirty_logged_cards_start = os::elapsedTime();
3675
3676 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3677 dirty_card_queue_set().reset_for_par_iteration();
3678 workers()->run_task(&redirty_task);
3679
3680 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3681 dcq.merge_bufferlists(&dirty_card_queue_set());
3682 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3683
3684 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3685 }
3686
3687 // Weak Reference Processing support
3688
do_object_b(oop p)3689 bool G1STWIsAliveClosure::do_object_b(oop p) {
3690 // An object is reachable if it is outside the collection set,
3691 // or is inside and copied.
3692 return !_g1h->is_in_cset(p) || p->is_forwarded();
3693 }
3694
do_object_b(oop obj)3695 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3696 assert(obj != NULL, "must not be NULL");
3697 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3698 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3699 // may falsely indicate that this is not the case here: however the collection set only
3700 // contains old regions when concurrent mark is not running.
3701 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3702 }
3703
3704 // Non Copying Keep Alive closure
3705 class G1KeepAliveClosure: public OopClosure {
3706 G1CollectedHeap*_g1h;
3707 public:
G1KeepAliveClosure(G1CollectedHeap * g1h)3708 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
do_oop(narrowOop * p)3709 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
do_oop(oop * p)3710 void do_oop(oop* p) {
3711 oop obj = *p;
3712 assert(obj != NULL, "the caller should have filtered out NULL values");
3713
3714 const InCSetState cset_state =_g1h->in_cset_state(obj);
3715 if (!cset_state.is_in_cset_or_humongous()) {
3716 return;
3717 }
3718 if (cset_state.is_in_cset()) {
3719 assert( obj->is_forwarded(), "invariant" );
3720 *p = obj->forwardee();
3721 } else {
3722 assert(!obj->is_forwarded(), "invariant" );
3723 assert(cset_state.is_humongous(),
3724 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3725 _g1h->set_humongous_is_live(obj);
3726 }
3727 }
3728 };
3729
3730 // Copying Keep Alive closure - can be called from both
3731 // serial and parallel code as long as different worker
3732 // threads utilize different G1ParScanThreadState instances
3733 // and different queues.
3734
3735 class G1CopyingKeepAliveClosure: public OopClosure {
3736 G1CollectedHeap* _g1h;
3737 OopClosure* _copy_non_heap_obj_cl;
3738 G1ParScanThreadState* _par_scan_state;
3739
3740 public:
G1CopyingKeepAliveClosure(G1CollectedHeap * g1h,OopClosure * non_heap_obj_cl,G1ParScanThreadState * pss)3741 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3742 OopClosure* non_heap_obj_cl,
3743 G1ParScanThreadState* pss):
3744 _g1h(g1h),
3745 _copy_non_heap_obj_cl(non_heap_obj_cl),
3746 _par_scan_state(pss)
3747 {}
3748
do_oop(narrowOop * p)3749 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
do_oop(oop * p)3750 virtual void do_oop( oop* p) { do_oop_work(p); }
3751
do_oop_work(T * p)3752 template <class T> void do_oop_work(T* p) {
3753 oop obj = RawAccess<>::oop_load(p);
3754
3755 if (_g1h->is_in_cset_or_humongous(obj)) {
3756 // If the referent object has been forwarded (either copied
3757 // to a new location or to itself in the event of an
3758 // evacuation failure) then we need to update the reference
3759 // field and, if both reference and referent are in the G1
3760 // heap, update the RSet for the referent.
3761 //
3762 // If the referent has not been forwarded then we have to keep
3763 // it alive by policy. Therefore we have copy the referent.
3764 //
3765 // If the reference field is in the G1 heap then we can push
3766 // on the PSS queue. When the queue is drained (after each
3767 // phase of reference processing) the object and it's followers
3768 // will be copied, the reference field set to point to the
3769 // new location, and the RSet updated. Otherwise we need to
3770 // use the the non-heap or metadata closures directly to copy
3771 // the referent object and update the pointer, while avoiding
3772 // updating the RSet.
3773
3774 if (_g1h->is_in_g1_reserved(p)) {
3775 _par_scan_state->push_on_queue(p);
3776 } else {
3777 assert(!Metaspace::contains((const void*)p),
3778 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3779 _copy_non_heap_obj_cl->do_oop(p);
3780 }
3781 }
3782 }
3783 };
3784
3785 // Serial drain queue closure. Called as the 'complete_gc'
3786 // closure for each discovered list in some of the
3787 // reference processing phases.
3788
3789 class G1STWDrainQueueClosure: public VoidClosure {
3790 protected:
3791 G1CollectedHeap* _g1h;
3792 G1ParScanThreadState* _par_scan_state;
3793
par_scan_state()3794 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3795
3796 public:
G1STWDrainQueueClosure(G1CollectedHeap * g1h,G1ParScanThreadState * pss)3797 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3798 _g1h(g1h),
3799 _par_scan_state(pss)
3800 { }
3801
do_void()3802 void do_void() {
3803 G1ParScanThreadState* const pss = par_scan_state();
3804 pss->trim_queue();
3805 }
3806 };
3807
3808 // Parallel Reference Processing closures
3809
3810 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3811 // processing during G1 evacuation pauses.
3812
3813 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3814 private:
3815 G1CollectedHeap* _g1h;
3816 G1ParScanThreadStateSet* _pss;
3817 RefToScanQueueSet* _queues;
3818 WorkGang* _workers;
3819
3820 public:
G1STWRefProcTaskExecutor(G1CollectedHeap * g1h,G1ParScanThreadStateSet * per_thread_states,WorkGang * workers,RefToScanQueueSet * task_queues)3821 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3822 G1ParScanThreadStateSet* per_thread_states,
3823 WorkGang* workers,
3824 RefToScanQueueSet *task_queues) :
3825 _g1h(g1h),
3826 _pss(per_thread_states),
3827 _queues(task_queues),
3828 _workers(workers)
3829 {
3830 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3831 }
3832
3833 // Executes the given task using concurrent marking worker threads.
