1 /*
2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentMarkThread.inline.hpp"
33 #include "gc/g1/g1Allocator.inline.hpp"
34 #include "gc/g1/g1CollectedHeap.inline.hpp"
35 #include "gc/g1/g1CollectionSet.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1MemoryPool.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1StringDedup.hpp"
56 #include "gc/g1/g1YCTypes.hpp"
57 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
58 #include "gc/g1/heapRegion.inline.hpp"
59 #include "gc/g1/heapRegionRemSet.hpp"
60 #include "gc/g1/heapRegionSet.inline.hpp"
61 #include "gc/g1/vm_operations_g1.hpp"
62 #include "gc/shared/adaptiveSizePolicy.hpp"
63 #include "gc/shared/gcHeapSummary.hpp"
64 #include "gc/shared/gcId.hpp"
65 #include "gc/shared/gcLocker.inline.hpp"
66 #include "gc/shared/gcTimer.hpp"
67 #include "gc/shared/gcTrace.hpp"
68 #include "gc/shared/gcTraceTime.inline.hpp"
69 #include "gc/shared/generationSpec.hpp"
70 #include "gc/shared/isGCActiveMark.hpp"
71 #include "gc/shared/preservedMarks.inline.hpp"
72 #include "gc/shared/suspendibleThreadSet.hpp"
73 #include "gc/shared/referenceProcessor.inline.hpp"
74 #include "gc/shared/taskqueue.inline.hpp"
75 #include "gc/shared/weakProcessor.hpp"
76 #include "logging/log.hpp"
77 #include "memory/allocation.hpp"
78 #include "memory/iterator.hpp"
79 #include "memory/resourceArea.hpp"
80 #include "oops/oop.inline.hpp"
81 #include "prims/resolvedMethodTable.hpp"
82 #include "runtime/atomic.hpp"
83 #include "runtime/init.hpp"
84 #include "runtime/orderAccess.inline.hpp"
85 #include "runtime/threadSMR.hpp"
86 #include "runtime/vmThread.hpp"
87 #include "utilities/align.hpp"
88 #include "utilities/globalDefinitions.hpp"
89 #include "utilities/stack.inline.hpp"
90
91 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
92
93 // INVARIANTS/NOTES
94 //
95 // All allocation activity covered by the G1CollectedHeap interface is
96 // serialized by acquiring the HeapLock. This happens in mem_allocate
97 // and allocate_new_tlab, which are the "entry" points to the
98 // allocation code from the rest of the JVM. (Note that this does not
99 // apply to TLAB allocation, which is not part of this interface: it
100 // is done by clients of this interface.)
101
102 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
103 private:
104 size_t _num_dirtied;
105 G1CollectedHeap* _g1h;
106 G1SATBCardTableLoggingModRefBS* _g1_bs;
107
108 HeapRegion* region_for_card(jbyte* card_ptr) const {
109 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
110 }
111
112 bool will_become_free(HeapRegion* hr) const {
113 // A region will be freed by free_collection_set if the region is in the
114 // collection set and has not had an evacuation failure.
115 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
116 }
117
118 public:
119 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
120 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
121
122 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
123 HeapRegion* hr = region_for_card(card_ptr);
124
125 // Should only dirty cards in regions that won't be freed.
126 if (!will_become_free(hr)) {
127 *card_ptr = CardTableModRefBS::dirty_card_val();
128 _num_dirtied++;
129 }
130
131 return true;
132 }
133
134 size_t num_dirtied() const { return _num_dirtied; }
135 };
136
137
138 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
139 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
140 }
141
142 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
143 // The from card cache is not the memory that is actually committed. So we cannot
144 // take advantage of the zero_filled parameter.
145 reset_from_card_cache(start_idx, num_regions);
146 }
147
148
149 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
150 MemRegion mr) {
151 return new HeapRegion(hrs_index, bot(), mr);
152 }
153
154 // Private methods.
155
156 HeapRegion*
157 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
158 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
159 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
160 if (!_secondary_free_list.is_empty()) {
161 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
162 "secondary_free_list has %u entries",
163 _secondary_free_list.length());
164 // It looks as if there are free regions available on the
165 // secondary_free_list. Let's move them to the free_list and try
166 // again to allocate from it.
167 append_secondary_free_list();
168
169 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
170 "empty we should have moved at least one entry to the free_list");
171 HeapRegion* res = _hrm.allocate_free_region(is_old);
172 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
173 "allocated " HR_FORMAT " from secondary_free_list",
174 HR_FORMAT_PARAMS(res));
175 return res;
176 }
177
178 // Wait here until we get notified either when (a) there are no
179 // more free regions coming or (b) some regions have been moved on
180 // the secondary_free_list.
181 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
182 }
183
184 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
185 "could not allocate from secondary_free_list");
186 return NULL;
187 }
188
189 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
190 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
191 "the only time we use this to allocate a humongous region is "
192 "when we are allocating a single humongous region");
193
194 HeapRegion* res;
195 if (G1StressConcRegionFreeing) {
196 if (!_secondary_free_list.is_empty()) {
197 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
198 "forced to look at the secondary_free_list");
199 res = new_region_try_secondary_free_list(is_old);
200 if (res != NULL) {
201 return res;
202 }
203 }
204 }
205
206 res = _hrm.allocate_free_region(is_old);
207
208 if (res == NULL) {
209 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
210 "res == NULL, trying the secondary_free_list");
211 res = new_region_try_secondary_free_list(is_old);
212 }
213 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
214 // Currently, only attempts to allocate GC alloc regions set
215 // do_expand to true. So, we should only reach here during a
216 // safepoint. If this assumption changes we might have to
217 // reconsider the use of _expand_heap_after_alloc_failure.
218 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
219
220 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
221 word_size * HeapWordSize);
222
223 if (expand(word_size * HeapWordSize)) {
224 // Given that expand() succeeded in expanding the heap, and we
225 // always expand the heap by an amount aligned to the heap
226 // region size, the free list should in theory not be empty.
227 // In either case allocate_free_region() will check for NULL.
228 res = _hrm.allocate_free_region(is_old);
229 } else {
230 _expand_heap_after_alloc_failure = false;
231 }
232 }
233 return res;
234 }
235
236 HeapWord*
237 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
238 uint num_regions,
239 size_t word_size,
240 AllocationContext_t context) {
241 assert(first != G1_NO_HRM_INDEX, "pre-condition");
242 assert(is_humongous(word_size), "word_size should be humongous");
243 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
244
245 // Index of last region in the series.
246 uint last = first + num_regions - 1;
247
248 // We need to initialize the region(s) we just discovered. This is
249 // a bit tricky given that it can happen concurrently with
250 // refinement threads refining cards on these regions and
251 // potentially wanting to refine the BOT as they are scanning
252 // those cards (this can happen shortly after a cleanup; see CR
253 // 6991377). So we have to set up the region(s) carefully and in
254 // a specific order.
255
256 // The word size sum of all the regions we will allocate.
257 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
258 assert(word_size <= word_size_sum, "sanity");
259
260 // This will be the "starts humongous" region.
261 HeapRegion* first_hr = region_at(first);
262 // The header of the new object will be placed at the bottom of
263 // the first region.
264 HeapWord* new_obj = first_hr->bottom();
265 // This will be the new top of the new object.
266 HeapWord* obj_top = new_obj + word_size;
267
268 // First, we need to zero the header of the space that we will be
269 // allocating. When we update top further down, some refinement
270 // threads might try to scan the region. By zeroing the header we
271 // ensure that any thread that will try to scan the region will
272 // come across the zero klass word and bail out.
273 //
274 // NOTE: It would not have been correct to have used
275 // CollectedHeap::fill_with_object() and make the space look like
276 // an int array. The thread that is doing the allocation will
277 // later update the object header to a potentially different array
278 // type and, for a very short period of time, the klass and length
279 // fields will be inconsistent. This could cause a refinement
280 // thread to calculate the object size incorrectly.
281 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
282
283 // Next, pad out the unused tail of the last region with filler
284 // objects, for improved usage accounting.
285 // How many words we use for filler objects.
286 size_t word_fill_size = word_size_sum - word_size;
287
288 // How many words memory we "waste" which cannot hold a filler object.
289 size_t words_not_fillable = 0;
290
291 if (word_fill_size >= min_fill_size()) {
292 fill_with_objects(obj_top, word_fill_size);
293 } else if (word_fill_size > 0) {
294 // We have space to fill, but we cannot fit an object there.
295 words_not_fillable = word_fill_size;
296 word_fill_size = 0;
297 }
298
299 // We will set up the first region as "starts humongous". This
300 // will also update the BOT covering all the regions to reflect
301 // that there is a single object that starts at the bottom of the
302 // first region.
303 first_hr->set_starts_humongous(obj_top, word_fill_size);
304 first_hr->set_allocation_context(context);
305 // Then, if there are any, we will set up the "continues
306 // humongous" regions.
307 HeapRegion* hr = NULL;
308 for (uint i = first + 1; i <= last; ++i) {
309 hr = region_at(i);
310 hr->set_continues_humongous(first_hr);
311 hr->set_allocation_context(context);
312 }
313
314 // Up to this point no concurrent thread would have been able to
315 // do any scanning on any region in this series. All the top
316 // fields still point to bottom, so the intersection between
317 // [bottom,top] and [card_start,card_end] will be empty. Before we
318 // update the top fields, we'll do a storestore to make sure that
319 // no thread sees the update to top before the zeroing of the
320 // object header and the BOT initialization.
321 OrderAccess::storestore();
322
323 // Now, we will update the top fields of the "continues humongous"
324 // regions except the last one.
325 for (uint i = first; i < last; ++i) {
326 hr = region_at(i);
327 hr->set_top(hr->end());
328 }
329
330 hr = region_at(last);
331 // If we cannot fit a filler object, we must set top to the end
332 // of the humongous object, otherwise we cannot iterate the heap
333 // and the BOT will not be complete.
334 hr->set_top(hr->end() - words_not_fillable);
335
336 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
337 "obj_top should be in last region");
338
339 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
340
341 assert(words_not_fillable == 0 ||
342 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
343 "Miscalculation in humongous allocation");
344
345 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
346
347 for (uint i = first; i <= last; ++i) {
348 hr = region_at(i);
349 _humongous_set.add(hr);
350 _hr_printer.alloc(hr);
351 }
352
353 return new_obj;
354 }
355
356 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
357 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
358 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
359 }
360
361 // If could fit into free regions w/o expansion, try.
362 // Otherwise, if can expand, do so.
363 // Otherwise, if using ex regions might help, try with ex given back.
364 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
365 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
366
367 _verifier->verify_region_sets_optional();
368
369 uint first = G1_NO_HRM_INDEX;
370 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
371
372 if (obj_regions == 1) {
373 // Only one region to allocate, try to use a fast path by directly allocating
374 // from the free lists. Do not try to expand here, we will potentially do that
375 // later.
376 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
377 if (hr != NULL) {
378 first = hr->hrm_index();
379 }
380 } else {
381 // We can't allocate humongous regions spanning more than one region while
382 // cleanupComplete() is running, since some of the regions we find to be
383 // empty might not yet be added to the free list. It is not straightforward
384 // to know in which list they are on so that we can remove them. We only
385 // need to do this if we need to allocate more than one region to satisfy the
386 // current humongous allocation request. If we are only allocating one region
387 // we use the one-region region allocation code (see above), that already
388 // potentially waits for regions from the secondary free list.
389 wait_while_free_regions_coming();
390 append_secondary_free_list_if_not_empty_with_lock();
391
392 // Policy: Try only empty regions (i.e. already committed first). Maybe we
393 // are lucky enough to find some.
394 first = _hrm.find_contiguous_only_empty(obj_regions);
395 if (first != G1_NO_HRM_INDEX) {
396 _hrm.allocate_free_regions_starting_at(first, obj_regions);
397 }
398 }
399
400 if (first == G1_NO_HRM_INDEX) {
401 // Policy: We could not find enough regions for the humongous object in the
402 // free list. Look through the heap to find a mix of free and uncommitted regions.
403 // If so, try expansion.
404 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
405 if (first != G1_NO_HRM_INDEX) {
406 // We found something. Make sure these regions are committed, i.e. expand
407 // the heap. Alternatively we could do a defragmentation GC.
408 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
409 word_size * HeapWordSize);
410
411 _hrm.expand_at(first, obj_regions, workers());
412 g1_policy()->record_new_heap_size(num_regions());
413
414 #ifdef ASSERT
415 for (uint i = first; i < first + obj_regions; ++i) {
416 HeapRegion* hr = region_at(i);
417 assert(hr->is_free(), "sanity");
418 assert(hr->is_empty(), "sanity");
419 assert(is_on_master_free_list(hr), "sanity");
420 }
421 #endif
422 _hrm.allocate_free_regions_starting_at(first, obj_regions);
423 } else {
424 // Policy: Potentially trigger a defragmentation GC.
425 }
426 }
427
428 HeapWord* result = NULL;
429 if (first != G1_NO_HRM_INDEX) {
430 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
431 word_size, context);
432 assert(result != NULL, "it should always return a valid result");
433
434 // A successful humongous object allocation changes the used space
435 // information of the old generation so we need to recalculate the
436 // sizes and update the jstat counters here.
437 g1mm()->update_sizes();
438 }
439
440 _verifier->verify_region_sets_optional();
441
442 return result;
443 }
444
445 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
446 assert_heap_not_locked_and_not_at_safepoint();
447 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
448
449 return attempt_allocation(word_size);
450 }
451
452 HeapWord*
453 G1CollectedHeap::mem_allocate(size_t word_size,
454 bool* gc_overhead_limit_was_exceeded) {
455 assert_heap_not_locked_and_not_at_safepoint();
456
457 if (is_humongous(word_size)) {
458 return attempt_allocation_humongous(word_size);
459 }
460 return attempt_allocation(word_size);
461 }
462
463 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
464 AllocationContext_t context) {
465 ResourceMark rm; // For retrieving the thread names in log messages.
466
467 // Make sure you read the note in attempt_allocation_humongous().
468
469 assert_heap_not_locked_and_not_at_safepoint();
470 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
471 "be called for humongous allocation requests");
472
473 // We should only get here after the first-level allocation attempt
474 // (attempt_allocation()) failed to allocate.
475
476 // We will loop until a) we manage to successfully perform the
477 // allocation or b) we successfully schedule a collection which
478 // fails to perform the allocation. b) is the only case when we'll
479 // return NULL.
480 HeapWord* result = NULL;
481 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
482 bool should_try_gc;
483 uint gc_count_before;
484
485 {
486 MutexLockerEx x(Heap_lock);
487 result = _allocator->attempt_allocation_locked(word_size, context);
488 if (result != NULL) {
489 return result;
490 }
491
492 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
493 // This is different to when only GCLocker::needs_gc() is set: try to avoid
494 // waiting because the GCLocker is active to not wait too long.
495 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
496 // No need for an ergo message here, can_expand_young_list() does this when
497 // it returns true.
498 result = _allocator->attempt_allocation_force(word_size, context);
499 if (result != NULL) {
500 return result;
501 }
502 }
503 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
504 // the GCLocker initiated GC has been performed and then retry. This includes
505 // the case when the GC Locker is not active but has not been performed.
506 should_try_gc = !GCLocker::needs_gc();
507 // Read the GC count while still holding the Heap_lock.
508 gc_count_before = total_collections();
509 }
510
511 if (should_try_gc) {
512 bool succeeded;
513 result = do_collection_pause(word_size, gc_count_before, &succeeded,
514 GCCause::_g1_inc_collection_pause);
515 if (result != NULL) {
516 assert(succeeded, "only way to get back a non-NULL result");
517 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
518 Thread::current()->name(), p2i(result));
519 return result;
520 }
521
522 if (succeeded) {
523 // We successfully scheduled a collection which failed to allocate. No
524 // point in trying to allocate further. We'll just return NULL.
525 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
526 SIZE_FORMAT " words", Thread::current()->name(), word_size);
527 return NULL;
528 }
529 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
530 Thread::current()->name(), word_size);
531 } else {
532 // Failed to schedule a collection.
533 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
534 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
535 SIZE_FORMAT " words", Thread::current()->name(), word_size);
536 return NULL;
537 }
538 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
539 // The GCLocker is either active or the GCLocker initiated
540 // GC has not yet been performed. Stall until it is and
541 // then retry the allocation.
542 GCLocker::stall_until_clear();
543 gclocker_retry_count += 1;
544 }
545
546 // We can reach here if we were unsuccessful in scheduling a
547 // collection (because another thread beat us to it) or if we were
548 // stalled due to the GC locker. In either can we should retry the
549 // allocation attempt in case another thread successfully
550 // performed a collection and reclaimed enough space. We do the
551 // first attempt (without holding the Heap_lock) here and the
552 // follow-on attempt will be at the start of the next loop
553 // iteration (after taking the Heap_lock).
554
555 result = _allocator->attempt_allocation(word_size, context);
556 if (result != NULL) {
557 return result;
558 }
559
560 // Give a warning if we seem to be looping forever.
561 if ((QueuedAllocationWarningCount > 0) &&
562 (try_count % QueuedAllocationWarningCount == 0)) {
563 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
564 Thread::current()->name(), try_count, word_size);
565 }
566 }
567
568 ShouldNotReachHere();
569 return NULL;
570 }
571
572 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
573 assert_at_safepoint(true /* should_be_vm_thread */);
574 if (_archive_allocator == NULL) {
575 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
576 }
577 }
578
579 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
580 // Allocations in archive regions cannot be of a size that would be considered
581 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
582 // may be different at archive-restore time.
583 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
584 }
585
586 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
587 assert_at_safepoint(true /* should_be_vm_thread */);
588 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
589 if (is_archive_alloc_too_large(word_size)) {
590 return NULL;
591 }
592 return _archive_allocator->archive_mem_allocate(word_size);
593 }
594
595 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
596 size_t end_alignment_in_bytes) {
597 assert_at_safepoint(true /* should_be_vm_thread */);
598 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
599
600 // Call complete_archive to do the real work, filling in the MemRegion
601 // array with the archive regions.
602 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
603 delete _archive_allocator;
604 _archive_allocator = NULL;
605 }
606
607 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
608 assert(ranges != NULL, "MemRegion array NULL");
609 assert(count != 0, "No MemRegions provided");
610 MemRegion reserved = _hrm.reserved();
611 for (size_t i = 0; i < count; i++) {
612 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
613 return false;
614 }
615 }
616 return true;
617 }
618
619 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
620 size_t count,
621 bool open) {
622 assert(!is_init_completed(), "Expect to be called at JVM init time");
623 assert(ranges != NULL, "MemRegion array NULL");
624 assert(count != 0, "No MemRegions provided");
625 MutexLockerEx x(Heap_lock);
626
627 MemRegion reserved = _hrm.reserved();
628 HeapWord* prev_last_addr = NULL;
629 HeapRegion* prev_last_region = NULL;
630
631 // Temporarily disable pretouching of heap pages. This interface is used
632 // when mmap'ing archived heap data in, so pre-touching is wasted.
633 FlagSetting fs(AlwaysPreTouch, false);
634
635 // Enable archive object checking used by G1MarkSweep. We have to let it know
636 // about each archive range, so that objects in those ranges aren't marked.
637 G1ArchiveAllocator::enable_archive_object_check();
638
639 // For each specified MemRegion range, allocate the corresponding G1
640 // regions and mark them as archive regions. We expect the ranges
641 // in ascending starting address order, without overlap.
642 for (size_t i = 0; i < count; i++) {
643 MemRegion curr_range = ranges[i];
644 HeapWord* start_address = curr_range.start();
645 size_t word_size = curr_range.word_size();
646 HeapWord* last_address = curr_range.last();
647 size_t commits = 0;
648
649 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
650 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
651 p2i(start_address), p2i(last_address));
652 guarantee(start_address > prev_last_addr,
653 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
654 p2i(start_address), p2i(prev_last_addr));
655 prev_last_addr = last_address;
656
657 // Check for ranges that start in the same G1 region in which the previous
658 // range ended, and adjust the start address so we don't try to allocate
659 // the same region again. If the current range is entirely within that
660 // region, skip it, just adjusting the recorded top.
661 HeapRegion* start_region = _hrm.addr_to_region(start_address);
662 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
663 start_address = start_region->end();
664 if (start_address > last_address) {
665 increase_used(word_size * HeapWordSize);
666 start_region->set_top(last_address + 1);
667 continue;
668 }
669 start_region->set_top(start_address);
670 curr_range = MemRegion(start_address, last_address + 1);
671 start_region = _hrm.addr_to_region(start_address);
672 }
673
674 // Perform the actual region allocation, exiting if it fails.
