1 /*
2 * Copyright (c) 2001, 2015, 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 "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1Allocator.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1EvacFailure.hpp"
39 #include "gc/g1/g1GCPhaseTimes.hpp"
40 #include "gc/g1/g1MarkSweep.hpp"
41 #include "gc/g1/g1OopClosures.inline.hpp"
42 #include "gc/g1/g1ParScanThreadState.inline.hpp"
43 #include "gc/g1/g1RegionToSpaceMapper.hpp"
44 #include "gc/g1/g1RemSet.inline.hpp"
45 #include "gc/g1/g1RootClosures.hpp"
46 #include "gc/g1/g1RootProcessor.hpp"
47 #include "gc/g1/g1StringDedup.hpp"
48 #include "gc/g1/g1YCTypes.hpp"
49 #include "gc/g1/heapRegion.inline.hpp"
50 #include "gc/g1/heapRegionRemSet.hpp"
51 #include "gc/g1/heapRegionSet.inline.hpp"
52 #include "gc/g1/suspendibleThreadSet.hpp"
53 #include "gc/g1/vm_operations_g1.hpp"
54 #include "gc/shared/gcHeapSummary.hpp"
55 #include "gc/shared/gcId.hpp"
56 #include "gc/shared/gcLocker.inline.hpp"
57 #include "gc/shared/gcTimer.hpp"
58 #include "gc/shared/gcTrace.hpp"
59 #include "gc/shared/gcTraceTime.hpp"
60 #include "gc/shared/generationSpec.hpp"
61 #include "gc/shared/isGCActiveMark.hpp"
62 #include "gc/shared/referenceProcessor.hpp"
63 #include "gc/shared/taskqueue.inline.hpp"
64 #include "logging/log.hpp"
65 #include "memory/allocation.hpp"
66 #include "memory/iterator.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "runtime/atomic.inline.hpp"
69 #include "runtime/init.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73 #include "utilities/stack.inline.hpp"
74
75 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
76
77 // INVARIANTS/NOTES
78 //
79 // All allocation activity covered by the G1CollectedHeap interface is
80 // serialized by acquiring the HeapLock. This happens in mem_allocate
81 // and allocate_new_tlab, which are the "entry" points to the
82 // allocation code from the rest of the JVM. (Note that this does not
83 // apply to TLAB allocation, which is not part of this interface: it
84 // is done by clients of this interface.)
85
86 // Local to this file.
87
88 class RefineCardTableEntryClosure: public CardTableEntryClosure {
89 bool _concurrent;
90 public:
91 RefineCardTableEntryClosure() : _concurrent(true) { }
92
93 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
94 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
95 // This path is executed by the concurrent refine or mutator threads,
96 // concurrently, and so we do not care if card_ptr contains references
97 // that point into the collection set.
98 assert(!oops_into_cset, "should be");
99
100 if (_concurrent && SuspendibleThreadSet::should_yield()) {
101 // Caller will actually yield.
102 return false;
103 }
104 // Otherwise, we finished successfully; return true.
105 return true;
106 }
107
108 void set_concurrent(bool b) { _concurrent = b; }
109 };
110
111
112 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
113 private:
114 size_t _num_processed;
115
116 public:
117 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
118
119 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
120 *card_ptr = CardTableModRefBS::dirty_card_val();
121 _num_processed++;
122 return true;
123 }
124
125 size_t num_processed() const { return _num_processed; }
126 };
127
128
129 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
130 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
131 }
132
133 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
134 // The from card cache is not the memory that is actually committed. So we cannot
135 // take advantage of the zero_filled parameter.
136 reset_from_card_cache(start_idx, num_regions);
137 }
138
139 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
140 {
141 // Claim the right to put the region on the dirty cards region list
142 // by installing a self pointer.
143 HeapRegion* next = hr->get_next_dirty_cards_region();
144 if (next == NULL) {
145 HeapRegion* res = (HeapRegion*)
146 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
147 NULL);
148 if (res == NULL) {
149 HeapRegion* head;
150 do {
151 // Put the region to the dirty cards region list.
152 head = _dirty_cards_region_list;
153 next = (HeapRegion*)
154 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
155 if (next == head) {
156 assert(hr->get_next_dirty_cards_region() == hr,
157 "hr->get_next_dirty_cards_region() != hr");
158 if (next == NULL) {
159 // The last region in the list points to itself.
160 hr->set_next_dirty_cards_region(hr);
161 } else {
162 hr->set_next_dirty_cards_region(next);
163 }
164 }
165 } while (next != head);
166 }
167 }
168 }
169
170 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
171 {
172 HeapRegion* head;
173 HeapRegion* hr;
174 do {
175 head = _dirty_cards_region_list;
176 if (head == NULL) {
177 return NULL;
178 }
179 HeapRegion* new_head = head->get_next_dirty_cards_region();
180 if (head == new_head) {
181 // The last region.
182 new_head = NULL;
183 }
184 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
185 head);
186 } while (hr != head);
187 assert(hr != NULL, "invariant");
188 hr->set_next_dirty_cards_region(NULL);
189 return hr;
190 }
191
192 // Returns true if the reference points to an object that
193 // can move in an incremental collection.
194 bool G1CollectedHeap::is_scavengable(const void* p) {
195 HeapRegion* hr = heap_region_containing(p);
196 return !hr->is_pinned();
197 }
198
199 // Private methods.
200
201 HeapRegion*
202 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
203 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
204 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
205 if (!_secondary_free_list.is_empty()) {
206 log_develop(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
207 "secondary_free_list has %u entries",
208 _secondary_free_list.length());
209 // It looks as if there are free regions available on the
210 // secondary_free_list. Let's move them to the free_list and try
211 // again to allocate from it.
212 append_secondary_free_list();
213
214 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
215 "empty we should have moved at least one entry to the free_list");
216 HeapRegion* res = _hrm.allocate_free_region(is_old);
217 log_develop(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
218 "allocated " HR_FORMAT " from secondary_free_list",
219 HR_FORMAT_PARAMS(res));
220 return res;
221 }
222
223 // Wait here until we get notified either when (a) there are no
224 // more free regions coming or (b) some regions have been moved on
225 // the secondary_free_list.
226 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
227 }
228
229 log_develop(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
230 "could not allocate from secondary_free_list");
231 return NULL;
232 }
233
234 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
235 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
236 "the only time we use this to allocate a humongous region is "
237 "when we are allocating a single humongous region");
238
239 HeapRegion* res;
240 if (G1StressConcRegionFreeing) {
241 if (!_secondary_free_list.is_empty()) {
242 log_develop(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
243 "forced to look at the secondary_free_list");
244 res = new_region_try_secondary_free_list(is_old);
245 if (res != NULL) {
246 return res;
247 }
248 }
249 }
250
251 res = _hrm.allocate_free_region(is_old);
252
253 if (res == NULL) {
254 log_develop(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
255 "res == NULL, trying the secondary_free_list");
256 res = new_region_try_secondary_free_list(is_old);
257 }
258 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
259 // Currently, only attempts to allocate GC alloc regions set
260 // do_expand to true. So, we should only reach here during a
261 // safepoint. If this assumption changes we might have to
262 // reconsider the use of _expand_heap_after_alloc_failure.
263 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
264
265 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
266 word_size * HeapWordSize);
267
268 if (expand(word_size * HeapWordSize)) {
269 // Given that expand() succeeded in expanding the heap, and we
270 // always expand the heap by an amount aligned to the heap
271 // region size, the free list should in theory not be empty.
272 // In either case allocate_free_region() will check for NULL.
273 res = _hrm.allocate_free_region(is_old);
274 } else {
275 _expand_heap_after_alloc_failure = false;
276 }
277 }
278 return res;
279 }
280
281 HeapWord*
282 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
283 uint num_regions,
284 size_t word_size,
285 AllocationContext_t context) {
286 assert(first != G1_NO_HRM_INDEX, "pre-condition");
287 assert(is_humongous(word_size), "word_size should be humongous");
288 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
289
290 // Index of last region in the series + 1.
291 uint last = first + num_regions;
292
293 // We need to initialize the region(s) we just discovered. This is
294 // a bit tricky given that it can happen concurrently with
295 // refinement threads refining cards on these regions and
296 // potentially wanting to refine the BOT as they are scanning
297 // those cards (this can happen shortly after a cleanup; see CR
298 // 6991377). So we have to set up the region(s) carefully and in
299 // a specific order.
300
301 // The word size sum of all the regions we will allocate.
302 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
303 assert(word_size <= word_size_sum, "sanity");
304
305 // This will be the "starts humongous" region.
306 HeapRegion* first_hr = region_at(first);
307 // The header of the new object will be placed at the bottom of
308 // the first region.
309 HeapWord* new_obj = first_hr->bottom();
310 // This will be the new top of the new object.
311 HeapWord* obj_top = new_obj + word_size;
312
313 // First, we need to zero the header of the space that we will be
314 // allocating. When we update top further down, some refinement
315 // threads might try to scan the region. By zeroing the header we
316 // ensure that any thread that will try to scan the region will
317 // come across the zero klass word and bail out.
318 //
319 // NOTE: It would not have been correct to have used
320 // CollectedHeap::fill_with_object() and make the space look like
321 // an int array. The thread that is doing the allocation will
322 // later update the object header to a potentially different array
323 // type and, for a very short period of time, the klass and length
324 // fields will be inconsistent. This could cause a refinement
325 // thread to calculate the object size incorrectly.
326 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
327
328 // We will set up the first region as "starts humongous". This
329 // will also update the BOT covering all the regions to reflect
330 // that there is a single object that starts at the bottom of the
331 // first region.
332 first_hr->set_starts_humongous(obj_top);
333 first_hr->set_allocation_context(context);
334 // Then, if there are any, we will set up the "continues
335 // humongous" regions.
336 HeapRegion* hr = NULL;
337 for (uint i = first + 1; i < last; ++i) {
338 hr = region_at(i);
339 hr->set_continues_humongous(first_hr);
340 hr->set_allocation_context(context);
341 }
342
343 // Up to this point no concurrent thread would have been able to
344 // do any scanning on any region in this series. All the top
345 // fields still point to bottom, so the intersection between
346 // [bottom,top] and [card_start,card_end] will be empty. Before we
347 // update the top fields, we'll do a storestore to make sure that
348 // no thread sees the update to top before the zeroing of the
349 // object header and the BOT initialization.
350 OrderAccess::storestore();
351
352 // Now that the BOT and the object header have been initialized,
353 // we can update top of the "starts humongous" region.
354 first_hr->set_top(MIN2(first_hr->end(), obj_top));
355 if (_hr_printer.is_active()) {
356 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->top());
357 }
358
359 // Now, we will update the top fields of the "continues humongous"
360 // regions.
361 hr = NULL;
362 for (uint i = first + 1; i < last; ++i) {
363 hr = region_at(i);
364 if ((i + 1) == last) {
365 // last continues humongous region
366 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
367 "new_top should fall on this region");
368 hr->set_top(obj_top);
369 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, obj_top);
370 } else {
371 // not last one
372 assert(obj_top > hr->end(), "obj_top should be above this region");
373 hr->set_top(hr->end());
374 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
375 }
376 }
377 // If we have continues humongous regions (hr != NULL), its top should
378 // match obj_top.
379 assert(hr == NULL || (hr->top() == obj_top), "sanity");
380 check_bitmaps("Humongous Region Allocation", first_hr);
381
382 increase_used(word_size * HeapWordSize);
383
384 for (uint i = first; i < last; ++i) {
385 _humongous_set.add(region_at(i));
386 }
387
388 return new_obj;
389 }
390
391 // If could fit into free regions w/o expansion, try.
392 // Otherwise, if can expand, do so.
393 // Otherwise, if using ex regions might help, try with ex given back.
394 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
395 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
396
397 verify_region_sets_optional();
398
399 uint first = G1_NO_HRM_INDEX;
400 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
401
402 if (obj_regions == 1) {
403 // Only one region to allocate, try to use a fast path by directly allocating
404 // from the free lists. Do not try to expand here, we will potentially do that
405 // later.
406 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
407 if (hr != NULL) {
408 first = hr->hrm_index();
409 }
410 } else {
411 // We can't allocate humongous regions spanning more than one region while
412 // cleanupComplete() is running, since some of the regions we find to be
413 // empty might not yet be added to the free list. It is not straightforward
414 // to know in which list they are on so that we can remove them. We only
415 // need to do this if we need to allocate more than one region to satisfy the
416 // current humongous allocation request. If we are only allocating one region
417 // we use the one-region region allocation code (see above), that already
418 // potentially waits for regions from the secondary free list.
419 wait_while_free_regions_coming();
420 append_secondary_free_list_if_not_empty_with_lock();
421
422 // Policy: Try only empty regions (i.e. already committed first). Maybe we
423 // are lucky enough to find some.
424 first = _hrm.find_contiguous_only_empty(obj_regions);
425 if (first != G1_NO_HRM_INDEX) {
426 _hrm.allocate_free_regions_starting_at(first, obj_regions);
427 }
428 }
429
430 if (first == G1_NO_HRM_INDEX) {
431 // Policy: We could not find enough regions for the humongous object in the
432 // free list. Look through the heap to find a mix of free and uncommitted regions.
433 // If so, try expansion.
434 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
435 if (first != G1_NO_HRM_INDEX) {
436 // We found something. Make sure these regions are committed, i.e. expand
437 // the heap. Alternatively we could do a defragmentation GC.
438 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
439 word_size * HeapWordSize);
440
441
442 _hrm.expand_at(first, obj_regions);
443 g1_policy()->record_new_heap_size(num_regions());
444
445 #ifdef ASSERT
446 for (uint i = first; i < first + obj_regions; ++i) {
447 HeapRegion* hr = region_at(i);
448 assert(hr->is_free(), "sanity");
449 assert(hr->is_empty(), "sanity");
450 assert(is_on_master_free_list(hr), "sanity");
451 }
452 #endif
453 _hrm.allocate_free_regions_starting_at(first, obj_regions);
454 } else {
455 // Policy: Potentially trigger a defragmentation GC.
456 }
457 }
458
459 HeapWord* result = NULL;
460 if (first != G1_NO_HRM_INDEX) {
461 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
462 word_size, context);
463 assert(result != NULL, "it should always return a valid result");
464
465 // A successful humongous object allocation changes the used space
466 // information of the old generation so we need to recalculate the
467 // sizes and update the jstat counters here.
468 g1mm()->update_sizes();
469 }
470
471 verify_region_sets_optional();
472
473 return result;
474 }
475
476 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
477 assert_heap_not_locked_and_not_at_safepoint();
478 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
479
480 uint dummy_gc_count_before;
481 uint dummy_gclocker_retry_count = 0;
482 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
483 }
484
485 HeapWord*
486 G1CollectedHeap::mem_allocate(size_t word_size,
487 bool* gc_overhead_limit_was_exceeded) {
488 assert_heap_not_locked_and_not_at_safepoint();
489
490 // Loop until the allocation is satisfied, or unsatisfied after GC.
491 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
492 uint gc_count_before;
493
494 HeapWord* result = NULL;
495 if (!is_humongous(word_size)) {
496 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
497 } else {
498 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
499 }
500 if (result != NULL) {
501 return result;
502 }
503
504 // Create the garbage collection operation...
505 VM_G1CollectForAllocation op(gc_count_before, word_size);
506 op.set_allocation_context(AllocationContext::current());
507
508 // ...and get the VM thread to execute it.
509 VMThread::execute(&op);
510
511 if (op.prologue_succeeded() && op.pause_succeeded()) {
512 // If the operation was successful we'll return the result even
513 // if it is NULL. If the allocation attempt failed immediately
514 // after a Full GC, it's unlikely we'll be able to allocate now.
515 HeapWord* result = op.result();
516 if (result != NULL && !is_humongous(word_size)) {
517 // Allocations that take place on VM operations do not do any
518 // card dirtying and we have to do it here. We only have to do
519 // this for non-humongous allocations, though.
520 dirty_young_block(result, word_size);
521 }
522 return result;
523 } else {
524 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
525 return NULL;
526 }
527 assert(op.result() == NULL,
528 "the result should be NULL if the VM op did not succeed");
529 }
530
531 // Give a warning if we seem to be looping forever.
532 if ((QueuedAllocationWarningCount > 0) &&
533 (try_count % QueuedAllocationWarningCount == 0)) {
534 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
535 }
536 }
537
538 ShouldNotReachHere();
539 return NULL;
540 }
541
542 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
543 AllocationContext_t context,
544 uint* gc_count_before_ret,
545 uint* gclocker_retry_count_ret) {
546 // Make sure you read the note in attempt_allocation_humongous().
547
548 assert_heap_not_locked_and_not_at_safepoint();
549 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
550 "be called for humongous allocation requests");
551
552 // We should only get here after the first-level allocation attempt
553 // (attempt_allocation()) failed to allocate.
554
555 // We will loop until a) we manage to successfully perform the
556 // allocation or b) we successfully schedule a collection which
557 // fails to perform the allocation. b) is the only case when we'll
558 // return NULL.
559 HeapWord* result = NULL;
560 for (int try_count = 1; /* we'll return */; try_count += 1) {
561 bool should_try_gc;
562 uint gc_count_before;
563
564 {
565 MutexLockerEx x(Heap_lock);
566 result = _allocator->attempt_allocation_locked(word_size, context);
567 if (result != NULL) {
568 return result;
569 }
570
571 if (GC_locker::is_active_and_needs_gc()) {
572 if (g1_policy()->can_expand_young_list()) {
573 // No need for an ergo verbose message here,
574 // can_expand_young_list() does this when it returns true.
575 result = _allocator->attempt_allocation_force(word_size, context);
576 if (result != NULL) {
577 return result;
578 }
579 }
580 should_try_gc = false;
581 } else {
582 // The GCLocker may not be active but the GCLocker initiated
583 // GC may not yet have been performed (GCLocker::needs_gc()
584 // returns true). In this case we do not try this GC and
585 // wait until the GCLocker initiated GC is performed, and
586 // then retry the allocation.
587 if (GC_locker::needs_gc()) {
588 should_try_gc = false;
589 } else {
590 // Read the GC count while still holding the Heap_lock.
591 gc_count_before = total_collections();
592 should_try_gc = true;
593 }
594 }
595 }
596
597 if (should_try_gc) {
598 bool succeeded;
599 result = do_collection_pause(word_size, gc_count_before, &succeeded,
600 GCCause::_g1_inc_collection_pause);
601 if (result != NULL) {
602 assert(succeeded, "only way to get back a non-NULL result");
603 return result;
604 }
605
606 if (succeeded) {
607 // If we get here we successfully scheduled a collection which
608 // failed to allocate. No point in trying to allocate
609 // further. We'll just return NULL.
610 MutexLockerEx x(Heap_lock);
611 *gc_count_before_ret = total_collections();
612 return NULL;
613 }
614 } else {
615 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
616 MutexLockerEx x(Heap_lock);
617 *gc_count_before_ret = total_collections();
618 return NULL;
619 }
620 // The GCLocker is either active or the GCLocker initiated
621 // GC has not yet been performed. Stall until it is and
622 // then retry the allocation.
623 GC_locker::stall_until_clear();
624 (*gclocker_retry_count_ret) += 1;
625 }
626
627 // We can reach here if we were unsuccessful in scheduling a
628 // collection (because another thread beat us to it) or if we were
629 // stalled due to the GC locker. In either can we should retry the
630 // allocation attempt in case another thread successfully
631 // performed a collection and reclaimed enough space. We do the
632 // first attempt (without holding the Heap_lock) here and the
633 // follow-on attempt will be at the start of the next loop
634 // iteration (after taking the Heap_lock).
635 result = _allocator->attempt_allocation(word_size, context);
636 if (result != NULL) {
637 return result;
638 }
639
640 // Give a warning if we seem to be looping forever.
641 if ((QueuedAllocationWarningCount > 0) &&
642 (try_count % QueuedAllocationWarningCount == 0)) {
643 warning("G1CollectedHeap::attempt_allocation_slow() "
644 "retries %d times", try_count);
645 }
646 }
647
648 ShouldNotReachHere();
649 return NULL;
650 }
651
652 void G1CollectedHeap::begin_archive_alloc_range() {
653 assert_at_safepoint(true /* should_be_vm_thread */);
654 if (_archive_allocator == NULL) {
655 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
656 }
657 }
658
659 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
660 // Allocations in archive regions cannot be of a size that would be considered
661 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
662 // may be different at archive-restore time.
663 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
664 }
665
666 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
667 assert_at_safepoint(true /* should_be_vm_thread */);
668 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
669 if (is_archive_alloc_too_large(word_size)) {
670 return NULL;
671 }
672 return _archive_allocator->archive_mem_allocate(word_size);
673 }
674
675 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
676 size_t end_alignment_in_bytes) {
677 assert_at_safepoint(true /* should_be_vm_thread */);
678 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
679
680 // Call complete_archive to do the real work, filling in the MemRegion
681 // array with the archive regions.
682 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
683 delete _archive_allocator;
684 _archive_allocator = NULL;
685 }
686
687 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
688 assert(ranges != NULL, "MemRegion array NULL");
689 assert(count != 0, "No MemRegions provided");
690 MemRegion reserved = _hrm.reserved();
691 for (size_t i = 0; i < count; i++) {
692 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
693 return false;
694 }
695 }
696 return true;
697 }
698
699 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
700 assert(!is_init_completed(), "Expect to be called at JVM init time");
701 assert(ranges != NULL, "MemRegion array NULL");
702 assert(count != 0, "No MemRegions provided");
703 MutexLockerEx x(Heap_lock);
704
705 MemRegion reserved = _hrm.reserved();
706 HeapWord* prev_last_addr = NULL;
707 HeapRegion* prev_last_region = NULL;
708
709 // Temporarily disable pretouching of heap pages. This interface is used
710 // when mmap'ing archived heap data in, so pre-touching is wasted.
711 FlagSetting fs(AlwaysPreTouch, false);
712
713 // Enable archive object checking in G1MarkSweep. We have to let it know
714 // about each archive range, so that objects in those ranges aren't marked.
715 G1MarkSweep::enable_archive_object_check();
716
717 // For each specified MemRegion range, allocate the corresponding G1
718 // regions and mark them as archive regions. We expect the ranges in
719 // ascending starting address order, without overlap.
720 for (size_t i = 0; i < count; i++) {
721 MemRegion curr_range = ranges[i];
722 HeapWord* start_address = curr_range.start();
723 size_t word_size = curr_range.word_size();
724 HeapWord* last_address = curr_range.last();
725 size_t commits = 0;
726
727 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
728 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
729 p2i(start_address), p2i(last_address));
730 guarantee(start_address > prev_last_addr,
731 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
732 p2i(start_address), p2i(prev_last_addr));
733 prev_last_addr = last_address;
734
735 // Check for ranges that start in the same G1 region in which the previous
736 // range ended, and adjust the start address so we don't try to allocate
737 // the same region again. If the current range is entirely within that
738 // region, skip it, just adjusting the recorded top.
739 HeapRegion* start_region = _hrm.addr_to_region(start_address);
740 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
741 start_address = start_region->end();
742 if (start_address > last_address) {
743 increase_used(word_size * HeapWordSize);
744 start_region->set_top(last_address + 1);
745 continue;
746 }
747 start_region->set_top(start_address);
748 curr_range = MemRegion(start_address, last_address + 1);
749 start_region = _hrm.addr_to_region(start_address);
750 }
751
752 // Perform the actual region allocation, exiting if it fails.
753 // Then note how much new space we have allocated.
754 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
755 return false;
756 }
757 increase_used(word_size * HeapWordSize);
758 if (commits != 0) {
759 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
760 HeapRegion::GrainWords * HeapWordSize * commits);
761
762 }
763
764 // Mark each G1 region touched by the range as archive, add it to the old set,
765 // and set the allocation context and top.
766 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
767 HeapRegion* last_region = _hrm.addr_to_region(last_address);
768 prev_last_region = last_region;
769
770 while (curr_region != NULL) {
771 assert(curr_region->is_empty() && !curr_region->is_pinned(),
772 "Region already in use (index %u)", curr_region->hrm_index());
773 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
774 curr_region->set_allocation_context(AllocationContext::system());
775 curr_region->set_archive();
776 _old_set.add(curr_region);
777 if (curr_region != last_region) {
778 curr_region->set_top(curr_region->end());
779 curr_region = _hrm.next_region_in_heap(curr_region);
780 } else {
781 curr_region->set_top(last_address + 1);
782 curr_region = NULL;
783 }
784 }
785
786 // Notify mark-sweep of the archive range.
