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 in G1MarkSweep. We have to let it know
703 // about each archive range, so that objects in those ranges aren't marked.
704 G1MarkSweep::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 G1MarkSweep::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 G1MarkSweep::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 a new incremental collection set for the next pause
1382 collection_set()->start_incremental_building();
1383
1384 clear_cset_fast_test();
1385
1386 _allocator->init_mutator_alloc_region();
1387
1388 g1_policy()->record_full_collection_end();
1389
1390 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1391 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1392 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1393 // before any GC notifications are raised.
1394 g1mm()->update_sizes();
1395
1396 gc_epilogue(true);
1397
1398 heap_transition.print();
1399
1400 print_heap_after_gc();
1401 print_heap_regions();
1402 trace_heap_after_gc(gc_tracer);
1403
1404 post_full_gc_dump(gc_timer);
1405 }
1406
1407 gc_timer->register_gc_end();
1408 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1409 }
1410
1411 return true;
1412 }
1413
1414 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1415 // Currently, there is no facility in the do_full_collection(bool) API to notify
1416 // the caller that the collection did not succeed (e.g., because it was locked
1417 // out by the GC locker). So, right now, we'll ignore the return value.
1418 bool dummy = do_full_collection(true, /* explicit_gc */
1419 clear_all_soft_refs);
1420 }
1421
1422 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1423 // Include bytes that will be pre-allocated to support collections, as "used".
1424 const size_t used_after_gc = used();
1425 const size_t capacity_after_gc = capacity();
1426 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1427
1428 // This is enforced in arguments.cpp.
1429 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1430 "otherwise the code below doesn't make sense");
1431
1432 // We don't have floating point command-line arguments
1433 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1434 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1435 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1436 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1437
1438 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1439 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1440
1441 // We have to be careful here as these two calculations can overflow
1442 // 32-bit size_t's.
1443 double used_after_gc_d = (double) used_after_gc;
1444 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1445 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1446
1447 // Let's make sure that they are both under the max heap size, which
1448 // by default will make them fit into a size_t.
1449 double desired_capacity_upper_bound = (double) max_heap_size;
1450 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1451 desired_capacity_upper_bound);
1452 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1453 desired_capacity_upper_bound);
1454
1455 // We can now safely turn them into size_t's.
1456 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1457 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1458
1459 // This assert only makes sense here, before we adjust them
1460 // with respect to the min and max heap size.
1461 assert(minimum_desired_capacity <= maximum_desired_capacity,
1462 "minimum_desired_capacity = " SIZE_FORMAT ", "
1463 "maximum_desired_capacity = " SIZE_FORMAT,
1464 minimum_desired_capacity, maximum_desired_capacity);
1465
1466 // Should not be greater than the heap max size. No need to adjust
1467 // it with respect to the heap min size as it's a lower bound (i.e.,
1468 // we'll try to make the capacity larger than it, not smaller).
1469 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1470 // Should not be less than the heap min size. No need to adjust it
1471 // with respect to the heap max size as it's an upper bound (i.e.,
1472 // we'll try to make the capacity smaller than it, not greater).
1473 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1474
1475 if (capacity_after_gc < minimum_desired_capacity) {
1476 // Don't expand unless it's significant
1477 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1478
1479 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1480 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1481 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1482
1483 expand(expand_bytes, _workers);
1484
1485 // No expansion, now see if we want to shrink
1486 } else if (capacity_after_gc > maximum_desired_capacity) {
1487 // Capacity too large, compute shrinking size
1488 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1489
1490 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1491 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1492 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1493
1494 shrink(shrink_bytes);
1495 }
1496 }
1497
1498 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1499 AllocationContext_t context,
1500 bool do_gc,
1501 bool clear_all_soft_refs,
1502 bool expect_null_mutator_alloc_region,
1503 bool* gc_succeeded) {
1504 *gc_succeeded = true;
1505 // Let's attempt the allocation first.
1506 HeapWord* result =
1507 attempt_allocation_at_safepoint(word_size,
1508 context,
1509 expect_null_mutator_alloc_region);
1510 if (result != NULL) {
1511 assert(*gc_succeeded, "sanity");
1512 return result;
1513 }
1514
1515 // In a G1 heap, we're supposed to keep allocation from failing by
1516 // incremental pauses. Therefore, at least for now, we'll favor
1517 // expansion over collection. (This might change in the future if we can
1518 // do something smarter than full collection to satisfy a failed alloc.)
1519 result = expand_and_allocate(word_size, context);
1520 if (result != NULL) {
1521 assert(*gc_succeeded, "sanity");
1522 return result;
1523 }
1524
1525 if (do_gc) {
1526 // Expansion didn't work, we'll try to do a Full GC.
1527 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1528 clear_all_soft_refs);
1529 }
1530
1531 return NULL;
1532 }
1533
1534 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1535 AllocationContext_t context,
1536 bool* succeeded) {
1537 assert_at_safepoint(true /* should_be_vm_thread */);
1538
1539 // Attempts to allocate followed by Full GC.
1540 HeapWord* result =
1541 satisfy_failed_allocation_helper(word_size,
1542 context,
1543 true, /* do_gc */
1544 false, /* clear_all_soft_refs */
1545 false, /* expect_null_mutator_alloc_region */
1546 succeeded);
1547
1548 if (result != NULL || !*succeeded) {
1549 return result;
1550 }
1551
1552 // Attempts to allocate followed by Full GC that will collect all soft references.
1553 result = satisfy_failed_allocation_helper(word_size,
1554 context,
1555 true, /* do_gc */
1556 true, /* clear_all_soft_refs */
1557 true, /* expect_null_mutator_alloc_region */
1558 succeeded);
1559
1560 if (result != NULL || !*succeeded) {
1561 return result;
1562 }
1563
1564 // Attempts to allocate, no GC
1565 result = satisfy_failed_allocation_helper(word_size,
1566 context,
1567 false, /* do_gc */
1568 false, /* clear_all_soft_refs */
1569 true, /* expect_null_mutator_alloc_region */
1570 succeeded);
1571
1572 if (result != NULL) {
1573 assert(*succeeded, "sanity");
1574 return result;
1575 }
1576
1577 assert(!collector_policy()->should_clear_all_soft_refs(),
1578 "Flag should have been handled and cleared prior to this point");
1579
1580 // What else? We might try synchronous finalization later. If the total
1581 // space available is large enough for the allocation, then a more
1582 // complete compaction phase than we've tried so far might be
1583 // appropriate.
1584 assert(*succeeded, "sanity");
1585 return NULL;
1586 }
1587
1588 // Attempting to expand the heap sufficiently
1589 // to support an allocation of the given "word_size". If
1590 // successful, perform the allocation and return the address of the
1591 // allocated block, or else "NULL".
1592
1593 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1594 assert_at_safepoint(true /* should_be_vm_thread */);
1595
1596 _verifier->verify_region_sets_optional();
1597
1598 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1599 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1600 word_size * HeapWordSize);
1601
1602
1603 if (expand(expand_bytes, _workers)) {
1604 _hrm.verify_optional();
1605 _verifier->verify_region_sets_optional();
1606 return attempt_allocation_at_safepoint(word_size,
1607 context,
1608 false /* expect_null_mutator_alloc_region */);
1609 }
1610 return NULL;
1611 }
1612
1613 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1614 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1615 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1616 HeapRegion::GrainBytes);
1617
1618 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1619 expand_bytes, aligned_expand_bytes);
1620
1621 if (is_maximal_no_gc()) {
1622 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1623 return false;
1624 }
1625
1626 double expand_heap_start_time_sec = os::elapsedTime();
1627 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1628 assert(regions_to_expand > 0, "Must expand by at least one region");
1629
1630 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1631 if (expand_time_ms != NULL) {
1632 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1633 }
1634
1635 if (expanded_by > 0) {
1636 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1637 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1638 g1_policy()->record_new_heap_size(num_regions());
1639 } else {
1640 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1641
1642 // The expansion of the virtual storage space was unsuccessful.
1643 // Let's see if it was because we ran out of swap.
1644 if (G1ExitOnExpansionFailure &&
1645 _hrm.available() >= regions_to_expand) {
1646 // We had head room...
1647 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1648 }
1649 }
1650 return regions_to_expand > 0;
1651 }
1652
1653 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1654 size_t aligned_shrink_bytes =
1655 ReservedSpace::page_align_size_down(shrink_bytes);
1656 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1657 HeapRegion::GrainBytes);
1658 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1659
1660 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1661 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1662
1663
1664 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",
1665 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1666 if (num_regions_removed > 0) {
1667 g1_policy()->record_new_heap_size(num_regions());
1668 } else {
1669 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1670 }
1671 }
1672
1673 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1674 _verifier->verify_region_sets_optional();
1675
1676 // We should only reach here at the end of a Full GC which means we
1677 // should not not be holding to any GC alloc regions. The method
1678 // below will make sure of that and do any remaining clean up.
1679 _allocator->abandon_gc_alloc_regions();
1680
1681 // Instead of tearing down / rebuilding the free lists here, we
1682 // could instead use the remove_all_pending() method on free_list to
1683 // remove only the ones that we need to remove.
1684 tear_down_region_sets(true /* free_list_only */);
1685 shrink_helper(shrink_bytes);
1686 rebuild_region_sets(true /* free_list_only */);
1687
1688 _hrm.verify_optional();
1689 _verifier->verify_region_sets_optional();
1690 }
1691
1692 // Public methods.
1693
1694 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1695 CollectedHeap(),
1696 _collector_policy(collector_policy),
1697 _g1_policy(create_g1_policy()),
1698 _collection_set(this, _g1_policy),
1699 _dirty_card_queue_set(false),
1700 _is_alive_closure_cm(this),
1701 _is_alive_closure_stw(this),
1702 _ref_processor_cm(NULL),
1703 _ref_processor_stw(NULL),
1704 _bot(NULL),
1705 _hot_card_cache(NULL),
1706 _g1_rem_set(NULL),
1707 _cg1r(NULL),
1708 _g1mm(NULL),
1709 _refine_cte_cl(NULL),
1710 _preserved_marks_set(true /* in_c_heap */),
1711 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1712 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1713 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1714 _humongous_reclaim_candidates(),
1715 _has_humongous_reclaim_candidates(false),
1716 _archive_allocator(NULL),
1717 _free_regions_coming(false),
1718 _gc_time_stamp(0),
1719 _summary_bytes_used(0),
1720 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1721 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1722 _expand_heap_after_alloc_failure(true),
1723 _old_marking_cycles_started(0),
1724 _old_marking_cycles_completed(0),
1725 _in_cset_fast_test(),
1726 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1727 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1728
1729 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1730 /* are_GC_task_threads */true,
1731 /* are_ConcurrentGC_threads */false);
1732 _workers->initialize_workers();
1733 _verifier = new G1HeapVerifier(this);
1734
1735 _allocator = G1Allocator::create_allocator(this);
1736
1737 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1738
1739 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1740
1741 // Override the default _filler_array_max_size so that no humongous filler
1742 // objects are created.
1743 _filler_array_max_size = _humongous_object_threshold_in_words;
1744
1745 uint n_queues = ParallelGCThreads;
1746 _task_queues = new RefToScanQueueSet(n_queues);
1747
1748 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1749
1750 for (uint i = 0; i < n_queues; i++) {
1751 RefToScanQueue* q = new RefToScanQueue();
1752 q->initialize();
1753 _task_queues->register_queue(i, q);
1754 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1755 }
1756
1757 // Initialize the G1EvacuationFailureALot counters and flags.
1758 NOT_PRODUCT(reset_evacuation_should_fail();)
1759
1760 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1761 }
1762
1763 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1764 size_t size,
1765 size_t translation_factor) {
1766 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1767 // Allocate a new reserved space, preferring to use large pages.
1768 ReservedSpace rs(size, preferred_page_size);
1769 G1RegionToSpaceMapper* result =
1770 G1RegionToSpaceMapper::create_mapper(rs,
1771 size,
1772 rs.alignment(),
1773 HeapRegion::GrainBytes,
1774 translation_factor,
1775 mtGC);
1776
1777 os::trace_page_sizes_for_requested_size(description,
1778 size,
1779 preferred_page_size,
1780 rs.alignment(),
1781 rs.base(),
1782 rs.size());
1783
1784 return result;
1785 }
1786
1787 jint G1CollectedHeap::initialize() {
1788 CollectedHeap::pre_initialize();
1789 os::enable_vtime();
1790
1791 // Necessary to satisfy locking discipline assertions.
1792
1793 MutexLocker x(Heap_lock);
1794
1795 // While there are no constraints in the GC code that HeapWordSize
1796 // be any particular value, there are multiple other areas in the
1797 // system which believe this to be true (e.g. oop->object_size in some
1798 // cases incorrectly returns the size in wordSize units rather than
1799 // HeapWordSize).
1800 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1801
1802 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1803 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1804 size_t heap_alignment = collector_policy()->heap_alignment();
1805
1806 // Ensure that the sizes are properly aligned.
1807 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1808 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1809 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1810
1811 _refine_cte_cl = new RefineCardTableEntryClosure();
1812
1813 jint ecode = JNI_OK;
1814 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1815 if (_cg1r == NULL) {
1816 return ecode;
1817 }
1818
1819 // Reserve the maximum.
1820
1821 // When compressed oops are enabled, the preferred heap base
1822 // is calculated by subtracting the requested size from the
1823 // 32Gb boundary and using the result as the base address for
1824 // heap reservation. If the requested size is not aligned to
1825 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1826 // into the ReservedHeapSpace constructor) then the actual
1827 // base of the reserved heap may end up differing from the
1828 // address that was requested (i.e. the preferred heap base).
1829 // If this happens then we could end up using a non-optimal
1830 // compressed oops mode.
1831
1832 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1833 heap_alignment);
1834
1835 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1836
1837 // Create the barrier set for the entire reserved region.
1838 G1SATBCardTableLoggingModRefBS* bs
1839 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1840 bs->initialize();
1841 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1842 set_barrier_set(bs);
1843
1844 // Create the hot card cache.
1845 _hot_card_cache = new G1HotCardCache(this);
1846
1847 // Also create a G1 rem set.
1848 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1849
1850 // Carve out the G1 part of the heap.
1851 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1852 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1853 G1RegionToSpaceMapper* heap_storage =
1854 G1RegionToSpaceMapper::create_mapper(g1_rs,
1855 g1_rs.size(),
1856 page_size,
1857 HeapRegion::GrainBytes,
1858 1,
1859 mtJavaHeap);
1860 os::trace_page_sizes("Heap",
1861 collector_policy()->min_heap_byte_size(),
1862 max_byte_size,
1863 page_size,
1864 heap_rs.base(),
1865 heap_rs.size());
1866 heap_storage->set_mapping_changed_listener(&_listener);
1867
1868 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1869 G1RegionToSpaceMapper* bot_storage =
1870 create_aux_memory_mapper("Block Offset Table",
1871 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1872 G1BlockOffsetTable::heap_map_factor());
1873
1874 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1875 G1RegionToSpaceMapper* cardtable_storage =
1876 create_aux_memory_mapper("Card Table",
1877 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1878 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1879
1880 G1RegionToSpaceMapper* card_counts_storage =
1881 create_aux_memory_mapper("Card Counts Table",
1882 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1883 G1CardCounts::heap_map_factor());
1884
1885 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1886 G1RegionToSpaceMapper* prev_bitmap_storage =
1887 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1888 G1RegionToSpaceMapper* next_bitmap_storage =
1889 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1890
1891 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1892 g1_barrier_set()->initialize(cardtable_storage);
1893 // Do later initialization work for concurrent refinement.
