1 /*
2 * Copyright (c) 2001, 2017, 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/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectorPolicy.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1HeapSizingPolicy.hpp"
43 #include "gc/g1/g1HeapTransition.hpp"
44 #include "gc/g1/g1HeapVerifier.hpp"
45 #include "gc/g1/g1HotCardCache.hpp"
46 #include "gc/g1/g1MarkSweep.hpp"
47 #include "gc/g1/g1OopClosures.inline.hpp"
48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc/g1/g1Policy.hpp"
50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
51 #include "gc/g1/g1RemSet.inline.hpp"
52 #include "gc/g1/g1RootClosures.hpp"
53 #include "gc/g1/g1RootProcessor.hpp"
54 #include "gc/g1/g1StringDedup.hpp"
55 #include "gc/g1/g1YCTypes.hpp"
56 #include "gc/g1/heapRegion.inline.hpp"
57 #include "gc/g1/heapRegionRemSet.hpp"
58 #include "gc/g1/heapRegionSet.inline.hpp"
59 #include "gc/g1/suspendibleThreadSet.hpp"
60 #include "gc/g1/vm_operations_g1.hpp"
61 #include "gc/shared/gcHeapSummary.hpp"
62 #include "gc/shared/gcId.hpp"
63 #include "gc/shared/gcLocker.inline.hpp"
64 #include "gc/shared/gcTimer.hpp"
65 #include "gc/shared/gcTrace.hpp"
66 #include "gc/shared/gcTraceTime.inline.hpp"
67 #include "gc/shared/generationSpec.hpp"
68 #include "gc/shared/isGCActiveMark.hpp"
69 #include "gc/shared/preservedMarks.inline.hpp"
70 #include "gc/shared/referenceProcessor.inline.hpp"
71 #include "gc/shared/taskqueue.inline.hpp"
72 #include "logging/log.hpp"
73 #include "memory/allocation.hpp"
74 #include "memory/iterator.hpp"
75 #include "memory/resourceArea.hpp"
76 #include "oops/oop.inline.hpp"
77 #include "prims/resolvedMethodTable.hpp"
78 #include "runtime/atomic.hpp"
79 #include "runtime/heapMonitoring.hpp"
80 #include "runtime/init.hpp"
81 #include "runtime/orderAccess.inline.hpp"
82 #include "runtime/vmThread.hpp"
83 #include "utilities/globalDefinitions.hpp"
84 #include "utilities/stack.inline.hpp"
85
86 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
87
88 // INVARIANTS/NOTES
89 //
90 // All allocation activity covered by the G1CollectedHeap interface is
91 // serialized by acquiring the HeapLock. This happens in mem_allocate
92 // and allocate_new_tlab, which are the "entry" points to the
93 // allocation code from the rest of the JVM. (Note that this does not
94 // apply to TLAB allocation, which is not part of this interface: it
95 // is done by clients of this interface.)
96
97 // Local to this file.
98
99 class RefineCardTableEntryClosure: public CardTableEntryClosure {
100 bool _concurrent;
101 public:
102 RefineCardTableEntryClosure() : _concurrent(true) { }
103
104 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
105 G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);
106
107 if (_concurrent && SuspendibleThreadSet::should_yield()) {
108 // Caller will actually yield.
109 return false;
110 }
111 // Otherwise, we finished successfully; return true.
112 return true;
113 }
114
115 void set_concurrent(bool b) { _concurrent = b; }
116 };
117
118
119 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
120 private:
121 size_t _num_dirtied;
122 G1CollectedHeap* _g1h;
123 G1SATBCardTableLoggingModRefBS* _g1_bs;
124
125 HeapRegion* region_for_card(jbyte* card_ptr) const {
126 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
127 }
128
129 bool will_become_free(HeapRegion* hr) const {
130 // A region will be freed by free_collection_set if the region is in the
131 // collection set and has not had an evacuation failure.
132 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
133 }
134
135 public:
136 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
137 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
138
139 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
140 HeapRegion* hr = region_for_card(card_ptr);
141
142 // Should only dirty cards in regions that won't be freed.
143 if (!will_become_free(hr)) {
144 *card_ptr = CardTableModRefBS::dirty_card_val();
145 _num_dirtied++;
146 }
147
148 return true;
149 }
150
151 size_t num_dirtied() const { return _num_dirtied; }
152 };
153
154
155 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
156 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
157 }
158
159 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
160 // The from card cache is not the memory that is actually committed. So we cannot
161 // take advantage of the zero_filled parameter.
162 reset_from_card_cache(start_idx, num_regions);
163 }
164
165 // Returns true if the reference points to an object that
166 // can move in an incremental collection.
167 bool G1CollectedHeap::is_scavengable(const void* p) {
168 HeapRegion* hr = heap_region_containing(p);
169 return !hr->is_pinned();
170 }
171
172 // Private methods.
173
174 HeapRegion*
175 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
176 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
177 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
178 if (!_secondary_free_list.is_empty()) {
179 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
180 "secondary_free_list has %u entries",
181 _secondary_free_list.length());
182 // It looks as if there are free regions available on the
183 // secondary_free_list. Let's move them to the free_list and try
184 // again to allocate from it.
185 append_secondary_free_list();
186
187 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
188 "empty we should have moved at least one entry to the free_list");
189 HeapRegion* res = _hrm.allocate_free_region(is_old);
190 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
191 "allocated " HR_FORMAT " from secondary_free_list",
192 HR_FORMAT_PARAMS(res));
193 return res;
194 }
195
196 // Wait here until we get notified either when (a) there are no
197 // more free regions coming or (b) some regions have been moved on
198 // the secondary_free_list.
199 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
200 }
201
202 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
203 "could not allocate from secondary_free_list");
204 return NULL;
205 }
206
207 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
208 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
209 "the only time we use this to allocate a humongous region is "
210 "when we are allocating a single humongous region");
211
212 HeapRegion* res;
213 if (G1StressConcRegionFreeing) {
214 if (!_secondary_free_list.is_empty()) {
215 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
216 "forced to look at the secondary_free_list");
217 res = new_region_try_secondary_free_list(is_old);
218 if (res != NULL) {
219 return res;
220 }
221 }
222 }
223
224 res = _hrm.allocate_free_region(is_old);
225
226 if (res == NULL) {
227 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
228 "res == NULL, trying the secondary_free_list");
229 res = new_region_try_secondary_free_list(is_old);
230 }
231 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
232 // Currently, only attempts to allocate GC alloc regions set
233 // do_expand to true. So, we should only reach here during a
234 // safepoint. If this assumption changes we might have to
235 // reconsider the use of _expand_heap_after_alloc_failure.
236 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
237
238 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
239 word_size * HeapWordSize);
240
241 if (expand(word_size * HeapWordSize)) {
242 // Given that expand() succeeded in expanding the heap, and we
243 // always expand the heap by an amount aligned to the heap
244 // region size, the free list should in theory not be empty.
245 // In either case allocate_free_region() will check for NULL.
246 res = _hrm.allocate_free_region(is_old);
247 } else {
248 _expand_heap_after_alloc_failure = false;
249 }
250 }
251 return res;
252 }
253
254 HeapWord*
255 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
256 uint num_regions,
257 size_t word_size,
258 AllocationContext_t context) {
259 assert(first != G1_NO_HRM_INDEX, "pre-condition");
260 assert(is_humongous(word_size), "word_size should be humongous");
261 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
262
263 // Index of last region in the series.
264 uint last = first + num_regions - 1;
265
266 // We need to initialize the region(s) we just discovered. This is
267 // a bit tricky given that it can happen concurrently with
268 // refinement threads refining cards on these regions and
269 // potentially wanting to refine the BOT as they are scanning
270 // those cards (this can happen shortly after a cleanup; see CR
271 // 6991377). So we have to set up the region(s) carefully and in
272 // a specific order.
273
274 // The word size sum of all the regions we will allocate.
275 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
276 assert(word_size <= word_size_sum, "sanity");
277
278 // This will be the "starts humongous" region.
279 HeapRegion* first_hr = region_at(first);
280 // The header of the new object will be placed at the bottom of
281 // the first region.
282 HeapWord* new_obj = first_hr->bottom();
283 // This will be the new top of the new object.
284 HeapWord* obj_top = new_obj + word_size;
285
286 // First, we need to zero the header of the space that we will be
287 // allocating. When we update top further down, some refinement
288 // threads might try to scan the region. By zeroing the header we
289 // ensure that any thread that will try to scan the region will
290 // come across the zero klass word and bail out.
291 //
292 // NOTE: It would not have been correct to have used
293 // CollectedHeap::fill_with_object() and make the space look like
294 // an int array. The thread that is doing the allocation will
295 // later update the object header to a potentially different array
296 // type and, for a very short period of time, the klass and length
297 // fields will be inconsistent. This could cause a refinement
298 // thread to calculate the object size incorrectly.
299 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
300
301 // Next, pad out the unused tail of the last region with filler
302 // objects, for improved usage accounting.
303 // How many words we use for filler objects.
304 size_t word_fill_size = word_size_sum - word_size;
305
306 // How many words memory we "waste" which cannot hold a filler object.
307 size_t words_not_fillable = 0;
308
309 if (word_fill_size >= min_fill_size()) {
310 fill_with_objects(obj_top, word_fill_size);
311 } else if (word_fill_size > 0) {
312 // We have space to fill, but we cannot fit an object there.
313 words_not_fillable = word_fill_size;
314 word_fill_size = 0;
315 }
316
317 // We will set up the first region as "starts humongous". This
318 // will also update the BOT covering all the regions to reflect
319 // that there is a single object that starts at the bottom of the
320 // first region.
321 first_hr->set_starts_humongous(obj_top, word_fill_size);
322 first_hr->set_allocation_context(context);
323 // Then, if there are any, we will set up the "continues
324 // humongous" regions.
325 HeapRegion* hr = NULL;
326 for (uint i = first + 1; i <= last; ++i) {
327 hr = region_at(i);
328 hr->set_continues_humongous(first_hr);
329 hr->set_allocation_context(context);
330 }
331
332 // Up to this point no concurrent thread would have been able to
333 // do any scanning on any region in this series. All the top
334 // fields still point to bottom, so the intersection between
335 // [bottom,top] and [card_start,card_end] will be empty. Before we
336 // update the top fields, we'll do a storestore to make sure that
337 // no thread sees the update to top before the zeroing of the
338 // object header and the BOT initialization.
339 OrderAccess::storestore();
340
341 // Now, we will update the top fields of the "continues humongous"
342 // regions except the last one.
343 for (uint i = first; i < last; ++i) {
344 hr = region_at(i);
345 hr->set_top(hr->end());
346 }
347
348 hr = region_at(last);
349 // If we cannot fit a filler object, we must set top to the end
350 // of the humongous object, otherwise we cannot iterate the heap
351 // and the BOT will not be complete.
352 hr->set_top(hr->end() - words_not_fillable);
353
354 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
355 "obj_top should be in last region");
356
357 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
358
359 assert(words_not_fillable == 0 ||
360 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
361 "Miscalculation in humongous allocation");
362
363 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
364
365 for (uint i = first; i <= last; ++i) {
366 hr = region_at(i);
367 _humongous_set.add(hr);
368 _hr_printer.alloc(hr);
369 }
370
371 return new_obj;
372 }
373
374 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
375 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
376 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
377 }
378
379 // If could fit into free regions w/o expansion, try.
380 // Otherwise, if can expand, do so.
381 // Otherwise, if using ex regions might help, try with ex given back.
382 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
383 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
384
385 _verifier->verify_region_sets_optional();
386
387 uint first = G1_NO_HRM_INDEX;
388 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
389
390 if (obj_regions == 1) {
391 // Only one region to allocate, try to use a fast path by directly allocating
392 // from the free lists. Do not try to expand here, we will potentially do that
393 // later.
394 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
395 if (hr != NULL) {
396 first = hr->hrm_index();
397 }
398 } else {
399 // We can't allocate humongous regions spanning more than one region while
400 // cleanupComplete() is running, since some of the regions we find to be
401 // empty might not yet be added to the free list. It is not straightforward
402 // to know in which list they are on so that we can remove them. We only
403 // need to do this if we need to allocate more than one region to satisfy the
404 // current humongous allocation request. If we are only allocating one region
405 // we use the one-region region allocation code (see above), that already
406 // potentially waits for regions from the secondary free list.
407 wait_while_free_regions_coming();
408 append_secondary_free_list_if_not_empty_with_lock();
409
410 // Policy: Try only empty regions (i.e. already committed first). Maybe we
411 // are lucky enough to find some.
412 first = _hrm.find_contiguous_only_empty(obj_regions);
413 if (first != G1_NO_HRM_INDEX) {
414 _hrm.allocate_free_regions_starting_at(first, obj_regions);
415 }
416 }
417
418 if (first == G1_NO_HRM_INDEX) {
419 // Policy: We could not find enough regions for the humongous object in the
420 // free list. Look through the heap to find a mix of free and uncommitted regions.
421 // If so, try expansion.
422 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
423 if (first != G1_NO_HRM_INDEX) {
424 // We found something. Make sure these regions are committed, i.e. expand
425 // the heap. Alternatively we could do a defragmentation GC.
426 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
427 word_size * HeapWordSize);
428
429 _hrm.expand_at(first, obj_regions, workers());
430 g1_policy()->record_new_heap_size(num_regions());
431
432 #ifdef ASSERT
433 for (uint i = first; i < first + obj_regions; ++i) {
434 HeapRegion* hr = region_at(i);
435 assert(hr->is_free(), "sanity");
436 assert(hr->is_empty(), "sanity");
437 assert(is_on_master_free_list(hr), "sanity");
438 }
439 #endif
440 _hrm.allocate_free_regions_starting_at(first, obj_regions);
441 } else {
442 // Policy: Potentially trigger a defragmentation GC.
443 }
444 }
445
446 HeapWord* result = NULL;
447 if (first != G1_NO_HRM_INDEX) {
448 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
449 word_size, context);
450 assert(result != NULL, "it should always return a valid result");
451
452 // A successful humongous object allocation changes the used space
453 // information of the old generation so we need to recalculate the
454 // sizes and update the jstat counters here.
455 g1mm()->update_sizes();
456 }
457
458 _verifier->verify_region_sets_optional();
459
460 return result;
461 }
462
463 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
464 assert_heap_not_locked_and_not_at_safepoint();
465 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
466
467 uint dummy_gc_count_before;
468 uint dummy_gclocker_retry_count = 0;
469 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
470 }
471
472 HeapWord*
473 G1CollectedHeap::mem_allocate(size_t word_size,
474 bool* gc_overhead_limit_was_exceeded) {
475 assert_heap_not_locked_and_not_at_safepoint();
476
477 // Loop until the allocation is satisfied, or unsatisfied after GC.
478 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
479 uint gc_count_before;
480
481 HeapWord* result = NULL;
482 if (!is_humongous(word_size)) {
483 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
484 } else {
485 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
486 }
487 if (result != NULL) {
488 return result;
489 }
490
491 // Create the garbage collection operation...
492 VM_G1CollectForAllocation op(gc_count_before, word_size);
493 op.set_allocation_context(AllocationContext::current());
494
495 // ...and get the VM thread to execute it.
496 VMThread::execute(&op);
497
498 if (op.prologue_succeeded() && op.pause_succeeded()) {
499 // If the operation was successful we'll return the result even
500 // if it is NULL. If the allocation attempt failed immediately
501 // after a Full GC, it's unlikely we'll be able to allocate now.
502 HeapWord* result = op.result();
503 if (result != NULL && !is_humongous(word_size)) {
504 // Allocations that take place on VM operations do not do any
505 // card dirtying and we have to do it here. We only have to do
506 // this for non-humongous allocations, though.
507 dirty_young_block(result, word_size);
508 }
509 return result;
510 } else {
511 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
512 return NULL;
513 }
514 assert(op.result() == NULL,
515 "the result should be NULL if the VM op did not succeed");
516 }
517
518 // Give a warning if we seem to be looping forever.
519 if ((QueuedAllocationWarningCount > 0) &&
520 (try_count % QueuedAllocationWarningCount == 0)) {
521 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
522 }
523 }
524
525 ShouldNotReachHere();
526 return NULL;
527 }
528
529 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
530 AllocationContext_t context,
531 uint* gc_count_before_ret,
532 uint* gclocker_retry_count_ret) {
533 // Make sure you read the note in attempt_allocation_humongous().
534
535 assert_heap_not_locked_and_not_at_safepoint();
536 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
537 "be called for humongous allocation requests");
538
539 // We should only get here after the first-level allocation attempt
540 // (attempt_allocation()) failed to allocate.
541
542 // We will loop until a) we manage to successfully perform the
543 // allocation or b) we successfully schedule a collection which
544 // fails to perform the allocation. b) is the only case when we'll
545 // return NULL.
546 HeapWord* result = NULL;
547 for (int try_count = 1; /* we'll return */; try_count += 1) {
548 bool should_try_gc;
549 uint gc_count_before;
550
551 {
552 MutexLockerEx x(Heap_lock);
553 result = _allocator->attempt_allocation_locked(word_size, context);
554 if (result != NULL) {
555 return result;
556 }
557
558 if (GCLocker::is_active_and_needs_gc()) {
559 if (g1_policy()->can_expand_young_list()) {
560 // No need for an ergo verbose message here,
561 // can_expand_young_list() does this when it returns true.
562 result = _allocator->attempt_allocation_force(word_size, context);
563 if (result != NULL) {
564 return result;
565 }
566 }
567 should_try_gc = false;
568 } else {
569 // The GCLocker may not be active but the GCLocker initiated
570 // GC may not yet have been performed (GCLocker::needs_gc()
571 // returns true). In this case we do not try this GC and
572 // wait until the GCLocker initiated GC is performed, and
573 // then retry the allocation.
574 if (GCLocker::needs_gc()) {
575 should_try_gc = false;
576 } else {
577 // Read the GC count while still holding the Heap_lock.
578 gc_count_before = total_collections();
579 should_try_gc = true;
580 }
581 }
582 }
583
584 if (should_try_gc) {
585 bool succeeded;
586 result = do_collection_pause(word_size, gc_count_before, &succeeded,
587 GCCause::_g1_inc_collection_pause);
588 if (result != NULL) {
589 assert(succeeded, "only way to get back a non-NULL result");
590 return result;
591 }
592
593 if (succeeded) {
594 // If we get here we successfully scheduled a collection which
595 // failed to allocate. No point in trying to allocate
596 // further. We'll just return NULL.
597 MutexLockerEx x(Heap_lock);
598 *gc_count_before_ret = total_collections();
599 return NULL;
600 }
601 } else {
602 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
603 MutexLockerEx x(Heap_lock);
604 *gc_count_before_ret = total_collections();
605 return NULL;
606 }
607 // The GCLocker is either active or the GCLocker initiated
608 // GC has not yet been performed. Stall until it is and
609 // then retry the allocation.
610 GCLocker::stall_until_clear();
611 (*gclocker_retry_count_ret) += 1;
612 }
613
614 // We can reach here if we were unsuccessful in scheduling a
615 // collection (because another thread beat us to it) or if we were
616 // stalled due to the GC locker. In either can we should retry the
617 // allocation attempt in case another thread successfully
618 // performed a collection and reclaimed enough space. We do the
619 // first attempt (without holding the Heap_lock) here and the
620 // follow-on attempt will be at the start of the next loop
621 // iteration (after taking the Heap_lock).
622 result = _allocator->attempt_allocation(word_size, context);
623 if (result != NULL) {
624 return result;
625 }
626
627 // Give a warning if we seem to be looping forever.
628 if ((QueuedAllocationWarningCount > 0) &&
629 (try_count % QueuedAllocationWarningCount == 0)) {
630 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
631 "retries %d times", try_count);
632 }
633 }
634
635 ShouldNotReachHere();
636 return NULL;
637 }
638
639 void G1CollectedHeap::begin_archive_alloc_range() {
640 assert_at_safepoint(true /* should_be_vm_thread */);
641 if (_archive_allocator == NULL) {
642 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
643 }
644 }
645
646 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
647 // Allocations in archive regions cannot be of a size that would be considered
648 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
649 // may be different at archive-restore time.
650 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
651 }
652
653 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
654 assert_at_safepoint(true /* should_be_vm_thread */);
655 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
656 if (is_archive_alloc_too_large(word_size)) {
657 return NULL;
658 }
659 return _archive_allocator->archive_mem_allocate(word_size);
660 }
661
662 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
663 size_t end_alignment_in_bytes) {
664 assert_at_safepoint(true /* should_be_vm_thread */);
665 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
666
667 // Call complete_archive to do the real work, filling in the MemRegion
668 // array with the archive regions.
669 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
670 delete _archive_allocator;
671 _archive_allocator = NULL;
672 }
673
674 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
675 assert(ranges != NULL, "MemRegion array NULL");
676 assert(count != 0, "No MemRegions provided");
677 MemRegion reserved = _hrm.reserved();
678 for (size_t i = 0; i < count; i++) {
679 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
680 return false;
681 }
682 }
683 return true;
684 }
685
686 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
687 assert(!is_init_completed(), "Expect to be called at JVM init time");
688 assert(ranges != NULL, "MemRegion array NULL");
689 assert(count != 0, "No MemRegions provided");
690 MutexLockerEx x(Heap_lock);
691
692 MemRegion reserved = _hrm.reserved();
693 HeapWord* prev_last_addr = NULL;
694 HeapRegion* prev_last_region = NULL;
695
696 // Temporarily disable pretouching of heap pages. This interface is used
697 // when mmap'ing archived heap data in, so pre-touching is wasted.