787 G1MarkSweep::set_range_archive(curr_range, true);
788 }
789 return true;
790 }
791
792 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
793 assert(!is_init_completed(), "Expect to be called at JVM init time");
794 assert(ranges != NULL, "MemRegion array NULL");
795 assert(count != 0, "No MemRegions provided");
796 MemRegion reserved = _hrm.reserved();
797 HeapWord *prev_last_addr = NULL;
798 HeapRegion* prev_last_region = NULL;
799
800 // For each MemRegion, create filler objects, if needed, in the G1 regions
801 // that contain the address range. The address range actually within the
802 // MemRegion will not be modified. That is assumed to have been initialized
803 // elsewhere, probably via an mmap of archived heap data.
804 MutexLockerEx x(Heap_lock);
805 for (size_t i = 0; i < count; i++) {
806 HeapWord* start_address = ranges[i].start();
807 HeapWord* last_address = ranges[i].last();
808
809 assert(reserved.contains(start_address) && reserved.contains(last_address),
810 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
811 p2i(start_address), p2i(last_address));
812 assert(start_address > prev_last_addr,
813 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
814 p2i(start_address), p2i(prev_last_addr));
815
816 HeapRegion* start_region = _hrm.addr_to_region(start_address);
817 HeapRegion* last_region = _hrm.addr_to_region(last_address);
818 HeapWord* bottom_address = start_region->bottom();
819
820 // Check for a range beginning in the same region in which the
821 // previous one ended.
822 if (start_region == prev_last_region) {
823 bottom_address = prev_last_addr + 1;
824 }
825
826 // Verify that the regions were all marked as archive regions by
827 // alloc_archive_regions.
828 HeapRegion* curr_region = start_region;
829 while (curr_region != NULL) {
830 guarantee(curr_region->is_archive(),
831 "Expected archive region at index %u", curr_region->hrm_index());
832 if (curr_region != last_region) {
833 curr_region = _hrm.next_region_in_heap(curr_region);
834 } else {
835 curr_region = NULL;
836 }
837 }
838
839 prev_last_addr = last_address;
840 prev_last_region = last_region;
841
842 // Fill the memory below the allocated range with dummy object(s),
843 // if the region bottom does not match the range start, or if the previous
844 // range ended within the same G1 region, and there is a gap.
845 if (start_address != bottom_address) {
846 size_t fill_size = pointer_delta(start_address, bottom_address);
847 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
848 increase_used(fill_size * HeapWordSize);
849 }
850 }
851 }
852
853 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
854 uint* gc_count_before_ret,
855 uint* gclocker_retry_count_ret) {
856 assert_heap_not_locked_and_not_at_safepoint();
857 assert(!is_humongous(word_size), "attempt_allocation() should not "
858 "be called for humongous allocation requests");
859
860 AllocationContext_t context = AllocationContext::current();
861 HeapWord* result = _allocator->attempt_allocation(word_size, context);
862
863 if (result == NULL) {
864 result = attempt_allocation_slow(word_size,
865 context,
866 gc_count_before_ret,
867 gclocker_retry_count_ret);
868 }
869 assert_heap_not_locked();
870 if (result != NULL) {
871 dirty_young_block(result, word_size);
872 }
873 return result;
874 }
875
876 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
877 assert(!is_init_completed(), "Expect to be called at JVM init time");
878 assert(ranges != NULL, "MemRegion array NULL");
879 assert(count != 0, "No MemRegions provided");
880 MemRegion reserved = _hrm.reserved();
881 HeapWord* prev_last_addr = NULL;
882 HeapRegion* prev_last_region = NULL;
883 size_t size_used = 0;
884 size_t uncommitted_regions = 0;
885
886 // For each Memregion, free the G1 regions that constitute it, and
887 // notify mark-sweep that the range is no longer to be considered 'archive.'
888 MutexLockerEx x(Heap_lock);
889 for (size_t i = 0; i < count; i++) {
890 HeapWord* start_address = ranges[i].start();
891 HeapWord* last_address = ranges[i].last();
892
893 assert(reserved.contains(start_address) && reserved.contains(last_address),
894 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
895 p2i(start_address), p2i(last_address));
896 assert(start_address > prev_last_addr,
897 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
898 p2i(start_address), p2i(prev_last_addr));
899 size_used += ranges[i].byte_size();
900 prev_last_addr = last_address;
901
902 HeapRegion* start_region = _hrm.addr_to_region(start_address);
903 HeapRegion* last_region = _hrm.addr_to_region(last_address);
904
905 // Check for ranges that start in the same G1 region in which the previous
906 // range ended, and adjust the start address so we don't try to free
907 // the same region again. If the current range is entirely within that
908 // region, skip it.
909 if (start_region == prev_last_region) {
910 start_address = start_region->end();
911 if (start_address > last_address) {
912 continue;
913 }
914 start_region = _hrm.addr_to_region(start_address);
915 }
916 prev_last_region = last_region;
917
918 // After verifying that each region was marked as an archive region by
919 // alloc_archive_regions, set it free and empty and uncommit it.
920 HeapRegion* curr_region = start_region;
921 while (curr_region != NULL) {
922 guarantee(curr_region->is_archive(),
923 "Expected archive region at index %u", curr_region->hrm_index());
924 uint curr_index = curr_region->hrm_index();
925 _old_set.remove(curr_region);
926 curr_region->set_free();
927 curr_region->set_top(curr_region->bottom());
928 if (curr_region != last_region) {
929 curr_region = _hrm.next_region_in_heap(curr_region);
930 } else {
931 curr_region = NULL;
932 }
933 _hrm.shrink_at(curr_index, 1);
934 uncommitted_regions++;
935 }
936
937 // Notify mark-sweep that this is no longer an archive range.
938 G1MarkSweep::set_range_archive(ranges[i], false);
939 }
940
941 if (uncommitted_regions != 0) {
942 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
943 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
944 }
945 decrease_used(size_used);
946 }
947
948 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
949 uint* gc_count_before_ret,
950 uint* gclocker_retry_count_ret) {
951 // The structure of this method has a lot of similarities to
952 // attempt_allocation_slow(). The reason these two were not merged
953 // into a single one is that such a method would require several "if
954 // allocation is not humongous do this, otherwise do that"
955 // conditional paths which would obscure its flow. In fact, an early
956 // version of this code did use a unified method which was harder to
957 // follow and, as a result, it had subtle bugs that were hard to
958 // track down. So keeping these two methods separate allows each to
959 // be more readable. It will be good to keep these two in sync as
960 // much as possible.
961
962 assert_heap_not_locked_and_not_at_safepoint();
963 assert(is_humongous(word_size), "attempt_allocation_humongous() "
964 "should only be called for humongous allocations");
965
966 // Humongous objects can exhaust the heap quickly, so we should check if we
967 // need to start a marking cycle at each humongous object allocation. We do
968 // the check before we do the actual allocation. The reason for doing it
969 // before the allocation is that we avoid having to keep track of the newly
970 // allocated memory while we do a GC.
971 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
972 word_size)) {
973 collect(GCCause::_g1_humongous_allocation);
974 }
975
976 // We will loop until a) we manage to successfully perform the
977 // allocation or b) we successfully schedule a collection which
978 // fails to perform the allocation. b) is the only case when we'll
979 // return NULL.
980 HeapWord* result = NULL;
981 for (int try_count = 1; /* we'll return */; try_count += 1) {
982 bool should_try_gc;
983 uint gc_count_before;
984
985 {
986 MutexLockerEx x(Heap_lock);
987
988 // Given that humongous objects are not allocated in young
989 // regions, we'll first try to do the allocation without doing a
990 // collection hoping that there's enough space in the heap.
991 result = humongous_obj_allocate(word_size, AllocationContext::current());
992 if (result != NULL) {
993 return result;
994 }
995
996 if (GC_locker::is_active_and_needs_gc()) {
997 should_try_gc = false;
998 } else {
999 // The GCLocker may not be active but the GCLocker initiated
1000 // GC may not yet have been performed (GCLocker::needs_gc()
1001 // returns true). In this case we do not try this GC and
1002 // wait until the GCLocker initiated GC is performed, and
1003 // then retry the allocation.
1004 if (GC_locker::needs_gc()) {
1005 should_try_gc = false;
1006 } else {
1007 // Read the GC count while still holding the Heap_lock.
1008 gc_count_before = total_collections();
1009 should_try_gc = true;
1010 }
1011 }
1012 }
1013
1014 if (should_try_gc) {
1015 // If we failed to allocate the humongous object, we should try to
1016 // do a collection pause (if we're allowed) in case it reclaims
1017 // enough space for the allocation to succeed after the pause.
1018
1019 bool succeeded;
1020 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1021 GCCause::_g1_humongous_allocation);
1022 if (result != NULL) {
1023 assert(succeeded, "only way to get back a non-NULL result");
1024 return result;
1025 }
1026
1027 if (succeeded) {
1028 // If we get here we successfully scheduled a collection which
1029 // failed to allocate. No point in trying to allocate
1030 // further. We'll just return NULL.
1031 MutexLockerEx x(Heap_lock);
1032 *gc_count_before_ret = total_collections();
1033 return NULL;
1034 }
1035 } else {
1036 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1037 MutexLockerEx x(Heap_lock);
1038 *gc_count_before_ret = total_collections();
1039 return NULL;
1040 }
1041 // The GCLocker is either active or the GCLocker initiated
1042 // GC has not yet been performed. Stall until it is and
1043 // then retry the allocation.
1044 GC_locker::stall_until_clear();
1045 (*gclocker_retry_count_ret) += 1;
1046 }
1047
1048 // We can reach here if we were unsuccessful in scheduling a
1049 // collection (because another thread beat us to it) or if we were
1050 // stalled due to the GC locker. In either can we should retry the
1051 // allocation attempt in case another thread successfully
1052 // performed a collection and reclaimed enough space. Give a
1053 // warning if we seem to be looping forever.
1054
1055 if ((QueuedAllocationWarningCount > 0) &&
1056 (try_count % QueuedAllocationWarningCount == 0)) {
1057 warning("G1CollectedHeap::attempt_allocation_humongous() "
1058 "retries %d times", try_count);
1059 }
1060 }
1061
1062 ShouldNotReachHere();
1063 return NULL;
1064 }
1065
1066 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1067 AllocationContext_t context,
1068 bool expect_null_mutator_alloc_region) {
1069 assert_at_safepoint(true /* should_be_vm_thread */);
1070 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1071 "the current alloc region was unexpectedly found to be non-NULL");
1072
1073 if (!is_humongous(word_size)) {
1074 return _allocator->attempt_allocation_locked(word_size, context);
1075 } else {
1076 HeapWord* result = humongous_obj_allocate(word_size, context);
1077 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1078 collector_state()->set_initiate_conc_mark_if_possible(true);
1079 }
1080 return result;
1081 }
1082
1083 ShouldNotReachHere();
1084 }
1085
1086 class PostMCRemSetClearClosure: public HeapRegionClosure {
1087 G1CollectedHeap* _g1h;
1088 ModRefBarrierSet* _mr_bs;
1089 public:
1090 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1091 _g1h(g1h), _mr_bs(mr_bs) {}
1092
1093 bool doHeapRegion(HeapRegion* r) {
1094 HeapRegionRemSet* hrrs = r->rem_set();
1095
1096 _g1h->reset_gc_time_stamps(r);
1097
1098 if (r->is_continues_humongous()) {
1099 // We'll assert that the strong code root list and RSet is empty
1100 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1101 assert(hrrs->occupied() == 0, "RSet should be empty");
1102 } else {
1103 hrrs->clear();
1104 }
1105 // You might think here that we could clear just the cards
1106 // corresponding to the used region. But no: if we leave a dirty card
1107 // in a region we might allocate into, then it would prevent that card
1108 // from being enqueued, and cause it to be missed.
1109 // Re: the performance cost: we shouldn't be doing full GC anyway!
1110 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1111
1112 return false;
1113 }
1114 };
1115
1116 void G1CollectedHeap::clear_rsets_post_compaction() {
1117 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1118 heap_region_iterate(&rs_clear);
1119 }
1120
1121 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1122 G1CollectedHeap* _g1h;
1123 UpdateRSOopClosure _cl;
1124 public:
1125 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1126 _cl(g1->g1_rem_set(), worker_i),
1127 _g1h(g1)
1128 { }
1129
1130 bool doHeapRegion(HeapRegion* r) {
1131 if (!r->is_continues_humongous()) {
1132 _cl.set_from(r);
1133 r->oop_iterate(&_cl);
1134 }
1135 return false;
1136 }
1137 };
1138
1139 class ParRebuildRSTask: public AbstractGangTask {
1140 G1CollectedHeap* _g1;
1141 HeapRegionClaimer _hrclaimer;
1142
1143 public:
1144 ParRebuildRSTask(G1CollectedHeap* g1) :
1145 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1146
1147 void work(uint worker_id) {
1148 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1149 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1150 }
1151 };
1152
1153 class PostCompactionPrinterClosure: public HeapRegionClosure {
1154 private:
1155 G1HRPrinter* _hr_printer;
1156 public:
1157 bool doHeapRegion(HeapRegion* hr) {
1158 assert(!hr->is_young(), "not expecting to find young regions");
1159 if (hr->is_free()) {
1160 // We only generate output for non-empty regions.
1161 } else if (hr->is_starts_humongous()) {
1162 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1163 } else if (hr->is_continues_humongous()) {
1164 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1165 } else if (hr->is_archive()) {
1166 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1167 } else if (hr->is_old()) {
1168 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1169 } else {
1170 ShouldNotReachHere();
1171 }
1172 return false;
1173 }
1174
1175 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1176 : _hr_printer(hr_printer) { }
1177 };
1178
1179 void G1CollectedHeap::print_hrm_post_compaction() {
1180 if (_hr_printer.is_active()) {
1181 PostCompactionPrinterClosure cl(hr_printer());
1182 heap_region_iterate(&cl);
1183 }
1184
1185 }
1186
1187 bool G1CollectedHeap::do_collection(bool explicit_gc,
1188 bool clear_all_soft_refs,
1189 size_t word_size) {
1190 assert_at_safepoint(true /* should_be_vm_thread */);
1191
1192 if (GC_locker::check_active_before_gc()) {
1193 return false;
1194 }
1195
1196 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1197 gc_timer->register_gc_start();
1198
1199 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1200 GCIdMark gc_id_mark;
1201 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1202
1203 SvcGCMarker sgcm(SvcGCMarker::FULL);
1204 ResourceMark rm;
1205
1206 print_heap_before_gc();
1207 trace_heap_before_gc(gc_tracer);
1208
1209 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1210
1211 verify_region_sets_optional();
1212
1213 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1214 collector_policy()->should_clear_all_soft_refs();
1215
1216 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1217
1218 {
1219 IsGCActiveMark x;
1220
1221 // Timing
1222 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1223 GCTraceCPUTime tcpu;
1224
1225 {
1226 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1227 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1228 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1229
1230 g1_policy()->record_full_collection_start();
1231
1232 // Note: When we have a more flexible GC logging framework that
1233 // allows us to add optional attributes to a GC log record we
1234 // could consider timing and reporting how long we wait in the
1235 // following two methods.
1236 wait_while_free_regions_coming();
1237 // If we start the compaction before the CM threads finish
1238 // scanning the root regions we might trip them over as we'll
1239 // be moving objects / updating references. So let's wait until
1240 // they are done. By telling them to abort, they should complete
1241 // early.
1242 _cm->root_regions()->abort();
1243 _cm->root_regions()->wait_until_scan_finished();
1244 append_secondary_free_list_if_not_empty_with_lock();
1245
1246 gc_prologue(true);
1247 increment_total_collections(true /* full gc */);
1248 increment_old_marking_cycles_started();
1249
1250 assert(used() == recalculate_used(), "Should be equal");
1251
1252 verify_before_gc();
1253
1254 check_bitmaps("Full GC Start");
1255 pre_full_gc_dump(gc_timer);
1256
1257 #if defined(COMPILER2) || INCLUDE_JVMCI
1258 DerivedPointerTable::clear();
1259 #endif
1260
1261 // Disable discovery and empty the discovered lists
1262 // for the CM ref processor.
1263 ref_processor_cm()->disable_discovery();
1264 ref_processor_cm()->abandon_partial_discovery();
1265 ref_processor_cm()->verify_no_references_recorded();
1266
1267 // Abandon current iterations of concurrent marking and concurrent
1268 // refinement, if any are in progress. We have to do this before
1269 // wait_until_scan_finished() below.
1270 concurrent_mark()->abort();
1271
1272 // Make sure we'll choose a new allocation region afterwards.
1273 _allocator->release_mutator_alloc_region();
1274 _allocator->abandon_gc_alloc_regions();
1275 g1_rem_set()->cleanupHRRS();
1276
1277 // We may have added regions to the current incremental collection
1278 // set between the last GC or pause and now. We need to clear the
1279 // incremental collection set and then start rebuilding it afresh
1280 // after this full GC.
1281 abandon_collection_set(g1_policy()->inc_cset_head());
1282 g1_policy()->clear_incremental_cset();
1283 g1_policy()->stop_incremental_cset_building();
1284
1285 tear_down_region_sets(false /* free_list_only */);
1286 collector_state()->set_gcs_are_young(true);
1287
1288 // See the comments in g1CollectedHeap.hpp and
1289 // G1CollectedHeap::ref_processing_init() about
1290 // how reference processing currently works in G1.
1291
1292 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1293 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1294
1295 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1296 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1297
1298 ref_processor_stw()->enable_discovery();
1299 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1300
1301 // Do collection work
1302 {
1303 HandleMark hm; // Discard invalid handles created during gc
1304 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1305 }
1306
1307 assert(num_free_regions() == 0, "we should not have added any free regions");
1308 rebuild_region_sets(false /* free_list_only */);
1309
1310 // Enqueue any discovered reference objects that have
1311 // not been removed from the discovered lists.
1312 ref_processor_stw()->enqueue_discovered_references();
1313
1314 #if defined(COMPILER2) || INCLUDE_JVMCI
1315 DerivedPointerTable::update_pointers();
1316 #endif
1317
1318 MemoryService::track_memory_usage();
1319
1320 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1321 ref_processor_stw()->verify_no_references_recorded();
1322
1323 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1324 ClassLoaderDataGraph::purge();
1325 MetaspaceAux::verify_metrics();
1326
1327 // Note: since we've just done a full GC, concurrent
1328 // marking is no longer active. Therefore we need not
1329 // re-enable reference discovery for the CM ref processor.
1330 // That will be done at the start of the next marking cycle.
1331 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1332 ref_processor_cm()->verify_no_references_recorded();
1333
1334 reset_gc_time_stamp();
1335 // Since everything potentially moved, we will clear all remembered
1336 // sets, and clear all cards. Later we will rebuild remembered
1337 // sets. We will also reset the GC time stamps of the regions.
1338 clear_rsets_post_compaction();
1339 check_gc_time_stamps();
1340
1341 // Resize the heap if necessary.
1342 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1343
1344 // We should do this after we potentially resize the heap so
1345 // that all the COMMIT / UNCOMMIT events are generated before
1346 // the compaction events.
1347 print_hrm_post_compaction();
1348
1349 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1350 if (hot_card_cache->use_cache()) {
1351 hot_card_cache->reset_card_counts();
1352 hot_card_cache->reset_hot_cache();
1353 }
1354
1355 // Rebuild remembered sets of all regions.
1356 uint n_workers =
1357 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1358 workers()->active_workers(),
1359 Threads::number_of_non_daemon_threads());
1360 workers()->set_active_workers(n_workers);
1361
1362 ParRebuildRSTask rebuild_rs_task(this);
1363 workers()->run_task(&rebuild_rs_task);
1364
1365 // Rebuild the strong code root lists for each region
1366 rebuild_strong_code_roots();
1367
1368 if (true) { // FIXME
1369 MetaspaceGC::compute_new_size();
1370 }
1371
1372 #ifdef TRACESPINNING
1373 ParallelTaskTerminator::print_termination_counts();
1374 #endif
1375
1376 // Discard all rset updates
1377 JavaThread::dirty_card_queue_set().abandon_logs();
1378 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1379
1380 _young_list->reset_sampled_info();
1381 // At this point there should be no regions in the
1382 // entire heap tagged as young.
1383 assert(check_young_list_empty(true /* check_heap */),
1384 "young list should be empty at this point");
1385
1386 // Update the number of full collections that have been completed.
1387 increment_old_marking_cycles_completed(false /* concurrent */);
1388
1389 _hrm.verify_optional();
1390 verify_region_sets_optional();
1391
1392 verify_after_gc();
1393
1394 // Clear the previous marking bitmap, if needed for bitmap verification.
1395 // Note we cannot do this when we clear the next marking bitmap in
1396 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1397 // objects marked during a full GC against the previous bitmap.
1398 // But we need to clear it before calling check_bitmaps below since
1399 // the full GC has compacted objects and updated TAMS but not updated
1400 // the prev bitmap.
1401 if (G1VerifyBitmaps) {
1402 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1403 }
1404 check_bitmaps("Full GC End");
1405
1406 // Start a new incremental collection set for the next pause
1407 assert(g1_policy()->collection_set() == NULL, "must be");
1408 g1_policy()->start_incremental_cset_building();
1409
1410 clear_cset_fast_test();
1411
1412 _allocator->init_mutator_alloc_region();
1413
1414 g1_policy()->record_full_collection_end();
1415
1416 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1417 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1418 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1419 // before any GC notifications are raised.
1420 g1mm()->update_sizes();
1421
1422 gc_epilogue(true);
1423 }
1424
1425 g1_policy()->print_detailed_heap_transition();
1426
1427 print_heap_after_gc();
1428 trace_heap_after_gc(gc_tracer);
1429
1430 post_full_gc_dump(gc_timer);
1431
1432 gc_timer->register_gc_end();
1433 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1434 }
1435
1436 return true;
1437 }
1438
1439 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1440 // do_collection() will return whether it succeeded in performing
1441 // the GC. Currently, there is no facility on the
1442 // do_full_collection() API to notify the caller than the collection
1443 // did not succeed (e.g., because it was locked out by the GC
1444 // locker). So, right now, we'll ignore the return value.
1445 bool dummy = do_collection(true, /* explicit_gc */
1446 clear_all_soft_refs,
1447 0 /* word_size */);
1448 }
1449
1450 // This code is mostly copied from TenuredGeneration.
1451 void
1452 G1CollectedHeap::
1453 resize_if_necessary_after_full_collection(size_t word_size) {
1454 // Include the current allocation, if any, and bytes that will be
1455 // pre-allocated to support collections, as "used".
1456 const size_t used_after_gc = used();
1457 const size_t capacity_after_gc = capacity();
1458 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1459
1460 // This is enforced in arguments.cpp.
1461 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1462 "otherwise the code below doesn't make sense");
1463
1464 // We don't have floating point command-line arguments
1465 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1466 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1467 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1468 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1469
1470 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1471 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1472
1473 // We have to be careful here as these two calculations can overflow
1474 // 32-bit size_t's.
1475 double used_after_gc_d = (double) used_after_gc;
1476 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1477 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1478
1479 // Let's make sure that they are both under the max heap size, which
1480 // by default will make them fit into a size_t.
1481 double desired_capacity_upper_bound = (double) max_heap_size;
1482 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1483 desired_capacity_upper_bound);
1484 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1485 desired_capacity_upper_bound);
1486
1487 // We can now safely turn them into size_t's.
1488 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1489 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1490
1491 // This assert only makes sense here, before we adjust them
1492 // with respect to the min and max heap size.
1493 assert(minimum_desired_capacity <= maximum_desired_capacity,
1494 "minimum_desired_capacity = " SIZE_FORMAT ", "
1495 "maximum_desired_capacity = " SIZE_FORMAT,
1496 minimum_desired_capacity, maximum_desired_capacity);
1497
1498 // Should not be greater than the heap max size. No need to adjust
1499 // it with respect to the heap min size as it's a lower bound (i.e.,
1500 // we'll try to make the capacity larger than it, not smaller).
1501 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1502 // Should not be less than the heap min size. No need to adjust it
1503 // with respect to the heap max size as it's an upper bound (i.e.,
1504 // we'll try to make the capacity smaller than it, not greater).