1894 _hot_card_cache->initialize(card_counts_storage);
1895
1896 // 6843694 - ensure that the maximum region index can fit
1897 // in the remembered set structures.
1898 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1899 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1900
1901 g1_rem_set()->initialize(max_capacity(), max_regions());
1902
1903 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1904 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1905 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1906 "too many cards per region");
1907
1908 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1909
1910 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1911
1912 {
1913 HeapWord* start = _hrm.reserved().start();
1914 HeapWord* end = _hrm.reserved().end();
1915 size_t granularity = HeapRegion::GrainBytes;
1916
1917 _in_cset_fast_test.initialize(start, end, granularity);
1918 _humongous_reclaim_candidates.initialize(start, end, granularity);
1919 }
1920
1921 // Create the G1ConcurrentMark data structure and thread.
1922 // (Must do this late, so that "max_regions" is defined.)
1923 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1924 if (_cm == NULL || !_cm->completed_initialization()) {
1925 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1926 return JNI_ENOMEM;
1927 }
1928 _cmThread = _cm->cmThread();
1929
1930 // Now expand into the initial heap size.
1931 if (!expand(init_byte_size, _workers)) {
1932 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1933 return JNI_ENOMEM;
1934 }
1935
1936 // Perform any initialization actions delegated to the policy.
1937 g1_policy()->init(this, &_collection_set);
1938
1939 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1940 SATB_Q_FL_lock,
1941 G1SATBProcessCompletedThreshold,
1942 Shared_SATB_Q_lock);
1943
1944 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1945 DirtyCardQ_CBL_mon,
1946 DirtyCardQ_FL_lock,
1947 (int)concurrent_g1_refine()->yellow_zone(),
1948 (int)concurrent_g1_refine()->red_zone(),
1949 Shared_DirtyCardQ_lock,
1950 NULL, // fl_owner
1951 true); // init_free_ids
1952
1953 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1954 DirtyCardQ_CBL_mon,
1955 DirtyCardQ_FL_lock,
1956 -1, // never trigger processing
1957 -1, // no limit on length
1958 Shared_DirtyCardQ_lock,
1959 &JavaThread::dirty_card_queue_set());
1960
1961 // Here we allocate the dummy HeapRegion that is required by the
1962 // G1AllocRegion class.
1963 HeapRegion* dummy_region = _hrm.get_dummy_region();
1964
1965 // We'll re-use the same region whether the alloc region will
1966 // require BOT updates or not and, if it doesn't, then a non-young
1967 // region will complain that it cannot support allocations without
1968 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1969 dummy_region->set_eden();
1970 // Make sure it's full.
1971 dummy_region->set_top(dummy_region->end());
1972 G1AllocRegion::setup(this, dummy_region);
1973
1974 _allocator->init_mutator_alloc_region();
1975
1976 // Do create of the monitoring and management support so that
1977 // values in the heap have been properly initialized.
1978 _g1mm = new G1MonitoringSupport(this);
1979
1980 G1StringDedup::initialize();
1981
1982 _preserved_marks_set.init(ParallelGCThreads);
1983
1984 _collection_set.initialize(max_regions());
1985
1986 return JNI_OK;
1987 }
1988
1989 void G1CollectedHeap::stop() {
1990 // Stop all concurrent threads. We do this to make sure these threads
1991 // do not continue to execute and access resources (e.g. logging)
1992 // that are destroyed during shutdown.
1993 _cg1r->stop();
1994 _cmThread->stop();
1995 if (G1StringDedup::is_enabled()) {
1996 G1StringDedup::stop();
1997 }
1998 }
1999
2000 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2001 return HeapRegion::max_region_size();
2002 }
2003
2004 void G1CollectedHeap::post_initialize() {
2005 ref_processing_init();
2006 }
2007
2008 void G1CollectedHeap::ref_processing_init() {
2009 // Reference processing in G1 currently works as follows:
2010 //
2011 // * There are two reference processor instances. One is
2012 // used to record and process discovered references
2013 // during concurrent marking; the other is used to
2014 // record and process references during STW pauses
2015 // (both full and incremental).
2016 // * Both ref processors need to 'span' the entire heap as
2017 // the regions in the collection set may be dotted around.
2018 //
2019 // * For the concurrent marking ref processor:
2020 // * Reference discovery is enabled at initial marking.
2021 // * Reference discovery is disabled and the discovered
2022 // references processed etc during remarking.
2023 // * Reference discovery is MT (see below).
2024 // * Reference discovery requires a barrier (see below).
2025 // * Reference processing may or may not be MT
2026 // (depending on the value of ParallelRefProcEnabled
2027 // and ParallelGCThreads).
2028 // * A full GC disables reference discovery by the CM
2029 // ref processor and abandons any entries on it's
2030 // discovered lists.
2031 //
2032 // * For the STW processor:
2033 // * Non MT discovery is enabled at the start of a full GC.
2034 // * Processing and enqueueing during a full GC is non-MT.
2035 // * During a full GC, references are processed after marking.
2036 //
2037 // * Discovery (may or may not be MT) is enabled at the start
2038 // of an incremental evacuation pause.
2039 // * References are processed near the end of a STW evacuation pause.
2040 // * For both types of GC:
2041 // * Discovery is atomic - i.e. not concurrent.
2042 // * Reference discovery will not need a barrier.
2043
2044 MemRegion mr = reserved_region();
2045
2046 // Concurrent Mark ref processor
2047 _ref_processor_cm =
2048 new ReferenceProcessor(mr, // span
2049 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2050 // mt processing
2051 ParallelGCThreads,
2052 // degree of mt processing
2053 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2054 // mt discovery
2055 MAX2(ParallelGCThreads, ConcGCThreads),
2056 // degree of mt discovery
2057 false,
2058 // Reference discovery is not atomic
2059 &_is_alive_closure_cm);
2060 // is alive closure
2061 // (for efficiency/performance)
2062
2063 // STW ref processor
2064 _ref_processor_stw =
2065 new ReferenceProcessor(mr, // span
2066 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2067 // mt processing
2068 ParallelGCThreads,
2069 // degree of mt processing
2070 (ParallelGCThreads > 1),
2071 // mt discovery
2072 ParallelGCThreads,
2073 // degree of mt discovery
2074 true,
2075 // Reference discovery is atomic
2076 &_is_alive_closure_stw);
2077 // is alive closure
2078 // (for efficiency/performance)
2079 }
2080
2081 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2082 return _collector_policy;
2083 }
2084
2085 size_t G1CollectedHeap::capacity() const {
2086 return _hrm.length() * HeapRegion::GrainBytes;
2087 }
2088
2089 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2090 hr->reset_gc_time_stamp();
2091 }
2092
2093 #ifndef PRODUCT
2094
2095 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2096 private:
2097 unsigned _gc_time_stamp;
2098 bool _failures;
2099
2100 public:
2101 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2102 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2103
2104 virtual bool doHeapRegion(HeapRegion* hr) {
2105 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2106 if (_gc_time_stamp != region_gc_time_stamp) {
2107 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2108 region_gc_time_stamp, _gc_time_stamp);
2109 _failures = true;
2110 }
2111 return false;
2112 }
2113
2114 bool failures() { return _failures; }
2115 };
2116
2117 void G1CollectedHeap::check_gc_time_stamps() {
2118 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2119 heap_region_iterate(&cl);
2120 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2121 }
2122 #endif // PRODUCT
2123
2124 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2125 _hot_card_cache->drain(cl, worker_i);
2126 }
2127
2128 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2129 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2130 size_t n_completed_buffers = 0;
2131 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2132 n_completed_buffers++;
2133 }
2134 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2135 dcqs.clear_n_completed_buffers();
2136 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2137 }
2138
2139 // Computes the sum of the storage used by the various regions.
2140 size_t G1CollectedHeap::used() const {
2141 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2142 if (_archive_allocator != NULL) {
2143 result += _archive_allocator->used();
2144 }
2145 return result;
2146 }
2147
2148 size_t G1CollectedHeap::used_unlocked() const {
2149 return _summary_bytes_used;
2150 }
2151
2152 class SumUsedClosure: public HeapRegionClosure {
2153 size_t _used;
2154 public:
2155 SumUsedClosure() : _used(0) {}
2156 bool doHeapRegion(HeapRegion* r) {
2157 _used += r->used();
2158 return false;
2159 }
2160 size_t result() { return _used; }
2161 };
2162
2163 size_t G1CollectedHeap::recalculate_used() const {
2164 double recalculate_used_start = os::elapsedTime();
2165
2166 SumUsedClosure blk;
2167 heap_region_iterate(&blk);
2168
2169 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2170 return blk.result();
2171 }
2172
2173 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2174 switch (cause) {
2175 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2176 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2177 case GCCause::_update_allocation_context_stats_inc: return true;
2178 case GCCause::_wb_conc_mark: return true;
2179 default : return false;
2180 }
2181 }
2182
2183 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2184 switch (cause) {
2185 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2186 case GCCause::_g1_humongous_allocation: return true;
2187 default: return is_user_requested_concurrent_full_gc(cause);
2188 }
2189 }
2190
2191 #ifndef PRODUCT
2192 void G1CollectedHeap::allocate_dummy_regions() {
2193 // Let's fill up most of the region
2194 size_t word_size = HeapRegion::GrainWords - 1024;
2195 // And as a result the region we'll allocate will be humongous.
2196 guarantee(is_humongous(word_size), "sanity");
2197
2198 // _filler_array_max_size is set to humongous object threshold
2199 // but temporarily change it to use CollectedHeap::fill_with_object().
2200 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2201
2202 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2203 // Let's use the existing mechanism for the allocation
2204 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2205 AllocationContext::system());
2206 if (dummy_obj != NULL) {
2207 MemRegion mr(dummy_obj, word_size);
2208 CollectedHeap::fill_with_object(mr);
2209 } else {
2210 // If we can't allocate once, we probably cannot allocate
2211 // again. Let's get out of the loop.
2212 break;
2213 }
2214 }
2215 }
2216 #endif // !PRODUCT
2217
2218 void G1CollectedHeap::increment_old_marking_cycles_started() {
2219 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2220 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2221 "Wrong marking cycle count (started: %d, completed: %d)",
2222 _old_marking_cycles_started, _old_marking_cycles_completed);
2223
2224 _old_marking_cycles_started++;
2225 }
2226
2227 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2228 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2229
2230 // We assume that if concurrent == true, then the caller is a
2231 // concurrent thread that was joined the Suspendible Thread
2232 // Set. If there's ever a cheap way to check this, we should add an
2233 // assert here.
2234
2235 // Given that this method is called at the end of a Full GC or of a
2236 // concurrent cycle, and those can be nested (i.e., a Full GC can
2237 // interrupt a concurrent cycle), the number of full collections
2238 // completed should be either one (in the case where there was no
2239 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2240 // behind the number of full collections started.
2241
2242 // This is the case for the inner caller, i.e. a Full GC.
2243 assert(concurrent ||
2244 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2245 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2246 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2247 "is inconsistent with _old_marking_cycles_completed = %u",
2248 _old_marking_cycles_started, _old_marking_cycles_completed);
2249
2250 // This is the case for the outer caller, i.e. the concurrent cycle.
2251 assert(!concurrent ||
2252 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2253 "for outer caller (concurrent cycle): "
2254 "_old_marking_cycles_started = %u "
2255 "is inconsistent with _old_marking_cycles_completed = %u",
2256 _old_marking_cycles_started, _old_marking_cycles_completed);
2257
2258 _old_marking_cycles_completed += 1;
2259
2260 // We need to clear the "in_progress" flag in the CM thread before
2261 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2262 // is set) so that if a waiter requests another System.gc() it doesn't
2263 // incorrectly see that a marking cycle is still in progress.
2264 if (concurrent) {
2265 _cmThread->set_idle();
2266 }
2267
2268 // This notify_all() will ensure that a thread that called
2269 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2270 // and it's waiting for a full GC to finish will be woken up. It is
2271 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2272 FullGCCount_lock->notify_all();
2273 }
2274
2275 void G1CollectedHeap::collect(GCCause::Cause cause) {
2276 assert_heap_not_locked();
2277
2278 uint gc_count_before;
2279 uint old_marking_count_before;
2280 uint full_gc_count_before;
2281 bool retry_gc;
2282
2283 do {
2284 retry_gc = false;
2285
2286 {
2287 MutexLocker ml(Heap_lock);
2288
2289 // Read the GC count while holding the Heap_lock
2290 gc_count_before = total_collections();
2291 full_gc_count_before = total_full_collections();
2292 old_marking_count_before = _old_marking_cycles_started;
2293 }
2294
2295 if (should_do_concurrent_full_gc(cause)) {
2296 // Schedule an initial-mark evacuation pause that will start a
2297 // concurrent cycle. We're setting word_size to 0 which means that
2298 // we are not requesting a post-GC allocation.
2299 VM_G1IncCollectionPause op(gc_count_before,
2300 0, /* word_size */
2301 true, /* should_initiate_conc_mark */
2302 g1_policy()->max_pause_time_ms(),
2303 cause);
2304 op.set_allocation_context(AllocationContext::current());
2305
2306 VMThread::execute(&op);
2307 if (!op.pause_succeeded()) {
2308 if (old_marking_count_before == _old_marking_cycles_started) {
2309 retry_gc = op.should_retry_gc();
2310 } else {
2311 // A Full GC happened while we were trying to schedule the
2312 // initial-mark GC. No point in starting a new cycle given
2313 // that the whole heap was collected anyway.
2314 }
2315
2316 if (retry_gc) {
2317 if (GCLocker::is_active_and_needs_gc()) {
2318 GCLocker::stall_until_clear();
2319 }
2320 }
2321 }
2322 } else {
2323 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2324 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2325
2326 // Schedule a standard evacuation pause. We're setting word_size
2327 // to 0 which means that we are not requesting a post-GC allocation.
2328 VM_G1IncCollectionPause op(gc_count_before,
2329 0, /* word_size */
2330 false, /* should_initiate_conc_mark */
2331 g1_policy()->max_pause_time_ms(),
2332 cause);
2333 VMThread::execute(&op);
2334 } else {
2335 // Schedule a Full GC.
2336 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2337 VMThread::execute(&op);
2338 }
2339 }
2340 } while (retry_gc);
2341 }
2342
2343 bool G1CollectedHeap::is_in(const void* p) const {
2344 if (_hrm.reserved().contains(p)) {
2345 // Given that we know that p is in the reserved space,
2346 // heap_region_containing() should successfully
2347 // return the containing region.
2348 HeapRegion* hr = heap_region_containing(p);
2349 return hr->is_in(p);
2350 } else {
2351 return false;
2352 }
2353 }
2354
2355 #ifdef ASSERT
2356 bool G1CollectedHeap::is_in_exact(const void* p) const {
2357 bool contains = reserved_region().contains(p);
2358 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2359 if (contains && available) {
2360 return true;
2361 } else {
2362 return false;
2363 }
2364 }
2365 #endif
2366
2367 bool G1CollectedHeap::obj_in_cs(oop obj) {
2368 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2369 return r != NULL && r->in_collection_set();
2370 }
2371
2372 // Iteration functions.
2373
2374 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2375
2376 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2377 ExtendedOopClosure* _cl;
2378 public:
2379 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2380 bool doHeapRegion(HeapRegion* r) {
2381 if (!r->is_continues_humongous()) {
2382 r->oop_iterate(_cl);
2383 }
2384 return false;
2385 }
2386 };
2387
2388 // Iterates an ObjectClosure over all objects within a HeapRegion.