698 FlagSetting fs(AlwaysPreTouch, false);
699
700 // Enable archive object checking used by G1MarkSweep. We have to let it know
701 // about each archive range, so that objects in those ranges aren't marked.
702 G1ArchiveAllocator::enable_archive_object_check();
703
704 // For each specified MemRegion range, allocate the corresponding G1
705 // regions and mark them as archive regions. We expect the ranges in
706 // ascending starting address order, without overlap.
707 for (size_t i = 0; i < count; i++) {
708 MemRegion curr_range = ranges[i];
709 HeapWord* start_address = curr_range.start();
710 size_t word_size = curr_range.word_size();
711 HeapWord* last_address = curr_range.last();
712 size_t commits = 0;
713
714 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
715 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
716 p2i(start_address), p2i(last_address));
717 guarantee(start_address > prev_last_addr,
718 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
719 p2i(start_address), p2i(prev_last_addr));
720 prev_last_addr = last_address;
721
722 // Check for ranges that start in the same G1 region in which the previous
723 // range ended, and adjust the start address so we don't try to allocate
724 // the same region again. If the current range is entirely within that
725 // region, skip it, just adjusting the recorded top.
726 HeapRegion* start_region = _hrm.addr_to_region(start_address);
727 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
728 start_address = start_region->end();
729 if (start_address > last_address) {
730 increase_used(word_size * HeapWordSize);
731 start_region->set_top(last_address + 1);
732 continue;
733 }
734 start_region->set_top(start_address);
735 curr_range = MemRegion(start_address, last_address + 1);
736 start_region = _hrm.addr_to_region(start_address);
737 }
738
739 // Perform the actual region allocation, exiting if it fails.
740 // Then note how much new space we have allocated.
741 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
742 return false;
743 }
744 increase_used(word_size * HeapWordSize);
745 if (commits != 0) {
746 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
747 HeapRegion::GrainWords * HeapWordSize * commits);
748
749 }
750
751 // Mark each G1 region touched by the range as archive, add it to the old set,
752 // and set the allocation context and top.
753 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
754 HeapRegion* last_region = _hrm.addr_to_region(last_address);
755 prev_last_region = last_region;
756
757 while (curr_region != NULL) {
758 assert(curr_region->is_empty() && !curr_region->is_pinned(),
759 "Region already in use (index %u)", curr_region->hrm_index());
760 curr_region->set_allocation_context(AllocationContext::system());
761 curr_region->set_archive();
762 _hr_printer.alloc(curr_region);
763 _old_set.add(curr_region);
764 if (curr_region != last_region) {
765 curr_region->set_top(curr_region->end());
766 curr_region = _hrm.next_region_in_heap(curr_region);
767 } else {
768 curr_region->set_top(last_address + 1);
769 curr_region = NULL;
770 }
771 }
772
773 // Notify mark-sweep of the archive range.
774 G1ArchiveAllocator::set_range_archive(curr_range, true);
775 }
776 return true;
777 }
778
779 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
780 assert(!is_init_completed(), "Expect to be called at JVM init time");
781 assert(ranges != NULL, "MemRegion array NULL");
782 assert(count != 0, "No MemRegions provided");
783 MemRegion reserved = _hrm.reserved();
784 HeapWord *prev_last_addr = NULL;
785 HeapRegion* prev_last_region = NULL;
786
787 // For each MemRegion, create filler objects, if needed, in the G1 regions
788 // that contain the address range. The address range actually within the
789 // MemRegion will not be modified. That is assumed to have been initialized
790 // elsewhere, probably via an mmap of archived heap data.
791 MutexLockerEx x(Heap_lock);
792 for (size_t i = 0; i < count; i++) {
793 HeapWord* start_address = ranges[i].start();
794 HeapWord* last_address = ranges[i].last();
795
796 assert(reserved.contains(start_address) && reserved.contains(last_address),
797 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
798 p2i(start_address), p2i(last_address));
799 assert(start_address > prev_last_addr,
800 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
801 p2i(start_address), p2i(prev_last_addr));
802
803 HeapRegion* start_region = _hrm.addr_to_region(start_address);
804 HeapRegion* last_region = _hrm.addr_to_region(last_address);
805 HeapWord* bottom_address = start_region->bottom();
806
807 // Check for a range beginning in the same region in which the
808 // previous one ended.
809 if (start_region == prev_last_region) {
810 bottom_address = prev_last_addr + 1;
811 }
812
813 // Verify that the regions were all marked as archive regions by
814 // alloc_archive_regions.
815 HeapRegion* curr_region = start_region;
816 while (curr_region != NULL) {
817 guarantee(curr_region->is_archive(),
818 "Expected archive region at index %u", curr_region->hrm_index());
819 if (curr_region != last_region) {
820 curr_region = _hrm.next_region_in_heap(curr_region);
821 } else {
822 curr_region = NULL;
823 }
824 }
825
826 prev_last_addr = last_address;
827 prev_last_region = last_region;
828
829 // Fill the memory below the allocated range with dummy object(s),
830 // if the region bottom does not match the range start, or if the previous
831 // range ended within the same G1 region, and there is a gap.
832 if (start_address != bottom_address) {
833 size_t fill_size = pointer_delta(start_address, bottom_address);
834 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
835 increase_used(fill_size * HeapWordSize);
836 }
837 }
838 }
839
840 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
841 uint* gc_count_before_ret,
842 uint* gclocker_retry_count_ret) {
843 assert_heap_not_locked_and_not_at_safepoint();
844 assert(!is_humongous(word_size), "attempt_allocation() should not "
845 "be called for humongous allocation requests");
846
847 AllocationContext_t context = AllocationContext::current();
848 HeapWord* result = _allocator->attempt_allocation(word_size, context);
849
850 if (result == NULL) {
851 result = attempt_allocation_slow(word_size,
852 context,
853 gc_count_before_ret,
854 gclocker_retry_count_ret);
855 }
856 assert_heap_not_locked();
857 if (result != NULL) {
858 dirty_young_block(result, word_size);
859 }
860 return result;
861 }
862
863 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
864 assert(!is_init_completed(), "Expect to be called at JVM init time");
865 assert(ranges != NULL, "MemRegion array NULL");
866 assert(count != 0, "No MemRegions provided");
867 MemRegion reserved = _hrm.reserved();
868 HeapWord* prev_last_addr = NULL;
869 HeapRegion* prev_last_region = NULL;
870 size_t size_used = 0;
871 size_t uncommitted_regions = 0;
872
873 // For each Memregion, free the G1 regions that constitute it, and
874 // notify mark-sweep that the range is no longer to be considered 'archive.'
875 MutexLockerEx x(Heap_lock);
876 for (size_t i = 0; i < count; i++) {
877 HeapWord* start_address = ranges[i].start();
878 HeapWord* last_address = ranges[i].last();
879
880 assert(reserved.contains(start_address) && reserved.contains(last_address),
881 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
882 p2i(start_address), p2i(last_address));
883 assert(start_address > prev_last_addr,
884 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
885 p2i(start_address), p2i(prev_last_addr));
886 size_used += ranges[i].byte_size();
887 prev_last_addr = last_address;
888
889 HeapRegion* start_region = _hrm.addr_to_region(start_address);
890 HeapRegion* last_region = _hrm.addr_to_region(last_address);
891
892 // Check for ranges that start in the same G1 region in which the previous
893 // range ended, and adjust the start address so we don't try to free
894 // the same region again. If the current range is entirely within that
895 // region, skip it.
896 if (start_region == prev_last_region) {
897 start_address = start_region->end();
898 if (start_address > last_address) {
899 continue;
900 }
901 start_region = _hrm.addr_to_region(start_address);
902 }
903 prev_last_region = last_region;
904
905 // After verifying that each region was marked as an archive region by
906 // alloc_archive_regions, set it free and empty and uncommit it.
907 HeapRegion* curr_region = start_region;
908 while (curr_region != NULL) {
909 guarantee(curr_region->is_archive(),
910 "Expected archive region at index %u", curr_region->hrm_index());
911 uint curr_index = curr_region->hrm_index();
912 _old_set.remove(curr_region);
913 curr_region->set_free();
914 curr_region->set_top(curr_region->bottom());
915 if (curr_region != last_region) {
916 curr_region = _hrm.next_region_in_heap(curr_region);
917 } else {
918 curr_region = NULL;
919 }
920 _hrm.shrink_at(curr_index, 1);
921 uncommitted_regions++;
922 }
923
924 // Notify mark-sweep that this is no longer an archive range.
925 G1ArchiveAllocator::set_range_archive(ranges[i], false);
926 }
927
928 if (uncommitted_regions != 0) {
929 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
930 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
931 }
932 decrease_used(size_used);
933 }
934
935 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
936 uint* gc_count_before_ret,
937 uint* gclocker_retry_count_ret) {
938 // The structure of this method has a lot of similarities to
939 // attempt_allocation_slow(). The reason these two were not merged
940 // into a single one is that such a method would require several "if
941 // allocation is not humongous do this, otherwise do that"
942 // conditional paths which would obscure its flow. In fact, an early
943 // version of this code did use a unified method which was harder to
944 // follow and, as a result, it had subtle bugs that were hard to
945 // track down. So keeping these two methods separate allows each to
946 // be more readable. It will be good to keep these two in sync as
947 // much as possible.
948
949 assert_heap_not_locked_and_not_at_safepoint();
950 assert(is_humongous(word_size), "attempt_allocation_humongous() "
951 "should only be called for humongous allocations");
952
953 // Humongous objects can exhaust the heap quickly, so we should check if we
954 // need to start a marking cycle at each humongous object allocation. We do
955 // the check before we do the actual allocation. The reason for doing it
956 // before the allocation is that we avoid having to keep track of the newly
957 // allocated memory while we do a GC.
958 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
959 word_size)) {
960 collect(GCCause::_g1_humongous_allocation);
961 }
962
963 // We will loop until a) we manage to successfully perform the
964 // allocation or b) we successfully schedule a collection which
965 // fails to perform the allocation. b) is the only case when we'll
966 // return NULL.
967 HeapWord* result = NULL;
968 for (int try_count = 1; /* we'll return */; try_count += 1) {
969 bool should_try_gc;
970 uint gc_count_before;
971
972 {
973 MutexLockerEx x(Heap_lock);
974
975 // Given that humongous objects are not allocated in young
976 // regions, we'll first try to do the allocation without doing a
977 // collection hoping that there's enough space in the heap.
978 result = humongous_obj_allocate(word_size, AllocationContext::current());
979 if (result != NULL) {
980 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
981 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
982 return result;
983 }
984
985 if (GCLocker::is_active_and_needs_gc()) {
986 should_try_gc = false;
987 } else {
988 // The GCLocker may not be active but the GCLocker initiated
989 // GC may not yet have been performed (GCLocker::needs_gc()
990 // returns true). In this case we do not try this GC and
991 // wait until the GCLocker initiated GC is performed, and
992 // then retry the allocation.
993 if (GCLocker::needs_gc()) {
994 should_try_gc = false;
995 } else {
996 // Read the GC count while still holding the Heap_lock.
997 gc_count_before = total_collections();
998 should_try_gc = true;
999 }
1000 }
1001 }
1002
1003 if (should_try_gc) {
1004 // If we failed to allocate the humongous object, we should try to
1005 // do a collection pause (if we're allowed) in case it reclaims
1006 // enough space for the allocation to succeed after the pause.
1007
1008 bool succeeded;
1009 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1010 GCCause::_g1_humongous_allocation);
1011 if (result != NULL) {
1012 assert(succeeded, "only way to get back a non-NULL result");
1013 return result;
1014 }
1015
1016 if (succeeded) {
1017 // If we get here we successfully scheduled a collection which
1018 // failed to allocate. No point in trying to allocate
1019 // further. We'll just return NULL.
1020 MutexLockerEx x(Heap_lock);
1021 *gc_count_before_ret = total_collections();
1022 return NULL;
1023 }
1024 } else {
1025 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1026 MutexLockerEx x(Heap_lock);
1027 *gc_count_before_ret = total_collections();
1028 return NULL;
1029 }
1030 // The GCLocker is either active or the GCLocker initiated
1031 // GC has not yet been performed. Stall until it is and
1032 // then retry the allocation.
1033 GCLocker::stall_until_clear();
1034 (*gclocker_retry_count_ret) += 1;
1035 }
1036
1037 // We can reach here if we were unsuccessful in scheduling a
1038 // collection (because another thread beat us to it) or if we were
1039 // stalled due to the GC locker. In either can we should retry the
1040 // allocation attempt in case another thread successfully
1041 // performed a collection and reclaimed enough space. Give a
1042 // warning if we seem to be looping forever.
1043
1044 if ((QueuedAllocationWarningCount > 0) &&
1045 (try_count % QueuedAllocationWarningCount == 0)) {
1046 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1047 "retries %d times", try_count);
1048 }
1049 }
1050
1051 ShouldNotReachHere();
1052 return NULL;
1053 }
1054
1055 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1056 AllocationContext_t context,
1057 bool expect_null_mutator_alloc_region) {
1058 assert_at_safepoint(true /* should_be_vm_thread */);
1059 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1060 "the current alloc region was unexpectedly found to be non-NULL");
1061
1062 if (!is_humongous(word_size)) {
1063 return _allocator->attempt_allocation_locked(word_size, context);
1064 } else {
1065 HeapWord* result = humongous_obj_allocate(word_size, context);
1066 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1067 collector_state()->set_initiate_conc_mark_if_possible(true);
1068 }
1069 return result;
1070 }
1071
1072 ShouldNotReachHere();
1073 }
1074
1075 class PostMCRemSetClearClosure: public HeapRegionClosure {
1076 G1CollectedHeap* _g1h;
1077 ModRefBarrierSet* _mr_bs;
1078 public:
1079 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1080 _g1h(g1h), _mr_bs(mr_bs) {}
1081
1082 bool doHeapRegion(HeapRegion* r) {
1083 HeapRegionRemSet* hrrs = r->rem_set();
1084
1085 _g1h->reset_gc_time_stamps(r);
1086
1087 if (r->is_continues_humongous()) {
1088 // We'll assert that the strong code root list and RSet is empty
1089 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1090 assert(hrrs->occupied() == 0, "RSet should be empty");
1091 } else {
1092 hrrs->clear();
1093 }
1094 // You might think here that we could clear just the cards
1095 // corresponding to the used region. But no: if we leave a dirty card
1096 // in a region we might allocate into, then it would prevent that card
1097 // from being enqueued, and cause it to be missed.
1098 // Re: the performance cost: we shouldn't be doing full GC anyway!
1099 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1100
1101 return false;
1102 }
1103 };
1104
1105 void G1CollectedHeap::clear_rsets_post_compaction() {
1106 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1107 heap_region_iterate(&rs_clear);
1108 }
1109
1110 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1111 G1CollectedHeap* _g1h;
1112 UpdateRSOopClosure _cl;
1113 public:
1114 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1115 _cl(g1->g1_rem_set(), worker_i),
1116 _g1h(g1)
1117 { }
1118
1119 bool doHeapRegion(HeapRegion* r) {
1120 if (!r->is_continues_humongous()) {
1121 _cl.set_from(r);
1122 r->oop_iterate(&_cl);
1123 }
1124 return false;
1125 }
1126 };
1127
1128 class ParRebuildRSTask: public AbstractGangTask {
1129 G1CollectedHeap* _g1;
1130 HeapRegionClaimer _hrclaimer;
1131
1132 public:
1133 ParRebuildRSTask(G1CollectedHeap* g1) :
1134 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1135
1136 void work(uint worker_id) {
1137 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1138 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1139 }
1140 };
1141
1142 class PostCompactionPrinterClosure: public HeapRegionClosure {
1143 private:
1144 G1HRPrinter* _hr_printer;
1145 public:
1146 bool doHeapRegion(HeapRegion* hr) {
1147 assert(!hr->is_young(), "not expecting to find young regions");
1148 _hr_printer->post_compaction(hr);
1149 return false;
1150 }
1151
1152 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1153 : _hr_printer(hr_printer) { }
1154 };
1155
1156 void G1CollectedHeap::print_hrm_post_compaction() {
1157 if (_hr_printer.is_active()) {
1158 PostCompactionPrinterClosure cl(hr_printer());
1159 heap_region_iterate(&cl);
1160 }
1161
1162 }
1163
1164 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1165 bool clear_all_soft_refs) {
1166 assert_at_safepoint(true /* should_be_vm_thread */);
1167
1168 if (GCLocker::check_active_before_gc()) {
1169 return false;
1170 }
1171
1172 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1173 gc_timer->register_gc_start();
1174
1175 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1176 GCIdMark gc_id_mark;
1177 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1178
1179 SvcGCMarker sgcm(SvcGCMarker::FULL);
1180 ResourceMark rm;
1181
1182 print_heap_before_gc();
1183 print_heap_regions();
1184 trace_heap_before_gc(gc_tracer);
1185
1186 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1187
1188 _verifier->verify_region_sets_optional();
1189
1190 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1191 collector_policy()->should_clear_all_soft_refs();
1192
1193 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1194
1195 {
1196 IsGCActiveMark x;
1197
1198 // Timing
1199 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1200 GCTraceCPUTime tcpu;
1201
1202 {
1203 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1204 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1205 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1206
1207 G1HeapTransition heap_transition(this);
1208 g1_policy()->record_full_collection_start();
1209
1210 // Note: When we have a more flexible GC logging framework that
1211 // allows us to add optional attributes to a GC log record we
1212 // could consider timing and reporting how long we wait in the
1213 // following two methods.
1214 wait_while_free_regions_coming();
1215 // If we start the compaction before the CM threads finish
1216 // scanning the root regions we might trip them over as we'll
1217 // be moving objects / updating references. So let's wait until
1218 // they are done. By telling them to abort, they should complete
1219 // early.
1220 _cm->root_regions()->abort();
1221 _cm->root_regions()->wait_until_scan_finished();
1222 append_secondary_free_list_if_not_empty_with_lock();
1223
1224 gc_prologue(true);
1225 increment_total_collections(true /* full gc */);
1226 increment_old_marking_cycles_started();
1227
1228 assert(used() == recalculate_used(), "Should be equal");
1229
1230 _verifier->verify_before_gc();
1231
1232 _verifier->check_bitmaps("Full GC Start");
1233 pre_full_gc_dump(gc_timer);
1234
1235 #if defined(COMPILER2) || INCLUDE_JVMCI
1236 DerivedPointerTable::clear();
1237 #endif
1238
1239 // Disable discovery and empty the discovered lists
1240 // for the CM ref processor.
1241 ref_processor_cm()->disable_discovery();
1242 ref_processor_cm()->abandon_partial_discovery();
1243 ref_processor_cm()->verify_no_references_recorded();
1244
1245 // Abandon current iterations of concurrent marking and concurrent
1246 // refinement, if any are in progress.
1247 concurrent_mark()->abort();
1248
1249 // Make sure we'll choose a new allocation region afterwards.
1250 _allocator->release_mutator_alloc_region();
1251 _allocator->abandon_gc_alloc_regions();
1252 g1_rem_set()->cleanupHRRS();
1253
1254 // We may have added regions to the current incremental collection
1255 // set between the last GC or pause and now. We need to clear the
1256 // incremental collection set and then start rebuilding it afresh
1257 // after this full GC.
1258 abandon_collection_set(collection_set());
1259
1260 tear_down_region_sets(false /* free_list_only */);
1261 collector_state()->set_gcs_are_young(true);
1262
1263 // See the comments in g1CollectedHeap.hpp and
1264 // G1CollectedHeap::ref_processing_init() about
1265 // how reference processing currently works in G1.
1266
1267 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1268 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1269
1270 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1271 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1272
1273 ref_processor_stw()->enable_discovery();
1274 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1275
1276 // Do collection work
1277 {
1278 HandleMark hm; // Discard invalid handles created during gc
1279 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1280 }
1281
1282 assert(num_free_regions() == 0, "we should not have added any free regions");
1283 rebuild_region_sets(false /* free_list_only */);
1284
1285 // Enqueue any discovered reference objects that have
1286 // not been removed from the discovered lists.
1287 ref_processor_stw()->enqueue_discovered_references();
1288
1289 #if defined(COMPILER2) || INCLUDE_JVMCI
1290 DerivedPointerTable::update_pointers();
1291 #endif
1292
1293 MemoryService::track_memory_usage();
1294
1295 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1296 ref_processor_stw()->verify_no_references_recorded();
1297
1298 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1299 ClassLoaderDataGraph::purge();
1300 MetaspaceAux::verify_metrics();
1301
1302 // Note: since we've just done a full GC, concurrent
1303 // marking is no longer active. Therefore we need not
1304 // re-enable reference discovery for the CM ref processor.
1305 // That will be done at the start of the next marking cycle.
1306 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1307 ref_processor_cm()->verify_no_references_recorded();
1308
1309 reset_gc_time_stamp();
1310 // Since everything potentially moved, we will clear all remembered
1311 // sets, and clear all cards. Later we will rebuild remembered
1312 // sets. We will also reset the GC time stamps of the regions.