3834 virtual void execute(ProcessTask& task, uint ergo_workers);
3835 };
3836
3837 // Gang task for possibly parallel reference processing
3838
3839 class G1STWRefProcTaskProxy: public AbstractGangTask {
3840 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3841 ProcessTask& _proc_task;
3842 G1CollectedHeap* _g1h;
3843 G1ParScanThreadStateSet* _pss;
3844 RefToScanQueueSet* _task_queues;
3845 ParallelTaskTerminator* _terminator;
3846
3847 public:
G1STWRefProcTaskProxy(ProcessTask & proc_task,G1CollectedHeap * g1h,G1ParScanThreadStateSet * per_thread_states,RefToScanQueueSet * task_queues,ParallelTaskTerminator * terminator)3848 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3849 G1CollectedHeap* g1h,
3850 G1ParScanThreadStateSet* per_thread_states,
3851 RefToScanQueueSet *task_queues,
3852 ParallelTaskTerminator* terminator) :
3853 AbstractGangTask("Process reference objects in parallel"),
3854 _proc_task(proc_task),
3855 _g1h(g1h),
3856 _pss(per_thread_states),
3857 _task_queues(task_queues),
3858 _terminator(terminator)
3859 {}
3860
work(uint worker_id)3861 virtual void work(uint worker_id) {
3862 // The reference processing task executed by a single worker.
3863 ResourceMark rm;
3864 HandleMark hm;
3865
3866 G1STWIsAliveClosure is_alive(_g1h);
3867
3868 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3869 pss->set_ref_discoverer(NULL);
3870
3871 // Keep alive closure.
3872 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3873
3874 // Complete GC closure
3875 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3876
3877 // Call the reference processing task's work routine.
3878 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3879
3880 // Note we cannot assert that the refs array is empty here as not all
3881 // of the processing tasks (specifically phase2 - pp2_work) execute
3882 // the complete_gc closure (which ordinarily would drain the queue) so
3883 // the queue may not be empty.
3884 }
3885 };
3886
3887 // Driver routine for parallel reference processing.
3888 // Creates an instance of the ref processing gang
3889 // task and has the worker threads execute it.
execute(ProcessTask & proc_task,uint ergo_workers)3890 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3891 assert(_workers != NULL, "Need parallel worker threads.");
3892
3893 assert(_workers->active_workers() >= ergo_workers,
3894 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3895 ergo_workers, _workers->active_workers());
3896 ParallelTaskTerminator terminator(ergo_workers, _queues);
3897 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3898
3899 _workers->run_task(&proc_task_proxy, ergo_workers);
3900 }
3901
3902 // End of weak reference support closures
3903
process_discovered_references(G1ParScanThreadStateSet * per_thread_states)3904 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3905 double ref_proc_start = os::elapsedTime();
3906
3907 ReferenceProcessor* rp = _ref_processor_stw;
3908 assert(rp->discovery_enabled(), "should have been enabled");
3909
3910 // Closure to test whether a referent is alive.
3911 G1STWIsAliveClosure is_alive(this);
3912
3913 // Even when parallel reference processing is enabled, the processing
3914 // of JNI refs is serial and performed serially by the current thread
3915 // rather than by a worker. The following PSS will be used for processing
3916 // JNI refs.
3917
3918 // Use only a single queue for this PSS.
3919 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3920 pss->set_ref_discoverer(NULL);
3921 assert(pss->queue_is_empty(), "pre-condition");
3922
3923 // Keep alive closure.
3924 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
3925
3926 // Serial Complete GC closure
3927 G1STWDrainQueueClosure drain_queue(this, pss);
3928
3929 // Setup the soft refs policy...
3930 rp->setup_policy(false);
3931
3932 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3933
3934 ReferenceProcessorStats stats;
3935 if (!rp->processing_is_mt()) {
3936 // Serial reference processing...
3937 stats = rp->process_discovered_references(&is_alive,
3938 &keep_alive,
3939 &drain_queue,
3940 NULL,
3941 pt);
3942 } else {
3943 uint no_of_gc_workers = workers()->active_workers();
3944
3945 // Parallel reference processing
3946 assert(no_of_gc_workers <= rp->max_num_queues(),
3947 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3948 no_of_gc_workers, rp->max_num_queues());
3949
3950 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3951 stats = rp->process_discovered_references(&is_alive,
3952 &keep_alive,
3953 &drain_queue,
3954 &par_task_executor,
3955 pt);
3956 }
3957
3958 _gc_tracer_stw->report_gc_reference_stats(stats);
3959
3960 // We have completed copying any necessary live referent objects.
3961 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3962
3963 make_pending_list_reachable();
3964
3965 rp->verify_no_references_recorded();
3966
3967 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3968 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3969 }
3970
make_pending_list_reachable()3971 void G1CollectedHeap::make_pending_list_reachable() {
3972 if (collector_state()->in_initial_mark_gc()) {
3973 oop pll_head = Universe::reference_pending_list();
3974 if (pll_head != NULL) {
3975 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3976 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3977 }
3978 }
3979 }
3980
merge_per_thread_state_info(G1ParScanThreadStateSet * per_thread_states)3981 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3982 double merge_pss_time_start = os::elapsedTime();
3983 per_thread_states->flush();
3984 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3985 }
3986
pre_evacuate_collection_set()3987 void G1CollectedHeap::pre_evacuate_collection_set() {
3988 _expand_heap_after_alloc_failure = true;
3989 _evacuation_failed = false;
3990
3991 // Disable the hot card cache.