675 // Then note how much new space we have allocated.
676 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
677 return false;
678 }
679 increase_used(word_size * HeapWordSize);
680 if (commits != 0) {
681 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
682 HeapRegion::GrainWords * HeapWordSize * commits);
683
684 }
685
686 // Mark each G1 region touched by the range as archive, add it to
687 // the old set, and set the allocation context and top.
688 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
689 HeapRegion* last_region = _hrm.addr_to_region(last_address);
690 prev_last_region = last_region;
691
692 while (curr_region != NULL) {
693 assert(curr_region->is_empty() && !curr_region->is_pinned(),
694 "Region already in use (index %u)", curr_region->hrm_index());
695 curr_region->set_allocation_context(AllocationContext::system());
696 if (open) {
697 curr_region->set_open_archive();
698 } else {
699 curr_region->set_closed_archive();
700 }
701 _hr_printer.alloc(curr_region);
702 _old_set.add(curr_region);
703 HeapWord* top;
704 HeapRegion* next_region;
705 if (curr_region != last_region) {
706 top = curr_region->end();
707 next_region = _hrm.next_region_in_heap(curr_region);
708 } else {
709 top = last_address + 1;
710 next_region = NULL;
711 }
712 curr_region->set_top(top);
713 curr_region->set_first_dead(top);
714 curr_region->set_end_of_live(top);
715 curr_region = next_region;
716 }
717
718 // Notify mark-sweep of the archive
719 G1ArchiveAllocator::set_range_archive(curr_range, open);
720 }
721 return true;
722 }
723
724 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
725 assert(!is_init_completed(), "Expect to be called at JVM init time");
726 assert(ranges != NULL, "MemRegion array NULL");
727 assert(count != 0, "No MemRegions provided");
728 MemRegion reserved = _hrm.reserved();
729 HeapWord *prev_last_addr = NULL;
730 HeapRegion* prev_last_region = NULL;
731
732 // For each MemRegion, create filler objects, if needed, in the G1 regions
733 // that contain the address range. The address range actually within the
734 // MemRegion will not be modified. That is assumed to have been initialized
735 // elsewhere, probably via an mmap of archived heap data.
736 MutexLockerEx x(Heap_lock);
737 for (size_t i = 0; i < count; i++) {
738 HeapWord* start_address = ranges[i].start();
739 HeapWord* last_address = ranges[i].last();
740
741 assert(reserved.contains(start_address) && reserved.contains(last_address),
742 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
743 p2i(start_address), p2i(last_address));
744 assert(start_address > prev_last_addr,
745 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
746 p2i(start_address), p2i(prev_last_addr));
747
748 HeapRegion* start_region = _hrm.addr_to_region(start_address);
749 HeapRegion* last_region = _hrm.addr_to_region(last_address);
750 HeapWord* bottom_address = start_region->bottom();
751
752 // Check for a range beginning in the same region in which the
753 // previous one ended.
754 if (start_region == prev_last_region) {
755 bottom_address = prev_last_addr + 1;
756 }
757
758 // Verify that the regions were all marked as archive regions by
759 // alloc_archive_regions.
760 HeapRegion* curr_region = start_region;
761 while (curr_region != NULL) {
762 guarantee(curr_region->is_archive(),
763 "Expected archive region at index %u", curr_region->hrm_index());
764 if (curr_region != last_region) {
765 curr_region = _hrm.next_region_in_heap(curr_region);
766 } else {
767 curr_region = NULL;
768 }
769 }
770
771 prev_last_addr = last_address;
772 prev_last_region = last_region;
773
774 // Fill the memory below the allocated range with dummy object(s),
775 // if the region bottom does not match the range start, or if the previous
776 // range ended within the same G1 region, and there is a gap.
777 if (start_address != bottom_address) {
778 size_t fill_size = pointer_delta(start_address, bottom_address);
779 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
780 increase_used(fill_size * HeapWordSize);
781 }
782 }
783 }
784
785 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size) {
786 assert_heap_not_locked_and_not_at_safepoint();
787 assert(!is_humongous(word_size), "attempt_allocation() should not "
788 "be called for humongous allocation requests");
789
790 AllocationContext_t context = AllocationContext::current();
791 HeapWord* result = _allocator->attempt_allocation(word_size, context);
792
793 if (result == NULL) {
794 result = attempt_allocation_slow(word_size, context);
795 }
796 assert_heap_not_locked();
797 if (result != NULL) {
798 dirty_young_block(result, word_size);
799 }
800 return result;
801 }
802
803 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
804 assert(!is_init_completed(), "Expect to be called at JVM init time");
805 assert(ranges != NULL, "MemRegion array NULL");
806 assert(count != 0, "No MemRegions provided");
807 MemRegion reserved = _hrm.reserved();
808 HeapWord* prev_last_addr = NULL;
809 HeapRegion* prev_last_region = NULL;
810 size_t size_used = 0;
811 size_t uncommitted_regions = 0;
812
813 // For each Memregion, free the G1 regions that constitute it, and
814 // notify mark-sweep that the range is no longer to be considered 'archive.'
815 MutexLockerEx x(Heap_lock);
816 for (size_t i = 0; i < count; i++) {
817 HeapWord* start_address = ranges[i].start();
818 HeapWord* last_address = ranges[i].last();
819
820 assert(reserved.contains(start_address) && reserved.contains(last_address),
821 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
822 p2i(start_address), p2i(last_address));
823 assert(start_address > prev_last_addr,
824 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
825 p2i(start_address), p2i(prev_last_addr));
826 size_used += ranges[i].byte_size();
827 prev_last_addr = last_address;
828
829 HeapRegion* start_region = _hrm.addr_to_region(start_address);
830 HeapRegion* last_region = _hrm.addr_to_region(last_address);
831
832 // Check for ranges that start in the same G1 region in which the previous
833 // range ended, and adjust the start address so we don't try to free
834 // the same region again. If the current range is entirely within that
835 // region, skip it.
836 if (start_region == prev_last_region) {
837 start_address = start_region->end();
838 if (start_address > last_address) {
839 continue;
840 }
841 start_region = _hrm.addr_to_region(start_address);
842 }
843 prev_last_region = last_region;
844
845 // After verifying that each region was marked as an archive region by
846 // alloc_archive_regions, set it free and empty and uncommit it.
847 HeapRegion* curr_region = start_region;
848 while (curr_region != NULL) {
849 guarantee(curr_region->is_archive(),
850 "Expected archive region at index %u", curr_region->hrm_index());
851 uint curr_index = curr_region->hrm_index();
852 _old_set.remove(curr_region);
853 curr_region->set_free();
854 curr_region->set_top(curr_region->bottom());
855 if (curr_region != last_region) {
856 curr_region = _hrm.next_region_in_heap(curr_region);
857 } else {
858 curr_region = NULL;
859 }
860 _hrm.shrink_at(curr_index, 1);
861 uncommitted_regions++;
862 }
863
864 // Notify mark-sweep that this is no longer an archive range.
865 G1ArchiveAllocator::set_range_archive(ranges[i], false);
866 }
867
868 if (uncommitted_regions != 0) {
869 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
870 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
871 }
872 decrease_used(size_used);
873 }
874
875 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
876 ResourceMark rm; // For retrieving the thread names in log messages.
877
878 // The structure of this method has a lot of similarities to
879 // attempt_allocation_slow(). The reason these two were not merged
880 // into a single one is that such a method would require several "if
881 // allocation is not humongous do this, otherwise do that"
882 // conditional paths which would obscure its flow. In fact, an early
883 // version of this code did use a unified method which was harder to
884 // follow and, as a result, it had subtle bugs that were hard to
885 // track down. So keeping these two methods separate allows each to
886 // be more readable. It will be good to keep these two in sync as
887 // much as possible.
888
889 assert_heap_not_locked_and_not_at_safepoint();
890 assert(is_humongous(word_size), "attempt_allocation_humongous() "
891 "should only be called for humongous allocations");
892
893 // Humongous objects can exhaust the heap quickly, so we should check if we
894 // need to start a marking cycle at each humongous object allocation. We do
895 // the check before we do the actual allocation. The reason for doing it
896 // before the allocation is that we avoid having to keep track of the newly
897 // allocated memory while we do a GC.
898 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
899 word_size)) {
900 collect(GCCause::_g1_humongous_allocation);
901 }
902
903 // We will loop until a) we manage to successfully perform the
904 // allocation or b) we successfully schedule a collection which
905 // fails to perform the allocation. b) is the only case when we'll
906 // return NULL.
907 HeapWord* result = NULL;
908 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
909 bool should_try_gc;
910 uint gc_count_before;
911
912
913 {
914 MutexLockerEx x(Heap_lock);
915
916 // Given that humongous objects are not allocated in young
917 // regions, we'll first try to do the allocation without doing a
918 // collection hoping that there's enough space in the heap.
919 result = humongous_obj_allocate(word_size, AllocationContext::current());
920 if (result != NULL) {
921 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
922 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
923 return result;
924 }
925
926 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
927 // the GCLocker initiated GC has been performed and then retry. This includes
928 // the case when the GC Locker is not active but has not been performed.
929 should_try_gc = !GCLocker::needs_gc();
930 // Read the GC count while still holding the Heap_lock.
931 gc_count_before = total_collections();
932 }
933
934 if (should_try_gc) {
935 bool succeeded;
936 result = do_collection_pause(word_size, gc_count_before, &succeeded,
937 GCCause::_g1_humongous_allocation);
938 if (result != NULL) {
939 assert(succeeded, "only way to get back a non-NULL result");
940 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
941 Thread::current()->name(), p2i(result));
942 return result;
943 }
944
945 if (succeeded) {
946 // We successfully scheduled a collection which failed to allocate. No
947 // point in trying to allocate further. We'll just return NULL.
948 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
949 SIZE_FORMAT " words", Thread::current()->name(), word_size);
950 return NULL;
951 }
952 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
953 Thread::current()->name(), word_size);
954 } else {
955 // Failed to schedule a collection.
956 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
957 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
958 SIZE_FORMAT " words", Thread::current()->name(), word_size);
959 return NULL;
960 }
961 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
962 // The GCLocker is either active or the GCLocker initiated
963 // GC has not yet been performed. Stall until it is and
964 // then retry the allocation.
965 GCLocker::stall_until_clear();
966 gclocker_retry_count += 1;
967 }
968
969
970 // We can reach here if we were unsuccessful in scheduling a
971 // collection (because another thread beat us to it) or if we were
972 // stalled due to the GC locker. In either can we should retry the
973 // allocation attempt in case another thread successfully
974 // performed a collection and reclaimed enough space.
975 // Humongous object allocation always needs a lock, so we wait for the retry
976 // in the next iteration of the loop, unlike for the regular iteration case.
977 // Give a warning if we seem to be looping forever.
978
979 if ((QueuedAllocationWarningCount > 0) &&
980 (try_count % QueuedAllocationWarningCount == 0)) {
981 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
982 Thread::current()->name(), try_count, word_size);
983 }
984 }
985
986 ShouldNotReachHere();
987 return NULL;
988 }
989
990 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
991 AllocationContext_t context,
992 bool expect_null_mutator_alloc_region) {
993 assert_at_safepoint(true /* should_be_vm_thread */);
994 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
995 "the current alloc region was unexpectedly found to be non-NULL");
996
997 if (!is_humongous(word_size)) {
998 return _allocator->attempt_allocation_locked(word_size, context);
999 } else {
1000 HeapWord* result = humongous_obj_allocate(word_size, context);
1001 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1002 collector_state()->set_initiate_conc_mark_if_possible(true);
1003 }
1004 return result;
1005 }
1006
1007 ShouldNotReachHere();
1008 }
1009
1010 class PostCompactionPrinterClosure: public HeapRegionClosure {
1011 private:
1012 G1HRPrinter* _hr_printer;
1013 public:
1014 bool do_heap_region(HeapRegion* hr) {
1015 assert(!hr->is_young(), "not expecting to find young regions");
1016 _hr_printer->post_compaction(hr);
1017 return false;
1018 }
1019
1020 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1021 : _hr_printer(hr_printer) { }
1022 };
1023
1024 void G1CollectedHeap::print_hrm_post_compaction() {
1025 if (_hr_printer.is_active()) {
1026 PostCompactionPrinterClosure cl(hr_printer());
1027 heap_region_iterate(&cl);
1028 }
1029 }
1030
1031 void G1CollectedHeap::abort_concurrent_cycle() {
1032 // Note: When we have a more flexible GC logging framework that
1033 // allows us to add optional attributes to a GC log record we
1034 // could consider timing and reporting how long we wait in the
1035 // following two methods.
1036 wait_while_free_regions_coming();
1037 // If we start the compaction before the CM threads finish
1038 // scanning the root regions we might trip them over as we'll
1039 // be moving objects / updating references. So let's wait until
1040 // they are done. By telling them to abort, they should complete
1041 // early.
1042 _cm->root_regions()->abort();
1043 _cm->root_regions()->wait_until_scan_finished();
1044 append_secondary_free_list_if_not_empty_with_lock();
1045
1046 // Disable discovery and empty the discovered lists
1047 // for the CM ref processor.
1048 ref_processor_cm()->disable_discovery();
1049 ref_processor_cm()->abandon_partial_discovery();
1050 ref_processor_cm()->verify_no_references_recorded();
1051
1052 // Abandon current iterations of concurrent marking and concurrent
1053 // refinement, if any are in progress.
1054 concurrent_mark()->abort();
1055 }
1056
1057 void G1CollectedHeap::prepare_heap_for_full_collection() {
1058 // Make sure we'll choose a new allocation region afterwards.
1059 _allocator->release_mutator_alloc_region();
1060 _allocator->abandon_gc_alloc_regions();
1061 g1_rem_set()->cleanupHRRS();
1062
1063 // We may have added regions to the current incremental collection
1064 // set between the last GC or pause and now. We need to clear the
1065 // incremental collection set and then start rebuilding it afresh
1066 // after this full GC.
1067 abandon_collection_set(collection_set());
1068
1069 tear_down_region_sets(false /* free_list_only */);
1070 collector_state()->set_gcs_are_young(true);
1071 }
1072
1073 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1074 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1075 assert(used() == recalculate_used(), "Should be equal");
1076 _verifier->verify_region_sets_optional();
1077 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1078 _verifier->check_bitmaps("Full GC Start");
1079 }
1080
1081 void G1CollectedHeap::prepare_heap_for_mutators() {
1082 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1083 ClassLoaderDataGraph::purge();
1084 MetaspaceAux::verify_metrics();
1085
1086 // Prepare heap for normal collections.
1087 assert(num_free_regions() == 0, "we should not have added any free regions");
1088 rebuild_region_sets(false /* free_list_only */);
1089 abort_refinement();
1090 resize_if_necessary_after_full_collection();
1091
1092 // Rebuild the strong code root lists for each region
1093 rebuild_strong_code_roots();
1094
1095 // Start a new incremental collection set for the next pause
1096 start_new_collection_set();
1097
1098 _allocator->init_mutator_alloc_region();
1099
1100 // Post collection state updates.
1101 MetaspaceGC::compute_new_size();
1102 }
1103
1104 void G1CollectedHeap::abort_refinement() {
1105 if (_hot_card_cache->use_cache()) {
1106 _hot_card_cache->reset_hot_cache();
1107 }
1108
1109 // Discard all remembered set updates.
1110 JavaThread::dirty_card_queue_set().abandon_logs();
1111 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1112 }
1113
1114 void G1CollectedHeap::verify_after_full_collection() {
1115 check_gc_time_stamps();
1116 _hrm.verify_optional();
1117 _verifier->verify_region_sets_optional();
1118 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1119 // Clear the previous marking bitmap, if needed for bitmap verification.
1120 // Note we cannot do this when we clear the next marking bitmap in
1121 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1122 // objects marked during a full GC against the previous bitmap.
1123 // But we need to clear it before calling check_bitmaps below since
1124 // the full GC has compacted objects and updated TAMS but not updated
1125 // the prev bitmap.
1126 if (G1VerifyBitmaps) {
1127 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1128 _cm->clear_prev_bitmap(workers());
1129 }
1130 _verifier->check_bitmaps("Full GC End");
1131
1132 // At this point there should be no regions in the
1133 // entire heap tagged as young.
1134 assert(check_young_list_empty(), "young list should be empty at this point");
1135
1136 // Note: since we've just done a full GC, concurrent
1137 // marking is no longer active. Therefore we need not
1138 // re-enable reference discovery for the CM ref processor.
1139 // That will be done at the start of the next marking cycle.
1140 // We also know that the STW processor should no longer
1141 // discover any new references.
1142 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1143 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1144 ref_processor_stw()->verify_no_references_recorded();
1145 ref_processor_cm()->verify_no_references_recorded();
1146 }
1147
1148 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1149 // Post collection logging.
1150 // We should do this after we potentially resize the heap so
1151 // that all the COMMIT / UNCOMMIT events are generated before
1152 // the compaction events.
1153 print_hrm_post_compaction();
1154 heap_transition->print();
1155 print_heap_after_gc();
1156 print_heap_regions();
1157 #ifdef TRACESPINNING
1158 ParallelTaskTerminator::print_termination_counts();
1159 #endif
1160 }
1161
1162 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1163 bool clear_all_soft_refs) {
1164 assert_at_safepoint(true /* should_be_vm_thread */);
1165
1166 if (GCLocker::check_active_before_gc()) {
1167 // Full GC was not completed.
1168 return false;
1169 }
1170
1171 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1172 soft_ref_policy()->should_clear_all_soft_refs();
1173
1174 G1FullCollector collector(this, &_full_gc_memory_manager, explicit_gc, do_clear_all_soft_refs);
1175 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1176
1177 collector.prepare_collection();
1178 collector.collect();
1179 collector.complete_collection();
1180
1181 // Full collection was successfully completed.
1182 return true;
1183 }
1184
1185 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1186 // Currently, there is no facility in the do_full_collection(bool) API to notify
1187 // the caller that the collection did not succeed (e.g., because it was locked
1188 // out by the GC locker). So, right now, we'll ignore the return value.
1189 bool dummy = do_full_collection(true, /* explicit_gc */
1190 clear_all_soft_refs);
1191 }
1192
1193 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1194 // Capacity, free and used after the GC counted as full regions to
1195 // include the waste in the following calculations.
1196 const size_t capacity_after_gc = capacity();
1197 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1198
1199 // This is enforced in arguments.cpp.
1200 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1201 "otherwise the code below doesn't make sense");
1202
1203 // We don't have floating point command-line arguments
1204 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1205 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1206 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1207 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1208
1209 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1210 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1211
1212 // We have to be careful here as these two calculations can overflow
1213 // 32-bit size_t's.
1214 double used_after_gc_d = (double) used_after_gc;
1215 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1216 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1217
1218 // Let's make sure that they are both under the max heap size, which
1219 // by default will make them fit into a size_t.
1220 double desired_capacity_upper_bound = (double) max_heap_size;
1221 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1222 desired_capacity_upper_bound);
1223 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1224 desired_capacity_upper_bound);
1225
1226 // We can now safely turn them into size_t's.
1227 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1228 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1229
1230 // This assert only makes sense here, before we adjust them
1231 // with respect to the min and max heap size.
1232 assert(minimum_desired_capacity <= maximum_desired_capacity,
1233 "minimum_desired_capacity = " SIZE_FORMAT ", "
1234 "maximum_desired_capacity = " SIZE_FORMAT,
1235 minimum_desired_capacity, maximum_desired_capacity);
1236
1237 // Should not be greater than the heap max size. No need to adjust
1238 // it with respect to the heap min size as it's a lower bound (i.e.,
1239 // we'll try to make the capacity larger than it, not smaller).
1240 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1241 // Should not be less than the heap min size. No need to adjust it
1242 // with respect to the heap max size as it's an upper bound (i.e.,
1243 // we'll try to make the capacity smaller than it, not greater).
1244 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1245
1246 if (capacity_after_gc < minimum_desired_capacity) {
1247 // Don't expand unless it's significant
1248 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1249
1250 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1251 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1252 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1253 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1254
1255 expand(expand_bytes, _workers);
1256
1257 // No expansion, now see if we want to shrink
1258 } else if (capacity_after_gc > maximum_desired_capacity) {
1259 // Capacity too large, compute shrinking size
1260 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1261
1262 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1263 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1264 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1265 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1266
1267 shrink(shrink_bytes);
1268 }
1269 }
1270
1271 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1272 AllocationContext_t context,
1273 bool do_gc,
1274 bool clear_all_soft_refs,
1275 bool expect_null_mutator_alloc_region,
1276 bool* gc_succeeded) {
1277 *gc_succeeded = true;
1278 // Let's attempt the allocation first.