1505 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1506
1507 if (capacity_after_gc < minimum_desired_capacity) {
1508 // Don't expand unless it's significant
1509 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1510
1511 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1512 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1513 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1514
1515 expand(expand_bytes);
1516
1517 // No expansion, now see if we want to shrink
1518 } else if (capacity_after_gc > maximum_desired_capacity) {
1519 // Capacity too large, compute shrinking size
1520 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1521
1522 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1523 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1524 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1525
1526 shrink(shrink_bytes);
1527 }
1528 }
1529
1530 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1531 AllocationContext_t context,
1532 bool do_gc,
1533 bool clear_all_soft_refs,
1534 bool expect_null_mutator_alloc_region,
1535 bool* gc_succeeded) {
1536 *gc_succeeded = true;
1537 // Let's attempt the allocation first.
1538 HeapWord* result =
1539 attempt_allocation_at_safepoint(word_size,
1540 context,
1541 expect_null_mutator_alloc_region);
1542 if (result != NULL) {
1543 assert(*gc_succeeded, "sanity");
1544 return result;
1545 }
1546
1547 // In a G1 heap, we're supposed to keep allocation from failing by
1548 // incremental pauses. Therefore, at least for now, we'll favor
1549 // expansion over collection. (This might change in the future if we can
1550 // do something smarter than full collection to satisfy a failed alloc.)
1551 result = expand_and_allocate(word_size, context);
1552 if (result != NULL) {
1553 assert(*gc_succeeded, "sanity");
1554 return result;
1555 }
1556
1557 if (do_gc) {
1558 // Expansion didn't work, we'll try to do a Full GC.
1559 *gc_succeeded = do_collection(false, /* explicit_gc */
1560 clear_all_soft_refs,
1561 word_size);
1562 }
1563
1564 return NULL;
1565 }
1566
1567 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1568 AllocationContext_t context,
1569 bool* succeeded) {
1570 assert_at_safepoint(true /* should_be_vm_thread */);
1571
1572 // Attempts to allocate followed by Full GC.
1573 HeapWord* result =
1574 satisfy_failed_allocation_helper(word_size,
1575 context,
1576 true, /* do_gc */
1577 false, /* clear_all_soft_refs */
1578 false, /* expect_null_mutator_alloc_region */
1579 succeeded);
1580
1581 if (result != NULL || !*succeeded) {
1582 return result;
1583 }
1584
1585 // Attempts to allocate followed by Full GC that will collect all soft references.
1586 result = satisfy_failed_allocation_helper(word_size,
1587 context,
1588 true, /* do_gc */
1589 true, /* clear_all_soft_refs */
1590 true, /* expect_null_mutator_alloc_region */
1591 succeeded);
1592
1593 if (result != NULL || !*succeeded) {
1594 return result;
1595 }
1596
1597 // Attempts to allocate, no GC
1598 result = satisfy_failed_allocation_helper(word_size,
1599 context,
1600 false, /* do_gc */
1601 false, /* clear_all_soft_refs */
1602 true, /* expect_null_mutator_alloc_region */
1603 succeeded);
1604
1605 if (result != NULL) {
1606 assert(*succeeded, "sanity");
1607 return result;
1608 }
1609
1610 assert(!collector_policy()->should_clear_all_soft_refs(),
1611 "Flag should have been handled and cleared prior to this point");
1612
1613 // What else? We might try synchronous finalization later. If the total
1614 // space available is large enough for the allocation, then a more
1615 // complete compaction phase than we've tried so far might be
1616 // appropriate.
1617 assert(*succeeded, "sanity");
1618 return NULL;
1619 }
1620
1621 // Attempting to expand the heap sufficiently
1622 // to support an allocation of the given "word_size". If
1623 // successful, perform the allocation and return the address of the
1624 // allocated block, or else "NULL".
1625
1626 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1627 assert_at_safepoint(true /* should_be_vm_thread */);
1628
1629 verify_region_sets_optional();
1630
1631 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1632 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1633 word_size * HeapWordSize);
1634
1635
1636 if (expand(expand_bytes)) {
1637 _hrm.verify_optional();
1638 verify_region_sets_optional();
1639 return attempt_allocation_at_safepoint(word_size,
1640 context,
1641 false /* expect_null_mutator_alloc_region */);
1642 }
1643 return NULL;
1644 }
1645
1646 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1647 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1648 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1649 HeapRegion::GrainBytes);
1650
1651 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1652 expand_bytes, aligned_expand_bytes);
1653
1654 if (is_maximal_no_gc()) {
1655 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1656 return false;
1657 }
1658
1659 double expand_heap_start_time_sec = os::elapsedTime();
1660 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1661 assert(regions_to_expand > 0, "Must expand by at least one region");
1662
1663 uint expanded_by = _hrm.expand_by(regions_to_expand);
1664 if (expand_time_ms != NULL) {
1665 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1666 }
1667
1668 if (expanded_by > 0) {
1669 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1670 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1671 g1_policy()->record_new_heap_size(num_regions());
1672 } else {
1673 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1674
1675 // The expansion of the virtual storage space was unsuccessful.
1676 // Let's see if it was because we ran out of swap.
1677 if (G1ExitOnExpansionFailure &&
1678 _hrm.available() >= regions_to_expand) {
1679 // We had head room...
1680 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1681 }
1682 }
1683 return regions_to_expand > 0;
1684 }
1685
1686 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1687 size_t aligned_shrink_bytes =
1688 ReservedSpace::page_align_size_down(shrink_bytes);
1689 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1690 HeapRegion::GrainBytes);
1691 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1692
1693 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1694 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1695
1696
1697 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",
1698 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1699 if (num_regions_removed > 0) {
1700 g1_policy()->record_new_heap_size(num_regions());
1701 } else {
1702 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1703 }
1704 }
1705
1706 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1707 verify_region_sets_optional();
1708
1709 // We should only reach here at the end of a Full GC which means we
1710 // should not not be holding to any GC alloc regions. The method
1711 // below will make sure of that and do any remaining clean up.
1712 _allocator->abandon_gc_alloc_regions();
1713
1714 // Instead of tearing down / rebuilding the free lists here, we
1715 // could instead use the remove_all_pending() method on free_list to
1716 // remove only the ones that we need to remove.
1717 tear_down_region_sets(true /* free_list_only */);
1718 shrink_helper(shrink_bytes);
1719 rebuild_region_sets(true /* free_list_only */);
1720
1721 _hrm.verify_optional();
1722 verify_region_sets_optional();
1723 }
1724
1725 // Public methods.
1726
1727 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1728 CollectedHeap(),
1729 _g1_policy(policy_),
1730 _dirty_card_queue_set(false),
1731 _is_alive_closure_cm(this),
1732 _is_alive_closure_stw(this),
1733 _ref_processor_cm(NULL),
1734 _ref_processor_stw(NULL),
1735 _bot_shared(NULL),
1736 _cg1r(NULL),
1737 _g1mm(NULL),
1738 _refine_cte_cl(NULL),
1739 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1740 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1741 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1742 _humongous_reclaim_candidates(),
1743 _has_humongous_reclaim_candidates(false),
1744 _archive_allocator(NULL),
1745 _free_regions_coming(false),
1746 _young_list(new YoungList(this)),
1747 _gc_time_stamp(0),
1748 _summary_bytes_used(0),
1749 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1750 _old_evac_stats(OldPLABSize, PLABWeight),
1751 _expand_heap_after_alloc_failure(true),
1752 _old_marking_cycles_started(0),
1753 _old_marking_cycles_completed(0),
1754 _heap_summary_sent(false),
1755 _in_cset_fast_test(),
1756 _dirty_cards_region_list(NULL),
1757 _worker_cset_start_region(NULL),
1758 _worker_cset_start_region_time_stamp(NULL),
1759 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1760 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1761 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1762 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1763
1764 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1765 /* are_GC_task_threads */true,
1766 /* are_ConcurrentGC_threads */false);
1767 _workers->initialize_workers();
1768
1769 _allocator = G1Allocator::create_allocator(this);
1770 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1771
1772 // Override the default _filler_array_max_size so that no humongous filler
1773 // objects are created.
1774 _filler_array_max_size = _humongous_object_threshold_in_words;
1775
1776 uint n_queues = ParallelGCThreads;
1777 _task_queues = new RefToScanQueueSet(n_queues);
1778
1779 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1780 assert(n_rem_sets > 0, "Invariant.");
1781
1782 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1783 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1784 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1785
1786 for (uint i = 0; i < n_queues; i++) {
1787 RefToScanQueue* q = new RefToScanQueue();
1788 q->initialize();
1789 _task_queues->register_queue(i, q);
1790 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1791 }
1792 clear_cset_start_regions();
1793
1794 // Initialize the G1EvacuationFailureALot counters and flags.
1795 NOT_PRODUCT(reset_evacuation_should_fail();)
1796
1797 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1798 }
1799
1800 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1801 size_t size,
1802 size_t translation_factor) {
1803 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1804 // Allocate a new reserved space, preferring to use large pages.
1805 ReservedSpace rs(size, preferred_page_size);
1806 G1RegionToSpaceMapper* result =
1807 G1RegionToSpaceMapper::create_mapper(rs,
1808 size,
1809 rs.alignment(),
1810 HeapRegion::GrainBytes,
1811 translation_factor,
1812 mtGC);
1813 if (TracePageSizes) {
1814 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1815 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1816 }
1817 return result;
1818 }
1819
1820 jint G1CollectedHeap::initialize() {
1821 CollectedHeap::pre_initialize();
1822 os::enable_vtime();
1823
1824 // Necessary to satisfy locking discipline assertions.
1825
1826 MutexLocker x(Heap_lock);
1827
1828 // While there are no constraints in the GC code that HeapWordSize
1829 // be any particular value, there are multiple other areas in the
1830 // system which believe this to be true (e.g. oop->object_size in some
1831 // cases incorrectly returns the size in wordSize units rather than
1832 // HeapWordSize).
1833 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1834
1835 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1836 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1837 size_t heap_alignment = collector_policy()->heap_alignment();
1838
1839 // Ensure that the sizes are properly aligned.
1840 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1841 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1842 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1843
1844 _refine_cte_cl = new RefineCardTableEntryClosure();
1845
1846 jint ecode = JNI_OK;
1847 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1848 if (_cg1r == NULL) {
1849 return ecode;
1850 }
1851
1852 // Reserve the maximum.
1853
1854 // When compressed oops are enabled, the preferred heap base
1855 // is calculated by subtracting the requested size from the
1856 // 32Gb boundary and using the result as the base address for
1857 // heap reservation. If the requested size is not aligned to
1858 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1859 // into the ReservedHeapSpace constructor) then the actual
1860 // base of the reserved heap may end up differing from the
1861 // address that was requested (i.e. the preferred heap base).
1862 // If this happens then we could end up using a non-optimal
1863 // compressed oops mode.
1864
1865 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1866 heap_alignment);
1867
1868 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1869
1870 // Create the barrier set for the entire reserved region.
1871 G1SATBCardTableLoggingModRefBS* bs
1872 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1873 bs->initialize();
1874 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1875 set_barrier_set(bs);
1876
1877 // Also create a G1 rem set.
1878 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1879
1880 // Carve out the G1 part of the heap.
1881
1882 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1883 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1884 G1RegionToSpaceMapper* heap_storage =
1885 G1RegionToSpaceMapper::create_mapper(g1_rs,
1886 g1_rs.size(),
1887 page_size,
1888 HeapRegion::GrainBytes,
1889 1,
1890 mtJavaHeap);
1891 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1892 max_byte_size, page_size,
1893 heap_rs.base(),
1894 heap_rs.size());
1895 heap_storage->set_mapping_changed_listener(&_listener);
1896
1897 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1898 G1RegionToSpaceMapper* bot_storage =
1899 create_aux_memory_mapper("Block offset table",
1900 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1901 G1BlockOffsetSharedArray::heap_map_factor());
1902
1903 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1904 G1RegionToSpaceMapper* cardtable_storage =
1905 create_aux_memory_mapper("Card table",
1906 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1907 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1908
1909 G1RegionToSpaceMapper* card_counts_storage =
1910 create_aux_memory_mapper("Card counts table",
1911 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1912 G1CardCounts::heap_map_factor());
1913
1914 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1915 G1RegionToSpaceMapper* prev_bitmap_storage =
1916 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1917 G1RegionToSpaceMapper* next_bitmap_storage =
1918 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1919
1920 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1921 g1_barrier_set()->initialize(cardtable_storage);
1922 // Do later initialization work for concurrent refinement.
1923 _cg1r->init(card_counts_storage);
1924
1925 // 6843694 - ensure that the maximum region index can fit
1926 // in the remembered set structures.
1927 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1928 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1929
1930 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1931 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1932 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1933 "too many cards per region");
1934
1935 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1936
1937 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1938
1939 {
1940 HeapWord* start = _hrm.reserved().start();
1941 HeapWord* end = _hrm.reserved().end();
1942 size_t granularity = HeapRegion::GrainBytes;
1943
1944 _in_cset_fast_test.initialize(start, end, granularity);
1945 _humongous_reclaim_candidates.initialize(start, end, granularity);
1946 }
1947
1948 // Create the ConcurrentMark data structure and thread.
1949 // (Must do this late, so that "max_regions" is defined.)
1950 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1951 if (_cm == NULL || !_cm->completed_initialization()) {
1952 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1953 return JNI_ENOMEM;
1954 }
1955 _cmThread = _cm->cmThread();
1956
1957 // Initialize the from_card cache structure of HeapRegionRemSet.
1958 HeapRegionRemSet::init_heap(max_regions());
1959
1960 // Now expand into the initial heap size.
1961 if (!expand(init_byte_size)) {
1962 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1963 return JNI_ENOMEM;
1964 }
1965
1966 // Perform any initialization actions delegated to the policy.
1967 g1_policy()->init();
1968
1969 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1970 SATB_Q_FL_lock,
1971 G1SATBProcessCompletedThreshold,
1972 Shared_SATB_Q_lock);
1973
1974 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1975 DirtyCardQ_CBL_mon,
1976 DirtyCardQ_FL_lock,
1977 concurrent_g1_refine()->yellow_zone(),
1978 concurrent_g1_refine()->red_zone(),
1979 Shared_DirtyCardQ_lock);
1980
1981 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1982 DirtyCardQ_CBL_mon,
1983 DirtyCardQ_FL_lock,
1984 -1, // never trigger processing
1985 -1, // no limit on length
1986 Shared_DirtyCardQ_lock,
1987 &JavaThread::dirty_card_queue_set());
1988
1989 // Here we allocate the dummy HeapRegion that is required by the
1990 // G1AllocRegion class.
1991 HeapRegion* dummy_region = _hrm.get_dummy_region();
1992
1993 // We'll re-use the same region whether the alloc region will
1994 // require BOT updates or not and, if it doesn't, then a non-young
1995 // region will complain that it cannot support allocations without
1996 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1997 dummy_region->set_eden();
1998 // Make sure it's full.
1999 dummy_region->set_top(dummy_region->end());
2000 G1AllocRegion::setup(this, dummy_region);
2001
2002 _allocator->init_mutator_alloc_region();
2003
2004 // Do create of the monitoring and management support so that
2005 // values in the heap have been properly initialized.
2006 _g1mm = new G1MonitoringSupport(this);
2007
2008 G1StringDedup::initialize();
2009
2010 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2011 for (uint i = 0; i < ParallelGCThreads; i++) {
2012 new (&_preserved_objs[i]) OopAndMarkOopStack();
2013 }
2014
2015 return JNI_OK;
2016 }
2017
2018 void G1CollectedHeap::stop() {
2019 // Stop all concurrent threads. We do this to make sure these threads
2020 // do not continue to execute and access resources (e.g. logging)
2021 // that are destroyed during shutdown.
2022 _cg1r->stop();
2023 _cmThread->stop();
2024 if (G1StringDedup::is_enabled()) {
2025 G1StringDedup::stop();
2026 }
2027 }
2028
2029 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2030 return HeapRegion::max_region_size();
2031 }
2032
2033 void G1CollectedHeap::post_initialize() {
2034 CollectedHeap::post_initialize();
2035 ref_processing_init();
2036 }
2037
2038 void G1CollectedHeap::ref_processing_init() {
2039 // Reference processing in G1 currently works as follows:
2040 //
2041 // * There are two reference processor instances. One is
2042 // used to record and process discovered references
2043 // during concurrent marking; the other is used to
2044 // record and process references during STW pauses
2045 // (both full and incremental).
2046 // * Both ref processors need to 'span' the entire heap as
2047 // the regions in the collection set may be dotted around.
2048 //
2049 // * For the concurrent marking ref processor:
2050 // * Reference discovery is enabled at initial marking.
2051 // * Reference discovery is disabled and the discovered
2052 // references processed etc during remarking.
2053 // * Reference discovery is MT (see below).
2054 // * Reference discovery requires a barrier (see below).
2055 // * Reference processing may or may not be MT
2056 // (depending on the value of ParallelRefProcEnabled
2057 // and ParallelGCThreads).
2058 // * A full GC disables reference discovery by the CM
2059 // ref processor and abandons any entries on it's
2060 // discovered lists.
2061 //
2062 // * For the STW processor:
2063 // * Non MT discovery is enabled at the start of a full GC.
2064 // * Processing and enqueueing during a full GC is non-MT.
2065 // * During a full GC, references are processed after marking.
2066 //
2067 // * Discovery (may or may not be MT) is enabled at the start
2068 // of an incremental evacuation pause.
2069 // * References are processed near the end of a STW evacuation pause.
2070 // * For both types of GC:
2071 // * Discovery is atomic - i.e. not concurrent.
2072 // * Reference discovery will not need a barrier.
2073
2074 MemRegion mr = reserved_region();
2075
2076 // Concurrent Mark ref processor
2077 _ref_processor_cm =
2078 new ReferenceProcessor(mr, // span
2079 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2080 // mt processing
2081 ParallelGCThreads,
2082 // degree of mt processing
2083 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2084 // mt discovery
2085 MAX2(ParallelGCThreads, ConcGCThreads),
2086 // degree of mt discovery
2087 false,
2088 // Reference discovery is not atomic
2089 &_is_alive_closure_cm);
2090 // is alive closure
2091 // (for efficiency/performance)
2092
2093 // STW ref processor
2094 _ref_processor_stw =
2095 new ReferenceProcessor(mr, // span
2096 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2097 // mt processing
2098 ParallelGCThreads,
2099 // degree of mt processing
2100 (ParallelGCThreads > 1),
2101 // mt discovery
2102 ParallelGCThreads,
2103 // degree of mt discovery
2104 true,
2105 // Reference discovery is atomic
2106 &_is_alive_closure_stw);
2107 // is alive closure
2108 // (for efficiency/performance)
2109 }
2110
2111 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2112 return g1_policy();
2113 }
2114
2115 size_t G1CollectedHeap::capacity() const {
2116 return _hrm.length() * HeapRegion::GrainBytes;
2117 }
2118
2119 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2120 hr->reset_gc_time_stamp();
2121 }
2122
2123 #ifndef PRODUCT
2124
2125 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2126 private:
2127 unsigned _gc_time_stamp;
2128 bool _failures;
2129
2130 public:
2131 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2132 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2133
2134 virtual bool doHeapRegion(HeapRegion* hr) {
2135 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2136 if (_gc_time_stamp != region_gc_time_stamp) {
2137 log_info(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2138 region_gc_time_stamp, _gc_time_stamp);
2139 _failures = true;
2140 }
2141 return false;
2142 }
2143
2144 bool failures() { return _failures; }
2145 };
2146
2147 void G1CollectedHeap::check_gc_time_stamps() {
2148 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2149 heap_region_iterate(&cl);
2150 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2151 }
2152 #endif // PRODUCT
2153
2154 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2155 _cg1r->hot_card_cache()->drain(cl, worker_i);
2156 }
2157
2158 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2159 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2160 size_t n_completed_buffers = 0;
2161 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2162 n_completed_buffers++;
2163 }
2164 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2165 dcqs.clear_n_completed_buffers();
2166 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2167 }
2168
2169 // Computes the sum of the storage used by the various regions.
2170 size_t G1CollectedHeap::used() const {
2171 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2172 if (_archive_allocator != NULL) {
2173 result += _archive_allocator->used();
2174 }
2175 return result;
2176 }
2177
2178 size_t G1CollectedHeap::used_unlocked() const {
2179 return _summary_bytes_used;
2180 }
2181
2182 class SumUsedClosure: public HeapRegionClosure {
2183 size_t _used;
2184 public:
2185 SumUsedClosure() : _used(0) {}
2186 bool doHeapRegion(HeapRegion* r) {
2187 _used += r->used();
2188 return false;
2189 }
2190 size_t result() { return _used; }
2191 };
2192
2193 size_t G1CollectedHeap::recalculate_used() const {
2194 double recalculate_used_start = os::elapsedTime();
2195
2196 SumUsedClosure blk;
2197 heap_region_iterate(&blk);
2198
2199 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2200 return blk.result();
2201 }
2202
2203 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2204 switch (cause) {
2205 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2206 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2207 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2208 case GCCause::_g1_humongous_allocation: return true;
2209 case GCCause::_update_allocation_context_stats_inc: return true;
2210 case GCCause::_wb_conc_mark: return true;
2211 default: return false;
2212 }
2213 }
2214
2215 #ifndef PRODUCT
2216 void G1CollectedHeap::allocate_dummy_regions() {
2217 // Let's fill up most of the region
2218 size_t word_size = HeapRegion::GrainWords - 1024;
2219 // And as a result the region we'll allocate will be humongous.
2220 guarantee(is_humongous(word_size), "sanity");
2221
2222 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2223 // Let's use the existing mechanism for the allocation
2224 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2225 AllocationContext::system());
2226 if (dummy_obj != NULL) {
2227 MemRegion mr(dummy_obj, word_size);
2228 CollectedHeap::fill_with_object(mr);
2229 } else {
2230 // If we can't allocate once, we probably cannot allocate
2231 // again. Let's get out of the loop.
2232 break;
2233 }
2234 }
2235 }
2236 #endif // !PRODUCT
2237
2238 void G1CollectedHeap::increment_old_marking_cycles_started() {
2239 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2240 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2241 "Wrong marking cycle count (started: %d, completed: %d)",
2242 _old_marking_cycles_started, _old_marking_cycles_completed);
2243
2244 _old_marking_cycles_started++;
2245 }
2246
2247 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2248 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2249
2250 // We assume that if concurrent == true, then the caller is a
2251 // concurrent thread that was joined the Suspendible Thread
2252 // Set. If there's ever a cheap way to check this, we should add an
2253 // assert here.
2254
2255 // Given that this method is called at the end of a Full GC or of a
2256 // concurrent cycle, and those can be nested (i.e., a Full GC can
2257 // interrupt a concurrent cycle), the number of full collections
2258 // completed should be either one (in the case where there was no
2259 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2260 // behind the number of full collections started.
2261
2262 // This is the case for the inner caller, i.e. a Full GC.
2263 assert(concurrent ||
2264 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2265 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2266 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2267 "is inconsistent with _old_marking_cycles_completed = %u",
2268 _old_marking_cycles_started, _old_marking_cycles_completed);
2269
2270 // This is the case for the outer caller, i.e. the concurrent cycle.
2271 assert(!concurrent ||
2272 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2273 "for outer caller (concurrent cycle): "
2274 "_old_marking_cycles_started = %u "
2275 "is inconsistent with _old_marking_cycles_completed = %u",
2276 _old_marking_cycles_started, _old_marking_cycles_completed);
2277
2278 _old_marking_cycles_completed += 1;
2279
2280 // We need to clear the "in_progress" flag in the CM thread before
2281 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2282 // is set) so that if a waiter requests another System.gc() it doesn't
2283 // incorrectly see that a marking cycle is still in progress.
2284 if (concurrent) {
2285 _cmThread->set_idle();
2286 }
2287
2288 // This notify_all() will ensure that a thread that called
2289 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2290 // and it's waiting for a full GC to finish will be woken up. It is
2291 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2292 FullGCCount_lock->notify_all();
2293 }
2294
2295 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2296 GCIdMarkAndRestore conc_gc_id_mark;
2297 collector_state()->set_concurrent_cycle_started(true);
2298 _gc_timer_cm->register_gc_start(start_time);
2299
2300 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2301 trace_heap_before_gc(_gc_tracer_cm);
2302 _cmThread->set_gc_id(GCId::current());
2303 }
2304
2305 void G1CollectedHeap::register_concurrent_cycle_end() {
2306 if (collector_state()->concurrent_cycle_started()) {
2307 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2308 if (_cm->has_aborted()) {
2309 _gc_tracer_cm->report_concurrent_mode_failure();
2310 }
2311
2312 _gc_timer_cm->register_gc_end();
2313 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2314
2315 // Clear state variables to prepare for the next concurrent cycle.