2389
2390 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2391 ObjectClosure* _cl;
2392 public:
2393 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2394 bool doHeapRegion(HeapRegion* r) {
2395 if (!r->is_continues_humongous()) {
2396 r->object_iterate(_cl);
2397 }
2398 return false;
2399 }
2400 };
2401
2402 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2403 IterateObjectClosureRegionClosure blk(cl);
2404 heap_region_iterate(&blk);
2405 }
2406
2407 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2408 _hrm.iterate(cl);
2409 }
2410
2411 void
2412 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2413 uint worker_id,
2414 HeapRegionClaimer *hrclaimer,
2415 bool concurrent) const {
2416 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2417 }
2418
2419 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2420 _collection_set.iterate(cl);
2421 }
2422
2423 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2424 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2425 }
2426
2427 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2428 HeapRegion* result = _hrm.next_region_in_heap(from);
2429 while (result != NULL && result->is_pinned()) {
2430 result = _hrm.next_region_in_heap(result);
2431 }
2432 return result;
2433 }
2434
2435 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2436 HeapRegion* hr = heap_region_containing(addr);
2437 return hr->block_start(addr);
2438 }
2439
2440 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2441 HeapRegion* hr = heap_region_containing(addr);
2442 return hr->block_size(addr);
2443 }
2444
2445 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2446 HeapRegion* hr = heap_region_containing(addr);
2447 return hr->block_is_obj(addr);
2448 }
2449
2450 bool G1CollectedHeap::supports_tlab_allocation() const {
2451 return true;
2452 }
2453
2454 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2455 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2456 }
2457
2458 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2459 return _eden.length() * HeapRegion::GrainBytes;
2460 }
2461
2462 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2463 // must be equal to the humongous object limit.
2464 size_t G1CollectedHeap::max_tlab_size() const {
2465 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2466 }
2467
2468 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2469 AllocationContext_t context = AllocationContext::current();
2470 return _allocator->unsafe_max_tlab_alloc(context);
2471 }
2472
2473 size_t G1CollectedHeap::max_capacity() const {
2474 return _hrm.reserved().byte_size();
2475 }
2476
2477 jlong G1CollectedHeap::millis_since_last_gc() {
2478 // See the notes in GenCollectedHeap::millis_since_last_gc()
2479 // for more information about the implementation.
2480 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2481 _g1_policy->collection_pause_end_millis();
2482 if (ret_val < 0) {
2483 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2484 ". returning zero instead.", ret_val);
2485 return 0;
2486 }
2487 return ret_val;
2488 }
2489
2490 void G1CollectedHeap::prepare_for_verify() {
2491 _verifier->prepare_for_verify();
2492 }
2493
2494 void G1CollectedHeap::verify(VerifyOption vo) {
2495 _verifier->verify(vo);
2496 }
2497
2498 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2499 return true;
2500 }
2501
2502 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2503 return _cmThread->request_concurrent_phase(phase);
2504 }
2505
2506 class PrintRegionClosure: public HeapRegionClosure {
2507 outputStream* _st;
2508 public:
2509 PrintRegionClosure(outputStream* st) : _st(st) {}
2510 bool doHeapRegion(HeapRegion* r) {
2511 r->print_on(_st);
2512 return false;
2513 }
2514 };
2515
2516 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2517 const HeapRegion* hr,
2518 const VerifyOption vo) const {
2519 switch (vo) {
2520 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2521 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2522 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2523 default: ShouldNotReachHere();
2524 }
2525 return false; // keep some compilers happy
2526 }
2527
2528 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2529 const VerifyOption vo) const {
2530 switch (vo) {
2531 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2532 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2533 case VerifyOption_G1UseMarkWord: {
2534 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2535 return !obj->is_gc_marked() && !hr->is_archive();
2536 }
2537 default: ShouldNotReachHere();
2538 }
2539 return false; // keep some compilers happy
2540 }
2541
2542 void G1CollectedHeap::print_heap_regions() const {
2543 Log(gc, heap, region) log;
2544 if (log.is_trace()) {
2545 ResourceMark rm;
2546 print_regions_on(log.trace_stream());
2547 }
2548 }
2549
2550 void G1CollectedHeap::print_on(outputStream* st) const {
2551 st->print(" %-20s", "garbage-first heap");
2552 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2553 capacity()/K, used_unlocked()/K);
2554 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2555 p2i(_hrm.reserved().start()),
2556 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2557 p2i(_hrm.reserved().end()));
2558 st->cr();
2559 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2560 uint young_regions = young_regions_count();
2561 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2562 (size_t) young_regions * HeapRegion::GrainBytes / K);
2563 uint survivor_regions = survivor_regions_count();
2564 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2565 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2566 st->cr();
2567 MetaspaceAux::print_on(st);
2568 }
2569
2570 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2571 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2572 "HS=humongous(starts), HC=humongous(continues), "
2573 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2574 "AC=allocation context, "
2575 "TAMS=top-at-mark-start (previous, next)");
2576 PrintRegionClosure blk(st);
2577 heap_region_iterate(&blk);
2578 }
2579
2580 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2581 print_on(st);
2582
2583 // Print the per-region information.
2584 print_regions_on(st);
2585 }
2586
2587 void G1CollectedHeap::print_on_error(outputStream* st) const {
2588 this->CollectedHeap::print_on_error(st);
2589
2590 if (_cm != NULL) {
2591 st->cr();
2592 _cm->print_on_error(st);
2593 }
2594 }
2595
2596 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2597 workers()->print_worker_threads_on(st);
2598 _cmThread->print_on(st);
2599 st->cr();
2600 _cm->print_worker_threads_on(st);
2601 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2602 if (G1StringDedup::is_enabled()) {
2603 G1StringDedup::print_worker_threads_on(st);
2604 }
2605 }
2606
2607 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2608 workers()->threads_do(tc);
2609 tc->do_thread(_cmThread);
2610 _cm->threads_do(tc);
2611 _cg1r->threads_do(tc); // also iterates over the sample thread
2612 if (G1StringDedup::is_enabled()) {
2613 G1StringDedup::threads_do(tc);
2614 }
2615 }
2616
2617 void G1CollectedHeap::print_tracing_info() const {
2618 g1_rem_set()->print_summary_info();
2619 concurrent_mark()->print_summary_info();
2620 }
2621
2622 #ifndef PRODUCT
2623 // Helpful for debugging RSet issues.
2624
2625 class PrintRSetsClosure : public HeapRegionClosure {
2626 private:
2627 const char* _msg;
2628 size_t _occupied_sum;
2629
2630 public:
2631 bool doHeapRegion(HeapRegion* r) {
2632 HeapRegionRemSet* hrrs = r->rem_set();
2633 size_t occupied = hrrs->occupied();
2634 _occupied_sum += occupied;
2635
2636 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2637 if (occupied == 0) {
2638 tty->print_cr(" RSet is empty");
2639 } else {
2640 hrrs->print();
2641 }
2642 tty->print_cr("----------");
2643 return false;
2644 }
2645
2646 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2647 tty->cr();
2648 tty->print_cr("========================================");
2649 tty->print_cr("%s", msg);
2650 tty->cr();
2651 }
2652
2653 ~PrintRSetsClosure() {
2654 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2655 tty->print_cr("========================================");
2656 tty->cr();
2657 }
2658 };
2659
2660 void G1CollectedHeap::print_cset_rsets() {
2661 PrintRSetsClosure cl("Printing CSet RSets");
2662 collection_set_iterate(&cl);
2663 }
2664
2665 void G1CollectedHeap::print_all_rsets() {
2666 PrintRSetsClosure cl("Printing All RSets");;
2667 heap_region_iterate(&cl);
2668 }
2669 #endif // PRODUCT
2670
2671 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2672
2673 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2674 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2675 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2676
2677 size_t eden_capacity_bytes =
2678 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2679
2680 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2681 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2682 eden_capacity_bytes, survivor_used_bytes, num_regions());
2683 }
2684
2685 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2686 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2687 stats->unused(), stats->used(), stats->region_end_waste(),
2688 stats->regions_filled(), stats->direct_allocated(),
2689 stats->failure_used(), stats->failure_waste());
2690 }
2691
2692 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2693 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2694 gc_tracer->report_gc_heap_summary(when, heap_summary);
2695
2696 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2697 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2698 }
2699
2700 G1CollectedHeap* G1CollectedHeap::heap() {
2701 CollectedHeap* heap = Universe::heap();
2702 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2703 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2704 return (G1CollectedHeap*)heap;
2705 }
2706
2707 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2708 // always_do_update_barrier = false;
2709 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2710 // Fill TLAB's and such
2711 accumulate_statistics_all_tlabs();
2712 ensure_parsability(true);
2713
2714 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2715 }
2716
2717 void G1CollectedHeap::gc_epilogue(bool full) {
2718 // we are at the end of the GC. Total collections has already been increased.
2719 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2720
2721 // FIXME: what is this about?
2722 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2723 // is set.
2724 #if defined(COMPILER2) || INCLUDE_JVMCI
2725 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2726 #endif
2727 // always_do_update_barrier = true;
2728
2729 resize_all_tlabs();
2730 allocation_context_stats().update(full);
2731
2732 // We have just completed a GC. Update the soft reference
2733 // policy with the new heap occupancy
2734 Universe::update_heap_info_at_gc();
2735 }
2736
2737 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2738 uint gc_count_before,
2739 bool* succeeded,
2740 GCCause::Cause gc_cause) {
2741 assert_heap_not_locked_and_not_at_safepoint();
2742 VM_G1IncCollectionPause op(gc_count_before,
2743 word_size,
2744 false, /* should_initiate_conc_mark */
2745 g1_policy()->max_pause_time_ms(),
2746 gc_cause);
2747
2748 op.set_allocation_context(AllocationContext::current());
2749 VMThread::execute(&op);
2750
2751 HeapWord* result = op.result();
2752 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2753 assert(result == NULL || ret_succeeded,
2754 "the result should be NULL if the VM did not succeed");
2755 *succeeded = ret_succeeded;
2756
2757 assert_heap_not_locked();
2758 return result;
2759 }
2760
2761 void
2762 G1CollectedHeap::doConcurrentMark() {
2763 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2764 if (!_cmThread->in_progress()) {
2765 _cmThread->set_started();
2766 CGC_lock->notify();
2767 }
2768 }
2769
2770 size_t G1CollectedHeap::pending_card_num() {
2771 size_t extra_cards = 0;
2772 JavaThread *curr = Threads::first();
2773 while (curr != NULL) {
2774 DirtyCardQueue& dcq = curr->dirty_card_queue();
2775 extra_cards += dcq.size();
2776 curr = curr->next();
2777 }
2778 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2779 size_t buffer_size = dcqs.buffer_size();
2780 size_t buffer_num = dcqs.completed_buffers_num();
2781
2782 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2783 // in bytes - not the number of 'entries'. We need to convert
2784 // into a number of cards.
2785 return (buffer_size * buffer_num + extra_cards) / oopSize;
2786 }
2787
2788 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2789 private:
2790 size_t _total_humongous;
2791 size_t _candidate_humongous;
2792
2793 DirtyCardQueue _dcq;
2794
2795 // We don't nominate objects with many remembered set entries, on
2796 // the assumption that such objects are likely still live.
2797 bool is_remset_small(HeapRegion* region) const {
2798 HeapRegionRemSet* const rset = region->rem_set();
2799 return G1EagerReclaimHumongousObjectsWithStaleRefs
2800 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2801 : rset->is_empty();
2802 }
2803
2804 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2805 assert(region->is_starts_humongous(), "Must start a humongous object");
2806
2807 oop obj = oop(region->bottom());
2808
2809 // Dead objects cannot be eager reclaim candidates. Due to class
2810 // unloading it is unsafe to query their classes so we return early.
2811 if (heap->is_obj_dead(obj, region)) {
2812 return false;
2813 }
2814
2815 // Candidate selection must satisfy the following constraints
2816 // while concurrent marking is in progress:
2817 //
2818 // * In order to maintain SATB invariants, an object must not be
2819 // reclaimed if it was allocated before the start of marking and
2820 // has not had its references scanned. Such an object must have
2821 // its references (including type metadata) scanned to ensure no
2822 // live objects are missed by the marking process. Objects
2823 // allocated after the start of concurrent marking don't need to
2824 // be scanned.
2825 //
2826 // * An object must not be reclaimed if it is on the concurrent
2827 // mark stack. Objects allocated after the start of concurrent
2828 // marking are never pushed on the mark stack.
2829 //
2830 // Nominating only objects allocated after the start of concurrent
2831 // marking is sufficient to meet both constraints. This may miss
2832 // some objects that satisfy the constraints, but the marking data
2833 // structures don't support efficiently performing the needed
2834 // additional tests or scrubbing of the mark stack.
2835 //
2836 // However, we presently only nominate is_typeArray() objects.
2837 // A humongous object containing references induces remembered
2838 // set entries on other regions. In order to reclaim such an
2839 // object, those remembered sets would need to be cleaned up.
2840 //
2841 // We also treat is_typeArray() objects specially, allowing them
2842 // to be reclaimed even if allocated before the start of
2843 // concurrent mark. For this we rely on mark stack insertion to
2844 // exclude is_typeArray() objects, preventing reclaiming an object
2845 // that is in the mark stack. We also rely on the metadata for
2846 // such objects to be built-in and so ensured to be kept live.
2847 // Frequent allocation and drop of large binary blobs is an
2848 // important use case for eager reclaim, and this special handling
2849 // may reduce needed headroom.
2850
2851 return obj->is_typeArray() && is_remset_small(region);
2852 }
2853
2854 public:
2855 RegisterHumongousWithInCSetFastTestClosure()
2856 : _total_humongous(0),
2857 _candidate_humongous(0),
2858 _dcq(&JavaThread::dirty_card_queue_set()) {
2859 }
2860
2861 virtual bool doHeapRegion(HeapRegion* r) {
2862 if (!r->is_starts_humongous()) {
2863 return false;
2864 }
2865 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2866
2867 bool is_candidate = humongous_region_is_candidate(g1h, r);
2868 uint rindex = r->hrm_index();
2869 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2870 if (is_candidate) {
2871 _candidate_humongous++;
2872 g1h->register_humongous_region_with_cset(rindex);
2873 // Is_candidate already filters out humongous object with large remembered sets.
2874 // If we have a humongous object with a few remembered sets, we simply flush these
2875 // remembered set entries into the DCQS. That will result in automatic
2876 // re-evaluation of their remembered set entries during the following evacuation
2877 // phase.
2878 if (!r->rem_set()->is_empty()) {
2879 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2880 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2881 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2882 HeapRegionRemSetIterator hrrs(r->rem_set());
2883 size_t card_index;
2884 while (hrrs.has_next(card_index)) {
2885 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2886 // The remembered set might contain references to already freed
2887 // regions. Filter out such entries to avoid failing card table
2888 // verification.
2889 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2890 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2891 *card_ptr = CardTableModRefBS::dirty_card_val();
2892 _dcq.enqueue(card_ptr);
2893 }
2894 }
2895 }
2896 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2897 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2898 hrrs.n_yielded(), r->rem_set()->occupied());
2899 r->rem_set()->clear_locked();
2900 }
2901 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2902 }
2903 _total_humongous++;
2904
2905 return false;
2906 }
2907
2908 size_t total_humongous() const { return _total_humongous; }
2909 size_t candidate_humongous() const { return _candidate_humongous; }
2910
2911 void flush_rem_set_entries() { _dcq.flush(); }
2912 };
2913
2914 void G1CollectedHeap::register_humongous_regions_with_cset() {
2915 if (!G1EagerReclaimHumongousObjects) {
2916 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2917 return;
2918 }
2919 double time = os::elapsed_counter();
2920
2921 // Collect reclaim candidate information and register candidates with cset.