1313 clear_rsets_post_compaction();
1314 check_gc_time_stamps();
1315
1316 resize_if_necessary_after_full_collection();
1317
1318 // We should do this after we potentially resize the heap so
1319 // that all the COMMIT / UNCOMMIT events are generated before
1320 // the compaction events.
1321 print_hrm_post_compaction();
1322
1323 if (_hot_card_cache->use_cache()) {
1324 _hot_card_cache->reset_card_counts();
1325 _hot_card_cache->reset_hot_cache();
1326 }
1327
1328 // Rebuild remembered sets of all regions.
1329 uint n_workers =
1330 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1331 workers()->active_workers(),
1332 Threads::number_of_non_daemon_threads());
1333 workers()->update_active_workers(n_workers);
1334 log_info(gc,task)("Using %u workers of %u to rebuild remembered set", n_workers, workers()->total_workers());
1335
1336 ParRebuildRSTask rebuild_rs_task(this);
1337 workers()->run_task(&rebuild_rs_task);
1338
1339 // Rebuild the strong code root lists for each region
1340 rebuild_strong_code_roots();
1341
1342 if (true) { // FIXME
1343 MetaspaceGC::compute_new_size();
1344 }
1345
1346 #ifdef TRACESPINNING
1347 ParallelTaskTerminator::print_termination_counts();
1348 #endif
1349
1350 // Discard all rset updates
1351 JavaThread::dirty_card_queue_set().abandon_logs();
1352 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1353
1354 // At this point there should be no regions in the
1355 // entire heap tagged as young.
1356 assert(check_young_list_empty(), "young list should be empty at this point");
1357
1358 // Update the number of full collections that have been completed.
1359 increment_old_marking_cycles_completed(false /* concurrent */);
1360
1361 _hrm.verify_optional();
1362 _verifier->verify_region_sets_optional();
1363
1364 _verifier->verify_after_gc();
1365
1366 // Clear the previous marking bitmap, if needed for bitmap verification.
1367 // Note we cannot do this when we clear the next marking bitmap in
1368 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1369 // objects marked during a full GC against the previous bitmap.
1370 // But we need to clear it before calling check_bitmaps below since
1371 // the full GC has compacted objects and updated TAMS but not updated
1372 // the prev bitmap.
1373 if (G1VerifyBitmaps) {
1374 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1375 _cm->clear_prev_bitmap(workers());
1376 }
1377 _verifier->check_bitmaps("Full GC End");
1378
1379 start_new_collection_set();
1380
1381 _allocator->init_mutator_alloc_region();
1382
1383 g1_policy()->record_full_collection_end();
1384
1385 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1386 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1387 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1388 // before any GC notifications are raised.
1389 g1mm()->update_sizes();
1390
1391 gc_epilogue(true);
1392
1393 heap_transition.print();
1394
1395 print_heap_after_gc();
1396 print_heap_regions();
1397 trace_heap_after_gc(gc_tracer);
1398
1399 post_full_gc_dump(gc_timer);
1400 }
1401
1402 gc_timer->register_gc_end();
1403 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1404 }
1405
1406 return true;
1407 }
1408
1409 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1410 // Currently, there is no facility in the do_full_collection(bool) API to notify
1411 // the caller that the collection did not succeed (e.g., because it was locked
1412 // out by the GC locker). So, right now, we'll ignore the return value.
1413 bool dummy = do_full_collection(true, /* explicit_gc */
1414 clear_all_soft_refs);
1415 }
1416
1417 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1418 // Include bytes that will be pre-allocated to support collections, as "used".
1419 const size_t used_after_gc = used();
1420 const size_t capacity_after_gc = capacity();
1421 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1422
1423 // This is enforced in arguments.cpp.
1424 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1425 "otherwise the code below doesn't make sense");
1426
1427 // We don't have floating point command-line arguments
1428 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1429 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1430 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1431 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1432
1433 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1434 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1435
1436 // We have to be careful here as these two calculations can overflow
1437 // 32-bit size_t's.
1438 double used_after_gc_d = (double) used_after_gc;
1439 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1440 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1441
1442 // Let's make sure that they are both under the max heap size, which
1443 // by default will make them fit into a size_t.
1444 double desired_capacity_upper_bound = (double) max_heap_size;
1445 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1446 desired_capacity_upper_bound);
1447 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1448 desired_capacity_upper_bound);
1449
1450 // We can now safely turn them into size_t's.
1451 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1452 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1453
1454 // This assert only makes sense here, before we adjust them
1455 // with respect to the min and max heap size.
1456 assert(minimum_desired_capacity <= maximum_desired_capacity,
1457 "minimum_desired_capacity = " SIZE_FORMAT ", "
1458 "maximum_desired_capacity = " SIZE_FORMAT,
1459 minimum_desired_capacity, maximum_desired_capacity);
1460
1461 // Should not be greater than the heap max size. No need to adjust
1462 // it with respect to the heap min size as it's a lower bound (i.e.,
1463 // we'll try to make the capacity larger than it, not smaller).
1464 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1465 // Should not be less than the heap min size. No need to adjust it
1466 // with respect to the heap max size as it's an upper bound (i.e.,
1467 // we'll try to make the capacity smaller than it, not greater).
1468 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1469
1470 if (capacity_after_gc < minimum_desired_capacity) {
1471 // Don't expand unless it's significant
1472 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1473
1474 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1475 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1476 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1477
1478 expand(expand_bytes, _workers);
1479
1480 // No expansion, now see if we want to shrink
1481 } else if (capacity_after_gc > maximum_desired_capacity) {
1482 // Capacity too large, compute shrinking size
1483 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1484
1485 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1486 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1487 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1488
1489 shrink(shrink_bytes);
1490 }
1491 }
1492
1493 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1494 AllocationContext_t context,
1495 bool do_gc,
1496 bool clear_all_soft_refs,
1497 bool expect_null_mutator_alloc_region,
1498 bool* gc_succeeded) {
1499 *gc_succeeded = true;
1500 // Let's attempt the allocation first.
1501 HeapWord* result =
1502 attempt_allocation_at_safepoint(word_size,
1503 context,
1504 expect_null_mutator_alloc_region);
1505 if (result != NULL) {
1506 assert(*gc_succeeded, "sanity");
1507 return result;
1508 }
1509
1510 // In a G1 heap, we're supposed to keep allocation from failing by
1511 // incremental pauses. Therefore, at least for now, we'll favor
1512 // expansion over collection. (This might change in the future if we can
1513 // do something smarter than full collection to satisfy a failed alloc.)
1514 result = expand_and_allocate(word_size, context);
1515 if (result != NULL) {
1516 assert(*gc_succeeded, "sanity");
1517 return result;
1518 }
1519
1520 if (do_gc) {
1521 // Expansion didn't work, we'll try to do a Full GC.
1522 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1523 clear_all_soft_refs);
1524 }
1525
1526 return NULL;
1527 }
1528
1529 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1530 AllocationContext_t context,
1531 bool* succeeded) {
1532 assert_at_safepoint(true /* should_be_vm_thread */);
1533
1534 // Attempts to allocate followed by Full GC.
1535 HeapWord* result =
1536 satisfy_failed_allocation_helper(word_size,
1537 context,
1538 true, /* do_gc */
1539 false, /* clear_all_soft_refs */
1540 false, /* expect_null_mutator_alloc_region */
1541 succeeded);
1542
1543 if (result != NULL || !*succeeded) {
1544 return result;
1545 }
1546
1547 // Attempts to allocate followed by Full GC that will collect all soft references.
1548 result = satisfy_failed_allocation_helper(word_size,
1549 context,
1550 true, /* do_gc */
1551 true, /* clear_all_soft_refs */
1552 true, /* expect_null_mutator_alloc_region */
1553 succeeded);
1554
1555 if (result != NULL || !*succeeded) {
1556 return result;
1557 }
1558
1559 // Attempts to allocate, no GC
1560 result = satisfy_failed_allocation_helper(word_size,
1561 context,
1562 false, /* do_gc */
1563 false, /* clear_all_soft_refs */
1564 true, /* expect_null_mutator_alloc_region */
1565 succeeded);
1566
1567 if (result != NULL) {
1568 assert(*succeeded, "sanity");
1569 return result;
1570 }
1571
1572 assert(!collector_policy()->should_clear_all_soft_refs(),
1573 "Flag should have been handled and cleared prior to this point");
1574
1575 // What else? We might try synchronous finalization later. If the total
1576 // space available is large enough for the allocation, then a more
1577 // complete compaction phase than we've tried so far might be
1578 // appropriate.
1579 assert(*succeeded, "sanity");
1580 return NULL;
1581 }
1582
1583 // Attempting to expand the heap sufficiently
1584 // to support an allocation of the given "word_size". If
1585 // successful, perform the allocation and return the address of the
1586 // allocated block, or else "NULL".
1587
1588 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1589 assert_at_safepoint(true /* should_be_vm_thread */);
1590
1591 _verifier->verify_region_sets_optional();
1592
1593 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1594 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1595 word_size * HeapWordSize);
1596
1597
1598 if (expand(expand_bytes, _workers)) {
1599 _hrm.verify_optional();
1600 _verifier->verify_region_sets_optional();
1601 return attempt_allocation_at_safepoint(word_size,
1602 context,
1603 false /* expect_null_mutator_alloc_region */);
1604 }
1605 return NULL;
1606 }
1607
1608 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1609 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1610 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1611 HeapRegion::GrainBytes);
1612
1613 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1614 expand_bytes, aligned_expand_bytes);
1615
1616 if (is_maximal_no_gc()) {
1617 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1618 return false;
1619 }
1620
1621 double expand_heap_start_time_sec = os::elapsedTime();
1622 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1623 assert(regions_to_expand > 0, "Must expand by at least one region");
1624
1625 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1626 if (expand_time_ms != NULL) {
1627 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1628 }
1629
1630 if (expanded_by > 0) {
1631 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1632 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1633 g1_policy()->record_new_heap_size(num_regions());
1634 } else {
1635 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1636
1637 // The expansion of the virtual storage space was unsuccessful.
1638 // Let's see if it was because we ran out of swap.
1639 if (G1ExitOnExpansionFailure &&
1640 _hrm.available() >= regions_to_expand) {
1641 // We had head room...
1642 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1643 }
1644 }
1645 return regions_to_expand > 0;
1646 }
1647
1648 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1649 size_t aligned_shrink_bytes =
1650 ReservedSpace::page_align_size_down(shrink_bytes);
1651 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1652 HeapRegion::GrainBytes);
1653 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1654
1655 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1656 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1657
1658
1659 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",
1660 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1661 if (num_regions_removed > 0) {
1662 g1_policy()->record_new_heap_size(num_regions());
1663 } else {
1664 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1665 }
1666 }
1667
1668 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1669 _verifier->verify_region_sets_optional();
1670
1671 // We should only reach here at the end of a Full GC which means we
1672 // should not not be holding to any GC alloc regions. The method
1673 // below will make sure of that and do any remaining clean up.
1674 _allocator->abandon_gc_alloc_regions();
1675
1676 // Instead of tearing down / rebuilding the free lists here, we
1677 // could instead use the remove_all_pending() method on free_list to
1678 // remove only the ones that we need to remove.
1679 tear_down_region_sets(true /* free_list_only */);
1680 shrink_helper(shrink_bytes);
1681 rebuild_region_sets(true /* free_list_only */);
1682
1683 _hrm.verify_optional();
1684 _verifier->verify_region_sets_optional();
1685 }
1686
1687 // Public methods.
1688
1689 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1690 CollectedHeap(),
1691 _collector_policy(collector_policy),
1692 _g1_policy(create_g1_policy()),
1693 _collection_set(this, _g1_policy),
1694 _dirty_card_queue_set(false),
1695 _is_alive_closure_cm(this),
1696 _is_alive_closure_stw(this),
1697 _ref_processor_cm(NULL),
1698 _ref_processor_stw(NULL),
1699 _bot(NULL),
1700 _hot_card_cache(NULL),
1701 _g1_rem_set(NULL),
1702 _cg1r(NULL),
1703 _g1mm(NULL),
1704 _refine_cte_cl(NULL),
1705 _preserved_marks_set(true /* in_c_heap */),
1706 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1707 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1708 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1709 _humongous_reclaim_candidates(),
1710 _has_humongous_reclaim_candidates(false),
1711 _archive_allocator(NULL),
1712 _free_regions_coming(false),
1713 _gc_time_stamp(0),
1714 _summary_bytes_used(0),
1715 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1716 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1717 _expand_heap_after_alloc_failure(true),
1718 _old_marking_cycles_started(0),
1719 _old_marking_cycles_completed(0),
1720 _in_cset_fast_test(),
1721 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1722 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1723
1724 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1725 /* are_GC_task_threads */true,
1726 /* are_ConcurrentGC_threads */false);
1727 _workers->initialize_workers();
1728 _verifier = new G1HeapVerifier(this);
1729
1730 _allocator = G1Allocator::create_allocator(this);
1731
1732 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1733
1734 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1735
1736 // Override the default _filler_array_max_size so that no humongous filler
1737 // objects are created.
1738 _filler_array_max_size = _humongous_object_threshold_in_words;
1739
1740 uint n_queues = ParallelGCThreads;
1741 _task_queues = new RefToScanQueueSet(n_queues);
1742
1743 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1744
1745 for (uint i = 0; i < n_queues; i++) {
1746 RefToScanQueue* q = new RefToScanQueue();
1747 q->initialize();
1748 _task_queues->register_queue(i, q);
1749 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1750 }
1751
1752 // Initialize the G1EvacuationFailureALot counters and flags.
1753 NOT_PRODUCT(reset_evacuation_should_fail();)
1754
1755 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1756 }
1757
1758 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1759 size_t size,
1760 size_t translation_factor) {
1761 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1762 // Allocate a new reserved space, preferring to use large pages.
1763 ReservedSpace rs(size, preferred_page_size);
1764 G1RegionToSpaceMapper* result =
1765 G1RegionToSpaceMapper::create_mapper(rs,
1766 size,
1767 rs.alignment(),
1768 HeapRegion::GrainBytes,
1769 translation_factor,
1770 mtGC);
1771
1772 os::trace_page_sizes_for_requested_size(description,
1773 size,
1774 preferred_page_size,
1775 rs.alignment(),
1776 rs.base(),
1777 rs.size());
1778
1779 return result;
1780 }
1781
1782 jint G1CollectedHeap::initialize() {
1783 CollectedHeap::pre_initialize();
1784 os::enable_vtime();
1785
1786 // Necessary to satisfy locking discipline assertions.
1787
1788 MutexLocker x(Heap_lock);
1789
1790 // While there are no constraints in the GC code that HeapWordSize
1791 // be any particular value, there are multiple other areas in the
1792 // system which believe this to be true (e.g. oop->object_size in some
1793 // cases incorrectly returns the size in wordSize units rather than
1794 // HeapWordSize).
1795 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1796
1797 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1798 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1799 size_t heap_alignment = collector_policy()->heap_alignment();
1800
1801 // Ensure that the sizes are properly aligned.
1802 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1803 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1804 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1805
1806 _refine_cte_cl = new RefineCardTableEntryClosure();
1807
1808 jint ecode = JNI_OK;
1809 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1810 if (_cg1r == NULL) {
1811 return ecode;
1812 }
1813
1814 // Reserve the maximum.
1815
1816 // When compressed oops are enabled, the preferred heap base
1817 // is calculated by subtracting the requested size from the
1818 // 32Gb boundary and using the result as the base address for
1819 // heap reservation. If the requested size is not aligned to
1820 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1821 // into the ReservedHeapSpace constructor) then the actual
1822 // base of the reserved heap may end up differing from the
1823 // address that was requested (i.e. the preferred heap base).
1824 // If this happens then we could end up using a non-optimal
1825 // compressed oops mode.
1826
1827 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1828 heap_alignment);
1829
1830 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1831
1832 // Create the barrier set for the entire reserved region.
1833 G1SATBCardTableLoggingModRefBS* bs
1834 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1835 bs->initialize();
1836 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1837 set_barrier_set(bs);
1838
1839 // Create the hot card cache.
1840 _hot_card_cache = new G1HotCardCache(this);
1841
1842 // Also create a G1 rem set.
1843 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1844
1845 // Carve out the G1 part of the heap.
1846 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1847 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1848 G1RegionToSpaceMapper* heap_storage =
1849 G1RegionToSpaceMapper::create_mapper(g1_rs,
1850 g1_rs.size(),
1851 page_size,
1852 HeapRegion::GrainBytes,
1853 1,
1854 mtJavaHeap);
1855 os::trace_page_sizes("Heap",
1856 collector_policy()->min_heap_byte_size(),
1857 max_byte_size,
1858 page_size,
1859 heap_rs.base(),
1860 heap_rs.size());
1861 heap_storage->set_mapping_changed_listener(&_listener);
1862
1863 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1864 G1RegionToSpaceMapper* bot_storage =
1865 create_aux_memory_mapper("Block Offset Table",
1866 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1867 G1BlockOffsetTable::heap_map_factor());
1868
1869 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1870 G1RegionToSpaceMapper* cardtable_storage =
1871 create_aux_memory_mapper("Card Table",
1872 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1873 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1874
1875 G1RegionToSpaceMapper* card_counts_storage =
1876 create_aux_memory_mapper("Card Counts Table",
1877 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1878 G1CardCounts::heap_map_factor());
1879
1880 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1881 G1RegionToSpaceMapper* prev_bitmap_storage =
1882 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1883 G1RegionToSpaceMapper* next_bitmap_storage =
1884 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1885
1886 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1887 g1_barrier_set()->initialize(cardtable_storage);
1888 // Do later initialization work for concurrent refinement.
1889 _hot_card_cache->initialize(card_counts_storage);
1890
1891 // 6843694 - ensure that the maximum region index can fit
1892 // in the remembered set structures.
1893 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1894 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1895
1896 g1_rem_set()->initialize(max_capacity(), max_regions());
1897
1898 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1899 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1900 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1901 "too many cards per region");
1902
1903 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1904
1905 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1906
1907 {
1908 HeapWord* start = _hrm.reserved().start();
1909 HeapWord* end = _hrm.reserved().end();
1910 size_t granularity = HeapRegion::GrainBytes;
1911
1912 _in_cset_fast_test.initialize(start, end, granularity);
1913 _humongous_reclaim_candidates.initialize(start, end, granularity);
1914 }
1915
1916 // Create the G1ConcurrentMark data structure and thread.
1917 // (Must do this late, so that "max_regions" is defined.)
1918 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1919 if (_cm == NULL || !_cm->completed_initialization()) {
1920 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1921 return JNI_ENOMEM;
1922 }
1923 _cmThread = _cm->cmThread();
1924
1925 // Now expand into the initial heap size.
1926 if (!expand(init_byte_size, _workers)) {
1927 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1928 return JNI_ENOMEM;
1929 }
1930
1931 // Perform any initialization actions delegated to the policy.
1932 g1_policy()->init(this, &_collection_set);
1933
1934 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1935 SATB_Q_FL_lock,
1936 G1SATBProcessCompletedThreshold,
1937 Shared_SATB_Q_lock);
1938
1939 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1940 DirtyCardQ_CBL_mon,
1941 DirtyCardQ_FL_lock,
1942 (int)concurrent_g1_refine()->yellow_zone(),
1943 (int)concurrent_g1_refine()->red_zone(),
1944 Shared_DirtyCardQ_lock,
1945 NULL, // fl_owner
1946 true); // init_free_ids
1947
1948 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1949 DirtyCardQ_CBL_mon,
1950 DirtyCardQ_FL_lock,
1951 -1, // never trigger processing
1952 -1, // no limit on length
1953 Shared_DirtyCardQ_lock,
1954 &JavaThread::dirty_card_queue_set());
1955
1956 // Here we allocate the dummy HeapRegion that is required by the
1957 // G1AllocRegion class.
1958 HeapRegion* dummy_region = _hrm.get_dummy_region();
1959
1960 // We'll re-use the same region whether the alloc region will
1961 // require BOT updates or not and, if it doesn't, then a non-young
1962 // region will complain that it cannot support allocations without
1963 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1964 dummy_region->set_eden();
1965 // Make sure it's full.
1966 dummy_region->set_top(dummy_region->end());
1967 G1AllocRegion::setup(this, dummy_region);
1968
1969 _allocator->init_mutator_alloc_region();
1970
1971 // Do create of the monitoring and management support so that
1972 // values in the heap have been properly initialized.
1973 _g1mm = new G1MonitoringSupport(this);
1974
1975 G1StringDedup::initialize();
1976
1977 _preserved_marks_set.init(ParallelGCThreads);
1978
1979 _collection_set.initialize(max_regions());
1980
1981 return JNI_OK;
1982 }
1983
1984 void G1CollectedHeap::stop() {
1985 // Stop all concurrent threads. We do this to make sure these threads
1986 // do not continue to execute and access resources (e.g. logging)
1987 // that are destroyed during shutdown.
1988 _cg1r->stop();
1989 _cmThread->stop();
1990 if (G1StringDedup::is_enabled()) {
1991 G1StringDedup::stop();
1992 }
1993 }
1994
1995 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1996 return HeapRegion::max_region_size();
1997 }
1998
1999 void G1CollectedHeap::post_initialize() {
2000 ref_processing_init();
2001 }
2002
2003 void G1CollectedHeap::ref_processing_init() {
2004 // Reference processing in G1 currently works as follows:
2005 //
2006 // * There are two reference processor instances. One is
2007 // used to record and process discovered references
2008 // during concurrent marking; the other is used to
2009 // record and process references during STW pauses
2010 // (both full and incremental).