2316 collector_state()->set_concurrent_cycle_started(false);
2317 _heap_summary_sent = false;
2318 }
2319 }
2320
2321 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2322 if (collector_state()->concurrent_cycle_started()) {
2323 // This function can be called when:
2324 // the cleanup pause is run
2325 // the concurrent cycle is aborted before the cleanup pause.
2326 // the concurrent cycle is aborted after the cleanup pause,
2327 // but before the concurrent cycle end has been registered.
2328 // Make sure that we only send the heap information once.
2329 if (!_heap_summary_sent) {
2330 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2331 trace_heap_after_gc(_gc_tracer_cm);
2332 _heap_summary_sent = true;
2333 }
2334 }
2335 }
2336
2337 void G1CollectedHeap::collect(GCCause::Cause cause) {
2338 assert_heap_not_locked();
2339
2340 uint gc_count_before;
2341 uint old_marking_count_before;
2342 uint full_gc_count_before;
2343 bool retry_gc;
2344
2345 do {
2346 retry_gc = false;
2347
2348 {
2349 MutexLocker ml(Heap_lock);
2350
2351 // Read the GC count while holding the Heap_lock
2352 gc_count_before = total_collections();
2353 full_gc_count_before = total_full_collections();
2354 old_marking_count_before = _old_marking_cycles_started;
2355 }
2356
2357 if (should_do_concurrent_full_gc(cause)) {
2358 // Schedule an initial-mark evacuation pause that will start a
2359 // concurrent cycle. We're setting word_size to 0 which means that
2360 // we are not requesting a post-GC allocation.
2361 VM_G1IncCollectionPause op(gc_count_before,
2362 0, /* word_size */
2363 true, /* should_initiate_conc_mark */
2364 g1_policy()->max_pause_time_ms(),
2365 cause);
2366 op.set_allocation_context(AllocationContext::current());
2367
2368 VMThread::execute(&op);
2369 if (!op.pause_succeeded()) {
2370 if (old_marking_count_before == _old_marking_cycles_started) {
2371 retry_gc = op.should_retry_gc();
2372 } else {
2373 // A Full GC happened while we were trying to schedule the
2374 // initial-mark GC. No point in starting a new cycle given
2375 // that the whole heap was collected anyway.
2376 }
2377
2378 if (retry_gc) {
2379 if (GC_locker::is_active_and_needs_gc()) {
2380 GC_locker::stall_until_clear();
2381 }
2382 }
2383 }
2384 } else {
2385 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2386 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2387
2388 // Schedule a standard evacuation pause. We're setting word_size
2389 // to 0 which means that we are not requesting a post-GC allocation.
2390 VM_G1IncCollectionPause op(gc_count_before,
2391 0, /* word_size */
2392 false, /* should_initiate_conc_mark */
2393 g1_policy()->max_pause_time_ms(),
2394 cause);
2395 VMThread::execute(&op);
2396 } else {
2397 // Schedule a Full GC.
2398 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2399 VMThread::execute(&op);
2400 }
2401 }
2402 } while (retry_gc);
2403 }
2404
2405 bool G1CollectedHeap::is_in(const void* p) const {
2406 if (_hrm.reserved().contains(p)) {
2407 // Given that we know that p is in the reserved space,
2408 // heap_region_containing() should successfully
2409 // return the containing region.
2410 HeapRegion* hr = heap_region_containing(p);
2411 return hr->is_in(p);
2412 } else {
2413 return false;
2414 }
2415 }
2416
2417 #ifdef ASSERT
2418 bool G1CollectedHeap::is_in_exact(const void* p) const {
2419 bool contains = reserved_region().contains(p);
2420 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2421 if (contains && available) {
2422 return true;
2423 } else {
2424 return false;
2425 }
2426 }
2427 #endif
2428
2429 bool G1CollectedHeap::obj_in_cs(oop obj) {
2430 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2431 return r != NULL && r->in_collection_set();
2432 }
2433
2434 // Iteration functions.
2435
2436 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2437
2438 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2439 ExtendedOopClosure* _cl;
2440 public:
2441 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2442 bool doHeapRegion(HeapRegion* r) {
2443 if (!r->is_continues_humongous()) {
2444 r->oop_iterate(_cl);
2445 }
2446 return false;
2447 }
2448 };
2449
2450 // Iterates an ObjectClosure over all objects within a HeapRegion.
2451
2452 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2453 ObjectClosure* _cl;
2454 public:
2455 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2456 bool doHeapRegion(HeapRegion* r) {
2457 if (!r->is_continues_humongous()) {
2458 r->object_iterate(_cl);
2459 }
2460 return false;
2461 }
2462 };
2463
2464 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2465 IterateObjectClosureRegionClosure blk(cl);
2466 heap_region_iterate(&blk);
2467 }
2468
2469 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2470 _hrm.iterate(cl);
2471 }
2472
2473 void
2474 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2475 uint worker_id,
2476 HeapRegionClaimer *hrclaimer,
2477 bool concurrent) const {
2478 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2479 }
2480
2481 // Clear the cached CSet starting regions and (more importantly)
2482 // the time stamps. Called when we reset the GC time stamp.
2483 void G1CollectedHeap::clear_cset_start_regions() {
2484 assert(_worker_cset_start_region != NULL, "sanity");
2485 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2486
2487 for (uint i = 0; i < ParallelGCThreads; i++) {
2488 _worker_cset_start_region[i] = NULL;
2489 _worker_cset_start_region_time_stamp[i] = 0;
2490 }
2491 }
2492
2493 // Given the id of a worker, obtain or calculate a suitable
2494 // starting region for iterating over the current collection set.
2495 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2496 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2497
2498 HeapRegion* result = NULL;
2499 unsigned gc_time_stamp = get_gc_time_stamp();
2500
2501 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2502 // Cached starting region for current worker was set
2503 // during the current pause - so it's valid.
2504 // Note: the cached starting heap region may be NULL
2505 // (when the collection set is empty).
2506 result = _worker_cset_start_region[worker_i];
2507 assert(result == NULL || result->in_collection_set(), "sanity");
2508 return result;
2509 }
2510
2511 // The cached entry was not valid so let's calculate
2512 // a suitable starting heap region for this worker.
2513
2514 // We want the parallel threads to start their collection
2515 // set iteration at different collection set regions to
2516 // avoid contention.
2517 // If we have:
2518 // n collection set regions
2519 // p threads
2520 // Then thread t will start at region floor ((t * n) / p)
2521
2522 result = g1_policy()->collection_set();
2523 uint cs_size = g1_policy()->cset_region_length();
2524 uint active_workers = workers()->active_workers();
2525
2526 uint end_ind = (cs_size * worker_i) / active_workers;
2527 uint start_ind = 0;
2528
2529 if (worker_i > 0 &&
2530 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2531 // Previous workers starting region is valid
2532 // so let's iterate from there
2533 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2534 result = _worker_cset_start_region[worker_i - 1];
2535 }
2536
2537 for (uint i = start_ind; i < end_ind; i++) {
2538 result = result->next_in_collection_set();
2539 }
2540
2541 // Note: the calculated starting heap region may be NULL
2542 // (when the collection set is empty).
2543 assert(result == NULL || result->in_collection_set(), "sanity");
2544 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2545 "should be updated only once per pause");
2546 _worker_cset_start_region[worker_i] = result;
2547 OrderAccess::storestore();
2548 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2549 return result;
2550 }
2551
2552 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2553 HeapRegion* r = g1_policy()->collection_set();
2554 while (r != NULL) {
2555 HeapRegion* next = r->next_in_collection_set();
2556 if (cl->doHeapRegion(r)) {
2557 cl->incomplete();
2558 return;
2559 }
2560 r = next;
2561 }
2562 }
2563
2564 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2565 HeapRegionClosure *cl) {
2566 if (r == NULL) {
2567 // The CSet is empty so there's nothing to do.
2568 return;
2569 }
2570
2571 assert(r->in_collection_set(),
2572 "Start region must be a member of the collection set.");
2573 HeapRegion* cur = r;
2574 while (cur != NULL) {
2575 HeapRegion* next = cur->next_in_collection_set();
2576 if (cl->doHeapRegion(cur) && false) {
2577 cl->incomplete();
2578 return;
2579 }
2580 cur = next;
2581 }
2582 cur = g1_policy()->collection_set();
2583 while (cur != r) {
2584 HeapRegion* next = cur->next_in_collection_set();
2585 if (cl->doHeapRegion(cur) && false) {
2586 cl->incomplete();
2587 return;
2588 }
2589 cur = next;
2590 }
2591 }
2592
2593 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2594 HeapRegion* result = _hrm.next_region_in_heap(from);
2595 while (result != NULL && result->is_pinned()) {
2596 result = _hrm.next_region_in_heap(result);
2597 }
2598 return result;
2599 }
2600
2601 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2602 HeapRegion* hr = heap_region_containing(addr);
2603 return hr->block_start(addr);
2604 }
2605
2606 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2607 HeapRegion* hr = heap_region_containing(addr);
2608 return hr->block_size(addr);
2609 }
2610
2611 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2612 HeapRegion* hr = heap_region_containing(addr);
2613 return hr->block_is_obj(addr);
2614 }
2615
2616 bool G1CollectedHeap::supports_tlab_allocation() const {
2617 return true;
2618 }
2619
2620 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2621 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2622 }
2623
2624 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2625 return young_list()->eden_used_bytes();
2626 }
2627
2628 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2629 // must be equal to the humongous object limit.
2630 size_t G1CollectedHeap::max_tlab_size() const {
2631 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2632 }
2633
2634 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2635 AllocationContext_t context = AllocationContext::current();
2636 return _allocator->unsafe_max_tlab_alloc(context);
2637 }
2638
2639 size_t G1CollectedHeap::max_capacity() const {
2640 return _hrm.reserved().byte_size();
2641 }
2642
2643 jlong G1CollectedHeap::millis_since_last_gc() {
2644 // assert(false, "NYI");
2645 return 0;
2646 }
2647
2648 void G1CollectedHeap::prepare_for_verify() {
2649 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2650 ensure_parsability(false);
2651 }
2652 g1_rem_set()->prepare_for_verify();
2653 }
2654
2655 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2656 VerifyOption vo) {
2657 switch (vo) {
2658 case VerifyOption_G1UsePrevMarking:
2659 return hr->obj_allocated_since_prev_marking(obj);
2660 case VerifyOption_G1UseNextMarking:
2661 return hr->obj_allocated_since_next_marking(obj);
2662 case VerifyOption_G1UseMarkWord:
2663 return false;
2664 default:
2665 ShouldNotReachHere();
2666 }
2667 return false; // keep some compilers happy
2668 }
2669
2670 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2671 switch (vo) {
2672 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2673 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2674 case VerifyOption_G1UseMarkWord: return NULL;
2675 default: ShouldNotReachHere();
2676 }
2677 return NULL; // keep some compilers happy
2678 }
2679
2680 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2681 switch (vo) {
2682 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2683 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2684 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2685 default: ShouldNotReachHere();
2686 }
2687 return false; // keep some compilers happy
2688 }
2689
2690 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2691 switch (vo) {
2692 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2693 case VerifyOption_G1UseNextMarking: return "NTAMS";
2694 case VerifyOption_G1UseMarkWord: return "NONE";
2695 default: ShouldNotReachHere();
2696 }
2697 return NULL; // keep some compilers happy
2698 }
2699
2700 class VerifyRootsClosure: public OopClosure {
2701 private:
2702 G1CollectedHeap* _g1h;
2703 VerifyOption _vo;
2704 bool _failures;
2705 public:
2706 // _vo == UsePrevMarking -> use "prev" marking information,
2707 // _vo == UseNextMarking -> use "next" marking information,
2708 // _vo == UseMarkWord -> use mark word from object header.
2709 VerifyRootsClosure(VerifyOption vo) :
2710 _g1h(G1CollectedHeap::heap()),
2711 _vo(vo),
2712 _failures(false) { }
2713
2714 bool failures() { return _failures; }
2715
2716 template <class T> void do_oop_nv(T* p) {
2717 T heap_oop = oopDesc::load_heap_oop(p);
2718 if (!oopDesc::is_null(heap_oop)) {
2719 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2720 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2721 LogHandle(gc, verify) log;
2722 log.info("Root location " PTR_FORMAT " points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2723 if (_vo == VerifyOption_G1UseMarkWord) {
2724 log.info(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2725 }
2726 ResourceMark rm;
2727 obj->print_on(log.info_stream());
2728 _failures = true;
2729 }
2730 }
2731 }
2732
2733 void do_oop(oop* p) { do_oop_nv(p); }
2734 void do_oop(narrowOop* p) { do_oop_nv(p); }
2735 };
2736
2737 class G1VerifyCodeRootOopClosure: public OopClosure {
2738 G1CollectedHeap* _g1h;
2739 OopClosure* _root_cl;
2740 nmethod* _nm;
2741 VerifyOption _vo;
2742 bool _failures;
2743
2744 template <class T> void do_oop_work(T* p) {
2745 // First verify that this root is live
2746 _root_cl->do_oop(p);
2747
2748 if (!G1VerifyHeapRegionCodeRoots) {
2749 // We're not verifying the code roots attached to heap region.
2750 return;
2751 }
2752
2753 // Don't check the code roots during marking verification in a full GC
2754 if (_vo == VerifyOption_G1UseMarkWord) {
2755 return;
2756 }
2757
2758 // Now verify that the current nmethod (which contains p) is
2759 // in the code root list of the heap region containing the
2760 // object referenced by p.
2761
2762 T heap_oop = oopDesc::load_heap_oop(p);
2763 if (!oopDesc::is_null(heap_oop)) {
2764 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2765
2766 // Now fetch the region containing the object
2767 HeapRegion* hr = _g1h->heap_region_containing(obj);
2768 HeapRegionRemSet* hrrs = hr->rem_set();
2769 // Verify that the strong code root list for this region
2770 // contains the nmethod
2771 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2772 log_info(gc, verify)("Code root location " PTR_FORMAT " "
2773 "from nmethod " PTR_FORMAT " not in strong "
2774 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2775 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2776 _failures = true;
2777 }
2778 }
2779 }
2780
2781 public:
2782 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2783 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2784
2785 void do_oop(oop* p) { do_oop_work(p); }
2786 void do_oop(narrowOop* p) { do_oop_work(p); }
2787
2788 void set_nmethod(nmethod* nm) { _nm = nm; }
2789 bool failures() { return _failures; }
2790 };
2791
2792 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2793 G1VerifyCodeRootOopClosure* _oop_cl;
2794
2795 public:
2796 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2797 _oop_cl(oop_cl) {}
2798
2799 void do_code_blob(CodeBlob* cb) {
2800 nmethod* nm = cb->as_nmethod_or_null();
2801 if (nm != NULL) {
2802 _oop_cl->set_nmethod(nm);
2803 nm->oops_do(_oop_cl);
2804 }
2805 }
2806 };
2807
2808 class YoungRefCounterClosure : public OopClosure {
2809 G1CollectedHeap* _g1h;
2810 int _count;
2811 public:
2812 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2813 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2814 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2815
2816 int count() { return _count; }
2817 void reset_count() { _count = 0; };
2818 };
2819
2820 class VerifyKlassClosure: public KlassClosure {
2821 YoungRefCounterClosure _young_ref_counter_closure;
2822 OopClosure *_oop_closure;
2823 public:
2824 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2825 void do_klass(Klass* k) {
2826 k->oops_do(_oop_closure);
2827
2828 _young_ref_counter_closure.reset_count();
2829 k->oops_do(&_young_ref_counter_closure);
2830 if (_young_ref_counter_closure.count() > 0) {
2831 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2832 }
2833 }
2834 };
2835
2836 class VerifyLivenessOopClosure: public OopClosure {
2837 G1CollectedHeap* _g1h;
2838 VerifyOption _vo;
2839 public:
2840 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2841 _g1h(g1h), _vo(vo)
2842 { }
2843 void do_oop(narrowOop *p) { do_oop_work(p); }
2844 void do_oop( oop *p) { do_oop_work(p); }
2845
2846 template <class T> void do_oop_work(T *p) {
2847 oop obj = oopDesc::load_decode_heap_oop(p);
2848 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2849 "Dead object referenced by a not dead object");
2850 }
2851 };
2852
2853 class VerifyObjsInRegionClosure: public ObjectClosure {
2854 private:
2855 G1CollectedHeap* _g1h;
2856 size_t _live_bytes;
2857 HeapRegion *_hr;
2858 VerifyOption _vo;
2859 public:
2860 // _vo == UsePrevMarking -> use "prev" marking information,
2861 // _vo == UseNextMarking -> use "next" marking information,
2862 // _vo == UseMarkWord -> use mark word from object header.
2863 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2864 : _live_bytes(0), _hr(hr), _vo(vo) {
2865 _g1h = G1CollectedHeap::heap();
2866 }
2867 void do_object(oop o) {
2868 VerifyLivenessOopClosure isLive(_g1h, _vo);
2869 assert(o != NULL, "Huh?");
2870 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2871 // If the object is alive according to the mark word,
2872 // then verify that the marking information agrees.
2873 // Note we can't verify the contra-positive of the
2874 // above: if the object is dead (according to the mark
2875 // word), it may not be marked, or may have been marked
2876 // but has since became dead, or may have been allocated
2877 // since the last marking.
2878 if (_vo == VerifyOption_G1UseMarkWord) {
2879 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2880 }
2881
2882 o->oop_iterate_no_header(&isLive);
2883 if (!_hr->obj_allocated_since_prev_marking(o)) {
2884 size_t obj_size = o->size(); // Make sure we don't overflow
2885 _live_bytes += (obj_size * HeapWordSize);
2886 }
2887 }
2888 }
2889 size_t live_bytes() { return _live_bytes; }
2890 };
2891
2892 class VerifyArchiveOopClosure: public OopClosure {
2893 public:
2894 VerifyArchiveOopClosure(HeapRegion *hr) { }
2895 void do_oop(narrowOop *p) { do_oop_work(p); }
2896 void do_oop( oop *p) { do_oop_work(p); }
2897
2898 template <class T> void do_oop_work(T *p) {
2899 oop obj = oopDesc::load_decode_heap_oop(p);
2900 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2901 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2902 p2i(p), p2i(obj));
2903 }
2904 };
2905
2906 class VerifyArchiveRegionClosure: public ObjectClosure {
2907 public:
2908 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2909 // Verify that all object pointers are to archive regions.
2910 void do_object(oop o) {
2911 VerifyArchiveOopClosure checkOop(NULL);
2912 assert(o != NULL, "Should not be here for NULL oops");
2913 o->oop_iterate_no_header(&checkOop);
2914 }
2915 };
2916
2917 class VerifyRegionClosure: public HeapRegionClosure {
2918 private:
2919 bool _par;
2920 VerifyOption _vo;
2921 bool _failures;
2922 public:
2923 // _vo == UsePrevMarking -> use "prev" marking information,
2924 // _vo == UseNextMarking -> use "next" marking information,
2925 // _vo == UseMarkWord -> use mark word from object header.
2926 VerifyRegionClosure(bool par, VerifyOption vo)
2927 : _par(par),
2928 _vo(vo),
2929 _failures(false) {}
2930
2931 bool failures() {
2932 return _failures;
2933 }
2934
2935 bool doHeapRegion(HeapRegion* r) {
2936 // For archive regions, verify there are no heap pointers to
2937 // non-pinned regions. For all others, verify liveness info.
2938 if (r->is_archive()) {
2939 VerifyArchiveRegionClosure verify_oop_pointers(r);
2940 r->object_iterate(&verify_oop_pointers);
2941 return true;
2942 }
2943 if (!r->is_continues_humongous()) {
2944 bool failures = false;
2945 r->verify(_vo, &failures);
2946 if (failures) {
2947 _failures = true;
2948 } else if (!r->is_starts_humongous()) {
2949 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2950 r->object_iterate(¬_dead_yet_cl);
2951 if (_vo != VerifyOption_G1UseNextMarking) {
2952 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2953 log_info(gc, verify)("[" PTR_FORMAT "," PTR_FORMAT "] max_live_bytes " SIZE_FORMAT " < calculated " SIZE_FORMAT,
2954 p2i(r->bottom()), p2i(r->end()), r->max_live_bytes(), not_dead_yet_cl.live_bytes());
2955 _failures = true;
2956 }
2957 } else {
2958 // When vo == UseNextMarking we cannot currently do a sanity
2959 // check on the live bytes as the calculation has not been
2960 // finalized yet.
2961 }
2962 }
2963 }
2964 return false; // stop the region iteration if we hit a failure
2965 }
2966 };
2967
2968 // This is the task used for parallel verification of the heap regions
2969
2970 class G1ParVerifyTask: public AbstractGangTask {
2971 private:
2972 G1CollectedHeap* _g1h;
2973 VerifyOption _vo;
2974 bool _failures;
2975 HeapRegionClaimer _hrclaimer;
2976
2977 public:
2978 // _vo == UsePrevMarking -> use "prev" marking information,
2979 // _vo == UseNextMarking -> use "next" marking information,
2980 // _vo == UseMarkWord -> use mark word from object header.
2981 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
2982 AbstractGangTask("Parallel verify task"),
2983 _g1h(g1h),
2984 _vo(vo),
2985 _failures(false),
2986 _hrclaimer(g1h->workers()->active_workers()) {}
2987
2988 bool failures() {
2989 return _failures;
2990 }
2991
2992 void work(uint worker_id) {
2993 HandleMark hm;
2994 VerifyRegionClosure blk(true, _vo);
2995 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
2996 if (blk.failures()) {
2997 _failures = true;
2998 }
2999 }
3000 };
3001
3002 void G1CollectedHeap::verify(VerifyOption vo) {
3003 if (!SafepointSynchronize::is_at_safepoint()) {
3004 log_info(gc, verify)("Skipping verification. Not at safepoint.");
3005 }
3006
3007 assert(Thread::current()->is_VM_thread(),
3008 "Expected to be executed serially by the VM thread at this point");
3009
3010 log_debug(gc, verify)("Roots");
3011 VerifyRootsClosure rootsCl(vo);
3012 VerifyKlassClosure klassCl(this, &rootsCl);
3013 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3014
3015 // We apply the relevant closures to all the oops in the
3016 // system dictionary, class loader data graph, the string table
3017 // and the nmethods in the code cache.
3018 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3019 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3020
3021 {
3022 G1RootProcessor root_processor(this, 1);
3023 root_processor.process_all_roots(&rootsCl,
3024 &cldCl,
3025 &blobsCl);
3026 }
3027
3028 bool failures = rootsCl.failures() || codeRootsCl.failures();
3029
3030 if (vo != VerifyOption_G1UseMarkWord) {
3031 // If we're verifying during a full GC then the region sets
3032 // will have been torn down at the start of the GC. Therefore
3033 // verifying the region sets will fail. So we only verify
3034 // the region sets when not in a full GC.
3035 log_debug(gc, verify)("HeapRegionSets");
3036 verify_region_sets();
3037 }
3038
3039 log_debug(gc, verify)("HeapRegions");
3040 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3041
3042 G1ParVerifyTask task(this, vo);
3043 workers()->run_task(&task);
3044 if (task.failures()) {
3045 failures = true;
3046 }
3047
3048 } else {
3049 VerifyRegionClosure blk(false, vo);
3050 heap_region_iterate(&blk);
3051 if (blk.failures()) {
3052 failures = true;
3053 }
3054 }
3055
3056 if (G1StringDedup::is_enabled()) {
3057 log_debug(gc, verify)("StrDedup");
3058 G1StringDedup::verify();
3059 }
3060
3061 if (failures) {
3062 log_info(gc, verify)("Heap after failed verification:");
3063 // It helps to have the per-region information in the output to
3064 // help us track down what went wrong. This is why we call
3065 // print_extended_on() instead of print_on().