2922 RegisterHumongousWithInCSetFastTestClosure cl;
2923 heap_region_iterate(&cl);
2924
2925 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2926 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2927 cl.total_humongous(),
2928 cl.candidate_humongous());
2929 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2930
2931 // Finally flush all remembered set entries to re-check into the global DCQS.
2932 cl.flush_rem_set_entries();
2933 }
2934
2935 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2936 public:
2937 bool doHeapRegion(HeapRegion* hr) {
2938 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2939 hr->verify_rem_set();
2940 }
2941 return false;
2942 }
2943 };
2944
2945 uint G1CollectedHeap::num_task_queues() const {
2946 return _task_queues->size();
2947 }
2948
2949 #if TASKQUEUE_STATS
2950 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2951 st->print_raw_cr("GC Task Stats");
2952 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2953 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2954 }
2955
2956 void G1CollectedHeap::print_taskqueue_stats() const {
2957 if (!log_is_enabled(Trace, gc, task, stats)) {
2958 return;
2959 }
2960 Log(gc, task, stats) log;
2961 ResourceMark rm;
2962 outputStream* st = log.trace_stream();
2963
2964 print_taskqueue_stats_hdr(st);
2965
2966 TaskQueueStats totals;
2967 const uint n = num_task_queues();
2968 for (uint i = 0; i < n; ++i) {
2969 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2970 totals += task_queue(i)->stats;
2971 }
2972 st->print_raw("tot "); totals.print(st); st->cr();
2973
2974 DEBUG_ONLY(totals.verify());
2975 }
2976
2977 void G1CollectedHeap::reset_taskqueue_stats() {
2978 const uint n = num_task_queues();
2979 for (uint i = 0; i < n; ++i) {
2980 task_queue(i)->stats.reset();
2981 }
2982 }
2983 #endif // TASKQUEUE_STATS
2984
2985 void G1CollectedHeap::wait_for_root_region_scanning() {
2986 double scan_wait_start = os::elapsedTime();
2987 // We have to wait until the CM threads finish scanning the
2988 // root regions as it's the only way to ensure that all the
2989 // objects on them have been correctly scanned before we start
2990 // moving them during the GC.
2991 bool waited = _cm->root_regions()->wait_until_scan_finished();
2992 double wait_time_ms = 0.0;
2993 if (waited) {
2994 double scan_wait_end = os::elapsedTime();
2995 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2996 }
2997 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2998 }
2999
3000 class G1PrintCollectionSetClosure : public HeapRegionClosure {
3001 private:
3002 G1HRPrinter* _hr_printer;
3003 public:
3004 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
3005
3006 virtual bool doHeapRegion(HeapRegion* r) {
3007 _hr_printer->cset(r);
3008 return false;
3009 }
3010 };
3011
3012 bool
3013 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3014 assert_at_safepoint(true /* should_be_vm_thread */);
3015 guarantee(!is_gc_active(), "collection is not reentrant");
3016
3017 if (GCLocker::check_active_before_gc()) {
3018 return false;
3019 }
3020
3021 _gc_timer_stw->register_gc_start();
3022
3023 GCIdMark gc_id_mark;
3024 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3025
3026 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3027 ResourceMark rm;
3028
3029 g1_policy()->note_gc_start();
3030
3031 wait_for_root_region_scanning();
3032
3033 print_heap_before_gc();
3034 print_heap_regions();
3035 trace_heap_before_gc(_gc_tracer_stw);
3036
3037 _verifier->verify_region_sets_optional();
3038 _verifier->verify_dirty_young_regions();
3039
3040 // We should not be doing initial mark unless the conc mark thread is running
3041 if (!_cmThread->should_terminate()) {
3042 // This call will decide whether this pause is an initial-mark
3043 // pause. If it is, during_initial_mark_pause() will return true
3044 // for the duration of this pause.
3045 g1_policy()->decide_on_conc_mark_initiation();
3046 }
3047
3048 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3049 assert(!collector_state()->during_initial_mark_pause() ||
3050 collector_state()->gcs_are_young(), "sanity");
3051
3052 // We also do not allow mixed GCs during marking.
3053 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3054
3055 // Record whether this pause is an initial mark. When the current
3056 // thread has completed its logging output and it's safe to signal
3057 // the CM thread, the flag's value in the policy has been reset.
3058 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3059
3060 // Inner scope for scope based logging, timers, and stats collection
3061 {
3062 EvacuationInfo evacuation_info;
3063
3064 if (collector_state()->during_initial_mark_pause()) {
3065 // We are about to start a marking cycle, so we increment the
3066 // full collection counter.
3067 increment_old_marking_cycles_started();
3068 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3069 }
3070
3071 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3072
3073 GCTraceCPUTime tcpu;
3074
3075 FormatBuffer<> gc_string("Pause ");
3076 if (collector_state()->during_initial_mark_pause()) {
3077 gc_string.append("Initial Mark");
3078 } else if (collector_state()->gcs_are_young()) {
3079 gc_string.append("Young");
3080 } else {
3081 gc_string.append("Mixed");
3082 }
3083 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3084
3085 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3086 workers()->active_workers(),
3087 Threads::number_of_non_daemon_threads());
3088 workers()->update_active_workers(active_workers);
3089 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3090
3091 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3092 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3093
3094 // If the secondary_free_list is not empty, append it to the
3095 // free_list. No need to wait for the cleanup operation to finish;
3096 // the region allocation code will check the secondary_free_list
3097 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3098 // set, skip this step so that the region allocation code has to
3099 // get entries from the secondary_free_list.
3100 if (!G1StressConcRegionFreeing) {
3101 append_secondary_free_list_if_not_empty_with_lock();
3102 }
3103
3104 G1HeapTransition heap_transition(this);
3105 size_t heap_used_bytes_before_gc = used();
3106
3107 // Don't dynamically change the number of GC threads this early. A value of
3108 // 0 is used to indicate serial work. When parallel work is done,
3109 // it will be set.
3110
3111 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3112 IsGCActiveMark x;
3113
3114 gc_prologue(false);
3115 increment_total_collections(false /* full gc */);
3116 increment_gc_time_stamp();
3117
3118 if (VerifyRememberedSets) {
3119 log_info(gc, verify)("[Verifying RemSets before GC]");
3120 VerifyRegionRemSetClosure v_cl;
3121 heap_region_iterate(&v_cl);
3122 }
3123
3124 _verifier->verify_before_gc();
3125
3126 _verifier->check_bitmaps("GC Start");
3127
3128 #if defined(COMPILER2) || INCLUDE_JVMCI
3129 DerivedPointerTable::clear();
3130 #endif
3131
3132 // Please see comment in g1CollectedHeap.hpp and
3133 // G1CollectedHeap::ref_processing_init() to see how
3134 // reference processing currently works in G1.
3135
3136 // Enable discovery in the STW reference processor
3137 if (g1_policy()->should_process_references()) {
3138 ref_processor_stw()->enable_discovery();
3139 } else {
3140 ref_processor_stw()->disable_discovery();
3141 }
3142
3143 {
3144 // We want to temporarily turn off discovery by the
3145 // CM ref processor, if necessary, and turn it back on
3146 // on again later if we do. Using a scoped
3147 // NoRefDiscovery object will do this.
3148 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3149
3150 // Forget the current alloc region (we might even choose it to be part
3151 // of the collection set!).
3152 _allocator->release_mutator_alloc_region();
3153
3154 // This timing is only used by the ergonomics to handle our pause target.
3155 // It is unclear why this should not include the full pause. We will
3156 // investigate this in CR 7178365.
3157 //
3158 // Preserving the old comment here if that helps the investigation:
3159 //
3160 // The elapsed time induced by the start time below deliberately elides
3161 // the possible verification above.
3162 double sample_start_time_sec = os::elapsedTime();
3163
3164 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3165
3166 if (collector_state()->during_initial_mark_pause()) {
3167 concurrent_mark()->checkpointRootsInitialPre();
3168 }
3169
3170 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3171
3172 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3173
3174 // Make sure the remembered sets are up to date. This needs to be
3175 // done before register_humongous_regions_with_cset(), because the
3176 // remembered sets are used there to choose eager reclaim candidates.
3177 // If the remembered sets are not up to date we might miss some
3178 // entries that need to be handled.
3179 g1_rem_set()->cleanupHRRS();
3180
3181 register_humongous_regions_with_cset();
3182
3183 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3184
3185 // We call this after finalize_cset() to
3186 // ensure that the CSet has been finalized.
3187 _cm->verify_no_cset_oops();
3188
3189 if (_hr_printer.is_active()) {
3190 G1PrintCollectionSetClosure cl(&_hr_printer);
3191 _collection_set.iterate(&cl);
3192 }
3193
3194 // Initialize the GC alloc regions.
3195 _allocator->init_gc_alloc_regions(evacuation_info);
3196
3197 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3198 pre_evacuate_collection_set();
3199
3200 // Actually do the work...
3201 evacuate_collection_set(evacuation_info, &per_thread_states);
3202
3203 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3204
3205 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3206 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3207
3208 eagerly_reclaim_humongous_regions();
3209
3210 record_obj_copy_mem_stats();
3211 _survivor_evac_stats.adjust_desired_plab_sz();
3212 _old_evac_stats.adjust_desired_plab_sz();
3213
3214 // Start a new incremental collection set for the next pause.
3215 collection_set()->start_incremental_building();
3216
3217 clear_cset_fast_test();
3218
3219 guarantee(_eden.length() == 0, "eden should have been cleared");
3220 g1_policy()->transfer_survivors_to_cset(survivor());
3221
3222 if (evacuation_failed()) {
3223 set_used(recalculate_used());
3224 if (_archive_allocator != NULL) {
3225 _archive_allocator->clear_used();
3226 }
3227 for (uint i = 0; i < ParallelGCThreads; i++) {
3228 if (_evacuation_failed_info_array[i].has_failed()) {
3229 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3230 }
3231 }
3232 } else {
3233 // The "used" of the the collection set have already been subtracted
3234 // when they were freed. Add in the bytes evacuated.
3235 increase_used(g1_policy()->bytes_copied_during_gc());
3236 }
3237
3238 if (collector_state()->during_initial_mark_pause()) {
3239 // We have to do this before we notify the CM threads that
3240 // they can start working to make sure that all the
3241 // appropriate initialization is done on the CM object.
3242 concurrent_mark()->checkpointRootsInitialPost();
3243 collector_state()->set_mark_in_progress(true);
3244 // Note that we don't actually trigger the CM thread at
3245 // this point. We do that later when we're sure that
3246 // the current thread has completed its logging output.
3247 }
3248
3249 allocate_dummy_regions();
3250
3251 _allocator->init_mutator_alloc_region();
3252
3253 {
3254 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3255 if (expand_bytes > 0) {
3256 size_t bytes_before = capacity();
3257 // No need for an ergo logging here,
3258 // expansion_amount() does this when it returns a value > 0.
3259 double expand_ms;
3260 if (!expand(expand_bytes, _workers, &expand_ms)) {
3261 // We failed to expand the heap. Cannot do anything about it.
3262 }
3263 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3264 }
3265 }
3266
3267 // We redo the verification but now wrt to the new CSet which
3268 // has just got initialized after the previous CSet was freed.
3269 _cm->verify_no_cset_oops();
3270
3271 // This timing is only used by the ergonomics to handle our pause target.
3272 // It is unclear why this should not include the full pause. We will
3273 // investigate this in CR 7178365.
3274 double sample_end_time_sec = os::elapsedTime();
3275 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3276 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3277 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3278
3279 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3280 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3281
3282 MemoryService::track_memory_usage();
3283
3284 // In prepare_for_verify() below we'll need to scan the deferred
3285 // update buffers to bring the RSets up-to-date if
3286 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3287 // the update buffers we'll probably need to scan cards on the
3288 // regions we just allocated to (i.e., the GC alloc
3289 // regions). However, during the last GC we called
3290 // set_saved_mark() on all the GC alloc regions, so card
3291 // scanning might skip the [saved_mark_word()...top()] area of
3292 // those regions (i.e., the area we allocated objects into
3293 // during the last GC). But it shouldn't. Given that
3294 // saved_mark_word() is conditional on whether the GC time stamp
3295 // on the region is current or not, by incrementing the GC time
3296 // stamp here we invalidate all the GC time stamps on all the
3297 // regions and saved_mark_word() will simply return top() for
3298 // all the regions. This is a nicer way of ensuring this rather
3299 // than iterating over the regions and fixing them. In fact, the
3300 // GC time stamp increment here also ensures that
3301 // saved_mark_word() will return top() between pauses, i.e.,
3302 // during concurrent refinement. So we don't need the
3303 // is_gc_active() check to decided which top to use when
3304 // scanning cards (see CR 7039627).
3305 increment_gc_time_stamp();
3306
3307 if (VerifyRememberedSets) {
3308 log_info(gc, verify)("[Verifying RemSets after GC]");
3309 VerifyRegionRemSetClosure v_cl;
3310 heap_region_iterate(&v_cl);
3311 }
3312
3313 _verifier->verify_after_gc();
3314 _verifier->check_bitmaps("GC End");
3315
3316 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3317 ref_processor_stw()->verify_no_references_recorded();
3318
3319 // CM reference discovery will be re-enabled if necessary.
3320 }
3321
3322 #ifdef TRACESPINNING
3323 ParallelTaskTerminator::print_termination_counts();
3324 #endif
3325
3326 gc_epilogue(false);
3327 }
3328
3329 // Print the remainder of the GC log output.
3330 if (evacuation_failed()) {
3331 log_info(gc)("To-space exhausted");
3332 }
3333
3334 g1_policy()->print_phases();
3335 heap_transition.print();
3336
3337 // It is not yet to safe to tell the concurrent mark to
3338 // start as we have some optional output below. We don't want the
3339 // output from the concurrent mark thread interfering with this
3340 // logging output either.
3341
3342 _hrm.verify_optional();
3343 _verifier->verify_region_sets_optional();
3344
3345 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3346 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3347
3348 print_heap_after_gc();
3349 print_heap_regions();
3350 trace_heap_after_gc(_gc_tracer_stw);
3351
3352 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3353 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3354 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3355 // before any GC notifications are raised.
3356 g1mm()->update_sizes();
3357
3358 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3359 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3360 _gc_timer_stw->register_gc_end();
3361 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3362 }
3363 // It should now be safe to tell the concurrent mark thread to start
3364 // without its logging output interfering with the logging output
3365 // that came from the pause.
3366
3367 if (should_start_conc_mark) {
3368 // CAUTION: after the doConcurrentMark() call below,
3369 // the concurrent marking thread(s) could be running
3370 // concurrently with us. Make sure that anything after
3371 // this point does not assume that we are the only GC thread
3372 // running. Note: of course, the actual marking work will
3373 // not start until the safepoint itself is released in
3374 // SuspendibleThreadSet::desynchronize().