3992 _hot_card_cache->reset_hot_cache_claimed_index();
3993 _hot_card_cache->set_use_cache(false);
3994
3995 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3996 _preserved_marks_set.assert_empty();
3997
3998 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3999
4000 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4001 if (collector_state()->in_initial_mark_gc()) {
4002 double start_clear_claimed_marks = os::elapsedTime();
4003
4004 ClassLoaderDataGraph::clear_claimed_marks();
4005
4006 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4007 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4008 }
4009 }
4010
evacuate_collection_set(G1ParScanThreadStateSet * per_thread_states)4011 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
4012 // Should G1EvacuationFailureALot be in effect for this GC?
4013 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4014
4015 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4016
4017 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4018
4019 double start_par_time_sec = os::elapsedTime();
4020 double end_par_time_sec;
4021
4022 {
4023 const uint n_workers = workers()->active_workers();
4024 G1RootProcessor root_processor(this, n_workers);
4025 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4026
4027 print_termination_stats_hdr();
4028
4029 workers()->run_task(&g1_par_task);
4030 end_par_time_sec = os::elapsedTime();
4031
4032 // Closing the inner scope will execute the destructor
4033 // for the G1RootProcessor object. We record the current
4034 // elapsed time before closing the scope so that time
4035 // taken for the destructor is NOT included in the
4036 // reported parallel time.
4037 }
4038
4039 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4040 phase_times->record_par_time(par_time_ms);
4041
4042 double code_root_fixup_time_ms =
4043 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4044 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4045 }
4046
post_evacuate_collection_set(EvacuationInfo & evacuation_info,G1ParScanThreadStateSet * per_thread_states)4047 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4048 // Also cleans the card table from temporary duplicate detection information used
4049 // during UpdateRS/ScanRS.
4050 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4051
4052 // Process any discovered reference objects - we have
4053 // to do this _before_ we retire the GC alloc regions
4054 // as we may have to copy some 'reachable' referent
4055 // objects (and their reachable sub-graphs) that were
4056 // not copied during the pause.
4057 process_discovered_references(per_thread_states);
4058
4059 // FIXME
4060 // CM's reference processing also cleans up the string and symbol tables.
4061 // Should we do that here also? We could, but it is a serial operation
4062 // and could significantly increase the pause time.
4063
4064 G1STWIsAliveClosure is_alive(this);
4065 G1KeepAliveClosure keep_alive(this);
4066
4067 {
4068 double start = os::elapsedTime();
4069
4070 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4071
4072 double time_ms = (os::elapsedTime() - start) * 1000.0;
4073 g1_policy()->phase_times()->record_weak_ref_proc_time(time_ms);
4074 }
4075
4076 if (G1StringDedup::is_enabled()) {
4077 double fixup_start = os::elapsedTime();
4078
4079 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4080
4081 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4082 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4083 }
4084
4085 if (evacuation_failed()) {
4086 restore_after_evac_failure();
4087
4088 // Reset the G1EvacuationFailureALot counters and flags
4089 // Note: the values are reset only when an actual
4090 // evacuation failure occurs.
4091 NOT_PRODUCT(reset_evacuation_should_fail();)
4092 }
4093
4094 _preserved_marks_set.assert_empty();
4095
4096 _allocator->release_gc_alloc_regions(evacuation_info);
4097
4098 merge_per_thread_state_info(per_thread_states);
4099
4100 // Reset and re-enable the hot card cache.
4101 // Note the counts for the cards in the regions in the
4102 // collection set are reset when the collection set is freed.
4103 _hot_card_cache->reset_hot_cache();
4104 _hot_card_cache->set_use_cache(true);
4105
4106 purge_code_root_memory();
4107
4108 redirty_logged_cards();
4109 #if COMPILER2_OR_JVMCI
4110 double start = os::elapsedTime();
4111 DerivedPointerTable::update_pointers();
4112 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4113 #endif
4114 g1_policy()->print_age_table();
4115 }
4116
record_obj_copy_mem_stats()4117 void G1CollectedHeap::record_obj_copy_mem_stats() {
4118 g1_policy()->old_gen_alloc_tracker()->
4119 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4120
4121 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4122 create_g1_evac_summary(&_old_evac_stats));
4123 }
4124
free_region(HeapRegion * hr,FreeRegionList * free_list,bool skip_remset,bool skip_hot_card_cache,bool locked)4125 void G1CollectedHeap::free_region(HeapRegion* hr,
4126 FreeRegionList* free_list,
4127 bool skip_remset,
4128 bool skip_hot_card_cache,
4129 bool locked) {
4130 assert(!hr->is_free(), "the region should not be free");
4131 assert(!hr->is_empty(), "the region should not be empty");
4132 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4133 assert(free_list != NULL, "pre-condition");
4134
4135 if (G1VerifyBitmaps) {
4136 MemRegion mr(hr->bottom(), hr->end());
4137 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4138 }
4139
4140 // Clear the card counts for this region.
4141 // Note: we only need to do this if the region is not young
4142 // (since we don't refine cards in young regions).
4143 if (!skip_hot_card_cache && !hr->is_young()) {
4144 _hot_card_cache->reset_card_counts(hr);
4145 }
4146 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4147 _g1_policy->remset_tracker()->update_at_free(hr);
4148 free_list->add_ordered(hr);
4149 }
4150
free_humongous_region(HeapRegion * hr,FreeRegionList * free_list)4151 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4152 FreeRegionList* free_list) {
4153 assert(hr->is_humongous(), "this is only for humongous regions");
4154 assert(free_list != NULL, "pre-condition");
4155 hr->clear_humongous();
4156 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4157 }
4158
remove_from_old_sets(const uint old_regions_removed,const uint humongous_regions_removed)4159 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4160 const uint humongous_regions_removed) {
4161 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4162 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4163 _old_set.bulk_remove(old_regions_removed);
4164 _humongous_set.bulk_remove(humongous_regions_removed);
4165 }
4166
4167 }
4168
prepend_to_freelist(FreeRegionList * list)4169 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4170 assert(list != NULL, "list can't be null");
4171 if (!list->is_empty()) {
4172 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4173 _hrm.insert_list_into_free_list(list);
4174 }
4175 }
4176
decrement_summary_bytes(size_t bytes)4177 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4178 decrease_used(bytes);
4179 }
4180
4181 class G1FreeCollectionSetTask : public AbstractGangTask {
4182 private:
4183
4184 // Closure applied to all regions in the collection set to do work that needs to
4185 // be done serially in a single thread.