1279 HeapWord* result =
1280 attempt_allocation_at_safepoint(word_size,
1281 context,
1282 expect_null_mutator_alloc_region);
1283 if (result != NULL) {
1284 return result;
1285 }
1286
1287 // In a G1 heap, we're supposed to keep allocation from failing by
1288 // incremental pauses. Therefore, at least for now, we'll favor
1289 // expansion over collection. (This might change in the future if we can
1290 // do something smarter than full collection to satisfy a failed alloc.)
1291 result = expand_and_allocate(word_size, context);
1292 if (result != NULL) {
1293 return result;
1294 }
1295
1296 if (do_gc) {
1297 // Expansion didn't work, we'll try to do a Full GC.
1298 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1299 clear_all_soft_refs);
1300 }
1301
1302 return NULL;
1303 }
1304
1305 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1306 AllocationContext_t context,
1307 bool* succeeded) {
1308 assert_at_safepoint(true /* should_be_vm_thread */);
1309
1310 // Attempts to allocate followed by Full GC.
1311 HeapWord* result =
1312 satisfy_failed_allocation_helper(word_size,
1313 context,
1314 true, /* do_gc */
1315 false, /* clear_all_soft_refs */
1316 false, /* expect_null_mutator_alloc_region */
1317 succeeded);
1318
1319 if (result != NULL || !*succeeded) {
1320 return result;
1321 }
1322
1323 // Attempts to allocate followed by Full GC that will collect all soft references.
1324 result = satisfy_failed_allocation_helper(word_size,
1325 context,
1326 true, /* do_gc */
1327 true, /* clear_all_soft_refs */
1328 true, /* expect_null_mutator_alloc_region */
1329 succeeded);
1330
1331 if (result != NULL || !*succeeded) {
1332 return result;
1333 }
1334
1335 // Attempts to allocate, no GC
1336 result = satisfy_failed_allocation_helper(word_size,
1337 context,
1338 false, /* do_gc */
1339 false, /* clear_all_soft_refs */
1340 true, /* expect_null_mutator_alloc_region */
1341 succeeded);
1342
1343 if (result != NULL) {
1344 return result;
1345 }
1346
1347 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1348 "Flag should have been handled and cleared prior to this point");
1349
1350 // What else? We might try synchronous finalization later. If the total
1351 // space available is large enough for the allocation, then a more
1352 // complete compaction phase than we've tried so far might be
1353 // appropriate.
1354 return NULL;
1355 }
1356
1357 // Attempting to expand the heap sufficiently
1358 // to support an allocation of the given "word_size". If
1359 // successful, perform the allocation and return the address of the
1360 // allocated block, or else "NULL".
1361
1362 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1363 assert_at_safepoint(true /* should_be_vm_thread */);
1364
1365 _verifier->verify_region_sets_optional();
1366
1367 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1368 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1369 word_size * HeapWordSize);
1370
1371
1372 if (expand(expand_bytes, _workers)) {
1373 _hrm.verify_optional();
1374 _verifier->verify_region_sets_optional();
1375 return attempt_allocation_at_safepoint(word_size,
1376 context,
1377 false /* expect_null_mutator_alloc_region */);
1378 }
1379 return NULL;
1380 }
1381
1382 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1383 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1384 aligned_expand_bytes = align_up(aligned_expand_bytes,
1385 HeapRegion::GrainBytes);
1386
1387 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1388 expand_bytes, aligned_expand_bytes);
1389
1390 if (is_maximal_no_gc()) {
1391 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1392 return false;
1393 }
1394
1395 double expand_heap_start_time_sec = os::elapsedTime();
1396 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1397 assert(regions_to_expand > 0, "Must expand by at least one region");
1398
1399 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1400 if (expand_time_ms != NULL) {
1401 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1402 }
1403
1404 if (expanded_by > 0) {
1405 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1406 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1407 g1_policy()->record_new_heap_size(num_regions());
1408 } else {
1409 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1410
1411 // The expansion of the virtual storage space was unsuccessful.
1412 // Let's see if it was because we ran out of swap.
1413 if (G1ExitOnExpansionFailure &&
1414 _hrm.available() >= regions_to_expand) {
1415 // We had head room...
1416 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1417 }
1418 }
1419 return regions_to_expand > 0;
1420 }
1421
1422 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1423 size_t aligned_shrink_bytes =
1424 ReservedSpace::page_align_size_down(shrink_bytes);
1425 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1426 HeapRegion::GrainBytes);
1427 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1428
1429 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1430 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1431
1432
1433 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",
1434 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1435 if (num_regions_removed > 0) {
1436 g1_policy()->record_new_heap_size(num_regions());
1437 } else {
1438 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1439 }
1440 }
1441
1442 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1443 _verifier->verify_region_sets_optional();
1444
1445 // We should only reach here at the end of a Full GC which means we
1446 // should not not be holding to any GC alloc regions. The method
1447 // below will make sure of that and do any remaining clean up.
1448 _allocator->abandon_gc_alloc_regions();
1449
1450 // Instead of tearing down / rebuilding the free lists here, we
1451 // could instead use the remove_all_pending() method on free_list to
1452 // remove only the ones that we need to remove.
1453 tear_down_region_sets(true /* free_list_only */);
1454 shrink_helper(shrink_bytes);
1455 rebuild_region_sets(true /* free_list_only */);
1456
1457 _hrm.verify_optional();
1458 _verifier->verify_region_sets_optional();
1459 }
1460
1461 // Public methods.
1462
1463 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1464 CollectedHeap(),
1465 _young_gen_sampling_thread(NULL),
1466 _collector_policy(collector_policy),
1467 _soft_ref_policy(),
1468 _memory_manager("G1 Young Generation", "end of minor GC"),
1469 _full_gc_memory_manager("G1 Old Generation", "end of major GC"),
1470 _eden_pool(NULL),
1471 _survivor_pool(NULL),
1472 _old_pool(NULL),
1473 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1474 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1475 _g1_policy(create_g1_policy(_gc_timer_stw)),
1476 _collection_set(this, _g1_policy),
1477 _dirty_card_queue_set(false),
1478 _is_alive_closure_cm(this),
1479 _is_alive_closure_stw(this),
1480 _ref_processor_cm(NULL),
1481 _ref_processor_stw(NULL),
1482 _bot(NULL),
1483 _hot_card_cache(NULL),
1484 _g1_rem_set(NULL),
1485 _cr(NULL),
1486 _g1mm(NULL),
1487 _preserved_marks_set(true /* in_c_heap */),
1488 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1489 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1490 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1491 _humongous_reclaim_candidates(),
1492 _has_humongous_reclaim_candidates(false),
1493 _archive_allocator(NULL),
1494 _free_regions_coming(false),
1495 _gc_time_stamp(0),
1496 _summary_bytes_used(0),
1497 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1498 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1499 _expand_heap_after_alloc_failure(true),
1500 _old_marking_cycles_started(0),
1501 _old_marking_cycles_completed(0),
1502 _in_cset_fast_test() {
1503
1504 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1505 /* are_GC_task_threads */true,
1506 /* are_ConcurrentGC_threads */false);
1507 _workers->initialize_workers();
1508 _verifier = new G1HeapVerifier(this);
1509
1510 _allocator = new G1DefaultAllocator(this);
1511
1512 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1513
1514 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1515
1516 // Override the default _filler_array_max_size so that no humongous filler
1517 // objects are created.
1518 _filler_array_max_size = _humongous_object_threshold_in_words;
1519
1520 uint n_queues = ParallelGCThreads;
1521 _task_queues = new RefToScanQueueSet(n_queues);
1522
1523 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1524
1525 for (uint i = 0; i < n_queues; i++) {
1526 RefToScanQueue* q = new RefToScanQueue();
1527 q->initialize();
1528 _task_queues->register_queue(i, q);
1529 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1530 }
1531
1532 // Initialize the G1EvacuationFailureALot counters and flags.
1533 NOT_PRODUCT(reset_evacuation_should_fail();)
1534
1535 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1536 }
1537
1538 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1539 size_t size,
1540 size_t translation_factor) {
1541 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1542 // Allocate a new reserved space, preferring to use large pages.
1543 ReservedSpace rs(size, preferred_page_size);
1544 G1RegionToSpaceMapper* result =
1545 G1RegionToSpaceMapper::create_mapper(rs,
1546 size,
1547 rs.alignment(),
1548 HeapRegion::GrainBytes,
1549 translation_factor,
1550 mtGC);
1551
1552 os::trace_page_sizes_for_requested_size(description,
1553 size,
1554 preferred_page_size,
1555 rs.alignment(),
1556 rs.base(),
1557 rs.size());
1558
1559 return result;
1560 }
1561
1562 jint G1CollectedHeap::initialize_concurrent_refinement() {
1563 jint ecode = JNI_OK;
1564 _cr = G1ConcurrentRefine::create(&ecode);
1565 return ecode;
1566 }
1567
1568 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1569 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1570 if (_young_gen_sampling_thread->osthread() == NULL) {
1571 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1572 return JNI_ENOMEM;
1573 }
1574 return JNI_OK;
1575 }
1576
1577 jint G1CollectedHeap::initialize() {
1578 os::enable_vtime();
1579
1580 // Necessary to satisfy locking discipline assertions.
1581
1582 MutexLocker x(Heap_lock);
1583
1584 // While there are no constraints in the GC code that HeapWordSize
1585 // be any particular value, there are multiple other areas in the
1586 // system which believe this to be true (e.g. oop->object_size in some
1587 // cases incorrectly returns the size in wordSize units rather than
1588 // HeapWordSize).
1589 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1590
1591 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1592 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1593 size_t heap_alignment = collector_policy()->heap_alignment();
1594
1595 // Ensure that the sizes are properly aligned.
1596 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1597 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1598 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1599
1600 // Reserve the maximum.
1601
1602 // When compressed oops are enabled, the preferred heap base
1603 // is calculated by subtracting the requested size from the
1604 // 32Gb boundary and using the result as the base address for
1605 // heap reservation. If the requested size is not aligned to
1606 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1607 // into the ReservedHeapSpace constructor) then the actual
1608 // base of the reserved heap may end up differing from the
1609 // address that was requested (i.e. the preferred heap base).
1610 // If this happens then we could end up using a non-optimal
1611 // compressed oops mode.
1612
1613 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1614 heap_alignment);
1615
1616 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1617
1618 // Create the barrier set for the entire reserved region.
1619 G1SATBCardTableLoggingModRefBS* bs
1620 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1621 bs->initialize();
1622 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1623 set_barrier_set(bs);
1624
1625 // Create the hot card cache.
1626 _hot_card_cache = new G1HotCardCache(this);
1627
1628 // Carve out the G1 part of the heap.
1629 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1630 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1631 G1RegionToSpaceMapper* heap_storage =
1632 G1RegionToSpaceMapper::create_mapper(g1_rs,
1633 g1_rs.size(),
1634 page_size,
1635 HeapRegion::GrainBytes,
1636 1,
1637 mtJavaHeap);
1638 os::trace_page_sizes("Heap",
1639 collector_policy()->min_heap_byte_size(),
1640 max_byte_size,
1641 page_size,
1642 heap_rs.base(),
1643 heap_rs.size());
1644 heap_storage->set_mapping_changed_listener(&_listener);
1645
1646 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1647 G1RegionToSpaceMapper* bot_storage =
1648 create_aux_memory_mapper("Block Offset Table",
1649 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1650 G1BlockOffsetTable::heap_map_factor());
1651
1652 G1RegionToSpaceMapper* cardtable_storage =
1653 create_aux_memory_mapper("Card Table",
1654 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1655 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1656
1657 G1RegionToSpaceMapper* card_counts_storage =
1658 create_aux_memory_mapper("Card Counts Table",
1659 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1660 G1CardCounts::heap_map_factor());
1661
1662 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1663 G1RegionToSpaceMapper* prev_bitmap_storage =
1664 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1665 G1RegionToSpaceMapper* next_bitmap_storage =
1666 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1667
1668 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1669 g1_barrier_set()->initialize(cardtable_storage);
1670 // Do later initialization work for concurrent refinement.
1671 _hot_card_cache->initialize(card_counts_storage);
1672
1673 // 6843694 - ensure that the maximum region index can fit
1674 // in the remembered set structures.
1675 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1676 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1677
1678 // Also create a G1 rem set.
1679 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1680 _g1_rem_set->initialize(max_capacity(), max_regions());
1681
1682 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1683 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1684 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1685 "too many cards per region");
1686
1687 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1688
1689 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1690
1691 {
1692 HeapWord* start = _hrm.reserved().start();
1693 HeapWord* end = _hrm.reserved().end();
1694 size_t granularity = HeapRegion::GrainBytes;
1695
1696 _in_cset_fast_test.initialize(start, end, granularity);
1697 _humongous_reclaim_candidates.initialize(start, end, granularity);
1698 }
1699
1700 // Create the G1ConcurrentMark data structure and thread.
1701 // (Must do this late, so that "max_regions" is defined.)
1702 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1703 if (_cm == NULL || !_cm->completed_initialization()) {
1704 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1705 return JNI_ENOMEM;
1706 }
1707 _cmThread = _cm->cm_thread();
1708
1709 // Now expand into the initial heap size.
1710 if (!expand(init_byte_size, _workers)) {
1711 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1712 return JNI_ENOMEM;
1713 }
1714
1715 // Perform any initialization actions delegated to the policy.
1716 g1_policy()->init(this, &_collection_set);
1717
1718 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1719 SATB_Q_FL_lock,
1720 G1SATBProcessCompletedThreshold,
1721 Shared_SATB_Q_lock);
1722
1723 jint ecode = initialize_concurrent_refinement();
1724 if (ecode != JNI_OK) {
1725 return ecode;
1726 }
1727
1728 ecode = initialize_young_gen_sampling_thread();
1729 if (ecode != JNI_OK) {
1730 return ecode;
1731 }
1732
1733 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1734 DirtyCardQ_FL_lock,
1735 (int)concurrent_refine()->yellow_zone(),
1736 (int)concurrent_refine()->red_zone(),
1737 Shared_DirtyCardQ_lock,
1738 NULL, // fl_owner
1739 true); // init_free_ids
1740
1741 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1742 DirtyCardQ_FL_lock,
1743 -1, // never trigger processing
1744 -1, // no limit on length
1745 Shared_DirtyCardQ_lock,
1746 &JavaThread::dirty_card_queue_set());
1747
1748 // Here we allocate the dummy HeapRegion that is required by the
1749 // G1AllocRegion class.
1750 HeapRegion* dummy_region = _hrm.get_dummy_region();
1751
1752 // We'll re-use the same region whether the alloc region will
1753 // require BOT updates or not and, if it doesn't, then a non-young
1754 // region will complain that it cannot support allocations without
1755 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1756 dummy_region->set_eden();
1757 // Make sure it's full.
1758 dummy_region->set_top(dummy_region->end());
1759 G1AllocRegion::setup(this, dummy_region);
1760
1761 _allocator->init_mutator_alloc_region();
1762
1763 // Do create of the monitoring and management support so that
1764 // values in the heap have been properly initialized.
1765 _g1mm = new G1MonitoringSupport(this);
1766
1767 G1StringDedup::initialize();
1768
1769 _preserved_marks_set.init(ParallelGCThreads);
1770
1771 _collection_set.initialize(max_regions());
1772
1773 return JNI_OK;
1774 }
1775
1776 void G1CollectedHeap::initialize_serviceability() {
1777 _eden_pool = new G1EdenPool(this);
1778 _survivor_pool = new G1SurvivorPool(this);
1779 _old_pool = new G1OldGenPool(this);
1780
1781 _full_gc_memory_manager.add_pool(_eden_pool);
1782 _full_gc_memory_manager.add_pool(_survivor_pool);
1783 _full_gc_memory_manager.add_pool(_old_pool);
1784
1785 _memory_manager.add_pool(_eden_pool);
1786 _memory_manager.add_pool(_survivor_pool);
1787
1788 }
1789
1790 void G1CollectedHeap::stop() {
1791 // Stop all concurrent threads. We do this to make sure these threads
1792 // do not continue to execute and access resources (e.g. logging)
1793 // that are destroyed during shutdown.
1794 _cr->stop();
1795 _young_gen_sampling_thread->stop();
1796 _cmThread->stop();
1797 if (G1StringDedup::is_enabled()) {
1798 G1StringDedup::stop();
1799 }
1800 }
1801
1802 void G1CollectedHeap::safepoint_synchronize_begin() {
1803 SuspendibleThreadSet::synchronize();
1804 }
1805
1806 void G1CollectedHeap::safepoint_synchronize_end() {
1807 SuspendibleThreadSet::desynchronize();
1808 }
1809
1810 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1811 return HeapRegion::max_region_size();
1812 }
1813
1814 void G1CollectedHeap::post_initialize() {
1815 CollectedHeap::post_initialize();
1816 ref_processing_init();
1817 }
1818
1819 void G1CollectedHeap::ref_processing_init() {
1820 // Reference processing in G1 currently works as follows:
1821 //
1822 // * There are two reference processor instances. One is
1823 // used to record and process discovered references
1824 // during concurrent marking; the other is used to
1825 // record and process references during STW pauses
1826 // (both full and incremental).
1827 // * Both ref processors need to 'span' the entire heap as
1828 // the regions in the collection set may be dotted around.
1829 //
1830 // * For the concurrent marking ref processor:
1831 // * Reference discovery is enabled at initial marking.
1832 // * Reference discovery is disabled and the discovered
1833 // references processed etc during remarking.
1834 // * Reference discovery is MT (see below).
1835 // * Reference discovery requires a barrier (see below).
1836 // * Reference processing may or may not be MT
1837 // (depending on the value of ParallelRefProcEnabled
1838 // and ParallelGCThreads).
1839 // * A full GC disables reference discovery by the CM
1840 // ref processor and abandons any entries on it's
1841 // discovered lists.
1842 //
1843 // * For the STW processor:
1844 // * Non MT discovery is enabled at the start of a full GC.
1845 // * Processing and enqueueing during a full GC is non-MT.
1846 // * During a full GC, references are processed after marking.
1847 //
1848 // * Discovery (may or may not be MT) is enabled at the start
1849 // of an incremental evacuation pause.
1850 // * References are processed near the end of a STW evacuation pause.
1851 // * For both types of GC:
1852 // * Discovery is atomic - i.e. not concurrent.
1853 // * Reference discovery will not need a barrier.
1854
1855 MemRegion mr = reserved_region();
1856
1857 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1858
1859 // Concurrent Mark ref processor
1860 _ref_processor_cm =
1861 new ReferenceProcessor(mr, // span
1862 mt_processing,
1863 // mt processing
1864 ParallelGCThreads,
1865 // degree of mt processing
1866 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1867 // mt discovery
1868 MAX2(ParallelGCThreads, ConcGCThreads),
1869 // degree of mt discovery
1870 false,
1871 // Reference discovery is not atomic
1872 &_is_alive_closure_cm);
1873 // is alive closure
1874 // (for efficiency/performance)
1875
1876 // STW ref processor
1877 _ref_processor_stw =
1878 new ReferenceProcessor(mr, // span
1879 mt_processing,
1880 // mt processing
1881 ParallelGCThreads,
1882 // degree of mt processing
1883 (ParallelGCThreads > 1),
1884 // mt discovery
1885 ParallelGCThreads,
1886 // degree of mt discovery
1887 true,
1888 // Reference discovery is atomic
1889 &_is_alive_closure_stw);
1890 // is alive closure
1891 // (for efficiency/performance)
1892 }
1893
1894 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1895 return _collector_policy;
1896 }
1897
1898 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1899 return &_soft_ref_policy;
1900 }
1901
1902 size_t G1CollectedHeap::capacity() const {
1903 return _hrm.length() * HeapRegion::GrainBytes;
1904 }
1905
1906 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1907 return _hrm.total_free_bytes();
1908 }
1909
1910 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1911 hr->reset_gc_time_stamp();
1912 }
1913
1914 #ifndef PRODUCT
1915
1916 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1917 private:
1918 unsigned _gc_time_stamp;
1919 bool _failures;
1920
1921 public:
1922 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1923 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1924
1925 virtual bool do_heap_region(HeapRegion* hr) {
1926 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1927 if (_gc_time_stamp != region_gc_time_stamp) {
1928 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1929 region_gc_time_stamp, _gc_time_stamp);
1930 _failures = true;
1931 }
1932 return false;
1933 }
1934
1935 bool failures() { return _failures; }
1936 };
1937
1938 void G1CollectedHeap::check_gc_time_stamps() {
1939 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1940 heap_region_iterate(&cl);
1941 guarantee(!cl.failures(), "all GC time stamps should have been reset");
1942 }
1943 #endif // PRODUCT
1944
1945 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1946 _hot_card_cache->drain(cl, worker_i);
1947 }
1948
1949 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1950 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1951 size_t n_completed_buffers = 0;
1952 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1953 n_completed_buffers++;
1954 }
1955 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1956 dcqs.clear_n_completed_buffers();
1957 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1958 }
1959
1960 // Computes the sum of the storage used by the various regions.
