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