4186 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4187 private:
4188 EvacuationInfo* _evacuation_info;
4189 const size_t* _surviving_young_words;
4190
4191 // Bytes used in successfully evacuated regions before the evacuation.
4192 size_t _before_used_bytes;
4193 // Bytes used in unsucessfully evacuated regions before the evacuation
4194 size_t _after_used_bytes;
4195
4196 size_t _bytes_allocated_in_old_since_last_gc;
4197
4198 size_t _failure_used_words;
4199 size_t _failure_waste_words;
4200
4201 FreeRegionList _local_free_list;
4202 public:
G1SerialFreeCollectionSetClosure(EvacuationInfo * evacuation_info,const size_t * surviving_young_words)4203 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4204 HeapRegionClosure(),
4205 _evacuation_info(evacuation_info),
4206 _surviving_young_words(surviving_young_words),
4207 _before_used_bytes(0),
4208 _after_used_bytes(0),
4209 _bytes_allocated_in_old_since_last_gc(0),
4210 _failure_used_words(0),
4211 _failure_waste_words(0),
4212 _local_free_list("Local Region List for CSet Freeing") {
4213 }
4214
do_heap_region(HeapRegion * r)4215 virtual bool do_heap_region(HeapRegion* r) {
4216 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4217
4218 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4219 g1h->clear_in_cset(r);
4220
4221 if (r->is_young()) {
4222 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4223 "Young index %d is wrong for region %u of type %s with %u young regions",
4224 r->young_index_in_cset(),
4225 r->hrm_index(),
4226 r->get_type_str(),
4227 g1h->collection_set()->young_region_length());
4228 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4229 r->record_surv_words_in_group(words_survived);
4230 }
4231
4232 if (!r->evacuation_failed()) {
4233 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4234 _before_used_bytes += r->used();
4235 g1h->free_region(r,
4236 &_local_free_list,
4237 true, /* skip_remset */
4238 true, /* skip_hot_card_cache */
4239 true /* locked */);
4240 } else {
4241 r->uninstall_surv_rate_group();
4242 r->set_young_index_in_cset(-1);
4243 r->set_evacuation_failed(false);
4244 // When moving a young gen region to old gen, we "allocate" that whole region
4245 // there. This is in addition to any already evacuated objects. Notify the
4246 // policy about that.
4247 // Old gen regions do not cause an additional allocation: both the objects
4248 // still in the region and the ones already moved are accounted for elsewhere.
4249 if (r->is_young()) {
4250 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4251 }
4252 // The region is now considered to be old.
4253 r->set_old();
4254 // Do some allocation statistics accounting. Regions that failed evacuation
4255 // are always made old, so there is no need to update anything in the young
4256 // gen statistics, but we need to update old gen statistics.
4257 size_t used_words = r->marked_bytes() / HeapWordSize;
4258
4259 _failure_used_words += used_words;
4260 _failure_waste_words += HeapRegion::GrainWords - used_words;
4261
4262 g1h->old_set_add(r);
4263 _after_used_bytes += r->used();
4264 }
4265 return false;
4266 }
4267
complete_work()4268 void complete_work() {
4269 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4270
4271 _evacuation_info->set_regions_freed(_local_free_list.length());
4272 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4273
4274 g1h->prepend_to_freelist(&_local_free_list);
4275 g1h->decrement_summary_bytes(_before_used_bytes);
4276
4277 G1Policy* policy = g1h->g1_policy();
4278 policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4279
4280 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4281 }
4282 };
4283
4284 G1CollectionSet* _collection_set;
4285 G1SerialFreeCollectionSetClosure _cl;
4286 const size_t* _surviving_young_words;
4287
4288 size_t _rs_lengths;
4289
4290 volatile jint _serial_work_claim;
4291
4292 struct WorkItem {
4293 uint region_idx;
4294 bool is_young;
4295 bool evacuation_failed;
4296
WorkItemG1FreeCollectionSetTask::WorkItem4297 WorkItem(HeapRegion* r) {
4298 region_idx = r->hrm_index();
4299 is_young = r->is_young();
4300 evacuation_failed = r->evacuation_failed();
4301 }
4302 };
4303
4304 volatile size_t _parallel_work_claim;
4305 size_t _num_work_items;
4306 WorkItem* _work_items;
4307
do_serial_work()4308 void do_serial_work() {
4309 // Need to grab the lock to be allowed to modify the old region list.