1961 size_t G1CollectedHeap::used() const {
1962 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1963 if (_archive_allocator != NULL) {
1964 result += _archive_allocator->used();
1965 }
1966 return result;
1967 }
1968
1969 size_t G1CollectedHeap::used_unlocked() const {
1970 return _summary_bytes_used;
1971 }
1972
1973 class SumUsedClosure: public HeapRegionClosure {
1974 size_t _used;
1975 public:
1976 SumUsedClosure() : _used(0) {}
1977 bool do_heap_region(HeapRegion* r) {
1978 _used += r->used();
1979 return false;
1980 }
1981 size_t result() { return _used; }
1982 };
1983
1984 size_t G1CollectedHeap::recalculate_used() const {
1985 double recalculate_used_start = os::elapsedTime();
1986
1987 SumUsedClosure blk;
1988 heap_region_iterate(&blk);
1989
1990 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
1991 return blk.result();
1992 }
1993
1994 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1995 switch (cause) {
1996 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1997 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1998 case GCCause::_wb_conc_mark: return true;
1999 default : return false;
2000 }
2001 }
2002
2003 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2004 switch (cause) {
2005 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2006 case GCCause::_g1_humongous_allocation: return true;
2007 default: return is_user_requested_concurrent_full_gc(cause);
2008 }
2009 }
2010
2011 #ifndef PRODUCT
2012 void G1CollectedHeap::allocate_dummy_regions() {
2013 // Let's fill up most of the region
2014 size_t word_size = HeapRegion::GrainWords - 1024;
2015 // And as a result the region we'll allocate will be humongous.
2016 guarantee(is_humongous(word_size), "sanity");
2017
2018 // _filler_array_max_size is set to humongous object threshold
2019 // but temporarily change it to use CollectedHeap::fill_with_object().
2020 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2021
2022 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2023 // Let's use the existing mechanism for the allocation
2024 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2025 AllocationContext::system());
2026 if (dummy_obj != NULL) {
2027 MemRegion mr(dummy_obj, word_size);
2028 CollectedHeap::fill_with_object(mr);
2029 } else {
2030 // If we can't allocate once, we probably cannot allocate
2031 // again. Let's get out of the loop.
2032 break;
2033 }
2034 }
2035 }
2036 #endif // !PRODUCT
2037
2038 void G1CollectedHeap::increment_old_marking_cycles_started() {
2039 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2040 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2041 "Wrong marking cycle count (started: %d, completed: %d)",
2042 _old_marking_cycles_started, _old_marking_cycles_completed);
2043
2044 _old_marking_cycles_started++;
2045 }
2046
2047 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2048 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2049
2050 // We assume that if concurrent == true, then the caller is a
2051 // concurrent thread that was joined the Suspendible Thread
2052 // Set. If there's ever a cheap way to check this, we should add an
2053 // assert here.
2054
2055 // Given that this method is called at the end of a Full GC or of a
2056 // concurrent cycle, and those can be nested (i.e., a Full GC can
2057 // interrupt a concurrent cycle), the number of full collections
2058 // completed should be either one (in the case where there was no
2059 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2060 // behind the number of full collections started.
2061
2062 // This is the case for the inner caller, i.e. a Full GC.
2063 assert(concurrent ||
2064 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2065 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2066 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2067 "is inconsistent with _old_marking_cycles_completed = %u",
2068 _old_marking_cycles_started, _old_marking_cycles_completed);
2069
2070 // This is the case for the outer caller, i.e. the concurrent cycle.
2071 assert(!concurrent ||
2072 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2073 "for outer caller (concurrent cycle): "
2074 "_old_marking_cycles_started = %u "
2075 "is inconsistent with _old_marking_cycles_completed = %u",
2076 _old_marking_cycles_started, _old_marking_cycles_completed);
2077
2078 _old_marking_cycles_completed += 1;
2079
2080 // We need to clear the "in_progress" flag in the CM thread before
2081 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2082 // is set) so that if a waiter requests another System.gc() it doesn't
2083 // incorrectly see that a marking cycle is still in progress.
2084 if (concurrent) {
2085 _cmThread->set_idle();
2086 }
2087
2088 // This notify_all() will ensure that a thread that called
2089 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2090 // and it's waiting for a full GC to finish will be woken up. It is
2091 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2092 FullGCCount_lock->notify_all();
2093 }
2094
2095 void G1CollectedHeap::collect(GCCause::Cause cause) {
2096 assert_heap_not_locked();
2097
2098 uint gc_count_before;
2099 uint old_marking_count_before;
2100 uint full_gc_count_before;
2101 bool retry_gc;
2102
2103 do {
2104 retry_gc = false;
2105
2106 {
2107 MutexLocker ml(Heap_lock);
2108
2109 // Read the GC count while holding the Heap_lock
2110 gc_count_before = total_collections();
2111 full_gc_count_before = total_full_collections();
2112 old_marking_count_before = _old_marking_cycles_started;
2113 }
2114
2115 if (should_do_concurrent_full_gc(cause)) {
2116 // Schedule an initial-mark evacuation pause that will start a
2117 // concurrent cycle. We're setting word_size to 0 which means that
2118 // we are not requesting a post-GC allocation.
2119 VM_G1CollectForAllocation op(0, /* word_size */
2120 gc_count_before,
2121 cause,
2122 true, /* should_initiate_conc_mark */
2123 g1_policy()->max_pause_time_ms(),
2124 AllocationContext::current());
2125 VMThread::execute(&op);
2126 if (!op.pause_succeeded()) {
2127 if (old_marking_count_before == _old_marking_cycles_started) {
2128 retry_gc = op.should_retry_gc();
2129 } else {
2130 // A Full GC happened while we were trying to schedule the
2131 // initial-mark GC. No point in starting a new cycle given
2132 // that the whole heap was collected anyway.
2133 }
2134
2135 if (retry_gc) {
2136 if (GCLocker::is_active_and_needs_gc()) {
2137 GCLocker::stall_until_clear();
2138 }
2139 }
2140 }
2141 } else {
2142 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2143 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2144
2145 // Schedule a standard evacuation pause. We're setting word_size
2146 // to 0 which means that we are not requesting a post-GC allocation.
2147 VM_G1CollectForAllocation op(0, /* word_size */
2148 gc_count_before,
2149 cause,
2150 false, /* should_initiate_conc_mark */
2151 g1_policy()->max_pause_time_ms(),
2152 AllocationContext::current());
2153 VMThread::execute(&op);
2154 } else {
2155 // Schedule a Full GC.
2156 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2157 VMThread::execute(&op);
2158 }
2159 }
2160 } while (retry_gc);
2161 }
2162
2163 bool G1CollectedHeap::is_in(const void* p) const {
2164 if (_hrm.reserved().contains(p)) {
2165 // Given that we know that p is in the reserved space,
2166 // heap_region_containing() should successfully
2167 // return the containing region.
2168 HeapRegion* hr = heap_region_containing(p);
2169 return hr->is_in(p);
2170 } else {
2171 return false;
2172 }
2173 }
2174
2175 #ifdef ASSERT
2176 bool G1CollectedHeap::is_in_exact(const void* p) const {
2177 bool contains = reserved_region().contains(p);
2178 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2179 if (contains && available) {
2180 return true;
2181 } else {
2182 return false;
2183 }
2184 }
2185 #endif
2186
2187 // Iteration functions.
2188
2189 // Iterates an ObjectClosure over all objects within a HeapRegion.
2190
2191 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2192 ObjectClosure* _cl;
2193 public:
2194 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2195 bool do_heap_region(HeapRegion* r) {
2196 if (!r->is_continues_humongous()) {
2197 r->object_iterate(_cl);
2198 }
2199 return false;
2200 }
2201 };
2202
2203 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2204 IterateObjectClosureRegionClosure blk(cl);
2205 heap_region_iterate(&blk);
2206 }
2207
2208 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2209 _hrm.iterate(cl);
2210 }
2211
2212 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2213 HeapRegionClaimer *hrclaimer,
2214 uint worker_id) const {
2215 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2216 }
2217
2218 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2219 HeapRegionClaimer *hrclaimer) const {
2220 _hrm.par_iterate(cl, hrclaimer, 0);
2221 }
2222
2223 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2224 _collection_set.iterate(cl);
2225 }
2226
2227 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2228 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2229 }
2230
2231 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2232 HeapRegion* hr = heap_region_containing(addr);
2233 return hr->block_start(addr);
2234 }
2235
2236 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2237 HeapRegion* hr = heap_region_containing(addr);
2238 return hr->block_size(addr);
2239 }
2240
2241 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2242 HeapRegion* hr = heap_region_containing(addr);
2243 return hr->block_is_obj(addr);
2244 }
2245
2246 bool G1CollectedHeap::supports_tlab_allocation() const {
2247 return true;
2248 }
2249
2250 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2251 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2252 }
2253
2254 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2255 return _eden.length() * HeapRegion::GrainBytes;
2256 }
2257
2258 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2259 // must be equal to the humongous object limit.
2260 size_t G1CollectedHeap::max_tlab_size() const {
2261 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2262 }
2263
2264 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2265 AllocationContext_t context = AllocationContext::current();
2266 return _allocator->unsafe_max_tlab_alloc(context);
2267 }
2268
2269 size_t G1CollectedHeap::max_capacity() const {
2270 return _hrm.reserved().byte_size();
2271 }
2272
2273 jlong G1CollectedHeap::millis_since_last_gc() {
2274 // See the notes in GenCollectedHeap::millis_since_last_gc()
2275 // for more information about the implementation.
2276 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2277 _g1_policy->collection_pause_end_millis();
2278 if (ret_val < 0) {
2279 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2280 ". returning zero instead.", ret_val);
2281 return 0;
2282 }
2283 return ret_val;
2284 }
2285
2286 void G1CollectedHeap::prepare_for_verify() {
2287 _verifier->prepare_for_verify();
2288 }
2289
2290 void G1CollectedHeap::verify(VerifyOption vo) {
2291 _verifier->verify(vo);
2292 }
2293
2294 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2295 return true;
2296 }
2297
2298 const char* const* G1CollectedHeap::concurrent_phases() const {
2299 return _cmThread->concurrent_phases();
2300 }
2301
2302 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2303 return _cmThread->request_concurrent_phase(phase);
2304 }
2305
2306 class PrintRegionClosure: public HeapRegionClosure {
2307 outputStream* _st;
2308 public:
2309 PrintRegionClosure(outputStream* st) : _st(st) {}
2310 bool do_heap_region(HeapRegion* r) {
2311 r->print_on(_st);
2312 return false;
2313 }
2314 };
2315
2316 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2317 const HeapRegion* hr,
2318 const VerifyOption vo) const {
2319 switch (vo) {
2320 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2321 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2322 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2323 default: ShouldNotReachHere();
2324 }
2325 return false; // keep some compilers happy
2326 }
2327
2328 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2329 const VerifyOption vo) const {
2330 switch (vo) {
2331 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2332 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2333 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2334 default: ShouldNotReachHere();
2335 }
2336 return false; // keep some compilers happy
2337 }
2338
2339 void G1CollectedHeap::print_heap_regions() const {
2340 LogTarget(Trace, gc, heap, region) lt;
2341 if (lt.is_enabled()) {
2342 LogStream ls(lt);
2343 print_regions_on(&ls);
2344 }
2345 }
2346
2347 void G1CollectedHeap::print_on(outputStream* st) const {
2348 st->print(" %-20s", "garbage-first heap");
2349 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2350 capacity()/K, used_unlocked()/K);
2351 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2352 p2i(_hrm.reserved().start()),
2353 p2i(_hrm.reserved().end()));
2354 st->cr();
2355 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2356 uint young_regions = young_regions_count();
2357 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2358 (size_t) young_regions * HeapRegion::GrainBytes / K);
2359 uint survivor_regions = survivor_regions_count();
2360 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2361 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2362 st->cr();
2363 MetaspaceAux::print_on(st);
2364 }
2365
2366 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2367 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2368 "HS=humongous(starts), HC=humongous(continues), "
2369 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2370 "AC=allocation context, "
2371 "TAMS=top-at-mark-start (previous, next)");
2372 PrintRegionClosure blk(st);
2373 heap_region_iterate(&blk);
2374 }
2375
2376 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2377 print_on(st);
2378
2379 // Print the per-region information.
2380 print_regions_on(st);
2381 }
2382
2383 void G1CollectedHeap::print_on_error(outputStream* st) const {
2384 this->CollectedHeap::print_on_error(st);
2385
2386 if (_cm != NULL) {
2387 st->cr();
2388 _cm->print_on_error(st);
2389 }
2390 }
2391
2392 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2393 workers()->print_worker_threads_on(st);
2394 _cmThread->print_on(st);
2395 st->cr();
2396 _cm->print_worker_threads_on(st);
2397 _cr->print_threads_on(st);
2398 _young_gen_sampling_thread->print_on(st);
2399 if (G1StringDedup::is_enabled()) {
2400 G1StringDedup::print_worker_threads_on(st);
2401 }
2402 }
2403
2404 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2405 workers()->threads_do(tc);
2406 tc->do_thread(_cmThread);
2407 _cm->threads_do(tc);
2408 _cr->threads_do(tc);
2409 tc->do_thread(_young_gen_sampling_thread);
2410 if (G1StringDedup::is_enabled()) {
2411 G1StringDedup::threads_do(tc);
2412 }
2413 }
2414
2415 void G1CollectedHeap::print_tracing_info() const {
2416 g1_rem_set()->print_summary_info();
2417 concurrent_mark()->print_summary_info();
2418 }
2419
2420 #ifndef PRODUCT
2421 // Helpful for debugging RSet issues.
2422
2423 class PrintRSetsClosure : public HeapRegionClosure {
2424 private:
2425 const char* _msg;
2426 size_t _occupied_sum;
2427
2428 public:
2429 bool do_heap_region(HeapRegion* r) {
2430 HeapRegionRemSet* hrrs = r->rem_set();
2431 size_t occupied = hrrs->occupied();
2432 _occupied_sum += occupied;
2433
2434 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2435 if (occupied == 0) {
2436 tty->print_cr(" RSet is empty");
2437 } else {
2438 hrrs->print();
2439 }
2440 tty->print_cr("----------");
2441 return false;
2442 }
2443
2444 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2445 tty->cr();
2446 tty->print_cr("========================================");
2447 tty->print_cr("%s", msg);
2448 tty->cr();
2449 }
2450
2451 ~PrintRSetsClosure() {
2452 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2453 tty->print_cr("========================================");
2454 tty->cr();
2455 }
2456 };
2457
2458 void G1CollectedHeap::print_cset_rsets() {
2459 PrintRSetsClosure cl("Printing CSet RSets");
2460 collection_set_iterate(&cl);
2461 }
2462
2463 void G1CollectedHeap::print_all_rsets() {
2464 PrintRSetsClosure cl("Printing All RSets");;
2465 heap_region_iterate(&cl);
2466 }
2467 #endif // PRODUCT
2468
2469 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2470
2471 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2472 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2473 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2474
2475 size_t eden_capacity_bytes =
2476 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2477
2478 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2479 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2480 eden_capacity_bytes, survivor_used_bytes, num_regions());
2481 }
2482
2483 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2484 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2485 stats->unused(), stats->used(), stats->region_end_waste(),
2486 stats->regions_filled(), stats->direct_allocated(),
2487 stats->failure_used(), stats->failure_waste());
2488 }
2489
2490 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2491 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2492 gc_tracer->report_gc_heap_summary(when, heap_summary);
2493
2494 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2495 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2496 }
2497
2498 G1CollectedHeap* G1CollectedHeap::heap() {
2499 CollectedHeap* heap = Universe::heap();
2500 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2501 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2502 return (G1CollectedHeap*)heap;
2503 }
2504
2505 void G1CollectedHeap::gc_prologue(bool full) {
2506 // always_do_update_barrier = false;
2507 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2508
2509 // This summary needs to be printed before incrementing total collections.
2510 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2511
2512 // Update common counters.
2513 increment_total_collections(full /* full gc */);
2514 if (full) {
2515 increment_old_marking_cycles_started();
2516 reset_gc_time_stamp();
2517 } else {
2518 increment_gc_time_stamp();
2519 }
2520
2521 // Fill TLAB's and such
2522 double start = os::elapsedTime();
2523 accumulate_statistics_all_tlabs();
2524 ensure_parsability(true);
2525 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2526 }
2527
2528 void G1CollectedHeap::gc_epilogue(bool full) {
2529 // Update common counters.
2530 if (full) {
2531 // Update the number of full collections that have been completed.
2532 increment_old_marking_cycles_completed(false /* concurrent */);
2533 }
2534
2535 // We are at the end of the GC. Total collections has already been increased.
2536 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2537
2538 // FIXME: what is this about?
2539 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2540 // is set.
2541 #if COMPILER2_OR_JVMCI
2542 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2543 #endif
2544 // always_do_update_barrier = true;
2545
2546 double start = os::elapsedTime();
2547 resize_all_tlabs();
2548 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2549
2550 MemoryService::track_memory_usage();
2551 // We have just completed a GC. Update the soft reference
2552 // policy with the new heap occupancy
2553 Universe::update_heap_info_at_gc();
2554 }
2555
2556 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2557 uint gc_count_before,
2558 bool* succeeded,
2559 GCCause::Cause gc_cause) {
2560 assert_heap_not_locked_and_not_at_safepoint();
2561 VM_G1CollectForAllocation op(word_size,
2562 gc_count_before,
2563 gc_cause,
2564 false, /* should_initiate_conc_mark */
2565 g1_policy()->max_pause_time_ms(),
2566 AllocationContext::current());
2567 VMThread::execute(&op);
2568
2569 HeapWord* result = op.result();
2570 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2571 assert(result == NULL || ret_succeeded,
2572 "the result should be NULL if the VM did not succeed");
2573 *succeeded = ret_succeeded;
2574
2575 assert_heap_not_locked();
2576 return result;
2577 }
2578
2579 void
2580 G1CollectedHeap::doConcurrentMark() {
2581 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2582 if (!_cmThread->in_progress()) {
2583 _cmThread->set_started();
2584 CGC_lock->notify();
2585 }
2586 }
2587
2588 size_t G1CollectedHeap::pending_card_num() {
2589 size_t extra_cards = 0;
2590 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2591 DirtyCardQueue& dcq = curr->dirty_card_queue();
2592 extra_cards += dcq.size();
2593 }
2594 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2595 size_t buffer_size = dcqs.buffer_size();
2596 size_t buffer_num = dcqs.completed_buffers_num();
2597
2598 return buffer_size * buffer_num + extra_cards;
2599 }
2600
2601 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2602 private:
2603 size_t _total_humongous;
2604 size_t _candidate_humongous;
2605
2606 DirtyCardQueue _dcq;
2607
2608 // We don't nominate objects with many remembered set entries, on
2609 // the assumption that such objects are likely still live.
2610 bool is_remset_small(HeapRegion* region) const {
2611 HeapRegionRemSet* const rset = region->rem_set();
2612 return G1EagerReclaimHumongousObjectsWithStaleRefs
2613 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2614 : rset->is_empty();
2615 }
2616
2617 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2618 assert(region->is_starts_humongous(), "Must start a humongous object");
2619
2620 oop obj = oop(region->bottom());
2621
2622 // Dead objects cannot be eager reclaim candidates. Due to class
2623 // unloading it is unsafe to query their classes so we return early.