2011 // * Both ref processors need to 'span' the entire heap as
2012 // the regions in the collection set may be dotted around.
2013 //
2014 // * For the concurrent marking ref processor:
2015 // * Reference discovery is enabled at initial marking.
2016 // * Reference discovery is disabled and the discovered
2017 // references processed etc during remarking.
2018 // * Reference discovery is MT (see below).
2019 // * Reference discovery requires a barrier (see below).
2020 // * Reference processing may or may not be MT
2021 // (depending on the value of ParallelRefProcEnabled
2022 // and ParallelGCThreads).
2023 // * A full GC disables reference discovery by the CM
2024 // ref processor and abandons any entries on it's
2025 // discovered lists.
2026 //
2027 // * For the STW processor:
2028 // * Non MT discovery is enabled at the start of a full GC.
2029 // * Processing and enqueueing during a full GC is non-MT.
2030 // * During a full GC, references are processed after marking.
2031 //
2032 // * Discovery (may or may not be MT) is enabled at the start
2033 // of an incremental evacuation pause.
2034 // * References are processed near the end of a STW evacuation pause.
2035 // * For both types of GC:
2036 // * Discovery is atomic - i.e. not concurrent.
2037 // * Reference discovery will not need a barrier.
2038
2039 MemRegion mr = reserved_region();
2040
2041 // Concurrent Mark ref processor
2042 _ref_processor_cm =
2043 new ReferenceProcessor(mr, // span
2044 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2045 // mt processing
2046 ParallelGCThreads,
2047 // degree of mt processing
2048 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2049 // mt discovery
2050 MAX2(ParallelGCThreads, ConcGCThreads),
2051 // degree of mt discovery
2052 false,
2053 // Reference discovery is not atomic
2054 &_is_alive_closure_cm);
2055 // is alive closure
2056 // (for efficiency/performance)
2057
2058 // STW ref processor
2059 _ref_processor_stw =
2060 new ReferenceProcessor(mr, // span
2061 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2062 // mt processing
2063 ParallelGCThreads,
2064 // degree of mt processing
2065 (ParallelGCThreads > 1),
2066 // mt discovery
2067 ParallelGCThreads,
2068 // degree of mt discovery
2069 true,
2070 // Reference discovery is atomic
2071 &_is_alive_closure_stw);
2072 // is alive closure
2073 // (for efficiency/performance)
2074 }
2075
2076 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2077 return _collector_policy;
2078 }
2079
2080 size_t G1CollectedHeap::capacity() const {
2081 return _hrm.length() * HeapRegion::GrainBytes;
2082 }
2083
2084 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2085 hr->reset_gc_time_stamp();
2086 }
2087
2088 #ifndef PRODUCT
2089
2090 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2091 private:
2092 unsigned _gc_time_stamp;
2093 bool _failures;
2094
2095 public:
2096 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2097 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2098
2099 virtual bool doHeapRegion(HeapRegion* hr) {
2100 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2101 if (_gc_time_stamp != region_gc_time_stamp) {
2102 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2103 region_gc_time_stamp, _gc_time_stamp);
2104 _failures = true;
2105 }
2106 return false;
2107 }
2108
2109 bool failures() { return _failures; }
2110 };
2111
2112 void G1CollectedHeap::check_gc_time_stamps() {
2113 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2114 heap_region_iterate(&cl);
2115 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2116 }
2117 #endif // PRODUCT
2118
2119 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2120 _hot_card_cache->drain(cl, worker_i);
2121 }
2122
2123 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2124 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2125 size_t n_completed_buffers = 0;
2126 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2127 n_completed_buffers++;
2128 }
2129 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2130 dcqs.clear_n_completed_buffers();
2131 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2132 }
2133
2134 // Computes the sum of the storage used by the various regions.
2135 size_t G1CollectedHeap::used() const {
2136 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2137 if (_archive_allocator != NULL) {
2138 result += _archive_allocator->used();
2139 }
2140 return result;
2141 }
2142
2143 size_t G1CollectedHeap::used_unlocked() const {
2144 return _summary_bytes_used;
2145 }
2146
2147 class SumUsedClosure: public HeapRegionClosure {
2148 size_t _used;
2149 public:
2150 SumUsedClosure() : _used(0) {}
2151 bool doHeapRegion(HeapRegion* r) {
2152 _used += r->used();
2153 return false;
2154 }
2155 size_t result() { return _used; }
2156 };
2157
2158 size_t G1CollectedHeap::recalculate_used() const {
2159 double recalculate_used_start = os::elapsedTime();
2160
2161 SumUsedClosure blk;
2162 heap_region_iterate(&blk);
2163
2164 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2165 return blk.result();
2166 }
2167
2168 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2169 switch (cause) {
2170 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2171 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2172 case GCCause::_update_allocation_context_stats_inc: return true;
2173 case GCCause::_wb_conc_mark: return true;
2174 default : return false;
2175 }
2176 }
2177
2178 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2179 switch (cause) {
2180 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2181 case GCCause::_g1_humongous_allocation: return true;
2182 default: return is_user_requested_concurrent_full_gc(cause);
2183 }
2184 }
2185
2186 #ifndef PRODUCT
2187 void G1CollectedHeap::allocate_dummy_regions() {
2188 // Let's fill up most of the region
2189 size_t word_size = HeapRegion::GrainWords - 1024;
2190 // And as a result the region we'll allocate will be humongous.
2191 guarantee(is_humongous(word_size), "sanity");
2192
2193 // _filler_array_max_size is set to humongous object threshold
2194 // but temporarily change it to use CollectedHeap::fill_with_object().
2195 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2196
2197 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2198 // Let's use the existing mechanism for the allocation
2199 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2200 AllocationContext::system());
2201 if (dummy_obj != NULL) {
2202 MemRegion mr(dummy_obj, word_size);
2203 CollectedHeap::fill_with_object(mr);
2204 } else {
2205 // If we can't allocate once, we probably cannot allocate
2206 // again. Let's get out of the loop.
2207 break;
2208 }
2209 }
2210 }
2211 #endif // !PRODUCT
2212
2213 void G1CollectedHeap::increment_old_marking_cycles_started() {
2214 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2215 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2216 "Wrong marking cycle count (started: %d, completed: %d)",
2217 _old_marking_cycles_started, _old_marking_cycles_completed);
2218
2219 _old_marking_cycles_started++;
2220 }
2221
2222 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2223 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2224
2225 // We assume that if concurrent == true, then the caller is a
2226 // concurrent thread that was joined the Suspendible Thread
2227 // Set. If there's ever a cheap way to check this, we should add an
2228 // assert here.
2229
2230 // Given that this method is called at the end of a Full GC or of a
2231 // concurrent cycle, and those can be nested (i.e., a Full GC can
2232 // interrupt a concurrent cycle), the number of full collections
2233 // completed should be either one (in the case where there was no
2234 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2235 // behind the number of full collections started.
2236
2237 // This is the case for the inner caller, i.e. a Full GC.
2238 assert(concurrent ||
2239 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2240 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2241 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2242 "is inconsistent with _old_marking_cycles_completed = %u",
2243 _old_marking_cycles_started, _old_marking_cycles_completed);
2244
2245 // This is the case for the outer caller, i.e. the concurrent cycle.
2246 assert(!concurrent ||
2247 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2248 "for outer caller (concurrent cycle): "
2249 "_old_marking_cycles_started = %u "
2250 "is inconsistent with _old_marking_cycles_completed = %u",
2251 _old_marking_cycles_started, _old_marking_cycles_completed);
2252
2253 _old_marking_cycles_completed += 1;
2254
2255 // We need to clear the "in_progress" flag in the CM thread before
2256 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2257 // is set) so that if a waiter requests another System.gc() it doesn't
2258 // incorrectly see that a marking cycle is still in progress.
2259 if (concurrent) {
2260 _cmThread->set_idle();
2261 }
2262
2263 // This notify_all() will ensure that a thread that called
2264 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2265 // and it's waiting for a full GC to finish will be woken up. It is
2266 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2267 FullGCCount_lock->notify_all();
2268 }
2269
2270 void G1CollectedHeap::collect(GCCause::Cause cause) {
2271 assert_heap_not_locked();
2272
2273 uint gc_count_before;
2274 uint old_marking_count_before;
2275 uint full_gc_count_before;
2276 bool retry_gc;
2277
2278 do {
2279 retry_gc = false;
2280
2281 {
2282 MutexLocker ml(Heap_lock);
2283
2284 // Read the GC count while holding the Heap_lock
2285 gc_count_before = total_collections();
2286 full_gc_count_before = total_full_collections();
2287 old_marking_count_before = _old_marking_cycles_started;
2288 }
2289
2290 if (should_do_concurrent_full_gc(cause)) {
2291 // Schedule an initial-mark evacuation pause that will start a
2292 // concurrent cycle. We're setting word_size to 0 which means that
2293 // we are not requesting a post-GC allocation.
2294 VM_G1IncCollectionPause op(gc_count_before,
2295 0, /* word_size */
2296 true, /* should_initiate_conc_mark */
2297 g1_policy()->max_pause_time_ms(),
2298 cause);
2299 op.set_allocation_context(AllocationContext::current());
2300
2301 VMThread::execute(&op);
2302 if (!op.pause_succeeded()) {
2303 if (old_marking_count_before == _old_marking_cycles_started) {
2304 retry_gc = op.should_retry_gc();
2305 } else {
2306 // A Full GC happened while we were trying to schedule the
2307 // initial-mark GC. No point in starting a new cycle given
2308 // that the whole heap was collected anyway.
2309 }
2310
2311 if (retry_gc) {
2312 if (GCLocker::is_active_and_needs_gc()) {
2313 GCLocker::stall_until_clear();
2314 }
2315 }
2316 }
2317 } else {
2318 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2319 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2320
2321 // Schedule a standard evacuation pause. We're setting word_size
2322 // to 0 which means that we are not requesting a post-GC allocation.
2323 VM_G1IncCollectionPause op(gc_count_before,
2324 0, /* word_size */
2325 false, /* should_initiate_conc_mark */
2326 g1_policy()->max_pause_time_ms(),
2327 cause);
2328 VMThread::execute(&op);
2329 } else {
2330 // Schedule a Full GC.
2331 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2332 VMThread::execute(&op);
2333 }
2334 }
2335 } while (retry_gc);
2336 }
2337
2338 bool G1CollectedHeap::is_in(const void* p) const {
2339 if (_hrm.reserved().contains(p)) {
2340 // Given that we know that p is in the reserved space,
2341 // heap_region_containing() should successfully
2342 // return the containing region.
2343 HeapRegion* hr = heap_region_containing(p);
2344 return hr->is_in(p);
2345 } else {
2346 return false;
2347 }
2348 }
2349
2350 #ifdef ASSERT
2351 bool G1CollectedHeap::is_in_exact(const void* p) const {
2352 bool contains = reserved_region().contains(p);
2353 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2354 if (contains && available) {
2355 return true;
2356 } else {
2357 return false;
2358 }
2359 }
2360 #endif
2361
2362 // Iteration functions.
2363
2364 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2365
2366 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2367 ExtendedOopClosure* _cl;
2368 public:
2369 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2370 bool doHeapRegion(HeapRegion* r) {
2371 if (!r->is_continues_humongous()) {
2372 r->oop_iterate(_cl);
2373 }
2374 return false;
2375 }
2376 };
2377
2378 // Iterates an ObjectClosure over all objects within a HeapRegion.
2379
2380 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2381 ObjectClosure* _cl;
2382 public:
2383 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2384 bool doHeapRegion(HeapRegion* r) {
2385 if (!r->is_continues_humongous()) {
2386 r->object_iterate(_cl);
2387 }
2388 return false;
2389 }
2390 };
2391
2392 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2393 IterateObjectClosureRegionClosure blk(cl);
2394 heap_region_iterate(&blk);
2395 }
2396
2397 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2398 _hrm.iterate(cl);
2399 }
2400
2401 void
2402 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2403 uint worker_id,
2404 HeapRegionClaimer *hrclaimer,
2405 bool concurrent) const {
2406 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2407 }
2408
2409 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2410 _collection_set.iterate(cl);
2411 }
2412
2413 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2414 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2415 }
2416
2417 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2418 HeapRegion* result = _hrm.next_region_in_heap(from);
2419 while (result != NULL && result->is_pinned()) {
2420 result = _hrm.next_region_in_heap(result);
2421 }
2422 return result;
2423 }
2424
2425 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2426 HeapRegion* hr = heap_region_containing(addr);
2427 return hr->block_start(addr);
2428 }
2429
2430 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2431 HeapRegion* hr = heap_region_containing(addr);
2432 return hr->block_size(addr);
2433 }
2434
2435 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2436 HeapRegion* hr = heap_region_containing(addr);
2437 return hr->block_is_obj(addr);
2438 }
2439
2440 bool G1CollectedHeap::supports_tlab_allocation() const {
2441 return true;
2442 }
2443
2444 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2445 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2446 }
2447
2448 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2449 return _eden.length() * HeapRegion::GrainBytes;
2450 }
2451
2452 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2453 // must be equal to the humongous object limit.
2454 size_t G1CollectedHeap::max_tlab_size() const {
2455 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2456 }
2457
2458 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2459 AllocationContext_t context = AllocationContext::current();
2460 return _allocator->unsafe_max_tlab_alloc(context);
2461 }
2462
2463 size_t G1CollectedHeap::max_capacity() const {
2464 return _hrm.reserved().byte_size();
2465 }
2466
2467 jlong G1CollectedHeap::millis_since_last_gc() {
2468 // See the notes in GenCollectedHeap::millis_since_last_gc()
2469 // for more information about the implementation.
2470 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2471 _g1_policy->collection_pause_end_millis();
2472 if (ret_val < 0) {
2473 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2474 ". returning zero instead.", ret_val);
2475 return 0;
2476 }
2477 return ret_val;
2478 }
2479
2480 void G1CollectedHeap::prepare_for_verify() {
2481 _verifier->prepare_for_verify();
2482 }
2483
2484 void G1CollectedHeap::verify(VerifyOption vo) {
2485 _verifier->verify(vo);
2486 }
2487
2488 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2489 return true;
2490 }
2491
2492 const char* const* G1CollectedHeap::concurrent_phases() const {
2493 return _cmThread->concurrent_phases();
2494 }
2495
2496 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2497 return _cmThread->request_concurrent_phase(phase);
2498 }
2499
2500 class PrintRegionClosure: public HeapRegionClosure {
2501 outputStream* _st;
2502 public:
2503 PrintRegionClosure(outputStream* st) : _st(st) {}
2504 bool doHeapRegion(HeapRegion* r) {
2505 r->print_on(_st);
2506 return false;
2507 }
2508 };
2509
2510 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2511 const HeapRegion* hr,
2512 const VerifyOption vo) const {
2513 switch (vo) {
2514 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2515 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2516 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2517 default: ShouldNotReachHere();
2518 }
2519 return false; // keep some compilers happy
2520 }
2521
2522 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2523 const VerifyOption vo) const {
2524 switch (vo) {
2525 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2526 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2527 case VerifyOption_G1UseMarkWord: {
2528 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2529 return !obj->is_gc_marked() && !hr->is_archive();
2530 }
2531 default: ShouldNotReachHere();
2532 }
2533 return false; // keep some compilers happy
2534 }
2535
2536 void G1CollectedHeap::print_heap_regions() const {
2537 Log(gc, heap, region) log;
2538 if (log.is_trace()) {
2539 ResourceMark rm;
2540 print_regions_on(log.trace_stream());
2541 }
2542 }
2543
2544 void G1CollectedHeap::print_on(outputStream* st) const {
2545 st->print(" %-20s", "garbage-first heap");
2546 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2547 capacity()/K, used_unlocked()/K);
2548 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2549 p2i(_hrm.reserved().start()),
2550 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2551 p2i(_hrm.reserved().end()));
2552 st->cr();
2553 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2554 uint young_regions = young_regions_count();
2555 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2556 (size_t) young_regions * HeapRegion::GrainBytes / K);
2557 uint survivor_regions = survivor_regions_count();
2558 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2559 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2560 st->cr();
2561 MetaspaceAux::print_on(st);
2562 }
2563
2564 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2565 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2566 "HS=humongous(starts), HC=humongous(continues), "
2567 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2568 "AC=allocation context, "
2569 "TAMS=top-at-mark-start (previous, next)");
2570 PrintRegionClosure blk(st);
2571 heap_region_iterate(&blk);
2572 }
2573
2574 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2575 print_on(st);
2576
2577 // Print the per-region information.
2578 print_regions_on(st);
2579 }
2580
2581 void G1CollectedHeap::print_on_error(outputStream* st) const {
2582 this->CollectedHeap::print_on_error(st);
2583
2584 if (_cm != NULL) {
2585 st->cr();
2586 _cm->print_on_error(st);
2587 }
2588 }
2589
2590 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2591 workers()->print_worker_threads_on(st);
2592 _cmThread->print_on(st);
2593 st->cr();
2594 _cm->print_worker_threads_on(st);
2595 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2596 if (G1StringDedup::is_enabled()) {
2597 G1StringDedup::print_worker_threads_on(st);
2598 }
2599 }
2600
2601 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2602 workers()->threads_do(tc);
2603 tc->do_thread(_cmThread);
2604 _cm->threads_do(tc);
2605 _cg1r->threads_do(tc); // also iterates over the sample thread
2606 if (G1StringDedup::is_enabled()) {
2607 G1StringDedup::threads_do(tc);
2608 }
2609 }
2610
2611 void G1CollectedHeap::print_tracing_info() const {
2612 g1_rem_set()->print_summary_info();
2613 concurrent_mark()->print_summary_info();
2614 }
2615
2616 #ifndef PRODUCT
2617 // Helpful for debugging RSet issues.
2618
2619 class PrintRSetsClosure : public HeapRegionClosure {
2620 private:
2621 const char* _msg;
2622 size_t _occupied_sum;
2623
2624 public:
2625 bool doHeapRegion(HeapRegion* r) {
2626 HeapRegionRemSet* hrrs = r->rem_set();
2627 size_t occupied = hrrs->occupied();
2628 _occupied_sum += occupied;
2629
2630 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2631 if (occupied == 0) {
2632 tty->print_cr(" RSet is empty");
2633 } else {
2634 hrrs->print();
2635 }
2636 tty->print_cr("----------");
2637 return false;
2638 }
2639
2640 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2641 tty->cr();
2642 tty->print_cr("========================================");
2643 tty->print_cr("%s", msg);
2644 tty->cr();
2645 }
2646
2647 ~PrintRSetsClosure() {
2648 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2649 tty->print_cr("========================================");
2650 tty->cr();
2651 }
2652 };
2653
2654 void G1CollectedHeap::print_cset_rsets() {
2655 PrintRSetsClosure cl("Printing CSet RSets");
2656 collection_set_iterate(&cl);
2657 }
2658
2659 void G1CollectedHeap::print_all_rsets() {
2660 PrintRSetsClosure cl("Printing All RSets");;
2661 heap_region_iterate(&cl);
2662 }
2663 #endif // PRODUCT
2664
2665 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2666
2667 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2668 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2669 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2670
2671 size_t eden_capacity_bytes =
2672 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2673
2674 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2675 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2676 eden_capacity_bytes, survivor_used_bytes, num_regions());
2677 }
2678
2679 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2680 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2681 stats->unused(), stats->used(), stats->region_end_waste(),
2682 stats->regions_filled(), stats->direct_allocated(),
2683 stats->failure_used(), stats->failure_waste());
2684 }
2685
2686 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2687 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2688 gc_tracer->report_gc_heap_summary(when, heap_summary);
2689
2690 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2691 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2692 }
2693
2694 G1CollectedHeap* G1CollectedHeap::heap() {
2695 CollectedHeap* heap = Universe::heap();
2696 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2697 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2698 return (G1CollectedHeap*)heap;
2699 }
2700
2701 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2702 // always_do_update_barrier = false;
2703 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2704
2705 double start = os::elapsedTime();
2706 // Fill TLAB's and such
2707 accumulate_statistics_all_tlabs();
2708 ensure_parsability(true);
2709 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2710
2711 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2712 }
2713
2714 void G1CollectedHeap::gc_epilogue(bool full) {
2715 // we are at the end of the GC. Total collections has already been increased.
2716 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2717
2718 // FIXME: what is this about?
2719 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2720 // is set.