4310 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4311 _collection_set->iterate(&_cl);
4312 }
4313
do_parallel_work_for_region(uint region_idx,bool is_young,bool evacuation_failed)4314 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4315 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4316
4317 HeapRegion* r = g1h->region_at(region_idx);
4318 assert(!g1h->is_on_master_free_list(r), "sanity");
4319
4320 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4321
4322 if (!is_young) {
4323 g1h->_hot_card_cache->reset_card_counts(r);
4324 }
4325
4326 if (!evacuation_failed) {
4327 r->rem_set()->clear_locked();
4328 }
4329 }
4330
4331 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4332 private:
4333 size_t _cur_idx;
4334 WorkItem* _work_items;
4335 public:
G1PrepareFreeCollectionSetClosure(WorkItem * work_items)4336 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4337
do_heap_region(HeapRegion * r)4338 virtual bool do_heap_region(HeapRegion* r) {
4339 _work_items[_cur_idx++] = WorkItem(r);
4340 return false;
4341 }
4342 };
4343
prepare_work()4344 void prepare_work() {
4345 G1PrepareFreeCollectionSetClosure cl(_work_items);
4346 _collection_set->iterate(&cl);
4347 }
4348
complete_work()4349 void complete_work() {
4350 _cl.complete_work();
4351
4352 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4353 policy->record_max_rs_lengths(_rs_lengths);
4354 policy->cset_regions_freed();
4355 }
4356 public:
G1FreeCollectionSetTask(G1CollectionSet * collection_set,EvacuationInfo * evacuation_info,const size_t * surviving_young_words)4357 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4358 AbstractGangTask("G1 Free Collection Set"),
4359 _cl(evacuation_info, surviving_young_words),
4360 _collection_set(collection_set),
4361 _surviving_young_words(surviving_young_words),
4362 _serial_work_claim(0),
4363 _rs_lengths(0),
4364 _parallel_work_claim(0),
4365 _num_work_items(collection_set->region_length()),
4366 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4367 prepare_work();
4368 }
4369
~G1FreeCollectionSetTask()4370 ~G1FreeCollectionSetTask() {
4371 complete_work();
4372 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4373 }
4374
4375 // Chunk size for work distribution. The chosen value has been determined experimentally
4376 // to be a good tradeoff between overhead and achievable parallelism.
chunk_size()4377 static uint chunk_size() { return 32; }
4378
work(uint worker_id)4379 virtual void work(uint worker_id) {
4380 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4381
4382 // Claim serial work.
4383 if (_serial_work_claim == 0) {
4384 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4385 if (value == 0) {
4386 double serial_time = os::elapsedTime();
4387 do_serial_work();
4388 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4389 }
4390 }
4391
4392 // Start parallel work.
4393 double young_time = 0.0;
4394 bool has_young_time = false;
4395 double non_young_time = 0.0;
4396 bool has_non_young_time = false;
4397
4398 while (true) {
4399 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4400 size_t cur = end - chunk_size();
4401
4402 if (cur >= _num_work_items) {
4403 break;
4404 }
4405
4406 double start_time = os::elapsedTime();
4407
4408 end = MIN2(end, _num_work_items);
4409
4410 for (; cur < end; cur++) {
4411 bool is_young = _work_items[cur].is_young;
4412
4413 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4414
4415 double end_time = os::elapsedTime();
4416 double time_taken = end_time - start_time;
4417 if (is_young) {
4418 young_time += time_taken;
4419 has_young_time = true;
4420 } else {
4421 non_young_time += time_taken;
4422 has_non_young_time = true;
4423 }
4424 start_time = end_time;
4425 }
4426 }
4427
4428 if (has_young_time) {
4429 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4430 }
4431 if (has_non_young_time) {
4432 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4433 }
4434 }
4435 };
4436
free_collection_set(G1CollectionSet * collection_set,EvacuationInfo & evacuation_info,const size_t * surviving_young_words)4437 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4438 _eden.clear();
4439
4440 double free_cset_start_time = os::elapsedTime();
4441
4442 {
4443 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4444 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4445
4446 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4447
4448 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4449 cl.name(),
4450 num_workers,
4451 _collection_set.region_length());
4452 workers()->run_task(&cl, num_workers);
4453 }
4454 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4455
4456 collection_set->clear();
4457 }
4458
4459 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4460 private:
4461 FreeRegionList* _free_region_list;
4462 HeapRegionSet* _proxy_set;
4463 uint _humongous_objects_reclaimed;
4464 uint _humongous_regions_reclaimed;
4465 size_t _freed_bytes;
4466 public:
4467
G1FreeHumongousRegionClosure(FreeRegionList * free_region_list)4468 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4469 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4470 }
4471
do_heap_region(HeapRegion * r)4472 virtual bool do_heap_region(HeapRegion* r) {
4473 if (!r->is_starts_humongous()) {
4474 return false;
4475 }
4476
4477 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4478
4479 oop obj = (oop)r->bottom();
4480 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4481
4482 // The following checks whether the humongous object is live are sufficient.
4483 // The main additional check (in addition to having a reference from the roots
4484 // or the young gen) is whether the humongous object has a remembered set entry.
4485 //
4486 // A humongous object cannot be live if there is no remembered set for it
4487 // because:
4488 // - there can be no references from within humongous starts regions referencing
4489 // the object because we never allocate other objects into them.
4490 // (I.e. there are no intra-region references that may be missed by the
4491 // remembered set)
4492 // - as soon there is a remembered set entry to the humongous starts region
4493 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4494 // until the end of a concurrent mark.
4495 //
4496 // It is not required to check whether the object has been found dead by marking
4497 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4498 // all objects allocated during that time are considered live.
4499 // SATB marking is even more conservative than the remembered set.
4500 // So if at this point in the collection there is no remembered set entry,
4501 // nobody has a reference to it.
4502 // At the start of collection we flush all refinement logs, and remembered sets
4503 // are completely up-to-date wrt to references to the humongous object.
4504 //
4505 // Other implementation considerations:
4506 // - never consider object arrays at this time because they would pose
4507 // considerable effort for cleaning up the the remembered sets. This is
4508 // required because stale remembered sets might reference locations that
4509 // are currently allocated into.