3375 doConcurrentMark();
3376 }
3377
3378 return true;
3379 }
3380
3381 void G1CollectedHeap::remove_self_forwarding_pointers() {
3382 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3383 workers()->run_task(&rsfp_task);
3384 }
3385
3386 void G1CollectedHeap::restore_after_evac_failure() {
3387 double remove_self_forwards_start = os::elapsedTime();
3388
3389 remove_self_forwarding_pointers();
3390 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3391 _preserved_marks_set.restore(&task_executor);
3392
3393 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3394 }
3395
3396 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3397 if (!_evacuation_failed) {
3398 _evacuation_failed = true;
3399 }
3400
3401 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3402 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3403 }
3404
3405 bool G1ParEvacuateFollowersClosure::offer_termination() {
3406 G1ParScanThreadState* const pss = par_scan_state();
3407 start_term_time();
3408 const bool res = terminator()->offer_termination();
3409 end_term_time();
3410 return res;
3411 }
3412
3413 void G1ParEvacuateFollowersClosure::do_void() {
3414 G1ParScanThreadState* const pss = par_scan_state();
3415 pss->trim_queue();
3416 do {
3417 pss->steal_and_trim_queue(queues());
3418 } while (!offer_termination());
3419 }
3420
3421 class G1ParTask : public AbstractGangTask {
3422 protected:
3423 G1CollectedHeap* _g1h;
3424 G1ParScanThreadStateSet* _pss;
3425 RefToScanQueueSet* _queues;
3426 G1RootProcessor* _root_processor;
3427 ParallelTaskTerminator _terminator;
3428 uint _n_workers;
3429
3430 public:
3431 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3432 : AbstractGangTask("G1 collection"),
3433 _g1h(g1h),
3434 _pss(per_thread_states),
3435 _queues(task_queues),
3436 _root_processor(root_processor),
3437 _terminator(n_workers, _queues),
3438 _n_workers(n_workers)
3439 {}
3440
3441 void work(uint worker_id) {
3442 if (worker_id >= _n_workers) return; // no work needed this round
3443
3444 double start_sec = os::elapsedTime();
3445 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3446
3447 {
3448 ResourceMark rm;
3449 HandleMark hm;
3450
3451 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3452
3453 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3454 pss->set_ref_processor(rp);
3455
3456 double start_strong_roots_sec = os::elapsedTime();
3457
3458 _root_processor->evacuate_roots(pss->closures(), worker_id);
3459
3460 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3461
3462 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3463 // treating the nmethods visited to act as roots for concurrent marking.
3464 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3465 // objects copied by the current evacuation.
3466 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3467 pss->closures()->weak_codeblobs(),
3468 worker_id);
3469
3470 _pss->add_cards_scanned(worker_id, cards_scanned);
3471
3472 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3473
3474 double term_sec = 0.0;
3475 size_t evac_term_attempts = 0;
3476 {
3477 double start = os::elapsedTime();
3478 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3479 evac.do_void();
3480
3481 evac_term_attempts = evac.term_attempts();
3482 term_sec = evac.term_time();
3483 double elapsed_sec = os::elapsedTime() - start;
3484 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3485 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3486 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3487 }
3488
3489 assert(pss->queue_is_empty(), "should be empty");
3490
3491 if (log_is_enabled(Debug, gc, task, stats)) {
3492 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3493 size_t lab_waste;
3494 size_t lab_undo_waste;
3495 pss->waste(lab_waste, lab_undo_waste);
3496 _g1h->print_termination_stats(worker_id,
3497 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3498 strong_roots_sec * 1000.0, /* strong roots time */
3499 term_sec * 1000.0, /* evac term time */
3500 evac_term_attempts, /* evac term attempts */
3501 lab_waste, /* alloc buffer waste */
3502 lab_undo_waste /* undo waste */
3503 );
3504 }
3505
3506 // Close the inner scope so that the ResourceMark and HandleMark
3507 // destructors are executed here and are included as part of the
3508 // "GC Worker Time".
3509 }
3510 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3511 }
3512 };
3513
3514 void G1CollectedHeap::print_termination_stats_hdr() {
3515 log_debug(gc, task, stats)("GC Termination Stats");
3516 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3517 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3518 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3519 }
3520
3521 void G1CollectedHeap::print_termination_stats(uint worker_id,
3522 double elapsed_ms,
3523 double strong_roots_ms,
3524 double term_ms,
3525 size_t term_attempts,
3526 size_t alloc_buffer_waste,
3527 size_t undo_waste) const {
3528 log_debug(gc, task, stats)
3529 ("%3d %9.2f %9.2f %6.2f "
3530 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3531 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3532 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3533 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3534 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3535 alloc_buffer_waste * HeapWordSize / K,
3536 undo_waste * HeapWordSize / K);
3537 }
3538
3539 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3540 private:
3541 BoolObjectClosure* _is_alive;
3542 int _initial_string_table_size;
3543 int _initial_symbol_table_size;
3544
3545 bool _process_strings;
3546 int _strings_processed;
3547 int _strings_removed;
3548
3549 bool _process_symbols;
3550 int _symbols_processed;
3551 int _symbols_removed;
3552
3553 public:
3554 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3555 AbstractGangTask("String/Symbol Unlinking"),
3556 _is_alive(is_alive),
3557 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3558 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3559
3560 _initial_string_table_size = StringTable::the_table()->table_size();
3561 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3562 if (process_strings) {
3563 StringTable::clear_parallel_claimed_index();
3564 }
3565 if (process_symbols) {
3566 SymbolTable::clear_parallel_claimed_index();
3567 }
3568 }
3569
3570 ~G1StringSymbolTableUnlinkTask() {
3571 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3572 "claim value %d after unlink less than initial string table size %d",
3573 StringTable::parallel_claimed_index(), _initial_string_table_size);
3574 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3575 "claim value %d after unlink less than initial symbol table size %d",
3576 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3577
3578 log_info(gc, stringtable)(
3579 "Cleaned string and symbol table, "
3580 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3581 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3582 strings_processed(), strings_removed(),
3583 symbols_processed(), symbols_removed());
3584 }
3585
3586 void work(uint worker_id) {
3587 int strings_processed = 0;
3588 int strings_removed = 0;
3589 int symbols_processed = 0;
3590 int symbols_removed = 0;
3591 if (_process_strings) {
3592 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3593 Atomic::add(strings_processed, &_strings_processed);
3594 Atomic::add(strings_removed, &_strings_removed);
3595 }
3596 if (_process_symbols) {
3597 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3598 Atomic::add(symbols_processed, &_symbols_processed);
3599 Atomic::add(symbols_removed, &_symbols_removed);
3600 }
3601 }
3602
3603 size_t strings_processed() const { return (size_t)_strings_processed; }
3604 size_t strings_removed() const { return (size_t)_strings_removed; }
3605
3606 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3607 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3608 };
3609
3610 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3611 private:
3612 static Monitor* _lock;
3613
3614 BoolObjectClosure* const _is_alive;
3615 const bool _unloading_occurred;
3616 const uint _num_workers;
3617
3618 // Variables used to claim nmethods.
3619 CompiledMethod* _first_nmethod;
3620 volatile CompiledMethod* _claimed_nmethod;
3621
3622 // The list of nmethods that need to be processed by the second pass.
3623 volatile CompiledMethod* _postponed_list;
3624 volatile uint _num_entered_barrier;
3625
3626 public:
3627 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3628 _is_alive(is_alive),
3629 _unloading_occurred(unloading_occurred),
3630 _num_workers(num_workers),
3631 _first_nmethod(NULL),
3632 _claimed_nmethod(NULL),
3633 _postponed_list(NULL),
3634 _num_entered_barrier(0)
3635 {
3636 CompiledMethod::increase_unloading_clock();
3637 // Get first alive nmethod
3638 CompiledMethodIterator iter = CompiledMethodIterator();
3639 if(iter.next_alive()) {
3640 _first_nmethod = iter.method();
3641 }
3642 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3643 }
3644
3645 ~G1CodeCacheUnloadingTask() {
3646 CodeCache::verify_clean_inline_caches();
3647
3648 CodeCache::set_needs_cache_clean(false);
3649 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3650
3651 CodeCache::verify_icholder_relocations();
3652 }
3653
3654 private:
3655 void add_to_postponed_list(CompiledMethod* nm) {
3656 CompiledMethod* old;
3657 do {
3658 old = (CompiledMethod*)_postponed_list;
3659 nm->set_unloading_next(old);
3660 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3661 }
3662
3663 void clean_nmethod(CompiledMethod* nm) {
3664 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3665
3666 if (postponed) {
3667 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3668 add_to_postponed_list(nm);
3669 }
3670
3671 // Mark that this thread has been cleaned/unloaded.
3672 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3673 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3674 }
3675
3676 void clean_nmethod_postponed(CompiledMethod* nm) {
3677 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3678 }
3679
3680 static const int MaxClaimNmethods = 16;
3681
3682 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3683 CompiledMethod* first;
3684 CompiledMethodIterator last;
3685
3686 do {
3687 *num_claimed_nmethods = 0;
3688
3689 first = (CompiledMethod*)_claimed_nmethod;
3690 last = CompiledMethodIterator(first);
3691
3692 if (first != NULL) {
3693
3694 for (int i = 0; i < MaxClaimNmethods; i++) {
3695 if (!last.next_alive()) {
3696 break;
3697 }
3698 claimed_nmethods[i] = last.method();
3699 (*num_claimed_nmethods)++;
3700 }
3701 }
3702
3703 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3704 }
3705
3706 CompiledMethod* claim_postponed_nmethod() {
3707 CompiledMethod* claim;
3708 CompiledMethod* next;
3709
3710 do {
3711 claim = (CompiledMethod*)_postponed_list;
3712 if (claim == NULL) {
3713 return NULL;
3714 }
3715
3716 next = claim->unloading_next();
3717
3718 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3719
3720 return claim;
3721 }
3722
3723 public:
3724 // Mark that we're done with the first pass of nmethod cleaning.
3725 void barrier_mark(uint worker_id) {
3726 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3727 _num_entered_barrier++;
3728 if (_num_entered_barrier == _num_workers) {
3729 ml.notify_all();
3730 }
3731 }
3732
3733 // See if we have to wait for the other workers to
3734 // finish their first-pass nmethod cleaning work.
3735 void barrier_wait(uint worker_id) {
3736 if (_num_entered_barrier < _num_workers) {
3737 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3738 while (_num_entered_barrier < _num_workers) {
3739 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3740 }
3741 }
3742 }
3743
3744 // Cleaning and unloading of nmethods. Some work has to be postponed
3745 // to the second pass, when we know which nmethods survive.
3746 void work_first_pass(uint worker_id) {
3747 // The first nmethods is claimed by the first worker.
3748 if (worker_id == 0 && _first_nmethod != NULL) {
3749 clean_nmethod(_first_nmethod);
3750 _first_nmethod = NULL;
3751 }
3752
3753 int num_claimed_nmethods;
3754 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3755
3756 while (true) {
3757 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3758
3759 if (num_claimed_nmethods == 0) {
3760 break;
3761 }
3762
3763 for (int i = 0; i < num_claimed_nmethods; i++) {
3764 clean_nmethod(claimed_nmethods[i]);
3765 }
3766 }
3767 }
3768
3769 void work_second_pass(uint worker_id) {
3770 CompiledMethod* nm;
3771 // Take care of postponed nmethods.
3772 while ((nm = claim_postponed_nmethod()) != NULL) {
3773 clean_nmethod_postponed(nm);
3774 }
3775 }
3776 };
3777
3778 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3779
3780 class G1KlassCleaningTask : public StackObj {
3781 BoolObjectClosure* _is_alive;
3782 volatile jint _clean_klass_tree_claimed;
3783 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3784
3785 public:
3786 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3787 _is_alive(is_alive),
3788 _clean_klass_tree_claimed(0),
3789 _klass_iterator() {
3790 }
3791
3792 private:
3793 bool claim_clean_klass_tree_task() {
3794 if (_clean_klass_tree_claimed) {
3795 return false;
3796 }
3797
3798 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3799 }
3800
3801 InstanceKlass* claim_next_klass() {
3802 Klass* klass;
3803 do {
3804 klass =_klass_iterator.next_klass();
3805 } while (klass != NULL && !klass->is_instance_klass());
3806
3807 // this can be null so don't call InstanceKlass::cast
3808 return static_cast<InstanceKlass*>(klass);
3809 }
3810
3811 public:
3812
3813 void clean_klass(InstanceKlass* ik) {
3814 ik->clean_weak_instanceklass_links(_is_alive);
3815 }
3816
3817 void work() {
3818 ResourceMark rm;
3819
3820 // One worker will clean the subklass/sibling klass tree.
3821 if (claim_clean_klass_tree_task()) {
3822 Klass::clean_subklass_tree(_is_alive);
3823 }
3824
3825 // All workers will help cleaning the classes,
3826 InstanceKlass* klass;
3827 while ((klass = claim_next_klass()) != NULL) {
3828 clean_klass(klass);
3829 }
3830 }
3831 };
3832
3833 // To minimize the remark pause times, the tasks below are done in parallel.
3834 class G1ParallelCleaningTask : public AbstractGangTask {
3835 private:
3836 G1StringSymbolTableUnlinkTask _string_symbol_task;
3837 G1CodeCacheUnloadingTask _code_cache_task;
3838 G1KlassCleaningTask _klass_cleaning_task;
3839
3840 public:
3841 // The constructor is run in the VMThread.
3842 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
3843 AbstractGangTask("Parallel Cleaning"),
3844 _string_symbol_task(is_alive, process_strings, process_symbols),
3845 _code_cache_task(num_workers, is_alive, unloading_occurred),
3846 _klass_cleaning_task(is_alive) {
3847 }
3848
3849 // The parallel work done by all worker threads.
3850 void work(uint worker_id) {
3851 // Do first pass of code cache cleaning.
3852 _code_cache_task.work_first_pass(worker_id);
3853
3854 // Let the threads mark that the first pass is done.
3855 _code_cache_task.barrier_mark(worker_id);
3856
3857 // Clean the Strings and Symbols.
3858 _string_symbol_task.work(worker_id);
3859
3860 // Wait for all workers to finish the first code cache cleaning pass.
3861 _code_cache_task.barrier_wait(worker_id);
3862
3863 // Do the second code cache cleaning work, which realize on
3864 // the liveness information gathered during the first pass.
3865 _code_cache_task.work_second_pass(worker_id);
3866
3867 // Clean all klasses that were not unloaded.
3868 _klass_cleaning_task.work();
3869 }
3870 };
3871
3872
3873 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
3874 bool process_strings,
3875 bool process_symbols,
3876 bool class_unloading_occurred) {
3877 uint n_workers = workers()->active_workers();
3878
3879 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
3880 n_workers, class_unloading_occurred);
3881 workers()->run_task(&g1_unlink_task);
3882 }
3883
3884 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
3885 bool process_strings, bool process_symbols) {
3886 { // Timing scope
3887 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
3888 workers()->run_task(&g1_unlink_task);
3889 }
3890 }
3891
3892 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3893 private:
3894 DirtyCardQueueSet* _queue;
3895 G1CollectedHeap* _g1h;
3896 public:
3897 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3898 _queue(queue), _g1h(g1h) { }
3899
3900 virtual void work(uint worker_id) {
3901 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3902 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3903
3904 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3905 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3906
3907 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3908 }
3909 };
3910
3911 void G1CollectedHeap::redirty_logged_cards() {
3912 double redirty_logged_cards_start = os::elapsedTime();
3913
3914 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3915 dirty_card_queue_set().reset_for_par_iteration();
3916 workers()->run_task(&redirty_task);
3917
3918 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3919 dcq.merge_bufferlists(&dirty_card_queue_set());
3920 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3921
3922 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3923 }
3924
3925 // Weak Reference Processing support
3926
3927 // An always "is_alive" closure that is used to preserve referents.
3928 // If the object is non-null then it's alive. Used in the preservation
3929 // of referent objects that are pointed to by reference objects
3930 // discovered by the CM ref processor.