2721 #if defined(COMPILER2) || INCLUDE_JVMCI
2722 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2723 #endif
2724 // always_do_update_barrier = true;
2725
2726 double start = os::elapsedTime();
2727 resize_all_tlabs();
2728 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2729
2730 allocation_context_stats().update(full);
2731
2732 // We have just completed a GC. Update the soft reference
2733 // policy with the new heap occupancy
2734 Universe::update_heap_info_at_gc();
2735 }
2736
2737 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2738 uint gc_count_before,
2739 bool* succeeded,
2740 GCCause::Cause gc_cause) {
2741 assert_heap_not_locked_and_not_at_safepoint();
2742 VM_G1IncCollectionPause op(gc_count_before,
2743 word_size,
2744 false, /* should_initiate_conc_mark */
2745 g1_policy()->max_pause_time_ms(),
2746 gc_cause);
2747
2748 op.set_allocation_context(AllocationContext::current());
2749 VMThread::execute(&op);
2750
2751 HeapWord* result = op.result();
2752 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2753 assert(result == NULL || ret_succeeded,
2754 "the result should be NULL if the VM did not succeed");
2755 *succeeded = ret_succeeded;
2756
2757 assert_heap_not_locked();
2758 return result;
2759 }
2760
2761 void
2762 G1CollectedHeap::doConcurrentMark() {
2763 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2764 if (!_cmThread->in_progress()) {
2765 _cmThread->set_started();
2766 CGC_lock->notify();
2767 }
2768 }
2769
2770 size_t G1CollectedHeap::pending_card_num() {
2771 size_t extra_cards = 0;
2772 JavaThread *curr = Threads::first();
2773 while (curr != NULL) {
2774 DirtyCardQueue& dcq = curr->dirty_card_queue();
2775 extra_cards += dcq.size();
2776 curr = curr->next();
2777 }
2778 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2779 size_t buffer_size = dcqs.buffer_size();
2780 size_t buffer_num = dcqs.completed_buffers_num();
2781
2782 return buffer_size * buffer_num + extra_cards;
2783 }
2784
2785 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2786 private:
2787 size_t _total_humongous;
2788 size_t _candidate_humongous;
2789
2790 DirtyCardQueue _dcq;
2791
2792 // We don't nominate objects with many remembered set entries, on
2793 // the assumption that such objects are likely still live.
2794 bool is_remset_small(HeapRegion* region) const {
2795 HeapRegionRemSet* const rset = region->rem_set();
2796 return G1EagerReclaimHumongousObjectsWithStaleRefs
2797 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2798 : rset->is_empty();
2799 }
2800
2801 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2802 assert(region->is_starts_humongous(), "Must start a humongous object");
2803
2804 oop obj = oop(region->bottom());
2805
2806 // Dead objects cannot be eager reclaim candidates. Due to class
2807 // unloading it is unsafe to query their classes so we return early.
2808 if (heap->is_obj_dead(obj, region)) {
2809 return false;
2810 }
2811
2812 // Candidate selection must satisfy the following constraints
2813 // while concurrent marking is in progress:
2814 //
2815 // * In order to maintain SATB invariants, an object must not be
2816 // reclaimed if it was allocated before the start of marking and
2817 // has not had its references scanned. Such an object must have
2818 // its references (including type metadata) scanned to ensure no
2819 // live objects are missed by the marking process. Objects
2820 // allocated after the start of concurrent marking don't need to
2821 // be scanned.
2822 //
2823 // * An object must not be reclaimed if it is on the concurrent
2824 // mark stack. Objects allocated after the start of concurrent
2825 // marking are never pushed on the mark stack.
2826 //
2827 // Nominating only objects allocated after the start of concurrent
2828 // marking is sufficient to meet both constraints. This may miss
2829 // some objects that satisfy the constraints, but the marking data
2830 // structures don't support efficiently performing the needed
2831 // additional tests or scrubbing of the mark stack.
2832 //
2833 // However, we presently only nominate is_typeArray() objects.
2834 // A humongous object containing references induces remembered
2835 // set entries on other regions. In order to reclaim such an
2836 // object, those remembered sets would need to be cleaned up.
2837 //
2838 // We also treat is_typeArray() objects specially, allowing them
2839 // to be reclaimed even if allocated before the start of
2840 // concurrent mark. For this we rely on mark stack insertion to
2841 // exclude is_typeArray() objects, preventing reclaiming an object
2842 // that is in the mark stack. We also rely on the metadata for
2843 // such objects to be built-in and so ensured to be kept live.
2844 // Frequent allocation and drop of large binary blobs is an
2845 // important use case for eager reclaim, and this special handling
2846 // may reduce needed headroom.
2847
2848 return obj->is_typeArray() && is_remset_small(region);
2849 }
2850
2851 public:
2852 RegisterHumongousWithInCSetFastTestClosure()
2853 : _total_humongous(0),
2854 _candidate_humongous(0),
2855 _dcq(&JavaThread::dirty_card_queue_set()) {
2856 }
2857
2858 virtual bool doHeapRegion(HeapRegion* r) {
2859 if (!r->is_starts_humongous()) {
2860 return false;
2861 }
2862 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2863
2864 bool is_candidate = humongous_region_is_candidate(g1h, r);
2865 uint rindex = r->hrm_index();
2866 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2867 if (is_candidate) {
2868 _candidate_humongous++;
2869 g1h->register_humongous_region_with_cset(rindex);
2870 // Is_candidate already filters out humongous object with large remembered sets.
2871 // If we have a humongous object with a few remembered sets, we simply flush these
2872 // remembered set entries into the DCQS. That will result in automatic
2873 // re-evaluation of their remembered set entries during the following evacuation
2874 // phase.
2875 if (!r->rem_set()->is_empty()) {
2876 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2877 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2878 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2879 HeapRegionRemSetIterator hrrs(r->rem_set());
2880 size_t card_index;
2881 while (hrrs.has_next(card_index)) {
2882 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2883 // The remembered set might contain references to already freed
2884 // regions. Filter out such entries to avoid failing card table
2885 // verification.
2886 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2887 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2888 *card_ptr = CardTableModRefBS::dirty_card_val();
2889 _dcq.enqueue(card_ptr);
2890 }
2891 }
2892 }
2893 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2894 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2895 hrrs.n_yielded(), r->rem_set()->occupied());
2896 r->rem_set()->clear_locked();
2897 }
2898 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2899 }
2900 _total_humongous++;
2901
2902 return false;
2903 }
2904
2905 size_t total_humongous() const { return _total_humongous; }
2906 size_t candidate_humongous() const { return _candidate_humongous; }
2907
2908 void flush_rem_set_entries() { _dcq.flush(); }
2909 };
2910
2911 void G1CollectedHeap::register_humongous_regions_with_cset() {
2912 if (!G1EagerReclaimHumongousObjects) {
2913 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2914 return;
2915 }
2916 double time = os::elapsed_counter();
2917
2918 // Collect reclaim candidate information and register candidates with cset.
2919 RegisterHumongousWithInCSetFastTestClosure cl;
2920 heap_region_iterate(&cl);
2921
2922 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2923 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2924 cl.total_humongous(),
2925 cl.candidate_humongous());
2926 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2927
2928 // Finally flush all remembered set entries to re-check into the global DCQS.
2929 cl.flush_rem_set_entries();
2930 }
2931
2932 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2933 public:
2934 bool doHeapRegion(HeapRegion* hr) {
2935 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2936 hr->verify_rem_set();
2937 }
2938 return false;
2939 }
2940 };
2941
2942 uint G1CollectedHeap::num_task_queues() const {
2943 return _task_queues->size();
2944 }
2945
2946 #if TASKQUEUE_STATS
2947 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2948 st->print_raw_cr("GC Task Stats");
2949 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2950 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2951 }
2952
2953 void G1CollectedHeap::print_taskqueue_stats() const {
2954 if (!log_is_enabled(Trace, gc, task, stats)) {
2955 return;
2956 }
2957 Log(gc, task, stats) log;
2958 ResourceMark rm;
2959 outputStream* st = log.trace_stream();
2960
2961 print_taskqueue_stats_hdr(st);
2962
2963 TaskQueueStats totals;
2964 const uint n = num_task_queues();
2965 for (uint i = 0; i < n; ++i) {
2966 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2967 totals += task_queue(i)->stats;
2968 }
2969 st->print_raw("tot "); totals.print(st); st->cr();
2970
2971 DEBUG_ONLY(totals.verify());
2972 }
2973
2974 void G1CollectedHeap::reset_taskqueue_stats() {
2975 const uint n = num_task_queues();
2976 for (uint i = 0; i < n; ++i) {
2977 task_queue(i)->stats.reset();
2978 }
2979 }
2980 #endif // TASKQUEUE_STATS
2981
2982 void G1CollectedHeap::wait_for_root_region_scanning() {
2983 double scan_wait_start = os::elapsedTime();
2984 // We have to wait until the CM threads finish scanning the
2985 // root regions as it's the only way to ensure that all the
2986 // objects on them have been correctly scanned before we start
2987 // moving them during the GC.
2988 bool waited = _cm->root_regions()->wait_until_scan_finished();
2989 double wait_time_ms = 0.0;
2990 if (waited) {
2991 double scan_wait_end = os::elapsedTime();
2992 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2993 }
2994 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2995 }
2996
2997 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2998 private:
2999 G1HRPrinter* _hr_printer;
3000 public:
3001 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
3002
3003 virtual bool doHeapRegion(HeapRegion* r) {
3004 _hr_printer->cset(r);
3005 return false;
3006 }
3007 };
3008
3009 void G1CollectedHeap::start_new_collection_set() {
3010 collection_set()->start_incremental_building();
3011
3012 clear_cset_fast_test();
3013
3014 guarantee(_eden.length() == 0, "eden should have been cleared");
3015 g1_policy()->transfer_survivors_to_cset(survivor());
3016 }
3017
3018 bool
3019 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3020 assert_at_safepoint(true /* should_be_vm_thread */);
3021 guarantee(!is_gc_active(), "collection is not reentrant");
3022
3023 if (GCLocker::check_active_before_gc()) {
3024 return false;
3025 }
3026
3027 _gc_timer_stw->register_gc_start();
3028
3029 GCIdMark gc_id_mark;
3030 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3031
3032 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3033 ResourceMark rm;
3034
3035 g1_policy()->note_gc_start();
3036
3037 wait_for_root_region_scanning();
3038
3039 print_heap_before_gc();
3040 print_heap_regions();
3041 trace_heap_before_gc(_gc_tracer_stw);
3042
3043 _verifier->verify_region_sets_optional();
3044 _verifier->verify_dirty_young_regions();
3045
3046 // We should not be doing initial mark unless the conc mark thread is running
3047 if (!_cmThread->should_terminate()) {
3048 // This call will decide whether this pause is an initial-mark
3049 // pause. If it is, during_initial_mark_pause() will return true
3050 // for the duration of this pause.
3051 g1_policy()->decide_on_conc_mark_initiation();
3052 }
3053
3054 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3055 assert(!collector_state()->during_initial_mark_pause() ||
3056 collector_state()->gcs_are_young(), "sanity");
3057
3058 // We also do not allow mixed GCs during marking.
3059 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3060
3061 // Record whether this pause is an initial mark. When the current
3062 // thread has completed its logging output and it's safe to signal
3063 // the CM thread, the flag's value in the policy has been reset.
3064 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3065
3066 // Inner scope for scope based logging, timers, and stats collection
3067 {
3068 EvacuationInfo evacuation_info;
3069
3070 if (collector_state()->during_initial_mark_pause()) {
3071 // We are about to start a marking cycle, so we increment the
3072 // full collection counter.
3073 increment_old_marking_cycles_started();
3074 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3075 }
3076
3077 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3078
3079 GCTraceCPUTime tcpu;
3080
3081 FormatBuffer<> gc_string("Pause ");
3082 if (collector_state()->during_initial_mark_pause()) {
3083 gc_string.append("Initial Mark");
3084 } else if (collector_state()->gcs_are_young()) {
3085 gc_string.append("Young");
3086 } else {
3087 gc_string.append("Mixed");
3088 }
3089 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3090
3091 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3092 workers()->active_workers(),
3093 Threads::number_of_non_daemon_threads());
3094 workers()->update_active_workers(active_workers);
3095 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3096
3097 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3098 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3099
3100 // If the secondary_free_list is not empty, append it to the
3101 // free_list. No need to wait for the cleanup operation to finish;
3102 // the region allocation code will check the secondary_free_list
3103 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3104 // set, skip this step so that the region allocation code has to
3105 // get entries from the secondary_free_list.
3106 if (!G1StressConcRegionFreeing) {
3107 append_secondary_free_list_if_not_empty_with_lock();
3108 }
3109
3110 G1HeapTransition heap_transition(this);
3111 size_t heap_used_bytes_before_gc = used();
3112
3113 // Don't dynamically change the number of GC threads this early. A value of
3114 // 0 is used to indicate serial work. When parallel work is done,
3115 // it will be set.
3116
3117 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3118 IsGCActiveMark x;
3119
3120 gc_prologue(false);
3121 increment_total_collections(false /* full gc */);
3122 increment_gc_time_stamp();
3123
3124 if (VerifyRememberedSets) {
3125 log_info(gc, verify)("[Verifying RemSets before GC]");
3126 VerifyRegionRemSetClosure v_cl;
3127 heap_region_iterate(&v_cl);
3128 }
3129
3130 _verifier->verify_before_gc();
3131
3132 _verifier->check_bitmaps("GC Start");
3133
3134 #if defined(COMPILER2) || INCLUDE_JVMCI
3135 DerivedPointerTable::clear();
3136 #endif
3137
3138 // Please see comment in g1CollectedHeap.hpp and
3139 // G1CollectedHeap::ref_processing_init() to see how
3140 // reference processing currently works in G1.
3141
3142 // Enable discovery in the STW reference processor
3143 if (g1_policy()->should_process_references()) {
3144 ref_processor_stw()->enable_discovery();
3145 } else {
3146 ref_processor_stw()->disable_discovery();
3147 }
3148
3149 {
3150 // We want to temporarily turn off discovery by the
3151 // CM ref processor, if necessary, and turn it back on
3152 // on again later if we do. Using a scoped
3153 // NoRefDiscovery object will do this.
3154 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3155
3156 // Forget the current alloc region (we might even choose it to be part
3157 // of the collection set!).
3158 _allocator->release_mutator_alloc_region();
3159
3160 // This timing is only used by the ergonomics to handle our pause target.
3161 // It is unclear why this should not include the full pause. We will
3162 // investigate this in CR 7178365.
3163 //
3164 // Preserving the old comment here if that helps the investigation:
3165 //
3166 // The elapsed time induced by the start time below deliberately elides
3167 // the possible verification above.
3168 double sample_start_time_sec = os::elapsedTime();
3169
3170 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3171
3172 if (collector_state()->during_initial_mark_pause()) {
3173 concurrent_mark()->checkpointRootsInitialPre();
3174 }
3175
3176 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3177
3178 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3179
3180 // Make sure the remembered sets are up to date. This needs to be
3181 // done before register_humongous_regions_with_cset(), because the
3182 // remembered sets are used there to choose eager reclaim candidates.
3183 // If the remembered sets are not up to date we might miss some
3184 // entries that need to be handled.
3185 g1_rem_set()->cleanupHRRS();
3186
3187 register_humongous_regions_with_cset();
3188
3189 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3190
3191 // We call this after finalize_cset() to
3192 // ensure that the CSet has been finalized.
3193 _cm->verify_no_cset_oops();
3194
3195 if (_hr_printer.is_active()) {
3196 G1PrintCollectionSetClosure cl(&_hr_printer);
3197 _collection_set.iterate(&cl);
3198 }
3199
3200 // Initialize the GC alloc regions.
3201 _allocator->init_gc_alloc_regions(evacuation_info);
3202
3203 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3204 pre_evacuate_collection_set();
3205
3206 // Actually do the work...
3207 evacuate_collection_set(evacuation_info, &per_thread_states);
3208
3209 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3210
3211 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3212 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3213
3214 eagerly_reclaim_humongous_regions();
3215
3216 record_obj_copy_mem_stats();
3217 _survivor_evac_stats.adjust_desired_plab_sz();
3218 _old_evac_stats.adjust_desired_plab_sz();
3219
3220 double start = os::elapsedTime();
3221 start_new_collection_set();
3222 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3223
3224 if (evacuation_failed()) {
3225 set_used(recalculate_used());
3226 if (_archive_allocator != NULL) {
3227 _archive_allocator->clear_used();
3228 }
3229 for (uint i = 0; i < ParallelGCThreads; i++) {
3230 if (_evacuation_failed_info_array[i].has_failed()) {
3231 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3232 }
3233 }
3234 } else {
3235 // The "used" of the the collection set have already been subtracted
3236 // when they were freed. Add in the bytes evacuated.
3237 increase_used(g1_policy()->bytes_copied_during_gc());
3238 }
3239
3240 if (collector_state()->during_initial_mark_pause()) {
3241 // We have to do this before we notify the CM threads that
3242 // they can start working to make sure that all the
3243 // appropriate initialization is done on the CM object.
3244 concurrent_mark()->checkpointRootsInitialPost();
3245 collector_state()->set_mark_in_progress(true);
3246 // Note that we don't actually trigger the CM thread at
3247 // this point. We do that later when we're sure that
3248 // the current thread has completed its logging output.
3249 }
3250
3251 allocate_dummy_regions();
3252
3253 _allocator->init_mutator_alloc_region();
3254
3255 {
3256 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3257 if (expand_bytes > 0) {
3258 size_t bytes_before = capacity();
3259 // No need for an ergo logging here,
3260 // expansion_amount() does this when it returns a value > 0.
3261 double expand_ms;
3262 if (!expand(expand_bytes, _workers, &expand_ms)) {
3263 // We failed to expand the heap. Cannot do anything about it.
3264 }
3265 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3266 }
3267 }
3268
3269 // We redo the verification but now wrt to the new CSet which
3270 // has just got initialized after the previous CSet was freed.
3271 _cm->verify_no_cset_oops();
3272
3273 // This timing is only used by the ergonomics to handle our pause target.
3274 // It is unclear why this should not include the full pause. We will
3275 // investigate this in CR 7178365.
3276 double sample_end_time_sec = os::elapsedTime();
3277 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3278 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3279 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3280
3281 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3282 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3283
3284 MemoryService::track_memory_usage();
3285
3286 // In prepare_for_verify() below we'll need to scan the deferred
3287 // update buffers to bring the RSets up-to-date if
3288 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3289 // the update buffers we'll probably need to scan cards on the
3290 // regions we just allocated to (i.e., the GC alloc
3291 // regions). However, during the last GC we called
3292 // set_saved_mark() on all the GC alloc regions, so card
3293 // scanning might skip the [saved_mark_word()...top()] area of
3294 // those regions (i.e., the area we allocated objects into
3295 // during the last GC). But it shouldn't. Given that
3296 // saved_mark_word() is conditional on whether the GC time stamp
3297 // on the region is current or not, by incrementing the GC time
3298 // stamp here we invalidate all the GC time stamps on all the
3299 // regions and saved_mark_word() will simply return top() for
3300 // all the regions. This is a nicer way of ensuring this rather
3301 // than iterating over the regions and fixing them. In fact, the
3302 // GC time stamp increment here also ensures that
3303 // saved_mark_word() will return top() between pauses, i.e.,
3304 // during concurrent refinement. So we don't need the
3305 // is_gc_active() check to decided which top to use when
3306 // scanning cards (see CR 7039627).
3307 increment_gc_time_stamp();
3308
3309 if (VerifyRememberedSets) {
3310 log_info(gc, verify)("[Verifying RemSets after GC]");
3311 VerifyRegionRemSetClosure v_cl;
3312 heap_region_iterate(&v_cl);
3313 }
3314
3315 _verifier->verify_after_gc();
3316 _verifier->check_bitmaps("GC End");
3317
3318 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3319 ref_processor_stw()->verify_no_references_recorded();
3320
3321 // CM reference discovery will be re-enabled if necessary.
3322 }
3323
3324 #ifdef TRACESPINNING
3325 ParallelTaskTerminator::print_termination_counts();
3326 #endif
3327
3328 gc_epilogue(false);
3329 }
3330
3331 // Print the remainder of the GC log output.
3332 if (evacuation_failed()) {
3333 log_info(gc)("To-space exhausted");
3334 }
3335
3336 g1_policy()->print_phases();
3337 heap_transition.print();
3338
3339 // It is not yet to safe to tell the concurrent mark to
3340 // start as we have some optional output below. We don't want the
3341 // output from the concurrent mark thread interfering with this
3342 // logging output either.
3343
3344 _hrm.verify_optional();
3345 _verifier->verify_region_sets_optional();
3346
3347 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3348 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3349
3350 print_heap_after_gc();
3351 print_heap_regions();
3352 trace_heap_after_gc(_gc_tracer_stw);
3353
3354 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3355 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3356 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3357 // before any GC notifications are raised.
3358 g1mm()->update_sizes();
3359
3360 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3361 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3362 _gc_timer_stw->register_gc_end();
3363 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3364 }
3365 // It should now be safe to tell the concurrent mark thread to start
3366 // without its logging output interfering with the logging output
3367 // that came from the pause.
3368
3369 if (should_start_conc_mark) {
3370 // CAUTION: after the doConcurrentMark() call below,
3371 // the concurrent marking thread(s) could be running
3372 // concurrently with us. Make sure that anything after
3373 // this point does not assume that we are the only GC thread
3374 // running. Note: of course, the actual marking work will
3375 // not start until the safepoint itself is released in
3376 // SuspendibleThreadSet::desynchronize().