3066 LogHandle(gc, verify) log;
3067 ResourceMark rm;
3068 print_extended_on(log.info_stream());
3069 }
3070 guarantee(!failures, "there should not have been any failures");
3071 }
3072
3073 double G1CollectedHeap::verify(bool guard, const char* msg) {
3074 double verify_time_ms = 0.0;
3075
3076 if (guard && total_collections() >= VerifyGCStartAt) {
3077 double verify_start = os::elapsedTime();
3078 HandleMark hm; // Discard invalid handles created during verification
3079 prepare_for_verify();
3080 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3081 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3082 }
3083
3084 return verify_time_ms;
3085 }
3086
3087 void G1CollectedHeap::verify_before_gc() {
3088 double verify_time_ms = verify(VerifyBeforeGC, "Before GC");
3089 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3090 }
3091
3092 void G1CollectedHeap::verify_after_gc() {
3093 double verify_time_ms = verify(VerifyAfterGC, "After GC");
3094 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3095 }
3096
3097 class PrintRegionClosure: public HeapRegionClosure {
3098 outputStream* _st;
3099 public:
3100 PrintRegionClosure(outputStream* st) : _st(st) {}
3101 bool doHeapRegion(HeapRegion* r) {
3102 r->print_on(_st);
3103 return false;
3104 }
3105 };
3106
3107 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3108 const HeapRegion* hr,
3109 const VerifyOption vo) const {
3110 switch (vo) {
3111 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3112 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3113 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3114 default: ShouldNotReachHere();
3115 }
3116 return false; // keep some compilers happy
3117 }
3118
3119 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3120 const VerifyOption vo) const {
3121 switch (vo) {
3122 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3123 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3124 case VerifyOption_G1UseMarkWord: {
3125 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3126 return !obj->is_gc_marked() && !hr->is_archive();
3127 }
3128 default: ShouldNotReachHere();
3129 }
3130 return false; // keep some compilers happy
3131 }
3132
3133 void G1CollectedHeap::print_on(outputStream* st) const {
3134 st->print(" %-20s", "garbage-first heap");
3135 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3136 capacity()/K, used_unlocked()/K);
3137 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3138 p2i(_hrm.reserved().start()),
3139 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3140 p2i(_hrm.reserved().end()));
3141 st->cr();
3142 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3143 uint young_regions = _young_list->length();
3144 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3145 (size_t) young_regions * HeapRegion::GrainBytes / K);
3146 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3147 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3148 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3149 st->cr();
3150 MetaspaceAux::print_on(st);
3151 }
3152
3153 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3154 print_on(st);
3155
3156 // Print the per-region information.
3157 st->cr();
3158 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3159 "HS=humongous(starts), HC=humongous(continues), "
3160 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3161 "PTAMS=previous top-at-mark-start, "
3162 "NTAMS=next top-at-mark-start)");
3163 PrintRegionClosure blk(st);
3164 heap_region_iterate(&blk);
3165 }
3166
3167 void G1CollectedHeap::print_on_error(outputStream* st) const {
3168 this->CollectedHeap::print_on_error(st);
3169
3170 if (_cm != NULL) {
3171 st->cr();
3172 _cm->print_on_error(st);
3173 }
3174 }
3175
3176 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3177 workers()->print_worker_threads_on(st);
3178 _cmThread->print_on(st);
3179 st->cr();
3180 _cm->print_worker_threads_on(st);
3181 _cg1r->print_worker_threads_on(st);
3182 if (G1StringDedup::is_enabled()) {
3183 G1StringDedup::print_worker_threads_on(st);
3184 }
3185 }
3186
3187 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3188 workers()->threads_do(tc);
3189 tc->do_thread(_cmThread);
3190 _cg1r->threads_do(tc);
3191 if (G1StringDedup::is_enabled()) {
3192 G1StringDedup::threads_do(tc);
3193 }
3194 }
3195
3196 void G1CollectedHeap::print_tracing_info() const {
3197 // We'll overload this to mean "trace GC pause statistics."
3198 if (TraceYoungGenTime || TraceOldGenTime) {
3199 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3200 // to that.
3201 g1_policy()->print_tracing_info();
3202 }
3203 g1_rem_set()->print_summary_info();
3204 concurrent_mark()->print_summary_info();
3205 g1_policy()->print_yg_surv_rate_info();
3206 }
3207
3208 #ifndef PRODUCT
3209 // Helpful for debugging RSet issues.
3210
3211 class PrintRSetsClosure : public HeapRegionClosure {
3212 private:
3213 const char* _msg;
3214 size_t _occupied_sum;
3215
3216 public:
3217 bool doHeapRegion(HeapRegion* r) {
3218 HeapRegionRemSet* hrrs = r->rem_set();
3219 size_t occupied = hrrs->occupied();
3220 _occupied_sum += occupied;
3221
3222 tty->print_cr("Printing RSet for region " HR_FORMAT,
3223 HR_FORMAT_PARAMS(r));
3224 if (occupied == 0) {
3225 tty->print_cr(" RSet is empty");
3226 } else {
3227 hrrs->print();
3228 }
3229 tty->print_cr("----------");
3230 return false;
3231 }
3232
3233 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3234 tty->cr();
3235 tty->print_cr("========================================");
3236 tty->print_cr("%s", msg);
3237 tty->cr();
3238 }
3239
3240 ~PrintRSetsClosure() {
3241 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3242 tty->print_cr("========================================");
3243 tty->cr();
3244 }
3245 };
3246
3247 void G1CollectedHeap::print_cset_rsets() {
3248 PrintRSetsClosure cl("Printing CSet RSets");
3249 collection_set_iterate(&cl);
3250 }
3251
3252 void G1CollectedHeap::print_all_rsets() {
3253 PrintRSetsClosure cl("Printing All RSets");;
3254 heap_region_iterate(&cl);
3255 }
3256 #endif // PRODUCT
3257
3258 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3259 YoungList* young_list = heap()->young_list();
3260
3261 size_t eden_used_bytes = young_list->eden_used_bytes();
3262 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3263
3264 size_t eden_capacity_bytes =
3265 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3266
3267 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3268 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3269 }
3270
3271 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3272 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3273 stats->unused(), stats->used(), stats->region_end_waste(),
3274 stats->regions_filled(), stats->direct_allocated(),
3275 stats->failure_used(), stats->failure_waste());
3276 }
3277
3278 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3279 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3280 gc_tracer->report_gc_heap_summary(when, heap_summary);
3281
3282 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3283 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3284 }
3285
3286
3287 G1CollectedHeap* G1CollectedHeap::heap() {
3288 CollectedHeap* heap = Universe::heap();
3289 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3290 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3291 return (G1CollectedHeap*)heap;
3292 }
3293
3294 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3295 // always_do_update_barrier = false;
3296 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3297 // Fill TLAB's and such
3298 accumulate_statistics_all_tlabs();
3299 ensure_parsability(true);
3300
3301 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
3302 }
3303
3304 void G1CollectedHeap::gc_epilogue(bool full) {
3305 // we are at the end of the GC. Total collections has already been increased.
3306 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
3307
3308 // FIXME: what is this about?
3309 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3310 // is set.
3311 #if defined(COMPILER2) || INCLUDE_JVMCI
3312 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3313 #endif
3314 // always_do_update_barrier = true;
3315
3316 resize_all_tlabs();
3317 allocation_context_stats().update(full);
3318
3319 // We have just completed a GC. Update the soft reference
3320 // policy with the new heap occupancy
3321 Universe::update_heap_info_at_gc();
3322 }
3323
3324 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3325 uint gc_count_before,
3326 bool* succeeded,
3327 GCCause::Cause gc_cause) {
3328 assert_heap_not_locked_and_not_at_safepoint();
3329 g1_policy()->record_stop_world_start();
3330 VM_G1IncCollectionPause op(gc_count_before,
3331 word_size,
3332 false, /* should_initiate_conc_mark */
3333 g1_policy()->max_pause_time_ms(),
3334 gc_cause);
3335
3336 op.set_allocation_context(AllocationContext::current());
3337 VMThread::execute(&op);
3338
3339 HeapWord* result = op.result();
3340 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3341 assert(result == NULL || ret_succeeded,
3342 "the result should be NULL if the VM did not succeed");
3343 *succeeded = ret_succeeded;
3344
3345 assert_heap_not_locked();
3346 return result;
3347 }
3348
3349 void
3350 G1CollectedHeap::doConcurrentMark() {
3351 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3352 if (!_cmThread->in_progress()) {
3353 _cmThread->set_started();
3354 CGC_lock->notify();
3355 }
3356 }
3357
3358 size_t G1CollectedHeap::pending_card_num() {
3359 size_t extra_cards = 0;
3360 JavaThread *curr = Threads::first();
3361 while (curr != NULL) {
3362 DirtyCardQueue& dcq = curr->dirty_card_queue();
3363 extra_cards += dcq.size();
3364 curr = curr->next();
3365 }
3366 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3367 size_t buffer_size = dcqs.buffer_size();
3368 size_t buffer_num = dcqs.completed_buffers_num();
3369
3370 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3371 // in bytes - not the number of 'entries'. We need to convert
3372 // into a number of cards.
3373 return (buffer_size * buffer_num + extra_cards) / oopSize;
3374 }
3375
3376 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3377 private:
3378 size_t _total_humongous;
3379 size_t _candidate_humongous;
3380
3381 DirtyCardQueue _dcq;
3382
3383 // We don't nominate objects with many remembered set entries, on
3384 // the assumption that such objects are likely still live.
3385 bool is_remset_small(HeapRegion* region) const {
3386 HeapRegionRemSet* const rset = region->rem_set();
3387 return G1EagerReclaimHumongousObjectsWithStaleRefs
3388 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3389 : rset->is_empty();
3390 }
3391
3392 bool is_typeArray_region(HeapRegion* region) const {
3393 return oop(region->bottom())->is_typeArray();
3394 }
3395
3396 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3397 assert(region->is_starts_humongous(), "Must start a humongous object");
3398
3399 // Candidate selection must satisfy the following constraints
3400 // while concurrent marking is in progress:
3401 //
3402 // * In order to maintain SATB invariants, an object must not be
3403 // reclaimed if it was allocated before the start of marking and
3404 // has not had its references scanned. Such an object must have
3405 // its references (including type metadata) scanned to ensure no
3406 // live objects are missed by the marking process. Objects
3407 // allocated after the start of concurrent marking don't need to
3408 // be scanned.
3409 //
3410 // * An object must not be reclaimed if it is on the concurrent
3411 // mark stack. Objects allocated after the start of concurrent
3412 // marking are never pushed on the mark stack.
3413 //
3414 // Nominating only objects allocated after the start of concurrent
3415 // marking is sufficient to meet both constraints. This may miss
3416 // some objects that satisfy the constraints, but the marking data
3417 // structures don't support efficiently performing the needed
3418 // additional tests or scrubbing of the mark stack.
3419 //
3420 // However, we presently only nominate is_typeArray() objects.
3421 // A humongous object containing references induces remembered
3422 // set entries on other regions. In order to reclaim such an
3423 // object, those remembered sets would need to be cleaned up.
3424 //
3425 // We also treat is_typeArray() objects specially, allowing them
3426 // to be reclaimed even if allocated before the start of
3427 // concurrent mark. For this we rely on mark stack insertion to
3428 // exclude is_typeArray() objects, preventing reclaiming an object
3429 // that is in the mark stack. We also rely on the metadata for
3430 // such objects to be built-in and so ensured to be kept live.
3431 // Frequent allocation and drop of large binary blobs is an
3432 // important use case for eager reclaim, and this special handling
3433 // may reduce needed headroom.
3434
3435 return is_typeArray_region(region) && is_remset_small(region);
3436 }
3437
3438 public:
3439 RegisterHumongousWithInCSetFastTestClosure()
3440 : _total_humongous(0),
3441 _candidate_humongous(0),
3442 _dcq(&JavaThread::dirty_card_queue_set()) {
3443 }
3444
3445 virtual bool doHeapRegion(HeapRegion* r) {
3446 if (!r->is_starts_humongous()) {
3447 return false;
3448 }
3449 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3450
3451 bool is_candidate = humongous_region_is_candidate(g1h, r);
3452 uint rindex = r->hrm_index();
3453 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3454 if (is_candidate) {
3455 _candidate_humongous++;
3456 g1h->register_humongous_region_with_cset(rindex);
3457 // Is_candidate already filters out humongous object with large remembered sets.
3458 // If we have a humongous object with a few remembered sets, we simply flush these
3459 // remembered set entries into the DCQS. That will result in automatic
3460 // re-evaluation of their remembered set entries during the following evacuation
3461 // phase.
3462 if (!r->rem_set()->is_empty()) {
3463 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3464 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3465 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3466 HeapRegionRemSetIterator hrrs(r->rem_set());
3467 size_t card_index;
3468 while (hrrs.has_next(card_index)) {
3469 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3470 // The remembered set might contain references to already freed
3471 // regions. Filter out such entries to avoid failing card table
3472 // verification.
3473 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3474 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3475 *card_ptr = CardTableModRefBS::dirty_card_val();
3476 _dcq.enqueue(card_ptr);
3477 }
3478 }
3479 }
3480 r->rem_set()->clear_locked();
3481 }
3482 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3483 }
3484 _total_humongous++;
3485
3486 return false;
3487 }
3488
3489 size_t total_humongous() const { return _total_humongous; }
3490 size_t candidate_humongous() const { return _candidate_humongous; }
3491
3492 void flush_rem_set_entries() { _dcq.flush(); }
3493 };
3494
3495 void G1CollectedHeap::register_humongous_regions_with_cset() {
3496 if (!G1EagerReclaimHumongousObjects) {
3497 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3498 return;
3499 }
3500 double time = os::elapsed_counter();
3501
3502 // Collect reclaim candidate information and register candidates with cset.
3503 RegisterHumongousWithInCSetFastTestClosure cl;
3504 heap_region_iterate(&cl);
3505
3506 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3507 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3508 cl.total_humongous(),
3509 cl.candidate_humongous());
3510 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3511
3512 // Finally flush all remembered set entries to re-check into the global DCQS.
3513 cl.flush_rem_set_entries();
3514 }
3515
3516 #ifdef ASSERT
3517 class VerifyCSetClosure: public HeapRegionClosure {
3518 public:
3519 bool doHeapRegion(HeapRegion* hr) {
3520 // Here we check that the CSet region's RSet is ready for parallel
3521 // iteration. The fields that we'll verify are only manipulated
3522 // when the region is part of a CSet and is collected. Afterwards,
3523 // we reset these fields when we clear the region's RSet (when the
3524 // region is freed) so they are ready when the region is
3525 // re-allocated. The only exception to this is if there's an
3526 // evacuation failure and instead of freeing the region we leave
3527 // it in the heap. In that case, we reset these fields during
3528 // evacuation failure handling.
3529 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3530
3531 // Here's a good place to add any other checks we'd like to
3532 // perform on CSet regions.
3533 return false;
3534 }
3535 };
3536 #endif // ASSERT
3537
3538 uint G1CollectedHeap::num_task_queues() const {
3539 return _task_queues->size();
3540 }
3541
3542 #if TASKQUEUE_STATS
3543 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3544 st->print_raw_cr("GC Task Stats");
3545 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3546 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3547 }
3548
3549 void G1CollectedHeap::print_taskqueue_stats() const {
3550 LogHandle(gc, task, stats) log;
3551 if (!log.is_develop()) {
3552 return;
3553 }
3554 ResourceMark rm;
3555 outputStream* st = log.develop_stream();
3556
3557 print_taskqueue_stats_hdr(st);
3558
3559 TaskQueueStats totals;
3560 const uint n = num_task_queues();
3561 for (uint i = 0; i < n; ++i) {
3562 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3563 totals += task_queue(i)->stats;
3564 }
3565 st->print_raw("tot "); totals.print(st); st->cr();
3566
3567 DEBUG_ONLY(totals.verify());
3568 }
3569
3570 void G1CollectedHeap::reset_taskqueue_stats() {
3571 const uint n = num_task_queues();
3572 for (uint i = 0; i < n; ++i) {
3573 task_queue(i)->stats.reset();
3574 }
3575 }
3576 #endif // TASKQUEUE_STATS
3577
3578 void G1CollectedHeap::log_gc_footer(double pause_time_counter) {
3579 if (evacuation_failed()) {
3580 log_info(gc)("To-space exhausted");
3581 }
3582
3583 double pause_time_sec = TimeHelper::counter_to_seconds(pause_time_counter);
3584 g1_policy()->print_phases(pause_time_sec);
3585
3586 g1_policy()->print_detailed_heap_transition();
3587 }
3588
3589
3590 void G1CollectedHeap::wait_for_root_region_scanning() {
3591 double scan_wait_start = os::elapsedTime();
3592 // We have to wait until the CM threads finish scanning the
3593 // root regions as it's the only way to ensure that all the
3594 // objects on them have been correctly scanned before we start
3595 // moving them during the GC.
3596 bool waited = _cm->root_regions()->wait_until_scan_finished();
3597 double wait_time_ms = 0.0;
3598 if (waited) {
3599 double scan_wait_end = os::elapsedTime();
3600 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3601 }
3602 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3603 }
3604
3605 bool
3606 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3607 assert_at_safepoint(true /* should_be_vm_thread */);
3608 guarantee(!is_gc_active(), "collection is not reentrant");
3609
3610 if (GC_locker::check_active_before_gc()) {
3611 return false;
3612 }
3613
3614 _gc_timer_stw->register_gc_start();
3615
3616 GCIdMark gc_id_mark;
3617 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3618
3619 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3620 ResourceMark rm;
3621
3622 wait_for_root_region_scanning();
3623
3624 print_heap_before_gc();
3625 trace_heap_before_gc(_gc_tracer_stw);
3626
3627 verify_region_sets_optional();
3628 verify_dirty_young_regions();
3629
3630 // This call will decide whether this pause is an initial-mark
3631 // pause. If it is, during_initial_mark_pause() will return true
3632 // for the duration of this pause.
3633 g1_policy()->decide_on_conc_mark_initiation();
3634
3635 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3636 assert(!collector_state()->during_initial_mark_pause() ||
3637 collector_state()->gcs_are_young(), "sanity");
3638
3639 // We also do not allow mixed GCs during marking.
3640 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3641
3642 // Record whether this pause is an initial mark. When the current
3643 // thread has completed its logging output and it's safe to signal
3644 // the CM thread, the flag's value in the policy has been reset.
3645 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3646
3647 // Inner scope for scope based logging, timers, and stats collection
3648 {
3649 EvacuationInfo evacuation_info;
3650
3651 if (collector_state()->during_initial_mark_pause()) {
3652 // We are about to start a marking cycle, so we increment the
3653 // full collection counter.
3654 increment_old_marking_cycles_started();
3655 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3656 }
3657
3658 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3659
3660 GCTraceCPUTime tcpu;
3661
3662 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3663 workers()->active_workers(),
3664 Threads::number_of_non_daemon_threads());
3665 workers()->set_active_workers(active_workers);
3666 FormatBuffer<> gc_string("Pause ");
3667 if (collector_state()->during_initial_mark_pause()) {
3668 gc_string.append("Initial Mark");
3669 } else if (collector_state()->gcs_are_young()) {
3670 gc_string.append("Young");
3671 } else {
3672 gc_string.append("Mixed");
3673 }
3674 GCTraceTime(Info, gc) tm5(gc_string, NULL, gc_cause(), true);
3675
3676
3677 double pause_start_sec = os::elapsedTime();
3678 double pause_start_counter = os::elapsed_counter();
3679 g1_policy()->note_gc_start(active_workers);
3680
3681 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3682 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3683
3684 // If the secondary_free_list is not empty, append it to the
3685 // free_list. No need to wait for the cleanup operation to finish;
3686 // the region allocation code will check the secondary_free_list
3687 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3688 // set, skip this step so that the region allocation code has to
3689 // get entries from the secondary_free_list.
3690 if (!G1StressConcRegionFreeing) {
3691 append_secondary_free_list_if_not_empty_with_lock();
3692 }
3693
3694 assert(check_young_list_well_formed(), "young list should be well formed");
3695
3696 // Don't dynamically change the number of GC threads this early. A value of
3697 // 0 is used to indicate serial work. When parallel work is done,
3698 // it will be set.
3699
3700 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3701 IsGCActiveMark x;
3702
3703 gc_prologue(false);
3704 increment_total_collections(false /* full gc */);
3705 increment_gc_time_stamp();
3706
3707 verify_before_gc();
3708
3709 check_bitmaps("GC Start");
3710
3711 #if defined(COMPILER2) || INCLUDE_JVMCI
3712 DerivedPointerTable::clear();
3713 #endif
3714
3715 // Please see comment in g1CollectedHeap.hpp and
3716 // G1CollectedHeap::ref_processing_init() to see how
3717 // reference processing currently works in G1.
3718
3719 // Enable discovery in the STW reference processor
3720 ref_processor_stw()->enable_discovery();
3721
3722 {
3723 // We want to temporarily turn off discovery by the
3724 // CM ref processor, if necessary, and turn it back on
3725 // on again later if we do. Using a scoped
3726 // NoRefDiscovery object will do this.
3727 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3728
3729 // Forget the current alloc region (we might even choose it to be part
3730 // of the collection set!).
3731 _allocator->release_mutator_alloc_region();
3732
3733 // This timing is only used by the ergonomics to handle our pause target.
3734 // It is unclear why this should not include the full pause. We will
3735 // investigate this in CR 7178365.
3736 //
3737 // Preserving the old comment here if that helps the investigation:
3738 //
3739 // The elapsed time induced by the start time below deliberately elides
3740 // the possible verification above.
3741 double sample_start_time_sec = os::elapsedTime();
3742
3743 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3744
3745 if (collector_state()->during_initial_mark_pause()) {
3746 concurrent_mark()->checkpointRootsInitialPre();
3747 }
3748
3749 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3750 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3751
3752 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3753
3754 register_humongous_regions_with_cset();
3755
3756 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3757
3758 _cm->note_start_of_gc();
3759 // We call this after finalize_cset() to
3760 // ensure that the CSet has been finalized.
3761 _cm->verify_no_cset_oops();
3762
3763 if (_hr_printer.is_active()) {
3764 HeapRegion* hr = g1_policy()->collection_set();
3765 while (hr != NULL) {
3766 _hr_printer.cset(hr);
3767 hr = hr->next_in_collection_set();
3768 }
3769 }
3770
3771 #ifdef ASSERT
3772 VerifyCSetClosure cl;
3773 collection_set_iterate(&cl);
3774 #endif // ASSERT
3775
3776 // Initialize the GC alloc regions.
3777 _allocator->init_gc_alloc_regions(evacuation_info);
3778
3779 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3780 pre_evacuate_collection_set();
3781
3782 // Actually do the work...
3783 evacuate_collection_set(evacuation_info, &per_thread_states);
3784
3785 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3786
3787 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3788 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3789
3790 eagerly_reclaim_humongous_regions();
3791
3792 g1_policy()->clear_collection_set();
3793
3794 // Start a new incremental collection set for the next pause.
3795 g1_policy()->start_incremental_cset_building();
3796
3797 clear_cset_fast_test();
3798
3799 _young_list->reset_sampled_info();
3800
3801 // Don't check the whole heap at this point as the
3802 // GC alloc regions from this pause have been tagged
3803 // as survivors and moved on to the survivor list.
3804 // Survivor regions will fail the !is_young() check.
3805 assert(check_young_list_empty(false /* check_heap */),
3806 "young list should be empty");
3807
3808 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3809 _young_list->first_survivor_region(),
3810 _young_list->last_survivor_region());
3811
3812 _young_list->reset_auxilary_lists();
3813
3814 if (evacuation_failed()) {
3815 set_used(recalculate_used());
3816 if (_archive_allocator != NULL) {
3817 _archive_allocator->clear_used();
3818 }
3819 for (uint i = 0; i < ParallelGCThreads; i++) {
3820 if (_evacuation_failed_info_array[i].has_failed()) {
3821 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3822 }
3823 }
3824 } else {
3825 // The "used" of the the collection set have already been subtracted
3826 // when they were freed. Add in the bytes evacuated.
3827 increase_used(g1_policy()->bytes_copied_during_gc());
3828 }
3829
3830 if (collector_state()->during_initial_mark_pause()) {
3831 // We have to do this before we notify the CM threads that
3832 // they can start working to make sure that all the
3833 // appropriate initialization is done on the CM object.
3834 concurrent_mark()->checkpointRootsInitialPost();
3835 collector_state()->set_mark_in_progress(true);
3836 // Note that we don't actually trigger the CM thread at
3837 // this point. We do that later when we're sure that
3838 // the current thread has completed its logging output.