3931 class G1AlwaysAliveClosure: public BoolObjectClosure {
3932 G1CollectedHeap* _g1;
3933 public:
3934 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3935 bool do_object_b(oop p) {
3936 if (p != NULL) {
3937 return true;
3938 }
3939 return false;
3940 }
3941 };
3942
3943 bool G1STWIsAliveClosure::do_object_b(oop p) {
3944 // An object is reachable if it is outside the collection set,
3945 // or is inside and copied.
3946 return !_g1->is_in_cset(p) || p->is_forwarded();
3947 }
3948
3949 // Non Copying Keep Alive closure
3950 class G1KeepAliveClosure: public OopClosure {
3951 G1CollectedHeap* _g1;
3952 public:
3953 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3954 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3955 void do_oop(oop* p) {
3956 oop obj = *p;
3957 assert(obj != NULL, "the caller should have filtered out NULL values");
3958
3959 const InCSetState cset_state = _g1->in_cset_state(obj);
3960 if (!cset_state.is_in_cset_or_humongous()) {
3961 return;
3962 }
3963 if (cset_state.is_in_cset()) {
3964 assert( obj->is_forwarded(), "invariant" );
3965 *p = obj->forwardee();
3966 } else {
3967 assert(!obj->is_forwarded(), "invariant" );
3968 assert(cset_state.is_humongous(),
3969 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3970 _g1->set_humongous_is_live(obj);
3971 }
3972 }
3973 };
3974
3975 // Copying Keep Alive closure - can be called from both
3976 // serial and parallel code as long as different worker
3977 // threads utilize different G1ParScanThreadState instances
3978 // and different queues.
3979
3980 class G1CopyingKeepAliveClosure: public OopClosure {
3981 G1CollectedHeap* _g1h;
3982 OopClosure* _copy_non_heap_obj_cl;
3983 G1ParScanThreadState* _par_scan_state;
3984
3985 public:
3986 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3987 OopClosure* non_heap_obj_cl,
3988 G1ParScanThreadState* pss):
3989 _g1h(g1h),
3990 _copy_non_heap_obj_cl(non_heap_obj_cl),
3991 _par_scan_state(pss)
3992 {}
3993
3994 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3995 virtual void do_oop( oop* p) { do_oop_work(p); }
3996
3997 template <class T> void do_oop_work(T* p) {
3998 oop obj = oopDesc::load_decode_heap_oop(p);
3999
4000 if (_g1h->is_in_cset_or_humongous(obj)) {
4001 // If the referent object has been forwarded (either copied
4002 // to a new location or to itself in the event of an
4003 // evacuation failure) then we need to update the reference
4004 // field and, if both reference and referent are in the G1
4005 // heap, update the RSet for the referent.
4006 //
4007 // If the referent has not been forwarded then we have to keep
4008 // it alive by policy. Therefore we have copy the referent.
4009 //
4010 // If the reference field is in the G1 heap then we can push
4011 // on the PSS queue. When the queue is drained (after each
4012 // phase of reference processing) the object and it's followers
4013 // will be copied, the reference field set to point to the
4014 // new location, and the RSet updated. Otherwise we need to
4015 // use the the non-heap or metadata closures directly to copy
4016 // the referent object and update the pointer, while avoiding
4017 // updating the RSet.
4018
4019 if (_g1h->is_in_g1_reserved(p)) {
4020 _par_scan_state->push_on_queue(p);
4021 } else {
4022 assert(!Metaspace::contains((const void*)p),
4023 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4024 _copy_non_heap_obj_cl->do_oop(p);
4025 }
4026 }
4027 }
4028 };
4029
4030 // Serial drain queue closure. Called as the 'complete_gc'
4031 // closure for each discovered list in some of the
4032 // reference processing phases.
4033
4034 class G1STWDrainQueueClosure: public VoidClosure {
4035 protected:
4036 G1CollectedHeap* _g1h;
4037 G1ParScanThreadState* _par_scan_state;
4038
4039 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4040
4041 public:
4042 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4043 _g1h(g1h),
4044 _par_scan_state(pss)
4045 { }
4046
4047 void do_void() {
4048 G1ParScanThreadState* const pss = par_scan_state();
4049 pss->trim_queue();
4050 }
4051 };
4052
4053 // Parallel Reference Processing closures
4054
4055 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4056 // processing during G1 evacuation pauses.
4057
4058 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4059 private:
4060 G1CollectedHeap* _g1h;
4061 G1ParScanThreadStateSet* _pss;
4062 RefToScanQueueSet* _queues;
4063 WorkGang* _workers;
4064 uint _active_workers;
4065
4066 public:
4067 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4068 G1ParScanThreadStateSet* per_thread_states,
4069 WorkGang* workers,
4070 RefToScanQueueSet *task_queues,
4071 uint n_workers) :
4072 _g1h(g1h),
4073 _pss(per_thread_states),
4074 _queues(task_queues),
4075 _workers(workers),
4076 _active_workers(n_workers)
4077 {
4078 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4079 }
4080
4081 // Executes the given task using concurrent marking worker threads.
4082 virtual void execute(ProcessTask& task);
4083 virtual void execute(EnqueueTask& task);
4084 };
4085
4086 // Gang task for possibly parallel reference processing
4087
4088 class G1STWRefProcTaskProxy: public AbstractGangTask {
4089 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4090 ProcessTask& _proc_task;
4091 G1CollectedHeap* _g1h;
4092 G1ParScanThreadStateSet* _pss;
4093 RefToScanQueueSet* _task_queues;
4094 ParallelTaskTerminator* _terminator;
4095
4096 public:
4097 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4098 G1CollectedHeap* g1h,
4099 G1ParScanThreadStateSet* per_thread_states,
4100 RefToScanQueueSet *task_queues,
4101 ParallelTaskTerminator* terminator) :
4102 AbstractGangTask("Process reference objects in parallel"),
4103 _proc_task(proc_task),
4104 _g1h(g1h),
4105 _pss(per_thread_states),
4106 _task_queues(task_queues),
4107 _terminator(terminator)
4108 {}
4109
4110 virtual void work(uint worker_id) {
4111 // The reference processing task executed by a single worker.
4112 ResourceMark rm;
4113 HandleMark hm;
4114
4115 G1STWIsAliveClosure is_alive(_g1h);
4116
4117 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4118 pss->set_ref_processor(NULL);
4119
4120 // Keep alive closure.
4121 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4122
4123 // Complete GC closure
4124 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4125
4126 // Call the reference processing task's work routine.
4127 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4128
4129 // Note we cannot assert that the refs array is empty here as not all
4130 // of the processing tasks (specifically phase2 - pp2_work) execute
4131 // the complete_gc closure (which ordinarily would drain the queue) so
4132 // the queue may not be empty.
4133 }
4134 };
4135
4136 // Driver routine for parallel reference processing.
4137 // Creates an instance of the ref processing gang
4138 // task and has the worker threads execute it.
4139 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4140 assert(_workers != NULL, "Need parallel worker threads.");
4141
4142 ParallelTaskTerminator terminator(_active_workers, _queues);
4143 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4144
4145 _workers->run_task(&proc_task_proxy);
4146 }
4147
4148 // Gang task for parallel reference enqueueing.
4149
4150 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4151 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4152 EnqueueTask& _enq_task;
4153
4154 public:
4155 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4156 AbstractGangTask("Enqueue reference objects in parallel"),
4157 _enq_task(enq_task)
4158 { }
4159
4160 virtual void work(uint worker_id) {
4161 _enq_task.work(worker_id);
4162 }
4163 };
4164
4165 // Driver routine for parallel reference enqueueing.
4166 // Creates an instance of the ref enqueueing gang
4167 // task and has the worker threads execute it.
4168
4169 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4170 assert(_workers != NULL, "Need parallel worker threads.");
4171
4172 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4173
4174 _workers->run_task(&enq_task_proxy);
4175 }
4176
4177 // End of weak reference support closures
4178
4179 // Abstract task used to preserve (i.e. copy) any referent objects
4180 // that are in the collection set and are pointed to by reference
4181 // objects discovered by the CM ref processor.
4182
4183 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4184 protected:
4185 G1CollectedHeap* _g1h;
4186 G1ParScanThreadStateSet* _pss;
4187 RefToScanQueueSet* _queues;
4188 ParallelTaskTerminator _terminator;
4189 uint _n_workers;
4190
4191 public:
4192 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4193 AbstractGangTask("ParPreserveCMReferents"),
4194 _g1h(g1h),
4195 _pss(per_thread_states),
4196 _queues(task_queues),
4197 _terminator(workers, _queues),
4198 _n_workers(workers)
4199 {
4200 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4201 }
4202
4203 void work(uint worker_id) {
4204 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4205
4206 ResourceMark rm;
4207 HandleMark hm;
4208
4209 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4210 pss->set_ref_processor(NULL);
4211 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4212
4213 // Is alive closure
4214 G1AlwaysAliveClosure always_alive(_g1h);
4215
4216 // Copying keep alive closure. Applied to referent objects that need
4217 // to be copied.
4218 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4219
4220 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4221
4222 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4223 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4224
4225 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4226 // So this must be true - but assert just in case someone decides to
4227 // change the worker ids.
4228 assert(worker_id < limit, "sanity");
4229 assert(!rp->discovery_is_atomic(), "check this code");
4230
4231 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4232 for (uint idx = worker_id; idx < limit; idx += stride) {
4233 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4234
4235 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4236 while (iter.has_next()) {
4237 // Since discovery is not atomic for the CM ref processor, we
4238 // can see some null referent objects.
4239 iter.load_ptrs(DEBUG_ONLY(true));
4240 oop ref = iter.obj();
4241
4242 // This will filter nulls.
4243 if (iter.is_referent_alive()) {
4244 iter.make_referent_alive();
4245 }
4246 iter.move_to_next();
4247 }
4248 }
4249
4250 // Drain the queue - which may cause stealing
4251 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4252 drain_queue.do_void();
4253 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4254 assert(pss->queue_is_empty(), "should be");
4255 }
4256 };
4257
4258 void G1CollectedHeap::process_weak_jni_handles() {
4259 double ref_proc_start = os::elapsedTime();
4260
4261 G1STWIsAliveClosure is_alive(this);
4262 G1KeepAliveClosure keep_alive(this);
4263 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4264
4265 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4266 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4267 }
4268
4269 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4270 // Any reference objects, in the collection set, that were 'discovered'
4271 // by the CM ref processor should have already been copied (either by
4272 // applying the external root copy closure to the discovered lists, or
4273 // by following an RSet entry).
4274 //
4275 // But some of the referents, that are in the collection set, that these
4276 // reference objects point to may not have been copied: the STW ref
4277 // processor would have seen that the reference object had already
4278 // been 'discovered' and would have skipped discovering the reference,
4279 // but would not have treated the reference object as a regular oop.
4280 // As a result the copy closure would not have been applied to the
4281 // referent object.
4282 //
4283 // We need to explicitly copy these referent objects - the references
4284 // will be processed at the end of remarking.
4285 //
4286 // We also need to do this copying before we process the reference
4287 // objects discovered by the STW ref processor in case one of these
4288 // referents points to another object which is also referenced by an
4289 // object discovered by the STW ref processor.
4290 double preserve_cm_referents_time = 0.0;
4291
4292 // To avoid spawning task when there is no work to do, check that
4293 // a concurrent cycle is active and that some references have been
4294 // discovered.
4295 if (concurrent_mark()->cmThread()->during_cycle() &&
4296 ref_processor_cm()->has_discovered_references()) {
4297 double preserve_cm_referents_start = os::elapsedTime();
4298 uint no_of_gc_workers = workers()->active_workers();
4299 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4300 per_thread_states,
4301 no_of_gc_workers,
4302 _task_queues);
4303 workers()->run_task(&keep_cm_referents);
4304 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4305 }
4306
4307 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4308 }
4309
4310 // Weak Reference processing during an evacuation pause (part 1).
4311 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4312 double ref_proc_start = os::elapsedTime();
4313
4314 ReferenceProcessor* rp = _ref_processor_stw;
4315 assert(rp->discovery_enabled(), "should have been enabled");
4316
4317 // Closure to test whether a referent is alive.
4318 G1STWIsAliveClosure is_alive(this);
4319
4320 // Even when parallel reference processing is enabled, the processing
4321 // of JNI refs is serial and performed serially by the current thread
4322 // rather than by a worker. The following PSS will be used for processing
4323 // JNI refs.
4324
4325 // Use only a single queue for this PSS.
4326 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4327 pss->set_ref_processor(NULL);
4328 assert(pss->queue_is_empty(), "pre-condition");
4329
4330 // Keep alive closure.
4331 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4332
4333 // Serial Complete GC closure
4334 G1STWDrainQueueClosure drain_queue(this, pss);
4335
4336 // Setup the soft refs policy...
4337 rp->setup_policy(false);
4338
4339 ReferenceProcessorStats stats;
4340 if (!rp->processing_is_mt()) {
4341 // Serial reference processing...
4342 stats = rp->process_discovered_references(&is_alive,
4343 &keep_alive,
4344 &drain_queue,
4345 NULL,
4346 _gc_timer_stw);
4347 } else {
4348 uint no_of_gc_workers = workers()->active_workers();
4349
4350 // Parallel reference processing
4351 assert(no_of_gc_workers <= rp->max_num_q(),
4352 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4353 no_of_gc_workers, rp->max_num_q());
4354
4355 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4356 stats = rp->process_discovered_references(&is_alive,
4357 &keep_alive,
4358 &drain_queue,
4359 &par_task_executor,
4360 _gc_timer_stw);
4361 }
4362
4363 _gc_tracer_stw->report_gc_reference_stats(stats);
4364
4365 // We have completed copying any necessary live referent objects.
4366 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4367
4368 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4369 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4370 }
4371
4372 // Weak Reference processing during an evacuation pause (part 2).
4373 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4374 double ref_enq_start = os::elapsedTime();
4375
4376 ReferenceProcessor* rp = _ref_processor_stw;
4377 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4378
4379 // Now enqueue any remaining on the discovered lists on to
4380 // the pending list.
4381 if (!rp->processing_is_mt()) {
4382 // Serial reference processing...
4383 rp->enqueue_discovered_references();
4384 } else {
4385 // Parallel reference enqueueing
4386
4387 uint n_workers = workers()->active_workers();
4388
4389 assert(n_workers <= rp->max_num_q(),
4390 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4391 n_workers, rp->max_num_q());
4392
4393 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4394 rp->enqueue_discovered_references(&par_task_executor);
4395 }
4396
4397 rp->verify_no_references_recorded();
4398 assert(!rp->discovery_enabled(), "should have been disabled");
4399
4400 // FIXME
4401 // CM's reference processing also cleans up the string and symbol tables.
4402 // Should we do that here also? We could, but it is a serial operation
4403 // and could significantly increase the pause time.
4404
4405 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4406 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4407 }
4408
4409 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4410 double merge_pss_time_start = os::elapsedTime();
4411 per_thread_states->flush();
4412 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4413 }
4414
4415 void G1CollectedHeap::pre_evacuate_collection_set() {
4416 _expand_heap_after_alloc_failure = true;
4417 _evacuation_failed = false;
4418
4419 // Disable the hot card cache.
4420 _hot_card_cache->reset_hot_cache_claimed_index();
4421 _hot_card_cache->set_use_cache(false);
4422
4423 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4424 _preserved_marks_set.assert_empty();
4425 }
4426
4427 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4428 // Should G1EvacuationFailureALot be in effect for this GC?