3377 doConcurrentMark();
3378 }
3379
3380 return true;
3381 }
3382
3383 void G1CollectedHeap::remove_self_forwarding_pointers() {
3384 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3385 workers()->run_task(&rsfp_task);
3386 }
3387
3388 void G1CollectedHeap::restore_after_evac_failure() {
3389 double remove_self_forwards_start = os::elapsedTime();
3390
3391 remove_self_forwarding_pointers();
3392 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3393 _preserved_marks_set.restore(&task_executor);
3394
3395 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3396 }
3397
3398 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3399 if (!_evacuation_failed) {
3400 _evacuation_failed = true;
3401 }
3402
3403 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3404 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3405 }
3406
3407 bool G1ParEvacuateFollowersClosure::offer_termination() {
3408 G1ParScanThreadState* const pss = par_scan_state();
3409 start_term_time();
3410 const bool res = terminator()->offer_termination();
3411 end_term_time();
3412 return res;
3413 }
3414
3415 void G1ParEvacuateFollowersClosure::do_void() {
3416 G1ParScanThreadState* const pss = par_scan_state();
3417 pss->trim_queue();
3418 do {
3419 pss->steal_and_trim_queue(queues());
3420 } while (!offer_termination());
3421 }
3422
3423 class G1ParTask : public AbstractGangTask {
3424 protected:
3425 G1CollectedHeap* _g1h;
3426 G1ParScanThreadStateSet* _pss;
3427 RefToScanQueueSet* _queues;
3428 G1RootProcessor* _root_processor;
3429 ParallelTaskTerminator _terminator;
3430 uint _n_workers;
3431
3432 public:
3433 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3434 : AbstractGangTask("G1 collection"),
3435 _g1h(g1h),
3436 _pss(per_thread_states),
3437 _queues(task_queues),
3438 _root_processor(root_processor),
3439 _terminator(n_workers, _queues),
3440 _n_workers(n_workers)
3441 {}
3442
3443 void work(uint worker_id) {
3444 if (worker_id >= _n_workers) return; // no work needed this round
3445
3446 double start_sec = os::elapsedTime();
3447 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3448
3449 {
3450 ResourceMark rm;
3451 HandleMark hm;
3452
3453 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3454
3455 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3456 pss->set_ref_processor(rp);
3457
3458 double start_strong_roots_sec = os::elapsedTime();
3459
3460 _root_processor->evacuate_roots(pss->closures(), worker_id);
3461
3462 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3463
3464 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3465 // treating the nmethods visited to act as roots for concurrent marking.
3466 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3467 // objects copied by the current evacuation.
3468 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3469 pss->closures()->weak_codeblobs(),
3470 worker_id);
3471
3472 _pss->add_cards_scanned(worker_id, cards_scanned);
3473
3474 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3475
3476 double term_sec = 0.0;
3477 size_t evac_term_attempts = 0;
3478 {
3479 double start = os::elapsedTime();
3480 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3481 evac.do_void();
3482
3483 evac_term_attempts = evac.term_attempts();
3484 term_sec = evac.term_time();
3485 double elapsed_sec = os::elapsedTime() - start;
3486 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3487 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3488 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3489 }
3490
3491 assert(pss->queue_is_empty(), "should be empty");
3492
3493 if (log_is_enabled(Debug, gc, task, stats)) {
3494 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3495 size_t lab_waste;
3496 size_t lab_undo_waste;
3497 pss->waste(lab_waste, lab_undo_waste);
3498 _g1h->print_termination_stats(worker_id,
3499 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3500 strong_roots_sec * 1000.0, /* strong roots time */
3501 term_sec * 1000.0, /* evac term time */
3502 evac_term_attempts, /* evac term attempts */
3503 lab_waste, /* alloc buffer waste */
3504 lab_undo_waste /* undo waste */
3505 );
3506 }
3507
3508 // Close the inner scope so that the ResourceMark and HandleMark
3509 // destructors are executed here and are included as part of the
3510 // "GC Worker Time".
3511 }
3512 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3513 }
3514 };
3515
3516 void G1CollectedHeap::print_termination_stats_hdr() {
3517 log_debug(gc, task, stats)("GC Termination Stats");
3518 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3519 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3520 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3521 }
3522
3523 void G1CollectedHeap::print_termination_stats(uint worker_id,
3524 double elapsed_ms,
3525 double strong_roots_ms,
3526 double term_ms,
3527 size_t term_attempts,
3528 size_t alloc_buffer_waste,
3529 size_t undo_waste) const {
3530 log_debug(gc, task, stats)
3531 ("%3d %9.2f %9.2f %6.2f "
3532 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3533 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3534 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3535 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3536 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3537 alloc_buffer_waste * HeapWordSize / K,
3538 undo_waste * HeapWordSize / K);
3539 }
3540
3541 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3542 private:
3543 BoolObjectClosure* _is_alive;
3544 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3545
3546 int _initial_string_table_size;
3547 int _initial_symbol_table_size;
3548
3549 bool _process_strings;
3550 int _strings_processed;
3551 int _strings_removed;
3552
3553 bool _process_symbols;
3554 int _symbols_processed;
3555 int _symbols_removed;
3556
3557 bool _process_string_dedup;
3558
3559 public:
3560 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3561 AbstractGangTask("String/Symbol Unlinking"),
3562 _is_alive(is_alive),
3563 _dedup_closure(is_alive, NULL, false),
3564 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3565 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3566 _process_string_dedup(process_string_dedup) {
3567
3568 _initial_string_table_size = StringTable::the_table()->table_size();
3569 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3570 if (process_strings) {
3571 StringTable::clear_parallel_claimed_index();
3572 }
3573 if (process_symbols) {
3574 SymbolTable::clear_parallel_claimed_index();
3575 }
3576 }
3577
3578 ~G1StringAndSymbolCleaningTask() {
3579 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3580 "claim value %d after unlink less than initial string table size %d",
3581 StringTable::parallel_claimed_index(), _initial_string_table_size);
3582 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3583 "claim value %d after unlink less than initial symbol table size %d",
3584 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3585
3586 log_info(gc, stringtable)(
3587 "Cleaned string and symbol table, "
3588 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3589 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3590 strings_processed(), strings_removed(),
3591 symbols_processed(), symbols_removed());
3592 }
3593
3594 void work(uint worker_id) {
3595 int strings_processed = 0;
3596 int strings_removed = 0;
3597 int symbols_processed = 0;
3598 int symbols_removed = 0;
3599 if (_process_strings) {
3600 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3601 Atomic::add(strings_processed, &_strings_processed);
3602 Atomic::add(strings_removed, &_strings_removed);
3603 }
3604 if (_process_symbols) {
3605 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3606 Atomic::add(symbols_processed, &_symbols_processed);
3607 Atomic::add(symbols_removed, &_symbols_removed);
3608 }
3609 if (_process_string_dedup) {
3610 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3611 }
3612 }
3613
3614 size_t strings_processed() const { return (size_t)_strings_processed; }
3615 size_t strings_removed() const { return (size_t)_strings_removed; }
3616
3617 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3618 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3619 };
3620
3621 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3622 private:
3623 static Monitor* _lock;
3624
3625 BoolObjectClosure* const _is_alive;
3626 const bool _unloading_occurred;
3627 const uint _num_workers;
3628
3629 // Variables used to claim nmethods.
3630 CompiledMethod* _first_nmethod;
3631 volatile CompiledMethod* _claimed_nmethod;
3632
3633 // The list of nmethods that need to be processed by the second pass.
3634 volatile CompiledMethod* _postponed_list;
3635 volatile uint _num_entered_barrier;
3636
3637 public:
3638 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3639 _is_alive(is_alive),
3640 _unloading_occurred(unloading_occurred),
3641 _num_workers(num_workers),
3642 _first_nmethod(NULL),
3643 _claimed_nmethod(NULL),
3644 _postponed_list(NULL),
3645 _num_entered_barrier(0)
3646 {
3647 CompiledMethod::increase_unloading_clock();
3648 // Get first alive nmethod
3649 CompiledMethodIterator iter = CompiledMethodIterator();
3650 if(iter.next_alive()) {
3651 _first_nmethod = iter.method();
3652 }
3653 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3654 }
3655
3656 ~G1CodeCacheUnloadingTask() {
3657 CodeCache::verify_clean_inline_caches();
3658
3659 CodeCache::set_needs_cache_clean(false);
3660 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3661
3662 CodeCache::verify_icholder_relocations();
3663 }
3664
3665 private:
3666 void add_to_postponed_list(CompiledMethod* nm) {
3667 CompiledMethod* old;
3668 do {
3669 old = (CompiledMethod*)_postponed_list;
3670 nm->set_unloading_next(old);
3671 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3672 }
3673
3674 void clean_nmethod(CompiledMethod* nm) {
3675 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3676
3677 if (postponed) {
3678 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3679 add_to_postponed_list(nm);
3680 }
3681
3682 // Mark that this thread has been cleaned/unloaded.
3683 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3684 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3685 }
3686
3687 void clean_nmethod_postponed(CompiledMethod* nm) {
3688 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3689 }
3690
3691 static const int MaxClaimNmethods = 16;
3692
3693 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3694 CompiledMethod* first;
3695 CompiledMethodIterator last;
3696
3697 do {
3698 *num_claimed_nmethods = 0;
3699
3700 first = (CompiledMethod*)_claimed_nmethod;
3701 last = CompiledMethodIterator(first);
3702
3703 if (first != NULL) {
3704
3705 for (int i = 0; i < MaxClaimNmethods; i++) {
3706 if (!last.next_alive()) {
3707 break;
3708 }
3709 claimed_nmethods[i] = last.method();
3710 (*num_claimed_nmethods)++;
3711 }
3712 }
3713
3714 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3715 }
3716
3717 CompiledMethod* claim_postponed_nmethod() {
3718 CompiledMethod* claim;
3719 CompiledMethod* next;
3720
3721 do {
3722 claim = (CompiledMethod*)_postponed_list;
3723 if (claim == NULL) {
3724 return NULL;
3725 }
3726
3727 next = claim->unloading_next();
3728
3729 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3730
3731 return claim;
3732 }
3733
3734 public:
3735 // Mark that we're done with the first pass of nmethod cleaning.
3736 void barrier_mark(uint worker_id) {
3737 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3738 _num_entered_barrier++;
3739 if (_num_entered_barrier == _num_workers) {
3740 ml.notify_all();
3741 }
3742 }
3743
3744 // See if we have to wait for the other workers to
3745 // finish their first-pass nmethod cleaning work.
3746 void barrier_wait(uint worker_id) {
3747 if (_num_entered_barrier < _num_workers) {
3748 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3749 while (_num_entered_barrier < _num_workers) {
3750 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3751 }
3752 }
3753 }
3754
3755 // Cleaning and unloading of nmethods. Some work has to be postponed
3756 // to the second pass, when we know which nmethods survive.
3757 void work_first_pass(uint worker_id) {
3758 // The first nmethods is claimed by the first worker.
3759 if (worker_id == 0 && _first_nmethod != NULL) {
3760 clean_nmethod(_first_nmethod);
3761 _first_nmethod = NULL;
3762 }
3763
3764 int num_claimed_nmethods;
3765 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3766
3767 while (true) {
3768 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3769
3770 if (num_claimed_nmethods == 0) {
3771 break;
3772 }
3773
3774 for (int i = 0; i < num_claimed_nmethods; i++) {
3775 clean_nmethod(claimed_nmethods[i]);
3776 }
3777 }
3778 }
3779
3780 void work_second_pass(uint worker_id) {
3781 CompiledMethod* nm;
3782 // Take care of postponed nmethods.
3783 while ((nm = claim_postponed_nmethod()) != NULL) {
3784 clean_nmethod_postponed(nm);
3785 }
3786 }
3787 };
3788
3789 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3790
3791 class G1KlassCleaningTask : public StackObj {
3792 BoolObjectClosure* _is_alive;
3793 volatile jint _clean_klass_tree_claimed;
3794 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3795
3796 public:
3797 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3798 _is_alive(is_alive),
3799 _clean_klass_tree_claimed(0),
3800 _klass_iterator() {
3801 }
3802
3803 private:
3804 bool claim_clean_klass_tree_task() {
3805 if (_clean_klass_tree_claimed) {
3806 return false;
3807 }
3808
3809 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3810 }
3811
3812 InstanceKlass* claim_next_klass() {
3813 Klass* klass;
3814 do {
3815 klass =_klass_iterator.next_klass();
3816 } while (klass != NULL && !klass->is_instance_klass());
3817
3818 // this can be null so don't call InstanceKlass::cast
3819 return static_cast<InstanceKlass*>(klass);
3820 }
3821
3822 public:
3823
3824 void clean_klass(InstanceKlass* ik) {
3825 ik->clean_weak_instanceklass_links(_is_alive);
3826 }
3827
3828 void work() {
3829 ResourceMark rm;
3830
3831 // One worker will clean the subklass/sibling klass tree.
3832 if (claim_clean_klass_tree_task()) {
3833 Klass::clean_subklass_tree(_is_alive);
3834 }
3835
3836 // All workers will help cleaning the classes,
3837 InstanceKlass* klass;
3838 while ((klass = claim_next_klass()) != NULL) {
3839 clean_klass(klass);
3840 }
3841 }
3842 };
3843
3844 class G1ResolvedMethodCleaningTask : public StackObj {
3845 BoolObjectClosure* _is_alive;
3846 volatile jint _resolved_method_task_claimed;
3847 public:
3848 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3849 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3850
3851 bool claim_resolved_method_task() {
3852 if (_resolved_method_task_claimed) {
3853 return false;
3854 }
3855 return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
3856 }
3857
3858 // These aren't big, one thread can do it all.
3859 void work() {
3860 if (claim_resolved_method_task()) {
3861 ResolvedMethodTable::unlink(_is_alive);
3862 }
3863 }
3864 };
3865
3866
3867 // To minimize the remark pause times, the tasks below are done in parallel.
3868 class G1ParallelCleaningTask : public AbstractGangTask {
3869 private:
3870 G1StringAndSymbolCleaningTask _string_symbol_task;
3871 G1CodeCacheUnloadingTask _code_cache_task;
3872 G1KlassCleaningTask _klass_cleaning_task;
3873 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3874
3875 public:
3876 // The constructor is run in the VMThread.
3877 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3878 AbstractGangTask("Parallel Cleaning"),
3879 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3880 _code_cache_task(num_workers, is_alive, unloading_occurred),
3881 _klass_cleaning_task(is_alive),
3882 _resolved_method_cleaning_task(is_alive) {
3883 }
3884
3885 // The parallel work done by all worker threads.
3886 void work(uint worker_id) {
3887 // Do first pass of code cache cleaning.
3888 _code_cache_task.work_first_pass(worker_id);
3889
3890 // Let the threads mark that the first pass is done.
3891 _code_cache_task.barrier_mark(worker_id);
3892
3893 // Clean the Strings and Symbols.
3894 _string_symbol_task.work(worker_id);
3895
3896 // Clean unreferenced things in the ResolvedMethodTable
3897 _resolved_method_cleaning_task.work();
3898
3899 // Wait for all workers to finish the first code cache cleaning pass.
3900 _code_cache_task.barrier_wait(worker_id);
3901
3902 // Do the second code cache cleaning work, which realize on
3903 // the liveness information gathered during the first pass.
3904 _code_cache_task.work_second_pass(worker_id);
3905
3906 // Clean all klasses that were not unloaded.
3907 _klass_cleaning_task.work();
3908 }
3909 };
3910
3911
3912 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3913 bool class_unloading_occurred) {
3914 uint n_workers = workers()->active_workers();
3915
3916 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3917 workers()->run_task(&g1_unlink_task);
3918 }
3919
3920 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3921 bool process_strings,
3922 bool process_symbols,
3923 bool process_string_dedup) {
3924 if (!process_strings && !process_symbols && !process_string_dedup) {
3925 // Nothing to clean.
3926 return;
3927 }
3928
3929 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3930 workers()->run_task(&g1_unlink_task);
3931
3932 }
3933
3934 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3935 private:
3936 DirtyCardQueueSet* _queue;
3937 G1CollectedHeap* _g1h;
3938 public:
3939 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3940 _queue(queue), _g1h(g1h) { }
3941
3942 virtual void work(uint worker_id) {
3943 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3944 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3945
3946 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3947 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3948
3949 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3950 }
3951 };
3952
3953 void G1CollectedHeap::redirty_logged_cards() {
3954 double redirty_logged_cards_start = os::elapsedTime();
3955
3956 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3957 dirty_card_queue_set().reset_for_par_iteration();
3958 workers()->run_task(&redirty_task);
3959
3960 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3961 dcq.merge_bufferlists(&dirty_card_queue_set());
3962 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3963
3964 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3965 }
3966
3967 // Weak Reference Processing support
3968
3969 // An always "is_alive" closure that is used to preserve referents.
3970 // If the object is non-null then it's alive. Used in the preservation
3971 // of referent objects that are pointed to by reference objects
3972 // discovered by the CM ref processor.
3973 class G1AlwaysAliveClosure: public BoolObjectClosure {
3974 G1CollectedHeap* _g1;
3975 public:
3976 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3977 bool do_object_b(oop p) {
3978 if (p != NULL) {
3979 return true;
3980 }
3981 return false;
3982 }
3983 };
3984
3985 bool G1STWIsAliveClosure::do_object_b(oop p) {
3986 // An object is reachable if it is outside the collection set,
3987 // or is inside and copied.
3988 return !_g1->is_in_cset(p) || p->is_forwarded();
3989 }
3990
3991 // Non Copying Keep Alive closure
3992 class G1KeepAliveClosure: public OopClosure {
3993 G1CollectedHeap* _g1;
3994 public:
3995 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3996 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3997 void do_oop(oop* p) {
3998 oop obj = *p;
3999 assert(obj != NULL, "the caller should have filtered out NULL values");
4000
4001 const InCSetState cset_state = _g1->in_cset_state(obj);
4002 if (!cset_state.is_in_cset_or_humongous()) {
4003 return;
4004 }
4005 if (cset_state.is_in_cset()) {
4006 assert( obj->is_forwarded(), "invariant" );
4007 *p = obj->forwardee();
4008 } else {
4009 assert(!obj->is_forwarded(), "invariant" );
4010 assert(cset_state.is_humongous(),
4011 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4012 _g1->set_humongous_is_live(obj);
4013 }
4014 }
4015 };
4016
4017 // Copying Keep Alive closure - can be called from both
4018 // serial and parallel code as long as different worker
4019 // threads utilize different G1ParScanThreadState instances
4020 // and different queues.
4021
4022 class G1CopyingKeepAliveClosure: public OopClosure {
4023 G1CollectedHeap* _g1h;
4024 OopClosure* _copy_non_heap_obj_cl;
4025 G1ParScanThreadState* _par_scan_state;
4026
4027 public:
4028 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4029 OopClosure* non_heap_obj_cl,
4030 G1ParScanThreadState* pss):
4031 _g1h(g1h),
4032 _copy_non_heap_obj_cl(non_heap_obj_cl),
4033 _par_scan_state(pss)
4034 {}
4035
4036 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4037 virtual void do_oop( oop* p) { do_oop_work(p); }
4038
4039 template <class T> void do_oop_work(T* p) {
4040 oop obj = oopDesc::load_decode_heap_oop(p);
4041
4042 if (_g1h->is_in_cset_or_humongous(obj)) {
4043 // If the referent object has been forwarded (either copied
4044 // to a new location or to itself in the event of an
4045 // evacuation failure) then we need to update the reference
4046 // field and, if both reference and referent are in the G1
4047 // heap, update the RSet for the referent.
4048 //
4049 // If the referent has not been forwarded then we have to keep
4050 // it alive by policy. Therefore we have copy the referent.
4051 //
4052 // If the reference field is in the G1 heap then we can push
4053 // on the PSS queue. When the queue is drained (after each
4054 // phase of reference processing) the object and it's followers
4055 // will be copied, the reference field set to point to the
4056 // new location, and the RSet updated. Otherwise we need to
4057 // use the the non-heap or metadata closures directly to copy
4058 // the referent object and update the pointer, while avoiding
4059 // updating the RSet.
4060
4061 if (_g1h->is_in_g1_reserved(p)) {
4062 _par_scan_state->push_on_queue(p);
4063 } else {
4064 assert(!Metaspace::contains((const void*)p),
4065 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4066 _copy_non_heap_obj_cl->do_oop(p);
4067 }
4068 }
4069 }
4070 };
4071
4072 // Serial drain queue closure. Called as the 'complete_gc'
4073 // closure for each discovered list in some of the
4074 // reference processing phases.
4075
4076 class G1STWDrainQueueClosure: public VoidClosure {
4077 protected:
4078 G1CollectedHeap* _g1h;
4079 G1ParScanThreadState* _par_scan_state;
4080
4081 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4082
4083 public:
4084 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4085 _g1h(g1h),
4086 _par_scan_state(pss)
4087 { }
4088
4089 void do_void() {
4090 G1ParScanThreadState* const pss = par_scan_state();
4091 pss->trim_queue();
4092 }
4093 };
4094
4095 // Parallel Reference Processing closures
4096
4097 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4098 // processing during G1 evacuation pauses.
4099
4100 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4101 private:
4102 G1CollectedHeap* _g1h;
4103 G1ParScanThreadStateSet* _pss;
4104 RefToScanQueueSet* _queues;
4105 WorkGang* _workers;
4106 uint _active_workers;
4107
4108 public:
4109 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4110 G1ParScanThreadStateSet* per_thread_states,
4111 WorkGang* workers,
4112 RefToScanQueueSet *task_queues,
4113 uint n_workers) :
4114 _g1h(g1h),
4115 _pss(per_thread_states),
4116 _queues(task_queues),
4117 _workers(workers),
4118 _active_workers(n_workers)
4119 {
4120 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4121 }
4122
4123 // Executes the given task using concurrent marking worker threads.