2624 if (heap->is_obj_dead(obj, region)) {
2625 return false;
2626 }
2627
2628 // Candidate selection must satisfy the following constraints
2629 // while concurrent marking is in progress:
2630 //
2631 // * In order to maintain SATB invariants, an object must not be
2632 // reclaimed if it was allocated before the start of marking and
2633 // has not had its references scanned. Such an object must have
2634 // its references (including type metadata) scanned to ensure no
2635 // live objects are missed by the marking process. Objects
2636 // allocated after the start of concurrent marking don't need to
2637 // be scanned.
2638 //
2639 // * An object must not be reclaimed if it is on the concurrent
2640 // mark stack. Objects allocated after the start of concurrent
2641 // marking are never pushed on the mark stack.
2642 //
2643 // Nominating only objects allocated after the start of concurrent
2644 // marking is sufficient to meet both constraints. This may miss
2645 // some objects that satisfy the constraints, but the marking data
2646 // structures don't support efficiently performing the needed
2647 // additional tests or scrubbing of the mark stack.
2648 //
2649 // However, we presently only nominate is_typeArray() objects.
2650 // A humongous object containing references induces remembered
2651 // set entries on other regions. In order to reclaim such an
2652 // object, those remembered sets would need to be cleaned up.
2653 //
2654 // We also treat is_typeArray() objects specially, allowing them
2655 // to be reclaimed even if allocated before the start of
2656 // concurrent mark. For this we rely on mark stack insertion to
2657 // exclude is_typeArray() objects, preventing reclaiming an object
2658 // that is in the mark stack. We also rely on the metadata for
2659 // such objects to be built-in and so ensured to be kept live.
2660 // Frequent allocation and drop of large binary blobs is an
2661 // important use case for eager reclaim, and this special handling
2662 // may reduce needed headroom.
2663
2664 return obj->is_typeArray() && is_remset_small(region);
2665 }
2666
2667 public:
2668 RegisterHumongousWithInCSetFastTestClosure()
2669 : _total_humongous(0),
2670 _candidate_humongous(0),
2671 _dcq(&JavaThread::dirty_card_queue_set()) {
2672 }
2673
2674 virtual bool do_heap_region(HeapRegion* r) {
2675 if (!r->is_starts_humongous()) {
2676 return false;
2677 }
2678 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2679
2680 bool is_candidate = humongous_region_is_candidate(g1h, r);
2681 uint rindex = r->hrm_index();
2682 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2683 if (is_candidate) {
2684 _candidate_humongous++;
2685 g1h->register_humongous_region_with_cset(rindex);
2686 // Is_candidate already filters out humongous object with large remembered sets.
2687 // If we have a humongous object with a few remembered sets, we simply flush these
2688 // remembered set entries into the DCQS. That will result in automatic
2689 // re-evaluation of their remembered set entries during the following evacuation
2690 // phase.
2691 if (!r->rem_set()->is_empty()) {
2692 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2693 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2694 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2695 HeapRegionRemSetIterator hrrs(r->rem_set());
2696 size_t card_index;
2697 while (hrrs.has_next(card_index)) {
2698 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2699 // The remembered set might contain references to already freed
2700 // regions. Filter out such entries to avoid failing card table
2701 // verification.
2702 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2703 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2704 *card_ptr = CardTableModRefBS::dirty_card_val();
2705 _dcq.enqueue(card_ptr);
2706 }
2707 }
2708 }
2709 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2710 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2711 hrrs.n_yielded(), r->rem_set()->occupied());
2712 r->rem_set()->clear_locked();
2713 }
2714 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2715 }
2716 _total_humongous++;
2717
2718 return false;
2719 }
2720
2721 size_t total_humongous() const { return _total_humongous; }
2722 size_t candidate_humongous() const { return _candidate_humongous; }
2723
2724 void flush_rem_set_entries() { _dcq.flush(); }
2725 };
2726
2727 void G1CollectedHeap::register_humongous_regions_with_cset() {
2728 if (!G1EagerReclaimHumongousObjects) {
2729 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2730 return;
2731 }
2732 double time = os::elapsed_counter();
2733
2734 // Collect reclaim candidate information and register candidates with cset.
2735 RegisterHumongousWithInCSetFastTestClosure cl;
2736 heap_region_iterate(&cl);
2737
2738 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2739 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2740 cl.total_humongous(),
2741 cl.candidate_humongous());
2742 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2743
2744 // Finally flush all remembered set entries to re-check into the global DCQS.
2745 cl.flush_rem_set_entries();
2746 }
2747
2748 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2749 public:
2750 bool do_heap_region(HeapRegion* hr) {
2751 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2752 hr->verify_rem_set();
2753 }
2754 return false;
2755 }
2756 };
2757
2758 uint G1CollectedHeap::num_task_queues() const {
2759 return _task_queues->size();
2760 }
2761
2762 #if TASKQUEUE_STATS
2763 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2764 st->print_raw_cr("GC Task Stats");
2765 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2766 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2767 }
2768
2769 void G1CollectedHeap::print_taskqueue_stats() const {
2770 if (!log_is_enabled(Trace, gc, task, stats)) {
2771 return;
2772 }
2773 Log(gc, task, stats) log;
2774 ResourceMark rm;
2775 LogStream ls(log.trace());
2776 outputStream* st = &ls;
2777
2778 print_taskqueue_stats_hdr(st);
2779
2780 TaskQueueStats totals;
2781 const uint n = num_task_queues();
2782 for (uint i = 0; i < n; ++i) {
2783 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2784 totals += task_queue(i)->stats;
2785 }
2786 st->print_raw("tot "); totals.print(st); st->cr();
2787
2788 DEBUG_ONLY(totals.verify());
2789 }
2790
2791 void G1CollectedHeap::reset_taskqueue_stats() {
2792 const uint n = num_task_queues();
2793 for (uint i = 0; i < n; ++i) {
2794 task_queue(i)->stats.reset();
2795 }
2796 }
2797 #endif // TASKQUEUE_STATS
2798
2799 void G1CollectedHeap::wait_for_root_region_scanning() {
2800 double scan_wait_start = os::elapsedTime();
2801 // We have to wait until the CM threads finish scanning the
2802 // root regions as it's the only way to ensure that all the
2803 // objects on them have been correctly scanned before we start
2804 // moving them during the GC.
2805 bool waited = _cm->root_regions()->wait_until_scan_finished();
2806 double wait_time_ms = 0.0;
2807 if (waited) {
2808 double scan_wait_end = os::elapsedTime();
2809 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2810 }
2811 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2812 }
2813
2814 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2815 private:
2816 G1HRPrinter* _hr_printer;
2817 public:
2818 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2819
2820 virtual bool do_heap_region(HeapRegion* r) {
2821 _hr_printer->cset(r);
2822 return false;
2823 }
2824 };
2825
2826 void G1CollectedHeap::start_new_collection_set() {
2827 collection_set()->start_incremental_building();
2828
2829 clear_cset_fast_test();
2830
2831 guarantee(_eden.length() == 0, "eden should have been cleared");
2832 g1_policy()->transfer_survivors_to_cset(survivor());
2833 }
2834
2835 bool
2836 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2837 assert_at_safepoint(true /* should_be_vm_thread */);
2838 guarantee(!is_gc_active(), "collection is not reentrant");
2839
2840 if (GCLocker::check_active_before_gc()) {
2841 return false;
2842 }
2843
2844 _gc_timer_stw->register_gc_start();
2845
2846 GCIdMark gc_id_mark;
2847 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2848
2849 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2850 ResourceMark rm;
2851
2852 g1_policy()->note_gc_start();
2853
2854 wait_for_root_region_scanning();
2855
2856 print_heap_before_gc();
2857 print_heap_regions();
2858 trace_heap_before_gc(_gc_tracer_stw);
2859
2860 _verifier->verify_region_sets_optional();
2861 _verifier->verify_dirty_young_regions();
2862
2863 // We should not be doing initial mark unless the conc mark thread is running
2864 if (!_cmThread->should_terminate()) {
2865 // This call will decide whether this pause is an initial-mark
2866 // pause. If it is, during_initial_mark_pause() will return true
2867 // for the duration of this pause.
2868 g1_policy()->decide_on_conc_mark_initiation();
2869 }
2870
2871 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2872 assert(!collector_state()->during_initial_mark_pause() ||
2873 collector_state()->gcs_are_young(), "sanity");
2874
2875 // We also do not allow mixed GCs during marking.
2876 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2877
2878 // Record whether this pause is an initial mark. When the current
2879 // thread has completed its logging output and it's safe to signal
2880 // the CM thread, the flag's value in the policy has been reset.
2881 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2882
2883 // Inner scope for scope based logging, timers, and stats collection
2884 {
2885 EvacuationInfo evacuation_info;
2886
2887 if (collector_state()->during_initial_mark_pause()) {
2888 // We are about to start a marking cycle, so we increment the
2889 // full collection counter.
2890 increment_old_marking_cycles_started();
2891 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2892 }
2893
2894 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2895
2896 GCTraceCPUTime tcpu;
2897
2898 G1HeapVerifier::G1VerifyType verify_type;
2899 FormatBuffer<> gc_string("Pause ");
2900 if (collector_state()->during_initial_mark_pause()) {
2901 gc_string.append("Initial Mark");
2902 verify_type = G1HeapVerifier::G1VerifyInitialMark;
2903 } else if (collector_state()->gcs_are_young()) {
2904 gc_string.append("Young");
2905 verify_type = G1HeapVerifier::G1VerifyYoungOnly;
2906 } else {
2907 gc_string.append("Mixed");
2908 verify_type = G1HeapVerifier::G1VerifyMixed;
2909 }
2910 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2911
2912 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2913 workers()->active_workers(),
2914 Threads::number_of_non_daemon_threads());
2915 workers()->update_active_workers(active_workers);
2916 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2917
2918 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2919 TraceMemoryManagerStats tms(&_memory_manager, gc_cause());
2920
2921 // If the secondary_free_list is not empty, append it to the
2922 // free_list. No need to wait for the cleanup operation to finish;
2923 // the region allocation code will check the secondary_free_list
2924 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2925 // set, skip this step so that the region allocation code has to
2926 // get entries from the secondary_free_list.
2927 if (!G1StressConcRegionFreeing) {
2928 append_secondary_free_list_if_not_empty_with_lock();
2929 }
2930
2931 G1HeapTransition heap_transition(this);
2932 size_t heap_used_bytes_before_gc = used();
2933
2934 // Don't dynamically change the number of GC threads this early. A value of
2935 // 0 is used to indicate serial work. When parallel work is done,
2936 // it will be set.
2937
2938 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2939 IsGCActiveMark x;
2940
2941 gc_prologue(false);
2942
2943 if (VerifyRememberedSets) {
2944 log_info(gc, verify)("[Verifying RemSets before GC]");
2945 VerifyRegionRemSetClosure v_cl;
2946 heap_region_iterate(&v_cl);
2947 }
2948
2949 _verifier->verify_before_gc(verify_type);
2950
2951 _verifier->check_bitmaps("GC Start");
2952
2953 #if COMPILER2_OR_JVMCI
2954 DerivedPointerTable::clear();
2955 #endif
2956
2957 // Please see comment in g1CollectedHeap.hpp and
2958 // G1CollectedHeap::ref_processing_init() to see how
2959 // reference processing currently works in G1.
2960
2961 // Enable discovery in the STW reference processor
2962 if (g1_policy()->should_process_references()) {
2963 ref_processor_stw()->enable_discovery();
2964 } else {
2965 ref_processor_stw()->disable_discovery();
2966 }
2967
2968 {
2969 // We want to temporarily turn off discovery by the
2970 // CM ref processor, if necessary, and turn it back on
2971 // on again later if we do. Using a scoped
2972 // NoRefDiscovery object will do this.
2973 NoRefDiscovery no_cm_discovery(ref_processor_cm());
2974
2975 // Forget the current alloc region (we might even choose it to be part
2976 // of the collection set!).
2977 _allocator->release_mutator_alloc_region();
2978
2979 // This timing is only used by the ergonomics to handle our pause target.
2980 // It is unclear why this should not include the full pause. We will
2981 // investigate this in CR 7178365.
2982 //
2983 // Preserving the old comment here if that helps the investigation:
2984 //
2985 // The elapsed time induced by the start time below deliberately elides
2986 // the possible verification above.
2987 double sample_start_time_sec = os::elapsedTime();
2988
2989 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2990
2991 if (collector_state()->during_initial_mark_pause()) {
2992 concurrent_mark()->checkpoint_roots_initial_pre();
2993 }
2994
2995 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2996
2997 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2998
2999 // Make sure the remembered sets are up to date. This needs to be
3000 // done before register_humongous_regions_with_cset(), because the
3001 // remembered sets are used there to choose eager reclaim candidates.
3002 // If the remembered sets are not up to date we might miss some
3003 // entries that need to be handled.
3004 g1_rem_set()->cleanupHRRS();
3005
3006 register_humongous_regions_with_cset();
3007
3008 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3009
3010 // We call this after finalize_cset() to
3011 // ensure that the CSet has been finalized.
3012 _cm->verify_no_cset_oops();
3013
3014 if (_hr_printer.is_active()) {
3015 G1PrintCollectionSetClosure cl(&_hr_printer);
3016 _collection_set.iterate(&cl);
3017 }
3018
3019 // Initialize the GC alloc regions.
3020 _allocator->init_gc_alloc_regions(evacuation_info);
3021
3022 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3023 pre_evacuate_collection_set();
3024
3025 // Actually do the work...
3026 evacuate_collection_set(evacuation_info, &per_thread_states);
3027
3028 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3029
3030 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3031 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3032
3033 eagerly_reclaim_humongous_regions();
3034
3035 record_obj_copy_mem_stats();
3036 _survivor_evac_stats.adjust_desired_plab_sz();
3037 _old_evac_stats.adjust_desired_plab_sz();
3038
3039 double start = os::elapsedTime();
3040 start_new_collection_set();
3041 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3042
3043 if (evacuation_failed()) {
3044 set_used(recalculate_used());
3045 if (_archive_allocator != NULL) {
3046 _archive_allocator->clear_used();
3047 }
3048 for (uint i = 0; i < ParallelGCThreads; i++) {
3049 if (_evacuation_failed_info_array[i].has_failed()) {
3050 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3051 }
3052 }
3053 } else {
3054 // The "used" of the the collection set have already been subtracted
3055 // when they were freed. Add in the bytes evacuated.
3056 increase_used(g1_policy()->bytes_copied_during_gc());
3057 }
3058
3059 if (collector_state()->during_initial_mark_pause()) {
3060 // We have to do this before we notify the CM threads that
3061 // they can start working to make sure that all the
3062 // appropriate initialization is done on the CM object.
3063 concurrent_mark()->checkpoint_roots_initial_post();
3064 collector_state()->set_mark_in_progress(true);
3065 // Note that we don't actually trigger the CM thread at
3066 // this point. We do that later when we're sure that
3067 // the current thread has completed its logging output.
3068 }
3069
3070 allocate_dummy_regions();
3071
3072 _allocator->init_mutator_alloc_region();
3073
3074 {
3075 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3076 if (expand_bytes > 0) {
3077 size_t bytes_before = capacity();
3078 // No need for an ergo logging here,
3079 // expansion_amount() does this when it returns a value > 0.
3080 double expand_ms;
3081 if (!expand(expand_bytes, _workers, &expand_ms)) {
3082 // We failed to expand the heap. Cannot do anything about it.
3083 }
3084 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3085 }
3086 }
3087
3088 // We redo the verification but now wrt to the new CSet which
3089 // has just got initialized after the previous CSet was freed.
3090 _cm->verify_no_cset_oops();
3091
3092 // This timing is only used by the ergonomics to handle our pause target.
3093 // It is unclear why this should not include the full pause. We will
3094 // investigate this in CR 7178365.
3095 double sample_end_time_sec = os::elapsedTime();
3096 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3097 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3098 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3099
3100 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3101 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3102
3103 if (VerifyRememberedSets) {
3104 log_info(gc, verify)("[Verifying RemSets after GC]");
3105 VerifyRegionRemSetClosure v_cl;
3106 heap_region_iterate(&v_cl);
3107 }
3108
3109 _verifier->verify_after_gc(verify_type);
3110 _verifier->check_bitmaps("GC End");
3111
3112 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3113 ref_processor_stw()->verify_no_references_recorded();
3114
3115 // CM reference discovery will be re-enabled if necessary.
3116 }
3117
3118 #ifdef TRACESPINNING
3119 ParallelTaskTerminator::print_termination_counts();
3120 #endif
3121
3122 gc_epilogue(false);
3123 }
3124
3125 // Print the remainder of the GC log output.
3126 if (evacuation_failed()) {
3127 log_info(gc)("To-space exhausted");
3128 }
3129
3130 g1_policy()->print_phases();
3131 heap_transition.print();
3132
3133 // It is not yet to safe to tell the concurrent mark to
3134 // start as we have some optional output below. We don't want the
3135 // output from the concurrent mark thread interfering with this
3136 // logging output either.
3137
3138 _hrm.verify_optional();
3139 _verifier->verify_region_sets_optional();
3140
3141 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3142 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3143
3144 print_heap_after_gc();
3145 print_heap_regions();
3146 trace_heap_after_gc(_gc_tracer_stw);
3147
3148 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3149 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3150 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3151 // before any GC notifications are raised.
3152 g1mm()->update_sizes();
3153
3154 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3155 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3156 _gc_timer_stw->register_gc_end();
3157 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3158 }
3159 // It should now be safe to tell the concurrent mark thread to start
3160 // without its logging output interfering with the logging output
3161 // that came from the pause.
3162
3163 if (should_start_conc_mark) {
3164 // CAUTION: after the doConcurrentMark() call below,
3165 // the concurrent marking thread(s) could be running
3166 // concurrently with us. Make sure that anything after
3167 // this point does not assume that we are the only GC thread
3168 // running. Note: of course, the actual marking work will
3169 // not start until the safepoint itself is released in
3170 // SuspendibleThreadSet::desynchronize().
3171 doConcurrentMark();
3172 }
3173
3174 return true;
3175 }
3176
3177 void G1CollectedHeap::remove_self_forwarding_pointers() {
3178 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3179 workers()->run_task(&rsfp_task);
3180 }
3181
3182 void G1CollectedHeap::restore_after_evac_failure() {
3183 double remove_self_forwards_start = os::elapsedTime();
3184
3185 remove_self_forwarding_pointers();
3186 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3187 _preserved_marks_set.restore(&task_executor);
3188
3189 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3190 }
3191
3192 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3193 if (!_evacuation_failed) {
3194 _evacuation_failed = true;
3195 }
3196
3197 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3198 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3199 }
3200
3201 bool G1ParEvacuateFollowersClosure::offer_termination() {
3202 G1ParScanThreadState* const pss = par_scan_state();
3203 start_term_time();
3204 const bool res = terminator()->offer_termination();
3205 end_term_time();
3206 return res;
3207 }
3208
3209 void G1ParEvacuateFollowersClosure::do_void() {
3210 G1ParScanThreadState* const pss = par_scan_state();
3211 pss->trim_queue();
3212 do {
3213 pss->steal_and_trim_queue(queues());
3214 } while (!offer_termination());
3215 }
3216
3217 class G1ParTask : public AbstractGangTask {
3218 protected:
3219 G1CollectedHeap* _g1h;
3220 G1ParScanThreadStateSet* _pss;
3221 RefToScanQueueSet* _queues;
3222 G1RootProcessor* _root_processor;
3223 ParallelTaskTerminator _terminator;
3224 uint _n_workers;
3225
3226 public:
3227 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3228 : AbstractGangTask("G1 collection"),
3229 _g1h(g1h),
3230 _pss(per_thread_states),
3231 _queues(task_queues),
3232 _root_processor(root_processor),
3233 _terminator(n_workers, _queues),
3234 _n_workers(n_workers)
3235 {}
3236
3237 void work(uint worker_id) {
3238 if (worker_id >= _n_workers) return; // no work needed this round
3239
3240 double start_sec = os::elapsedTime();
3241 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3242
3243 {
3244 ResourceMark rm;
3245 HandleMark hm;
3246
3247 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3248
3249 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3250 pss->set_ref_processor(rp);
3251
3252 double start_strong_roots_sec = os::elapsedTime();
3253
3254 _root_processor->evacuate_roots(pss->closures(), worker_id);
3255
3256 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3257 // treating the nmethods visited to act as roots for concurrent marking.
3258 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3259 // objects copied by the current evacuation.