4510 uint region_idx = r->hrm_index();
4511 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4512 !r->rem_set()->is_empty()) {
4513 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",
4514 region_idx,
4515 (size_t)obj->size() * HeapWordSize,
4516 p2i(r->bottom()),
4517 r->rem_set()->occupied(),
4518 r->rem_set()->strong_code_roots_list_length(),
4519 next_bitmap->is_marked(r->bottom()),
4520 g1h->is_humongous_reclaim_candidate(region_idx),
4521 obj->is_typeArray()
4522 );
4523 return false;
4524 }
4525
4526 guarantee(obj->is_typeArray(),
4527 "Only eagerly reclaiming type arrays is supported, but the object "
4528 PTR_FORMAT " is not.", p2i(r->bottom()));
4529
4530 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",
4531 region_idx,
4532 (size_t)obj->size() * HeapWordSize,
4533 p2i(r->bottom()),
4534 r->rem_set()->occupied(),
4535 r->rem_set()->strong_code_roots_list_length(),
4536 next_bitmap->is_marked(r->bottom()),
4537 g1h->is_humongous_reclaim_candidate(region_idx),
4538 obj->is_typeArray()
4539 );
4540
4541 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4542 cm->humongous_object_eagerly_reclaimed(r);
4543 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4544 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4545 region_idx,
4546 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4547 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4548 _humongous_objects_reclaimed++;
4549 do {
4550 HeapRegion* next = g1h->next_region_in_humongous(r);
4551 _freed_bytes += r->used();
4552 r->set_containing_set(NULL);
4553 _humongous_regions_reclaimed++;
4554 g1h->free_humongous_region(r, _free_region_list);
4555 r = next;
4556 } while (r != NULL);
4557
4558 return false;
4559 }
4560
humongous_objects_reclaimed()4561 uint humongous_objects_reclaimed() {
4562 return _humongous_objects_reclaimed;
4563 }
4564
humongous_regions_reclaimed()4565 uint humongous_regions_reclaimed() {
4566 return _humongous_regions_reclaimed;
4567 }
4568
bytes_freed() const4569 size_t bytes_freed() const {
4570 return _freed_bytes;
4571 }
4572 };
4573
eagerly_reclaim_humongous_regions()4574 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4575 assert_at_safepoint_on_vm_thread();
4576
4577 if (!G1EagerReclaimHumongousObjects ||
4578 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4579 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4580 return;
4581 }
4582
4583 double start_time = os::elapsedTime();
4584
4585 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4586
4587 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4588 heap_region_iterate(&cl);
4589
4590 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4591
4592 G1HRPrinter* hrp = hr_printer();
4593 if (hrp->is_active()) {
4594 FreeRegionListIterator iter(&local_cleanup_list);
4595 while (iter.more_available()) {
4596 HeapRegion* hr = iter.get_next();
4597 hrp->cleanup(hr);
4598 }
4599 }
4600
4601 prepend_to_freelist(&local_cleanup_list);
4602 decrement_summary_bytes(cl.bytes_freed());
4603
4604 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4605 cl.humongous_objects_reclaimed());
4606 }
4607
4608 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4609 public:
do_heap_region(HeapRegion * r)4610 virtual bool do_heap_region(HeapRegion* r) {
4611 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4612 G1CollectedHeap::heap()->clear_in_cset(r);
4613 r->set_young_index_in_cset(-1);
4614 return false;
4615 }
4616 };
4617
abandon_collection_set(G1CollectionSet * collection_set)4618 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4619 G1AbandonCollectionSetClosure cl;
4620 collection_set->iterate(&cl);
4621
4622 collection_set->clear();
4623 collection_set->stop_incremental_building();
4624 }
4625
is_old_gc_alloc_region(HeapRegion * hr)4626 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4627 return _allocator->is_retained_old_region(hr);
4628 }
4629
set_region_short_lived_locked(HeapRegion * hr)4630 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4631 _eden.add(hr);
4632 _g1_policy->set_region_eden(hr);
4633 }
4634
4635 #ifdef ASSERT
4636
4637 class NoYoungRegionsClosure: public HeapRegionClosure {
4638 private:
4639 bool _success;
4640 public:
NoYoungRegionsClosure()4641 NoYoungRegionsClosure() : _success(true) { }
do_heap_region(HeapRegion * r)4642 bool do_heap_region(HeapRegion* r) {
4643 if (r->is_young()) {
4644 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4645 p2i(r->bottom()), p2i(r->end()));
4646 _success = false;
4647 }
4648 return false;
4649 }
success()4650 bool success() { return _success; }
4651 };
4652
check_young_list_empty()4653 bool G1CollectedHeap::check_young_list_empty() {
4654 bool ret = (young_regions_count() == 0);
4655
4656 NoYoungRegionsClosure closure;
4657 heap_region_iterate(&closure);
4658 ret = ret && closure.success();
4659
4660 return ret;
4661 }
4662
4663 #endif // ASSERT
4664
4665 class TearDownRegionSetsClosure : public HeapRegionClosure {
4666 private:
4667 HeapRegionSet *_old_set;
4668
4669 public:
TearDownRegionSetsClosure(HeapRegionSet * old_set)4670 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4671
do_heap_region(HeapRegion * r)4672 bool do_heap_region(HeapRegion* r) {
4673 if (r->is_old()) {
4674 _old_set->remove(r);
4675 } else if(r->is_young()) {
4676 r->uninstall_surv_rate_group();
4677 } else {
4678 // We ignore free regions, we'll empty the free list afterwards.
4679 // We ignore humongous regions, we're not tearing down the
4680 // humongous regions set.