4429 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4430
4431 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4432
4433 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4434
4435 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4436 if (collector_state()->during_initial_mark_pause()) {
4437 double start_clear_claimed_marks = os::elapsedTime();
4438
4439 ClassLoaderDataGraph::clear_claimed_marks();
4440
4441 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4442 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4443 }
4444
4445 double start_par_time_sec = os::elapsedTime();
4446 double end_par_time_sec;
4447
4448 {
4449 const uint n_workers = workers()->active_workers();
4450 G1RootProcessor root_processor(this, n_workers);
4451 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4452
4453 print_termination_stats_hdr();
4454
4455 workers()->run_task(&g1_par_task);
4456 end_par_time_sec = os::elapsedTime();
4457
4458 // Closing the inner scope will execute the destructor
4459 // for the G1RootProcessor object. We record the current
4460 // elapsed time before closing the scope so that time
4461 // taken for the destructor is NOT included in the
4462 // reported parallel time.
4463 }
4464
4465 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4466 phase_times->record_par_time(par_time_ms);
4467
4468 double code_root_fixup_time_ms =
4469 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4470 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4471 }
4472
4473 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4474 // Process any discovered reference objects - we have
4475 // to do this _before_ we retire the GC alloc regions
4476 // as we may have to copy some 'reachable' referent
4477 // objects (and their reachable sub-graphs) that were
4478 // not copied during the pause.
4479 if (g1_policy()->should_process_references()) {
4480 preserve_cm_referents(per_thread_states);
4481 process_discovered_references(per_thread_states);
4482 } else {
4483 ref_processor_stw()->verify_no_references_recorded();
4484 process_weak_jni_handles();
4485 }
4486
4487 if (G1StringDedup::is_enabled()) {
4488 double fixup_start = os::elapsedTime();
4489
4490 G1STWIsAliveClosure is_alive(this);
4491 G1KeepAliveClosure keep_alive(this);
4492 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4493
4494 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4495 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4496 }
4497
4498 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4499
4500 if (evacuation_failed()) {
4501 restore_after_evac_failure();
4502
4503 // Reset the G1EvacuationFailureALot counters and flags
4504 // Note: the values are reset only when an actual
4505 // evacuation failure occurs.
4506 NOT_PRODUCT(reset_evacuation_should_fail();)
4507 }
4508
4509 _preserved_marks_set.assert_empty();
4510
4511 // Enqueue any remaining references remaining on the STW
4512 // reference processor's discovered lists. We need to do
4513 // this after the card table is cleaned (and verified) as
4514 // the act of enqueueing entries on to the pending list
4515 // will log these updates (and dirty their associated
4516 // cards). We need these updates logged to update any
4517 // RSets.
4518 if (g1_policy()->should_process_references()) {
4519 enqueue_discovered_references(per_thread_states);
4520 } else {
4521 g1_policy()->phase_times()->record_ref_enq_time(0);
4522 }
4523
4524 _allocator->release_gc_alloc_regions(evacuation_info);
4525
4526 merge_per_thread_state_info(per_thread_states);
4527
4528 // Reset and re-enable the hot card cache.
4529 // Note the counts for the cards in the regions in the
4530 // collection set are reset when the collection set is freed.
4531 _hot_card_cache->reset_hot_cache();
4532 _hot_card_cache->set_use_cache(true);
4533
4534 purge_code_root_memory();
4535
4536 redirty_logged_cards();
4537 #if defined(COMPILER2) || INCLUDE_JVMCI
4538 DerivedPointerTable::update_pointers();
4539 #endif
4540 g1_policy()->print_age_table();
4541 }
4542
4543 void G1CollectedHeap::record_obj_copy_mem_stats() {
4544 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4545
4546 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4547 create_g1_evac_summary(&_old_evac_stats));
4548 }
4549
4550 void G1CollectedHeap::free_region(HeapRegion* hr,
4551 FreeRegionList* free_list,
4552 bool skip_remset,
4553 bool skip_hot_card_cache,
4554 bool locked) {
4555 assert(!hr->is_free(), "the region should not be free");
4556 assert(!hr->is_empty(), "the region should not be empty");
4557 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4558 assert(free_list != NULL, "pre-condition");
4559
4560 if (G1VerifyBitmaps) {
4561 MemRegion mr(hr->bottom(), hr->end());
4562 concurrent_mark()->clearRangePrevBitmap(mr);
4563 }
4564
4565 // Clear the card counts for this region.
4566 // Note: we only need to do this if the region is not young
4567 // (since we don't refine cards in young regions).
4568 if (!skip_hot_card_cache && !hr->is_young()) {
4569 _hot_card_cache->reset_card_counts(hr);
4570 }
4571 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4572 free_list->add_ordered(hr);
4573 }
4574
4575 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4576 FreeRegionList* free_list,
4577 bool skip_remset) {
4578 assert(hr->is_humongous(), "this is only for humongous regions");
4579 assert(free_list != NULL, "pre-condition");
4580 hr->clear_humongous();
4581 free_region(hr, free_list, skip_remset);
4582 }
4583
4584 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4585 const uint humongous_regions_removed) {
4586 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4587 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4588 _old_set.bulk_remove(old_regions_removed);
4589 _humongous_set.bulk_remove(humongous_regions_removed);
4590 }
4591
4592 }
4593
4594 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4595 assert(list != NULL, "list can't be null");
4596 if (!list->is_empty()) {
4597 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4598 _hrm.insert_list_into_free_list(list);
4599 }
4600 }
4601
4602 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4603 decrease_used(bytes);
4604 }
4605
4606 class G1ParScrubRemSetTask: public AbstractGangTask {
4607 protected:
4608 G1RemSet* _g1rs;
4609 HeapRegionClaimer _hrclaimer;
4610
4611 public:
4612 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4613 AbstractGangTask("G1 ScrubRS"),
4614 _g1rs(g1_rs),
4615 _hrclaimer(num_workers) {
4616 }
4617
4618 void work(uint worker_id) {
4619 _g1rs->scrub(worker_id, &_hrclaimer);
4620 }
4621 };
4622
4623 void G1CollectedHeap::scrub_rem_set() {
4624 uint num_workers = workers()->active_workers();
4625 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4626 workers()->run_task(&g1_par_scrub_rs_task);
4627 }
4628
4629 class G1FreeCollectionSetTask : public AbstractGangTask {
4630 private:
4631
4632 // Closure applied to all regions in the collection set to do work that needs to
4633 // be done serially in a single thread.
4634 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4635 private:
4636 EvacuationInfo* _evacuation_info;
4637 const size_t* _surviving_young_words;
4638
4639 // Bytes used in successfully evacuated regions before the evacuation.
4640 size_t _before_used_bytes;
4641 // Bytes used in unsucessfully evacuated regions before the evacuation
4642 size_t _after_used_bytes;
4643
4644 size_t _bytes_allocated_in_old_since_last_gc;
4645
4646 size_t _failure_used_words;
4647 size_t _failure_waste_words;
4648
4649 FreeRegionList _local_free_list;
4650 public:
4651 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4652 HeapRegionClosure(),
4653 _evacuation_info(evacuation_info),
4654 _surviving_young_words(surviving_young_words),
4655 _before_used_bytes(0),
4656 _after_used_bytes(0),
4657 _bytes_allocated_in_old_since_last_gc(0),
4658 _failure_used_words(0),
4659 _failure_waste_words(0),
4660 _local_free_list("Local Region List for CSet Freeing") {
4661 }
4662
4663 virtual bool doHeapRegion(HeapRegion* r) {
4664 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4665
4666 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4667 g1h->clear_in_cset(r);
4668
4669 if (r->is_young()) {
4670 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4671 "Young index %d is wrong for region %u of type %s with %u young regions",
4672 r->young_index_in_cset(),
4673 r->hrm_index(),
4674 r->get_type_str(),
4675 g1h->collection_set()->young_region_length());
4676 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4677 r->record_surv_words_in_group(words_survived);
4678 }
4679
4680 if (!r->evacuation_failed()) {
4681 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4682 _before_used_bytes += r->used();
4683 g1h->free_region(r,
4684 &_local_free_list,
4685 true, /* skip_remset */
4686 true, /* skip_hot_card_cache */
4687 true /* locked */);
4688 } else {
4689 r->uninstall_surv_rate_group();
4690 r->set_young_index_in_cset(-1);
4691 r->set_evacuation_failed(false);
4692 // When moving a young gen region to old gen, we "allocate" that whole region
4693 // there. This is in addition to any already evacuated objects. Notify the
4694 // policy about that.
4695 // Old gen regions do not cause an additional allocation: both the objects
4696 // still in the region and the ones already moved are accounted for elsewhere.
4697 if (r->is_young()) {
4698 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4699 }
4700 // The region is now considered to be old.
4701 r->set_old();
4702 // Do some allocation statistics accounting. Regions that failed evacuation
4703 // are always made old, so there is no need to update anything in the young
4704 // gen statistics, but we need to update old gen statistics.
4705 size_t used_words = r->marked_bytes() / HeapWordSize;
4706
4707 _failure_used_words += used_words;
4708 _failure_waste_words += HeapRegion::GrainWords - used_words;
4709
4710 g1h->old_set_add(r);
4711 _after_used_bytes += r->used();
4712 }
4713 return false;
4714 }
4715
4716 void complete_work() {
4717 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4718
4719 _evacuation_info->set_regions_freed(_local_free_list.length());
4720 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4721
4722 g1h->prepend_to_freelist(&_local_free_list);
4723 g1h->decrement_summary_bytes(_before_used_bytes);
4724
4725 G1Policy* policy = g1h->g1_policy();
4726 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4727
4728 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4729 }
4730 };
4731
4732 G1CollectionSet* _collection_set;
4733 G1SerialFreeCollectionSetClosure _cl;
4734 const size_t* _surviving_young_words;
4735
4736 size_t _rs_lengths;
4737
4738 volatile jint _serial_work_claim;
4739
4740 struct WorkItem {
4741 uint region_idx;
4742 bool is_young;
4743 bool evacuation_failed;
4744
4745 WorkItem(HeapRegion* r) {
4746 region_idx = r->hrm_index();
4747 is_young = r->is_young();
4748 evacuation_failed = r->evacuation_failed();
4749 }
4750 };
4751
4752 volatile size_t _parallel_work_claim;
4753 size_t _num_work_items;
4754 WorkItem* _work_items;
4755
4756 void do_serial_work() {
4757 // Need to grab the lock to be allowed to modify the old region list.
4758 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4759 _collection_set->iterate(&_cl);
4760 }
4761
4762 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4763 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4764
4765 HeapRegion* r = g1h->region_at(region_idx);
4766 assert(!g1h->is_on_master_free_list(r), "sanity");
4767
4768 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4769
4770 if (!is_young) {
4771 g1h->_hot_card_cache->reset_card_counts(r);
4772 }
4773
4774 if (!evacuation_failed) {
4775 r->rem_set()->clear_locked();
4776 }
4777 }
4778
4779 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4780 private:
4781 size_t _cur_idx;
4782 WorkItem* _work_items;
4783 public:
4784 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4785
4786 virtual bool doHeapRegion(HeapRegion* r) {
4787 _work_items[_cur_idx++] = WorkItem(r);
4788 return false;
4789 }
4790 };
4791
4792 void prepare_work() {
4793 G1PrepareFreeCollectionSetClosure cl(_work_items);
4794 _collection_set->iterate(&cl);
4795 }
4796
4797 void complete_work() {
4798 _cl.complete_work();
4799
4800 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4801 policy->record_max_rs_lengths(_rs_lengths);
4802 policy->cset_regions_freed();
4803 }
4804 public:
4805 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4806 AbstractGangTask("G1 Free Collection Set"),
4807 _cl(evacuation_info, surviving_young_words),
4808 _collection_set(collection_set),
4809 _surviving_young_words(surviving_young_words),
4810 _serial_work_claim(0),
4811 _rs_lengths(0),
4812 _parallel_work_claim(0),
4813 _num_work_items(collection_set->region_length()),
4814 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4815 prepare_work();
4816 }
4817
4818 ~G1FreeCollectionSetTask() {
4819 complete_work();
4820 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4821 }
4822
4823 // Chunk size for work distribution. The chosen value has been determined experimentally
4824 // to be a good tradeoff between overhead and achievable parallelism.
4825 static uint chunk_size() { return 32; }
4826
4827 virtual void work(uint worker_id) {
4828 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4829
4830 // Claim serial work.
4831 if (_serial_work_claim == 0) {
4832 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4833 if (value == 0) {
4834 double serial_time = os::elapsedTime();
4835 do_serial_work();
4836 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4837 }
4838 }
4839
4840 // Start parallel work.
4841 double young_time = 0.0;
4842 bool has_young_time = false;
4843 double non_young_time = 0.0;
4844 bool has_non_young_time = false;
4845
4846 while (true) {
4847 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4848 size_t cur = end - chunk_size();
4849
4850 if (cur >= _num_work_items) {
4851 break;
4852 }
4853
4854 double start_time = os::elapsedTime();
4855
4856 end = MIN2(end, _num_work_items);
4857
4858 for (; cur < end; cur++) {
4859 bool is_young = _work_items[cur].is_young;
4860
4861 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4862
4863 double end_time = os::elapsedTime();
4864 double time_taken = end_time - start_time;
4865 if (is_young) {
4866 young_time += time_taken;
4867 has_young_time = true;
4868 } else {
4869 non_young_time += time_taken;
4870 has_non_young_time = true;
4871 }
4872 start_time = end_time;
4873 }
4874 }
4875
4876 if (has_young_time) {
4877 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4878 }
4879 if (has_non_young_time) {
4880 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4881 }
4882 }
4883 };
4884
4885 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4886 _eden.clear();
4887
4888 double free_cset_start_time = os::elapsedTime();
4889
4890 {
4891 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4892 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4893
4894 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4895
4896 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4897 cl.name(),
4898 num_workers,
4899 _collection_set.region_length());
4900 workers()->run_task(&cl, num_workers);
4901 }
4902 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4903
4904 collection_set->clear();
4905 }
4906
4907 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4908 private:
4909 FreeRegionList* _free_region_list;
4910 HeapRegionSet* _proxy_set;
4911 uint _humongous_regions_removed;
4912 size_t _freed_bytes;
4913 public:
4914
4915 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4916 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4917 }
4918
4919 virtual bool doHeapRegion(HeapRegion* r) {
4920 if (!r->is_starts_humongous()) {
4921 return false;
4922 }
4923
4924 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4925
4926 oop obj = (oop)r->bottom();
4927 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4928
4929 // The following checks whether the humongous object is live are sufficient.
4930 // The main additional check (in addition to having a reference from the roots
4931 // or the young gen) is whether the humongous object has a remembered set entry.
4932 //
4933 // A humongous object cannot be live if there is no remembered set for it
4934 // because:
4935 // - there can be no references from within humongous starts regions referencing
4936 // the object because we never allocate other objects into them.
4937 // (I.e. there are no intra-region references that may be missed by the
4938 // remembered set)
4939 // - as soon there is a remembered set entry to the humongous starts region
4940 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4941 // until the end of a concurrent mark.
4942 //
4943 // It is not required to check whether the object has been found dead by marking
4944 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4945 // all objects allocated during that time are considered live.
4946 // SATB marking is even more conservative than the remembered set.
4947 // So if at this point in the collection there is no remembered set entry,
4948 // nobody has a reference to it.
4949 // At the start of collection we flush all refinement logs, and remembered sets
4950 // are completely up-to-date wrt to references to the humongous object.
4951 //
4952 // Other implementation considerations:
4953 // - never consider object arrays at this time because they would pose
4954 // considerable effort for cleaning up the the remembered sets. This is
4955 // required because stale remembered sets might reference locations that
4956 // are currently allocated into.