3260 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3261 pss->closures()->weak_codeblobs(),
3262 worker_id);
3263
3264 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3265
3266 double term_sec = 0.0;
3267 size_t evac_term_attempts = 0;
3268 {
3269 double start = os::elapsedTime();
3270 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3271 evac.do_void();
3272
3273 evac_term_attempts = evac.term_attempts();
3274 term_sec = evac.term_time();
3275 double elapsed_sec = os::elapsedTime() - start;
3276 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3277 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3278 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3279 }
3280
3281 assert(pss->queue_is_empty(), "should be empty");
3282
3283 if (log_is_enabled(Debug, gc, task, stats)) {
3284 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3285 size_t lab_waste;
3286 size_t lab_undo_waste;
3287 pss->waste(lab_waste, lab_undo_waste);
3288 _g1h->print_termination_stats(worker_id,
3289 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3290 strong_roots_sec * 1000.0, /* strong roots time */
3291 term_sec * 1000.0, /* evac term time */
3292 evac_term_attempts, /* evac term attempts */
3293 lab_waste, /* alloc buffer waste */
3294 lab_undo_waste /* undo waste */
3295 );
3296 }
3297
3298 // Close the inner scope so that the ResourceMark and HandleMark
3299 // destructors are executed here and are included as part of the
3300 // "GC Worker Time".
3301 }
3302 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3303 }
3304 };
3305
3306 void G1CollectedHeap::print_termination_stats_hdr() {
3307 log_debug(gc, task, stats)("GC Termination Stats");
3308 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3309 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3310 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3311 }
3312
3313 void G1CollectedHeap::print_termination_stats(uint worker_id,
3314 double elapsed_ms,
3315 double strong_roots_ms,
3316 double term_ms,
3317 size_t term_attempts,
3318 size_t alloc_buffer_waste,
3319 size_t undo_waste) const {
3320 log_debug(gc, task, stats)
3321 ("%3d %9.2f %9.2f %6.2f "
3322 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3323 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3324 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3325 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3326 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3327 alloc_buffer_waste * HeapWordSize / K,
3328 undo_waste * HeapWordSize / K);
3329 }
3330
3331 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3332 private:
3333 BoolObjectClosure* _is_alive;
3334 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3335
3336 int _initial_string_table_size;
3337 int _initial_symbol_table_size;
3338
3339 bool _process_strings;
3340 int _strings_processed;
3341 int _strings_removed;
3342
3343 bool _process_symbols;
3344 int _symbols_processed;
3345 int _symbols_removed;
3346
3347 bool _process_string_dedup;
3348
3349 public:
3350 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3351 AbstractGangTask("String/Symbol Unlinking"),
3352 _is_alive(is_alive),
3353 _dedup_closure(is_alive, NULL, false),
3354 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3355 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3356 _process_string_dedup(process_string_dedup) {
3357
3358 _initial_string_table_size = StringTable::the_table()->table_size();
3359 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3360 if (process_strings) {
3361 StringTable::clear_parallel_claimed_index();
3362 }
3363 if (process_symbols) {
3364 SymbolTable::clear_parallel_claimed_index();
3365 }
3366 }
3367
3368 ~G1StringAndSymbolCleaningTask() {
3369 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3370 "claim value %d after unlink less than initial string table size %d",
3371 StringTable::parallel_claimed_index(), _initial_string_table_size);
3372 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3373 "claim value %d after unlink less than initial symbol table size %d",
3374 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3375
3376 log_info(gc, stringtable)(
3377 "Cleaned string and symbol table, "
3378 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3379 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3380 strings_processed(), strings_removed(),
3381 symbols_processed(), symbols_removed());
3382 }
3383
3384 void work(uint worker_id) {
3385 int strings_processed = 0;
3386 int strings_removed = 0;
3387 int symbols_processed = 0;
3388 int symbols_removed = 0;
3389 if (_process_strings) {
3390 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3391 Atomic::add(strings_processed, &_strings_processed);
3392 Atomic::add(strings_removed, &_strings_removed);
3393 }
3394 if (_process_symbols) {
3395 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3396 Atomic::add(symbols_processed, &_symbols_processed);
3397 Atomic::add(symbols_removed, &_symbols_removed);
3398 }
3399 if (_process_string_dedup) {
3400 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3401 }
3402 }
3403
3404 size_t strings_processed() const { return (size_t)_strings_processed; }
3405 size_t strings_removed() const { return (size_t)_strings_removed; }
3406
3407 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3408 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3409 };
3410
3411 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3412 private:
3413 static Monitor* _lock;
3414
3415 BoolObjectClosure* const _is_alive;
3416 const bool _unloading_occurred;
3417 const uint _num_workers;
3418
3419 // Variables used to claim nmethods.
3420 CompiledMethod* _first_nmethod;
3421 CompiledMethod* volatile _claimed_nmethod;
3422
3423 // The list of nmethods that need to be processed by the second pass.
3424 CompiledMethod* volatile _postponed_list;
3425 volatile uint _num_entered_barrier;
3426
3427 public:
3428 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3429 _is_alive(is_alive),
3430 _unloading_occurred(unloading_occurred),
3431 _num_workers(num_workers),
3432 _first_nmethod(NULL),
3433 _claimed_nmethod(NULL),
3434 _postponed_list(NULL),
3435 _num_entered_barrier(0)
3436 {
3437 CompiledMethod::increase_unloading_clock();
3438 // Get first alive nmethod
3439 CompiledMethodIterator iter = CompiledMethodIterator();
3440 if(iter.next_alive()) {
3441 _first_nmethod = iter.method();
3442 }
3443 _claimed_nmethod = _first_nmethod;
3444 }
3445
3446 ~G1CodeCacheUnloadingTask() {
3447 CodeCache::verify_clean_inline_caches();
3448
3449 CodeCache::set_needs_cache_clean(false);
3450 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3451
3452 CodeCache::verify_icholder_relocations();
3453 }
3454
3455 private:
3456 void add_to_postponed_list(CompiledMethod* nm) {
3457 CompiledMethod* old;
3458 do {
3459 old = _postponed_list;
3460 nm->set_unloading_next(old);
3461 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3462 }
3463
3464 void clean_nmethod(CompiledMethod* nm) {
3465 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3466
3467 if (postponed) {
3468 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3469 add_to_postponed_list(nm);
3470 }
3471
3472 // Mark that this thread has been cleaned/unloaded.
3473 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3474 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3475 }
3476
3477 void clean_nmethod_postponed(CompiledMethod* nm) {
3478 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3479 }
3480
3481 static const int MaxClaimNmethods = 16;
3482
3483 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3484 CompiledMethod* first;
3485 CompiledMethodIterator last;
3486
3487 do {
3488 *num_claimed_nmethods = 0;
3489
3490 first = _claimed_nmethod;
3491 last = CompiledMethodIterator(first);
3492
3493 if (first != NULL) {
3494
3495 for (int i = 0; i < MaxClaimNmethods; i++) {
3496 if (!last.next_alive()) {
3497 break;
3498 }
3499 claimed_nmethods[i] = last.method();
3500 (*num_claimed_nmethods)++;
3501 }
3502 }
3503
3504 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3505 }
3506
3507 CompiledMethod* claim_postponed_nmethod() {
3508 CompiledMethod* claim;
3509 CompiledMethod* next;
3510
3511 do {
3512 claim = _postponed_list;
3513 if (claim == NULL) {
3514 return NULL;
3515 }
3516
3517 next = claim->unloading_next();
3518
3519 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3520
3521 return claim;
3522 }
3523
3524 public:
3525 // Mark that we're done with the first pass of nmethod cleaning.
3526 void barrier_mark(uint worker_id) {
3527 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3528 _num_entered_barrier++;
3529 if (_num_entered_barrier == _num_workers) {
3530 ml.notify_all();
3531 }
3532 }
3533
3534 // See if we have to wait for the other workers to
3535 // finish their first-pass nmethod cleaning work.
3536 void barrier_wait(uint worker_id) {
3537 if (_num_entered_barrier < _num_workers) {
3538 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3539 while (_num_entered_barrier < _num_workers) {
3540 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3541 }
3542 }
3543 }
3544
3545 // Cleaning and unloading of nmethods. Some work has to be postponed
3546 // to the second pass, when we know which nmethods survive.
3547 void work_first_pass(uint worker_id) {
3548 // The first nmethods is claimed by the first worker.
3549 if (worker_id == 0 && _first_nmethod != NULL) {
3550 clean_nmethod(_first_nmethod);
3551 _first_nmethod = NULL;
3552 }
3553
3554 int num_claimed_nmethods;
3555 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3556
3557 while (true) {
3558 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3559
3560 if (num_claimed_nmethods == 0) {
3561 break;
3562 }
3563
3564 for (int i = 0; i < num_claimed_nmethods; i++) {
3565 clean_nmethod(claimed_nmethods[i]);
3566 }
3567 }
3568 }
3569
3570 void work_second_pass(uint worker_id) {
3571 CompiledMethod* nm;
3572 // Take care of postponed nmethods.
3573 while ((nm = claim_postponed_nmethod()) != NULL) {
3574 clean_nmethod_postponed(nm);
3575 }
3576 }
3577 };
3578
3579 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3580
3581 class G1KlassCleaningTask : public StackObj {
3582 BoolObjectClosure* _is_alive;
3583 volatile int _clean_klass_tree_claimed;
3584 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3585
3586 public:
3587 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3588 _is_alive(is_alive),
3589 _clean_klass_tree_claimed(0),
3590 _klass_iterator() {
3591 }
3592
3593 private:
3594 bool claim_clean_klass_tree_task() {
3595 if (_clean_klass_tree_claimed) {
3596 return false;
3597 }
3598
3599 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3600 }
3601
3602 InstanceKlass* claim_next_klass() {
3603 Klass* klass;
3604 do {
3605 klass =_klass_iterator.next_klass();
3606 } while (klass != NULL && !klass->is_instance_klass());
3607
3608 // this can be null so don't call InstanceKlass::cast
3609 return static_cast<InstanceKlass*>(klass);
3610 }
3611
3612 public:
3613
3614 void clean_klass(InstanceKlass* ik) {
3615 ik->clean_weak_instanceklass_links(_is_alive);
3616 }
3617
3618 void work() {
3619 ResourceMark rm;
3620
3621 // One worker will clean the subklass/sibling klass tree.
3622 if (claim_clean_klass_tree_task()) {
3623 Klass::clean_subklass_tree(_is_alive);
3624 }
3625
3626 // All workers will help cleaning the classes,
3627 InstanceKlass* klass;
3628 while ((klass = claim_next_klass()) != NULL) {
3629 clean_klass(klass);
3630 }
3631 }
3632 };
3633
3634 class G1ResolvedMethodCleaningTask : public StackObj {
3635 BoolObjectClosure* _is_alive;
3636 volatile int _resolved_method_task_claimed;
3637 public:
3638 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3639 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3640
3641 bool claim_resolved_method_task() {
3642 if (_resolved_method_task_claimed) {
3643 return false;
3644 }
3645 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3646 }
3647
3648 // These aren't big, one thread can do it all.
3649 void work() {
3650 if (claim_resolved_method_task()) {
3651 ResolvedMethodTable::unlink(_is_alive);
3652 }
3653 }
3654 };
3655
3656
3657 // To minimize the remark pause times, the tasks below are done in parallel.
3658 class G1ParallelCleaningTask : public AbstractGangTask {
3659 private:
3660 G1StringAndSymbolCleaningTask _string_symbol_task;
3661 G1CodeCacheUnloadingTask _code_cache_task;
3662 G1KlassCleaningTask _klass_cleaning_task;
3663 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3664
3665 public:
3666 // The constructor is run in the VMThread.
3667 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3668 AbstractGangTask("Parallel Cleaning"),
3669 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3670 _code_cache_task(num_workers, is_alive, unloading_occurred),
3671 _klass_cleaning_task(is_alive),
3672 _resolved_method_cleaning_task(is_alive) {
3673 }
3674
3675 // The parallel work done by all worker threads.
3676 void work(uint worker_id) {
3677 // Do first pass of code cache cleaning.
3678 _code_cache_task.work_first_pass(worker_id);
3679
3680 // Let the threads mark that the first pass is done.
3681 _code_cache_task.barrier_mark(worker_id);
3682
3683 // Clean the Strings and Symbols.
3684 _string_symbol_task.work(worker_id);
3685
3686 // Clean unreferenced things in the ResolvedMethodTable
3687 _resolved_method_cleaning_task.work();
3688
3689 // Wait for all workers to finish the first code cache cleaning pass.
3690 _code_cache_task.barrier_wait(worker_id);
3691
3692 // Do the second code cache cleaning work, which realize on
3693 // the liveness information gathered during the first pass.
3694 _code_cache_task.work_second_pass(worker_id);
3695
3696 // Clean all klasses that were not unloaded.
3697 _klass_cleaning_task.work();
3698 }
3699 };
3700
3701
3702 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3703 bool class_unloading_occurred) {
3704 uint n_workers = workers()->active_workers();
3705
3706 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3707 workers()->run_task(&g1_unlink_task);
3708 }
3709
3710 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3711 bool process_strings,
3712 bool process_symbols,
3713 bool process_string_dedup) {
3714 if (!process_strings && !process_symbols && !process_string_dedup) {
3715 // Nothing to clean.
3716 return;
3717 }
3718
3719 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3720 workers()->run_task(&g1_unlink_task);
3721
3722 }
3723
3724 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3725 private:
3726 DirtyCardQueueSet* _queue;
3727 G1CollectedHeap* _g1h;
3728 public:
3729 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3730 _queue(queue), _g1h(g1h) { }
3731
3732 virtual void work(uint worker_id) {
3733 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3734 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3735
3736 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3737 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3738
3739 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3740 }
3741 };
3742
3743 void G1CollectedHeap::redirty_logged_cards() {
3744 double redirty_logged_cards_start = os::elapsedTime();
3745
3746 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3747 dirty_card_queue_set().reset_for_par_iteration();
3748 workers()->run_task(&redirty_task);
3749
3750 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3751 dcq.merge_bufferlists(&dirty_card_queue_set());
3752 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3753
3754 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3755 }
3756
3757 // Weak Reference Processing support
3758
3759 // An always "is_alive" closure that is used to preserve referents.
3760 // If the object is non-null then it's alive. Used in the preservation
3761 // of referent objects that are pointed to by reference objects
3762 // discovered by the CM ref processor.
3763 class G1AlwaysAliveClosure: public BoolObjectClosure {
3764 G1CollectedHeap* _g1;
3765 public:
3766 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3767 bool do_object_b(oop p) {
3768 if (p != NULL) {
3769 return true;
3770 }
3771 return false;
3772 }
3773 };
3774
3775 bool G1STWIsAliveClosure::do_object_b(oop p) {
3776 // An object is reachable if it is outside the collection set,
3777 // or is inside and copied.
3778 return !_g1->is_in_cset(p) || p->is_forwarded();
3779 }
3780
3781 // Non Copying Keep Alive closure
3782 class G1KeepAliveClosure: public OopClosure {
3783 G1CollectedHeap* _g1;
3784 public:
3785 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3786 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3787 void do_oop(oop* p) {
3788 oop obj = *p;
3789 assert(obj != NULL, "the caller should have filtered out NULL values");
3790
3791 const InCSetState cset_state = _g1->in_cset_state(obj);
3792 if (!cset_state.is_in_cset_or_humongous()) {
3793 return;
3794 }
3795 if (cset_state.is_in_cset()) {
3796 assert( obj->is_forwarded(), "invariant" );
3797 *p = obj->forwardee();
3798 } else {
3799 assert(!obj->is_forwarded(), "invariant" );
3800 assert(cset_state.is_humongous(),
3801 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3802 _g1->set_humongous_is_live(obj);
3803 }
3804 }
3805 };
3806
3807 // Copying Keep Alive closure - can be called from both
3808 // serial and parallel code as long as different worker
3809 // threads utilize different G1ParScanThreadState instances
3810 // and different queues.
3811
3812 class G1CopyingKeepAliveClosure: public OopClosure {
3813 G1CollectedHeap* _g1h;
3814 OopClosure* _copy_non_heap_obj_cl;
3815 G1ParScanThreadState* _par_scan_state;
3816
3817 public:
3818 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3819 OopClosure* non_heap_obj_cl,
3820 G1ParScanThreadState* pss):
3821 _g1h(g1h),
3822 _copy_non_heap_obj_cl(non_heap_obj_cl),
3823 _par_scan_state(pss)
3824 {}
3825
3826 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3827 virtual void do_oop( oop* p) { do_oop_work(p); }
3828
3829 template <class T> void do_oop_work(T* p) {
3830 oop obj = oopDesc::load_decode_heap_oop(p);
3831
3832 if (_g1h->is_in_cset_or_humongous(obj)) {
3833 // If the referent object has been forwarded (either copied
3834 // to a new location or to itself in the event of an
3835 // evacuation failure) then we need to update the reference
3836 // field and, if both reference and referent are in the G1
3837 // heap, update the RSet for the referent.
3838 //
3839 // If the referent has not been forwarded then we have to keep
3840 // it alive by policy. Therefore we have copy the referent.
3841 //
3842 // If the reference field is in the G1 heap then we can push
3843 // on the PSS queue. When the queue is drained (after each
3844 // phase of reference processing) the object and it's followers
3845 // will be copied, the reference field set to point to the
3846 // new location, and the RSet updated. Otherwise we need to
3847 // use the the non-heap or metadata closures directly to copy
3848 // the referent object and update the pointer, while avoiding
3849 // updating the RSet.
3850
3851 if (_g1h->is_in_g1_reserved(p)) {
3852 _par_scan_state->push_on_queue(p);
3853 } else {
3854 assert(!Metaspace::contains((const void*)p),
3855 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3856 _copy_non_heap_obj_cl->do_oop(p);
3857 }
3858 }
3859 }
3860 };
3861
3862 // Serial drain queue closure. Called as the 'complete_gc'
3863 // closure for each discovered list in some of the
3864 // reference processing phases.
3865
3866 class G1STWDrainQueueClosure: public VoidClosure {
3867 protected:
3868 G1CollectedHeap* _g1h;
3869 G1ParScanThreadState* _par_scan_state;
3870
3871 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3872
3873 public:
3874 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3875 _g1h(g1h),
3876 _par_scan_state(pss)
3877 { }
3878
3879 void do_void() {
3880 G1ParScanThreadState* const pss = par_scan_state();
3881 pss->trim_queue();
3882 }
3883 };
3884
3885 // Parallel Reference Processing closures
3886
3887 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3888 // processing during G1 evacuation pauses.
3889
3890 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3891 private:
3892 G1CollectedHeap* _g1h;
3893 G1ParScanThreadStateSet* _pss;
3894 RefToScanQueueSet* _queues;
3895 WorkGang* _workers;
3896 uint _active_workers;
3897
3898 public:
3899 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3900 G1ParScanThreadStateSet* per_thread_states,
3901 WorkGang* workers,
3902 RefToScanQueueSet *task_queues,
3903 uint n_workers) :
3904 _g1h(g1h),
3905 _pss(per_thread_states),
3906 _queues(task_queues),
3907 _workers(workers),
3908 _active_workers(n_workers)
3909 {
3910 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3911 }
3912
3913 // Executes the given task using concurrent marking worker threads.
3914 virtual void execute(ProcessTask& task);
3915 virtual void execute(EnqueueTask& task);
3916 };
3917
3918 // Gang task for possibly parallel reference processing
3919
3920 class G1STWRefProcTaskProxy: public AbstractGangTask {
3921 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3922 ProcessTask& _proc_task;
3923 G1CollectedHeap* _g1h;
3924 G1ParScanThreadStateSet* _pss;
3925 RefToScanQueueSet* _task_queues;
3926 ParallelTaskTerminator* _terminator;
3927
3928 public:
3929 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3930 G1CollectedHeap* g1h,
3931 G1ParScanThreadStateSet* per_thread_states,
3932 RefToScanQueueSet *task_queues,
3933 ParallelTaskTerminator* terminator) :
3934 AbstractGangTask("Process reference objects in parallel"),
3935 _proc_task(proc_task),
3936 _g1h(g1h),
3937 _pss(per_thread_states),
3938 _task_queues(task_queues),
3939 _terminator(terminator)
3940 {}
3941
3942 virtual void work(uint worker_id) {
3943 // The reference processing task executed by a single worker.
3944 ResourceMark rm;
3945 HandleMark hm;
3946
3947 G1STWIsAliveClosure is_alive(_g1h);
3948
3949 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3950 pss->set_ref_processor(NULL);
3951
3952 // Keep alive closure.
3953 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3954
3955 // Complete GC closure
3956 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3957
3958 // Call the reference processing task's work routine.