4124 virtual void execute(ProcessTask& task);
4125 virtual void execute(EnqueueTask& task);
4126 };
4127
4128 // Gang task for possibly parallel reference processing
4129
4130 class G1STWRefProcTaskProxy: public AbstractGangTask {
4131 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4132 ProcessTask& _proc_task;
4133 G1CollectedHeap* _g1h;
4134 G1ParScanThreadStateSet* _pss;
4135 RefToScanQueueSet* _task_queues;
4136 ParallelTaskTerminator* _terminator;
4137
4138 public:
4139 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4140 G1CollectedHeap* g1h,
4141 G1ParScanThreadStateSet* per_thread_states,
4142 RefToScanQueueSet *task_queues,
4143 ParallelTaskTerminator* terminator) :
4144 AbstractGangTask("Process reference objects in parallel"),
4145 _proc_task(proc_task),
4146 _g1h(g1h),
4147 _pss(per_thread_states),
4148 _task_queues(task_queues),
4149 _terminator(terminator)
4150 {}
4151
4152 virtual void work(uint worker_id) {
4153 // The reference processing task executed by a single worker.
4154 ResourceMark rm;
4155 HandleMark hm;
4156
4157 G1STWIsAliveClosure is_alive(_g1h);
4158
4159 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4160 pss->set_ref_processor(NULL);
4161
4162 // Keep alive closure.
4163 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4164
4165 // Complete GC closure
4166 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4167
4168 // Call the reference processing task's work routine.
4169 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4170
4171 // Note we cannot assert that the refs array is empty here as not all
4172 // of the processing tasks (specifically phase2 - pp2_work) execute
4173 // the complete_gc closure (which ordinarily would drain the queue) so
4174 // the queue may not be empty.
4175 }
4176 };
4177
4178 // Driver routine for parallel reference processing.
4179 // Creates an instance of the ref processing gang
4180 // task and has the worker threads execute it.
4181 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4182 assert(_workers != NULL, "Need parallel worker threads.");
4183
4184 ParallelTaskTerminator terminator(_active_workers, _queues);
4185 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4186
4187 _workers->run_task(&proc_task_proxy);
4188 }
4189
4190 // Gang task for parallel reference enqueueing.
4191
4192 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4193 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4194 EnqueueTask& _enq_task;
4195
4196 public:
4197 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4198 AbstractGangTask("Enqueue reference objects in parallel"),
4199 _enq_task(enq_task)
4200 { }
4201
4202 virtual void work(uint worker_id) {
4203 _enq_task.work(worker_id);
4204 }
4205 };
4206
4207 // Driver routine for parallel reference enqueueing.
4208 // Creates an instance of the ref enqueueing gang
4209 // task and has the worker threads execute it.
4210
4211 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4212 assert(_workers != NULL, "Need parallel worker threads.");
4213
4214 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4215
4216 _workers->run_task(&enq_task_proxy);
4217 }
4218
4219 // End of weak reference support closures
4220
4221 // Abstract task used to preserve (i.e. copy) any referent objects
4222 // that are in the collection set and are pointed to by reference
4223 // objects discovered by the CM ref processor.
4224
4225 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4226 protected:
4227 G1CollectedHeap* _g1h;
4228 G1ParScanThreadStateSet* _pss;
4229 RefToScanQueueSet* _queues;
4230 ParallelTaskTerminator _terminator;
4231 uint _n_workers;
4232
4233 public:
4234 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4235 AbstractGangTask("ParPreserveCMReferents"),
4236 _g1h(g1h),
4237 _pss(per_thread_states),
4238 _queues(task_queues),
4239 _terminator(workers, _queues),
4240 _n_workers(workers)
4241 {
4242 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4243 }
4244
4245 void work(uint worker_id) {
4246 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4247
4248 ResourceMark rm;
4249 HandleMark hm;
4250
4251 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4252 pss->set_ref_processor(NULL);
4253 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4254
4255 // Is alive closure
4256 G1AlwaysAliveClosure always_alive(_g1h);
4257
4258 // Copying keep alive closure. Applied to referent objects that need
4259 // to be copied.
4260 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4261
4262 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4263
4264 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4265 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4266
4267 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4268 // So this must be true - but assert just in case someone decides to
4269 // change the worker ids.
4270 assert(worker_id < limit, "sanity");
4271 assert(!rp->discovery_is_atomic(), "check this code");
4272
4273 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4274 for (uint idx = worker_id; idx < limit; idx += stride) {
4275 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4276
4277 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4278 while (iter.has_next()) {
4279 // Since discovery is not atomic for the CM ref processor, we
4280 // can see some null referent objects.
4281 iter.load_ptrs(DEBUG_ONLY(true));
4282 oop ref = iter.obj();
4283
4284 // This will filter nulls.
4285 if (iter.is_referent_alive()) {
4286 iter.make_referent_alive();
4287 }
4288 iter.move_to_next();
4289 }
4290 }
4291
4292 // Drain the queue - which may cause stealing
4293 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4294 drain_queue.do_void();
4295 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4296 assert(pss->queue_is_empty(), "should be");
4297 }
4298 };
4299
4300 void G1CollectedHeap::process_weak_jni_handles() {
4301 double ref_proc_start = os::elapsedTime();
4302
4303 G1STWIsAliveClosure is_alive(this);
4304 G1KeepAliveClosure keep_alive(this);
4305 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4306
4307 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4308 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4309 }
4310
4311 void G1CollectedHeap::process_heap_monitoring() {
4312 log_develop_trace(gc, ref)("HeapSampling [other] : heap monitoring processing");
4313 G1STWIsAliveClosure is_alive(this);
4314 G1KeepAliveClosure keep_alive(this);
4315 HeapMonitoring::weak_oops_do(&is_alive, &keep_alive);
4316 }
4317
4318 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4319 // Any reference objects, in the collection set, that were 'discovered'
4320 // by the CM ref processor should have already been copied (either by
4321 // applying the external root copy closure to the discovered lists, or
4322 // by following an RSet entry).
4323 //
4324 // But some of the referents, that are in the collection set, that these
4325 // reference objects point to may not have been copied: the STW ref
4326 // processor would have seen that the reference object had already
4327 // been 'discovered' and would have skipped discovering the reference,
4328 // but would not have treated the reference object as a regular oop.
4329 // As a result the copy closure would not have been applied to the
4330 // referent object.
4331 //
4332 // We need to explicitly copy these referent objects - the references
4333 // will be processed at the end of remarking.
4334 //
4335 // We also need to do this copying before we process the reference
4336 // objects discovered by the STW ref processor in case one of these
4337 // referents points to another object which is also referenced by an
4338 // object discovered by the STW ref processor.
4339 double preserve_cm_referents_time = 0.0;
4340
4341 // To avoid spawning task when there is no work to do, check that
4342 // a concurrent cycle is active and that some references have been
4343 // discovered.
4344 if (concurrent_mark()->cmThread()->during_cycle() &&
4345 ref_processor_cm()->has_discovered_references()) {
4346 double preserve_cm_referents_start = os::elapsedTime();
4347 uint no_of_gc_workers = workers()->active_workers();
4348 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4349 per_thread_states,
4350 no_of_gc_workers,
4351 _task_queues);
4352 workers()->run_task(&keep_cm_referents);
4353 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4354 }
4355
4356 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4357 }
4358
4359 // Weak Reference processing during an evacuation pause (part 1).
4360 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4361 double ref_proc_start = os::elapsedTime();
4362
4363 ReferenceProcessor* rp = _ref_processor_stw;
4364 assert(rp->discovery_enabled(), "should have been enabled");
4365
4366 // Closure to test whether a referent is alive.
4367 G1STWIsAliveClosure is_alive(this);
4368
4369 // Even when parallel reference processing is enabled, the processing
4370 // of JNI refs is serial and performed serially by the current thread
4371 // rather than by a worker. The following PSS will be used for processing
4372 // JNI refs.
4373
4374 // Use only a single queue for this PSS.
4375 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4376 pss->set_ref_processor(NULL);
4377 assert(pss->queue_is_empty(), "pre-condition");
4378
4379 // Keep alive closure.
4380 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4381
4382 // Serial Complete GC closure
4383 G1STWDrainQueueClosure drain_queue(this, pss);
4384
4385 // Setup the soft refs policy...
4386 rp->setup_policy(false);
4387
4388 ReferenceProcessorStats stats;
4389 if (!rp->processing_is_mt()) {
4390 // Serial reference processing...
4391 stats = rp->process_discovered_references(&is_alive,
4392 &keep_alive,
4393 &drain_queue,
4394 NULL,
4395 _gc_timer_stw);
4396 } else {
4397 uint no_of_gc_workers = workers()->active_workers();
4398
4399 // Parallel reference processing
4400 assert(no_of_gc_workers <= rp->max_num_q(),
4401 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4402 no_of_gc_workers, rp->max_num_q());
4403
4404 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4405 stats = rp->process_discovered_references(&is_alive,
4406 &keep_alive,
4407 &drain_queue,
4408 &par_task_executor,
4409 _gc_timer_stw);
4410 }
4411
4412 _gc_tracer_stw->report_gc_reference_stats(stats);
4413
4414 // We have completed copying any necessary live referent objects.
4415 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4416
4417 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4418 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4419 }
4420
4421 // Weak Reference processing during an evacuation pause (part 2).
4422 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4423 double ref_enq_start = os::elapsedTime();
4424
4425 ReferenceProcessor* rp = _ref_processor_stw;
4426 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4427
4428 // Now enqueue any remaining on the discovered lists on to
4429 // the pending list.
4430 if (!rp->processing_is_mt()) {
4431 // Serial reference processing...
4432 rp->enqueue_discovered_references();
4433 } else {
4434 // Parallel reference enqueueing
4435
4436 uint n_workers = workers()->active_workers();
4437
4438 assert(n_workers <= rp->max_num_q(),
4439 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4440 n_workers, rp->max_num_q());
4441
4442 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4443 rp->enqueue_discovered_references(&par_task_executor);
4444 }
4445
4446 rp->verify_no_references_recorded();
4447 assert(!rp->discovery_enabled(), "should have been disabled");
4448
4449 // FIXME
4450 // CM's reference processing also cleans up the string and symbol tables.
4451 // Should we do that here also? We could, but it is a serial operation
4452 // and could significantly increase the pause time.
4453
4454 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4455 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4456 }
4457
4458 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4459 double merge_pss_time_start = os::elapsedTime();
4460 per_thread_states->flush();
4461 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4462 }
4463
4464 void G1CollectedHeap::pre_evacuate_collection_set() {
4465 _expand_heap_after_alloc_failure = true;
4466 _evacuation_failed = false;
4467
4468 // Disable the hot card cache.
4469 _hot_card_cache->reset_hot_cache_claimed_index();
4470 _hot_card_cache->set_use_cache(false);
4471
4472 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4473 _preserved_marks_set.assert_empty();
4474
4475 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4476
4477 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4478 if (collector_state()->during_initial_mark_pause()) {
4479 double start_clear_claimed_marks = os::elapsedTime();
4480
4481 ClassLoaderDataGraph::clear_claimed_marks();
4482
4483 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4484 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4485 }
4486 }
4487
4488 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4489 // Should G1EvacuationFailureALot be in effect for this GC?
4490 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4491
4492 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4493
4494 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4495
4496 double start_par_time_sec = os::elapsedTime();
4497 double end_par_time_sec;
4498
4499 {
4500 const uint n_workers = workers()->active_workers();
4501 G1RootProcessor root_processor(this, n_workers);
4502 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4503
4504 print_termination_stats_hdr();
4505
4506 workers()->run_task(&g1_par_task);
4507 end_par_time_sec = os::elapsedTime();
4508
4509 // Closing the inner scope will execute the destructor
4510 // for the G1RootProcessor object. We record the current
4511 // elapsed time before closing the scope so that time
4512 // taken for the destructor is NOT included in the
4513 // reported parallel time.
4514 }
4515
4516 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4517 phase_times->record_par_time(par_time_ms);
4518
4519 double code_root_fixup_time_ms =
4520 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4521 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4522 }
4523
4524 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4525 // Process any discovered reference objects - we have
4526 // to do this _before_ we retire the GC alloc regions
4527 // as we may have to copy some 'reachable' referent
4528 // objects (and their reachable sub-graphs) that were
4529 // not copied during the pause.
4530 if (g1_policy()->should_process_references()) {
4531 preserve_cm_referents(per_thread_states);
4532 process_discovered_references(per_thread_states);
4533 } else {
4534 ref_processor_stw()->verify_no_references_recorded();
4535 process_weak_jni_handles();
4536 process_heap_monitoring();
4537 }
4538
4539 if (G1StringDedup::is_enabled()) {
4540 double fixup_start = os::elapsedTime();
4541
4542 G1STWIsAliveClosure is_alive(this);
4543 G1KeepAliveClosure keep_alive(this);
4544 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4545
4546 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4547 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4548 }
4549
4550 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4551
4552 if (evacuation_failed()) {
4553 restore_after_evac_failure();
4554
4555 // Reset the G1EvacuationFailureALot counters and flags
4556 // Note: the values are reset only when an actual
4557 // evacuation failure occurs.
4558 NOT_PRODUCT(reset_evacuation_should_fail();)
4559 }
4560
4561 _preserved_marks_set.assert_empty();
4562
4563 // Enqueue any remaining references remaining on the STW
4564 // reference processor's discovered lists. We need to do
4565 // this after the card table is cleaned (and verified) as
4566 // the act of enqueueing entries on to the pending list
4567 // will log these updates (and dirty their associated
4568 // cards). We need these updates logged to update any
4569 // RSets.
4570 if (g1_policy()->should_process_references()) {
4571 enqueue_discovered_references(per_thread_states);
4572 } else {
4573 g1_policy()->phase_times()->record_ref_enq_time(0);
4574 }
4575
4576 _allocator->release_gc_alloc_regions(evacuation_info);
4577
4578 merge_per_thread_state_info(per_thread_states);
4579
4580 // Reset and re-enable the hot card cache.
4581 // Note the counts for the cards in the regions in the
4582 // collection set are reset when the collection set is freed.
4583 _hot_card_cache->reset_hot_cache();
4584 _hot_card_cache->set_use_cache(true);
4585
4586 purge_code_root_memory();
4587
4588 redirty_logged_cards();
4589 #if defined(COMPILER2) || INCLUDE_JVMCI
4590 double start = os::elapsedTime();
4591 DerivedPointerTable::update_pointers();
4592 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4593 #endif
4594 g1_policy()->print_age_table();
4595 }
4596
4597 void G1CollectedHeap::record_obj_copy_mem_stats() {
4598 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4599
4600 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4601 create_g1_evac_summary(&_old_evac_stats));
4602 }
4603
4604 void G1CollectedHeap::free_region(HeapRegion* hr,
4605 FreeRegionList* free_list,
4606 bool skip_remset,
4607 bool skip_hot_card_cache,
4608 bool locked) {
4609 assert(!hr->is_free(), "the region should not be free");
4610 assert(!hr->is_empty(), "the region should not be empty");
4611 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4612 assert(free_list != NULL, "pre-condition");
4613
4614 if (G1VerifyBitmaps) {
4615 MemRegion mr(hr->bottom(), hr->end());
4616 concurrent_mark()->clearRangePrevBitmap(mr);
4617 }
4618
4619 // Clear the card counts for this region.
4620 // Note: we only need to do this if the region is not young
4621 // (since we don't refine cards in young regions).
4622 if (!skip_hot_card_cache && !hr->is_young()) {
4623 _hot_card_cache->reset_card_counts(hr);
4624 }
4625 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4626 free_list->add_ordered(hr);
4627 }
4628
4629 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4630 FreeRegionList* free_list,
4631 bool skip_remset) {
4632 assert(hr->is_humongous(), "this is only for humongous regions");
4633 assert(free_list != NULL, "pre-condition");
4634 hr->clear_humongous();
4635 free_region(hr, free_list, skip_remset);
4636 }
4637
4638 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4639 const uint humongous_regions_removed) {
4640 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4641 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4642 _old_set.bulk_remove(old_regions_removed);
4643 _humongous_set.bulk_remove(humongous_regions_removed);
4644 }
4645
4646 }
4647
4648 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4649 assert(list != NULL, "list can't be null");
4650 if (!list->is_empty()) {
4651 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4652 _hrm.insert_list_into_free_list(list);
4653 }
4654 }
4655
4656 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4657 decrease_used(bytes);
4658 }
4659
4660 class G1ParScrubRemSetTask: public AbstractGangTask {
4661 protected:
4662 G1RemSet* _g1rs;
4663 HeapRegionClaimer _hrclaimer;
4664
4665 public:
4666 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4667 AbstractGangTask("G1 ScrubRS"),
4668 _g1rs(g1_rs),
4669 _hrclaimer(num_workers) {
4670 }
4671
4672 void work(uint worker_id) {
4673 _g1rs->scrub(worker_id, &_hrclaimer);
4674 }
4675 };
4676
4677 void G1CollectedHeap::scrub_rem_set() {
4678 uint num_workers = workers()->active_workers();
4679 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4680 workers()->run_task(&g1_par_scrub_rs_task);
4681 }
4682
4683 class G1FreeCollectionSetTask : public AbstractGangTask {
4684 private:
4685
4686 // Closure applied to all regions in the collection set to do work that needs to
4687 // be done serially in a single thread.
4688 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4689 private:
4690 EvacuationInfo* _evacuation_info;
4691 const size_t* _surviving_young_words;
4692
4693 // Bytes used in successfully evacuated regions before the evacuation.
4694 size_t _before_used_bytes;
4695 // Bytes used in unsucessfully evacuated regions before the evacuation
4696 size_t _after_used_bytes;
4697
4698 size_t _bytes_allocated_in_old_since_last_gc;
4699
4700 size_t _failure_used_words;
4701 size_t _failure_waste_words;
4702
4703 FreeRegionList _local_free_list;
4704 public:
4705 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4706 HeapRegionClosure(),
4707 _evacuation_info(evacuation_info),
4708 _surviving_young_words(surviving_young_words),
4709 _before_used_bytes(0),
4710 _after_used_bytes(0),
4711 _bytes_allocated_in_old_since_last_gc(0),
4712 _failure_used_words(0),
4713 _failure_waste_words(0),
4714 _local_free_list("Local Region List for CSet Freeing") {
4715 }
4716
4717 virtual bool doHeapRegion(HeapRegion* r) {
4718 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4719
4720 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4721 g1h->clear_in_cset(r);
4722
4723 if (r->is_young()) {
4724 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4725 "Young index %d is wrong for region %u of type %s with %u young regions",
4726 r->young_index_in_cset(),
4727 r->hrm_index(),
4728 r->get_type_str(),
4729 g1h->collection_set()->young_region_length());
4730 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4731 r->record_surv_words_in_group(words_survived);
4732 }
4733
4734 if (!r->evacuation_failed()) {
4735 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4736 _before_used_bytes += r->used();
4737 g1h->free_region(r,
4738 &_local_free_list,
4739 true, /* skip_remset */
4740 true, /* skip_hot_card_cache */
4741 true /* locked */);
4742 } else {
4743 r->uninstall_surv_rate_group();
4744 r->set_young_index_in_cset(-1);
4745 r->set_evacuation_failed(false);
4746 // When moving a young gen region to old gen, we "allocate" that whole region
4747 // there. This is in addition to any already evacuated objects. Notify the
4748 // policy about that.
4749 // Old gen regions do not cause an additional allocation: both the objects
4750 // still in the region and the ones already moved are accounted for elsewhere.
4751 if (r->is_young()) {
4752 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4753 }
4754 // The region is now considered to be old.
4755 r->set_old();
4756 // Do some allocation statistics accounting. Regions that failed evacuation
4757 // are always made old, so there is no need to update anything in the young
4758 // gen statistics, but we need to update old gen statistics.
4759 size_t used_words = r->marked_bytes() / HeapWordSize;
4760
4761 _failure_used_words += used_words;
4762 _failure_waste_words += HeapRegion::GrainWords - used_words;
4763
4764 g1h->old_set_add(r);
4765 _after_used_bytes += r->used();
4766 }
4767 return false;
4768 }
4769
4770 void complete_work() {
4771 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4772
4773 _evacuation_info->set_regions_freed(_local_free_list.length());
4774 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4775
4776 g1h->prepend_to_freelist(&_local_free_list);
4777 g1h->decrement_summary_bytes(_before_used_bytes);
4778
4779 G1Policy* policy = g1h->g1_policy();
4780 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4781
4782 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4783 }
4784 };
4785
4786 G1CollectionSet* _collection_set;
4787 G1SerialFreeCollectionSetClosure _cl;
4788 const size_t* _surviving_young_words;
4789
4790 size_t _rs_lengths;
4791
4792 volatile jint _serial_work_claim;
4793
4794 struct WorkItem {
4795 uint region_idx;
4796 bool is_young;
4797 bool evacuation_failed;
4798
4799 WorkItem(HeapRegion* r) {
4800 region_idx = r->hrm_index();
4801 is_young = r->is_young();
4802 evacuation_failed = r->evacuation_failed();
4803 }
4804 };
4805
4806 volatile size_t _parallel_work_claim;
4807 size_t _num_work_items;
4808 WorkItem* _work_items;
4809
4810 void do_serial_work() {
4811 // Need to grab the lock to be allowed to modify the old region list.