4957 uint region_idx = r->hrm_index();
4958 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4959 !r->rem_set()->is_empty()) {
4960 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",
4961 region_idx,
4962 (size_t)obj->size() * HeapWordSize,
4963 p2i(r->bottom()),
4964 r->rem_set()->occupied(),
4965 r->rem_set()->strong_code_roots_list_length(),
4966 next_bitmap->isMarked(r->bottom()),
4967 g1h->is_humongous_reclaim_candidate(region_idx),
4968 obj->is_typeArray()
4969 );
4970 return false;
4971 }
4972
4973 guarantee(obj->is_typeArray(),
4974 "Only eagerly reclaiming type arrays is supported, but the object "
4975 PTR_FORMAT " is not.", p2i(r->bottom()));
4976
4977 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",
4978 region_idx,
4979 (size_t)obj->size() * HeapWordSize,
4980 p2i(r->bottom()),
4981 r->rem_set()->occupied(),
4982 r->rem_set()->strong_code_roots_list_length(),
4983 next_bitmap->isMarked(r->bottom()),
4984 g1h->is_humongous_reclaim_candidate(region_idx),
4985 obj->is_typeArray()
4986 );
4987
4988 // Need to clear mark bit of the humongous object if already set.
4989 if (next_bitmap->isMarked(r->bottom())) {
4990 next_bitmap->clear(r->bottom());
4991 }
4992 do {
4993 HeapRegion* next = g1h->next_region_in_humongous(r);
4994 _freed_bytes += r->used();
4995 r->set_containing_set(NULL);
4996 _humongous_regions_removed++;
4997 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4998 r = next;
4999 } while (r != NULL);
5000
5001 return false;
5002 }
5003
5004 uint humongous_free_count() {
5005 return _humongous_regions_removed;
5006 }
5007
5008 size_t bytes_freed() const {
5009 return _freed_bytes;
5010 }
5011 };
5012
5013 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5014 assert_at_safepoint(true);
5015
5016 if (!G1EagerReclaimHumongousObjects ||
5017 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5018 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5019 return;
5020 }
5021
5022 double start_time = os::elapsedTime();
5023
5024 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5025
5026 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5027 heap_region_iterate(&cl);
5028
5029 remove_from_old_sets(0, cl.humongous_free_count());
5030
5031 G1HRPrinter* hrp = hr_printer();
5032 if (hrp->is_active()) {
5033 FreeRegionListIterator iter(&local_cleanup_list);
5034 while (iter.more_available()) {
5035 HeapRegion* hr = iter.get_next();
5036 hrp->cleanup(hr);
5037 }
5038 }
5039
5040 prepend_to_freelist(&local_cleanup_list);
5041 decrement_summary_bytes(cl.bytes_freed());
5042
5043 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5044 cl.humongous_free_count());
5045 }
5046
5047 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
5048 public:
5049 virtual bool doHeapRegion(HeapRegion* r) {
5050 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
5051 G1CollectedHeap::heap()->clear_in_cset(r);
5052 r->set_young_index_in_cset(-1);
5053 return false;
5054 }
5055 };
5056
5057 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
5058 G1AbandonCollectionSetClosure cl;
5059 collection_set->iterate(&cl);
5060
5061 collection_set->clear();
5062 collection_set->stop_incremental_building();
5063 }
5064
5065 void G1CollectedHeap::set_free_regions_coming() {
5066 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5067
5068 assert(!free_regions_coming(), "pre-condition");
5069 _free_regions_coming = true;
5070 }
5071
5072 void G1CollectedHeap::reset_free_regions_coming() {
5073 assert(free_regions_coming(), "pre-condition");
5074
5075 {
5076 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5077 _free_regions_coming = false;
5078 SecondaryFreeList_lock->notify_all();
5079 }
5080
5081 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5082 }
5083
5084 void G1CollectedHeap::wait_while_free_regions_coming() {
5085 // Most of the time we won't have to wait, so let's do a quick test
5086 // first before we take the lock.
5087 if (!free_regions_coming()) {
5088 return;
5089 }
5090
5091 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5092
5093 {
5094 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5095 while (free_regions_coming()) {
5096 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5097 }
5098 }
5099
5100 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5101 }
5102
5103 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5104 return _allocator->is_retained_old_region(hr);
5105 }
5106
5107 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5108 _eden.add(hr);
5109 _g1_policy->set_region_eden(hr);
5110 }
5111
5112 #ifdef ASSERT
5113
5114 class NoYoungRegionsClosure: public HeapRegionClosure {
5115 private:
5116 bool _success;
5117 public:
5118 NoYoungRegionsClosure() : _success(true) { }
5119 bool doHeapRegion(HeapRegion* r) {
5120 if (r->is_young()) {
5121 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5122 p2i(r->bottom()), p2i(r->end()));
5123 _success = false;
5124 }
5125 return false;
5126 }
5127 bool success() { return _success; }
5128 };
5129
5130 bool G1CollectedHeap::check_young_list_empty() {
5131 bool ret = (young_regions_count() == 0);
5132
5133 NoYoungRegionsClosure closure;
5134 heap_region_iterate(&closure);
5135 ret = ret && closure.success();
5136
5137 return ret;
5138 }
5139
5140 #endif // ASSERT
5141
5142 class TearDownRegionSetsClosure : public HeapRegionClosure {
5143 private:
5144 HeapRegionSet *_old_set;
5145
5146 public:
5147 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5148
5149 bool doHeapRegion(HeapRegion* r) {
5150 if (r->is_old()) {
5151 _old_set->remove(r);
5152 } else if(r->is_young()) {
5153 r->uninstall_surv_rate_group();
5154 } else {
5155 // We ignore free regions, we'll empty the free list afterwards.
5156 // We ignore humongous regions, we're not tearing down the
5157 // humongous regions set.
5158 assert(r->is_free() || r->is_humongous(),
5159 "it cannot be another type");
5160 }
5161 return false;
5162 }
5163
5164 ~TearDownRegionSetsClosure() {
5165 assert(_old_set->is_empty(), "post-condition");
5166 }
5167 };
5168
5169 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5170 assert_at_safepoint(true /* should_be_vm_thread */);
5171
5172 if (!free_list_only) {
5173 TearDownRegionSetsClosure cl(&_old_set);
5174 heap_region_iterate(&cl);
5175
5176 // Note that emptying the _young_list is postponed and instead done as
5177 // the first step when rebuilding the regions sets again. The reason for
5178 // this is that during a full GC string deduplication needs to know if
5179 // a collected region was young or old when the full GC was initiated.
5180 }
5181 _hrm.remove_all_free_regions();
5182 }
5183
5184 void G1CollectedHeap::increase_used(size_t bytes) {
5185 _summary_bytes_used += bytes;
5186 }
5187
5188 void G1CollectedHeap::decrease_used(size_t bytes) {
5189 assert(_summary_bytes_used >= bytes,
5190 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5191 _summary_bytes_used, bytes);
5192 _summary_bytes_used -= bytes;
5193 }
5194
5195 void G1CollectedHeap::set_used(size_t bytes) {
5196 _summary_bytes_used = bytes;
5197 }
5198
5199 class RebuildRegionSetsClosure : public HeapRegionClosure {
5200 private:
5201 bool _free_list_only;
5202 HeapRegionSet* _old_set;
5203 HeapRegionManager* _hrm;
5204 size_t _total_used;
5205
5206 public:
5207 RebuildRegionSetsClosure(bool free_list_only,
5208 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5209 _free_list_only(free_list_only),
5210 _old_set(old_set), _hrm(hrm), _total_used(0) {
5211 assert(_hrm->num_free_regions() == 0, "pre-condition");
5212 if (!free_list_only) {
5213 assert(_old_set->is_empty(), "pre-condition");
5214 }
5215 }
5216
5217 bool doHeapRegion(HeapRegion* r) {
5218 if (r->is_empty()) {
5219 // Add free regions to the free list
5220 r->set_free();
5221 r->set_allocation_context(AllocationContext::system());
5222 _hrm->insert_into_free_list(r);
5223 } else if (!_free_list_only) {
5224
5225 if (r->is_humongous()) {
5226 // We ignore humongous regions. We left the humongous set unchanged.
5227 } else {
5228 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5229 // We now consider all regions old, so register as such. Leave
5230 // archive regions set that way, however, while still adding
5231 // them to the old set.
5232 if (!r->is_archive()) {
5233 r->set_old();
5234 }
5235 _old_set->add(r);
5236 }
5237 _total_used += r->used();
5238 }
5239
5240 return false;
5241 }
5242
5243 size_t total_used() {
5244 return _total_used;
5245 }
5246 };
5247
5248 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5249 assert_at_safepoint(true /* should_be_vm_thread */);
5250
5251 if (!free_list_only) {
5252 _eden.clear();
5253 _survivor.clear();
5254 }
5255
5256 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5257 heap_region_iterate(&cl);
5258
5259 if (!free_list_only) {
5260 set_used(cl.total_used());
5261 if (_archive_allocator != NULL) {
5262 _archive_allocator->clear_used();
5263 }
5264 }
5265 assert(used_unlocked() == recalculate_used(),
5266 "inconsistent used_unlocked(), "
5267 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5268 used_unlocked(), recalculate_used());
5269 }
5270
5271 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5272 _refine_cte_cl->set_concurrent(concurrent);
5273 }
5274
5275 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5276 HeapRegion* hr = heap_region_containing(p);
5277 return hr->is_in(p);
5278 }
5279
5280 // Methods for the mutator alloc region
5281
5282 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5283 bool force) {
5284 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5285 assert(!force || g1_policy()->can_expand_young_list(),
5286 "if force is true we should be able to expand the young list");
5287 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5288 if (force || should_allocate) {
5289 HeapRegion* new_alloc_region = new_region(word_size,
5290 false /* is_old */,
5291 false /* do_expand */);
5292 if (new_alloc_region != NULL) {
5293 set_region_short_lived_locked(new_alloc_region);
5294 _hr_printer.alloc(new_alloc_region, !should_allocate);
5295 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5296 return new_alloc_region;
5297 }
5298 }
5299 return NULL;
5300 }
5301
5302 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5303 size_t allocated_bytes) {
5304 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5305 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5306
5307 collection_set()->add_eden_region(alloc_region);
5308 increase_used(allocated_bytes);
5309 _hr_printer.retire(alloc_region);
5310 // We update the eden sizes here, when the region is retired,
5311 // instead of when it's allocated, since this is the point that its
5312 // used space has been recored in _summary_bytes_used.
5313 g1mm()->update_eden_size();
5314 }
5315
5316 // Methods for the GC alloc regions
5317
5318 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5319 if (dest.is_old()) {
5320 return true;
5321 } else {
5322 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5323 }
5324 }
5325
5326 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5327 assert(FreeList_lock->owned_by_self(), "pre-condition");
5328
5329 if (!has_more_regions(dest)) {
5330 return NULL;
5331 }
5332
5333 const bool is_survivor = dest.is_young();
5334
5335 HeapRegion* new_alloc_region = new_region(word_size,
5336 !is_survivor,
5337 true /* do_expand */);
5338 if (new_alloc_region != NULL) {
5339 // We really only need to do this for old regions given that we
5340 // should never scan survivors. But it doesn't hurt to do it
5341 // for survivors too.
5342 new_alloc_region->record_timestamp();
5343 if (is_survivor) {
5344 new_alloc_region->set_survivor();
5345 _survivor.add(new_alloc_region);
5346 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5347 } else {
5348 new_alloc_region->set_old();
5349 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5350 }
5351 _hr_printer.alloc(new_alloc_region);
5352 bool during_im = collector_state()->during_initial_mark_pause();
5353 new_alloc_region->note_start_of_copying(during_im);
5354 return new_alloc_region;
5355 }
5356 return NULL;
5357 }
5358
5359 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5360 size_t allocated_bytes,
5361 InCSetState dest) {
5362 bool during_im = collector_state()->during_initial_mark_pause();
5363 alloc_region->note_end_of_copying(during_im);
5364 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5365 if (dest.is_old()) {
5366 _old_set.add(alloc_region);
5367 }
5368 _hr_printer.retire(alloc_region);
5369 }
5370
5371 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5372 bool expanded = false;
5373 uint index = _hrm.find_highest_free(&expanded);
5374
5375 if (index != G1_NO_HRM_INDEX) {
5376 if (expanded) {
5377 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5378 HeapRegion::GrainWords * HeapWordSize);
5379 }
5380 _hrm.allocate_free_regions_starting_at(index, 1);
5381 return region_at(index);
5382 }
5383 return NULL;
5384 }
5385
5386 // Optimized nmethod scanning
5387
5388 class RegisterNMethodOopClosure: public OopClosure {
5389 G1CollectedHeap* _g1h;
5390 nmethod* _nm;
5391
5392 template <class T> void do_oop_work(T* p) {
5393 T heap_oop = oopDesc::load_heap_oop(p);
5394 if (!oopDesc::is_null(heap_oop)) {
5395 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5396 HeapRegion* hr = _g1h->heap_region_containing(obj);
5397 assert(!hr->is_continues_humongous(),
5398 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5399 " starting at " HR_FORMAT,
5400 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5401
5402 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5403 hr->add_strong_code_root_locked(_nm);
5404 }
5405 }
5406
5407 public:
5408 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5409 _g1h(g1h), _nm(nm) {}
5410
5411 void do_oop(oop* p) { do_oop_work(p); }
5412 void do_oop(narrowOop* p) { do_oop_work(p); }
5413 };
5414
5415 class UnregisterNMethodOopClosure: public OopClosure {
5416 G1CollectedHeap* _g1h;
5417 nmethod* _nm;
5418
5419 template <class T> void do_oop_work(T* p) {
5420 T heap_oop = oopDesc::load_heap_oop(p);
5421 if (!oopDesc::is_null(heap_oop)) {
5422 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5423 HeapRegion* hr = _g1h->heap_region_containing(obj);
5424 assert(!hr->is_continues_humongous(),
5425 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5426 " starting at " HR_FORMAT,
5427 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5428
5429 hr->remove_strong_code_root(_nm);
5430 }
5431 }
5432
5433 public:
5434 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5435 _g1h(g1h), _nm(nm) {}
5436
5437 void do_oop(oop* p) { do_oop_work(p); }
5438 void do_oop(narrowOop* p) { do_oop_work(p); }
5439 };
5440
5441 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5442 CollectedHeap::register_nmethod(nm);
5443
5444 guarantee(nm != NULL, "sanity");
5445 RegisterNMethodOopClosure reg_cl(this, nm);
5446 nm->oops_do(®_cl);
5447 }
5448
5449 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5450 CollectedHeap::unregister_nmethod(nm);
5451
5452 guarantee(nm != NULL, "sanity");
5453 UnregisterNMethodOopClosure reg_cl(this, nm);
5454 nm->oops_do(®_cl, true);
5455 }
5456
5457 void G1CollectedHeap::purge_code_root_memory() {
5458 double purge_start = os::elapsedTime();
5459 G1CodeRootSet::purge();
5460 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5461 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5462 }
5463
5464 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5465 G1CollectedHeap* _g1h;
5466
5467 public:
5468 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5469 _g1h(g1h) {}
5470
5471 void do_code_blob(CodeBlob* cb) {
5472 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5473 if (nm == NULL) {
5474 return;
5475 }
5476
5477 if (ScavengeRootsInCode) {
5478 _g1h->register_nmethod(nm);
5479 }
5480 }
5481 };
5482
5483 void G1CollectedHeap::rebuild_strong_code_roots() {
5484 RebuildStrongCodeRootClosure blob_cl(this);
5485 CodeCache::blobs_do(&blob_cl);
5486 }