4681 assert(r->is_free() || r->is_humongous(),
4682 "it cannot be another type");
4683 }
4684 return false;
4685 }
4686
~TearDownRegionSetsClosure()4687 ~TearDownRegionSetsClosure() {
4688 assert(_old_set->is_empty(), "post-condition");
4689 }
4690 };
4691
tear_down_region_sets(bool free_list_only)4692 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4693 assert_at_safepoint_on_vm_thread();
4694
4695 if (!free_list_only) {
4696 TearDownRegionSetsClosure cl(&_old_set);
4697 heap_region_iterate(&cl);
4698
4699 // Note that emptying the _young_list is postponed and instead done as
4700 // the first step when rebuilding the regions sets again. The reason for
4701 // this is that during a full GC string deduplication needs to know if
4702 // a collected region was young or old when the full GC was initiated.
4703 }
4704 _hrm.remove_all_free_regions();
4705 }
4706
increase_used(size_t bytes)4707 void G1CollectedHeap::increase_used(size_t bytes) {
4708 _summary_bytes_used += bytes;
4709 }
4710
decrease_used(size_t bytes)4711 void G1CollectedHeap::decrease_used(size_t bytes) {
4712 assert(_summary_bytes_used >= bytes,
4713 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4714 _summary_bytes_used, bytes);
4715 _summary_bytes_used -= bytes;
4716 }
4717
set_used(size_t bytes)4718 void G1CollectedHeap::set_used(size_t bytes) {
4719 _summary_bytes_used = bytes;
4720 }
4721
4722 class RebuildRegionSetsClosure : public HeapRegionClosure {
4723 private:
4724 bool _free_list_only;
4725 HeapRegionSet* _old_set;
4726 HeapRegionManager* _hrm;
4727 size_t _total_used;
4728
4729 public:
RebuildRegionSetsClosure(bool free_list_only,HeapRegionSet * old_set,HeapRegionManager * hrm)4730 RebuildRegionSetsClosure(bool free_list_only,
4731 HeapRegionSet* old_set, HeapRegionManager* hrm) :
4732 _free_list_only(free_list_only),
4733 _old_set(old_set), _hrm(hrm), _total_used(0) {
4734 assert(_hrm->num_free_regions() == 0, "pre-condition");
4735 if (!free_list_only) {
4736 assert(_old_set->is_empty(), "pre-condition");
4737 }
4738 }
4739
do_heap_region(HeapRegion * r)4740 bool do_heap_region(HeapRegion* r) {
4741 // After full GC, no region should have a remembered set.
4742 r->rem_set()->clear(true);
4743 if (r->is_empty()) {
4744 // Add free regions to the free list
4745 r->set_free();
4746 _hrm->insert_into_free_list(r);
4747 } else if (!_free_list_only) {
4748
4749 if (r->is_humongous()) {
4750 // We ignore humongous regions. We left the humongous set unchanged.
4751 } else {
4752 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4753 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
4754 r->move_to_old();
4755 _old_set->add(r);
4756 }
4757 _total_used += r->used();
4758 }
4759
4760 return false;
4761 }
4762
total_used()4763 size_t total_used() {
4764 return _total_used;
4765 }
4766 };
4767
rebuild_region_sets(bool free_list_only)4768 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4769 assert_at_safepoint_on_vm_thread();
4770
4771 if (!free_list_only) {
4772 _eden.clear();
4773 _survivor.clear();
4774 }
4775
4776 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4777 heap_region_iterate(&cl);
4778
4779 if (!free_list_only) {
4780 set_used(cl.total_used());
4781 if (_archive_allocator != NULL) {
4782 _archive_allocator->clear_used();
4783 }
4784 }
4785 assert(used_unlocked() == recalculate_used(),
4786 "inconsistent used_unlocked(), "
4787 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4788 used_unlocked(), recalculate_used());
4789 }
4790
is_in_closed_subset(const void * p) const4791 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4792 HeapRegion* hr = heap_region_containing(p);
4793 return hr->is_in(p);
4794 }
4795
4796 // Methods for the mutator alloc region
4797
new_mutator_alloc_region(size_t word_size,bool force)4798 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4799 bool force) {
4800 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4801 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4802 if (force || should_allocate) {
4803 HeapRegion* new_alloc_region = new_region(word_size,
4804 false /* is_old */,
4805 false /* do_expand */);
4806 if (new_alloc_region != NULL) {
4807 set_region_short_lived_locked(new_alloc_region);
4808 _hr_printer.alloc(new_alloc_region, !should_allocate);
4809 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4810 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4811 return new_alloc_region;
4812 }
4813 }
4814 return NULL;
4815 }
4816
retire_mutator_alloc_region(HeapRegion * alloc_region,size_t allocated_bytes)4817 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4818 size_t allocated_bytes) {
4819 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4820 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4821
4822 collection_set()->add_eden_region(alloc_region);
4823 increase_used(allocated_bytes);
4824 _hr_printer.retire(alloc_region);
4825 // We update the eden sizes here, when the region is retired,
4826 // instead of when it's allocated, since this is the point that its
4827 // used space has been recored in _summary_bytes_used.