3839 }
3840
3841 allocate_dummy_regions();
3842
3843 _allocator->init_mutator_alloc_region();
3844
3845 {
3846 size_t expand_bytes = g1_policy()->expansion_amount();
3847 if (expand_bytes > 0) {
3848 size_t bytes_before = capacity();
3849 // No need for an ergo logging here,
3850 // expansion_amount() does this when it returns a value > 0.
3851 double expand_ms;
3852 if (!expand(expand_bytes, &expand_ms)) {
3853 // We failed to expand the heap. Cannot do anything about it.
3854 }
3855 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3856 }
3857 }
3858
3859 // We redo the verification but now wrt to the new CSet which
3860 // has just got initialized after the previous CSet was freed.
3861 _cm->verify_no_cset_oops();
3862 _cm->note_end_of_gc();
3863
3864 // This timing is only used by the ergonomics to handle our pause target.
3865 // It is unclear why this should not include the full pause. We will
3866 // investigate this in CR 7178365.
3867 double sample_end_time_sec = os::elapsedTime();
3868 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3869 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3870 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3871
3872 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3873 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3874
3875 MemoryService::track_memory_usage();
3876
3877 // In prepare_for_verify() below we'll need to scan the deferred
3878 // update buffers to bring the RSets up-to-date if
3879 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3880 // the update buffers we'll probably need to scan cards on the
3881 // regions we just allocated to (i.e., the GC alloc
3882 // regions). However, during the last GC we called
3883 // set_saved_mark() on all the GC alloc regions, so card
3884 // scanning might skip the [saved_mark_word()...top()] area of
3885 // those regions (i.e., the area we allocated objects into
3886 // during the last GC). But it shouldn't. Given that
3887 // saved_mark_word() is conditional on whether the GC time stamp
3888 // on the region is current or not, by incrementing the GC time
3889 // stamp here we invalidate all the GC time stamps on all the
3890 // regions and saved_mark_word() will simply return top() for
3891 // all the regions. This is a nicer way of ensuring this rather
3892 // than iterating over the regions and fixing them. In fact, the
3893 // GC time stamp increment here also ensures that
3894 // saved_mark_word() will return top() between pauses, i.e.,
3895 // during concurrent refinement. So we don't need the
3896 // is_gc_active() check to decided which top to use when
3897 // scanning cards (see CR 7039627).
3898 increment_gc_time_stamp();
3899
3900 verify_after_gc();
3901 check_bitmaps("GC End");
3902
3903 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3904 ref_processor_stw()->verify_no_references_recorded();
3905
3906 // CM reference discovery will be re-enabled if necessary.
3907 }
3908
3909 #ifdef TRACESPINNING
3910 ParallelTaskTerminator::print_termination_counts();
3911 #endif
3912
3913 gc_epilogue(false);
3914 }
3915
3916 // Print the remainder of the GC log output.
3917 log_gc_footer(os::elapsed_counter() - pause_start_counter);
3918
3919 // It is not yet to safe to tell the concurrent mark to
3920 // start as we have some optional output below. We don't want the
3921 // output from the concurrent mark thread interfering with this
3922 // logging output either.
3923
3924 _hrm.verify_optional();
3925 verify_region_sets_optional();
3926
3927 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3928 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3929
3930 print_heap_after_gc();
3931 trace_heap_after_gc(_gc_tracer_stw);
3932
3933 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3934 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3935 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3936 // before any GC notifications are raised.
3937 g1mm()->update_sizes();
3938
3939 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3940 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3941 _gc_timer_stw->register_gc_end();
3942 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3943 }
3944 // It should now be safe to tell the concurrent mark thread to start
3945 // without its logging output interfering with the logging output
3946 // that came from the pause.
3947
3948 if (should_start_conc_mark) {
3949 // CAUTION: after the doConcurrentMark() call below,
3950 // the concurrent marking thread(s) could be running
3951 // concurrently with us. Make sure that anything after
3952 // this point does not assume that we are the only GC thread
3953 // running. Note: of course, the actual marking work will
3954 // not start until the safepoint itself is released in
3955 // SuspendibleThreadSet::desynchronize().
3956 doConcurrentMark();
3957 }
3958
3959 return true;
3960 }
3961
3962 void G1CollectedHeap::remove_self_forwarding_pointers() {
3963 double remove_self_forwards_start = os::elapsedTime();
3964
3965 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3966 workers()->run_task(&rsfp_task);
3967
3968 // Now restore saved marks, if any.
3969 for (uint i = 0; i < ParallelGCThreads; i++) {
3970 OopAndMarkOopStack& cur = _preserved_objs[i];
3971 while (!cur.is_empty()) {
3972 OopAndMarkOop elem = cur.pop();
3973 elem.set_mark();
3974 }
3975 cur.clear(true);
3976 }
3977
3978 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3979 }
3980
3981 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3982 if (!_evacuation_failed) {
3983 _evacuation_failed = true;
3984 }
3985
3986 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3987
3988 // We want to call the "for_promotion_failure" version only in the
3989 // case of a promotion failure.
3990 if (m->must_be_preserved_for_promotion_failure(obj)) {
3991 OopAndMarkOop elem(obj, m);
3992 _preserved_objs[worker_id].push(elem);
3993 }
3994 }
3995
3996 class G1ParEvacuateFollowersClosure : public VoidClosure {
3997 private:
3998 double _start_term;
3999 double _term_time;
4000 size_t _term_attempts;
4001
4002 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4003 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4004 protected:
4005 G1CollectedHeap* _g1h;
4006 G1ParScanThreadState* _par_scan_state;
4007 RefToScanQueueSet* _queues;
4008 ParallelTaskTerminator* _terminator;
4009
4010 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4011 RefToScanQueueSet* queues() { return _queues; }
4012 ParallelTaskTerminator* terminator() { return _terminator; }
4013
4014 public:
4015 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4016 G1ParScanThreadState* par_scan_state,
4017 RefToScanQueueSet* queues,
4018 ParallelTaskTerminator* terminator)
4019 : _g1h(g1h), _par_scan_state(par_scan_state),
4020 _queues(queues), _terminator(terminator),
4021 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4022
4023 void do_void();
4024
4025 double term_time() const { return _term_time; }
4026 size_t term_attempts() const { return _term_attempts; }
4027
4028 private:
4029 inline bool offer_termination();
4030 };
4031
4032 bool G1ParEvacuateFollowersClosure::offer_termination() {
4033 G1ParScanThreadState* const pss = par_scan_state();
4034 start_term_time();
4035 const bool res = terminator()->offer_termination();
4036 end_term_time();
4037 return res;
4038 }
4039
4040 void G1ParEvacuateFollowersClosure::do_void() {
4041 G1ParScanThreadState* const pss = par_scan_state();
4042 pss->trim_queue();
4043 do {
4044 pss->steal_and_trim_queue(queues());
4045 } while (!offer_termination());
4046 }
4047
4048 class G1ParTask : public AbstractGangTask {
4049 protected:
4050 G1CollectedHeap* _g1h;
4051 G1ParScanThreadStateSet* _pss;
4052 RefToScanQueueSet* _queues;
4053 G1RootProcessor* _root_processor;
4054 ParallelTaskTerminator _terminator;
4055 uint _n_workers;
4056
4057 public:
4058 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4059 : AbstractGangTask("G1 collection"),
4060 _g1h(g1h),
4061 _pss(per_thread_states),
4062 _queues(task_queues),
4063 _root_processor(root_processor),
4064 _terminator(n_workers, _queues),
4065 _n_workers(n_workers)
4066 {}
4067
4068 void work(uint worker_id) {
4069 if (worker_id >= _n_workers) return; // no work needed this round
4070
4071 double start_sec = os::elapsedTime();
4072 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4073
4074 {
4075 ResourceMark rm;
4076 HandleMark hm;
4077
4078 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4079
4080 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4081 pss->set_ref_processor(rp);
4082
4083 double start_strong_roots_sec = os::elapsedTime();
4084
4085 _root_processor->evacuate_roots(pss->closures(), worker_id);
4086
4087 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4088
4089 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4090 // treating the nmethods visited to act as roots for concurrent marking.
4091 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4092 // objects copied by the current evacuation.
4093 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4094 pss->closures()->weak_codeblobs(),
4095 worker_id);
4096
4097 _pss->add_cards_scanned(worker_id, cards_scanned);
4098
4099 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4100
4101 double term_sec = 0.0;
4102 size_t evac_term_attempts = 0;
4103 {
4104 double start = os::elapsedTime();
4105 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4106 evac.do_void();
4107
4108 evac_term_attempts = evac.term_attempts();
4109 term_sec = evac.term_time();
4110 double elapsed_sec = os::elapsedTime() - start;
4111 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4112 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4113 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4114 }
4115
4116 assert(pss->queue_is_empty(), "should be empty");
4117
4118 if (log_is_enabled(Debug, gc, task, stats)) {
4119 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4120 size_t lab_waste;
4121 size_t lab_undo_waste;
4122 pss->waste(lab_waste, lab_undo_waste);
4123 _g1h->print_termination_stats(worker_id,
4124 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4125 strong_roots_sec * 1000.0, /* strong roots time */
4126 term_sec * 1000.0, /* evac term time */
4127 evac_term_attempts, /* evac term attempts */
4128 lab_waste, /* alloc buffer waste */
4129 lab_undo_waste /* undo waste */
4130 );
4131 }
4132
4133 // Close the inner scope so that the ResourceMark and HandleMark
4134 // destructors are executed here and are included as part of the
4135 // "GC Worker Time".
4136 }
4137 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4138 }
4139 };
4140
4141 void G1CollectedHeap::print_termination_stats_hdr() {
4142 LogHandle(gc, task, stats) log;
4143 if (!log.is_debug()) {
4144 return;
4145 }
4146 log.debug("GC Termination Stats");
4147 log.debug(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4148 log.debug("thr ms ms %% ms %% attempts total alloc undo");
4149 log.debug("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4150 }
4151
4152 void G1CollectedHeap::print_termination_stats(uint worker_id,
4153 double elapsed_ms,
4154 double strong_roots_ms,
4155 double term_ms,
4156 size_t term_attempts,
4157 size_t alloc_buffer_waste,
4158 size_t undo_waste) const {
4159 log_debug(gc, task, stats)
4160 ("%3d %9.2f %9.2f %6.2f "
4161 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4162 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4163 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4164 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4165 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4166 alloc_buffer_waste * HeapWordSize / K,
4167 undo_waste * HeapWordSize / K);
4168 }
4169
4170 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4171 private:
4172 BoolObjectClosure* _is_alive;
4173 int _initial_string_table_size;
4174 int _initial_symbol_table_size;
4175
4176 bool _process_strings;
4177 int _strings_processed;
4178 int _strings_removed;
4179
4180 bool _process_symbols;
4181 int _symbols_processed;
4182 int _symbols_removed;
4183
4184 public:
4185 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4186 AbstractGangTask("String/Symbol Unlinking"),
4187 _is_alive(is_alive),
4188 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4189 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4190
4191 _initial_string_table_size = StringTable::the_table()->table_size();
4192 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4193 if (process_strings) {
4194 StringTable::clear_parallel_claimed_index();
4195 }
4196 if (process_symbols) {
4197 SymbolTable::clear_parallel_claimed_index();
4198 }
4199 }
4200
4201 ~G1StringSymbolTableUnlinkTask() {
4202 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4203 "claim value %d after unlink less than initial string table size %d",
4204 StringTable::parallel_claimed_index(), _initial_string_table_size);
4205 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4206 "claim value %d after unlink less than initial symbol table size %d",
4207 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4208
4209 log_trace(gc, stringdedup)("Cleaned string and symbol table, "
4210 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4211 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4212 strings_processed(), strings_removed(),
4213 symbols_processed(), symbols_removed());
4214 }
4215
4216 void work(uint worker_id) {
4217 int strings_processed = 0;
4218 int strings_removed = 0;
4219 int symbols_processed = 0;
4220 int symbols_removed = 0;
4221 if (_process_strings) {
4222 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4223 Atomic::add(strings_processed, &_strings_processed);
4224 Atomic::add(strings_removed, &_strings_removed);
4225 }
4226 if (_process_symbols) {
4227 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4228 Atomic::add(symbols_processed, &_symbols_processed);
4229 Atomic::add(symbols_removed, &_symbols_removed);
4230 }
4231 }
4232
4233 size_t strings_processed() const { return (size_t)_strings_processed; }
4234 size_t strings_removed() const { return (size_t)_strings_removed; }
4235
4236 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4237 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4238 };
4239
4240 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4241 private:
4242 static Monitor* _lock;
4243
4244 BoolObjectClosure* const _is_alive;
4245 const bool _unloading_occurred;
4246 const uint _num_workers;
4247
4248 // Variables used to claim nmethods.
4249 nmethod* _first_nmethod;
4250 volatile nmethod* _claimed_nmethod;
4251
4252 // The list of nmethods that need to be processed by the second pass.
4253 volatile nmethod* _postponed_list;
4254 volatile uint _num_entered_barrier;
4255
4256 public:
4257 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4258 _is_alive(is_alive),
4259 _unloading_occurred(unloading_occurred),
4260 _num_workers(num_workers),
4261 _first_nmethod(NULL),
4262 _claimed_nmethod(NULL),
4263 _postponed_list(NULL),
4264 _num_entered_barrier(0)
4265 {
4266 nmethod::increase_unloading_clock();
4267 // Get first alive nmethod
4268 NMethodIterator iter = NMethodIterator();
4269 if(iter.next_alive()) {
4270 _first_nmethod = iter.method();
4271 }
4272 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4273 }
4274
4275 ~G1CodeCacheUnloadingTask() {
4276 CodeCache::verify_clean_inline_caches();
4277
4278 CodeCache::set_needs_cache_clean(false);
4279 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4280
4281 CodeCache::verify_icholder_relocations();
4282 }
4283
4284 private:
4285 void add_to_postponed_list(nmethod* nm) {
4286 nmethod* old;
4287 do {
4288 old = (nmethod*)_postponed_list;
4289 nm->set_unloading_next(old);
4290 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4291 }
4292
4293 void clean_nmethod(nmethod* nm) {
4294 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4295
4296 if (postponed) {
4297 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4298 add_to_postponed_list(nm);
4299 }
4300
4301 // Mark that this thread has been cleaned/unloaded.
4302 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4303 nm->set_unloading_clock(nmethod::global_unloading_clock());
4304 }
4305
4306 void clean_nmethod_postponed(nmethod* nm) {
4307 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4308 }
4309
4310 static const int MaxClaimNmethods = 16;
4311
4312 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4313 nmethod* first;
4314 NMethodIterator last;
4315
4316 do {
4317 *num_claimed_nmethods = 0;
4318
4319 first = (nmethod*)_claimed_nmethod;
4320 last = NMethodIterator(first);
4321
4322 if (first != NULL) {
4323
4324 for (int i = 0; i < MaxClaimNmethods; i++) {
4325 if (!last.next_alive()) {
4326 break;
4327 }
4328 claimed_nmethods[i] = last.method();
4329 (*num_claimed_nmethods)++;
4330 }
4331 }
4332
4333 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4334 }
4335
4336 nmethod* claim_postponed_nmethod() {
4337 nmethod* claim;
4338 nmethod* next;
4339
4340 do {
4341 claim = (nmethod*)_postponed_list;
4342 if (claim == NULL) {
4343 return NULL;
4344 }
4345
4346 next = claim->unloading_next();
4347
4348 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4349
4350 return claim;
4351 }
4352
4353 public:
4354 // Mark that we're done with the first pass of nmethod cleaning.
4355 void barrier_mark(uint worker_id) {
4356 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4357 _num_entered_barrier++;
4358 if (_num_entered_barrier == _num_workers) {
4359 ml.notify_all();
4360 }
4361 }
4362
4363 // See if we have to wait for the other workers to
4364 // finish their first-pass nmethod cleaning work.
4365 void barrier_wait(uint worker_id) {
4366 if (_num_entered_barrier < _num_workers) {
4367 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4368 while (_num_entered_barrier < _num_workers) {
4369 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4370 }
4371 }
4372 }
4373
4374 // Cleaning and unloading of nmethods. Some work has to be postponed
4375 // to the second pass, when we know which nmethods survive.
4376 void work_first_pass(uint worker_id) {
4377 // The first nmethods is claimed by the first worker.
4378 if (worker_id == 0 && _first_nmethod != NULL) {
4379 clean_nmethod(_first_nmethod);
4380 _first_nmethod = NULL;
4381 }
4382
4383 int num_claimed_nmethods;
4384 nmethod* claimed_nmethods[MaxClaimNmethods];
4385
4386 while (true) {
4387 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4388
4389 if (num_claimed_nmethods == 0) {
4390 break;
4391 }
4392
4393 for (int i = 0; i < num_claimed_nmethods; i++) {
4394 clean_nmethod(claimed_nmethods[i]);
4395 }
4396 }
4397 }
4398
4399 void work_second_pass(uint worker_id) {
4400 nmethod* nm;
4401 // Take care of postponed nmethods.
4402 while ((nm = claim_postponed_nmethod()) != NULL) {
4403 clean_nmethod_postponed(nm);
4404 }
4405 }
4406 };
4407
4408 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4409
4410 class G1KlassCleaningTask : public StackObj {
4411 BoolObjectClosure* _is_alive;
4412 volatile jint _clean_klass_tree_claimed;
4413 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4414
4415 public:
4416 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4417 _is_alive(is_alive),
4418 _clean_klass_tree_claimed(0),
4419 _klass_iterator() {
4420 }
4421
4422 private:
4423 bool claim_clean_klass_tree_task() {
4424 if (_clean_klass_tree_claimed) {
4425 return false;
4426 }
4427
4428 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4429 }
4430
4431 InstanceKlass* claim_next_klass() {
4432 Klass* klass;
4433 do {
4434 klass =_klass_iterator.next_klass();
4435 } while (klass != NULL && !klass->is_instance_klass());
4436
4437 // this can be null so don't call InstanceKlass::cast
4438 return static_cast<InstanceKlass*>(klass);
4439 }
4440
4441 public:
4442
4443 void clean_klass(InstanceKlass* ik) {
4444 ik->clean_weak_instanceklass_links(_is_alive);
4445 }
4446
4447 void work() {
4448 ResourceMark rm;
4449
4450 // One worker will clean the subklass/sibling klass tree.
4451 if (claim_clean_klass_tree_task()) {
4452 Klass::clean_subklass_tree(_is_alive);
4453 }
4454
4455 // All workers will help cleaning the classes,
4456 InstanceKlass* klass;
4457 while ((klass = claim_next_klass()) != NULL) {
4458 clean_klass(klass);
4459 }
4460 }
4461 };
4462
4463 // To minimize the remark pause times, the tasks below are done in parallel.
4464 class G1ParallelCleaningTask : public AbstractGangTask {
4465 private:
4466 G1StringSymbolTableUnlinkTask _string_symbol_task;
4467 G1CodeCacheUnloadingTask _code_cache_task;
4468 G1KlassCleaningTask _klass_cleaning_task;
4469
4470 public:
4471 // The constructor is run in the VMThread.
4472 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4473 AbstractGangTask("Parallel Cleaning"),
4474 _string_symbol_task(is_alive, process_strings, process_symbols),
4475 _code_cache_task(num_workers, is_alive, unloading_occurred),
4476 _klass_cleaning_task(is_alive) {
4477 }
4478
4479 // The parallel work done by all worker threads.
4480 void work(uint worker_id) {
4481 // Do first pass of code cache cleaning.
4482 _code_cache_task.work_first_pass(worker_id);
4483
4484 // Let the threads mark that the first pass is done.
4485 _code_cache_task.barrier_mark(worker_id);
4486
4487 // Clean the Strings and Symbols.
4488 _string_symbol_task.work(worker_id);
4489
4490 // Wait for all workers to finish the first code cache cleaning pass.
4491 _code_cache_task.barrier_wait(worker_id);
4492
4493 // Do the second code cache cleaning work, which realize on
4494 // the liveness information gathered during the first pass.
4495 _code_cache_task.work_second_pass(worker_id);
4496
4497 // Clean all klasses that were not unloaded.
4498 _klass_cleaning_task.work();
4499 }
4500 };
4501
4502
4503 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4504 bool process_strings,
4505 bool process_symbols,
4506 bool class_unloading_occurred) {
4507 uint n_workers = workers()->active_workers();
4508
4509 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4510 n_workers, class_unloading_occurred);
4511 workers()->run_task(&g1_unlink_task);
4512 }
4513
4514 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4515 bool process_strings, bool process_symbols) {
4516 {
4517 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4518 workers()->run_task(&g1_unlink_task);
4519 }
4520
4521 if (G1StringDedup::is_enabled()) {
4522 G1StringDedup::unlink(is_alive);
4523 }
4524 }
4525
4526 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4527 private:
4528 DirtyCardQueueSet* _queue;
4529 public:
4530 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4531
4532 virtual void work(uint worker_id) {
4533 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4534 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4535
4536 RedirtyLoggedCardTableEntryClosure cl;
4537 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4538
4539 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4540 }
4541 };
4542
4543 void G1CollectedHeap::redirty_logged_cards() {
4544 double redirty_logged_cards_start = os::elapsedTime();
4545
4546 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4547 dirty_card_queue_set().reset_for_par_iteration();
4548 workers()->run_task(&redirty_task);
4549
4550 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4551 dcq.merge_bufferlists(&dirty_card_queue_set());
4552 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4553
4554 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4555 }
4556
4557 // Weak Reference Processing support
4558
4559 // An always "is_alive" closure that is used to preserve referents.
4560 // If the object is non-null then it's alive. Used in the preservation
4561 // of referent objects that are pointed to by reference objects
4562 // discovered by the CM ref processor.
4563 class G1AlwaysAliveClosure: public BoolObjectClosure {
4564 G1CollectedHeap* _g1;
4565 public:
4566 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4567 bool do_object_b(oop p) {
4568 if (p != NULL) {
4569 return true;
4570 }
4571 return false;
4572 }
4573 };
4574
4575 bool G1STWIsAliveClosure::do_object_b(oop p) {
4576 // An object is reachable if it is outside the collection set,
4577 // or is inside and copied.
4578 return !_g1->is_in_cset(p) || p->is_forwarded();
4579 }
4580
4581 // Non Copying Keep Alive closure
4582 class G1KeepAliveClosure: public OopClosure {
4583 G1CollectedHeap* _g1;
4584 public:
4585 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4586 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4587 void do_oop(oop* p) {
4588 oop obj = *p;
4589 assert(obj != NULL, "the caller should have filtered out NULL values");
4590
4591 const InCSetState cset_state = _g1->in_cset_state(obj);
4592 if (!cset_state.is_in_cset_or_humongous()) {
4593 return;
4594 }
4595 if (cset_state.is_in_cset()) {
4596 assert( obj->is_forwarded(), "invariant" );
4597 *p = obj->forwardee();
4598 } else {
4599 assert(!obj->is_forwarded(), "invariant" );
4600 assert(cset_state.is_humongous(),
4601 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4602 _g1->set_humongous_is_live(obj);
4603 }
4604 }
4605 };
4606
4607 // Copying Keep Alive closure - can be called from both
4608 // serial and parallel code as long as different worker
4609 // threads utilize different G1ParScanThreadState instances
4610 // and different queues.
4611
4612 class G1CopyingKeepAliveClosure: public OopClosure {
4613 G1CollectedHeap* _g1h;
4614 OopClosure* _copy_non_heap_obj_cl;
4615 G1ParScanThreadState* _par_scan_state;
4616
4617 public:
4618 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4619 OopClosure* non_heap_obj_cl,
4620 G1ParScanThreadState* pss):
4621 _g1h(g1h),
4622 _copy_non_heap_obj_cl(non_heap_obj_cl),
4623 _par_scan_state(pss)
4624 {}
4625
4626 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4627 virtual void do_oop( oop* p) { do_oop_work(p); }
4628
4629 template <class T> void do_oop_work(T* p) {
4630 oop obj = oopDesc::load_decode_heap_oop(p);
4631
4632 if (_g1h->is_in_cset_or_humongous(obj)) {
4633 // If the referent object has been forwarded (either copied
4634 // to a new location or to itself in the event of an
4635 // evacuation failure) then we need to update the reference
4636 // field and, if both reference and referent are in the G1
4637 // heap, update the RSet for the referent.
4638 //
4639 // If the referent has not been forwarded then we have to keep
4640 // it alive by policy. Therefore we have copy the referent.
