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