4812 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4813 _collection_set->iterate(&_cl);
4814 }
4815
4816 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4817 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4818
4819 HeapRegion* r = g1h->region_at(region_idx);
4820 assert(!g1h->is_on_master_free_list(r), "sanity");
4821
4822 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4823
4824 if (!is_young) {
4825 g1h->_hot_card_cache->reset_card_counts(r);
4826 }
4827
4828 if (!evacuation_failed) {
4829 r->rem_set()->clear_locked();
4830 }
4831 }
4832
4833 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4834 private:
4835 size_t _cur_idx;
4836 WorkItem* _work_items;
4837 public:
4838 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4839
4840 virtual bool doHeapRegion(HeapRegion* r) {
4841 _work_items[_cur_idx++] = WorkItem(r);
4842 return false;
4843 }
4844 };
4845
4846 void prepare_work() {
4847 G1PrepareFreeCollectionSetClosure cl(_work_items);
4848 _collection_set->iterate(&cl);
4849 }
4850
4851 void complete_work() {
4852 _cl.complete_work();
4853
4854 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4855 policy->record_max_rs_lengths(_rs_lengths);
4856 policy->cset_regions_freed();
4857 }
4858 public:
4859 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4860 AbstractGangTask("G1 Free Collection Set"),
4861 _cl(evacuation_info, surviving_young_words),
4862 _collection_set(collection_set),
4863 _surviving_young_words(surviving_young_words),
4864 _serial_work_claim(0),
4865 _rs_lengths(0),
4866 _parallel_work_claim(0),
4867 _num_work_items(collection_set->region_length()),
4868 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4869 prepare_work();
4870 }
4871
4872 ~G1FreeCollectionSetTask() {
4873 complete_work();
4874 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4875 }
4876
4877 // Chunk size for work distribution. The chosen value has been determined experimentally
4878 // to be a good tradeoff between overhead and achievable parallelism.
4879 static uint chunk_size() { return 32; }
4880
4881 virtual void work(uint worker_id) {
4882 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4883
4884 // Claim serial work.
4885 if (_serial_work_claim == 0) {
4886 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4887 if (value == 0) {
4888 double serial_time = os::elapsedTime();
4889 do_serial_work();
4890 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4891 }
4892 }
4893
4894 // Start parallel work.
4895 double young_time = 0.0;
4896 bool has_young_time = false;
4897 double non_young_time = 0.0;
4898 bool has_non_young_time = false;
4899
4900 while (true) {
4901 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4902 size_t cur = end - chunk_size();
4903
4904 if (cur >= _num_work_items) {
4905 break;
4906 }
4907
4908 double start_time = os::elapsedTime();
4909
4910 end = MIN2(end, _num_work_items);
4911
4912 for (; cur < end; cur++) {
4913 bool is_young = _work_items[cur].is_young;
4914
4915 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4916
4917 double end_time = os::elapsedTime();
4918 double time_taken = end_time - start_time;
4919 if (is_young) {
4920 young_time += time_taken;
4921 has_young_time = true;
4922 } else {
4923 non_young_time += time_taken;
4924 has_non_young_time = true;
4925 }
4926 start_time = end_time;
4927 }
4928 }
4929
4930 if (has_young_time) {
4931 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4932 }
4933 if (has_non_young_time) {
4934 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4935 }
4936 }
4937 };
4938
4939 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4940 _eden.clear();
4941
4942 double free_cset_start_time = os::elapsedTime();
4943
4944 {
4945 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4946 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4947
4948 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4949
4950 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4951 cl.name(),
4952 num_workers,
4953 _collection_set.region_length());
4954 workers()->run_task(&cl, num_workers);
4955 }
4956 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4957
4958 collection_set->clear();
4959 }
4960
4961 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4962 private:
4963 FreeRegionList* _free_region_list;
4964 HeapRegionSet* _proxy_set;
4965 uint _humongous_objects_reclaimed;
4966 uint _humongous_regions_reclaimed;
4967 size_t _freed_bytes;
4968 public:
4969
4970 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4971 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4972 }
4973
4974 virtual bool doHeapRegion(HeapRegion* r) {
4975 if (!r->is_starts_humongous()) {
4976 return false;
4977 }
4978
4979 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4980
4981 oop obj = (oop)r->bottom();
4982 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4983
4984 // The following checks whether the humongous object is live are sufficient.
4985 // The main additional check (in addition to having a reference from the roots
4986 // or the young gen) is whether the humongous object has a remembered set entry.
4987 //
4988 // A humongous object cannot be live if there is no remembered set for it
4989 // because:
4990 // - there can be no references from within humongous starts regions referencing
4991 // the object because we never allocate other objects into them.
4992 // (I.e. there are no intra-region references that may be missed by the
4993 // remembered set)
4994 // - as soon there is a remembered set entry to the humongous starts region
4995 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4996 // until the end of a concurrent mark.
4997 //
4998 // It is not required to check whether the object has been found dead by marking
4999 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5000 // all objects allocated during that time are considered live.
5001 // SATB marking is even more conservative than the remembered set.
5002 // So if at this point in the collection there is no remembered set entry,
5003 // nobody has a reference to it.
5004 // At the start of collection we flush all refinement logs, and remembered sets
5005 // are completely up-to-date wrt to references to the humongous object.
5006 //
5007 // Other implementation considerations:
5008 // - never consider object arrays at this time because they would pose
5009 // considerable effort for cleaning up the the remembered sets. This is
5010 // required because stale remembered sets might reference locations that
5011 // are currently allocated into.
5012 uint region_idx = r->hrm_index();
5013 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5014 !r->rem_set()->is_empty()) {
5015 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",
5016 region_idx,
5017 (size_t)obj->size() * HeapWordSize,
5018 p2i(r->bottom()),
5019 r->rem_set()->occupied(),
5020 r->rem_set()->strong_code_roots_list_length(),
5021 next_bitmap->isMarked(r->bottom()),
5022 g1h->is_humongous_reclaim_candidate(region_idx),
5023 obj->is_typeArray()
5024 );
5025 return false;
5026 }
5027
5028 guarantee(obj->is_typeArray(),
5029 "Only eagerly reclaiming type arrays is supported, but the object "
5030 PTR_FORMAT " is not.", p2i(r->bottom()));
5031
5032 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",
5033 region_idx,
5034 (size_t)obj->size() * HeapWordSize,
5035 p2i(r->bottom()),
5036 r->rem_set()->occupied(),
5037 r->rem_set()->strong_code_roots_list_length(),
5038 next_bitmap->isMarked(r->bottom()),
5039 g1h->is_humongous_reclaim_candidate(region_idx),
5040 obj->is_typeArray()
5041 );
5042
5043 // Need to clear mark bit of the humongous object if already set.
5044 if (next_bitmap->isMarked(r->bottom())) {
5045 next_bitmap->clear(r->bottom());
5046 }
5047 _humongous_objects_reclaimed++;
5048 do {
5049 HeapRegion* next = g1h->next_region_in_humongous(r);
5050 _freed_bytes += r->used();
5051 r->set_containing_set(NULL);
5052 _humongous_regions_reclaimed++;
5053 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
5054 r = next;
5055 } while (r != NULL);
5056
5057 return false;
5058 }
5059
5060 uint humongous_objects_reclaimed() {
5061 return _humongous_objects_reclaimed;
5062 }
5063
5064 uint humongous_regions_reclaimed() {
5065 return _humongous_regions_reclaimed;
5066 }
5067
5068 size_t bytes_freed() const {
5069 return _freed_bytes;
5070 }
5071 };
5072
5073 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5074 assert_at_safepoint(true);
5075
5076 if (!G1EagerReclaimHumongousObjects ||
5077 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5078 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5079 return;
5080 }
5081
5082 double start_time = os::elapsedTime();
5083
5084 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5085
5086 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5087 heap_region_iterate(&cl);
5088
5089 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
5090
5091 G1HRPrinter* hrp = hr_printer();
5092 if (hrp->is_active()) {
5093 FreeRegionListIterator iter(&local_cleanup_list);
5094 while (iter.more_available()) {
5095 HeapRegion* hr = iter.get_next();
5096 hrp->cleanup(hr);
5097 }
5098 }
5099
5100 prepend_to_freelist(&local_cleanup_list);
5101 decrement_summary_bytes(cl.bytes_freed());
5102
5103 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5104 cl.humongous_objects_reclaimed());
5105 }
5106
5107 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
5108 public:
5109 virtual bool doHeapRegion(HeapRegion* r) {
5110 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
5111 G1CollectedHeap::heap()->clear_in_cset(r);
5112 r->set_young_index_in_cset(-1);
5113 return false;
5114 }
5115 };
5116
5117 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
5118 G1AbandonCollectionSetClosure cl;
5119 collection_set->iterate(&cl);
5120
5121 collection_set->clear();
5122 collection_set->stop_incremental_building();
5123 }
5124
5125 void G1CollectedHeap::set_free_regions_coming() {
5126 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5127
5128 assert(!free_regions_coming(), "pre-condition");
5129 _free_regions_coming = true;
5130 }
5131
5132 void G1CollectedHeap::reset_free_regions_coming() {
5133 assert(free_regions_coming(), "pre-condition");
5134
5135 {
5136 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5137 _free_regions_coming = false;
5138 SecondaryFreeList_lock->notify_all();
5139 }
5140
5141 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5142 }
5143
5144 void G1CollectedHeap::wait_while_free_regions_coming() {
5145 // Most of the time we won't have to wait, so let's do a quick test
5146 // first before we take the lock.
5147 if (!free_regions_coming()) {
5148 return;
5149 }
5150
5151 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5152
5153 {
5154 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5155 while (free_regions_coming()) {
5156 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5157 }
5158 }
5159
5160 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5161 }
5162
5163 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5164 return _allocator->is_retained_old_region(hr);
5165 }
5166
5167 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5168 _eden.add(hr);
5169 _g1_policy->set_region_eden(hr);
5170 }
5171
5172 #ifdef ASSERT
5173
5174 class NoYoungRegionsClosure: public HeapRegionClosure {
5175 private:
5176 bool _success;
5177 public:
5178 NoYoungRegionsClosure() : _success(true) { }
5179 bool doHeapRegion(HeapRegion* r) {
5180 if (r->is_young()) {
5181 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5182 p2i(r->bottom()), p2i(r->end()));
5183 _success = false;
5184 }
5185 return false;
5186 }
5187 bool success() { return _success; }
5188 };
5189
5190 bool G1CollectedHeap::check_young_list_empty() {
5191 bool ret = (young_regions_count() == 0);
5192
5193 NoYoungRegionsClosure closure;
5194 heap_region_iterate(&closure);
5195 ret = ret && closure.success();
5196
5197 return ret;
5198 }
5199
5200 #endif // ASSERT
5201
5202 class TearDownRegionSetsClosure : public HeapRegionClosure {
5203 private:
5204 HeapRegionSet *_old_set;
5205
5206 public:
5207 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5208
5209 bool doHeapRegion(HeapRegion* r) {
5210 if (r->is_old()) {
5211 _old_set->remove(r);
5212 } else if(r->is_young()) {
5213 r->uninstall_surv_rate_group();
5214 } else {
5215 // We ignore free regions, we'll empty the free list afterwards.
5216 // We ignore humongous regions, we're not tearing down the
5217 // humongous regions set.
5218 assert(r->is_free() || r->is_humongous(),
5219 "it cannot be another type");
5220 }
5221 return false;
5222 }
5223
5224 ~TearDownRegionSetsClosure() {
5225 assert(_old_set->is_empty(), "post-condition");
5226 }
5227 };
5228
5229 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5230 assert_at_safepoint(true /* should_be_vm_thread */);
5231
5232 if (!free_list_only) {
5233 TearDownRegionSetsClosure cl(&_old_set);
5234 heap_region_iterate(&cl);
5235
5236 // Note that emptying the _young_list is postponed and instead done as
5237 // the first step when rebuilding the regions sets again. The reason for
5238 // this is that during a full GC string deduplication needs to know if
5239 // a collected region was young or old when the full GC was initiated.
5240 }
5241 _hrm.remove_all_free_regions();
5242 }
5243
5244 void G1CollectedHeap::increase_used(size_t bytes) {
5245 _summary_bytes_used += bytes;
5246 }
5247
5248 void G1CollectedHeap::decrease_used(size_t bytes) {
5249 assert(_summary_bytes_used >= bytes,
5250 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5251 _summary_bytes_used, bytes);
5252 _summary_bytes_used -= bytes;
5253 }
5254
5255 void G1CollectedHeap::set_used(size_t bytes) {
5256 _summary_bytes_used = bytes;
5257 }
5258
5259 class RebuildRegionSetsClosure : public HeapRegionClosure {
5260 private:
5261 bool _free_list_only;
5262 HeapRegionSet* _old_set;
5263 HeapRegionManager* _hrm;
5264 size_t _total_used;
5265
5266 public:
5267 RebuildRegionSetsClosure(bool free_list_only,
5268 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5269 _free_list_only(free_list_only),
5270 _old_set(old_set), _hrm(hrm), _total_used(0) {
5271 assert(_hrm->num_free_regions() == 0, "pre-condition");
5272 if (!free_list_only) {
5273 assert(_old_set->is_empty(), "pre-condition");
5274 }
5275 }
5276
5277 bool doHeapRegion(HeapRegion* r) {
5278 if (r->is_empty()) {
5279 // Add free regions to the free list
5280 r->set_free();
5281 r->set_allocation_context(AllocationContext::system());
5282 _hrm->insert_into_free_list(r);
5283 } else if (!_free_list_only) {
5284
5285 if (r->is_humongous()) {
5286 // We ignore humongous regions. We left the humongous set unchanged.
5287 } else {
5288 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5289 // We now consider all regions old, so register as such. Leave
5290 // archive regions set that way, however, while still adding
5291 // them to the old set.
5292 if (!r->is_archive()) {
5293 r->set_old();
5294 }
5295 _old_set->add(r);
5296 }
5297 _total_used += r->used();
5298 }
5299
5300 return false;
5301 }
5302
5303 size_t total_used() {
5304 return _total_used;
5305 }
5306 };
5307
5308 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5309 assert_at_safepoint(true /* should_be_vm_thread */);
5310
5311 if (!free_list_only) {
5312 _eden.clear();
5313 _survivor.clear();
5314 }
5315
5316 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5317 heap_region_iterate(&cl);
5318
5319 if (!free_list_only) {
5320 set_used(cl.total_used());
5321 if (_archive_allocator != NULL) {
5322 _archive_allocator->clear_used();
5323 }
5324 }
5325 assert(used_unlocked() == recalculate_used(),
5326 "inconsistent used_unlocked(), "
5327 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5328 used_unlocked(), recalculate_used());
5329 }
5330
5331 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5332 _refine_cte_cl->set_concurrent(concurrent);
5333 }
5334
5335 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5336 HeapRegion* hr = heap_region_containing(p);
5337 return hr->is_in(p);
5338 }
5339
5340 // Methods for the mutator alloc region
5341
5342 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5343 bool force) {
5344 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5345 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5346 if (force || should_allocate) {
5347 HeapRegion* new_alloc_region = new_region(word_size,
5348 false /* is_old */,
5349 false /* do_expand */);
5350 if (new_alloc_region != NULL) {
5351 set_region_short_lived_locked(new_alloc_region);
5352 _hr_printer.alloc(new_alloc_region, !should_allocate);
5353 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5354 return new_alloc_region;
5355 }
5356 }
5357 return NULL;
5358 }
5359
5360 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5361 size_t allocated_bytes) {
5362 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5363 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5364
5365 collection_set()->add_eden_region(alloc_region);
5366 increase_used(allocated_bytes);
5367 _hr_printer.retire(alloc_region);
5368 // We update the eden sizes here, when the region is retired,
5369 // instead of when it's allocated, since this is the point that its
5370 // used space has been recored in _summary_bytes_used.
5371 g1mm()->update_eden_size();
5372 }
5373
5374 // Methods for the GC alloc regions
5375
5376 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5377 if (dest.is_old()) {
5378 return true;
5379 } else {
5380 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5381 }
5382 }
5383
5384 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5385 assert(FreeList_lock->owned_by_self(), "pre-condition");
5386
5387 if (!has_more_regions(dest)) {
5388 return NULL;
5389 }
5390
5391 const bool is_survivor = dest.is_young();
5392
5393 HeapRegion* new_alloc_region = new_region(word_size,
5394 !is_survivor,
5395 true /* do_expand */);
5396 if (new_alloc_region != NULL) {
5397 // We really only need to do this for old regions given that we
5398 // should never scan survivors. But it doesn't hurt to do it
5399 // for survivors too.
5400 new_alloc_region->record_timestamp();
5401 if (is_survivor) {
5402 new_alloc_region->set_survivor();
5403 _survivor.add(new_alloc_region);
5404 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5405 } else {
5406 new_alloc_region->set_old();
5407 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5408 }
5409 _hr_printer.alloc(new_alloc_region);
5410 bool during_im = collector_state()->during_initial_mark_pause();
5411 new_alloc_region->note_start_of_copying(during_im);
5412 return new_alloc_region;
5413 }
5414 return NULL;
5415 }
5416
5417 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5418 size_t allocated_bytes,
5419 InCSetState dest) {
5420 bool during_im = collector_state()->during_initial_mark_pause();
5421 alloc_region->note_end_of_copying(during_im);
5422 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5423 if (dest.is_old()) {
5424 _old_set.add(alloc_region);
5425 }
5426 _hr_printer.retire(alloc_region);
5427 }
5428
5429 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5430 bool expanded = false;
5431 uint index = _hrm.find_highest_free(&expanded);
5432
5433 if (index != G1_NO_HRM_INDEX) {
5434 if (expanded) {
5435 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5436 HeapRegion::GrainWords * HeapWordSize);
5437 }
5438 _hrm.allocate_free_regions_starting_at(index, 1);
5439 return region_at(index);
5440 }
5441 return NULL;
5442 }
5443
5444 // Optimized nmethod scanning
5445
5446 class RegisterNMethodOopClosure: public OopClosure {
5447 G1CollectedHeap* _g1h;
5448 nmethod* _nm;
5449
5450 template <class T> void do_oop_work(T* p) {
5451 T heap_oop = oopDesc::load_heap_oop(p);
5452 if (!oopDesc::is_null(heap_oop)) {
5453 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5454 HeapRegion* hr = _g1h->heap_region_containing(obj);
5455 assert(!hr->is_continues_humongous(),
5456 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5457 " starting at " HR_FORMAT,
5458 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5459
5460 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5461 hr->add_strong_code_root_locked(_nm);
5462 }
5463 }
5464
5465 public:
5466 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5467 _g1h(g1h), _nm(nm) {}
5468
5469 void do_oop(oop* p) { do_oop_work(p); }
5470 void do_oop(narrowOop* p) { do_oop_work(p); }
5471 };
5472
5473 class UnregisterNMethodOopClosure: public OopClosure {
5474 G1CollectedHeap* _g1h;
5475 nmethod* _nm;
5476
5477 template <class T> void do_oop_work(T* p) {
5478 T heap_oop = oopDesc::load_heap_oop(p);
5479 if (!oopDesc::is_null(heap_oop)) {
5480 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5481 HeapRegion* hr = _g1h->heap_region_containing(obj);
5482 assert(!hr->is_continues_humongous(),
5483 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5484 " starting at " HR_FORMAT,
5485 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5486
5487 hr->remove_strong_code_root(_nm);
5488 }
5489 }
5490
5491 public:
5492 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5493 _g1h(g1h), _nm(nm) {}
5494
5495 void do_oop(oop* p) { do_oop_work(p); }
5496 void do_oop(narrowOop* p) { do_oop_work(p); }
5497 };
5498
5499 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5500 CollectedHeap::register_nmethod(nm);
5501
5502 guarantee(nm != NULL, "sanity");
5503 RegisterNMethodOopClosure reg_cl(this, nm);
5504 nm->oops_do(®_cl);
5505 }
5506
5507 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5508 CollectedHeap::unregister_nmethod(nm);
5509
5510 guarantee(nm != NULL, "sanity");
5511 UnregisterNMethodOopClosure reg_cl(this, nm);
5512 nm->oops_do(®_cl, true);
5513 }
5514
5515 void G1CollectedHeap::purge_code_root_memory() {
5516 double purge_start = os::elapsedTime();
5517 G1CodeRootSet::purge();
5518 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5519 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5520 }
5521
5522 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5523 G1CollectedHeap* _g1h;
5524
5525 public:
5526 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5527 _g1h(g1h) {}
5528
5529 void do_code_blob(CodeBlob* cb) {
5530 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5531 if (nm == NULL) {
5532 return;
5533 }
5534
5535 if (ScavengeRootsInCode) {
5536 _g1h->register_nmethod(nm);
5537 }
5538 }
5539 };
5540
5541 void G1CollectedHeap::rebuild_strong_code_roots() {
5542 RebuildStrongCodeRootClosure blob_cl(this);
5543 CodeCache::blobs_do(&blob_cl);
5544 }