4641 //
4642 // If the reference field is in the G1 heap then we can push
4643 // on the PSS queue. When the queue is drained (after each
4644 // phase of reference processing) the object and it's followers
4645 // will be copied, the reference field set to point to the
4646 // new location, and the RSet updated. Otherwise we need to
4647 // use the the non-heap or metadata closures directly to copy
4648 // the referent object and update the pointer, while avoiding
4649 // updating the RSet.
4650
4651 if (_g1h->is_in_g1_reserved(p)) {
4652 _par_scan_state->push_on_queue(p);
4653 } else {
4654 assert(!Metaspace::contains((const void*)p),
4655 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4656 _copy_non_heap_obj_cl->do_oop(p);
4657 }
4658 }
4659 }
4660 };
4661
4662 // Serial drain queue closure. Called as the 'complete_gc'
4663 // closure for each discovered list in some of the
4664 // reference processing phases.
4665
4666 class G1STWDrainQueueClosure: public VoidClosure {
4667 protected:
4668 G1CollectedHeap* _g1h;
4669 G1ParScanThreadState* _par_scan_state;
4670
4671 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4672
4673 public:
4674 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4675 _g1h(g1h),
4676 _par_scan_state(pss)
4677 { }
4678
4679 void do_void() {
4680 G1ParScanThreadState* const pss = par_scan_state();
4681 pss->trim_queue();
4682 }
4683 };
4684
4685 // Parallel Reference Processing closures
4686
4687 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4688 // processing during G1 evacuation pauses.
4689
4690 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4691 private:
4692 G1CollectedHeap* _g1h;
4693 G1ParScanThreadStateSet* _pss;
4694 RefToScanQueueSet* _queues;
4695 WorkGang* _workers;
4696 uint _active_workers;
4697
4698 public:
4699 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4700 G1ParScanThreadStateSet* per_thread_states,
4701 WorkGang* workers,
4702 RefToScanQueueSet *task_queues,
4703 uint n_workers) :
4704 _g1h(g1h),
4705 _pss(per_thread_states),
4706 _queues(task_queues),
4707 _workers(workers),
4708 _active_workers(n_workers)
4709 {
4710 assert(n_workers > 0, "shouldn't call this otherwise");
4711 }
4712
4713 // Executes the given task using concurrent marking worker threads.
4714 virtual void execute(ProcessTask& task);
4715 virtual void execute(EnqueueTask& task);
4716 };
4717
4718 // Gang task for possibly parallel reference processing
4719
4720 class G1STWRefProcTaskProxy: public AbstractGangTask {
4721 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4722 ProcessTask& _proc_task;
4723 G1CollectedHeap* _g1h;
4724 G1ParScanThreadStateSet* _pss;
4725 RefToScanQueueSet* _task_queues;
4726 ParallelTaskTerminator* _terminator;
4727
4728 public:
4729 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4730 G1CollectedHeap* g1h,
4731 G1ParScanThreadStateSet* per_thread_states,
4732 RefToScanQueueSet *task_queues,
4733 ParallelTaskTerminator* terminator) :
4734 AbstractGangTask("Process reference objects in parallel"),
4735 _proc_task(proc_task),
4736 _g1h(g1h),
4737 _pss(per_thread_states),
4738 _task_queues(task_queues),
4739 _terminator(terminator)
4740 {}
4741
4742 virtual void work(uint worker_id) {
4743 // The reference processing task executed by a single worker.
4744 ResourceMark rm;
4745 HandleMark hm;
4746
4747 G1STWIsAliveClosure is_alive(_g1h);
4748
4749 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4750 pss->set_ref_processor(NULL);
4751
4752 // Keep alive closure.
4753 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4754
4755 // Complete GC closure
4756 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4757
4758 // Call the reference processing task's work routine.
4759 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4760
4761 // Note we cannot assert that the refs array is empty here as not all
4762 // of the processing tasks (specifically phase2 - pp2_work) execute
4763 // the complete_gc closure (which ordinarily would drain the queue) so
4764 // the queue may not be empty.
4765 }
4766 };
4767
4768 // Driver routine for parallel reference processing.
4769 // Creates an instance of the ref processing gang
4770 // task and has the worker threads execute it.
4771 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4772 assert(_workers != NULL, "Need parallel worker threads.");
4773
4774 ParallelTaskTerminator terminator(_active_workers, _queues);
4775 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4776
4777 _workers->run_task(&proc_task_proxy);
4778 }
4779
4780 // Gang task for parallel reference enqueueing.
4781
4782 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4783 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4784 EnqueueTask& _enq_task;
4785
4786 public:
4787 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4788 AbstractGangTask("Enqueue reference objects in parallel"),
4789 _enq_task(enq_task)
4790 { }
4791
4792 virtual void work(uint worker_id) {
4793 _enq_task.work(worker_id);
4794 }
4795 };
4796
4797 // Driver routine for parallel reference enqueueing.
4798 // Creates an instance of the ref enqueueing gang
4799 // task and has the worker threads execute it.
4800
4801 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4802 assert(_workers != NULL, "Need parallel worker threads.");
4803
4804 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4805
4806 _workers->run_task(&enq_task_proxy);
4807 }
4808
4809 // End of weak reference support closures
4810
4811 // Abstract task used to preserve (i.e. copy) any referent objects
4812 // that are in the collection set and are pointed to by reference
4813 // objects discovered by the CM ref processor.
4814
4815 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4816 protected:
4817 G1CollectedHeap* _g1h;
4818 G1ParScanThreadStateSet* _pss;
4819 RefToScanQueueSet* _queues;
4820 ParallelTaskTerminator _terminator;
4821 uint _n_workers;
4822
4823 public:
4824 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4825 AbstractGangTask("ParPreserveCMReferents"),
4826 _g1h(g1h),
4827 _pss(per_thread_states),
4828 _queues(task_queues),
4829 _terminator(workers, _queues),
4830 _n_workers(workers)
4831 { }
4832
4833 void work(uint worker_id) {
4834 ResourceMark rm;
4835 HandleMark hm;
4836
4837 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4838 pss->set_ref_processor(NULL);
4839 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4840
4841 // Is alive closure
4842 G1AlwaysAliveClosure always_alive(_g1h);
4843
4844 // Copying keep alive closure. Applied to referent objects that need
4845 // to be copied.
4846 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4847
4848 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4849
4850 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4851 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4852
4853 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4854 // So this must be true - but assert just in case someone decides to
4855 // change the worker ids.
4856 assert(worker_id < limit, "sanity");
4857 assert(!rp->discovery_is_atomic(), "check this code");
4858
4859 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4860 for (uint idx = worker_id; idx < limit; idx += stride) {
4861 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4862
4863 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4864 while (iter.has_next()) {
4865 // Since discovery is not atomic for the CM ref processor, we
4866 // can see some null referent objects.
4867 iter.load_ptrs(DEBUG_ONLY(true));
4868 oop ref = iter.obj();
4869
4870 // This will filter nulls.
4871 if (iter.is_referent_alive()) {
4872 iter.make_referent_alive();
4873 }
4874 iter.move_to_next();
4875 }
4876 }
4877
4878 // Drain the queue - which may cause stealing
4879 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4880 drain_queue.do_void();
4881 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4882 assert(pss->queue_is_empty(), "should be");
4883 }
4884 };
4885
4886 // Weak Reference processing during an evacuation pause (part 1).
4887 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4888 double ref_proc_start = os::elapsedTime();
4889
4890 ReferenceProcessor* rp = _ref_processor_stw;
4891 assert(rp->discovery_enabled(), "should have been enabled");
4892
4893 // Any reference objects, in the collection set, that were 'discovered'
4894 // by the CM ref processor should have already been copied (either by
4895 // applying the external root copy closure to the discovered lists, or
4896 // by following an RSet entry).
4897 //
4898 // But some of the referents, that are in the collection set, that these
4899 // reference objects point to may not have been copied: the STW ref
4900 // processor would have seen that the reference object had already
4901 // been 'discovered' and would have skipped discovering the reference,
4902 // but would not have treated the reference object as a regular oop.
4903 // As a result the copy closure would not have been applied to the
4904 // referent object.
4905 //
4906 // We need to explicitly copy these referent objects - the references
4907 // will be processed at the end of remarking.
4908 //
4909 // We also need to do this copying before we process the reference
4910 // objects discovered by the STW ref processor in case one of these
4911 // referents points to another object which is also referenced by an
4912 // object discovered by the STW ref processor.
4913
4914 uint no_of_gc_workers = workers()->active_workers();
4915
4916 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4917 per_thread_states,
4918 no_of_gc_workers,
4919 _task_queues);
4920
4921 workers()->run_task(&keep_cm_referents);
4922
4923 // Closure to test whether a referent is alive.
4924 G1STWIsAliveClosure is_alive(this);
4925
4926 // Even when parallel reference processing is enabled, the processing
4927 // of JNI refs is serial and performed serially by the current thread
4928 // rather than by a worker. The following PSS will be used for processing
4929 // JNI refs.
4930
4931 // Use only a single queue for this PSS.
4932 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4933 pss->set_ref_processor(NULL);
4934 assert(pss->queue_is_empty(), "pre-condition");
4935
4936 // Keep alive closure.
4937 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4938
4939 // Serial Complete GC closure
4940 G1STWDrainQueueClosure drain_queue(this, pss);
4941
4942 // Setup the soft refs policy...
4943 rp->setup_policy(false);
4944
4945 ReferenceProcessorStats stats;
4946 if (!rp->processing_is_mt()) {
4947 // Serial reference processing...
4948 stats = rp->process_discovered_references(&is_alive,
4949 &keep_alive,
4950 &drain_queue,
4951 NULL,
4952 _gc_timer_stw);
4953 } else {
4954 // Parallel reference processing
4955 assert(rp->num_q() == no_of_gc_workers, "sanity");
4956 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4957
4958 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4959 stats = rp->process_discovered_references(&is_alive,
4960 &keep_alive,
4961 &drain_queue,
4962 &par_task_executor,
4963 _gc_timer_stw);
4964 }
4965
4966 _gc_tracer_stw->report_gc_reference_stats(stats);
4967
4968 // We have completed copying any necessary live referent objects.
4969 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4970
4971 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4972 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4973 }
4974
4975 // Weak Reference processing during an evacuation pause (part 2).
4976 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4977 double ref_enq_start = os::elapsedTime();
4978
4979 ReferenceProcessor* rp = _ref_processor_stw;
4980 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4981
4982 // Now enqueue any remaining on the discovered lists on to
4983 // the pending list.
4984 if (!rp->processing_is_mt()) {
4985 // Serial reference processing...
4986 rp->enqueue_discovered_references();
4987 } else {
4988 // Parallel reference enqueueing
4989
4990 uint n_workers = workers()->active_workers();
4991
4992 assert(rp->num_q() == n_workers, "sanity");
4993 assert(n_workers <= rp->max_num_q(), "sanity");
4994
4995 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4996 rp->enqueue_discovered_references(&par_task_executor);
4997 }
4998
4999 rp->verify_no_references_recorded();
5000 assert(!rp->discovery_enabled(), "should have been disabled");
5001
5002 // FIXME
5003 // CM's reference processing also cleans up the string and symbol tables.
5004 // Should we do that here also? We could, but it is a serial operation
5005 // and could significantly increase the pause time.
5006
5007 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5008 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5009 }
5010
5011 void G1CollectedHeap::pre_evacuate_collection_set() {
5012 _expand_heap_after_alloc_failure = true;
5013 _evacuation_failed = false;
5014
5015 // Disable the hot card cache.
5016 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5017 hot_card_cache->reset_hot_cache_claimed_index();
5018 hot_card_cache->set_use_cache(false);
5019
5020 }
5021
5022 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5023 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5024
5025 // Should G1EvacuationFailureALot be in effect for this GC?
5026 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5027
5028 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5029 double start_par_time_sec = os::elapsedTime();
5030 double end_par_time_sec;
5031
5032 {
5033 const uint n_workers = workers()->active_workers();
5034 G1RootProcessor root_processor(this, n_workers);
5035 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5036 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5037 if (collector_state()->during_initial_mark_pause()) {
5038 ClassLoaderDataGraph::clear_claimed_marks();
5039 }
5040
5041 print_termination_stats_hdr();
5042
5043 workers()->run_task(&g1_par_task);
5044 end_par_time_sec = os::elapsedTime();
5045
5046 // Closing the inner scope will execute the destructor
5047 // for the G1RootProcessor object. We record the current
5048 // elapsed time before closing the scope so that time
5049 // taken for the destructor is NOT included in the
5050 // reported parallel time.
5051 }
5052
5053 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5054
5055 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5056 phase_times->record_par_time(par_time_ms);
5057
5058 double code_root_fixup_time_ms =
5059 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5060 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5061
5062 // Process any discovered reference objects - we have
5063 // to do this _before_ we retire the GC alloc regions
5064 // as we may have to copy some 'reachable' referent
5065 // objects (and their reachable sub-graphs) that were
5066 // not copied during the pause.
5067 process_discovered_references(per_thread_states);
5068
5069 if (G1StringDedup::is_enabled()) {
5070 double fixup_start = os::elapsedTime();
5071
5072 G1STWIsAliveClosure is_alive(this);
5073 G1KeepAliveClosure keep_alive(this);
5074 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5075
5076 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5077 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5078 }
5079
5080 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5081
5082 if (evacuation_failed()) {
5083 remove_self_forwarding_pointers();
5084
5085 // Reset the G1EvacuationFailureALot counters and flags
5086 // Note: the values are reset only when an actual
5087 // evacuation failure occurs.
5088 NOT_PRODUCT(reset_evacuation_should_fail();)
5089 }
5090
5091 // Enqueue any remaining references remaining on the STW
5092 // reference processor's discovered lists. We need to do
5093 // this after the card table is cleaned (and verified) as
5094 // the act of enqueueing entries on to the pending list
5095 // will log these updates (and dirty their associated
5096 // cards). We need these updates logged to update any
5097 // RSets.
5098 enqueue_discovered_references(per_thread_states);
5099 }
5100
5101 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5102 _allocator->release_gc_alloc_regions(evacuation_info);
5103
5104 per_thread_states->flush();
5105
5106 record_obj_copy_mem_stats();
5107
5108 // Reset and re-enable the hot card cache.
5109 // Note the counts for the cards in the regions in the
5110 // collection set are reset when the collection set is freed.
5111 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5112 hot_card_cache->reset_hot_cache();
5113 hot_card_cache->set_use_cache(true);
5114
5115 purge_code_root_memory();
5116
5117 redirty_logged_cards();
5118 #if defined(COMPILER2) || INCLUDE_JVMCI
5119 DerivedPointerTable::update_pointers();
5120 #endif
5121 }
5122
5123 void G1CollectedHeap::record_obj_copy_mem_stats() {
5124 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5125 create_g1_evac_summary(&_old_evac_stats));
5126 }
5127
5128 void G1CollectedHeap::free_region(HeapRegion* hr,
5129 FreeRegionList* free_list,
5130 bool par,
5131 bool locked) {
5132 assert(!hr->is_free(), "the region should not be free");
5133 assert(!hr->is_empty(), "the region should not be empty");
5134 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5135 assert(free_list != NULL, "pre-condition");
5136
5137 if (G1VerifyBitmaps) {
5138 MemRegion mr(hr->bottom(), hr->end());
5139 concurrent_mark()->clearRangePrevBitmap(mr);
5140 }
5141
5142 // Clear the card counts for this region.
5143 // Note: we only need to do this if the region is not young
5144 // (since we don't refine cards in young regions).
5145 if (!hr->is_young()) {
5146 _cg1r->hot_card_cache()->reset_card_counts(hr);
5147 }
5148 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5149 free_list->add_ordered(hr);
5150 }
5151
5152 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5153 FreeRegionList* free_list,
5154 bool par) {
5155 assert(hr->is_humongous(), "this is only for humongous regions");
5156 assert(free_list != NULL, "pre-condition");
5157 hr->clear_humongous();
5158 free_region(hr, free_list, par);
5159 }
5160
5161 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5162 const HeapRegionSetCount& humongous_regions_removed) {
5163 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5164 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5165 _old_set.bulk_remove(old_regions_removed);
5166 _humongous_set.bulk_remove(humongous_regions_removed);
5167 }
5168
5169 }
5170
5171 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5172 assert(list != NULL, "list can't be null");
5173 if (!list->is_empty()) {
5174 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5175 _hrm.insert_list_into_free_list(list);
5176 }
5177 }
5178
5179 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5180 decrease_used(bytes);
5181 }
5182
5183 class G1ParCleanupCTTask : public AbstractGangTask {
5184 G1SATBCardTableModRefBS* _ct_bs;
5185 G1CollectedHeap* _g1h;
5186 HeapRegion* volatile _su_head;
5187 public:
5188 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5189 G1CollectedHeap* g1h) :
5190 AbstractGangTask("G1 Par Cleanup CT Task"),
5191 _ct_bs(ct_bs), _g1h(g1h) { }
5192
5193 void work(uint worker_id) {
5194 HeapRegion* r;
5195 while (r = _g1h->pop_dirty_cards_region()) {
5196 clear_cards(r);
5197 }
5198 }
5199
5200 void clear_cards(HeapRegion* r) {
5201 // Cards of the survivors should have already been dirtied.
5202 if (!r->is_survivor()) {
5203 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5204 }
5205 }
5206 };
5207
5208 #ifndef PRODUCT
5209 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5210 G1CollectedHeap* _g1h;
5211 G1SATBCardTableModRefBS* _ct_bs;
5212 public:
5213 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5214 : _g1h(g1h), _ct_bs(ct_bs) { }
5215 virtual bool doHeapRegion(HeapRegion* r) {
5216 if (r->is_survivor()) {
5217 _g1h->verify_dirty_region(r);
5218 } else {
5219 _g1h->verify_not_dirty_region(r);
5220 }
5221 return false;
5222 }
5223 };
5224
5225 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5226 // All of the region should be clean.
5227 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5228 MemRegion mr(hr->bottom(), hr->end());
5229 ct_bs->verify_not_dirty_region(mr);
5230 }
5231
5232 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5233 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5234 // dirty allocated blocks as they allocate them. The thread that
5235 // retires each region and replaces it with a new one will do a
5236 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5237 // not dirty that area (one less thing to have to do while holding
5238 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5239 // is dirty.
5240 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5241 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5242 if (hr->is_young()) {
5243 ct_bs->verify_g1_young_region(mr);
5244 } else {
5245 ct_bs->verify_dirty_region(mr);
5246 }
5247 }
5248
5249 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5250 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5251 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5252 verify_dirty_region(hr);
5253 }
5254 }
5255
5256 void G1CollectedHeap::verify_dirty_young_regions() {
5257 verify_dirty_young_list(_young_list->first_region());
5258 }
5259
5260 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5261 HeapWord* tams, HeapWord* end) {
5262 guarantee(tams <= end,
5263 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5264 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5265 if (result < end) {
5266 log_info(gc, verify)("## wrong marked address on %s bitmap: " PTR_FORMAT, bitmap_name, p2i(result));
5267 log_info(gc, verify)("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, bitmap_name, p2i(tams), p2i(end));
5268 return false;
5269 }
5270 return true;
5271 }
5272
5273 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5274 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5275 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5276
5277 HeapWord* bottom = hr->bottom();
5278 HeapWord* ptams = hr->prev_top_at_mark_start();
5279 HeapWord* ntams = hr->next_top_at_mark_start();
5280 HeapWord* end = hr->end();
5281
5282 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5283
5284 bool res_n = true;
5285 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5286 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5287 // if we happen to be in that state.
5288 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5289 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5290 }
5291 if (!res_p || !res_n) {
5292 log_info(gc, verify)("#### Bitmap verification failed for " HR_FORMAT, HR_FORMAT_PARAMS(hr));
5293 log_info(gc, verify)("#### Caller: %s", caller);
5294 return false;
5295 }
5296 return true;
5297 }
5298
5299 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5300 if (!G1VerifyBitmaps) return;
5301
5302 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5303 }
5304
5305 class G1VerifyBitmapClosure : public HeapRegionClosure {
5306 private:
5307 const char* _caller;
5308 G1CollectedHeap* _g1h;
5309 bool _failures;
5310
5311 public:
5312 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5313 _caller(caller), _g1h(g1h), _failures(false) { }
5314
5315 bool failures() { return _failures; }
5316
5317 virtual bool doHeapRegion(HeapRegion* hr) {
5318 bool result = _g1h->verify_bitmaps(_caller, hr);
5319 if (!result) {
5320 _failures = true;
5321 }
5322 return false;
5323 }
5324 };
5325
5326 void G1CollectedHeap::check_bitmaps(const char* caller) {
5327 if (!G1VerifyBitmaps) return;
5328
5329 G1VerifyBitmapClosure cl(caller, this);
5330 heap_region_iterate(&cl);
5331 guarantee(!cl.failures(), "bitmap verification");
5332 }
5333
5334 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5335 private:
5336 bool _failures;
5337 public:
5338 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5339
5340 virtual bool doHeapRegion(HeapRegion* hr) {
5341 uint i = hr->hrm_index();
5342 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5343 if (hr->is_humongous()) {
5344 if (hr->in_collection_set()) {
5345 log_info(gc, verify)("\n## humongous region %u in CSet", i);
5346 _failures = true;
5347 return true;
5348 }
5349 if (cset_state.is_in_cset()) {
5350 log_info(gc, verify)("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5351 _failures = true;
5352 return true;
5353 }
5354 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5355 log_info(gc, verify)("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5356 _failures = true;
5357 return true;
5358 }
5359 } else {
5360 if (cset_state.is_humongous()) {
5361 log_info(gc, verify)("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5362 _failures = true;
5363 return true;
5364 }
5365 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5366 log_info(gc, verify)("\n## in CSet %d / cset state %d inconsistency for region %u",
5367 hr->in_collection_set(), cset_state.value(), i);
5368 _failures = true;
5369 return true;
5370 }
5371 if (cset_state.is_in_cset()) {
5372 if (hr->is_young() != (cset_state.is_young())) {
5373 log_info(gc, verify)("\n## is_young %d / cset state %d inconsistency for region %u",
5374 hr->is_young(), cset_state.value(), i);
5375 _failures = true;
5376 return true;
5377 }
5378 if (hr->is_old() != (cset_state.is_old())) {
5379 log_info(gc, verify)("\n## is_old %d / cset state %d inconsistency for region %u",
5380 hr->is_old(), cset_state.value(), i);
5381 _failures = true;
5382 return true;
5383 }
5384 }
5385 }
5386 return false;
5387 }
5388
5389 bool failures() const { return _failures; }
5390 };
5391
5392 bool G1CollectedHeap::check_cset_fast_test() {
5393 G1CheckCSetFastTableClosure cl;
5394 _hrm.iterate(&cl);
5395 return !cl.failures();
5396 }
5397 #endif // PRODUCT
5398
5399 void G1CollectedHeap::cleanUpCardTable() {
5400 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5401 double start = os::elapsedTime();
5402
5403 {
5404 // Iterate over the dirty cards region list.
5405 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5406
5407 workers()->run_task(&cleanup_task);
5408 #ifndef PRODUCT
5409 if (G1VerifyCTCleanup || VerifyAfterGC) {
5410 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5411 heap_region_iterate(&cleanup_verifier);
5412 }
5413 #endif
5414 }
5415
5416 double elapsed = os::elapsedTime() - start;
5417 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5418 }
5419
5420 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5421 size_t pre_used = 0;
5422 FreeRegionList local_free_list("Local List for CSet Freeing");
5423
5424 double young_time_ms = 0.0;
5425 double non_young_time_ms = 0.0;
5426
5427 // Since the collection set is a superset of the the young list,
5428 // all we need to do to clear the young list is clear its
5429 // head and length, and unlink any young regions in the code below
5430 _young_list->clear();
5431
5432 G1CollectorPolicy* policy = g1_policy();
5433
5434 double start_sec = os::elapsedTime();
5435 bool non_young = true;
5436
5437 HeapRegion* cur = cs_head;
5438 int age_bound = -1;
5439 size_t rs_lengths = 0;
5440
5441 while (cur != NULL) {
5442 assert(!is_on_master_free_list(cur), "sanity");
5443 if (non_young) {
5444 if (cur->is_young()) {
5445 double end_sec = os::elapsedTime();
5446 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5447 non_young_time_ms += elapsed_ms;
5448
5449 start_sec = os::elapsedTime();
5450 non_young = false;
5451 }
5452 } else {
5453 if (!cur->is_young()) {
5454 double end_sec = os::elapsedTime();
5455 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5456 young_time_ms += elapsed_ms;
5457
5458 start_sec = os::elapsedTime();
5459 non_young = true;
5460 }
5461 }
5462
5463 rs_lengths += cur->rem_set()->occupied_locked();
5464
5465 HeapRegion* next = cur->next_in_collection_set();
5466 assert(cur->in_collection_set(), "bad CS");
5467 cur->set_next_in_collection_set(NULL);
5468 clear_in_cset(cur);
5469
5470 if (cur->is_young()) {
5471 int index = cur->young_index_in_cset();
5472 assert(index != -1, "invariant");
5473 assert((uint) index < policy->young_cset_region_length(), "invariant");
5474 size_t words_survived = surviving_young_words[index];
5475 cur->record_surv_words_in_group(words_survived);
5476
5477 // At this point the we have 'popped' cur from the collection set
5478 // (linked via next_in_collection_set()) but it is still in the
5479 // young list (linked via next_young_region()). Clear the
5480 // _next_young_region field.