3959 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3960
3961 // Note we cannot assert that the refs array is empty here as not all
3962 // of the processing tasks (specifically phase2 - pp2_work) execute
3963 // the complete_gc closure (which ordinarily would drain the queue) so
3964 // the queue may not be empty.
3965 }
3966 };
3967
3968 // Driver routine for parallel reference processing.
3969 // Creates an instance of the ref processing gang
3970 // task and has the worker threads execute it.
3971 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
3972 assert(_workers != NULL, "Need parallel worker threads.");
3973
3974 ParallelTaskTerminator terminator(_active_workers, _queues);
3975 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3976
3977 _workers->run_task(&proc_task_proxy);
3978 }
3979
3980 // Gang task for parallel reference enqueueing.
3981
3982 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
3983 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
3984 EnqueueTask& _enq_task;
3985
3986 public:
3987 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
3988 AbstractGangTask("Enqueue reference objects in parallel"),
3989 _enq_task(enq_task)
3990 { }
3991
3992 virtual void work(uint worker_id) {
3993 _enq_task.work(worker_id);
3994 }
3995 };
3996
3997 // Driver routine for parallel reference enqueueing.
3998 // Creates an instance of the ref enqueueing gang
3999 // task and has the worker threads execute it.
4000
4001 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4002 assert(_workers != NULL, "Need parallel worker threads.");
4003
4004 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4005
4006 _workers->run_task(&enq_task_proxy);
4007 }
4008
4009 // End of weak reference support closures
4010
4011 // Abstract task used to preserve (i.e. copy) any referent objects
4012 // that are in the collection set and are pointed to by reference
4013 // objects discovered by the CM ref processor.
4014
4015 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4016 protected:
4017 G1CollectedHeap* _g1h;
4018 G1ParScanThreadStateSet* _pss;
4019 RefToScanQueueSet* _queues;
4020 ParallelTaskTerminator _terminator;
4021 uint _n_workers;
4022
4023 public:
4024 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4025 AbstractGangTask("ParPreserveCMReferents"),
4026 _g1h(g1h),
4027 _pss(per_thread_states),
4028 _queues(task_queues),
4029 _terminator(workers, _queues),
4030 _n_workers(workers)
4031 {
4032 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4033 }
4034
4035 void work(uint worker_id) {
4036 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4037
4038 ResourceMark rm;
4039 HandleMark hm;
4040
4041 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4042 pss->set_ref_processor(NULL);
4043 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4044
4045 // Is alive closure
4046 G1AlwaysAliveClosure always_alive(_g1h);
4047
4048 // Copying keep alive closure. Applied to referent objects that need
4049 // to be copied.
4050 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4051
4052 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4053
4054 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4055 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4056
4057 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4058 // So this must be true - but assert just in case someone decides to
4059 // change the worker ids.
4060 assert(worker_id < limit, "sanity");
4061 assert(!rp->discovery_is_atomic(), "check this code");
4062
4063 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4064 for (uint idx = worker_id; idx < limit; idx += stride) {
4065 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4066
4067 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4068 while (iter.has_next()) {
4069 // Since discovery is not atomic for the CM ref processor, we
4070 // can see some null referent objects.
4071 iter.load_ptrs(DEBUG_ONLY(true));
4072 oop ref = iter.obj();
4073
4074 // This will filter nulls.
4075 if (iter.is_referent_alive()) {
4076 iter.make_referent_alive();
4077 }
4078 iter.move_to_next();
4079 }
4080 }
4081
4082 // Drain the queue - which may cause stealing
4083 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4084 drain_queue.do_void();
4085 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4086 assert(pss->queue_is_empty(), "should be");
4087 }
4088 };
4089
4090 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4091 // Any reference objects, in the collection set, that were 'discovered'
4092 // by the CM ref processor should have already been copied (either by
4093 // applying the external root copy closure to the discovered lists, or
4094 // by following an RSet entry).
4095 //
4096 // But some of the referents, that are in the collection set, that these
4097 // reference objects point to may not have been copied: the STW ref
4098 // processor would have seen that the reference object had already
4099 // been 'discovered' and would have skipped discovering the reference,
4100 // but would not have treated the reference object as a regular oop.
4101 // As a result the copy closure would not have been applied to the
4102 // referent object.
4103 //
4104 // We need to explicitly copy these referent objects - the references
4105 // will be processed at the end of remarking.
4106 //
4107 // We also need to do this copying before we process the reference
4108 // objects discovered by the STW ref processor in case one of these
4109 // referents points to another object which is also referenced by an
4110 // object discovered by the STW ref processor.
4111 double preserve_cm_referents_time = 0.0;
4112
4113 // To avoid spawning task when there is no work to do, check that
4114 // a concurrent cycle is active and that some references have been
4115 // discovered.
4116 if (concurrent_mark()->cm_thread()->during_cycle() &&
4117 ref_processor_cm()->has_discovered_references()) {
4118 double preserve_cm_referents_start = os::elapsedTime();
4119 uint no_of_gc_workers = workers()->active_workers();
4120 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4121 per_thread_states,
4122 no_of_gc_workers,
4123 _task_queues);
4124 workers()->run_task(&keep_cm_referents);
4125 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4126 }
4127
4128 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4129 }
4130
4131 // Weak Reference processing during an evacuation pause (part 1).
4132 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4133 double ref_proc_start = os::elapsedTime();
4134
4135 ReferenceProcessor* rp = _ref_processor_stw;
4136 assert(rp->discovery_enabled(), "should have been enabled");
4137
4138 // Closure to test whether a referent is alive.
4139 G1STWIsAliveClosure is_alive(this);
4140
4141 // Even when parallel reference processing is enabled, the processing
4142 // of JNI refs is serial and performed serially by the current thread
4143 // rather than by a worker. The following PSS will be used for processing
4144 // JNI refs.
4145
4146 // Use only a single queue for this PSS.
4147 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4148 pss->set_ref_processor(NULL);
4149 assert(pss->queue_is_empty(), "pre-condition");
4150
4151 // Keep alive closure.
4152 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4153
4154 // Serial Complete GC closure
4155 G1STWDrainQueueClosure drain_queue(this, pss);
4156
4157 // Setup the soft refs policy...
4158 rp->setup_policy(false);
4159
4160 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4161
4162 ReferenceProcessorStats stats;
4163 if (!rp->processing_is_mt()) {
4164 // Serial reference processing...
4165 stats = rp->process_discovered_references(&is_alive,
4166 &keep_alive,
4167 &drain_queue,
4168 NULL,
4169 pt);
4170 } else {
4171 uint no_of_gc_workers = workers()->active_workers();
4172
4173 // Parallel reference processing
4174 assert(no_of_gc_workers <= rp->max_num_q(),
4175 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4176 no_of_gc_workers, rp->max_num_q());
4177
4178 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4179 stats = rp->process_discovered_references(&is_alive,
4180 &keep_alive,
4181 &drain_queue,
4182 &par_task_executor,
4183 pt);
4184 }
4185
4186 _gc_tracer_stw->report_gc_reference_stats(stats);
4187
4188 // We have completed copying any necessary live referent objects.
4189 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4190
4191 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4192 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4193 }
4194
4195 // Weak Reference processing during an evacuation pause (part 2).
4196 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4197 double ref_enq_start = os::elapsedTime();
4198
4199 ReferenceProcessor* rp = _ref_processor_stw;
4200 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4201
4202 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4203
4204 // Now enqueue any remaining on the discovered lists on to
4205 // the pending list.
4206 if (!rp->processing_is_mt()) {
4207 // Serial reference processing...
4208 rp->enqueue_discovered_references(NULL, pt);
4209 } else {
4210 // Parallel reference enqueueing
4211
4212 uint n_workers = workers()->active_workers();
4213
4214 assert(n_workers <= rp->max_num_q(),
4215 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4216 n_workers, rp->max_num_q());
4217
4218 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4219 rp->enqueue_discovered_references(&par_task_executor, pt);
4220 }
4221
4222 rp->verify_no_references_recorded();
4223 assert(!rp->discovery_enabled(), "should have been disabled");
4224
4225 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4226 // ensure that it is marked in the bitmap for concurrent marking to discover.
4227 if (collector_state()->during_initial_mark_pause()) {
4228 oop pll_head = Universe::reference_pending_list();
4229 if (pll_head != NULL) {
4230 _cm->mark_in_next_bitmap(pll_head);
4231 }
4232 }
4233
4234 // FIXME
4235 // CM's reference processing also cleans up the string and symbol tables.
4236 // Should we do that here also? We could, but it is a serial operation
4237 // and could significantly increase the pause time.
4238
4239 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4240 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4241 }
4242
4243 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4244 double merge_pss_time_start = os::elapsedTime();
4245 per_thread_states->flush();
4246 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4247 }
4248
4249 void G1CollectedHeap::pre_evacuate_collection_set() {
4250 _expand_heap_after_alloc_failure = true;
4251 _evacuation_failed = false;
4252
4253 // Disable the hot card cache.
4254 _hot_card_cache->reset_hot_cache_claimed_index();
4255 _hot_card_cache->set_use_cache(false);
4256
4257 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4258 _preserved_marks_set.assert_empty();
4259
4260 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4261
4262 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4263 if (collector_state()->during_initial_mark_pause()) {
4264 double start_clear_claimed_marks = os::elapsedTime();
4265
4266 ClassLoaderDataGraph::clear_claimed_marks();
4267
4268 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4269 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4270 }
4271 }
4272
4273 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4274 // Should G1EvacuationFailureALot be in effect for this GC?
4275 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4276
4277 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4278
4279 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4280
4281 double start_par_time_sec = os::elapsedTime();
4282 double end_par_time_sec;
4283
4284 {
4285 const uint n_workers = workers()->active_workers();
4286 G1RootProcessor root_processor(this, n_workers);
4287 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4288
4289 print_termination_stats_hdr();
4290
4291 workers()->run_task(&g1_par_task);
4292 end_par_time_sec = os::elapsedTime();
4293
4294 // Closing the inner scope will execute the destructor
4295 // for the G1RootProcessor object. We record the current
4296 // elapsed time before closing the scope so that time
4297 // taken for the destructor is NOT included in the
4298 // reported parallel time.
4299 }
4300
4301 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4302 phase_times->record_par_time(par_time_ms);
4303
4304 double code_root_fixup_time_ms =
4305 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4306 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4307 }
4308
4309 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4310 // Process any discovered reference objects - we have
4311 // to do this _before_ we retire the GC alloc regions
4312 // as we may have to copy some 'reachable' referent
4313 // objects (and their reachable sub-graphs) that were
4314 // not copied during the pause.
4315 if (g1_policy()->should_process_references()) {
4316 preserve_cm_referents(per_thread_states);
4317 process_discovered_references(per_thread_states);
4318 } else {
4319 ref_processor_stw()->verify_no_references_recorded();
4320 }
4321
4322 G1STWIsAliveClosure is_alive(this);
4323 G1KeepAliveClosure keep_alive(this);
4324
4325 {
4326 double start = os::elapsedTime();
4327
4328 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4329
4330 double time_ms = (os::elapsedTime() - start) * 1000.0;
4331 g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4332 }
4333
4334 if (G1StringDedup::is_enabled()) {
4335 double fixup_start = os::elapsedTime();
4336
4337 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4338
4339 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4340 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4341 }
4342
4343 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4344
4345 if (evacuation_failed()) {
4346 restore_after_evac_failure();
4347
4348 // Reset the G1EvacuationFailureALot counters and flags
4349 // Note: the values are reset only when an actual
4350 // evacuation failure occurs.
4351 NOT_PRODUCT(reset_evacuation_should_fail();)
4352 }
4353
4354 _preserved_marks_set.assert_empty();
4355
4356 // Enqueue any remaining references remaining on the STW
4357 // reference processor's discovered lists. We need to do
4358 // this after the card table is cleaned (and verified) as
4359 // the act of enqueueing entries on to the pending list
4360 // will log these updates (and dirty their associated
4361 // cards). We need these updates logged to update any
4362 // RSets.
4363 if (g1_policy()->should_process_references()) {
4364 enqueue_discovered_references(per_thread_states);
4365 } else {
4366 g1_policy()->phase_times()->record_ref_enq_time(0);
4367 }
4368
4369 _allocator->release_gc_alloc_regions(evacuation_info);
4370
4371 merge_per_thread_state_info(per_thread_states);
4372
4373 // Reset and re-enable the hot card cache.
4374 // Note the counts for the cards in the regions in the
4375 // collection set are reset when the collection set is freed.
4376 _hot_card_cache->reset_hot_cache();
4377 _hot_card_cache->set_use_cache(true);
4378
4379 purge_code_root_memory();
4380
4381 redirty_logged_cards();
4382 #if COMPILER2_OR_JVMCI
4383 double start = os::elapsedTime();
4384 DerivedPointerTable::update_pointers();
4385 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4386 #endif
4387 g1_policy()->print_age_table();
4388 }
4389
4390 void G1CollectedHeap::record_obj_copy_mem_stats() {
4391 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4392
4393 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4394 create_g1_evac_summary(&_old_evac_stats));
4395 }
4396
4397 void G1CollectedHeap::free_region(HeapRegion* hr,
4398 FreeRegionList* free_list,
4399 bool skip_remset,
4400 bool skip_hot_card_cache,
4401 bool locked) {
4402 assert(!hr->is_free(), "the region should not be free");
4403 assert(!hr->is_empty(), "the region should not be empty");
4404 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4405 assert(free_list != NULL, "pre-condition");
4406
4407 if (G1VerifyBitmaps) {
4408 MemRegion mr(hr->bottom(), hr->end());
4409 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4410 }
4411
4412 // Clear the card counts for this region.
4413 // Note: we only need to do this if the region is not young
4414 // (since we don't refine cards in young regions).
4415 if (!skip_hot_card_cache && !hr->is_young()) {
4416 _hot_card_cache->reset_card_counts(hr);
4417 }
4418 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4419 free_list->add_ordered(hr);
4420 }
4421
4422 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4423 FreeRegionList* free_list,
4424 bool skip_remset) {
4425 assert(hr->is_humongous(), "this is only for humongous regions");
4426 assert(free_list != NULL, "pre-condition");
4427 hr->clear_humongous();
4428 free_region(hr, free_list, skip_remset);
4429 }
4430
4431 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4432 const uint humongous_regions_removed) {
4433 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4434 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4435 _old_set.bulk_remove(old_regions_removed);
4436 _humongous_set.bulk_remove(humongous_regions_removed);
4437 }
4438
4439 }
4440
4441 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4442 assert(list != NULL, "list can't be null");
4443 if (!list->is_empty()) {
4444 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4445 _hrm.insert_list_into_free_list(list);
4446 }
4447 }
4448
4449 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4450 decrease_used(bytes);
4451 }
4452
4453 class G1ParScrubRemSetTask: public AbstractGangTask {
4454 protected:
4455 G1RemSet* _g1rs;
4456 HeapRegionClaimer _hrclaimer;
4457
4458 public:
4459 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4460 AbstractGangTask("G1 ScrubRS"),
4461 _g1rs(g1_rs),
4462 _hrclaimer(num_workers) {
4463 }
4464
4465 void work(uint worker_id) {
4466 _g1rs->scrub(worker_id, &_hrclaimer);
4467 }
4468 };
4469
4470 void G1CollectedHeap::scrub_rem_set() {
4471 uint num_workers = workers()->active_workers();
4472 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4473 workers()->run_task(&g1_par_scrub_rs_task);
4474 }
4475
4476 class G1FreeCollectionSetTask : public AbstractGangTask {
4477 private:
4478
4479 // Closure applied to all regions in the collection set to do work that needs to
4480 // be done serially in a single thread.
4481 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4482 private:
4483 EvacuationInfo* _evacuation_info;
4484 const size_t* _surviving_young_words;
4485
4486 // Bytes used in successfully evacuated regions before the evacuation.
4487 size_t _before_used_bytes;
4488 // Bytes used in unsucessfully evacuated regions before the evacuation
4489 size_t _after_used_bytes;
4490
4491 size_t _bytes_allocated_in_old_since_last_gc;
4492
4493 size_t _failure_used_words;
4494 size_t _failure_waste_words;
4495
4496 FreeRegionList _local_free_list;
4497 public:
4498 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4499 HeapRegionClosure(),
4500 _evacuation_info(evacuation_info),
4501 _surviving_young_words(surviving_young_words),
4502 _before_used_bytes(0),
4503 _after_used_bytes(0),
4504 _bytes_allocated_in_old_since_last_gc(0),
4505 _failure_used_words(0),
4506 _failure_waste_words(0),
4507 _local_free_list("Local Region List for CSet Freeing") {
4508 }
4509
4510 virtual bool do_heap_region(HeapRegion* r) {
4511 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4512
4513 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4514 g1h->clear_in_cset(r);
4515
4516 if (r->is_young()) {
4517 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4518 "Young index %d is wrong for region %u of type %s with %u young regions",
4519 r->young_index_in_cset(),
4520 r->hrm_index(),
4521 r->get_type_str(),
4522 g1h->collection_set()->young_region_length());
4523 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4524 r->record_surv_words_in_group(words_survived);
4525 }
4526
4527 if (!r->evacuation_failed()) {
4528 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4529 _before_used_bytes += r->used();
4530 g1h->free_region(r,
4531 &_local_free_list,
4532 true, /* skip_remset */
4533 true, /* skip_hot_card_cache */
4534 true /* locked */);
4535 } else {
4536 r->uninstall_surv_rate_group();
4537 r->set_young_index_in_cset(-1);
4538 r->set_evacuation_failed(false);
4539 // When moving a young gen region to old gen, we "allocate" that whole region
4540 // there. This is in addition to any already evacuated objects. Notify the
4541 // policy about that.
4542 // Old gen regions do not cause an additional allocation: both the objects
4543 // still in the region and the ones already moved are accounted for elsewhere.
4544 if (r->is_young()) {
4545 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4546 }
4547 // The region is now considered to be old.
4548 r->set_old();
4549 // Do some allocation statistics accounting. Regions that failed evacuation
4550 // are always made old, so there is no need to update anything in the young
4551 // gen statistics, but we need to update old gen statistics.
4552 size_t used_words = r->marked_bytes() / HeapWordSize;
4553
4554 _failure_used_words += used_words;
4555 _failure_waste_words += HeapRegion::GrainWords - used_words;
4556
4557 g1h->old_set_add(r);
4558 _after_used_bytes += r->used();
4559 }
4560 return false;
4561 }
4562
4563 void complete_work() {
4564 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4565
4566 _evacuation_info->set_regions_freed(_local_free_list.length());
4567 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4568
4569 g1h->prepend_to_freelist(&_local_free_list);
4570 g1h->decrement_summary_bytes(_before_used_bytes);
4571
4572 G1Policy* policy = g1h->g1_policy();
4573 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4574
4575 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4576 }
4577 };
4578
4579 G1CollectionSet* _collection_set;
4580 G1SerialFreeCollectionSetClosure _cl;
4581 const size_t* _surviving_young_words;
4582
4583 size_t _rs_lengths;
4584
4585 volatile jint _serial_work_claim;
4586
4587 struct WorkItem {
4588 uint region_idx;
4589 bool is_young;
4590 bool evacuation_failed;
4591
4592 WorkItem(HeapRegion* r) {
4593 region_idx = r->hrm_index();
4594 is_young = r->is_young();
4595 evacuation_failed = r->evacuation_failed();
4596 }
4597 };
4598
4599 volatile size_t _parallel_work_claim;
4600 size_t _num_work_items;
4601 WorkItem* _work_items;
4602
4603 void do_serial_work() {
4604 // Need to grab the lock to be allowed to modify the old region list.