4828 g1mm()->update_eden_size();
4829 }
4830
4831 // Methods for the GC alloc regions
4832
has_more_regions(InCSetState dest)4833 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4834 if (dest.is_old()) {
4835 return true;
4836 } else {
4837 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4838 }
4839 }
4840
new_gc_alloc_region(size_t word_size,InCSetState dest)4841 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4842 assert(FreeList_lock->owned_by_self(), "pre-condition");
4843
4844 if (!has_more_regions(dest)) {
4845 return NULL;
4846 }
4847
4848 const bool is_survivor = dest.is_young();
4849
4850 HeapRegion* new_alloc_region = new_region(word_size,
4851 !is_survivor,
4852 true /* do_expand */);
4853 if (new_alloc_region != NULL) {
4854 if (is_survivor) {
4855 new_alloc_region->set_survivor();
4856 _survivor.add(new_alloc_region);
4857 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4858 } else {
4859 new_alloc_region->set_old();
4860 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4861 }
4862 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4863 _hr_printer.alloc(new_alloc_region);
4864 bool during_im = collector_state()->in_initial_mark_gc();
4865 new_alloc_region->note_start_of_copying(during_im);
4866 return new_alloc_region;
4867 }
4868 return NULL;
4869 }
4870
retire_gc_alloc_region(HeapRegion * alloc_region,size_t allocated_bytes,InCSetState dest)4871 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4872 size_t allocated_bytes,
4873 InCSetState dest) {
4874 bool during_im = collector_state()->in_initial_mark_gc();
4875 alloc_region->note_end_of_copying(during_im);
4876 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4877 if (dest.is_old()) {
4878 _old_set.add(alloc_region);
4879 }
4880 _hr_printer.retire(alloc_region);
4881 }
4882
alloc_highest_free_region()4883 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4884 bool expanded = false;
4885 uint index = _hrm.find_highest_free(&expanded);
4886
4887 if (index != G1_NO_HRM_INDEX) {
4888 if (expanded) {
4889 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4890 HeapRegion::GrainWords * HeapWordSize);
4891 }
4892 _hrm.allocate_free_regions_starting_at(index, 1);
4893 return region_at(index);
4894 }
4895 return NULL;
4896 }
4897
4898 // Optimized nmethod scanning
4899
4900 class RegisterNMethodOopClosure: public OopClosure {
4901 G1CollectedHeap* _g1h;
4902 nmethod* _nm;
4903
do_oop_work(T * p)4904 template <class T> void do_oop_work(T* p) {
4905 T heap_oop = RawAccess<>::oop_load(p);
4906 if (!CompressedOops::is_null(heap_oop)) {
4907 oop obj = CompressedOops::decode_not_null(heap_oop);
4908 HeapRegion* hr = _g1h->heap_region_containing(obj);
4909 assert(!hr->is_continues_humongous(),
4910 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4911 " starting at " HR_FORMAT,
4912 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4913
4914 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4915 hr->add_strong_code_root_locked(_nm);
4916 }
4917 }
4918
4919 public:
RegisterNMethodOopClosure(G1CollectedHeap * g1h,nmethod * nm)4920 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4921 _g1h(g1h), _nm(nm) {}
4922
do_oop(oop * p)4923 void do_oop(oop* p) { do_oop_work(p); }
do_oop(narrowOop * p)4924 void do_oop(narrowOop* p) { do_oop_work(p); }
4925 };
4926
4927 class UnregisterNMethodOopClosure: public OopClosure {
4928 G1CollectedHeap* _g1h;
4929 nmethod* _nm;
4930
do_oop_work(T * p)4931 template <class T> void do_oop_work(T* p) {
4932 T heap_oop = RawAccess<>::oop_load(p);
4933 if (!CompressedOops::is_null(heap_oop)) {
4934 oop obj = CompressedOops::decode_not_null(heap_oop);
4935 HeapRegion* hr = _g1h->heap_region_containing(obj);
4936 assert(!hr->is_continues_humongous(),
4937 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4938 " starting at " HR_FORMAT,
4939 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4940
4941 hr->remove_strong_code_root(_nm);
4942 }
4943 }
4944
4945 public:
UnregisterNMethodOopClosure(G1CollectedHeap * g1h,nmethod * nm)4946 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4947 _g1h(g1h), _nm(nm) {}
4948
do_oop(oop * p)4949 void do_oop(oop* p) { do_oop_work(p); }
do_oop(narrowOop * p)4950 void do_oop(narrowOop* p) { do_oop_work(p); }
4951 };
4952
4953 // Returns true if the reference points to an object that
4954 // can move in an incremental collection.
is_scavengable(oop obj)4955 bool G1CollectedHeap::is_scavengable(oop obj) {
4956 HeapRegion* hr = heap_region_containing(obj);
4957 return !hr->is_pinned();
4958 }
4959
register_nmethod(nmethod * nm)4960 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4961 guarantee(nm != NULL, "sanity");
4962 RegisterNMethodOopClosure reg_cl(this, nm);
4963 nm->oops_do(®_cl);
4964 }
4965
unregister_nmethod(nmethod * nm)4966 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4967 guarantee(nm != NULL, "sanity");
4968 UnregisterNMethodOopClosure reg_cl(this, nm);
4969 nm->oops_do(®_cl, true);
4970 }
4971
purge_code_root_memory()4972 void G1CollectedHeap::purge_code_root_memory() {
4973 double purge_start = os::elapsedTime();
4974 G1CodeRootSet::purge();
4975 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4976 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4977 }
4978
4979 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4980 G1CollectedHeap* _g1h;
4981
4982 public:
RebuildStrongCodeRootClosure(G1CollectedHeap * g1h)4983 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4984 _g1h(g1h) {}
4985
do_code_blob(CodeBlob * cb)4986 void do_code_blob(CodeBlob* cb) {
4987 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4988 if (nm == NULL) {
4989 return;
4990 }
4991
4992 if (ScavengeRootsInCode) {
4993 _g1h->register_nmethod(nm);
4994 }
4995 }
4996 };
4997
rebuild_strong_code_roots()4998 void G1CollectedHeap::rebuild_strong_code_roots() {
4999 RebuildStrongCodeRootClosure blob_cl(this);
5000 CodeCache::blobs_do(&blob_cl);
5001 }
5002
memory_managers()5003 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5004 GrowableArray<GCMemoryManager*> memory_managers(2);
5005 memory_managers.append(&_memory_manager);
5006 memory_managers.append(&_full_gc_memory_manager);
5007 return memory_managers;
5008 }
5009
memory_pools()5010 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5011 GrowableArray<MemoryPool*> memory_pools(3);
5012 memory_pools.append(_eden_pool);
5013 memory_pools.append(_survivor_pool);
5014 memory_pools.append(_old_pool);
5015 return memory_pools;
5016 }
5017