5481 cur->set_next_young_region(NULL);
5482 } else {
5483 int index = cur->young_index_in_cset();
5484 assert(index == -1, "invariant");
5485 }
5486
5487 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5488 (!cur->is_young() && cur->young_index_in_cset() == -1),
5489 "invariant" );
5490
5491 if (!cur->evacuation_failed()) {
5492 MemRegion used_mr = cur->used_region();
5493
5494 // And the region is empty.
5495 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5496 pre_used += cur->used();
5497 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5498 } else {
5499 cur->uninstall_surv_rate_group();
5500 if (cur->is_young()) {
5501 cur->set_young_index_in_cset(-1);
5502 }
5503 cur->set_evacuation_failed(false);
5504 // The region is now considered to be old.
5505 cur->set_old();
5506 // Do some allocation statistics accounting. Regions that failed evacuation
5507 // are always made old, so there is no need to update anything in the young
5508 // gen statistics, but we need to update old gen statistics.
5509 size_t used_words = cur->marked_bytes() / HeapWordSize;
5510 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5511 _old_set.add(cur);
5512 evacuation_info.increment_collectionset_used_after(cur->used());
5513 }
5514 cur = next;
5515 }
5516
5517 evacuation_info.set_regions_freed(local_free_list.length());
5518 policy->record_max_rs_lengths(rs_lengths);
5519 policy->cset_regions_freed();
5520
5521 double end_sec = os::elapsedTime();
5522 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5523
5524 if (non_young) {
5525 non_young_time_ms += elapsed_ms;
5526 } else {
5527 young_time_ms += elapsed_ms;
5528 }
5529
5530 prepend_to_freelist(&local_free_list);
5531 decrement_summary_bytes(pre_used);
5532 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5533 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5534 }
5535
5536 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5537 private:
5538 FreeRegionList* _free_region_list;
5539 HeapRegionSet* _proxy_set;
5540 HeapRegionSetCount _humongous_regions_removed;
5541 size_t _freed_bytes;
5542 public:
5543
5544 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5545 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5546 }
5547
5548 virtual bool doHeapRegion(HeapRegion* r) {
5549 if (!r->is_starts_humongous()) {
5550 return false;
5551 }
5552
5553 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5554
5555 oop obj = (oop)r->bottom();
5556 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5557
5558 // The following checks whether the humongous object is live are sufficient.
5559 // The main additional check (in addition to having a reference from the roots
5560 // or the young gen) is whether the humongous object has a remembered set entry.
5561 //
5562 // A humongous object cannot be live if there is no remembered set for it
5563 // because:
5564 // - there can be no references from within humongous starts regions referencing
5565 // the object because we never allocate other objects into them.
5566 // (I.e. there are no intra-region references that may be missed by the
5567 // remembered set)
5568 // - as soon there is a remembered set entry to the humongous starts region
5569 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5570 // until the end of a concurrent mark.
5571 //
5572 // It is not required to check whether the object has been found dead by marking
5573 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5574 // all objects allocated during that time are considered live.
5575 // SATB marking is even more conservative than the remembered set.
5576 // So if at this point in the collection there is no remembered set entry,
5577 // nobody has a reference to it.
5578 // At the start of collection we flush all refinement logs, and remembered sets
5579 // are completely up-to-date wrt to references to the humongous object.
5580 //
5581 // Other implementation considerations:
5582 // - never consider object arrays at this time because they would pose
5583 // considerable effort for cleaning up the the remembered sets. This is
5584 // required because stale remembered sets might reference locations that
5585 // are currently allocated into.
5586 uint region_idx = r->hrm_index();
5587 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5588 !r->rem_set()->is_empty()) {
5589 log_trace(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",
5590 region_idx,
5591 (size_t)obj->size() * HeapWordSize,
5592 p2i(r->bottom()),
5593 r->rem_set()->occupied(),
5594 r->rem_set()->strong_code_roots_list_length(),
5595 next_bitmap->isMarked(r->bottom()),
5596 g1h->is_humongous_reclaim_candidate(region_idx),
5597 obj->is_typeArray()
5598 );
5599 return false;
5600 }
5601
5602 guarantee(obj->is_typeArray(),
5603 "Only eagerly reclaiming type arrays is supported, but the object "
5604 PTR_FORMAT " is not.", p2i(r->bottom()));
5605
5606 log_trace(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",
5607 region_idx,
5608 (size_t)obj->size() * HeapWordSize,
5609 p2i(r->bottom()),
5610 r->rem_set()->occupied(),
5611 r->rem_set()->strong_code_roots_list_length(),
5612 next_bitmap->isMarked(r->bottom()),
5613 g1h->is_humongous_reclaim_candidate(region_idx),
5614 obj->is_typeArray()
5615 );
5616
5617 // Need to clear mark bit of the humongous object if already set.
5618 if (next_bitmap->isMarked(r->bottom())) {
5619 next_bitmap->clear(r->bottom());
5620 }
5621 do {
5622 HeapRegion* next = g1h->next_region_in_humongous(r);
5623 _freed_bytes += r->used();
5624 r->set_containing_set(NULL);
5625 _humongous_regions_removed.increment(1u, r->capacity());
5626 g1h->free_humongous_region(r, _free_region_list, false);
5627 r = next;
5628 } while (r != NULL);
5629
5630 return false;
5631 }
5632
5633 HeapRegionSetCount& humongous_free_count() {
5634 return _humongous_regions_removed;
5635 }
5636
5637 size_t bytes_freed() const {
5638 return _freed_bytes;
5639 }
5640
5641 size_t humongous_reclaimed() const {
5642 return _humongous_regions_removed.length();
5643 }
5644 };
5645
5646 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5647 assert_at_safepoint(true);
5648
5649 if (!G1EagerReclaimHumongousObjects ||
5650 (!_has_humongous_reclaim_candidates && !log_is_enabled(Trace, gc, humongous))) {
5651 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5652 return;
5653 }
5654
5655 double start_time = os::elapsedTime();
5656
5657 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5658
5659 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5660 heap_region_iterate(&cl);
5661
5662 HeapRegionSetCount empty_set;
5663 remove_from_old_sets(empty_set, cl.humongous_free_count());
5664
5665 G1HRPrinter* hrp = hr_printer();
5666 if (hrp->is_active()) {
5667 FreeRegionListIterator iter(&local_cleanup_list);
5668 while (iter.more_available()) {
5669 HeapRegion* hr = iter.get_next();
5670 hrp->cleanup(hr);
5671 }
5672 }
5673
5674 prepend_to_freelist(&local_cleanup_list);
5675 decrement_summary_bytes(cl.bytes_freed());
5676
5677 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5678 cl.humongous_reclaimed());
5679 }
5680
5681 // This routine is similar to the above but does not record
5682 // any policy statistics or update free lists; we are abandoning
5683 // the current incremental collection set in preparation of a
5684 // full collection. After the full GC we will start to build up
5685 // the incremental collection set again.
5686 // This is only called when we're doing a full collection
5687 // and is immediately followed by the tearing down of the young list.
5688
5689 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5690 HeapRegion* cur = cs_head;
5691
5692 while (cur != NULL) {
5693 HeapRegion* next = cur->next_in_collection_set();
5694 assert(cur->in_collection_set(), "bad CS");
5695 cur->set_next_in_collection_set(NULL);
5696 clear_in_cset(cur);
5697 cur->set_young_index_in_cset(-1);
5698 cur = next;
5699 }
5700 }
5701
5702 void G1CollectedHeap::set_free_regions_coming() {
5703 log_develop(gc, freelist)("G1ConcRegionFreeing [cm thread] : "
5704 "setting free regions coming");
5705
5706 assert(!free_regions_coming(), "pre-condition");
5707 _free_regions_coming = true;
5708 }
5709
5710 void G1CollectedHeap::reset_free_regions_coming() {
5711 assert(free_regions_coming(), "pre-condition");
5712
5713 {
5714 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5715 _free_regions_coming = false;
5716 SecondaryFreeList_lock->notify_all();
5717 }
5718
5719 log_develop(gc, freelist)("G1ConcRegionFreeing [cm thread] : "
5720 "reset free regions coming");
5721 }
5722
5723 void G1CollectedHeap::wait_while_free_regions_coming() {
5724 // Most of the time we won't have to wait, so let's do a quick test
5725 // first before we take the lock.
5726 if (!free_regions_coming()) {
5727 return;
5728 }
5729
5730 log_develop(gc, freelist)("G1ConcRegionFreeing [other] : "
5731 "waiting for free regions");
5732
5733 {
5734 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5735 while (free_regions_coming()) {
5736 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5737 }
5738 }
5739
5740 log_develop(gc, freelist)("G1ConcRegionFreeing [other] : "
5741 "done waiting for free regions");
5742 }
5743
5744 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5745 return _allocator->is_retained_old_region(hr);
5746 }
5747
5748 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5749 _young_list->push_region(hr);
5750 }
5751
5752 class NoYoungRegionsClosure: public HeapRegionClosure {
5753 private:
5754 bool _success;
5755 public:
5756 NoYoungRegionsClosure() : _success(true) { }
5757 bool doHeapRegion(HeapRegion* r) {
5758 if (r->is_young()) {
5759 log_info(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5760 p2i(r->bottom()), p2i(r->end()));
5761 _success = false;
5762 }
5763 return false;
5764 }
5765 bool success() { return _success; }
5766 };
5767
5768 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5769 bool ret = _young_list->check_list_empty(check_sample);
5770
5771 if (check_heap) {
5772 NoYoungRegionsClosure closure;
5773 heap_region_iterate(&closure);
5774 ret = ret && closure.success();
5775 }
5776
5777 return ret;
5778 }
5779
5780 class TearDownRegionSetsClosure : public HeapRegionClosure {
5781 private:
5782 HeapRegionSet *_old_set;
5783
5784 public:
5785 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5786
5787 bool doHeapRegion(HeapRegion* r) {
5788 if (r->is_old()) {
5789 _old_set->remove(r);
5790 } else {
5791 // We ignore free regions, we'll empty the free list afterwards.
5792 // We ignore young regions, we'll empty the young list afterwards.
5793 // We ignore humongous regions, we're not tearing down the
5794 // humongous regions set.
5795 assert(r->is_free() || r->is_young() || r->is_humongous(),
5796 "it cannot be another type");
5797 }
5798 return false;
5799 }
5800
5801 ~TearDownRegionSetsClosure() {
5802 assert(_old_set->is_empty(), "post-condition");
5803 }
5804 };
5805
5806 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5807 assert_at_safepoint(true /* should_be_vm_thread */);
5808
5809 if (!free_list_only) {
5810 TearDownRegionSetsClosure cl(&_old_set);
5811 heap_region_iterate(&cl);
5812
5813 // Note that emptying the _young_list is postponed and instead done as
5814 // the first step when rebuilding the regions sets again. The reason for
5815 // this is that during a full GC string deduplication needs to know if
5816 // a collected region was young or old when the full GC was initiated.
5817 }
5818 _hrm.remove_all_free_regions();
5819 }
5820
5821 void G1CollectedHeap::increase_used(size_t bytes) {
5822 _summary_bytes_used += bytes;
5823 }
5824
5825 void G1CollectedHeap::decrease_used(size_t bytes) {
5826 assert(_summary_bytes_used >= bytes,
5827 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5828 _summary_bytes_used, bytes);
5829 _summary_bytes_used -= bytes;
5830 }
5831
5832 void G1CollectedHeap::set_used(size_t bytes) {
5833 _summary_bytes_used = bytes;
5834 }
5835
5836 class RebuildRegionSetsClosure : public HeapRegionClosure {
5837 private:
5838 bool _free_list_only;
5839 HeapRegionSet* _old_set;
5840 HeapRegionManager* _hrm;
5841 size_t _total_used;
5842
5843 public:
5844 RebuildRegionSetsClosure(bool free_list_only,
5845 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5846 _free_list_only(free_list_only),
5847 _old_set(old_set), _hrm(hrm), _total_used(0) {
5848 assert(_hrm->num_free_regions() == 0, "pre-condition");
5849 if (!free_list_only) {
5850 assert(_old_set->is_empty(), "pre-condition");
5851 }
5852 }
5853
5854 bool doHeapRegion(HeapRegion* r) {
5855 if (r->is_empty()) {
5856 // Add free regions to the free list
5857 r->set_free();
5858 r->set_allocation_context(AllocationContext::system());
5859 _hrm->insert_into_free_list(r);
5860 } else if (!_free_list_only) {
5861 assert(!r->is_young(), "we should not come across young regions");
5862
5863 if (r->is_humongous()) {
5864 // We ignore humongous regions. We left the humongous set unchanged.
5865 } else {
5866 // Objects that were compacted would have ended up on regions
5867 // that were previously old or free. Archive regions (which are
5868 // old) will not have been touched.
5869 assert(r->is_free() || r->is_old(), "invariant");
5870 // We now consider them old, so register as such. Leave
5871 // archive regions set that way, however, while still adding
5872 // them to the old set.
5873 if (!r->is_archive()) {
5874 r->set_old();
5875 }
5876 _old_set->add(r);
5877 }
5878 _total_used += r->used();
5879 }
5880
5881 return false;
5882 }
5883
5884 size_t total_used() {
5885 return _total_used;
5886 }
5887 };
5888
5889 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5890 assert_at_safepoint(true /* should_be_vm_thread */);
5891
5892 if (!free_list_only) {
5893 _young_list->empty_list();
5894 }
5895
5896 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5897 heap_region_iterate(&cl);
5898
5899 if (!free_list_only) {
5900 set_used(cl.total_used());
5901 if (_archive_allocator != NULL) {
5902 _archive_allocator->clear_used();
5903 }
5904 }
5905 assert(used_unlocked() == recalculate_used(),
5906 "inconsistent used_unlocked(), "
5907 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5908 used_unlocked(), recalculate_used());
5909 }
5910
5911 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5912 _refine_cte_cl->set_concurrent(concurrent);
5913 }
5914
5915 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5916 HeapRegion* hr = heap_region_containing(p);
5917 return hr->is_in(p);
5918 }
5919
5920 // Methods for the mutator alloc region
5921
5922 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5923 bool force) {
5924 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5925 assert(!force || g1_policy()->can_expand_young_list(),
5926 "if force is true we should be able to expand the young list");
5927 bool young_list_full = g1_policy()->is_young_list_full();
5928 if (force || !young_list_full) {
5929 HeapRegion* new_alloc_region = new_region(word_size,
5930 false /* is_old */,
5931 false /* do_expand */);
5932 if (new_alloc_region != NULL) {
5933 set_region_short_lived_locked(new_alloc_region);
5934 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
5935 check_bitmaps("Mutator Region Allocation", new_alloc_region);
5936 return new_alloc_region;
5937 }
5938 }
5939 return NULL;
5940 }
5941
5942 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5943 size_t allocated_bytes) {
5944 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5945 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5946
5947 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5948 increase_used(allocated_bytes);
5949 _hr_printer.retire(alloc_region);
5950 // We update the eden sizes here, when the region is retired,
5951 // instead of when it's allocated, since this is the point that its
5952 // used space has been recored in _summary_bytes_used.
5953 g1mm()->update_eden_size();
5954 }
5955
5956 // Methods for the GC alloc regions
5957
5958 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5959 uint count,
5960 InCSetState dest) {
5961 assert(FreeList_lock->owned_by_self(), "pre-condition");
5962
5963 if (count < g1_policy()->max_regions(dest)) {
5964 const bool is_survivor = (dest.is_young());
5965 HeapRegion* new_alloc_region = new_region(word_size,
5966 !is_survivor,
5967 true /* do_expand */);
5968 if (new_alloc_region != NULL) {
5969 // We really only need to do this for old regions given that we
5970 // should never scan survivors. But it doesn't hurt to do it
5971 // for survivors too.
5972 new_alloc_region->record_timestamp();
5973 if (is_survivor) {
5974 new_alloc_region->set_survivor();
5975 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
5976 check_bitmaps("Survivor Region Allocation", new_alloc_region);
5977 } else {
5978 new_alloc_region->set_old();
5979 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
5980 check_bitmaps("Old Region Allocation", new_alloc_region);
5981 }
5982 bool during_im = collector_state()->during_initial_mark_pause();
5983 new_alloc_region->note_start_of_copying(during_im);
5984 return new_alloc_region;
5985 }
5986 }
5987 return NULL;
5988 }
5989
5990 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5991 size_t allocated_bytes,
5992 InCSetState dest) {
5993 bool during_im = collector_state()->during_initial_mark_pause();
5994 alloc_region->note_end_of_copying(during_im);
5995 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5996 if (dest.is_young()) {
5997 young_list()->add_survivor_region(alloc_region);
5998 } else {
5999 _old_set.add(alloc_region);
6000 }
6001 _hr_printer.retire(alloc_region);
6002 }
6003
6004 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6005 bool expanded = false;
6006 uint index = _hrm.find_highest_free(&expanded);
6007
6008 if (index != G1_NO_HRM_INDEX) {
6009 if (expanded) {
6010 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
6011 HeapRegion::GrainWords * HeapWordSize);
6012 }
6013 _hrm.allocate_free_regions_starting_at(index, 1);
6014 return region_at(index);
6015 }
6016 return NULL;
6017 }
6018
6019 // Heap region set verification
6020
6021 class VerifyRegionListsClosure : public HeapRegionClosure {
6022 private:
6023 HeapRegionSet* _old_set;
6024 HeapRegionSet* _humongous_set;
6025 HeapRegionManager* _hrm;
6026
6027 public:
6028 HeapRegionSetCount _old_count;
6029 HeapRegionSetCount _humongous_count;
6030 HeapRegionSetCount _free_count;
6031
6032 VerifyRegionListsClosure(HeapRegionSet* old_set,
6033 HeapRegionSet* humongous_set,
6034 HeapRegionManager* hrm) :
6035 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6036 _old_count(), _humongous_count(), _free_count(){ }
6037
6038 bool doHeapRegion(HeapRegion* hr) {
6039 if (hr->is_young()) {
6040 // TODO
6041 } else if (hr->is_humongous()) {
6042 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6043 _humongous_count.increment(1u, hr->capacity());
6044 } else if (hr->is_empty()) {
6045 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6046 _free_count.increment(1u, hr->capacity());
6047 } else if (hr->is_old()) {
6048 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6049 _old_count.increment(1u, hr->capacity());
6050 } else {
6051 // There are no other valid region types. Check for one invalid
6052 // one we can identify: pinned without old or humongous set.
6053 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6054 ShouldNotReachHere();
6055 }
6056 return false;
6057 }
6058
6059 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6060 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6061 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6062 old_set->total_capacity_bytes(), _old_count.capacity());
6063
6064 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6065 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6066 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6067
6068 guarantee(free_list->num_free_regions() == _free_count.length(), "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length());
6069 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6070 free_list->total_capacity_bytes(), _free_count.capacity());
6071 }
6072 };
6073
6074 void G1CollectedHeap::verify_region_sets() {
6075 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6076
6077 // First, check the explicit lists.
6078 _hrm.verify();
6079 {
6080 // Given that a concurrent operation might be adding regions to
6081 // the secondary free list we have to take the lock before
6082 // verifying it.
6083 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6084 _secondary_free_list.verify_list();
6085 }
6086
6087 // If a concurrent region freeing operation is in progress it will
6088 // be difficult to correctly attributed any free regions we come
6089 // across to the correct free list given that they might belong to
6090 // one of several (free_list, secondary_free_list, any local lists,
6091 // etc.). So, if that's the case we will skip the rest of the
6092 // verification operation. Alternatively, waiting for the concurrent
6093 // operation to complete will have a non-trivial effect on the GC's
6094 // operation (no concurrent operation will last longer than the
6095 // interval between two calls to verification) and it might hide
6096 // any issues that we would like to catch during testing.
6097 if (free_regions_coming()) {
6098 return;
6099 }
6100
6101 // Make sure we append the secondary_free_list on the free_list so
6102 // that all free regions we will come across can be safely
6103 // attributed to the free_list.
6104 append_secondary_free_list_if_not_empty_with_lock();
6105
6106 // Finally, make sure that the region accounting in the lists is
6107 // consistent with what we see in the heap.
6108
6109 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6110 heap_region_iterate(&cl);
6111 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6112 }
6113
6114 // Optimized nmethod scanning
6115
6116 class RegisterNMethodOopClosure: public OopClosure {
6117 G1CollectedHeap* _g1h;
6118 nmethod* _nm;
6119
6120 template <class T> void do_oop_work(T* p) {
6121 T heap_oop = oopDesc::load_heap_oop(p);
6122 if (!oopDesc::is_null(heap_oop)) {
6123 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6124 HeapRegion* hr = _g1h->heap_region_containing(obj);
6125 assert(!hr->is_continues_humongous(),
6126 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6127 " starting at " HR_FORMAT,
6128 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6129
6130 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6131 hr->add_strong_code_root_locked(_nm);
6132 }
6133 }
6134
6135 public:
6136 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6137 _g1h(g1h), _nm(nm) {}
6138
6139 void do_oop(oop* p) { do_oop_work(p); }
6140 void do_oop(narrowOop* p) { do_oop_work(p); }
6141 };
6142
6143 class UnregisterNMethodOopClosure: public OopClosure {
6144 G1CollectedHeap* _g1h;
6145 nmethod* _nm;
6146
6147 template <class T> void do_oop_work(T* p) {
6148 T heap_oop = oopDesc::load_heap_oop(p);
6149 if (!oopDesc::is_null(heap_oop)) {
6150 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6151 HeapRegion* hr = _g1h->heap_region_containing(obj);
6152 assert(!hr->is_continues_humongous(),
6153 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6154 " starting at " HR_FORMAT,
6155 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6156
6157 hr->remove_strong_code_root(_nm);
6158 }
6159 }
6160
6161 public:
6162 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6163 _g1h(g1h), _nm(nm) {}
6164
6165 void do_oop(oop* p) { do_oop_work(p); }
6166 void do_oop(narrowOop* p) { do_oop_work(p); }
6167 };
6168
6169 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6170 CollectedHeap::register_nmethod(nm);
6171
6172 guarantee(nm != NULL, "sanity");
6173 RegisterNMethodOopClosure reg_cl(this, nm);
6174 nm->oops_do(®_cl);
6175 }
6176
6177 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6178 CollectedHeap::unregister_nmethod(nm);
6179
6180 guarantee(nm != NULL, "sanity");
6181 UnregisterNMethodOopClosure reg_cl(this, nm);
6182 nm->oops_do(®_cl, true);
6183 }
6184
6185 void G1CollectedHeap::purge_code_root_memory() {
6186 double purge_start = os::elapsedTime();
6187 G1CodeRootSet::purge();
6188 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6189 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6190 }
6191
6192 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6193 G1CollectedHeap* _g1h;
6194
6195 public:
6196 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6197 _g1h(g1h) {}
6198
6199 void do_code_blob(CodeBlob* cb) {
6200 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6201 if (nm == NULL) {
6202 return;
6203 }
6204
6205 if (ScavengeRootsInCode) {
6206 _g1h->register_nmethod(nm);
6207 }
6208 }
6209 };
6210
6211 void G1CollectedHeap::rebuild_strong_code_roots() {
6212 RebuildStrongCodeRootClosure blob_cl(this);
6213 CodeCache::blobs_do(&blob_cl);
6214 }