4605 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4606 _collection_set->iterate(&_cl);
4607 }
4608
4609 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4610 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4611
4612 HeapRegion* r = g1h->region_at(region_idx);
4613 assert(!g1h->is_on_master_free_list(r), "sanity");
4614
4615 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4616
4617 if (!is_young) {
4618 g1h->_hot_card_cache->reset_card_counts(r);
4619 }
4620
4621 if (!evacuation_failed) {
4622 r->rem_set()->clear_locked();
4623 }
4624 }
4625
4626 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4627 private:
4628 size_t _cur_idx;
4629 WorkItem* _work_items;
4630 public:
4631 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4632
4633 virtual bool do_heap_region(HeapRegion* r) {
4634 _work_items[_cur_idx++] = WorkItem(r);
4635 return false;
4636 }
4637 };
4638
4639 void prepare_work() {
4640 G1PrepareFreeCollectionSetClosure cl(_work_items);
4641 _collection_set->iterate(&cl);
4642 }
4643
4644 void complete_work() {
4645 _cl.complete_work();
4646
4647 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4648 policy->record_max_rs_lengths(_rs_lengths);
4649 policy->cset_regions_freed();
4650 }
4651 public:
4652 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4653 AbstractGangTask("G1 Free Collection Set"),
4654 _cl(evacuation_info, surviving_young_words),
4655 _collection_set(collection_set),
4656 _surviving_young_words(surviving_young_words),
4657 _serial_work_claim(0),
4658 _rs_lengths(0),
4659 _parallel_work_claim(0),
4660 _num_work_items(collection_set->region_length()),
4661 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4662 prepare_work();
4663 }
4664
4665 ~G1FreeCollectionSetTask() {
4666 complete_work();
4667 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4668 }
4669
4670 // Chunk size for work distribution. The chosen value has been determined experimentally
4671 // to be a good tradeoff between overhead and achievable parallelism.
4672 static uint chunk_size() { return 32; }
4673
4674 virtual void work(uint worker_id) {
4675 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4676
4677 // Claim serial work.
4678 if (_serial_work_claim == 0) {
4679 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4680 if (value == 0) {
4681 double serial_time = os::elapsedTime();
4682 do_serial_work();
4683 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4684 }
4685 }
4686
4687 // Start parallel work.
4688 double young_time = 0.0;
4689 bool has_young_time = false;
4690 double non_young_time = 0.0;
4691 bool has_non_young_time = false;
4692
4693 while (true) {
4694 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4695 size_t cur = end - chunk_size();
4696
4697 if (cur >= _num_work_items) {
4698 break;
4699 }
4700
4701 double start_time = os::elapsedTime();
4702
4703 end = MIN2(end, _num_work_items);
4704
4705 for (; cur < end; cur++) {
4706 bool is_young = _work_items[cur].is_young;
4707
4708 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4709
4710 double end_time = os::elapsedTime();
4711 double time_taken = end_time - start_time;
4712 if (is_young) {
4713 young_time += time_taken;
4714 has_young_time = true;
4715 } else {
4716 non_young_time += time_taken;
4717 has_non_young_time = true;
4718 }
4719 start_time = end_time;
4720 }
4721 }
4722
4723 if (has_young_time) {
4724 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4725 }
4726 if (has_non_young_time) {
4727 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4728 }
4729 }
4730 };
4731
4732 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4733 _eden.clear();
4734
4735 double free_cset_start_time = os::elapsedTime();
4736
4737 {
4738 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4739 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4740
4741 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4742
4743 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4744 cl.name(),
4745 num_workers,
4746 _collection_set.region_length());
4747 workers()->run_task(&cl, num_workers);
4748 }
4749 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4750
4751 collection_set->clear();
4752 }
4753
4754 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4755 private:
4756 FreeRegionList* _free_region_list;
4757 HeapRegionSet* _proxy_set;
4758 uint _humongous_objects_reclaimed;
4759 uint _humongous_regions_reclaimed;
4760 size_t _freed_bytes;
4761 public:
4762
4763 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4764 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4765 }
4766
4767 virtual bool do_heap_region(HeapRegion* r) {
4768 if (!r->is_starts_humongous()) {
4769 return false;
4770 }
4771
4772 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4773
4774 oop obj = (oop)r->bottom();
4775 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4776
4777 // The following checks whether the humongous object is live are sufficient.
4778 // The main additional check (in addition to having a reference from the roots
4779 // or the young gen) is whether the humongous object has a remembered set entry.
4780 //
4781 // A humongous object cannot be live if there is no remembered set for it
4782 // because:
4783 // - there can be no references from within humongous starts regions referencing
4784 // the object because we never allocate other objects into them.
4785 // (I.e. there are no intra-region references that may be missed by the
4786 // remembered set)
4787 // - as soon there is a remembered set entry to the humongous starts region
4788 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4789 // until the end of a concurrent mark.
4790 //
4791 // It is not required to check whether the object has been found dead by marking
4792 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4793 // all objects allocated during that time are considered live.
4794 // SATB marking is even more conservative than the remembered set.
4795 // So if at this point in the collection there is no remembered set entry,
4796 // nobody has a reference to it.
4797 // At the start of collection we flush all refinement logs, and remembered sets
4798 // are completely up-to-date wrt to references to the humongous object.
4799 //
4800 // Other implementation considerations:
4801 // - never consider object arrays at this time because they would pose
4802 // considerable effort for cleaning up the the remembered sets. This is
4803 // required because stale remembered sets might reference locations that
4804 // are currently allocated into.
4805 uint region_idx = r->hrm_index();
4806 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4807 !r->rem_set()->is_empty()) {
4808 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",
4809 region_idx,
4810 (size_t)obj->size() * HeapWordSize,
4811 p2i(r->bottom()),
4812 r->rem_set()->occupied(),
4813 r->rem_set()->strong_code_roots_list_length(),
4814 next_bitmap->is_marked(r->bottom()),
4815 g1h->is_humongous_reclaim_candidate(region_idx),
4816 obj->is_typeArray()
4817 );
4818 return false;
4819 }
4820
4821 guarantee(obj->is_typeArray(),
4822 "Only eagerly reclaiming type arrays is supported, but the object "
4823 PTR_FORMAT " is not.", p2i(r->bottom()));
4824
4825 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",
4826 region_idx,
4827 (size_t)obj->size() * HeapWordSize,
4828 p2i(r->bottom()),
4829 r->rem_set()->occupied(),
4830 r->rem_set()->strong_code_roots_list_length(),
4831 next_bitmap->is_marked(r->bottom()),
4832 g1h->is_humongous_reclaim_candidate(region_idx),
4833 obj->is_typeArray()
4834 );
4835
4836 // Need to clear mark bit of the humongous object if already set.
4837 if (next_bitmap->is_marked(r->bottom())) {
4838 next_bitmap->clear(r->bottom());
4839 }
4840 _humongous_objects_reclaimed++;
4841 do {
4842 HeapRegion* next = g1h->next_region_in_humongous(r);
4843 _freed_bytes += r->used();
4844 r->set_containing_set(NULL);
4845 _humongous_regions_reclaimed++;
4846 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4847 r = next;
4848 } while (r != NULL);
4849
4850 return false;
4851 }
4852
4853 uint humongous_objects_reclaimed() {
4854 return _humongous_objects_reclaimed;
4855 }
4856
4857 uint humongous_regions_reclaimed() {
4858 return _humongous_regions_reclaimed;
4859 }
4860
4861 size_t bytes_freed() const {
4862 return _freed_bytes;
4863 }
4864 };
4865
4866 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4867 assert_at_safepoint(true);
4868
4869 if (!G1EagerReclaimHumongousObjects ||
4870 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4871 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4872 return;
4873 }
4874
4875 double start_time = os::elapsedTime();
4876
4877 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4878
4879 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4880 heap_region_iterate(&cl);
4881
4882 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4883
4884 G1HRPrinter* hrp = hr_printer();
4885 if (hrp->is_active()) {
4886 FreeRegionListIterator iter(&local_cleanup_list);
4887 while (iter.more_available()) {
4888 HeapRegion* hr = iter.get_next();
4889 hrp->cleanup(hr);
4890 }
4891 }
4892
4893 prepend_to_freelist(&local_cleanup_list);
4894 decrement_summary_bytes(cl.bytes_freed());
4895
4896 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4897 cl.humongous_objects_reclaimed());
4898 }
4899
4900 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4901 public:
4902 virtual bool do_heap_region(HeapRegion* r) {
4903 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4904 G1CollectedHeap::heap()->clear_in_cset(r);
4905 r->set_young_index_in_cset(-1);
4906 return false;
4907 }
4908 };
4909
4910 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4911 G1AbandonCollectionSetClosure cl;
4912 collection_set->iterate(&cl);
4913
4914 collection_set->clear();
4915 collection_set->stop_incremental_building();
4916 }
4917
4918 void G1CollectedHeap::set_free_regions_coming() {
4919 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4920
4921 assert(!free_regions_coming(), "pre-condition");
4922 _free_regions_coming = true;
4923 }
4924
4925 void G1CollectedHeap::reset_free_regions_coming() {
4926 assert(free_regions_coming(), "pre-condition");
4927
4928 {
4929 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4930 _free_regions_coming = false;
4931 SecondaryFreeList_lock->notify_all();
4932 }
4933
4934 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4935 }
4936
4937 void G1CollectedHeap::wait_while_free_regions_coming() {
4938 // Most of the time we won't have to wait, so let's do a quick test
4939 // first before we take the lock.
4940 if (!free_regions_coming()) {
4941 return;
4942 }
4943
4944 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4945
4946 {
4947 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4948 while (free_regions_coming()) {
4949 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4950 }
4951 }
4952
4953 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4954 }
4955
4956 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4957 return _allocator->is_retained_old_region(hr);
4958 }
4959
4960 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4961 _eden.add(hr);
4962 _g1_policy->set_region_eden(hr);
4963 }
4964
4965 #ifdef ASSERT
4966
4967 class NoYoungRegionsClosure: public HeapRegionClosure {
4968 private:
4969 bool _success;
4970 public:
4971 NoYoungRegionsClosure() : _success(true) { }
4972 bool do_heap_region(HeapRegion* r) {
4973 if (r->is_young()) {
4974 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4975 p2i(r->bottom()), p2i(r->end()));
4976 _success = false;
4977 }
4978 return false;
4979 }
4980 bool success() { return _success; }
4981 };
4982
4983 bool G1CollectedHeap::check_young_list_empty() {
4984 bool ret = (young_regions_count() == 0);
4985
4986 NoYoungRegionsClosure closure;
4987 heap_region_iterate(&closure);
4988 ret = ret && closure.success();
4989
4990 return ret;
4991 }
4992
4993 #endif // ASSERT
4994
4995 class TearDownRegionSetsClosure : public HeapRegionClosure {
4996 private:
4997 HeapRegionSet *_old_set;
4998
4999 public:
5000 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5001
5002 bool do_heap_region(HeapRegion* r) {
5003 if (r->is_old()) {
5004 _old_set->remove(r);
5005 } else if(r->is_young()) {
5006 r->uninstall_surv_rate_group();
5007 } else {
5008 // We ignore free regions, we'll empty the free list afterwards.
5009 // We ignore humongous regions, we're not tearing down the
5010 // humongous regions set.
5011 assert(r->is_free() || r->is_humongous(),
5012 "it cannot be another type");
5013 }
5014 return false;
5015 }
5016
5017 ~TearDownRegionSetsClosure() {
5018 assert(_old_set->is_empty(), "post-condition");
5019 }
5020 };
5021
5022 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5023 assert_at_safepoint(true /* should_be_vm_thread */);
5024
5025 if (!free_list_only) {
5026 TearDownRegionSetsClosure cl(&_old_set);
5027 heap_region_iterate(&cl);
5028
5029 // Note that emptying the _young_list is postponed and instead done as
5030 // the first step when rebuilding the regions sets again. The reason for
5031 // this is that during a full GC string deduplication needs to know if
5032 // a collected region was young or old when the full GC was initiated.
5033 }
5034 _hrm.remove_all_free_regions();
5035 }
5036
5037 void G1CollectedHeap::increase_used(size_t bytes) {
5038 _summary_bytes_used += bytes;
5039 }
5040
5041 void G1CollectedHeap::decrease_used(size_t bytes) {
5042 assert(_summary_bytes_used >= bytes,
5043 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5044 _summary_bytes_used, bytes);
5045 _summary_bytes_used -= bytes;
5046 }
5047
5048 void G1CollectedHeap::set_used(size_t bytes) {
5049 _summary_bytes_used = bytes;
5050 }
5051
5052 class RebuildRegionSetsClosure : public HeapRegionClosure {
5053 private:
5054 bool _free_list_only;
5055 HeapRegionSet* _old_set;
5056 HeapRegionManager* _hrm;
5057 size_t _total_used;
5058
5059 public:
5060 RebuildRegionSetsClosure(bool free_list_only,
5061 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5062 _free_list_only(free_list_only),
5063 _old_set(old_set), _hrm(hrm), _total_used(0) {
5064 assert(_hrm->num_free_regions() == 0, "pre-condition");
5065 if (!free_list_only) {
5066 assert(_old_set->is_empty(), "pre-condition");
5067 }
5068 }
5069
5070 bool do_heap_region(HeapRegion* r) {
5071 if (r->is_empty()) {
5072 // Add free regions to the free list
5073 r->set_free();
5074 r->set_allocation_context(AllocationContext::system());
5075 _hrm->insert_into_free_list(r);
5076 } else if (!_free_list_only) {
5077
5078 if (r->is_humongous()) {
5079 // We ignore humongous regions. We left the humongous set unchanged.
5080 } else {
5081 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5082 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5083 r->move_to_old();
5084 _old_set->add(r);
5085 }
5086 _total_used += r->used();
5087 }
5088
5089 return false;
5090 }
5091
5092 size_t total_used() {
5093 return _total_used;
5094 }
5095 };
5096
5097 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5098 assert_at_safepoint(true /* should_be_vm_thread */);
5099
5100 if (!free_list_only) {
5101 _eden.clear();
5102 _survivor.clear();
5103 }
5104
5105 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5106 heap_region_iterate(&cl);
5107
5108 if (!free_list_only) {
5109 set_used(cl.total_used());
5110 if (_archive_allocator != NULL) {
5111 _archive_allocator->clear_used();
5112 }
5113 }
5114 assert(used_unlocked() == recalculate_used(),
5115 "inconsistent used_unlocked(), "
5116 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5117 used_unlocked(), recalculate_used());
5118 }
5119
5120 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5121 HeapRegion* hr = heap_region_containing(p);
5122 return hr->is_in(p);
5123 }
5124
5125 // Methods for the mutator alloc region
5126
5127 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5128 bool force) {
5129 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5130 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5131 if (force || should_allocate) {
5132 HeapRegion* new_alloc_region = new_region(word_size,
5133 false /* is_old */,
5134 false /* do_expand */);
5135 if (new_alloc_region != NULL) {
5136 set_region_short_lived_locked(new_alloc_region);
5137 _hr_printer.alloc(new_alloc_region, !should_allocate);
5138 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5139 return new_alloc_region;
5140 }
5141 }
5142 return NULL;
5143 }
5144
5145 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5146 size_t allocated_bytes) {
5147 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5148 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5149
5150 collection_set()->add_eden_region(alloc_region);
5151 increase_used(allocated_bytes);
5152 _hr_printer.retire(alloc_region);
5153 // We update the eden sizes here, when the region is retired,
5154 // instead of when it's allocated, since this is the point that its
5155 // used space has been recored in _summary_bytes_used.
5156 g1mm()->update_eden_size();
5157 }
5158
5159 // Methods for the GC alloc regions
5160
5161 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5162 if (dest.is_old()) {
5163 return true;
5164 } else {
5165 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5166 }
5167 }
5168
5169 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5170 assert(FreeList_lock->owned_by_self(), "pre-condition");
5171
5172 if (!has_more_regions(dest)) {
5173 return NULL;
5174 }
5175
5176 const bool is_survivor = dest.is_young();
5177
5178 HeapRegion* new_alloc_region = new_region(word_size,
5179 !is_survivor,
5180 true /* do_expand */);
5181 if (new_alloc_region != NULL) {
5182 // We really only need to do this for old regions given that we
5183 // should never scan survivors. But it doesn't hurt to do it
5184 // for survivors too.
5185 new_alloc_region->record_timestamp();
5186 if (is_survivor) {
5187 new_alloc_region->set_survivor();
5188 _survivor.add(new_alloc_region);
5189 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5190 } else {
5191 new_alloc_region->set_old();
5192 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5193 }
5194 _hr_printer.alloc(new_alloc_region);
5195 bool during_im = collector_state()->during_initial_mark_pause();
5196 new_alloc_region->note_start_of_copying(during_im);
5197 return new_alloc_region;
5198 }
5199 return NULL;
5200 }
5201
5202 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5203 size_t allocated_bytes,
5204 InCSetState dest) {
5205 bool during_im = collector_state()->during_initial_mark_pause();
5206 alloc_region->note_end_of_copying(during_im);
5207 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5208 if (dest.is_old()) {
5209 _old_set.add(alloc_region);
5210 }
5211 _hr_printer.retire(alloc_region);
5212 }
5213
5214 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5215 bool expanded = false;
5216 uint index = _hrm.find_highest_free(&expanded);
5217
5218 if (index != G1_NO_HRM_INDEX) {
5219 if (expanded) {
5220 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5221 HeapRegion::GrainWords * HeapWordSize);
5222 }
5223 _hrm.allocate_free_regions_starting_at(index, 1);
5224 return region_at(index);
5225 }
5226 return NULL;
5227 }
5228
5229 // Optimized nmethod scanning
5230
5231 class RegisterNMethodOopClosure: public OopClosure {
5232 G1CollectedHeap* _g1h;
5233 nmethod* _nm;
5234
5235 template <class T> void do_oop_work(T* p) {
5236 T heap_oop = oopDesc::load_heap_oop(p);
5237 if (!oopDesc::is_null(heap_oop)) {
5238 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5239 HeapRegion* hr = _g1h->heap_region_containing(obj);
5240 assert(!hr->is_continues_humongous(),
5241 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5242 " starting at " HR_FORMAT,
5243 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5244
5245 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5246 hr->add_strong_code_root_locked(_nm);
5247 }
5248 }
5249
5250 public:
5251 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5252 _g1h(g1h), _nm(nm) {}
5253
5254 void do_oop(oop* p) { do_oop_work(p); }
5255 void do_oop(narrowOop* p) { do_oop_work(p); }
5256 };
5257
5258 class UnregisterNMethodOopClosure: public OopClosure {
5259 G1CollectedHeap* _g1h;
5260 nmethod* _nm;
5261
5262 template <class T> void do_oop_work(T* p) {
5263 T heap_oop = oopDesc::load_heap_oop(p);
5264 if (!oopDesc::is_null(heap_oop)) {
5265 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5266 HeapRegion* hr = _g1h->heap_region_containing(obj);
5267 assert(!hr->is_continues_humongous(),
5268 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5269 " starting at " HR_FORMAT,
5270 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5271
5272 hr->remove_strong_code_root(_nm);
5273 }
5274 }
5275
5276 public:
5277 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5278 _g1h(g1h), _nm(nm) {}
5279
5280 void do_oop(oop* p) { do_oop_work(p); }
5281 void do_oop(narrowOop* p) { do_oop_work(p); }
5282 };
5283
5284 // Returns true if the reference points to an object that
5285 // can move in an incremental collection.
5286 bool G1CollectedHeap::is_scavengable(oop obj) {
5287 HeapRegion* hr = heap_region_containing(obj);
5288 return !hr->is_pinned();
5289 }
5290
5291 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5292 guarantee(nm != NULL, "sanity");
5293 RegisterNMethodOopClosure reg_cl(this, nm);
5294 nm->oops_do(®_cl);
5295 }
5296
5297 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5298 guarantee(nm != NULL, "sanity");
5299 UnregisterNMethodOopClosure reg_cl(this, nm);
5300 nm->oops_do(®_cl, true);
5301 }
5302
5303 void G1CollectedHeap::purge_code_root_memory() {
5304 double purge_start = os::elapsedTime();
5305 G1CodeRootSet::purge();
5306 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5307 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5308 }
5309
5310 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5311 G1CollectedHeap* _g1h;
5312
5313 public:
5314 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5315 _g1h(g1h) {}
5316
5317 void do_code_blob(CodeBlob* cb) {
5318 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5319 if (nm == NULL) {
5320 return;
5321 }
5322
5323 if (ScavengeRootsInCode) {
5324 _g1h->register_nmethod(nm);
5325 }
5326 }
5327 };
5328
5329 void G1CollectedHeap::rebuild_strong_code_roots() {
5330 RebuildStrongCodeRootClosure blob_cl(this);
5331 CodeCache::blobs_do(&blob_cl);
5332 }
5333
5334 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5335 GrowableArray<GCMemoryManager*> memory_managers(2);
5336 memory_managers.append(&_memory_manager);
5337 memory_managers.append(&_full_gc_memory_manager);
5338 return memory_managers;
5339 }
5340
5341 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5342 GrowableArray<MemoryPool*> memory_pools(3);
5343 memory_pools.append(_eden_pool);
5344 memory_pools.append(_survivor_pool);
5345 memory_pools.append(_old_pool);
5346 return memory_pools;
5347 }